JP2003128491A - Silicon substrate for epitaxial wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon wafer for epitaxial wafer in which the transition layer width and particle of the epitaxial wafer can be uniformly controlled over whole surface of the epitaxial wafer, and which improves the production yield of the epitaxial wafer and the production yield and the reliability of a final product or a device. SOLUTION: The silicon substrate for epitaxial wafer on the surface of which an epitaxial film is formed includes boron of 10<18> atoms/cm<3> or more and further includes tin of 0.1 to 1.0×[BX] atoms/cm<3> relative to the boron concentration [BX].

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon substrate for an epitaxial wafer, and more particularly to a silicon substrate for an epitaxial wafer doped with boron and tin. 2. Description of the Related Art In recent years, M devices such as power devices and VLSI
Silicon epitaxial wafers are widely used as substrates for semiconductor devices having an OS structure. MO like this
A typical silicon epitaxial wafer for S is a silicon single crystal substrate containing a high concentration of boron and the same silicon single crystal film grown in a vapor phase. The reason for adding high-concentration boron to the substrate is to add a so-called intrinsic gettering function to the substrate. [0003] However, under the current state of miniaturization of devices, it has become evident that the characteristics and defects of the epitaxial layer affect the electrical characteristics of the device. The required characteristics are also becoming stricter. For example, as a MOS LSI epitaxial wafer, the transition layer width on the epitaxial layer side caused by the diffusion of boron from a silicon substrate containing high-concentration boron must be steep from 0.4 μm to 0.1 μm. In addition, particles on the surface of the epitaxial layer have become so severe that the existence of minute particles of 0.15 μm or less is not allowed. [0005] Correspondingly, the improvement of the epitaxial apparatus and the epitaxial process have been made. However, the conventional substrate containing boron of 10 ¹⁹ atoms / cm ³ or more is doped with P ¹⁶ atoms / cm ³ doped with boron at 10 ¹⁶ atoms / cm ³ or more. Type epitaxial layer having a film pressure of 5 μm is vapor-phase grown (reaction temperature: 1000 ° C., reaction gas: SiH ₄ , carrier gas: H ₂ , dopant: hydrogen gas containing 100 ppm of B ₂ H ₆ , flow rate: carrier gas: 40 l / min, reaction) Gas 11 l / min, dopant 1.6E- ⁴ l / mi
n, the number of rotations is 200 rpm), the transition width of the epitaxial layer is as shown in FIG.
FIG. 5 shows the in-plane distribution of particles of μm or less. Both the transition width shown in FIG. 4 and the particle characteristics shown in FIG. Such non-uniformity becomes more remarkable as the boron concentration of the substrate becomes higher, and 10 ¹⁸ atoms /
If it is more than cm ³ , it greatly affects the production yield of the epitaxial wafer and the characteristics of the device. As described above, when the conventional silicon substrate for epitaxial growth is used, it is difficult to control the transition width and the particle characteristics uniformly and precisely over the entire surface of the epitaxial wafer. In the vicinity, it is difficult to control the above characteristics to the desired shape,
The production yield of the epitaxial wafer, the production yield of the device of the final product, and the reliability were low. Therefore, the transition layer width and the particles of the epitaxial wafer can be controlled uniformly over the entire surface of the epitaxial wafer, and the production yield of the epitaxial wafer and the production of the device of the final product are further improved. There has been a demand for a silicon substrate for an epitaxial wafer with improved yield and reliability. The present invention has been made in view of the above circumstances, and can control the transition layer width and particles of an epitaxial wafer uniformly over the entire surface of the epitaxial wafer, and can reduce the production yield of the epitaxial wafer and the final product. It is an object of the present invention to provide a silicon substrate for an epitaxial wafer having improved device production yield and reliability. [0009] To achieve the above object, according to an aspect of, according to one aspect of the present invention, a silicon substrate for epitaxial wafer epitaxial film is formed on the surface, 10 and boron ¹⁸ atoms / cm ³ or more, and 0.1 to the boron concentration [BX].
There is provided a silicon substrate for an epitaxial wafer, characterized by containing tin of 1.0 to [BX] atoms / cm ³ . Thereby, the transition layer width and the particles of the epitaxial wafer can be uniformly controlled over the entire surface of the epitaxial wafer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a silicon substrate for an epitaxial wafer according to the present invention will be described in detail. As a result of extensive studies, the present inventors have found that the characteristics (transition width and particles) required of an epitaxial wafer affect the internal stress of the epitaxial wafer and the minute slip (dislocation) resulting from the release of the stress. Found to be. Further, they have found that the stress and the slip are affected by the silicon substrate in addition to the epitaxial device conditions and the epitaxial process conditions. Furthermore, although it is difficult to quantify these stresses and slips, various studies have been made on the assumption that the causes of these stresses and slips are caused by lattice mismatch between the silicon wafer of the substrate and the epitaxial layer. As a result, by adding tin to the substrate to the same degree as the boron concentration, the above-described stress and slip are greatly reduced, and the transition width and the 0.1%
It has been found that the inferiority at the periphery and the center of the epitaxial wafer of particles of 5 μm or less can be improved. Based on these findings, finally, the characteristics (transition width, particles) of the epitaxial wafer are controlled to high purity over the entire surface of the wafer by improving the silicon wafer as the substrate according to the present invention. Is now possible. That is, when manufacturing a MOS epitaxial wafer to be used for an VLSI or the like, the characteristics of the epitaxial wafer are improved by limiting the characteristics of the silicon substrate. The substrate for an epitaxial wafer according to the present invention is an epitaxial wafer using a silicon single crystal substrate containing at least 10 ¹⁸ atoms / cm ^{3 of} boron. 0x
[BX] It is a substrate containing atoms / cm ³ of tin at the same time. As a result, the thickness and particles of the transition layer of the epitaxial wafer can be controlled uniformly over the entire surface of the wafer. Next, a method of manufacturing a substrate for an epitaxial wafer according to the present invention will be described. The silicon wafer to be used contains 1 boron.
0 ¹⁸ atoms / cm ³ or more P with small specific resistance
It is a type wafer. On the surface of the silicon wafer substrate, a P-type epitaxial layer having a relatively high specific resistance and containing boron by two to three digits less than that of the substrate is formed in accordance with a conventional method. Specifically, a raw material gas and a carrier gas are supplied into a furnace of a batch type, a single wafer type or the like using a wafer epitaxial device. As the dopant, B ₂ H ₆ (concentration of about 100 ppm) mixed in H ₂ gas is used. For example, a case in which a thin film is vapor-phase grown on a wafer substrate by using a commonly used high-speed rotating single-wafer epitaxial vapor-phase growth apparatus will be described. First, a reaction gas, A carrier gas or the like is supplied to a reaction furnace of a vapor phase growth apparatus. As the reaction gas, S
iH ₂ , SiH ₆ , SiCl ₄ , SiHCl ₃ , SiH
₂ Cl ₂ or the like is used, and H ₂ is usually used as a carrier gas. The vapor growth temperature is 700 to 1200 ° C., the vapor growth pressure is 5 to 200 torr, and the number of rotations of the holder is 500.
An epitaxial layer is grown under operating conditions of about 2500 rpm. [Embodiments] Evaluation method: A silicon ingot is pulled up by the Czochralski method by combining various concentrations of boron and tin, and a silicon substrate containing various boron and tin concentrations cut out from the obtained silicon ingot is prepared. Prepare and perform epitaxial growth by the usual method. The transition width of the obtained epitaxial layer and particles of 0.15 μm or less were evaluated. Evaluation results: As shown in FIGS. 1 to 3,
Boron Concentration [BX] 1 × 10 ¹⁸ , 5 × 10 ^18, and 1 × 10 ¹⁹ atoms / cm ³ Transition Layer Width at Wafer Periphery (Most Recessive Part) and Tin Concentration Dependent on Number of Particles of 0.15 μm or Less Shows sex. As the substrate has a higher boron concentration, these characteristics become more inferior at the periphery and the center of the wafer, and the boron concentration is 1 × 10 ¹⁸ atom
At ms / cm ³ or more, the effect on the production yield and device characteristics of the epitaxial wafer cannot be ignored, as in the conventional example. However, as shown in FIGS. 1 to 3, the tin concentration is 0.1 to
When a silicon substrate containing 1.0 × [BX] is used at the same time, the inferiority of the above-mentioned characteristics at the periphery and the center of the epitaxial wafer is greatly improved, and the distribution in the wafer becomes uniform with a desired value and accuracy. Was. According to the silicon substrate for an epitaxial wafer according to the present invention, the transition layer width and the particles of the epitaxial wafer can be controlled uniformly over the entire surface of the epitaxial wafer. Can provide a silicon substrate for an epitaxial wafer in which the manufacturing yield and reliability of a device as a final product are improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a test result diagram of an example using a silicon substrate for an epitaxial wafer according to the present invention. FIG. 2 is a test result diagram of an example using a silicon substrate for an epitaxial wafer according to the present invention. FIG. 3 is a test result diagram of an example using a silicon substrate for an epitaxial wafer according to the present invention. FIG. 4 is a characteristic (transition width) diagram using a conventional silicon substrate for an epitaxial wafer. FIG. 5 is a characteristic (particle) diagram using a conventional silicon substrate for an epitaxial wafer.

Claims (1)

Claims 1. A silicon substrate for an epitaxial wafer having an epitaxial film formed on a surface thereof, wherein the silicon substrate contains boron at a concentration of 10 ¹⁸ atoms / cm ³ or more and has a boron concentration [BX]. 0.1 ~ 1.0 × [BX]
A silicon substrate for an epitaxial wafer, characterized by containing atoms / cm ³ of tin.