Element Chip Sidewall Smoothing via Plasma Post-Processing
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Solution Overview
Problem
The plasma dicing method using the Bosch process results in element chips with rugged sidewalls due to isotropic etching, leading to increased leakage current and deterioration of device characteristics, and shortening etching time does not sufficiently reduce ruggedness while compromising productivity.
Innovation Solution
A three-step post-processing method involving sidewall cleaning, oxidation, and etching using plasma, while maintaining a resin film on the element chips, to reduce the ruggedness of the sidewalls by removing deposits, forming an oxide layer, and preferentially etching the peaks of scallops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the Bosch process is used for plasma dicing, then high aspect ratio grooves can be formed, but the sidewall becomes rugged with scallops leading to increased leakage current
Solution Approach 1:
The patent applies parameter changes by modifying the etching conditions (isotropic to anisotropic transition) and performing post-etching smoothing treatment to reduce scallop depth. This changes the physical parameters of the groove formation process to achieve both high aspect ratio and smooth sidewalls, thereby resolving the contradiction between manufacturing precision and reliability.
2Manufacturing precision
If etching time is shortened to reduce ruggedness, then sidewall smoothness improves, but etching amount per operation decreases requiring more cycles and reducing productivity
Solution Approach 1:
The patent applies preliminary action by performing a smoothing treatment after the main etching process. This preliminary smoothing step removes the ruggedness without requiring multiple etching cycles, thus maintaining productivity while achieving the desired sidewall smoothness.
3Manufacturing precision
If the non-Bosch process is used for plasma dicing, then the sidewall becomes smooth, but side-etching occurs especially in thick substrates
Solution Approach 1:
The patent applies parameter changes by transitioning from isotropic etching to anisotropic etching through parameter adjustment, and further optimizing the etching profile through post-etching smoothing. This allows achieving smooth sidewalls without the side-etching problems of the non-Bosch process, thereby improving ease of manufacture while maintaining manufacturing precision.
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
The method effectively reduces the ruggedness of the sidewalls, improving the characteristics of element chips by minimizing leakage current and maintaining productivity.
Implementation Method 1
a sidewall cleaning step of exposing the element chip to a first plasma, to remove deposits adhering to the sidewall
Implementation Method 2
a sidewall oxidation step of exposing the element chip to a second plasma, after the sidewall cleaning step, to oxidize a surface of the sidewall
Implementation Method 3
a sidewall etching step of exposing the element chip to a third plasma, after the sidewall oxidation step, to etch the sidewall
Data Source
AI summary
An element chip smoothing method including: an element chip preparation step of preparing at least one element chip including a first surface covered with a resin film, a second surface opposite the first surface, and a sidewall connecting the first surface to the second surface and having ruggedness; a sidewall cleaning step of exposing the element chip to a first plasma, to remove deposits adhering to the sidewall, with the resin film allowed to continue to exist; a sidewall oxidation step of exposing the element chip to a second plasma, after the sidewall cleaning step, to oxidize a surface of the sidewall, with the resin film allowed to continue to exist; and a sidewall etching step of exposing the element chip to a third plasma, after the sidewall oxidation step, to etch the sidewall, with the resin film allowed to continue to exist.