Localized Etch Back Using Temperature Zones for Wafer Planarization
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Solution Overview
Problem
Existing etch back procedures in semiconductor manufacturing 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 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, with each zone having independently controllable etch parameters. This allows different regions to be etched at different rates to compensate for local thickness variations, achieving uniform removal rates across the entire wafer despite material non-uniformities and random etch condition variations.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting etch process parameters (such as power, pressure, gas flow) for different zones during the etch back process. By modifying these parameters in real-time based on measured wafer topography, the system achieves uniform removal rates and compensates for random variations in etch conditions and material non-uniformities.
2Manufacturing precision
If etch back is performed to thin wafers, then quantum efficiency and package fit are improved, but thickness variations increase
Solution Approach 1:
The patent applies preliminary action by performing a measurement step before the etch back process to map the initial wafer topography and thickness variations. This pre-characterization data is used to plan and optimize the subsequent etch back process, allowing the system to achieve uniform thickness reduction while maintaining high productivity through efficient process planning.
Solution Approach 2:
The patent implements feedback by using real-time or post-etch measurement data to verify thickness uniformity and adjust process parameters for subsequent wafers or re-etch cycles. This closed-loop approach ensures that thickness variations are minimized while maintaining etch back process efficiency through data-driven process optimization.
3Manufacturing precision
If uniform etching is achieved through multiple measurements and temperature adjustments, then thickness variation is reduced to less than 0.3 microns, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the wafer surface into multiple temperature control zones, each with independent temperature control. This segmentation allows localized temperature adjustments to compensate for edge effects and non-uniform heating, achieving uniform etching across the entire wafer while managing system complexity through modular zone control.
Solution Approach 2:
The patent uses temperature as an intermediary parameter to control etch rate uniformity. By introducing temperature control zones as intermediaries between the plasma source and the wafer, the system can indirectly regulate etch rates in different regions, achieving uniform thickness removal while simplifying the direct control of etch parameters across the entire wafer 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 achieves more uniform removal rates and post-etch topography, reducing thickness variations to less than 0.3 microns and achieving a smooth, level surface, with etch rate uniformity of less than 0.04%.
Implementation Method 1
a plasma source configured to generate ions to etch the work piece
Implementation Method 2
The controller is configured to individually heat or cool the plurality of temperature control elements to heat or cool the plurality of temperature control zones
Implementation Method 3
The controller is configured to individually heat or cool the plurality of temperature control elements 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.