JP2012109422A - Edge polishing apparatus for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an edge polishing apparatus for obtaining a semiconductor substrate with a protective film which does not shorten the life of a rear face grinding stone of the semiconductor substrate.SOLUTION: An edge polishing apparatus 1 comprises a polishing head 4 which has a cam-like frame 4b pivotally supported by a rotation axis 4a; a stop pin 4c; a patch 4d made of silicone rubber sponge for contacting the edge part of a semiconductor substrate with a polishing surface of a polishing tape T and sliding a polishing tape supplied from a supply reel 2 on its surface; a pair of first polishing tape feeding roller 4e provided apart across the patch and a second polishing tape feeding roller 4f; and a third polishing tape feeding roller 4g provided on a back surface of the first engineering polishing tape feeding roller made of resin and for returning the polishing tape to the take-up reel 3.

Description

  The present invention is a semiconductor substrate with printed wiring on the surface of the silicon substrate, or a protective film affixed to the printed wiring surface of the semiconductor substrate, the silicon substrate surface of the semiconductor substrate facing up and adsorbed to the suction chuck, The present invention relates to an edge polishing apparatus used for polishing an edge surface of a semiconductor substrate by pressing a polishing tape of an edge polishing apparatus against an edge surface of a semiconductor substrate rotated by rotation of an adsorption chuck. A semiconductor substrate that is edge-polished by this edge polishing apparatus leaving an oblique angle of 20 to 88 degrees of the edge portion of the semiconductor substrate is obtained by using a cup wheel type grinding wheel in the next process of the edge polishing process. In the back grinding method in which the silicon substrate thickness is reduced to a thickness of 20 to 100 μm by back grinding, a semiconductor substrate having a thickness of 20 to 100 μm in which chipping of the semiconductor substrate is prevented can be obtained. In addition, the service life of the cup wheel type grindstone during the back grinding is improved.

  In the method of grinding the back surface (silicon base surface) of a semiconductor substrate, the back surface grinding of the semiconductor substrate is performed to prevent chipping of the substrate during back surface grinding or to prevent chipping during the transport by the transport pad of the back ground substrate. Trimming a bevel portion and an edge portion of a semiconductor substrate using a grindstone roller or a polishing tape is performed together with a pre-processing step or backside grinding.

  Japanese Patent Application Laid-Open No. 11-33887 (Patent Document 1) discloses a chuck table that holds a semiconductor substrate, and grinding that presses against one surface of the semiconductor substrate held on the chuck table and grinds one surface of the semiconductor substrate. And a chamfering grindstone for chamfering the edge of the semiconductor substrate which is pressed against the edge of the semiconductor substrate held by the chuck table, and grinding processing by the grinding grindstone and the chamfering grindstone This proposes a semiconductor substrate grinding apparatus capable of performing chamfering by the same method.

  Japanese Patent Laying-Open No. 2003-273053 (Patent Document 2) is a surface grinding method in which the back surface of a semiconductor substrate to which a protective film is attached is surface ground, and the peripheral edge of the semiconductor substrate is ground along the circumferential direction. A peripheral edge cutting step of forming a vertical cut surface substantially perpendicular to the back surface or an inclined cut surface inclined outward from the back surface side to the front surface side, and a semiconductor substrate in which the peripheral portion is cut by a grindstone A surface grinding method including a back surface grinding step of surface grinding while leaving the vertical cut surface or the inclined cut surface.

  Japanese Patent No. 4125148 (Patent Document 3) discloses a polishing tape in a substrate processing apparatus in which a polishing tape is pressed against a predetermined portion of a substrate and the substrate is polished by sliding contact between the polishing tape and the substrate. A bevel that supports the substrate with an elastic member and extends the elastic member to generate a tension, and the abrasive binder coating layer of the polishing tape is pressed against the bevel portion of the substrate with a certain force by the tension to polish the bevel portion. During the polishing of the substrate and the substrate, the tension applied to the polishing tape that is in sliding contact with the surface to be polished of the substrate or the tension applied to the mechanism portion that presses the polishing tape against the surface to be polished of the substrate is measured. A substrate processing apparatus including a control unit for determining a polishing state of a polishing surface is proposed.

Furthermore, the patent 4463326 specification (patent document 4) is an apparatus for polishing an outer peripheral end portion of a semiconductor wafer in which a surface on which a semiconductor element is formed is attached by a protective sheet,
Semiconductor wafer holding means for holding the semiconductor wafer in the horizontal direction with the front side down and the back side up,
A polishing head equipped with a runnable polishing tape for grinding the outer peripheral edge of the semiconductor wafer held by the semiconductor wafer holding means;
The polishing head presses the polishing tape against the outer peripheral edge of the semiconductor wafer and travels in a vertical direction or a horizontal direction from bottom to top to polish the outer peripheral edge of the semiconductor wafer together with the protective sheet. So that it can be pivoted,
Proposed is a tape polishing apparatus for the outer peripheral edge of a semiconductor wafer, wherein the polishing tape is made by adhering abrasive grains by electrostatic spraying.

  Using a cup wheel type grindstone, a silicon substrate surface having a thickness of 720 to 770 μm obtained by polishing the edge and bevel portion of the semiconductor substrate described in Patent Document 2, Patent Document 3 and Patent Document 4 with a polishing tape. When the back surface is ground and the thickness of the silicon substrate is reduced to 20 to 80 μm, the thickness from the half thickness of the silicon substrate to the surface of the printed wiring shows an acute angle. There is an annular part that is not affixed to the substrate, and the protective film of this non-adhered part during backside grinding or the grinding scraps adhere to the grinding wheel blade of a cup wheel grindstone that has become hot due to grinding, thereby reducing the grinding ability There was found.

  In addition, US Pat. No. 6,641,464 (Patent Document 5) discloses that the top wafer and the edge of the adhesive bonded to each other by bonding the top wafer and the bottom wafer with an adhesive have an inclination angle of 60 to 160 degrees. Disclosed are a method of edge trimming with an abrasive tape and an edge polishing apparatus used therefor.

Japanese Patent Laid-Open No. 11-33887 JP 2003-273053 A FIG. 7 of Japanese Patent No. 4125148 Japanese Patent No. 4463326 2 and 6 of US Pat. No. 6,641,464.

  In the back grinding of the semiconductor substrate in which the silicon substrate thickness of the semiconductor substrate is reduced from 720 to 770 μm to a thickness of 20 to 100 μm, the printed wiring surface of the semiconductor substrate is photocured to prevent cracking and chipping of the semiconductor substrate after the back grinding. A protective film in which a conductive acrylic resin adhesive or a thermally decomposable foamed resin adhesive is applied to a film is pasted, and edge trimming and back surface grinding of the semiconductor substrate with the protective film are performed.

  In the semiconductor substrate grinding apparatus described in Patent Document 1, since the back grinding and edge trimming are performed simultaneously, it is predicted that the residue of the protective film adheres to the cutting edge of the cup wheel grinding wheel.

  An object of the present invention is to provide an edge polishing apparatus for a semiconductor substrate which forms a semiconductor substrate edge portion capable of extending the service life of a cup wheel type grindstone in a back grinding process of the semiconductor substrate in a later step.

The invention of claim 1
A supply reel wound with a polishing tape having a polishing surface;
A take-up reel that winds up the polishing tape;
A silicon rubber sponge backing plate that causes the polishing surface of the polishing tape to come into contact with the edge of the stop pin and the semiconductor substrate and to slide the polishing tape supplied from the supply reel to the cam-shaped frame supported by the rotating shaft, A pair of the first engineering resin polishing tape feed roller and the second engineering resin polishing tape feed roller provided apart from each other with the abutting plate interposed therebetween, and provided on the back surface of the first engineering resin polishing tape feed roller. A polishing head provided with a third engineering resin polishing tape feed roller for returning the polishing tape to the take-up reel side;
A servo motor that rotationally drives the rotating shaft of the polishing head;
A motor for rotating the take-up reel;
A stepping motor that pulls out the polishing tape from the supply reel and rotationally drives a relay feed roller that supplies the polishing tape to the first engineering resin polishing tape feed roller of the polishing head;
An edge polishing apparatus for a semiconductor substrate is provided.

  According to a second aspect of the present invention, the semiconductor substrate edge polishing apparatus according to the first aspect is used to rotate the protective film-attached semiconductor substrate placed on the workpiece suction chuck table, and to the edge portion of the protective film-attached semiconductor substrate. From the protective film obtained by trimming by rotating the rotating shaft of the polishing head with a servomotor and bringing the polishing surface of the polishing tape supplied to the front surface of the backing plate into contact with an inclination angle of 2 to 70 degrees A protective film-attached semiconductor substrate having an edge inclination angle (θ) reaching a silicon substrate surface of 20 to 88 degrees is provided.

  Since the edge polishing apparatus of the present invention can cut off the edge portion and bevel portion of the semiconductor substrate obliquely with a polishing tape, it is like the substrate edge / bevel portion polishing apparatus described in Patent Document 2, Patent Document 3, and Patent Document 4. Further, there is no need for a pressing material that pushes up and down the bevel portion of the substrate. Further, in the edge polishing apparatus of the present invention, the front surface of the backing plate is positioned closer to the edge portion side of the semiconductor substrate than the rotation axes of the first engineering resin polishing tape feed roller and the second engineering resin polishing tape feed roller. Since it is fixed to the cam-shaped frame, the air cylinder for advancing and retreating the contact plate horizontally in the edge direction of the semiconductor substrate as in the substrate edge / bevel portion polishing apparatus described in Patent Document 2, Patent Document 3 and Patent Document 4 is provided. This eliminates the need for such a feed mechanism and allows the edge polishing apparatus to be designed in a compact manner.

  Protective film-attached semiconductor substrate without edge between protective film and semiconductor substrate by trimming processing using polishing tape so that edge portion of protective-substrate-attached semiconductor substrate remains at an inclination angle of 20 to 88 degrees according to the diameter of semiconductor substrate Therefore, the fear that the protective film residue adheres to the cutting edge of the cup wheel type grinding wheel is solved. Therefore, the service period (life) of the cup wheel type grindstone until it is replaced with a new cup wheel type grindstone is not shortened compared with the back grinding process of the semiconductor substrate to which the protective film is not attached.

FIG. 1 is a front view of an edge polishing apparatus for a semiconductor substrate. FIG. 2 is a right side view of the semiconductor substrate edge polishing apparatus with a part cut away. FIG. 3 is a front sectional view of the polishing head taken along the line AA in FIG. FIG. 4 shows a left side view of the rotated polishing head. FIG. 5 shows a partial cross-sectional view of a semiconductor substrate with a protective film, in which the bevel portion and the edge portion are cut off obliquely by an edge polishing apparatus.

  The semiconductor substrate edge polishing apparatus of the present invention will be described below with reference to the drawings.

An edge polishing apparatus 1 for a semiconductor substrate w shown in FIGS. 1 and 2 includes a supply reel 2 around which a polishing tape T having a polishing surface Ta is wound,
A take-up reel 3 for winding the polishing tape T;
Silicone rubber that causes the polishing surface Ta of the polishing tape to come into contact with the stop pin 4c and the edge portion of the semiconductor substrate and to slide the polishing tape supplied from the supply reel 2 to the cam-like frame 4b supported by the rotating shaft 4a Sponge backing plate 4d, a pair of first engineering resin polishing tape feed roller 4e and second engineering resin polishing tape feed roller 4f provided apart from each other by sandwiching the backing plate 4d, the first engineering resin polishing tape A polishing head 4 provided with a third engineering resin polishing tape feed roller 4g provided on the back surface of the feed roller 4e and returning the polishing tape to the take-up reel side;
A servomotor 5 that rotationally drives the rotating shaft 4a of the polishing head;
A torque motor 6 for rotating the take-up reel 3;
A stepping motor 7 is provided that pulls out the polishing tape T from the supply reel 2 and rotationally drives relay feed rollers 7a and 7b that supply the polishing tape to the first engineering resin polishing tape feed roller 4e of the polishing head.

  In the figure, 1a is a housing of the edge polishing apparatus, 4k is a positioning pin provided on the tip end surface of the housing 4h of the rotating shaft 4a, and the end face of the cam frame 4b rotated by the servo motor 5 or the stop pin 4c is this. The end face of the cam frame 4b abuts on the positioning pin 4k and does not rotate beyond the rotation angle. 4s indicates a displacement sensor, and 10 indicates a cooling water jet nozzle.

  The polishing tape feed rollers 4e and 4f are made of engineering resin such as polyether ether ketone resin (PEEK), polyacetal resin, nylon 6,10, nylon 6,12, etc., and have excellent heat resistance and slipperiness. Laura.

  The silicon rubber sponge backing plate 4d is excellent in surface slipperiness and rich in elasticity, and has elasticity that can expand and contract in the thickness direction according to the stress when the polishing tape T is pressed against the edge portion of the semiconductor substrate w. It is an elastic body. In the drawing, a silicone rubber sponge backing plate having a thickness of 9 mm, a height of 26 mm, and a width of 48 mm was used. The front surface of the silicone rubber sponge backing plate 4d is closer to the edge of the semiconductor substrate than the rotation axis of the first engineering resin polishing tape feed roller 4e and the rotation axis of the second engineering resin polishing tape feed roller 4f. (In FIG. 3, the front surface of the abutting plate 4d is provided on a business trip from the rotational shaft surfaces of the 3 mm polishing tape feed rollers 4e and 4f), and is fixed to the cam-like frame 4b.

  The silicone rubber sponge base plate 4d is made of an organopolysiloxane foam, polyimide organopolysiloxane foam, or polyurethane foam with an organopolysiloxane coating agent applied to the surface in a thickness of 5 to 30 μm and cured to form a film. The formed laminate is used. The independent cell diameter of the foam is preferably 20 to 300 μm.

  In the position indicated by the phantom line in FIG. 1, the polishing head 4 is rotated on the rotating shaft 4 a by driving the servo motor 5, and the polishing tape T is attached to the edge portion of the semiconductor substrate w fixed on the suction chuck table 9. The silicon rubber sponge backing plate 4d is brought into contact with the vertical surface of the edge end surface with an inclination angle (90-θ) of 70 to 2 degrees. The inclination angle (90-θ) depends on the diameter of the semiconductor substrate w and is 2 to 5 degrees for 200 mm, 300 mm, and 450 mm diameter semiconductor substrates, and 55 to 70 degrees for 4 to 6 inch diameter semiconductor substrates. Therefore, the edge inclination angle (θ) from the edge trimmed protective film to the silicon substrate surface is 20 to 88 degrees, that is, 85 to 88 degrees for 200 mm, 300 mm, and 450 mm diameter semiconductor substrates, and 20 for the 4 inch diameter semiconductor substrate. A semiconductor substrate with a protective film having an edge inclination angle (θ) of ˜35 degrees is obtained (see FIG. 5).

  The adhesive surface between the protective film F and the semiconductor substrate w is formed by obliquely cutting (polishing) the bevel portion and the edge portion of the semiconductor substrate including the free protective film portion Fg. Since the grinding residue does not adhere to the grindstone cutting edge of the cup wheel grindstone, the reduction in the life of the cup wheel grindstone due to the protective film is eliminated.

  As the semiconductor substrate, a DRAM, LED substrate, MEMS substrate, STV substrate, SOI substrate, or the like can be used.

  As the base film material of the protective film F, linear linear low density polyethylene, polyethylene terephthalate, polyimide, or the like is used, and the film thickness is generally 20 to 200 μm. The protective film F can be obtained from Furukawa Electric Co., Ltd., Lintec Co., Ltd., Sekisui Chemical Co., Ltd., Mitsui Chemicals Co., Ltd., Hitachi Chemical Co., Ltd., Toagosei Co., Ltd., Toray Industries, Inc.

  The protective film F is affixed to the printed wiring surface of the semiconductor substrate w so that the outer peripheral edge Fg of the protective film F protrudes from the outer peripheral edge of the 1 to 3 mm wide semiconductor substrate. Therefore, during edge trimming of the protective film-attached semiconductor substrate with the polishing tape, a gap is not generated between the protective film F and the semiconductor substrate w as shown in FIG. 3B in the cross-section of the edge-trimmed protective film-attached semiconductor substrate. Further, it is necessary to perform trimming processing so that the protective film Fg protruding from the outer peripheral edge of the semiconductor substrate does not exist.

As the polishing tape T, silicon carbide having a polishing number of # 4,000 to # 10,000 on the surface of a biaxially stretched polyethylene terephthalate film substrate (T _b ) having a thickness of 100 to 150 μm commercially available from Nippon Micro Coating Co., Ltd. Abrasive binder coating agent in which diamond abrasive grains with abrasive grains and / or abrasive numbers # 4,000 to # 12,000 are dispersed is applied in a thickness of 5 to 10 μm and dried to provide an abrasive binder coating layer (T A polishing tape provided with _f ) is preferred.

  The polishing process for trimming the edge portion of the semiconductor substrate to which the protective film is attached is performed through the following steps using the edge polishing apparatus 1 of the semiconductor substrate using the polishing tape.

(1) protective film application semiconductor substrate affixed protective film F on the printed wiring surface of the housing silicon base w _s surface to the printed circuit is applied the semiconductor substrate w in the storage cassette, the multi-joint type transport robot It is gripped or sucked and transferred with the silicon substrate _ws surface of the semiconductor substrate attached with the protective film facing upward and the protective film surface facing the suction chuck table 9 surface, where it is vacuum-sucked and fixed to the suction chuck table 9.

  (2) Next, the suction chuck table 9 is moved up and down to adjust the height position of the protective film-attached semiconductor substrate to the polishing start position.

(3) The suction chuck table 9 is rotated. The rotation speed of the suction chuck table 9 is preferably 1,800 to 5,000 min ⁻¹ .

  (4) The torque motor 6 is operated to rotate the rotation shaft of the take-up reel 3, and the work of winding the polishing tape around the rotation shaft is started. At this time, the stepping motor 7 is also operated, the rotational speed of the rotating shaft of the relay feed roller 7a is made smaller than the rotational speed of the rotating shaft of the take-up reel 3, and the speed of the polishing tape taken up is brake controlled. The tension between the first engineering resin polishing tape feed roller 4e, the backing plate 4d, the second engineering resin polishing tape feed roller 4f, and the third engineering resin polishing tape feed roller 4g of the polishing head 4 is tensioned without slackening. It is possible to feed the polishing tape while maintaining this state.

  (5) When the servo motor 5 of the polishing head 4 is operated, the rotating shaft 4a is rotated by (90−θ) degrees, and the polishing surface Ta of the polishing tape is brought into contact with the edge portion of the semiconductor substrate w rotating the contact plate 4d. Then, the edge polishing is started by rubbing. At this time, the cooling water is supplied from the cooling water supply nozzle 10 toward the processing action portion where the polishing surface Ta of the polishing tape contacts the edge portion of the semiconductor substrate w.

  (6) The edge polishing process is performed for 5 to 20 seconds, then the operation of the torque motor 6 and the stepping motor 7 is stopped, and the movement of the polishing tape is stopped. ) Is operated in the reverse rotation direction so as to return to the original position, and the polishing head 4 is returned to the standby position.

  (7) Stop the rotation of the suction chuck table 9 and then raise and lower it to return to the polishing start position.

  The semiconductor substrate edge polishing apparatus of the present invention is designed to be compact and can be easily installed in a semiconductor substrate manufacturing machine. Also, when grinding the back surface of a semiconductor substrate with a protective film applied with edge trimming, the protective film residue does not adhere to the cutting edge of the cup wheel grinding wheel, so it is time to replace the cup wheel grinding wheel (life) However, it does not become shorter than the replacement time of the cup wheel type grinding wheel of the conventional back grinding apparatus.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate edge polishing device 2 Supply reel 3 Take-up reel 4 Polishing head 4a Rotating shaft 4b Cam-shaped frame 4d Silicon rubber sponge pad 4e First engineering resin polishing tape feed roller 4f Second engineering resin polishing tape feed Roller 5 Servo motor 6 Torque motor 7 Stepping motor T Polishing tape F Protective film w Semiconductor substrate

Claims (2)

A supply reel wound with a polishing tape having a polishing surface;
A take-up reel that winds up the polishing tape;
A silicon rubber sponge backing plate that causes the polishing surface of the polishing tape to come into contact with the edge of the stop pin and the semiconductor substrate and to slide the polishing tape supplied from the supply reel to the cam-shaped frame supported by the rotating shaft, A pair of the first engineering resin polishing tape feed roller and the second engineering resin polishing tape feed roller provided apart from each other with the abutting plate interposed therebetween, and provided on the back surface of the first engineering resin polishing tape feed roller. A polishing head provided with a third engineering resin polishing tape feed roller for returning the polishing tape to the take-up reel side;
A servo motor that rotationally drives the rotating shaft of the polishing head;
A motor for rotating the take-up reel;
A stepping motor that pulls out the polishing tape from the supply reel and rotationally drives a relay feed roller that supplies the polishing tape to the first engineering resin polishing tape feed roller of the polishing head;
An edge polishing apparatus for a semiconductor substrate, comprising:   2. The semiconductor substrate edge polishing apparatus according to claim 1, wherein the protective film-attached semiconductor substrate placed on the workpiece suction chuck table is rotated, and the rotation axis of the polishing head is servoed to the edge portion of the protective film-attached semiconductor substrate. The edge from the protective film to the silicon substrate surface obtained by trimming the polishing surface of the polishing tape that is rotated by a motor and supplied to the front surface of the backing plate in contact with an inclination angle of 2 to 70 degrees. A semiconductor substrate with a protective film having an inclination angle (θ) of 20 to 88 degrees.

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