Die-Level Stacking via Temporary Adhesive Release
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Solution Overview
Problem
Conventional wafer-level die stacking processes are costly and risky due to the need for new tooling and the handling of fully processed wafers with multiple die, which can result in breakage and increased costs.
Innovation Solution
A die-level die stacking process is implemented, where individual die are processed into stacks using existing manufacturing tools and temporary substrates, allowing only known good die to be processed, and temporary components are used for affixing and supporting the die stacks before being removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer-level die stacking process is used, then die stacks can be formed with multiple die interconnected, but processing costs increase and risk of breakage increases
Solution Approach 1:
The patent segments the wafer-level process into individual die-level operations. Instead of handling entire wafers with multiple stacked die, the process treats each die individually after dicing, allowing standard tools to handle single die or small groups rather than complex wafer-level assemblies. This segmentation reduces the complexity and cost of handling tools while maintaining the ability to form interconnected die stacks.
Solution Approach 2:
The patent performs dicing and initial die preparation before the stacking process. By pre-dicing the wafer into individual die and preparing them in advance, the system can use standard, lower-cost tools for the actual stacking operation rather than requiring expensive new tooling designed specifically for wafer-level processing with multiple stacked die.
2Productivity
If new tooling is developed to handle wafers with stacked die, then die stacking can be performed, but device complexity and cost increase
Solution Approach 1:
Instead of developing new tooling to handle wafers with multiple stacked die (the conventional approach), the patent inverts the approach by using standard, existing tools to handle individual die or small groups after dicing. This reversal eliminates the need for complex new tooling while achieving the same die stacking capability through a different process sequence.
Solution Approach 2:
The patent extracts the complexity from the handling tooling by separating the dicing step from the stacking step. By dicing the wafer first and then handling individual die with standard tools, the system removes the requirement for complex integrated tooling that would need to simultaneously manage entire wafers with multiple stacked die.
3Reliability
If fully processed wafers have additional die bonded thereto, then die stacks are formed, but scrap increases due to bad die
Solution Approach 1:
The patent performs testing and selection of good die before the stacking process. By pre-identifying and selecting only functional die through wafer-level or die-level testing prior to dicing and stacking, the system ensures that only known good die are processed into stacks, eliminating the risk of incorporating defective die and reducing scrap from bad die.
Data Source
AI summary
Apparatuses and methods for forming die stacks are disclosed herein. An example method includes dispensing a temporary adhesive onto a substrate, placing a base die onto the temporary adhesive, curing the temporary adhesive, forming a die stack that includes the base die, activating a release layer disposed on the substrate, wherein the release layer is between the substrate and the temporary adhesive, removing the die stack from the substrate, and removing the temporary adhesive from the die stack.