CN110690648B

CN110690648B - Laser device

Info

Publication number: CN110690648B
Application number: CN201910850471.4A
Authority: CN
Inventors: 崔元珍; 金东焕
Original assignee: Shanghai Wuzhao Electronic Technology Co ltd
Current assignee: Shanghai Wuzhao Electronic Technology Co ltd
Priority date: 2019-07-09
Filing date: 2019-09-04
Publication date: 2022-05-13
Anticipated expiration: 2039-09-04
Also published as: KR102230643B1; KR20210007065A; CN110690648A

Abstract

The invention discloses a laser device, which comprises: a substrate; a first reflective laminate disposed on the substrate; an active layer disposed on the first reflective stack; an oxide layer disposed on the active layer; a second reflective stack disposed on the oxide layer; a plurality of grooves penetrating the second reflective laminate, the oxide layer, the active layer, and the first reflective laminate; a first electrode layer disposed on the second reflective laminate and electrically connected to the second reflective laminate; and a second electrode layer disposed on the second reflective laminate and extending into the plurality of grooves to be electrically connected to the first reflective laminate, wherein the second reflective laminate has a reflectance higher than that of the first reflective laminate.

Description

Laser device

Technical Field

The invention relates to a laser device (LASER DEVICE).

Background

A Vertical Cavity Surface Emitting Laser (VCSEL) is capable of single longitudinal mode oscillation with a narrow spectrum and a radiation angle of a light beam is small, so that coupling efficiency (coupling efficiency) is high.

Recently, a technology of fabricating a light source matrix for patterning Vertical Cavity Surface Emitting Lasers (VCSELs) in a two-dimensional array form is actively studied. A three-dimensional image of an object can be constructed by illuminating the object with a light source matrix patterned in a two-dimensional array and analyzing the pattern of reflected light.

However, most vertical cavity surface emitting lasers are configured by a substrate, a lower reflective layer, a laser cavity, and an upper reflective layer structure, and emit light generated in the laser cavity to an upper portion, which is a direction opposite to the substrate.

That is, in the flip chip structure in which light generated in a laser cavity is emitted to the outside through a substrate, it is not practical to develop the flip chip structure.

Disclosure of Invention

Problems to be solved

The invention discloses a VCSEL laser device with a flip chip structure.

The invention discloses a VCSEL laser device with excellent light output.

The problem to be solved by the present invention is not limited to this, and may include an object or an effect that can be grasped from the means for solving the problem or the embodiments described below.

Means for solving the problems

The laser device according to an embodiment of the present invention includes: a substrate; a first reflective laminate disposed on the substrate; an active layer disposed on the first reflective stack; an oxide layer disposed on the active layer; a second reflective laminate disposed on the oxide layer; a plurality of grooves penetrating the second reflective laminate, the oxide layer, the active layer, and the first reflective laminate; a first electrode layer disposed on the second reflective laminate and electrically connected to the second reflective laminate; and a second electrode layer disposed on the second reflective laminate and extending into the plurality of grooves to be electrically connected to the first reflective laminate, wherein the second reflective laminate has a reflectance higher than that of the first reflective laminate.

The laser device may further include a conductive layer disposed between the substrate and the first reflective stack, wherein the substrate is not doped with a dopant, and the conductive layer is doped with a dopant.

The dopant doped in the conductive layer may be the same as the dopant doped in the first reflective stack, and the conductive layer may have a higher doping concentration than the first reflective stack.

The laser device may include a first insulating layer extending to an inside of the plurality of grooves, the plurality of grooves and the first insulating layer exposing a portion of an upper surface of the conductive layer.

The second electrode layer may include a contact portion extending into the plurality of grooves and electrically connected to the conductive layer.

The laser device may include a second insulating layer disposed between the first electrode layer and the second electrode layer.

The laser light generated in the active layer can be reflected by the second reflective laminate and emitted to the outside through the substrate.

The oxide layer may include a plurality of non-oxidized regions each surrounded on a plane by the plurality of grooves.

Each of the non-oxidized regions may be surrounded on a plane by the plurality of contact portions, and the plurality of contact portions may overlap the plurality of grooves on a plane.

A laser device according to another embodiment of the present invention includes: a substrate; a conductive layer disposed on the substrate; a first reflective laminate disposed on the conductive layer; an active layer disposed on the first reflective stack; an oxide layer disposed on the active layer; a second reflective laminate disposed on the oxide layer; a plurality of grooves that penetrate the second reflective laminate, the oxide layer, the active layer, and the first reflective laminate and expose the conductive layer; a first electrode layer disposed on the second reflective laminate; a first insulating layer which is disposed on the first electrode layer and the plurality of grooves and includes an opening portion exposing the conductive layer; a second electrode layer disposed on the first insulating layer, extending toward the opening, and contacting the conductive layer; a second insulating layer disposed on the second electrode layer; a first pad which penetrates the first insulating layer and the second insulating layer and is electrically connected to the first electrode layer; and a second pad electrically connected to the second electrode layer through the second insulating layer.

Effects of the invention

According to the embodiment, a laser device of a flip chip structure can be manufactured. Therefore, additional wire bonding operations can be omitted.

In addition, the light output can be improved.

In addition, the operating voltage can be reduced.

In addition, light uniformity can be improved.

In addition, the number of chips that can be produced in 1 wafer can be increased.

In addition, the manufacturing cost of the chip can be reduced.

Drawings

Fig. 1 is a top view of a laser device according to one embodiment of the present invention.

Fig. 2a is a cross-sectional view a-a of fig. 1.

Fig. 2b is a partially enlarged view a of fig. 2 a.

Fig. 3 is a sectional view B-B of fig. 1.

Fig. 4 is a graph measuring relative light output according to doping concentration of a substrate.

Fig. 5 is a graph in which an I-V curve according to the thickness of a conductive layer is measured.

Fig. 6 to 25 are diagrams showing a laser device fabrication process.

Fig. 26 to 30 show various modifications of the arrangement of the recess and the non-oxidized region.

Detailed Description

Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described below. However, the present invention is not limited to the specific embodiments, and it should be understood that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

Terms including ordinal numbers such as first, second, and the like can be used to describe a plurality of types of components, but the components are not limited to the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, a second component can be named a first component without departing from the scope of the present invention, and similarly, a first component can also be named a second component. The term "and/or" includes a combination of a plurality of items described in association or one of a plurality of items described in association.

When a certain component is referred to as being "connected" or "in contact with" another component, it is to be understood that the component can be directly connected or in contact with the other component, but another component can also be present therebetween. On the contrary, in the case where a certain constituent element is referred to as being "directly connected" or "directly contacting" to another constituent element, it is to be understood that no other constituent element exists therebetween.

The terms used in the present application are used only for describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In the present application, the terms "including" or "having" are intended to specify the presence of the features, numerals, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not to preclude the presence or addition of one or more other features or numerals, steps, actions, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in dictionaries as generally used should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Hereinafter, the embodiments will be described in detail with reference to the drawings, and the same or corresponding constituent elements are denoted by the same reference numerals regardless of the reference numerals, and the repetitive description thereof will be omitted.

Fig. 1 is a top view of a laser device according to an embodiment of the present invention, fig. 2a is a sectional view a-a of fig. 1, fig. 2B is a partially enlarged view a of fig. 2a, and fig. 3 is a sectional view B-B of fig. 1.

Referring to fig. 1, the laser device according to the embodiment may be a flip chip type in which a first pad 62 and a second pad 61 are disposed on an upper portion of a chip on a plane.

The first pad 62 and the second pad 61 are disposed on the upper portion of the chip, and can extend long in one direction. The laser device of this structure can be directly mounted on a circuit substrate without an additional wire bonding operation. In addition, this flip chip configuration has various benefits.

The laser device can include a plurality of grooves H1 and a plurality of non-oxidized regions 53 in a plane. The oxide layer 51 can be oxidized by being exposed to the outside by the plurality of grooves H1. The oxide layer 51 can be oxidized to a virtual oxidation diameter P1 centering on the groove H1. As a result, the regions not overlapping with the respective oxidation diameters P1 were not oxidized. Therefore, the non-oxidized region 53 through which current or light passes can be formed in a region not subjected to oxidation.

Each non-oxidized region 53 can be surrounded by a plurality of adjacent grooves H1. The groove H1 disposed closest to any non-oxidized region can be defined as the adjacent groove H1. In fig. 1, although 1 non-oxidized region 53 is illustrated as being surrounded by 4 adjacent grooves H1, the number of adjacent grooves H1 is not particularly limited. Illustratively, the number of adjacent grooves H1 may also be 5 or 8.

At this time, the distance from the non-oxidized region 53 to each adjacent groove H1 may be practically the same. According to the embodiment, since the side surfaces of the oxide layer exposed by the adjacent grooves H1 are gradually oxidized (P1 region) to form the non-oxidized regions 53, the distance from the non-oxidized regions 53 to each adjacent groove H1 can be almost the same if the oxidation speed is the same.

The area ratio of the plurality of non-oxidized regions to the plurality of recesses may be 1: 0.03 to 1: 5. when the area ratio becomes more than 1: when the amount is small at 0.03 (for example, 1: 0.01), the area of the groove becomes too small, and the oxidation process becomes long. In addition, when the area ratio becomes larger than 1: in case 5, the non-oxidized region becomes too small, and thus, a problem occurs in that injection of holes is not smooth.

The plurality of contact portions 82a can overlap the plurality of grooves H1, respectively, on a plane. The contact portion 82a is a region where the second electrode layer is electrically connected to the conductive layer, and can be formed in the central portion of the groove H1. Therefore, each non-oxidized region 53 may have a structure surrounded by a plurality of contacts 82a on a plane.

Referring to fig. 2a and 2b, a laser device according to an embodiment can include a substrate 10, a first reflective stack 20, a laser cavity 30 including an active layer 32, an oxide layer 51, a second reflective stack 40, a plurality of grooves H1, a first electrode layer 81, and a second electrode layer 82.

The substrate 10 may be a semi-insulating or conductive substrate. Illustratively, the substrate 10 is a low-dopant concentration GaAs substrate, which may have a dopant concentration of 1 × 10¹⁴cm^-3To 1 × 10¹⁷cm^-3Degree of the disease.

In addition, the substrate 10 according to the embodiment may be a GaAs substrate that is not doped with a dopant. With this configuration, the light transmittance of the substrate 10 can be improved. The thickness of the substrate 10 may be 0 to 120 μm. The substrate can also be removed as needed.

The conductive layer 11 can be disposed on the substrate 10. Since the substrate 10 is not doped with a dopant, the substrate 10 can have insulating properties. Therefore, it is necessary to connect electrodes to the conductive layer 11 and supply a current to the first reflective laminate 20.

The doping concentration of the conductive layer 11 may be 1 × 10¹⁸cm^-3To 10X 10¹⁸cm^-3. The doping concentration of the conductive layer 11 can also be higher than the doping concentration of the first reflective stack 20. Although the conductive layer 11 is shown as being disposed between the substrate 10 and the first reflective laminate 20, the present invention is not necessarily limited thereto, and the conductive layer 11 may be disposed inside the first reflective laminate 20.

That is, the first reflective laminate 20 may include functional layers that simultaneously exhibit a reflective action and a current spreading action. The doping concentration of the functional layer is 1 x 10¹⁸cm^-3To 10X 10¹⁸cm^-3And thus may be higher than the doping concentration of the remaining layers.

The thickness of the conductive layer 11 may be 1 μm to 10 μm. In the case where the thickness of the conductive layer 11 is more than 10 μm, it becomes too thick to increase the light absorption rate. Therefore, the light output may be weakened. In addition, when the thickness is thinner than 1 μm, the resistance increases and the current dispersion effect decreases, and thus the light uniformity decreases.

The first reflective laminate 20 may be disposed on the substrate 10 or the conductive layer 11. The first reflective stack 20 can include a Distributed Bragg Reflector (DBR) of n-type superlattice structure. The first reflective stack 20 can be epitaxially deposited on the substrate 10 by MOCVD, MBE, or other techniques.

The first reflective stack 20 is capable of performing an internal reflection function at the VCSEL structure. The first reflective stack 20 can alternately stack a plurality of first reflective layers 21 and a plurality of second reflective layers 22.

Both the first reflective layer 21 and the second reflective layer 22 may be AlGaAs or AlGaAsP, but the aluminum composition of the first reflective layer 21 may be higher.

The first and second

reflective layers

21 and 22 can be doped with n-type dopants. The doping concentration may be 4 × 10¹⁸cm^-3To 8X 10¹⁸cm^-3。

The first and second

reflective layers

21 and 22 can have an effective optical thickness of approximately 1/4 degrees of the wavelength of light produced by the VCSEL.

The reflectance of the first reflective stack 20 may depend on the difference in refractive index between the first reflective layer 21 and the second reflective layer 22 and the number of stacked first reflective layer 21 and second reflective layer 22. Therefore, in order to obtain a high reflectivity for ensuring high quality VCSEL characteristics, the larger the difference in refractive index and the smaller the number of laminations, the better.

The laser cavity 30 can be disposed on the first reflective stack 20. The laser cavity 30 can include more than one well layer and barrier layer. The well layer can be selected from any one of GaAs, AlGaAs, AlGaAsSb, InAlGaAs, AlInGaP, GaAsP, or InGaAsP, and the barrier layer can be selected from any one of AlGaAs, InAlGaAs, InAlGaAsP, AlGaAsSb, GaAsP, AlGaAsP, GaInP, AlInGaP, or InGaAsP.

The laser cavity 30 can be designed to have sufficient optical gain. Illustratively, the laser cavity 30 according to the embodiment can be provided with a well layer having an appropriate thickness and composition ratio at the center thereof to emit light in a wavelength range of approximately 800nm to 900 nm. However, the wavelength range of the laser light output from the well layer is not particularly limited.

The laser cavity 30 can include a first semiconductor layer 31 disposed at a lower portion of the active layer 32 and a second semiconductor layer 33 disposed at an upper portion of the active layer. The first semiconductor layer 31 may be an n-type semiconductor layer and the second semiconductor layer 33 may be a P-type semiconductor layer, but is not necessarily limited thereto. The first semiconductor layer and the second semiconductor layer may also be undoped. Illustratively, the first semiconductor layer and the second semiconductor layer may be AlGaAs, but are not necessarily limited thereto.

The oxide layer 51 can be disposed over the laser cavity 30. The oxide layer 51 can be doped with the same kind of dopant as the second reflective stack 40. Illustratively, the oxide layer 51 can have a doping concentration of approximately 1 × 10¹⁸cm^-3The P-type dopant of (3) is not necessarily limited thereto.

The oxide layer 51 can include a semiconductor compound containing aluminum such as AlAs, AlGaAs, inalgas, or the like. The oxidized layer 51 according to the embodiment can be provided with an unoxidized non-oxidized region 53 at the center thereof. That is, the oxidized layer 51 can form the non-oxidized region 53 in the center thereof.

In the case of the oxidized region of the oxide layer 51, the resistance will be relatively high and the refractive index will be relatively low instead. Therefore, a current is injected into the non-oxidized region 53. Specifically, the distribution of holes (holes) in the non-oxidized region 53 becomes high, so that the optical gain can be improved.

The second reflective stack 40 may be disposed on the oxide layer 51. The second reflective stack 40 can include a plurality of third reflective layers 41 and fourth reflective layers 42.

The third reflective layer 41 can have a composition of AlGaAs, and the fourth reflective layer 42 can have a composition of GaAs. Therefore, the aluminum composition of the third reflective layer 41 may be higher than that of the fourth reflective layer 42.

The second reflective stack 40 may be doped to have a different polarity than the first reflective stack 20. Illustratively, if the first reflective stack 20 and the conductive layer 11 are doped with an n-type dopant, the second reflective stack 40 can be doped with a P-type dopant.

The reflectance of the second reflective stack 40 may be higher than the reflectance of the first reflective stack 20. Illustratively, the reflectance of the second reflective stack 40 may be 100% and the reflectance of the first reflective stack 20 may be 80% when referenced to light having a wavelength in the range of 800nm to 900 nm. Therefore, the light L1 generated in the laser cavity 30 can be emitted toward the first reflective stack 20 and the substrate 10.

The number of layers of the first reflective laminate 20 may be smaller than that of the second reflective laminate 40 in order to direct the emission direction of the laser light toward the substrate 10 and to reduce the reflectance. For example, the number of layers of the first reflective stack may be approximately 17 to 25 pairs (pair), and the number of layers of the second reflective stack may be approximately 35 to 39 pairs (pair). Therefore, the reflectance of the first reflective laminate 20 can be smaller than the reflectance of the second reflective laminate 40.

The plurality of grooves H1 can penetrate the second reflective stack 40, the oxide layer 51, the laser cavity 30, and the first reflective stack 20. Therefore, the oxidized layer 51 exposed by the plurality of grooves H1 can be gradually oxidized from the side to form the non-oxidized region 53.

The first electrode layer 81 can be disposed on the second reflective laminate 40 and electrically connected to the second reflective laminate 40. The first electrode layer 81 can be disposed on the second reflective stack 40 remaining after the formation of the plurality of grooves H1.

The first electrode layer 81 may be a P-type contact electrode. Illustratively, the first electrode layer 81 can be formed to include ITO (indium tin oxide), IZO (indium zinc oxide), IZTO (indium zinc oxide), IAZO (indium aluminum zinc oxide), IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (indium gallium zinc oxide, zinc aluminum oxide), ATO (antimony tin oxide ), GZO (gallium zinc oxide, gallium zinc oxide), IZO (IZO Nitride, zinc oxide Nitride), ago (Al-Ga ZnO, aluminum gallium zinc oxide), IGZO (In-Ga, indium gallium zinc oxide), ZnO (zinc oxide), IrO (indium gallium zinc oxide), IZO (indium gallium zinc oxide, zinc oxide Nitride), zo (Al-Ga ZnO, indium gallium zinc oxide), indium gallium zinc oxide), zinc oxide (zinc oxide), indium gallium zinc oxide, indium gallium Nitride, gallium zinc oxide, indium gallium Nitride, indium gallium Nitride, indium gallium Nitride, indium_x(Iridium oxide), RuO_x(ruthenium oxide), NiO (nickel oxide), RuO_xITO (ruthenium oxide/indium tin oxide), Ni/IrO_xAu (nickel/iridium oxide/gold) or Ni/IrO_xAt least one of/Au/ITO (nickel/iridium oxide/gold/indium tin oxide), Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, Au, Hf, W, but not limited to these materials.

The first insulating layer 71 can be disposed on the first electrode layer 81 and the plurality of grooves H1. The first insulating layer 71 forms a groove inside the plurality of grooves H1 to expose a part of the upper surface of the conductive layer 11.

The second electrode layer 82 is disposed on the first insulating layer 71 and can extend into the plurality of grooves H1. The second electrode layer 82 can include a contact portion 82a that is electrically connected to the conductive layer 11 through the groove of the first insulating layer 71. Therefore, the current injected into the second electrode layer 82 can flow through the conductive layer 11 and be dispersed to the first reflective stacked body 20. The second electrode layer 82 may be an n-type contact electrode.

The second insulating layer 72 can be disposed on the second electrode layer 82. The second insulating layer 72 can include a groove exposing a portion of the first electrode layer 81 and a groove exposing a portion of the second electrode layer 82.

The first and second insulating

layers

71 and 72 may be SiO₂、Si₃N₄、SiON、Ta₂O₅、HfO₂At least one of BCB (benzocyclobutene) and polyimide (polyimide), but is not necessarily limited thereto.

The first pad 62 can penetrate the second insulating layer 72 and be electrically connected to the first electrode layer 81. The second pad 61 can penetrate the second insulating layer 72 and be electrically connected to the second electrode layer 82.

According to the embodiment, both the first pads 62 and the second pads 61 can be disposed on the upper portion of the second reflective laminate 40. The laser device according to the embodiment has a flip chip structure, and thus, can be mounted on a circuit substrate without an additional wire bonding process.

Fig. 4 is a graph in which the relative light output according to the doping concentration of the substrate is measured, and fig. 5 is a graph in which the I-V curve according to the thickness of the conductive layer is measured.

Referring to fig. 4, it can be seen that the light output varies with the doping concentration of the substrate. Illustratively, the doping concentrations at the substrate are 2.0 × 10, respectively¹⁸cm^-3、1.0×10¹⁸cm^-3、5.0×10¹⁷cm^-3、1.0×10¹⁷cm^-3And 1.0X 10¹⁶cm^-3In the case of (2), the light output was found to vary depending on the thickness.

1.0X 10 substrate 10 having the lowest doping concentration¹⁶cm^-3In the case of (2), it was found that the light output was almost constant even when the thickness was increased. However, it is known that the higher the doping concentration of the substrate, the higher the light absorption rate becomes, and the light output decreases sharply. The doping concentration in the substrate is 2.0 × 10 as an example¹⁸cm^-3And the light output is reduced to 80% in the case where the thickness of the substrate is 20 μm, and the light output is sharply reduced to approximately 60% in the case where the thickness of the substrate is 40 μm.

Therefore, in the flip chip structure in which light is output through the substrate, it is found that the lower the doping concentration is, the more advantageous the light output is. Therefore, in one embodiment, the substrate is not doped but an additional thin conductive layer is formed, so that not only light output can be improved but also current spreading efficiency can be improved.

Referring to fig. 5, it is understood that when the conductive layer has a thickness of 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, or 6.0 μm, the voltage increase due to the increase in current is constant when the chip is driven. That is, it is found that the voltage rise due to the resistance of the conductive layer does not greatly affect the total operating voltage rise. However, it is known that the operating voltage is relatively large when the thickness of the conductive layer is 0.1 μm. Therefore, the thickness of the conductive layer is preferably 0.5 μm or more. In addition, when the thickness of the conductive layer is larger than 10 μm, there is a problem that the light absorption rate becomes large. Accordingly, the thickness of the conductive layer may be 0.5 μm to 10 μm.

Fig. 6 to 25 are diagrams showing a laser device fabrication process.

Referring to fig. 6, the substrate 10, the conductive layer 11, the first reflective stack 20, the laser cavity 30, the oxide layer 51, and the second reflective stack 40 can be sequentially grown. The layers can be constructed to incorporate the features previously described. Although the film can be produced by Metal-Organic Chemical Vapor Deposition (MOCVD), Liquid Phase Epitaxy (LPE), Molecular Beam Epitaxy (MBE), or the like, the film is not necessarily limited thereto.

The substrate is GaAs substrate, and the doping concentration can be reduced to 1 × 10¹⁴cm^-3To 1X 10¹⁷cm^-3To the extent that the substrate is fabricated to reduce light absorption, or may be undoped at all.

Referring to fig. 7, the first photoresist R1 is formed on the second reflective stack 40 using a mask, and the groove H1 can be formed in a region where the first photoresist R1 is not formed as shown in fig. 8.

The groove H1 can penetrate through the second reflective stack 40, the oxide layer 51, the laser cavity 30, and the first reflective stack 20 to expose a part of the upper surface of the conductive layer 11.

Referring to fig. 9, if the oxide layer 51 exposed by the plurality of grooves H1 is exposed to water vapor (H)₂O), oxidation can proceed from the outside to the inside of the exposed oxide layer 51. The region P1 oxidized as shown in fig. 1 becomes gradually wider along the diameter of the groove H1.

Referring to fig. 10, when the oxidation is stopped, a non-oxidized region 53 that is not oxidized is formed in the center. The oxidation rate and time can be appropriately adjusted to adjust the area of the non-oxidized region 53. That is, the amount of water vapor, the oxidation time, and the like can be adjusted to form a non-oxidized region of a desired diameter. At this time, it is also possible to form the second reflective stack thereon after removing the non-oxidized region in the oxide layer 51 in advance.

Referring to fig. 11, a second photoresist R2 can be filled in the plurality of grooves H1. Referring to fig. 12, the first electrode layer 81 can be formed on the second photoresist R2. The first electrode layer 81 can be formed entirely on the upper portion of the second photoresist R2 and on the upper portion of the second electrode stacked body 40. Referring to fig. 13, if the second photoresist R2 is selectively removed by applying a lift-off process, the first electrode layer 81 can be disposed only on the upper portion of the second reflective stack 40.

Referring to fig. 14, the first insulating layer 71 can be formed on the upper portion of the first electrode layer 81 and the entire inside of the plurality of grooves H1. Thereafter, a third photoresist R3 is formed as shown in fig. 15, and a part of the first insulating layer 71 disposed in the inner region of the groove H1 is removed as shown in fig. 16 to form a third groove H3, whereby the conductive layer 11 can be exposed. At this time, a second groove H2 exposing a part of the first electrode layer 81 can be further formed. Thereafter, the third photoresist R3 can be removed as in fig. 17.

Referring to fig. 18 and 19, it is possible to form a fourth photoresist R4 on the upper portion of the second groove H2 exposed by the first electrode layer 81 and to form the second electrode layer 82 as a whole. In this process, the contact portion 82a extending into the plurality of grooves H1 and connected to the conductive layer 11 can be formed.

Referring to fig. 20 and 21, it is possible to selectively remove the fourth photoresist R4 and form the second insulating layer 72 as a whole using a lift-off process. Referring to fig. 22 and 23, a fifth photoresist R5 can be formed to form a fourth groove H5 and a fifth groove H4 on the second insulating layer 72. The fourth groove H5 can expose the second electrode layer 82, and the fifth groove can expose the first electrode layer 81.

Thereafter, as shown in fig. 24 and 25, the sixth photoresist R6 can be formed to form the first pad 62 and the second pad 61. The first pad 62 can be electrically connected to the first electrode layer 81 through the fifth groove, and the second pad 61 can be electrically connected to the second electrode layer 82 through the fourth groove.

The grooves H1 can be selectively formed in various shapes such as a cross shape, a polygon shape, a radial shape, and the like. However, since the uniform non-oxidized region 53 needs to be formed by oxidation along the plurality of grooves H1, the shape of the groove H1 is advantageously symmetrical about a virtual line passing through the center.

Referring to fig. 26 and 27, the groove H1 can have a rectangular or square shape. In this case, the non-oxidized region 53 can have a quadrangular shape.

Referring to fig. 28, the groove H1 can have a triangular shape. In this case, the non-oxidized region 53 can also have a triangular shape.

In addition, referring to fig. 29, the groove H1 can have a hexagonal shape. In this case, the non-oxidized region 53 can have a hexagonal shape. However, not necessarily limited thereto, the groove H1 and the non-oxidized region 53 can also have various polygonal structures such as a pentagon, an octagon, and the like. However, it is not necessarily limited thereto, and the groove H1 can have a circular shape as shown in fig. 30.

The laser device according to the present embodiment can be used as a light source for 3D face recognition and 3D imaging technology.

3D face recognition and 3D imaging techniques require a matrix of light sources patterned into a two-dimensional array configuration. Such a light source matrix patterned in a two-dimensional array form can be irradiated onto an object and the pattern of reflected light can be analyzed.

In this case, a three-dimensional image of the object can be formed by analyzing the state of distortion of each unit light reflected from the curved surface of each object in the light source matrix patterned in the two-dimensional array form.

When the VCSEL array according to the embodiment is fabricated using the light source (Structured light source) patterned in the two-dimensional array form, it is possible to provide a light source (Structured light source) matrix patterned in the two-dimensional array form in which the characteristics of each unit light source are uniform.

VCSELs required for 3D face recognition and 3D imaging technologies may require highly efficient optics capable of achieving light outputs of several to several tens of watts (watt) and short pulses of 1 to 10ns or light modulation above 100MHz with low power consumption.

The modulation equivalent circuit of the optical device can be represented by an RC circuit in which the characteristic time determining the modulation speed can be represented by the product of the resistance and the electrostatic capacitance. Therefore, it is important to ensure low resistance to realize a device capable of high-speed modulation and high photoelectric conversion efficiency. Therefore, the present invention can provide a solution that most suitably provides a light source for 3D face recognition and 3D imaging.

In addition, the laser device according to the present invention can be used as a low-priced VCSEL light source in various application fields such as an optical communication device, a Closed Circuit Television (CCTV), a night vision (night vision) for an automobile, motion recognition, medical treatment/therapy, a communication device for the internet of things (IoT), a thermal camera, a thermal imaging camera, a pump field of SOL (Solid state laser), a heating process for bonding a plastic film, and the like.

Although the above description has been mainly given with reference to the embodiments, the present invention is only illustrative and not limited thereto, and it will be apparent to those skilled in the art that various modifications and applications not illustrated above can be made within a scope not departing from the essential characteristics of the present embodiments. For example, each of the components specifically shown in the embodiments can be implemented by being modified. Also, various points of difference associated with such modifications and applications should be construed to include the scope of the present invention as defined in the appended claims.

Claims

1. A laser device, comprising:

a substrate;

a conductive layer disposed on the substrate and having a thickness of 1 to 10 μm;

a first reflective laminate disposed on the conductive layer;

an active layer disposed on the first reflective stack;

an oxide layer disposed on the active layer;

a second reflective laminate disposed on the oxide layer;

a plurality of grooves that penetrate the second reflective laminate, the oxide layer, the active layer, and the first reflective laminate and expose the conductive layer;

a first electrode layer disposed on the second reflective laminate and electrically connected to the second reflective laminate; and the number of the first and second groups,

a second electrode layer disposed on the second reflective laminate and extending into the plurality of grooves to be electrically connected to the conductive layer,

the reflectance of the second reflective laminate is higher than the reflectance of the first reflective laminate,

the conductive layer is disposed between the substrate and the first reflective laminate,

the substrate is not doped with a dopant,

the conductive layer is doped with a dopant.

2. The laser device of claim 1,

the dopant doped in the conductive layer is the same as the dopant doped in the first reflective stack,

the doping concentration of the conductive layer is higher than the doping concentration of the first reflective stack.

3. The laser device according to claim 2,

comprising a first insulating layer extending to the inside of the plurality of grooves,

the plurality of grooves and the first insulating layer expose a portion of the upper surface of the conductive layer.

4. The laser device according to claim 3,

the second electrode layer includes a contact portion extending into the plurality of grooves and electrically connected to the conductive layer.

5. The laser device of claim 1,

the second insulating layer is disposed between the first electrode layer and the second electrode layer.

6. The laser device of claim 1,

the laser light generated in the active layer is reflected by the second reflective laminate, passes through the substrate, and is emitted to the outside.

7. The laser device according to claim 4,

the oxide layer includes a plurality of non-oxidized regions,

each non-oxidized region is surrounded on a plane by the plurality of grooves.

8. The laser device according to claim 7,

each non-oxidized region is surrounded on a plane by a plurality of contacts,

the plurality of contact portions are overlapped with the plurality of grooves on a plane.

9. A laser device, comprising:

a substrate;

a first reflective laminate disposed on the conductive layer;

an active layer disposed on the first reflective stack;

an oxide layer disposed on the active layer;

a second reflective laminate disposed on the oxide layer;

a first electrode layer disposed on the second reflective laminate;

a first insulating layer which is disposed on the first electrode layer and the plurality of grooves and includes an opening portion exposing the conductive layer;

a second electrode layer disposed on the first insulating layer, extending toward the opening, and contacting the conductive layer;

a second insulating layer disposed on the second electrode layer;

a first pad which penetrates the first insulating layer and the second insulating layer and is electrically connected to the first electrode layer; and the number of the first and second groups,

a second pad which penetrates the second insulating layer and is electrically connected to the second electrode layer,

the substrate is not doped with a dopant,

the conductive layer is doped with a dopant.

10. The laser device according to claim 9,

the reflectance of the second reflective laminate is higher than the reflectance of the first reflective laminate.

11. The laser device of claim 10,