Plasma Etching Apparatus Radial Gas Flow Control
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Solution Overview
Problem
In plasma etching for semiconductor manufacturing, achieving uniformity in the etching of larger wafers is challenging due to non-uniform diffusion of radicals across the wafer plane, affecting line width and depth uniformity.
Innovation Solution
A plasma etching apparatus with multiple gas supply units positioned equidistantly around the wafer, controlled by a controller to adjust the flow rate of processing gas in each region based on a specific equation, ensuring uniform plasma distribution and etching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single gas supply unit is used for the entire wafer surface, then the device structure is simple, but the in-plane uniformity of etching characteristics deteriorates due to non-uniform radical diffusion
Solution Approach 1:
The gas supply unit is divided into multiple independent gas supply regions (first, second, third regions) that correspond to different radial zones of the wafer. Each region has its own gas supply holes and flow control, allowing independent adjustment of processing gas flow to different areas of the wafer surface to compensate for non-uniform radical diffusion
Solution Approach 2:
Different flow rates of processing gas are supplied to different radial regions of the wafer based on the local radical diffusion characteristics. The gas supply holes in each region are configured with specific flow rates to achieve uniform processing gas concentration across the entire wafer surface, addressing the non-uniformity at each location
2Productivity
If the wafer diameter is enlarged to increase productivity, then the processing capacity improves, but the in-plane uniformity of line width and depth uniformity deteriorates due to increased radial variation in radical diffusion
Solution Approach 1:
The gas supply system is segmented into multiple radial regions with independent flow control, allowing each region to be optimized for the specific radical diffusion characteristics at that radial position on the large-diameter wafer
Solution Approach 2:
The flow rate parameter of processing gas is varied across different radial regions to compensate for the non-uniform radical diffusion that occurs on large-diameter wafers, maintaining uniform etching characteristics across the entire wafer surface
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 allows for precise control of the flow rate ratio, enhancing in-plane uniformity of etching characteristics and improving the etching process on larger wafers by optimizing the distribution of radicals across the wafer plane.
Implementation Method 1
a high frequency power source configured to supply a high frequency power to at least one of the holding unit and the electrode plate so as to generate plasma from the processing gas supplied into the space by the plurality of supply units
Implementation Method 2
since the diffusion state of radicals is not uniform in the central region and the peripheral region in the wafer plane
Data Source
AI summary
A plasma etching apparatus of the present disclosure etches a substrate by plasma of a processing gas. The plasma etching apparatus includes a processing container; a holding unit configured to hold a substrate; and an electrode plate. The plasma etching apparatus further includes configured to supply the processing gas to a space between the holding unit and the electrode plate and disposed in n (n is a natural number of two or more) regions of the substrate divided concentrically in a radial direction, respectively. In addition, the plasma etching apparatus further includes a high frequency power source configured to supply a high frequency power to at least one of the holding unit and the electrode plate so as to generate plasma. The plasma etching apparatus controls a flow rate of the processing gas.