Patent ID: 12237647

DETAILED DESCRIPTION

The present disclosure provides many different embodiments, or examples, for implementing different features of this disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

A semiconductor vertical cavity surface emitting laser (VCSEL) device includes top and bottom electrodes, with distributed Bragg reflectors (DBRs) and an optically active region arranged between the top and bottom electrodes. The DBRs comprise DBR layers, which are comprised of a stack of alternating layers. In conventional VCSEL device fabrication, an etching process is performed to form outer sidewalls of the DBR layers and the optically active region. Then, an oxidation process is performed, causing oxidation to occur on the outer sidewalls of the DBR layers and the optically active region. After the oxidation process, a sidewall spacer is formed to cover the oxidized outer sidewalls of the DBR layers and the optically active region. Although use of this fabrication method is widely adopted, the oxidation in the DBR layers results in a decrease in thermal conductivity and a decrease in the operable wavelength bandwidth for the device. This results in a higher thermal temperature in the optically active region during normal operation. As the temperature of the optically active region increases, the operating wavelength will increase respectively. This causes an unwanted defect as the device will no longer operate at the desired wavelength.

In some embodiments of the present disclosure, to prevent the oxidation in the DBR layers, sidewall spacers may be introduced at intermediate steps of the above process. First, a substrate is formed over a first electrode and a second set of DBR layers is formed over the substrate. An optically active region is formed over the second set of DBR layers. Then, a first set of DBR layers is formed over the optically active region. The new process involves an etching process performed through the first set of DBR layers. Then, a first sidewall spacer formed around sidewalls of the first set of DBR layers. An oxidation process is then performed after the first sidewall spacer has been formed, where the oxidation will only form in the optically active region. Then, an etching process is performed through the optically active region and the second set of DBR layers below the optically active region. Finally, a second sidewall spacer is formed around outer sidewalls of the first sidewall spacer, second set of DBR layers, and the optically active region. This prevents any oxidation from forming in any of the DBR layers, therefore preventing the defect related to oxidation in the DBR layers.

Referring toFIG.1, a cross-sectional view of a VCSEL device100in accordance with some embodiments is provided. The VCSEL device100includes a bottom electrode101with a substrate102disposed over the bottom electrode101. The substrate102may be, for example, a bulk substrate (e.g., a bulk silicon substrate), a silicon-on-insulator (SOI) substrate, or the like. In some embodiments, the substrate102is a layer of gallium arsenide. A first reflector104is disposed over the substrate102. An optically active region106, which includes a central optically active region107comprising a metal (un-oxidized) and a peripheral optically active region108comprising an oxidized version of the metal, is disposed over the first reflector104. The first reflector104and the peripheral optically active region106have outer sidewalls that are aligned. A second reflector110is disposed over the optically active region106, and a masking layer112is disposed over the second reflector110. A top electrode114with a central aperture is disposed over the masking layer112. A first spacer116is disposed over the optically active region106and covers outer sidewalls of the second reflector110and masking layer112. A second spacer118disposed over the substrate102and covers outer sidewalls of the first spacer116, the optically active region106, and the first reflector104.

In some embodiments, the bottom electrode101comprises copper, iron, cobalt, nickel, titanium, or the like. In some embodiments, the top electrode114comprises copper, iron, cobalt, nickel, titanium, or the like; and can be made of the same material or a different material than the bottom electrode101. In some embodiments, the masking layer112may, for example, be or comprise a photo resist, silicon oxide, or the like formed to a thickness within a range of between approximately 1.5 micrometers to approximately 4 micrometers. In some embodiments, the first spacer116comprises a nitride, such as titanium nitride or silicon nitride formed to a thickness within a range of between approximately 1000 and approximately 2000 micrometers. In some embodiments, the second spacer118comprises a nitride, such as titanium nitride or silicon nitride formed to a thickness within a range of between approximately 1000 and approximately 2000 micrometers. In some embodiments, the central region107of the optically active region106comprises a metal, such as aluminum; while the peripheral region108comprises an oxidized version of the metal, such as aluminum oxide. In some embodiments, the central region of optically active region106comprises a high concentration of aluminum, for example ranging from 96% to 100% aluminum, which can promote higher thermal conductivity for the optically active region than lower concentrations of aluminum.

During operation of the VCSEL device100, a bias is applied across the bottom electrode101and top electrode114, which causes the central optically active region107to emit light120. The first and second reflectors104,110are positioned so that the generated light120reflects multiple times between the first and second reflectors104,110, and due to the effects of interference, some patterns and/or frequencies of light are amplified by constructive interference while other patterns and/or frequencies of light are attenuated by destructive interference. In this way, after multiple reflections back and forth between the first reflector104and the second reflector110, the light120passes out through the aperture in the top electrode114with a pre-determined wavelength.

While the VCSEL device is generating this light120, heat is also generated. To better dissipate this heat, the first spacer116has an innermost sidewall that entirely covers an outer sidewall of the second reflector110. Moreover, the first spacer116is formed in direct contact with un-oxidized material on the outer sidewall of the second reflector110. Compared to previous approaches where outer sidewalls of the second reflector110were oxidized, embodiments of the present disclosure where the second reflector110remains entirely un-oxidized within the confines of the first spacer116provides the second reflector110with a higher thermal conductivity. Because of this, the second reflector110is made entirely of un-oxidized material, which allows the second reflector110to more efficiently dissipate heat. Therefore, compared to previous VCSELs, the VCSEL device100ofFIG.1is able to maintain a more constant temperature during operation and correspondingly outputs light120at a more consistent wavelength.

FIG.2illustrates a cross-sectional view of some additional embodiments of a VCSEL device200. The first reflector104and second reflector110are comprised of alternating layers of two different materials with different refractive indices. The stack of alternating layers comprise of a first layer202and a second layer204. In some embodiments, the first layer202may be comprised of Gallium arsenide (GaAs) and the second layer204may be comprised of Aluminum arsenide (AlAs). In some embodiments, the first reflector104and the second reflector110are each comprised of 40 pairs or greater of alternating layers of the first layer202and the second layer204.

In some embodiments, the first reflector104and second reflector110may be distributed Bragg reflectors (DBRs) containing a stack of pairs206. The stack of pairs206comprise of a first layer202and a second layer204. Each pair206may be about one-half wavelength thick, where a wavelength corresponds to the wavelength emitted from the VCSEL device. Each individual layer, first layer202and second layer204, may be about one-fourth wavelength thick. For example, in some embodiments, the wavelength emitted from the VCSEL device is 840 nm, and the pair206has a thickness of approximately 420 nm. Each individual layer, first layer202and second layer204, of the pair206may be comprised of different materials with different concentrations. In some embodiments, the first layer202comprises Aluminum Gallium Arsenide with an Aluminum concentration of 10% (Al0.1GaAs), the second layer204comprises Aluminum Gallium Arsenide with an Aluminum concentration of 90% (Al0.9GaAs). In other embodiments, the first layer202comprises Gallium Arsenide (GaAs), the second layer204comprises Aluminum Arsenide (AlAs). These other embodiments where the first layer is GaAs and the second layer is AlAs have a lower thermal resistivity than embodiments where the first layer is Al0.1GaAs and the second layer is Al0.9GaAs.

FIG.3illustrates a cross-sectional view of some additional embodiments of a VCSEL device300. Outer sidewalls of the second reflector110comprise a plurality of recesses. Inner sidewalls of the first spacer116comprise a plurality of protrusions that engagedly meet the plurality of recesses in the second reflector110. Outer sidewalls of the first spacer116comprise a second plurality of recesses. In some embodiments, the plurality of protrusions and the plurality of recesses comprise of semicircles. In some embodiments, the plurality of protrusions and the plurality of recesses comprise of triangles. Outer sidewalls of the first layer202and the second layer204comprise a recess. In some embodiments, outer sidewalls of the first layer202and the second layer204comprise a plurality of recesses (not shown).

FIG.4illustrates a cross-sectional view of some additional embodiments of a VCSEL device400. Outer sidewalls of the second reflector110comprise a plurality of recesses. Inner sidewalls of the first spacer116comprise a plurality of protrusions that engagedly meet the plurality of recesses in the second reflector110. Outer sidewalls of the first spacer116comprise a second plurality of recesses. Inner sidewalls of the second spacer118comprise a second plurality of protrusions that directly contact the second plurality of recesses of the first spacer116. Outer sidewalls of the second spacer118comprise a third plurality of recesses. In some embodiments, the plurality of protrusions and the plurality of recesses comprise semicircles. Outer sidewalls of the first layer202and the second layer204comprise a recess.

FIG.5illustrates a cross-sectional view of some additional embodiments of a VCSEL device500. Outer sidewalls of the second reflector110comprise a plurality of recesses. Inner sidewalls of the first spacer116comprise a plurality of protrusions that meet the plurality of recesses in the second reflector110. Outer sidewalls of the first spacer116comprise a second plurality of recesses. Outer sidewalls of the optically active region106comprise a fourth plurality of recesses. Outer sidewalls of the first reflector104comprise a fifth plurality of recesses. Inner sidewalls of the second spacer118comprise a second plurality of protrusions that directly contact the second plurality of recesses of the first spacer116, the fourth plurality of recesses of the optically active region106, and the fifth plurality of recesses of the first reflector104. Outer sidewalls of the second spacer118comprise a third plurality of recesses. In some embodiments, the plurality of protrusions and the plurality of recesses comprise of semicircles. Outer sidewalls of the first layer202and the second layer204comprise a recess. In some embodiments, outer sidewalls of the first layer202and the second layer204comprise a plurality of recesses (not shown).

FIG.6illustrates a cross-sectional view of some additional embodiments of a VCSEL device600. Outer sidewalls of the second reflector110comprise a plurality of recesses. Outer sidewalls of the masking layer112comprise a sixth plurality of recesses. Inner sidewalls of the first spacer116comprise a plurality of protrusions that meet the plurality of recesses in the second reflector110, and the sixth plurality of recesses in the first spacer116. Outer sidewalls of the first spacer116comprise a second plurality of recesses. Outer sidewalls of the optically active region106comprise a fourth plurality of recesses. Outer sidewalls of the first reflector104comprise a fifth plurality of recesses. Inner sidewalls of the second spacer118comprise a second plurality of protrusions that directly contact the second plurality of recesses of the first spacer116, the fourth plurality of recesses of the optically active region106, and the fifth plurality of recesses of the first reflector104. Outer sidewalls of the second spacer118comprise a third plurality of recesses. In some embodiments, the plurality of protrusions and the plurality of recesses comprise of semicircles. Outer sidewalls of the first layer202and the second layer204comprise a recess. In some embodiments, outer sidewalls of the first layer202and the second layer204comprise a plurality of recesses (not shown).

FIG.7illustrates a cross-sectional view of some additional embodiments of a VCSEL device700. Compared to the VCSEL device ofFIG.1, the VCSEL device700has flipped the positions of the bottom electrode101and substrate102. It will be appreciated that positions of the bottom electrode101and substrate102can also be flipped in the other embodiments illustrated and/or discussed herein, and these variations are contemplated as falling within the scope of the present disclosure.

