Workpiece Etching via Mixed Gas Plasma Denaturation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the SAC process for manufacturing electronic devices, such as fin-type field effect transistors, the etching of the oxide region using fluorocarbon gas results in residue formation at the bottom of holes, which narrows the hole width and prevents sufficient etching of the nitride region, leading to excessive etching of the nitride regions covering the raised regions.
Innovation Solution
A method involving two steps: forming an opening in the oxide region to expose the nitride region between raised regions, and then etching the residue and nitride region using a mixed gas plasma containing hydrogen and NF3 to denature and remove the silicon oxide and nitride sections, reducing the cutting of the nitride regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorocarbon gas plasma is used to etch the oxide region, then the oxide region can be effectively etched, but residue is formed at the bottom of holes which narrows hole width and prevents sufficient etching of the nitride region
Solution Approach 1:
The etching process is divided into multiple sequential steps using different plasma gases: first fluorocarbon gas for oxide etching, then hydrogen-containing gas for residue removal, and finally NF3 gas for nitride region etching. This segmentation allows each step to optimize for its specific function without the adverse effects of using a single gas for all etching operations.
Solution Approach 2:
The patent changes the chemical composition parameters of the plasma gas between etching steps. By switching from fluorocarbon gas to hydrogen-containing gas and then to NF3 gas, the chemical reactivity and etching characteristics are adjusted to achieve complete removal of oxide, residue, and nitride layers with precise control over hole dimensions.
2Productivity
If fluorocarbon gas plasma is used for etching, then etching can proceed, but excessive etching of the nitride regions covering the raised regions occurs
Solution Approach 1:
The etching process is divided into multiple sequential steps using different plasma gases: first fluorocarbon gas for oxide etching, then hydrogen-containing gas for residue removal, and finally NF3 gas for nitride region etching. This segmentation allows each step to optimize for its specific function without the adverse effects of using a single gas for all etching operations.
Solution Approach 2:
Different plasma gases are applied at different stages to achieve different etching qualities: fluorocarbon gas provides aggressive etching for oxide removal, while NF3 gas provides selective etching for the nitride region with better control over the etching front, preventing excessive lateral etching of the nitride regions covering the raised regions.
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 method effectively removes the residue and nitride sections while minimizing the etching of the nitride regions covering the raised regions, allowing for deeper hole formation and improved processing precision.
Implementation Method 1
a denatured region is formed by exposing the workpiece to plasma of a mixed gas including a hydrogen-containing gas and NF3 gas to denature the residue and the second section
Data Source
AI summary
Disclosed is a method of processing a workpiece so as to form an opening that extends from an oxide region to a base layer through a portion between the raised regions. The method includes: (1) a step of forming an opening in the oxide region to expose a second section between the raised regions; and (2) a step of etching a residue made of silicon oxide and existing within the opening and a second section. In the second step, a denatured region is formed by exposing the workpiece to plasma of a mixed gas including a hydrogen-containing gas and NF3 gas to denature the residue and the second section, and the denatured region is removed.