FinFET Trench Formation via Dual Etching and Passivation
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Solution Overview
Problem
Current FinFET fabrication methods face challenges in forming shallow trench isolation (STI) between fin-shaped structures, which affects the gate structure formation and current performance due to expansion issues.
Innovation Solution
A method involving two etching processes is employed to divide fin-shaped structures into portions, forming trenches and ensuring precise control over the trench depth and width, using a first etching process to create an initial trench and a second etching process to extend it, while utilizing a passivation layer to protect critical areas during the second etching step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single etching process is used to form trenches between fin-shaped structures, then the process is simple and fast, but the trench depth and width control is poor, affecting gate structure formation
Solution Approach 1:
The single etching process is divided into two sequential etching processes. The first etching process forms an initial trench with controlled depth, and the second etching process extends the trench to the final depth. This segmentation allows for better control of trench dimensions by optimizing each etching step independently, resolving the contradiction between precision and complexity.
Solution Approach 2:
The first etching process performs a preliminary action by forming an initial trench structure before the second etching process extends it. This preliminary trench formation allows for better control of the final trench dimensions, as the second etching can be precisely controlled to achieve the target depth and width, thereby improving manufacturing precision.
2Reliability
If shallow trench isolation is formed between fin-shaped structures, then isolation is achieved, but expansion occurs that affects gate structure formation
Solution Approach 1:
The trench formation is segmented into two etching steps with a passivation layer deposited between them. This segmentation prevents expansion issues by controlling the trench walls more effectively, ensuring that the isolation is achieved without compromising the precision of subsequent gate structure formation.
Solution Approach 2:
A passivation layer is introduced as an intermediary between the two etching processes. This passivation layer protects the trench walls from excessive etching and prevents expansion, thereby maintaining both effective isolation and precise gate structure formation without the harmful expansion effects.
3Reliability
If the trench depth is increased to improve isolation, then isolation effectiveness improves, but the critical dimensions of the device are affected
Solution Approach 1:
The trench formation is divided into two etching steps, allowing the total trench depth to be achieved while maintaining control over critical dimensions. The first etching step creates an initial trench, and the second step extends it to the required depth, with each step controlled to preserve critical dimensions.
Solution Approach 2:
The first etching process performs a preliminary action by forming an initial trench structure that establishes the trench width and position. The second etching process then extends the depth without significantly affecting the critical dimensions, thereby achieving both effective isolation and precise critical dimension control.
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
This approach enhances the control over the trench formation, allowing for improved gate structure deposition and maintaining the critical dimensions of the device, thereby addressing the expansion issues and enhancing the overall performance of FinFETs.
Implementation Method 1
performing a first etching process to remove part of the fin-shaped structure for forming a trench
Implementation Method 2
performing a second etching process to extend the depth of the trench and divide the fin-shaped structure into a first portion and a second portion
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of: providing a substrate; forming a fin-shaped structure on the substrate; performing a first etching process to remove part of the fin-shaped structure for forming a trench; and performing a second etching process to extend the depth of the trench and divide the fin-shaped structure into a first portion and a second portion.