JPS6072219A - Fabrication of semiconductor single crystal thin film - Google Patents

Abstract

PURPOSE:To obtain the epitaxial layer of excellent crystallizability by a method wherein when a semiconductor film is epitaxially grown on an insulating substrate, the substrate is coated with the first semiconductor film firstly followed by ion implantation after which the first film is removed by etching and the second semiconductor film is newly grown epitaxially on the exposed surface of the substrate. CONSTITUTION:An Si film 2 of about 0.2mum thick is deposited on a sapphire substrate 1 by vapor deposition and Si<+> ions are implanted with acceleration energy of 120keV and doze quantity of 1X10<15>/cm<2>. Thus a projection range at implantation of ions is set near the boundary of Si and sapphire to produce a surface layer having high concentration of a distribution in a depth direction in the surface side on a sapphire side. Next, the film 2 is removed by etching using an HF-HNO3-group solution. The sapphire substrate thus changed its surface condition is put in a CVD oven and while an H2 carrier gas and an SiH4 gas are introduced to make the substrate temperature 950 deg.C and growing speed 2mum/ sec, an Si film 3 of about 0.6mum thick is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for manufacturing a semiconductor single crystal film on an insulating crystal substrate.

[Prior art and its problems]

An integrated circuit using a semiconductor film on an insulating single crystal substrate is advantageous over one using a semiconductor substrate in terms of its structure, high density, and high speed.

On the other hand, since different types of single crystal films are crystallized on a single crystal substrate, a high density of lattice defects exists on this single crystal substrate.
They have the disadvantage of degrading the electrical characteristics of the device. For example, a silicon film (S) on a sapphire single crystal substrate
MOS denomination devices using MOS) compared to those using Si single-crystal substrates.

It is known that carrier mobility is low.

Basically, lattice defects occur in silicon films.

This is due to the mechanism at the early stage of silicon film growth.

In other words, when silicon grows on a sapphire substrate,
This is because nucleation occurs, and during this process, sapphire and silicon react in G1, and as a result, correction of the orientation difference between particles due to droplet-like coalescence is prevented.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for epitaxially growing a semiconductor thin film with excellent crystallinity by changing the growth mode in the early stage of growth.

[Summary of the invention]

In the present invention, the epitaxially grown semiconductor 1
By introducing the constituent atoms (Si) of the first bullet (Si), fluorine, or an inert gas such as argon into the insulating substrate using the ion implantation method, the semiconductor film is allowed to grow uniformly on the insulating substrate. , preventing the formation of lattice defects.

〔Effect of the invention〕

The present invention has made it possible to eliminate the generation of lattice defects during the initial growth process and to produce devices with excellent electrical characteristics on an insulating substrate.

[Embodiments of the invention]

This will be explained below using examples. FIG. 1 is a diagram showing an embodiment of the present invention. (1012) Sapphire substrate (1
) is prepared, and a silicon film (2) is deposited on it using a vapor deposition method.
2 μm JIJ product. Next, silicon ions were accelerated at an energy of 120 KeV and a dose of I x 10 ``cm-''.
Inject into the sample under the following conditions. The projected range of ion implantation at this time is near the silicon-sapphire interface, so
Sapphire 11111# is also implanted with silicon ions, and the depth distribution of silicon in Sapphire 1 (1) has a high concentration on the surface side.Next.

Etch the silicon film with HF-HNo system solution.

Since the sapphire substrate is chemically stable, one surface 21 is not etched. A sapphire substrate with etched silicon film was placed in a CVD furnace.

A silicon film is grown to a thickness of 0.6 μm at a substrate temperature of 950° C. and a growth rate of 2 μm/sec using hydrogen gas as a carrier gas and S i H 4 gas as a base gas.

The lattice defect density of this sample was measured by a selective etching method and was found to be 2.5 x 10'/cm', which was reduced by two orders of magnitude compared to the conventional method in which silicon was epitaxially grown directly on the sapphire substrate 1.

The reason why the lattice defect density decreased in this way is considered to be as follows. That is, silicon implanted into a sapphire substrate is rearranged during epitaxial growth, particularly on the sapphire surface, making it easier for silicon to break and adhere to the substrate surface during epitaxial growth. For this reason, uniform growth is possible in the initial stage of growth, and the generation of lattice defects is minimized.In addition, since the sapphire surface is covered with silicon 11. and then ion implantation is performed, damage to the sapphire surface is minimized. It can be made small and the crystallinity of one surface is maintained.

[Other embodiments of the invention]

The type and orientation of the substrate is sapphire (1012).
Of course, it is only good for the surface. The ion implantation conditions, silicon film growth method and conditions are also not limited to those in the embodiment.

[Brief explanation of drawings]

FIGS. 1A to 1C are cross-sectional views showing one embodiment of the present invention. 1... Sapphire (1012) surface, 2... First semiconductor film, 3... Second semiconductor film. Semiconductor film. Patent attorney Noriyuki Chika (and one other person) Figure 1 (θ, ) (b) SL+CC)

Claims (1)

[Claims] A sickle coated with this first semiconductor film on an insulating single crystal substrate,
A step of performing ion implantation, a step of removing the ion-implanted semiconductor film, and epitaxial growth of a second semiconductor film of the same type as the first semiconductor film on the insulating single crystal substrate from which the semiconductor film has been removed. A method for producing a semiconductor single crystal thin film, the method comprising the step of: