Interposer Bump Removal for SSIT Reliability
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Solution Overview
Problem
In stacked silicon interconnect technology (SSIT) devices, incomplete and defective interposer dies with formed bumps can cause shorts and reliability issues due to dislodged bumps trapped between bumps on populated semiconductor dies, leading to additional processing complexity and costs.
Innovation Solution
A method for removing bumps from incomplete and defective interposer dies on an interposer wafer, involving forming bumps, identifying and protecting good dies, etching and stripping photoresist layers to isolate and remove bumps from incomplete and defective dies, and reflow joining and cleaning the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bumps are formed on the entirety of the interposer wafer including incomplete and defective dies, then bump uniformity and optimal bump density are achieved, but dislodged bumps from incomplete/defective dies cause shorts and reliability problems
Solution Approach 1:
The patent applies preliminary action by forming bumps on all interposer dies (including incomplete and defective ones) during the initial fabrication process to ensure uniformity and optimal density. Later, a selective removal process is performed to eliminate bumps only from incomplete/defective dies before population, thus preventing shorts while maintaining the benefits of uniform bump formation across the entire wafer.
Solution Approach 2:
The patent applies local quality by making the bump presence/absence property location-specific. After initial uniform bump formation, the process selectively removes bumps from specific locations (incomplete and defective dies) while preserving bumps on good dies. This creates a non-uniform final distribution where bump presence is tailored to the quality of each specific die location.
2Reliability
If bumps are removed from incomplete and defective interposer dies, then shorts and reliability problems are prevented, but additional processing steps are required
Solution Approach 1:
The patent performs bump removal as a preliminary action before the population process. By removing bumps from incomplete and defective dies beforehand, the subsequent population process can proceed without risk of shorts caused by dislodged bumps. This sequencing simplifies the overall process by preventing defects early rather than requiring complex detection and correction later.
Solution Approach 2:
The patent applies the extraction principle by selectively removing (taking out) bumps from incomplete and defective interposer dies. This extraction isolates the problematic bumps that would otherwise cause shorts, separating them from the functional bumps on good dies. The removal process uses photoresist masking and etching to precisely extract only the necessary bumps while leaving the rest intact.
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
Prevents dislodged bumps from causing shorts and reliability problems, simplifying the assembly process and reducing costs by ensuring only good interposer dies are populated with semiconductor dies.
Implementation Method 1
forming a second photoresist layer to protect bumps corresponding to interposer dies of the interposer wafer that are to be populated with semiconductor dies
Implementation Method 2
etching bumps corresponding to the identified at least one incomplete interposer die and/or at least one defective interposer die
Implementation Method 3
performing reflow joining on the interposer wafer
Data Source
AI summary
A method for removing bumps from incomplete interposer die(s) and/or defective interposer die(s) of an interposer wafer is described. The method includes forming bumps on an interposer wafer; identifying at least one incomplete interposer die and/or at least one defective interposer die of the interposer wafer; and removing bumps from the at least one incomplete interposer die and/or the at least one defective interposer die of the interposer wafer.