Carbon Layer Plasma Etching With Boron Passivation for CD Uniformity
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Solution Overview
Problem
Current plasma etch technologies face challenges in etching high aspect ratio features in semiconductor devices, particularly with carbon containing masks, as they suffer from bowing, clogging, local CD uniformity issues, and throughput limitations, where optimizing one characteristic often worsens another.
Innovation Solution
A method involving a simultaneous etch and passivation step using a plasma formed from a boron containing passivant gas and an oxygen containing gas, which etches features in the carbon containing layer while minimizing bowing and clogging, and improving local CD uniformity and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used to etch high aspect ratio features in carbon containing masks, then etching capability is achieved, but bowing and clogging occur which worsen manufacturing precision
Solution Approach 1:
A boron-containing passivant gas is introduced as an intermediary substance that deposits on the sidewalls of the etched features, forming a protective layer that prevents carbon mask material from migrating and clogging the features, thereby eliminating bowing and improving feature shape accuracy
Solution Approach 2:
The etch process parameters are changed by introducing a boron-containing passivant gas and optimizing the gas composition ratio, which alters the etching mechanism to reduce sidewall damage and prevent material migration, thus reducing bowing and clogging
2Productivity
If conventional etch processes are used, then etching is performed, but local CD uniformity and throughput are limited
Solution Approach 1:
The etch and passivation processes are merged into a single continuous step where boron-containing passivant gas is introduced during the etching process itself, eliminating the need for separate process steps and improving throughput while maintaining local CD uniformity through continuous sidewall protection
Solution Approach 2:
The etching and passivation functions are combined into a single integrated process step, where the boron-containing passivant gas performs both etching assistance and sidewall protection simultaneously, increasing productivity without sacrificing local CD uniformity
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 achieves improved ellipticity, reduced feature to feature CD variance, and increased throughput by using a single-step process that etches 90% to 100% of the feature depth, with boron containing passivation gas reducing sputtering and redeposition, thus enhancing defect performance and chip density.
Implementation Method 1
A plasma is created from the etch gas, wherein the plasma etches features in the carbon containing layer
Implementation Method 2
boron containing passivation gas reducing sputtering and redeposition
Data Source
AI summary
A method for etching features in a carbon containing layer below a mask is provided. A simultaneous etch and passivation step is provided comprising flowing an etch gas comprising a boron containing passivant gas and an oxygen containing gas. A plasma is created from the etch gas, wherein the plasma etches features in the carbon containing layer.