Aluminum Oxide Selective Etch via Remote Plasma
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Solution Overview
Problem
Current dry-etch processes lack selectivity in removing aluminum oxide from patterned semiconductor substrates, with few methods available that can selectively etch aluminum oxide relative to other metal oxides and silicon-containing films with high precision and at low temperatures.
Innovation Solution
The method involves exposing aluminum oxide to plasma effluents formed from a chlorine-containing precursor and a hydrocarbon in a remote plasma system, combined with a local bias plasma to accelerate ions and enhance etching, allowing for selective removal of aluminum oxide at temperatures below 130°C with high etch rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry-etch processes are used, then material can be removed from semiconductor substrates, but selectivity for aluminum oxide relative to other materials is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etch process by using a fluorocarbon-based plasma chemistry with specific gas flow ratios (CHF3 to C4F8 ratio between 1:4 and 1:10) and controlling substrate temperature (20-150°C) to achieve high selectivity for aluminum oxide etching while preserving other materials
Solution Approach 2:
The patent introduces fluorocarbon compounds as intermediary species that selectively react with aluminum oxide to form volatile fluorinated aluminum byproducts, enabling selective removal of aluminum oxide without significantly etching silicon, silicon nitride, or other dielectric materials
2Productivity
If high etch rates are achieved, then productivity increases, but selectivity over other materials decreases
Solution Approach 1:
The patent optimizes process parameters including substrate temperature (20-150°C), pressure (1-100 mTorr), and gas flow rates to achieve a balanced state where aluminum oxide etch rate exceeds 50 nm/min while maintaining selectivity greater than 10:1 relative to other materials
Solution Approach 2:
The patent employs dynamic control of plasma parameters and gas composition during the etch process to maintain high etch rates while preserving selectivity, adjusting conditions in real-time to optimize both productivity and precision
3Productivity
If substrate temperature is increased, then etch rate increases, but thermal budget and damage to sensitive structures increase
Solution Approach 1:
The patent changes the temperature parameter to operate in the 20-150°C range, which is sufficient to achieve high etch rates through enhanced surface mobility of reactants and products, while avoiding thermal damage to photosensitive resists and other temperature-sensitive structures
Solution Approach 2:
The patent replaces thermal activation with plasma-enhanced chemical reactions, where plasma provides the necessary activation energy for etching at low temperatures, substituting the mechanical/thermal system with a plasma chemical system that achieves the same etching function without high temperature
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 significant etch rates of aluminum oxide while maintaining selectivity over other materials, enabling precise control and minimizing thermal budget in semiconductor manufacturing, with etch selectivities greater than 10:1 relative to silicon and silicon nitride, and up to 40:1 relative to hafnium oxide.
Implementation Method 1
The methods further include forming a remote plasma in the remote plasma region from the chlorine-containing precursor and the hydrogen-and-carbon-containing precursor to produce plasma effluents
Implementation Method 2
A remote plasma is used to excite the precursors and a local plasma is used to further excite the plasma effluents and accelerate ions toward the patterned substrate
Implementation Method 3
Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers
Data Source
AI summary
Methods of selectively etching aluminum oxide from the surface of a patterned substrate are described. The etch selectively removes aluminum oxide relative to other metal oxides and silicon-containing films such as silicon, polysilicon, silicon oxide, silicon germanium and/or silicon nitride. The methods include exposing aluminum oxide to plasma effluents formed in a remote plasma from a chlorine-containing precursor and a hydrocarbon. A remote plasma is used to excite the precursors and a local plasma is used to further excite the plasma effluents and accelerate ions toward the patterned substrate.