Multi-Zone Platen Temperature Control for Etch Uniformity
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Solution Overview
Problem
Achieving uniform etch rate across a workpiece scanned by a ribbon ion beam is challenging due to radial and linear non-uniformities, which are exacerbated by temperature variations and the interface between the workpiece and holder, making it difficult to maintain the desired etch rate within 3-5% (3 sigma value) across the entire surface.
Innovation Solution
A semiconductor processing system with a workpiece holder featuring independently controlled thermal zones, including an inner zone and concentric rings divided into multiple outer zones, allows for separate temperature control of different regions to compensate for both radial and linear etch rate non-uniformities, using a thermal controller to adjust the temperature profile based on the workpiece type and etching species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a ribbon ion beam is used for etching, then productivity is improved through scanning capability, but manufacturing precision deteriorates due to radial and linear etch rate non-uniformity
Solution Approach 1:
The workpiece holder is divided into multiple independently controlled thermal zones (central zone, intermediate zones, outer zones) that can be maintained at different temperatures to compensate for spatial variations in etch rate, thereby achieving uniform etching across the workpiece surface while maintaining high productivity through ribbon ion beam scanning
2Productivity
If the workpiece is scanned through the ribbon ion beam, then productivity is improved, but manufacturing precision deteriorates due to linear non-uniformity along the scan direction
Solution Approach 1:
The thermal zones are positioned and controlled to specifically address linear non-uniformity along the scan direction, with intermediate zones compensating for etch rate variations in the translated direction, enabling uniform etching while maintaining scanning-based high productivity
3Manufacturing precision
If the outer edge of the workpiece is maintained at a different temperature than the center, then manufacturing precision is improved by compensating for radial non-uniformity, but device complexity increases due to multiple thermal zones
Solution Approach 1:
The workpiece holder is segmented into multiple thermal zones with independent temperature control, allowing each zone to be optimized for its specific spatial location and etch rate characteristics, thereby achieving uniform radial etching while managing the complexity through modular zone design
Solution Approach 2:
The temperatures of different thermal zones are adjusted as control parameters to compensate for radial non-uniformity in etch rate, with outer zones maintained at different temperatures than the central zone to achieve uniform etching across the workpiece surface
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 system effectively reduces etch rate non-uniformity, achieving a 3 sigma value of 3% or less by precisely managing temperature across the workpiece, thereby improving etch rate uniformity and adaptability to various etching species.
Implementation Method 1
a heating element is embedded in the inner thermal zone and each outer thermal zone
Implementation Method 2
The present workpiece holder comprises a plurality of independently controlled thermal zones to compensate for both radial and linear etch rate non-uniformity
Data Source
AI summary
A system and method for etching workpieces in a uniform manner are disclosed. The system includes a semiconductor processing system that generates a ribbon ion beam, and a workpiece holder that scans the workpiece through the ribbon ion beam. The workpiece holder includes a plurality of independently controlled thermal zones so that the temperature of different regions of the workpiece may be separately controlled. In certain embodiments, etch rate uniformity may be a function of distance from the center of the workpiece, also referred to as radial non-uniformity. Further, when the workpiece is scanned, there may also be etch rate uniformity issues in the translated direction, referred to as linear non-uniformity. The present workpiece holder comprises a plurality of independently controlled thermal zones to compensate for both radial and linear etch rate non-uniformity.