JP2001077119A - Epitaxial silicon wafer and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a process for wafer manufacturing by depositing a crystal defect-free silicon epitaxial layer on an epitaxial growth surface of a silicon substrate. SOLUTION: A silicon oxide film 2 is formed in an epitaxial growth surface 3 so that the depth decided by implantation ionic species and acceleration energy is most frequently 30 nm or more and 1.2 μm or less from an epitaxial growth surface 3 of a silicon substrate 1. Thereafter, an oxide film 2 is removed by hydrofluoric acid through ion implantation, and a crystal defect-free silicon epitaxial layer 5 is deposited by an epitaxial growth method on an epitaxial growth surface 3 wherein the oxide film 2 is removed. In the process, a crystal defect layer 6 is formed in a region of 30 nm or more and 1.2 μm or less deep from an epitaxial growth surface 3 by ion implantation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicon wafer used for a semiconductor integrated circuit and a method for manufacturing the same.

[0002]

2. Description of the Related Art Metal contamination is a factor that deteriorates the electrical characteristics of semiconductor devices. As a method for preventing the deterioration of device characteristics due to metal contamination, a method of providing a gettering site inside or on the back surface of silicon and collecting metal at the gettering site is known. The gettering method is to introduce oxygen precipitates and dislocations into the inside of a silicon wafer by heat treatment, and to getter metal contaminant elements by utilizing crystal defects (IG: Internal).
Gettering) and forming an incomplete crystalline film such as polysilicon on the back surface of the silicon wafer or introducing defects by ion implantation, sandblasting, etc. on the back surface,
Using these defects, gettering of metal contamination elements (E
G: External gettering is common.

As a gettering method applied to an epitaxial wafer, there are a method using IG and a method using iron-boron bonding by a substrate having a high boron concentration. In particular, a technique has been disclosed in which ions are implanted into an epitaxial growth surface of a silicon wafer before epitaxial growth. Japanese Patent Application Laid-Open No. H11-74276 describes a structure and a manufacturing method in which a gettering site is provided near a device by forming a dislocation or strain layer by ion implantation before epitaxial growth. Additional testing showed that this method resulted in a large number of SFs in the epi layer when epitaxial growth was simply performed on the implanted substrate.
Defects such as (Stacking Fault) and dislocations are generated, and the examples describe that the implanted ion species may be any element. However, depending on the ion species, the acceleration energy and dose must be optimized. In addition, crystal defects are transferred and generated in the epi layer, which has a serious adverse effect on device characteristics.

[0004]

With the increase in the degree of integration of devices, the heat treatment temperature in the device process has been lowered, and the diameter of silicon wafers has become larger. In a large-diameter silicon wafer, when gettering sites (oxygen precipitates) are formed inside by IG, problems such as warpage and slip occur. It is also conceivable that gettering on the back surface does not reach the gettering site because a sufficient diffusion distance of the metal element cannot be obtained due to an increase in the thickness of the wafer and the influence of the low-temperature process. Therefore, the metal element exists in the device active region near the epitaxial film, and may cause deterioration of the electrical characteristics of the device.

In view of the above problems, it is important for an epitaxial wafer to provide a gettering site on a silicon wafer substrate immediately below an epitaxial film.

In order to solve the problem, there is a technique using the above-described ion implantation. The published technology shown in the prior art utilizes implantation defects, but implanted ion species that do not contain crystal defects in the epitaxial layer,
The acceleration energy and the dose are not described in detail, and it is not clear which region to use for manufacturing.

It is an object of the present invention to provide a gettering capability of an epitaxial wafer and to provide epitaxial growth on the surface by providing a crystal defect caused by ion implantation immediately below an epitaxial layer as a gettering site near a device active region. An object of the present invention is to provide a silicon wafer that does not generate crystal defects in a layer and a method for manufacturing the same. Another object of the present invention is to provide a technique that simplifies the wafer manufacturing process and does not lower the gettering ability as compared with the conventional technique.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and have completed the present invention.

That is, the present invention has a crystal defect layer by ion implantation in a region having a depth of 30 nm or more and 1.2 μm or less from an epitaxial growth surface of a silicon substrate, and has a silicon defect free crystal defect on the epitaxial growth surface of the silicon substrate. An epitaxial silicon wafer having an epitaxial layer deposited thereon.

The present invention also provides an oxide film having a thickness of at least 10 nm and a range of 30 nm to 1.2 μm from the epitaxial growth surface of the silicon substrate, the range of which is determined by the implanted ion species and the acceleration energy. Are formed on the epitaxial growth surface of the silicon substrate, and ions whose acceleration energy is controlled so as to have the above-mentioned range are added to the epitaxial growth surface of the silicon substrate at 1E13 to 1E15 ions /.
After the implantation of a dose of cm ^2, the silicon oxide film is removed, and then a silicon epitaxial layer is deposited on an epitaxial growth surface of the silicon substrate. Here, the effect of the implanted ion is large, particularly when it is implemented by any one selected from argon ion (Ar ⁺ ), boron ion (B ⁺ ), and boron fluoride ion (BF ₂ ⁺ ). The acceleration energy is 100 to 200 KeV, the method for forming the silicon oxide film is thermal oxidation or chemical oxidation, the method for removing the silicon oxide film is hydrofluoric acid, and the method for depositing the silicon epitaxial layer is 1000. ° C or higher 12
Atmospheric pressure epitaxial growth at a temperature of 00 ° C. or lower is a method of manufacturing an epitaxial silicon wafer particularly excellent in gettering.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

In order to achieve the above-mentioned object, the following procedure is performed (see FIG. 1).

The mode value of the range distance determined by the implanted ion species and the acceleration energy is 30 nm or more and 1.2 μm or less from the epitaxial growth surface 3 (hereinafter referred to as “epi layer deposition substrate surface”) of the silicon substrate 1. Then, a silicon oxide film 2 is formed on the surface of the substrate for epilayer deposition. It is important that the oxide film has a thickness of at least 10 nm. The reason for forming the oxide film is to prevent contamination of metal contamination by ion implantation and to improve the uniformity of implantation. There is a possibility that crystal defects may enter the epitaxial layer 5 formed later due to the contamination of the metal, and the effect is not seen unless the thickness is at least 10 nm or more. The reason that the mode value of the range is set to a position deeper than 30 nm from the surface of the substrate for epilayer deposition is that if it is less than 30 nm, defects are transferred to the surface during epitaxial growth. In particular, for any ion species, when the ion implantation is performed at an acceleration energy of 100 to 200 KeV and a dose of 1E13 to 1E15 ions / cm ² , epitaxial silicon having characteristics excellent in gettering ability and surface epitaxial layer crystallinity is obtained. A wafer can be provided. If the implantation acceleration energy is too low, the rate of occurrence of crystal defects for gettering the metal is reduced, so that the gettering ability is reduced. In addition, when manufacturing with high acceleration energy, a crystal defect occurs in the epitaxial layer, so that implantation conditions are defined. Similarly, if the dose is too low, the amount of implantation defects decreases. If it is too high, crystal defects will be transferred to the epitaxial layer,
That optimal region exists. It is important that the oxide film is a dense oxide film formed in a clean environment with little metal contamination, such as a thermal oxide film or a chemical oxide film.

After the ion implantation, the oxide film is removed with hydrofluoric acid, and cleaning effective for removing metals and particles is performed.
This can also serve as substrate cleaning before epitaxial growth.

Thereafter, a silicon epitaxial layer is deposited on the surface of the epitaxial layer deposition substrate from which the oxide film has been removed by an epitaxial growth method. At 1000 to 1200 ° C. in epitaxial growth, crystal defects such as dislocations due to ionic species in the vicinity of the range do not disappear, and conversely, secondary defects occur. Here, the epitaxial growth using lamp heating by a normal pressure epitaxial growth apparatus can exert more advantageous effects.

In the epitaxial silicon wafer according to the present invention, a crystal defect layer 6 is formed in a region having a depth of 30 nm or more and 1.2 μm or less from the surface of the epitaxial layer deposition substrate by the above-described ion implantation. This "depth"
Indicates the distance from the substrate surface 3 to the center of the crystal defect layer 6. This crystal defect layer may have any thickness as long as it has its center in the above numerical range.

[0017]

EXAMPLES The present invention will be described more specifically with reference to the following examples.

A p-type (100) 8-inch silicon substrate having a resistivity of about 10 Ωcm was prepared. Various epitaxial silicon wafers were manufactured in the following procedure. The gettering was evaluated using a sample intentionally contaminated with nickel.

1) First, all the implanted ions of argon ion, boron ion, and boron fluoride ion are permeated, and a minimum oxide film thickness of 10 nm which does not affect metal.
A silicon substrate on which a thermal oxide film is formed is prepared, and acceleration energy is set to 100, 150, 180, 2 for each ion.
4 levels of 00 KeV, dose amount 1E13, 1E14,
As 4 levels of 5E14, 1E15 ions / cm ² ,
Ion was implanted into the silicon substrate under a total of 16 levels of conditions. A material not injected was also prepared as a comparative material.

2) Next, the oxide film is removed with 0.5% diluted hydrofluoric acid, and metals and particles are removed by washing with ammonia hydrogen peroxide solution, hydrochloric acid hydrogen peroxide solution, etc. Pressure epitaxial growth equipment
Silicon epitaxial growth of 5 μm was performed at a temperature of 100 to 1150 ° C.

3) Subsequently, the surface of the obtained epitaxial silicon wafer was intentionally contaminated with nickel at 5E12 atoms / cm ² by spin coating. Also in this case, a sample that was not contaminated was prepared for comparison.

4) After performing a diffusion heat treatment at 1000 ° C. for 60 minutes in a nitrogen atmosphere, a MOS capacitor having an aluminum electrode on which a gate oxide film is formed at 300 ° is manufactured.
The occurrence lifetime was obtained from Zerubst analysis by measurement.

5) Tables 1 to 3 show the measurement results of the generation lifetime of each ion-implanted sample. Occurrence lifetime is 10
A wafer having a msec or longer was evaluated as having gettering ability. The gettering ability is excellent when the acceleration energy is 100 to 200 KeV and the dose of each ion of argon, boron and boron fluoride is in the range of 1E13 to 1E15 ions / cm ² . In addition, it can be seen that the values for these wafers are almost equal to the lifetime of an epitaxial wafer that is not intentionally contaminated. Furthermore, in all of the above cases, no defects were transferred to the surface.

6) As shown in FIG. 2, boron ions are accelerated at an energy of 100 KeV and a dose is 1E14 ions / cm ^2.
5E12 is applied to an epitaxial silicon wafer obtained by growing an epitaxial layer on
The depth direction distribution of each element by SIMS of the wafer which was contaminated with atoms / cm ² and subjected to gettering treatment was shown. It can be seen that nickel is gettered near the range of boron ion implantation.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

As described above, according to the present invention, argon ions, boron ions or boron fluoride ions are implanted immediately below the epitaxial layer near the device active region by ion implantation. It is possible to provide an epitaxial silicon wafer having high gettering ability without introducing stacking faults and dislocations in the epitaxial layer by introducing crystal defects.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of an epitaxial silicon wafer of the present invention.

FIG. 2 SIMS showing gettering ability of an epitaxial silicon wafer of the present invention intentionally contaminated with nickel.
Fig. 3 is a distribution diagram of each element in the depth direction.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 silicon oxide film 3 silicon substrate epitaxial growth surface 4 silicon substrate surface layer (implantation defect recovery) 5 epitaxial layer 6 ion-implanted crystal defect layer

Claims (7)

[Claims] 1. A silicon epitaxial layer having a crystal defect layer by ion implantation in a region having a depth of not less than 30 nm and not more than 1.2 μm from an epitaxial growth surface of a silicon substrate. An epitaxial silicon wafer, comprising: 2. A silicon oxide film having a thickness of at least 10 nm and having a range of 30 nm to 1.2 μm from the epitaxial growth surface of the silicon substrate, wherein a range of the implanted ions determined by the type of the implanted ions and the acceleration energy is formed. Ions formed on the epitaxial growth surface and whose acceleration energy is controlled so as to have the above-mentioned range are applied to the epitaxial growth surface of the silicon substrate by 1E13 to 1E15io.
A method for manufacturing an epitaxial silicon wafer, comprising: after implanting a dose of ns / cm ² , removing the silicon oxide film, and then depositing a silicon epitaxial layer on an epitaxial growth surface of the silicon substrate. 3. The method according to claim 1, wherein the implanted ion species is argon ion (Ar
⁺ ), Boron ions (B ⁺ ) and boron fluoride ions (B
_{3. The} method for producing an epitaxial silicon wafer according to claim 2, wherein the method is any one selected from F ₂ ⁺ ). 4. An acceleration energy of 100 to 200 Ke
3. The method for producing an epitaxial silicon wafer according to claim 2, wherein V is V. 5. The method according to claim 2, wherein the method for forming the silicon oxide film is thermal oxidation or chemical oxidation. 6. The method for manufacturing an epitaxial silicon wafer according to claim 2, wherein the method for removing the silicon oxide film is hydrofluoric acid. 7. The method of manufacturing an epitaxial silicon wafer according to claim 2, wherein the method of depositing the silicon epitaxial layer is a normal pressure epitaxial growth method at 1000 ° C. to 1200 ° C.