Backside Isolation Regions for Uniform Gate-All-Around IC Fabrication
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Solution Overview
Problem
Current methods for forming isolation regions between semiconductor devices in ICs cause within-die variations, leading to yield issues and performance deterioration due to non-uniform semiconductor structures and gate etch out, particularly when cutting semiconductor structures before gate formation.
Innovation Solution
Forming backside isolation regions by removing semiconductor regions between gates from the backside of the IC device, which avoids non-uniform semiconductor structures and reduces within-die variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If semiconductor structures are cut in isolation regions before gate formation, then isolation regions can be formed between devices, but non-uniform semiconductor structures and gate etch out occur leading to within-die variations
Solution Approach 1:
The patent inverts the conventional sequence by forming isolation regions after gate formation rather than before. Specifically, gates are formed across continuous semiconductor structures first, then isolation regions are created by removing semiconductor material in non-functional areas after the gates are in place. This reversal eliminates gate etch out issues and non-uniform semiconductor structures that plague the conventional approach, as the gates are already formed and protected when isolation regions are subsequently defined.
Solution Approach 2:
The patent applies preliminary action by forming gates across the entire wafer including potential isolation regions before creating the isolation structures themselves. This ensures that gate patterns are established on uniform semiconductor structures first, and then isolation regions are defined afterward by selective removal of semiconductor material. The preliminary gate formation prevents within-die variations because all gates experience the same formation conditions on uniform substrate before any isolation structures are introduced.
2Ease of manufacture
If conventional isolation region formation methods are used, then isolation between devices is achieved, but yield issues and performance deterioration occur due to within-die variations
Solution Approach 1:
By inverting the process sequence to form gates before isolation regions, the patent eliminates the harmful effects of gate etch out and non-uniform semiconductor structures that currently reduce yield. The conventional approach cuts semiconductor structures before gate formation, causing within-die variations that deteriorate device performance. The inverted approach forms gates on uniform structures first, then creates isolation regions afterward, thereby maintaining high yield while still achieving proper device isolation.
3Device complexity
If semiconductor structures are cut before gate formation, then isolation regions can be defined, but non-uniform semiconductor structures result affecting downstream processes
Solution Approach 1:
The patent resolves the uniformity issue by inverting the process sequence: gates are formed first on continuous, uniform semiconductor structures across the entire wafer, then isolation regions are created by selective removal of semiconductor material afterward. This ensures that all semiconductor structures maintain uniformity during the critical gate formation step, and subsequent isolation region definition does not compromise this uniformity since the gates are already in place and the semiconductor structures are not cut before gating.
Data Source
AI summary
An IC device may have active regions and one or more isolation regions. The IC device includes gates that are in parallel. One or more semiconductor structures (e.g., fins, nanoribbons, etc.) may extend across each gate in the IC device. Some of the gates are in the active regions. The other gates are in the isolation region. A gate in an active region may be between semiconductor regions, which may function as the source region and drain region of a transistor. A gate in an isolation region may be between insulator regions. The insulator regions may be formed from the backside of the IC device. For instance, semiconductor regions may be formed in both the active regions and the isolation regions. The semiconductor regions in the regions designated to be isolation regions may be removed from the backside and filled with one or more electrical insulators.