Pulsed Plasma Etching Timing for Selective Silicon Film Patterning
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Solution Overview
Problem
Existing plasma processing methods face challenges in achieving high etching selectivity and rate, particularly when etching silicon-containing films with masks, due to instability in plasma generation and potential peeling of the mask during the etching process.
Innovation Solution
A plasma processing method involving periodic supply of a negative pulse voltage and RF power, where the pulse voltage is applied before the onset of RF power, stabilizes plasma generation and enhances etching selectivity and rate by controlling the timing of voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing methods are used to etch silicon-containing films, then etching can be performed, but etching selectivity is low and mask peeling occurs
Solution Approach 1:
The patent applies periodic pulsed voltage to the substrate holding electrode instead of continuous voltage. The pulse width is set to 1 μs to 10 ms, with the pulse repetition frequency controlled so that the pulse period is 1/10 to 1000 times the RF period. This periodic action stabilizes plasma generation while controlling ion bombardment energy, thereby improving etching selectivity and preventing mask peeling by reducing excessive ion impact.
Solution Approach 2:
The negative pulse voltage is applied to the substrate holding electrode before the RF power is supplied to generate plasma. This preliminary application of negative voltage prepares the electrode surface and establishes appropriate electric field conditions before plasma generation begins, ensuring stable plasma initiation and preventing mask peeling from the outset of the etching process.
2Productivity
If higher RF power is supplied to increase etching rate, then etching speed improves, but plasma stability decreases and mask peeling occurs
Solution Approach 1:
By applying periodic pulsed voltage with specific pulse widths (1 μs to 10 ms) and pulse repetition frequencies (1/10 to 1000 times the RF period), the patent stabilizes plasma generation even at higher RF power levels. The pulsed nature of the voltage prevents continuous high-energy ion bombardment that would cause mask peeling, while maintaining sufficient etching rate through controlled plasma density.
Solution Approach 2:
The patent changes the voltage application parameters by introducing pulse width (1 μs to 10 ms) and pulse repetition frequency (1/10 to 1000 times RF period) as control variables. These parameter changes allow the system to maintain plasma stability and prevent mask peeling while operating at RF power levels that provide high etching rates, effectively decoupling etching rate from plasma stability.
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
The method improves etching selectivity by 40% or more and etching rate by up to 30% compared to conventional methods, by stabilizing plasma and preventing mask peeling.
Implementation Method 1
periodically supplying RF power and generating plasma from the process gas by the RF power to etch the silicon-containing film
Data Source
AI summary
A plasma processing method includes:a) providing a substrate on a substrate support;b) supplying a process gas;c) periodically supplying a pulse voltage to the substrate support; andd) periodically supplying RF power and generating plasma from the process gas to etch a silicon-containing film included in the substrate. The pulse voltage is negative. A first period in which a first pulse voltage is supplied and a second period in which the pulse voltage is not supplied or a second pulse voltage whose absolute value is less than that of the first pulse voltage is supplied are repeated in c). A third period in which first RF power is supplied and a fourth period in which the RF power is not supplied or second RF power less than the first RF power is supplied are repeated in d). The first period starts before a start of the third period.