Vertical Cavity Surface Emitting Laser

Abstract

The present disclosure provides a vertical cavity surface emitting laser (VCSEL), which includes: a lower reflecting mirror; an upper reflecting mirror; an active layer, which is interposed between the lower reflecting mirror and the upper reflecting mirror; an aperture forming layer, which is interposed between the upper reflecting mirror and the active layer and has an oxide layer and a window layer surrounded by the oxide layer; and a plurality of oxide holes, which penetrate the upper reflecting mirror and the aperture forming layer, wherein the upper reflecting mirror includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, and the plurality of oxide holes are arranged in the isolated region.

Description

Technical Field

[0001] The present disclosure relates to a high reliability vertical cavity surface emitting laser. Background Art

[0002] A vertical-cavity surface-emitting laser (VCSEL) is a laser that emits a laser beam in a direction vertical to the substrate surface.

[0003] A typical VCSEL includes an active layer arranged between reflectors. Electrons and holes injected through the reflectors generate light in the active layer, and laser light is generated and emitted through resonance based on the reflectors.

[0004] The current flowing vertically in VCSEL needs to be confined to a small area, and for this purpose, etching and oxidation methods have been used. For example, the reflector layer and the active layer are etched to form a ring-shaped groove to form an isolated mesa (post), and the groove is used to form an oxide layer to concentrate the current in a small area of ​​the aperture (aperture).

[0005] However, in order to form a ring-shaped groove, a wide area needs to be etched, which is burdensome. In particular, when forming a pad electrode, the connection portion connecting the pad and the emitter passes through the groove, which may cause a risk of disconnection, thereby reducing the process yield. In addition, since a wide groove is formed around the emitter, the reliability of the emitter is adversely affected due to surface defects. Summary of the invention

[0006] Embodiments of the present disclosure provide a VCSEL with high reliability.

[0007] In particular, embodiments of the present disclosure provide a VCSEL capable of preventing electrical disconnection caused by trenches.

[0008] Furthermore, the embodiments of the present disclosure provide a VCSEL capable of preventing emitter performance from being degraded due to defects.

[0009] A vertical cavity surface emitting laser (VCSEL) of one embodiment of the present disclosure includes: a lower reflecting mirror; an upper reflecting mirror; an active layer, which is located between the lower reflecting mirror and the upper reflecting mirror; an aperture forming layer, which is located between the upper reflecting mirror and the active layer and has an oxide layer and a window layer surrounded by the oxide layer; and a plurality of oxide holes, which penetrate the upper reflecting mirror and the aperture forming layer, wherein the upper reflecting mirror includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, and the plurality of oxide holes are arranged in the isolated region.

[0010] According to another embodiment of the present disclosure, a vertical cavity surface emitting laser (VCSEL) is provided, which has an emitter array. The vertical cavity surface emitting laser includes: a lower reflector; an upper reflector; an active layer between the lower reflector and the upper reflector; an aperture forming layer between the upper reflector and the active layer, and having an oxide layer and a window layer surrounded by the oxide layer; and a plurality of oxide holes, which penetrate the upper reflector and the aperture forming layer, the upper reflector includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, the upper reflector includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, the emitter array is arranged in the isolated region, and the plurality of oxide holes are arranged corresponding to each emitter and arranged in the isolated region.

[0011] According to the embodiments of the present disclosure, an insulating region is formed by ion implantation, which can prevent electrical disconnection. Furthermore, by arranging oxide holes in the isolated region, defects formed by ion implantation can be prevented from moving into the emitter, thereby providing a highly reliable VCSEL. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. 1 is a schematic top view of a VCSEL according to an embodiment of the present disclosure.

[0013] Figure 2a It is enlarged to show Figure 1 A schematic top view of the emission area.

[0014] Figure 2b It is along Figure 2a A schematic cross-sectional view taken along the cutting line AA.

[0015] Figure 3a , Figure 3b , Figure 4a , Figure 4b , Figure 5a , Figure 5b , Figure 6a as well as Figure 6b 1 and 2 are schematic plan views and cross-sectional views for explaining a method of manufacturing a VCSEL according to an embodiment of the present disclosure.

[0016] Figure 7 FIG. 4 is a schematic top view of a VCSEL according to yet another embodiment of the present disclosure.

[0017] Figure 8a It is enlarged to show Figure 7 Schematic top view of a portion of an emitter array.

[0018] Figure 8b It is along Figure 8a A cross-sectional view taken along the cutting line BB.

[0019] Figure 8c It is along Figure 8a Cross-sectional view taken along the cutting line CC.

[0020] Figure 9a FIG. 1 is a schematic top view for explaining an oxide hole used to form an oxide layer according to an embodiment of the present disclosure.

[0021] Figure 9b to Figure 9d It is a schematic plan view for explaining various modified examples of oxidation holes for forming an oxide layer. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. The embodiments introduced below are provided as examples so that the concept of the present invention can be fully conveyed to the general technicians in the technical field to which the present disclosure belongs. Therefore, the present disclosure is not limited to the embodiments described below, and may also be implemented in other forms. Moreover, in the accompanying drawings, the width, length, thickness, etc. of the constituent elements may also be enlarged for convenience. In addition, when it is recorded that a constituent element is "above" or "on" other constituent elements, it not only includes the situation that each part is "directly above" other parts or "directly on" other parts, but also includes the situation that other constituent elements are interposed between each constituent element and other constituent elements. Throughout the entire specification, the same reference numerals represent the same constituent elements.

[0023] A vertical cavity surface emitting laser (VCSEL) of one embodiment of the present disclosure includes: a lower reflecting mirror; an upper reflecting mirror; an active layer, which is located between the lower reflecting mirror and the upper reflecting mirror; an aperture forming layer, which is located between the upper reflecting mirror and the active layer and has an oxide layer and a window layer surrounded by the oxide layer; and a plurality of oxide holes, which penetrate the upper reflecting mirror and the aperture forming layer, wherein the upper reflecting mirror includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, and the plurality of oxide holes are arranged in the isolated region.

[0024] The oxide holes are arranged in isolated regions, thereby preventing defects formed by ion implantation from moving around the window layer, and providing a highly reliable VCSEL.

[0025] An insulating region formed by ion implantation is formed from the upper reflecting mirror to constitute a portion of the thickness of the lower reflecting mirror.

[0026] On the other hand, the vertical cavity surface emitting laser may further include an ohmic contact layer, the ohmic contact layer is arranged on the upper reflecting mirror, and the ohmic contact layer includes a ring-shaped circular portion and a protruding portion protruding toward the outside of the circular portion.

[0027] The annular shape may be a partial annular shape with a portion cut out.

[0028] On the other hand, the oxidation holes may be arranged between the protrusions. The ohmic contact layer includes the protrusions, and the oxidation holes are arranged between the protrusions, so that the oxidation holes can be arranged at narrower intervals, thereby reducing the size of the emitter.

[0029] The oxidation holes may each have a smaller width than the protrusions. By forming the oxidation holes to be relatively small, it is possible to suppress moisture penetration through the oxidation holes after the oxide layer is formed.

[0030] On the other hand, the vertical cavity surface emitting laser may further include: a surface protection layer covering the ohmic contact layer and the upper reflector; and an upper insulating layer arranged on the surface protection layer, the oxidation holes passing through the surface protection layer, and the upper insulating layer covering the oxidation holes.

[0031] In addition, the VCSEL may further include a plurality of through holes, the plurality of through holes penetrate the upper insulating layer and the surface protection layer to expose the ohmic contact layer, and the through holes are arranged corresponding to the protrusions.

[0032] It may be that the vertical cavity surface emitting laser further includes a pad and a connection portion arranged on the upper insulating layer, the pad is arranged above the insulating region, and the connection portion extends from the pad and is electrically connected to the ohmic contact layer through the through hole.

[0033] The oxidation holes may be circular or quadrilateral in shape, but are not limited thereto. The shape and number of the oxidation holes may be changed as required.

[0034] According to another embodiment of the present disclosure, a vertical cavity surface emitting laser (VCSEL) is provided, which has an emitter array. The vertical cavity surface emitting laser includes: a lower reflector; an upper reflector; an active layer between the lower reflector and the upper reflector; an aperture forming layer between the upper reflector and the active layer, and having an oxide layer and a window layer surrounded by the oxide layer; and a plurality of oxide holes, which penetrate the upper reflector and the aperture forming layer, the upper reflector includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, the upper reflector includes an insulating region formed by ion implantation and an isolated region surrounded by the insulating region, the emitter array is arranged in the isolated region, and the plurality of oxide holes are arranged corresponding to each emitter and arranged in the isolated region.

[0035] The insulating region formed by ion implantation may be formed from the upper reflecting mirror to constitute a portion of the thickness of the lower reflecting mirror.

[0036] It may be that the vertical cavity surface emitting laser further comprises an ohmic contact layer, the ohmic contact layer is arranged on the upper reflector corresponding to each emitter, each ohmic contact layer comprises a circular portion in the shape of an annulus and a protrusion protruding outward from the circular portion, and the oxidation hole is arranged between the protrusions. It may be that the annular shape is a partial annular shape with a portion cut off. Further, it may be that the oxidation holes have a width smaller than that of the protrusions.

[0037] It may be that the vertical cavity surface emitting laser further includes: a surface protection layer covering the ohmic contact layer and the upper reflector; and an upper insulating layer arranged on the surface protection layer, the oxidation hole penetrates the surface protection layer, and the upper insulating layer covers the oxidation hole.

[0038] Furthermore, the VCSEL may further include a plurality of through holes, the plurality of through holes penetrate the upper insulating layer and the surface protection layer to expose the ohmic contact layer, and the through holes are arranged corresponding to the protrusions.

[0039] In addition, the vertical cavity surface emitting laser may further include a pad and a connection portion arranged on the upper insulating layer, the pad being arranged above the insulating region, and the connection portion extending from the pad and electrically connected to the ohmic contact layer through the through hole.

[0040] Furthermore, the connection portion may have a mesh shape including circular openings corresponding to the emitters.

[0041] The oxidation pores may have a circular or quadrilateral shape, but are not limited thereto.

[0042] Hereinafter, various embodiments of the present disclosure are described in detail with reference to the accompanying drawings.

[0043] Figure 1 is a schematic top view of a VCSEL according to an embodiment of the present disclosure, Figure 2a It is enlarged to show Figure 1 A schematic top view of the emission area, Figure 2b It is along Figure 2a A schematic cross-sectional view taken along the cutting line AA.

[0044] Reference Figure 1 , Figure 2a as well as Figure 2b, VCSEL100 includes an emitter 150, a pad 40, and a connection portion 41. The emitter 150 includes a lower reflector 25, an active layer 27, an aperture forming layer 29, and an upper reflector 31. VCSEL100 may also include a substrate 21, a buffer layer 23, an ohmic contact layer 33, a surface protection layer 35, and an upper insulating layer 39. VCSEL100 may also include an insulating region 37 based on ion implantation and an isolated region surrounded by the insulating region, which may include an oxidation hole.

[0045] The substrate 21 may be a conductive substrate, for example, a semiconductor substrate such as n-type GaAs. The substrate 21 may also be a growth substrate for growing a semiconductor layer thereon, and may be selected according to the semiconductor layer to be grown.

[0046] The buffer layer 23 may be formed to facilitate the growth of the semiconductor layer, or may be omitted. When the substrate 23 is a GaAs substrate, the buffer layer 23 may be, for example, a GaAs layer.

[0047] The lower reflector 25 has a distributed Bragg reflector structure and may include an n-type semiconductor layer. The lower reflector 25 may be formed by, for example, repeatedly stacking semiconductor layers having different refractive indices. For example, the lower reflector 25 may be formed by alternately stacking AlGaAs layers having a relatively low Al content and AlGaAs layers having a relatively high Al content. In particular, the lower reflector 25 may be formed by alternately stacking Al0.15Ga0.85As layers having an Al content of 15% and Al0.85Ga0.15As layers having an Al content of 85%. As n-type doping, approximately 1 to 3×10 18 / cm 3 The lower reflector 25 may include, for example, more than 30 pairs of semiconductor layers having different refractive indices. The thickness of each layer in the lower reflector 25 may be set to 1 / 4 of the wavelength of light in each layer. A pair of semiconductor layers having different refractive indices may have a thickness in the range of approximately 100 nm to 200 nm.

[0048] The active layer 27 is arranged on the lower reflecting mirror 25 and may be in contact with the lower reflecting mirror 25. The active layer 27 may have a barrier layer and a well layer, and may have a structure in which the well layer is interposed between the barrier layers. The active layer 27 may especially have a multi-quantum well structure having a plurality of well layers, for example, may include a stacked structure of GaAs / InGaAs / GaAs. The structure of the barrier layer and the well layer may be changed according to the desired laser wavelength, and the well layer may include, for example, a quaternary system, a ternary system or a binary system of the InAlGaAs system. In addition, the GaAs system is illustrated in the present disclosure, but it is not limited thereto, and a semiconductor layer of the InAlGaN system or the InAlGaP system may also be used, whereby the barrier layer and the well layer may also have a nitride or phosphide structure.

[0049] The well layer in the active layer 27 is formed of a non-doped layer, and the barrier layer can also be formed of a non-doped layer. The thickness of the well layer can be approximately 2 nm to 8 nm, and the thickness of the barrier layer can be approximately in the range of 2 nm to 15 nm.

[0050] The upper reflector 31 is arranged on the active layer 27. The upper reflector 31 has a distributed Bragg reflector structure and may include a p-type semiconductor layer. The upper reflector 31 may be formed by, for example, repeatedly stacking semiconductor layers having different refractive indices. For example, the upper reflector 31 may be formed by alternately stacking AlGaAs layers having a relatively low Al content and AlGaAs layers having a relatively high Al content, as in the lower reflector 25. In particular, the upper reflector 31 may be formed by alternately stacking Al0.15Ga0.85As layers having an Al content of 15% and Al0.85Ga0.15As layers having an Al content of 85%. As p-type doping, for example, about 1 to 5×10 18 / cm 3 The upper reflector 31 may include, for example, 20 or more pairs of semiconductor layers having different refractive indices. However, the number of pairs in the upper reflector 31 is relatively small compared to the number of pairs in the lower reflector 25. On the other hand, the thickness of each layer may be set to 1 / 4 of the wavelength of light in each layer.

[0051] On the other hand, the aperture forming layer 29 is arranged between the active layer 27 and the upper reflector 31. The aperture forming layer 29 may include an oxide layer 29x and a window layer 29w. The window layer 29w is surrounded by the oxide layer 29x, thereby forming an aperture that limits the current path. The aperture forming layer 29 may be formed, for example, of an AlGaAs layer having a higher Al content than the layer in the upper reflector 31. For example, the Al content in the aperture forming layer 29 may be about 90% or more. The oxide layer 29x is formed by oxidizing the AlGaAs layer in a region other than the window layer 29w.

[0052] The width of the aperture formed by the oxide layer 29x, ie, the window layer 29w, is not particularly limited, and may be, for example, in the range of 8 um to 12 um.

[0053] Figure 2a The window layer 29w or the aperture is shown to have a disc shape, but it is not necessarily limited to this. The window layer 29w may be a disc shape, but may also be other shapes such as a polygonal shape close to a disc. Figures 9a to 9d Explain again.

[0054] On the other hand, the emitter 150 includes an insulating region 37 formed by ion implantation and an isolated region surrounded by the insulating region 37. Ions are implanted into the upper reflector 31, further into the aperture forming layer 29 and the active layer 27, and also into a portion of the thickness of the lower reflector 25.

[0055] The insulating region 37 prevents current from flowing to other regions except the aperture (window layer 29w), improving light efficiency.

[0056] The ohmic contact layer 33 is disposed on the upper reflector 31. In particular, the ohmic contact layer 33 may be in ohmic contact with the upper reflector 31 in an isolated region surrounded by the insulating region 37. The ohmic contact layer 33 may include Ti, Pt, and Au, for example, and may be formed into an ohmic contact by a rapid thermal treatment process. Figure 2a As shown, the ohmic contact layer 33 may include a partially annular circular portion 33 a and a protrusion 33 b protruding to the outside of the circular portion.

[0057] The surface protection layer 35 protects the upper reflector 31 and the ohmic contact layer 33 during the ion implantation process. The surface protection layer 35 is formed of a light-transmitting material, such as a silicon oxide film or a silicon nitride film. The surface protection layer 35 can also be formed to have a thickness that is an integral multiple of 1 / 4 of the wavelength of light in the surface protection layer. For example, when the surface protection layer 35 is made of Si 3 N 4 When formed, the thickness can be formed to be an integral multiple of about 118 nm. In addition, the surface protection layer 35 is formed to have tensile strain, and for this purpose, it can be formed at 250° C., for example.

[0058] The oxidation hole 29a is formed to expose the aperture forming layer 29. To this end, the oxidation hole 29a may penetrate the upper reflector 31 and the aperture forming layer 29, further penetrate the active layer 27, and may penetrate a part of the thickness of the lower reflector 25. The oxidation hole 29a may also penetrate the surface protection layer 35.

[0059] The oxidation hole 29a is arranged outside the ohmic contact layer 33, and in particular, can be arranged between the protrusions 33b. Further, the oxidation hole 29a is formed on an isolated region surrounded by the insulating region 37. By arranging the oxidation hole 29a on an isolated region separated from the insulating region 37 formed by ion implantation, it is possible to prevent the defects generated by ion implantation from moving toward the aperture during the formation of the oxidation layer 29x. In addition, by forming the ohmic contact layer 33 with the protrusions 33b, the oxidation holes 29a can be arranged closer to each other, thereby reducing the size of the emitter 150.

[0060] In addition, the oxidation holes 29a can be formed to be smaller than the size of the protrusions 33b. For example, the width of the oxidation holes 29a can be smaller than the width of the protrusions 33b. By setting the size of the oxidation holes 29a to be relatively small, it is possible to suppress the penetration of moisture through the oxidation holes after the oxide layer is formed. For example, the depth of the oxidation holes 29a can be about 3um, and the hole diameter can be about 4um.

[0061] The aperture forming layer 29 is oxidized through the oxidation hole 29a to define an oxidation layer 29x and a window layer 29w. At this time, the upper reflector 31, the active layer 27 and the lower reflector 25 exposed from the sidewall of the oxidation hole 29a may also be partially oxidized.

[0062] The upper insulating layer 39 covers the surface protection layer 35 and the oxide hole 29a. The upper reflector 31, the oxide layer 29x, the active layer 27 and the lower reflector 25 exposed in the oxide hole 29a are covered and insulated by the upper insulating layer 39. The upper insulating layer 39 is formed of a light-transmitting material, for example, a silicon oxide film or a silicon nitride film. The upper insulating layer 39 can also be formed to have a thickness that is an integral multiple of 1 / 4 of the wavelength of light in the upper insulating layer. For example, when the upper insulating layer 39 is made of Si 3 N 4 When formed, the thickness may be about 200 nm, 300 nm, or 500 nm. In addition, the upper insulating layer 39 is formed to have tensile strain, and for this purpose, it may be formed at 250° C., for example.

[0063] On the other hand, a through hole 39a is formed, which penetrates the upper insulating layer 39 and the surface protection layer 35 to expose the ohmic contact layer 33. The through hole 39a is arranged corresponding to the protrusion 33b of the ohmic contact layer 33. Figure 2a As shown, the through hole 39a may be formed to expose the protrusion 33b together with the round portion 33a. Figure 2a Although the through hole 39a is shown as a quadrilateral shape, the shape is not particularly limited and may be circular.

[0064] On the other hand, pads 40 and connecting portions 41 may be arranged on upper insulating layer 39. Pads 40 are arranged over a relatively wide area as an area for bonding wires. Pads 40 may be arranged on insulating area 37 formed by ion implantation, for example, and thus parasitic capacitance may be reduced.

[0065] On the other hand, the connection portion 41 can electrically connect the pad 40 and the ohmic contact layer 33. The connection portion 41 can be connected to the ohmic contact layer 33 through the through hole 39a. The connection portion 41 can have a partially annular circular portion along the ohmic contact layer 33, and an opening portion 41a that can emit a laser beam is provided inside the annular circular portion.

[0066] The pad 40 and the connection portion 41 may be formed of the same metal material, for example, Ti / Pt / Au. The pad 40 and the connection portion 41 may be formed to a thickness of about 2 μm or more.

[0067] On the other hand, although not shown, another pad, such as an n-pad, may be formed under the substrate 21. When the substrate 21 is a GaAs substrate, the n-pad may be made of AuGe / Ni / Au as an example. form.

[0068] Figure 3a , 3b 4a, 4b, 5a, 5b, 6a and 6b are schematic top views and cross-sectional views for explaining a method of manufacturing a VCSEL according to an embodiment of the present disclosure. Each cross-sectional view is a view taken along the section line AA of the corresponding top view.

[0069] First, refer to Figure 3a as well as Figure 3b , semiconductor layers 23 , 25 , 27 , 29 , and 31 are formed on a substrate 21 , and an ohmic contact layer 33 is formed.

[0070] The substrate 21 may be, for example, an n-type GaAs substrate. The semiconductor layer may include a buffer layer 23, a lower reflector 25, an active layer 27, an aperture forming layer 29, and an upper reflector 31. The semiconductor layer may be formed by epitaxial growth techniques such as metal organic chemical vapor deposition or molecular beam epitaxy.

[0071] The buffer layer 23 can be formed of a GaAs layer on the substrate 21, for example. The lower reflector 25 is formed on the buffer layer 23, and an active layer 27, an aperture forming layer 29, and an upper reflector 31 can be formed in sequence on the lower reflector 25. The lower reflector 25 and the upper reflector 31 can be formed by repeatedly stacking AlGaAs / AlGaAs with different Al compositions. The specific structures of the lower reflector 25, the active layer 27, the aperture forming layer 29, and the upper reflector 31 have been described in detail above, so in order to avoid repetition, their description is omitted here.

[0072] An ohmic contact layer 33 is formed on the upper reflector 31. The ohmic contact layer 33 is formed to include a partially annular circular portion 33a and a protruding portion 33b protruding from the circular portion 33a to the outside. The ohmic contact layer 33 can be formed by using a lift-off technique to form a metal layer, and then heat-treated by a rapid heat treatment process. The metal layer can be formed of, for example, Ti / Pt / Au, and can be formed to be approximately as well as A good ohmic contact can be formed between the ohmic contact layer 33 and the upper reflector 31 by heat treatment.

[0073] In this embodiment, a case where one ohmic contact layer 33 is formed on the substrate 21 is shown. The substrate 21 may have a diameter of, for example, 10 mm. A plurality of ohmic contact layers 33 may be formed in each element region on the substrate 21 .

[0074] In addition, the ohmic contact layer 33 can be used as a mask using a negative photoresist or a positive photoresist, but the positive photoresist is more suitable for forming a high-density array.

[0075] Reference Figure 4a as well as Figure 4b A surface protection layer 35 is formed to cover the upper reflection mirror 31 and the ohmic contact layer 33. The surface protection layer 35 protects the surface of the upper reflection mirror 31 during an ion implantation process (eg, implantation).

[0076] The surface protection layer 35 may be made of, for example, Si 3 N 4 Or SiO 2 The thickness of the surface protection layer 35 can be formed to be an integral multiple of 1 / 4 of the wavelength of light. For example, when the surface protection layer 35 is made of Si 3 N 4 When formed, it can be formed to a thickness that is an integral multiple of about 118 nm.

[0077] Next, a photoresist is formed on the surface protection layer 35, and the photoresist is used as a mask to implant ions through the upper reflector 31 using an ion implantation process. Hydrogen ions can be implanted, whereby the region into which the ions are implanted is converted into an insulating region. The implantation energy of the hydrogen ions can be up to about 350 keV, and the photoresist can be formed to a sufficient thickness, such as 8 um, to block hydrogen ions of such energy.

[0078] On the other hand, a photoresist is formed to cover the ohmic contact layer 33, and thus, ion implantation is performed outside the ohmic contact layer 33. Figure 4aAs shown in FIG. 1 , a circular isolated region is formed by ion implantation, and an insulating region 37 is formed outside the isolated region. Figure 4b As shown, the insulating region 37 may be formed to a portion of the thickness of the lower reflector 25. After the ion implantation is completed, the photoresist is removed.

[0079] Reference Figure 5a as well as Figure 5b The oxidation hole 29 a may penetrate the surface protection layer 35 , the upper reflector 31 , the aperture forming layer 29 , the active layer 27 , and may penetrate a portion of the thickness of the lower reflector 25 .

[0080] In addition, the oxidation hole 29a is formed in an isolated region surrounded by the insulating region 37 and, therefore, is separated from the ion implantation region.

[0081] Further, the oxidation hole 29a may be arranged between the protrusions 33b and may have a size smaller than the protrusions 33b. The oxidation hole 29a may have a depth of about 3um, a diameter (or width) of about 4um at the inlet side, and a sidewall inclination of about 80 degrees. The shape of the oxidation hole 29a may be various. For this, refer to Figures 9a to 9d The ohmic contact layer 33 is formed to have the protrusion 33b, so that the width of the circular portion 33a can be reduced, thereby reducing the interval between the oxidation holes 29a.

[0082] Next, the aperture forming layer 29 exposed through the oxidation hole 29a is oxidized. The oxidation can be performed, for example, at a temperature in the range of 400°C to 430°C, and by adjusting the Al composition ratio of the aperture forming layer 29, the temperature and the composition can be set so as to show an oxidation rate of 10 times or more relative to the layers in the lower reflector 25 and the upper reflector 31.

[0083] By the oxidation process, an oxidation layer 29x is formed on the aperture forming layer 29. The oxidation layer 29x is advanced toward the inside of the aperture forming layer 29 through the aperture forming layer 29 exposed at the inner wall of the oxidation hole 29a. Thus, a window layer 29w (aperture) is formed below the area surrounded by the ohmic contact layer 33. Figure 5b As shown, a portion of the oxide layer 29 x may also be formed within the insulating region 37 .

[0084] Since oxidation is performed at a relatively high temperature of 400 to 430° C., defects formed in the insulating region 37 by ion implantation may move. At this time, since the oxidation hole 29a is arranged in an isolated region surrounded by the insulating region 37, the defects can be prevented from moving to the window layer 29w side.

[0085] Reference Figure 6a as well as Figure 6b, an upper insulating layer 39 is formed on the surface protection layer 35. The upper insulating layer 39 can be formed of a light-transmitting material, for example, Si 3 N 4 Or SiO 2 The upper insulating layer 39 covers the sidewalls and the bottom of the oxidation hole 29a to insulate the semiconductor layer exposed in the oxidation hole 29a.

[0086] On the other hand, the upper insulating layer 39 and the surface protection layer 35 are patterned to form a through hole 39a exposing the ohmic contact layer 33. Figure 6a As shown, the through hole 39 a may be formed corresponding to the protrusion 33 b of the ohmic contact layer 33 .

[0087] Although not shown in the figure, when forming the through hole 39a, a component separation region, such as a cutting line, for separating a plurality of component regions formed on the substrate 21 may be formed together. The cutting line is formed by etching the surface protection layer 35 and the upper insulating layer 39, and can prevent the surface protection layer 39 and the upper insulating layer 39 from peeling off when performing a cutting process for separating components later.

[0088] Then, form Figure 1 The pad 40 and the connecting portion 41 are as shown. The pad 40 and the connecting portion 41 can be formed by lift-off technology, for example, can be formed of Ti / Pt / Au.

[0089] Afterwards, the individual components are separated along the cutting lines to complete the Figure 1 In addition, before the substrate 21 is divided, an n-pad may be formed under the substrate 21.

[0090] Figure 7 is a schematic top view of a VCSEL according to yet another embodiment of the present disclosure, Figure 8a It is enlarged to show Figure 7 A schematic top view of a portion of an emitter array, Figure 8b It is along Figure 8a The cross-sectional view taken along the cutting line BB of Figure 8c It is along Figure 8a Cross-sectional view taken along the cutting line CC.

[0091] Reference Figure 7 , Figure 8a , Figure 8b as well as Figure 8c The VCSEL 200 of this embodiment is different from the reference Figure 1 , Figure 2a as well as Figure 2b The VCSEL 100 described is substantially similar, including a plurality of emitter arrays 250, and thus differs in that the shape of the pad 40 is changed. To avoid repetition, the same contents are omitted.

[0092] As shown, emitters may be arranged in a honeycomb shape on substrate 21. Emitter array region 250 may be surrounded by ion implantation-based insulating region 37, and pad 40 may be located on insulating region 37. Pad 40 may be formed on one side of substrate 21 adjacent to array region 250.

[0093] like Figure 8a As shown, lines for indicating the boundary regions of ion implantation are shown in each emitter region, but since the lines in the emitter array region overlap each other, the insulating region 37 based on ion implantation is not formed in the emitter array region 250. That is, ion implantation is performed only outside the boundary line surrounding the outside of the emitter array region 250 to form the insulating region 37.

[0094] Each emitter is as shown in the reference Figure 1 , Figure 2a as well as Figure 2b As described above, it includes a lower reflector 25, an active layer 27, an aperture forming layer 29, and an upper reflector 31. In addition, the aperture forming layer 29 includes an oxide layer 29x and a window layer 29w, and the current flow is limited in the window layer 29w. The basic structure of each emitter is the same as the emitter 150 described above, except for the insulating region 37 based on ion implantation.

[0095] In addition, an ohmic contact layer 33 may be formed in each emitter, and the ohmic contact layer 33 may include a partially annular circular portion 33a and a protrusion 33b as described in the previous embodiment. In addition, in each emitter region, an oxidation hole 29a is arranged between the protrusions 33b, and a through hole 39a is formed corresponding to the protrusion 33b. The oxidation hole 29a and the through hole 39a formed in each emitter are the same as those formed in the emitter 150 of the embodiment described above. In particular, the oxidation hole 29a is formed separately according to each emitter, so that the size of the oxidation hole 29a can be made smaller than the size of the protrusion 33b, thereby improving the reliability of the element. In addition, the oxidation hole 29a is formed in an isolated area surrounded by an insulating area 37 formed by ion implantation. Therefore, it is possible to prevent defects from moving to the vicinity of the window layer 29w during the oxidation process, and the reliability of the element can be improved.

[0096] On the other hand, the connection portion 41 connecting the pad 40 and the ohmic contact layer 33 can be connected to each emitter through the through hole 39a. The emitters can all be connected in parallel. However, in the previous embodiment, it is described that the connection portion 41 has a partial ring shape, but in this embodiment, since the connection portion 41 is connected to multiple emitters, it is difficult to form a partial ring shape. As shown in the figure, it can have a mesh shape forming a circular opening portion 41a.

