JPS60198832A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a substrate for IC having high reliability by a method wherein an Si wafer having an intrinsic gettering effect, and moreover made concentration of O2 within depth of 10mum from the surface of the Si substrate to 5X10<17>/cm<3> or less, and the surface region thereof is made to no defect layer substantially is used. CONSTITUTION:Heat treatments of a high temperature and a low temperature are performed to an Si wafer having concentration of O2 of 12-18X10<17>/cm<3> normally, and concentration of O2 of the layer within depth of 10mum from the surface 1, which is the active region of a transistor, is made to 5X10<17>/cm<3> or less. An actually no defect layer is formed in such a way, the defect of the element activating region 2 thereof is reduced to 10<3>-10<6>/cm<3>, and an intrinsic gettering effect is generated. Moreover lattice defects 4 of a large number are left as they are like the beginning in a region under the region 2. When a substrate obtained in such a way is used, a transistor having no characteristic inferiority and no characteristic variation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves reliability by minimizing defects in characteristics and fluctuations in characteristics by preventing the generation of microscopic defects and oxygen donors in active regions of semiconductor devices, especially transistors, etc. The present invention relates to a high yield semiconductor integrated circuit device.

In recent years, semiconductor integrated circuit devices have become increasingly interconnected and ultra-fine, and stable circuits and manufacturing processes are required for insulation in order to realize high-precision semiconductor integrated circuit devices. Therefore, silicon wafers are designed to prevent characteristic defects caused by lattice defects such as dislocations and precipitates due to supersaturated oxygen in the active region of transistors, and also to prevent the generation of oxygen donors that cause input leakage defects and deterioration of the operating margin. It has become essential to use.

Until now, measures to improve the yield υ and reliability of semiconductor integrated circuit devices have mainly focused on scratches and dust on the surface of silicon wafers, and various solutions have been found, but lattice defects caused by the silicon wafer itself Characteristic defects caused by oxygen donors and oxygen donors have not been sufficiently evaluated.

In this avian LSI, there are not only characteristic defects that occur due to troubles during manufacturing, but also characteristic defects caused by lattice defects and oxygen donors caused by atoms or ions such as oxygen and carbon contained in the active region of the transistor. is a bigger problem.

For example, if lattice defects or oxygen donors occur in the wall-poor layer, which is the active region of a transistor, due to precipitates or dislocations that occur frequently due to carbon or supersaturated oxygen contained in silicon, these may be the source of leakage. This may cause the circuit function to malfunction.

It is also known that in the case of a silicon substrate, the depletion layer width Xd is expressed by the following equation.

CT = bottom surface εr = relative dielectric constant (11,7) ε〇−dielectric E$<8.854X10” (Fsm−”)
') φB - built-in voltage <0.7V> q = electron charge (1,6X 10"(C1> kite = concentration of acceptor atoms <13Ω - my substrate = 10.2 o"(m-")>
50 ohm substrate, 2.5 x 10''(m)> The above problem occurred because no measures were taken to eliminate oxygen in the active region of the transistor.

Figure 1 shows that the oxygen concentration of a conventional substrate without a diffusion process is 12
2 is a cross-sectional view of a silicon wafer of ~18×10" α-. FIG. 2 is a cross-sectional view after being subjected to the same heat treatment as when manufacturing a semiconductor integrated circuit device using the silicon wafer of FIG. 1.

In FIG. 1, 1 is the surface of the silicon wafer, 2 is the active region of the transistor, and 3 is oxygen contained within the silicon wafer.

Using a silicon wafer like this,
The cross-sectional view of a semiconductor integrated circuit device manufactured through a heat treatment process at ℃ is as shown in Figure 2. In the active region of a transistor, lattice defects such as precipitates and dislocations frequently occur due to carbon and oxygen. Since oxygen donors 4 (indicated by

The purpose of the present invention has been made to address the above problems, and the purpose is to eliminate lattice defects caused by supersaturated oxygen precipitates and dislocations by removing as much oxygen as possible from the active region of a transistor. It is an object of the present invention to provide a highly reliable, high-yield semiconductor integrated circuit device by preventing the occurrence of oxygen donors and eliminating characteristic defects due to this cause, as well as preventing the generation of oxygen donors that cause characteristic fluctuations.

The gist of the present invention is that the I-G effect (IJ thick gettering = getter linking effect of harmful impurities possessed by defects inside a silicon wafer) is caused by oxygen within υ10 μm from the surface, which is the active region of the transistor. a degree 5
A semiconductor device using a silicon wafer having a V of 10" cm or less and making this slope a defect-free layer in history.

10μ from the surface which is the active region of the above transistor.
oxygen within 5 x 10"cm, the concentration is below 5 x 10"cm,
To create a silicon wafer in which this region is a defect-free layer, the substrate oxygen concentration is 12~18X1017cTrL, the carbon concentration is Q, and the carbon concentration is normalized to 4 ppm or less, and the temperature is heated to 1000°C with an inert gas to eliminate the oxygen near the surface. Heat treatment is performed at a high temperature of 16 hours (if the temperature exceeds 10008C, the treatment time may be shortened), and then, in order to create the A method is used in which heat treatment is performed at 8 degrees Celsius for about 10 hours.

Embodiments of the present invention will be described in detail below with reference to FIGS. 3, 4, and 5.

FIG. 3 shows a cross-sectional view of a silicon wafer according to an embodiment of the present invention, and FIG. 4 shows a semiconductor device using the silicon wafer of FIG. A cross-sectional view after the same heat treatment as when manufacturing the #4 integrated circuit device is shown.

In FIGS. 3 and 4, the same parts as in FIGS. 1 and 2 are designated by the same numbers and will therefore be omitted. FIG. 5 shows a correlation diagram between surface oxygen concentration and surface defect density.

The present invention differs from conventional semiconductor integrated circuit devices in that the conventional substrate oxygen concentration is 12 to 18 x 10I? ctri-
``A silicon wafer is subjected to high-temperature and bottom-temperature heat treatment to reduce the oxygen concentration within 10 μm from the surface, which is the activation region of the transistor, to less than 1゛ in a 5 x 10' hole, creating a virtually defect-free layer there. Inside the υ wafer, there are defects 'k10'
~10" am and has an I-G effect is used in the manufacture of semiconductor integrated circuit devices.

This is because the active region 2 of the transistor in FIG. 3, for example, is made defect-free r@, so that the semiconductor assembly M[i, ! Even after manufacturing IW&S, no oxygen-based lattice defects or P element donors are generated in the active region fr\v,2 of the transistor.

This is because, as shown in Fig. 5, the surface defects decrease as the ~element concentration on the surface decreases, and the surface oxygen level decreases to 5 x 1 (1"cML).
This can be understood from the fact that the number of defects is O~1/20 iK.

Furthermore, inside the silicon wafer, there are 103 to 10' defects.
Since the transistor is made of c+n, this defect counteracts the gettering effect of harmful impurities, so that the transistor has extremely stable characteristics.

According to the inverse υ invention described above, since the area within 910 μm from the surface of silicon, which is the active region of the transistor, is virtually defect-free, this area has oxygen-based lattice defects and oxygen 1. No donor is generated and internal defects are created. Since it has a G effect, harmful impurities are gettered and characteristic defects and characteristic fluctuations are eliminated, resulting in high yield and high 4i! A ready-to-use semiconductor integrated circuit device can be easily obtained.

[Brief explanation of the drawing]

Figure 1 shows that the oxygen concentration of a conventional substrate that has not undergone a diffusion process is 1-2.
~18X10? Cross-sectional view of α silicon wafer, 2nd
The figure is a cross-sectional view after applying the same heat treatment as when manufacturing a semiconductor integrated circuit device using the silicon wafer shown in FIG. 1, FIG. 3 is a cross-sectional view of a silicon wafer according to an embodiment of the present invention, and FIG. is a cross-sectional view after the silicon wafer shown in FIG. 3 has been subjected to the same heat treatment as when manufacturing a semiconductor integrated circuit device, and FIG. 5 is a correlation diagram between surface oxygen concentration and surface defect density. 1...Silicon wafer surface, 2...
Activation region of element, 3...Oxygen, 4...
- Lattice defect, 5...Oxygen donor. Figure 3 Separate figure 4 Figure 5 Dark frowning five side 0 cover 1 dark trap

Claims (1)

[Claims] It has an I-G effect and the oxygen concentration within 910 μm from the silicon surface is 5 x 10"crrL-" or less,
A semiconductor device characterized by using a silicon wafer whose surface region is substantially defect-free.