Localized Etch Back Using Temperature Zones for Wafer Planarity
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Solution Overview
Problem
Existing etch back procedures in semiconductor processing 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 by heating or cooling specific sites based on their measured heights, ensuring uniform etching across the semiconductor wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etch back procedures are used, then the etching process can be completed, but the removal rate is non-uniform 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, with each zone having independently controllable etch parameters. This allows different regions to be etched at different rates to compensate for local variations in material thickness and etch conditions, achieving uniform overall removal despite inherent non-uniformities
Solution Approach 2:
The patent changes etch parameters (such as power, pressure, gas flow, or temperature) locally across different zones of the wafer during the etch back process. By dynamically adjusting these parameters based on real-time measurements of wafer topography, the system compensates for random variations in etch conditions and material non-uniformities, achieving consistent removal rates
2Manufacturing precision
If etch back is performed to thin the wafer, then quantum efficiency and package fit are improved, but thickness variations increase
Solution Approach 1:
The patent performs preliminary measurements of wafer topography before the etch back process using optical or mechanical sensing. Based on these pre-etch measurements, the system pre-configures the etch parameters for different zones, allowing proactive compensation for thickness variations rather than reactive adjustment during etching
Solution Approach 2:
The patent implements a feedback control system where real-time or post-etch measurements of wafer topography are fed back to adjust etch parameters for subsequent processing. This closed-loop control ensures that thickness variations are continuously monitored and corrected, achieving final planarity with thickness variations less than 0.3 microns
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 more uniform removal rates and post-etch topography, reducing thickness variations to less than 0.3 microns and etch rate uniformity to less than 0.04%, significantly improving the planarity and smoothness of the semiconductor substrate.
Implementation Method 1
a plasma source configured to generate ions to etch the work piece
Implementation Method 2
The plurality of temperature control elements are used to heat or cool the plurality of temperature control zones
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.