Die Pad Projections for Semiconductor Bonding Integrity
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Solution Overview
Problem
The challenge is to prevent the bonding material from reaching the upper and lower surfaces of semiconductor chips, which can cause electrical shorting when the chips are reduced in thickness to 200 μm or less, as the bonding material may cover electrodes or extend between surfaces.
Innovation Solution
A die pad with projections of different shapes (pedestal and bank shapes) on its surface is used, where the semiconductor chip is placed such that its ends are positioned above grooves between these projections, allowing the bonding material to fill the grooves and prevent it from reaching the chip surfaces, thereby maintaining electrical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the semiconductor chip thickness is reduced to 200 μm or less to improve stacking capabilities, then the stacking capability is improved, but the bonding material may reach the upper and lower surfaces of the chip causing electrical shorting
Solution Approach 1:
The bonding area is segmented into multiple regions by dividing it into a plurality of bonding areas with bonding materials disposed therebetween. This segmentation prevents the bonding material from reaching the chip surfaces by creating isolated bonding zones separated by die pad regions, thereby maintaining electrical integrity even when chip thickness is reduced to 200 μm or less
Solution Approach 2:
Different regions of the die pad are assigned different functions: some regions serve as bonding areas for electrical connection while others serve as insulating regions. This local differentiation ensures that bonding materials remain confined to specific zones and do not bridge across the chip thickness, resolving the electrical shorting risk while maintaining thin chip design
2Strength
If the bonding material is applied to bond the chip to the die pad, then the bonding strength is achieved, but the bonding material may extend up to the upper surface of the chip covering electrodes
Solution Approach 1:
The die pad surface is divided into distinct bonding areas and non-bonding areas. By confining bonding materials to specific segmented zones and providing spacing between bonding areas, the design ensures that bonding material does not spread to cover electrodes on the chip upper surface, maintaining manufacturing precision while achieving adequate bonding strength
Solution Approach 2:
The die pad structure acts as an intermediary between the bonding material and the chip electrodes. By designing the die pad with specific bonding area configurations and spacing, it mediates the bonding process to prevent direct contact between bonding material and electrodes, thereby preventing electrode coverage while maintaining bonding integrity
Data Source
AI summary
The specification discloses a technique for preventing a bonding material from reaching the upper and lower surfaces of a semiconductor chip in bonding the semiconductor chip using the bonding material. A die pad of the technique disclosed in the specification includes the following: a die pad substrate; a first projection disposed on the upper surface of the die pad substrate, the first projection having a pedestal shape; a second projection disposed on the upper surface of the die pad substrate so as to surround at least part of the first projection in a plan view, the second projection having a bank shape; and a third projection disposed on the upper surface of the die pad substrate so as to surround at least part of the second projection in a plan view, the third projection having a bank shape.