PATENT DOCUMENT

Publication Number: US-12119275-B2
Application Number: US-202117461207-A
Country: US
Kind Code: B2

Title: Recessed lid and ring designs and lid local peripheral reinforcement designs

Abstract:
Modules and methods of assembly are described. A module includes a lid mounted on a module substrate and covering a component. A stiffener structure may optionally be mounted between the lid and module substrate. A recess can be formed in any of an outer wall bottom surface of the lid, and top or bottom surface of the stiffener structure such that an adhesive layer at least partially fills the recess.

Claims:
What is claimed is: 
     
       1. A module comprising:
 a module substrate; 
 a component on a top side of the module substrate; 
 a stiffener structure mounted on the top side of the module substrate, the stiffener including a flat top surface; and 
 a lid mounted on the flat top surface of the stiffener structure and covering the component, wherein the lid comprises a bottom surface and a lid recess in the bottom surface, 
 wherein the stiffener structure flat top surface is bonded to the bottom surface of the lid with a first adhesive layer that at least partially fills the lid recess in the bottom surface of the lid. 
 
     
     
       2. The module of  claim 1 , wherein the lid recess is along an outer portion of an outer wall of the lid. 
     
     
       3. The module of  claim 1 , wherein the lid recess is along an inner portion of an outer wall of the lid. 
     
     
       4. The module of  claim 1 , wherein the lid recess includes a plurality of steps. 
     
     
       5. The module of  claim 1 , wherein the lid recess is sloped or curved. 
     
     
       6. The module of  claim 1 , further comprising a second adhesive layer bonding the stiffener structure to the top side of the module substrate. 
     
     
       7. The module of  claim 1 , wherein the stiffener structure is formed of a material with lower coefficient of thermal expansion (CTE) than the lid. 
     
     
       8. The module of  claim 1 , wherein the lid includes a plurality of local peripheral reinforcement structures extending laterally adjacent to the stiffener structure. 
     
     
       9. The module of  claim 8 , wherein the plurality of local peripheral reinforcement structures is located at corners of the lid. 
     
     
       10. The module of  claim 8 , wherein the plurality of local peripheral reinforcement structures is located along side edges of the lid. 
     
     
       11. A module comprising:
 a module substrate; 
 a component on a top side of the module substrate; 
 a stiffener structure mounted on a flat surface of the top side of the module substrate; 
 a lid mounted on the stiffener structure and covering the component; 
 a first adhesive layer bonding a top surface of the stiffener structure to the lid; 
 a second adhesive layer bonding a bottom surface of the stiffener structure to the module substrate; and 
 a first stiffener recess formed in the bottom surface of the stiffener structure; 
 wherein the second adhesive layer at least partially fills the first stiffener recess. 
 
     
     
       12. The module of  claim 11 , further comprising a second stiffener recess formed in a top surface of the stiffener structure. 
     
     
       13. The module of  claim 11 , wherein the first stiffener recess includes a plurality of steps. 
     
     
       14. The module of  claim 11 , wherein the first stiffener recess is sloped or curved. 
     
     
       15. The module of  claim 11 , wherein the lid includes a plurality of local peripheral reinforcement structures extending laterally adjacent to and outside of a lateral periphery of the stiffener structure. 
     
     
       16. A module comprising:
 a module substrate; 
 a component on a top side of the module substrate; 
 a stiffener structure mounted on the top side of the module substrate; and 
 a lid mounted on the stiffener structure and covering the component; 
 wherein the lid includes a plurality of local peripheral reinforcement structures extending laterally adjacent to and outside of a lateral periphery of the stiffener structure. 
 
     
     
       17. The module of  claim 16 , wherein the plurality of local peripheral reinforcement structures is located at corners of the lid. 
     
     
       18. The module of  claim 17 , wherein the plurality of local peripheral reinforcement structures is located along side edges of the lid.

Description:
BACKGROUND 
     Field 
     Embodiments described herein relate to multiple chip modules, and in particular to lids thereof. 
     Background Information 
     Lids are widely used in multiple chip modules (MCMs) for a variety of reasons, such as to provide mechanical integrity, hermetic sealing from environment, and thermal performance. In an exemplary implementation one or more components are surface mounted onto a module substrate, and then optionally underfilled. A lid is then secured onto the module substrate and over the component(s). 
     SUMMARY 
     Embodiments describe multiple chip module (MCM) structures in which recessed lid and/or stiffener structure designs are assembled to obtain the mechanical integrity and thermal benefits of a lid, while mitigating stress at the bonding interfaces and protecting integrity of the MCM. In some embodiments, the lid may include a plurality of local peripheral reinforcement structures that extend laterally adjacent to the stiffener structure to provide additional mechanical integrity while assisting alignment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is an exploded isometric view illustration of a module including a lid and stiffener structure with inner and outer support structures in accordance with an embodiment. 
         FIG.  1 B  is an isometric bottom view illustration of a lid with inner and outer walls in accordance with an embodiment. 
         FIGS.  2 A- 2 C  are schematic cross-sectional side view illustrations of lid designs with recessed outer walls in accordance with embodiments. 
         FIGS.  3 A- 3 B  are schematic cross-sectional side view illustrations of lid designs with step recessed outer walls in accordance with embodiments. 
         FIGS.  4 A- 4 D  are schematic cross-sectional side view illustrations of recessed stiffener structure designs in accordance with embodiments. 
         FIGS.  5 A- 5 C  are schematic cross-sectional side view illustrations of step recessed stiffener structure designs in accordance with embodiments. 
         FIG.  6 A  is an exploded isometric top view illustration of a module including a lid with overhanging local peripheral reinforcement structures in accordance with an embodiment. 
         FIG.  6 B  is an isometric bottom view illustration of a lid with overhanging local peripheral reinforcement structures in accordance with an embodiment. 
         FIG.  7 A  is a schematic bottom view illustration of a lid with overhanging local peripheral reinforcement structures arranged over a stiffener structure in accordance with an embodiment. 
         FIG.  7 B  is a close-up schematic cross-sectional side view illustration of a lid with overhanging local peripheral reinforcement structure arranged over a stiffener structure in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     While lids can provide mechanical integrity to an MCM, it has been observed that lids can also induce large stress and high warpage in an MCM and induce mechanical failures. For example, lids formed of copper may have a comparatively high coefficient of thermal expansion (CTE) relative to other module features. This can result in thermal expansion and induce stress and warpage in the MCM components (e.g. packages) when the lid is strongly coupled with the rest of the module. The large stress at the interface (e.g. lid and substrate interface, lid and stiffener interface, etc.) may cause delamination of the bonding material used (e.g. adhesive) or bulk cracking of the bonding material. CTE mismatch between low CTE stiffeners and the rest of the MCM components can cause high stress and mechanical failure as well. In accordance with embodiments, various combinations of lids and stiffener structures (also referred to as stiffener rings) are provided to reduce stresses in the bonding locations and hence protect integrity of the MCM. 
     Referring now to  FIG.  1 A  an exploded isometric view illustration is provided of a module  150  (e.g. MCM) including a lid  300  and stiffener structure  200  with inner support structures  220  and outer support structures  210 .  FIG.  1 B  is an isometric bottom view illustration of a lid  300  with inner walls  320  and outer walls  310  in accordance with an embodiment. In the illustrated embodiment the inner walls  320  can align with the inner support structures  220 , while the outer walls  310  can align with the outer support structures  210 . 
     In the exemplary embodiment, the module  150  includes a module substrate  100  including a top side  102  and bottom side  104 . A plurality of first components  120  can be mounted on the top side  102  of the module substrate  100 . First components  120  may be active or passive devices, and may be chips or packages. For example, first components  120  may be memory packages, such as dynamic random-access memory (DRAM) including one or more dies, which can be stacked dies, or side-by-side. In an embodiment, first components are chip scale packages. First components  120  can additionally be different types of components, and need not be identical. One or more second components  130  can also be mounted on the top side  102  of the module substrate  100 . In an embodiment, a second component  130  is a package that includes a plurality (e.g. two or more) of side-by-side dies. For example, second component  130  may include a plurality of side-by-side logic, or system on chip dies. 
     Referring now to  FIGS.  2 A- 2 C  schematic cross-sectional side view illustrations are provided of lid  300  designs with recessed outer walls  310  in accordance with embodiments. It is to be appreciated that while only outer walls  310  are illustrated, the recessed wall structures in accordance with embodiments can also, or alternatively, be used with the optional inner walls. In an exemplary implementation, first components  120  and second component  130  are surface mounted onto the module substrate  100  using any suitable technique such as solder bumps  160 , with optional underfill  162  (e.g. epoxy). In the illustrated embodiment, the second component  130  is a package that includes a plurality of side-by-side dies  132  on a package substrate  131  and encapsulated in a molding compound  134 . As shown, the space  133  laterally between the dies  132  may be filled with molding compound  134 . It has been observed this can be a high stress location within the MCM due to close proximity of a variety of materials and MCM structures. 
     A thermal interface material (TIM)  170  can be located on top sides of the first components  120  and second component  130  in order to secure to the lid  300 . TIM  170  may be applied using any suitable technique such as dispensing or tape. Exemplary TIM  170  materials include, but are not limited to, thermal grease, solder, metal filled polymer matrix, etc. 
     In accordance with embodiments the lid  300  can be bonded to an intermediate stiffener structure  200  (also referred to as a stiffener ring), which in turn is bonded to the module substrate  100 . The stiffener structure  200  and lid  300  can be bonded using adhesive layers  230 ,  232 . Exemplary adhesive materials include glass paste, epoxies, urethane, polyurethane, silicone elastomers, etc. The lid  300  can similarly be bonded to the stiffener structure  200  after mounting the stiffener structure on the module substrate  100 , or before. 
     The lid  300  may include a roof  330 , outer (periphery) walls  310  and optionally inner walls  320 . The bottom surface  302  of the roof may be bonded to the TIM  170  on top of the second component  130  and first components  120 . Contour of the bottom surface  302  (thickness of the roof  330 ) can be adjusted to evenly mate with the TIM  170  for the various first components  120  and second component  130 . The outer walls  310  and optional inner walls  320  can extend from the roof  330  (e.g. protrude from the bottom surface) to form one or more cavities  305  which accommodate the second component  130  and first components  120 . In accordance with embodiments, the stiffener structure  200  is shaped to mate with the outer walls  310  and optional inner walls  320  of the lid  300 . Specifically, the stiffener structure  200  can include outer support structure (walls)  210  and optional inner support structure  220  (walls). Outer support structure  210  and inner support structure  220  may be integrally formed of the same material. Alternatively, outer support structure  210  and inner support structure  220  can be formed of different materials with different CTE. A variety of additional configurations, with different materials are possible. The mating surfaces between the stiffener structure  200  and lid  300  may have a same surface area. A plurality of module solder bumps  190  may optionally be applied to the bottom side  104  of the module substrate  100  for further integration. 
     In accordance with embodiments, various combinations of lids and stiffener structures are provided to balance the ability of the lid to provide mechanical integrity to the module while not inducing mechanical failure. In particular, various combinations of recessed lid and stiffener structure designs are described. Furthermore, lids with local perimeter reinforcements are described to provide additional mechanical integrity while assisting alignment. 
     In an embodiment a module  150  includes a module substrate  100 , a component (e.g. first component  120 , second component  130 , etc.) on a top side  102  of the module substrate, and a lid  300  mounted on the module substrate and covering the component. The lid may include an outer wall  310  that includes a lid recess  314  in a bottom surface  312  of the outer wall  310 . As shown in  FIGS.  2 A- 3 C , a first adhesive layer  230  can at least partially fill the lid recess  314  in the bottom surface  312  of the outer wall  310 . Such a recessed lid design may allow for a localized thickness increase of the first adhesive layer  230  so that stresses can be reduced. 
     Referring to the embodiments illustrated in  FIGS.  2 A- 2 B , the first adhesive layer  230  may be bonded to both the bottom surface  312  of the outer wall  310  and to the top side  102  of the module substrate. The lid recesses  314  may be formed along different regions of the outer wall  310 . For example, in the embodiment illustrated in  FIG.  2 A  the lid recess  314  is along an outer portion  316  (exterior portion) of the outer wall. Thus, the outer wall  310  may be thicker along an inner portion  318  than an outer portion  316 . Alternatively, the lid recess  314  can be along the inner portion  318  rather than the outer portion  316 . Width of the lid recesses  314  can be varied within a lid  300  as shown in  FIG.  2 A , for specific stress control for example. 
     In the embodiment illustrated in  FIG.  2 A , the lid recess  314  is in the form of a step, which may have a vertical sidewall or tapered sidewall. The lid recess  314  may also be sloped or curved, as shown in  FIG.  2 B . 
     In accordance with embodiment the lid  300  walls can align with the module substrate  100  or stiffener structures. For example, an outer wall  310  bottommost bottom surface  312  may be flat to mate with a flat top side  102  of the module substrate  100 . Inclusion of the lid recesses  314  can reduce flat-on-flat surface area and potentially delamination caused by thermal stresses. Some amount of flat-on-flat surface stacking however can aid with stability. 
     In some embodiments a stiffener structure  200  is stacked between the lid  300  and the module substrate  100 . For example, the stiffener structure  200  can be formed of a lower CTE material than the lid to reduce stress and warpage of the MCM. In an exemplary implementation a low CTE stiffener material can be a nickel-iron alloy (FeNi36), iron-nickel-cobalt alloy (sold under the trademark KOVAR, trademark of CRS Holdings, Inc., Delaware), iron-nickel alloy (Alloy42), stainless steels (SUS410, SUS430), etc. while the lid is formed of a higher CTE material such as copper. 
     Referring now to the embodiment illustrated in  FIG.  2 C , a stiffener structure  200  can be mounted on the top side  102  of the module substrate  100 . Specifically, the top surface of outer support structure  210  of the stiffener structure  200  can be bonded to the bottom surface  312  of the outer wall  310  with the first adhesive layer  230 . A second adhesive layer  232  can be used to bond a bottom surface of the stiffener structure  200  to the top side  102  of the module substrate  100 . In the particular embodiment illustrated, the bottom surface  211  and top surface  212  of the stiffener structure  200  (our outer support structure  210 ) are flat. However, this is not required, and the stiffener structure  200  top and/or bottom surfaces can include stiffener recesses, such as stepped, sloped or curved recesses. The top surface  212  of the stiffener structure can also have a contour that mates with and is opposite of a contour for the bottom surface  312  of the outer wall  310 . 
     In some embodiments, the outer wall  310  includes a stepped lid recess  314 . For example, in the embodiments illustrated in  FIGS.  2 A and  2 C , the lid recess  314  includes a single step. The lid recess  314  may include a plurality of steps as illustrated in  FIGS.  3 A- 3 B . As shown, the steps can proceed as a staircase with continuous increase or decrease in thickness of the outer wall  310  from exterior side to interior side of the lid  300 . The steps can also be variable, such that a larger recess volume in a center portion of the outer wall  310 . 
     Referring now to  FIGS.  4 A- 4 D , schematic cross-sectional side view illustrations are provided of recessed stiffener structure  200  designs in accordance with embodiments. Similar to the recessed lid designs, the stiffener structure  200  can alternatively be recessed, or recessed in combination with the lid  300 . In an embodiment, a module  150  includes a module substrate  100 , a component (first component  120  and/or second component  130 ) on a top side  102  of the module substrate, a stiffener structure  200  mounted on the top side  102  of the module substrate, and a lid  300  mounted on the stiffener structure  200  and covering the component. A first adhesive layer  230  can be used to bond the top surface  212  of the stiffener structure  200  to the lid  300 , and a second adhesive layer  232  can be used to bond the bottom surface  211  of the stiffener structure  200  to the module substrate  100 . In accordance with embodiments, a stiffener recess  214  is formed in either, or both, of the top surface  212  and bottom surface  211  of the stiffener structure  200 . 
     The stiffener recesses  214  may be formed along different regions of the stiffener structure  200  (e.g. within outer support structure  210  and inner support structure  220 ). For example, in the embodiment illustrated in  FIG.  4 A  the stiffener recess  214  is along an outer portion  216  (exterior portion) of the outer support structure. Thus, the outer support structure  210  may be thicker along an inner portion  218  than an outer portion  216 . Alternatively, the stiffener recess  214  can be along the inner portion  218  rather than the outer portion  216 . Width of the stiffener recesses  214  can be varied within a stiffener structure  200  as shown in  FIG.  2 A , for specific stress control for example. 
     In the embodiment illustrated in  FIGS.  4 A- 4 C , the stiffener recess  214  is in the form of a step, which may have a vertical sidewall or tapered sidewall. The stiffener recess  214  may also be sloped or curved, as shown in  FIG.  4 D . 
     In accordance with embodiment the stiffener structure can align with the module substrate  100  and lid  300 . For example, a bottommost bottom surface  211  may be flat to mate with a flat top side  102  of the module substrate  100 . A topmost top surface  212  may be flat to mate with a flat bottom surface  312  of the lid  300 . Inclusion of the stiffener recesses  214  can reduce flat-on-flat surface area and potentially delamination caused by thermal stresses. Some amount of flat-on-flat surface stacking however can aid with stability. 
     In some embodiments, the stiffener structure  200  includes a stepped stiffener recess  214 . For example, in the embodiments illustrated in  FIGS.  4 A- 4 C , the lid recess  314  includes a single step. The lid recess  314  may include a plurality of steps on one or both sides as illustrated in  FIGS.  5 A- 5 C . As shown, the steps can proceed as a staircase with continuous increase or decrease in thickness of the stiffener structure  200  from exterior side to interior side of the stiffener structure  200 . The steps can also be variable, such that a larger recess volume in a center portion of the stiffener structure  200 . 
     Referring again briefly o  FIGS.  4 A and  5 A , the lids  300  in accordance with embodiments when used with stiffener structures  200  may or may not include inner and outer walls. As shown, the stiffener structures  200  can be bonded to the bottom surfaces of the outer walls  310 , as well as inner walls, or to the bottom surface  302  of roof  330 . 
     Up until this point, various combinations of recessed lids and stiffener have been described to balance the ability of the lid to provide mechanical integrity to the module while not inducing mechanical failure. In order to further facilitate alignment of the lids  300  and stiffener structures  200 , local peripheral reinforcement structures (or local caps) can be included on the lids  300  to provide additional mechanical integrity while assisting alignment. 
     Referring now to  FIGS.  6 A- 6 B ,  FIG.  6 A  is an exploded isometric top view illustration of a module  150  including a lid  300  with overhanging local peripheral reinforcement structures  350  in accordance with an embodiment;  FIG.  6 B  is an isometric bottom view illustration of a lid  300  with overhanging local peripheral reinforcement structures  350  in accordance with an embodiment.  FIGS.  6 A- 6 B  are substantially similar to  FIGS.  1 A- 1 B  with addition of the local peripheral reinforcement structures  350 . In accordance with embodiments, the lid  300  can be mounted onto the module substrate  100 , optionally with an intermediate stiffener structure  200  therebetween. In such embodiments, the lid  300  and/or optional stiffener structure  200  can include any combination of the various recess designs described herein. Furthermore, embodiments envision modules  150  including a lid with local peripheral reinforcement structures  350  without combination with the various recess designs described herein. 
     In an embodiment, a module  150  includes a module substrate  100 , a component on a top side  102  of the module substrate, a stiffener structure  200  mounted on the top side  102  of the module substrate  100 , and a lid  300  mounted on the stiffener structure  200  and covering the component. In an embodiment, the lid  300  includes a plurality of local peripheral reinforcement structures  350  extending laterally adjacent to the stiffener structure  200 . In the particular embodiment illustrated in  FIGS.  6 A- 6 B , the local peripheral reinforcement structures  350  are located at corners of the lid  300 . However, the local peripheral reinforcement structures  350  can formed at other locations, such as along side edges of the lid  300 . In both configurations, the locations and closeness to the side edges of the stiffener structure  200  can mitigate x-y shift of the lid  300  and facilitate integrity of the adhesive bonds. 
     Referring now to  FIGS.  7 A- 7 B ,  FIG.  7 A  is a schematic bottom view illustration of a lid  300  with overhanging local peripheral reinforcement structures  350  arranged over a stiffener structure  200  in accordance with an embodiment;  FIG.  7 B  is a close-up schematic cross-sectional side view illustration of a lid  300  with overhanging local peripheral reinforcement structure  350  arranged over a stiffener structure  200  in accordance with an embodiment. In an embodiment, the local peripheral reinforcement structures  350  extend from an outer wall  310  of the lid  300 . More specifically, the local peripheral reinforcement structures  350  are formed by an additional width (W) of the lid  300 , and protrude from a bottommost bottom surface  312  of the outer wall  310  which rests on the reinforcement structure  200 . The local reinforcement structures  350  may be in the form of a hanging lip of length (L), including a width (w) an inner surface that is spaced apart from the reinforcement structure  200  by a gap (G). The length (L) may be a distance between the bottom surface  312  of the outer wall  310  and a bottom surface  352  of the lip. The gap (G) distance may be designed to balance alignment and processability. In some embodiments, the length (L) of the local reinforcement structure  350  can extend laterally adjacent to a side edge of the module substrate  100 . Such a configuration can be achieved both with and without the stiffener structure  200 . 
     In utilizing the various aspects of the embodiments, it would become apparent to one skilled in the art that combinations or variations of the above embodiments are possible for forming module with recessed lid and/or ring designs and lid with local peripheral reinforcement structures. Although the embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the specific features or acts described. The specific features and acts disclosed are instead to be understood as embodiments of the claims useful for illustration.

Metadata:
Filing Date: 20210830
Publication Date: 20241015
Grant Date: 20241015
Priority Date: 20210830
Inventors: CHEN, WEI
ZHAO, JIE-HUA
ZHAI, JUN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L23/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/3511", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/562", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/053", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L23/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L23/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L23/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/053", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 85288627