FIG.8Aillustrates a perspective view of some embodiments of a laser device800aincluding an array of VCSEL devices with a cross-sectional cut shown for some of the VCSEL devices. In some embodiments, a VCSEL device801may be comprised within an array having a plurality of VCSEL devices arranged in rows and columns. The VCSEL device801includes a bottom electrode101with a substrate102disposed over the bottom electrode101. A first reflector104is disposed over the substrate102. An optically active region106is disposed over the first reflector104. The first reflector104and the optically active region106have outer sidewalls that are aligned. An oxidized peripheral region108of the optically active region106is comprised of oxidation. A central region107of the optically active region106does not contain oxidation. A second reflector110disposed over the optically active region106. A masking layer112disposed over the second reflector110. An electrode114is formed over the masking layer112. In some embodiments the electrode114comprises an aperture through a center of the electrode114exposing an upper surface of the masking layer112. A first spacer116disposed over the optically active region106and covering outer sidewalls of the second reflector110and masking layer112. A second spacer118disposed over the bottom electrode101and covering outer sidewalls of the first spacer116, the optically active region106, and the first reflector104.

FIG.8Billustrates a graph800bcomprising a thermal resistivity curve810demonstrating thermal conductivity properties of embodiments of a VCSEL device, such as previously illustrated and described inFIGS.1-7. The thermal resistivity curve810reflects thermal resistivity of a compound comprising aluminum gallium arsenide, with a chemical formula AlxGax-1As. The x-axis ofFIG.8Brepresents the value of x in the above chemical formula. The y-axis ofFIG.8Brepresents increasing thermal resistivity (cm*K/W, e.g. centimeter*kelvin/watt) of the compound comprising AlxGax-1As. A VCSEL device comprising materials with low thermal conductivity will prevent heat from building up in an optically active region of the VCSEL device during operation, which will prevent the device from failing due to a shift in operating frequency from the buildup of heat in the optically active region.

More particularly inFIG.8Ba first point802corresponds to an x value of 0 and a second point808corresponds to an x value of 1. In some embodiments of a VCSEL device according to the present disclosure, for example, the first point802corresponds to a thermal resistivity of the first layer202(e.g. the first layer202comprises GaAs), the second point808corresponds to a thermal resistivity of the second layer204(e.g. the second layer204comprises AlAs). Therefore, in the above example, a combination of the first and second layers202,204will result in an overall low thermal resistivity for the VCSEL device. In some embodiments, a third point804represents a concentration of Al in the optically active region106. In some embodiments the concentration of Al in the optically active region106is less than the concentration of Al in the second layer204. For example, the concentration of Al in the optically active region106is 98% (e.g. Al0.98) while the concentration of Al in the second layer204is 100% (e.g. AlAs).

Additionally inFIG.8Ba range of x values between points806and812represent the range of x values in which DBR stacks within a second VCSEL device comprise oxidization. The range of x values between points806and812can be within the range of approximately 0.1 and 0.9, e.g. where a first layer in the DBR stacks comprises Al0.1Ga0.9As (e.g. x=0.1) and a second layer in the DBR stacks comprises Al0.9Ga0.1As (e.g. x=0.9). The thermal resistivity curve810between the points806and812depict a range of thermal resistivity of the compounds used to make the first and second layer in the DBR stacks of the second VCSEL device.

A thermal resistivity of a combination of the first and second layers of the second VCSEL device will be greater than the thermal resistivity of the combination of the first and second layers202,204of the VCSEL device according to the present disclosure. Therefore, the second VCSEL device that comprises oxidation in the DBR stacks suffers from endurance degradation due to a higher thermal resistivity in the DBR stacks. Thus, the VCSEL device according to the present disclosure has improved endurance due to a lower thermal resistivity, allowing the device to better dissipate heat within the optically active region during operation.

FIG.8Cillustrates a graph800ccomprising a pair of reflectance curves of embodiments of a VCSEL device, such as previously illustrated and described inFIGS.1-7. It can be appreciated that a VCSEL device could be designed for many different wavelengths, thereforeFIG.8Cand the associated wavelength values are merely an example. During operation of the VCSEL device, a voltage is applied across the device and the VCSEL device has an operating wavelength, monochromatic light will emit when the operating wavelength is at a resonance wavelength. The VCSEL device commonly has a range of resonance wavelengths called an operating bandwidth. During operation of the VSCEL device, heat will build up in an optically active region of the device and cause the operating wavelength to increase. As the heat increases, the operating wavelength can increase outside of the operating bandwidth and cause the VCSEL device to fail to emit monochromatic light. In regards toFIG.8Cthe operating bandwidth can be defined as any wavelength with a reflectance of 1.0, or any wavelength above a specific reflectance value such as a reflectance above approximately 0.75, 0.85, or 0.95.

More particularly inFIG.8Ca first reflectance curve818corresponds to a spectral reflectance of a VCSEL device according to the present disclosure. A first operating bandwidth818acorresponds to an operating bandwidth of the first reflectance curve818. In some embodiments the first operating bandwidth818ais between approximately 905 nm and approximately 985 nm. A second reflectance curve816corresponds to a spectral reflectance of a second VCSEL device that comprises oxidation in its DBR stacks. A second operating bandwidth816acorresponds to an operating bandwidth of the second reflectance curve816. In some embodiments the second operating bandwidth816ais between approximately 920 nm and approximately 965 nm. In comparison of the first and second reflectance curves818,816, the first operating bandwidth818acomprises a greater range of resonance wavelength values compared to the second operating bandwidth816a. Additional, a trough near a center of the first operating bandwidth818ahas a substantially greater reflectance value than a trough near a center of the second operating bandwidth816a. Therefore, during operation of the second VCSEL device, as heat builds up within an optically active region of the second VCSEL device an operating wavelength will increase outside of the second operating bandwidth816amore quickly than the VCSEL device according to the present disclosure. Thus, sidewall spacers in the VCSEL device according to the present disclosure increase the operating bandwidth of the VCSEL device and increases the device's ability to emit monochromatic light.

FIGS.9-16illustrate cross-sectional views900-1600of some embodiments of a method of forming a VCSEL device. Although the cross-sectional views900-1600shown inFIGS.9-16are described with reference to a method, it will be appreciated that the structures shown inFIGS.9-16are not limited to the method but rather may stand alone separate of the method. AlthoughFIGS.9-16are described as a series of acts, it will be appreciated that these acts are not limiting in that the order of the acts can be altered in other embodiments, and the methods disclosed are also applicable to other structures. In other embodiments, some acts that are illustrated and/or described may be omitted in whole or in part.

As shown in cross-sectional view900ofFIG.9, a bottom electrode101is formed on a lower surface of substrate102. In some embodiments, the bottom electrode101comprises Copper, Iron, Cobalt, Nickel, Titanium, or the like. The substrate102may be, for example, a bulk substrate (e.g., a bulk silicon substrate) or a silicon-on-insulator (SOI) substrate. A first reflective layer902is formed over the substrate102. The first reflective layer902is comprised of alternating layers of two different materials with different refractive indices. The stack of alternating layers for the first reflective layer902may comprise a third layer910, which may be comprised of Gallium arsenide (GaAs), and a fourth layer912, which may be comprised of Aluminum arsenide (AlAs). In some embodiments, the first reflective layer902is comprised of 40 pairs or greater of alternating layers of the third layer910and the fourth layer912. An optically active layer904is formed over the first reflective layer902. In some embodiments the optically active layer904comprises a metal, such as aluminum; and may comprise gallium and/or arsenide. In some embodiments, the optically active layer904comprises a high concentration of aluminum (e.g. at least 98%, up to 100%), the remaining concentration of the optically active layer904may be, for example, gallium in a concentration of approximately 0.5% to approximately 1.5% and/or arsenide in a concentration of approximately 0.5% to approximately 1.5% randomly distributed across the optically active layer904. A second reflective layer906is formed over the optically active layer904. The second reflective layer906comprises alternating layers of two different materials with different refractive indices. The stack of alternating layers for the second reflective layer906can comprise third layer910, which may be comprised of Gallium arsenide (GaAs), and the fourth layer912, which may be comprised of Aluminum arsenide (AlAs). A masking layer112is formed over the second reflective layer906. The masking layer112is patterned, for example by using photolithography, to cover a first portion of the second reflective layer906and leave a sacrificial portion908of the second reflective layer906exposed.

As shown in cross-sectional view1000ofFIG.10, an etching process1002is performed to etch the second reflective layer906and remove the sacrificial portion908to define a second reflector110. The etching process1002involves performing a first etch process to remove the sacrificial portion of the third layer910, thereby defining the first layer202, and using a second different etch process to remove the sacrificial portion of the fourth layer912, defining the second layer204. The alternation between the first etch process and the second etch process is repeated until an upper surface of the optically active layer904is exposed. In some embodiments, the first etch process involves a vertical etch or an anisotropic etch with a first etchant. In some embodiments, the second etch process involves an isotropic etch or a wet etch. In some embodiments, the first etchant is a different chemical than the second etchant.

In some embodiments, first etch initially leaves the third layer910with substantially vertical sidewalls, then the second etch bevels and/or recesses these sidewalls of the third layer910and also bevels and/or recesses sidewalls of the fourth layer912. In some embodiments, the second etch process etches more lateral material on the fourth layer912than the first etch process etches lateral material on the third layer910. This results in the outermost sidewalls of the first layer202having a greater maximum width than the outermost sidewalls of the second layer204(not shown). In some embodiments, the above process is used iteratively to propagate through each of the pairs in the second reflector110. This causes a first pair of the pair206to have a greater maximum width than a maximum width of a second pair of the pair206(not shown). The first pair is located above the second pair.

As shown in cross-sectional view1100ofFIG.11, a first spacer layer1102is formed over the optically active layer904and the masking layer112. The first spacer layer1102covers outer sidewalls of the second reflector110and outer sidewalls of the masking layer112. In some embodiments, the first spacer layer1102comprises a nitride, such as titanium nitride or silicon nitride formed to a thickness within a range of between approximately 750 and approximately 1000 micrometers.

As shown in cross-sectional view1200ofFIG.12, a portion of the first spacer layer1102is removed by exposing the first spacer layer1102to an etchant1204(e.g., a vertical or anisotropic etch, such as a plasma etch) to define a first spacer116. The first spacer116covers outer sidewalls of the masking layer112and outer sidewalls of the second reflector110. A lower surface of the first spacer116contacts the upper surface of the optically active layer904.

As shown in cross-sectional view1300ofFIG.13, a thermal oxidation process1304is performed on the optically active layer904. This thermal oxidation process leaves a central region107of the optically active layer904un-oxidized, and defines an oxidized peripheral region1302of the optically active layer904. The oxidized peripheral region1302extends under the first spacer116, and under the second reflector110. Thus, innermost sidewalls of the oxidized peripheral region1302of the optically active layer904extend below and within outermost sidewalls of the second reflector110. Innermost sidewalls of the oxidized peripheral region1302of the optically active layer904are in direct contact with outermost sidewalls of the central region107of the optically active layer904. In some embodiments, the central region107is un-oxidized.

As shown in cross-sectional view1400ofFIG.14, an etching process1402is performed to etch the optically active layer904to define an optically active region106and to etch the first reflective layer902to define a first reflector104. The etching process1402involves performing a third etch process to remove a portion of the optically active layer904, defining the optically active region106. Then, alternating between a first etch process to remove a portion of the third layer910, thereby defining the first layer202, and a second etch process to remove a portion of the fourth layer912, thereby defining the second layer204. The alternation between the first etch process and the second etch process is repeated until an upper surface of the substrate102is exposed. In some embodiments, the first etch process involves a vertical etch or an anisotropic etch with a first etchant. In some embodiments, the second etch process involves an isotropic etch or a wet etch with a second etchant. In some embodiments, the second etchant is a different chemical than the first etchant.

In some embodiments, first etch initially leaves the third layer910with substantially vertical sidewalls, then the second etch bevels and/or recesses these sidewalls of the third layer910and also bevels and/or recesses sidewalls of the fourth layer912. In some embodiments, the second etch process etches more lateral material on the fourth layer912than the first etch process etches lateral material on the third layer910. This results in the outermost sidewalls of the first layer202to have a greater maximum width than the outermost sidewalls of the second layer204(not shown). In some embodiments, the above process propagates through all of the pairs in the first reflector104. This causes a first pair of the pair206to have a greater maximum width than a maximum width of a second pair of the pair206(not shown). The first pair is located above the second pair.

As shown in cross-sectional view1500ofFIG.15, a second spacer layer1502is formed over the masking layer112, first spacer116, and the substrate102. The second spacer layer1502covers outermost sidewalls of the first spacer116, outermost sidewalls of the optically active region106, and outermost sidewalls of the first reflector104. In some embodiments, the second spacer layer1502comprises a nitride, such as titanium nitride or silicon nitride, and is formed to a thickness within a range of between approximately 750 and approximately 1000 micrometers.

As shown in cross-sectional view1600ofFIG.16, a portion of the second spacer layer1502is removed by exposing the second spacer layer1502to an etchant1602to define a second spacer118. The second spacer118covers outermost sidewalls of the first spacer116, outermost sidewalls of the optically active region106, and outermost sidewalls of the first reflector104. A lower surface of the second spacer118contacts the upper surface of the substrate102. An electrode114is formed over the masking layer112. In some embodiments the electrode114comprises an aperture through a center of the electrode114exposing an upper surface of the masking layer112. In some embodiments, the electrode114comprises Copper, Iron, Cobalt, Nickel, Titanium, or the like.

FIG.17illustrates a method1700of forming a VCSEL device in accordance with some embodiments. Although the method1700is illustrated and/or described as a series of acts or events, it will be appreciated that the method is not limited to the illustrated ordering or acts. Thus, in some embodiments, the acts may be carried out in different orders than illustrated, and/or may be carried out concurrently. Further, in some embodiments, the illustrated acts or events may be subdivided into multiple acts or events, which may be carried out at separate times or concurrently with other acts or sub-acts. In some embodiments, some illustrated acts or events may be omitted, and other un-illustrated acts or events may be included.

At1702, a first reflective layer is formed over a substrate.FIG.9illustrates a cross-sectional view900corresponding to some embodiments of act1702.

At1704, an optically active layer is formed over the first reflective layer.FIG.9illustrates a cross-sectional view900corresponding to some embodiments of act1704.

At1706, a second reflective layer is formed over the optically active layer.FIG.9illustrates a cross-sectional view900corresponding to some embodiments of act1706.

At1708, a masking layer is formed over the second reflective layer.FIG.9illustrates a cross-sectional view900corresponding to some embodiments of act1708.

At1710, a portion of the second reflective layer is removed, defining a second reflector and exposing an upper surface of the optically active layer.FIG.10illustrates a cross-sectional view1000corresponding to some embodiments of act1710.

At1712, a first spacer is formed covering outermost sidewalls of the second reflector and outermost sidewalls of the masking layer.FIGS.11and12illustrate a cross-sectional view1100and1200corresponding to some embodiments of act1712.

At1714, oxidation is formed in a peripheral region of the optically active layer.FIG.13illustrates a cross-sectional view1300corresponding to some embodiments of act1714.

At1716, a portion of the optically active layer is removed, defining an optically active region and remove a portion of the first reflective layer, defining a first reflector.FIG.14illustrates a cross-sectional view1400corresponding to some embodiments of act1716.

At1718, a second spacer is formed covering outer sidewalls of the first spacer, outer sidewalls of the optically active region and outer sidewalls of the first reflector.FIGS.15and16illustrate a cross-sectional view1500and1600corresponding to some embodiments of act1718.

At1720, an electrode is formed over the masking layer, where the electrode comprises an aperture through the center of the electrode.FIG.16illustrates a cross-sectional view1600corresponding to some embodiments of act1720.

Accordingly, in some embodiments, the present disclosure relates to a method of forming a VCSEL device that performs an oxidation process to produce oxidation in the optically active region and no oxidation forms in the first and second reflector.

In some embodiments, the present disclosure relates to a method for manufacturing a vertical cavity surface emitting laser. The method includes forming an optically active layer disposed over a first reflective layer; forming a second reflective layer disposed over the optically active layer; forming a masking layer disposed over the second reflective layer, the masking layer covers a reflector region of the second reflective layer, the masking layer leaves a sacrificial portion of the second reflective layer exposed; performing a first etch process to remove the sacrificial portion of the second reflective layer, defining a second reflector and exposing an upper surface of the optically active layer; forming a first spacer covering outer sidewalls of the second reflector and outer sidewalls of the masking layer, a lower surface of the first spacer contacts the upper surface of the optically active layer; performing an oxidation process with the first spacer in place to oxidize a peripheral region of the optically active layer while leaving a central region of the optically active layer un-oxidized; performing a second etch process to remove a portion of the oxidized peripheral region, defining an optically active region and removing a portion of the first reflective layer, defining a first reflector; forming a second spacer covering outer sidewalls of the first spacer, outer sidewalls of a remaining portion of the oxidized peripheral region, and outer sidewalls of the first reflector.

In some embodiments, the present disclosure relates to a vertical surface emitting laser (VCSEL) structure. A substrate disposed over a first electrode; a first reflector disposed over the substrate; an optically active region disposed over the first reflector, the first reflector and the optically active region have outer sidewalls that are aligned; a second reflector disposed over the optically active region, the optically active region is optically coupled to the first and second reflectors; a masking layer disposed over the second reflector; a second electrode disposed over the masking layer, the second electrode contains an aperture through a center of the second electrode exposing an upper surface of the masking layer; a first spacer covering outer sidewalls of the second reflector, a lower surface of the first spacer contacts an upper surface of the optically active region; a second spacer covering outer sidewalls of the first spacer, outer sidewalls of the optically active region, and outer sidewalls of the second reflector.

In some embodiments, the present disclosure relates to a vertical surface emitting laser (VCSEL) structure. A first reflector disposed over a substrate, the first reflector comprises a first aluminum arsenide layer, and a first gallium arsenide layer stacked over the first aluminum arsenide layer; an optically active region over the first reflector, the optically active region comprising a central region and a peripheral region surrounding the central region, the central region comprising aluminum, and the peripheral region comprising aluminum oxide, the peripheral region has outer sidewalls that are aligned with outer sidewalls of the first reflector; a second reflector disposed over the optically active region, the second reflector comprises a second aluminum arsenide layer, and a second gallium arsenide layer stacked over the second aluminum arsenide layer, the optically active region is optically coupled to the first and second reflectors; a masking layer disposed over the second reflector; a second electrode disposed over the masking layer, the second electrode contains an aperture through a center of the second electrode exposing an upper surface of the masking layer; a first spacer covering outer sidewalls of the second reflector, a lower surface of the first spacer contacts an upper surface of the peripheral region of the optically active region, inner sidewalls of the first spacer directly contact outer sidewalls of the second reflector without any oxidation material separating the first spacer from the second reflector; a second spacer covering outer sidewalls of the first spacer, the outer sidewalls of the peripheral region of the optically active region, and the outer sidewalls of the second reflector.

It will be appreciated that in this written description, as well as in the claims below, the terms “first”, “second”, “second”, “third” etc. are merely generic identifiers used for ease of description to distinguish between different elements of a figure or a series of figures. In and of themselves, these terms do not imply any temporal ordering or structural proximity for these elements, and are not intended to be descriptive of corresponding elements in different illustrated embodiments and/or un-illustrated embodiments. For example, “a first dielectric layer” described in connection with a first figure may not necessarily correspond to a “first dielectric layer” described in connection with another figure, and may not necessarily correspond to a “first dielectric layer” in an un-illustrated embodiment.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.