Flip-chip assembly of protected micromechanical devices
First Claim
1. A packaged micromechanical device comprising:
- a semiconductor chip having an integrated circuit including a plurality of micromechanical components configured in a plane in the central portion of said chip, and a plurality of metallic terminals disposed in peripheral portions, surrounding said chip;
an electrically insulting substrate having first and second surfaces and an opening, said surfaces being substantially parallel to each other;
a plurality of electrically conductive routing lines integral with said substrate;
a first plurality of metallic contact pads disposed on said first surface, in proximity to said opening and electrically connected with said routing lines;
a second plurality of metallic contact pads disposed on said first surface, remote from said opening and electrically connected with said routing lines;
a plurality of solder balls electrically connecting said terminals to said first plurality of contact pads, mounting said chip onto said substrate spaced apart by a gap, whereby one level of said opening is closed, and positioning said substrate in a plane parallel to said components plane;
a polymer encapsulant filling said gap, surrounding said opening with a continuous frame of polymer; and
a lid adhered to said second surface in a plane parallel to said components plane, whereby a second level of said opening is closed.
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Accused Products
Abstract
A low-cost ceramic package, in land-grid array or ball-grid array configuration, for micromechanical components is fabricated by coating the whole integrated circuits wafer with a protective material, selectively etching the coating for solder ball attachment, singulating the chips, flip-chip assembling a chip onto the opening of a ceramic substrate, underfilling the gaps between the solder joints with a polymeric encapsulant, removing the protective material form the components, and attaching a lid to the substrate for sealing the package.
It is an aspect of the present invention to be applicable to a variety of different semiconductor micromechanical devices, for instance actuators, motors, sensors, spatial light modulators, and deformable mirror devices. In all applications, the invention achieves technical advantages as well as significant cost reduction and yield increase.
83 Citations
23 Claims
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1. A packaged micromechanical device comprising:
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a semiconductor chip having an integrated circuit including a plurality of micromechanical components configured in a plane in the central portion of said chip, and a plurality of metallic terminals disposed in peripheral portions, surrounding said chip;
an electrically insulting substrate having first and second surfaces and an opening, said surfaces being substantially parallel to each other;
a plurality of electrically conductive routing lines integral with said substrate;
a first plurality of metallic contact pads disposed on said first surface, in proximity to said opening and electrically connected with said routing lines;
a second plurality of metallic contact pads disposed on said first surface, remote from said opening and electrically connected with said routing lines;
a plurality of solder balls electrically connecting said terminals to said first plurality of contact pads, mounting said chip onto said substrate spaced apart by a gap, whereby one level of said opening is closed, and positioning said substrate in a plane parallel to said components plane;
a polymer encapsulant filling said gap, surrounding said opening with a continuous frame of polymer; and
a lid adhered to said second surface in a plane parallel to said components plane, whereby a second level of said opening is closed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of fabricating land-grid array devices for semiconductor chips having an integrated circuit including a plurality of micromechanical components configured in a plane in the central portion of said chip and a plurality of metallic terminals disposed in peripheral portions encircling said chip, comprising:
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providing a wafer having a surface including a plurality of said chips;
coating said wafer surface with a protective material;
selectively etching said protective coating, exposing said terminals of each of said chips;
depositing one solder ball on each of said exposed terminals;
separating the resulting composite structure into discrete chips;
providing an electrically insulating substrate having first and second surfaces and an opening, said surfaces being substantially parallel to each other, a first plurality of metallic contact pads disposed on said first surface in proximity to said opening, and a second plurality of metallic contact pads disposed on said first surface remote from said opening;
mounting one of said discrete chips on said first plurality of substrate contact pads by forming solder joints, spaced apart by a gap;
controlling the height of said solder joints to maintain uniformity, thereby positioning said substrate in a plane parallel to said components plane;
filling said gap with a polymeric encapsulant, surrounding said opening by a continuous frame of encapsulant;
removing said protective material, thereby exposing the surfaces of said components; and
attaching a lid to said second substrate surface, thereby positioning said lid in a plane parallel to said plane of said components. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification