RF Electrode Tuning for Selective Oxide Etching with Polymer Deposition
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in reliably forming submicron features with high aspect ratios and precise profiles while minimizing material waste and ensuring high production throughput, as conventional methods face issues with inaccurate lithography, redeposition of by-products, and poor etching selectivity, leading to device failure and low yield.
Innovation Solution
A method involving continuous gas flow and cyclic tuning of RF signals to electrodes for depositing and etching film stacks, using a polymer layer to selectively etch oxide and nitride portions, achieving high selectivity and controlled feature formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional etching methods are used to form high aspect ratio features, then feature depth can be achieved, but redeposition of by-products blocks feature openings and limits aspect ratio
Solution Approach 1:
The patent converts the harmful redeposition of etching by-products into a beneficial protective polymer layer through controlled deposition. This polymer layer prevents unwanted material accumulation while allowing the etching process to proceed, effectively transforming the harmful redeposition effect into a protective mechanism that enables higher aspect ratios.
Solution Approach 2:
The patent introduces a polymer layer as an intermediary substance between the etching reactants and the substrate. This polymer mediator protects the feature openings from being blocked by redeposited materials while permitting the etching reaction to continue, thus enabling the formation of high aspect ratio features without the harmful effects of material accumulation.
2Manufacturing precision
If high selectivity etching is used to achieve accurate profile control, then etching precision is improved, but production throughput decreases
Solution Approach 1:
The patent employs periodic alternation between deposition and etching cycles. During deposition phases, polymer is formed to protect features; during etching phases, material is removed with high selectivity. This periodic action allows the process to maintain high precision profile control while increasing overall throughput by optimizing both protective and etching functions in alternating sequences.
Solution Approach 2:
The patent achieves continuous useful action by maintaining a continuous flow of process gas throughout the entire process, eliminating idle time between deposition and etching steps. The cyclic tuning of RF signals to the electrode enables continuous alternation between deposition and etching modes without interrupting the gas flow, thereby maintaining productive action throughout the process and increasing throughput while preserving precision.
3Manufacturing precision
If lithography exposure and developing are used to transfer features, then feature patterning is achieved, but line width roughness and wiggling profiles cause inaccurate feature transfer
Solution Approach 1:
The patent applies preliminary action by forming a protective polymer layer on the substrate surface before the etching process begins. This pre-formed polymer layer compensates for potential lithography imperfections by providing a uniform protective barrier that ensures accurate feature transfer during etching, thereby improving both manufacturing precision and device yield.
Solution Approach 2:
The polymer layer serves as an intermediary that bridges the lithography pattern and the final etched feature. It provides a controlled, uniform interface that reduces the impact of lithography-induced line width roughness and wiggling profiles, ensuring more accurate feature transfer to the underlying film stack and improving device yield.
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 high selectivity in etching oxide over nitride portions, increases throughput, and reduces process gas consumption, resulting in improved feature precision and device yield.
Implementation Method 1
A first radio frequency (RF) signal is delivered to an electrode while the gas mixture is supplied at the continuous flow rate to deposit a polymer layer over the surface of the substrate
Implementation Method 2
A second RF signal is delivered to the electrode while continuously supplying the gas mixture at the continuous flow rate to selectively etch the oxide containing portion relative to the nitride containing portion
Data Source
AI summary
A method of forming features over a semiconductor substrate is provided. The method includes supplying a gas mixture over a surface of a substrate at a continuous flow rate. A first radio frequency (RF) signal is delivered to an electrode while the gas mixture is supplied at the continuous flow rate to deposit a polymer layer over the surface of the substrate. The surface of the substrate includes an oxide containing portion and a nitride containing portion. A second RF signal is delivered to the electrode while continuously supplying the gas mixture at the continuous flow rate to selectively etch the oxide containing portion relative to the nitride containing portion.