JP2002176018A - Method for manufacturing soi wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an SOI wafer having proper processing accuracy and yield without necessity of a wafer with an oxide film to manufacture the SOI wafer having active layers of different thicknesses with excellent productivity. SOLUTION: The method for manufacturing the SOI wafer comprises the steps of preparing the wafer 1a obtained by laminating and adhering a polishing surface 7 of the wafer 5 for a support to an oxide film 10 formed over a polishing surface 9 of the wafer 6 for the active layer and integrating them, laminating the laminated wafer 1a to a laminating plate 15, grinding it, setting the plate 15 of the state in which the ground laminated wafer 1b is laminated to project at a polishing margin from a lower end face 29 of the guide ring 27 of the polishing unit 21 for holding the plate 15 with the wafer 1b, polishing it by a polishing cloth 22, and stopping the unit 21 by the contact of the lower end face 29 of the ring 27 with the cloth 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an SOI wafer, and more particularly to a method for manufacturing an SOI wafer having good processing accuracy and yield and excellent productivity.

[0002]

2. Description of the Related Art SOI (silicon on silicon) in which a thin film silicon single crystal is formed on an insulator such as an insulating layer or an insulating film.
Insulator)
In view of high speed, low voltage, low power consumption, miniaturization ability, simplification of processes, and the like, it has been attracting attention as a next-generation semiconductor and is being developed.

[0003] As shown in FIG.
It has a structure in which an active layer (Si) 4 of 1-5 μm thin film silicon is formed on a silicon substrate 2 of 100-800 μm via an oxide film (SiO 2) 3 of about 1 μm.
As an I-wafer manufacturing method, there is an adhesive bonding method.

An adhesive laminating method having a manufacturing process as shown in FIG. 2 is a method of laminating two silicon wafers 5 and 6 polished to a mirror surface with high precision. A polished surface 7 of the wafer 5 and an oxide film 10 formed to a thickness of about 1 μm are bonded and integrated to a polished surface 9 of the active layer wafer 6 including a region to be the other surface active layer 8. This is for manufacturing a bonded wafer 1a.

Further, the surface active layer 8 is processed to a thickness of 1 to 5 μm by using a high-precision processing method including a grinding step and a polishing step, and an SOI layer 10 having an oxide film thin layer 10 of about 1 μm formed in between. This is a method for manufacturing the wafer 1.

[0006] The conventional grinding process is a generally used method, in which the bonded wafer 1a is ground using a # 320 diamond grindstone for rough grinding and a # 2000 diamond grindstone for precision grinding. The bonded wafer 1b which has been finished to the remaining thickness and ground is manufactured.

In the conventional polishing step, as shown in FIG. 6, a bonded wafer 1b is bonded to a central portion of a bonding plate 42 of a polishing apparatus 41 with an adhesive wax 43, and furthermore, is fixed to an outer peripheral portion of the bonding plate 42. Four wafers 44 with an oxide film having a thickness of 4 mm are adhered with adhesive wax 43. The bonding plate 42 on which the bonded wafer 1b and the wafer 44 with an oxide film are bonded is a polishing device 4
1 and a polishing cloth is stuck thereon to apply pressure and rotation to the polishing platen. By the action of the slurry, the bonded wafer 39 is processed into a predetermined thickness of the active layer 4 and the SOI wafer 1 is manufactured.

In the conventional polishing apparatus 41, the rotation of the polishing platen is stopped by the wafer 44 with an oxide film disposed around the bonded wafer 1b so that the active layer 4 having a predetermined thickness is obtained. is there. The oxide film of the wafer 44 with an oxide film is hard, and when the polishing cloth comes into contact with the oxide film, a large resistance is applied to the polishing cloth, and the rotation of the polishing platen is stopped.
In order to obtain a flat and uniform active layer 4 having a predetermined thickness, a minimum of three wafers 44 with an oxide film are necessary, and it takes time to attach and detach the wafers 44 with an oxide film to and from the attaching plate 42. Productivity had declined.

When three or more wafers with an oxide film 44 are bonded, the thickness of the active layer 4 of the SOI wafer 1 is unstable because the adhesive wax layer 43 varies. Further, the active layer 4 of the SOI wafer 1 to be manufactured
When the thicknesses of the wafers are different, wafers with oxide films having different thicknesses must be prepared each time, and wafers with oxide films of various thicknesses are required.

[0010]

In order to manufacture an SOI wafer having an active layer having a different thickness without using an oxide film wafer to polish the active layer to a predetermined thickness. Without the need for wafers with different oxide films
There is a demand for a method of manufacturing an SOI wafer having a high processing accuracy, a good yield, and excellent productivity, and the present invention has been made in consideration of the above-described circumstances. In order to manufacture SOI wafers with active layers of different thicknesses without using wafers with oxide films, the need for wafers with oxide films with different thicknesses is high, processing accuracy and yield are good, and productivity is improved. An object of the present invention is to provide an excellent method for manufacturing an SOI wafer.

[0011]

According to a first aspect of the present invention, there is provided a polishing method comprising the steps of attaching a polished surface of a wafer for a support and an oxide film formed on a polished surface of a wafer for an active layer. Prepare a bonded wafer that has been bonded and integrated, paste this bonded wafer on the bonding plate and perform grinding. The polishing device is set so that it protrudes from the lower end surface of the guide ring of the polishing device by the amount of the polishing allowance, and is polished with a polishing cloth. The gist is to provide a method for manufacturing an SOI wafer.

In the invention of claim 2 of the present application, the setting of the attaching plate is performed by attaching the attaching plate so as to be flush with the guide ring, and then retreating the guide ring by a polishing allowance. Item 1 SOI
The gist is that it is a wafer manufacturing method.

According to a third aspect of the present invention, there is provided a method for manufacturing an SOI wafer according to the first or second aspect, wherein a diamond layer is formed on a lower end surface of the guide ring. .

According to the invention of claim 4 of the present application, a groove for reducing an area in contact with a mounting surface of a grinding device and a polishing device is formed on a non-sticking surface of the sticking plate. SOI according to item 1
The gist is that it is a wafer manufacturing method.

According to a fifth aspect of the present invention, there is provided a method of manufacturing an SOI wafer according to the fourth aspect, wherein the groove is a spiral V-shaped groove.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an SOI wafer according to the present invention will be described below with reference to the drawings.

The bonded wafer 1a used in the method for manufacturing an SOI wafer according to the present invention is manufactured according to the SOI wafer manufacturing process as shown in FIG.

Bonded wafer manufacturing process: For example, two silicon wafers 5 and 6 having a thickness of 600 to 800 μm polished to a mirror surface with high precision are prepared, and a wafer 5 for a support serving as one support is prepared. Polished surface 7 and the other 1-5 μm
An oxide film (S) formed to a thickness of about 1 μm on the polished surface 9 of the active layer wafer 6 including a region to be the surface active layer 8 having a thickness of
iO2) 10 to form a bonded wafer 1a.

Grinding process: The surface active layer 8 of the active layer wafer 6 is ground by the grinding device 11 having a structure as shown in FIG. Is obtained.

The grinding device 11 used in the grinding process includes, for example, a vacuum chuck table 13 having a vacuum chuck 12,
An attaching plate 15 fixed to the vacuum chuck base 13 by vacuum suction and having a spiral V-shaped groove 14 formed on the back surface which is a non-applied surface;
And a diamond whetstone 16 which is arranged to be able to move up and down and is driven to rotate by a motor (not shown).

Accordingly, in the step of grinding the bonded wafer 1a, the adhesive wax 17 is applied to the bonded wafer 1a to a uniform thickness by spin coating, and then bonded to the bonding plate 15 which has been heated in advance. This bonded wafer 1
a is attached to the grinding plate 11
Is mounted on the vacuum chuck table 13 that is driven to rotate, is sucked by the vacuum chuck 12, and is fixed to the vacuum chuck table 13.

At this time, a spiral V-shaped groove 14 is formed on the back surface of the attaching plate 15 so as not to lower the vacuum suction function, and the attaching plate 15 is securely fixed to the vacuum chuck table 13. Since the contact area between the vacuum chuck table 13 and the attaching plate 15 is reduced, the relatively thin attaching plate 15 is not deformed by the adhesion of dust or abrasive, and the wafer 1a is ground with high precision.

Thereafter, rough grinding is performed with a diamond grindstone 16, for example, a # 320 diamond grindstone.
The bonded wafer 1b is manufactured by grinding with a 000 diamond grindstone and precision processing to a thickness of 20 μm leaving a polishing allowance.

Since the grinding process is performed after the bonded wafer 1a is bonded to the bonding plate 15, a dent is generated in the bonded wafer 1b after grinding due to dust or the like attached to the bonded wafer 1a or the vacuum chuck base 13. Can be prevented, and a decrease in yield can be prevented.

Polishing step: The bonded wafer 1b ground in the pre-grinding step is polished by the single wafer polishing apparatus 21 having a structure as shown in FIG. 1 to a surface active layer 8 having a thickness of about 20 μm. The surface active layer 4 having a thickness of 1 to 5 μm is obtained.

The single-wafer polishing apparatus 21 includes a platen 23 on which a polishing cloth 22 is provided and driven and rotated; a slurry pipe 24 for supplying a slurry S to the polishing cloth 22;
5, a guide ring 27 having a substantially ring shape is fitted in the polishing head 26 via a spigot 28 so as to be able to advance and retreat. The lower surface 29 of the guide ring 27 is formed of a diamond layer, and the height thereof can be adjusted by a height adjustment screw 30, and can be fixed at a predetermined position by a fixing screw 31. The bonding plate 15 used in the pre-grinding step is inserted into the guide ring 27 of the polishing head 26, and can be fixed at a predetermined position by a fixing screw 32.

Therefore, in the polishing step of the bonded wafer 1b, as shown in FIG. 4, the bonding plate 15 on which the bonded wafer 1b ground in the previous step is bonded is inserted into the guide ring 27 and the surface active layer 8 is formed. And guide ring 27
Are set so that the diamond layer 29 forming the lower end surface of the same is flush with the surface. Thereafter, as shown in FIG. 1, the bonded wafer 1b is polished to a predetermined thickness t1 (t1 =
The height adjusting screw 30 is rotated and adjusted so as to obtain the surface active layer 8 of 1 to 5 μm), the guide ring 27 is retracted by the polishing allowance t2 (t2 = 15 to 19 μm), and the fixing screw 31 is removed. , 32.

The guide ring 27 retreats for the polishing allowance t2,
The bonded wafer 1b is attached to the bonding plate 15 so that the bonded wafer 1b is in a protruding state for the polishing allowance t2.
In this state, the bonding plate 15 and the polishing head 26 are rotated, and the polishing plate 24 is pressed against the rotating polishing cloth 22 while supplying the polishing agent 24 to perform the polishing allowance t2. When the bonded wafer 1b is polished by the polishing allowance t2, the diamond layer 29 comes into contact with the polishing pad 22, but the diamond layer 29 has high hardness.
9, a large resistance is applied, the rotation of the single wafer polishing apparatus 21 is stopped, and the polishing process is completed, so that the SOI wafer 1 is manufactured.

In this polishing step, while the bonded wafer 1b ground in the previous step is still attached to the attaching plate 15, the attaching plate 15 is attached to the single wafer polishing apparatus 2.
Since the polishing is performed by setting to 1, the bonded wafer 1b
Cracks and chips are not generated, and the production yield can be improved.

Further, the guide ring 27 having the diamond layer 29 formed on the lower end face is retracted by the polishing allowance t2,
Since the surface active layer 4 having the predetermined thickness t1 is obtained, easy and precise polishing can be performed, and the productivity is good.

The method of manufacturing an SOI wafer according to the present invention is not limited to a single wafer type in which a grinding device and a polishing device are processed by attaching one bonded wafer to one attaching plate. It is also applicable to a batch type in which a plurality of bonded wafers are attached to a plate and processed.

Further, the present invention can be applied to polishing of a CPM in a device process.

[0033]

EXAMPLE A mirror-polished silicon wafer having a thickness of 725 μm and a silicon wafer having a polishing surface having an oxide film having a thickness of 1 μm were prepared.

After washing, lamination is performed at room temperature.
Perform bonding annealing at 100 ° C. for 2 hours to obtain a thickness of 1450 μm.
m of bonded wafers were obtained.

A bonding wax is applied to the bonded wafer by spin coating to a uniform thickness, and is heated in advance and is bonded to a bonding plate having a spiral V-shaped groove formed on a non-bonding surface, and an oxide film is formed by a grinding device. The formed wafer was ground to about 705 μm, leaving a polishing allowance of about 20 μm.

The thickness of the active layer was measured using FTIR, and data for determining how many μm should be polished to form a 2 μm active layer was obtained.

While the bonded wafer was bonded, the bonding plate was set in the polishing apparatus such that the polished surface of the bonded wafer and the lower end surface (diamond layer) of the guide ring coincided with each other. Polishing was performed by retracting the guide ring by 18 μm.

An SOI wafer having an active layer thickness of 2 μm, an oxide film thickness of 1 μm, a substrate thickness of 725 μm, and no scratches or deformation on the active layer was obtained.

[0039]

According to the method for manufacturing an SOI wafer according to the present invention, an SOI wafer having an active layer of a different thickness does not require a wafer with an oxide film to polish the active layer to a predetermined thickness. Does not require wafers with oxide films of different thicknesses to produce
A method for manufacturing an SOI wafer having excellent productivity can be provided.

Grinding and polishing are performed with the bonded wafer attached to the attaching plate.
It is possible to prevent dents from occurring in the bonded wafer after processing, thereby preventing a reduction in yield.

After attaching the set of attachment plates so that the attachment plates are flush with the guide rings, the guide rings are retracted by the polishing allowance, so that a predetermined thickness can be obtained without using wafers with oxide films having different thicknesses. A surface active layer having a thickness can be obtained, polishing can be performed easily and precisely, and productivity is good.

Since the diamond layer is formed on the lower end surface of the guide ring, the lower end surface is not worn, so that precise polishing can be performed and the durability of the guide ring is improved.

Since the groove for reducing the area in contact with the mounting surface of the grinding device and the polishing device is formed on the non-bonding surface of the bonding plate, the contact area between the mounting surface of the grinding device and the polishing device and the bonding plate is reduced. The relatively thin sticking plate is not deformed by the adhesion of dust and abrasives, and the wafer can be processed with high accuracy.

Since the groove is a spiral V-shaped groove,
The relatively thin attachment plate is not deformed more effectively by the adhesion of dust and abrasives, and the wafer can be processed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a polishing apparatus used in a method for manufacturing an SOI wafer according to the present invention.

FIG. 2 is a process chart of a method for manufacturing an SOI wafer according to the present invention.

FIG. 3 is a conceptual diagram of a grinding apparatus used in the method for manufacturing an SOI wafer according to the present invention.

FIG. 4 is a conceptual diagram showing a setting process of an attaching plate of a polishing apparatus used in the method for manufacturing an SOI wafer according to the present invention.

FIG. 5 is a conceptual diagram of a general SOI wafer.

FIG. 6 is a conceptual diagram of a grinding apparatus used in a conventional SOI wafer manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 SOI wafer 1a Laminated wafer 1b Laminated wafer 2 Insulator substrate 3 Oxide film 4 Active layer 5 Silicon wafer 6 Silicon wafer 7 Polished surface 8 Surface active layer 9 Polished surface 10 Oxide film 11 Grinding device 12 Vacuum chuck 13 Vacuum chuck table 14 V Groove 15 Adhesion Plate 16 Diamond Grinding Stone 17 Adhesive Wax 21 Single Wafer Polishing Device 22 Polishing Cloth 23 Platen 24 Slurry Pipe 25 Rotating Disk 26 Polishing Head 27 Guide Ring 28 Inlay 29 Diamond Layer 30 Height Adjusting Screw 31 Fixing Screw 32 Fixing screw S slurry

Claims (5)

[Claims] 1. A bonded wafer in which a polished surface of a support wafer and an oxide film formed on a polished surface of an active layer wafer are bonded and integrated to prepare a bonded wafer, and the bonded wafer is bonded. Attached to the plate and ground, set the bonded plate with the ground bonded wafer stuck so that the bonded wafer protrudes from the lower end surface of the guide ring of the polishing device that holds the bonded plate by the amount of polishing allowance. And polishing the workpiece with a polishing cloth, and stopping the polishing apparatus when the polishing cloth comes into contact with the lower end face of the guide ring. 2. The SOI according to claim 1, wherein the setting of the attaching plate is performed by attaching the attaching plate so as to be flush with the guide ring, and then retreating the guide ring by a polishing allowance. Wafer manufacturing method. 3. The method for manufacturing an SOI wafer according to claim 1, wherein a diamond layer is formed on a lower end surface of the guide ring. 4. A non-sticking surface of the sticking plate is provided with a groove for reducing an area in contact with a mounting surface of a grinding device and a polishing device.
The method for manufacturing an SOI wafer according to any one of the above items. 5. The method according to claim 4, wherein the groove is a spiral V-shaped groove.