JP2006247696A - Laser heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser heating apparatus capable of heating a semiconductor substrate or the like uniformly at high temperature. <P>SOLUTION: The apparatus is composed of a laser oscillator 3 which is formed by stacking a plurality of laser diode bars and an optical lens system 5 which is interposed between the laser oscillator and an object 4 to be heated. The optical lens system comprises collimator lenses 6 installed at the laser exit port of each laser diode bar in the fast axis direction of the laser oscillator 3, a convex lens 7 and a fly's eye lens 8 arranged in order toward the object to be heated. Parallel light beams from the collimator lenses are passed through the convex lens and the fly's eye lens and then, after converged, the beams are defocused and made to emit to the object 4 to be heated. In the slow axis direction of the laser oscillator 3, the laser beam from the laser exit port is shaped by a first diaphragm with the output angle unchanged and emitted to the object to be heated. Near the converging point of the optical lens system 5 in the fast axis direction of the laser oscillator, there is provided a second diaphragm 9 that transmits the laser beam. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser heating apparatus, and more particularly to a laser heating apparatus capable of uniformly heating a semiconductor substrate or the like at a high temperature.

Conventionally, a YAG laser or a carbon dioxide laser heating device is used to heat a semiconductor substrate or the like using a spot moving method, a linear beam irradiation method, a scanning method, or a high-power semiconductor laser heating device with a wide stripe width. It was heated (Patent Document 1).
JP-A-10-94892

  However, since both the spot moving method and the scanning method are methods in which a portion to be heated is scanned with a laser beam, the entire portion to be heated cannot be irradiated with the laser beam at a time, resulting in a reduction in processing efficiency. In addition, the linear beam irradiation method and the high-power semiconductor laser heating apparatus with a wide stripe width have the disadvantage that they can only be heated in a linear shape and a large area cannot be heated at a desired temperature distribution at a time. It was.

  In addition, when a laser beam is irradiated perpendicularly to an object to be heated such as a semiconductor substrate, the semiconductor laser element may be damaged by the reflected light from the object to be heated.

  Further, the radiant heat generated by the heated object generated by the laser light returns to the laser oscillator side, shortening the life of the semiconductor laser element, and the long-term stability performance is inferior.

  Further, the conventional laser heating apparatus has a disadvantage that the irradiation area of the object to be heated in the fast axis direction and the irradiation area of the object to be heated in the slow axis direction are greatly different.

  The present invention eliminates the above-mentioned drawbacks.

  The laser heating apparatus of the present invention includes a laser oscillator formed by laminating a plurality of laser diode bars, and an optical lens system interposed between the laser oscillator and an object to be heated. In the direction of the fast axis of the oscillator, a collimating lens provided at the laser exit of each laser diode bar, a convex lens and a fly-eye lens arranged in order toward the object to be heated, and parallel from the collimating lens. The light is focused after passing through the convex lens and fly-eye lens and then defocused to irradiate the object to be heated. In the slow axis direction of the laser oscillator, the laser light remains at the exit angle emitted from the laser exit. The laser beam emitted from the laser diode bar is kept at the emission angle by the first aperture. Shape and wherein the allowed to irradiate the object to be heated.

  In the laser heating apparatus of the present invention, in the fast axis direction of the laser oscillator, one or a plurality of convex lenses for reducing the defocus amount of the focused laser beam or making it a parallel beam It is characterized by irradiating an object to be heated through

  In the laser heating apparatus of the present invention, the laser beam emitted from the laser exit is further spread by a concave lens in the slow axis direction of the laser oscillator.

  Further, in the slow axis direction of the laser oscillator, after being shaped by the first diaphragm, the object to be heated is irradiated through a convex lens for making parallel light.

  The opening area of the first diaphragm aperture on the laser oscillator side is larger than the heated object side.

  The laser heating apparatus of the present invention has a second diaphragm for shaping laser light in the slow axis direction in the vicinity of the condensing point of the optical lens system in the fast axis direction of the laser oscillator. The aperture area of the aperture opening on the heated portion side is larger than that on the laser oscillator side.

  Further, the second diaphragm is formed of a material having good thermal conductivity.

  The surface of the second diaphragm on the side to be heated is coated with ceramic.

  The optical lens system and the second stop near the condensing point are provided in the same lens holder, and the laser light emitted from the lens holder portion is used as defocused light.

  In the laser heating apparatus of the present invention, since the laser beam in the fast axis direction is passed through the fly-eye lens after passing through the convex lens, the laser beam can be homogenized.

  In the laser heating apparatus of the present invention, since the object to be heated is irradiated with defocused light, the object to be heated can be uniformly heated in a short time with a single irradiation.

  The second aperture shapes the laser beam in the slow axis direction, reduces the return of reflected light from the object to be heated to the laser oscillator side, and emits radiation light generated by heating the object to be heated. The incidence on the oscillator side can be reduced, the laser element can be prevented from being damaged, and the life and performance of the semiconductor laser can be remarkably improved.

  Further, in the laser heating apparatus of the present invention, a convex lens is provided at a position where a necessary irradiation area is obtained in both the fast axis direction and the slow axis direction, and parallel light is used, so that the laser light is not wasted and is to be heated. Since it can irradiate, there is little heating of the extra part of an apparatus and a heat loss is lost.

  Normally, the light at the condensing point passes through without being constricted, but since the second stop is provided near the condensing point of the optical lens system in the fast axis direction, laser light can be transmitted as necessary. It can also be shaped into the required shape.

  In addition, since the lens and the diaphragm are provided in the same lens holder, it is possible to reduce the size.

  Also, by increasing the number of laser diode bars, the laser output can be increased and the object to be heated can be heated over a wide range, the output of each laser diode can be made different, and the thickness of the heater sink plate can be adjusted appropriately. The object to be heated can be heated with a desired temperature distribution by changing the interval of the laser diode bars to be stacked differently or by arranging the laser diode bars in a plurality of rows instead of one row.

  In addition, since convex lenses are provided in both the fast axis direction and the slow axis direction at the necessary area from the defocused light to obtain parallel light, the irradiation area other than the object to be heated 4 is reduced, so that heat loss can be reduced.

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

  As shown in FIG. 1, the laser heating apparatus according to the present invention includes, for example, a heat sink composed of a copper plate having a thickness of 1 mm to 3 mm and a continuous oscillation (CW) laser diode bar 1 having a thickness of 0.1 mm to 3 mm and an output of 40 W to 100 W. A laser oscillator 3 composed of a laser stack with an output of 0.8 kW to 2 kW composed of 20 sheets sandwiched by plates 2 and an optical lens system 5 interposed between the laser oscillator 3 and the object to be heated 4. Constitute.

  Further, as shown in FIG. 2, in the fast axis direction of the laser oscillator, the collimating lens 6 provided with the optical lens system 5 at the laser exit of each laser diode bar 1 and the laser from the laser oscillator 3 are irradiated. A convex lens 7, a fly-eye lens 8, and a second aperture 9, which are sequentially arranged between the heated object 4 such as a silicon substrate having a diameter of 2 inches and the collimating lens 6 toward the heated object 4. After the laser beam made parallel by the collimator lens 6 passes through the convex lens 7 and the fly eye lens 8 makes the laser distribution between the pitches of the adjacent laser diode bars 1 uniform, The laser beam is condensed, defocused, and irradiated on the object 4 to be heated.

  Further, as shown in FIG. 3, in the slow axis direction of the laser oscillator, the laser light emitted from the laser diode bar 1 is arranged on the laser oscillator side from the second diaphragm 9 with an emission angle (about 10 degrees). The shape is adjusted by the first diaphragm 10 and the second diaphragm 9, and the object to be heated 4 is irradiated and heated.

  Note that the opening 11 of the first diaphragm 10 has an opening area that gradually increases from the heated object side toward the oscillator side as shown in FIG. 4 in order to improve shaping of the laser beam in the slow axis direction. To make up.

  Further, as shown in FIG. 5, the opening 12 of the second diaphragm 9 is configured such that the opening area gradually increases from the laser oscillator side toward the heated object side. The second diaphragm 9 is made of a material having good thermal conductivity such as an aluminum plate in order to shape the slow-axis laser light and diffuse the reflected light and radiant light from the heated object 4 widely. The surface of the heated object is preferably ceramic coated to form minute irregularities.

  The opening 12 of the second diaphragm 9 is preferably as small as possible and provided at the fast axis side condensing point position.

  In the laser heating apparatus of the present invention, the second aperture 9 shapes the slow-axis side laser light and reduces the reflected light from the object to be heated 4 to the laser oscillator 3 side. It is possible to reduce the incidence of radiant light emitted by heating of the heated object 4 on the laser oscillator 3 side, to prevent damage to the laser element, and to significantly improve the life and performance of the semiconductor laser. .

  The collimating lens 6, the convex lens 7, the fly-eye lens 8, the first diaphragm 10, and the second diaphragm 9 near the condensing point are provided in a cylindrical lens holder (not shown), and the laser oscillator By converging the fast axis in the lens holder and integrating the lens holder with the laser oscillator 3, the fast axis and the slow axis of the light emitted from the lens holder become defocused light, respectively. As a result of irradiating the object to be heated 4 with light, the object to be heated can be uniformly heated to, for example, 1000 degrees in a short time, and a uniform and good oxide film can be formed on the object to be heated. Can do.

  Further, since the fly-eye lens is provided after the convex lens on the fast axis of the laser oscillator, the laser light can be made uniform.

  Further, since the second diaphragm 9 is provided in the vicinity of the condensing point, the laser beam can be shaped into a necessary shape.

  In order to make the irradiation region of the object to be heated 4 in the fast axis direction substantially coincide with that in the slow axis direction, in the second embodiment of the present invention, as shown in FIG. In the direction, one or a plurality of convex lenses 13 are provided between the second diaphragm 9 and the object 4 to be heated, and the focused laser light passes through the convex lens 13 and is defocused to a smaller extent to be heated. The object 4 is irradiated.

  Further, as shown in FIG. 7, a concave lens 14 is provided between the laser oscillator 3 and the first diaphragm 10 in the slow axis direction of the laser oscillator 3, and the laser light emitted from the laser oscillator 3 is After spreading through the concave lens 14, the shape of the laser beam is adjusted by the first diaphragm 10 and the second diaphragm 9, and the object to be heated 4 is irradiated and heated.

  In this way, the irradiation area of the article to be heated 4 can be made substantially square.

  Further, the convex lens 13 and the concave lens 14 may be provided in the lens holder.

  In the third embodiment of the present invention, as shown in FIG. 8, the fast axis of the laser oscillator 3 is used so that the laser beam does not leak to a portion other than the irradiation region of the article 4 to be heated in the fast axis direction. In the direction, one or a plurality of convex lenses 15 are provided in the necessary region range from the defocused laser light with the range narrowed by the convex lens 13 so as to be collimated so as to irradiate the object to be heated 4. .

  As shown in FIG. 9, in the slow axis direction of the laser oscillator 3, the laser light is shaped by the second diaphragm 9, and then a convex lens 16 is provided at a position in a region range where the laser light is necessary. Light is used to irradiate the object 4 to be heated. If it does in this way, the irradiation light of the to-be-heated material 4 can be made into the parallel light of a laser, and parts other than a to-be-heated material are not heated by the spread of a laser beam, and heat loss can be reduced. it can.

  The fast axis convex lens 15 and the slow axis convex lens 16 are positioned by a lens holder different from the lens holder.

It is a perspective view of the laser oscillator of the laser heating apparatus of this invention. It is a fast-axis direction explanatory drawing of the laser heating apparatus of this invention. It is slow-axis direction explanatory drawing of the laser heating apparatus of this invention. It is a vertical side view of the 1st aperture_diaphragm | restriction shown in FIG. It is a vertical side view of the 2nd aperture_diaphragm | restriction shown in FIG. It is a fast-axis direction explanatory drawing of 2nd Example of the laser heating apparatus of this invention. It is slow axis direction explanatory drawing of 2nd Example of the laser heating apparatus of this invention. It is a fast-axis direction explanatory drawing of 3rd Example of the laser heating apparatus of this invention. It is slow axis direction explanatory drawing of 3rd Example of the laser heating apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser diode bar 2 Heat sink plate 3 Laser oscillator 4 Heated object 5 Optical lens system 6 Collimating lens 7 Convex lens 8 Fly eye lens 9 2nd aperture 10 1st aperture 11 Opening 12 Opening 13 Convex lens 14 Concave lens 15 Convex lens 16 Concave lens

Claims (11)

  A laser oscillator formed by laminating a plurality of laser diode bars, and an optical lens system interposed between the laser oscillator and an object to be heated. It consists of a collimating lens provided at the laser exit of the laser diode bar, a convex lens and a fly-eye lens arranged in order toward the object to be heated, and parallel light emitted from the collimating lens is converted into the convex lens, fly-eye. After passing through the lens, the light is condensed and then defocused to irradiate the object to be heated. In the slow axis direction of the laser oscillator, the laser beam is composed of a first diaphragm that squeezes the laser light at the exit angle from the laser exit. The laser beam emitted from the laser diode bar is shaped by the first diaphragm at the emission angle to irradiate the object to be heated. Laser heating apparatus, characterized in that.   2. The object to be heated is irradiated with the focused laser beam through one or a plurality of convex lenses for reducing the defocus amount in the fast axis direction of the laser oscillator. The laser heating apparatus as described.   2. The laser heating according to claim 1, wherein in the fast axis direction of the laser oscillator, the object to be heated is irradiated through one or a plurality of convex lenses for making the condensed laser light into parallel light. apparatus.   4. The laser heating apparatus according to claim 1, wherein the laser beam emitted from the laser exit is further expanded by a concave lens in the slow axis direction of the laser oscillator.   5. The object to be heated is irradiated in a slow axis direction of the laser oscillator through a convex lens for making parallel light after shaping by the first diaphragm. Laser heating device.   6. The laser heating apparatus according to claim 1, wherein an opening area on the laser oscillator side of an opening of the first diaphragm is larger than that on the object to be heated.   2. A second stop for shaping laser light in the slow axis direction in the vicinity of the condensing point of the optical lens system in the fast axis direction of the laser oscillator. Or the laser heating apparatus of 6.   8. The laser heating apparatus according to claim 7, wherein an opening area on the heated portion side of the opening portion of the second diaphragm is larger than that on the laser oscillator side.   9. The laser heating apparatus according to claim 7, wherein the second diaphragm is made of a material having good thermal conductivity.   10. The laser heating apparatus according to claim 7, 8 or 9, wherein the surface of the second diaphragm on the side to be heated is coated with ceramic.   The optical lens system and a second stop near the condensing point are provided in the same lens holder, and the laser beam emitted from the lens holder portion is defocused light. The laser heating apparatus according to 3, 4, 5, 6, 7, 8, 9 or 10.

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