Semiconductor flip-chip package and method for the fabrication thereof

Abstract

A simplified process for flip-chip attachment of a chip to a substrate is provided by pre-coating the chip with an encapsulant underfill material having separate discrete solder columns therein to eliminate the conventional capillary flow underfill process. Such a structure permits incorporation of remeltable layers for rework, test, or repair. It also allows incorporation of electrical redistribution layers. In one aspect, the chip and pre-coated encapsulant are placed at an angle to the substrate and brought into contact with the pre-coated substrate, then the chip and precoated encapsulant are pivoted about the first point of contact, expelling any gas therebetween until the solder bumps on the chip are fully in contact with the substrate. There is also provided a flip-chip configuration having a complaint solder/flexible encapsulant understructure that deforms generally laterally with the substrate as the substrate undergoes expansion or contraction. With this configuration, the complaint solder/flexible encapsulant understructure absorbs the strain caused by the difference in the thermal coefficients of expansion between the chip and the substrate without bending the chip and substrate.

1 .- 52 . (canceled)  
     
     
         53 . An encapsulated semiconductor chip comprising an active surface with an encapsulant composition deposited on said active surface, said encapsulant composition comprising at least two distinct portions: 
 a) a distinct first portion having a thermally curable composition comprising an inorganic filler; and    b) a distinct second portion having a thermally curable composition without an inorganic filler.    
     
     
         54 . The encapsulated semiconductor chip of  claim 53  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         55 . The encapsulated semiconductor chip of  claim 53  wherein the inorganic filler material comprises silica.  
     
     
         56 . The encapsulated semiconductor chip of  claim 53  wherein said encapsulant composition is a solid.  
     
     
         57 . The encapsulated semiconductor chip of  claim 53  wherein said encapsulant composition is a viscous liquid.  
     
     
         58 . The encapsulated semiconductor chip of  claim 53  wherein the semiconductor chip further comprises solder bumps.  
     
     
         59 . The encapsulated semiconductor chip of  claim 53  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         60 . The encapsulated semiconductor chip of  claim 53  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         61 . The encapsulated semiconductor chip of  claim 53  wherein the thermally curable composition of the distinct second portion is uncured.  
     
     
         62 . A method for manufacturing an encapsulated semiconductor chip comprising the steps of: 
 a) providing a chip with solder bumps on an active surface thereof;    b) depositing a distinct first portion of an encapsulant composition on said active surface, said distinct first portion having a having a thermally curable composition comprising an inorganic filler;    c) providing a substrate having a pattern of separate discrete solderable metal pads thereon, at least one of said pads corresponding to at least one of said solder bumps;    d) depositing a distinct second portion of said encapsulant composition on said substrate surface, said distinct second portion having a thermally curable composition without an inorganic filler and wherein said first distinct portion has a large amount of inorganic filler with respect to the amount of inorganic filler in said second distinct portion; and    e) attaching the chip to the substrate to form said encapsulated semiconductor chip wherein the solder bumps are facing the substrate and aligned with the solder pads.    
     
     
         63 . The method according to  claim 62  further comprising the step of heating the encapsulated semiconductor chip to cure said encapsulant composition and reflow the solder, said heating being done after the step of attachment.  
     
     
         64 . The method according to  claim 63  wherein the step of heating is accomplished using solder reflow technology.  
     
     
         65 . The method of  claim 62  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         66 . The method of  claim 62  wherein the inorganic filler material comprises silica.  
     
     
         67 . The method of  claim 62  wherein said encapsulant composition is a solid.  
     
     
         68 . The method of  claim 62  wherein said encapsulant composition is a viscous liquid.  
     
     
         69 . The method of  claim 62  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         70 . The method of  claim 62  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         71 . The method of  claim 62  wherein the thermally curable composition of the distinct second portion is uncured.  
     
     
         72 . A method for manufacturing an encapsulated semiconductor chip comprising the steps of: 
 a) providing a chip with solder bumps on an active surface thereof;    b) depositing a distinct first portion of an encapsulant composition on said active surface, said distinct first portion having a having a thermally curable composition comprising an inorganic filler;    c) depositing a distinct second portion of said encapsulant composition on said distinct first portion, said distinct second portion having a thermally curable composition without an inorganic filler and wherein said first distinct portion has a large amount of inorganic filler with respect to the amount of inorganic filler in said second distinct portion;    d) providing a substrate having a pattern of separate discrete solderable metal pads thereon, at least one of said pads corresponding to at least one of said solder bumps; and    e) attaching the chip to the substrate to form said encapsulated semiconductor chip wherein the solder bumps are facing the substrate and aligned with the solder pads.    
     
     
         73 . The method according to  claim 72  further comprising the step of heating the encapsulated semiconductor chip to cure said encapsulant composition and reflow the solder, said heating being done after the step of attachment.  
     
     
         74 . The method according to  claim 73  wherein the step of heating is accomplished using solder reflow technology.  
     
     
         75 . The method of  claim 72  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         76 . The method of  claim 72  wherein the inorganic filler material comprises silica.  
     
     
         77 . The method of  claim 72  wherein said encapsulant composition is a solid.  
     
     
         78 . The method of  claim 72  wherein said encapsulant composition is a viscous liquid.  
     
     
         79 . The method of  claim 72  wherein the semiconductor chip further comprises solder bumps.  
     
     
         80 . The method of  claim 72  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         81 . The method of  claim 72  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         82 . The method of  claim 72  wherein the thermally curable composition of the distinct second portion is uncured.  
     
     
         83 . An encapsulated semiconductor chip comprising an active surface with an encapsulant composition deposited on said active surface, said encapsulant composition comprising at least two distinct portions: 
 a) a distinct first portion having a thermally curable composition comprising an inorganic filler; and    b) a distinct second portion having a thermally curable composition comprising an inorganic filler;    wherein said first distinct portion has a large concentration of inorganic filler with respect to the concentration of inorganic filler in said second distinct portion.    
     
     
         84 . The encapsulated semiconductor chip of  claim 83  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         85 . The encapsulated semiconductor chip of  claim 83  wherein the inorganic filler material comprises silica.  
     
     
         86 . The encapsulated semiconductor chip of  claim 83  wherein said encapsulant composition is a solid.  
     
     
         87 . The encapsulated semiconductor chip of  claim 83  wherein said encapsulant composition is a viscous liquid.  
     
     
         88 . The encapsulated semiconductor chip of  claim 83  wherein the semiconductor chip further comprises solder bumps.  
     
     
         89 . The encapsulated semiconductor chip of  claim 83  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         90 . The encapsulated semiconductor chip of  claim 83  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         91 . The encapsulated semiconductor chip of  claim 83  wherein the thermally curable composition of the distinct second portion is uncured.  
     
     
         92 . A method for manufacturing an encapsulated semiconductor chip comprising the steps of: 
 a) providing a chip with solder bumps on an active surface thereof;    b) depositing an encapsulant on said active surface, said encapsulant comprising: 
 (1) a distinct first portion thermally curable composition comprising an inorganic filler;  
 (2) a distinct second portion thermally curable composition without an inorganic filler;  
   d) providing a substrate having a pattern of separate discrete solderable metal pads thereon, at least one of said pads corresponding to at least one of said solder bumps; and    e) attaching the chip to the substrate to form said encapsulated semiconductor chip wherein the solder bumps are facing the substrate and aligned with the solder pads.    
     
     
         93 . The method according to  claim 92  further comprising the step of heating the encapsulated semiconductor chip to cure said encapsulant composition and reflow the solder, said heating being done after the step of attachment.  
     
     
         94 . The method according to  claim 93  wherein the step of heating is accomplished using solder reflow technology.  
     
     
         95 . The method of  claim 92  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         96 . The method of  claim 92  wherein the inorganic filler material comprises silica.  
     
     
         97 . The method of  claim 92  wherein said encapsulant composition is a solid.  
     
     
         98 . The method of  claim 92  wherein said encapsulant composition is a viscous liquid.  
     
     
         99 . The method of  claim 92  wherein the semiconductor chip further comprises solder bumps.  
     
     
         100 . The method of  claim 92  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         101 . The method of  claim 92  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         102 . The method of  claim 92  wherein the thermally curable composition of the distinct second portion is uncured.  
     
     
         103 . The method of  claim 92  wherein said first distinct portion has a large amount of inorganic filler with respect to the amount of inorganic filler in said second distinct portion.  
     
     
         104 . A method for manufacturing an encapsulated semiconductor chip comprising the steps of: 
 a) providing a chip with solder bumps on an active surface thereof;    b) depositing an encapsulant on said active surface, said encapsulant comprising: 
 (1) a distinct first portion having a thermally curable composition comprising an inorganic filler; and;  
 (2) a distinct second portion having a thermally curable composition comprising an inorganic filler, wherein said first distinct portion has a large concentration of inorganic filler with respect to the concentration of inorganic filler in said second distinct portion.  
   d) providing a substrate having a pattern of separate discrete solderable metal pads thereon, at least one of said pads corresponding to at least one of said solder bumps; and    e) attaching the chip to the substrate to form said encapsulated semiconductor chip wherein the solder bumps are facing the substrate and aligned with the solder pads.    
     
     
         105 . The method according to  claim 104  further comprising the step of heating the encapsulated semiconductor chip to cure said encapsulant composition and reflow the solder, said heating being done after the step of attachment.  
     
     
         106 . The method according to  claim 105  wherein the step of heating is accomplished using solder reflow technology.  
     
     
         107 . The method of  claim 104  wherein the thermally curable composition of the distinct first portion further comprises an epoxy resin.  
     
     
         108 . The method of  claim 104  wherein the inorganic filler material comprises silica.  
     
     
         109 . The method of  claim 104  wherein said encapsulant composition is a solid.  
     
     
         110 . The method of  claim 104  wherein said encapsulant composition is a viscous liquid.  
     
     
         111 . The method of  claim 104  wherein the semiconductor chip further comprises solder bumps.  
     
     
         112 . The method of  claim 104  wherein the thermally curable composition of the distinct second portion has fluxing properties.  
     
     
         113 . The method of  claim 104  wherein the thermally curable composition of the distinct first portion is uncured.  
     
     
         114 . The method of  claim 104  wherein the thermally curable composition of the distinct second portion is uncured.