Hardmask Film Stack for Lithography Profile Control
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Solution Overview
Problem
Current film stack and etching processes face challenges in forming high aspect ratio features with precise profile control and minimal material waste, as they often result in line width roughness, redeposition of by-products, and poor etching selectivity, leading to device failure and yield loss.
Innovation Solution
A method involving a film stack with a hardmask layer containing metal-containing materials and a carefully selected etching gas mixture, such as chlorine or bromine-containing gases, to enhance lithography exposure and etching precision, including the formation of a passivation layer to manage sidewalls and bottom surfaces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional etching processes are used to form high aspect ratio features, then feature depth can be achieved, but line width roughness increases and profile control deteriorates
Solution Approach 1:
A passivation layer is formed on the sidewalls of the photoresist layer before the etching process begins. This preliminary action protects the sidewalls during etching, preventing material redeposition and maintaining profile control throughout the deep etching process required for high aspect ratio features
Solution Approach 2:
The passivation layer acts as an intermediary material between the photoresist layer and the underlying layers being etched. It mediates the etching process by providing a protective barrier that prevents direct interaction between the etchant and the sidewalls, thereby maintaining manufacturing precision while achieving the required feature depth
2Productivity
If conventional etching processes are used, then etching can proceed, but redeposition of by-products blocks feature openings and limits aspect ratio
Solution Approach 1:
The passivation layer converts the harmful effect of redeposition into a beneficial protective barrier. Material that would otherwise redeposit and block feature openings is instead deposited onto the passivation layer, which protects the underlying feature openings and allows continuous etching at high rates without aspect ratio limitations
Solution Approach 2:
The passivation layer serves as an intermediary that intercepts redeposited by-products before they can reach and block the feature openings. This intermediary layer allows the etching process to proceed at high productivity while preventing the accumulation of harmful redeposited material in critical areas
3Ease of manufacture
If conventional film stack materials are used, then standard processing can be maintained, but etching selectivity is poor and profile accuracy deteriorates
Solution Approach 1:
The film stack materials are modified by changing their compositional parameters - specifically using metal-containing materials with atomic numbers greater than 28 in the hardmask layer. This parameter change enhances etching selectivity and profile accuracy while maintaining compatibility with standard processing techniques
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 profile control, reduced line edge roughness, and enhanced etching selectivity, thereby increasing device yield and reliability.
Implementation Method 1
etching the hardmask layer exposed by a photoresist layer, where the hardmask layer is etched by a gas mixture having a chlorine-containing gas or a bromine-containing gas
Implementation Method 2
formation of a passivation layer to manage sidewalls and bottom surfaces effectively
Data Source
AI summary
Methods for forming a film stack comprising a hardmask layer and etching such hardmask layer to form features in the film stack are provided. The methods described herein facilitate profile and dimension control of features through a proper profile management scheme formed in the film stack. In one or more embodiments, a method for etching a hardmask layer includes forming a hardmask layer on a substrate, where the hardmask layer contains a metal-containing material containing a metal element having an atomic number greater than 28, supplying an etching gas mixture to the substrate, and etching the hardmask layer exposed by a photoresist layer.