JP7721382B2 - Polishing pad manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a polishing pad.

In semiconductor manufacturing processes, chemical mechanical polishing (CMP) is used to planarize the surface after insulating film deposition and to form metal wiring. One of the important technologies required for chemical mechanical polishing is polishing endpoint detection, which determines whether the polishing process is complete. For example, over-polishing or under-polishing relative to the target polishing endpoint directly leads to product defects. For this reason, chemical mechanical polishing requires strict control of the amount of polishing by detecting the polishing endpoint.

Chemical mechanical polishing is a complex process, and the polishing speed (polishing rate) varies depending on the operating conditions of the polishing equipment, the quality of consumables (slurry, polishing pads, dressers, etc.), and variations in conditions over time during the polishing process. Furthermore, in recent years, the precision of remaining film thickness and in-plane uniformity required in semiconductor manufacturing processes have become increasingly strict. For these reasons, detecting the polishing endpoint with sufficient accuracy has become more difficult.

The main methods for detecting the polishing endpoint are optical endpoint detection, torque endpoint detection, and eddy current endpoint detection. With optical endpoint detection, the endpoint is detected by irradiating the wafer with light through a transparent window member installed on the polishing pad and monitoring the reflected light.

As an example of a method for manufacturing a polishing pad using this type of optical endpoint detection method, Patent Document 1 discloses a method for manufacturing a polishing pad in which a liner is provided on the bottom surface of a mold to secure a window block, and then a curable material is filled into the mold and allowed to harden.

Japanese Patent Application Laid-Open No. 2013-197597

However, with the method of fixing the window block at the bottom of the mold as in Patent Document 1, if the liner deforms due to heat during curing, the window block cannot be fixed vertically to the mold, which is a problem. Furthermore, because the window block is fixed directly to the liner, it is difficult to reuse, which raises manufacturing costs.

Furthermore, in Patent Document 1, a window adhesive is used to bond the window block to the top surface of the liner, but with this type of bonding method, when the hardenable material is loaded into the mold cavity, there is a risk that the window block may tilt or become misaligned (hereinafter collectively referred to as "misalignment, etc.") due to the flow of the hardenable material or the expansion or contraction of the hardenable material as it hardens.

In addition, when placing a relatively small component for the endpoint detection window in an accurate position, the window position needs to be fine-tuned, but if the window is fixed using window adhesive, the position cannot be adjusted thereafter, which reduces the manufacturing yield of good products.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a method for manufacturing a polishing pad that can suppress misalignment of the end-point detection window component while also allowing the position of the end-point detection window component to be easily adjusted.

That is, the present invention is as follows.
[1]
A method for manufacturing a polishing pad having a polishing layer with an endpoint detection window, comprising:
a curing step of fixing an end point detection window member in a mold and curing the curable resin in contact with the end point detection window member to form a resin sheet incorporating the end point detection window member;
a slicing step of slicing the resin sheet to form an abrasive layer,
In the curing step, the end-point detection window member is clamped by clamping portions of a position fixing jig installed on the upper part of the mold, thereby being suspended and fixed.
A method for manufacturing a polishing pad.
[2]
In the curing step, after filling the mold with a curable resin, the end-point detection window member is brought into contact with the curable resin to cure the curable resin.
A method for producing the polishing pad according to [1].
[3]
In the curing step, the end point detection window member is fixed in the mold, and then a curable resin is filled in the mold and cured.
A method for producing the polishing pad according to [1].
[4]
the position fixing jig has a through hole through which the end point detection window member is inserted,
the clamping portion clamps the end-point detection window member inserted into the through-hole;
[1] - [3] The method for producing a polishing pad according to any one of [1] to [3].
[5]
the clamping portion detachably clamps the end-point detection window member;
[4] A method for producing a polishing pad according to any one of [1] to [4].
[6]
the position fixing jig has a first fitting portion that fits with the upper part of the mold;
[1] to [5], the method for producing a polishing pad according to any one of [1] to [5].
[7]
the mold has a second fitting portion that fits with the position fixing jig;
[6] A method for producing a polishing pad according to any one of [1] to [6].
[8]
a groove forming step of forming grooves on the polishing surface of the polishing layer,
No groove processing is performed on the exposed portion of the end point detection window member before the groove forming step.
[1] to [7], the method for producing a polishing pad according to any one of [1] to [7].
[9]
a lamination step of laminating a base layer and/or a cushion layer on the surface of the polishing layer opposite to the polishing surface,
[1] to [8], the method for producing a polishing pad according to any one of [1] to [8].

The present invention provides a method for manufacturing a polishing pad that can suppress misalignment of the end point detection window component while also allowing for easy adjustment of the position of the end point detection window component.

10 is a perspective view showing an example in which the end-point detection window member of the present embodiment is clamped by a clamping portion. FIG. 10 is a perspective view showing another example in which the end-point detection window member of the present embodiment is clamped by the clamping portion. FIG. FIG. 2 is a top view showing one embodiment of a combination of a mold and a position fixing jig for producing a resin sheet used in this embodiment. FIG. 10 is a top view showing another embodiment in which a mold and a position fixing jig are combined to produce a resin sheet used in this embodiment. 4 is a cross-sectional view showing the A-A' cross section of the mold shown in FIG. 3 before the hardening resin is injected. 4 is a cross-sectional view showing the A-A' cross section of the mold shown in FIG. 3 after the hardening resin is injected. FIG. 3 is a top view showing the resin sheet obtained after the curing process. 10 is a cross-sectional view of the resin sheet obtained after the curing process, near the end point detection window. FIG. 1 is a schematic perspective view of a polishing pad according to an embodiment of the present invention. 3 is a schematic cross-sectional view of an end point detection window portion of the polishing pad of the present embodiment. FIG.

The following describes in detail an embodiment of the present invention (hereinafter referred to as "the present embodiment"), with reference to the drawings as necessary. However, the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. Note that identical elements throughout the drawings will be given the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

1. Method for Manufacturing Polishing Pad The method for manufacturing a polishing pad of this embodiment includes a curing step in which an endpoint detection window member is fixed in a mold and a curable resin is cured while in contact with the endpoint detection window member to form a resin sheet incorporating the endpoint detection window member, and a slicing step in which the resin sheet is sliced to form a polishing layer. In the curing step, the endpoint detection window member is clamped by a clamping portion of a position fixing jig installed above the mold, and is thereby suspended and fixed, thereby manufacturing a polishing pad having a polishing layer with an endpoint detection window.

In this way, by clamping the endpoint detection window member with the clamping portion of the position fixing jig installed on the top of the mold, the endpoint detection window member can be fixed more firmly than with adhesives, etc. This further reduces misalignment of the endpoint detection window member due to the flow of the curable resin or the expansion or contraction of the curable material when curing. Furthermore, while the endpoint detection window member may be fixed at an angle when fixed with adhesives, etc., by clamping the endpoint detection window member with the clamping portion, it can be fixed vertically.

Furthermore, when the endpoint detection window member is fixed to the bottom surface of the mold with adhesive or the like, its position cannot be adjusted once it is fixed. However, by suspending and fixing the endpoint detection window member using a clamping unit, the endpoint detection window member can be easily removed. The clamping unit can be loosened and the embedded position of the endpoint detection window member can be fine-tuned until the curable resin hardens. Because endpoint detection windows typically do not have polishing capabilities, it is preferable to make the size of the window placed in the polishing pad as small as possible. To accurately deliver transmitted light to the detector portion of the polishing device through a small endpoint detection window, the window must be precisely positioned in the same location on each polishing pad. Therefore, enabling such fine adjustments can also improve the yield rate. After the curable resin hardens, the clamping unit can be loosened and the endpoint detection window member removed from the clamping unit, allowing the positioning jig and the resulting resin sheet to be separated.

Furthermore, because the component for the endpoint detection window is attached to the position fixing jig rather than the mold, there is no need to process the mold itself, and conventional ones can be used as is. Furthermore, the position fixing jig can be used multiple times, so it does not need to be disposable like a liner.

1.1. Curing Step The curing step is a step in which an endpoint detection window member is fixed in a mold, and the curable resin is cured while in contact with the endpoint detection window member to form a resin sheet incorporating the endpoint detection window member.

1.1.1 End Point Detection Window Member First, prior to the curing step, an end point detection window member 10 is prepared. The shape of the end point detection window member 10 is not particularly limited, but examples thereof include a rectangular parallelepiped and a cylindrical shape, as shown in Figures 1 and 2.

As shown in FIG. 1, the rectangular parallelepiped end point detection window member 10 has sides that are easy to clamp, allowing it to be more stably fixed to the position fixing jig 30. The shape of the rectangular parallelepiped end point detection window member 10 is not particularly limited as long as it is configured as a window material of the required size, but for example, the end face in the hanging direction may have a convex shape. Such a convex shape makes it easier for the curable resin to flow between the end face of the end point detection window member 10 and the bottom surface 21 of the mold 20, preventing air bubbles from being trapped in the curable resin.

As shown in FIG. 2, the cylindrical end point detection window member 10 can have, for example, a pillar portion 11 and a base portion 12. Here, the pillar portion 11 is embedded in the resin sheet 50 after the curing process to form the end point detection window 51. The cross-sectional shape of the pillar portion 11 is not particularly limited and may be circular or polygonal, and the tip of the pillar portion 11 may have a convex shape. Furthermore, the base portion 12 may be configured to be wider than the hole diameter of the clamping portion 31 of the position fixing jig 30. In this way, when the end point detection window member 10 is inserted from above into the clamping portion 31 of the position fixing jig 30, it is engaged by the base portion 12, and the cylindrical end point detection window member 10 is fixed in place and will not fall off.

In this way, by configuring the cylindrical endpoint detection window member 10 to have a shape including a pillar portion 11 and a base portion 12, the pillar portion 11 can be made relatively small within the range necessary for the endpoint detection window, while the base portion 12 can further prevent it from falling off. This tends to prevent the endpoint detection window member 10 from being displaced or tilted due to the resin injected during the curing process or the resin being cured. Furthermore, because the pillar portion 11 can be configured relatively small within the range necessary for the endpoint detection window, the impact of embedding the endpoint detection window on the polishing characteristics of the polishing pad can be further reduced. Note that the shape of the endpoint detection window member 10 is not limited to that shown in Figure 2; the cylindrical endpoint detection window member 10 may have only the pillar portion 11 without the base portion 12.

The endpoint detection window member 10 can be produced, for example, by injecting resin into a mold (not shown), without any particular limitation. After the endpoint detection window member 10 is removed from the mold, the sides are preferably treated with sandpaper or a solvent. This allows the release agent to be removed if it is present on the endpoint detection window member 10. Furthermore, roughening the sides with sandpaper tends to improve adhesion between the resin sheet 50 and the endpoint detection window member 10 (endpoint detection window 51) when the endpoint detection window member 10 is embedded in the resin sheet 50.

1.1.2 Position Fixing Jig The position fixing jig 30 is not particularly limited as long as it has a clamping portion 31, can be installed above the mold 20, and can suspend and fix the end point detection window member 10 by the clamping portion 31. As shown in Figures 5 and 6, the end point detection window member 10 is suspended and fixed by the clamping portion 31 of this position fixing jig 30.

For example, if the end point detection window members 10 are fixed to the bottom surface of the mold 20, it is difficult to change the number or position of the end point detection window members 10 after the mold is filled with curable resin. On the other hand, if the end point detection window members 10 are fixed by hanging them, as in this embodiment, it is easy to change the position or number of the end point detection window members 10 even after the mold 20 has been filled with curable resin, as long as it has not yet hardened.

Furthermore, there is no need to make any other modifications to the mold itself, such as to the bottom of the mold 20, in order to secure the end point detection window member 10; the mold 20 can be the same as the one used to manufacture polishing pads that do not have an end point detection window.

Furthermore, the clamping portion 31 is not particularly limited as long as it clamps and secures the endpoint detection window member 10. By clamping the sides of the endpoint detection window member 10 with such clamping portion 31, the endpoint detection window member 10 can be suspended and secured vertically, and is less likely to shift in position even when a force is applied in the planar direction. This prevents the endpoint detection window member 10 from failing to function as an endpoint detection window if it is secured at an angle rather than vertically, or from being pushed out of position by the flow of the curable material or the expansion or contraction of the curable material as it hardens. This effect is particularly pronounced compared to methods in which the endpoint detection window member 10 is secured on only one side with, for example, an adhesive.

Furthermore, by using the clamping unit 31, there is no need to use a fixing means such as an adhesive, and the endpoint detection window member 10 can be easily attached and detached. For example, if an adhesive or the like is used, there is a concern that misalignment or detachment may occur if the adhesive strength is weak, and if the adhesive strength is strong, it may be difficult to remove the endpoint detection window member 10 from the position fixing jig 30 after the curing process. In contrast, when using the clamping unit 31, it is sufficient to clamp the endpoint detection window member 10 from at least one direction, and by weakening the clamping force, it can be easily attached and detached. Furthermore, when using adhesive, it is necessary to sand the adhesive surface of the endpoint detection window member 10 with sandpaper or the like to make it flat, but using the clamping unit 31 eliminates such measures.

The clamping portion 31 is not particularly limited as long as it clamps and secures the end point detection window member 10 as described above. It may have one or more members that clamp the end point detection window member 10, and may also have an adjustment portion 32 for adjusting the clamping force. Among these, a clamping portion 31 configured to clamp the end point detection window member 10 simply by fitting it in is preferred from the standpoint of ease of attachment and detachment, and a clamping portion 31 with an adjustment portion 32 is preferred because the strength of the fixation can be adjusted.

Such an adjustment unit 32 may be, for example, a screw or spring that tightens multiple members (clamping units 31) that clamp the end point detection window member 10, as shown in Figure 1. In Figure 1, the clamping units 31, which consist of two members, are connected via the adjustment unit 32 (screw), and the adjustment unit 32 makes it possible to adjust the distance between the clamping units 31, which consist of two members. As a result, by tightening the adjustment unit 32 to shorten the distance between the clamping units 31, the sides of the end point detection window member 10 are pressed down, and the clamping force is adjusted.

The adjustment portion 32 may also be, for example, a screw or spring that tightens the end point detection window member 10 together with the clamping portion 31, as shown in Figure 2. In Figure 2, the bottom of the adjustment portion 32 (screw) that penetrates from the side of the clamping portion 31 presses against the side of the end point detection window member 10, thereby adjusting the clamping force by the pressing force between the inner wall of the clamping portion 31 and the bottom of the adjustment portion 32 (screw).

The configuration of the clamping unit 31 and the adjustment unit 32 is not limited to the above, and they can have any other structure as long as they are configured to be able to increase or decrease the clamping force.

The position fixing jig 30 may have a through hole 33 through which the end point detection window member 10 is inserted, and in this case, the clamping portion 31 may clamp the end point detection window member 10 inserted into the through hole 33. By inserting the end point detection window member 10 into the through hole 33 pre-formed in the position fixing jig 30 and clamping it in this way, positioning can be easily performed according to the through hole 33.

The clamping portion 31 can clamp the end point detection window member 10 for easier detachment. This makes it easier to remove the end point detection window member 10, and the embedding position of the end point detection window member 10 can be fine-tuned by loosening the clamping portion 31 until the curable resin hardens. This fine adjustment can also improve manufacturing yield. Furthermore, after the curable resin hardens, the clamping portion 31 can be loosened and the end point detection window member 10 can be removed from the clamping portion 31, allowing the position fixing jig 30 and the resulting resin sheet 50 to be separated.

Figures 3 and 4 show top views of a mold 20 for producing a resin sheet, and Figure 5 shows a cross-sectional view taken along line A-A' in Figure 3 before the curable resin is injected into the mold 20. The mold 20 shown in Figures 3 to 5 includes a position fixing jig 30 that fixes the end point detection window member 10 of the embodiment shown in Figure 2 using the adjustment unit 32 of the embodiment shown in Figure 4. As shown in Figures 3 and 5, the position fixing jig 30 is installed above the mold 20, and the end point detection window member 10 is clamped by the clamping unit 31 of the position fixing jig 30, thereby hanging and fixed vertically downward.

The shape of the mold 20 is not particularly limited, but it can be, for example, a flat mold for forming a resin sheet, or a rectangular mold for forming a resin block from which a resin sheet is cut. The position fixing jig 30 is fixed in contact with the side wall 22 so as to cover the upper part of the mold 20.

The portion of the position fixing jig 30 that comes into contact with the mold 20 may have an uneven shape (first fitting portion) that can fit with the top of the mold 20. The portion of the mold 20 that comes into contact with the position fixing jig 30 may also have an uneven shape (second fitting portion) that can fit with the position fixing jig 30. This makes it easier to position the position fixing jig 30 when installing it on the mold 20, and tends to prevent the embedded position of the endpoint detection window member 10 from shifting during each curing process.

The material of the position fixing jig 30 is not particularly limited, but it may be a heat-resistant material that will not deform even in the heat of the hardening process, such as aluminum alloy or stainless steel.

1.1.3. Curable Resin In the curing process, the endpoint detection window member 10 is fixed in the mold 20 as described above, and the curable resin 40 is cured while in contact with the endpoint detection window member 10 to form a resin sheet 50 incorporating the endpoint detection window member 10 (endpoint detection window 51). Figure 4 shows a cross-sectional view of A-A' in Figure 2 after the curable resin has been injected into the mold 20.

In this embodiment, there are no particular limitations as long as the curable resin 40 is cured while in contact with the end point detection window member 10. As shown in Figure 3, the end point detection window member 10 may be fixed within the mold 20, and then the mold 20 may be filled with the curable resin 40 and the curable resin 40 may be cured. Alternatively, the mold 20 may be filled with the curable resin 40, and then the end point detection window member 10 may be brought into contact with the curable resin, and then the curable resin 40 may be cured.

The curable resin is not particularly limited, but examples include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more. Such polyurethane resins can be synthesized from polyisocyanate and polyol.

1.2. Slicing Process The slicing process is a process of slicing the resin sheet to form the polishing layer. Figures 7 and 8 show a top view and a cross-sectional view of the resin sheet 50 obtained after the curing process, by removing it from the mold 20 and removing the base portion 12. As shown in Figures 7 and 8, the resin sheet has an endpoint detection window member embedded therein.

The slicing method is not particularly limited, but one example is to cut a resin sheet like the one shown in Figures 7 and 8 in the surface direction to create a polishing pad of any desired thickness. Also, as shown in Figure 9, a rectangular polishing pad may be cut into a circular shape.

1.3 Groove Forming Step The method for manufacturing a polishing pad of this embodiment may optionally include a groove forming step of forming grooves on the polishing surface of the polishing layer (see FIG. 10). Note that it is preferable not to perform groove processing on the exposed portion of the end point detection window member, as this would interfere with optical endpoint detection.

1.4. Other Steps The method for producing a polishing pad of this embodiment may, if necessary, include a lamination step of laminating a base layer and/or a cushion layer on the surface of the polishing layer opposite the polishing surface.

