Plasma Etching Cycles With Protective Film for Dielectric Selectivity
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Solution Overview
Problem
Existing plasma processing techniques face challenges in achieving a high selectivity ratio for etching dielectric films while effectively removing etching films, particularly in maintaining the integrity of dielectric films during the etching process.
Innovation Solution
A plasma processing method involving a cycle of forming a protective film on a dielectric film using a carbon-containing gas and then etching both the protective film and the etching film using a noble gas, with an increasing bias signal power or DC voltage in subsequent cycles to enhance etching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plasma processing method uses a carbon-containing gas to form a protective film on the dielectric film and then uses a noble gas to etch the protective film and etching film, then the selectivity ratio for etching the etching film while protecting the dielectric film is improved, but the process complexity and number of processing steps increase
Solution Approach 1:
The plasma processing method is divided into multiple distinct cycles, each comprising a protective film formation step using carbon-containing gas and an etching step using noble gas. This segmentation allows independent optimization of protection and etching functions, achieving high selectivity ratio by controlling each step separately rather than attempting to achieve both functions in a single continuous process.
Solution Approach 2:
The method employs periodic alternation between protective film formation and etching operations through repeated cycles. By periodically switching between carbon-containing gas (for protection) and noble gas (for etching), the process achieves cumulative etching of the target film while maintaining dielectric film protection throughout the extended processing sequence.
2Productivity
If the bias signal power or DC voltage is increased in subsequent cycles to enhance etching efficiency, then the etching speed and productivity are improved, but the risk of damaging the dielectric film increases
Solution Approach 1:
A protective film is formed on the dielectric film surface before each etching operation. This preliminary protective layer acts as a sacrificial barrier that can withstand increased bias signal power or DC voltage during etching, allowing higher productivity without compromising dielectric film integrity. The protective film is specifically designed to be removable after etching while protecting the underlying dielectric.
Solution Approach 2:
The method introduces a cushioning protective film layer between the aggressive etching plasma and the sensitive dielectric film. This cushioning layer absorbs the impact of high-power bias signals during etching, preventing direct damage to the dielectric film while still allowing efficient etching of the target etching film through the protective layer.
3Quantity of substance
If multiple cycles of protective film formation and etching are repeated, then the overall etching depth and material removal are improved, but the processing time increases
Solution Approach 1:
The method dynamically adjusts processing parameters across repeated cycles, including modifying bias signal power, gas flow rates, and cycle durations. This dynamic optimization allows the process to maintain efficient material removal rates throughout multiple cycles while minimizing idle time and optimizing the balance between protective film formation and etching durations to reduce total processing time.
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 method achieves a high selectivity ratio for etching films by effectively protecting the dielectric films and incrementally increasing the etching efficiency through the bias signal power or DC voltage adjustments, thereby ensuring precise control over the etching process.
Implementation Method 1
supplying a processing gas containing at least a carbon-containing gas into the chamber to generate a plasma and forming a protective film at least on the dielectric film
Implementation Method 2
forming a protective film at least on the dielectric film
Implementation Method 3
supplying a processing gas containing at least a noble gas into the chamber to generate a plasma and supplying a bias signal to the substrate support unit to etch at least a portion of the protective film and the etching film
Implementation Method 4
supplying a bias signal to the substrate support unit to etch at least a portion of the protective film and the etching film
Data Source
AI summary
A plasma processing method includes: (a) preparing a substrate having an etching film and a dielectric film; (b) etching the etching film by repeatedly executing, a plurality of times, a cycle including (b-a) supplying a processing gas containing at least a carbon-containing gas into the chamber and forming a protective film at least on the dielectric film, and (b-b) supplying a processing gas containing at least a noble gas into the chamber; and (c) etching the etching film by executing, one or more times, a cycle including (c-a) supplying a processing gas containing at least a carbon-containing gas into the chamber, and (c-b) supplying a processing gas containing at least a noble gas into the chamber and supplying a bias signal to the substrate support.