Insulation Film Etching Method for Semiconductor Underlayer Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional etching methods for semiconductor devices struggle to accurately etch insulation films without damaging the underlying layers, especially as underlayers become thinner with advancements in high integration and density, leading to issues with contamination and precision.
Innovation Solution
A method involving a three-step process: first, etching the insulation film with a fluorocarbon gas plasma until just before the underlayer is exposed; second, modifying the remaining film quality using a different plasma gas, such as O2 or H2; and third, removing the modified film using a liquid chemical or a chemical oxide removal process without plasma, ensuring precise removal of the insulation film without damaging the underlayer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is performed to etch the insulation film until the underlayer is exposed, then the insulation film is effectively removed, but the underlayer is damaged by reactive ion irradiation
Solution Approach 1:
The etching process is divided into two distinct stages: first, a dry etching process removes the insulation film until just before the underlayer is exposed; second, a wet etching process selectively removes the defective layer formed on the underlayer surface. This segmentation allows each process to be optimized independently, achieving complete insulation film removal while protecting the underlayer from damage.
Solution Approach 2:
A defective layer is intentionally formed on the underlayer surface during the dry etching process, which then serves as a sacrificial intermediary. This defective layer absorbs the harmful reactive ion irradiation, protecting the bulk underlayer material. The defective layer is subsequently removed by selective wet etching, leaving the underlayer intact.
2Object-affected harmful factors
If wet etching is used to remove the defective layer, then the defective layer is eliminated, but overetching occurs on the underlayer surface
Solution Approach 1:
The etching selectivity parameters are carefully controlled by adjusting the composition and concentration of the wet etching solution. By optimizing these parameters, the wet etching process selectively attacks the defective layer while exhibiting minimal etching rate on the intact underlayer material, thereby preventing overetching and maintaining fabrication accuracy.
Solution Approach 2:
The wet etching solution exhibits different etching rates on different regions of the underlayer surface. The defective layer regions are highly susceptible to wet etching due to their altered material properties, while the intact underlayer regions resist etching. This local quality difference enables selective removal of only the defective portions without damaging the surrounding underlayer structure.
3Productivity
If conventional etching methods are used, then the insulation film is etched, but contamination occurs on the underlayer surface
Solution Approach 1:
The reactive ions that would normally cause contamination and damage are utilized in a controlled manner during the first etching stage to form a localized defective layer. This defective layer then serves as a protective barrier during subsequent processing. The harmful reactive ion irradiation is thus converted into a beneficial sacrificial layer that prevents contamination of the bulk underlayer.
Solution Approach 2:
The process replaces direct mechanical/physical removal methods that cause contamination with a chemical approach. The wet etching solution chemically selectively removes the defective layer through dissolution, avoiding the mechanical sputtering and ion bombardment that cause contamination in conventional dry etching methods.
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 allows for high-accuracy etching of insulation films without damaging the underlayer, maintaining precision even as underlayers thin, and preventing contamination, thus supporting the trend towards higher semiconductor integration and density.
Implementation Method 1
a first process of etching the insulation film until just before an underlayer is about to be exposed by applying a first plasma of a first processing gas
Implementation Method 2
etching the insulation film with a fluorocarbon gas plasma
Implementation Method 3
a second process of modifying a quality of a remaining film of the insulation film by applying a second plasma of a second processing gas
Implementation Method 4
modifying the remaining film quality using a different plasma gas, such as O2 or H2
Implementation Method 5
removing the modified film using a liquid chemical or a chemical oxide removal process
Data Source
AI summary
A method for etching an insulation film through a patterned mask, includes the steps of etching the insulation film until just before an underlayer is about to be exposed by applying a plasma, and modifying a quality of a remaining film of the insulation film by applying another plasma which is different from the plasma used in the above etching process. The method further includes the process of removing the modified remaining film of the insulation film with a liquid chemical. The process of removing the modified remaining film can be also achieved by a dry etching method not employing a plasma.