Radiative Substrate Holder for Uniform Wafer Temperature
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Solution Overview
Problem
Substrate processing in microelectronic devices often results in uneven heating due to localized heating techniques, leading to temperature nonuniformity and defects, which existing cooling methods like liquid cooling and convective cooling struggle to address effectively, especially in scanning processes where substrate holders with limited contact areas exacerbate cross-wafer and wafer-to-wafer temperature variations.
Innovation Solution
A method and apparatus for radiative cooling of substrates during processing, where the substrate holder is heated to balance heat transfer by radiating thermal energy, maintaining a steady temperature through the use of a substrate holder with a higher emissivity material to enhance radiative heat dissipation, eliminating the need for liquid cooling and convective cooling mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If localized scanning techniques are used to process a selected portion of the substrate, then processing efficiency is improved, but temperature nonuniformity across the substrate surface worsens
Solution Approach 1:
The substrate holder is designed with non-uniform emissivity distribution, where different regions have different emissivity values. The region corresponding to the processed area has higher emissivity for enhanced cooling, while other regions have lower emissivity. This local quality variation enables targeted cooling of the processed region without affecting other areas, thereby maintaining temperature uniformity across the entire substrate surface while preserving the efficiency benefits of localized scanning processing.
2Device complexity
If substrate holders with limited contact areas are used, then device complexity is reduced, but cross-wafer and wafer-to-wafer temperature variations worsen
Solution Approach 1:
The invention replaces complex mechanical cooling systems (such as liquid cooling channels, contact cooling mechanisms) with a radiative cooling system. The substrate holder incorporates materials with controlled emissivity properties that enable passive radiative heat transfer. This substitution eliminates the need for complex cooling infrastructure while achieving superior temperature uniformity through thermal radiation physics, thereby reducing device complexity while improving temperature control.
3Temperature
If high emissivity material is used on the substrate holder surface, then radiative cooling effectiveness is improved, but heat absorption from processing sources worsens
Solution Approach 1:
The substrate holder employs spatially varying emissivity where the upper surface (exposed to processing sources) has lower emissivity to minimize heat absorption, while the lower surface or specific regional zones have higher emissivity to maximize radiative cooling effectiveness. This local quality differentiation allows the system to simultaneously reduce harmful heat absorption from processing sources and enhance cooling performance in the same component.
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 approach achieves improved cross-wafer and wafer-to-wafer temperature uniformity, increased throughput, and reduced adsorption of compounds like sulfur, allowing for more consistent processing outcomes without the complexity of additional cooling systems.
Implementation Method 1
cooling the substrate while processing the substrate by radiating heat from the substrate holder
Implementation Method 2
maintaining the substrate at the steady temperature by heating the substrate holder such that heat transferred from the substrate by radiating heat from the substrate holder substantially balances heat transferred to the substrate by processing the substrate and by heating the substrate holder
Data Source
AI summary
A method of cooling a substrate during processing includes processing a substrate supported by a substrate holder where the substrate is heated by the processing, cooling the substrate while processing the substrate by radiating heat from the substrate holder, and maintaining the substrate at a steady temperature to within a tolerance while processing the substrate. The substrate is maintained at the steady temperature by heating the substrate holder such that heat transferred from the substrate by radiating heat from the substrate holder substantially balances heat transferred to the substrate by processing the substrate and by heating the substrate holder.