JPS60160119A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a desired oxide film and an excellent diffusion layer of desired depth by a method wherein the greater part of a desired oxide film is grown in a short period by performing a wet oxidation, and then a diffusion is advanced by performing a dry thermal oxidation. CONSTITUTION:After B has been deposited on an N-layer 2 from the window of an oxide film 3, a P-layer 4 of approximately 3mum in thickness is formed by performing a wet oxidation at 1,150 deg.C for 30min, and an oxide film of approximately 8,500Angstrom in thickness is covered thereon. Temperature is raised to 1,230 deg.C under the above-mentioned condition, and when the above is oxidized for approximately 10hr using dry O2, the P-layer 4 is diffused to the depth of 17mum, an oxide film of approximately 1,400Angstrom is newly grown on the film5, and this oxide film can be used satisfactorily as a diffusion mask in the process to be performed subsequently. According to this constitution, an oxide film and a diffusion layer of desired thickness can be obtained, and moreover, a heat treatment can be finished within 10hr, thereby enabling to reduce the generation of crystal defects remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to an impurity diffusion method.

As is well known, diffusion heat31 occurs in the manufacturing process of semiconductor devices.
This is done repeatedly. Diffusion is the process of introducing impurity atoms into a semiconductor to form a layer with an arbitrary conductivity type and impurity profile, but in order to actually manufacture semiconductor devices, selective diffusion flE +% is required. *Prior to diffusion, an oxide film is generated on the H-plane, and a photo-etching process is performed. Usually, the initial diffusion is removed and the oxide film formed in the latter half of the previous diffusion process is used as a mask. There is also.

On the other hand, the diffusion depth in this type of diffusion treatment is related to the heating temperature and heating time.For example, in order to achieve a deep diffusion of about 14 to 17 μm, 72 hours at 1208°C is required. shall be. When processed at such high temperatures for a long period of time, crystal defects are likely to occur not only on the surface of the wafer but also inside the wafer. 1200 more than this
When diffusing at a high temperature of ℃ or higher, the thermal diffusion method using V ryo 0 dew is generally applied, but the oxide film formation rate Jt in this case is the same as the wet thermal oxidation method (including wet O oxidation and steam oxidation). I'm busy and I'm late for A.
Therefore, the heating time required for the above-mentioned diffusion is also long.

The object of this invention is to prevent the occurrence of crystal defects by shortening the diffusion time, and to make it easier to obtain a desired diffusion depth and oxide film thickness.

When carrying out two-stage diffusion using this invention, the first stage diffuses highly concentrated impurities for a short time and generates an oxide film of the required thickness through thermal oxidation in a single wet state, and the second stage diffuses The method is characterized in that, following the first stage diffusion, a previous diffusion layer is formed in a high temperature region to a desired depth, and an oxide film is formed by dry O8 on the surface KF of the oxide film.

Since an oxide film is generated by a wet thermal oxidation method during the first stage diffusion, an oxide film with a desired thickness can be obtained in a short time. For example, heating at 900 to 1200° C. for about 80 minutes is sufficient to obtain an oxide film with a thickness of 6800 to 7800 Å. The impurity diffusion depth at this time is approximately 8μ.
It is. Also, if the impurity is highly concentrated (.Usually, the surface thickness of the diffusion layer is about 1OIs~1('1''/d),
It would be better to use Gao Nong Liao instead. A wet thermal oxidation method is used in this diffusion step.

The second stage of diffusion is for sending the previously diffused impurities into the interior. The depth of this diffusion is 14-17μ
This can be done in about 198+'1.10 hours.

Therefore, compared to the conventional method, the high temperature treatment time is much shorter. As a result, surface and internal crystal defects are sufficiently reduced.

In addition, the time required for manufacturing is also short.The second step uses a thermal oxidation method using dry 08.Therefore, an oxide film is formed even during this step.The thickness of the oxide film formed at this time is approximately The thickness is approximately 1 μm.This, together with the previous oxide film, provides the thickness necessary for the next diffusion process.Therefore, unnecessary impurities can be sufficiently prevented from entering the diffusion region during the next diffusion process.

Through the above steps, an oxide film of desired thickness and a diffusion layer of desired depth can be obtained. And IC72 than the conventional one
Since it is exposed to high temperatures for a long period of time, the occurrence of crystal defects not only on one surface but also in the interior is significantly reduced. In addition, during the second stage of diffusion, we compared the results when only N gas was flowed and when only 08 gas was flowed.

(4//m) and OB (1n OCC/m') were combined and flowed together, and in the middle of the flow only O dew gas was flowed, and the crystal defects on the 1 surface were further significantly reduced. It is confirmed that it will.

Next, embodiment 1 of this invention will be described.

The figure shows an N-type epitaxial layer formed on an N-type substrate.
The case where the conduction region of the mold is formed by diffusion is shown in FIG. Ln on the surface of the semiconductor substrate (for example, N type) 1
It is assumed that the conduction region 2 of the mold has already been formed by epitaxial V growth and is sticky, and 8 is an oxide film produced by a thermal oxidation method. A P-type conduction region is generated in this conduction region 2. In order to generate the P-type conduction region, $ill oxide is partially photoetched from the surface of the generation region as shown in Figure 1. Remove.

Next, the value determined in this invention is obtained by debodimenting impurities such as boron, and then drying at 1150℃ wet to 804℃.
+Heat. As a result, as shown in FIG. 8, a P-type conduction region 4 made of boron is formed through diffusion to a thin thickness of, for example, about 8 μm. At the same time, a new 5-level oxide film I is formed on the surface. The thickness of this film is, for example, about 6500A. Next, the temperature inside the furnace is increased to, for example, 1280℃, and about 1
Thermal oxidation was performed by drying for 0 hours. As a result, the 8th
As shown in the figure, diffusion progressed in the conduction region 4 to a depth of approximately 17 μm. At the same time, a new oxide film is generated on the surface of the oxidized $5. This film thickness is about 580 OA, so the thickness of both oxide films 5 is about 14.00 OA. An oxide film of this thickness can be used sufficiently as a mask necessary for the next diffusion step.

As detailed above, according to this invention, when performing two-stage diffusion, most of the necessary oxide film is generated in a short time by wet thermal oxidation in the first stage diffusion, and then heated by dry 08. Since oxidation is more effective than introducing impurities into the interior and promoting diffusion, it is possible to obtain an oxide film of the desired thickness and a diffusion layer of the desired depth, and it is also possible to process at high temperatures for a long time. Therefore, it is possible to significantly reduce the occurrence of crystal defects.

[Brief explanation of the drawing]

1 to 8 are cross-sectional views showing the manufacturing process according to the present invention.

Claims (1)

[Claims] 4. Highly concentrated impurities are heated for a short time by wet thermal oxidation to form an oxide film of a desired thickness. Ni:1I
IT&! A manufacturing method for semiconductor mounting, in which impurities are diffused shallowly, and then the impurities are heated for a long time by thermal oxidation using a dry O group in a high-temperature state, and the impurities are diffused to a desired depth by sending the impurities inside.