JPS60109220A - Manufacture of amorphous silicon - Google Patents

Abstract

PURPOSE:To increase the utilizing efficiency of a reactive gas by projecting the reactive gas from a nozzle to the point where the optical axis of a laser beam projected on a movable substrate crosses with the substrate and by projecting the laser beam only when the optical axis comes in accordance with the necessary position on the substrate surface as moving the substrate so as to form a selective film on the substrate. CONSTITUTION:Reactive gas are blown off from gas blow-off outlets 6a and 6b into a vacuum container. The front end of this gas outlet is thin and the gas is blown off from that end. Meanwhile, an optical axis of laser goes along the arrow A and is reflected by a mirror 3 and goes along the arrow B to reach the surface of a substrate 8. As a manipulator 9 can move upward, down ward, right and left, it is moved only at a constant pace and is stopped and the laser beam is projected the position where the manipulater is stopped. As the reactive gas is blown off in the vicinity of the substrate which is irradiated with the laser beam, a thin film of a-Si is formed on the substrate which is exposed to the spot of laser by laser CVD. Accordingly, if movement and stop of the manipulator is synchronized with the intervals of irradiation of laser, it is possible to form the spots of a-Si film on the substrate at a constant pace.

Description

DETAILED DESCRIPTION OF THE INVENTION In laser CVD, the present invention injects a reactive gas only in the vicinity of the substrate that is hit by the laser beam, and selectively deposits amorphous silicon (hereinafter referred to as a-Bi) in the necessary locations on the substrate. This invention relates to a method for producing amorphous silicon that improves the efficiency of using reactive gases in the production of devices.

Saichika, α-si technology has progressed, and devices that incorporate a large number of α-8i elements in a large area have appeared, such as display panel switching TF'Ts, two-dimensional reading optical sensors, or line sensors. It is being done.

Conventionally, when making such devices, plasma O
After applying α-Bi to the entire surface of the substrate by VD, optical VD, or thermal CVD, the necessary portions, that is, the TPT portions serving as the sensor portions are left, and the other portions are removed by photoetching. That is, only a small portion of the formed α-si is effectively used.

Furthermore, in the conventional apparatus, since the gas introduced into the vacuum container spreads throughout the vacuum container, it adheres not only to the α-gild substrate but also to unnecessary parts of the vacuum container. Furthermore, unreacted gas is discharged to the exhaust system. in this way,
In the conventional method, a large amount of reaction gas is wasted.

Generally, the silane gas used in the production of a-8i is a very expensive gas. For example, monosilane gas costs about 100 yen per 111 (-; 100 F/l). The conventional method for this gas is 100 to 200 cc/mi? 1.
If plasma CVD is performed for one hour, the gas cost alone will cost 600 to 1,200 yen. Moreover, only a small portion of α-S< is effectively used as a device.

The present invention eliminates these drawbacks, and its purpose is to improve the efficiency of reactant gas utilization.

FIG. 1 shows the reaction chamber of the apparatus used in the production of the present invention. The upper half of FIG. 1 is a side view of the reaction chamber, and the lower half is a plan view. In Fig. 1, an IH vacuum container, a two-digit laser,
3Fi mirror, 4 is light introduction port.

5 a): 5 bd reaction gas inlet pipe, 6α and 6bu gas outlet, hole diameter at the tip #-i3 to 10sn.

Further, a substrate heater 76, a substrate 8, and a manipulator 9 can move the substrate heater 7 and the substrate 8 vertically and horizontally. In addition, 1o is an exhaust port connected to a vacuum exhaust system consisting of an oil diffusion pump and an oil rotary pump.The manufacturing method will be described. In Fig. 1, the inside of the vacuum container 1 is evacuated from the vacuum exhaust port 10 to IXjO-'TOrr: 6, and then one reaction gas is introduced one step at a time to bring the temperature of the substrate 8 to 200'C using the substrate heater 71C. A reactant gas is introduced into the tube from an external gas system. The reaction gas is
This is a mixture of hydrogen and silane mixed with doping gas such as diborane or phosphine, if necessary.

This reaction gas is blown out into the vacuum container from gas outlet ports 6α and 6b. The tip of the air outlet has an inner diameter of 3~
It is narrowed to 10 meters, and the gas is 5 to 10 meters from this mouth.
cc/mix, blows out.

On the other hand, the optical axis of the laser passes through arrow A, is reflected by mirror 3, and reaches the surface of entering substrate 8 along arrow BK.

Here, since the manipulator 9 can move vertically and horizontally, it moves by a certain pitch and then stops.

Stop and irradiate the fc- location with laser light. Since a reactive gas is blown out near the substrate irradiated with the laser beam, a thin film of α-Bi is formed by the laser QVDK on the substrate hit by the laser spot.

Therefore, by synchronizing the movement and stop of the manipulator with the laser irradiation interval, α-
8i film spots can be formed. Specifically, the manipulator is moved by a motor drive, and the laser irradiation and the manipulator movement are synchronized by a computer.

Using a 1-t 100 W carbon dioxide laser as the laser,
Although not shown in FIG. 1, an optical system was used to form a spot with a diameter of 50 to 60 μm on the substrate surface. At this time, an α-Si film with a diameter of 60 to 80 μm could be formed on the substrate. If the laser beam is further focused, the diameter will be 20μmφ.
It is also possible to form an α-si film.

By the above method, the efficiency of reactant gas, which has been a problem in the past, has been greatly improved. The effect will be explained using an example of a line sensor. The line sensor for A4 size is approximately 210 IIm long, and the optical sensor is approximately 18
The diameter of the sensor is approximately 0.1 m square (or approximately 0.1 m in diameter). In addition, since the sensor thickness is usually about 1μ, when forming an α-Si film using the conventional method, the VC is 3μ.
200 cc/mi for 0 minutes? 1. must be flushed with monosilane gas. Therefore, the total amount of monosilane is 6
It is t.

On the other hand, in the case of the present invention, the film formation rate of laser OVD is 1 to 3 μtn/S. Even if it were 1 μrn/S, it would take about 30 minutes to form 1800 elements, which is the conventional film formation time. It's exactly the same. However, the reaction gas (
Mainly monosilane) flow it u 5 cc/rrr
in.

is sufficient. Therefore, the total amount was 0.151, which was 1/40 of the conventional amount. Since the price of silane is as high as Moe's price, this difference is of great value.

The manufacturing method of the present invention has an extremely wide range of applications, including not only the above-mentioned line sensor but also a switching TPT for a two-dimensional display, a two-dimensional introduction optical sensor, etc.

[Brief explanation of drawings]

Figure 1) is a synonym for the apparatus used in the production of the present invention. 1... Vacuum vessel 2... Laser 3... Mirror 4... Light introduction port 5α~5b... Reaction gas introduction tube 6a~ 6b...
・・・・Gas blowing lower ・・・・・Substrate heater 8 ・・Substrate 9 ・・Manipulator 10 ・・・・・Exhaust port and above Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Figure 1

Claims (1)

[Claims] In a method of manufacturing amorphous silicon using a laser CVIIIC, the optical axis of a laser beam is directed onto a movable substrate and the optical axis changes toward the point where the optical axis and the substrate change. Amorphous silicon that selectively forms a film on a substrate by injecting a reactive gas from a nozzle, moving the substrate, and irradiating a laser beam only when the optical axis matches the required position on the substrate surface. manufacturing method.