Patterned Chip Bump Structure for Grinding Depth Alignment
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Solution Overview
Problem
The challenge in existing chip structure and semiconductor package fabrication is the difficulty in controlling the depth of grinding the encapsulant, leading to either insufficient or excessive exposure of metal bumps, which can damage pads and affect yield.
Innovation Solution
A chip structure with patterned bumps having two distinct plane patterns at different heights is introduced, allowing for precise control of grinding depth by ensuring one pattern is flush with metal bumps, thus preventing over-exposure or under-exposure during encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the encapsulant is ground to expose metal bumps, then the metal bumps can be accessed for wiring, but the grinding depth is difficult to control leading to either insufficient exposure or over-ground damage
Solution Approach 1:
The patent introduces a patterned bump structure with two different plane patterns at different heights as an intermediary reference feature. The first plane pattern at the first height serves as a mediator between the metal bumps and the grinding process, providing a visible reference that indicates when the metal bumps are properly exposed without requiring direct measurement of the metal bump exposure itself.
Solution Approach 2:
The patterned bumps with two plane patterns are formed on the chip body before the grinding process. The first plane pattern at the first height is prepared in advance as a reference feature that will be exposed during grinding, allowing the grinding depth to be controlled and monitored during the process rather than relying on post-grinding inspection.
2Manufacturing precision
If the encapsulant is ground deeper to ensure metal bump exposure, then more metal bumps are exposed, but the pads may be damaged due to excessive grinding
Solution Approach 1:
The first plane pattern of the patterned bumps acts as an intermediary reference feature that indicates the correct grinding depth. By monitoring the exposure of this plane pattern during grinding, the process can be stopped at the appropriate depth before the pads are damaged, preventing the harmful effect of over-grinding while ensuring sufficient metal bump exposure.
Solution Approach 2:
The patterned bumps with the first plane pattern at the first height serve as a protective reference feature that cushions against the risk of over-grinding. This reference structure allows for real-time monitoring of grinding depth, enabling the operator to stop the grinding process before the pads are damaged, thus preventing harm before it occurs.
3Object-affected harmful factors
If the encapsulant is ground less to avoid pad damage, then pad damage is reduced, but the metal bumps are not sufficiently exposed
Solution Approach 1:
The first plane pattern of the patterned bumps serves as a mediator that provides visual feedback during the grinding process. This reference feature allows the operator to monitor the grinding depth and determine when the metal bumps are sufficiently exposed without needing to over-grind, thus achieving adequate exposure while preventing pad damage.
Solution Approach 2:
The patterned bumps with the first plane pattern at the first height provide visual feedback during the grinding process. As the encapsulant is ground away, the exposure of the first plane pattern indicates the grinding depth, allowing real-time adjustment and monitoring to ensure sufficient metal bump exposure while preventing excessive grinding that would damage the pads.
Data Source
AI summary
A chip structure has a chip body having a plurality of pads, a plurality of metal bumps respectively formed on the pads, and a patterned bump directly formed on the chip body. The patterned bump has at least two different upper and lower plane patterns. A top surface of each of the metal bumps is higher than a height position on which the upper plane pattern is. When the chip structure is ground to the height position, the ground tops of the metal bumps and the upper plane pattern are flush. Therefore, detecting whether the upper plane pattern is exposed determines whether all the metal bumps are exposed and flush to each other to avoid insufficient grinding depth or over-ground.