JPH0334326A - Semiconductor wafer - Google Patents

Abstract

PURPOSE:To augment the yield of devices by increasing the gettering capacity of heavy metal impurity by a method wherein the device is formed on an epitaxial wafer having misfit dislocation caused by the difference between the lattice constant of a high concentration impurity diffused layer and that of an epitaxial layer. CONSTITUTION:High concentration impurity diffused regions 2 are formed on a P-type silicon substrate 1 e.g. having crystal surface of 100 and in specific resistance of 0.01OMEGA.cm by selective doping of an impurity in the concentration of around 1X10<20>atom/cm<2>. Next, an epitaxial film 3 10mum thick is deposited on the P-type silicon substrate 1. The epitaxial deposition process is performed at the deposition temperature of 1150 deg.C and the room temperature using a mixed gas of hydrogen silicon tetrachloride (SiCl4). diboron (B2H6) as an applicable gas. At this time, the specific resistance of the epitaxial film 3 is specified to be 10OMEGA.cm by adjusting the amount of diboron. Through these procedures, the production of particles from rear surface is avoided; the decline in the yield affected by the particles is restrained; and the gettering capacity is increased so that the decline in the yield due to the heavy metal pollution during the device formation process may be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor wafer, and particularly to a semiconductor wafer having an epitaxial film formed on a semiconductor substrate.

[Conventional technology]

FIG. 2 is a cross-sectional view of an example of a conventional semiconductor wafer.

An epitaxial film 3 is formed on a P-type silicon substrate doped with boron as an impurity at a high concentration to create a wafer for manufacturing a semiconductor film device.

Such semiconductor wafers are prone to latch-up between elements and α
Since it is effective in preventing line soft errors, it is used in highly integrated memory circuit elements, highly integrated logic circuit elements, ultra-high speed memory circuit elements, and the like. At this time, in order to prevent latch-up and α-ray radiation error, it is effective for the P-type silicon substrate to contain as high a concentration of boron as possible and to have a low resistance. The epitaxial film 3 formed on this silicon substrate serves as a device formation region, and therefore has a resistivity that is two orders of magnitude higher than that of the silicon substrate in practice.

However, the lattice constant of a silicon substrate containing boron decreases as the boron concentration increases, and as the resistance decreases, the difference in lattice constant from that of the epitaxial film increases, causing large warpage of the wafer and misfit dislocations. For this reason, conventional semiconductor devices using epitaxial wafers of this type use epitaxial wafers with a reduced boron concentration in an attempt to prevent warping of the wafers and occurrence of misfit dislocations.

In addition, the back surface of such epitaxial wafers is damaged by sandblasting to getter the heavy metals. In this gettering method, the back surface of the wafer is crushed by sandblasting, so silicon particles are generated from the back surface during the device forming process.

[Problem to be solved by the invention]

Semiconductor devices using conventional silicon epitaxial wafers as described above have the disadvantage that misfit dislocations occur when the resistance of the P-type silicon substrate is lowered to prevent latch-up and α-ray soft errors, and this causes device failure.

Furthermore, in the sandblasting gettering method conventionally used for epitaxial wafers, particles are generated during the device formation process, which causes device failure.

[Means to solve the problem]

A semiconductor wafer of the present invention includes a semiconductor substrate in which a high concentration impurity diffusion region is selectively formed, and a semiconductor film epitaxially formed on the semiconductor substrate and in which a misfit dislocation generation region is formed on the high concentration impurity diffusion region. It is characterized by having the following.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are sectional views showing the order of steps for explaining a manufacturing method according to an embodiment of the present invention.

First, as shown in Figure 1(a), the crystal plane is (100)
A high concentration impurity diffusion region 2 is formed by selectively doping a P-type silicon substrate 1 having a specific resistance of 0.01 Ω· to a concentration of approximately 1×10 2′ atoms/d.

Next, as shown in FIG. 1(b), a P-type silicon substrate 1
An epitaxial film 3 is grown thereon to a thickness of 10 μm. In epitaxial growth, the growth temperature is 1150°C, normal pressure, and hydrogen/silicon tetrachloride (SiC) is used as the supply gas.
14) A mixed gas of diborane (B2H6) was used. At this time, the specific resistance of the epitaxial film 3 was set to 10Ω·Cl11 by adjusting the amount of diborane.

After forming the folds, this wafer was etched with a defect-selective etching solution to evaluate the occurrence of misfit dislocations. As a result, it was confirmed that a misfit dislocation generation region 4 as shown in FIG. 1(b) was formed. In addition, as a reference sample, an epitaxial film was grown to a thickness of 10 μm in the same manner as in the above example of the present invention on a P-type silicon substrate with the same resistivity as in the above example of the present invention and whose back surface was strained by sandblasting. As a result, an epitaxial wafer having a conventional structure as shown in FIG. 2 was obtained.

Dynamic random access memory devices (hereinafter referred to as DRAM devices) were created using the above two types of epitaxial wafers, and the amount of particles generated from the back surface and the yield of the devices were compared. As a result, generation of particles was observed in the epitaxial wafer of the conventional structure, whereas generation of particles was not observed in the epitaxial wafer of the present invention.

Furthermore, the yield of DRAM devices using the epitaxial wafer of the present invention was improved by 35% compared to that using an epitaxial wafer with a conventional structure.

This is because the present invention eliminates the generation of particles from the backside, which suppresses the drop in yield due to the influence of particles, and the improved gettering ability suppresses the drop in yield due to heavy metal contamination during the device formation process. It's a good thing.

〔Effect of the invention〕

As explained above, the present invention forms an epitaxial film on a substrate in which a high concentration impurity diffusion layer is formed in a partial region, and eliminates misfit caused by the difference in lattice constant between the high concentration impurity diffusion layer and the epitaxial film. By forming devices on an epitaxial wafer having dislocations, the misfit dislocation generation region has a high gettering ability for heavy metal impurities, making it possible to increase the yield of devices compared to the prior art.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are cross-sectional views for explaining a manufacturing method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of an example of a conventional semiconductor wafer. DESCRIPTION OF SYMBOLS 1... P-type silicon substrate, 2... High concentration impurity diffusion region, 3... Epitaxial film, 4... Misfit dislocation generation region, 5... Element formation region, 6... MO
S) Ranjistor.

Claims (1)

[Claims] It is characterized by having a semiconductor substrate in which a high concentration impurity diffusion region is selectively formed, and a semiconductor film epitaxially formed on the semiconductor substrate and in which a misfit dislocation generation region is formed on the high concentration impurity diffusion region. semiconductor wafers.