JPH0479228A - Formation of semiconductor layer - Google Patents

Abstract

PURPOSE:To enable effective prevention of lamination defects in a semiconductor layer by carrying out ion implantation and heat treatment of impurities and neutral element to a surface part of a semiconductor substrate before growth of the semiconductor layer. CONSTITUTION:An amorphous-processed layer 2 is formed on a surface part of a semiconductor substrate 1 through ion implantation of silicon as a neutral element. A high concentration impurity layer 3 is formed on a surface part of the semiconductor substrate 1 through ion implantation of impurities such as boron B, phosphorus P or arsenic As. Thereafter, crystal of the amorphous layer 2 is recovered by annealing. Then, an oxide film is formed by sacrificial oxidation, a sacrificial oxide film 4 is removed, metallic impurities, etc., which are produced on the surface part of the semiconductor substrate 1 are removed, and a silicon epitaxial growth layer 5 is formed.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B0 Overview of the invention C1 Prior art 0 Problems to be solved by the invention E1 Means for solving the problems F6 Effects G Examples [Figures 1 and 2] H9 Of the invention Effects (A, Industrial Application Field) The present invention relates to a method for forming a semiconductor layer, and particularly to a method for forming a semiconductor layer in which the semiconductor layer is grown on the surface of a semiconductor substrate.

(B. Summary of the Invention) In the method for forming a semiconductor layer described above, the present invention includes the steps of removing impurities and intermediates from the surface of the semiconductor substrate before growing the semiconductor layer, in order to prevent stacking faults from occurring in the semiconductor layer. This method involves ion implantation of a chemical element and heat treatment.

(C, Prior Art) As a manufacturing technology for semiconductor integrated circuits, impurities are injected into a semiconductor device at a high concentration by ion implantation, and then an epitaxially grown layer is formed on the surface of this impurity implanted layer. Many techniques are used to form and manufacture semiconductor devices.

(D. Problem that the invention seeks to solve) However,
As described above, when an epitaxial growth layer is formed on the surface of a semiconductor substrate, there is a problem in that stacking faults occur at a high density on the surface of the epitaxial growth layer.

These stacking faults are caused by the crystal destruction of the semiconductor substrate surface by impurity ion implantation, and by the precipitation of metal impurities and implanted impurities at the interface between the semiconductor substrate surface and the epitaxial growth layer, which become the nucleus. This occurs due to the growth of defects as the epitaxial growth layer grows.

Therefore, attempts have been made to reduce the precipitation of metal impurities and implanted impurities by performing sacrificial oxidation on the surface of the impurity implantation layer before forming the epitaxial growth layer and removing the oxide film produced by the sacrifice.

However, in reality, it has not been possible to sufficiently lower the density of stacking faults.

Therefore, an object of the present invention is to effectively prevent stacking faults from occurring in semiconductor layers.

(E. Means for Solving the Problems) In order to solve the above problems, the method for forming a semiconductor layer of the present invention includes ion implantation of impurities and neutral elements into the surface portion of the semiconductor substrate before the growth of the semiconductor layer. It is characterized by performing heat treatment.

(F, Effect) According to the method for forming a semiconductor layer of the present invention, not only impurity ion implantation but also neutral element ion implantation is performed into the semiconductor substrate surface before the growth of the semiconductor layer. Can be made amorphous. And after that,
Because heat treatment is performed, it is possible to recover the crystals on the surface of the semiconductor substrate that has once become amorphous, and during the heat treatment, metal impurities near the surface of the semiconductor substrate can be gettered by defects in the neutral element injection layer. Since the semiconductor layer is formed on the semiconductor substrate on which the crystals have been recovered and the metal impurities have been gettered, stacking defects in the semiconductor layer can be considerably reduced.

(G, Example) [FIGS. 1 and 2] Hereinafter, a method for forming a semiconductor layer of the present invention will be described in detail according to the illustrated example.

FIGS. 1A to 1E are cross-sectional views showing one embodiment of the method for forming a semiconductor layer of the present invention in the order of steps.

