JP3216583B2 - Manufacturing method of bonded SOI substrate - Google Patents

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 a bonded SOI substrate, which is bonded and bonded with a dielectric layer interposed between a first semiconductor wafer and a second semiconductor wafer, and a protection method used for the bonded SOI substrate. The present invention relates to an agent application device.

[0002]

2. Description of the Related Art Conventionally, there has been known an SOI (Silicon on Insulator) substrate formed by bonding a first semiconductor wafer and a second semiconductor wafer with a dielectric layer interposed therebetween. In the production of a bonded SOI substrate, the first semiconductor wafer serving as a support substrate and the second semiconductor wafer serving as an element forming layer are bonded with a dielectric layer interposed therebetween to form a bonded semiconductor wafer. 2. Description of the Related Art A manufacturing method for reducing the thickness of a second semiconductor wafer to a predetermined thickness is known.

For example, as shown in FIG. 5, a dielectric layer 5 is formed on one of semiconductor wafers 1 and 2 (see FIG. 5A), and the mirror surfaces of these semiconductor wafers 1 and 2 are joined together. Thus, an adhesive wafer 3 is formed (see FIG. 5B). Bonding is strengthened by heat treatment in an oxidizing atmosphere after bonding, and an oxide film 6 is formed on the outer periphery.
(3)).

In this type of semiconductor wafer, sagging occurs at the peripheral edge of the wafer during mirror polishing, and a gap occurs at the peripheral edge of the bonded wafer 3 bonded and bonded due to the sagging, and an unbonded portion is generated. I do. Such a non-adhered portion is peeled and scattered when a wafer to be an element forming layer is thinned to several μm in a process after forming a bonded wafer, and a part of the unadhered portion adheres to the surface and is processed during processing. It is necessary to remove them beforehand because they may cause damage or cause pattern breakage during element formation.

[0005] For this reason, unbonded portions generated at the peripheral portion of the bonded wafer 3 are removed. In this case, the region including the unbonded portion between the semiconductor wafer 1 and the semiconductor wafer 2 is ground in the thickness direction until just before the bonding interface (FIG. 5).
(See (4)), the grinding portion 8 is removed by etching using an alkaline etching solution (KOH aqueous solution) or the like (see FIG. 5 (5)). In addition, 10 is a grinding part after etching.

After that, the oxide film 6 is formed with a hydrogen fluoride solution or the like.
Is removed (see FIG. 5 (6)), and the element forming layer is ground (FIG. 5
(See (7)), mirror finishing is performed (see FIG. 5 (8)), and a bonded SOI substrate is formed.

[0007]

However, the bonding S
In the step of forming the OI wafer, the first semiconductor wafer or the second semiconductor wafer forming the bonded wafer is formed by a force applied from a grindstone such as a diamond blade at the time of grinding when removing an unbonded portion at the peripheral edge of the bonded wafer. In some cases, the semiconductor wafer may be severely cracked or the edges may be chipped, resulting in an inconvenience that the yield is reduced.

For example, as shown in FIGS. 4 (a) and 4 (b), a grindstone is used to grind an unbonded portion of the peripheral portion of the bonded wafer 3 on which the first and second semiconductor wafers are bonded. From 18 a force is directly applied to the unbonded part during grinding and polishing,
In some cases, the edge of the bonded wafer 3 was severely cracked or chipped along the direction of the force (the arrow in the figure indicates the direction in which the force was applied).

Further, particles such as wafer fragments generated by grinding may be scattered to the dielectric layer interposed between the bonded wafers, and the embedded oxide film as the dielectric layer may be damaged. If the oxide film is scratched in this way, the scratch is selectively etched at the time of subsequent etching, and an etch pit is generated, resulting in a defective product.

Therefore, the present invention solves the above-mentioned problems by bonding and bonding a first semiconductor wafer and a second semiconductor wafer, and protecting the peripheral portion of the bonded wafer with wax or the like. A bonded SOI substrate that can prevent cracks and chips from occurring during edge grinding of the bonded wafer, and also prevents buried oxide films from being damaged by scattered particles and the like, thereby improving the yield rate. It is an object of the present invention to provide a method for producing the same and a protective agent applying device used for the method.

[0011]

According to a method for manufacturing an SOI substrate according to the present invention, a dielectric layer is provided on one or both of a first semiconductor wafer and a second semiconductor wafer, and mirror surfaces of these semiconductor wafers are connected to each other. a step of adhesion is caused to adhere by heat treatment in an oxidizing atmosphere, the unbonded portion serving generated in the peripheral portion of the first semiconductor wafer including
Grinding a region to be damaged to a thickness at which the second semiconductor wafer is not damaged. When grinding the peripheral portion of the first semiconductor wafer, the first semiconductor wafer and the second semiconductor wafer are ground. A method of manufacturing a bonded SOI substrate having a configuration in which the semiconductor wafer bonded by applying a protective material to a peripheral portion of the substrate is protected, and cracking, chipping, and the like of the wafer during grinding are prevented.

Thus, the first semiconductor wafer and the second semiconductor wafer
When a protective agent such as wax is applied to the peripheral portions of the first and second semiconductor wafers after bonding the semiconductor wafers, the protective agent serves as a buffer, and the force applied to the semiconductor wafers during grinding and polishing is dispersed. In addition, cracking and chipping of the semiconductor wafer can be prevented, and the yield can be improved.

Further, since a protective agent such as wax is applied to the peripheral portions of the first semiconductor wafer and the second semiconductor wafer, the peripheral portions of the first semiconductor wafer and the second semiconductor wafer are filled with a buried oxide film interposed between the first and second semiconductor wafers. Particles and the like generated during grinding and polishing can be prevented from entering, and the yield rate can be further improved.

[0014]

[0015]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

FIG. 1 is a process chart showing a method for manufacturing a bonded substrate according to the present invention.

A method of manufacturing a bonded substrate according to the present invention will be described with reference to a process chart showing the manufacturing method of FIG.

As shown in FIG. 1, semiconductor wafers 1 and 2
Is formed into a predetermined shape by mirror finishing or the like (see FIG. 1).
(1)), one of the semiconductor wafers 1 and 2,
In this example, a dielectric layer 5 serving as a buried oxide film is formed on a first semiconductor wafer (see FIG. 1 (2)). Next, these semiconductor wafers 1 and 2 are bonded together with their mirror surfaces to form an adhesive wafer 3 (see FIG. 1 (3)). Then, after bonding, heat treatment (for example, 1,100 ° C. ×
2Hr) to form an oxide film 6 on the outer periphery of the bonding wafer 3 (see FIG. 1 (4)).

Thereafter, a wax 7 serving as a protective agent is applied to the peripheral portion of the bonding wafer 3 by a method described later to protect the bonding wafer 3 (see FIG. 1 (5)).

As described above, the wax 7 is bonded to the bonding wafer 3
Is applied to the peripheral portions of the semiconductor wafers 1 and 2 and serves as a cushioning material for the force applied to the semiconductor wafers 1 and 2 during grinding, thereby preventing the semiconductor wafers 1 and 2 from being cracked or chipped. Further, since the peripheral portion of the bonding wafer 3 is protected by the wax 7, it is possible to prevent particles or the like generated during grinding from entering the dielectric layer 5 between the semiconductor wafers 1 and 2. Grinding can be performed without damaging the oxide film 5 and the oxide film 6.

Thereafter, the non-contact portion generated on the outer peripheral portion of the bonding wafer 3 together with the wax 7 is removed. After grinding, the wax 7 applied to the peripheral portion is removed with a solvent or the like. In this case, the region including the unbonded portion between the semiconductor wafer 1 and the semiconductor wafer 2 is ground in the thickness direction to just before (approximately 50 μm before) the bonding interface (FIG. 1 (6)).
reference).

Further, an alkaline etching solution (TMA)
H: Tetramethylammonium hydroxide aqueous solution, APW:
Using a mixture of ethylenediamine, pyrocatechol and water), the destruction layer and the silicon on the oxide film are removed by grinding the grinding portion 8 (see FIG. 1 (7)). Here, reference numeral 11 in the figure denotes a ground portion after etching with the APW solution or the TMAH solution. Then, the element formation layer is ground (FIG. 1)
(Refer to (8)) to perform mirror finishing and the like (FIG. 1)
(9)). In this example, a process of forming a bonded SOI wafer without removing an oxide film formed on the back surface of the bonded SOI wafer is shown. In the above etching, the oxide film remaining on the outer peripheral portion is pulverized and flattened in the steps of grinding and mirror finishing the element formation layer.

Next, a wax coating apparatus for applying the wax 7 to the above-mentioned bonded wafer 3 will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram of a wax application device 12 that applies wax to an outer peripheral portion of an adhesive wafer.

As shown in FIG. 2, the wax coating device 12
Comprises a vacuum chuck 13 for holding the bonding wafer 3, a motor 14 for rotating the vacuum chuck 13, a wax holding container 15, a wax supply nozzle 16 connected to the wax holding container 15, and a hot air heater 17. Have been.

The wax supply nozzle 16 is provided at a position in contact with the peripheral edge of the adhesive wafer 3 held by the vacuum chuck 13.

The bonded wafer 3 held by the vacuum chuck 13 is rotated by a motor 14
, And a certain amount of wax is supplied from the wax nozzle 16 to the periphery of the bonding wafer 3, and a certain amount of wax is applied to the entire periphery of the bonding wafer 3. .

FIG. 3 is an enlarged view of the peripheral portion of the adhesive wafer whose peripheral portion is coated with wax.

As shown in FIG. 3, when the wax 7 is applied to the peripheral portion of the bonding wafer 3, the force applied from the grindstone 18 or the like of the grinding device or the like during grinding is not directly applied to the wafer 3, and the wax 7 is buffered. Since the force is dispersed as a material, cracking and chipping of the wafer 3 can be prevented.

If the outer edge of the adhesive wafer is protected by the wax, particles such as dust generated during grinding can be prevented from entering the dielectric layer, and the dielectric layer is damaged by the particles. ,
It is possible to prevent the occurrence of etch pits and the like later, and to improve the yield rate.

[0031]

As described above, the method for manufacturing a bonded SOI substrate according to the present invention uses the first semiconductor wafer.
A dielectric material on one or both of the second semiconductor wafer and the second semiconductor wafer
Layers, and mirror surfaces of these semiconductor wafers
Step of bonding by heat treatment in an oxidizing atmosphere
And unconnected portions generated at the periphery of the first semiconductor wafer.
A region including a portion to be attached to the second semiconductor wafer.
Grinding to a thickness that does not cause damage to the
When grinding the peripheral portion of the first semiconductor wafer, a protective material such as wax is applied to the peripheral portions of the first semiconductor wafer and the second semiconductor wafer. The force applied to the semiconductor wafer at the time of grinding and polishing is dispersed, so that the semiconductor wafer can be prevented from cracking or chipping, and the yield can be improved.

The peripheral portions of the first semiconductor wafer and the second semiconductor wafer are coated with a protective agent such as wax, so that the peripheral portions of the first semiconductor wafer and the second semiconductor wafer are filled with a buried oxide film interposed between the first and second semiconductor wafers. Particles and the like generated during grinding and polishing can be prevented from entering, and the buried oxide film 5 and the oxide film 6 can be prevented from being damaged, and the yield can be improved.

[0033]

[0034]

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a bonded SOI substrate according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating a wax application device for a bonded SOI substrate according to the present invention.

FIG. 3 is a partially enlarged view showing an outer edge portion of the bonded SOI substrate according to the present invention.

4A and 4B are partially enlarged views showing an outer edge portion of a bonded SOI substrate according to a conventional example.

FIG. 5 is a process chart showing a method for manufacturing a bonded SOI substrate according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st semiconductor wafer 2 2nd semiconductor wafer 3 Adhesion wafer 5 Dielectric layer 6 Oxide film 7 Wax 8 Grinding part 10 Grinding part 11 Grinding part 12 Wax coating device 13 Vacuum chuck 14 Motor 15 Wax holding container 16 Wax supply Nozzle 17 Hot air heater 18 Whetstone

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/304 622 H01L 21/02 H01L 27/12

Claims (1)

(57) [Claims] A step of having a dielectric layer on one or both of a first semiconductor wafer and a second semiconductor wafer, bringing mirror surfaces of these semiconductor wafers into close contact with each other, and bonding them by heat treatment in an oxidizing atmosphere; Including the unbonded portion generated at the peripheral portion of the first semiconductor wafer
Grinding a region to be damaged to a thickness at which the second semiconductor wafer is not damaged. When grinding the peripheral portion of the first semiconductor wafer, the first semiconductor wafer and the second semiconductor wafer are ground. A method for manufacturing an SOI substrate, comprising applying a protective material to a peripheral portion of the SOI substrate.