JPH02220444A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture a heterojunction transistor by a method wherein, after a bipolar transistor has been formed by an ordinary process, silicon ions are implanted into an emitter part. CONSTITUTION:SiO2 is formed on a silicon substrate 101; after that, a window for base use is opened; a mask 102 for ion implantation use is formed; boron ions are implanted; a base layer 103 is formed. Then, an SiO2 film 106 is formed again; after that, a window for emitter use is formed; a polycrystalline silicon film is formed; after that, an emitter 104 is formed. After that, a mask 105, for ion implantation use, in which a window has been opened in a part of the emitter is formed; silicon ions are implanted; the emitter of polycrystalline silicon is made amorphous; a wide-gap emitter is formed. Thereby, it is possible to form a heterojunction bipolar transistor whose amplification factor is high and whose high-frequency characteristics are good only by adding an ion- implantation process to an existing bipolar transistor process.

Description

[Detailed description of the invention] [Industrial use 11F] The present invention relates to a method for manufacturing a semiconductor device.

[Prior Art] As a method for forming a wide gap emitter of a heterojunction bipolar transistor, an MBIC device has conventionally been mainly used when a gallium arsenide thread semiconductor is used. However, this method has a very slow film formation rate;
Furthermore, the use of gallium arsenide results in high costs and poor manufacturing technology, resulting in low industrial productivity.

Therefore, there is active research into manufacturing heterojunction bipolar transistors using silicon, which is currently the most advanced in manufacturing technology. In this case, as a method for forming wide gap emitters, the plasma OVD method is often used due to its excellent mass production.The materials for wide gap emitters include amorphous (or microcrystalline) silicon, silicon and carbon or oxygen. compounds are used.

[Problems to be solved by the invention] Of these, it is relatively easy to change the composition of silicon-based compounds to give them a gradient structure in the band gap, but it is not very easy to make them have a gradient structure in the band gap due to their low electrical conductivity. Not desirable.

On the other hand, when amorphous (or microcrystalline) silicon is used as a wide-gap emitter, if the bandgap has a sloped structure during film formation, it is possible to change the substrate temperature, gas flow rate, etc. This causes problems such as changes in the amount of impurities such as boron and other impurities, making it difficult to control.

[Means for Solving the Problems] According to the present invention, a semiconductor device manufacturing method is characterized in that, in a heterojunction transistor having a wide gap emitter, the method includes a step of making the emitter amorphous by ion implantation.

[Example] The present invention will be explained below according to the examples.

FIG. 1 shows an example in which the present invention was used to fabricate a silicon HBT in which the emitter paste junction was a sloped junction.

810. After forming, a window for the paste is opened in a photo-etching process and a mask 102 for ion implantation is formed.
A base layer 103 is formed by implanting boron ions. (Fig. 1 (α)) Next, after forming the S10° film 106 again using the sputtering method, a window for the emitter is formed using the photoetching process, and a rectangular multilayer film 106 is formed using the reduced pressure 0/D method. After forming a film of crystalline silicon, an emitter 104 is formed again by a photo-etching process.

(FIG. 1(b)) Through the steps up to this point, a normal npn type (homojunction) bipolar transistor is formed. Here, an ion implantation mask 105 with a window in the emitter portion is formed using photoresist, and silicon ions are implanted to make the polycrystalline silicon emitter amorphous. (1st
Figure (C)) The band gap of polycrystalline silicon is 1.0
~1.3θV, which is almost equal to single crystal silicon (,1.12eV).

However, by becoming amorphous, the band gap becomes 1
．． 2-2. It can expand to OeV and form a wide gap emitter. (FIG. 2) By using the present invention, a heterojunction transistor can be manufactured by simply adding a step of implanting silicon ions into the emitter portion after forming a bipolar transistor in a normal process. Furthermore, the bandgap structure can be changed by changing the implantation amount and implantation speed of silicon ions. (Any bandgap distribution can be obtained by changing it over time.) Also,
When amorphous silicon is formed on this crystalline silicon, the interface unit at the bonding surface becomes a problem, but in this example, the bonding surface is polycrystalline and single crystal, so good bonding characteristics can be obtained. .

(An even better bonding interface is achieved by terminating the dangling bonds of silicon near the bonding portion with hydrogen, fluorine, etc.) Here, S10. I am using 81Nx
or an organic film, etc., and in addition to thermal oxidation and sputtering, a low pressure OVD method or the like may also be used.
As a method for forming polycrystalline silicon, a plasma QVD method, an atmospheric pressure OVD method, a sputtering method, or the like may be used. Further, a thermal diffusion method or the like may be used to form the base layer, and arsenic or the like may be used as an impurity.

A currently well-used emitter formation method is the washed emitter method, which creates a thin base layer by thermally diffusing impurities from polycrystalline silicon (104 in Figure 1) into the space region; The present invention is effective and can provide a better bonding interface.

In addition, by using this method, a faster HBT-0M09 circuit can be fabricated without changing the manufacturing process of the B10MO8 circuit (just adding a silicon ion implantation process to the emitter 501). Can be done. (
(Figure 3) Although the case of a silicon npn type bibor 2 transistor has been described above, the present invention can be similarly applied to other elemental semiconductors such as germanium and selenium, and compound semiconductors such as sea. Of course, a pnp type may also be used. Moreover, it can be applied not only to a case on a semiconductor substrate but also to a bipolar transistor formed on an insulating substrate or an insulating layer, and of course can also be used as a component of a three-dimensional process.

[Effects of the Invention] As described above, by using the semiconductor device manufacturing method of the present invention, a high amplification factor can be achieved in the current bipolar transistor process by simply adding a step of implanting ions into the emitter section after the transistor is completed. A heterojunction bipolar transistor with good high frequency characteristics (high speed) can be formed.

[Brief explanation of the drawing]

FIGS. 1(α), (b), and (C) are process cross-sectional views of an embodiment in which an npn-type heterojunction bipolar transistor was manufactured using the present invention. FIG. 2 is a diagram of the band diagram and ion implantation amount of the npn type heterojunction bipolar transistor shown in FIG. 1. FIG. 5 is a sectional view of an embodiment of an 810M0!9 circuit manufactured using the present invention. 101... Collector 105... Pace ↓ [↓ (a) (b) Figure 4... Emitter

Claims (1)

[Claims] A method for manufacturing a semiconductor device, comprising a step of making the emitter amorphous by ion implantation in a heterojunction transistor having a wide gap emitter.