JP4570084B2 - Substrate bonding method - Google Patents

Description

The present invention relates to an adhesive sheet interposed therebetween bonding two substrates laminating a substrate Way Method.

  In recent years, electronic devices incorporating a semiconductor device such as a mobile phone or a personal computer have been rapidly reduced in thickness and size, and accordingly, semiconductor packages and eventually semiconductor wafers have also been reduced in thickness.

  In general, a semiconductor wafer (hereinafter simply referred to as a “wafer”) is formed by forming a large number of elements on the wafer, and then grinding the back surface of the wafer in a back grinding process with an adhesive tape for protecting the element surface being applied to the wafer surface. Then, it is divided into each element in a dicing process. However, in recent years, it has been desired to reduce the wafer thickness to 100 μm or less.

  Such thinly back-ground wafers are very likely to warp due to residual stress at the time of device formation and residual stress due to grinding, and are in a fragile state, and handling properties such as conveyance between various processes are extremely poor. It has become.

Therefore, a means for reinforcing the wafer by bonding a base such as a dummy wafer or a glass plate to the wafer via an adhesive tape has been proposed. As an example, a wafer with an adhesive tape attached to the upper surface is placed on and fixed to a holding table, and a base made of a glass plate or the like (corresponding to the second substrate in the present invention) is supported above the wafer. The base is locked and held at the upper end of the part in an inclined posture, and the press roller is rolled and moved directly to the surface of the base that is held inclined, and the base support part is lowered in accordance with the movement, thereby Some are configured to be attached to a wafer (see, for example, Patent Document 1).
JP 2000-349136 A

  The above-described conventional substrate laminating apparatus employs a structure in which the reinforcing base is locked and held at the upper end of the cylindrical base supporting portion surrounding the semiconductor wafer. However, the outer peripheral part of the base protrudes slightly from the outer periphery of the semiconductor wafer reinforced by bonding the base, and the protrusion of the base is There is a risk of hindering subsequent processing.

  Further, since the rolling movement is performed while directly pressing the press roller against the surface of the semiconductor wafer, there is a possibility that the semiconductor wafer is forcibly bent and damaged.

The present invention has been made in view of such circumstances, and a substrate for reinforcement having the same diameter or smaller than that can be bonded to a substrate such as a semiconductor wafer, which is also effective for downsizing the apparatus. next, and aims to provide a substrate lamination way method can be eliminated damage to the semiconductor wafer.

The present invention has the following configuration in order to achieve the above object.
The first invention is a substrate laminating method in which a double-sided adhesive sheet is interposed to laminate two substrates.
A process of attaching a double-sided adhesive sheet with a separator on the surface of the first substrate;
Placing and aligning the second substrate on the separator upper surface of the double-sided adhesive sheet;
The pressure-sensitive adhesive surface of a support sheet having a pressure-sensitive adhesive surface weaker than the double-sided adhesive sheet is stretched on a pair of sheet clamps so as to face the second substrate, and a sticking roller is rolled on the surface of the support sheet. Pasting the second substrate on the support sheet, and placing the second substrate opposite the first substrate with a gap;
Removing the separator from the double-sided pressure-sensitive adhesive sheet on the first substrate;
The process of applying the second substrate to the double-sided adhesive sheet applied to the first substrate while pressing the application roller on the non- adhesive surface of the support sheet under reduced pressure, and peeling the second substrate from the support sheet ;
It is characterized by comprising.

  (Operation and Effect) According to the above method, first, the double-sided adhesive sheet is bonded onto the surface of the first substrate, and then the second substrate is bonded to the support sheet. Thereafter, the second substrate attached to and supported by the support sheet is moved by pressing the attaching means to the surface of the support sheet in a state where the support sheet is positioned on the surface of the first substrate under a reduced pressure state. Affix to the first substrate. This completes the bonding process between the first substrate and the second substrate.

  In this case, the second substrate disposed opposite to the first substrate is not supported by mechanically locking and supporting the periphery of the second substrate. Depending on the diameter, the restriction of the area required for the structure for locking and holding the outer periphery can be eliminated.

  Therefore, according to the method of the present invention, a second substrate having the same diameter as the first substrate or a smaller diameter than the first substrate can be bonded, and the second substrate can be bonded without protruding from the first substrate. The subsequent processing can be performed in a state where there is no protrusion.

  Further, since the second substrate is pressed through the support sheet, the pressing stress by the attaching means is absorbed by the support sheet, and the second substrate is not excessively bent. As a result, the second substrate is also damaged. Can be prevented. In addition, since the bonding process is performed under a reduced pressure state, the adhesive area is expanded by the pressure-sensitive adhesive's restoring force when it is returned from the reduced pressure state to the atmospheric state without causing air bubbles in the bonding surface. The bonding between the first substrate and the second substrate can be strengthened, and the bonding process can be performed with few defective products.

  Furthermore, it is not necessary to provide a large mechanism for supporting the second substrate outside the first substrate, which contributes to the miniaturization of the entire apparatus.

  According to a second invention, in the substrate bonding method of the first invention, at least one of the first substrate and the second substrate is a semiconductor wafer.

  (Operation / Effect) The above method is preferably applied to a semiconductor wafer thinly processed by back grinding. That is, it is suitable for bonding a reinforcing substrate to a semiconductor wafer before back grinding.

According to the substrate lamination Way Method according to the invention, so that paste the second substrate affixed to the adhesive surface while pressing the adherend surface of the supporting sheet to the double-sided adhesive sheet adhered to the first substrate Thus, the periphery of the second substrate can be configured not to be mechanically locked and held. Therefore, it is possible to eliminate the restriction of the area required for the configuration for locking and holding the outer periphery depending on the diameter of the second substrate.

  Further, since the second substrate is pressed through the support sheet, the pressing stress by the attaching means is efficiently absorbed and dispersed in the support sheet, and the second substrate is not excessively bent. As a result, the second substrate It is also possible to avoid damage to the machine. In addition, since the bonding process is performed under a reduced pressure state, the adhesive area is expanded by the pressure-sensitive adhesive's restoring force when it is returned from the reduced pressure state to the atmospheric state without causing air bubbles in the bonding surface. The bonding between the first substrate and the second substrate can be strengthened, and the bonding process can be performed with few defective products.

  Furthermore, it is not necessary to provide a large mechanism for supporting the second substrate outside the first substrate, which contributes to the miniaturization of the entire apparatus.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a longitudinal front view of a basic structure of a substrate bonding apparatus for executing the substrate bonding method according to the present invention, and FIG. 2 shows a plan view thereof.

  The substrate laminating apparatus of the present embodiment uses a double-sided adhesive sheet S to a reinforcing substrate W2 made of a glass plate as a second substrate on the surface of a semiconductor wafer (hereinafter simply referred to as “wafer”) W1 as a first substrate. The laminating mechanism 2 is housed in a vacuum chamber 1 that can be opened and closed.

  The decompression chamber 1 is composed of a rectangular box-shaped main case 1a that is open at the top and a cover case 1b that is connected to the main case 1a so as to be swingable and openable. The cover case 1b is tightly closed to the main case 1a. Thus, the vacuum pump 10 is operated to evacuate and decompress the inside of the chamber.

  The laminating mechanism 2 is provided on the main case side, a holding table 3 for horizontally mounting and holding the wafer W1, and a pair of sheets erected at positions facing the front and rear outside the holding table 3. Clamps 4 and 5 and a laminating roller 6 that is horizontally supported and driven forward and backward between the sheet clamps 4 and 5 are provided. For convenience, the right side of the figure is the front and the left side is the rear.

  The holding table 3 has an upper surface configured as a vacuum suction surface, and can hold the wafer W1 positioned and placed by suction. Further, as will be described later, a heater 7 is embedded in the holding table 3 for heating and softening the adhesive of the double-sided adhesive sheet S attached to the wafer W1 to enhance the adhesiveness. The heater 7 corresponds to the heating means of the present invention.

  As shown in FIG. 9, the sheet clamps 4 and 5 are used to hold the front and rear ends of the support sheet T to which the reinforcing substrate W <b> 2 is adhered and held, and to float and stretch along the upper side of the holding table 3. In the upper part, sheet holding portions 4a and 5a for holding and supporting the front and rear ends of the support sheet T are provided. Here, while the rear (left in the figure) seat clamp 5 is fixedly arranged, the front (right in the figure) seat clamp 4 can swing back and forth around a fulcrum x at its lower end. In addition, a torsion spring (not shown) is assembled to the fulcrum x so that the seat clamp 4 tilts backward when a moment greater than the rearward setting is applied. Yes.

  Returning to FIG. 1, the laminating roller 6 is configured by covering an outer periphery of a metal roller with an elastic material such as silicon rubber, and a movable base 8 disposed in the main case 1 a so as to be movable back and forth and ascend and descend. It is supported horizontally at the bottom of the left and right. Further, the laminating roller 6 can be driven to rotate by a motor 9, and when laminating operation for horizontally moving the laminating roller 6 forward, it is driven to rotate forward at the same peripheral speed as the forward movement speed. Yes.

  Although the detailed structure is not shown, the movable base 8 is supported by a lifting frame that is driven up and down by a pulse motor or the like so as to be horizontally movable back and forth via a guide shaft, and is a belt type or screw type. The laminating roller 6 is moved back and forth horizontally by the horizontal driving means, and the laminating roller 6 is moved back and forth horizontally by moving the movable table 8 back and forth, and the laminating roller 6 is moved up and down by raising and lowering a lifting frame (not shown). It is like that.

  In addition, the laminating roller 6 can be driven to rotate by a motor 9 and is driven to rotate forward at the same peripheral speed as the forward movement speed during the laminating operation for moving the laminating roller 6 forward. .

  The board | substrate bonding procedure using the bonding mechanism 2 comprised in this way is demonstrated below with reference to FIG. 3 thru | or FIG.

  (1) First, as shown in FIG. 3, the cover case 1 b is lifted to open the decompression chamber 1, and the wafer W1 before the back grinding process is placed on the upper surface of the holding table 3 so that the surface that is the element formation surface faces upward. Place it in position and hold it by suction. At this point, the laminating roller 6 is waiting at the previous origin position.

  (2) Next, as shown in FIG. 4, a double-sided adhesive sheet S with a separator cut out in substantially the same shape as the wafer W1 is attached to the surface of the wafer W1 sucked and held on the holding table 3 with a separator st. Paste the top side.

  (3) Next, as shown in FIG. 5, the reinforcing substrate W2 formed in substantially the same shape as the wafer W1 is positioned and mounted on the upper surface of the separator st of the double-sided adhesive sheet S bonded to the wafer W1.

  (4) Next, as shown in FIG. 6, the supporting sheet T is stretched across the front and rear sheet clamps 4 and 5 with the adhesive surface facing downward. The support sheet T used here has an adhesive force capable of adhering and holding the reinforcing substrate W2 on the lower surface, and one having a weaker adhesive force than the double-sided adhesive sheet S is used.

  (5) Next, as shown in FIG. 7, the laminating roller 6 is lowered until it comes into contact with the upper surface of the support sheet T, and then moved forward while being driven to rotate, and the reinforcing substrate W <b> 2 is placed on the lower surface of the support sheet T. Paste.

  (6) When the attachment of the reinforcing substrate W2 to the support sheet T is completed, as shown in FIG. 8, the laminating roller 6 is retracted, and the sheet holding portion 4a in the front sheet clamp 4 is opened, and the support sheet T is turned up from the front end side, and the reinforcing substrate W2 is temporarily withdrawn upward, and the exposed separator st of the double-sided adhesive sheet S is peeled and removed.

(7) Next, as shown in FIG. 9, the turned up support sheet T is lowered again and supported by the front sheet clamp 4. Thereby, the reinforcing substrate W2 adhered and held on the lower surface of the support sheet T is 0.5 to 2.0 mm, preferably 0.1 to 5.0 mm, with respect to the double-sided adhesive sheet S adhered to the surface of the wafer W1. It is opposed with a small gap. In this state, the cover case 1b is closed and the vacuum chamber 1 is evacuated, and the heater 7 is turned on to heat the holding table 3 to soften the adhesive of the double-sided adhesive sheet S.

  When the pressure in the chamber is reduced to 65 kPa or less, preferably 10 kPa or less, more preferably 0.1 kPa or less, as shown in FIG. 10, the laminating roller 6 is driven forward to rotate along the upper surface of the support sheet T again. The reinforcing substrate W2 adhered and supported on the lower surface of the support sheet T is sequentially bonded to the double-sided adhesive sheet S from the rear end to the front end.

  In this case, since the rotation driving speed is controlled so that the peripheral speed of the laminating roller 6 that is driven to rotate coincides with the roller forward movement speed, it is avoided that the drag force in the surface direction acts on the support sheet T. Is done.

  Further, as the advancing movement of the laminating roller 6 progresses, the tension of the support sheet T increases, and the rearward moment acting on the front sheet clamp 4 gradually increases due to this tension. As shown in FIG. When the tension becomes larger than the set value, the front sheet clamp 4 is tilted rearward against its elastic holding force, and it is avoided that excessive tension acts on the support sheet T to cause elongation. Therefore, it is possible to avoid the stress due to the pressing force by the laminating roller 6 from being efficiently absorbed by the support sheet, and the reinforcing substrate W2 from being bent and damaged.

  (8) When the above processing is completed and the laminating roller 6 is retracted, the support sheet T is restored and floated, and the wafer W1 to which the reinforcing substrate W2 is bonded is placed on the holding table 3 as shown in FIG. Left behind. Here, after the inside of the chamber is returned to the atmospheric pressure, the cover case 1b is opened, the sheet holding by the front sheet clamp 4 is released, the support sheet T is turned up and retracted from the front end side, and the reinforcing substrate W2 is retracted. Is unloaded from the holding table 3.

  Thus, one bonding process is completed, a new wafer W1 is loaded, and the above processes are sequentially repeated. The support sheet T may be replaced with a new one for each bonding process, but can be repeatedly used until the adhesive strength is reduced.

  Hereinafter, preferred embodiments for performing good substrate bonding will be described.

  (A) The 2nd board | substrate W2 as a board | substrate for reinforcement can use metal plates, such as various inorganic wafers, such as a silicon | silicone, quartz, and a sapphire other than a glass plate, and a stainless steel plate. The thickness is 1500 μm or less, preferably 1000 μm or less, although it depends on the rigidity. Further, the amount of bending of the reinforcing substrate when bonded and pressed through the bonding roller is 0.2 mm or more, preferably 0.5 to 10 mm, more preferably 1 to 5 mm. If the amount of deflection is 0.2 mm or less, self-adhesion may proceed due to the wettability of the double-sided adhesive sheet, and if the amount of deflection is too large, the reinforcing substrate itself tends to warp, which is not preferable. .

  (B) The pressure-sensitive adhesive, soluble pressure-sensitive adhesive, thermosetting pressure-sensitive adhesive, thermoplastic pressure-sensitive adhesive, radiation curable pressure-sensitive adhesive, heat-peelable pressure-sensitive adhesive, etc. An agent can be used, but when it is desired to peel the wafer without damage after the back surface grinding, a radiation curable pressure sensitive adhesive or a heat peelable pressure sensitive adhesive is preferred.

(C) The supporting sheet T is desirably one having as little elongation as possible, that is, one having a high Young's modulus, and is 200 kg / mm ² or more, preferably 250 kg / mm ² or more, more preferably 350 kg / mm ² or more. Should be used. Examples of the base material of the support sheet having such performance include a plastic sheet, paper, and metal foil, and the plastic sheet is preferable in terms of processability and cost. Examples of the material for the plastic sheet include polyimide, polyamide, polyethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, and polyphenyl sulfate. Moreover, as an adhesive applied to the plastic sheet, a general-purpose material such as rubber, acrylic, or silicone can be used, and is approximately 1.5 N / 10 mm, preferably about 2.0 to 8.0 N / 10 mm. If the adhesive strength is, the retention property of the reinforcing substrate in the pasting process and the peelability from the reinforcing substrate after the pasting process are suitably exhibited.

  (D) As the first substrate W1 to which the second substrate W2 is bonded for reinforcement, a circuit substrate made of plastic ceramic, metal, or a compound wafer such as gallium arsenide or gallium phosphide is conceivable in addition to the silicon semiconductor wafer. The size and shape are arbitrary.

