Etching Method for Poly Silicon Mask Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The spacer double patterning method forms masks with slanted tips, requiring higher selectivity to prevent tip removal, but enhancing selectivity leads to mask closure due to reaction product deposition, creating a trade-off.
Innovation Solution
An etching method involving intermittent high-frequency power supply and a gas mixture of hydrogen bromide (HBr) and oxygen (O2) is used to improve mask selectivity and prevent mask closure by controlling plasma conditions and gas ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gas with depositing property is supplied to improve mask selectivity, then mask selectivity is improved, but reaction product deposits on the side walls of the mask causing mask closure
Solution Approach 1:
The patent applies periodic action by intermittently supplying high-frequency power to the plasma generation electrode in a pulsed manner. This creates alternating etching periods (when plasma is active) and deposition periods (when plasma is inactive, allowing reaction products to be removed). This periodic control resolves the contradiction by preventing continuous deposition that would cause mask closure while maintaining sufficient etching rate for selectivity.
Solution Approach 2:
The patent changes physical parameters by controlling the duty cycle, pulse width, and power level of the intermittent high-frequency supply. By adjusting these parameters, the etching rate and deposition rate are independently controlled, allowing optimization of mask selectivity while preventing mask closure through parameter optimization rather than gas composition changes alone.
2Manufacturing precision
If the mask selectivity is improved by supplying a gas with depositing property, then the selectivity is enhanced, but the reaction product deposits on the side walls causing block of opening
Solution Approach 1:
Intermittent high-frequency power supply creates periodic etching and cleaning cycles, preventing reaction product accumulation that would block mask openings while maintaining etching selectivity during active plasma periods.
Solution Approach 2:
The patent maintains continuous process control by alternating between etching action (plasma on) and cleaning action (plasma off), ensuring both etching selectivity and mask opening integrity are maintained throughout the continuous etching process.
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 enhances mask selectivity and maintains an optimal etching shape without mask closure, improving the etching process by balancing selectivity and mask integrity.
Implementation Method 1
etching a poly silicon film deposited on the object to be processed into a mask pattern of a silicon-containing oxide film patterned by a spacer double patterning method by plasma generated from the process gas
Implementation Method 2
supplying a process gas containing hydrogen bromide HBr and oxygen O2 into the processing chamber
Implementation Method 3
intermittently supplying first high frequency power to either the first electrode or the second electrode while supplying second high frequency power lower than the first high frequency power to the second electrode
Data Source
AI summary
An etching method for etching an object to be processed in a processing chamber including a first electrode and a second electrode disposed facing the first electrode and configured to receive the object to be processed thereon is provided that includes steps of intermittently supplying first high frequency power to either the first electrode or the second electrode while supplying second high frequency power lower than the first high frequency power to the second electrode, supplying a process gas containing hydrogen bromide HBr and oxygen O2 into the processing chamber, and etching a poly silicon film deposited on the object to be processed into a mask pattern of a silicon-containing oxide film patterned by a spacer double patterning method by plasma generated from the process gas.