HF Plasma Etching with Metal Masks for High Selectivity
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Solution Overview
Problem
Current etching methods face challenges in achieving high selectivity between silicon-containing films and masks during plasma etching processes, particularly with polysilicon masks on silicon-containing films, where the etching process often results in inadequate selectivity and feature failures.
Innovation Solution
The method involves using a plasma processing apparatus with a chamber to etch a substrate containing a silicon-containing film and a mask made of metals like tungsten, molybdenum, ruthenium, titanium, indium, or zinc, utilizing a process gas that includes hydrogen fluoride gas, with specific control of temperature and gas flow rates to enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used with polysilicon masks on silicon-containing films, then the etching process can be performed, but the etching selectivity between the mask and the film is insufficient
Solution Approach 1:
The patent changes the material parameter of the mask from polysilicon to metals with high affinity for fluorine (tungsten, molybdenum, ruthenium, titanium, indium, gallium, or zinc). This parameter change in mask material composition fundamentally alters the etching selectivity by exploiting the chemical affinity difference between these metals and fluorine-containing etchants, thereby resolving the selectivity issue without causing feature failures.
2Productivity
If the etching rate of the silicon-containing film is increased, then the productivity improves, but the etching selectivity between the film and the mask deteriorates
Solution Approach 1:
The patent changes the mask material parameter to metals with high fluorine affinity, which creates a selective etching response. These metals form protective fluoride layers that reduce their own etching rate while allowing the silicon-containing film to etch at high rates. This parameter change decouples the productivity-selectivity trade-off, enabling high productivity without sacrificing 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 significantly improves the etching selectivity between the silicon-containing film and the mask, reducing the mask's etching rate while increasing the film's etching rate, thereby minimizing feature failures and enhancing the precision of the etching process.
Implementation Method 1
etching the etching target film using plasma generated from a process gas including a hydrogen fluoride gas
Implementation Method 2
The mask contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc
Data Source
AI summary
An etching method is implementable with a plasma processing apparatus including a chamber. The method includes (a) providing, in the chamber, a substrate including an etching target film and a mask on the etching target film, and (b) etching the etching target film using plasma generated from a process gas including a hydrogen fluoride gas. The mask contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc.