Selective Etching via Deposition and Adsorption Films
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Solution Overview
Problem
Current plasma etching methods face challenges in selectively etching one region of a substrate over another, particularly in reducing the etching rate of certain materials, which affects the selectivity and efficiency of the process.
Innovation Solution
A method involving the formation of a deposition film on a substrate using plasma from a first gas, followed by an adsorption film from a gaseous precursor, and then selectively etching the first region using ions from a second gas, while the adsorption film reduces the etching rate of the second region, enhancing selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is performed using a mixture gas of CH3F and O2 to selectively etch silicon nitride over silicon oxide, then the etching selectivity is improved, but the etching rate of the silicon oxide region cannot be sufficiently reduced
Solution Approach 1:
The etching process is divided into multiple sequential steps with different gas compositions and parameters. The first step uses CF4-based plasma to etch silicon nitride, followed by a second step using CH3F/O2 plasma to etch silicon oxide. This segmentation allows each step to be optimized for its specific target material, achieving both high selectivity and controlled etching rates for different regions.
Solution Approach 2:
The patent employs periodic alternation between different plasma conditions - switching between CF4-based plasma and CH3F/O2 plasma in sequential cycles. Each plasma type is applied periodically to target different materials, with parameters such as gas flow rates, pressure, and power adjusted in each cycle to achieve the desired etching selectivity and rate control.
2Manufacturing precision
If the etching rate of the second region is reduced to enhance selectivity, then the manufacturing precision is improved, but the overall etching efficiency decreases
Solution Approach 1:
The total etching process is segmented into multiple specialized steps, each optimized for specific materials. By dividing the process into CF4-based etching for silicon nitride and CH3F/O2-based etching for silicon oxide, the patent achieves high selectivity without requiring excessive process time, as each segment targets its intended material efficiently.
Solution Approach 2:
The patent utilizes parameter changes between different plasma steps - adjusting gas composition, pressure, and power levels - to optimize etching rates for different materials. This allows rapid etching of silicon nitride in the first step while controlling silicon oxide etching in subsequent steps, reducing overall process time while maintaining high selectivity.
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 effectively promotes the etching reaction between the chemical species in the deposition film and the first region's material, while minimizing the etching of the second region, thereby enhancing the selectivity and efficiency of the etching process.
Implementation Method 1
plasma is generated from a processing gas in the chamber
Implementation Method 2
forming a deposition film on the substrate formed from a chemical species included in plasma
Implementation Method 3
supplying a gaseous precursor to the substrate having the deposition film formed thereon, thereby forming an adsorption film on the substrate from the precursor
Implementation Method 4
supplying ions from plasma generated from a second gas to the substrate
Implementation Method 5
cause a reaction between the material of the first region and a chemical species included in the deposition film
Implementation Method 6
reducing an etching rate of the second region by the adsorption film
Data Source
AI summary
A method of etching selectively etches a first region of a substrate with respect to a second region of the substrate formed of a different material from the first region. A deposition film is formed of a chemical species included in plasma generated from a first gas. A gaseous precursor is supplied to the substrate having the deposition film formed thereon to form an adsorption film on the substrate from the precursor. Ions from plasma generated from a second gas are supplied to the substrate having the deposition film and the adsorption film formed thereon so as to cause a reaction between the material of the first region and a chemical species included in the deposition film, so that the first region is etched. The adsorption film reduces the etching rate of the second region during the etching of the first region.