JP2014199889A - Light exposure head and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set an outgoing direction of a laser beam to an arbitrary direction with respect to a substrate when a plurality of semiconductor laser elements are formed on the substrate, and to perform effective cooling of a light-emitting layer.SOLUTION: A light exposure head 1 comprises: one semiconductor substrate (a substrate 10); a plurality of semiconductor laser element parts 2, which uses the substrate 10 as a common substrate, each having a light-emitting layer 2A along a surface of the substrate 10, and a pair of resonator end surfaces 20 vertical to the surface; a recessed groove part 3 formed between the resonator end surfaces 20 of adjacent semiconductor laser element parts 2; and a reflection surface 4 facing a light emission surface of the semiconductor laser element parts 2, in the recessed groove part 3, and reflecting a laser beam Lb emitted from the light emission surface to the substrate 10 side. An exposed surface is irradiated with the laser beam Lb via the substrate 10.

Description

  The present invention relates to an exposure head using a semiconductor laser as a light source and a manufacturing method thereof.

  An exposure apparatus using a semiconductor laser as a light source is used for various pattern formations including circuit pattern formation and image formation. Such an exposure apparatus has been made into a multi-beam in order to meet the demand for high-speed exposure processing, and is known to have a multi-beam semiconductor laser array head in which a plurality of semiconductor laser elements are arranged in parallel on a substrate. (See Patent Document 1 below).

  Further, in the conventional technique described in Patent Document 2 below, a semiconductor laser element layer in which a light emitting layer is formed on a main surface made of a (1-10-4) plane of an n-type GaN substrate, and the semiconductor laser element layer Reflective surface formed of a (000-1) plane that is formed in a region facing the light exit surface formed of the (1-101) plane formed at the end of the n-type substrate and extends at an inclination with respect to the main surface of the n-type GaN substrate. Further, there is shown a surface emitting laser array in which the semiconductor laser elements having the reflection surfaces described above are arranged side by side on one wafer (n-type GaN substrate).

JP 2005-353614 A JP 2009-170496 A

  In the prior art described in Patent Document 1, since a plurality of individually formed semiconductor laser elements are arranged on a substrate, it is difficult to ensure the positional accuracy of the arrangement pitch, and high-definition pattern formation is performed. However, if the arrangement pitch varies, there arises a problem that a high quality pattern cannot be formed. In addition, since there are individual differences in individually formed semiconductor laser elements, the prior art as described in Patent Document 1 makes uniform the output of a plurality of arranged semiconductor laser elements to improve the quality of pattern formation. There are problems that are difficult to raise.

  On the other hand, the prior art described in Patent Document 2 can form a plurality of semiconductor laser elements on one substrate and emit laser light in a direction intersecting with the substrate. By forming a plurality of semiconductor laser elements on one wafer, it becomes possible to form an array with high positional accuracy of the semiconductor lithography technique, so that it is possible to eliminate the deterioration in pattern formation quality due to variations in arrangement pitch. In addition, since a plurality of semiconductor laser elements formed simultaneously on one wafer can minimize individual differences, it is possible to improve the quality of pattern formation by making the outputs of a plurality of semiconductor laser elements arranged uniform. .

  However, since the conventional technique described in Patent Document 2 forms a reflecting surface inclined on the main surface by the crystal growth surface, there is a problem that the laser beam emission direction cannot be set to an arbitrary direction with respect to the substrate. In addition, since the laser beam is emitted to the light emitting layer side with respect to the substrate, it is not possible to provide a cooling means directly on the light emitting layer side, and it is necessary to cool through the substrate. There is a problem that the light emitting layer cannot be cooled.

  This invention makes it an example of a subject to cope with such a problem. In other words, in an exposure head that uses a semiconductor laser as the light source, by creating multiple semiconductor laser elements on a single substrate, it is possible to form an array with high positional accuracy and element formation with reduced individual differences, and variations in array pitch In addition to eliminating the deterioration of pattern formation quality caused by the above, and improving the quality of pattern formation by uniformizing the output of a plurality of arrayed semiconductor laser elements, when forming a plurality of semiconductor laser elements on a substrate, any It is an object of the present invention to be able to set the emitting direction of the laser light in the direction of, and to cool the light emitting layer effectively.

  In order to achieve such an object, an exposure head and an exposure head manufacturing method according to the present invention include at least the following configurations.

  One semiconductor substrate, the semiconductor substrate as a common substrate, a plurality of semiconductor laser element portions having a light emitting layer along the surface of the substrate and a pair of resonator end faces perpendicular to the surface, and the adjacent semiconductor laser A concave groove formed between the resonator end faces of the element portion, and a laser beam emitted from the light emitting surface facing the light emitting surface of the semiconductor laser element portion in the concave groove portion is reflected to the substrate side An exposure head, comprising: a reflecting surface for irradiating the surface to be exposed with laser light through the substrate.

  Forming a semiconductor laser element layer including a light emitting layer along a surface of the semiconductor substrate on one semiconductor substrate; forming a plurality of parallel groove portions in the semiconductor laser element layer; and a pair of wall surfaces in the groove portion Forming a plurality of semiconductor laser element portions having a cavity end face, embedding the concave groove portion with a light transmission layer, forming a processed surface inclined with respect to the surface of the semiconductor substrate in the light transmission layer, Forming a reflective surface on the processing surface that faces the light emitting surface of the semiconductor laser element portion and reflects the laser light emitted from the light emitting surface toward the substrate; and emitting the laser light from the semiconductor substrate And a step of forming a common electrode for driving the plurality of semiconductor laser element portions on a side surface and forming a light exit opening facing the reflective surface. Law.

  In the present invention having such a feature, by forming a plurality of semiconductor laser element portions on one substrate, it is possible to form an array with high positional accuracy and element formation with suppressed individual differences, and due to variations in arrangement pitch. It is possible to improve the quality of pattern formation by eliminating deterioration in quality of pattern formation and making the outputs of a plurality of arranged semiconductor laser element portions uniform. Also, when forming a plurality of semiconductor laser element portions on the substrate, a laser beam is emitted in any direction with respect to the substrate by forming a reflective surface on the processed surface of the light transmission layer formed in the groove portion. Can be set. Further, by emitting laser light through the substrate, cooling can be performed from the side close to the light emitting layer, so that the light emitting layer can be effectively cooled.

It is explanatory drawing which shows the structure of the exposure head which concerns on one Embodiment of this invention, (a) is principal part explanatory drawing, (b) is the A section enlarged view in (a), (c) is B in (a). FIG. It is explanatory drawing which showed the layer structure of the semiconductor laser element part in embodiment of this invention. It is explanatory drawing which showed the structure of the exposure head which concerns on other embodiment of this invention. It is explanatory drawing explaining each process of the manufacturing method of the exposure head which concerns on embodiment of this invention. It is explanatory drawing explaining each process of the manufacturing method of the exposure head which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a configuration of an exposure head according to an embodiment of the present invention, FIG. 1 (a) is an explanatory view of a main part, FIG. 1 (b) is an enlarged view of a part A in FIG. FIG.1 (c) is the B section enlarged view in Fig.1 (a).

  The exposure head 1 includes a single semiconductor substrate (hereinafter simply referred to as a substrate) 10, a plurality of semiconductor laser element portions 2 using the substrate 10 as a common substrate, a concave groove portion 3, and a reflective surface 4. The substrate 10 is a semiconductor substrate that can constitute a semiconductor laser, and can be made of a material that is transparent to the generated laser light. For example, GaN having light transmittance in a wide wavelength range. A substrate, an α-SiC substrate having light transmittance in a long wavelength region, or the like can be used.

  The semiconductor laser element section 2 includes a light emitting layer 2A along the surface of the substrate 10 and a pair of resonator end faces 20 (20A, 20B) perpendicular to the surface of the substrate 10. FIG. 2 shows an example of the layer structure of the semiconductor laser element portion 2. The layer structure L of the semiconductor laser element portion 2 is composed of a semiconductor layer L1 and electrode layers (first electrode layer 21 and second electrode layer 22) disposed outside the semiconductor layer L1. When the substrate 10 is an n-type GaN substrate, the first electrode layer 21 is a p-electrode and the second electrode layer 22 is an n-electrode. The semiconductor layer L1 includes, for example, a first semiconductor layer (n-type GaN layer) 11, a light emitting layer 2A, a second semiconductor layer (p-type GaN layer) 12 and the like stacked on a substrate (n-type GaN substrate) 10. . The structure of the semiconductor laser element unit 2 is not limited to this, and various conventionally known structures can be employed.

  A plurality of semiconductor laser element portions 2 having the substrate 10 as a common substrate are formed by dividing the common semiconductor layer L1 by the groove portion 3. That is, the left and right wall surfaces 3 </ b> A and 3 </ b> B of the concave groove portion 3 constitute the resonator end surface 20 (20 </ b> A and 20 </ b> B) in the semiconductor laser element portion 2. In the resonator end surface 20, one resonator end surface 20A serving as a light emitting surface is a partially reflecting surface, and a reflection layer 20B1 is formed on the other resonator end surface 20B. The plurality of semiconductor laser element portions 2 formed in this way are highly uniform elements with individual differences suppressed.

  A reflecting surface 4 is formed in the recessed groove portion 3 formed between the resonator end surfaces 20 of the adjacent semiconductor laser element portions 2. The reflecting surface 4 is formed so as to face the light emitting surface (one resonator end surface 20A) of the semiconductor laser element portion 2, and reflects the laser light Lb emitted from the light emitting surface toward the substrate 10 side. Is.

  The reflection surface 4 is formed on the processed surface 5 </ b> A of the light transmission layer 5 formed in the groove 3. The light transmission layer 5 is formed as will be described later, and has a processed surface 5A inclined at an arbitrary angle with respect to the surface of the substrate 10. By forming the reflective layer 4A on the processed surface 5A, the reflective surface 4 for reflecting the laser beam is formed on the substrate 10 side.

The light transmissive layer 5 is made of a material having high light transmittance, such as a SiO ₂ layer, and having good processability. In the exposure head according to the embodiment of the present invention, the reflective surface 4 is formed on the processed surface 5A of the light-transmitting layer 5 with good processability, and therefore the reflective head 4 reflects in any direction with respect to the surface of the substrate 10. Laser light can be emitted.

  A second electrode layer 22 serving as a common electrode for driving the plurality of semiconductor laser element portions 2 is formed on the surface of the substrate 10 on the laser light emitting side, and the light emitting aperture is opposed to the reflecting surface 4. A portion 23 is provided. The light emitting opening 23 is formed by forming an opening in the second electrode layer 22 having a light shielding function. The laser light emitted from the semiconductor laser element portion 2, reflected by the reflecting surface 4 and transmitted through the substrate 10 is emitted from the light emitting opening 23 to the outside of the substrate 10, condensed by the microlens 6, and not shown Irradiates the exposed surface. That is, the light exit opening 23 formed on the light exit side surface of the substrate 10 functions as an aperture stop for the microlens 6.

  FIG. 3 is an explanatory view showing the configuration of an exposure head according to another embodiment of the present invention. Parts common to the above-described embodiment are given the same reference numerals, and redundant description is omitted. In the exposure head 1 (1A) according to this embodiment, the second electrode layer 22 formed on the light emitting side surface of the substrate 10 is covered with a heat dissipation layer 25 via a transparent insulating film 24. The heat dissipation layer 25 can be formed of a metal layer having high thermal conductivity such as Al. In the heat dissipation layer 25, naturally, an opening corresponding to the light emitting opening 23 is formed. By providing such a heat dissipation layer 25, the substrate 10 heated by transmitting the laser beam can be effectively cooled.

  In the exposure head 1 (1A) shown in FIG. 3, the cooling means is brought into contact with the semiconductor laser element portion 2 by interposing (circulating) the liquid cooling means 7 on the semiconductor laser element portion 2. As the liquid cooling means 7, for example, an insulating liquid (such as Fluorinert manufactured by Sumitomo 3M) can be used. The exposure head 1 (1A) can cover the semiconductor laser element portion 2 with a coolant by emitting the laser light Lb from the substrate 10 side. Accordingly, it is possible to effectively cool the vicinity of the light emitting layer 2 </ b> A that is significantly heated, and the light emission efficiency of the semiconductor laser element portion 2 can be improved. A wiring (Au wire) 9 is connected to the first electrode layer 21 covered with the liquid cooling means 7 via a bump ball 8, and the wiring 9 is connected to a drive circuit (not shown).

  4 and 5 are explanatory views for explaining each step of the exposure head manufacturing method according to the embodiment of the present invention.

  As the first step, as shown in FIG. 4A, a semiconductor layer L1 including a light emitting layer 2A along the surface of the semiconductor substrate 10 is formed on one substrate (semiconductor substrate) 10.

  As the next step, as shown in FIG. 4B, a plurality of semiconductors in which a plurality of recessed groove portions 3 are formed in parallel with the semiconductor layer L1 and the pair of wall surfaces 3A and 3B in the recessed groove portion 3 are the resonator end surfaces 20 are formed. The laser element portion 2 is formed. The concave groove 3 is formed by machining the substrate 10 (GaN substrate) by machining to form a concave groove. Instead of mechanical processing, chemical processing technology (such as etching processing) or physical processing technology (such as ion beam processing) may be used. Moreover, the concave groove part 3 can also be formed by combining these processing techniques.

  In order to form the semiconductor laser element portion 2 using the wall surfaces 3A and 3B of the recessed groove portion 3 as the resonator end surface 20, as shown in FIG. 3C, a reflecting layer 20B1 is formed on the wall surface 3B, and further, the wall surface The resonator end surface 20 (20A) by 3A is used as a partial reflection surface. The reflective layer 20B1 is formed by forming a metal film having a high reflectance on the wall surface 3B by a film formation method such as vapor deposition or forming a total reflection film using a multilayer film.

In the next step, as shown in FIG. 4D, FIG. 5E, and FIG. 5F, the recessed groove portion 3 is embedded with the light transmission layer 5, and the substrate (semiconductor substrate) 10 is embedded in the light transmission layer 5. A processed surface 5A inclined with respect to the surface is formed. Specifically, first, as shown in FIG. 4D, the groove 3 is completely filled with a light transmission layer 5 (for example, a SiO ₂ layer). At this time, a layer deposition method such as an SOG (Spin-on-Glass) method or a CVD method can be used. Thereafter, as shown in FIG. 5E, the light transmission layer 5 protruding from the groove 3 is removed by CMP polishing or the like. Then, as shown in FIG. 5 (f), the light emitting end face side in the groove 3 is inclined by etching using a gray scale mask, and all the light transmission layers 5 in the other grooves 3 are removed. To do. At this time, the formation of the inclined structure and the removal of the other light transmission layer 5 are not limited to the above-described etching process, and a machining process or an ion beam process may be used.

  In the next step, as shown in FIG. 5G, the laser beam emitted from the light emitting surface facing the light emitting surface of the semiconductor laser element part 2 is formed on the processed surface 5A. The reflection surface 4 to be reflected is formed. In forming the reflective surface 4, the reflective layer 4A is formed on the processed surface 5A by a film formation method such as vapor deposition. As the reflective layer 4A, a metal film having a high reflectance is formed, or a total reflection film made of a multilayer film is formed.

  In the next step, as shown in FIG. 5H, a second electrode layer 22 serving as a common electrode for driving the plurality of semiconductor laser element portions 2 is formed on the surface of the substrate (semiconductor substrate) 10 on the laser light emission side. At the same time, a light exit opening 23 facing the reflecting surface 4 is formed. Further, the first electrode layer 21 is formed on the semiconductor layer L1. The light emitting opening 23 is formed by forming an opening having a necessary area by selective etching after the second electrode layer 22 is formed on the entire surface.

  The exposure head 1 (1A) according to the embodiment of the present invention described above is an element in which a plurality of semiconductor laser element portions 2 are formed on a single substrate 10 so that an array with high positional accuracy and individual differences are suppressed. This makes it possible to eliminate the deterioration of the pattern formation quality due to the variation in the arrangement pitch, and to uniform the outputs of the plurality of semiconductor laser element portions 2 arranged to improve the quality of the pattern formation.

  Further, when forming the plurality of semiconductor laser element portions 2 on the substrate 10, the reflective surface 4 is formed on the processed surface 5A of the light transmission layer 5 formed in the concave groove portion 3, depending on the processing of the processed surface 5A. The emission direction of the laser beam can be set in any direction with respect to the substrate 10. Further, by emitting laser light through the substrate 10, it is possible to cool from the side close to the light emitting layer 2A, so that the light emitting layer 2A can be effectively cooled, and the light emission efficiency of the semiconductor laser element portion 2 is achieved. Can be increased. In addition, since effective cooling can suppress thermal distortion of the pitch interval of the semiconductor laser element portion 2 and the like, high-definition pattern formation can be realized with high quality.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. In addition, the above-described embodiments can be combined by utilizing each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1, 1A: exposure head, 2: semiconductor laser element portion, 2A: light emitting layer,
3: groove portion, 3A, 3B: wall surface, 4: reflective surface, 4A: reflective layer,
5: light transmission layer, 5A: processed surface, 6: microlens, 7: liquid cooling means,
10: Substrate, 20 (20A, 20B): End face of resonator, 20B1: Reflective layer,
21: 1st electrode layer, 22: 2nd electrode layer, 23: Light emission opening part, 24: Insulating film,
25: heat dissipation layer, L: layer structure, L1: semiconductor layer, Lb: laser beam

Claims (6)

One semiconductor substrate,
A plurality of semiconductor laser element portions having a light emitting layer along a surface of the substrate and a pair of resonator end faces perpendicular to the surface, wherein the semiconductor substrate is a common substrate;
A recessed groove formed between the resonator end faces of the adjacent semiconductor laser element portions;
A reflecting surface that faces the light emitting surface of the semiconductor laser element portion in the concave groove and reflects the laser light emitted from the light emitting surface toward the substrate;
An exposure head that irradiates a surface to be exposed with laser light through the substrate.   2. The exposure head according to claim 1, wherein the reflection surface is formed on the processed surface of a light transmission layer formed in the concave groove portion and having a processed surface inclined with respect to the surface of the substrate. .   3. The laser output side surface of the substrate is provided with a common electrode for driving the plurality of semiconductor laser element units and a light output opening facing the reflection surface. Exposure head.   4. The exposure head according to claim 3, wherein the common electrode is covered with a heat dissipation layer.   5. The exposure head according to claim 1, wherein a cooling means is in contact with the semiconductor laser element portion. Forming a semiconductor layer including a light emitting layer along a surface of the semiconductor substrate on one semiconductor substrate;
Forming a plurality of parallel groove portions in the semiconductor layer, and forming a plurality of semiconductor laser element portions having a pair of wall surfaces in the groove portions as resonator end faces;
The recessed groove is filled with a light transmission layer, a processed surface inclined with respect to the surface of the semiconductor substrate is formed in the light transmission layer, and the light emitting surface of the semiconductor laser element unit is opposed to the processed surface. Forming a reflecting surface for reflecting the laser beam emitted from the light emitting surface to the substrate side;
Forming a common electrode for driving the plurality of semiconductor laser element portions on a surface on the laser light emitting side of the semiconductor substrate, and forming a light emitting opening facing the reflecting surface. A method for manufacturing an exposure head.

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