Plasma Reactor Asymmetry Correction via Tiltable Applicator
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Solution Overview
Problem
In semiconductor device fabrication, maintaining uniform plasma etch rates across large workpieces is challenging due to asymmetrical plasma ion density distributions caused by non-symmetrical reactor chamber configurations and vacuum pump placement, which conventional control features are unable to fully correct.
Innovation Solution
A plasma reactor with a tiltable and rotatable plasma source power applicator and adjustable RF power distribution allows for transformation of asymmetrical etch rate distributions into symmetrical ones, enabling uniform etch rate correction by adjusting the relative positions and power levels of inner and outer applicator portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional control features (symmetrical adjustments) are used, then device complexity is reduced, but manufacturing precision deteriorates due to inability to correct asymmetrical plasma distribution
Solution Approach 1:
The patent applies asymmetry by making the plasma source power applicator asymmetrical in structure and positioning. The applicator includes an asymmetrical distribution of conductive elements and reactances, and can be positioned at an asymmetrical location within the chamber. This allows the control features themselves to be asymmetrical, enabling them to correct the asymmetrical plasma distribution patterns that occur during plasma processing of large workpieces.
2Manufacturing precision
If vacuum pump is located at one particular location, then device complexity is reduced, but plasma distribution uniformity deteriorates due to asymmetrical pumping
Solution Approach 1:
The patent accepts the asymmetrical vacuum pump configuration as a given constraint and compensates for it by introducing asymmetry into the plasma source power applicator. The applicator's asymmetrical design and positioning counterbalance the asymmetrical vacuum pumping, allowing uniform plasma distribution to be achieved despite the single-location vacuum pump.
3Manufacturing precision
If RF power is applied uniformly across the ceiling, then device complexity is reduced, but etch rate uniformity deteriorates due to asymmetrical plasma characteristics
Solution Approach 1:
The patent applies local quality by creating non-uniform RF power distribution across the plasma source power applicator. The applicator has different impedance characteristics at different locations, and RF power is applied with varying magnitude and phase across different regions. This localized variation in RF power application compensates for the asymmetrical plasma distribution patterns.
Solution Approach 2:
The RF power distribution is made asymmetrical to match the asymmetrical plasma distribution. The applicator positioning and conductive element distribution are asymmetrical, creating corresponding asymmetrical RF power patterns that correct the plasma non-uniformities.
4Adaptability or versatility
If plasma source power applicator is fixed in position, then device complexity is reduced, but adaptability deteriorates due to inability to correct non-uniformities
Solution Approach 1:
The patent applies dynamics by making the plasma source power applicator movable rather than fixed. The applicator can be repositioned to different locations within the chamber and can be tilted to different orientations. This dynamic positioning capability allows the system to adapt to different workpiece sizes, shapes, and processing requirements, enabling correction of various non-uniformity patterns.
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 effectively transforms asymmetrical etch rate distributions into uniform ones, improving plasma process uniformity and correcting non-uniformities across the workpiece surface.
Implementation Method 1
a plasma source power applicator overlying the ceiling and comprising a radially inner applicator portion and a radially outer applicator portion, and RF power apparatus coupled to said inner and outer applicator portions
Implementation Method 2
tilt apparatus capable of tilting either the workpiece support pedestal or the outer applicator portion about a radial axis perpendicular to said axis of symmetry
Implementation Method 3
capable of rotating said workpiece support pedestal about said axis of symmetry
Implementation Method 4
a vacuum pump coupled to the chamber
Data Source
AI summary
A plasma reactor for processing a workpiece includes a process chamber comprising an enclosure including a ceiling and having a vertical axis of symmetry generally perpendicular to said ceiling, a workpiece support pedestal inside the chamber and generally facing the ceiling, process gas injection apparatus coupled to the chamber and a vacuum pump coupled to the chamber. The reactor further includes a plasma source power applicator overlying the ceiling and comprising a radially inner applicator portion and a radially outer applicator portion, and RF power apparatus coupled to said inner and outer applicator portions, and tilt apparatus capable of tilting either the workpiece support pedestal or the outer applicator portion about a radial axis perpendicular to said axis of symmetry and capable of rotating said workpiece support pedestal about said axis of symmetry. In a preferred embodiment, the reactor further includes apparatus for effecting axially symmetrical adjustments of plasma distribution, which may be either (or both) elevation apparatus for changing the location of said inner and outer portions relative to one another along said vertical axis of symmetry, or apparatus for apportioning the RF power levels applied to the inner and outer applicator portions.