Plasma Processing Apparatus Extended Protrusion Electrode
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Solution Overview
Problem
Conventional microwave plasma processing apparatuses face challenges in stabilizing plasma potential oscillation and preventing metal contamination of facing electrodes due to design limitations, which affect the efficiency and uniformity of plasma processes on semiconductor wafers.
Innovation Solution
A plasma processing apparatus with a design that includes an annular extended protrusion as a second electrode, forming a gap with the dielectric plate to increase the facing electrode's surface area, thereby stabilizing plasma potential and preventing sputtering, while maintaining a sufficient microwave introduction area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the facing electrode closely contacts the microwave transmissive plate to increase surface area, then plasma potential stability is improved, but microwave introduction becomes unstable and plasma generation becomes unstable
Solution Approach 1:
The patent transitions from a two-dimensional contact interface to a three-dimensional gap structure. By positioning the facing electrode at a specific distance (5-20mm) from the microwave transmissive plate, the design utilizes the third dimension (space) to simultaneously achieve large effective area for plasma potential stabilization while maintaining stable microwave introduction through the gap.
2Stability of the object's composition
If the facing electrode protrudes toward the processing space to increase surface area, then plasma potential stability is improved, but the front end of the facing electrode is sputtered by plasma causing contamination
Solution Approach 1:
Instead of extending the facing electrode horizontally into the plasma generation space (which causes sputtering), the patent utilizes the vertical dimension by positioning the electrode at an optimized distance from the microwave transmissive plate. This spatial arrangement allows the electrode to achieve sufficient effective area for plasma potential stabilization while remaining outside the high-energy plasma region, thereby preventing sputtering and contamination.
3Reliability
If a microwave transmissive plate is provided at the upper region of the processing chamber, then plasma generation is enabled, but the facing electrode cannot have a sufficiently large area due to design limitations
Solution Approach 1:
The patent resolves the area limitation by utilizing the vertical dimension (distance from the microwave transmissive plate) rather than being constrained to a two-dimensional plane. By positioning the facing electrode at an optimized distance (5-20mm) from the plate, the design effectively increases the electrode's functional area for plasma potential stabilization while maintaining compatibility with the microwave transmissive plate structure.
4Productivity
If high frequency power is applied to the mounting table electrode, then plasma process efficiency is improved, but plasma potential oscillation becomes large making the process unstable
Solution Approach 1:
The patent introduces a facing electrode as an intermediary element between the mounting table electrode and the plasma. This intermediate component provides a stable reference potential and facilitates the formation of a return circuit for high frequency current, thereby enabling efficient plasma processing while suppressing plasma potential oscillation and maintaining process stability.
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 solution effectively stabilizes plasma generation, reduces contamination, and enhances the uniformity of plasma processes on semiconductor wafers by providing a large facing electrode area without compromising microwave power transmission.
Implementation Method 1
a dielectric plate configured to form a plasma generation space by closing the opening of the processing chamber and transmit a microwave so as to introduce the microwave into the processing chamber
Implementation Method 2
a planar antenna provided above the dielectric plate and configured to introduce the microwave generated by a microwave generator into the processing chamber via the dielectric plate
Implementation Method 3
a first electrode embedded in the mounting table and configured to apply a bias voltage to the target object
Implementation Method 4
a surface of the facing electrode typically made of aluminum may be sputtered by the plasma, resulting in contamination
Data Source
AI summary
There is provided a plasma processing apparatus capable of stably generating plasma by suppressing oscillation of a plasma potential, and capable of preventing contamination caused by sputtering a facing electrode made of metal. A high frequency bias power is applied to an electrode within a mounting table for mounting a target object thereon. An extended protrusion 60 is formed at an inner peripheral surface of a cover member 27. The extended protrusion 60 is formed toward a plasma generation space S and serves as a facing electrode facing an electrode 7 within a mounting table 5 with the plasma generation space S therebetween. A ratio of a surface area of the facing electrode with respect to that of an electrode for bias (facing electrode surface area/bias electrode area) is in a range of from about 1 to about 5.