JPS594128A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the semiconductor device whereon no change in carrier density is brought into the interior of a substrate and also the fluctuation of specific resistance can be prevented by a method wherein a heat treatment is performed on the semiconductor substrate in the inert gas atmosphere such as hydrogen gas or nitrogen gas containing hydrogen gas and the like. CONSTITUTION:After a heat treatment, as the first process, has been performed at 700 deg.C for 24hr in a nitrogen atmosphere on the silicon substrate formed by performing a CZ method, another heat treatnent as the second process is performed at 1,050 deg.C for three hours in the same nitrogen atmohphere, and then as the third process, a heat treatment is performed at 400 deg.C for ten minutes in an atmsophere containing the nitrogen gas of 5% of hydrogen gas and 95% of nitrogen gas in volume percentage. The first process above-mentioned is performed for the purpose of forming a deffective nuclear on the silicon substrate, and the second process is performed in orde to form a diffused zone by outdiffusing oxygen located on the surface of the substrate and, at the same time, to grow a defective nuclear. Through these procedures, the diffused zone is formed on the working region of the substrate after the second process has been completed, and the donor incidentally generated when the above diffused zone is formed disappears in the third process, thereby enabling to effectively prevent the fluctuations of specific resistance in the working region.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to manufacturing a semiconductor device including a step of forming a denuded zone in a semiconductor element forming region of a semiconductor substrate and forming defect nuclei therein. Concerning improvements in methods.

(2) Technical background In order to ensure good characteristics of semiconductor devices,
It is desirable that crystal defects such as dislocations and stacking faults do not exist in the substrate. Improving the degree of integration is a very important requirement for semiconductor devices, and in such highly integrated semiconductor devices, the dimensions of the operating area of the semiconductor device are extremely small, and the size of crystal defects is relatively small. This is because the crystal defects cannot be ignored and the influence of the crystal defects described above makes it difficult to form an image.

Incidentally, a silicon (Si) single crystal substrate is generally manufactured using the Czochralski method (hereinafter referred to as the CZ method), but this silicon (Si) substrate manufactured by the EZ method has , it already contains impurities such as oxygen atoms (0) that are unavoidably mixed in from the crucible during single crystal pulling, and these impurities become defect nuclei and cause problems in the subsequent semiconductor device element formation process, especially at high temperatures. During the process, crystal defects grow into crystal defects.It is difficult at the current state of technology to remove these crystal defects in the state of oxygen atoms (0), etc., but using the subsequent heat treatment process, the above oxygen atoms can be removed. It is possible to remove (0), and various efforts have been made to make the operating region a defect-free layer (denuded zone).

(3) Prior art and problems In the prior art, prior to the semiconductor element formation process, defect absorption sources are formed by forming scratches on the semiconductor substrate surface or by ion implantation, followed by heat treatment. A method has been used in which crystal defects, etc. on the substrate surface generated during the process are captured by the above-mentioned absorption source.However, this method not only involves additional steps, but also its capture effect is not necessarily perfect. Therefore, recently, oxygen atom (0)
as an impurity at a fairly high concentration (1018/ClTl
By performing high temperature heat treatment on the silicon (S t ) substrate contained in 3), impurities such as oxygen atoms (0) near the substrate surface are removed by outdiffusion, and
By forming oxygen precipitates (Sixty) or crystal defects caused by them inside the substrate, we can trap and eliminate micro defects and stacking faults that occur during the semiconductor element formation process, especially during the heat treatment process. A method in which the operating area is a denuded dead zone has been put into practical use. This method utilizes the so-called intrinsic gettering phenomenon (hereinafter referred to as the IG phenomenon), in which microscopic defects such as crystal defects that occur deep in the substrate adsorb harmful impurities and defects on the substrate surface and eliminate them. Its usefulness has been recognized.

By the way, in the method of forming the denuded dead zone, various combinations of heat treatment temperature range and heat treatment time have been reported, and there are too many combinations to list, but among them, 550 ('C) to 900 ( 'C)
It has been recognized that the low temperature heat treatment step for several to several tens of hours is the most effective for the formation of defect nuclei, and this step is included in all of the above methods.

However, the above-mentioned low-temperature heat treatment process generates new donors that act as n-type carriers inside the substrate.
It has become clear that this has the disadvantage that the carrier concentration changes, resulting in a change in the resistivity of the substrate.

(4) Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to form a denuded zone in a semiconductor element formation region of a semiconductor substrate, and to form defect nuclei therein. A semiconductor device manufacturing method including a low-temperature heat treatment step at 550 ['e) to 900 [°C], which does not cause a change in carrier concentration inside the substrate, that is, prevents a change in resistivity, is provided. It is about providing.

(5) Structure of the Invention The structure of the present invention is that after a semiconductor substrate is subjected to low-temperature heat treatment to form defect nuclei, the semiconductor substrate is treated with hydrogen (N2) gas or nitrogen (N2) gas containing N2 gas. The purpose is to perform heat treatment in an active gas atmosphere.

Silicon '(S+) single fa manufactured by Cl method
The oxygen atom (0) contained in supersaturated oxygen is 55o[
It is well known that precipitates (Sixty) having lattice defects are formed by precipitating in a low temperature heat treatment process at temperatures of 900° C. to 900° C.

The inventors of the present invention discovered that the interface between the precipitate (Sixty) thus formed and the silicon (Si) single crystal matrix has unpaired bonds (1) due to lattice defects in the precipitate (Sixty). angling Bond), and the unpaired electron involved in the cono unpaired bond acts as a donor, causing a change in the carrier concentration in the operating region. I got the idea that by reacting the like, stable covalent bonds could be generated and unpaired bonds could be eliminated.
) gas and an inert gas such as nitrogen (N2) gas, the present invention was completed by embodying the above idea.

In addition, the temperature range of the heat treatment step performed specifically to eliminate the above-mentioned unpaired bonds is 200 ("C) to 900C.
[°C] was found to be effective through repeated experiments.

(6) Embodiment of the Invention A method for manufacturing a semiconductor device according to an embodiment of the present invention will be explained, and the structure and unique effects of the present invention will be clarified.

In order to form a denuded zone in the active region of a silicon (Si) substrate formed by the Cl method, in the semiconductor device element forming process, the above-mentioned substrate is subjected to a two-step heat treatment process, and then an operation process. A heat treatment step consisting of one step is performed to eliminate the donors generated in the region. That is, as a first step, heat treatment was performed at 700 [°C] in a nitrogen atmosphere (N2) for 24 hours, and then as a second step, heat treatment was performed at 1,050 [°C] in a room floor (N2) atmosphere. Heat treatment was performed for 3 hours at
Heat treatment is performed at 400 [° C.] for 10 minutes in an atmosphere containing gas and 95 [%] nitrogen (N2) gas. Here, the first step is to form defect nuclei on the silicon (8i) substrate, and the second step is to out-diffuse oxygen on the substrate surface to form a denuded zone and grow defect nuclei. I'm going to

According to the above process, a denuded dead zone is formed in the active region of the substrate after the completion of the second step, and the donors incidentally generated at that time are annihilated in the third step, and the specific resistance of the active region is reduced. Changes are effectively prevented.

FIG. 1 shows a comparison between the amount of donors generated after completing the first and second steps and the amount of donors generated after completing the first, second and third steps. In the figure, the vertical axis is the amount of generated donors (XIO" cm-3) converted from the change in resistivity of the silicon (Si) substrate, and the horizontal axis is the amount of oxygen contained in the silicon (Sl) substrate. Concentration (, ppln
atoln). Furthermore, the broken line indicates the amount of donors generated after completing the first and second steps, and the solid line indicates the amount of donors generated after completing the first, second, and third steps.

As is clear from this figure, when the substrate is subjected to a heat treatment process that includes the third process, the amount of donors generated is extremely small, and is particularly high compared to when heat treatment is performed that does not include the third process. It was confirmed that there is a very significant donor extinction effect, that is, an effect of preventing donor generation, depending on the oxygen concentration.

(7) As described in detail, according to the present invention, the 550 ['
C) To provide a method for manufacturing a semiconductor device that does not cause a change in carrier concentration inside the substrate, that is, prevents a change in resistivity, in a method for manufacturing a semiconductor device including a low temperature heat treatment step at ~900['C]. be able to.

[Brief explanation of drawings]

Figure 1 shows the first step performed at 700 [℃], 1.
050[:'The second step using Cl, and 400[:'
The amount of donors (solid line) generated accompanying the method of manufacturing a semiconductor device according to an embodiment of the present invention, which consists of the third step performed with 700 ("C), and the first step performed with 700 ("Cl), .050 ('C) and the amount of donors (dashed line) generated in the conventional semiconductor device manufacturing method consisting of the second step, and the oxygen concentration contained in the silicon (Si) single crystal as an independent variable. This is a graph comparing the following.Representative Patent Attorney Hiroshi Matsuoka

Claims (1)

[Claims] Manufacture of a semiconductor device, comprising a step of subjecting a semiconductor substrate to low-temperature heat treatment to form defect nuclei, and then heat-treating the semiconductor substrate in an atmosphere of hydrogen gas or an inert gas containing hydrogen gas. Method.