JPH0466102B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an emitter of a bipolar transistor.

[Conventional technology]

Conventionally, the emitter of a bipolar transistor can be formed by diffusing impurities using a vapor phase diffusion method or by implanting impurities into silicon by ion implantation.

[Problem that the invention seeks to solve]

The two conventional methods described above have the following drawbacks.

(1) The disadvantage of forming the silicon by diffusing impurities using the vapor phase diffusion method is that the concentration of impurities diffused into silicon varies, and especially in the case of large diameter wafers, the dispersion in impurity concentration becomes significant.
This has the disadvantage that the current amplification factor of the transistor varies greatly.

(2) The disadvantage of implanting impurities into silicon using ion implantation is that impurity ions are implanted into silicon with high energy, damaging the silicon crystal and creating crystal defects. However, the recovery by heat treatment is not perfect, and leakage current remains between the emitter and base of the transistor, deteriorating the characteristics of the transistor.

It is an object of the present invention to eliminate the above-mentioned conventional drawbacks, and to provide a bipolar transistor with few crystal defects caused by ion implantation, with little leakage between the emitter and base of the transistor, and with a stable silicon-oxide film interface.

[Means for solving problems]

In the method for manufacturing a semiconductor device of the present invention, in forming an emitter of a bipolar transistor using a P-type impurity region as a base region, N
forming a first N-type impurity region by implanting type impurities by high-energy ion implantation, and forming a second N-type impurity region by performing gas diffusion into the first N-type impurity region at a low temperature and for a short time. and a step of simultaneously heat-treating the first and second N-type impurity regions by heating in a high-temperature inert gas at a gas diffusion temperature.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view for explaining one embodiment of the present invention.

As shown in FIG. 1, the method for manufacturing a semiconductor device according to the present invention includes adding a P ⁺ base region 2, which is the base of a bipolar transistor, to an N ^- epitaxial layer 1.
N-type impurities are implanted into the silicon by high-energy ion implantation to form a deep N ⁺ region 3, and then N-type impurities are implanted at low temperature (approximately 800°C).
High concentration and shallow N ⁺⁺ region 4 by diffusion for a short time
form. Next, there is a manufacturing method in which the emitter of a bipolar transistor is formed by applying high-temperature heat treatment.

FIG. 2 is a diagram showing an impurity profile in the vertical direction of the emitter of a transistor formed according to the embodiment described above.

In FIG. 2, curve A is the base impurity profile, curve B is the emitter impurity profile formed by ion implantation, and curve C is the impurity profile formed by diffusion at low temperature. In this embodiment, since the deep N ⁺ region 3 is formed by ion implantation, this region has crystal defects caused by the ion implantation. However, in this embodiment, after ion implantation, N-type impurities are diffused at a low temperature for a short time to form a shallow N ⁺⁺ region 4, and then heat treated, so that gettering and crystal defects in the shallow N ⁺⁺ region are reduced, and as a result, the transistor The leakage between the emitter and the base can be reduced.

Further, since the glass layer 6 can be formed on the surface of the oxide film 5 and the emitter region 4 by diffusion to form the shallow N ⁺⁺ region 4, there is also the effect of stabilizing the interface between the silicon and the oxide film.

〔Effect of the invention〕

As explained above, according to the present invention, in forming the emitter of a bipolar transistor, crystal defects caused by ion implantation can be reduced, leakage between the emitter and base of the transistor can be reduced, and the silicon and oxide film interface can be stabilized. This has the effect that it can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining one embodiment of the present invention, and FIG. 2 is a diagram showing an impurity profile in the vertical direction of the emitter of a transistor formed according to one embodiment of the present invention. 1...N ^- epitaxial layer, 2...P ⁺ base region, 3...deep N ⁺ region, 4...shallow N ⁺⁺ region,
5... Oxide film, 6... Glass layer.

Claims (1)

[Claims] 1 In forming the emitter of a bipolar transistor having a P-type impurity region as a base region, the P-type impurity region is
forming a first N-type impurity region by implanting N-type impurities into the type impurity region by high-energy ion implantation; and performing gas diffusion at low temperature and for a short time into the first N-type impurity region to form the first a step of forming a second N-type impurity region with a higher concentration than the N-type impurity region; and a step of simultaneously heat-treating the first and second N-type impurity regions by heating in an inert gas at a temperature higher than the gas diffusion temperature. A method for manufacturing a semiconductor device, comprising: