Matching Plasma Reactors via RF Source Tilt Angle Adjustment
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Solution Overview
Problem
Plasma reactors of identical design produce different etch rate distributions due to mechanical tolerances and assembly factors, leading to inconsistent processing results in semiconductor wafer manufacturing.
Innovation Solution
A method to match two plasma reactors by observing plasma skew magnitude and direction, computing non-uniformity values at successive tilt angles, and adjusting the tilt angle to align non-uniformity functions, ensuring consistent etch rate distributions across both reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma reactors of identical design are used in large manufacturing facilities, then productivity is improved through increased output, but manufacturing precision deteriorates due to differences in etch rate distribution among reactors
Solution Approach 1:
The patent applies parameter changes by adjusting the tilt angle of the RF power applicator in each plasma reactor. This mechanical parameter adjustment modifies the plasma ion density distribution to compensate for manufacturing variations, enabling different reactors to produce consistent etch rate distributions despite being identical in design
Solution Approach 2:
The patent implements preliminary action through a predictive method that determines the optimal tilt angle adjustment before actual production. By pre-characterizing each reactor's plasma skew and computing the required tilt angle offset, the system eliminates the need for trial-and-error adjustments during manufacturing, ensuring consistent etch rates from the outset
2Ease of manufacture
If mechanical tolerances and assembly factors are present in plasma reactors, then ease of manufacture is improved, but manufacturing precision deteriorates due to variations in plasma ion density distribution
Solution Approach 1:
The patent compensates for mechanical tolerances and assembly variations by changing the operational parameter of tilt angle. This adjustment modifies the plasma ion density distribution to counteract the effects of manufacturing tolerances, maintaining consistent etch rate distributions across reactors with standard assembly tolerances
Solution Approach 2:
The patent employs feedback through a measurement and computation process that characterizes each reactor's plasma skew and determines the corrective tilt angle adjustment. This feedback loop identifies the specific deviations caused by assembly factors and applies the precise correction needed to achieve uniform plasma ion density distribution
Data Source
AI summary
Etch rate distribution non-uniformities are predicted for a succession of hardware tilt angles of the RF source applicator relative to the workpiece, and the behavior is modeled as a non-uniformity function for each one of at least two plasma reactors. An offset Δα in tilt angle α between the non-uniformity functions of the two plasma reactors is detected. The two reactors are then matched by performing a hardware tilt in one of them through a tilt angle equal to the offset Δα.