Flip Chip Wafer Groove Support Ring Method
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Solution Overview
Problem
The existing flip chip technology for semiconductor packaging is complex and inefficient, with low production efficiency due to the need for deep grooves or thinning of the wafer, which can lead to lattice damage and corrosion during the etching process.
Innovation Solution
A method that involves forming a support ring at the back surface of the wafer to provide mechanical support, allowing for thinning without breaking, and using a partial plastic package layer that exposes scribe lines to facilitate cutting into individual semiconductor devices without the need for deep grooves or grinding, enabling easier separation and attachment to a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If deep grooves are formed or wafer is thinned to expose grooves for cutting, then individual semiconductor devices can be separated, but the wafer becomes prone to breaking and lattice damage occurs during etching
Solution Approach 1:
The patent applies preliminary action by forming grooves at the front surface of the wafer before any thinning or breaking occurs. These pre-formed grooves serve as guides for subsequent cutting operations, eliminating the need to thin the wafer or create deep grooves that would compromise structural integrity. The grooves are formed at a safe depth that maintains wafer strength while still enabling effective separation.
Solution Approach 2:
The patent transitions from the conventional approach of creating deep vertical grooves or thinning the wafer thickness to forming grooves at the front surface dimension. This dimensional change allows cutting to be guided by surface-level grooves rather than requiring penetration through the entire wafer thickness, thereby maintaining structural integrity while achieving effective device separation.
2Ease of manufacture
If the wafer is thinned to expose grooves from the back, then cutting can be performed, but the back side is vulnerable to corrosion during etching due to prior grinding and ion injection
Solution Approach 1:
The patent forms grooves at the front surface before any thinning or etching operations. This preliminary groove formation allows subsequent cutting to be performed without needing to thin the wafer or expose grooves from the back, thereby avoiding the corrosion-prone etching step on the vulnerable back surface.
Solution Approach 2:
The patent extracts the groove formation step from the back surface processing sequence and relocates it to the front surface. This extraction eliminates the need to thin the wafer to expose grooves from the back, thereby removing the wafer back surface from the harmful etching environment and preventing corrosion.
3Ease of operation
If conventional flip chip process is used with multiple handling steps, then chips can be flipped and mounted, but production efficiency is extremely low
Solution Approach 1:
The patent merges the chip separation and chip mounting operations into a single integrated process. By forming grooves at the front surface that guide cutting, the wafer can be cut into individual chips that remain attached to the substrate, eliminating the need for separate handling, flipping, and mounting steps. This consolidation dramatically improves production efficiency while maintaining mounting capability.
Solution Approach 2:
The patent segments the conventional multi-step flip chip process into a simplified integrated process. Instead of separate steps for chip separation, handling, flipping, and mounting, the groove-guided cutting method enables direct separation and attachment in one operation, reducing process complexity and improving productivity.
Data Source
AI summary
A method for preparing semiconductor devices in a flip chip process comprises forming deep grooves surrounding each of the semiconductor chips; depositing a first plastic package material to form a first plastic package layer covering front surface of the semiconductor wafer and filling the deep grooves; depositing a metal layer at back surface of the semiconductor wafer after grinding; grinding an outermost portion of the metal layer thus forming a ring area located at back surface around edge of the semiconductor wafer not covered by the metal layer; cutting the first plastic package layer, the semiconductor wafer, the metal layer and the first plastic package material filled in the deep grooves along a straight line formed by two ends of each of the deep grooves filled with the first plastic package material; and picking up the semiconductor devices and mounting on a substrate without flipping the semiconductor devices.