By-Site Etch Back Using Temperature Zones for Wafer Planarization
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Solution Overview
Problem
Etch back procedures in semiconductor processing often suffer from non-uniform removal rates due to random variations in etch conditions and material non-uniformities, leading to inconsistencies in the thickness and height of etched layers.
Innovation Solution
A system comprising a measurement apparatus and a localized etch back apparatus with temperature control zones and a plasma source, where the etch rates are tailored based on pre-etch surface height measurements to achieve uniform etching across the semiconductor wafer, using either temperature control elements or liquid etchant dispensing for precise etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etch back procedures are used, then material removal is achieved, but non-uniform removal rates occur due to random variations in etch conditions and material non-uniformities
Solution Approach 1:
The patent applies local quality by dividing the etch back process into multiple zones across the wafer surface, where each zone has independently controllable etch parameters. This allows different regions to be etched at different rates to compensate for local thickness variations, achieving uniform overall removal despite initial non-uniformities in the wafer or etch conditions
Solution Approach 2:
The patent changes etch parameters (such as power, gas flow, or temperature) locally across different zones of the wafer during the etch back process. By dynamically adjusting these parameters based on measured thickness variations, the system compensates for random variations in etch conditions and material non-uniformities, achieving consistent removal rates and uniform thickness
2Manufacturing precision
If uniform etch back is achieved through multiple measurements and localized temperature control, then post-etch topography uniformity is significantly improved, but device complexity and process time increase
Solution Approach 1:
The patent segments the wafer surface into multiple zones with independent temperature control elements, allowing localized adjustment of etch rates. This segmentation enables precise control of post-etch topography uniformity by addressing specific regional variations rather than requiring uniform control across the entire wafer, reducing the overall system complexity while maintaining high precision
Solution Approach 2:
The patent performs preliminary measurements of wafer thickness before the etch back process to identify regions requiring compensation. By pre-planning the localized temperature control strategy based on these measurements, the system avoids the need for complex real-time adjustments during etching, thereby reducing device complexity while achieving the desired uniformity
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 achieves a significantly more uniform post-etch topography with a total thickness variation of less than 0.3 microns, improving the uniformity and accuracy of semiconductor wafer thinning.
Implementation Method 1
The plurality of temperature control elements are used to heat or cool the plurality of temperature control zones, respectively, to a first plurality of temperatures, respectively
Implementation Method 2
a plasma source configured to generate ions to etch the work piece
Data Source
AI summary
A work piece is positioned on a work piece support, which includes a plurality of temperature control zones. A pre-etch surface topography is determined by measuring a plurality of pre-etch surface heights or thicknesses at a plurality of sites on the work piece. The plurality of sites correspond to the plurality of temperature control zones on the work piece support. At least a first zone of the temperature control zones is heated or cooled based on the measured plurality of pre-etch surface heights or thicknesses, so that the first zone has a first temperature different from a second temperature of a second zone of the temperature control zones. A dry etch is carried out while the first zone has the first temperature different from the second temperature of the second zone of the temperature control zones.