Shallow Trench Isolation Recessing to Prevent STI Dishing
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the dishing effect in shallow trench isolations (STIs) due to differing etch rates of liner and insulating layers, leading to uneven STI thickness and potential damage to channel regions during ion implantation processes in gate-all-around (GAA) transistors.
Innovation Solution
Implementing an ion implantation process to introduce impurities into the insulating layer of STIs, altering the bonding structure and increasing etch resistance, thereby reducing the etch rate difference between liner and insulating layers and mitigating the dishing effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed to increase etch resistance of insulating layer, then etch rate difference between liner and insulating layers is reduced, but manufacturing process complexity increases
Solution Approach 1:
Ion implantation is performed on the insulating layer before the recessing step to pre-modify its etch resistance. This preliminary action ensures that during the subsequent recessing process, the insulating layer etches at a controlled rate matching the liner layer, thereby preventing dishing effect and achieving uniform STI thickness.
Solution Approach 2:
The etch resistance parameter of the insulating layer is changed by introducing impurities through ion implantation. This parameter modification alters the chemical composition and bonding structure of the insulating layer, making its etch rate comparable to that of the liner layer, thus resolving the dishing problem.
2Reliability
If ion implantation is performed to protect channel regions, then structural integrity is improved, but manufacturing time increases
Solution Approach 1:
Ion implantation is performed in advance before the recessing step to pre-protect the channel regions. By introducing impurities into the insulating layer beforehand, the channel regions are shielded from potential damage during the subsequent recessing process, ensuring structural integrity while maintaining process efficiency.
3Manufacturing precision
If ion implantation is used to reduce dishing effect, then STI quality is improved, but manufacturing cost increases
Solution Approach 1:
The etch resistance parameter of the insulating layer is modified through ion implantation to match that of the liner layer. This parameter change ensures that both layers recess at the same rate, eliminating the dishing effect and producing high-quality STI structures with uniform thickness and excellent planarity.
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 ion implantation process enhances the etch resistance of STIs, ensuring consistent thickness and protecting channel regions, improving the manufacturing process for GAA transistors by reducing the dishing effect and maintaining structural integrity.
Implementation Method 1
performing an ion implantation process to the insulating layer
Data Source
AI summary
A method of forming a semiconductor device includes etching trenches in a substrate to form fin structures, depositing a liner layer to line the trenches, filling the trenches with an insulating layer, performing an ion implantation process to the insulating layer, after performing the ion implantation process, recessing the insulating layer to form shallow trench isolation (STI) regions adjacent the fin structures, and forming a gate crossing the fin structures.