JP2010205861A - Chamfering device for laminated wafer, and method for chamfering bevel and edge of laminated wafer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edge chamfering method for a laminated wafer that facilitates the centering of the laminated wafer executed when the laminated wafer is transferred to a processing stage of a subsequent processing process. <P>SOLUTION: A cylindrical grinding wheel 12 is configured so that the thickness of the outer-peripheral surface is 0.3-1.5 mm. The cylindrical grinding wheel is used to chamfer the thickness of an edge and that of a bevel of the laminated wafer to the thickness of exceeding 1/3-1/2 of the thickness of one lower-tier base wafer w<SB>2</SB>of the laminated wafer w and 1/2 of the thickness of a wafer w<SB>1</SB>to be ground in the upper tier of the laminated wafer w while leaving the thickness of an insulating layer to be ≥10 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a processing apparatus for chamfering a bevel portion and an edge portion of a laminated wafer (SOI wafer, TSV wafer) in which a plurality of semiconductor wafers are laminated using a thin cylindrical grinding wheel, and chamfering of the laminated wafer using the same. On how to do.

As a method for manufacturing an SOI wafer, (A) a step of forming a laminated body by superposing a semiconductor wafer and a support wafer via an oxide film, and (B) by reducing the thickness of the semiconductor wafer to a predetermined thickness In a method for manufacturing a bonded SOI wafer, including a step of forming a thin single-crystal silicon layer on a supporting wafer through a buried oxide film layer, (C) overlapping between step (A) and step (B). The oxide film formed on the peripheral edge and chamfered portion of the main surface on the mating side is removed so that the oxide film remains only on the overlapping surface excluding the peripheral edge. A method characterized by encapsulating with a main surface and a single crystal silicon layer has been proposed (see, for example, Patent Document 1).

In addition, an element substrate (wafer) having a diameter of 150 mm and a support substrate are prepared, wet oxidation is performed on the element substrate, an oxide film having a thickness of 1 μm is formed, and the polishing surface side of the element substrate on which the oxide film is formed; The polished surface of the supporting substrate was superposed and adhered, and the adhered bonded substrate was subjected to heat treatment at a high temperature of 1000 ° C. to enhance the bonding force of the superimposed surfaces. Thereafter, the diameter is reduced to 125 mm, and after removing the oxide film formed during the heat treatment by hydrofluoric acid treatment, the surface is ground and subjected to primary polishing, and 2 mm from the end surface portion (outermost peripheral portion) of the bonded substrate. After generating an outer peripheral sag in the outer peripheral portion of the range (region), the diameter is reduced to 100 mm by chamfering again, and finally, secondary polishing and finish polishing are performed to create an SOI wafer. This is also known (see, for example, Patent Document 2).

Furthermore, a method of polishing a bevel portion and an edge portion of a laminated (SOI) wafer using an abrasive tape has also been proposed (see, for example, Patent Document 3).

Furthermore, after laminating a plurality of silicon wafers having bevels in the peripheral portion, and laminating the plurality of silicon wafers in the laminated state, the peripheral bevel is ground to form a vertical edge surface, and then There has also been proposed a method of obtaining a thin silicon wafer by back grinding the surface of each individual silicon wafer (see, for example, Patent Document 4).

Further, as shown in FIG. 3, the support substrate wafer (101) and the active layer wafer are bonded via the bonding insulating film (102), and the active layer wafer is thinned and the active layer (103) of the semiconductor element is formed. Further, the outer peripheral portion thereof is beveled at an angle of 30 ° to 60 ° with respect to the surface of the active layer, and then the end portion of the bonding insulating film (102) is removed by an etching process (107) An SOI wafer exposed on a bevel surface formed by bevel processing on the active layer side has also been proposed (see, for example, Patent Document 5).

The next generation of ultra-thin semiconductor substrates with the diameter of semiconductor substrates (wafers) increasing from 150 to 200 mm to 300 to 450 mm and the thickness of 20 to 100 μm is required. SOI wafers and TSV stacks with diameters of 300 to 450 mm The edge surface of the SOI wafer is chamfered by using the edge chamfering grinding wheel or polishing tape described in Patent Documents 1 to 3 for edge polishing or grinding of the wafer, and then back surface grinding and back surface of the SOI wafer or TSV laminated wafer are performed. It has been found that many chippings and cracks are observed at the edge portion of the flat processed SOI wafer obtained by polishing.

The method for vertically chamfering the bevel portion and the edge portion of the SOI wafer described in Patent Document 4 is excellent in that the SOI layer can be prevented from being broken (cracked or chipped) in the outer peripheral portion in the manufacturing process of the semiconductor device using the SOI wafer. Technology. However, it is necessary to perform wafer centering operations in a back grinding process, a polishing process, or a wafer peeling process in a post-processing process. Semiconductor substrate processing manufacturers are requesting that some edge surfaces be left on the base wafer so that a centering process can be performed in the post-process of the lower wafer on the stacked wafer.

The bevel part and edge chamfering method described in Patent Document 5 is an excellent technique capable of preventing the SOI layer from being damaged (cracked or chipped) in the outer peripheral part in the manufacturing process of the semiconductor device using the SOI wafer. In addition, there is an advantage that the centering step is not required in the post-process. However, the chamfering of the bevel portion and the edge portion of the laminated wafer requires two steps of a grinding step and an etching step, and there is a disadvantage that the installation area of these chamfering devices attached to the substrate thinning flattening device becomes wide.

JP 2005-79109 A JP 2006-100406 A US Pat. No. 6,641,464 FIG. 7 of Japanese Patent Application Laid-Open No. 2004-22899 FIG. 4B of Japanese Patent Application Laid-Open No. 2007-214256

The present invention provides a base wafer portion diameter that does not cause cracks or chipping in a laminated wafer obtained by back-grinding or polishing in a subsequent process, and enables centering when transferring the laminated wafer to the subsequent process. A chamfering grinding method and a chamfering device for bevel portions and edge portions of laminated wafers (SOI wafers, TSV wafers) that leave chamfered portions of the portions are provided.

According to the first aspect of the present invention, a cylindrical grinding wheel having a thickness of 0.3 to 1.5 mm and a diameter smaller than the diameter of the laminated wafer and having an abrasive number of 500 to 2,000 is provided in the longitudinal direction of the diameter. A grinding head that is supported by the grinding wheel shaft so that the grinding wheel can be rotated in the horizontal direction, and the cylindrical grinding wheel of the grinding head is moved back and forth in the direction of the center point of the laminated wafer that is horizontally mounted on the support chuck in the diametrical direction. A moving mechanism for enabling movement, a rotation driving mechanism for rotating the grinding wheel shaft, a lifting mechanism for the grinding wheel shaft, the support chuck for placing the laminated wafer, a rotation driving mechanism for the rotation shaft for supporting the work table of the support chuck, Also provided is a chamfering device for a laminated wafer, comprising a grinding fluid supply mechanism for supplying a grinding fluid to a chamfered portion of the laminated wafer.

According to a second aspect of the present invention, there is provided a method for chamfering a bevel portion and an edge portion of a laminated wafer through the following steps using the chamfering device for the laminated wafer according to the first aspect. (1) The height position of the cylindrical grinding wheel with respect to the laminated wafer placed on the support chuck in the diametrical direction is adjusted by the lifting mechanism of the grinding wheel shaft. (2) The cylindrical grinding wheel is brought into contact with the edge portion of the laminated wafer to be ground by the moving mechanism of the grinding head in the direction of the center point of the rotating laminated wafer placed on the support chuck, Then, the rotating cylindrical grinding wheel is moved forward to bring the outer peripheral surface of the cylindrical grinding wheel into contact with the outer peripheral surface of the laminated wafer, and then the lower and lower surfaces of the cylindrical grinding wheel are rubbed against the laminated wafer. Cylinder for chamfering the thickness of the laminated wafer that exceeds 1/3 to 1/2 of the thickness of one base wafer and 1/2 of the thickness of the upper ground wafer and leaves an insulating layer of 10 μm or more. The grinding wheel is moved forward by 1 to 5 mm. In this chamfering process, the grinding liquid is supplied from the grinding liquid supply mechanism to the chamfering part of the laminated wafer and the cylindrical grinding wheel. (3) When the chamfering of the edge portion and the bevel portion of the laminated wafer by the forward movement of the cylindrical grinding wheel is finished, the cylindrical grinding wheel is moved backward from the laminated wafer chamfered by the moving mechanism of the grinding head. .

In the laminated wafer chamfering apparatus according to the first aspect, since the chamfering of the bevel portion and the edge portion of the laminated wafer can be simultaneously ground while leaving the diameter portion of the base wafer, the installation area can be reduced.

In the method for chamfering the bevel portion and the edge portion of the laminated wafer according to the second aspect of the invention, since the grinding process is performed leaving the diameter portion of the base wafer, the laminated wafer can be centered in the post-process of the laminated wafer.

FIG. 1 is a side view of a chamfering device for a bevel portion and an edge portion of a laminated wafer. FIG. 2 is an explanatory view showing an execution procedure of a chamfering process for a bevel portion and an edge portion of a laminated wafer. FIG. 3 is a partial cross-sectional view of a laminated wafer in which the bevel portion and the edge portion of the laminated wafer are chamfered. (Known)

A chamfering apparatus 1 shown in FIG. 1 includes a chamfering tool stage 10, a support chuck 20, and grinding fluid supply mechanisms 30 and 30. The chamfering tool stage 10 raises a column 60 on the upper surface of a tool table 11 composed of a guideway 11a and a slideway 11b provided on a frame 40, and a grindstone shaft lifting mechanism 50 is suspended from the upper front of the column. The grinding wheel shaft 13 is fixed to the side surface of the grinding wheel shaft mounting plate 55 of the grinding wheel shaft lifting mechanism, and the cylindrical grinding wheel 12 is rotatably fixed to the lower end portion of the grinding wheel shaft 13 by a rotational drive mechanism so that the diameter direction thereof becomes a horizontal plane. By doing so, the grinding head 14 is configured. Although a rotation drive mechanism is not shown, built-in motor drive is preferable, but an external rotation drive mechanism of a combination of a servo motor, a pulley, and a belt may be used.

The tool table 11 is slidable on the guide way 11 a and slides on the center point o of the laminated wafer placed on the support chuck 20. The ball screw 21d receives the rotational drive of the servo motor 21c, and the slide way 21b is moved forward to the center point position side of the laminated wafer placed on the support chuck 20, or retracted from the center point position of the laminated wafer. The forward / backward movement of the slide way 11b may be linear actuator drive or linear motor drive. A displacement sensor (laser distance meter) 70 is attached to the upper end of the slide way 21b to measure the bottom surface height of the cylindrical grinding wheel 12.

The grindstone shaft raising / lowering device 50 receives the rotational drive of the servo motor 52 by the ball screw 51 and raises / lowers the grindstone shaft mounting plate 54 in the vertical direction via the threaded body 54. The screw 54 slides on the guide rail 53. The up and down movement of the grindstone shaft mounting plate 55 may be driven by a linear actuator or a linear motor.

The thickness of the cylindrical grinding wheel 12 is 1/3 to 1/2 of the thickness of one base wafer on the lower layer of the laminated wafer to be chamfered and 1/2 of the thickness of the wafer to be chamfered on the upper wafer. The thickness of the insulating layer thickness (t) exceeding 10 μm is chamfered to a total thickness of 0.75 to 1.5 mm, and the diameter of the cylindrical grinding wheel is smaller than the diameter of the laminated wafer. Vitrified bond grindstones, metal bond grindstones, and resin bond grindstones of CBN abrasive grains or diamond abrasive grains having a number of 500 to 2,000 are preferred. The grinding wheel portion of the cylindrical grinding wheel 12 is subjected to electrolytic plating on the peripheral surface of the outer periphery of the metal disk so as to have an outer circumferential width of the grinding wheel blade having a height of 0.75 to 1.5 mm and a width of 1 to 5 mm. It may be obtained.

The support chuck 20 is preferably a vacuum chuck in which a porous ceramic chuck table 21 is rotatably supported by a hollow shaft 22, and the diameter of the porous ceramic chuck table 21 is 0.1 to 5 mm smaller than the diameter of the laminated wafer. preferable. A decompression pipe, a pure water supply pipe, and a compressed air supply pipe are provided in the hollow shaft 22 pipe.

The grinding fluid supply mechanism 30 supplies the grinding fluid toward the chamfering portion (working portion) of the laminated wafer and the cylindrical grinding wheel when chamfering the laminated wafer.

The chamfering of the bevel portion and the edge portion of the laminated wafer w is performed through the following steps as shown in FIG.

(1) The bottom height position of the cylindrical grinding wheel 12 with respect to the laminated wafer w placed on the support chuck 20 in the diametrical direction is adjusted by lowering the grinding wheel shaft lifting mechanism 50 (see FIG. 2a).

(2) The laminated wafer w placed on the support chuck 20 is rotated at a rotational speed of 100 to 300 rpm, and then rotated at a rotational speed of 800 to 2,000 rpm toward the center point o of the laminated wafer w. The cylindrical grinding wheel 12 is moved forward by the moving mechanism of the grinding head 14, the outer peripheral surface of the cylindrical grinding wheel 12 is brought into contact with the edge portion of the laminated wafer w to be ground, and the cylindrical grinding wheel 12 is further moved forward. is the outer peripheral surface and one grinding 1 / 3-1 / 2 the thickness and the upper thickness of the lower base wafer w ₂ of the laminated wafer while the upper and lower surfaces is rubbed into laminated wafer of the cylindrical grinding wheel 12 rotating Te Cylindrical grinding wheel forward movement of 1-5 mm that chamfers the thickness of the laminated wafer that exceeds 1/2 of the thickness of the wafer w _{1 and} the insulating layer has a thickness of 10 μm or more. 5-3 mm / min (see FIG. 2b). During the chamfering process, the grinding liquid is supplied from the grinding liquid supply mechanism 30 to the chamfering part where the laminated wafer w and the cylindrical grinding wheel 12 are in contact with each other.

(3) When chamfering of the edge portion and the bevel portion of the laminated wafer w by the forward movement of the cylindrical grinding wheel 12 is completed, the laminated wafer w in which the cylindrical grinding wheel 12 is chamfered by the moving mechanism 11 of the grinding head 14. A backward movement is performed further away to stop the rotation of the grindstone shaft 13 (see FIG. 2c).

As an object to be ground w, an SOI wafer w obtained by laminating _two printed wafer surfaces w ₁ and w ₂ facing each other on the surface of a silicon substrate having a diameter of 300 mm and a thickness of 750 μm with printed circuits (thickness 10 μm) facing each other. Then, the chamfering of the laminated wafer w was performed using the chamfering apparatus 1 shown in FIG.

First, the diamond vitrified cylindrical grinding wheel 12 having a thickness of 0.8 mm, a diameter of 120 mm, and a grinding number 800 is lowered by the grinding wheel shaft lifting mechanism 50, and the laminated wafer w in which the diametrical direction is horizontally placed on the support chuck 20. bottom height position of the cylindrical grinding wheel 12 so as to be 10μm on position than the longest diameter portion L of the lower wafer w ₂ was adjusted.

Next, the grindstone shaft 13 rotating at 1,500 rpm is advanced at a speed of 2 mm / min toward the center point o of the laminated wafer w placed on the porous ceramic chuck table 21 of the support chuck 20 rotating at 200 rpm. The outer peripheral surface and the upper and lower surfaces of the cylindrical grinding wheel 12 rotating by rotating the cylindrical grinding wheel 12 forward at the same moving speed are brought into contact with the outer peripheral surface of the laminated wafer w. Chamfering with a chamfering height of 0.8 mm and a chamfering width of 2.5 mm on the diameter surface is performed by grinding the upper and lower base wafers w ₂ and the bevel and edge of the upper wafer w ₁ while rubbing against w. It was.

In this chamfering process, chamfering is performed while supplying pure water (grinding liquid) in an amount of 2 liters / minute from the pair of grinding liquid supply mechanisms 30 and 30 to the chamfering part where the laminated wafer w and the cylindrical grinding wheel 12 are in contact with each other. Processing was performed.

After the chamfering of the edge portion and the bevel portion of the laminated wafer w by the cylindrical grinding wheel 12 is finished, the cylindrical grinding wheel 12 is moved backward from the laminated wafer w chamfered by the moving mechanism of the grinding head 14, The rotation of the grindstone shaft 13 was stopped.

After the rotation of the porous ceramic chuck table 21 of the support chuck 20 is stopped, the surface of the laminated wafer w is blown with pressurized water and brush-washed, and then pressurized water is supplied to the lower surface of the porous ceramic chuck table 21 to thereby porous the laminated wafer w. Peeling from the ceramic chuck table 21 was facilitated.

A laminated wafer in which a bevel portion and an edge portion on the support chuck 20 are chamfered and ground using a planarization apparatus GDM300II (trade name, manufactured by Okamoto Machine Tool Co., Ltd.) for a semiconductor substrate described in Japanese Patent Application No. 2008-183398. w was adsorbed to the suction pad of the articulated transfer robot and transferred to the back grinding stage.

Roughly grind the silicon substrate surface of the laminated wafer using a rough grinding cup wheel type diamond resin bond grindstone of grinding number 600 on the rough grinding stage (substrate rotation speed is 300 rpm, grinding wheel shaft rotation speed is 1,800 rpm) The silicon substrate surface w ₁ was cut off by 670 μm.

This rough ground silicon base surface w ₁ is subjected to a final grinding process (rotation of the substrate) on the rough ground silicon base surface w ₁ using a cup wheel type diamond vitrified bond grindstone with a polishing number of 8,000 in a finish grinding stage. The number of rotations was 300 rpm and the rotation speed of the grinding wheel shaft was 1,800 rpm), the silicon substrate surface w ₁ was scraped by 30 μm, and the thickness of the silicon substrate w ₁ was reduced to 20 μm. Then, after the brush cleaning while supplying pure water to the grinding silicon substrate surface w _1, and dried blowing dry air. Resulting in the silicon base surface w _1, grinding striation were found.

After the ground semiconductor substrate is transferred to the polishing stage, the silica-based particle-dispersed aqueous abrasive slurry “SR300” (trade name) of Japan Air Products Co. is applied to the ground silicon substrate surface w ₁ at 100 cc / Grinding marks are removed by rubbing at a pressure of 230 g / cm ² , a polishing pad rotating on the silicon substrate surface w ₁ while supplying a minute amount, a rotating speed of the polishing pad of 250 rpm, and a rotating speed of the laminated semiconductor substrate w of 150 rpm. Buffing was performed for 6 minutes. The thickness of the silicon substrate surface w ₁ was reduced by 3 μm.

The pressure of the polishing pad according to the silicon base surface w ₁ .. This buffing silica-based particles dispersed aqueous abrasive slurry "SR300" (trade name) on the silicon base surface w ₁ with an amount supplied of 300 cc / min 50 g / A second buffing process was performed for 4 minutes, in which the polishing pad was rubbed at cm ² , the polishing pad rotating at 20 rpm, and the semiconductor substrate rotating at 20 rpm. The thickness of the silicon substrate surface w ₁ was further reduced by 0.1 μm. The number of particles adhering to the silicon substrate surface was 5,043 particles having a diameter of 0.2 μm or less, and 204 particles having a diameter of 1.0 μm or more.

After that, after this grinding and buffing silicon base surface w ₁ was subjected to alkali cleaning for 2 minutes to supply the drug SC1 in an amount of 500 cc / min, and then acid cleaning with hydrofluoric acid-containing ozone water for 1 minute. The silicon substrate surface w ₁ is washed with pure water, spin-dried, and two foreign particles (grinding scraps and polishing scraps) having a diameter of 0.2 μm or less are attached, and the surface average roughness (Ra) is 0.002 μm. A laminated wafer having a silicon substrate mirror surface was obtained. No chipping or cracking was found on the laminated wafer.

When edge chamfering processing, back surface grinding processing, back surface polishing processing, and cleaning were performed in the same manner as in Example 1 above, no chipping or cracking was found on any of the stacked wafers.

In the post-processing step, chamfering of the bevel portion and the edge portion of the laminated wafer that does not cause cracking or chipping in the laminated wafer w can be performed. Chamfered laminated wafer, the maximum diameter portion of the lower wafer w ₂ is left, the laminated wafer w in the processing stage of the post-processing step is easily centering the laminated wafer is performed when it is transported.

DESCRIPTION OF SYMBOLS 1 Chamfering apparatus 10 Chamfering tool stage 11 Tool table 12 Cylindrical grinding wheel 13 Grinding wheel shaft 14 Grinding head 20 Support chuck 21 Work table (Chuck table made of porous ceramic) 30 Grinding fluid supply nozzle 50 Grinding wheel shaft lifting device 60 Column 70 Displacement sensor w Lamination Wafer w ₁ Upper stage (back grinding) Wafer w ₂ Lower stage (base) Wafer L Lower wafer diameter end t Upper wafer Insulating layer chamfer thickness

Claims (2)

A cylindrical grinding wheel having a thickness of 0.3 to 1.5 mm and a diameter smaller than the diameter of the laminated wafer and having a grinding number of 50 to 2,000 can be rotated in the horizontal direction in the longitudinal direction of the diameter. A grinding head that is supported by the grinding wheel shaft, a moving mechanism that enables the cylindrical grinding wheel of the grinding head to move back and forth in the direction of the center point of the laminated wafer that is horizontally mounted on the support chuck in the diameter direction, Rotation drive mechanism for rotating the grinding wheel shaft, lifting mechanism for the grinding wheel shaft, the support chuck for placing the laminated wafer, a rotational drive mechanism for the rotational shaft for bearing the work table of the support chuck, and a chamfered portion of the laminated wafer A chamfering device for a laminated wafer, comprising: a grinding fluid supply mechanism for supplying a grinding fluid to the substrate. A method for chamfering a bevel portion and an edge portion of a laminated wafer through the following steps using the chamfering device for a laminated wafer according to claim 1. (1) The height position of the cylindrical grinding wheel with respect to the laminated wafer placed on the support chuck in the diametrical direction is adjusted by the lifting mechanism of the grinding wheel shaft. (2) The cylindrical grinding wheel is brought into contact with the edge portion of the laminated wafer to be ground by the moving mechanism of the grinding head in the direction of the center point of the rotating laminated wafer placed on the support chuck, Then, the rotating cylindrical grinding wheel is moved forward to bring the outer peripheral surface of the cylindrical grinding wheel into contact with the outer peripheral surface of the laminated wafer, and then the lower and lower surfaces of the cylindrical grinding wheel are rubbed against the laminated wafer. The thickness of the laminated wafer is chamfered so as to exceed 1/3 to 1/2 of the thickness of one base wafer and 1/2 of the thickness of the wafer to be ground on the upper side, leaving an insulating layer thickness of 10 μm or more. The cylindrical grinding wheel is moved forward by 1 to 5 mm. In this chamfering process, the grinding liquid is supplied from the grinding liquid supply mechanism to the chamfering part of the laminated wafer and the cylindrical grinding wheel. (3) When the chamfering of the edge portion and the bevel portion of the laminated wafer by the forward movement of the cylindrical grinding wheel is finished, the cylindrical grinding wheel is moved backward from the laminated wafer chamfered by the moving mechanism of the grinding head. .

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