Electrostatic Chuck Capacitance Matching for Stable Plasma Etching
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Solution Overview
Problem
In semiconductor device manufacturing, high aspect ratio etching processes using plasma processing apparatuses with focus rings of varying heights fail to adequately suppress tilting of contact holes due to impedance mismatches between the target substrate and the focus ring, leading to variations in ion incidence angles and hole inclinations when bias power is changed.
Innovation Solution
A plasma processing apparatus with a dielectric layer between the outer peripheral portion of the electrostatic chuck and the base or focus ring, which reduces the difference in electrostatic capacitance between the central and peripheral portions, ensuring impedance matching and stabilizing the plasma sheath heights regardless of bias power changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring with multiple flat portions of different heights is used, then tilting suppression is improved, but impedance matching between central and peripheral portions deteriorates when bias power changes
Solution Approach 1:
The patent changes the electrostatic capacitance parameter by introducing a dielectric layer with specific capacitance values. The dielectric layer has an electrostatic capacitance of 0.5 nF to 5 nF, which reduces the difference between central and peripheral electrostatic capacitances to within 10%, thereby maintaining impedance matching stability when bias power changes while preserving tilting suppression
Solution Approach 2:
The dielectric layer acts as an intermediary component between the electrostatic chuck and the base or focus ring. This intermediary layer with controlled electrostatic capacitance mediates the electrical field distribution, balancing the impedance between central and peripheral regions and stabilizing plasma sheath height regardless of bias power variations
2Adaptability or versatility
If bias power magnitude is changed during plasma processing, then processing flexibility is improved, but plasma sheath height relation between target substrate and focus ring varies
Solution Approach 1:
The dielectric layer creates equipotential conditions by equalizing the electrostatic capacitance difference between central and peripheral portions. This ensures that when bias power changes, the plasma sheath heights above the target substrate and focus ring maintain a consistent relationship, keeping ion incidence angles stable across different processing conditions
3Manufacturing precision
If the electrostatic capacitance difference between central and peripheral portions is large, then focus ring function is improved, but impedance matching between target substrate and base deteriorates
Solution Approach 1:
The patent modifies the electrostatic capacitance parameter by introducing a dielectric layer with specific capacitance (0.5 nF to 5 nF). This changes the overall capacitance distribution to reduce the difference between central and peripheral portions to within 10%, maintaining both focus ring function and impedance matching
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 solution effectively suppresses tilting and hole inclination variations during plasma processing by maintaining consistent ion incidence angles, even when bias power is switched between low and high values, thereby improving yield and processing precision.
Implementation Method 1
a dielectric layer, provided between the outer peripheral portion of the electrostatic and the base or the focus ring, having an electrostatic capacitance that reduces a difference between an electrostatic capacitance of the central portion of the electrostatic chuck and an electrostatic capacitance of the outer peripheral portion of the electrostatic chuck
Implementation Method 2
A high frequency bias power for attracting ions in plasma may be applied to the target substrate
Implementation Method 3
a plasma processing apparatus for performing processing such as etching or the like on a target substrate, e.g., a semiconductor wafer, by applying the plasma of a processing gas to the target substrate
Data Source
AI summary
A plasma processing apparatus includes a base, an electrostatic chuck provided on the base, and a dielectric layer. A bias power, whose magnitude is changed during plasma processing on a target substrate, is applied to the base. The electrostatic chuck has a central portion on which the target substrate is mounted and an outer peripheral portion on which a focus ring is mounted to surround the target substrate. The dielectric layer is provided between the outer peripheral portion of the electrostatic and the base or the focus ring and has an electrostatic capacitance that reduces a difference between an electrostatic capacitance of the central portion of the electrostatic chuck and an electrostatic capacitance of the outer peripheral portion of the electrostatic chuck.