Half-Pitch Patterning with Tin Middle Layer and Silicon Spacer Mask
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Solution Overview
Problem
The sidewall spacer method using an organic resist underlayer film and a silicon-containing middle layer film faces challenges in efficiently removing the silicon-containing middle layer film without damaging the substrate, leading to unsatisfactory performance and yield decrease due to the complexity and risk of pattern collapse in finer pattern formation.
Innovation Solution
A patterning process involving the formation of a tin-containing middle layer film and an organic underlayer film, where the tin-containing middle layer film is used as a mask to transfer patterns to the organic underlayer film, and subsequently, an inorganic silicon-containing film is formed to cover and expose the organic underlayer film pattern, allowing for the removal of both films by dry-etching without damaging the substrate or the inorganic silicon-containing film, thereby forming a pattern with a pitch half that of the original resist pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon-containing middle layer film is used in the sidewall spacer method, then pattern transfer accuracy is improved, but substrate damage occurs due to difficulty in removing the silicon-containing film
Solution Approach 1:
An organic underlayer film is introduced as an intermediary between the substrate and the silicon-containing middle layer film. This organic film serves as a sacrificial layer that can be selectively removed by oxygen plasma, allowing the silicon-containing film to be detached from the substrate without direct plasma exposure that would cause damage. The organic film mediates the removal process, protecting the substrate while enabling pattern transfer.
Solution Approach 2:
The invention changes the material composition parameter of the middle layer from pure silicon-containing material to a bilayer structure with distinct etch selectivity. The organic underlayer film has different chemical composition and etching characteristics compared to the silicon-containing film, enabling selective removal. By changing material parameters (composition, etch selectivity), the process achieves both accurate pattern transfer and substrate protection.
2Manufacturing precision
If the sidewall spacer method is used for finer pattern formation, then pattern pitch is reduced to half, but pattern collapse risk increases
Solution Approach 1:
The organic underlayer film serves as a cushioning or support structure during the pattern formation process. It provides mechanical support to the sidewall spacers during formation and subsequent processing steps, preventing collapse before the final pattern is achieved. The sacrificial nature of this layer allows it to be removed afterward, having fulfilled its supportive function.
Solution Approach 2:
The organic underlayer film acts as a mediator that enables the formation of ultra-fine patterns by providing a stable foundation during sidewall spacer formation. It allows the process to proceed to half-pitch patterns without collapse, then is removed to leave the final pattern. The intermediary layer makes the unreliable process of fine pattern formation stable and controllable.
3Manufacturing precision
If complex multi-step processes are used for pattern formation, then pattern resolution is improved, but productivity decreases
Solution Approach 1:
The invention merges multiple functions into a unified process flow: the organic underlayer film simultaneously serves as etch stop layer, sacrificial layer, and mechanical support. The sidewall spacer formation process combines pattern transfer and pattern multiplication (half-pitch) in one sequence. By merging these functions, the process achieves high resolution without proportionally increasing step count, thereby maintaining productivity.
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 process enables the efficient and smooth formation of a finer pattern with high smoothness and accuracy, avoiding substrate damage and yield decrease, and effectively forms an inorganic silicon-containing film pattern with a pitch half that of the original resist pattern, enhancing the productivity and quality of the patterning process.
Implementation Method 1
dry-etching the tin-containing middle layer film while using the upper layer resist pattern as a mask to transfer the upper layer resist pattern to the tin-containing middle layer film
Implementation Method 2
removing the portion of the tin-containing middle layer film left on the upper portion of the organic underlayer film pattern by dry-etching
Implementation Method 3
forming an inorganic silicon-containing film comprising polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or a composite material thereof, by a CVD method or an ALD method
Implementation Method 4
forming an inorganic silicon-containing film comprising polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or a composite material thereof, by a CVD method or an ALD method
Implementation Method 5
removing the organic underlayer film pattern to form an inorganic silicon-containing film pattern with a pattern pitch that is 1/2 of a pattern pitch of the upper layer resist pattern
Data Source
Figure 1(A)~1(J)
Figure 2(A)~2(J)
AI summary
A patterning process capable of readily and efficiently forming a fine pattern without damaging a substrate is provided. The patterning process includes: forming an organic underlayer film, a tin-containing middle layer film, and an upper layer resist film on a substrate to be processed; forming an upper layer resist pattern; transferring the upper layer resist pattern to the tin-containing middle layer film, and forming an organic underlayer film pattern on an upper portion of which a portion of the tin-containing middle layer film is left; removing the portion of the tin-containing middle layer film by dry-etching; forming an inorganic silicon-containing film so as to cover the organic underlayer film pattern; exposing the upper portion of the organic underlayer film pattern; removing the organic underlayer film pattern to form an inorganic silicon-containing film pattern with a pattern pitch that is 1/2 of that of the upper layer resist pattern; and processing the substrate to be processed while using the inorganic silicon-containing film pattern as a mask to form a pattern in the substrate to be processed.