JPH08107193A - Manufacture of soi substrate - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing an SOI substrate in which the generation of a crystalline defect (pit) is prevented without a grinding stress to a laminated wafer and which has better production efficiency than that of a prior art method for manufacturing. CONSTITUTION: A laminated wafer 4 is obtained by laminating a support substrate 2 and an activated substrate 3. The upper surface of the substrate 3 is planely ground. A cutter 1 is provided at a dicing machine. The wafer 4 is horizontally rotated, and the cutter 1 is rotated substantially perpendicularly to the substrate 3. The substrates 2, 3 are cut at the same plane along the outer periphery of the wafer 4 by the cutter 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOI substrate manufacturing method for manufacturing an SOI substrate from a bonded wafer obtained by bonding a semiconductor wafer functioning as a supporting substrate and a semiconductor wafer functioning as an active substrate. is there.

[0002]

2. Description of the Related Art In recent years, an SOI substrate has been required as a substrate for high-performance semiconductor devices because of its high withstand voltage and high speed, and an SOI substrate having a large area and few crystal defects meets the requirements of this type. It has become relatively easy to make a bonded wafer obtained by bonding two semiconductor wafers. Usually, such a bonded wafer is manufactured by the following steps (see FIG. 3). (1) The active substrate 11 is heat-treated, and an oxide film 13 is formed on the surface thereof.
After forming, the joint surface 11a with the support substrate 12 is mirror-finished, while the joint surface 12a of the support substrate 12 is also mirror-finished (FIG. 3A). (2) Bonding surface 11 with mirror finish of each substrate
After cleaning, hydrophilic treatment, and drying treatment of a and 12a, the bonding surfaces 11a and 12 of the respective bonding surfaces 11a and 12 are kept hydrophilic.
Join a together. By heat-treating this again, the active substrate 11 and the supporting substrate 12 are attached to each other, and the oxide film 13 is also formed on the supporting substrate 12 side. Thereby, the bonded wafer 14 is obtained (FIG. 3 (b)).

However, by performing the hydrophilic treatment and the drying treatment, residual hydrogen and hydrogen ions are likely to collect on the outer peripheral portion of the bonded wafer 14, which causes bubbles to form unbonded portions (voids). Become. Since the strength of the non-bonded portion is lower than that of other portions and causes chipping or particle generation in a later device process, it is necessary to remove the outer peripheral portion of the active substrate 11 including the non-bonded portion. Conventionally, as a method of removing the outer peripheral portion of the active substrate 11,
The following method is used to reduce the diameter of the bonded wafer 14. That is, as shown in FIG. 4A, after the upper surface of the active substrate 11 is surface-ground to a predetermined thickness, the bonded wafer 14 is rotated in the horizontal direction and the profile wheel 15 is rotated in the horizontal direction. This variant wheel 15
The outer peripheral portion of the bonded wafer 14 is brought into contact with the upper grinding surface 15a of the above, and is ground by a width of about 1 inch from the horizontal direction to reduce the diameter. Next, as shown in FIGS. 4B and 4C, the peripheral edge of the bonded wafer 14 having a reduced diameter is brought into contact with the lower grinding surface 15b of the deformed wheel 15, and the peripheral edge is chamfered. Finally, with the intermediate oxide film 5a left, the oxide film 13 is removed by etching with a hydrofluoric acid solution, and the upper surface of the active substrate 11 is further thinly polished to obtain an SOI substrate (not shown).

[0004]

However, in the method of grinding the outer peripheral portion of such a bonded wafer from the horizontal direction to reduce the diameter of the bonded wafer, the width to be ground is as large as about 1 inch. The horizontal grinding stress is applied to the bonded wafer for a long period of time, resulting in processing strain, which causes crystal defects (pits) such as cracks. Further, the width to be ground is as large as about 1 inch, and it takes too much time to grind from the horizontal direction, resulting in a problem of poor production efficiency. The present invention has been made in view of the above problems, and an SOI substrate that can prevent the generation of crystal defects (pits) without applying a grinding stress to a bonded wafer and has a higher production efficiency than the conventional manufacturing method. It is an object of the present invention to provide a manufacturing method of.

[0005]

Therefore, in the present invention, when a semiconductor wafer functioning as a supporting substrate and a semiconductor wafer functioning as an active substrate are bonded to each other to manufacture an SOI substrate, an outer peripheral portion of the bonded semiconductor wafers is used. In the method of removing the semiconductor wafer, the outer peripheral portion of the semiconductor wafer is cut by a cutter that rotates in a direction substantially perpendicular to the bonded semiconductor wafer.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a method for manufacturing an SOI substrate according to the present invention, FIG. 2 is a diagram showing a manufacturing process for the method for manufacturing an SOI substrate according to the present invention, and FIG. 3 is a diagram showing an example of a manufacturing process for a bonded wafer. FIG. 4 is a diagram showing a conventional method for manufacturing an SOI substrate.

The method of manufacturing the SOI substrate of this embodiment is the same as the above-mentioned conventional technique until the bonded wafer 4 is obtained. That is, as shown in FIG. 2A, the support substrate 2 is heat-treated, and after the oxide film 5 is grown on the surface of the support substrate 2, the active substrate 3 is bonded to the upper surface of the support substrate 2 through hydrophilic treatment and drying treatment. As shown in FIG. 2B, the bonded support substrate 2 and active substrate 3 are heat-bonded to each other, and an oxide film 5 is grown on the entire surface to obtain a bonded wafer 4. As shown in FIG. 2C, the upper surface of the active substrate 3 of the bonded wafer 4 is surface ground by a grinding machine.

Next, a method of removing the outer peripheral portion of this embodiment will be described. As shown in FIG. 1A, the surface-ground bonded wafer 4 is rotated in the horizontal direction. Next, the disk-shaped cutter 1 provided on the dicing machine is attached to the active substrate 3
It is rotated in a substantially vertical direction with respect to and is lowered in the direction of arrow A from above. As shown in FIG. 1B, the cutter 1
As the substrate goes down, the active substrate 3 and the supporting substrate 2 are cut substantially vertically on the same plane along the outer peripheral portion, and when the cutter 1 cuts the oxide film 5 on the bottom surface of the supporting substrate 2, the outer peripheral portion including the unbonded portion is cut. Becomes a donut shape and is separated from the bonded wafer 4, and the cutting is completed.

Further, returning to the process diagram of FIG. 2, the SOI substrate is manufactured in the next process. As shown in FIG. 2D, the donut-shaped outer peripheral portion is removed from the bonded wafer 4.
As shown in FIG. 2E, the bonded wafer 4 from which the outer peripheral portion has been removed is chamfered. Finally, the oxide film 5 remaining on the bottom surface of the bonded wafer 4 is removed by etching with a hydrofluoric acid solution, and the upper surface of the active substrate 3 is further thinly polished to obtain an SOI substrate (not shown).

Although the bonded wafer 4 is cut after the active substrate 3 is ground in the above embodiment, the invention is not limited to this, and the bonded wafer is cut before the active substrate is ground. Then, the active substrate may be subjected to surface grinding thereafter.

[0011]

Since the present invention is configured as described above,
In removing the unbonded portion on the outer peripheral portion of the bonded wafer, grinding stress is not applied to the bonded wafer, which has an excellent effect of preventing generation of crystal defects (pits). Also, cutting from the vertical direction can remove the outer peripheral portion in a shorter time than grinding from the horizontal direction,
It has an excellent effect of high production efficiency.

[Brief description of drawings]

FIG. 1 is a schematic view showing a method for manufacturing an SOI substrate according to the present invention.

FIG. 2 is a diagram showing a manufacturing process of an SOI substrate manufacturing method according to the present invention.

FIG. 3 is a diagram showing an example of a manufacturing process of a bonded wafer.

FIG. 4 is a diagram showing a method for manufacturing an SOI substrate according to the related art.

[Explanation of symbols]

 1 Cutter 2 Support Substrate 3 Active Substrate 4 Bonded Wafer 5 Oxide Film 5a Intermediate Oxide Film 11 Active Substrate 12 Support Substrate 13 Oxide Film 13a Intermediate Oxide Film 14 Bonded Wafer 15 Deformed Wheel 15a Upper Grinding Surface 15b Lower Grinding Surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eriko Hashiguchi 1112 Kihara, Kiyotake-cho, Miyazaki-gun, Miyazaki Prefecture Komatsu Electronics Co., Ltd.

Claims (3)

[Claims] 1. A method of removing an outer peripheral portion of a bonded semiconductor wafer when bonding a semiconductor wafer functioning as a supporting substrate and a semiconductor wafer functioning as an active substrate to each other to manufacture an SOI substrate. A method of manufacturing an SOI substrate, wherein an outer peripheral portion of the semiconductor wafer is cut by a cutter that rotates in a direction substantially perpendicular to the wafer. 2. The method for manufacturing an SOI substrate according to claim 1, wherein the bonded semiconductor wafer is rotated in the horizontal direction and the outer peripheral portion of the semiconductor wafer is cut. 3. The manufacturing of an SOI substrate according to claim 1, wherein a dicing machine is used, and the outer peripheral portion of the bonded semiconductor wafers is cut by a disk-shaped cutter provided in the dicing machine. Method.