JPH06120139A - Semiconductor material manufacturing equipment - Google Patents

Abstract

PURPOSE:To stably obtain single crystal semiconductor material, when semiconductor material is fused and recrystallized by laser beam irradiation. CONSTITUTION:Polycrystalline or noncrystalline semiconductor material, e.g. polycrystalline or noncrystalline silicon thin film 2 on an insulative substrate 1 is irradiated with a laser beam BM0 from a laser lignt source 3 via a rotary mirror 5 of a rotary mirror equipment 4. The semiconductor material 2 is scanned in the direction of an arrow A. Thereby the polycrystalline or noncrystalline semiconductor material 2 can be continuosly fused and recrystallized. In this case, the laser beam BM0 is rotated by a radius corresponding to the inclination angle theta to the rotary shaft 7 of the rotary mirror 5. The beam profile of the laser beam on the semiconductor material 2 becomes a stable doughnut type having a specified radius. The beam intensity distribution becomes a stable double-humped type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor material manufacturing apparatus for melting and recrystallizing a polycrystalline or amorphous semiconductor material.

[0002]

2. Description of the Related Art Conventionally, a laser beam melting recrystallization method has been known when a single crystal thin film is formed on an insulating material to obtain a semiconductor device having an SOI structure. This laser melting recrystallization method is used, for example, when manufacturing a semiconductor device having an SOI structure, and a polycrystalline or amorphous silicon thin film formed on an insulating substrate 203 as shown in FIG. 12A. 201 is heated and melted with the energy of the laser beam BM, and the laser beam or the substrate is relatively moved to move the melting region as shown by an arrow A to cool and solidify the molten silicon, and recrystallized silicon 202 It is supposed to be. This laser melting recrystallization method does not require heating the entire substrate to near the melting point of silicon, unlike the zone melting recrystallization method using lamp light, a wire-shaped carbon heater, a high frequency heating carbon susceptor, or the like. Therefore, the scale of the manufacturing apparatus can be reduced, and there is no problem of substrate deformation due to high temperature heating. In addition, since the zone melting recrystallization method mainly uses radiant heating from various heat sources, the state of melting and recrystallization greatly differs depending on the distance between the heat source and the substrate, whereas the laser beam melting recrystallization method Since the crystallization method utilizes the generation of heat due to the absorption of laser light, the temperature profile on the substrate is less likely to be affected by the distance between the substrate and the laser light source,
Further, since the laser beam can be guided to the substrate from any position by using various optical systems such as a lens mirror, the coherency of the laser beam can be easily ensured, and therefore, compared with the zone melting recrystallization. Thus, the melting and recrystallization of the semiconductor material can be performed stably and reliably and efficiently.

[0003]

However, in the conventional semiconductor material manufacturing apparatus utilizing the laser beam melting recrystallization method, the intensity distribution of the laser beam on the surface of the semiconductor material (for example, silicon) has a converging property. From the goodness of
Normally, it is of a Gauss type as shown in FIG. Therefore, the temperature distribution in the vicinity of the molten region of the semiconductor material (silicon) reflects the Gaussian beam intensity, as shown in FIG.
As shown in, the central portion is highest in the beam scanning direction and becomes lower toward the periphery. In such a circumstance, recrystallization of molten silicon progresses simultaneously from the periphery of the melted portion, and thus recrystallized silicon often becomes a polycrystalline body as shown in FIG. You can't get stable.

In order to stably obtain the single crystal semiconductor material, the temperature distribution in the vicinity of the melting region may be set to be lower in the central portion and higher in the peripheral portion. That is,
In this case, since recrystallization proceeds from the central portion, crystal growth from a single nucleus is possible, and it can be expected that a single crystal region can be obtained in a wide range.

To obtain such a temperature distribution, for example,
It has been proposed to irradiate a laser beam with a bimodal intensity distribution as shown in FIG. Specifically, a laser beam having a Gaussian intensity distribution is separated into two beams by using a birefringent plate and is irradiated, or the document “Appl. Phys. Lett. 40 (5) 1 March 1982,
As described in "Pages 394 to 395", a laser beam mode is used as a donut type, or laser beams from two laser oscillators are combined and irradiated to obtain a bimodal intensity distribution. It is possible. These methods have the advantage of not changing the substrate structure and complicating the process, but in both cases, it is difficult to maintain the bimodal beam intensity distribution stably with good controllability. There is a problem that a material cannot be stably obtained, and it has not reached a practical level.

Further, in the conventional laser beam melting recrystallization method as shown in FIG. 12, the heating region is the laser beam B.
Since it is limited by the diameter of M, there is a limit to the processing capacity,
The throughput cannot be improved. processing power,
That is, in order to improve the throughput, a wide heating region may be formed by a laser beam. As a method of forming a wide heating region, for example, as shown in FIG. 16, a laser beam BM is used by using a vibrating mirror 504.
It is conceivable to oscillate at a high frequency in an arbitrary width in a direction B orthogonal to the substrate scanning direction A. However, this method requires a high-power laser to vibrate at a high frequency in consideration of the thermal diffusion rate in the substrate 501, and the width w of the heating region 503 of the semiconductor material 502 is limited. Further, as shown in FIG. 17, by irradiating a plurality of laser beams BMM in the direction B orthogonal to the substrate scanning direction A while arranging them in line and superimposing them,
It has also been proposed to form a wide heating region (Japanese Patent Laid-Open No. 59-52831). However, by overlapping the laser beams with Gaussian intensity distribution,
Forming a wide beam with a sufficiently uniform intensity distribution is
There was a problem that it was difficult in reality.

According to the present invention, a single crystal semiconductor material can be stably obtained when the semiconductor material is melted and recrystallized by irradiation with a laser beam, and further, a sufficiently uniform intensity distribution is wide. An object of the present invention is to provide a semiconductor material manufacturing apparatus capable of forming a beam and stably obtaining a single crystal semiconductor material with high throughput.

[0008]

1 (a) and 1 (b) are views showing a configuration example of a semiconductor material manufacturing apparatus according to the present invention. Referring to FIG. 1A, this semiconductor material manufacturing apparatus includes a laser light source 3 which emits a laser beam BM ₀ , and a polycrystalline or amorphous semiconductor material (for example, polycrystalline or amorphous) on an insulating substrate 1. 2) has a rotary mirror device 4 for irradiating a laser beam BM ₀ from a laser light source 3. Here, as the laser light source 3, a CO ₂ laser having an output capable of melting a polycrystalline or amorphous semiconductor material on the insulating substrate 1,
Ar laser, YAG laser or the like is used.

Further, referring to FIG. 1B, the rotary mirror device 4 has a motor 6 and a rotary mirror (rotary reflecting mirror) 5 attached to a rotary shaft 7 of the motor 6, and In the invention, the reflecting surface of the rotary mirror 5 of the rotary mirror device 4 is attached in a state of being inclined by an angle θ with respect to a right angle with respect to the rotary shaft 7 of the motor 6, as shown in FIG. Here, as the mirror 5, one that reflects 99% or more of the laser beam BM ₀ from the laser light source 3 is used.
For example, when a CO ₂ laser is used as the laser light source 3, a gold (Au) -coated Si mirror can be used, and when an Ar laser is used, a dielectric-coated quartz mirror can be used. You can Also, the motor 6
For this, an AC motor or the like that rotates smoothly and has little vibration is used, and the number of rotations is preferably 500 rpm or more. Further, as for the attachment angle θ, any angle can be selected according to the required beam profile.

Next, the operation of the semiconductor material manufacturing apparatus having such a configuration will be described. A laser beam BM ₀ from the laser light source 3 passes through a rotary mirror 5 of a rotary mirror device 4 to a polycrystalline or amorphous semiconductor material (for example, a polycrystalline or amorphous silicon thin film) 2 on an insulating substrate 1. Irradiate. By scanning the semiconductor material 2 in the direction of arrow A, for example, the polycrystalline or amorphous semiconductor material 2 is removed as shown in FIG.
As indicated by reference numeral 10 in (a), it is possible to continuously melt and recrystallize.

At this time, the laser light source 3 which emits a single (single single mode) laser beam is used, and the laser light source 3 has a beam profile as shown in FIGS. 2 (a) and 2 (b). When a single laser beam BM ₀ having a beam intensity is emitted, this laser beam BM ₀ is inclined with respect to the rotation axis 7 of the rotary mirror 5 by an inclination angle θ.
It can be rotated with a radius according to. In this case, the beam profile of the laser beam on the semiconductor material 2 becomes a stable donut shape having a predetermined diameter D, as shown in FIG. It becomes a stable bimodal type as shown in FIG. Further, by changing the tilt angle θ of the rotating mirror 5, the diameter D of the donut shape can be changed arbitrarily.
The bimodal beam intensity distribution can be easily controlled.

As described above, in the present invention, the rotary mirror 5 is provided with a predetermined tilt angle θ with respect to the rotary shaft 7 of the motor 6.
Since it is attached, the bimodal beam intensity distribution can be stably maintained with good controllability, whereby a single crystal semiconductor material (for example, a single crystal silicon thin film) can be stably obtained. it can.

As the laser light source 3, a synthetic laser beam in which a plurality of laser beams are superposed on the same straight line is used. The laser light source 3 has a beam profile and beam intensity as shown in FIGS. 4 (a) and 4 (b). When a laser beam BM _{0 that} is linearly combined with is emitted, the individual beams are vibrated by the rotation of the rotating mirror 5 to obtain the beam intensity as shown in FIG. 5 on the semiconductor material 2. be able to. That is, by vibrating the individual beams of the combined laser beam BM ₀ by the rotation of the rotating mirror 5, the intensity distribution of the combined beam can be made sufficiently uniform, and uniform melting with high throughput in a wide region can be achieved. Recrystallization can be performed. In other words, when a plurality of laser beams superposed in the same straight line are irradiated through the rotating mirror 5 of the present invention, this can be used as a linear heat source with uniform intensity.

[0014]

Embodiment 1 FIG. 6 is a block diagram of the apparatus of Embodiment 1. As shown in FIG. In Example 1,
As the laser light source 3, an output of 10 W and a beam diameter of 2 mm A
An Ar laser that emits an r laser beam is used, and the rotating mirror device 4 is arranged so that the Ar laser beam from the laser light source 3 enters the rotating shaft 7 of the motor 6 at an angle of 45 °.
The rotary mirror 5 was attached to the rotary shaft 7 of the motor 6 at an angle θ of 0.1 ° with respect to the right angle.

By constructing the apparatus as described above and rotating the rotary mirror 5 by the motor 6 at 1000 rpm while the position of the sample 30 is 500 mm away from the center of the rotary mirror 5, the beam profile on the sample 30 and The beam intensities were as shown in FIGS. 7 (a) and 7 (b), respectively. That is, it was a donut type having a strength peak diameter D of 3.5 mm. As the sample 30, a quartz substrate 31 having a thickness of 1.6 mm and a thickness of 3000
Using a polycrystalline silicon film 32 of Å and a surface protective film (SiO ₂ film) 33 having a thickness of 1.5 μm formed in this order by the CVD method, while irradiating the laser beam having the above donut-shaped intensity distribution, As a result of scanning at a speed of 0.1 mm / sec, the silicon film 32 was melted and recrystallized over a width of 5 mm, and the central portion 34 having a width of 1.5 mm could be single-crystallized.

Example 2 In Example 2, the laser light source 3 having the structure shown in FIG. 8 was used. That is, output 10 W, beam diameter 9 mm
Place a CO ₂ laser light source 1101 for emitting a laser beam to a total of 12 straight lines on each CO ₂ laser light source 1101
Twelve laser beams B _{1 to} B ₁₂ emitted as parallel beams from each other are combined by a beam combining optical system 1103 including a mirror and a beam combiner, and a linear beam with a center distance d between the beams is 4.5 mm. It was made to synthesize BM ₀ . The intensity distribution of the combined beam at this time is actually as shown in FIG. 9 due to subtle differences in the individual beam profiles of the 12 beams, and the intensity distribution of the combined beam is uniform. In fact, it is difficult to make the intensity distribution of the synthetic beam uniform in the laser light source 3.
Such combined beam BM ₀ is incident on the rotary mirror 5 of the rotary mirror device 4 as shown in FIG. The incident angle of the combined beam BM ₀ is the same as that in the first embodiment.
The rotary mirror 5 is mounted at an angle θ of 0.1 ° with respect to the rotary shaft 7. The position of the sample 30 was 100 mm away from the center of the rotating mirror 5. In this state, rotate the rotary mirror 5 to 10
When rotated at 00 rpm, the intensity distribution of the synthetic beam at the sample position disappears due to the vibration of the entire beam,
As shown in FIG. 11, it became almost uniform. Sample 30
As in Example 1, a quartz substrate having a thickness of 1.6 mm and a polycrystalline silicon film having a thickness of 3000 Å and a thickness of 1.5
A surface protective film (SiO ₂ film) having a thickness of μm formed in this order by a CVD method is used, and while irradiating the linear laser beam having the uniform intensity distribution, the beam has a velocity of 0.1 mm / sec in the orthogonal direction. As a result of scanning with, it was possible to uniformly melt and recrystallize polycrystalline silicon over a width of 45 mm.

[0017]

As described above, according to the present invention, a polycrystalline or amorphous semiconductor material is provided through a rotary reflecting mirror mounted with a laser beam at an inclination angle θ with respect to a predetermined rotation axis. Since it is configured to irradiate the single crystal semiconductor material, the bimodal beam intensity distribution can be stably maintained with good controllability, and a single crystal semiconductor material can be stably obtained. That is, when a single single-mode laser beam is used as the laser beam, the beam can be rotated with an arbitrary radius, so that a stable donut-shaped laser beam with an arbitrary size can be obtained. By irradiating and scanning a polycrystalline or amorphous silicon thin film on an insulating material with this, single crystal silicon can be stably obtained. Also, when multiple linearly combined laser beams are used, the intensity distribution of the combined beams can be made sufficiently uniform by vibrating the individual beams by rotating the mirrors, and the throughput for a wide area can be improved. A uniform and high melt recrystallization can be performed.

[Brief description of drawings]

1A and 1B are diagrams showing a configuration example of a semiconductor material manufacturing apparatus according to the present invention.

2A and 2B are diagrams respectively showing a beam profile and a beam intensity of a single laser beam emitted from a laser light source.

3A and 3B are laser beams on a semiconductor material when the laser beam having the beam profile and the beam intensity shown in FIGS. 2A and 2B is incident on the semiconductor material through a rotating mirror. 3 is a diagram showing a beam profile and a beam intensity of FIG.

4 (a) and 4 (b) are diagrams respectively showing a beam profile and a beam intensity of a linear laser beam emitted from a laser light source.

FIG. 5 is a diagram showing the beam intensity of the laser beam on the semiconductor material when the laser beam having the beam profile and the beam intensity shown in FIGS. 2A and 2B is incident on the semiconductor material through the rotating mirror. .

6 is a configuration diagram of a semiconductor material manufacturing apparatus of Example 1. FIG.

7 (a) and 7 (b) are diagrams showing a beam profile and a beam intensity of a laser beam on a semiconductor material in the apparatus of FIG. 6, respectively.

FIG. 8 is a configuration diagram of a laser light source of a semiconductor material manufacturing apparatus according to a second embodiment.

9 is a diagram showing an intensity distribution of a combined beam emitted from the laser light source of FIG.

FIG. 10 is a configuration diagram of a rotating mirror device of a semiconductor material manufacturing apparatus according to a second embodiment.

11 is a diagram showing the beam intensity of the laser beam on the semiconductor material when the linear laser beam having the beam intensity shown in FIG. 9 is incident on the semiconductor material via the rotating mirror.

12A and 12B are views for explaining a melting and recrystallization method of a conventional semiconductor material manufacturing apparatus.

FIG. 13 is a diagram showing a Gaussian laser beam intensity distribution.

FIG. 14 is a diagram showing how recrystallized silicon becomes a polycrystal.

FIG. 15 is a diagram showing a bimodal laser beam intensity distribution.

FIG. 16 is a diagram for explaining a conventional method for forming a wide heating region.

FIG. 17 is a diagram for explaining a conventional method of forming a wide heating region.

[Explanation of symbols]

 1 Insulating Substrate 2 Semiconductor Material 3 Laser Light Source 4 Rotating Mirror Device 5 Rotating Mirror 6 Motor 7 Motor Rotating Shaft

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Dai ▲ Taka ▼ Goichi Goichi Takahata Kumanodou, Natori City, Miyagi Prefecture 10 Rico-Applied Electronics Research Institute Co., Ltd. (72) Inventor Takeshi Hino Miyagi Prefecture 10 Rico, 5th place on the side of Takadate Kumano-do, Natori City

Claims (3)

[Claims] 1. A polycrystalline or amorphous semiconductor material is melted by irradiating a laser beam emitted from a laser light source,
In a semiconductor material manufacturing apparatus for recrystallizing, a laser beam from a laser light source is irradiated onto the semiconductor material via a rotary reflecting mirror that rotates around a predetermined rotation axis, and the rotary reflecting mirror is The semiconductor material manufacturing apparatus is characterized in that the reflecting surface is attached at a predetermined angle θ from a right angle with respect to the rotation axis. 2. The semiconductor material manufacturing apparatus according to claim 1, wherein the tilt angle θ of the rotary reflecting mirror with respect to the rotation axis is:
A semiconductor material manufacturing apparatus characterized in that it can be set at an arbitrary angle. 3. The semiconductor material manufacturing apparatus according to claim 1, wherein the laser beam emitted from the laser light source is
Is it a single single mode laser beam,
Alternatively, the semiconductor material manufacturing apparatus is a linear synthetic laser beam in which a plurality of laser beams are superposed on the same straight line.