Selective Etching via Dynamic E-Mode to H-Mode Plasma Transition
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Solution Overview
Problem
Current etching technologies, such as TCP and ICP, are limited in achieving highly selective etching of semiconductor films like SiN, polysilicon, and silicon dioxide due to their inability to provide the necessary plasma conditions at low pressures.
Innovation Solution
The solution involves operating a high-density plasma source at high pressures (>0.5 Torr) and controlling the ratio of electric (E-mode) to magnetic (H-mode) RF coupling by varying ICP power, RF frequency, and gas chemistry, allowing for optimized plasma properties and selective etching by transitioning between E-mode and H-mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching technologies (TCP, ICP) are used, then the etching process can be performed, but highly selective etching cannot be achieved due to inability to provide necessary plasma conditions at low pressures
Solution Approach 1:
The system dynamically transitions between E-mode and H-mode plasma operation during the etching process. This dynamic mode switching enables optimization of plasma conditions at different stages, achieving highly selective etching by providing appropriate plasma characteristics (electron temperature and density) that conventional static systems cannot deliver
Solution Approach 2:
The invention changes fundamental plasma parameters by switching between E-mode and H-mode operation. This parameter change allows the system to provide the necessary plasma conditions at low pressures that conventional etching technologies cannot achieve, thereby enabling highly selective etching of different film types
2Temperature
If E-mode plasma is used, then electron temperature can be maintained, but electron density is insufficient for highly selective etching
Solution Approach 1:
The system transitions from E-mode to H-mode plasma operation during the etching process. This dynamic transition allows the system to first establish electron temperature in E-mode, then increase electron density by switching to H-mode, achieving both conditions necessary for highly selective etching
3Quantity of substance
If H-mode plasma is used, then electron density is high, but electron temperature is reduced limiting selective etching capability
Solution Approach 1:
The system transitions from H-mode back to E-mode plasma operation after the initial etching stage. This dynamic transition allows the system to first utilize H-mode for high electron density, then switch to E-mode to maintain electron temperature for selective etching of remaining films
4Productivity
If conventional plasma sources are used, then the etching process can proceed, but nitride/oxide selectivity is insufficient
Solution Approach 1:
The dynamic mode switching between E-mode and H-mode enables the system to optimize plasma conditions specifically for nitride/oxide selectivity. By transitioning between modes, the system achieves both adequate etching rate and high selectivity that conventional static plasma sources cannot provide
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 highly selective etching by optimizing electron temperature and electron density, allowing for the selective generation of radicals for etching while minimizing passivation, thereby improving nitride/oxide selectivity.
Implementation Method 1
radio frequency (RF) plasma may be used to activate chemical reactions
Implementation Method 2
inductively coupled plasma (ICP)
Data Source
AI summary
A method for selectively etching one exposed material of a substrate relative to another exposed material of the substrate includes a) arranging the substrate in a processing chamber; b) setting a chamber pressure; c) setting an RF frequency and an RF power for RF plasma; d) supplying a plasma gas mixture to the processing chamber; e) striking the RF plasma in the processing chamber in one of an electric mode (E-mode) and a magnetic mode (H-mode); and f) during plasma processing of the substrate, changing at least one of the chamber pressure, the RF frequency, the RF power and the plasma gas mixture to switch from the one of the E-mode and the H-mode to the other of the E-mode and the H-mode.