JPH02140937A - Silicon substrate - Google Patents

Abstract

PURPOSE:To improve the mechanical strength of a silicon substrate and prevent the electric characteristic and the yield of a semiconductor element from decreasing by making a surface containing specific concentration of oxygen. CONSTITUTION:Decrease of the mechanical strength of the surface of a silicon substrate for intrinsic gettering can be prevented by making said surface of the silicon substrate contain 1X10<18>atoms/cm<2> or higher concentration of oxygen. Therefore, a crystal defect such as dislocation hardly occurs even under the stress along the edge of the thin film pattern of a silicon oxide film, a silicon nitride film, etc., the mechanical substance of a semiconductor device, by installing the semiconductor device on the silicon substrate. Thereby the electric characteristic of a semiconductor element does not decrease and high-quality semiconductor devices can be obtained with high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silicon substrate, and more particularly to a silicon substrate for intrinsic gettering that has the ability to getter contaminants and minute defects.

[Prior Art J Intrinsic gettering (hereinafter abbreviated as IG) is a technology for gettering contaminant impurities and minute defects that sneak into crystal defect regions inside a silicon substrate during the manufacturing process of semiconductor devices.

Conventionally, with this type of silicon substrate, the silicon substrate surface has a
At a depth of several tens of micrometers from m, there are no crystal defects due to oxygen precipitation, so the oxygen concentration is extremely low compared to the inside of the silicon substrate.
F-121-76 was unexpected (the same applies hereafter).

[Problem to be solved by the invention]

It is generally known that oxygen in a single crystal has the function of fixing dislocations and increasing the mechanical strength of a silicon substrate. However, when the oxygen concentration is lower than 1×10 18 atoms/cm 3 , its function decreases rapidly.

Since the above-described conventional silicon substrate for intrinsic gettering has a surface oxygen concentration of about 1016 to loH, the mechanical strength of the silicon substrate surface is reduced. Therefore, when a semiconductor device is provided on such a silicon substrate, there is a drawback that crystal defects such as dislocations are easily introduced due to stress at the pattern edges of the silicon oxide film, silicon nitride film, etc. that are the constituent materials of the semiconductor device. be.

This is particularly noticeable in recent high-density, highly integrated semiconductor devices.

In a semiconductor device into which these crystal defects are introduced, the electrical characteristics of the semiconductor element deteriorate, resulting in a decrease in yield and, in turn, a decrease in reliability.

[Means to solve the problem]

The silicon substrate of the present invention has a surface containing oxygen at a concentration higher than I x 10''g/d.

In contrast to the conventional silicon substrate described above, the present invention is a silicon substrate for intrinsic gettering, but the oxygen concentration on the silicon substrate surface is higher than 1 x 10'' atoms/d, and a semiconductor device is configured on the silicon substrate surface. It has sufficient mechanical strength to withstand the stress of materials different from silicon.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing the reverse current/voltage characteristics of a PN diode in an embodiment of the present invention.

That is, a crystal defect layer is formed inside the silicon substrate, a defect-free layer is formed near the surface, and a semiconductor element is formed by a normal method on a silicon substrate that uniformly contains 1.4 x 101' atoms/d of oxygen from the front surface to the back surface. A semiconductor device was completed by forming a semiconductor device, and its characteristics were measured. In FIG. 1, curve A is the characteristic curve when a conventional silicon substrate is used, and curve B is the characteristic curve of this embodiment. Note that this conventional silicon substrate has a surface oxygen concentration of 3×10″ atoms/aII.

As is clear from FIG. 1, the current for reverse bias is extremely small in this embodiment compared to a conventional semiconductor device using a silicon substrate.

When the inventor of the present application observed the crystal defects on the surface of the samples from which the measurement results of curves A and B were obtained using the selective etching method, no crystal defects were observed in the samples of the present invention, whereas conventional silicon In the sample using the substrate, 10 dislocations/d were observed at the pattern end of the field silicon oxide film for semiconductor element isolation. This is because in the silicon substrate of the present invention, the surface oxygen concentration was as high as 1.4×10'' atoms/aa, so the silicon substrate surface could sufficiently withstand the stress of the field silicon oxide film.

As described above, according to this embodiment, there are no crystal defects at the pattern ends of the field silicon oxide film, the reverse current of the PN junction is reduced, and high performance and high quality semiconductor devices can be obtained at a high yield. be able to.

FIG. 2 is a distribution diagram of the depth method when oxygen concentration in a silicon substrate is measured by SIMS (secondary ion mass spectrometry) according to another embodiment of the present invention. In order to obtain the silicon substrate of the present invention, the following treatment may be performed, for example. First, 1
．． 12 silicon substrates containing 8X10” atoms/- of oxygen
When heat treatment is performed at 00°C for 3 hours and oxygen near the silicon substrate surface is diffused outward, the oxygen concentration on the silicon substrate surface becomes 10'' atoms/d (Fig. 2(a)).
Heat treatment is performed at 0° C. for 4 hours to grow oxygen precipitation nuclei inside the silicon substrate, which has a high oxygen concentration. After this, the known LPC
A silicon nitride film is deposited on a silicon substrate to a thickness of 60 μm using the UD (low pressure vapor deposition) method, and heat treated at 1200° C. for 3 hours to cause oxygen to diffuse from the inside of the silicon substrate to the surface. (Figure 2-(b)). By performing these treatments, the silicon substrate of the present invention can be obtained.

In this example, as a method of increasing the oxygen concentration on the surface of the silicon substrate, a silicon nitride film was deposited on the surface as an oxygen diffusion-resistant mask to diffuse the oxygen inside the silicon substrate to the surface. It is okay to introduce.

〔Effect of the invention〕

As explained above, the present invention provides a silicon substrate for intrinsic gettering with 1 x 101'' atoms/a.
By using a silicon substrate having a surface with an oxygen concentration higher than a, there is an effect that the mechanical strength of the silicon substrate surface does not decrease.

Therefore, by providing a semiconductor device on the silicon substrate of the present invention, crystal defects such as dislocations are not introduced even under stress at the edge of a thin film pattern such as a silicon oxide film or a silicon nitride film, which is a mechanical substance of the semiconductor device. It is possible to provide high-quality semiconductor devices at a high yield without deteriorating the electrical characteristics of semiconductor elements.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the reverse current-voltage characteristics of a PN diode in an embodiment of the present invention, and FIGS. 2(a) and (b)
) is a distribution diagram in the depth direction of the oxygen concentration in a silicon substrate measured by SIMS in another example of the present invention. Agent Patent Attorney Uchihara Shin Kaya (α) θ, l ÷ Lノ<A as l θ (V) Dai Kayakuni (b)

Claims (1)

[Claims] The inside of the silicon substrate has a crystal defect layer caused by oxygen precipitates,
A silicon substrate whose surface is a defect-free layer, characterized by having a surface containing oxygen at a concentration higher than 1×10^1^8 atoms/cm^3.