Post fabrication processing of semiconductor chips
First Claim
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1. A method for forming a pattern of electrically conductive pads on a semiconductor device, said semiconductor device having an active side and a passive side, comprising the steps of:
- creating a plurality of bumps on said active side in accordance with said pattern, said bumps having edges, said edges being separated from the adjacent edge of the adjacent bump by a nominal distance, and said bumps having a nominal width;
patterning on said active side a mask, said mask having openings above said bumps, each of said openings having walls, said walls being separated by a nominal width, and said walls being separated from the adjacent wall of the adjacent opening by a nominal distance, said nominal width of separation of said walls being less than said nominal width of said bumps, and said nominal distance separating said bumps being less than said nominal distance separating said adjacent walls of adjacent openings;
depositing into said openings a flowable alloy, said flowable alloy contacting said walls and completely filling the width between said walls;
completely removing said mask.
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Abstract
A method for processing semiconductor chips which deters the formation of "tin whiskers" and which removes excess substrate material from the passive side of a semiconductor device is presented. The deterrence of tin whiskers is accomplished by controlling the size of the bead of flowable metal on the conductive bump. The removal of excess material from the passive side of the semiconductor device is accomplished by chemical reaction after the formation of the conductive bump.
75 Citations
23 Claims
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1. A method for forming a pattern of electrically conductive pads on a semiconductor device, said semiconductor device having an active side and a passive side, comprising the steps of:
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creating a plurality of bumps on said active side in accordance with said pattern, said bumps having edges, said edges being separated from the adjacent edge of the adjacent bump by a nominal distance, and said bumps having a nominal width; patterning on said active side a mask, said mask having openings above said bumps, each of said openings having walls, said walls being separated by a nominal width, and said walls being separated from the adjacent wall of the adjacent opening by a nominal distance, said nominal width of separation of said walls being less than said nominal width of said bumps, and said nominal distance separating said bumps being less than said nominal distance separating said adjacent walls of adjacent openings; depositing into said openings a flowable alloy, said flowable alloy contacting said walls and completely filling the width between said walls;
completely removing said mask. - View Dependent Claims (2, 3, 4, 5, 6, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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7. A method for forming a row of aligned electrically conductive pads on a semiconductor device comprising the steps of:
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creating a plurality of electrically conductive bumps in accordance with the desired pattern of said row, said bumps having edges, said bumps having a nominal width along the axis of alignment of the conductive pads, and said bump edges having a nominal distance between the adjacent bump edges of adjacent bumps; patterning on said bumps a mask, said mask having openings above said bumps, said openings having edges, said openings having a nominal width along the axis of alignment of the conductive pads, and said opening edges having a nominal distance between the adjacent edges of adjacent openings, wherein said nominal distance between said opening edges is greater than said nominal distance between said bumps; depositing into said openings a flowable alloy and completely removing said mask.
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8. A method for physically and electrically connecting at least one TAB lead with a bump on a semiconductor device comprising the steps of:
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creating a plurality of bumps, said bumps having edges, said edges being separated from the adjacent edge of the adjacent bump by a nominal distance, and said bumps having a nominal width; patterning on said bumps a mask, said mask having openings above said bumps, each of said openings having walls, said walls being separated by a nominal width, and said walls being separated from the adjacent wall of the adjacent opening by a nominal distance, said nominal width of separation of said walls being less than said nominal width of said bumps, and said nominal distance separating said bumps being lesser than said nominal distance separating said adjacent walls of adjacent openings; depositing into said openings a bead of a flowable alloy said flowable alloy contacting said walls and completely filling the width between said walls;
completely removing said mask;
placing said TAB lead on said flowable alloy on one of said bumps;
causing said flowable alloy to flow and causing said flowable alloy to solidify. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification