JPH06196459A - Manufacture of semiconductor silicon wafer - Google Patents

Abstract

PURPOSE:To solve the problems of a semiconductor silicon wafer, such as the deterioration of surface cleanness and surface roughness, and lowering of the dopant concentration in a surface region after the thermal treatment carried out in a hydrogen atmosphere or a hydrogen-containing atmosphere without subjecting it to a mirror polishing process again. CONSTITUTION:A semiconductor substrate is thermally treated in a hydrogen atmosphere or a hydrogen-containing atmosphere through such a method that gas, for instance, halide gas such as hydrogen chloride gas or the like capable of etching a semiconductor substrate is introduced in a thermal treatment or in another thermal treatment after the thermal treatment concerned so as to perform an etching treatment of the semiconductor substrate, whereby a required etching treatment can be carried out corresponding to the width of region lessened in dopant concentration near the surface of the semiconductor substrate, and the substrate is lessened in number of surface particles and improved in surface roughness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a semiconductor wafer such as silicon, and more particularly, under hydrogen or a hydrogen-containing atmosphere for improving the crystal quality in the vicinity of the wafer surface which is an active region of a semiconductor element. It is possible to dramatically improve the characteristics and yield of semiconductor devices by preventing the deterioration of surface cleanliness and surface roughness and the increase in the resistance of the area near the surface, which occur in the method for manufacturing a semiconductor silicon wafer that is subjected to the high temperature heat treatment. The present invention relates to a method for manufacturing a semiconductor silicon wafer.

[0002]

2. Description of the Related Art A thin thermal oxide film is used as an insulating film between a gate electrode and a substrate in a gate portion of a MOS transistor which is a basic constituent element of a MOS LSI device. In recent years, with the high integration of MOSLSI devices, the gate oxide film has become thinner, and the problem of its reliability has become apparent. The withstand voltage characteristic of the gate oxide film strongly depends on the crystal quality in the vicinity of the surface of the silicon substrate used, and greatly affects the reliability and yield of the highly integrated MOS LSI device.

As a method for solving such a problem, JP-A-60-231365 and JP-A-61-1934 are used.
No. 5, JP-A-61-193458, etc., a silicon substrate is heated in a hydrogen atmosphere or in a hydrogen-containing atmosphere at a temperature of 950 ° C. to 1200 ° C. for 5 minutes or more to perform device processing. It is known to significantly improve the dielectric strength characteristics of the formed gate oxide film.

However, the above processing has the following problems. That is, in the heat treatment step in a hydrogen atmosphere or in a hydrogen-containing atmosphere, the surface cleanliness is deteriorated (particle adhesion), the surface roughness (haze level) is deteriorated, and the resistance of the surface vicinity region is increased by the outward diffusion of the dopant. Is. More specifically, when the semiconductor silicon substrate is heated in an atmosphere containing hydrogen, the natural oxide film formed on the substrate surface is removed by the reducing action of hydrogen, the active silicon surface is exposed, and the particles of particles mixed in the furnace are exposed. Adhesion becomes strong and cannot be removed by wet cleaning after heat treatment.

Further, the surface of the active substrate is deteriorated by etching the surface of the active substrate by a slight amount of oxygen and water mixed in the furnace. Further, with the removal of the natural oxide film, the dopant doped in the substrate is diffused outward, which causes a phenomenon that the concentration near the surface of the substrate is lowered. Therefore, considering application to silicon substrate products, it is necessary to remove surface-adhered particles, improve surface roughness and remove dopant concentration lowering regions by mirror polishing again after high-temperature heat treatment under hydrogen or hydrogen-containing atmosphere. there were.

[0006]

In recent years, the degree of integration of semiconductor devices, that is, miniaturization has been remarkably increased, and accordingly, the required specifications for surface quality have become stricter. In view of these circumstances, the above-mentioned conventionally disclosed technical methods cannot provide any measures against deterioration of surface cleanliness, deterioration of surface roughness, and high resistance in the vicinity of the surface. Becomes difficult to convert.

In view of the above situation, the present invention has a problem that the surface cleanliness is deteriorated, the surface roughness is deteriorated, and the dopant concentration in the vicinity of the surface is lowered after the heat treatment in a hydrogen atmosphere or a hydrogen-containing atmosphere. An object of the present invention is to provide a method for manufacturing a semiconductor silicon substrate, which can be solved all at once without performing mirror finishing.

[0008]

According to the present invention, the surface of a silicon wafer is subjected to high temperature heat treatment in a hydrogen atmosphere, an atmosphere containing hydrogen, or an inert atmosphere, and then the surface of the wafer is etched by an etching gas. The present invention is a method for manufacturing a semiconductor silicon wafer. More specifically, after a high temperature heat treatment performed on a silicon wafer such as a CZ single crystal in a hydrogen atmosphere or an atmosphere containing hydrogen, for example, 1
A method for producing a semiconductor silicon wafer, characterized in that a halide gas is introduced in a temperature range of 000 ° C to 1300 ° C, and the wafer surface is etched with the halide gas.

According to the present invention, in order to improve the crystal quality on the surface or in the vicinity thereof, a silicon wafer is subjected to a high temperature heat treatment in a hydrogen atmosphere or an atmosphere containing hydrogen, and then the etching gas is used. A method of manufacturing a semiconductor silicon wafer, characterized in that the surface of the wafer is etched. More specifically, for the above purpose, after subjecting a silicon wafer such as a CZ single crystal to a high temperature heat treatment in a hydrogen atmosphere or an atmosphere containing hydrogen, subsequently, for example, 1100 ° C. to 1 ° C.
A method of manufacturing a semiconductor silicon wafer, characterized in that a halide gas is introduced in a temperature range of 150 ° C., and the surface of the wafer is etched by the halide gas.

In the present invention, the step of etching the surface of the wafer with an etching gas is performed by performing high-temperature heat treatment in a hydrogen atmosphere or an atmosphere containing hydrogen, and subsequently introducing an etching gas to perform the surface etching, or Etching gas in a temperature range of 1000 ° C. to 1300 ° C. under a hydrogen atmosphere, an atmosphere containing hydrogen, or an inert atmosphere during various other heat treatments after the above high-temperature heat treatment or when the heat treatment is subsequently performed. If the above can be introduced, any heat treatment can be targeted.

In the present invention, any gas can be used for etching as long as it can etch a semiconductor substrate. However, etching with a halide gas such as hydrogen chloride is performed in a hydrogen atmosphere or an atmosphere containing hydrogen. After the heat treatment of the substrate, it improves the surface cleanliness and surface roughness, has a high effect of preventing the high resistance of the surface vicinity region, and dramatically improves the characteristics and yield of semiconductor devices without mirror finishing. Is perfect for

In the present invention, the effect of the surface etching of the wafer is sufficiently obtained if the etching gas can be introduced in the temperature range of 1000 ° C to 1300 ° C. further,
Etching temperature by introducing hydrogen chloride 1000 ° C. to 105
In the range of 0 ° C., the etching effect of hydrogen chloride on the substrate exhibits anisotropy, so that the surface roughness is not significantly improved. Further, in the temperature range of 1200 ° C. or higher, the strength of the silicon substrate is significantly weakened and plastic change occurs.
Therefore, the hydrogen chloride introduction temperature is most preferably 1100 ° C to 1150 ° C.

[0013]

The present invention relates to a method of heat treating a semiconductor substrate in a hydrogen atmosphere or an atmosphere containing hydrogen, wherein a gas capable of etching the semiconductor substrate, for example, a halide such as hydrogen chloride is treated during or after the heat treatment. It is characterized in that it is introduced during the separate heat treatment to carry out the etching treatment, and the desired etching treatment can be carried out according to the width of the dopant-reduced region near the surface of the semiconductor to be heat-treated, which reduces the surface particles and reduces the surface roughness. Can be improved. This invention can perform a desired etching treatment by appropriately selecting the etching temperature and time, the gas species and its concentration according to the width of the dopant-reduced region near the surface of the heat-treated semiconductor that is measured in advance. And the surface roughness can be significantly improved.

[0014]

EXAMPLES Conventional Example A silicon substrate (boron concentration: 4 × 10 ¹⁸ atoms / cm ³ ) grown by the Czochralski method was mirror-polished, and heat-treated at 1120 ° C. for 2 hours in a 100% hydrogen atmosphere. The boron concentration in the depth direction was investigated from the surface layer of the substrate. The evaluation device was determined by a secondary ion mass spectrometer. As shown in the measurement results of FIG. 2, in the heat treatment in a hydrogen atmosphere, a region where the boron concentration was lowered was observed from the substrate surface layer to a depth of 2 μm. On the other hand, unlike the hydrogen atmosphere, the boron concentration change after the above heat treatment conditions were performed in an oxygen and nitrogen atmosphere, and no outward diffusion of boron was observed. Similar results were obtained with the phosphorus-doped silicon substrate.

Example 1 A boron-doped silicon wafer was heat-treated in a 100% hydrogen atmosphere at 1120 ° C. for 2 hours and taken over.
At a heat treatment temperature of 1120 ° C., hydrogen chloride was introduced at 1 l / min for 3 minutes at a hydrogen flow rate of 60 l / min to remove the substrate surface layer by about 2 μm, and then the outward diffusion length of the dopant was measured by a secondary ion mass spectrometer. investigated. As shown in FIG. 1, the measurement result shows that the dopant out-diffusion region generated after the heat treatment at 1120 ° C. for 2 hours in a hydrogen atmosphere is removed,
It is possible to provide a substrate having a uniform dopant concentration in the depth direction. Also, the same results as above were obtained for the phosphorus-doped silicon wafer.

Example 2 A surface roughness measurement, particles, and counting of a sample obtained by heat-treating a boron-doped semiconductor silicon substrate in a 100% hydrogen atmosphere at a heat treatment temperature of 900 ° C. to 1200 ° C. for 10 minutes were performed. Tenco is the evaluation device
r company, surfscan4500 particle counter was used. As shown in FIG. 3, the surface roughness is remarkably deteriorated in the low temperature range, and the product is unacceptable. Next, these samples are heat-treated at a temperature of 1000 ° C to 1300 ° C.
Flow rate 60 l / min, hydrogen chloride flow rate 1 l /
Heat treatment was performed for 3 minutes for 3 minutes, and surface roughness evaluation was performed in the same manner as above. As shown in the results of FIG. 4, a significant improvement in the substrate surface roughness was observed. However, since the etching action of hydrogen chloride on the substrate exhibits anisotropy in the etching temperature range of 1000 ° C. to 1050 ° C. due to the introduction of hydrogen chloride, the surface roughness is not significantly improved. Further, in the temperature range of 1200 ° C. or higher, the strength of the Si substrate is significantly weakened, causing plastic change. Therefore, the hydrogen chloride introduction temperature is preferably 1100 ° C to 1150 ° C.

Next, the total number of particles adhering to the substrate was 169 (scattering cross-section area 0.00) immediately after hydrogen annealing.
9 μm ² or more was counted. ) After introducing hydrogen chloride 19
It is possible to make it as individual as a normal product board.

Example 3 100% of a plurality of boron-doped silicon wafers
After performing heat treatment for 10 minutes at various heating temperatures between 900 and 1100 ° C. in a hydrogen atmosphere, the breakdown voltage of the oxide film was measured, and the measurement results are shown by ◯ in FIG. Following the above high-temperature hydrogen heat treatment, at a heat treatment temperature of 1100 ° C., after introducing hydrogen chloride at a hydrogen flow rate of 60 l / min for 2 l / min for 2 minutes, the oxide film breakdown voltage of each silicon wafer was measured, and the measurement results are shown. 5 shows with a triangle. Although the surface layer of the substrate was removed by etching by about 2 μm by the introduction of hydrogen chloride, as is clear from FIG. 5, the deterioration of the oxide film withstand voltage due to the etching of the present invention is not observed. It should be noted that the silicon wafer that has been subjected to the high-temperature hydrogen heat treatment at 900 ° C. has an improved oxide film withstand voltage after etching.
It is considered that this is an effect of the high temperature heat treatment at ℃.

[0019]

According to the present invention, after the high temperature heat treatment in hydrogen or a hydrogen-containing atmosphere, the semiconductor wafer surface is subsequently etched with a halide gas to reduce the dopant concentration in the vicinity of the substrate surface accompanying the high temperature hydrogen heat treatment. In order to solve problems such as area and surface cleanliness, that is, it is possible to improve crystallinity in the vicinity of the wafer surface which is a semiconductor element active area by etching under specific conditions, improve surface cleanliness and surface roughness, It is possible to prevent the resistance in the region near the surface from becoming high and to dramatically improve the characteristics and yield of the semiconductor wafer, and obtain advantages such as improved device characteristics and improved yield in the process.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the depth from the surface of a silicon wafer that has been subjected to an etching treatment according to the present invention and the dopant concentration.

FIG. 2 is a graph showing the relationship between the depth from the surface of a silicon wafer that has been subjected to conventional high-temperature hydrogen heat treatment and the dopant concentration.

FIG. 3 is a graph showing a relationship between an introduction temperature and a substrate surface roughness (haze level) immediately after a conventional high temperature hydrogen heat treatment.

FIG. 4 is a graph showing the relationship between the etching temperature and the surface roughness (haze level) of a silicon wafer that has been treated according to the present invention.

FIG. 5 is a graph showing the relationship with the oxide film breakdown voltage of a silicon wafer after the heat treatment in a hydrogen atmosphere and after the treatment according to the present invention.

Claims (2)

[Claims] 1. A method for producing a semiconductor silicon wafer, which comprises subjecting a silicon wafer to a high temperature heat treatment in a hydrogen atmosphere or an atmosphere containing hydrogen, and subsequently performing surface etching of the wafer with an etching gas. 2. The method for producing a semiconductor silicon wafer according to claim 1, wherein the etching gas is introduced in a temperature range of 1000 ° C. to 1300 ° C.