JP5528520B2 - Polishing apparatus having pressure distribution adjustment function - Google Patents

Description

  The present invention relates to a polishing apparatus having a pressure distribution adjusting function, and in particular, in chemical mechanical polishing (CMP), even when a platen is thermally deformed due to heat generation during polishing, pressure due to the influence of thermal deformation is determined. The present invention relates to a polishing apparatus that minimizes distribution changes.

  In recent years, fine processing of semiconductors has progressed, and a pattern is formed over multiple layers. It is inevitable that a certain degree of unevenness is generated on the surface of the layer on which the pattern is formed. Conventionally, the pattern of the next layer is formed as it is. However, as the number of layers increases and the width of a line or hole decreases, it becomes difficult to form a good pattern, and defects and the like easily occur.

  For this reason, the pattern of the next layer is formed after the surface of the layer on which the pattern is formed is polished and flattened. Thus, in order to polish the surface of a wafer such as a semiconductor, a polishing apparatus using a CMP process is used. This type of CMP polishing apparatus generally has a configuration in which a polishing pad is mounted on a platen and polishing is performed by relatively sliding the wafer and the polishing pad while supplying a slurry.

  In general, as a polishing pad used in a process of flattening a semiconductor wafer or forming a wiring, a polyurethane pad is generally laminated on a nonwoven fabric impregnated with polyurethane.

  In order to polish the surface of the semiconductor wafer flatly, the surface hardness of the polishing pad on the side of polishing the wafer needs to be high. However, when the hardness of the pad is high, it becomes impossible to follow the waviness of the entire wafer, and in particular when the wafer has warpage, it becomes impossible to polish uniformly over the entire surface of the wafer.

  Further, in the construction of the two-layer pad, conventionally, when a polishing process is performed with a pad having a plurality of grooves, a very large amount of slurry is required. This is because the groove needs to fill the abrasive in order to supply the abrasive from the groove. However, as compared with the case where the pad is formed only with holes, the slurry is discharged more and the required amount of slurry is increased. On the other hand, when the pad is formed only with holes, when the wafer is removed from the pad, the wafer is deformed into a sucker shape due to the holes provided in the pad, and a negative pressure is generated between the pad and the wafer. There was a problem that the sticking to the pad occurred and hindered the operation of the device.

  In order to solve such a problem, the hard layer and the soft layer are provided with two layers, and the hard layer is provided with a plurality of holes penetrating therethrough and a polishing surface provided with a plurality of grooves. Pads are known. That is, by forming grooves and a large number of holes in the polishing pad, they are independently displaced, and part of the increase in the contact pressure of the polishing pad with respect to the edge is avoided (see, for example, Patent Document 1).

  There is also provided a polishing pad comprising an elastic sheet having a plurality of protrusions mounted on the upper surface of a table (platen) having a polishing surface, and a polishing pad mounted on the elastic sheet and having a polishing surface on the upper surface. Are known. That is, a space is formed between the polishing pad or the table by a large number of protrusions, and the polishing pad is deformed with good followability by dispersing local pressurization to the surroundings (see, for example, Patent Document 2). ).

  Furthermore, in the publication of Patent Document 3 as a pad-shaped configuration, an elastic body is interposed between the pad and the polishing surface plate. In this known example, if it is a conventional soft polishing cloth, as shown in FIG. 9 of patent document 3, it will contact and deform | transform also into the recessed part of a wafer surface by elastic deformation. For this reason, there has been a problem that the planarization cannot be performed efficiently.

  In addition, when using an extremely hard polishing cloth, there is a problem that it contacts the convex portion of the wafer when viewed macroscopically, and only the macroscopic convex portion is polished, and the entire wafer surface is not polished uniformly. . Therefore, as a polishing device that performs uniform polishing along the shape of the sample surface on a macro scale and improves flatness on a micro scale, the sample contact surface is configured with a hard member attached below it. It is set as the structure provided with the soft member (for example, refer patent document 3).

  Furthermore, in another known example, in the case of the above configuration, depending on the polishing conditions, there was a tendency that polishing on the outer peripheral portion of the wafer progressed faster than the central portion of the wafer. In order to solve such problems and provide a polishing apparatus capable of polishing the entire surface of the wafer constantly and uniformly, a ring-shaped convex body is provided between the polishing surface plate and the elastic body. The convex body is characterized in that the thickness corresponding to the locus of the central portion of the wafer is the thickest and the peripheral portion is the thinnest (see, for example, Patent Document 4).

  Further, in another known example, the surface of the wafer to be flattened is required to be uniformly polished macroscopically over the entire surface of the wafer surface having waviness while flattening the micro unevenness formed on the wafer surface. . In such a problem, in the conventional soft pad, polishing proceeds following the wafer surface, but the micro unevenness cannot be flattened, and in the hard pad, the micro uneven surface is flattened. However, it was impossible to polish uniformly when viewed macroscopically.

  For such problems, by interposing an elastic body between the hard pad and the polishing surface plate, the hard pad acts on the micro to perform flattening, while the macro has an effect of the elastic body. Further, polishing is performed following the surface against macro undulations on the wafer surface (see, for example, Patent Document 5).

  Also, the wafer surface is often polished at different polishing rates, and there is a need to provide the desired flatness and finish when polishing at such different polishing rates. For such needs, it is necessary to have a polishing head capable of polishing a substantially uniform substrate. In response to this problem, an independent chamber is provided in the carrier head that presses the wafer against the pad, and the pressure in the chamber is independently controlled, whereby the pressure applied to the wafer is independently controlled for each region. Attempts have been made to solve the problem (see, for example, Patent Document 6).

  In addition, the top ring that presses the wafer is divided into multiple areas, and the pressure in each area is optimized to correct the non-uniformity of other elements. The structure which tries to obtain is also known (for example, refer patent document 7).

  In addition, when forming a two-layer pad, the surface layer pad swells with slurry and generates wrinkles, so a support layer is provided for the purpose of preventing wrinkles, and a sheet is attached as this support layer. Have been disclosed (for example, see Patent Document 8).

Japanese Patent No. 3042593 JP 2004-160573 A Japanese Patent No. 3024417 (refer to FIG. 9 in particular) Japanese Patent No. 3681226 Japanese Patent No. 3024417 Special table 2001-509440 Japanese Patent No. 3795128 JP-A-10-156705

  The invention described in Patent Document 1 suppresses an increase in the contact pressure of the polishing pad by displacing the polishing pad independently, but in principle, the phenomenon that the wafer itself sinks and bends still remains. For this reason, the neutral surface of the wafer is deformed, the contact pressure at the wafer edge is increased, and the pressure inside the edge is changed. In the case where the neutral surface of the wafer is bent by the polishing load to be applied, the contact pressure applied to the edge is also changed by the wafer load, and a uniform pressure cannot be applied within the wafer surface. In particular, for wafers with large diameters, warpage of the wafer becomes a problem, and when the wafer with warpage is polished while being bent, the contact pressure applied to the edge is particularly synergistic, giving a uniform pressure within the wafer surface. I can't.

  In addition, many holes provided on the surface of the polishing pad are for holding the abrasive supplied onto the polishing pad during polishing, but if polishing debris enters this hole, it is removed by rinsing etc. It is very difficult to do. For example, even if polishing waste comes out from one hole, the polishing waste immediately enters another hole, so that the polishing waste on the polishing pad cannot be washed away cleanly. Therefore, if too many holes are provided on the surface of the polishing pad, polishing debris on the polishing pad will remain, and if the polishing debris remains on the polishing pad for a long time, it will lump and scratch. Cause it to occur.

  The invention described in Patent Document 2 also distributes local pressure by a large number of protrusions provided on the elastic sheet. However, when the flexural rigidity of the polishing pad on the surface layer is weak, the influence of the elastic sheet As a result, the polishing pad sinks and the planarization characteristics deteriorate. Therefore, when the wafer itself sinks and the neutral surface bends, the contact pressure applied to the edge changes as in Patent Document 1, and a uniform pressure cannot be applied within the wafer surface.

  In addition, there have been the following problems. First, when the platen sheet is affixed with a double-sided tape, when the platen sheet is replaced, the pressure distribution applied to the wafer by the polishing pad may change due to the sheet mounting error. When the platen sheet is an elastic body, when it is attached to the platen, the attachment state varies depending on the skill level of the operator, and a stable pressure distribution may not be formed.

  Further, when the polishing pad is completely flat and the wafer is also completely flat, the pressure is not applied evenly. In principle, when a plane-to-plane contact is made, the pressure is not uniformly applied but concentrated on the edge. In order to make the pressure uniform in the plane, it is necessary to form a round shape.

  If the sheet to be attached to the platen is an elastic body with high density, if the elastic body is recessed in some areas, the volume remains constant, and the elastic body becomes convex in other areas due to the Poisson's ratio. . As a result, the pressure distribution varies within the wafer surface, and a uniform pressure cannot be applied within the wafer surface.

  Even if the flexural rigidity of the surface layer of the polishing pad formed in two layers is strong in the dry state, the flexural rigidity is lowered by the penetration of the slurry, and as a result, the flattening characteristics may be deteriorated. Moreover, when dressing the polishing pad, the thickness of the surface layer changes, and the index (Young's modulus x cross-sectional second moment) related to the flexural rigidity changes from the initial state. When the cross section is rectangular, the second moment of the cross section is proportional to the cube of the height (thickness), so the change in thickness due to dressing is extremely large.

  In the invention described in Patent Document 3, a hard pad is used on the surface, an elastic body is interposed between the pad and the polishing surface plate, and the unevenness formed on the wafer surface is flattened so that the entire surface of the wafer is covered. For waviness, a method is shown in which a hard pad on the surface moves up and down on the elastic body to uniformly polish the surface following the surface.

  However, for example, when the initial film thickness is viewed macroscopically, it is formed in a concentric convex or concave shape so that the film thickness distribution seen in the macro after polishing is made uniform by correcting it. Further, there is no disclosure of a polishing method in which the polishing amount between the wafer center and the outer periphery is intentionally changed and corrected.

  Further, the polishing apparatus is not configured for the purpose of correcting the polishing shape on the entire surface of the wafer. Furthermore, if the initial film thickness distribution is not uniform in the wafer film deposition process before the polishing process, and there are several patterns, the film thickness distribution pattern is appropriate depending on the film thickness distribution pattern. The polishing shape cannot be controlled.

  Further, when a hard pad is used on the surface, the hard pad surface needs to contribute to polishing by holding a slurry. However, a hard pad holding slurry indicates that the pad surface is swollen by the slurry. Due to the swelling of the hard pad, the flexural rigidity of the surface layer pad is greatly reduced. As a result, there is a problem in that a stable planarization characteristic cannot be achieved due to a change in the deflection characteristic of the surface layer pad. Further, when the pad is used by dressing, there is a problem that the thickness of the pad is reduced and the rigidity against the bending deformation is changed, and a certain flattening characteristic cannot be achieved.

  Furthermore, in patent document 3, the shape which supported the hard part with the lower soft member is taken. In another embodiment, a groove is formed in a hard pad so that each hard member can be deformed into a caterpillar shape. If it is such a form, for example, when the segmented hard part is supported by the soft member, the lower soft member is deformed laterally by the shearing stress of polishing, and the hard member part on the pad surface is When it is not polished, it will lie down.

  As a result, it becomes difficult to provide a stable pressure distribution. Also, since the pressing force and shear stress of polishing work on the lower soft member at the same time, when using a soft member with the hard part on top, torsional stress acts between the hard part and the soft part, and the interface part Or, there is a concern that the soft member may break.

  In another embodiment, a groove is formed in the pad portion of the hard portion, and the groove portion serves as a fulcrum so that the pad bends. However, even in such a configuration, in the state where compression and shear stress due to polishing work, the torsional stress on the pad described above does not act on the thick hard part, but on the part thinned by the groove. The torsional stress acts intensively.

  As a result, it is conceivable that the thinned groove portion undergoes a fretting phenomenon that is repeatedly subjected to tensile and bending stresses, and is slightly displaced from the underlying elastic body portion. When the hard pad on the surface floats from the elastic material below it, it becomes more susceptible to torsional stress.

  Since the pad subjected to torsional stress deforms itself, it becomes impossible to give a stable pressure distribution to the wafer over a long period of time.

  Thus, in the configuration in which the flexure strength of the pad and the configuration of the pad are not continuous in the pad surface and are segmented, the polishing stress is concentrated on the physically weakest part. It may break from that position.

  Furthermore, when a portion having a high bending rigidity and a portion having a low bending rigidity are mixed in the pad portion on the surface, when a certain bending strength is received, the stress is concentrated and a deformation occurs in the portion having a low bending rigidity. As a result, the plane of the portion where the bending rigidity is strong does not necessarily take a horizontal plane, but is inclined in the stressed direction by the shear stress, and contributes to the polishing in the inclined state. As a result, it is predicted that the flat portion having a high deflection rigidity cannot maintain its own horizontal posture, and as a result, the pressure distribution to the wafer is greatly deteriorated.

  In the case of a configuration in which a hard member is arranged on a soft member, for example, when replacing a pad, the soft member and the hard member are replaced as a set. For example, as in the present invention, according to the initial film thickness distribution, the polishing shape is arbitrarily controlled instead of uniformly polishing so as to make the film thickness distribution after polishing uniform. When it is necessary to adjust the pressure distribution, it is necessary to adjust the pressure distribution every time the pad is replaced.

  For each pad of consumable material, preparing a large number of elastic bodies whose pressure distribution is delicately adjusted is very technically problematic, and the elastic material whose pressure distribution is delicately adjusted is attached to the device. Even in the above, advanced technology is required. For example, if it is simply screwed, the pressure distribution will be affected by the threaded part and the unthreaded part, or even if the entire surface is simply bonded with an adhesive, the elastic body will be stretched or contracted Therefore, there is a problem that the preset pressure distribution cannot always be reflected.

  In this way, when the wafer is not polished uniformly, but the polishing shape is arbitrarily made non-uniform so as to correct the shape according to the film thickness distribution state of the wafer, such a device configuration, and the pad It is self-evident that the purpose cannot be achieved with a configuration.

  In the invention described in Patent Document 4, when there is a tendency that the polishing of the wafer outer peripheral portion proceeds faster than the wafer central portion depending on the polishing conditions, a convex body is sandwiched between the elastic body and the polishing platen, and the center of the wafer Discloses a method of correcting the nonuniformity of polishing due to polishing conditions by increasing the pressure of the portion. However, in this case as well, the content of correcting the shape corresponding to the initial film thickness distribution shape is not disclosed. This is for correcting that the outer peripheral portion of the wafer is polished quickly depending on the polishing conditions, and does not control the polishing shape.

  However, as an extension line of this method, for example, when the polishing recipe is a condition for uniformly polishing, it has the ability to polish the vicinity of the center more than others in the polishing shape by using the convex body Is to be predicted, and this can be regarded as polishing shape control.

  However, even in Patent Document 4, the problem of correcting the polishing shape each time with various initial film thickness shapes is not satisfactory. In the case where the convex body and the elastic body are held between the polishing pad and the polishing surface plate, the convex body and the elastic body on the polishing surface plate are not fixed. Since the elastic body moves in the polishing pad on the elastic body, it is difficult to ensure a stable pressure distribution.

  Further, when not fixed, it is very difficult to form a stable pressure distribution because there is a problem of attachment error particularly in an elastic body.

  When a convex body is fixed on the polishing surface plate and an elastic body is fixed on it, everything is integrated with the polishing surface plate. For example, polishing is performed when the polishing shape is corrected by the initial film thickness. It becomes the form which replaces the whole surface plate. This is a huge effort.

  Furthermore, even if a convex body is sandwiched under the elastic body, for example, in a dense elastic body itself, if a certain part of the elastic body deforms locally, the elastic body tries to keep the volume constant. Bounce occurs in other parts. Therefore, it is theoretically difficult to press the entire surface uniformly.

  In addition, in order to prevent such a situation, if a sponge material that has bubbles (voids) that do not bounce even if the volume changes to some extent, even if one part is locally deformed, the other part Will not be affected by it.

  However, in the sponge material having such bubbles, the volume of the void portion gradually deforms in the polishing process in which repeated pressure is applied. As a result, the pressure distribution in the initial use state of the elastic body and the state in which the elastic body is repeatedly used Naturally, the pressure distribution in the chamber changes. As a result, it is impossible to obtain a constant pressure distribution between the initial and final use of the sponge material, and there is a problem that it is difficult to apply as an elastic material that forms a stable pressure distribution applicable to mass production.

  Furthermore, polishing is performed by placing a polishing pad on the elastic body. For example, when the surface of the elastic body is not processed, it occurs at the interface between the polishing pad on the surface and the elastic body below the surface. It is predicted that the shear stress will cause a shift. If this deviation becomes large, only the pad may be wrinkled due to swelling, and if this is used repeatedly, it is predicted that the pad may break due to the wrinkle.

  In this method, when polishing is performed with a convex body and an elastic body interposed between the polishing pad and the polishing surface plate, the polishing pad on the surface layer contributes to the polishing including the polishing slurry. For example, when a polishing pad such as foamed polyurethane is used, it is very hard in a dry state where it is not polished, and is not easily deformed. However, once the slurry is swelled and swollen, it becomes very deformable. Therefore, the bending deformation of the pad surface changes depending on the state including the slurry.

  Further, the polishing pad is usually subjected to pad dressing, and the pad surface is regenerated and polished. Pad dressing is performed while cutting the pad surface. Therefore, the thickness of the pad decreases with the use of the pad.

  For example, the initial pad thickness is about 1.27 mm, but if it is used, the thickness is reduced by about 0.4 mm to 0.87 mm, and the thickness is reduced to about 2/3. As the pad thickness decreases, the rigidity of the pad against deformation is greatly affected. For example, when the thickness changes to 2/3, the cross-sectional secondary moment when the member is simply bent is proportional to the cube of the thickness, and thus becomes 8/27, which is reduced to about 30%.

  As a result, the ability to flatten the irregularities on the wafer surface changes significantly, and it is difficult to obtain stable flattening characteristics over a long period of time. Here, it is obvious that the bending deformation of the pad greatly affects the flattening of the irregularities on the wafer surface. For example, if the surface layer pad is very hard and an extremely thin pad or a thick pad is assumed, the importance can be easily understood.

  Assuming that a stainless steel pad of 0.01 mm is assumed, in order to compressively deform it, the thickness hardly changes from 0.01 mm. However, since it is very thin, even a hard member pad made of stainless steel can be easily bent. As a result, even if it is a stainless steel pad, the hardness of the underlying elastic body becomes dominant, and it can be easily predicted that the unevenness on the wafer surface cannot be flattened, similar to that processed with a soft member. .

  On the other hand, assuming a very thick 1cm pad as a surface layer pad with a stainless steel pad, no matter how much the base material has an elastic body, the surface layer pad hardly bends. It is easy to understand that flat processing is performed without following the waviness seen in the macro of the wafer, just like polishing with a hard pad (lapping machine) without following. Therefore, the flexural deformation characteristic of the surface layer pad during polishing is an important factor for taking advantage of the characteristics of the elastic body underneath, and must be strictly managed.

In the control of such bending deformation characteristics, in Patent Document 4, foamed polyurethane is used for the surface layer pad. In such a foam polishing pad, it has been difficult to optimize and keep its flexural deformation constant by the following two factors that change accompanying polishing.
・ The foam pad swells and softens due to the slurry,
・ Pad thickness is reduced by pad dressing.

  Furthermore, this method is expected to lack manufacturing stability. That is, even if the convex body is processed with high accuracy and the elastic body is processed with high accuracy, a problem occurs when the both are superposed. In particular, if the convex body and the elastic body are simply placed one on top of the other, a positional deviation or the like occurs each time, so that it is difficult to form a stable pressure distribution. For example, when the elastic body is fixed to the convex body with a screw, for example, the hardness of the elastic body near the screw increases, resulting in a variation in pressure distribution. The shear force causes a deviation between the convex body and the elastic body.

  As a result, concentrated stress acts on the threaded portion, causing problems such as partial breakage of the elastic body near the threaded portion. A problem also arises when the elastic body is attached to a convex plate having a size equivalent to a polishing surface plate by full adhesion or the like. For example, even if an elastic body and a convex body are manufactured with high accuracy, and further, a convex body is manufactured with high accuracy, uneven bonding occurs when both are bonded. In particular, when an elastic body is pasted, a partially stretched part and a contracted part are mixed in the same plane, so that the thickness of the convex body is uniformly in the plane. It is difficult to achieve a corresponding pressure distribution.

  In Patent Document 6, an independent chamber is provided in a carrier head that presses a wafer against a pad, and the pressure applied to the wafer is controlled independently for each region by independently controlling the pressure in the chamber. I am trying to solve the problem.

  However, in such a configuration, pressure is applied from the back side of the wafer and the wafer is pressed against the pad, so the pressure distribution state between the wafer and the pad changes depending on the deflection rigidity of the wafer, so stable pressure distribution control is not necessarily required. There is a problem that does not become.

  For example, in order to form a desired polishing shape, a wafer having a certain thickness is used, and pressure is applied to a chamber existing on the back side of the wafer to deform the flexible film thereon, so that the wafer and the pad are in contact with each other. Assume that the pressure distribution is controlled. Next, assume that another slightly thicker wafer is applied and the same pressure is applied to the chamber as well. In this case, the pressure distribution between the wafer and the pad is completely different. This is because the flexural rigidity of the wafer varies depending on the thickness of the wafer, and therefore when the pressure is transmitted through the wafer, the pressure transmission largely depends on the deflection deformation of the wafer.

  In an extreme case, assuming that the wafer was a thick wafer of about 10 mm, the wafer stiffness would be very large, even if the pressure in the three chambers was changed, the pressure distribution between the wafer and the pad would be It can be easily predicted that it will remain almost unchanged.

  As described above, assuming ideal pressure distribution control on the wafer, even if an ideal pressure distribution state corresponding to the polishing shape is designed in order to obtain a desired polishing shape, the pressure is applied through the wafer. It is obvious that ideal polishing shape control cannot be performed in principle because the desired pressure distribution is destroyed in principle depending on the bending deformation of the wafer and the warpage of the wafer.

  Similarly, in Patent Document 7, if various elements related to polishing act uniformly, a uniform polishing shape is obtained in principle. However, depending on the element, there is an element that does not act uniformly. The case where there is a problem of non-uniformity is taken up.

  In response to these problems, the top ring that presses the wafer is divided into multiple areas, and the pressure in each area is optimized to correct the non-uniformity of other elements. A uniform polished shape is obtained.

  However, for the same reason as in Patent Document 6, it is obvious that an ideal pressure distribution cannot be formed at the interface between the wafer and the pad in principle, so that the ideal polishing shape cannot be controlled. .

  In Patent Document 8, when the two-layer pad is formed, the surface layer pad is swollen by slurry or the like to generate wrinkles, and therefore a support layer is provided for the purpose of preventing wrinkles. A structure in which a sheet is attached as the support layer is disclosed. However, even if this sheet for preventing wrinkles is used as the bending deformation sheet of the present invention, the following problems occur.

  It is also assumed that the wafer is placed on a holding table. That is, it is considered that the wafer is normally placed without being attracted to the holding table. When such a wafer is placed on a holding table, it does not make any sense at all even if the bending deformation sheet of the present invention is used instead of a sheet for preventing wrinkling. This is because, in a state where the wafer is simply placed in a warped state, it is assumed that the wafer itself bends on its holding table even if the deformation is controlled by the deformation sheet and pressed. In addition, when the wafer has a warp, the stress for correcting the warp is also affected.

  In this patent, the wafer is attracted and held on the back surface, the wafer neutral surface is made flat, and the wafer warpage is forced to provide wafer thickness unevenness and film thickness distribution on the wafer surface relative to the wafer back surface. Define the waviness shape of the wafer surface that has been added.

  In addition to having the function of flattening the irregularities formed in advance on the wafer surface and following the waviness of the wafer surface defined in the previous state, the flexure characteristics of the pad deformation sheet are flattening and follow the waviness. Will be achieved. The deflection deformation sheet has the original function of following the waviness shape of the wafer surface only for a wafer that can be regarded as a rigid body that can be regarded as a rigid body that does not flex with the wafer holder, based on the back surface of the wafer. It is.

  If the wafer is not flattened, the wafer warp cannot be corrected, and the wafer thickness unevenness and film thickness distribution are confused with the influence of the warp, and the waviness component of the wafer cannot be defined. Therefore, the bending deformation sheet is set as a bending characteristic, and the bending characteristic is set so as to follow the waviness of the wafer surface while suppressing the bending in the area where the wafer surface is flattened. The setting itself cannot be made. Depending on the case, there are cases where polishing is performed non-uniformly without following the waviness, and unevenness formed on the wafer surface cannot be flattened.

  Furthermore, even if a wrinkle prevention sheet shown in Patent Document 8 is used for the present invention, the bending characteristics of the sheet are not considered for the purpose of following the flattening of the wafer surface and the waviness of the wafer surface. , It doesn't make sense. That is, in Patent Document 8, the portion responsible for planarization of the wafer surface is the surface hard pad portion. However, the hardness of the flexure deformation of the hard pad portion is greatly changed due to swelling of the slurry or wear of the pad itself due to dressing, and the degree of flexure deformation increases.

  In the sheet for preventing wrinkling, a thin polyethylene sheet having a thickness of about 0.05 mm at most is used. The pad thickness is nearly 1.3mm. Such a thin polyethylene sheet may be effective in preventing wrinkling of the pad, but is not effective in controlling the flexural deformation characteristics of the pad because it is very thin. As a result, the flexure characteristics of the surface layer pad are affected as they are, and as a result, they are greatly affected by the decrease in flexural rigidity due to swelling due to slurry and wear of the pad due to dressing.

  In the present invention, the deflection characteristics of the pad are controlled by the deflection deformation sheet, and the deflection deformation is such that a stable deflection characteristic is obtained without being affected as much as possible by the change in the deflection characteristics due to the swelling of the pad slurry and the pad depletion due to the dressing. Use a sheet.

  For this reason, the thickness of the deformed sheet is required to be at least 0.1 mm or more than that which was about 0.05 mm in Patent Document 8, and ideally a thickness of about 0.2 mm to 0.5 mm in consideration of the thickness of the pad. Is preferred. In more detail, the thickness of the bending deformation sheet is set so that it hardly bends in the flattening region, and the Young's modulus of the member is set so that it can be sufficiently bent even with a small distributed load in the region following the waviness. It is desirable to set the thickness in consideration.

  Then, in view of the situation which concerns, this invention aims at solving the following subject.

  Problem 1: To provide a polishing apparatus for forming an ideal pressure distribution for obtaining a desired polishing shape without being affected by the deflection rigidity of the wafer or the warpage of the wafer.

  Problem 2: Even if the platen surface is warmed by the heat generated during polishing and the flatness of the platen changes slightly due to the temperature difference from the backside of the platen, the pressure distribution on the wafer surface does not change significantly. As a result, the polishing uniformity within the wafer surface is not greatly deteriorated. Furthermore, the temperature difference between the front and back surfaces of the platen is not increased by making it difficult for heat generated during polishing to be transmitted to the surface of the platen.

  Problem 3: When the back surface of the polishing pad is affixed on the platen with an adhesive or double-sided tape, bubbles are prevented from entering the polishing pad surface and adversely affecting the pressure distribution applied to the wafer surface.

  Problem 4: The wafer surface is not bent on the polishing pad when the wafer is pressed with a uniform pressure from the back surface of the wafer while following the polishing pad on the wafer surface against the gentle waviness on the wafer surface. And a neutral surface that is constantly a constant plane, so that a stable and uniform pressure distribution can be formed on the wafer.

  Problem 5: Even when the platen sheet is an elastic body, a change in pressure distribution due to an attachment error of the platen sheet is eliminated, and a stable pressure distribution can be formed when the sheet is attached to the platen.

  Problem 6: When the polishing pad is completely flat and the wafer is also completely flat, the pressure is not applied evenly in principle, but the pressure distribution on the wafer surface is uniform depending on the shape of the platen sheet. To be.

  Problem 7: Even if the sheet to be attached to the platen is an elastic body having a high density, a uniform pressure distribution is applied to the entire surface of the wafer so that the sheet does not rebound due to the pressing pressure.

  Problem 8: When the flexural rigidity of the surface layer of the polishing pad formed in two layers is weak, or even if the flexural rigidity is strong in the dry state, the flexural rigidity is lowered by the penetration of the slurry, and as a result, the flattening characteristics deteriorate. Even in such a case, a certain degree of flatness is ensured by making the second layer hard to suppress bending deformation. Also, even if the surface thickness changes due to dressing of the polishing pad and the index related to flexural rigidity changes from the initial state, a stable and uniform pressure distribution can be formed on the wafer. To do.

  Problem 9: When an initial wafer has various film thickness distributions, a compression deformation suitable for correcting the film thickness distribution so as to obtain a desired film thickness distribution after polishing according to the film thickness distribution. It is possible to adjust the pressure distribution by selecting a plate and laying the pressure distribution adjusting sheet on a polishing surface plate by an appropriate method.

  Problem 10: Furthermore, the elastic body itself has a stable pressure distribution shape on the wafer by repeated operations, and as a result, a constantly stable pressure distribution form can be obtained.

The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is a polishing in which polishing is performed by relatively slidingly contacting a wafer and the polishing pad while dropping and supplying slurry onto the polishing pad. In the device
Using the back surface of the wafer as a reference surface, a wafer holding table to which the entire surface of the wafer is decompressed and flattened,
A compression deformation plate that is laid and fixed on a platen that moves relative to the wafer to form a desired pressure distribution;
A tensioning mechanism for tensioning and fixing the polishing pad on the compression deformation plate;
The polishing pad is provided with a bending deformation sheet laid on the compression deformation plate and displaceable by bending deformation, and a surface layer pad laid on the bending deformation sheet and holding a dropped slurry.
The surface pad is affixed and integrated on the flexible deformation sheet.
A polishing apparatus having a pressure distribution adjusting function is provided.

  According to this configuration, the wafer is reduced in pressure over the entire surface and held flattened and held, so that the wafer is continuously flattened and processed regardless of the warpage of the wafer, so that a stable pressure distribution not caused by the wafer state is achieved. As a result, a stable polished shape can be obtained. Further, even when a polishing load is applied to the wafer, the wafer does not bend as in the prior art, and the neutral surface of the wafer constantly maintains a flat surface. Accordingly, it is possible to eliminate the fact that the wafer is bent and deformed by the polishing load, and that the bending deformation of the wafer affects the pressure distribution in the wafer surface during polishing.

  In addition, a polishing pad according to the present invention includes a bending deformation sheet that is laid on a compression deformation plate and can be displaced by bending deformation, and a surface layer pad that is laid on the bending deformation sheet and holds a dropped slurry. Yes.

  According to this pad configuration, even if the surface layer pad is swollen by the slurry by the bending deformation sheet that can be displaced by the bending deformation, the bending deformation rate is controlled by the bending deformation sheet rather than the bending of the surface layer pad. Stable bending deformation can be ensured regardless of pad wear and slurry swelling, and stable flattening characteristics can be obtained.

  In addition, the compression deformation plate that supports the flexure deformation sheet on the back side and has a desired pressure distribution formed in advance allows the pressure distribution when the wafer and the pad are in contact to be viewed macroscopically. Become. Further, regarding the pressure distribution when viewed macroscopically, the bending deformation sheet under the surface layer pad can be bent with almost no resistance in a region that follows the waviness of the wafer.

  As will be described later, according to the equation relating to bending deformation, it can be seen that the amount of displacement to be bent and deformed is proportional to the fourth power of the radius when the same distributed load is applied. In other words, the bending deformation is very small and neglected in a narrow range, but it is easily bent greatly in a slightly wide range. By using this bending principle, in a narrow region where flattening is required, the bending deformation sheet is not bent, the pad acts as a rigid body, and the region is polished uniformly by following the waviness of the wafer surface. In this case, the bending rigidity may be set so as to be easily bent. Since the amount of bending changes in proportion to the fourth power of the radius of the region, the bending deformation can be changed drastically by selecting a bending deformation sheet having an appropriate bending rigidity.

  When the surface layer pad, which has been a problem in the past, swells including slurry, the rigidity of the flexural deformation changes, and as a result, there is no problem that the polishing performance for flattening and polishing the unevenness of the wafer surface is significantly deteriorated.

  This is because the bending deformation of the bending deformation sheet on the lower side of the surface layer pad dominates against this bending deformation, and the bending deformation sheet of the surface layer pad does not swell against this slurry. This is because it is almost controlled by the bending deformation.

  Furthermore, the entire surface of the pad, particularly the bending deformation sheet, has a uniform thickness structure. Since the bending deformation sheet has a uniform thickness, it does not have a portion having a weak local strength as in a conventional pad. As a result, the shearing stress caused by polishing and the torsional stress combined with the stress that purely presses the wafer are dispersed by the uniform bending deformation sheet. As a result, the fretting phenomenon expected when using conventional grooves or pads of hard members that are segmented does not occur, and the entire bending deformation sheet is subjected to the shearing stress of polishing.

  As a result, the stress is concentrated at a portion where the strength of the pad is weak during polishing, thereby causing a fretting phenomenon. As a result, the pad does not break from the portion. Also, the surface pad and the bending deformation sheet cause a phenomenon that a part of the surface pad is lifted from the elastic body due to the torsional stress, and the pressure distribution exerted on the part in the wafer by the surface layer pad becomes extremely large and deteriorates. There is nothing. As a result, the flexural deformation sheet maintains a stable strength over a long period of time, and a stable polished shape can be obtained under a stable pressure distribution state.

  In addition, even if there are variations in the thickness of the surface pad, the bending deformation sheet, etc., the elastic deformation for following the waviness of the entire wafer surface has a slight deformation margin because the previous compression deformation plate has a sufficient deformation margin. A stable predetermined pressure distribution is formed regardless of the thickness variation of the members. The pressure distribution can be transmitted to the wafer as it is without being disturbed by the deformation of the wafer.

  As a result, a stable desired polished shape can be obtained regardless of the flexural rigidity of the wafer (such as wafers having different thicknesses) or warpage of the wafer. Furthermore, even if the initial wafer film thickness distribution is non-uniform, the desired polished shape can be obtained, so that the initial non-uniform film thickness distribution can be corrected to obtain a uniform pressure distribution after polishing. Is possible.

  Here, the flattening of the wafer is indispensable particularly when controlling the shape of polishing which is the subject of the present invention. If the wafer is not flattened, it does not make sense to apply pressure to the compression deformation plate below the pad. In particular, when the film thickness distribution of the initial wafer is not uniform and it is necessary to correct the non-uniform film thickness distribution for polishing, this becomes remarkable.

  For example, when a wafer is placed on a flat plate and there is a warp in the placed state, even if a uniform polishing load is applied to the wafer, the polishing load is not uniform. It is necessary to correct the wafer warp by applying a biased polishing load for correcting the warpage of the wafer, and to apply a uniform polishing load on the wafer.

  At that time, the uneven polishing pressure for correcting the warpage of the wafer and the arbitrarily non-uniform polishing pressure for correcting the initial film thickness distribution of the wafer are almost the same, but the deviation at the same position. Even if a biased polishing pressure is applied to correct the shape of the initial film thickness distribution, the pressure state corresponding to the deviation may be used to correct the warpage of the wafer. sell. In such a state, the initial film thickness distribution cannot be corrected, and uniform polishing is performed, and the resulting film thickness distribution of the wafer is not as uniform as the initial film thickness distribution. It will end.

  Therefore, in order to effectively operate the pressure distribution with a deviation to correct the initial film thickness distribution, the wafer is held in a form that eliminates the influence of the warpage of the wafer as much as possible, and then controlled. It is important to give a stable pressure distribution to the wafer by a compression deformation plate having a responsive pressure distribution state.

  Furthermore, at the same time, the pressure distribution adjustment requires that the two functions of the compression deformation plate and the bending deformation sheet independently act on the two functions of the compression deformation and the bending deformation. Even if the polishing shape is controlled by the pressure distribution, as a precondition, it is required to flatten the unevenness formed on the wafer plane. As a method for that purpose, the method shown in the present invention utilizes the deflection characteristics of the member. As described above, since the displacement amount of the member increases in proportion to the fourth power of the radius of the region, an effect of turning on and off depending on the size of the region can be obtained.

  Furthermore, since the amount of bending is controlled by a uniform bending deformation sheet instead of the conventional hard sectioned member, the torsional stress generated by polishing shear and pressing stress is not locally received. The stress is dispersed by the uniform bending deformation sheet. As a result, the flexural deformation sheet will not break, and it will not lift locally from the elastic body, and it will be possible to constantly give a constant pressure distribution with stable flexural deformation. .

  Moreover, the polishing apparatus according to the present invention has a lifting mechanism for lifting and fixing the polishing pad on the compression deformation plate.

  With this configuration, the tensioning mechanism is fixed on the compression deformation plate in a state where the polishing pad integrally formed by pasting the surface layer pad and the flexural deformation sheet is pulled down to the lower side of the platen, There is no pressure change accompanying the attachment of the surface layer pad, and the surface layer pad is attached to the elastic body on the surface of the compression deformation plate without expanding even if the surface layer pad swells. Moreover, since the surface layer pad and the bending deformation | transformation sheet | seat bonded together are easily bent, it reflects the pressure distribution formed with the compression deformation board. In addition, since the double-sided tape is not interposed between the surface layer pad and the flexurally deformable sheet that are bonded together and the elastic body, a stable pressure distribution can be ensured.

  As a result, conventionally, since the operator replaced the polishing pad, there was a variation in pasting depending on the skill of the worker itself, but in the present invention, due to the variation in pasting. There is no pressure distribution variation.

  Furthermore, according to the pasting method using a double-sided tape or the like, for example, when a flexible deformation sheet is attached to an elastic material on a compression deformation plate, there is a problem that the elastic material does not stick with an adhesive tape and peels off in the middle. Arise. Alternatively, if it is pasted, the elastic material on the surface may be peeled off during the next peeling.

  In addition, even if the surface of the compression deformation plate or the surface of the bending deformation sheet is subjected to any treatment to be easily removed and secured, and the stable adhesion ability can be secured, the following problem occurs. That is, at the time of polishing, when the shearing stress of polishing acts, it directly twists the elastic body on the compression deformation plate. Due to this torsional stress, the elastic body deforms in the lateral direction and loses a stable elastic recovery force when used for a long time. Since the compression deformation plate has a shape in which a predetermined pressure distribution is formed in advance, it is preferable to use the compression deformation plate with a low replacement frequency over a long period of time. The continuous lateral stress acts on the compression deformed plate, which significantly shortens the usable lifetime.

  When the tensioning mechanism fixes the polishing pad while holding the outer peripheral edge of the polishing pad while being pulled down to the lower side of the platen, the shearing stress due to polishing exerted on the pad is supported by the tensioning mechanism. No lateral stress is applied to the compression deformation plate below. For this reason, the compression deformation plate is simply subjected to repeated load due to polishing in the compression direction. With such a shape, the compression deformable plate is formed of a material that can sufficiently withstand repeated compressive stress, and thus can be used over a long period of time.

  In addition, the bending deformation sheet integrated with the surface layer pad is bent to such an extent that it can be sufficiently displaced against the waviness of the wafer on the compression deformation plate, but it is greatly deformed with respect to the stress in the pulling direction. And sufficient strength. Thereby, the pad does not break due to the shearing stress of polishing and does not wrinkle.

  Furthermore, when replacing the pad, only the polishing pad needs to be replaced. The replacement method can be easily removed by removing the pad's outer ring, removing the polishing pad leaving the compression deformation plate, and mounting the pad by placing the outer ring on the compression deformation plate and lifting it up at the outer periphery. It is possible to attach.

  With this method, pressure was distributed between the pad and the wafer by introducing air bubbles between the polishing platen and the pad, as was the case when using the conventional double-sided tape to bond the pad onto the platen. There will be no variation in. Regardless of the skill of the operator, it is possible to stably attach a pad on the compression deformation plate to have a stable pressure distribution. That is, a stable pressure distribution can be formed by not interposing a double-sided tape.

  According to this configuration, since the surface layer pad holding the slurry and the flexible deformation sheet are integrated on the entire surface, even if the surface layer pad holding the slurry swells and deforms, the deformation due to the swelling is not deformed. It can suppress by a bending deformation sheet. Furthermore, when the surface layer pad is not firmly fixed to the bending deformation sheet, it is predicted that the surface layer portion holding the slurry is twisted and broken by the shearing stress of polishing, according to the present invention. In addition, since the slurry holding portion and the bending deformation sheet are firmly fixed, there is no such concern.

  Furthermore, in flexural deformation control with a flexural deformation sheet to achieve both of the functions of flattening the unevenness of the wafer and following the waviness of the wafer surface, the flexural deformation sheet and the surface layer pad are integrated to integrate them. Stable bending deformation control can be performed at the part. Furthermore, even if the portion holding the slurry is reduced in flexural rigidity due to the decrease in pad thickness due to slurry holding or pad dressing, the flexural rigidity of the closely-fitted deformation deformed sheet is dominantly affecting the slurry holding portion. In addition, stable bending deformation control can be realized. As a result, it is possible to achieve both the flattening of the wafer surface and the function of following the long range waviness of the wafer surface.

According to a second aspect of the present invention, the elastic body on the surface of the compression deformation plate is formed of an elastic material having a small compression set without voids, and the opposed surface facing the polishing pad is segmented.
2. The polishing apparatus having a pressure distribution adjusting function according to claim 1, wherein the opposing surfaces of the segmented elastic bodies are independently deformed.

  According to this configuration, even when subjected to repeated stress due to polishing, a dense material having a stable elastic recovery force can be selected without causing any permanent compression set in the elastic body. If the elastic material is not dense, for example, an elastic body having a void such as a sponge, the elastic body itself is deformed under repeated stress and a stable elastic recovery force cannot be expected, and the pressure distribution of polishing can be reproduced repeatedly. Not.

  In addition, in the case of a dense material having a stable elastic recovery force as shown above, when the elastic body is locally deformed in a certain region, the vicinity of the vicinity of the elastic body itself is maintained due to the function of keeping the volume of the elastic body constant. The bounce stress occurs. As a result, there is a problem that it is difficult to keep the polishing pressure distribution continuously following the wafer surface.

  However, depending on whether the opposing surface of the elastic body of the dense compression deformation plate has a groove or the elastic body itself is divided and arranged, it can be deformed independently in each elastic body region. Become. The conventional bounce stress is not generated, and it is possible to follow the waviness of the wafer surface constantly and uniformly.

  As a result, a stable predetermined pressure distribution can be formed on the wafer, and the wafer polishing shape can be accurately controlled.

  Moreover, according to this structure, the opposing surface of an elastic body is divided by the groove | channel etc., for example, and each deform | transforms independently. If the elastic body is not segmented, use of an elastic material (elastic body) with a small compression set as described above causes other parts to rise to keep the volume of the elastic material constant even when deformed. Complete the deformation state. This deformation of the elastic material during polishing, even if one part is deformed by the waviness of the wafer, because of such a bounce in the other part, as a result can not be pressed independently by each wafer location .

  Since the elastic body of the compression deformation plate is segmented, each segmented portion is independently deformed, and as a result, the polishing pressure distribution can be controlled regardless of the waviness of the wafer surface. It becomes.

  Therefore, for example, when the elastic body is formed of a high-density elastic material, even if it is recessed in some areas, it can be prevented from rebounding in other areas, and the pressure distribution on the wafer surface can be made uniform. Can be.

Third aspect of the present invention, the compressive deformation plate, said elastic body for compressing deformation, according to claim 2, characterized in that and a hard plate for uniformly fixing the elastic body in the whole surface A polishing apparatus having a pressure distribution adjusting function is provided.

  When the compression deformation plate is composed only of an elastic body, it is difficult to fix the compression deformation plate to the platen, for example, screw fixing is not possible. With double-sided tape and adhesive fixing, pressure variations can occur depending on the method of application, and the operator cannot easily do this. However, according to this configuration, since the elastic body in which a predetermined pressure distribution is formed in advance is attached to the hard plate, the worker can easily attach it by simply placing the hard plate surface on the polishing surface plate as it is. Become.

  In addition, as for the accuracy in mounting, if the platen and the hard plate have sufficient surface accuracy, they are simply aligned. Furthermore, if both have sufficient rigidity, they can be sufficiently attached by screw fixing or the like. The screw distribution does not disturb the pressure distribution of the elastic material.

  Furthermore, a hard plate is integrally attached to the back surface of the elastic body, a compression deformation plate on which a predetermined pressure distribution is formed is mounted on the platen, and a surface layer pad in which a bending deformation sheet is integrally attached to the back surface. Mount on the elastic body. That is, a surface layer pad, a bending deformation sheet, an elastic body, and a hard plate are attached to the surface of the platen in order from the top, and the compression deformation plate is formed by integrating the elastic body and the hard plate.

  According to this configuration, even if thermal deformation is caused by a slight temperature gradient between the platen surface and the back surface by the compression deformation plate, the deformation is absorbed by the deformation margin of the elastic body and is stable according to the elastic deformation of the substance. A pressure distribution is formed. Further, by protecting the platen with an elastic body, the pressure distribution does not change even if the platen has a dent or the like. Further, since the elastic body is attached to the hard plate to form an integrated structure, the pressure distribution can be easily adjusted without replacing the platen.

According to a fourth aspect of the present invention, there is provided the polishing apparatus having a pressure distribution adjusting function according to the third aspect, wherein the compression deformation plate is formed so as to be integrally replaceable from the platen .

  According to this configuration, the elastic body and the hard plate constituting the compression deformation plate are integrally formed to be exchangeable. Thereby, in order to avoid that an elastic body and a hard board move unnecessary between a platen and a polishing pad, the pressure distribution formed in the compression deformation board can be stabilized over a long period of time.

According to a fifth aspect of the present invention, there is provided the polishing apparatus having a pressure distribution adjusting function according to the fourth aspect, wherein the surface of the compression deformation plate is formed into a shape in consideration of the pressure distribution in advance. .

  According to this configuration, since the pressure distribution is formed on the compression deformation plate in advance, it is possible to give a stable pressure distribution to the wafer without using the pad. In particular, the pad is consumed by pad dressing along with polishing, and the exchange frequency due to consumption is very high. On the other hand, the compression deformation plate is only subjected to polishing stress, and unlike the surface layer pad, it is not immersed in the slurry or consumed by the dressing. Therefore, even in a state where stress is repeatedly applied, by using an elastic material having a small compression set, it is possible to produce the same elastic recovery force over a long period of time, and a stable pressure distribution is formed. It becomes possible.

  The compression deformation plate is deformed with a sufficient deformation margin. As a result, there is a deformation margin sufficient to allow a series of slight dimensional deformations such as uneven thickness of the member, uneven thickness due to thermal deformation of the platen, and uneven thickness of the wafer substrate itself. By giving the wafer the pressure distribution previously provided on the compression deformation plate with this sufficient deformation margin, it is possible to give the wafer a robust pressure distribution that is not affected by various disturbances. It becomes possible.

  Furthermore, the wafer is vacuum-adsorbed and flattened on the basis of the wafer back surface. Even when the wafer is subjected to the polishing pressure in the flattened state, the flat state of the back surface hardly deforms. It is possible to apply a stable pressure distribution to the wafer surface by applying the pressure distribution of the compression deformation plate, in which the pressure distribution is set in advance, to the wafer surface under the reference state that does not deform.

According to a sixth aspect of the present invention, in the region where the polishing pad flattens the irregularities on the surface of the wafer, the amount of deformation of the pre-polishing pad is smaller than the amount of compressive deformation and follows the waviness of the wafer surface. 2. A polishing apparatus having a pressure distribution adjusting function according to claim 1 , wherein the bending rigidity is set so that the bending deformation amount of the polishing pad is larger than the compression deformation amount.

  According to this configuration, the flexural rigidity of the polishing pad is set so that the flexural deformation amount of the integrated surface layer pad is smaller than the compressive deformation amount in the region where the unevenness on the wafer surface is flattened. On the other hand, in the region following the waviness of the wafer surface, the flexural rigidity of the polishing pad is set so that the flexural deformation amount of the integrated surface layer pad is larger than the compressive deformation amount.

  In the present invention, as described above, a hard plate is integrally attached to the back surface of the elastic body and mounted on the platen, and a flexible deformation sheet is attached to the back surface of the surface layer pad and attached to the elastic body. Since the wafer is averaged while correcting the warp of the wafer, the elastic deformation can absorb the thermal deformation of the platen and form a stable pressure distribution according to the elastic deformation of the substance. . Further, by protecting the platen with an elastic body, it is possible to prevent a change in pressure distribution even if the platen has a dent or the like. In addition, since the elastic body is attached to the hard plate and integrated, the pressure distribution can be easily adjusted without replacing the platen.

  Moreover, since the surface layer pad is affixed on the flexible deformable sheet having a low spreadability, a double-sided tape for affixing the surface layer pad is not necessary, and fine adjustment of the adhesive force is not required other than the pressure distribution.

  In addition, since the polishing pad made up of the surface layer pad and the bending deformation sheet with the tension mechanism attached integrally is lifted and fixed on the polishing pad, it is possible to prevent the pressure change associated with the surface layer pad from being attached. Even if it swells, it can be mounted without stretching. Moreover, since the surface layer pad and the bending deformation sheet that are attached together are easily bent, the pressure distribution formed by the elastic body can be reflected. Further, since the double-sided tape is not interposed between the surface layer pad and the flexurally deformable sheet that are integrally bonded and the elastic body, a stable pressure distribution can be ensured.

  In addition, since the elastic body is formed of a material having a small compressive deformation and the surface thereof is formed in a convex shape in consideration of the pressure distribution in advance, even when the bending rigidity of the surface layer pad is reduced, the change in the pressure distribution is suppressed, Polishing uniformity within the wafer surface can be maintained. In addition, since the surface of the elastic body is formed in a convex shape considering the pressure distribution in advance, even if the polishing pad and the wafer are completely flat, a uniform pressure distribution is given within the wafer surface and the polishing uniformity Can be secured.

  In addition, the opposing surface of the elastic body is segmented, and each of them is deformed independently, and the elastic body and the hard plate are formed so as to be integrated and replaceable. Therefore, the sheet to be attached to the platen is a high-density elastic body. Even if it exists, uniform pressure distribution can be given to the whole wafer surface so that the rebound does not occur due to the pressing pressure. Also, even when the surface thickness changes due to the dressing of the polishing pad and the index related to the flexural rigidity changes from the initial state, a stable and uniform pressure distribution can be formed on the wafer. it can.

1 is an overall perspective view of a CMP type polishing apparatus according to the present invention. Explanatory drawing of a wafer holding stand. Explanatory drawing of the pressure distribution shape of a compression deformation board. Explanatory drawing of the pressing state of a polishing pad. Explanatory drawing of the spring model corresponding to FIG. A graph comparing the size of the dent and the amount of deformation. Explanatory drawing of the deformation | transformation characteristic with respect to the magnitude | size of a dent. Explanatory drawing which shows the structure of a polishing pad. Explanatory drawing of a platen.

In order to achieve a purpose of providing a platen sheet that prevents the platen from being thermally deformed due to heat generation during polishing and minimizes a change in pressure distribution, the wafer is supplied while dropping slurry on the polishing pad. In a polishing apparatus that performs polishing by relatively sliding the polishing pad and the polishing pad,
Using the back surface of the wafer as a reference surface, a wafer holding table to which the entire surface of the wafer is decompressed and flattened,
A compression deformation plate that is laid and fixed on a platen that moves relative to the wafer to form a desired pressure distribution;
A tension mechanism that lifts and fixes the polishing pad on the compression deformation plate, and the polishing pad is laid on the compression deformation plate and can be displaced by bending deformation; and the deformation deformation and a surface layer pad which holds the slurry dropped is laid on the sheet, the surface layer pad is more achieved a polishing apparatus having a pressure distribution adjustment function are integrated pasted on the bending deformation sheet did.

  FIG. 1 is an overall perspective view of a CMP type polishing apparatus, and FIG. 2 is an explanatory view of a wafer holder. The polishing apparatus 10 mainly includes a wafer holding table 20 that holds a wafer, a rotating platen 30, and a polishing pad 50 that is mounted on the platen 30 via a compression deformation plate 40. The wafer holding table 20 is formed in a disk shape, holds the wafer under reduced pressure on its lower surface, and a rotating shaft 21 is connected to the center of the upper surface, and rotates in the direction of arrow A by driving a motor (not shown).

  The wafer holder 20 is provided with a groove for vacuum suction on the entire surface. By reducing the pressure through the reduced pressure suction hole 20a communicating with the groove of the suction table, the wafer can be firmly suctioned and held on the wafer holding table 20. The flatness of the surface of the wafer chuck plate 20b of the wafer holder 20 is finished to about 5 μm, for example. The parallelism of the wafer holder 20 is also within 10 μm. Even if the wafer has a warp in such a state, the warp can be sufficiently corrected by this reduced-pressure adsorption. As a result, the wafer is strongly flattened without bending with respect to the wafer back surface.

  Next, the compression deformation plate 40 has a configuration in which an elastic body 41 is attached to a hard plate 42. As the material of the hard plate 42, it is desirable to use a member that is a plane reference, such as stainless steel or ceramics, that does not deform even when subjected to some stress.

  The hard plate 42 becomes a compression deformation plate 40 as a base and is attached to the platen 30 as it is. When the hard plate 42 is mounted on the platen 30, the surface of the platen 30 and the surface of the hard plate 42 are simply aligned, and a pin (not shown) is erected on the platen 30. It is sufficient that it does not deviate from the surface.

  As another method, the outer peripheral portion of the hard plate 42 may be attached to the platen 30 by screwing. Since both of them are sufficiently hard and are joined at the mating surface, even if the periphery is fixed with screws, the pressure distribution exerted on the wafer by the compression deformation plate 40 is not affected by the fixing method.

  As a method of attaching the elastic body 41 on the hard plate 42, a method using a double-sided tape, a method using an adhesive, or the like is selected. Since the member is very sensitive to the formation of pressure distribution, it is desirable to apply the elastic body 41 to the hard plate 42 as uniformly as possible.

  As the material of the elastic body 41, it is desirable to use a rubber material such as styrene butadiene rubber or nitrile butadiene rubber which does not leave compression set. In addition, it is desirable to select a rubber hardness of about 20 to 60 according to JIS6253, but this also depends on the surface shape of the rubber material. By making the surface into a small section, the amount of apparent deformation can be increased, and even a somewhat hard material can be softened.

  Next, as shown in FIG. 3, the elastic body 41 is previously provided with a pressure distribution shape. Such a pressure distribution shape can be obtained by cutting out the surface of the elastic body 41, that is, the opposing surface 41s facing the polishing pad (not shown) placed on the elastic body 41 into a predetermined shape. . The shape of the elastic body 41 of the compression deformation plate 40 for forming the pressure distribution is a convex shape shown in FIG. 3 (a), a concave shape shown in FIG. 3 (b), and a taper shown in FIG. 3 (c). Various shapes such as a shape are possible. Such a shape may be modified in advance using a commercially available pressure distribution measuring device or the like so as to be a shape based on the pressure gradient, and the opposing surface 41s of the elastic body may be processed.

  Although the processing method of the opposing surface 41s of the elastic body 41 can be formed by a mold or the like, the surface is ground after the elastic material is adhered to the hard plate 42 with a double-sided tape or an adhesive 43. Is suitable for correcting the pressure distribution most finely. As the surface shape of the elastic body 41, for example, a portion where the opposing surface 41 s of the elastic body 41 is about 100 μm to 200 μm and the portion in contact with the wafer central portion (the intermediate portion between the center of the elastic body and the outer periphery) is in contact with the wafer peripheral portion. It was set to be higher than (the center or the outer periphery of the elastic body).

  The total thickness of the elastic body 41 was 7 mm, and the thickness of the hard plate 42 therebelow was made of SUS and the thickness was 1 cm. The parallelism and flatness of the SUS part were about 10 μm or less. With this accuracy, a sufficient deformation margin of the elastic body 41 can be taken.

  Next, even if a pressure distribution shape is provided, a desired pressure distribution shape may not necessarily be obtained. As described above, in the case of the elastic body 41 having a high density, the elastic body 41 is deformed so as to keep the volume constant. Therefore, the volume of the elastic body 41 that is locally deformed in one place is bounced to another place. The amount of deformation increases. In order to keep the volume of the elastic body 41 constant, the elastic body 41 is deformed so as not to allow local deformation, and as a result, distortion may occur.

  For this reason, a groove 41a is provided on the opposing surface 41s of the elastic body 41 as shown in FIG. Even when the elastic body 41 is deformed so that the volume of the elastic body 41 is kept constant when the elastic body 41 is subjected to compressive deformation in the longitudinal direction, the volume reduction due to the deformation is expanded at the groove 41a. Become. As a result, the elastic body 41 is allowed to be independently compressed and deformed at each of the sections partitioned by the groove 41a. As the shape of the groove 41a, the groove 41a can be formed on the opposing surface 41s of the elastic body 41 in various patterns such as a lattice shape, a triangular shape, and a circular shape. As the shape of the groove 41a, the depth is set to 5 mm, for example. The groove pitch was 15 mm and the groove width was about 1 mm.

  FIG. 4 is a cross-sectional view of a state in which the polishing pad 50 in which the surface layer pad 51 and the bending deformation sheet 52 in this patent are integrated presses the dent, and FIG. 5 is an explanatory view of a corresponding spring model. For convenience of explanation, the positional relationship between the wafer and the pad is turned upside down.

  As shown in FIG. 4, a polishing pad 50 composed of a surface layer pad 51 and a bending deformation sheet 52 is attached on the elastic body 41. The bending deformation sheet 52 is resistant to tensile stress, but is preferably a flexible member. This is because, in the case of this method, the bending displacement of the bending deformation sheet 52 hardly bends in the order of flattening the wafer W, and sufficiently bends and follows the surface of the wafer W in the order of following the waviness of the wafer W. A flexible deformation sheet 52 of a degree is desired.

  Therefore, as a material of the bending deformation sheet 52, a stainless steel sheet or other metal material, a PET material, a Teflon (registered trademark) sheet, or the like is preferable. For example, when a PET material or other resin sheet is used, the thickness of the bending deformation sheet 52 is preferably about 1 mm to 2 mm, but may be thinner. The thickness of the bending deformation sheet 52 depends on the lateral size of the unevenness formed on the surface of the wafer W to be flattened. That is, a thickness of about 0.05 mm is sufficient if the unevenness in the area of the order of 0.01 mm is at most, but if the unevenness in the area of the order of about 1 mm is formed, the deformation sheet 52 is about 1 mm. Thickness is required.

  If the bending deformation sheet 52 has a thickness of about 1 mm, depending on the Young's modulus of the member, even if there is a undulation of about φ100 mm region on the wafer W, the surface pad surface is not difficult on the wafer W surface, It is possible to follow. As a result, the bending deformation sheet 52 can be bent in a form depending on the amount of compression deformation of the compression deformation plate 40.

  Further, on the bending deformation sheet 52, there is a surface layer pad 51 that has good slurry retention and contributes to polishing. This surface layer pad 51 contributes to polishing as a function to be fulfilled. Specifically, it has a good retention of slurry, and when the surface layer pad 51 is clogged, it can be recovered from that state. Thus, a function such as being able to perform pad dressing is required.

  For example, when the surface layer pad 51 is formed of a hard material, even if a simple sheet material such as a polyethylene sheet, a vinyl chloride sheet, or an acrylic sheet is used, the slurry retainability is poor, and further, the slurry retainability is bathed. Therefore, it is possible that the surface cannot be pad dressed. Therefore, for example, a material in which a foam or a nonwoven fabric is impregnated with a hard resin is used even if it is called a resin. An IC1000 (thickness 1.27 mm) manufactured by Nitta Haas is an example of the surface layer pad 51 that has good slurry retention, can be pad dressed, and can obtain good polishing characteristics.

  Needless to say, such a pad material having good slurry holding ability swells somewhat to hold the slurry when holding the slurry. Furthermore, it is shaped like a foam to increase the holding area of the slurry. In such a foam-shaped member, since the pad itself swells and expands by holding the slurry, the hardness, the degree of flexural deformation, and the like naturally change. Therefore, it is difficult to use the pad material in place of the bending deformation sheet 52 while maintaining a certain bending deformation, and the surface of the pad is constantly maintained by the slurry holding performance and dressing performance, and the polishing characteristics are the best. The original function is to obtain a member for obtaining.

  For this reason, the function required of the bending deformation sheet 52 is required to obtain a stable bending characteristic regardless of the retention of the slurry that the surface layer pad 51 cannot fulfill and the pad dressing state. For this reason, forming a foam or non-woven fabric with a material impregnated with a hard resin greatly hinders the stability of flexural deformation, so it is desirable that the sheet material is as strong as possible and does not hold a slurry. .

  Further, since the surface layer pad 52 and the bending deformation sheet 51 are required to be integrally bent on the compression deformation plate 40, it is desirable that they are integrated. As an integration method, various methods such as sticking with a double-sided tape, sticking with an adhesive, and thermocompression bonding can be used. Even when the bending deformation sheet 51 and the surface layer pad 52 are integrated, it is obvious that the properties of each layer (the surface layer pad 52 part and the bending deformation sheet 51 part) are different from each other due to the characteristics of each member.

  Next, the effect of flattening the wafer surface with respect to the bending deformation sheet 52 and the principle of following the waviness of the wafer surface will be described.

  As shown in FIG. 4, assuming a recess 22 having a diameter 2 a on the wafer W, the followability of the pad according to the diameter (size) of the recess 22 is evaluated. When the followability is good, that is, when the pad reaches the dent sufficiently, it indicates that the polishing proceeds uniformly. When not following the dent, it indicates that only the convex portion is selectively polished.

  As shown in FIG. 5, in the spring model in which the polishing pad 50 composed of the bending deformation sheet 52 and the surface layer pad 51 and the compression deformation plate 40 thereunder are combined, the spring A and the spring B having greatly different spring constants are arranged in series. It is considered that the leaf springs C are sandwiched between them. Spring A refers to compressive deformation of the surface pad. It is hard to deform with a hard member, and the spring constant is very large. Spring B refers to the compression deformation of the compression deformation plate. Since it is formed of an elastic body, it has a small spring constant and is easily deformed as compared with the spring A.

  The leaf spring C in the meantime corresponds to the bending deformation sheet affixed to the back side of the surface layer pad. By the state of these three springs, it is possible to achieve both flattening of minute irregularities and uniform polishing on the entire wafer surface. In order to achieve both flattening polishing and uniform polishing, it is important to balance the deformation caused by the longitudinal elasticity of the surface layer pad (spring A) and the deformation of the bending deformation sheet (spring C).

  When a uniform distributed pressure p is applied to the pad, the longitudinal deformation ωA of the surface layer pad is approximately obtained by the following equation.

      EA is expressed by the following equation.

  Next, the amount of bending deformation of the bending deformation sheet when a uniform distributed pressure is similarly applied is obtained. Assuming that the uniform distributed pressure p acts on the bending deformation sheet (leaf spring C), the maximum bending amount ωC of the bending deformation sheet with respect to the recess having the radius a can be expressed by the following equation.

  In addition, D becomes following Formula.

  FIG. 6 is a graph comparing the amount of deformation of the surface layer pad (the amount of deformation of the spring A) and the amount of deformation of the bending deformation sheet (the amount of deformation of the leaf spring C) against the radius a of the recess, and FIG. It is explanatory drawing which shows the difference in the displacement characteristic of the bending deformation sheet | seat with respect to. For convenience of explanation, FIG. 7 shows the positional relationship between the wafer and the pad reversed.

  As shown in FIG. 6, the deformation amount of the surface layer pad has a theoretically constant value even when the dent area is large. On the other hand, the amount of deformation due to the bending of the bending deformation sheet increases rapidly in proportion to the fourth power of the radius a of the recess. When the radius a of the dent is less than 4 mm, the bending deformation amount of the bending deformation sheet is negligibly small, and the deformation amount of the surface layer pad exceeds the bending amount of the bending deformation sheet. In this region, since the deformation amount of the surface layer member that is a hard member is dominant, the convex portion is selectively polished without following the dent.

  On the other hand, when the dent radius a is 4 mm or more, the bending deformation amount of the bending deformation sheet greatly exceeds the compression deformation amount of the surface layer pad. The bending of the bending deformation sheet is supported by the deformation of the compression deformation plate. When the radius a is 10 mm or more, the bending deformation amount of the bending deformation sheet is very large, and the stress required for the deformation is almost negligible. Therefore, the total spring constant K is equal to the spring constant KA of the surface layer pad (spring A) and the compression. The spring constant KB of the deformation plate (spring B) is combined in series, and is expressed by the following equation.

  Here, the compression deformation plate has a very small spring constant as compared with the surface layer pad, and KA >> KB. Therefore, from equation (5), the total elastic constant K is expressed by the following equation.

  This indicates that the deformation of the compression deformation plate is dominant, and the surface pad surface sufficiently follows the dent.

  When the unevenness of the narrow region and the radius “a” of the dent are less than 4 mm, the flexural deformation sheet hardly bends, so that the compressive deformation of the surface layer pad is dominant, and the elastic constant K is expressed by the following equation.

  FIG. 7A shows a case where the radius a of the recess is less than 4 mm, and the leaf spring does not deform in a narrow region. Therefore, the spring A having a large elastic modulus acts on the surface. The surface layer pad does not follow the irregularities on the wafer surface, and only the convex portions are selectively polished, and the planarization proceeds. On the other hand, FIG. 7B shows a case where the radius a of the recess is 4 mm or more, and the leaf spring is deformed in a wide region. As a result, the spring C having a small elastic modulus moves. The surface layer pad follows the irregularities on the wafer surface and uniformly grinds all irregularities.

  In this way, by changing the bending characteristics of the bending deformation sheet, whether the compression deformation of the compression deformation plate is applied or only the compression elasticity of the surface layer pad is applied without being applied, or the unevenness is followed. It is possible to separate whether the convex portion is polished and flattened without being followed.

  This represents that local planarization polishing and global uniform polishing can be compatible. By adjusting the Young's modulus and thickness of the flexural deformation sheet and changing the flexural characteristics of the pad, it becomes possible to adjust the critical region of flattening polishing and uniform polishing.

  Based on the above principle, using the fact that the deflection characteristics of the flexural deformation sheet changes rapidly depending on the size of the region, while flattening the unevenness of the wafer in the local portion, about the waviness of the wafer surface, Follow and polish.

  FIG. 8 is an explanatory diagram showing various examples of the configuration of the polishing pad 50. In order to make the bending characteristic uniform and continuous, the bending deformation sheet 52 is composed of a single sheet. On the other hand, the surface layer pad 51 has only a function of holding and polishing the slurry. For this reason, a single continuous sheet may be used as shown in FIG. 8A, but the bending deformation sheet 52 may be attached only to the polishing portion facing the wafer as shown in FIG. 8B. Further, as shown in FIG. 8C, in order to spread the slurry uniformly on the surface layer pad 51, the surface layer pad 51 may be divided, and one sheet between the positions may be bent and the deformation sheet 52 may be pasted one by one. Good. Further, as shown in FIG. 8D, if the surface layer pad 51 is to be segmented, the surface layer pad 51 is previously provided with a groove 53, and the single surface layer pad 51 provided with the groove 53 is bent and deformed. It may be pasted on.

  Using such a mechanism and configuration, it is possible to perform polishing under the following polishing conditions, for example.

  Polishing was performed under such experimental conditions. The convex part having a width of about 100 μm and a step of 0.5 μm was flattened to a step of 0.1 μm or less after being polished by about 0.5 μm. Furthermore, the in-plane uniformity of the wafer polishing rate was as good as 3.2% (1σ).

  On the other hand, the platen 30 is formed in a disc shape, and a rotary shaft 31 is connected to the center of the lower surface thereof. The platen 30 is rotated in the direction of arrow B by driving a motor 32. The wafer surface is polished by pressing the wafer held on the surface of the wafer holding table 20 against the polishing pad 40 on the rotating platen 30 while supplying a slurry containing an abrasive to the polishing pad 50 on the platen 20. Is done.

  FIG. 9 is an explanatory diagram of the platen 30. As described above, the polishing pad 50 is mounted on the platen 30 via the compression deformation plate 40. More specifically, as shown in FIG. Are attached together on the platen 30, and the bending deformation sheet 52 is attached together on the back surface of the surface pad 51 and attached onto the elastic body 41.

  The elastic body 41 is formed of a material having a relatively small compressive deformation, and has a high bending rigidity and a good flattening characteristic. The opposing surface 41s of the elastic body 41 is partitioned by, for example, a groove (not shown), and is formed so that each of them is deformed independently. Also, the opposing surface 41s of the elastic body 41 considers the pressure distribution in advance. It has a convex shape.

  Further, the hard plate 42 affixed to the back surface of the elastic body 41 is affixed to the back surface of the elastic body 41 by means of baking or the like using a stainless or ceramic plate. Then, the elastic body 41 and the hard plate 42 bonded together are placed on the platen 30 and fixed by physical fixing means.

  Here, the bending deformation sheet 52 affixed to the back surface of the surface layer pad 51 is made of a material that does not bend in a narrow area and does not bend in a wide area, for example, a PET (Polyethylene Terephthalate) film. Then, in a state where the surface layer pad 51 and the outer peripheral edge portion of the bending deformation sheet 52 that are bonded together are sandwiched, and the stop ring 60 that is provided on the side surface of the platen 30 is pulled down below the side surface of the platen 30. The polishing pad 50 is lifted and fixed on the compression deformation plate 40 by a lifting mechanism composed of a bracket 51 for positioning and fixing. That is, the outer peripheral edge portions of the surface layer pad 51 and the bending deformation sheet 52 are fixed in a state where the outer peripheral edge portions are pulled down to the lower side of the platen 30. Thereby, the shear stress due to polishing exerted on the polishing pad 40 is supported by the retaining ring 60, and no lateral stress is applied to the compression deformation plate 50.

  In this way, the surface layer pad 51 is attached to the bending deformation sheet 52 to be integrated, and the outer peripheral edge portion is fixed in a pulled down state, so that there is no pressure change associated with the attachment of the surface layer pad 51, and the surface layer pad Even if 51 swells, it is attached to the elastic body 41 without extending. In addition, since the double-sided tape is not interposed between the surface layer pad 51 and the flexurally deformable sheet 52 and the elastic body 41 that are bonded together, a stable pressure distribution can be ensured.

  With the configuration described above, all the problems to be solved by the invention can be solved. That is, since the thermal deformation of the platen 30 is absorbed by the elastic body 41 and the temperature difference between the front surface and the back surface of the platen 30 is not increased, the polishing uniformity within the wafer surface is prevented from greatly deteriorating. it can.

  Problem 2: Since the surface layer pad 51 is affixed on the flexible deformable sheet 52 having a low spreadability, a double-sided tape is not necessary, and the adverse effect on the pressure distribution applied to the wafer surface can be prevented.

  Problem 3: Since the elastic body 41 with the hard plate 41 attached integrally is disposed under the surface layer pad 51 and the flexural deformation sheet 52 attached integrally, the wafer surface is prevented from the gentle waviness of the wafer surface. While the surface layer pad 51 is followed, when pressing with a uniform pressure from the back surface of the wafer, the wafer does not bend on the surface layer pad 51, and a stable and uniform pressure distribution is formed on the wafer. Can do.

  Problem 4: Since the hard plate 41 is integrally attached to the back surface of the elastic body 41 and mounted on the platen 30, even if the platen sheet is an elastic body, there is no change in pressure distribution due to the mounting error of the platen sheet, A stable pressure distribution can be formed when the platen sheet is attached to the platen 30.

  Problem 5: Since the surface of the elastic body 41 is previously formed in a convex shape that takes pressure distribution into account, even if the surface layer pad 51 is completely flat and the wafer is also completely flat, the wafer surface The pressure distribution applied inside can be made uniform.

  Problem 6: Since the surface of the elastic body 41 is segmented and each deforms independently, even if it is a high-density elastic body, it does not rebound due to the pressing pressure, and even pressure is applied to the entire surface of the wafer. Distribution can be given.

  Problem 7: Even when the surface layer 51 has a weak bending rigidity, the elastic body 41 and the hard plate 41 are integrally formed, so that the bending deformation can be suppressed. Even if the thickness of the surface layer is changed by dressing, a stable and uniform pressure distribution can be formed on the wafer.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 10 Polishing apparatus 20 Wafer holder 22 Wafer dent 30 Platen 40 Compression deformation plate 41 Elastic body 42 Hard plate 50 Polishing pad 51 Surface layer pad 52 Deformation deformation sheet 60 Stop ring 61 Bracket

Claims (6)

In a polishing apparatus that performs polishing by relatively sliding a wafer and the polishing pad while dropping and supplying slurry onto the polishing pad,
Using the back surface of the wafer as a reference surface, a wafer holding table to which the entire surface of the wafer is decompressed and flattened,
A compression deformation plate that is laid and fixed on a platen that moves relative to the wafer to form a desired pressure distribution;
A tensioning mechanism for tensioning and fixing the polishing pad on the compression deformation plate;
The polishing pad is provided with a bending deformation sheet laid on the compression deformation plate and displaceable by bending deformation, and a surface layer pad laid on the bending deformation sheet and holding a dropped slurry.
The polishing apparatus having a pressure distribution adjusting function, wherein the surface layer pad is bonded and integrated on the bending deformation sheet . The elastic body on the surface of the compression deformed plate is formed of an elastic material having a small compression set without voids, and the opposing surface facing the polishing pad is segmented,
Compartment facing surface of differentiated elastic body polishing apparatus having a pressure distribution adjustment function according to claim 1, wherein that you modified each independently. The said compression deformation board is equipped with the said elastic body for compressive deformation, and the hard board which fixes this elastic body uniformly over the whole surface, The grinding | polishing which has a pressure distribution adjustment function of Claim 2 characterized by the above-mentioned. apparatus. 4. The polishing apparatus having a pressure distribution adjusting function according to claim 3 , wherein the compression deformation plate is formed so as to be exchangeable integrally with the platen . The polishing apparatus having a pressure distribution adjusting function according to claim 4 , wherein the compression deformation plate has a surface formed in advance in a shape that takes pressure distribution into consideration . The polishing pad is in a region where the unevenness of the wafer surface is flattened, and the deflection deformation amount of the pre-polishing pad is smaller than the compression deformation amount, and the polishing pad deflection deformation follows the waviness of the wafer surface. polishing apparatus having a pressure distribution adjustment function according to claim 1, wherein the amount is characterized in that it is set the rigidity deflection to be greater than the amount of compressive deformation.

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