SOG Etch via Trench Resist Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor etching processes, particularly for multi-layer semiconductor devices with a Spin On Glass (SOG) layer, the thick SOG layer over via patterns cannot be fully removed during the main dielectric etch step, leading to undercut and pattern floating issues, which are challenging to address with conventional methods without causing ULK damage or microloading.
Innovation Solution
A trench resist layer is patterned with a trench reticle to open a via pattern similar to the large via feature, allowing for the complete removal of thick SOG during the SOG etch step, followed by thorough removal of remaining SOG and UL material during the ULK etch, preventing pattern lifting and ensuring clean via formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etch recipes are used to remove thick SOG over dipping UL, then SOG removal is incomplete, but increasing etch aggressiveness causes ULK damage and microloading
Solution Approach 1:
The patent segments the via pattern into two types: original large via patterns and newly formed smaller via patterns. This segmentation allows differential etching where the smaller patterns provide etch access without requiring complete SOG removal from the large patterns, thereby preventing ULK damage while still achieving adequate SOG thinning through the combined effect of multiple pattern types
Solution Approach 2:
The patent performs preliminary patterning to create additional smaller via patterns before the main etch process. These pre-formed patterns serve as etch entry points that facilitate SOG removal from beneath the large via patterns during subsequent etching steps, enabling complete SOG removal without requiring excessively aggressive etch conditions that would damage the ULK layer
2Productivity
If main dielectric etch step is used, then through etching is achieved, but thick SOG over dipping UL cannot be fully removed
Solution Approach 1:
The patent divides the via pattern into multiple size categories, creating a hierarchy where smaller via patterns etch through faster and create channels that facilitate SOG removal from larger patterns. This segmented approach maintains high productivity through aggressive etching of small patterns while achieving complete SOG removal from large patterns through the combined effect of all pattern types
Solution Approach 2:
The smaller via patterns act as intermediary structures that mediate between the high-speed through-etching process and the complete SOG removal requirement. These intermediary patterns create etch pathways and reduce SOG thickness in critical areas, enabling the main dielectric etch to proceed effectively while ensuring complete SOG removal without compromising productivity
Data Source
AI summary
A system and method of preventing pattern lifting during a trench etch/clean process is disclosed. A first layer comprising a first dip is formed over a first via pattern. A trench resist layer is formed. The trench resist layer is patterned with a trench reticle to produce a second via pattern in the trench resist layer over the first via pattern. A photo resist over the first via pattern is opened during a trench processing. Thus, an additional pattern added on a trench pattern reticle is used to open, i.e., remove resist over, a huge via feature area causing under layer dip.