JPH0722428A - Manufacture of silicon wafer, and silicon wafer - Google Patents

Abstract

PURPOSE:To provide a silicon wafer manufacturing method capable of performing control so as to cause silicon wafers containing polysilicon to have an optimum gettering effect or a larger gettering quantity, or to cause the silicon wafer containing polysilicon to have a larger gettering quantity. CONSTITUTION:(1) This invention concerns a manufacturing method for silicon wafers containing polysilicon, and has constitution for controlling the film quality of the polysilicon represented by a crystal orientating property. (2) The title silicon wafer is one containing polysilicon, and has constitution that makes the orientation ratio (220)/((111) +(220)) of the crystal orientating property of the polysilicon 0.9 or larger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer manufacturing method and a silicon wafer. INDUSTRIAL APPLICABILITY The present invention can be used as a silicon wafer used for manufacturing a semiconductor device and a method for manufacturing a silicon wafer.

[0002]

2. Description of the Related Art For a Si wafer used in a semiconductor process in which a semiconductor device such as an IC is formed on a Si wafer, a PolySi film is used for gettering.
The one added to the back surface of the i-wafer is known.

In the semiconductor process, the presence of impurities such as heavy metals on the Si wafer causes inconvenience. For example, S
It diffuses from the surface of the i-wafer and causes a junction leak defect. Therefore, various gettering functions are added to the Si wafer serving as the substrate.

The PolySi film added to the Si wafer has such a gettering effect.
It has a gettering effect of drawing the heavy metal on the i-wafer surface into the bulk during thermal diffusion. Such a wafer is
It is called an EG (enhanced gettering or extrinsic gettering) wafer. The gettering action of this type of wafer is said to be due to the fact that heavy metals are trapped in defects at the interface between the PolySi film and Si. There are still many unclear points about the mechanism. A PolySi film may be added for other purposes such as warpage prevention, and in that case, the PolySi film may also provide a gettering effect.

[0005]

With respect to the Si wafer having the above gettering effect, further improvement in the gettering amount is desired. However, in order to control the optimum gettering amount, in other words, in order to increase the gettering amount, it is usually necessary to add the Pol added to the Si wafer.
The structure of the ySi film has not been known so far, and no particular research and development has been done on this point. Basically, no research has been done to pay attention to the performance of the PolySi film added to the Si wafer and perform some control.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to control a silicon wafer to which polysilicon is added so as to obtain an optimum gettering effect or to improve the gettering amount. It is an object to provide a method for manufacturing a silicon wafer.

It is another object of the present invention to provide a silicon wafer to which polysilicon is added and which has an improved gettering amount.

[0008]

The invention according to claim 1 of the present application is a method of manufacturing a silicon wafer to which polysilicon is added, wherein the film quality of the polysilicon is controlled. Therefore, the above object is achieved thereby.

The invention of claim 2 of the present application is a method of manufacturing a silicon wafer to which polysilicon is added, which is a method of manufacturing a silicon wafer configured to control the crystal orientation of the polysilicon. The above object has been achieved by.

The invention of claim 3 of the present application is a silicon wafer to which polysilicon is added, and the crystal orientation of the polysilicon is defined by an orientation ratio of (220) / {(111) + (2
20)} is 0.9 or more, which achieves the above object.

In the invention of the present application, it is not possible to prevent the formation of various films and the like on the silicon wafer in addition to polysilicon (also appropriately referred to as PolySi). For example, the back surface polysilicon may be additionally formed with a SiN film or the like.

In the invention of claim 1 of the present application, the term "polysilicon film quality" refers to characteristics such as crystal grain size and crystal orientation which are controllable and correlated with the gettering effect.

In the inventions of claims 2 and 3 of the present application, P
The orientation of oliSi refers to the orientation obtained by the X-ray diffraction method, and is 220 planes / (220 planes +) measured by the X-ray diffraction method.
The orientation ratio is defined as the intensity ratio of the (110 plane).

The present invention has been completed based on the following knowledge found by the present inventors.

As shown in FIG. 2, the inventors of the present invention have shown that the orientation ratios are 0.95, 0.9, 0.6 and 0.4, respectively.
An Si wafer having Si on the back surface and an Si wafer without PolySi were prepared. Samples A to E respectively.
These samples A to E were evaluated for gettering amount due to intentional contamination.

In FIG. 1, the initial surface contamination concentration (refer to the horizontal axis) is 1 × 10 ¹¹ to 1 × 10 ¹⁴ atoms / cm ² by Fe.
The results of measuring the surface contamination concentration (see vertical axis) after heat treatment of the sample intentionally contaminated are shown below. A thermal simulation for this test is shown in FIG. That is, as shown in FIG.
Samples A to E that were intentionally contaminated were heated in a nitrogen atmosphere (compounding a small amount of oxygen to prevent nitriding) at 950 ° C. for 1 hour, and further heated at 1100 ° C. for 1 hour, then The temperature was lowered and the surface contamination concentration was measured to examine how much contamination was reduced by the gettering effect of PolySi. The data of each of the samples A to E are shown as I to V, respectively. 1 × 10 ¹² atoms / indicated by a broken line in FIG.
The cm ² contamination is the highest initial contamination in a normal process, and generally no more contamination is found on a normal Si wafer unless there is a special accident.

It can be seen from FIG. 1 that the gettering effect differs depending on the crystal orientation of PolySi. Further, it can be seen that the gettering effect is large when the orientation rate is 0.9 or more. This result was obtained with a similar tendency for Ni, Cr, etc. other than Fe.

[0018]

According to the invention of claim 1 of the present application, when a silicon wafer to which polysilicon is added is manufactured, attention is paid to the property of the polysilicon and the film quality of the polysilicon is controlled to obtain the optimum getter. The ring effect can be obtained, and the gettering effect can be improved.

According to the invention of claim 2 of the present application, when a silicon wafer to which polysilicon is added is manufactured, attention is paid to the property of the polysilicon, and the crystal orientation of the polysilicon is controlled, so that it is optimal. The gettering effect can be obtained, and the gettering effect can be improved.

According to the invention of claim 3 of the present application, the crystal orientation of the polysilicon of the silicon wafer to which polysilicon is added is determined by the orientation ratio (220) / {(111) + (22).
0)} is 0.9 or more, a silicon wafer with an improved gettering effect was obtained.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. However, it should be understood that the present invention is not limited to the embodiments.

Example 1 In this example, the present invention is applied to a Si wafer for manufacturing a semiconductor device, particularly a 6-inch wafer having a large diameter.

In this embodiment, 5 shown in FIG. 2 described above is used.
Types of samples AE were used.

Samples A to D were prepared by controlling the SiH ₄ gas flow rate and temperature in the PolySi film formation. The PolySi film thicknesses were all set to 1.0 to 1.5 μm by adjusting the film formation time.

A test was conducted by the thermal simulation shown in FIG. This simulation referred to the thermal history temperature condition in the actual process. As a result, in FIG.
The results shown in are obtained. Sample A with an orientation rate of 0.9 or more,
It can be seen that B has a small degree of contamination and is effective.

Samples A and B were able to realize a yield improvement of 15% in the defect inspection for leak current, as compared with those having an orientation ratio of 0.4 or less (Samples D and E). Moreover, as compared with the sample having an orientation rate of 0.6 (Sample C),
% Improvement was realized.

As described above, according to this example, the gettering effect was controlled, and the Si wafer having the improved gettering effect was obtained. Particularly, in this embodiment, the orientation ratio of PolySi is (220) / {(220) + (111)} =
By controlling to 0.9 or more, the gettering effect could be improved.

[0028]

As described above, according to the present invention, a silicon wafer to which polysilicon is added can be controlled to obtain the optimum gettering effect or to improve the gettering amount. A manufacturing method can be provided. Further, it is possible to provide a silicon wafer to which polysilicon is added and which has an improved gettering amount.

[Brief description of drawings]

FIG. 1 shows Example 1 and is a graph showing test results of gettering effect.

2 is a diagram showing a thermal simulation in the test of FIG.

FIG. 3 is a diagram illustrating a Si wafer sample used in a test of Example 1.

[Explanation of symbols]

The gettering effect is shown by a graph showing the relationship between the initial surface contamination concentration and the back surface contamination concentration after heat treatment for each of the I to V samples.

Claims (3)

[Claims] 1. A method of manufacturing a silicon wafer to which polysilicon is added, wherein the quality of the polysilicon film is controlled. 2. A method of manufacturing a silicon wafer to which polysilicon is added, wherein the crystal orientation of the polysilicon is controlled. 3. A silicon wafer to which polysilicon is added, wherein the crystal orientation of the polysilicon is the orientation ratio (220) /
A silicon wafer configured such that {(111) + (220)} is 0.9 or more.