The present disclosure relates to an emitter array and, more particularly, to configuration of an emitter pattern on an emitter array.
A vertical-emitting device, such as a vertical cavity surface emitting laser (VCSEL), is a laser in which a beam is emitted in a direction perpendicular to a surface of a substrate (e.g., vertically from a surface of a semi-conductor wafer). Multiple vertical-emitting devices may be arranged in an array with a common substrate.
According to some possible implementations, a die may comprise: a plurality of adjacent emitters; and a potential dislocation line, wherein the plurality of adjacent emitters and the potential dislocation line are offset from each other within a range of angles based on a relative rotation of the plurality of adjacent emitters and the potential dislocation line.
According to some possible implementations, a vertical cavity surface emitting laser (VCSEL) array may comprise: a plurality of adjacent VCSELs; and a potential dislocation line, wherein the plurality of adjacent VCSELs and the potential dislocation line are offset from each other based on a relative rotation of a die associated with the VCSEL array and the potential dislocation line.
According to some possible implementations, a wafer may comprise: a plurality of die that include a plurality of adjacent emitters; and a potential dislocation line, wherein the plurality of adjacent emitters and the potential dislocation line are offset from each other based on a relative rotation of the plurality of adjacent emitters and the potential dislocation line.
The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.
An emitter array may be arranged on a die in regular evenly spaced patterns (e.g., for optimal power and temperature profile across the emitter array). Often, an emitter pattern of the emitter array is aligned with potential dislocation lines of the die (e.g., lines along which dislocations are likely to propagate). In some cases, when a defect in the die propagates along a potential dislocation line, the defect may intersect one or more emitters of the emitter array based on the emitter pattern of the emitter array being aligned with a potential dislocation line (e.g., thereby causing the one or more emitters to fail, to produce less than a threshold amount of optical output, to produce less than a threshold amount of power, etc.). If a threshold quantity of emitters are intersected (or if a threshold quantity of adjacent emitters are intersected), the defect may cause a failure of the entire emitter array.
Some implementations described herein provide a die where emitter (e.g., adjacent emitters) on the die and a potential dislocation line of the die are offset from each other within a range of angles based on a relative rotation of the emitters and the potential dislocation line. In this way, the relative rotation of the emitters and the potential dislocation line reduces a quantity of emitters (or adjacent emitters) that could be intersected by a defect propagating along the potential dislocation line. This improves a reliability of an emitter array by reducing or eliminating a likelihood that the emitter array fails due to propagation of a defect. In addition, this conserves costs associated with replacing an emitter array when a threshold quantity of emitters and/or a threshold quantity of adjacent emitters fail. Further, this improves a quality of an emitter array by reducing or eliminating potential intersection of a defect with the emitters of the emitter array.
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As further shown, emitter 100 includes an optical aperture 108 in a portion of the emitter within the inner radius of the partial ring-shape of P-Ohmic metal layer 104. Emitter 100 emits a laser beam via optical aperture 108. As further shown, emitter 100 also includes a current confinement aperture 110 (e.g., an oxide aperture formed by an oxidation layer (not shown) of emitter 100). Current confinement aperture 110 is formed below optical aperture 108.
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The number and arrangement of layers shown in
Notably, while the design of emitter 100 is described as including a vertical cavity surface emitting laser (VCSEL), other implementations are possible. For example, the design of emitter 100 may apply in the context of another type of optical device, such as a light emitting diode (LED), or another type of vertical emitting (e.g., top emitting or bottom emitting) optical device. Additionally, the design of emitter 100 may apply to emitters of any wavelength, power level, emission profile, or the like. In other words, emitter 100 is not particular to an emitter with a given performance characteristic.
Backside cathode layer 128 may include a layer that makes electrical contact with substrate layer 126. For example, backside cathode layer 128 may include an annealed metallization layer, such as an AuGeNi layer, a PdGeAu layer, or the like.
Substrate layer 126 may include a base substrate layer upon which epitaxial layers are grown. For example, substrate layer 126 may include a semiconductor layer, such as a GaAs layer, an InP layer, and/or the like.
Bottom mirror 124 may include a bottom reflector layer of emitter 100. For example, bottom mirror 124 may include a distributed Bragg reflector (DBR).
Active region 122 may include a layer that confines electrons and defines an emission wavelength of emitter 100. For example, active region 122 may be a quantum well.
Oxidation layer 120 may include an oxide layer that provides optical and electrical confinement of emitter 100. In some implementations, oxidation layer 120 may be formed as a result of wet oxidation of an epitaxial layer. For example, oxidation layer 120 may be an Al2O3 layer formed as a result of oxidation of an AlAs or AlGaAs layer. Oxidation trench 112 may include openings that allow oxygen (e.g., dry oxygen, wet oxygen) to access the epitaxial layer from which oxidation layer 120 is formed.
Current confinement aperture 110 may include an optically active aperture defined by oxidation layer 120. A size of current confinement aperture 110 may range, for example, from approximately 6.0 μm to approximately 14.0 μm. In some implementations, a size of current confinement aperture 110 may depend on a width of oxidation trench 112 that surrounds emitter 100. For example, oxidation trench 112 may be etched to expose the epitaxial layer from which oxidation layer 120 is formed. Here, before dielectric passivation/mirror layer 114 is deposited, oxidation of the epitaxial layer may occur for a particular distance (e.g., identified as do in
Top mirror 118 may include a top reflector layer of emitter 100. For example, top mirror 118 may include a DBR.
Implant isolation material 116 may include a material that provides electrical isolation. For example, implant isolation material 116 may include an ion implanted material, such as an H implanted material or a Hydrogen/Proton implanted material. In some implementations, implant isolation material 116 may define implant protection layer 102.
Dielectric passivation/mirror layer 114 may include a layer that acts as a protective passivation layer and that acts as an additional DBR. For example, dielectric passivation/mirror layer 114 may include one or more sub-layers (e.g., a SiO2 layer, a Si3N4 layer) deposited (e.g., via chemical vapor deposition) on one or more other layers of emitter 100.
As shown, dielectric passivation/mirror layer 114 may include one or more dielectric via openings 106 that provide electrical access to P-Ohmic metal layer 104. Optical aperture 108 may include a portion of dielectric passivation/mirror layer 114 over current confinement aperture 110 via which light may be emitted.
P-Ohmic metal layer 104 may include a layer that makes electrical contact through which electrical current may flow. For example, P-Ohmic metal layer 104 may include a TiAu layer, a TiPtAu layer, or the like, through which electrical current may flow (e.g., via a bondpad (not shown) that contacts P-Ohmic metal layer 104 through dielectric via openings 106).
In some implementations, emitter 100 may be manufactured using a series of steps. For example, bottom mirror 124, active region 122, oxidation layer 120, and top mirror 118 may be epitaxially grown on substrate layer 126, after which P-Ohmic metal layer 104 may be deposited on top mirror 118. Next, oxidation trench 112 may be etched to expose oxidation layer 120 for oxidation. Implant isolation material 116 may be created via ion implantation, after which dielectric passivation/mirror layer 114 may be deposited. Dielectric via openings 106 may be etched in dielectric passivation/mirror layer 114 (e.g., to expose P-Ohmic metal layer for contact). Plating, seeding, and etching may be performed, after which substrate layer 126 may be thinned and/or lapped to a target thickness. Finally, backside cathode layer 128 may be deposited on a bottom side of substrate layer 126.
The number, arrangement, thicknesses, order, symmetry, or the like, of layers shown in
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As shown by reference number 212, the offset between the pattern of emitters 206 and potential dislocation line 208 may be within a range of angles. For example, the range of angles may be one degree to 15 degrees (inclusive). In some implementations, an angle of offset for a particular emitter array 202 may be determined based on a dimension of emitters 206 in emitter array 202, a dimension of a sub-array (e.g., a row of emitters 206, a column of emitters 206, a group of emitters 206 that form a particular shape, and/or the like) of emitter array 202, and/or the like. For example, the angle of offset may be based on a diameter of emitter 206 in emitter array 202 (e.g., a larger relative diameter may correspond to a larger relative angle of offset), a spacing between adjacent emitters 206 (e.g., a larger relative spacing may correspond to a smaller relative angle of offset), a distance between ends of a sub-array of emitter 202 (e.g., ends of a row or a column of emitters 206), a spacing between adjacent sub-arrays (e.g., a larger relative spacing may permit a larger relative angle of offset), a quantity of emitters 206 that need to be offset from potential dislocation line 208 (e.g., a higher relative quantity may correspond to a larger relative angle of offset), and/or the like.
As shown by reference number 214, by offsetting emitters 206 and potential dislocation line 208 from each other, potential dislocation line 208 intersects three emitters 206 in a row of emitters 206 (e.g., three adjacent emitters 206), rather than intersecting all emitters 206 in the row as would be the case if emitter 202 had been manufactured in a normal manner where the pattern of emitters 206 was aligned with potential dislocation line 208. Various criteria could be used to determine the offset such as: reducing intersection of potential dislocation 208 with a threshold quantity of emitters 206 in a row (e.g., a single emitter 206, three or fewer emitters 206, five or fewer emitters 206, and/or the like), a threshold quantity of adjacent emitters 206 in the row (e.g., two adjacent emitters 206, three or fewer adjacent emitters 206, five or fewer adjacent emitters 206, and/or the like), and/or the like. In some implementations, offsetting emitters 206 and potential dislocation line 208 in the manner described herein may prevent emitters 206 from outputting less than approximately 50 percent of an expected amount of power (e.g., based on avoiding potential dislocation line 208).
In this way, a relative rotation between a pattern of emitters 206 (e.g., adjacent emitters 206) and die 204 offsets the pattern of emitters 206 and potential dislocation lines 208 within a range of angles. This reduces a quantity of emitters 206 and/or adjacent emitters 206 that could be intersected by propagation of a defect along potential dislocation line 208. In addition, this reduces a likelihood of a failure of a threshold quantity of emitters 206 and/or adjacent emitters 206, thereby reducing or eliminating a likelihood of failure of a device associated with emitter array 202. Further, this improves a quality of an optical beam from emitter array 202 by facilitating generation of a more uniform optical beam. Further, this reduces a likelihood of failure of emitters 206 without having to increase a distance between adjacent emitters 206 to reduce the likelihood of failure.
As indicated above,
As shown by reference number 304, emitters 206 of emitter array 302 may be substantially aligned with each other and/or with potential dislocation line 208. For example, rows of emitters 206 of emitter array 302 may be aligned with a crystallographic axis of emitter array 302. As shown by reference number 306, potential dislocation line 208 intersects a set of adjacent emitters 206 (e.g., three adjacent emitters 206) based on emitters 206 being substantially aligned with each other and/or with potential dislocation line 208. In some implementations, potential dislocation line 208 may intersect a threshold quantity of emitters 206 and/or a threshold quantity of adjacent emitters 206 to cause emitter array 302 to fail (e.g., to fail to output a threshold amount of optical power).
Reference number 308 shows a portion of emitter array 202 in contrast to emitter array 302 described above. As shown by reference number 310, emitters 206 of emitter array 202 are not substantially aligned (e.g., are offset from each other). For example, emitters 206 may be offset from each other based on a dislocation angle of potential dislocation line 208, an expected, or maximum, diameter of emitters 206, and/or the distance between emitter centers of emitters 206 of emitter array 202. Continuing with the previous example, adjacent emitters 206 may be offset in a north-south direction by approximately 2.7 micrometers (μm) based on a 1.6 degree dislocation angle of potential dislocation line 208, a 47 μm distance between adjacent emitters 206, and an eight micrometer expected diameter of emitters 206. This may prevent damage to more than two adjacent emitters 206. For example, as shown by reference number 312, potential dislocation line 208 may not intersect a first emitter 206. Additionally, or alternatively, and as another example, potential dislocation line 208 may intersect a second emitter 206 (as shown by reference number 314). Additionally, or alternatively, and as another example, potential dislocation line 208 may intersect an edge of a third emitter 206 (as shown by reference number 316). Continuing with the previous example, although potential dislocation line 208 intersects a portion of the third emitter 206, a defect propagating along potential dislocation line 208 may not cause enough damage to the third emitter 206 to cause the third emitter 206 to fail, to fail to output a threshold amount of optical output, and/or the like.
In some implementations, emitters 206 may be offset by a different amount than that described above. For example, depending on a distance between rows of emitters 206 of emitter array 202, adjacent emitters 206 may be offset in a north-south direction by approximately 5.5 μm. This may prevent any adjacent emitters 206 from being intersected by potential dislocation line 208, thereby further reducing a quantity of emitters 206 that could be intersected by a defect propagating along potential dislocation line 208.
As indicated above,
As shown by reference number 402, emitter array 202-1 may include a rectangular two-dimensional pattern of emitters 206. As shown by reference number 404, emitter array 202-2 may include an offset two-dimensional pattern of emitters 206. In this way, a relative rotation of a pattern of emitters 206 and potential dislocation line 208 can be used with various patterns for emitters 206 to offset emitters 206 from potential dislocation line 208.
As indicated above,
Although described in the context of an emitter array 202 that includes a regular pattern of emitters 206, the implementations described herein may apply equally to an emitter array 202 that includes a semi-random pattern of emitters 206, a segmented pattern of emitters 206, and/or the like. For example, a pattern of emitters 206 may include a random pattern of emitters 206 and a regular pattern of emitters 206 that are interleaved with each other (e.g., a horizontal line of regularly spaced emitters 206 and/or a vertical line of regularly spaced emitters 206 interleaved with a random pattern of emitters 206). In this case, adjacent emitters 206 of the regular pattern of emitters 206 and a potential dislocation line 208 may be offset from each other to minimize a quantity of emitters 206 of the regular pattern of emitters 206 that intersect the potential dislocation line 208.
In this way, emitters 206 (e.g., adjacent emitters 206) and potential dislocation line 208 may be offset from each other within a range of angles via a relative rotation between emitters 206 and potential dislocation line 208. This reduces a quantity of emitters 206 that could be potentially intersected by a defect in die 204, thereby improving a reliability of emitter array 202. In addition, this reduces or eliminates a need to increase a distance between emitters 206 to reduce a likelihood that emitters 206 are intersected by potential dislocation line 208, thereby maintaining a footprint of emitter array 202. Further, this reduces or eliminates a need for emitter array 202 to be replaced due to a failure of emitters 206 (e.g., due to propagation of a defect along potential dislocation line 208 causing failure of one or more emitters 206), thereby conserving costs related to replacing emitter array 202.
The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations.
As used herein, the term component is intended to be broadly construed as hardware, firmware, or a combination of hardware and software.
Some implementations are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, more than the threshold, higher than the threshold, greater than or equal to the threshold, less than the threshold, fewer than the threshold, lower than the threshold, less than or equal to the threshold, equal to the threshold, or the like.
Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible implementations includes each dependent claim in combination with every other claim in the claim set.
No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.), and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/586,000, filed on Nov. 14, 2017, the content of which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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62586000 | Nov 2017 | US |