Protection Layer for Wafer Passivation During Plasma Etching
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Solution Overview
Problem
Conventional plasma etch processes for semiconductor wafers often damage the passivation layer, leading to reliability issues such as delamination due to the erosion of the surface during the removal of the etch mask, which affects the adhesion of chip packaging material.
Innovation Solution
A method involving the formation of a protection layer and a mask layer over the passivation layer, where the protection layer is selectively etchable relative to the passivation and the mask layer is selectively etchable relative to the protection layer, allowing for precise removal of these layers without damaging the passivation, thereby preventing surface erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is used to process the wafer front side, then etching capability is improved, but the passivation layer surface is damaged leading to delamination
Solution Approach 1:
A protection layer is introduced as an intermediary between the mask layer and the passivation layer. This protection layer absorbs the damage from plasma etching and mask removal processes, preventing direct contact between these harsh processes and the passivation layer surface, thereby maintaining passivation integrity while enabling effective wafer etching
Solution Approach 2:
The protection layer is formed on the passivation layer before any etching or mask removal operations. This preliminary protective measure ensures that the passivation layer is already shielded when subsequent plasma etching and mask stripping processes occur, preventing surface erosion before it can happen
2Reliability
If a protection layer is added to protect the passivation, then passivation integrity is improved, but process complexity increases
Solution Approach 1:
The protection layer is designed with specific material properties and thickness parameters that enable selective etching. By carefully controlling the etch selectivity between the protection layer, mask layer, and passivation layer, the process achieves automatic layer-by-layer removal without requiring complex additional process steps, thus limiting the increase in process complexity
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 approach prevents or significantly reduces damage to the passivation layer, maintaining its integrity and enhancing the reliability of chip packaging by ensuring a damage-free surface for packaging and field performance.
Implementation Method 1
the protection layer includes a material that is selectively etchable to a material of the passivation; forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer includes a material that is selectively etchable to the material of the protection layer
Implementation Method 2
Processing a wafer may sometimes include etching, for example plasma etching, a side of the wafer where the semiconductor is processed
Data Source
AI summary
A method for processing a wafer in accordance with various embodiments may include: forming a passivation over the wafer; forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer includes a material that is selectively etchable to a material of the passivation; forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer includes a material that is selectively etchable to the material of the protection layer; etching the wafer using the mask layer as a mask; selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; and selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer.