JPS6240719A - Manufacture of epitaxial wafer - Google Patents

Abstract

PURPOSE:To improve the electric characteristics of an element and to suppress the generation of a defect by diffusing in advance boron before epitaxial growing. CONSTITUTION:After boron of 1X10<19>cm<-3> or more is diffused in the entire or specific portion of a P-type substrate added with boron of 0.01-0.02OMEGA.cm of specific resistance with remarkable difficulty in manufacture, it is epitaxially grown. In other words, when the boron is diffused in high density to the depth necessary to prevent a conductive type from being inverted, there is no problem in the sufficient function of an element, and there is sufficient function even by a method of diffusing only in the specific portion necessary in a circuit. A thermally diffusing method is adapted for the efficient diffusion, and the diffusion to the specific portion can be performed by the masking action of an oxide film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a crystalline silicon substrate for manufacturing a silicone semiconductor device, and in particular to prevention of latch-up.

The present invention relates to Evita kiqual wafers for the purpose of manufacturing semiconductor devices with a soft error prevention function.

[Conventional technology]

Conventionally, this type of Evita quali wafer has been manufactured using a P-type or N-type high concentration substrate (specific resistance 0.01 to 0.02Ω・cr).
It was manufactured by epitaxial growth on ll) and was put into use. If an extremely high concentration P-type wafer (specific resistance 0001Ω・cIn) is used, dislocations will occur in the shrimp layer, making it impossible to manufacture devices. Therefore, the resistance value of the crystal substrate itself should be set to 0.01Ω・α or less What we did was not practical.

[Problem that the invention seeks to solve]

It has become clear that the above-mentioned limitation on the specific resistance of the crystal substrate causes problems in certain devices. In other words, it is necessary that the conductivity type of a part of the circuit of the element does not reverse from P type to N type during operation, and furthermore, this circuit part exists penetrating from the shrimp layer to the substrate. For this purpose, the boron concentration of the substrate must be l x l Q”cII
It has become necessary to be at least L-'. Therefore, the conventional P/P epitaxial wafer has a substrate resistivity of 0.
If it is 01~002Ω/metal, the average boron concentration is 6X10
If it is "α'" 3, it cannot be used. Also 001
Although it is not technically impossible to pull crystals of Ω·a or less, the yield is low, and there are problems in terms of low price and mass supply.

[Means for solving problems]

The epitaxial wafer of the present invention is a boron-doped P-type substrate with a specific resistance of 001 to 0.020, which does not cause any difficulty in manufacturing, and boron is added to the entire surface or a specific part of the substrate. - After spreading 3 or more,
It is characterized by epitaxial growth.

In other words, if boron is diffused at a high concentration to a depth that is necessary to prevent conduction type reversal, there will be no problem in terms of device functionality, and a method in which boron is diffused only to specific parts necessary for the circuit is also functionally sufficient. This discovery led to the present invention. A thermal diffusion method is suitable for efficient diffusion, and diffusion to a specific portion can be achieved by using the masking effect of an oxide film. As a secondary effect of the present invention, it is possible to simultaneously cause oxygen outward diffusion for suppressing oxygen-induced defects in the P-type cavity concentration substrate of the Czochralski method substrate. That is, during thermal diffusion at 1200 to 1100°C, solid solution oxygen diffuses outward from the substrate, making it possible to reduce the oxygen concentration near the surface.

A region with a low oxygen concentration is less likely to generate defects during the subsequent manufacturing heat process, and can prevent element deterioration. Although the concentration and depth of boron to be diffused depend on the device configuration, it is possible to achieve a considerably high concentration, and epitaxial growth can be performed thereon without causing defects.

〔Example〕

Plane orientation (100), boron addition 0.01-0.02Ω・
For single-crystal wafers produced by the Czochlafleschi method in No. 1,
Diffusion was performed by thermal diffusion method using diborane. After the boron glass was deposited, it was annealed at 1200''C for 64 hours to diffuse boron to a depth of approximately 8 μm. After the diffusion, the oxide film was removed and a 2-3 μm thick layer was formed using dichloro7rane gas.

FIG. 1 is a cross-sectional view of a wafer according to the present invention.

In the figure, 1 indicates a P-type substrate with a specific resistance of 0.01 to 0.02 Ω・a, 2 indicates a diffusion layer in which approximately 8 μn1 of boron is diffused at 1200'O, and 3 indicates a shrimp layer grown on the substrate. . Devices were manufactured using this epitaxial wafer and a conventional epitaxial wafer, and their characteristics were compared. As intended, the epitaxial wafer according to the present invention is less likely to cause conduction type reversal, and the formation of defects at the shrimp/substrate interface is suppressed, so the hold time (charge retention time) of DRAM is shortened. , 3-4 compared to conventional shrimp wafer
This was a significant improvement.

〔Effect of the invention〕

As explained above, the present invention has a significant effect on improving the electrical characteristics of the device and suppressing the occurrence of defects by diffusing boron before shrimp growth. The present invention provides an industrially effective method in which a substrate having a resistivity within a range that is easy to manufacture is used, and a thermal diffusion method that allows easy mass processing is used.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an epitaxial wafer according to the present invention. 1... High concentration P type substrate, 2... High concentration diffusion layer, 3... Shrimp layer.

Claims (1)

[Claims] Boron is epitaxially grown on a boron-doped silicon single crystal wafer with a resistivity of 0.02 Ω・cm or less after diffusing boron to a depth of 1×10^1^9 cm^-^3 or more over the entire surface or a specific part of the wafer. A method for manufacturing an epitaxial wafer, characterized by: