JP2002050583A - Substrate-heating method and substrate-heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide substrate-heating method/substrate-heating device, which use laser beams for improving the temperature distribution of a substrate to be uniform. SOLUTION: For scanning and irradiating the substrate 6 with the laser beam L from a laser beam generating source 2 via a first reflection device 3 and a second reflection device 4, a radiation thermometer 10 detects the intraface temperature distribution of the substrate and the output is supplied to a controller 11. Thus, the intraface temperature distribution difference of the substrate 6 is measured. Control signals are supplied to the galvanometers 3B and 4B of the respective reflection devices 3 and 4 from the controller 11, so that the temperature distribution difference becomes zero. A prescribed area on the substrate 6, which is not in the prescribed temperature, is heated on focus and the whole area of the substrate 6 is maintained to the prescribed temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate heating method and a substrate heating apparatus for heating a substrate to be processed to a predetermined temperature by irradiating the substrate with laser light.

[0002]

2. Description of the Related Art For example, in order to continuously oscillate a semiconductor laser at room temperature, it is necessary to confine injected carriers and generated light in an active region. In the step of forming the active region in the semiconductor laser manufacturing process, a vapor phase growth method of growing a film by a chemical reaction between a substrate gas heated to a predetermined temperature and a source gas is generally adopted.

Conventionally employed methods for heating a substrate include lamp heating such as an infrared lamp, resistance heating such as a heater, and RF (high frequency) heating. In these heating methods, a semiconductor substrate is heated by disposing a heating source such as a lamp, a resistance heating wire, or an RF coil near the semiconductor substrate.

[0004]

However, in any of the above-mentioned heating methods, it is presently difficult to achieve a uniform in-plane temperature distribution. This is based on the geometrical positional relationship between the heating source and the substrate to be processed, such that the portion closest to the heating source is easily heated. Also,
Temperature distribution in the substrate surface also occurs depending on the flow rate, type, and set temperature of the gas flowing into the furnace. For this reason, it is very difficult to ensure the crystallinity, composition, and carrier concentration of the formed film uniformly in the plane, and there is a problem that the product characteristics such as the oscillation laser wavelength vary.

[0005] In particular, the difference in the temperature distribution of the substrate is more likely to occur as the heating temperature is higher. If the substrate has a remarkable temperature distribution, the substrate will be warped or broken (cracked). Further, this difference in the temperature distribution of the substrate is a factor that hinders an increase in the size of the substrate.

On the other hand, Japanese Patent No. 2548961,
As described in each publication of 145554, there is known a laser heat treatment technique in which a substrate to be processed is subjected to scanning irradiation with laser light to perform a predetermined heat treatment. However, if this technique is simply used, a temperature distribution difference occurs in the substrate surface due to the flow of the supplied gas or the like, and the in-plane temperature distribution cannot be made uniform.

The present invention has been made in view of the above problems, and has as its object to provide a substrate heating method and a substrate heating apparatus using a laser beam, which can improve the uniformity of the temperature distribution of the substrate.

[0008]

In order to solve the above problems, a substrate heating method according to the present invention is a heating method for heating a substrate to be processed by scanning and irradiating a laser beam.
It is characterized in that the temperature distribution in the plane of the substrate to be processed is detected, and the scanning of the laser beam is controlled so that the temperature distribution difference becomes zero.

Since the in-plane temperature distribution during the heat treatment of the substrate is generated by the set temperature, the gas flow rate, and the like, the present invention employs laser light as a heating source and sets the laser light so that the in-plane temperature distribution difference becomes zero. Scanning control is performed. The scanning control of the laser light means that the scanning speed and the scanning sequence are adjusted in accordance with the in-plane temperature distribution state, and thus, the in-plane temperature distribution can be made uniform.

In order to solve the above problems, a substrate heating apparatus according to the present invention includes a laser light generating source, and a rotating shaft that receives the laser light emitted from the laser light generating source and can be driven to reverse. A first reflection means, and a rotation axis in a direction intersecting the rotation axis of the first reflection means, and the laser light reflected by the first reflection means is reflected toward the substrate to be processed. A second reflection means, a temperature distribution detection means for detecting a temperature distribution of the substrate to be processed, and a first reflection means and / or a second reflection means based on a detection output of the temperature distribution detection means. Control means for controlling driving.

The laser light emitted from the laser light source is applied to the substrate to be processed via the first reflecting means and the second reflecting means. The laser light applied to the substrate to be processed is scanned in one direction in the plane while being scanned in a direction intersecting the one direction, whereby the entire area in the plane of the substrate is heated to a predetermined temperature. Then, based on the in-plane temperature distribution of the substrate to be processed detected by the temperature distribution detecting means, such that the in-plane temperature distribution difference becomes zero,
The driving of the first reflection unit and / or the second reflection unit is controlled via the control unit.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an outline of a substrate heating apparatus according to an embodiment of the present invention. The substrate heating device 1 includes a laser light source 2, a first reflection device 3, and a second reflection device 4. In the present embodiment, an excimer laser is used as the laser light L emitted from the laser light
Each of the second reflecting devices 3 and 4 is constituted by a combination of reflecting mirrors 3A and 4A and galvanometers 3B and 4B.

The first reflecting device 3 has its reflecting mirror 3 A opposed to the exit of the laser light source 2. The reflecting mirror 3A is configured to be able to be inverted by a galvanometer 3B in a direction indicated by an arrow x, and scan the laser light L emitted from the laser light source 1 toward the reflecting mirror 4A of the second reflecting device 4. Is done. On the other hand, the reflecting mirror 4A of the second reflecting device can be inverted and driven in the direction indicated by the arrow y by the galvanometer 4B, and directs the laser light L from the first reflecting device 3 toward the substrate 6 arranged in the processing furnace 5. Scanning irradiation.

Each of these reflecting mirrors 3A, 4A has a rotation axis in a direction orthogonal to each other, and scans a laser beam L on the substrate 6 in the left and right direction in the drawing by one of the reflecting mirrors 3A.
The other reflector 4A scans the substrate 6 with the laser beam L in the direction perpendicular to the plane of the drawing. Thus, as shown in FIG. 2, the substrate 6 is irradiated with the laser beam L in the X direction while being scanned and irradiated in the Y direction.
Heat the entire area.

The furnace wall 7 of the processing furnace 5 is made of transparent quartz arranged horizontally, and a carrier gas 9 containing a raw material is applied to a substrate (for example, a GaAs substrate in this embodiment) 6 housed therein. Is provided. Outside the processing furnace 5, a radiation thermometer 10 is arranged on the surface side of the substrate 6. The radiation thermometer 10 includes a susceptor (a transparent body in the present embodiment) 8 that supports the furnace wall 7 and the substrate 6.
The temperature distribution in the plane of the substrate 6 heated by the laser light L irradiated through the substrate 6 is detected. The output of the radiation thermometer 10 is supplied to a control device 11. The control device 11 is configured by a computer, measures a temperature distribution difference at each point of the substrate 6 based on the output of the radiation thermometer 10, and controls the first reflection device 3 and / or the first reflection device 3 so that the temperature distribution difference becomes zero. A control signal for controlling the driving of each of the galvanometers 3B and 4B of the two-reflector 4 is transmitted.

Next, the operation of the present embodiment will be described.

The reflecting mirrors 3A of the first and second reflecting devices 3 and 4,
4A is driven in reverse in the directions of the arrows x and y at a predetermined frequency by driving the galvanometers 3B and 4B, respectively. The laser light L emitted from the laser light source 2 is reflected by the first reflection device 3 and the second reflection device 4 and is irradiated on the back surface of the substrate 6 in the processing furnace 5 by scanning. That is, as shown in FIG. 2, the entire area of the substrate 6 is heated to and maintained at a predetermined temperature while the laser beam L is irradiated on the substrate 6 by scanning in the X and Y directions.

The in-plane temperature of the substrate 6 is monitored by a radiation thermometer 10. The control device 11 includes the radiation thermometer 1
The in-plane temperature distribution of the substrate 6 is measured based on the output of 0.
In the present embodiment, as shown in FIG. 3, the inside of the surface of the substrate 6 is virtually formed by a plurality of divided areas D, and each of these divided areas D
Each time, the temperature is obtained and the entire temperature distribution is measured. Then, the divided area D (X, Y) not at the predetermined temperature
Is coordinated, the laser beam L is radiated mainly to the area, and the control device 11 adjusts the turning angles of the reflecting mirrors 3A and 4A so that the temperature distribution difference becomes zero as a whole.
Supplies control signals to the galvanometers 3B and 4B of the reflection devices 3 and 4, respectively. Note that the size of the divided area D is
In the present embodiment, the size is equal to the spot diameter of the laser beam L.

In the present embodiment, the carrier gas 9
With respect to the flow, the temperature of the region of the substrate 6 located on the upstream side tends to be lower than that of other regions. Therefore, as the scanning control, the predetermined temperature is maintained over the entire area of the substrate 6 by reducing the scanning speed of the laser light L or increasing the frequency of irradiation of the laser light L in the area as compared with the other areas. I do.

In this embodiment, since the galvanometers 3B and 4B are used for the scanning mechanism of the laser beam L, high responsiveness to the control signal from the control device 11 is obtained, and high accuracy In addition, the laser light L can be irradiated in a pinpoint manner. Further, since the radiation thermometer 10 is employed as the temperature distribution detecting means of the substrate 6, the in-plane temperature of the substrate 6 can be detected from outside the processing furnace 5.

As described above, the laser beam L
Is scanned and irradiated in the X and Y directions to heat and maintain the substrate 6 at a predetermined temperature, while the output of the in-plane temperature distribution of the substrate 6 is fed back to the scanning drive mechanism of the laser light L, so that the temperature of the substrate 6 is increased. It is possible to make the distribution almost completely uniform. This prevents the substrate 6 from being warped or cracked due to a difference in temperature distribution, and can form an element as designed over the entire area of the substrate 6. In this embodiment, in particular, characteristics such as the oscillation laser wavelength are reduced. A semiconductor laser without variation can be obtained.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the configuration in which the radiation thermometer 10 is adopted as the temperature distribution detecting means and the radiation thermometer 10 is arranged on the surface side of the substrate 6 has been described, but the substrate 6 is supported instead. The temperature distribution of the susceptor 8 can be detected as the temperature distribution of the substrate 6 by disposing it on the susceptor 8 side. This configuration example is particularly effective when the furnace wall 7 facing the substrate 6 is devitrified due to adhesion of foreign matter. Further, an infrared camera can be used instead of the radiation thermometer. In this case, the temperature distribution difference can be obtained by directly performing image processing on the imaged substrate.

In the above embodiment, the first and second
The reflecting devices 3 and 4 are combined with the reflecting mirrors 3A and 4A and the galvanometer 3.
Although a combination of B and 4B is used, a polygon mirror (polyhedral mirror) may be used instead.

Further, in the above embodiment, the substrate 6 is fixedly arranged in the furnace, but the heat treatment is performed while rotating the substrate around its center (while rotating the susceptor 8). For example, the portion where the carrier gas 9 hits can be equalized in the substrate plane to reduce the temperature distribution difference.

In the above embodiment, the semiconductor laser manufacturing process has been described as an example. However, the present invention is not limited to this, and the substrate temperature may be set to a predetermined temperature for other substrates such as a silicon substrate. The present invention can also be effectively applied to various processes (thermal oxidation, thermal diffusion, thermal CVD) performed by heating at a high temperature.

[0028]

As described above, according to the present invention, the following effects can be obtained.

That is, according to the substrate heating method of the first aspect, the in-plane temperature distribution of the substrate to be processed can be made almost completely uniform, thereby reducing the variation in the characteristics of the elements to be formed. In addition to this, it is possible to prevent damage such as warping or cracking of the substrate and sufficiently cope with an increase in the size of the substrate.

According to the second aspect, a region having a temperature distribution difference can be quickly and accurately specified, and the scanning accuracy of laser light can be improved.

According to the third aspect of the present invention, the substrate to be processed can be uniformly heated based on the output of the temperature distribution detecting means, so that the substrate can be heated. In addition, it is possible to reduce the variation of the substrate, prevent the substrate from being damaged such as warpage or crack, and sufficiently cope with an increase in the size of the substrate.

According to the fourth aspect, the area to be heated can be irradiated with laser light with high responsiveness and high accuracy and pinpoint.

According to the fifth aspect, the installation location of the temperature distribution detecting means can be set with a high degree of freedom.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of a substrate heating apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a trajectory of a laser beam on a wafer according to an embodiment of the present invention.

FIG. 3 is a plan view of a wafer for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate heating device, 2 ... Laser light source, 3 ... 1st reflection device (1st reflection means), 3A, 4A ... Reflection mirror, 3B,
4B: galvanometer, 4: second reflecting device (second reflecting means), 5: processing furnace, 6: substrate (substrate to be processed), 8: susceptor, 10: radiation thermometer (temperature distribution detecting means), 11
... Control device (control means).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/31 C21D 1/09 M // C21D 1/09 H01L 21/302 B

Claims (5)

[Claims] 1. A substrate heating method for heating a substrate to be processed by scanning and irradiating a laser beam to the substrate, wherein a temperature distribution in a plane of the substrate to be processed is detected, and the laser distribution is set so that a temperature distribution difference becomes zero. A method for heating a substrate, comprising controlling scanning of light. 2. The substrate heating method according to claim 1, wherein the detection of the temperature distribution in the plane is performed based on the temperatures of individual regions obtained by dividing the plane into a plurality. 3. A laser light generating source, a first reflecting means having a rotation axis capable of receiving and invertingly driving the laser light emitted from the laser light generating source, and a rotation of the first reflecting means. A second reflecting unit having a rotation axis in a direction intersecting the moving axis, and reflecting the laser light reflected by the first reflecting unit toward the substrate to be processed; and a temperature of the substrate to be processed. Temperature distribution detecting means for detecting a distribution; and
And / or control means for controlling the driving of the second reflecting means. 4. The substrate heating apparatus according to claim 3, wherein said first and second reflecting means comprise a galvanometer and a reflecting mirror. 5. The substrate heating apparatus according to claim 3, wherein said temperature distribution detecting means is a radiation thermometer.