Plasma Processing Apparatus Bent Gas Flow Path
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Solution Overview
Problem
In plasma processing apparatuses, applying higher negative DC voltage to accelerate secondary electrons and ions for high aspect ratio etching holes leads to abnormal electric discharge, reducing semiconductor device yield due to reaction products depositing on the wafer surface.
Innovation Solution
A plasma processing apparatus design with a bent gas flow path between the upper and grounding electrodes, increasing the distance and pressure between electrodes to prevent electric discharge, while maintaining a higher DC voltage, using a configuration where the gas flow path has a horizontal component and obstructing straight movement of the processing gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a higher negative DC voltage is applied to accelerate secondary electrons and ions for high aspect ratio etching holes, then the etching capability is improved, but abnormal electric discharge occurs which reduces semiconductor device yield
Solution Approach 1:
A gas flow path is introduced as an intermediary element between the upper electrode and the wafer. This gas flow path serves as a mediator that prevents direct electrical contact and abnormal discharge while allowing the processing gas to reach the wafer surface for etching. The gas flow path effectively decouples the electrical field application from the gas delivery function, enabling high voltage operation without discharge.
Solution Approach 2:
The gas flow path extends in the vertical dimension between the upper electrode and the wafer, creating a three-dimensional structure that prevents horizontal electrical discharge. By utilizing the vertical space and creating a layered configuration, the invention separates the electrical field region from the gas flow region, allowing high voltage to be applied without causing abnormal discharge that would otherwise occur in a planar configuration.
2Manufacturing precision
If a higher negative DC voltage is applied to form high aspect ratio etching holes, then the aspect ratio is improved, but reaction products are deposited on the wafer surface due to abnormal electric discharge
Solution Approach 1:
The gas flow path acts as an intermediary barrier that prevents the formation of abnormal electric discharge. By introducing this intermediate structure, the invention eliminates the harmful reaction products that would otherwise be generated by discharge, while still allowing the processing gas to flow through and enable high aspect ratio etching hole formation.
Solution Approach 2:
The invention converts the potential harm of high voltage application (which causes abnormal discharge) into a benefit by using the gas flow path to guide and control the voltage application. The gas flow path transforms what would be a harmful electrical discharge into a controlled process that enables high aspect ratio etching without harmful byproducts.
3Productivity
If a straight gas flow path is used between electrodes, then the gas flow efficiency is improved, but electric discharge occurs at the vicinity of the upper electrode
Solution Approach 1:
The gas flow path is designed with a bent or curved configuration rather than a straight line. This curvature in the gas flow path increases the distance between the upper electrode and the wafer while still allowing efficient gas flow. The bent path prevents direct electrical field lines from forming, thereby eliminating abnormal electric discharge while maintaining gas flow efficiency.
Solution Approach 2:
The gas flow path utilizes the vertical dimension by bending upward and then downward, creating a three-dimensional flow path. This dimensional approach increases the effective distance between electrodes in the electrical field direction while maintaining compact horizontal footprint, preventing discharge without sacrificing gas flow efficiency.
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
Prevents electric discharge during high DC voltage application, allowing for the formation of etching holes with higher aspect ratios without yield reduction by increasing the distance and pressure between electrodes, ensuring efficient plasma processing.
Implementation Method 1
a high frequency power is applied to at least one of an upper electrode and a lower electrode provided to face each other, a gas is excited into plasma by electric field energy of the high frequency power
Implementation Method 2
a negative DC voltage is applied to the upper electrode such that an application voltage during a period when the application of the high frequency power is OFF is higher than an application voltage during a period when the application of the high frequency power is ON
Data Source
AI summary
A plasma processing apparatus comprises an upper electrode 42, a lower electrode, a grounding member 61 provided above the upper electrode 42 via an insulating member 60; and a DC power supply for applying a DC voltage to the upper electrode 42. Gas diffusion rooms 54 and 55 communicating with a gas supply opening 53 formed at a lower surface of the upper electrode 42 are formed in the upper electrode 42 and a gas flow path 62 communicating with the gas diffusion rooms 54 and 55 is formed in the insulating member 60. A bent portion 63 for allowing a gas within the gas flow path to flow in a direction having at least a horizontal component is formed at the gas flow path 62 such that an end of the gas flow path 62 cannot be seen from the other end thereof when viewed from the top.