JP2006140382A - Optical element, manufacturing method thereof, surface emitting element array, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having formed micro lenses of good shapes, and to provide the manufacturing method thereof. <P>SOLUTION: The manufacturing method of an optical element includes a process for forming a surface emitting element 100 on a substrate, a process for measuring the optical characteristic of the surface emitting element 100, a process for determining the necessary dripping quantity of the precursor solution of a light-transmissive hardening resin for forming each desired micro lens based on the measured optical characteristic and from a predetermined calibrating information, a process for dripping each precursor solution 50' having the determined dripping quantity on an emitting surface 46 of the surface emitting element 100, and a process for so hardening each dripped precursor solution 50' as to form each micro lens 50. The calibrating information indicates the relation generated among the optical characteristics of the samples of the surface emitting element which are obtained respectively before and after forming the micro lenses on the element and the necessary dripping quantity of the precursor solution for forming the micro lenses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element and a manufacturing method thereof, and a surface light emitting element array and a manufacturing method thereof.

  2. Description of the Related Art A vertical cavity surface emitting laser (hereinafter abbreviated as VCSEL), which is a surface light emitting element, can be two-dimensionally integrated and is expected as a light source for parallel optical communication. In addition, the VCSEL has an advantage that it can be inspected at the wafer level after fabrication. When VCSELs are arrayed, microlenses that can be arrayed may be used in combination with VCSELs in order to improve the characteristics.

  However, in order to realize parallel optical communication using the VCSEL, the uniformity of element characteristics within the wafer surface caused by process factors is particularly important. For example, even if 90% yield can be ensured with a single VCSEL chip, when this is arrayed, it is only 66% for 4 channels, 43% for 8 channels, and 19% for 16 channels. You can't expect. For this reason, there is a demand for a technique for improving the yield when VCSELs are arrayed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical element in which a microlens having a good shape is formed and a method for manufacturing the same.

  Another object of the present invention is to provide a surface light emitting element array in which a difference in characteristics between chips is reduced and a method for manufacturing the same.

(1) The manufacturing method of the optical element of the present invention is as follows:
Forming a surface light emitting element on a substrate;
Measuring optical characteristics of the surface light emitting element;
Determining a dripping amount of a precursor solution of a cured resin having light permeability necessary for forming a desired microlens from predetermined calibration information based on the measured optical characteristics;
Dropping the determined amount of the precursor solution above the emission surface of the surface light emitting element;
Curing the dropped precursor solution to form a microlens;
Including
The calibration information includes the optical characteristics of the surface light emitting element sample without the microlens, the optical characteristics after the microlens is formed on the surface light emitting element sample, and the dripping of the precursor solution required for forming the microlens. It shows the relationship with quantity.

  According to the method for manufacturing an optical element of the present invention, an optical element in which a microlens having a favorable shape is provided above the emission surface of the surface light emitting element can be manufactured in a simpler process. This is because the knowledge of the correspondence between the emission angle before and after microlens formation and the amount of precursor dripping required to form the microlens is obtained in advance. This is because the amount of dripping necessary to form a desired microlens can be determined only by measuring the above. As a result, according to the manufacturing method of the present invention, a desired microlens can be formed by a simpler process, and an optical element in which element characteristics are improved, for example, a radiation angle is reduced can be manufactured. .

  In the method of manufacturing an optical element according to the present invention, providing another specific item (hereinafter referred to as “B”) above the specific item (hereinafter referred to as “A”) The case where B is provided directly and the case where B is provided on A via another on A are included.

  (2) In the method for manufacturing an optical element of the present invention, the optical characteristic may be an emission angle of emitted light.

(3) In the method for producing an optical element of the present invention, the dropping of the precursor solution is performed by a droplet discharge method,
By controlling at least one of the unit dropping amount and the number of droppings, the dropping can be performed so as to satisfy the determined dropping amount.

  According to this aspect, by controlling the unit dropping amount or the number of droppings, it is possible to perform dropping with high accuracy so as to satisfy the determined dropping amount.

(4) The method for producing the surface light emitting element array of the present invention includes:
Forming a plurality of surface-emitting elements arrayed on a substrate;
Measuring optical characteristics of the surface light emitting elements,
Based on the measured optical characteristics, determining a dripping amount of a precursor solution of a cured resin having light permeability necessary for forming a desired microlens from predetermined calibration information for each of the surface light emitting elements,
Dropping each of the determined dropping amounts of the precursor solution above the exit surface of the surface light emitting element;
Curing the dropped precursor to form a microlens;
Including
The calibration information includes the optical characteristics of the surface light emitting element sample without the microlens, the optical characteristics after the microlens is formed on the surface light emitting element sample, and the dripping of the precursor solution required for forming the microlens. It shows the relationship with quantity.

  According to the method for manufacturing a surface light emitting element array of the present invention, it is possible to form a surface light emitting element array with little variation in element characteristics within the surface. This is because the knowledge of the correspondence between the emission angle of the surface light emitting element before and after the microlens formation and the amount of the precursor dropped to form the microlens is obtained in advance. This is because the amount of dripping necessary to obtain the desired microlens can be determined according to the respective optical characteristics measured. That is, the formation of the microlens can be controlled so that the characteristics of each surface light emitting element after the formation of the microlens exhibit a desired range of characteristics. As a result, it is possible to form a surface light emitting element array with reduced variations in in-plane element characteristics.

  (5) In the method for manufacturing a surface light emitting element array according to the present invention, the optical characteristic may be a radiation angle of emitted light.

(6) In the method for manufacturing the surface light emitting element array of the present invention, the dropping of the precursor solution is performed by a droplet discharge method,
By controlling at least one of the unit dropping amount and the number of droppings, the dropping can be performed so as to satisfy the determined total dropping amount.

  According to this aspect, by controlling the unit dropping amount or the number of droppings, it is possible to perform dropping with high accuracy so as to satisfy the determined dropping amount.

(7) In the method for manufacturing a surface light emitting element array of the present invention, when the precursor solution is dropped onto the surface light emitting element using an inkjet head capable of changing the unit dropping amount of the precursor solution,
Changing the unit drop amount of the inkjet head according to the measurement result of the optical property may be included.

  According to this aspect, it is possible to efficiently perform the precise dropping with respect to each of the surface light emitting elements formed in the same plane.

  (8) The optical element of the present invention is an optical element formed by any one of the optical element manufacturing methods described above.

  This optical element is manufactured by controlling the formation of microlenses so as to obtain desired element characteristics. That is, according to the present invention, an optical element having good element characteristics can be provided.

  (9) The surface light-emitting element array of the present invention is a surface light-emitting element array formed by any one of the surface light-emitting element array manufacturing methods described above.

  This surface light emitting element array is formed by controlling the amount of precursor dropped to form the microlens so as to reduce variation in characteristics within the surface. Therefore, it is possible to provide a surface light emitting element array in which the characteristic difference between chips is reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. In the following embodiments, a case of a surface light emitting element array in which a plurality of elements are arranged on a substrate will be described as an example.

  FIG. 1 is a cross-sectional view schematically showing a surface emitting laser array (an example of a surface emitting element array) according to an embodiment of the present invention. FIG. 2 is an external view schematically showing the surface emitting laser array according to the embodiment of the present invention.

  The surface emitting laser array according to the present embodiment includes a plurality of vertical cavity surface emitting lasers (VCSEL) 100 arranged in a plane on a wafer 150, as shown in the external view of FIG. .

  As shown in the sectional view of FIG. 1, the surface emitting laser 100 constituting the surface emitting laser array of the present embodiment has an n-type electrode 42 as a common electrode on the back side of the n-type substrate 10. A semiconductor layer 20 including an active layer is disposed on the main surface side. A p-type electrode 44 is formed on the semiconductor layer 20. The semiconductor layer 20 has a pin diode structure, and constitutes a vertical resonator by sandwiching the intrinsic semiconductor layer as an active layer with mirror layers made of a semiconductor multilayer film. The semiconductor layer 20 includes a columnar portion 22 for controlling the oscillation mode in the vertical resonator. The columnar portion 22 is embedded with an insulating layer 30 as necessary. Further, the semiconductor layer 20 may include a current confinement structure.

  Further, the surface emitting laser 100 is provided with a microlens 50 on the emission surface above the semiconductor layer 20. In the surface emitting laser 100, the optical characteristics of the laser light generated in the semiconductor layer 20 are adjusted by the microlens 50, and the emitted light Pout is emitted to the outside of the element. That is, in the surface emitting laser array of the present embodiment, each of the plurality of surface emitting lasers 100 is formed by the microlens 50 so that the characteristic difference between the chips is reduced, and the yield is high. Below, an example of the manufacturing process of the surface emitting laser ray of this Embodiment is demonstrated, referring FIGS.

  First, as shown in FIG. 3, a plurality of surface emitting lasers 100 are formed in an array on a substrate 10. The semiconductor layer 20 can be formed by, for example, an epitaxial growth method such as an MBE method or an MOCVD method. The columnar portion 22 can be formed by patterning using a photolithography technique. The n-type electrode 42 and the p-type electrode 44 are formed so as to be in ohmic contact with the substrate 10 and the semiconductor layer 20 by, for example, a vacuum deposition method.

  Next, optical characteristics of the formed surface emitting laser 100, for example, a radiation angle is measured by a known method. Based on the measured radiation angle, the amount of the precursor solution to be dropped to determine the microlens is determined from calibration information prepared in advance.

  In this embodiment, the calibration information includes the emission angle of the surface emitting laser without the microlens, the emission angle of the surface emitting laser after the microlens is formed, and the dripping of the precursor liquid required for the formation of the microlens. The quantity is shown in a graph. If these correspondences are clarified, the emission angle of the emitted light of the surface emitting element after forming the microlens becomes a desired value simply by measuring the emission angle of the surface emitting laser without the microlens. It is possible to determine how much precursor solution should be dropped.

  Next, a specific example of the calibration information and a method for determining a required drop amount using the calibration information will be described. FIG. 4 shows a radiation angle before and after the formation of the microlens and a dripping amount required for the formation of the microlens when a surface emitting laser sample having a light emitting region of the active layer having a diameter of 8 μm is used. In FIG. 4, the vertical axis represents the emission angle of the surface emitting laser sample, and the horizontal axis represents the number of drops when the volume of one dot is about 1.6 pl. The calculation of the radiation angle for obtaining this calibration information was performed by the ray tracing method. As can be seen from FIG. 4, according to the calibration information, the amount of dripping required to obtain a surface emitting laser having a desired radiation angle differs depending on the radiation angle before the microlens formation.

  For example, in the case where the radiation angle of the surface emitting laser after forming the microlens is set to 22 deg, 8 dots (12.8 pl) if the measured radiation angle is 28 deg, 7 dots (11.11) if 24 deg. 2 pl) and 22 deg, it is determined that it is necessary to drop 6 dots (9.6 pl).

  Next, as shown in FIG. 5, a dripping amount of the precursor solution 50 ′ determined in the previous step is dropped on the emission surface 46 of the surface emitting laser 100. As the curable resin material, various materials such as a thermosetting type, an ultraviolet curable type, and an electron beam curable type can be used. In this embodiment, an example in which an ultraviolet curable resin material is used will be described. Moreover, the precursor solution 50 can be dripped using an inkjet head, a dispenser, etc., for example. In this embodiment, an inkjet head 210 is used. It is preferable that the inkjet head 210 can change the unit dropping amount of the precursor solution 50 ′. This may vary depending on the surface emitting element 100, but if the unit drop amount of the solution from the inkjet head 210 can be changed according to the measurement result of the optical characteristics, the unit drop amount can be changed flexibly. This is because the formation of the microlens 50 can be completed early with a small number of steps. Further, when the inkjet head 210 having a piezo element is used, this can be realized by changing the drive waveform for each surface emitting laser 100 when changing the unit drop amount.

  Further, in addition to the unit drop amount, the number of drops can be controlled so that the determined drop amount of each surface emitting laser 100 is satisfied.

  Next, as shown in FIG. 6, the precursor solution 50 ′ formed on each emission surface 46 of the surface emitting laser 100 is irradiated with ultraviolet rays 222 using an ultraviolet irradiation device 220 to cure the resin material. . As a result, the microlenses 50 are formed on all the surface emitting lasers 100 on the substrate 10.

  In this way, by adjusting the amount of the curable resin precursor solution 50 ′ required for forming the microlens, the surface emitting laser array including the surface emitting lasers 100 having respective optical characteristics within a desired range. Is manufactured. In other words, the VCSEL light output, radiation angle characteristics, and oscillation wavelength can be changed depending on the shape, refractive index, thermal conductivity, and transmittance of the resin, so the surface emitting laser can be selected by appropriately selecting the shape and material of the resin. These characteristics can be controlled within a target range.

  Further, in the manufacturing method of the present embodiment, the optical characteristic is preferably the emission angle of the emitted light, but is not particularly limited to this, and the optical characteristic is measured by using the oscillation wavelength, other characteristics, or a combination thereof. Then, based on the measurement result, calibration information can be created to determine the dripping amount necessary for actual microlens formation.

  3 to 6, the microlens 50 is formed only on the light exit surface 46. However, as long as the optical axes of the microlens 50 and the output light Pout coincide, The microlens 50 may be formed on the electrode 44 beyond 46.

  According to the method for manufacturing a surface light emitting element array of the present embodiment, it is possible to form a surface light emitting element array with little variation in element characteristics within the surface. This is because the knowledge of the correspondence between the emission angle of the surface light emitting element before and after the microlens formation and the amount of the precursor dropped to form the microlens is obtained in advance. This is because the amount of dripping necessary to obtain the desired microlens can be determined according to the respective optical characteristics measured.

  Conventionally, in order to suppress the above-described variation in optical characteristics between chips, the characteristics have been made uniform by improving a process that generates variations in the wafer surface. In VCSELs, uniformity of epitaxial growth in which semiconductor multilayer films are stacked, uniformity of resonator mesa diameter, or electrode opening diameter, and the like are important for in-plane characteristic uniformity. Of course, the elimination of variations due to these process factors is important and effective.

  However, stabilization of such a process requires more accurate equipment and requires a large capital investment. Even with one VCSEL resonator diameter, the coater resist film thickness uniformity, aligner illuminance uniformity, developer development uniformity, dry etcher etching rate uniformity, etc. The uniformity of the wafer surface can be achieved by the stability of the apparatus. In order to make all these devices highly accurate, a large amount of capital investment is required, and labor for setting the conditions in each device is also required, and a substantial increase in the cost of the device is inevitable.

  However, as described above, in the present embodiment, by obtaining predetermined calibration information in advance, the characteristics of each surface light emitting element after the formation of the microlens show characteristics within a desired range. The formation can be controlled. As a result, it is possible to form a surface light-emitting element array with reduced variations in in-plane element characteristics by a simpler process without the need to prepare an expensive manufacturing apparatus. It is also highly useful in terms of productivity such as yield.

  In addition, this Embodiment is not limited to the above-mentioned Embodiment, A various deformation | transformation is possible within the range of the summary of this invention. For example, although the present invention has been illustrated as applied to a method for manufacturing a surface emitting laser array, the present invention is not limited to this and can also be applied to the formation of surface emitting elements that are not on the array. In this case, it is possible to form a surface emitting laser (an example of an optical element according to the present invention) having a desired microlens by appropriately adjusting the microlens formation process. Specifically, the VCSEL light output, radiation angle characteristics, and oscillation wavelength can be changed by the shape, refractive index, thermal conductivity, and transmittance of the resin, so the resin shape and material can be selected appropriately. A surface emitting laser having desired characteristics can be manufactured.

Sectional drawing which shows the surface emitting laser array concerning this Embodiment. 1 is an external view showing a surface emitting laser array according to an embodiment. The figure which shows 1 process of the formation method of the surface emitting laser array concerning this Embodiment. The figure which shows an example of the calibration information used with the formation method of the surface emitting laser array concerning this Embodiment. The figure which shows 1 process of the formation method of the surface emitting laser array concerning this Embodiment. The figure which shows 1 process of the formation method of the surface emitting laser array concerning this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Semiconductor layer, 22 ... Columnar part, 30 ... Insulating layer, 42 ... N-type electrode, 44 ... P-type electrode, 46 ... Outgoing surface, 50 ... Microlens, 50 '... Precursor solution, 100 ... Surface emitting laser, 150 ... wafer, 210 ... inkjet head, 220 ... ultraviolet irradiation device, 222 ... ultraviolet

Claims (9)

Forming a surface light emitting element on a substrate;
Measuring optical characteristics of the surface light emitting element;
Determining a dripping amount of a precursor solution of a cured resin having light permeability necessary for forming a desired microlens from predetermined calibration information based on the measured optical characteristics;
Dropping the determined amount of the precursor solution above the emission surface of the surface light emitting element;
Curing the dropped precursor solution to form a microlens;
Including
The calibration information includes the optical characteristics of the surface light emitting element sample without the microlens, the optical characteristics after forming the microlens on the surface light emitting element sample, and the dripping amount of the precursor solution required for forming the microlens. The manufacturing method of the optical element which shows the relationship. In claim 1,
The method for manufacturing an optical element, wherein the optical characteristic is a radiation angle of outgoing light. In claim 1 or 2,
The dropping of the precursor solution is performed by a droplet discharge method,
A method of manufacturing an optical element, wherein dropping is performed so as to satisfy the determined dropping amount by controlling at least one of the unit dropping amount and the number of droppings. Forming a plurality of surface-emitting elements arrayed on a substrate;
Measuring optical characteristics of the surface light emitting elements,
Based on the measured optical characteristics, determining a dripping amount of a precursor solution of a cured resin having light permeability necessary for forming a desired microlens from predetermined calibration information for each of the surface light emitting elements,
Dropping each of the determined dropping amounts of the precursor solution above the exit surface of the surface light emitting element;
Curing the dropped precursor to form a microlens;
Including
The calibration information includes the optical characteristics of the surface light emitting element sample without the microlens, the optical characteristics after forming the microlens on the surface light emitting element sample, and the dripping amount of the precursor solution required for forming the microlens. The manufacturing method of the surface emitting element array which shows the relationship with these. In claim 4,
The method for manufacturing a surface light emitting element array, wherein the optical characteristic is a radiation angle of emitted light. In claim 4 or 5,
The dropping of the precursor solution is performed by a droplet discharge method,
A method of manufacturing a surface light emitting element array, wherein the dropping is performed so as to satisfy the determined dropping amount by controlling at least one of the unit dropping amount and the dropping number. In claim 6,
In the case where the precursor solution is dropped on the surface light emitting device using an inkjet head capable of changing the unit dropping amount of the precursor solution,
A method for manufacturing a surface light emitting element array, comprising changing a unit drop amount of the inkjet head according to a measurement result of the optical characteristics.   An optical element manufactured by the manufacturing method according to claim 1.   A surface-emitting element array formed by the manufacturing method according to claim 4.

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