Hydrogen Peroxide Plasma Etching for Ashable Hard Mask Removal
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Solution Overview
Problem
Conventional methods for removing ashable hard masks (AHMs) from semiconductor wafers are inefficient and generate harmful fluorine radicals and greenhouse gases, leading to costly scrubbing processes and potential damage to underlying materials.
Innovation Solution
A hydrogen peroxide plasma etching method is employed, using a gas mixture with hydrogen peroxide vapor concentrations greater than 0.1% by volume, which forms a stable plasma to effectively remove AHMs without generating halogen radicals or byproducts, thereby minimizing damage to the substrate and adjacent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oxygen plasma or fluorine-based plasma is used to remove AHM, then the AHM can be removed, but harmful fluorine radicals and fluorinated greenhouse gases are generated requiring costly scrubbing
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma gas from conventional oxygen or fluorine-based gases to hydrogen peroxide vapor (H2O2) at controlled concentrations (0.1-10% by volume). This parameter change enables AHM removal through oxidation by hydroxyl radicals while avoiding the generation of harmful fluorinated byproducts, thus resolving the contradiction between removal efficiency and harmful emissions
Solution Approach 2:
The patent employs hydrogen peroxide as a strong oxidant that decomposes in plasma to generate highly reactive hydroxyl radicals (•OH). These radicals efficiently oxidize and remove the carbon-based AHM material through chemical reactions, achieving effective AHM removal without the environmental harm associated with fluorine-based methods
2Productivity
If conventional plasma methods are used to remove AHM, then the AHM can be removed, but underlying materials suffer from oxidation and damage
Solution Approach 1:
The patent achieves selective etching by creating different chemical environments at different locations. The hydrogen peroxide plasma generates hydroxyl radicals that preferentially react with the carbon-based AHM material while being less aggressive toward the underlying silicon or other sensitive materials. This local selectivity in chemical reactivity enables effective AHM removal with minimal damage to underlying structures
Solution Approach 2:
The hydrogen peroxide vapor acts as an intermediary substance that mediates the etching process. It decomposes in the plasma to generate reactive hydroxyl radicals that serve as the actual etching species. This intermediary mechanism provides controlled and selective oxidation that removes AHM while minimizing direct plasma exposure and damage to underlying materials
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 hydrogen peroxide plasma etching method enables efficient removal of AHMs with reduced oxidation and damage to underlying materials, offering a more environmentally friendly and cost-effective alternative compared to traditional oxygen plasma methods.
Implementation Method 1
forming a plasma from a gas mixture, wherein: the gas mixture includes hydrogen peroxide vapor with a concentration greater than 0.1% by volume; the concentration of the hydrogen peroxide vapor in the gas mixture is substantially stable over time; and the plasma includes hydrogen peroxide species
Implementation Method 2
etching an ashable hard mask (AHM) on a substrate by exposing the AHM to the plasma
Implementation Method 3
The hydrogen peroxide plasma etching method enables efficient removal of AHMs with reduced oxidation and damage to underlying materials
Data Source
AI summary
The techniques described herein relate to a method for etching an ashable hard mask (AHM) on a substrate. The method includes forming a plasma from a gas mixture, wherein the gas mixture includes hydrogen peroxide vapor with a concentration greater than 0.1% by volume, wherein the concentration of the hydrogen peroxide vapor in the gas mixture is substantially stable over time, and wherein the plasma comprises hydrogen peroxide species. The method further includes etching the AHM by exposing the AHM to the plasma.