Wafer Level Stack Die Placement Using Photosensitive Adhesive Tape
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Solution Overview
Problem
Conventional methods for stack die placement are inefficient and time-consuming, requiring individual picking and placing of dice, which limits the throughput and efficiency in multi-chip package manufacturing.
Innovation Solution
A method involving a wafer adhered to a photosensitive adhesive tape, where the tape is selectively exposed to create adhesion-released portions, allowing multiple dice to be detached and fixed on die carriers in batches, facilitating rapid wafer level stack die placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If individual picking and placing of dice is used, then precision of die placement is maintained, but productivity is reduced
Solution Approach 1:
The patent merges multiple individual die placement operations into a single batch operation by attaching multiple dice to a common carrier wafer. The carrier wafer serves as a temporary platform that holds multiple dice in their final positions, allowing simultaneous transfer to the target substrate. This combining of operations directly addresses the productivity issue by eliminating the sequential nature of conventional pick-and-place methods.
Solution Approach 2:
The patent performs preliminary attachment of multiple dice to the carrier wafer before the final placement operation. The dice are pre-positioned and secured on the carrier wafer using adhesive, creating a ready-to-transfer assembly. This preliminary action allows the actual placement to be executed as a single batch operation, significantly reducing the time required compared to individual placement.
2Productivity
If wafer is cut into individual dice first, then picking and placing is performed, but manufacturing complexity increases
Solution Approach 1:
The patent combines the carrier wafer with multiple dice into a single integrated assembly for transfer. Rather than handling individual dice, the entire carrier wafer with attached dice is moved as one unit to the target substrate. This merging simplifies the handling process and reduces the number of separate operations required, directly addressing the manufacturing complexity issue.
Solution Approach 2:
The carrier wafer serves as an intermediary component that facilitates batch transfer of multiple dice. It acts as a temporary holding and transport platform, enabling the group transfer of dice without requiring complex individual manipulation. This intermediary approach simplifies the overall process by providing a straightforward mechanism for batch handling.
3Strength
If thermoset adhesive is heated to adhere dice, then bonding strength is achieved, but processing time is extended
Solution Approach 1:
The patent merges the adhesive application and heating operations into a single batch process. Instead of applying and heating adhesive for each die individually, all dice on the carrier wafer receive adhesive and are heated simultaneously. This combined operation maintains the required bonding strength while dramatically reducing the total processing time compared to sequential operations.
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
This method significantly increases the number of units per hour (UPH) and reduces the time required for the stacking process by enabling batch processing of dice placement, thereby enhancing the efficiency of the die placement cycle.
Implementation Method 1
the photosensitive adhesive tape is selectively exposed to form an adhesion-released portion
Data Source
AI summary
A method for wafer level stack die placement is disclosed. At first, a wafer including a plurality of dice is provided. The wafer is adhered to a photosensitive adhesive tape. The wafer is attached on a die carrier to fix at least one die from the wafer on the die carrier. The die carrier may be another wafer. The photosensitive adhesive tape is selectively exposed to form an adhesion-released portion. The adhesion-released portion is aligned with the fixed die. Then, the photosensitive adhesive tape and the die carrier with the fixed die are apart. Therefore the stack die placement in the die-attaching batch is quick and efficient.