Patent Publication Number: US-2023147783-A1

Title: Dual junction led with non-overlapping segmentation

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 63/276,834, filed on Nov. 8, 2021, the entirety of which is hereby incorporated by reference herein. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to an illumination system, such as for a camera. 
     BACKGROUND OF THE DISCLOSURE 
     There is ongoing effort to improve illumination systems, such as for cameras. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a side view of an example of an illumination system, in accordance with some examples. 
         FIG.  2    shows a front view of an example of a dual junction LED array including first and second junctions that extend in a plane, in accordance with some examples. 
         FIG.  3    shows a front view of an example of a dual junction LED array including first and second junctions that extend in a plane, in accordance with some examples. 
         FIG.  4    shows a front view of an example of a dual junction LED array including first and second junctions that extend in a plane, in accordance with some examples. 
         FIG.  5    shows an example of a partially manufactured dual-junction LED array, at which a mirror layer has been deposited, in accordance with some examples. 
         FIG.  6    shows an example of a partially manufactured dual-junction LED array, at which a hardmask has been deposited, in accordance with some examples. 
         FIG.  7    shows an example of a partially manufactured dual-junction LED array, at which the hardmask has been pattern and etched, in accordance with some examples. 
         FIG.  8    shows an example of a partially manufactured dual-junction LED array, at which the dielectric spacers have been deposited on sidewalls of the vias, in accordance with some examples. 
         FIG.  9    shows an example of a partially manufactured dual-junction LED array, at which p-vias have been patterned and etched in the hardmask, in accordance with some examples. 
         FIG.  10    shows an example of a partially manufactured dual-junction LED array, at which the p-vias and delectric spacers have been filled with metal, in accordance with some examples. 
         FIG.  11    shows an example of a partially manufactured dual-junction LED array, at which the bonding dielectric has been deposited and patterned, in accordance with some examples. 
         FIG.  12    shows an example of a partially manufactured dual-junction LED array, at which the bond pads have been formed, in accordance with some examples. 
         FIG.  13    shows an example of a partially manufactured dual-junction LED array, at which the structure of  FIG.  12    has been bonded to a substrate, in accordance with some examples. 
         FIG.  14    shows an example of a partially manufactured dual-junction LED array, at which the substrate has been removed, in accordance with some examples. 
         FIG.  15    shows an example of a partially manufactured dual-junction LED array, at which n-side segmentation has been performed, in accordance with some examples. 
         FIG.  16    shows an example of a partially manufactured dual-junction LED array, at which the etched portions have been passivated, in accordance with some examples. 
         FIG.  17    shows a flowchart of an example of a method for providing illumination, in accordance with some examples. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Elements in the drawings are not necessarily drawn to scale. The configurations shown in the drawings are merely examples and should not be construed as limiting in any manner. 
     DETAILED DESCRIPTION 
     In an example, an illumination system can include a dual-junction light-emitting diode (LED) array including first and second junctions that extend in a plane. The first junction can emit first light from a plurality of first light-emitting areas that are separated by first boundaries. The second junction can be disposed on the first junction such that the first light passes through the second junction. The second junction can emit second light from a plurality of second light-emitting areas. The second light-emitting areas can be separated by second boundaries that correspond in a one-to-one correspondence to the first boundaries. The second boundaries can be offset in the plane from the corresponding first boundaries. The offset can help reduce or eliminate dark bands in the combined first and second light, which could be present if the second boundaries were not offset from the first boundaries. 
       FIG.  1    shows a side view of an example of an illumination system  100 , in accordance with some examples. 
     A dual junction light-emitting diode (LED) array  106  (hereinafter referred to as an “LED array”) can include a first junction and a second junction that extend in a plane. The first junction can emit first light  110  from a plurality of first light-emitting areas (hereinafter referred to as “LEDs”). The first junction can emit first light from a plurality of first light-emitting areas that are separated by first boundaries (e.g., areas that do not emit light). The second junction can be disposed on the first junction such that the first light passes through the second junction. The second junction can emit second light  112  from a plurality of second light-emitting areas (also referred to as “LEDs”). The second light-emitting areas can be separated by second boundaries that correspond in a one-to-one correspondence to the first boundaries. The second boundaries can be offset in the plane from the corresponding first boundaries. A lens  114  can direct the first light  110  and the second light  112  toward a scene  104  as illumination  116 . In the example of  FIG.  1   , the scene  104  includes a happy cat. Other suitable scenes can also be used. The LED array  106  and its structure are described in detail in  FIGS.  2 - 13    below. 
     A camera  102  can include a camera lens  122  that can collect reflected light  124  that is reflected from and/or emitted by the scene  104 . The camera lens  122  can direct the reflect light  124  onto a multi-pixel sensor  126  to form an image of the scene  104  on the multi-pixel sensor  126 . A controller  128  can receive a data signal that represents the image of the scene  104 . The controller  128  can drive the LEDs  108  in the LED array  106 . For example, the controller can optionally control one or more LEDs  108  in the LED array  106  independent of another one or more LEDs  108  in the LED array  106 , so as to illuminate the scene in a specified manner. For example, relatively close objects in the scene  104  may require a first amount of illumination, and relatively distant objects in the scene  104  may require a second amount of illumination, greater than the first amount, to have a same brightness in the image of the scene  104 . Other configurations are also possible. The camera  102  and illumination system  100  can be disposed in a housing  130 . In some examples, the housing  130  can be configured as a smart phone or other suitable device. 
       FIG.  2    shows a front view of an example of a dual junction LED array  200  including first and second junctions that extend in a plane (e.g., in a plane of the page of  FIG.  2   ), in accordance with some examples.  FIG.  3    shows a front view of an example of a dual junction LED array  300  including first and second junctions that extend in a plane (e.g., in a plane of the page of  FIG.  3   ), in accordance with some examples.  FIG.  4    shows a front view of an example of a dual-junction LED array  400  including first and second junctions that extend in a plane (e.g., in a plane of the page of  FIG.  4   ), in accordance with some examples. In the views of  FIGS.  2 - 4   , the first junction is parallel to the plane of the page, and the second junction is disposed between the first junction and the viewer. 
     The first junction can emit first light from a plurality of first light-emitting areas  202  that are separated by first boundaries  204 . The second junction can be disposed on the first junction such that the first light passes through the second junction. The second junction can emit second light from a plurality of second light-emitting areas  206 . The second light-emitting areas  206  can be separated by second boundaries  208  that correspond in a one-to-one correspondence to the first boundaries  204 . The second boundaries  208  can be offset in the plane from the corresponding first boundaries  204 . The offset can help reduce or eliminate dark bands in the combined first and second light, which could be present if the second boundaries  208  were not offset from the first boundaries  204 . 
     In some examples, the plurality of second light-emitting areas  206  can correspond in a one-to-one correspondence to the plurality of first light-emitting areas  202 . In some examples, each first light-emitting area  202  can emit first light that passes through at least part of the corresponding second light-emitting area  206 , and, optionally, through a second boundary  208  that is adjacent to the corresponding second light-emitting area  206 . 
     In some examples, the first boundaries  204  can be parallel to the second boundaries  208 . For example, the first boundaries  204  can include boundaries that extend along a first direction and boundaries that extend along a second direction that is orthogonal to the first direction. The second boundaries  208  can also include boundaries that extend along the first direction and the second direction. 
     In some examples, the plurality of first light-emitting areas  202  can be arranged in a first rectilinear array along orthogonal first and second dimensions. In some examples, each first boundary  204  can be arranged as an elongated area that extends along one of the first or second dimensions. In some examples, the plurality of second light-emitting areas  206  can be arranged in a second rectilinear array along the first and second dimensions. In some examples, each second boundary  208  can be arranged as an elongated area that extends along one of the first or second dimensions. 
     In some examples, such as the configurations of  FIGS.  2  and  3   , at least one first boundary  204  can extend in an unbroken line along a full extent of the first rectilinear array. 
     In some examples, such as the configuration of  FIG.  4   , at least one first boundary  204  can include a discontinuity. For example, the first boundary  204  can include a first segment and a second segment laterally offset from the first segment. In some examples, such as the configuration of  FIG.  4   , the at least one first boundary  204  can include a plurality of segments that are parallel. 
     In some examples, such as the configurations of  FIGS.  2  and  3   , at least one second boundary  208  can extend in an unbroken line along a full extent of the second rectilinear array. 
     In some examples, such as the configuration of  FIG.  4   , at least one second boundary  208  can include a discontinuity. In some examples, such as the configuration of  FIG.  4   , the at least one second boundary  208  can include a plurality of segments that are parallel. 
     In some examples, each first light-emitting area  202  can be electrically connected in series to the corresponding second light-emitting area  206 , such that an applied current causes the first light-emitting area  202  and the corresponding second light-emitting area  206  to produce light simultaneously. 
     In some examples, each first light emitting area  202  can be electrically powerable independent of other first light-emitting areas  202  of the plurality of first light-emitting areas  202 . In some examples, a subset of first light emitting areas  202  can be electrically powerable independent of other subsets of first light-emitting areas  202  of the plurality of first light-emitting areas  202 . In some examples, each second light emitting area  206  can be electrically powerable independent of other second light-emitting areas  206  of the plurality of second light-emitting areas  206 . In some examples, a subset of second light emitting areas  206  can be electrically powerable independent of other subsets of second light-emitting areas  206  of the plurality of second light-emitting areas  206 . 
       FIGS.  5 - 16    show cross-sectional side views of an example of a dual-junction LED array in various stages of manufacture, in accordance with some examples. In  FIGS.  5 - 16   , elements are numbered in the figure in which they initially appear or are modified, but are not numbered in subsequent figures for clarity. 
       FIG.  5    shows an example of a partially manufactured dual-junction LED array  500 , at which a mirror layer has been deposited, such as a metal mirror or a composite mirror, in accordance with some examples. A first n-doped layer  502  has been deposited or grown on a substrate  504 , such as a sapphire substrate. A first p-doped layer  506  has been deposited or grown on the first n-doped layer  502 , forming a first junction  508 . A second n-doped layer  510  has been deposited or grown on the first p-doped layer  506 . A second p-doped layer  512  has been deposited or grown on the second n-doped layer  510 , forming a second junction  514 . The first n-doped layer  502  and the second n-doped layer  510  can be formed from the same n-doped material or from different n-doped materials. The first p-doped layer  506  and the second p-doped layer  512  can be formed from the same p-doped material or from different p-doped materials. 
       FIG.  6    shows an example of a partially manufactured dual-junction LED array  600 , at which a hardmask  602  has been deposited. The hardmask  602  can include a dielectric material, or other suitable material. The hardmask  602  has been deposited on the second p-doped layer  512 . 
       FIG.  7    shows an example of a partially manufactured dual-junction LED array  700 , at which the hardmask has been pattern and etched, in accordance with some examples. The hardmask  602  of  FIG.  6    has been patterned and etched to form patterned hardmask  702 . The etching extends through the second p-doped layer  512  to form a patterned second p-doped layer  704 . The etching extends through the second n-doped layer  510  to form a patterned second n-doped layer  706 . The etching extends through the first n-doped layer  502  to form a patterned first n-doped layer  708 . The etched portions form vias  710 . 
       FIG.  8    shows an example of a partially manufactured dual-junction LED array  800 , at which the dielectric spacers have been deposited on sidewalls of the vias, in accordance with some examples. A dielectric material, such as the dielectric material used to form the hardmask  602 , has been deposited on sidewalls of the vias to form dielectric spacers  802 . The dielectric material may not be deposited on the bottom of the vias, or may have been deposited and subsequently removed. 
       FIG.  9    shows an example of a partially manufactured dual-junction LED array  900 , at which p-vias have been patterned and etched in the hardmask, in accordance with some examples. The hardmask  602  of  FIG.  6    has been patterned and etched to form p-vias  902 . 
       FIG.  10    shows an example of a partially manufactured dual-junction LED array  1000 , at which the p-vias and dielectric spacers have been filled with metal, in accordance with some examples. The p-vias  902  of  FIG.  6    and the dielectric spacers  802  of  FIG.  8    have been filled with a metal to form electrical connections  1002 . Such filling can include a depositing of a seed layer, a plate, and chemo-mechanical polishing. Any or all of the metal filling can be performed by evaporation/plating, sputtering, and/or beam epitaxy. 
       FIG.  11    shows an example of a partially manufactured dual-junction LED array  1100 , at which the bonding dielectric has been deposited and patterned, in accordance with some examples. A bonding dielectric  1102  has been deposited on the hardmask  602  and patterned/etched at locations away from the electrical connections  1002 . 
       FIG.  12    shows an example of a partially manufactured dual-junction LED array  1200 , at which the bond pads have been formed, in accordance with some examples. A metal has been deposited in the regions between the bonding delectric  1102  of  FIG.  11   , to enlarge the surface area of the electrical connections  1002  of  FIG.  10    to form the bond pads  1202 . Such depositing can include a depositing of a seed layer, a plate, and chemo-mechanical polishing. Any or all of the metal filling can be performed by evaporation/plating, sputtering, and/or beam epitaxy. 
       FIG.  13    shows an example of a partially manufactured dual-junction LED array  1300 , at which the structure of  FIG.  12    has been bonded to a substrate, in accordance with some examples. In  FIG.  13   , the structure of  FIG.  12    has been inverted and wafer-to-wafer bonded to a patterned substrate  1302 . The bonding can include hybrid bonding. 
       FIG.  14    shows an example of a partially manufactured dual-junction LED array  1400 , at which the substrate  504  has been removed, in accordance with some examples. The substrate  504  of  FIG.  5   , such as the sapphire substrate, has been removed, such as by laser liftoff. Such liftoff can be a wafer-level laser liftoff of the growth substrate, such as  504 . Patterned roughening can optionally be performed. 
       FIG.  15    shows an example of a partially manufactured dual-junction LED array  1500 , at which n-side segmentation has been performed, in accordance with some examples. Segmentation can define where the boundaries occur between light-emitting areas of the final device. The segmentation can be patterned as described above, so that the boundaries of one junction are offset from the boundaries of the other junction. The first n-doped layer  502  of  FIG.  5    can be etched to form the patterned first n-doped layer  1502 . The first p-doped layer  506  of  FIG.  5    can be etched to form the patterned first p-doped layer  1504 . The etched portions  1506  in both of these layers can form the segmentation pattern. 
       FIG.  16    shows an example of a partially manufactured dual-junction LED array  1600 , at which the etched portions have been passivated, in accordance with some examples. The etched portions  1506  of  FIG.  15    have been filled of partially filled (including sidewalls and bottoms) with a dielectric material  1602 . Such passivation can electrically isolate one light-emitting area from the other light-emitting areas. The dual-junction LED array  1600  can function as a completed device. 
     In some examples, the dual junction can optionally be covered by a wavelength converting layer, such as a phosphor. The dual junction can produce first light having a first wavelength, such as in the blue or violet portion of the visible spectrum. The wavelength converting layer can absorb some or all of the first light and emit second light having a second wavelength that is greater than the first wavelength, such as in the yellow portion of the visible spectrum. The full light output can be the second light, or a combination of the first light and the second light. In some examples, the phosphor and the geometry of the dual junction can be tailored to output light having a specified peak wavelength and/or a specified wavelength spectrum. 
       FIG.  17    shows a flowchart of an example of a method  1700  for providing illumination, in accordance with some examples. The method  1700  can be executed by the illumination system  100  of  FIG.  1   , or by any suitable illumination system. The method  1700  is but one example of a method for providing illumination. Other methods can also be used. 
     At operation  1702 , first light, such as first light  110 , can be emitted from a first junction of a dual junction LED array, such as LED array  106 , LED array  200 , LED array  300 , or LED array  400 , from a plurality of first light-emitting areas, such as first light-emitting areas  202 , that extend in a plane and are separated by first boundaries, such as first boundaries  204 . 
     At operation  1704 , the first light can be passed through a second junction of the dual junction LED array. 
     At operation  1706 , second light, such as second light  112 , can be emitted from the second junction from a plurality of second light-emitting areas, such as second light-emitting areas  206 , that correspond in a one-to-one correspondence to the plurality of first light-emitting areas. The plurality of second light-emitting areas can be separated by second boundaries, such as second boundaries  208 , that are offset in the plane from the first boundaries. In some examples, the first boundaries can be parallel to the second boundaries. 
     In some examples, each first light-emitting area can be electrically connected in series to the corresponding second light-emitting area, such that the first light-emitting area and the corresponding second light-emitting area can produce light simultaneously in response to an applied current. In other examples, each first light-emitting area and the corresponding second light-emitting area can be electrically powered independently. 
     In some examples, each first light emitting area can be electrically powerable independent of other first light-emitting areas of the plurality of first light-emitting areas. In some examples, each second light emitting area can be electrically powerable independent of other second light-emitting areas of the plurality of second light-emitting areas. 
     The system and method are applicable to adaptive flash for mobile devices, steerable illumination for automotive/industry applications, and others. 
     To further illustrate the systems and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples can stand on its own or can be combined in any permutation or combination with any one or more of the other examples. 
     In Example 1, an illumination system can include a dual junction light-emitting diode (LED) array including a first junction and a second junction that extend in a plane. The first junction can emit first light from a plurality of first light-emitting areas. The first light-emitting areas can be separated by first boundaries. The second junction can be disposed on the first junction such that the first light passes through the second junction. The second junction can emit second light from a plurality of second light-emitting areas. The second light-emitting areas can be separated by second boundaries that correspond in a one-to-one correspondence to the first boundaries. The second boundaries can be offset in the plane from the corresponding first boundaries. 
     In Example 2, the illumination system of Example 1 can optionally be configured such that: the plurality of second light-emitting areas corresponds in a one-to-one correspondence to the plurality of first light-emitting areas; and each first light-emitting area is configured to emit first light that passes through at least part of the corresponding second light-emitting area. 
     In Example 3, the illumination system of any one of Examples 1-2 can optionally be configured such that each first light-emitting area is configured to emit first light that passes through at least part of the corresponding second light-emitting area and through a second boundary that is adjacent to the corresponding second light-emitting area. 
     In Example 4, the illumination system of any one of Examples 1-3 can optionally be configured such that each first light-emitting area is electrically connected in series to the corresponding second light-emitting area, such that an applied current causes the first light-emitting area and the corresponding second light-emitting area to produce light simultaneously. 
     In Example 5, the illumination system of any one of Examples 1-4 can optionally be configured such that: each first light emitting area is electrically powerable independent of other first light-emitting areas of the plurality of first light-emitting areas; and each second light emitting area is electrically powerable independent of other second light-emitting areas of the plurality of second light-emitting areas. 
     In Example 6, the illumination system of any one of Examples 1-5 can optionally be configured such that the first boundaries are parallel to the second boundaries. 
     In Example 7, the illumination system of any one of Examples 1-6 can optionally be configured such that: the plurality of first light-emitting areas is arranged in a first rectilinear array along orthogonal first and second dimensions; each first boundary is arranged as an elongated area that extends along one of the first or second dimensions; the plurality of second light-emitting areas is arranged in a second rectilinear array along the first and second dimensions; and each second boundary is arranged as an elongated area that extends along one of the first or second dimensions. 
     In Example 8, the illumination system of any one of Examples 1-7 can optionally be configured such that at least one first boundary extends in an unbroken line along a full extent of the first rectilinear array. 
     In Example 9, the illumination system of any one of Examples 1-8 can optionally be configured such that at least one first boundary includes a discontinuity. 
     In Example 10, the illumination system of any one of Examples 1-9 can optionally be configured such that the at least one first boundary includes a plurality of segments that are parallel. 
     In Example 11, the illumination system of any one of Examples 1-10 can optionally be configured such that at least one second boundary extends in an unbroken line along a full extent of the second rectilinear array. 
     In Example 12, the illumination system of any one of Examples 1-11 can optionally be configured such that at least one second boundary includes a discontinuity. 
     In Example 13, the illumination system of any one of Examples 1-12 can optionally be configured such that the at least one second boundary includes a plurality of segments that are parallel. 
     In Example 14, the illumination system of any one of Examples 1-13 can optionally further include: a controller configured to selectively power at least one of the first light-emitting areas and at least some of the second light-emitting areas in response to distance to objects in a scene; a lens configured to direct the first light and the second light toward the scene as illumination; and a camera configured to collect illumination that is reflected from the scene to form an image of the scene. 
     In Example 15, the illumination system of any one of Examples 1-14 can optionally further include: a flash for the camera, the flash including the dual-junction LED array and the lens; and a housing that includes the flash, the camera, and the controller. 
     In Example 16, a method for providing illumination can include: emitting first light from a first junction of a dual junction light-emitting diode (LED) array from a plurality of first light-emitting areas that extend in a plane and are separated by first boundaries; passing the first light through a second junction of the dual junction LED array; and emitting second light from the second junction from a plurality of second light-emitting areas that correspond in a one-to-one correspondence to the plurality of first light-emitting areas, the plurality of second light-emitting areas being separated by second boundaries that are offset in the plane from the first boundaries. 
     In Example 17, the method of Example 16 can optionally be configured such that each first light-emitting area is electrically connected in series to the corresponding second light-emitting area, such that the first light-emitting area and the corresponding second light-emitting area are configured to produce light simultaneously in response to an applied current. 
     In Example 18, the method of any one of Examples 16-17 can optionally be configured such that: each first light emitting area is electrically powerable independent of other first light-emitting areas of the plurality of first light-emitting areas; and each second light emitting area is electrically powerable independent of other second light-emitting areas of the plurality of second light-emitting areas. 
     In Example 19, the method of any one of Examples 16-18 can optionally be configured such that the first boundaries are parallel to the second boundaries. 
     In Example 20, an illumination system can include a dual junction light-emitting diode (LED) array including a first junction and a second junction that extend in a plane. The first junction can emit first light from a plurality of first light-emitting areas. The first light-emitting areas can be separated by first boundaries. The second junction can be disposed on the first junction such that the first light passes through the second junction. The second junction can emit second light from a plurality of second light-emitting areas. The plurality of second light-emitting areas can correspond in a one-to-one correspondence to the plurality of first light-emitting areas. Each first light-emitting area can emit first light that passes through at least part of the corresponding second light-emitting area. Each first light-emitting area can be electrically connected in series to the corresponding second light-emitting area, such that the first light-emitting area can produce the first light and the corresponding second light-emitting area can produce the second light simultaneously in response to an applied current. The second light-emitting areas can be separated by second boundaries that correspond in a one-to-one correspondence to the first boundaries. The second boundaries can be offset in the plane from the corresponding first boundaries. The illumination system can further include a lens that can direct the first light and the second light toward a scene as illumination. The illumination system can further include a camera that can collect illumination that is reflected from the scene to form an image of the scene. 
     In Example 21, an illumination system can include a processor; memory including instructions that, when executed by the processor, cause the processor to perform operations, the operations including: emitting first light from a first junction of a dual-junction light-emitting diode (LED) array from a plurality of first light-emitting areas that extend in a plane and are separated by first boundaries; passing the first light through a second junction of the dual-junction LED array; and emitting second light from the second junction from a plurality of second light-emitting areas that correspond in a one-to-one correspondence to the plurality of first light-emitting areas, the plurality of second light-emitting areas being separated by second boundaries that are offset in the plane from the first boundaries. 
     In Example 22, the illumination system of Example 21 can optionally include the limitations of any one of Examples 1-20. 
     While only certain features of the system and method have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes. Method operations can be performed substantially simultaneously or in a different order.