(A) As shown in FIG. 2A, the surface of the semiconductor substrate 1 is made amorphous by ion-implanting silicon as a neutral element. Reference numeral 2 denotes an amorphous layer formed on the surface of the semiconductor substrate 1 by this ion implantation.

The implantation concentration of silicon is, for example, 2 x 1015 cm-2
Good condition.

(B) Next, as shown in the same figure (B), for example, boron B, phosphorus P, or arsenic A
A high concentration impurity layer 3 is formed by ion-implanting impurities such as s. The impurity implantation concentration is, for example, 2×1
It is about 0"cm-2.

(C) Next, as shown in the same figure (C), for example, 1200
By annealing at a temperature of .degree. C., the amorphous layer 2 into which silicon ions have been implanted is crystallized.

(D) Next, as shown in the figure (D), the surface of the semiconductor substrate 1 is subjected to sacrificial oxidation (heating temperature: 1200° C.). 4 is an oxide film formed by this sacrificial oxidation.

(E) After that, metal impurities generated on the surface of the semiconductor substrate 1 are removed by removing the sacrificial oxide film 4, and then a silicon epitaxial growth layer 5 is formed as shown in FIG. do.

Figure 2 shows the dependence of the density of stacking faults on the silicon dose, where the horizontal axis shows the silicon dose [×1015cm-
2] and the stacking fault density [cm-2] is plotted on the vertical axis.

As is clear from this figure, in the conventional case, that is, the process (A
) is not provided, and therefore the silicon dose is 0, the defect density is about 10'cm-2, whereas if silicon is implanted at about 2 x 1 () 15cm-2 as in this example, The defect density can be reduced to less than 10" CD1-2, that is, less than 1/100. In reality, the number of defects is reduced to 1
It was also possible to make it less than 0 cm-2.

As described above, according to the present method for forming a semiconductor layer, since the surface portion of the semiconductor substrate 1 is made amorphous by silicon ion implantation and then activated and annealed, crystal destruction caused by impurity ion implantation can be recovered. ,Also,
Metal impurities in the vicinity of the surface of the semiconductor substrate 1 can also be gettered by defects in the silicon injection layer 2 during activation annealing, and the defect density can be reduced as described above.

In the above embodiment, the silicon ion implantation step was performed before the impurity ion implantation step, but the reverse may be used, or silicon and impurity ions may be implanted simultaneously. Further, the thickness of the amorphous layer formed by silicon ion implantation may be thinner or thicker than the thickness of the high concentration impurity layer. Although silicon is ion-implanted as a material, other elements, such as carbon, may be ion-implanted as long as they have little negative effect on the crystallinity of silicon.

(H, Effects of the Invention) As described above, the method for forming a semiconductor layer of the present invention involves ion-implanting impurities and neutral elements into the surface of a semiconductor substrate, followed by heat treatment, and then forming a layer on the semiconductor substrate. It is characterized by growing a semiconductor layer.

Therefore, according to the method for forming a semiconductor layer of the present invention, before the growth of the semiconductor layer, not only impurity ions are implanted into the surface of the semiconductor substrate (ion implantation of neutral elements is also performed, so the surface of the semiconductor substrate is once made amorphous). You can then
Since the heat treatment is performed, the crystals on the surface of the semiconductor substrate that have been once amorphous can be recovered, and metal impurities near the surface of the semiconductor substrate can be gettered by defects in the neutral element injection layer during the heat treatment. Since the semiconductor layer is formed on the semiconductor substrate on which the crystals have been recovered and the metal impurities have been gettered, stacking defects in the semiconductor layer can be considerably reduced.

1... semiconductor substrate, 2...Neutral element injection layer.

[Brief explanation of drawings]

FIGS. 1A to 1E are cross-sectional views showing step-by-step an embodiment of the method for forming a semiconductor layer of the present invention, and FIG. 2 is a diagram showing the dependence of defect density on silicon dose. Explanation of symbols 1

Claims (1)

[Claims] (1) A method for forming a semiconductor layer, which comprises ion-implanting impurities and neutral elements into the surface of a semiconductor substrate, then performing heat treatment, and then growing a semiconductor layer on the semiconductor substrate.