JPS6321818A - Treating method for semiconductor thin film - Google Patents

Abstract

PURPOSE:To make it possible to obtain rapidly a polycrystalline semiconductor thin film having crystal particles of a large particle size, by applying heat treatment to an amorphous semiconductor thin film in a heating furnace after energy beams are applied thereto. CONSTITUTION:Silicon ions Si<+> are implanted into a semiconductor thin film formed on a substrate, so as to make it amorphous. Next, excimer laser is applied to said semiconductor thin film. Thereafter, it is annealed by a heating furnace whose temperature is 600 deg.C or below, for instance. By applying the excimer laser to the semiconductor thin film before annealing, in this way, the amorphous semiconductor thin film can be put in an amorphous state which is found just before polycrystallization. Thus, a time required for generation is made to be zero substantially, and the size of a crystal particle which can be made to grow in the same annealing time can be made larger than usual.

Description

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

A. Industrial fields of application B1 Overview of the invention C1 Background art 1 Problems to be solved by the invention [Figure 3] E0 Means for solving the problems F0 Effects G. Examples [Figures 1 and 3] Figure 2] H0 Effects of the Invention (A, Industrial Application Field) The present invention relates to a method for processing a semiconductor thin film, and particularly to a method for processing a semiconductor thin film in which crystal grains having a larger grain size are grown than by heat-treating the semiconductor thin film. .

(B. Summary of the Invention) The present invention provides a semiconductor thin film processing method for rapidly growing crystal grains having a larger grain size than by heat-treating a semiconductor thin film. , Before heat treatment, the semiconductor thin film is irradiated with energy rays such as a laser beam. Therefore, the irradiation of the energy rays instantly changes the amorphous semiconductor thin film to an amorphous state just before polycrystallization. Polycrystalization by the subsequent heat treatment rapidly progresses, and as a result, a polycrystalline semiconductor thin film having crystal grains with a large grain size can be quickly obtained.

(C, Background technology) To manufacture TPT, etc., silicon ions Si1 are ion-implanted into a semiconductor thin film grown on a substrate to temporarily make the semiconductor thin film amorphous, and then the substrate is passed through a heating furnace to anneal it. A technique that makes semiconductor thin films polycrystalline is often used. According to this technique, it was possible to increase the grain size of crystal grains to 5 μm.

(D. Problems to be Solved by the Invention) [Figure 3] By the way, the method of implanting silicon ions Si+ into a semiconductor thin film to make the semiconductor thin film amorphous and annealing takes a long time to form the nuclei of crystal grains. This method has a major drawback in that it takes a long time and therefore the time required to obtain crystal grains with a large grain size, that is, the annealing time is extremely long.

Figure 3 shows the relationship between the annealing time and the maximum grain size of crystal grains, using the implantation amount of silicon ions Si+ during ion implantation for amorphousization as a parameter. For example, when the implantation amount is 5xlO15 /c
It is clear that in the case of m2, the maximum particle size can certainly be made 5.0 μm or more. However, no grains grow at all until about 15 hours have passed after the start of annealing. That is, it takes as much as 15 hours for grain growth nuclei to occur. Therefore, the annealing time inevitably becomes very long.

However, the implantation amount of silicon ion Si" is 1゜5X10
15/cm2, the time from the start of annealing to the start of grain growth becomes shorter;
The growth rate becomes extremely slow when it grows to 5 μm.
It is very difficult to obtain such grains. When the implantation amount is on the order of 1014/am2, grain growth starts immediately after the start of annealing, but the growth stops immediately, making it impossible to make the maximum grain size of the grains 0.1 μm or more.

Therefore, in order to grow grains to a grain size of 5 μm or more, the dose of silicon ion Si” should be 1.sx 10157 cm2 or more, preferably 5x
It is necessary to make it 1015/cm2 or more, but in that case, it would take as long as 15 hours for nuclear generation, and this time could not be overlooked when trying to improve the productivity of TPT etc.

The present invention has been made to solve these problems, and aims to make it possible to quickly obtain crystal grains having a large grain size.

(E. Means for Solving the Problems) In order to solve the above-mentioned problems, the semiconductor thin film processing method of the present invention is characterized by performing heat treatment in a heating furnace after irradiating the amorphous semiconductor thin film with energy rays. That is.

(F. Effect) According to the method for processing a semiconductor thin film of the present invention, energy rays are irradiated before the amorphous semiconductor thin film is heat-treated. However, it is possible to make it amorphous just before polycrystallization, and heat treatment can be applied to a sample of the amorphous semiconductor thin film facing polycrystallization. Therefore, grains can be grown immediately after the start of heat treatment, the heat treatment time can be shortened by the long time conventionally required to generate grain growth nuclei, and productivity can be improved accordingly.

(G, Example) [FIGS. 1 and 2] Hereinafter, the method for processing a semiconductor thin film of the present invention will be explained in detail according to the illustrated embodiment.

FIG. 1 is a flowchart showing one embodiment of the semiconductor thin film processing method of the present invention in the order of steps.

(a) The semiconductor thin layer (film thickness: 800 mm) formed on the substrate is made amorphous by implanting silicon ions "Si". The amount of silicon ions Si+ implanted is, for example, about 5xlO157 cm2.

(b) Next, the semiconductor thin film is irradiated with an excimer laser. It is better to perform this irradiation at a low energy of, for example, somj/pulse/Cm2, and to perform it locally by reticle control only at the portions of the semiconductor thin film where cells such as TPT are to be formed. However, if the channel length or channel width is long, irradiation is performed in a linear manner.

(c) After that, annealing is performed in a heating furnace at a temperature of, for example, 600° C. or lower than that of warp.

By irradiating the semiconductor thin film with an excimer laser during annealing in this manner, the amorphous semiconductor thin film can be brought into an amorphous state immediately before polycrystallization, and the time required for nucleation can be reduced to approximately zero. Figure 2 is a relationship diagram showing the relationship between the pulse energy of the laser beam and the size of the growing dalein when excimer laser is irradiated before annealing, and it is clear that the size of the dalein can be controlled by the pulse energy. .

As described above, since the time required for nucleation can be reduced to approximately 0, the size of the □ crystal grains that can be grown with the same annealing time can be made larger than before.

By selectively irradiating the amorphous semiconductor thin film with an excimer laser, dalein can be grown only in the selectively irradiated portions.

(H, Effect of the invention) As described above, the method for processing a semiconductor thin film of the present invention is as follows:
The method is characterized in that the amorphous semiconductor thin film is irradiated with energy rays and then heat treated in a heating furnace.

Therefore, according to the method for processing a semiconductor thin film of the present invention, the amorphous state instantly changes to the amorphous state immediately before polycrystalization by irradiation with energy rays, so that in the subsequent heat treatment, the nuclei of crystal grains immediately after the start of the treatment. is generated and the growth of the crystal grains proceeds rapidly, so that a polycrystalline semiconductor thin film having crystal grains with a large grain size can be quickly obtained.

[Brief explanation of the drawing]

1 and 2 are for explaining one embodiment of the method for processing a semiconductor thin film of the present invention. FIG. 1 is a flow diagram showing the processing method step by step, and FIG. FIG. 3 is a diagram showing the relationship between the annealing time and the grain size of the crystal grain to explain the problem to be solved by the invention. Flowchart shown on the shoulder of tf IJ process j 1 Figure 1 Flow diagram shown on the shoulder 2 Process (ml 7 cm) Energy and grain size p relationship diagram Figure 2

Claims (1)

[Claims] (1) A method for processing a semiconductor thin film, which comprises irradiating an amorphous semiconductor thin film with energy rays and then performing heat treatment in a heating furnace.