Hardmask Etching Profile Control via Passivation Layer
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Solution Overview
Problem
Current etching processes for forming submicron features with high aspect ratios face challenges such as redeposition of by-products, irregular profiles, and loss of dimensional control, leading to device failure and low yield due to inadequate etching selectivity and sidewall protection.
Innovation Solution
A method involving a controlled etching and passivation process using a gas mixture to form a passivation layer on the sidewalls of a hardmask layer, allowing for precise control of etching profiles and dimension management by alternating between etching and deposition phases with specific gas mixtures, including silicon-containing gases, to prevent redeposition and maintain sidewall protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If traditional anisotropic etching is used to form high aspect ratio features, then etching depth can be achieved, but redeposition of by-products blocks the feature opening and prevents reactive etchants from reaching the lower surface
Solution Approach 1:
A passivation layer is formed on the sidewalls of the hardmask layer before completing the etching process. This preliminary protective action prevents redeposition material from blocking the feature opening, allowing reactive etchants to continue reaching the lower surface and achieve the required etching depth for high aspect ratio features
Solution Approach 2:
The passivation layer acts as an intermediary protective barrier between the redeposition material and the sidewalls of the hardmask layer. This intermediate layer prevents direct contact and adhesion of redeposition material, maintaining feature opening patency while enabling continued etching progress
2Length of stationary object
If etching continues to increase aspect ratio, then feature depth increases, but redeposition material randomly adheres to sidewalls causing irregular profiles and bowing
Solution Approach 1:
The passivation layer is formed in advance on the sidewalls before the etching process completes, establishing a protective barrier that prevents random adhesion of redeposition material. This preliminary action ensures uniform profile development and prevents bowing or twisting profiles throughout the etching process
Solution Approach 2:
The passivation layer serves as an intermediary that mediates between the redeposition material and the sidewall surface. This intermediate barrier ensures uniform material distribution and prevents irregular profile formation, maintaining manufacturing precision for high aspect ratio features
3Productivity
If aggressive etchants are used to etch the hardmask layer, then etching speed increases, but the hardmask layer and BARC/ARC are damaged resulting in inaccurate pattern transfer
Solution Approach 1:
The passivation layer is formed in advance on the sidewalls of the hardmask layer, creating a protective barrier before aggressive etching begins. This preliminary protection allows the use of aggressive etchants at high speeds while preventing damage to the hardmask layer and BARC/ARC, thereby maintaining pattern transfer accuracy
Solution Approach 2:
The passivation layer acts as an intermediary protective layer between the aggressive etchants and the hardmask layer/BARC-ARC structure. This intermediate barrier enables high-speed etching while mediating the interaction to prevent sidewall damage and maintain dimensional control
4Device complexity
If no sidewall protection is provided during etching, then etching process is simpler, but corner features suffer from rounded top shoulder erosion and loss of dimensional control
Solution Approach 1:
The passivation layer is formed in advance on the sidewalls and corner regions before the etching process completes. This preliminary protective action prevents rounded top shoulder erosion and maintains sharp corner features, ensuring dimensional control without significantly complicating the overall 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
This approach enables the formation of features with desired profiles and high aspect ratios while maintaining accurate critical dimensions, reducing device failure and improving yield by ensuring reliable pattern transfer and structural integrity.
Implementation Method 1
switching the etching gas mixture to a deposition gas mixture comprising a silicon containing gas to form a passivation layer on sidewalls of the hardmask layer
Implementation Method 2
supplying an etching gas mixture onto a substrate to etch an exposed portion of a hardmask layer
Data Source
AI summary
Methods for etching a hardmask layer to transfer features into a material layer using an etch process are provided. The methods described herein advantageously facilitate profile and dimension control of features through a proper sidewall and bottom management scheme during the hardmask open process. In one embodiment, a method for etching a hardmask layer to form features in the hardmask layer includes supplying an etching gas mixture onto a substrate to etch an exposed portion of a hardmask layer exposed by a patterned photoresist layer disposed on the substrate, switching the etching gas mixture to a deposition gas mixture comprising a silicon containing gas to form a passivation layer on sidewalls of the hardmask layer and forming openings in the hardmask layer.