Backside Trench Chip Separation for Low-Force Thin-Die Pick-Up
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Solution Overview
Problem
The conventional method of singularizing electronic chips from a wafer requires high pick-up forces, especially for very thin chips, leading to potential damage and increased pick-up time, and limits the minimum thickness and maximum size of chips that can be handled.
Innovation Solution
Forming trenches on the back side of the wafer around the electronic chips, covering them with back side metallization, and attaching an adhesive layer to fill the trenches during separation, allowing for low-force pick-up by reducing burr and recast formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cutting method is used to separate electronic chips from wafer, then chips can be separated, but high pick-up force is required which may damage very thin chips and increases pick-up time
Solution Approach 1:
The wafer is divided into individual chip regions by forming trenches between adjacent chips. These trenches create physical separations that allow each chip to be independently handled with lower force, eliminating the need to lift entire wafer sections simultaneously.
Solution Approach 2:
An adhesive layer is introduced as an intermediary between the wafer back side metallization and the pickup tool. This adhesive layer distributes the pick-up force across a larger area and reduces stress concentration on individual chips, enabling lower peak forces to be used during chip separation and pickup.
2Productivity
If conventional cutting method is used, then chips can be separated, but pick-up time increases due to high force requirements and sequential processing
Solution Approach 1:
By pre-forming trenches that segment the wafer into individual chip regions, multiple chips can be prepared for simultaneous pickup. The segmentation allows parallel processing of multiple chips, reducing the total pick-up time compared to sequential handling of individual chips.
Solution Approach 2:
The trenches are formed and adhesive layers are applied to the back side metallization before the actual chip pickup operation. This preliminary preparation ensures that when pickup occurs, the chips are already positioned and ready for immediate separation, eliminating setup time during the pickup process itself.
3Reliability
If back side metallization is present, then electrical connects are provided, but pick-up force increases making thin chips prone to damage
Solution Approach 1:
The adhesive layer serves as an intermediary between the pickup tool and the back side metallization. It transfers the pick-up force to the metallization structure in a distributed manner, allowing the metallization to provide electrical connectivity without requiring high concentrated forces that would damage thin chips.
Solution Approach 2:
The back side metallization is selectively formed in specific patterns and regions to provide necessary electrical connections only where required. This localized metallization approach maintains electrical functionality while minimizing the overall force required for pickup, as metal is present only in essential connection areas rather than covering the entire chip surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables defect-free, low-force pick-up of thin chips, reducing the risk of damage and shortening the pick-up time, while increasing the pickup capability for smaller and thinner chips.
Implementation Method 1
attaching an adhesive layer of a tape to at least part of the back side metallization, and separating the electronic chip by removing material from a front side of the wafer along a separation path which includes part of the at least one trench in such a way that, during separating, the adhesive layer fills at least part of the at least one trench above a level of the back side metallization on the back side
Data Source
AI summary
A method of separating an electronic chip from a wafer is disclosed. In one aspect, the method comprises forming at least one trench in a back side of the wafer around at least part of the electronic chip to be separated, forming a back side metallization covering at least part of the back side and at least part of the at least one trench and attaching an adhesive layer of a tape to at least part of the back side metallization. The electronic chip is separated by removing material from a front side of the wafer along a separation path which includes part of the at least one trench in such a way that, during separating, the adhesive layer fills at least part of the at least one trench above a level of the back side metallization on the back side.