JP2004235251A - Laminated substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated substrate that can be expanded in device forming area, can be shortened in outer periphery grinding time, and can prolong the service life of an outer periphery grinding wheel, and to provide a method of manufacturing the substrate. <P>SOLUTION: An orientation flat OF is formed in a notch forming section for a notch n by grinding the outer periphery of a wafer 10 for active layer except the notch forming section. Therefore, the outer periphery of the wafer 10 can be ground by separately setting the widths of the notch forming section and the other section in a terrace section. Consequently, the device forming area of the wafer 10 is expanded and the outer periphery grinding time becomes shorter as compared with the conventional outer periphery grinding practice in which the outer periphery of the wafer 10 is ground to a broader width until the wafer 10 becomes circular form. In addition, the whole area of the outer peripheral section of the wafer 10 can be ground by using one outer periphery grinding wheel. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bonded substrate and a method for manufacturing the same, and more particularly, to a technology for processing a surface silicon layer in an orientation flat portion or a notch portion in a bonded substrate obtained by bonding a surface silicon layer and a wafer for a supporting substrate that supports the surface silicon layer. .
[0002]
[Prior art]
2. Description of the Related Art A bonded SOI (Silicon on Insulator) substrate is known as one type of bonded substrate obtained by bonding two silicon wafers. This is because a buried oxide film (silicon oxide film) having a thickness of several μm is buried between an SOI layer (surface silicon layer) on which devices are formed on the surface and a supporting substrate wafer that supports the device from the back side. This is a bonded SOI substrate.
[0003]
A conventional method for manufacturing a bonded SOI substrate will be described with reference to FIGS. FIG. 4 is a flow sheet showing a method for manufacturing a bonded substrate according to a conventional means. FIG. 5A is a plan view of a bonded substrate according to a conventional means. FIG. 5B is a plan view of another bonded substrate according to the conventional means. FIG. 5C is a plan view of still another bonded substrate according to the conventional means.
First, a single crystal silicon ingot pulled up by the CZ method was subjected to block cutting, notch processing, and slicing to form a silicon wafer, and the obtained wafer was chamfered, wrapped, polished, and finished to a mirror surface. Two silicon wafers 101 and 102 with a notch n are prepared (FIG. 4A). The active layer wafer 101 has an insulating silicon oxide film 101a formed on the entire exposed surface thereof by thermal oxidation.
[0004]
Next, the wafer 101 for the active layer and the wafer 102 for the support substrate are overlapped with each other at room temperature using the respective notches n as guides for positioning, thereby producing a bonded wafer 103. As a result, a buried oxide film 101b appears between the two wafers 101 and 102. Thereafter, a predetermined bonding heat treatment is performed on the bonded wafer 103 (FIG. 4B). Thus, a silicon oxide film 103a is formed on the entire exposed surface of the bonded wafer 103.
[0005]
Next, the outer peripheral portion of the active layer wafer 101 is ground in order to remove a bonding failure portion due to the outer peripheral shape of the chamfered wafers 101 and 102 (FIG. 4C). This peripheral grinding is stopped to such an extent that it does not reach the bonding interface. As a result, a small amount of uncut portion 101c appears on the outer peripheral portion of the active layer wafer 101.
Subsequently, the bonded wafer 103 comes into contact with an alkaline etching solution such as KOH, and the uncut portion 101c is melted (FIG. 4D). As a result, the outer peripheral portion of the buried oxide film 101b on the outer peripheral portion of the supporting substrate wafer 102 is exposed. This exposed area is called a terrace.
Next, the surface of the active layer wafer 101 is ground and further polished to produce a bonded SOI substrate in which the thin SOI layer 101A is supported by the supporting substrate wafer 102 from the back side (FIG. 4 ( e)).
[0006]
By the way, notches n are formed on the outer peripheral portion of the wafer 101 for the active layer and the outer peripheral portion of the wafer 102 for the support substrate to facilitate the detection and alignment of the crystal orientation.
At the time of the outer peripheral grinding, the active layer wafer 101 is processed into a small-diameter perfectly circular shape in which the formation portion of the notch n is removed (FIG. 5A). The processing into the perfect circular shape is to solve the following problem. That is, (1) If the outer periphery is ground to the same notch shape as before processing (FIG. 5B), a grinding wheel dedicated to the notch having a small diameter is required separately from the outer periphery grinding wheel. (2) In addition, the number of manufacturing steps of the bonded SOI substrate increases. (3) Furthermore, the grinding wheel dedicated to the notch having a small diameter and low strength must be rotated at a high speed, and the grinding wheel is easily damaged. This is because the grinding speed of the formation portion of the notch n is adjusted to that of another portion of the outer peripheral portion of the wafer. (4) In the outer peripheral grinding wheel, the boundary portion between the normal wafer outer peripheral portion and the notch n forming portion is easily sharpened, and therefore, the device forming surface side of the active layer wafer 101 is easily chipped.
[0007]
[Problems to be solved by the invention]
However, in the conventional method for manufacturing a bonded SOI substrate, when the wafer for the active layer 101 and the wafer for the support substrate 102 are bonded to each other with the notched wafers as described above, the bonded wafer is removed during outer peripheral grinding. The width (removal width) of the terrace portion is d1 (FIG. 5A). Therefore, the width d1 of the terrace is longer than the width d2 of the terrace when the wafer 101 for the active layer and the wafer 102 for the support substrate are each a wafer with an orientation flat (FIG. 5C). As a result, the device formation area of the active layer wafer 101 was reduced. In addition, since the area to be removed by the outer peripheral grinding of the active layer wafer 101 is increased, another problem that the processing time becomes longer and the abrasion of the outer peripheral grinding wheel is accelerated also occurs.
The width of the terrace portion refers to the width of the bonded wafer 103 when viewed from above, on a line orthogonal to the tangent to the outer peripheral surface of the surface silicon layer 101A after removal, from the outer peripheral edge of the active layer wafer 101 before removal, Of the SOI layer 101A of FIG.
[0008]
[Object of the invention]
Therefore, the present invention provides a bonded substrate that can increase the device formation area of the active layer wafer, can shorten the processing time of the outer peripheral grinding, and can further increase the life of the grinding wheel. Its purpose is to provide a method for its manufacture.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, an active layer wafer and a support substrate wafer having a notch formed in a part of an outer peripheral portion are bonded to each other, and an active layer wafer of a bonded wafer obtained by the bonding is bonded. While removing the defective bonding portion of the outer peripheral portion, the thickness of the active layer wafer is reduced to form a surface silicon layer. In the bonded substrate, the outer peripheral portion of the surface silicon layer has a circumferential direction matching the notch. A bonded substrate in which a positioning notch having a notch angle larger than the notch angle of the notch is formed at a position.
As the wafer for the active layer and the wafer for the support substrate, for example, a silicon wafer can be adopted.
As the bonded substrate, for example, a bonded SOI substrate in which a buried oxide film is formed between a surface silicon layer and a supporting substrate wafer can be used. In addition, a substrate in which the surface silicon layer and the support substrate wafer are directly bonded to each other may be used. An example of the surface silicon layer is an SOI layer of a bonded SOI substrate.
[0010]
The thickness of the surface silicon layer is not limited. For example, in the case of a thick surface silicon layer, the thickness is 20 to 50 μm, preferably 30 μm or less. In the surface silicon layer of the thin film, the thickness is 1 to 20 μm.
The alignment notch is formed on a part of the outer peripheral portion of the active layer wafer in order to facilitate various types of alignment with the active layer wafer (for example, alignment with the support substrate wafer during bonding). This is a cutout for the alignment guide. In addition, the alignment notch can be used for determining the crystal orientation and the conduction type.
The notch angle of the alignment notch is not limited. The point is that the angle should be larger than the notch angle of the notch. The shape of the alignment notch may be, for example, an acute or obtuse V-shape. Further, the shape may be an arc shape. Here, the notch angle of the V-shaped notch is the central angle of the V-shape. The notch angle of the notch having the arc shape is an opening angle between a line segment connecting the start point and the intermediate point of the arc and a line segment connecting the intermediate point and the end point of the arc. However, the maximum angle is preferably 180 degrees. When the notch angle is 180 degrees, the alignment notch has an orientation flat shape.
The number of the alignment notches is not limited. One or more may be used.
The size and the number of notches formed on the outer peripheral portion of the supporting substrate wafer are not limited.
[0011]
The invention according to claim 2 is the bonded substrate according to claim 1, wherein a width of the positioning notch is different from a width of removing the defective bonding portion excluding the positioning notch. .
For example, the width of removing the defective bonding portion is made smaller than the width of the alignment notch. Conversely, the width of removal of the defective bonding portion may be longer than the width of the alignment notch.
The width of the alignment notch is the width of the active layer before the notch on a line orthogonal to the peripheral wall of the alignment notch of the surface silicon layer when the bonded wafer is viewed in a plan view with the active layer wafer side facing upward. From the outer peripheral edge of the wafer for use to the outer peripheral edge of the alignment notch after the notch.
Also, the width of removal of the defective bonding portion is, on a line orthogonal to the tangent to the outer peripheral surface of the surface silicon layer excluding the notch for alignment, when the bonded wafer is viewed in a plan view with the wafer side for the active layer facing upward. , The length from the outer edge of the active layer wafer before removal to the outer edge of the surface silicon layer after removal.
[0012]
According to the third aspect of the present invention, a wafer for an active layer in which a notch is formed in a part of an outer peripheral portion and a wafer for a support substrate in which a notch is formed in a part of an outer peripheral portion are formed in the wafer circumferential direction of each notch. A bonding step of aligning and bonding, and a heat treatment step of increasing the bonding strength of the bonded wafer produced by this bonding and forming a silicon oxide film on the entire exposed surface of the bonded wafer; A thickness reducing step of reducing the thickness of the active layer wafer of the bonded wafer with the increased bonding strength, and an outer peripheral removing step of removing the outer peripheral portion of the active layer wafer of the bonded wafer with the increased bonding strength; Positioning the notch forming portion of the active layer wafer from which the outer peripheral portion has been removed, having an angle larger than the notch angle of the active layer wafer. Notch is bonded substrate having a cut portion forming step of forming a.
[0013]
The bonding of the active layer wafer and the support substrate wafer is performed, for example, by laminating both wafers at room temperature.
The heat treatment temperature in the heat treatment step is 800 ° C. or higher, for example, 1100 ° C. The time of the bonding heat treatment is, for example, about 2 hours. Oxygen or the like is used as an atmospheric gas in the thermal oxidation furnace to be used.
The specific configuration of the thickness reducing step is not limited. The point is that the active layer wafer can be reduced in thickness to a thin surface silicon layer. For example, the thickness of the active layer wafer may be reduced by etching. Alternatively, the active layer wafer may be reduced in thickness by sequentially performing surface grinding and surface polishing. Further, the thickness may be reduced only by polishing the surface by appropriately changing the polishing conditions.
In the thickness reduction method by surface grinding and surface polishing, when the surface of the active layer wafer is ground, for example, grinding with a surface grinding wheel is performed. The surface grinding conditions are, for example, using a resinoid grinding wheel of # 300 to # 2000 and grinding the surface until the remaining wafer thickness becomes 10 to 60 μm.
[0014]
As the surface polishing, for example, a bonded wafer whose surface has been ground is mounted on a polishing head of a polishing apparatus, and while a polishing agent (slurry) containing free abrasive grains is supplied in a polishing liquid, the ground surface of the surface silicon layer is ground. Is pressed against a polishing cloth spread on a polishing platen. The polishing apparatus may be a single wafer type polishing apparatus or a batch type polishing apparatus. Further, a wax-type single-side polishing apparatus or a wax-less type apparatus may be used.
Examples of the polishing cloth include a porous nonwoven fabric type obtained by impregnating polyurethane into polyester felt, a foamable urethane type obtained by slicing a block of foamed urethane, and a foamed polyurethane on the surface of a base material in which polyester felt is impregnated with polyurethane. And a suede type in which an opening is formed in the foamed layer by removing the surface layer portion of the polyurethane.
[0015]
The specific configuration of the outer periphery removing step is not limited. In short, it is only necessary to remove a defective bonding portion with the support substrate wafer, which is present on the outer peripheral portion of the active layer wafer. If there is a defective bonding portion, the defective portion is peeled and scattered in a subsequent cleaning step, polishing step, and the like, which becomes a dust generation source, and contaminates and damages the surface of the surface silicon layer (device forming surface). Cause.
For example, as an outer peripheral removing method, the outer peripheral portion of the active layer wafer can be removed by outer peripheral grinding in which the outer peripheral portion of the active layer wafer is ground from the surface side. Further, the outer peripheral portion of the active layer wafer may be removed by etching. In addition, outer periphery grinding and outer periphery etching may be used in combination.
[0016]
Of these, the outer peripheral grinding in the outer peripheral removing step using both the outer peripheral grinding and the outer peripheral etching is performed at the bonding interface, at the vicinity of the bonding interface, or until the outer peripheral grinding reaches the supporting substrate wafer through the bonding interface. You may. For example, in the case of peripheral grinding to the vicinity of the bonding interface, the remaining thickness of the peripheral portion of the active layer wafer after the peripheral grinding is about 10 to 60 μm.
The conditions for the outer periphery grinding are, for example, using a resinoid grinding wheel of # 300 to # 2000 and outer periphery grinding until the remaining wafer thickness becomes 10 to 60 μm.
Further, the uncut portion left after the outer peripheral grinding can be subjected to the outer peripheral etching using an alkaline etching solution. Here, the outer peripheral etching refers to a step of removing an uncut portion of the outer peripheral portion of the active layer wafer including processing damage caused by outer peripheral grinding with an alkaline etching solution. As the alkaline etching solution, for example, KOH, NaOH or the like can be employed. When this outer periphery etching is performed, a portion (remaining portion) of the silicon oxide film formed at the time of the bonding heat treatment remains in a beard-shaped cross section in the region of the uncut portion of the outer periphery of the wafer. The remaining portion of the silicon oxide film is removed by, for example, HF cleaning with an HF cleaning solution.
The order of the thickness reducing step and the outer peripheral removing step may be such that the thickness reducing step is performed first, and then the outer peripheral removing step is performed, or the reverse order.
[0017]
[Action]
According to the method of manufacturing a bonded substrate according to claim 3 or 4, the thickness of the notched active layer wafer bonded to the notched support substrate wafer is reduced, and the outer peripheral portion of the wafer outer peripheral portion is removed. At this time, the notch forming portion of the surface silicon layer is formed with a notch for alignment in place of the notch, so that the surface silicon layer is not a conventional substantially circular shape but a wafer having a shape with a notch for alignment (hereinafter referred to as a wafer). , Wafers with alignment notches). On the other hand, a notch at the time of bonding is formed in the outer peripheral portion of the supporting substrate wafer.
In this manner, the outer periphery removal step of the active layer wafer can be performed by dividing the notch into a notch for alignment and by removing the outer periphery of the other outer periphery of the wafer. In the terrace portion, the width of the notch formation portion and the removal width of the other terrace portions can be individually set, and the outer periphery can be ground.
[0018]
Thus, by including the notch forming portion in the grinding area as in the conventional case, the removal width of the outer peripheral portion of the wafer (the processing length in the wafer radial direction) is longer than in the case of the substantially circular outer peripheral grinding in which the removal width of the wafer is increased. Processing time for removing the outer periphery of the wafer can be reduced.
Of these, according to the invention of claim 4, the entire circumference of the outer peripheral portion of the active layer wafer can be ground using only one kind of outer peripheral grinding wheel.
Further, according to the bonded substrate of claim 1, since the surface silicon layer is a wafer with a notch for alignment and the wafer for a support substrate is a wafer with a notch, compared to the conventional substantially round outer periphery grinding. In addition, the device formation area of the active layer wafer can be increased.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flow sheet showing a method for manufacturing a bonded substrate according to one embodiment of the present invention. FIG. 2 is a longitudinal sectional view of an outer peripheral grinding device used in the method for manufacturing a bonded substrate according to one embodiment of the present invention. FIG. 3A is a plan view of a bonded substrate according to one embodiment of the present invention. FIG. 3B is a plan view of a bonded substrate according to another embodiment of the present invention.
As shown in FIG. 1, first, a single crystal silicon ingot is pulled up by the CZ method, and thereafter, the obtained single crystal silicon ingot is subjected to block cutting, notching, and slicing, and further, the obtained wafer is chamfered. Mirror polishing (including a notch) is performed to prepare an active layer wafer 10 with a notch n having a thickness of 725 μm and a diameter of 8 inches and having a mirror finish. The single crystal silicon ingot may be manufactured by the FZ method. The notch processing is performed by pressing a rotating notch grinding wheel on a part of the outer peripheral surface of the short ingot cut from the block and moving the grinding wheel in the longitudinal direction of the ingot.
On the other hand, a mirror-finished support substrate wafer 20 of the same size with a notch n is prepared by the same manufacturing method as that of the active layer wafer 10 (FIG. 1A). Of these, the insulating silicon oxide film 10a is formed on the entire exposed surface of the active layer wafer 10 by thermal oxidation using a thermal oxidation furnace.
[0020]
Thereafter, the mirror surfaces of both wafers 10 and 20 are overlapped with each other at room temperature in a clean room by using the respective notches n as guides for positioning (FIG. 1B). Thereby, a bonded wafer 30 is formed. By this bonding, the portion of the silicon oxide film 10a interposed between the active layer wafer 10 and the support substrate wafer 20 becomes the buried oxide film 10b.
Next, the bonded wafer 30 is inserted into a quartz reaction tube of a thermal oxidation furnace for bonding, and bonded and heat-treated in an oxygen gas atmosphere. The bonding temperature is 1100 ° C. and the heat treatment time is 2 hours (also FIG. 1B). As a result, the entire exposed surface of the bonded wafer 30 is covered with the silicon oxide film 30a. As a result, the oxide film of the active layer wafer 10 becomes thick.
[0021]
Next, a void inspection by ultrasonic irradiation is performed. The non-defective bonded wafer 30 has an outer peripheral portion of the active layer wafer 10 (excluding a notch n forming portion) in order to remove a defective bonding caused by the outer peripheral shape of the chamfered wafers 10 and 20. Is subjected to peripheral grinding from the device forming surface side using resinoid peripheral grinding wheels # 300 to # 2000 (FIG. 1 (c)). As the outer peripheral grinding device, an outer peripheral grinding wheel 40 having a truncated cone shape is used (FIG. 2). At the time of the outer peripheral grinding, the surface of the bonded wafer 30 on the side of the active layer wafer 10 is vacuum-sucked by the vacuum chuck 41, and the outer peripheral grinding grindstone 40 rotating about the rotation axis 40 a rotates the wafer 10 for the active layer. The outer periphery is cut.
[0022]
If there is a defective bonding portion, the defective portion is peeled and scattered in a subsequent cleaning step, polishing step, and the like, and is adhered to contaminate the surface of the SOI layer. This is because the surface of the SOI layer is damaged during wafer processing in the process. This peripheral grinding is stopped at a depth that does not reach the bonding interface. The thickness of the remaining uncut portion 10c of the outer peripheral portion of the active layer wafer 10 is about 775 μm (in the case of 8 inches). The width D1 of the uncut portion 10c is 2 mm. As a result, of the notch n formation portion, the V-shaped outwardly open end is removed. The rotation speed of the resinoid outer peripheral grinding wheel is 5000 to 8000 rpm, and the rotation speed of the active layer wafer 10 is 0.2 to 1 rpm.
[0023]
Then, using the same outer circumference grinding resinoid outer circumference grinding wheel, an orientation flat (positioning notch) OF having a size to completely remove the notch n is formed in the formation portion of the notch n of the active layer wafer 10. (FIGS. 1D and 1D). At this time, for example, the maximum width D2 of the orientation flat OF is 5 mm (FIG. 3A). That is, the maximum width D2 of the orientation flat OF is 3 mm longer than the width D1 (2 mm) of the uncut portion 10c. Alternatively, the orientation flat OF 'may be formed in a mountain shape that resembles the shape of the notch n of the supporting substrate wafer 20 (FIG. 3B). The rotation speed of the resinoid outer peripheral grinding wheel during this orientation flat processing is 5000 to 8000 rpm.
Then, the uncut portion 10c is removed by alkali etching (FIG. 1 (e)). That is, the bonded wafer 30 is immersed in an alkaline etching solution such as KOH, and the uncut portion 10c is dissolved. Thus, the outer peripheral region of the support substrate wafer 20, specifically, the outer peripheral portion (terrace portion) of the buried oxide film 10b is exposed.
[0024]
Next, the surface of the active layer wafer 10 is ground from the device forming surface side thereof using # 300 to # 2000 resinoid grinding wheels to form a thinned SOI layer 10A (FIG. 1 (f)). At this time, the surface grinding amount is 600 to 700 μm, and the thickness of the SOI layer 10A reduced by the processing is about 20 μm. A bonded wafer 30 with the active layer wafer 10 facing upward is held in vacuum on a single-wafer porous ceramic chuck (not shown), and is rotated in this state. On the other hand, a resinoid grinding wheel for surface grinding is rotating above the surface, and is lowered at a constant speed so that the active layer wafer 10 is ground. The rotational speed of the resinoid grinding wheel for surface grinding is 2000 to 6000 rpm, and the rotational speed of the porous ceramic chuck is 10 to 300 rpm.
[0025]
Then, the ground surface of the SOI layer 10A is polished (also FIG. 1 (f)). Specifically, the bonded wafer 30 whose surface has been ground on the lower surface of a polishing head of a single-wafer polishing apparatus (not shown) is held with the active layer wafer 10 side facing downward. Next, while the abrasive (slurry) is supplied at a predetermined flow rate, the ground surface of the active layer wafer 10 is pressed against a polishing cloth spread on the upper surface of a polishing platen to polish the surface. As the polishing cloth, a soft nonwoven pad manufactured by Rodale, Suba600 (Asker hardness 80 °) is employed. The polishing amount at this time is 10 to 20 μm. As a result, an orientation flat OF is formed on a part of the outer periphery of the SOI layer 10A, and a bonded SOI substrate having a notch n formed on a part of the outer periphery of the supporting substrate wafer 20 is produced (FIG. 3A). ).
Thereafter, the obtained bonded SOI substrate is washed, packed in a wafer case or the like, and then shipped to a device maker.
[0026]
As described above, the outer peripheral portion of the outer peripheral portion of the active layer wafer 10 is subjected to the outer peripheral grinding except for the portion where the notch n is formed. Since the orientation flat OF is formed, in the terrace portion, the width D2 in the wafer radial direction of the portion where the notch n is formed and the other width D1 can be separately set and the outer periphery can be ground. Therefore, the device formation area of the active layer wafer 10 can be increased as compared with the conventional case where the outer peripheral grinding of a substantially perfect circular shape in which the width of removal of the terrace portion is long is performed. Further, the processing time for the outer peripheral grinding of the wafer for active layer 10 is also reduced. Further, the entire circumference of the outer peripheral portion of the active layer wafer including the formation portion of the notch n can be ground using only one outer peripheral grinding wheel.
[0027]
【The invention's effect】
According to the bonded substrate of claim 1 of the present invention, the surface silicon layer is a wafer with a notch for positioning and the wafer for a support substrate is a wafer with a notch. Thus, the device formation area of the active layer wafer can be increased.
[0028]
According to the method for manufacturing a bonded substrate according to claims 3 and 4, the outer peripheral removal step of the active layer wafer is partially removed by changing the notch to the notch for positioning. Since removal can be performed separately from the removal of the outer peripheral portion of the wafer, the processing time for removing the outer periphery can be reduced as compared with the conventional substantially circular outer periphery grinding.
Of these, according to the invention of claim 4, the entire circumference of the outer peripheral portion of the active layer wafer can be ground using only one kind of outer peripheral grinding wheel.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a method for manufacturing a bonded substrate according to one embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of an outer peripheral grinding device used in the method for manufacturing a bonded substrate according to one embodiment of the present invention.
FIG. 3A is a plan view of a bonded substrate according to one embodiment of the present invention.
(B) is a plan view of a bonded substrate according to another embodiment of the present invention.
FIG. 4 is a flow sheet showing a method for manufacturing a bonded substrate according to a conventional means.
FIG. 5A is a plan view of a bonded substrate according to a conventional means.
(B) is a plan view of another bonded substrate according to the conventional means.
(C) is a plan view of yet another bonded substrate according to the conventional means.
[Explanation of symbols]
10 wafer for active layer,
10A SOI layer (surface silicon layer),
10a silicon oxide film,
20 wafer for supporting substrate,
30 bonded wafers,
n notch,
OF orientation flat (notch for positioning).

Claims (4)

The wafer for the active layer and the wafer for the support substrate having a notch formed in a part of the outer peripheral portion are bonded to each other, and a bonded defect portion of the outer peripheral portion of the active layer wafer of the bonded wafer obtained by this bonding is removed. And a bonded substrate in which the active layer wafer is reduced in thickness to form a surface silicon layer,
A bonded substrate having a notch for positioning having a notch angle larger than a notch angle of the notch formed at a circumferential position corresponding to the notch in an outer peripheral portion of the surface silicon layer. 2. The bonded substrate according to claim 1, wherein a width of the positioning notch and a width of removing the defective bonding portion excluding the positioning notch are different. Laminating an active layer wafer with a notch formed in a part of the outer peripheral part and a support substrate wafer with a notch formed in a part of the outer peripheral part by aligning the positions of the notches in the circumferential direction of the wafer Process and
A heat treatment step of increasing the bonding strength of the bonded wafer produced by this bonding and forming a silicon oxide film on the entire exposed surface of the bonded wafer;
A thickness reduction step of reducing the thickness of the active layer wafer of the bonded wafer with the increased bonding strength;
An outer peripheral removing step of removing the outer peripheral portion of the active layer wafer of the bonded wafer with the increased bonding strength;
A notch forming step of forming a notch for positioning having a notch angle larger than the notch angle of the notch of the active layer wafer on the notch forming portion of the active layer wafer from which the outer peripheral portion has been removed. Substrate manufacturing method. 4. The method for manufacturing a bonded substrate according to claim 3, wherein the outer peripheral grinding wheel used in the outer peripheral removing step is the same as the notched part forming grindstone used in the notched part forming step.

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