SiC Trench Mask Structure for High-Temperature Etching
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Solution Overview
Problem
Existing mask structures for semiconductor trench etching and impurity implantation are not compatible with silicon carbide substrates, which require high-temperature processes, limiting their applicability and process efficiency.
Innovation Solution
A novel mask structure comprising a photoresist hard mask atop a thin metal layer and an oxide layer, allowing for trench etching and subsequent ion implantation, with adjustable thickness for substrate compatibility and plasma etch selectivity, enabling use with silicon carbide and other substrates like silicon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mask structures are used for trench etching and impurity implantation, then the process works for standard substrates, but the mask structure is incompatible with silicon carbide substrates requiring high-temperature processes
Solution Approach 1:
The patent employs a composite mask structure consisting of multiple layers including photoresist, metal layers (such as tungsten or molybdenum), and dielectric layers. This composite construction allows the mask to withstand high-temperature silicon carbide processing while maintaining its structural integrity and functionality for both trench etching and ion implantation operations.
2Productivity
If a single mask structure is used for both trench etch and ion implantation processes, then process efficiency is improved, but the mask design becomes more complex
Solution Approach 1:
The patent designs a universal mask structure that performs multiple functions: it serves as the masking layer for trench etching and subsequently as the alignment reference for ion implantation. The mask includes specific geometric features and layer configurations that enable it to fulfill both roles without requiring separate masking steps, thereby improving overall process efficiency.
3Duration of action of stationary object
If the photoresist mask layer is used to resist lengthy etch processes, then the mask durability is improved, but the photoresist material selection and thickness must be precisely controlled
Solution Approach 1:
The patent optimizes the photoresist layer parameters including thickness (typically 1-5 micrometers), composition, and cross-linking characteristics to achieve sufficient durability during lengthy etch processes. The photoresist is formulated and processed to maintain its structural integrity throughout the etching operation while allowing for precise thickness control through standardized deposition and development procedures.
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
Enables efficient trench formation and ion implantation processes for silicon carbide and other substrates, such as MOSFETs and IGBTs, with the hard mask resisting lengthy etch processes and serving as a self-aligned doping mask, enhancing process compatibility and efficiency.
Implementation Method 1
the plasma etch of the exposed underlying metal and oxide and the subsequent plasma etch of spaced trenches into the substrate
Implementation Method 2
the plasma etch of the exposed underlying metal and oxide
Data Source
AI summary
A mask structure and process for forming trenches in a silicon carbide or other wafer, and for implanting impurities into the walls of the trenches using the same mask where the mask includes a thin aluminum layer and a patterned hard photoresist mask. A thin LTO oxide may be placed between the metal layer and the hard photoresist mask.