JPH03278520A - Laser cvd apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus, which can sufficiently form a desired deposit by one laser light source and can contrive to make a deposition speed higher and deposition more efficient by equipping an apparatus with a permeability variable optical system for half-splitting a single reaction-exciting laser light vertically and horizontally relative to a substrate and for applying the light to the substrate. CONSTITUTION:In a laser CVD apparatus for applying laser light to a raw material gas introduced into a reaction chamber 9 to subject the raw material gas to decomposition reaction and to deposit reaction chemical species generated from the raw material gas from a vapor phase on a substrate 8 placed in the reaction chamber 9 to grow a desired thin film, the apparatus is equipped with a permeability variable optical system 15 for half-splitting a single reaction-exciting laser light vertically and horizontally relative to the substrate 8 and for applying the light to the substrate 8. For example, a permeability variable optical system 15 for half-splitting laser light generated from a laser oscillator 1 and for changing the amount of energy of the half-split laser light in the manner of corresponding to a reaction time is provided and the half-split laser light is converged by a converging optical system 4, adjusted in energy density and guided to the reaction chamber 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser CVD apparatus for forming highly functional thin films used for semiconductors and mechanical parts.

[Prior Art] FIG. 3 shows a conventional laser CVD apparatus disclosed in, for example, Japanese Unexamined Patent Publication No. 61-30028.

Light source for substrate heating (1) and pulsed laser light source for reaction (2)
) are arranged in parallel, a light beam control system (3) is connected to the substrate heating light source (1), and a pulsed laser light source (2) for reaction is connected to the light source (1) for heating the substrate.
) is attached with a cylindrical lens (4) for condensing light. (5) is a mirror for perpendicularly entering the laser beam onto the substrate (8).The substrate (8) on which the desired deposit is to be formed. A raw material gas supply system (6) for reaction and a raw material gas exhaust system (7) are connected to the reaction chamber (9) in which vertical and horizontal laser beams are installed. A laser transmission window (10) is provided to guide the laser beam into the reaction chamber (9).

A common lock (11) for synchronizing each other and a variable delay circuit (12) for setting respective predetermined delay times when synchronizing are connected between the light sources (1) and (2). ing. (13) is a microcomputer for controlling these,
(14) is a substrate support stand.

With the above configuration, the substrate (
A source gas is introduced from the source gas supply system (6) onto the surface of the substrate (8), and a deposit is formed on the substrate (8) in a vapor phase.

At this time, the laser pulse (1) for heating the substrate is focused using a cylindrical lens (4) and then vertically irradiated onto the substrate (8), and the pulsed laser beam from the reaction light source (2) is applied to the substrate. (8) Irradiate horizontally. It is necessary to irradiate the raw material gas and the substrate (8) with the pulsed laser beam for heating the substrate and the pulsed laser beam for reaction at appropriate timings. In order to obtain this timing, a common lock (11) is used for synchronization, and the timing is set by a variable delay circuit (12) for setting each predetermined amount of delay time. As a result, the supplied raw material gas is photolyzed by the two pulsed laser beams, and a desired product can be deposited on the substrate (8). moreover.

The raw material gas after use is discharged to the outside of the yarn through an exhaust system (7).

[Problems to be Solved by the Invention] The conventional laser CVD apparatus as described above requires the use of two light sources as laser light sources for reaction, and the need to synchronize the two light sources. There were problems such as the equipment was large-scale and its utilization efficiency was low.

This invention was made to solve the above-mentioned problems, and it is possible to sufficiently form a desired deposit with a single laser light source, and also to increase the speed and efficiency of deposition. The purpose is to obtain a laser CVD device that can perform the following steps.

[Means for Solving the Problems] A laser CVD apparatus according to the present invention includes a light splitting means such as a beam splitter with variable transmittance as a laser light irradiation method, and simultaneously irradiates a substrate with laser light horizontally and vertically. This is how it was done.

[Function] In this invention, the laser beam is divided into two by the light splitting means.
Divide the beam and irradiate the substrate horizontally and vertically at the same time. Furthermore, by making the transmittance of the light splitting means variable, irradiation is performed with the horizontal and vertical laser energy ratios changed.

[Embodiment J] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In Figure 1, the laser oscillator (1) has a transmittance that divides the laser beam generated by the laser oscillator (1) into two, and changes the energy amount of the divided laser beam in accordance with the reaction time. A variable optical system (15) is attached. (5) is a total reflection mirror for changing the optical path of the vertically incident laser beam (17), (4) is a condensing optical system for adjusting the energy density of the laser beam, (16), (
17) converts the laser beam generated from the laser oscillator (1) into 2
These are the horizontally incident laser beam and the vertically incident laser beam, respectively.

In addition, the same reference numerals as in FIG. 3 indicate the same or corresponding parts.

Next, the operation will be explained. A variable transmittance optical system (15) transmits a laser beam generated from a laser oscillator (1), such as an argon-fluorine or krypton-fluorine excimer laser beam.
) and divide it into two parts. The two divided laser beams are a horizontally incident laser beam (16) and a vertically incident laser beam (16), respectively.
17), and after condensing the light and adjusting the energy density by the condensing optical system (4), the laser beam introducing window (10
) into the reaction chamber (9). Raw material gas supply system (
6) Supplying raw material gases, such as disilane gas and hydrogen gas, to the reaction chamber (9) while controlling the flow rates. By irradiating this raw material gas with a laser beam, the raw material gas is excited and undergoes a decomposition reaction to form a desired deposit (microcrystalline silicon) on the substrate (8) in the gas phase using conventional laser CVD. In the apparatus, the substrate on which the thin film is to be formed is irradiated with laser light horizontally, vertically, or both at the same time, but in either method, the laser energy is always kept constant. However, during thin film formation, a lot of normal incident laser energy is required to generate crystal nuclei on the substrate surface, but less energy is needed in the subsequent growth process, which is because too much normal energy can cause the deposits to nucleate. This is due to the discovery that in order to achieve high-speed film formation, it is desirable to reduce the vertical laser energy and increase the horizontal incident energy to promote the gas phase reaction. . Therefore, the laser beam from one laser oscillator (1) is divided into two by a beam splitter and irradiated horizontally and vertically at the same time, but when dividing, the transmittance of the beam splitter is adjusted to match the thin film forming process. It is variable. Specifically, as shown in Figure 2, by optimizing the process by changing this variable transmittance in an S-shaped manner with respect to the reaction time, we have created a structure suitable for effective use of laser light and thin film formation. It becomes possible to set the device configuration.

With the above device configuration, laser light, which has a high photon cost, can be effectively used for thin film formation reactions, and high-performance thin films can be efficiently formed, and high-speed deposition can be achieved, leading to cost reductions. It becomes possible.

In the above embodiments, an excimer laser oscillator is used as the laser light source, but other light sources may be used, for example, harmonics of a solid-state laser such as a YAG laser may be used.

Further, although the variable transmittance optical system has been described, as a means for dividing the laser beam, a chopper equipped with a reflecting mirror may be rotated to divide the laser beam into two parts, and the same effect as in the above embodiment can be obtained.

Furthermore, a beam splitter for a variable transmittance optical system can be manufactured by coating a dielectric material (for example, silicon dioxide, etc.) with a controlled film thickness, or a dye laser (for example, Rhodamine 110, etc.) can be used as a light source for generating laser light for reaction excitation. ), various modifications can be considered, such as using harmonics of

[Effect of the invention] As described above, according to the present invention, a single laser beam can be
Since the laser is divided and irradiated simultaneously horizontally and vertically, and the horizontal and vertical laser energies are optimized for the reaction, the equipment can be made at a low cost and deposits can be obtained efficiently.

[Brief explanation of the drawing]

Fig. 1 is an optical circuit diagram of an embodiment of the present invention, Fig. 2 is a reaction time dependence characteristic diagram of transmittance of a beam splitter of a variable transmittance optical system, and Fig. 3 is an optical circuit of a conventional laser CVD apparatus. It is a diagram. (1)... Laser oscillator, (6)... Raw material gas supply system, (8)... Substrate, (9)... Reaction chamber, (15)...
Variable transmittance optical system. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Dosho Soga Figure 1 15-・Transmittance @variable) E school

Claims (1)

[Claims] By irradiating the raw material gas introduced into the reaction chamber with a laser beam, the raw material gas is decomposed and reacted, and the reaction generated from the raw material gas is deposited from the vapor phase on a substrate installed in the reaction chamber. A laser CVD apparatus for growing a desired thin film by irradiating a single reaction excitation laser beam into two parts perpendicularly and horizontally to a substrate and irradiating said substrate with a variable transmittance optical system. Laser CVD equipment.