HARC Etch Chemistry Using Metallic Masks for Higher Selectivity
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Solution Overview
Problem
Existing high aspect ratio contact (HARC) etches in semiconductor manufacturing face issues with slower etch rates and contact deformations due to the use of polymeric fluorocarbon gases, which adversely affect device performance.
Innovation Solution
Employing a mask made of at least partially metallic materials, such as tungsten silicide (WSiX), and using etchant gases like CF4, CHF3, and NF3 to improve etch rates and selectivity, avoiding carbon-based deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric fluorocarbon gases are used for HARC etching, then mask protection is improved, but etch rate decreases and contact deformations occur
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant gas from polymeric fluorocarbon gases to non-polymeric fluorocarbon gases (CF4, CHF3, NF3), which fundamentally alters the etching mechanism to eliminate carbon-based deposition while maintaining mask protection through controlled chemical reactions with the oxide-containing material layer
Solution Approach 2:
The patent employs a disposable-like approach by using non-polymeric gases that do not form persistent protective polymers on the mask, allowing for cleaner etching processes without the accumulation of deformable carbon-based deposits, thus maintaining mask integrity throughout the etching process
2Reliability
If polymeric fluorocarbon gases are used for HARC etching, then mask protection is improved, but contact deformation increases
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant gas from polymeric fluorocarbon gases to non-polymeric fluorocarbon gases (CF4, CHF3, NF3), which fundamentally alters the etching mechanism to eliminate carbon-based deposition that causes contact deformation, while maintaining mask protection through controlled chemical reactions
Solution Approach 2:
The patent converts the potential harm of reduced mask protection (from using non-polymeric gases) into a benefit by demonstrating that the cleaner etching process without carbon deposition actually improves overall process control and reduces contact deformation, achieving better manufacturing precision
3Productivity
If non-polymeric fluorocarbon gases are used, then etch rate increases, but mask selectivity may worsen
Solution Approach 1:
The patent applies local quality by targeting specific chemical interactions - the non-polymeric fluorocarbon gases are selected to have high reactivity with the oxide-containing material layer (improving etch rate) while maintaining appropriate selectivity through controlled reaction conditions and gas composition optimization
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 results in higher etch rates, reduced contact deformations, and improved selectivity between the mask and wafer, enhancing device yield and performance.
Implementation Method 1
selectively etching the mask and the wafer under the mask by using an etchant gas that is selected from a group consisting of CF4, CHF3, and NF3
Data Source
AI summary
A method for etching wafer includes providing a wafer, forming a mask comprising a pattern on a surface of the wafer, and etching the mask by using an etchant gas. The wafer includes an oxide containing material layer. The mask includes a material at least partially containing a metal. The etchant gas is selected from a group consisting of CF4, CHF3, and NF3. Therefore, increased selectivity between the mask and the wafer and satisfactory etch rate (ER) can be achieved.