2. Polishing Pad Fig. 9 shows a schematic perspective view of the polishing pad of this embodiment, and Fig. 10 shows a cross-sectional view of the periphery of the endpoint detection window 51 in Fig. 9. As shown in Fig. 10, the polishing pad of this embodiment has a resin sheet 50 (polishing layer) and an endpoint detection window 51, and may have a cushion layer 52 on the side opposite the polishing surface 50a, as necessary.

As shown in FIG. 10, an adhesive layer 53 may be provided between the resin sheet 50 (polishing layer) and the cushion layer 52, and an adhesive layer 54 may be provided on the surface of the cushion layer 52. The polishing surface 50a of the polishing pad of this embodiment may be flat or may have an uneven surface with grooves 55 formed therein, as shown in FIG. 10. The grooves 55 may be formed in various shapes, such as multiple concentric circles, a grid pattern, or a radial pattern, either alone or in combination.

The end point detection window 51 is a transparent member provided in an opening in the resin sheet 50 (polishing layer), and serves as a transmission path for light from the film thickness detection sensor during optical end point detection. In this embodiment, the end point detection window is circular, but it may also be square, rectangular, polygonal, elliptical, or other shapes as needed.

The resin sheet 50 (polishing layer) is not particularly limited, but for example, a polyurethane sheet can be used. This polyurethane sheet has an opening in which an end-point detection window is embedded. The location of the opening is not particularly limited, but it is preferable to provide it at a radial position corresponding to the film thickness detection sensor installed on the table of the polishing apparatus. Furthermore, the number of openings is not particularly limited, but it is preferable to have multiple openings at similar radial positions so that the window passes over the film thickness detection sensor multiple times as the polishing pad attached to the table rotates once.

The polishing pad manufacturing method of the present invention has industrial applicability as an efficient method for manufacturing polishing pads suitable for optical endpoint detection methods.

10...End point detection window member, 11...Columnar portion, 12...Pedestal portion, 20...Mold, 21...Bottom surface, 22...Side wall, 30...Position fixing jig, 31...Cleaning portion, 32...Adjustment portion, 40...Curable resin, 50...Resin sheet, 50a...Polished surface, 51...End point detection window, 52...Cushion layer, 53...Adhesive layer, 54...Adhesive layer, 55...Groove

Claims (8)

A method for manufacturing a polishing pad having a polishing layer with an endpoint detection window, comprising:
a curing step of fixing an end point detection window member in a mold and curing the curable resin in contact with the end point detection window member to form a resin sheet incorporating the end point detection window member;
a slicing step of slicing the resin sheet to form an abrasive layer,
In the curing step, the end-point detection window member is clamped by clamping portions of a position fixing jig installed on the upper part of the mold, thereby being suspended and fixed ;
the position fixing jig has a through hole through which the end point detection window member is inserted,
the clamping portion clamps the end-point detection window member inserted into the through-hole ;
A method for manufacturing a polishing pad. In the curing step, after filling the mold with a curable resin, the end-point detection window member is brought into contact with the curable resin to cure the curable resin.
The method for producing the polishing pad according to claim 1 . In the curing step, the end point detection window member is fixed in the mold, and then a curable resin is filled in the mold and cured.
The method for producing the polishing pad according to claim 1 . the clamping portion detachably clamps the end-point detection window member;
The method for producing the polishing pad according to any one of claims 1 to 3 . the position fixing jig has a first fitting portion that fits with the upper part of the mold;
A method for producing a polishing pad according to any one of claims 1 to 4 . the mold has a second fitting portion that fits with the position fixing jig;
A method for producing a polishing pad according to any one of claims 1 to 5 . a groove forming step of forming grooves on the polishing surface of the polishing layer,
No groove processing is performed on the exposed portion of the end point detection window member before the groove forming step.
A method for producing a polishing pad according to any one of claims 1 to 6 . a lamination step of laminating a base layer and/or a cushion layer on the surface of the polishing layer opposite to the polishing surface,
A method for producing a polishing pad according to any one of claims 1 to 7 .