  As described above, the reinforcing substrate W2 attached to the adhesive surface is attached to the double-sided adhesive sheet S attached to the wafer W1 while rolling the attaching roller on the upper surface of the support sheet T. By configuring, it is not necessary to lock and hold the peripheral edge of the diameter of the reinforcing substrate W2, so that the apparatus can be downsized.

  In addition, when the reinforcing substrate W2 is pasted, the sheet clamp 5 is configured to tilt toward the rear when a moment more than the setting acts on the rear of the pasting roller 6, so that the pressing by the pasting roller 6 is performed. The stress is efficiently absorbed and dispersed in the support sheet T and does not act directly on the reinforcing substrate W2. Therefore, it is possible to avoid the reinforcing substrate W2 from being bent or damaged.

  Furthermore, since both substrates W1 and W2 are bonded together in a substantially vacuum state by reducing the pressure, it is possible to eliminate air entrapment at the interface, and the pressure-sensitive adhesive is restored by returning to the atmospheric pressure state after bonding, and the bonding area As a result, both substrates can be firmly bonded.

  The present invention is not limited to the embodiment described above, and can be modified as follows.

  (1) The sheet clamps 4 and 5 are not necessarily provided in a pair at the front and rear. For example, the support sheet T can be stretched while holding the front, rear, left and right corners, and the number and installation positions thereof are supported. It can be arbitrarily set according to conditions such as the size of the sheet T and the length of the laminating roller 6. In particular, when the support sheet T is large and the slack is likely to occur, the periphery of the support sheet T is supported by a sheet clamp configured in a hollow rectangular frame shape, and the inside of the rectangular frame sheet clamp is You may employ | adopt the structure which moves the bonding roller 6 back and forth.

  (2) As a specific means for holding the end portion of the support sheet T by the sheet clamps 4 and 5, in addition to the above-described holding type, it is also possible to hold by a vacuum suction force.

  (3) As means for absorbing the tension of the support sheet T generated by the bonding operation, in addition to tilting the entire sheet clamp 4 around the fulcrum x as described above, the entire sheet clamp 4 is elastically supported so that it can slide back and forth. You can also It is also possible to implement the structure in which only the sheet holding portion 4a is elastically supported to be slidable back and forth with respect to the fixed sheet clamp base, and only the sheet holding portion 4a is displaced rearward by the sheet tension.

  (4) In the above embodiment, the laminating roller 6 is configured to be driven at the same peripheral speed as that of the movable table 8, but is configured to be driven as the movable table 8 moves. May be.

It is a vertical side view of the board | substrate bonding apparatus which concerns on this invention. It is a top view of the board | substrate bonding apparatus which concerns on this invention. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process. It is a schematic side view which shows a board | substrate bonding process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Depressurization chamber 3 ... Holding table 4 ... Sheet clamp 5 ... Sheet clamp 6 ... Laminating roller W1 ... 1st board | substrate (wafer)
W2 ... Second substrate (reinforcing substrate)
S ... Double-sided adhesive sheet T ... Support sheet

Claims (2)

In the substrate laminating method of laminating two substrates with a double-sided adhesive sheet interposed,
A process of attaching a double-sided adhesive sheet with a separator on the surface of the first substrate;
Placing and aligning the second substrate on the separator upper surface of the double-sided adhesive sheet;
The pressure-sensitive adhesive surface of a support sheet having a pressure-sensitive adhesive surface weaker than the double-sided adhesive sheet is stretched on a pair of sheet clamps so as to face the second substrate, and a sticking roller is rolled on the surface of the support sheet. Pasting the second substrate on the support sheet, and placing the second substrate opposite the first substrate with a gap;
Removing the separator from the double-sided pressure-sensitive adhesive sheet on the first substrate;
The process of applying the second substrate to the double-sided adhesive sheet applied to the first substrate while pressing the application roller on the non- adhesive surface of the support sheet under reduced pressure, and peeling the second substrate from the support sheet ;
A method of laminating a substrate, comprising: In the substrate bonding method according to claim 1,
A substrate bonding method, wherein at least one of the first substrate and the second substrate is a semiconductor wafer.

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