Two-Step Plasma Etching for PZT Structures
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Solution Overview
Problem
Plasma etching of PZT structures with noble metal electrodes results in involatile metal etch products that accumulate in the chamber, leading to reduced mean time between cleans (MTBC), flaking, and contamination, which decreases productivity and increases particle defects due to thermal gradients and poor adhesion.
Innovation Solution
A two-step plasma etching process with gas inlet switching, using different etch process gas mixtures supplied through separate gas inlet arrangements, to achieve more uniform deposition and extend MTBC by concentrating precursor gases around the gas inlets, thereby improving adhesion and reducing flaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single gas inlet arrangement is used for plasma etching, then the process is simple and quick, but deposition is non-uniform leading to flaking and reduced MTBC
Solution Approach 1:
The gas inlet arrangement is segmented into multiple separate inlet arrangements (first gas inlet arrangement and second gas inlet arrangement), each supplying different etch process gas mixtures to different regions of the chamber. This segmentation enables uniform deposition by distributing precursor gases more evenly throughout the chamber while maintaining a relatively simple overall structure.
2Reliability
If chamber cleaning is performed frequently to remove involatile metal etch products, then chamber cleanliness is maintained, but productivity decreases due to reduced MTBC
Solution Approach 1:
The involatile metal etch products that would normally accumulate and cause flaking are converted into beneficial uniform deposits on the chamber walls through the two-step etching process with multiple gas inlet arrangements. The harmful by-products become a protective uniform coating that prevents stress buildup and flaking, thereby extending MTBC and improving productivity.
3Productivity
If high power plasma etching is used to increase etch rate, then productivity improves, but thermal gradients increase causing flaking and particles
Solution Approach 1:
The plasma etching process is segmented into two distinct steps using different gas mixtures supplied through separate inlet arrangements. This allows optimization of each step for different purposes: first step for high etch rate with appropriate gas composition, second step for uniform deposition and stress control, thereby reducing thermal gradients and particle formation while maintaining overall productivity.
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 two-step etching process extends the MTBC, reduces particle defects, and maintains chamber cleanliness by promoting uniform deposition of etch products, enhancing the productivity and yield of PZT-based devices.
Implementation Method 1
etching the structure by performing a first plasma etch step using a first etch process gas mixture
Implementation Method 2
a first gas inlet arrangement comprising one or more gas inlets and a second gas inlet arrangement comprising one or more gas inlets
Data Source
AI summary
A structure comprising a substrate and a component which forms involatile metal etch products is plasma etched. A structure comprising a substrate and a component which forms involatile metal etch products is provided. The structure is positioned on a support within a chamber having a first gas inlet arrangement comprising one or more gas inlets and a second gas inlet arrangement comprising one or more gas inlets. The structure is etched by performing a first plasma etch step using a first etch process gas mixture which is only introduced into the chamber through the first gas inlet arrangement. The structure is further etched by performing a second plasma etch step using a second etch process gas mixture which is only introduced into the chamber through the second gas inlet arrangement.