PATENT DOCUMENT

Publication Number: US-12218479-B2
Application Number: US-202117379759-A
Country: US
Kind Code: B2

Title: Photonic integrated circuits with controlled collapse chip connections

Abstract:
Embodiments are directed to a photonic device that includes a first substrate defining a surface and a trench forming a depression along a portion of the surface, and a second substrate coupled with the surface and extending from the surface to form a raised portion around the trench. The photonic device can also include a laser die positioned within the trench, such that the laser die is surrounded by the second substrate, and an optical material positioned within a region between the laser die and the second substrate. The photonic device can further include a third substrate coupled with the second substrate such that the second substrate is positioned between the first substrate and the third substrate such that the second substrate is configured to at least partially isolate the laser die from mechanical stress exerted on the optical device.

Claims:
What is claimed is: 
     
       1. An optical device, comprising:
 a first substrate defining:
 a surface; and 
 a trench forming a depression along a portion of the surface; 
 
 a second substrate coupled with the surface and extending from the surface to form a raised portion around the trench; 
 a laser die positioned within the trench, such that the laser die is surrounded by the second substrate; 
 an optical material positioned within a region between the laser die, the first substrate, and the second substrate, the optical material comprising at least one of a liquid material or a solid material; and 
 a third substrate coupled with the second substrate such that the second substrate is positioned between the first substrate and the third substrate; wherein: 
 the second substrate is configured to at least partially isolate the laser die from mechanical stress exerted on the optical device. 
 
     
     
       2. The optical device of  claim 1 , further comprising:
 an optical output; 
 an underfill material positioned between the first substrate and the second substrate; and 
 a fill dam configured to retain the underfill material such that it does not cover the optical output. 
 
     
     
       3. The optical device of  claim 1 , wherein the third substrate defines a fill dam coupled to or extending toward the first substrate. 
     
     
       4. The optical device of  claim 3 , wherein a bottom edge of the fill dam is offset from the first substrate. 
     
     
       5. The optical device of  claim 3 , wherein the fill dam is configured to retain a fill material within a space between the first substrate and the third substrate. 
     
     
       6. The optical device of  claim 1 , further comprising an interconnect formed from an electrically conductive material and positioned on the third substrate. 
     
     
       7. The optical device of  claim 6 , wherein:
 the third substrate comprises a first surface that faces toward the first substrate and a second surface opposite the first surface; and 
 the interconnect is positioned on the second surface. 
 
     
     
       8. The optical device of  claim 6 , wherein the interconnect is electrically coupled to the laser die.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a nonprovisional of, and claims the benefit under 35 U.S.C. § 119(e) of, U.S. Provisional Patent Application No. 63/053,841, filed Jul. 20, 2020, the contents of which are incorporated herein by reference as if fully disclosed herein. 
    
    
     FIELD 
     The described embodiments relate generally to photonic integrated circuits. More particularly, the present embodiments relate to systems and methods for producing photonic integrated circuits that can be assembled using controlled collapse chip connections. 
     BACKGROUND 
     Photonic integrated circuits include integrated optical circuits that employ photonic components that emit and/or absorb optical signals such as visible or infrared light. Photonic integrated circuits can include optical emitters such as laser emitters and can be manufactured using microfabrication techniques such as micromachining and lithography to create features of the photonic circuit on a substrate. Photonic components such as lasers may be coupled with the circuit at various stages in the manufacturing process and one or more steps may be performed after the addition of the photonic components such as coating to help protect these components from contamination or damage. Once assembled the photonic integrated circuit may be interconnected to other semi-conductor devices. 
     SUMMARY 
     Embodiments are directed to an optical device including a first substrate defining a surface and a trench forming a depression along a portion of the surface, and a second substrate coupled with the surface and extending from the surface to form a raised portion around the trench. The optical device may also include a laser die positioned within the trench, such that the laser die is surrounded by the second substrate, and an optical material positioned within a region between the laser die and the second substrate. The optical device may further include a third substrate coupled with the second substrate such that the second substrate is positioned between the first substrate and the third substrate. The second substrate may be configured to at least partially isolate the laser die from mechanical stress exerted on the optical device. 
     In some embodiments the optical device further includes an optical output, a fill material positioned between the first substrate and the second substrate, and a fill dam configured to retain the fill material such that it does not cover the optical output. In some cases, the optical device includes a fill dam coupled with the third substrate and extending toward the first substrate. In some cases, a bottom edge of the fill dam is offset from the first substrate. The fill dam may be configured to retain a fill material within a space between the first substrate and the third substrate. In some embodiments, the optical device includes an interconnect formed from an electrically conductive material that is positioned on the third substrate. In some cases, the third substrate comprises a first surface that faces toward the first substrate and a second surface opposite the first surface, and the interconnect is positioned on the second surface. In further examples, the interconnect is electrically coupled to the laser die. 
     Embodiments described herein are also directed to a method of manufacturing an optical device, where the method includes forming a trench in a first substrate that defines a depression along a surface of the first substrate and forming a raised feature comprising a second substrate around the trench. The raised feature may extend from the surface. The method may also include coupling a laser die to the first substrate such that the laser die is positioned within the trench and surrounded by the raised feature, and introducing a first optical material to a first region between the raised feature and the laser die. The method may also include coupling a third substrate to the raised feature such that the raised feature is positioned between the first substrate and the third substrate, and introducing a second material into a second region at least partially defined by the first substrate, the raised feature, and the third substrate. 
     In some embodiments, the method may further include forming a fill dam on the third substrate that extends toward the first substrate and is offset from the first substrate when the second substrate is coupled to the raised feature. In some cases, the method can include forming an interconnect on the second substrate, where the interconnect is positioned on an external surface of the third substrate and is coupled to the raised feature. 
     Embodiments described herein are also directed to an optical device, including a first substrate that defines a surface including a first electrical contact, and a trench forming a depression along a portion of the surface. The optical device can also include a laser die positioned within the trench and coupled with the first electrical contact, and a first material coupled with the laser die and at least a portion of the first substrate. A second substrate may be coupled to the first substrate and form a cavity around the laser die, and the second substrate can include a second electrical contact that is electrically coupled to the first electrical contact. An electrical interconnect can be coupled to an outer surface of the second substrate and electrically coupled with the second electrical contact. 
     In some embodiments, the first material forms a layer covering the laser die and at least a portion of the first substrate, the second substrate may be a silicon wafer, and the cavity can be etched from the silicon wafer. The electrical interconnect may include a solder based material that is configured to electrically couple the laser die with an electrical circuit. In some cases, the first material includes a conformal coating that covers the laser die and at least a portion of the first substrate. In some examples, the second substrate is formed from a silicon material, and the second substrate includes a via extending through the silicon material. The via may contain an electrically conductive material comprising the second electrical contact. In some cases, the electrical interconnect is at least partially positioned on an external surface of the second substrate. 
     Embodiments described herein include a method of forming an optical device, where the method includes forming a trench in a first substrate that defines a depression along a surface of the first substrate. The method may include depositing a first electrical contact onto the first substrate such that a first portion of the first electrical contact is located in the trench, and coupling a laser die to the first substrate such that the laser die is positioned within the trench. A first material may be applied over the laser die and at least a portion of the first substrate. In some cases, the method further includes coupling a second substrate to the first substrate such that a second electrical contact of the second substrate is electrically coupled with the first electrical contact. The second substrate may form a cavity around the laser die. The method may also include forming an electrical interconnect on an outer surface of the second substrate such that the electrical interconnect is electrically coupled to the second electrical contact. 
     In some embodiments, the second substrate is a silicon material, and the method may further include etching the second substrate to form at least a portion of the cavity in the silicon material. In some cases, the electrical interconnect is formed using a ball drop process to deposit a solder based material on the second substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIGS.  1 A and  1 B  illustrate top and cross-sectional views, respectively, of a first example optical device; 
         FIG.  2    illustrates a cross-sectional view of a first example of an optical device; 
         FIG.  3    illustrates a cross-sectional view of a first example of an optical device; 
         FIG.  4    illustrates an example method for manufacturing a first example of an optical device; 
         FIGS.  5 A and  5 B  illustrate top and cross-sectional views, respectively, of a second example of an optical device; 
         FIG.  6    illustrates a cross-sectional view of a second example of an optical device; 
         FIG.  7    illustrates an example method for manufacturing a second example of an optical device; and 
         FIG.  8    illustrates an example block diagram from an optical device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any characteristics attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented there between, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Embodiments described herein include an optical device such as a photonic integrated circuit (PIC) that includes optical components such as laser dice and structures for protecting the optical components. In a first set of embodiments, an optical device can include a first substrate material that has a depression defining a trench and a second substrate that forms a wall around the trench. An optical output such as a laser die may be positioned within the trench and a third substrate may be positioned on the wall formed by the second substrate. The trench, the wall, and the third substrate may form a cavity around the laser die. In some cases, the cavity may contain an optical fill material in the space defined by the trench, the wall, and the third substrate. Accordingly, the laser die may be isolated from contamination and protected from mechanical stress experienced by the optical device. In some embodiments, interconnects such as controlled collapse chip connections (also referred to as C4 or flip chip connections), copper pillar connections, gold stud bumps, or a combination thereof can be positioned on an outer surface of the third substrate. Thus, the optical device can be interconnected to other integrated circuits using C4 (flip chip), copper pillar, gold stud bump, or other suitable connection methods. 
     In some embodiments, a fill material may be introduced to a space between the first substrate and the third substrate. For example, the wall formed from the second substrate may offset the first substrate from the third substrate thereby creating a gap between these components. A fill material may be injected into this gap to fill the space between the first and the third substrates. In some cases, the optical device may include a fill dam to help control the location of the fill material within the gap. For example, the fill dam may be formed on the first substrate and extend toward the first substrate. The fill dam may define a structure that blocks the movement of the fill material. In some cases, the fill dam may be located near a facet or optical output of the optical device. Thus, the fill dam may prevent the fill material from covering or otherwise interfering with an optical output of the optical device. 
     In another set of embodiments, an optical device can include a first substrate material that has a depression defining a trench and a second substrate material that has a recessed feature. A laser die may be positioned within the trench and the first and second substrates can be joined to form a cavity around the laser die. The cavity can be defined by the trench in the first substrate and the recessed feature in the second substrate. The cavity may isolate the laser die from contamination and/or protect the laser die from mechanical stress experienced by the optical device. In some embodiments, interconnects (C4/flip chip) can be positioned on an outer surface of the second substrate. Thus, the optical device can be interconnected to other integrated circuits using C4 or flip chip connection methods. 
     These and other embodiments are discussed below with reference to  FIGS.  1 - 8   . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG.  1 A  illustrates a top view of an optical device  100 , and  FIG.  1 B  illustrates a cross-sectional view of the optical device taken along line A-A. As illustrated, multiple optical devices may be formed on a first substrate  102 , one of which is labeled for clarity. The optical device  100  can include a trench  104  that is defined by a depressed region in an upper surface of the first substrate  102 . A second substrate can define a wall  106  that is formed around the trench  104  and extends from the upper surface of the first substrate  102 . In some embodiments, the wall  106  can form a closed perimeter around the trench  104 . A photonic device such as a laser die  108  can be positioned within the trench  104  and surrounded by the wall  106 . The laser die  108  can be coupled to an electrical contact  110 , which can be coupled to a post  112  or interconnection bump; the term “post,” as used herein, encompasses bumps as well. The post  112  can be formed from C4 interconnections, copper post connections, gold stud bump connections, or other suitable connections, and multiple posts  112  can be distributed along a surface of the first substrate  102 , for example, to form an array of posts  112 . 
     In some embodiments, the optical device  100  can include an optical fill material  114  in a region between the wall  106  and the laser die  108 . The optical fill material  114  can be introduced into the region between the wall  106  and the laser die  108  as a liquid/viscous material such that it conforms or at least partially conforms to the surfaces in this region formed by the wall  106  and the laser die  108 . The optical fill material  114  can be cured to form a solid or semi-solid structure around the laser die  108 . In some examples, the optical fill material  114  may not be cured until one or more additional processing steps have occurred such as adding additional structures/elements to the optical device  100  as described herein. The optical fill material  114  can include an optical underfill material, adhesive, or the like. 
     In some embodiments, the first substrate  102  can be formed from a silicon, ceramic, plastic, or other suitable material and the trench  104  can be machined, etched, or formed in the material using processes such as patterned lithography techniques. The second substrate, defining the wall  106 , can be formed from a variety of materials. For example, the wall  106  may be formed from an organic or ceramic substrate and be plated using copper and/or solder to create a structure that extends or is raised from the surface of the first substrate  102 . In cases where the wall  106  forms a closed perimeter around the trench  104 , the wall  106  and the trench  104  may form a first portion of a closed cavity around the laser die  108  that isolates the laser die  108 . The wall  106  can be configured to be more rigid than the laser die  108 , such that the wall  106  can isolate/protect the laser die  108  from mechanical stress or other physical disturbances. In some examples, a top of the wall  106  may extend to a height of the top of the laser die  108  when the laser die is positioned with in the trench  104  and is coupled with the first substrate  102 . In some cases, the wall  106  can extend above the laser die  108  such that a top of the wall  106  is above a top of the laser die  108 . 
     In some embodiments, the wall  106  is formed using repassivation techniques with materials that can include polyimide, polybenzocyclobutene, or benzocyclobutene, and a redistribution layer that can be formed by metal pattern plating processes that includes forming C4 solder bumps, metal studs, or metal pillars (collectively, “posts”). In some cases, forming the wall can include forming passivation layers on one or more of these components. In some examples, the bump, stud, and/or pillar heights can be between about 10 and about 150 micrometers, the redistribution layer thickness can be between about 1 micrometer and about 5 micrometers, and the passivation thickness can be between about 1 micrometer and about 20 micrometers. 
       FIG.  2    illustrates a cross-sectional view of an optical device  200  taken along line A-A and further including a third substrate  202 , a fill material  204 , a fill dam  206  and an optical output  208 . The optical device  200  may be an example of the optical device  100  and can include a first substrate  102  having a trench  104 , a wall  106  positioned around the trench  104 , a laser die  108  positioned within the trench  104 , and an optical fill material  114  as described with reference to  FIG.  1   . The third substrate  202  may be positioned on top of the wall  106  such that it is offset from the first substrate  102 . The fill material  204  may be located between the first substrate  102  and the third substrate  202 . The fill dam  206  may extend from the third substrate  202  and towards the first substrate  102 , and the optical output  208  may be located on the first substrate  102 . 
     In some embodiments, the third substrate  202  may form a layer of material that is coupled with the second substrate forming the wall  106 . The third substrate  202  may be formed from a silicon, ceramic, organic, or other suitable material and may partially define a space that is defined by an upper surface of the first substrate  102 , an outer surface of the wall  106 , and a lower surface of the third substrate  202 . The third substrate  202  may be at least partially supported by the wall  106 . The third substrate  202  may also be coupled with the post  112  (which may be an interconnection bump) using C4, copper pillar, or gold stud bump connection techniques. In some embodiments, a fill material  204  can be introduced into the space between the first substrate  102 , the wall  106 , and the third substrate  202 . The fill material  204  can be introduced as a liquid or viscous material and be injected or flow into the space defined by the first substrate  102 , the wall  106 , and the third substrate  202 . The fill material  204  can be cured such that it hardens to form a more structurally rigid material. In some cases, the optical fill material  114  and the fill material  204  can be cured at the same or similar times to couple the third substrate  202  to the wall  106  and the first substrate  102 . The fill material  204  can include an optical underfill material, adhesive, or the like. 
     The combination of the wall  106  and the fill material  204  can create a structural support between the first substrate  102  and the third substrate  202  such that the laser die  108  is isolated and/or protected from mechanical stress. In some cases, the optical fill material  114 , the first substrate  102 , the wall  106 , and the third substrate  202  can also protect the laser die  108  from contaminants such as dust, debris, moisture, and the like. 
     In some embodiments, the fill dam  206  can be positioned along the third substrate  202  and extend towards the first substrate  102 . The fill dam  206  can help retain the fill material  204  within the space between the first substrate  102  and the third substrate  202  such that the fill material does not cover the optical output  208 . For example, the fill dam  206  may extend towards an upper surface of the first substrate  102  such that there is a smaller gap between the first substrate  102  and the fill dam  206  than there is between the first substrate  102  and the third substrate  202 . In some examples, the fill dam  206  can form a gap with the first substrate  102  that is between 10 micrometers and 80 micrometers. Accordingly, as fill material  204  is introduced into the optical device  200  (through injection, surface tension, or other technique), the fill dam  206  may prevent the fill material  204  from spreading over the optical output  208 . In some cases, the size and positioning of the fill dam  206  may be based on one or more properties of the fill material  204  such as a viscosity, surface tension, and so on. In some cases, the optical output  208  may include a facet. 
       FIG.  3    illustrates a cross-sectional view of an optical device  300  taken along line A-A and also including one or more interconnects  302  positioned along an upper surface of the third substrate  202 . The optical device  300  may be an example of the optical devices  100  and  200  and can include a first substrate  102  having a trench  104 , a wall  106  positioned around the trench  104 , a laser die  108  positioned within the trench  104 , an optical fill material  114 , a third substrate  202 , a fill material  204 , a fill dam  206  and an optical output  208  as described with reference to  FIGS.  1  and  2   . 
     In some embodiments, the interconnects  302  can be deposited on an upper surface of the third substrate  202 . The interconnects  302  can be formed from solder, copper, gold, or other suitable materials, or a combination thereof, and used for bonding the optical device to another device such as another integrated circuit that may be used to drive the laser die  108 . In some embodiments, the interconnects  302  can be configured to allow for flip chip (C4) bonding of the optical device to other wafer devices. In some embodiments, one or more interconnects  302  may be electrically coupled with the post  112  (and electrical contact  110 ) such that the interconnect  302  is electrically coupled to the laser die  108 . 
     In some embodiments, one or more portions of a chip may be divided such that different optical devices  300  that were formed on a single chip can be separated in multiple discrete optical devices  300 . After the separation, the optical devices may undergo inspections such as a visual inspection to confirm that they are ready to be bonded to other devices such as other integrated circuits using flip chip (C4) bonding techniques. 
       FIG.  4    illustrates an example method  400  for manufacturing an optical device such as the optical devices  100 ,  200 , and  300  described with reference to  FIGS.  1 - 3   . At  402 , the method  400  may include forming a trench in a first substrate that defines depression along a surface of the first substrate. For example, the first substrate may include a silicon material and the trench may be etched, machined, or formed using other suitable processes such as lithographic patterning processes. In some cases, the depth of the trench may be defined based on a size of a photonic device such as a laser die that is to be at least partially located within the trench. The trench may form a first portion of a cavity that surrounds the laser die. In some cases, conductive traces may be created in the trench that are used to couple the laser die to one or more driver circuits. 
     At  404 , the method  400  may include forming a raised feature using a second substrate, which may be the same or different material as the first substrate. The second substrate can form a wall around the trench that extends from the surface of the first substrate. The raised feature may be formed from an organic or ceramic material or other suitable materials. In some cases, the raised feature may be coated with copper, solder, gold, or a combination thereof, which may be used to couple the raised feature to one or more other components of the optical device. The raised feature may at least partially isolate a photonic component such as a laser die from the surrounding environment, and/or provide protection from mechanical stress applied to the optical device. 
     At  406 , the method  400  can include coupling a laser die to the first substrate such that the laser die is positioned within the trench defined by the first substrate. In some cases, the laser die may be coupled with electrical traces/contacts that are located within the trench. The laser die may be partially surrounded by the trench. In some cases, the laser die may also be partially surrounded by the raised feature that surrounds the trench. 
     At  408 , the method  400  may include introducing a first optical material into a first region between the raised feature and the laser die. The optical fill material may include a liquid/viscous material that can flow around the laser die and trench to conform to features of the laser die and the trench. In some cases, the optical fill material may be cured after settling into the region between the laser die and the trench. In some examples, the optical fill material may be transparent when cured such that light emitted from the laser die can pass through the cured optical fill material. The optical fill material may stabilize the laser die in place, protect it from contamination (dust, debris, moisture and the like), and help isolate the laser die from mechanical stress or other physical disruptions. 
     At  410 , the method  400  may include coupling a third substrate to the raised feature such that the raised feature is positioned between the first substrate and the third substrate. In some cases, coupling the third substrate to the raised feature may be accomplished using physical connections such as a solder, gold, or copper materials, the optical fill material, or other fill materials as described herein. The third substrate may be offset from the first substrate by the raised feature to form a space or region between the first and second substrates. 
     At  412 , the method  400  can include introducing a second fill to a second region at least partially defined by the first substrate, the second substrate, and the raised feature. The second material may be introduced to the second region as a liquid and be injected or flow into the second region via surface tension forces, or other suitable processes. Once in place, the fill material can be cured to transform it to a solid material, which can include heat curing, light curing, or other suitable methods. 
     In some embodiments, the method  400  may include forming a fill dam on the third substrate such that the fill dam extends toward the first substrate and is offset from the first substrate. A lower edge of the fill dam may form a smaller gap with the first substrate that prevents or resists the fill material from moving past the fill dam. The fill damn may be used to control where fill material can move to within the second region and prevent the fill material from covering an optical output of the optical device such as a facet. In some cases, the method  400  can include forming one or more interconnects on an outer surface of the second substrate. The interconnects may be used to couple the optical device to other devices using flip chip (C4) bonding techniques. 
       FIG.  5 A  illustrates a top view of an optical device  500  and  FIG.  5 B  illustrates a cross-sectional view of the optical device  500  taken along line B-B. The optical device  500  can be an example of a photonic integrated circuit having an optical output, such as a laser die  508 , protected by a capping substrate such as a silicon capping wafer (which may be referred to as a second substrate  506 ). As illustrated, multiple optical devices may be formed on a first substrate  502 , one of which is labeled for clarity. In some cases, the first substrate is a silicon photonics substrate. The optical device  500  can include an optical facet  503  and a trench  504  that is defined by depressed regions in an upper surface of the first substrate  502 . The optical facet  503  and/or the trench  504  can be formed in the first substrate  502  using etching techniques or other suitable processes, such as those described herein with respect to the trench  504 , or any other suitable process. A second substrate  506 , which may be an example of a silicon capping substrate or wafer, can be coupled with the first substrate to form one or more cavities in the optical device  500 . The second substrate  506  can be a silicon capping wafer and a facet can be located within a first cavity of the wafer. Similarly, the laser die  508  can be located within a second cavity formed by coupling the first substrate  502  (e.g., the silicon photonics substrate) and the second substrate  506 . The cavity can isolate photonic components, such as the facet  503  and the laser die  508  from the surrounding environment, which can protect these components from mechanical stress applied to the optical device, protect them from other physical damage, and isolate them from contamination, debris, and so on. 
     In some embodiments, a first material, which can include an optical underfill, can couple the laser die  508  to the first substrate  502  and/or the second substrate  506 . The first material can encapsulate the laser die  508  to protect the laser die such as by reducing stress between the laser die  508  and the first substrate  502 . The laser die  508  can also be coupled with a first electrical contact  512 , which can be partially located in the trench  504 . In some embodiments, the second substrate  506  can include a second electrical contact  514 , which can be coupled to the first electrical contact  512 . 
     In some embodiments, the first substrate  502  can be formed from a silicon material (or any other suitable material, which may include a ceramic or plastic) and the trench  504  can be machined, etched, or formed in the silicon material using any suitable processes such as patterned lithography techniques. The second substrate  506  can be formed from a silicon material and the second substrate  506  can be etched, machined, or manufactured using other suitable techniques to create a recess  507  in the second substrate  506  that forms an upper portion of the cavity. Etching of the first substrate  502  and/or the second substrate  506  can be performed along crystalline planes in the silicon material. In some embodiments, the trench  504  can be created in the first substrate, and independently, the recess  507  can be created in the second substrate  506 . The first substrate  502  and the second substrate  506  can be joined to form the cavity. The first substrate  502  and the second substrate  506  can be bonded together using solder based connections, or other suitable methods such as adhesive bonding. In some embodiments, the second substrate (e.g., the capping wafer) may be formed from a material other than silicon. 
     In some embodiments, the laser die  508  can be positioned within the trench  504  and coupled to the first substrate  502  prior to bonding the first substrate  502  with the second substrate  506 . In some embodiments, the facet  503  is also formed in the first substrate  502  and also contained within the recess  507  that is formed after joining the first substrate  502  and the second substrate  506 . In other cases, the optical facet  503  can be located in a different cavity from the laser die. The first electrical contact  512  can be deposited onto the first substrate  502  and the laser die  508  can be bonded to the first electrical contact  512 . The first electrical contact  512  can include electrically conductive traces that are partially located within the trench  504 . In some cases, the first electrical contact  512  can also be positioned along a portion of the first substrate  502  that is adjacent the trench  504 . In some embodiments, a first material  510 , such as an optical underfill, can be deposited around the laser die  508  and a portion of the first substrate  502  to form a layer/coating that covers the laser die  508 , which may help protect the laser die  508  from contaminants such as dust, debris, moisture, or the like. 
     When the first substrate  502  is coupled with the second substrate  506 , the cavity/cavities around the facet  503  and/or laser die  508  may protect the facet  503  and laser die  508  from contaminants (dust, debris, moisture, etc.), mechanical stress, or other physical disruptions. For example, the first substrate  502  and the second substrate  506  may form a protective barrier around the facet  503  and/or the laser die  508 . 
     In some embodiments, the second substrate  506  can include a via that comprises at least a portion of the second electrical contact  514 . The second electrical contact  514  may couple to the first electrical contact  512  and also include a portion of electrically conductive material that is located on an external surface of the second substrate  506 . Thus, the second electrical contact  514  may be used to electrically couple the laser die  508  (or other photonic component) to an external device such as an integrated circuit that is used to drive the laser die  508 . 
       FIG.  6    illustrates a cross-sectional view of an optical device  600  taken along line B-B and further comprising one or more electrical interconnects  602 . The optical device  600  can be an example of the optical device  500  and include the first substrate  502 , the second substrate  506 , the facet  503 , the laser die  508 , the first electrical contact  512 , and the second electrical contact  514  described with reference to  FIG.  5   . 
     In some embodiments, the interconnects  602  can be deposited on an upper surface of the second substrate  506 . The interconnects  602  can be formed from a solder based material and used for bonding the optical device to another device such as another integrated circuit that may be used to drive the laser die  508 . In some embodiments, the interconnects  602  can be configured to allow flip chip (C4) bonding, copper pillar bonding, or gold stud bump bonding of the optical device to other wafer devices. In some embodiments, one or more interconnects  602  may be electrically coupled with the second electrical contact  514  (and the first electrical contact  512 ) such that the interconnect  602  is electrically coupled to the laser die  508 . Thus, the interconnects  602  may be used to connect the laser die  508  to other devices (other integrated circuits) that are used to drive the laser die  508 . 
       FIG.  7    illustrates an example method  700  for manufacturing an optical device such as the optical devices  500  and  600  described with reference to  FIGS.  5  and  6   . At  702 , the method  700  may include forming a trench in a first substrate that defines a depression along a surface of the first substrate. For example, the first substrate may include a silicon material and the trench may be etched, machined, or formed using other suitable processes such as lithographic patterning processes. In some cases, the depth of the trench may be defined based on a size of a photonic device such as a laser die that is to be at least partially located within the trench. The trench may form a first portion of a cavity that surrounds the laser die. In some cases, an optical facet can be formed in the first substrate using etching, machining, or other suitable techniques. 
     At  704 , the method  700  may include depositing a first electrical contact onto the first substrate such that at least a portion of the electrical contact is located in the trench. In some cases, the first electrical contact may include one or more conductive traces positioned in the trench that are used to couple the laser die to one or more driver circuits. The first electrical contact may extend from the trench and along a portion of the first substrate, for example, to a location where a via from another layer will interface with the first substrate. 
     At  706 , the method  700  can include coupling a laser die to the first substrate such that the laser die is positioned within the trench defined by the first substrate. In some cases, the laser die may be coupled with first electrical contact/traces that are located within the trench. The laser die may be partially surrounded by the trench. 
     At  708 , the method  700  may include applying a first material over the laser die and at least a portion of the first substrate. In some cases, the first material may include a conformal coating that covers the laser die. The first material may be selected to protect the laser die from contamination such as dust, debris, or moisture. 
     At  710 , the method  700  may include coupling a second substrate to the first substrate such that a second electrical contact of the second substrate is electrically coupled with the first electrical contact. In some cases, the second substrate may have a via that includes the second electrical contact and the via may align with the first electrical contact to provide an electrical path from the laser die to an external surface of the second substrate. 
     At  712 , the method  700  may include forming an electrical interconnect on an outer surface of the second substrate such that the electrical interconnect is electrically coupled to the second electrical contact. The interconnects may include a solder based material or other suitable electrically conductive material that can be used to couple the optical device to other devices using flip chip (C4), copper pillar, gold stud bump, or other bonding techniques. 
       FIG.  8    illustrates an example block diagram of an optical device  800 , which may in some cases take the form of any of the optical devices as described with reference to  FIGS.  1 - 7   . The optical device can include a processor  802 , an input/output (I/O) mechanism  804  (e.g., an input/output device, such as a touch screen, crown or button, input/output port, or haptic interface), one or more optical units  806  (e.g., a photonic device such as a laser die), memory  808 , sensors  810  (e.g., an optical sensing system), and a power source  812  (e.g., a rechargeable battery). The processor  802  can control some or all of the operations of the optical device  800 . The processor  802  can communicate, either directly or indirectly, with some or all of the components of the optical device  800 . For example, a system bus or other communication mechanism  814  can provide communication between the processor  802 , the I/O mechanism  804 , the optical unit  806 , the memory  808 , the sensors  810 , and the power source  812 . 
     The processor  802  can be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor  802  can be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitable computing element or elements. 
     It should be noted that the components of the optical device  800  can be controlled by multiple processors. For example, select components of the optical device  800  (e.g., a sensor  810 ) may be controlled by a first processor and other components of the optical device  800  (e.g., the optics unit  806 ) may be controlled by a second processor, where the first and second processors may or may not be in communication with each other. 
     The I/O mechanism  804  can transmit and/or receive data from a user or another electronic device. An I/O device can include a display, a touch sensing input surface, one or more buttons (e.g., a graphical user interface “home” button), one or more cameras, one or more microphones or speakers, one or more ports, such as a microphone port, and/or a keyboard. Additionally or alternatively, an I/O device or port can transmit electronic signals via a communications network, such as a wireless and/or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet connections. 
     The memory  808  can store electronic data that can be used by the optical device  800 . For example, the memory  808  can store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, and data structures or databases. The memory  808  can be configured as any type of memory. By way of example only, the memory  808  can be implemented as random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such devices. 
     The optical device  800  may also include one or more sensors  810  positioned almost anywhere on the optical device  800 . The sensor(s)  810  can be configured to sense one or more type of parameters, such as but not limited to, pressure, light, touch, heat, movement, relative motion, biometric data (e.g., biological parameters), and so on. For example, the sensor(s)  810  may include a heat sensor, a position sensor, a light or optical sensor, an accelerometer, a pressure transducer, a gyroscope, a magnetometer, a health monitoring sensor, and so on. Additionally, the one or more sensors  810  can utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasound, piezoelectric, and thermal sensing technology. 
     The power source  812  can be implemented with any device capable of providing energy to the optical device  800 . For example, the power source  812  may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power source  812  can be a power connector or power cord that connects the optical device  800  to another power source, such as a wall outlet. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20210719
Publication Date: 20250204
Grant Date: 20250204
Priority Date: 20200720
Inventors: LEE, SEUNGJAE
Sawyer, Brett
CHOU, CHIA-TE
BYRD, JERRY
ABEDIASL, Hooman
Assignee: APPLE INC
CPC Classifications: [{"code": "H01S5/021", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/0239", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/02234", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01S5/4025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01S5/02345", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/02315", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/4202", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01S5/0225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/43", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01S5/0239", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/021", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/0225", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 77301008