Tapered Sidewall Liner for High-Aspect-Ratio Etch Profiles
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Solution Overview
Problem
High aspect ratio etching processes in semiconductor manufacturing result in tapered features, leading to increased device failure, limited device density, and performance issues due to non-uniform passivation and defects such as CD increase, notching, and profile twisting.
Innovation Solution
A method involving a patterned mask, partial etching, and deposition of a tapered sidewall liner to control feature profiles, using plasma enhanced chemical vapor deposition (PECVD) to form a helmet mask, allowing for more aggressive etching while minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high aspect ratio etching is performed without a liner, then etch rate is improved, but feature profile becomes tapered and defects increase
Solution Approach 1:
A liner layer is deposited on the sidewalls of the patterned mask to act as an intermediary protective layer during etching. This liner prevents direct contact between the etchant and the mask, maintaining feature profile uniformity and preventing defects while allowing high etch rates to be achieved in the underlying stack.
Solution Approach 2:
The liner is deposited on the mask sidewalls before the main etching process begins. This preliminary deposition ensures that the mask is pre-protected against etching, allowing the subsequent high aspect ratio etching to proceed without profile degradation or feature widening.
2Reliability
If metal containing passivant is used during etching, then passivation is improved, but non-uniform deposition causes CD increase and notching
Solution Approach 1:
The liner layer serves as a disposable protective layer that is intentionally designed to be consumed or modified during the etching process. By using a sacrificial liner on the mask sidewalls, the process achieves uniform protection without the complications of metal-containing passivants, preventing CD increase and notching while maintaining reliable etching performance.
3Manufacturing precision
If tapered liner is deposited on sidewalls, then profile control is improved, but deposition complexity increases
Solution Approach 1:
The liner deposition process utilizes parameter changes in the PECVD process to create a tapered liner profile. By adjusting deposition parameters such as gas flow rates, pressure, and temperature during the deposition, a tapered liner is formed that is thicker at the top and thinner at the bottom, providing optimal profile control without requiring complex multi-step deposition sequences.
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 precise control of feature profiles, reducing tapering and defects, enabling deeper etches with consistent widths, and reducing manufacturing costs by minimizing mask thickness requirements.
Implementation Method 1
A tapered liner is deposited on the sidewalls of the features using plasma enhanced chemical vapor deposition (PECVD)
Data Source
AI summary
A method for etching features in a stack is provided. A patterned mask is formed over the stack. Features are partially etched in the stack through the patterned mask. A helmet mask is deposited over the patterned mask and liner on sidewalls of the features. The stack is etched through the helmet mask.