Cyclical Etching Process for Oxide Layer Profile Control
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Solution Overview
Problem
Current etching processes for semiconductor devices face challenges in achieving high selectivity and accurate profile control, particularly for sub-half micron features, due to poor process control and non-uniform etch selectivity, leading to irregular structure profiles and line edge roughness.
Innovation Solution
A method combining a main etching process with a cyclical etching process using a treatment gas mixture, followed by a chemical etching process with a gas mixture containing ammonium and nitrogen trifluoride, and a transition process, to achieve high selectivity and accurate profile control for etching material layers on semiconductor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional etching process is used to etch material layers, then the etching speed is maintained, but the etch selectivity is poor and profile control is inaccurate
Solution Approach 1:
The etching process is divided into multiple distinct phases: a main etching process for rapid material removal, followed by a treatment process, then a chemical etching process with ammonium and nitrogen trifluoride for high selectivity and profile control, and finally a transition process. This segmentation allows each phase to optimize for its specific function, achieving both speed and precision without requiring a single complex process
Solution Approach 2:
The patent implements a cyclical etching process that alternates between different gas mixtures and process conditions. The periodic switching between the main etching phase, treatment phase, chemical etching phase, and transition phase creates a rhythm of aggressive etching followed by controlled refinement, enabling accurate profile control while maintaining overall etching efficiency
2Manufacturing precision
If the etching process is extended to improve selectivity and profile control, then the manufacturing precision is improved, but the processing time increases
Solution Approach 1:
By dividing the etching into specialized phases, the main etching process can operate at high speed for bulk material removal, while the subsequent chemical etching phase with ammonium and nitrogen trifluoride provides the necessary selectivity and profile control. This segmentation prevents the need to slow down the entire process to achieve precision, as only the critical phases are extended
Solution Approach 2:
The patent changes multiple parameters between phases: gas composition (from main etching gases to ammonium and nitrogen trifluoride mixture), temperature conditions, and pressure settings. These parameter changes enable the process to achieve high selectivity in the chemical etching phase without requiring a proportional increase in total processing time, as each phase operates at optimized conditions for its specific function
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 enables the formation of high aspect ratio features with improved etch selectivity and accurate profile control, reducing the likelihood of over-etching and maintaining high throughput, thus enhancing the manufacturing of next-generation semiconductor devices.
Implementation Method 1
performing a chemical etching process on the substrate by supplying a chemical etching gas mixture into the processing chamber, wherein the chemical etching gas includes at least an ammonium gas and a nitrogen trifluoride
Implementation Method 2
performing a treatment process on the substrate by supplying a treatment gas mixture into the processing chamber to treat the etched feature in the oxide layer
Data Source
AI summary
Methods for etching a material layer disposed on the substrate using a combination of a main etching step and a cyclical etching process are provided. The method includes performing a main etching process in a processing chamber to an oxide layer, forming a feature with a first predetermined depth in the oxide layer, performing a treatment process on the substrate by supplying a treatment gas mixture into the processing chamber to treat the etched feature in the oxide layer, performing a chemical etching process on the substrate by supplying a chemical etching gas mixture into the processing chamber, wherein the chemical etching gas includes at least an ammonium gas and a nitrogen trifluoride, wherein the chemical etching process further etches the feature to a second predetermined depth, and performing a transition process on the etched substrate by supplying a transition gas mixture into the processing chamber.