[0097] The method of manufacturing the VCSEL 200 having a reflector array is substantially similar to the method of manufacturing the VCSEL 100 described above, and thus detailed description thereof is omitted.

[0098] Figure 9a 2 is a schematic top view for explaining an oxide hole 29a for forming an oxide layer according to an embodiment of the present disclosure. Figure 9b to Figure 9d It is a schematic plan view for explaining various modified examples of oxidation holes for forming an oxide layer.

[0099] Reference Figure 9a , the oxidation hole 29a is formed in the isolated region surrounded by the insulating region 37 based on ion implantation. As shown in the above-described embodiment, the oxidation hole 29a can be formed to have a circular or elliptical shape. In particular, six oxidation holes 29a can be formed, thereby oxidizing the aperture forming layer 29 to form an oxidation layer 29x, and through the oxidation layer 29x, a window layer 29w is formed in the isolated region. The window layer 29w is formed in a substantially circular shape.

[0100] The shape and arrangement of the oxidation holes 29a can be modified in many ways. Figure 9b As shown, the oxidation holes 129a may have a square or rectangular shape and be arranged at positions corresponding to the vertices of a regular hexagon. Fig.9c As shown, the oxidation hole 129b has a quadrilateral shape, and the side close to the center of the isolated area can be formed concave. Figure 9d As shown, eight oxidation holes 129c may be arranged at positions corresponding to the vertices of a regular octagon.

[0101] On the other hand, the circular or elliptical oxidation hole 29a is convenient to form using pattern and timing technology, and can also improve the stability of the upper insulating layer 39 or the connecting portion 41 formed thereon. However, the shape of the oxidation hole 29a is not limited to a circular or elliptical shape in the present disclosure, and can also be deformed into a quadrilateral or other shapes as described above.

[0102] Although various embodiments of the present disclosure have been described above, the present invention is not limited to these embodiments. In addition, the content or constituent elements described for one embodiment may also be applied to other embodiments without departing from the technical concept of the present invention.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: substrate; A plurality of emitters are arranged on the substrate; as well as an upper insulating layer covering the plurality of emitters; The pad and the connecting portion are formed on one side of the substrate adjacent to the plurality of emitters. Wherein, the plurality of emitters include: Lower reflector; Upper reflector; An ohmic contact layer, arranged on the upper reflector; an active layer, disposed between the lower reflector and the upper reflector; an aperture forming layer, interposed between the upper reflecting mirror and the active layer, and having an oxide layer and a window layer surrounded by the oxide layer; and an oxidation hole penetrating the upper reflector, the aperture forming layer, the active layer and a portion of the lower reflector; a plurality of through holes penetrating the upper insulating layer to expose the ohmic contact layer; The connection portion extends from the pad and is electrically connected to the ohmic contact layer through the through hole and covers the oxidation hole. The oxidation holes are covered by the upper insulating layer, The connecting portion includes a partially annular circular portion formed along the ohmic contact layer, The connecting portion covers the upper insulating layer, The plurality of emitters are arranged in a honeycomb shape.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: The region where the plurality of emitters are arranged is surrounded by an insulating region formed by ion implantation.

3. The vertical cavity surface emitting laser according to claim 1, characterized in that: The ohmic contact layer includes a circular portion in an annular shape and a protruding portion protruding toward an outer side of the circular portion.

4. The vertical cavity surface emitting laser according to claim 3, characterized in that: The annular shape is a partial annular shape obtained by cutting a portion of the annular shape.

5. The vertical cavity surface emitting laser according to claim 4, characterized in that: The oxidation holes are arranged between the projections.

6. The vertical cavity surface emitting laser according to claim 5, characterized in that: The oxidation hole has a smaller width than the protrusion.

7. The vertical cavity surface emitting laser according to claim 4, characterized in that: The plurality of emitters further include: a surface protection layer covering the ohmic contact layer and the upper reflector, Wherein, the upper insulating layer is arranged on the surface protection layer, The oxidation pores penetrate the surface protection layer.

8. The vertical cavity surface emitting laser according to claim 7, characterized in that: The plurality of through holes penetrate the upper insulating layer and the surface protection layer to expose the ohmic contact layer. The through holes are arranged corresponding to the protruding portions.

9. The vertical cavity surface emitting laser according to claim 2, characterized in that: The pad is arranged above the insulating region.

10. The vertical cavity surface emitting laser according to claim 1, characterized in that: The oxidation pores have a circular or quadrilateral shape.

11. The vertical cavity surface emitting laser according to claim 9, characterized in that: The connection portion has a mesh shape including circular openings corresponding to the emitters.

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