Selective Fin Etching for Transistor Isolation at Tight Spacing
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Solution Overview
Problem
In advanced technology nodes, the shrinking dimensions of transistors lead to a reduction in spacing between source/drain portions, making it challenging to prevent source/drain merging without effective isolation structures.
Innovation Solution
A selective etching method is employed to manufacture semiconductor structures with relatively high fin sidewalls, which are crucial for isolation between adjacent transistors. This method involves forming fin sidewalls on isolation structures and using a protection layer to prevent damage during etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor dimensions are reduced to increase integration density, then the number of transistors per unit area increases, but the spacing between adjacent transistors decreases making isolation difficult
Solution Approach 1:
The patent segments the isolation process into multiple controlled etching stages with selective fin sidewall removal. By dividing the source/drain region into segments separated by fin sidewalls, and selectively removing material between them, the method achieves precise isolation even at reduced transistor spacing
Solution Approach 2:
The patent performs preliminary formation of fin sidewalls before the main isolation etching process. These fin sidewalls serve as protective structures that prevent unwanted etching during subsequent processing steps, enabling precise control of isolation regions before final pattern definition
2Reliability
If fin sidewalls are made taller to improve isolation effectiveness, then source/drain merging is prevented, but the etching process becomes more complex and time-consuming
Solution Approach 1:
The patent applies local quality by making fin sidewall height and removal selective to specific locations. Not all fin sidewalls are removed uniformly - instead, removal is selectively applied to specific regions based on local isolation requirements, allowing tailored isolation effectiveness without uniform process complexity
Solution Approach 2:
The patent employs partial action by removing only certain fin sidewalls rather than all fin sidewalls uniformly. This selective removal approach achieves sufficient isolation in critical regions while maintaining structure integrity elsewhere, reducing overall process complexity and time
3Ease of manufacture
If conventional etching is used without protection layers, then the process is simpler, but fin sidewalls are damaged during source/drain recess formation
Solution Approach 1:
The patent introduces protection layers as intermediary structures between the fin sidewalls and the etching process. These protection layers act as mediators that allow the etching process to proceed while preventing direct contact between the etchant and fin sidewalls, thus preserving fin sidewall integrity during source/drain recess formation
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 prevents source/drain merging by maintaining sufficient isolation between transistors, even at reduced dimensions, while also allowing for flexible control of fin sidewall height and reducing defects in the semiconductor devices.
Implementation Method 1
performing an etching process such that the exposed region of the semiconductor fin is etched away to form a recess while a protection layer is formed to protect each of the fin sidewalls during the etching process
Data Source
AI summary
A method for manufacturing a semiconductor structure includes forming a semiconductor portion which has an exposed region; forming two fin sidewalls which are disposed at two opposite sides of the exposed region of the semiconductor portion, and which include a dielectric material; and performing an etching process such that the exposed region of the semiconductor portion is etched away to form a recess while a protection layer is formed to protect each of the fin sidewalls during the etching process. Other methods for manufacturing the semiconductor structure are also disclosed.