JP2001210654A - Method of manufacturing semiconductor film having characteristic in withstand voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a semiconductor thin film, which can conduct inactive processing and cleaning processing, on an exposed part in the p-n junction face of the semiconductor thin film in a short time at a room temperature and has the characteristic in withstand voltage of high productivity. SOLUTION: A second conductive SiGe film is laminated on a first conductive Si substrate. The p-n junction face is exposed by etching. A laminated body in a state where the p-n junction face is exposed is irradiated with an ultraviolet ray and the cleaning processing and the inactive processing are conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used for a semiconductor device such as a bipolar transistor and a rectifier.
The present invention relates to a method for producing a semiconductor thin film having a withstand voltage based on SiGe or SiGe.

[0002]

2. Description of the Related Art A case of manufacturing a bipolar transistor having a three-layer structure of Si / SiGe / Si will be described with reference to FIG.

First, a second conductivity type SiGe film 52 (eg, p-type SiGe) serving as a base layer is formed on a first conductivity type Si substrate 51 (eg, n-type Si) as a collector, and an emitter is further formed thereon. First conductivity type Si film 53 serving as a layer
A film (for example, n-type Si) is formed (Step S1). Then
The first conductivity type Si film 53 (emitter layer) is
Dry etching using a reactive ion etching method or a milling method until the Ge film 52 (base layer) is exposed,
Exposing a base surface 54 on which an electrode is to be formed (step S
2). Further, the side surface of the stacked body is etched by a wet etching method or the like to form a mesa etched portion 55 (step S3).

Next, the laminated body is dry-oxidized by, for example, heating in an oxygen (O ₂ ) gas atmosphere to form an oxide film 56 having a thickness of about 10 nm on the surface thereof (step S).
4). In this thermal oxidation step S4, the second conductivity type Si
It is necessary to keep the electrical characteristics of the Ge film 52 from deteriorating as much as possible, but it requires heating the sample at a temperature of about 750 ° C. and an oxidation time of about 2 to 10 hours. This oxide film 56 is necessary to prevent a leakage current at the semiconductor pn junction surface and to maintain the withstand voltage characteristics of the bipolar transistor.

Further, after selectively removing the oxide film 56 at a place where an electrode is to be formed by a conventional method, metal aluminum is vapor-deposited on the entire surface and patterned to form a collector electrode 57, a base electrode 58 and an emitter. The electrodes 59 are formed (step S5). Thus, Si /
A bipolar transistor having a SiGe / Si three-layer structure is obtained.

[0006]

However, in the conventional manufacturing method, it is necessary to hold the sample in a high temperature region for a long time, and the doping profile is deteriorated by the long-time thermal oxidation treatment. Further, since the thermal oxidation process requires a long time, the productivity is low. Such a problem also applies to other semiconductor devices such as a rectifier.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to solve the problem at room temperature by exposing the pn junction between the Si substrate and the SiGe film and the exposed pn junction between the SiGe film and the Si film. It is an object of the present invention to provide a method of manufacturing a semiconductor thin film having high withstand voltage and high productivity, which can perform inactivation treatment and cleaning treatment in a short time.

[0008]

According to the present invention, there is provided a method of manufacturing a semiconductor thin film having a withstand voltage according to the present invention, comprising the steps of: laminating a second conductivity type SiGe film on a first conductivity type Si substrate; And performing a cleaning treatment and an inactivation treatment by irradiating the laminated body with the pn junction surface exposed to ultraviolet rays in an air atmosphere. .

It is most preferable that the ultraviolet ray is irradiated at room temperature, but the temperature may be slightly higher than room temperature. However, in order to prevent spontaneous oxidation caused by increasing the substrate temperature, it is desirable that the temperature at the time of ultraviolet irradiation does not exceed 100 ° C. The ultraviolet irradiation time is preferably several minutes, and most preferably 1-2 minutes. Further, the wavelength of the ultraviolet light is preferably in the range of 100 to 300 nm.

In the present invention, ozone is generated by irradiating the atmosphere with ultraviolet rays having a specific wavelength, and the generated ozone forms an oxide film on the pn junction surface and decomposes and removes impurities (eg, organic substances such as oils and fats). Is made.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1) Referring to FIG. 1, as a first embodiment of the present invention, n having a three-layer structure of Si / SiGe / Si
A case where a pn-type bipolar transistor is manufactured will be described.

First, an n-type Si substrate 1 (thickness 0.5 mm) to be a collector layer is charged into a CVD furnace, and the substrate temperature is increased to 700 to 800 ° C. to supply a process gas. On a Si substrate 1, a p of about 400 nm
Type SiGe film 2 was formed by vapor phase epitaxy. This p-type SiGe film 2 is to be a base layer. Next, the inside of the CVD furnace is evacuated, and another process gas is supplied to form an n-type Si film 3 having a thickness of about 600 nm on the p-type SiGe film 2 (step S11). This n-type Si
The film 3 is to be an emitter layer. In addition, a sputtering apparatus may be used as the film forming means in addition to the CVD apparatus.

Next, until the p-type SiGe film 2 to be a base layer is completely exposed, the n-type Si film 3 and the p-type SiG
The e film 2 is selectively etched by a reactive ion etching method to expose the base surface 4 on which an electrode is to be formed (step S12). Further, the side surfaces of the stacked body are etched by the wet etching method to form the mesa-etched portions 5 (Step S13).

The atmosphere inside the processing chamber is set to the atmosphere, and the light source 6 is turned on to irradiate the atmosphere with ultraviolet rays having a wavelength range of 100 to 300 nm. The irradiation time of the ultraviolet rays was about 1 minute. A mercury lamp was used as the ultraviolet light source 6. Ozone 7 is generated from oxygen in the atmosphere by ultraviolet irradiation (step S14).
The generated ozone 7 decomposes and removes organic impurities (such as oils and fats) on the sample surface at room temperature (around 25 ° C.), so that the sample surface is cleaned. At the same time, the exposed semiconductor surface is oxidized to form a thin oxide film 8 having a thickness of about 2 nm (step S15).

Further, after selectively removing the oxide film 8 from a portion where an electrode is to be formed, aluminum is deposited on the entire surface, and a collector electrode 9, a base electrode 10 and an emitter electrode 11 are formed by patterning. (Step S16). Thus, the illustrated npn-type bipolar transistor was obtained.

It has been confirmed that the withstand voltage between the collector and the base of the bipolar transistor manufactured as described above has a breakdown voltage substantially equal to that of a conventional oxide film. This indicates that inactivation and cleaning of the interface of the semiconductor pn are realized in a short time at room temperature.

According to this embodiment, the process for improving the withstand voltage of the bipolar transistor, which took several hours in the conventional method, can be completed in only a few minutes, and the productivity is dramatically improved. I was able to.

In the above embodiment, the case of an npn-type bipolar transistor has been described. However, the present invention is not limited to this and can be similarly applied to a case of a pnp-type bipolar transistor.

Further, in the above embodiment, the ultraviolet irradiation time at room temperature is about 1 minute, but the temperature condition may be set slightly higher than room temperature, and the ultraviolet irradiation time may be 1 minute or more and 5 minutes or less. May be lengthened within the range.

(Embodiment 2) Next, a case of manufacturing a rectifier having a two-layered structure of Si / SiGe will be described as a second embodiment of the present invention with reference to FIG.

First, an n-type Si substrate 2 to be a cathode
1 (0.5 mm thick) is loaded into a CVD furnace, and the substrate temperature is increased to 700 to 800 ° C. to supply a process gas, whereby p-type SiGe having a thickness of about 400 nm is formed on the Si substrate 21. The film 2 is formed (Step S21).

Subsequently, boron ions 23 are implanted from above the p-type SiGe film 22 by an ion implanter 23. Thereafter, an annealing process is performed at a temperature of 1000 ° C. for 1 to 3 minutes in a nitrogen atmosphere to activate the implanted ions, and a boron high concentration layer 24 is formed on the surface of the p-type SiGe film 22.
Is formed (Step S22). The side surface of the rectifier is etched by a method such as wet etching to form a mesa etching portion 25 (step S23).

The atmosphere inside the processing chamber is turned on, and the light source 26 is turned on to irradiate the atmosphere with ultraviolet rays having a wavelength range of 100 to 300 nm. The irradiation time of the ultraviolet rays was about 1 minute. Ozone 27 is generated from oxygen in the atmosphere by ultraviolet irradiation (step S24). This generated ozone 27 is at room temperature (25 ° C.
Under (before and after), organic impurities (such as fats and oils) on the sample surface are decomposed and removed, so that the sample surface is cleaned. At the same time, the exposed semiconductor surface is oxidized to form a thin oxide film 28 having a thickness of about 2 nm (step S25).

Further, after selectively removing the oxide film 28 at a place where an electrode is to be formed, aluminum is deposited on the entire surface and an anode electrode 29 and a cathode electrode 30 are formed by patterning, respectively (step). S26). Thus, the illustrated pn-type rectifier was obtained.

The withstand voltage between the anode and the cathode of the rectifier thus manufactured can maintain the same withstand voltage as in the case where the conventional oxide film is provided. This indicates that the passivation and cleaning treatment of the semiconductor pn interface is realized in a short time at room temperature.

According to this embodiment, the process for improving the withstand voltage of the rectifier, which required several hours in the conventional method, can be completed in only a few minutes, and the productivity is dramatically improved. Was completed.

In the above embodiment, Si / SiGe-
Although the case of a pn-type rectifier has been described, the present invention is not limited to this, and a Si / Si-pn-type rectifier, a Si / SiGe-
The same can be applied to an np rectifier, a Si / Si-np rectifier, and the like.

[0029]

According to the present invention, the exposed portions of the pn junction between the Si substrate and the SiGe film and the pn junction between the SiGe film and the Si film are subjected to the passivation treatment at room temperature in a short time. Since the cleaning treatment can be performed, the productivity of a semiconductor thin film having a desired withstand voltage characteristic is greatly improved.

[Brief description of the drawings]

FIG. 1 is a process flowchart and a schematic cross-sectional view showing a method for manufacturing a semiconductor thin film (Si / SiGe / Si bipolar transistor) having a withstand voltage according to a first embodiment of the present invention.

FIGS. 2A and 2B are a process flowchart and a schematic cross-sectional view illustrating a method for manufacturing a semiconductor thin film (Si / SiGe rectifier) having a withstand voltage according to a second embodiment of the present invention.

FIG. 3 is a process flowchart and a schematic cross-sectional view showing a conventional manufacturing method.

[Explanation of symbols]

 1; n-type Si substrate; 2; p-type SiGe film; 3; n-type Si film; 4; base surface; 5; mesa etching portion; 6; ultraviolet light source; Collector electrode, 10; base electrode, 11; emitter electrode. 21; n-type Si substrate; 22; p-type SiGe film; 23; boron ion; 24; high-concentration p-type SiGe layer; 25; mesa-etched portion; Anode electrode, 30; cathode electrode.

Claims (5)

[Claims] A first conductive type Si substrate on a first conductive type Si substrate;
A step of laminating a Ge film, a step of exposing a pn junction surface by etching, and a cleaning treatment and an inactivation treatment by irradiating the laminated body with the pn junction surface exposed to ultraviolet rays in an air atmosphere. A method of manufacturing a semiconductor thin film having a withstand voltage. 2. The method according to claim 1, wherein the pn junction surface is passivated or cleaned without substantially heating the substrate. 3. The method according to claim 1, wherein the passivation treatment and the cleaning treatment of the pn junction surface are performed simultaneously. 4. The method according to claim 1, wherein the ultraviolet light is irradiated at room temperature. 5. The method according to claim 1, wherein the ultraviolet irradiation time is several minutes.