JP2535645B2 - Semiconductor substrate manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a method for manufacturing an SOI substrate, which aims to provide an SOI substrate with a small warp or an SOI substrate with a controlled warp amount. The semiconductor substrate is annealed after ion implantation for forming an insulating film at a high acceleration so as to leave a crystal layer on the surface, and then an insulating film buried inside is formed. A semiconductor substrate is manufactured by a method for manufacturing an SOI substrate, which uses a supporting substrate as an element substrate on the insulating film.

[Industrial applications]

The present invention relates to a semiconductor substrate manufacturing method, and more particularly to a SOI substrate manufacturing method.

A semiconductor device using an SOI substrate can be completely separated by using trench element separation and the like together, and has various advantages such as improved radiation resistance, elimination of latch-up phenomenon, and achievement of higher speed. However, the drawback is that SOI
Since the substrate has a thick insulating layer, such as an SiO ₂ insulating layer, S
The i-layer was warped due to mechanical stress. The warp of the wafer not only hinders the drawing of a fine pattern, but also causes crystal defects due to stress, and segregates unnecessary impurities in a portion where stress is concentrated, thereby deteriorating device characteristics. Therefore, SOI with small warpage
Development of a substrate manufacturing method is desired.

[Conventional technology]

FIGS. 1 (a) to 1 (c) are views for explaining conventional problems in a bonded SOI substrate, where 1 is a first semiconductor substrate, 1a and 1b are insulating films, and 2 is a second semiconductor. Substrate, 3 represents a semiconductor layer of reduced thickness.

The first semiconductor substrate 1 and the second semiconductor substrate 2 on which the insulating films 1a and 1b are formed do not warp before being bonded, but after the bonding, the surface of the first semiconductor substrate 1 is shaped and polished. When the insulating layer 1a is removed to form the semiconductor layer 3 with a reduced thickness, the semiconductor layer 3 with a reduced thickness has a warp such that it becomes a convex surface. The final warp of the wafer is determined by the process of forming the element, and therefore the initial warp of the wafer is not merely required to be small, but it must be determined according to the process. In the case of the SOI substrate, the warpage cannot be controlled freely because the warpage is regulated by the insulating film.

On the other hand, in the case of a Si substrate alone, it has been possible to freely control warpage in the slicing process and grinding process.

[Problems to be Solved by the Invention]

An object of the present invention is to provide a method for manufacturing an SOI substrate having a small warp or a method for manufacturing an SOI substrate in which the amount of warp can be freely controlled by investigating the cause of warpage in a conventional bonded SOI substrate.

[Means for solving the problem]

The above-mentioned problem is to perform annealing after performing ion implantation for forming an insulating film on the warped semiconductor substrate 4 from the concave surface at such a high acceleration as to leave a crystal layer on the surface, and then performing annealing on the buried insulating film 6. And forming a support substrate 8 under the insulating film 6,
This is solved by a method of manufacturing a semiconductor substrate, which obtains an SOI substrate having the element substrate 7 on the insulating film 6.

[Action]

The semiconductor substrate 4 having a warp is annealed after ion implantation for forming an insulating film from the concave surface at such a high acceleration as to leave a crystal layer on the surface, and then annealing is performed.
When the film is formed, the difference in the coefficient of thermal expansion between the insulating film 6 and the semiconductor substrate 4 acts in the direction in which the curvature of the concave surface is relaxed to make it convex, so that it is possible to reduce the warp or adjust the warp amount. Become. Since the portion of the element substrate 7 is overwhelmingly thinner than the portion of the support substrate 8, the contribution to the warp of the element substrate can be ignored.

〔Example〕

 FIG. 2 shows an embodiment of the present invention.

The semiconductor substrate 4 has a thickness of 500 to 600 μm, and the amount of warpage on the surface is about 80.
It is a 6 inch Si wafer with a concave surface of μm.

From the concave surface, acceleration voltage 200 keV, dose 2 × 10 ¹⁸ cm
Oxygen (O ⁺ ) is ion-implanted under the condition of ^-2 . 0.1 to the surface
An oxygen ion implantation region 5 having a high oxygen ion concentration and having a thickness of 0.5 to 1 μm is formed inside, leaving a crystal layer of about 0.5 μm. (See FIG. 2 (a)).

High temperature annealing is performed at 1250 ° C. for 30 minutes to form the buried insulating film 6.

In this way, under the buried insulating film 6, the supporting substrate 8,
A substantially flat SOI substrate having the element substrate 7 on the top was obtained. (See FIG. 2B) As ions for forming the insulating film 6, in addition to O ⁺ , N ⁺ , O ₂ ⁺ , N ₂ ⁺ , O ²⁺ , N ²⁺ , O ₂ ²⁺ , N ₂ ^2+, etc. can also be used.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain an SOI substrate with a small warp or a controlled warp amount. By using the SOI substrate of the present invention, stable operation of the device can be ensured and reliability can be improved.

The present invention contributes to the miniaturization of the device and the improvement of the yield, and has a large number of rollers.

[Brief description of drawings]

1 (a) to 1 (c) are sectional views for explaining the embodiment I, FIGS. 1 (a) to 1 (c) are views for explaining conventional problems, and FIG. 2 (a). And (b) are sectional views for explaining the embodiment. In the figure, 1 is a first semiconductor substrate, 2 is a second semiconductor substrate, 1a and 1b are insulating films and oxide films, 3 is a semiconductor layer with reduced thickness, 4 is a semiconductor substrate, and 5 is oxygen ion. An implantation region, 6 is a buried insulating film, 7 is an element substrate, and 8 is a supporting substrate.

Claims (2)

(57) [Claims] 1. A semiconductor substrate (4) having a warp is annealed after ion implantation for forming an insulating film from the concave surface at such a high acceleration as to leave a crystal layer on the surface, followed by annealing. A semiconductor substrate obtained by forming a film (6) to obtain a SOI substrate having a support substrate (8) below the insulating film (6) and an element substrate (7) above the insulating film (6). Manufacturing method. 2. Use of O ⁺ , N ⁺ , O ₂ ⁺ , N ₂ ⁺ , O ²⁺ , N ²⁺ , O ₂ ²⁺ , N ₂ ²⁺ as ions for forming an insulating film. The method of manufacturing a semiconductor substrate according to claim 1, wherein the semiconductor substrate is manufactured.