Cryogenic Plasma Etching for Tapered Apertures Without Mask Clogging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plasma etching methods face challenges in achieving fine linewidths and contact hole patterns due to deposition of process gases, which can occlude mask pattern apertures, leading to incomplete or irregular etching of target films.
Innovation Solution
A substrate processing apparatus and method involving a plasma generator, controller, and specific gas mixtures (e.g., CF4 and H2) to etch silicon-containing films, controlling substrate temperature to −30° C. or less, forming tapered apertures in silicon-containing antireflection films and subsequently etching silicon oxide films, preventing aperture occlusion and achieving precise etching profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching is performed using a process gas having a precursor causing deposition easily, then etching speed is improved, but deposits adhere to the upper portion of the mask pattern and occlude apertures
Solution Approach 1:
The patent changes the physical state parameters by cooling the substrate to −30° C. or less during etching. This temperature parameter change modifies the deposition behavior of process gas precursors, allowing high etching speed while preventing aperture occlusion by controlling where deposits form (on sidewalls rather than on mask apertures)
Solution Approach 2:
The patent converts the harmful deposition effect into a beneficial one by using the deposited material to form a tapered profile on the sidewalls of the etched aperture. The deposition that would normally occlude apertures is instead directed to create the desired tapered shape, improving etching performance while maintaining aperture openness
2Manufacturing precision
If etching is performed to achieve fine linewidths, then manufacturing precision is improved, but deposits may occlude mask pattern apertures leading to incomplete etching
Solution Approach 1:
The patent applies parameter change by controlling substrate temperature at −30° C. or less during the etching process. This enables precise linewidth control through tapered aperture formation while preventing aperture occlusion that would cause incomplete etching, thus maintaining both manufacturing precision and etching completeness
3Manufacturing precision
If substrate temperature is reduced to −30° C. or less, then aperture occlusion is prevented and tapered profiles are formed, but additional cooling equipment and energy are required
Solution Approach 1:
The patent implements parameter change by setting substrate temperature to −30° C. or less, which directly achieves tapered aperture formation and prevents aperture occlusion. The cooling system, while adding some complexity, provides a straightforward mechanism to control the temperature parameter that yields significant improvements in aperture profile control and etching reliability
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
The method effectively shrinks critical dimensions, prevents aperture occlusion, and maintains etching profile verticality, enabling the formation of small, regularly arranged contact holes in silicon oxide films without clogging, thus enhancing the precision and efficiency of wafer processing.
Implementation Method 1
a plasma generator configured to form a plasma in the chamber
Implementation Method 2
etching the first film through the second aperture with a plasma formed from a first process gas containing a fluorocarbon gas
Implementation Method 3
cooling the substrate to −30° C. or less
Data Source
AI summary
A substrate processing apparatus includes: a chamber; a substrate support disposed in the chamber; a plasma generator configured to form a plasma in the chamber; and a controller configured to perform a process including: placing a substrate on the substrate support, the substrate including a first film, a second film and a third film, the first film containing a silicon, the second film having a second aperture, the first film being disposed between the second film and the third film; cooling the substrate to −30° C. or less; etching the first film through the second aperture with a plasma formed from a first process gas containing a fluorocarbon gas, to form a first aperture of a tapered shape in the first film such that a width of the first aperture gradually decreases toward a bottom of the first aperture; and etching the third film through the first aperture.