Dynamic Backside Gas Control for Wafer Temperature Uniformity
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Solution Overview
Problem
Conventional semiconductor manufacturing processes face challenges in achieving uniformity across substrates during etching due to spatial variations in plasma density, process chemistry, and substrate temperature, which affect feature critical dimensions and side-wall angles, leading to non-uniform yields of high-performance devices.
Innovation Solution
Dynamic control of backside gas pressure across a substrate holder to vary thermal conductivity between the substrate and the holder, allowing for real-time adjustment of substrate temperature and temperature distribution to compensate for non-uniformities in plasma density and chemistry, thereby improving process uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional static backside gas supply is used, then substrate temperature control is simple, but process uniformity across the substrate deteriorates due to spatial variations in plasma density and chemistry
Solution Approach 1:
The backside gas supply system is divided into multiple independently controllable zones (e.g., center zone and edge zone) with separate gas supply lines and control valves. This segmentation allows different gas pressures to be applied to different regions of the substrate backside, enabling localized temperature control to compensate for spatial variations in plasma density and chemistry, thereby improving process uniformity without requiring complete system redesign
Solution Approach 2:
The gas supply system transitions from a static configuration to a dynamic one where gas pressures in different zones can be independently adjusted during the etching process. This dynamic control enables real-time compensation for process non-uniformities by varying the thermal conductivity between the substrate and holder in different regions, improving manufacturing precision while maintaining manageable system complexity through electronic control
2Temperature
If backside gas pressure is increased to improve thermal conductivity, then substrate temperature uniformity improves, but gas consumption and system complexity increase
Solution Approach 1:
Different gas pressures are applied to different zones of the substrate backside based on local temperature requirements. For example, the edge zone may receive higher gas pressure to increase thermal conductivity and reduce edge heating, while the center zone maintains lower pressure. This localized approach achieves substrate temperature uniformity without proportionally increasing overall gas consumption, as each zone receives only the gas flow necessary for its specific thermal control needs
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 effectively enhances the uniformity of etching results by dynamically managing substrate temperature, offsetting non-uniform effects of process conditions and improving the consistency of critical dimensions and side-wall angles across the substrate.
Implementation Method 1
backside gas pressure is varied across the substrate holder to control substrate conditions and condition variation or uniformity across the substrate during processing
Implementation Method 2
vary the thermal conductivity between the substrate and the substrate holder, allowing for real-time adjustment of substrate temperature and temperature distribution
Data Source
AI summary
A method and apparatus are provided to control the radial or non-radial temperature distribution across a substrate during processing to compensate for non-uniform effects, including radial and angular non-uniformities arising from system variations, or process variations, or both. The temperature is controlled, preferably dynamically, by flowing backside gas differently across different areas on a wafer supporting chuck to vary heat conduction across the wafer. Backside gas flow, of helium, for example, is dynamically varied across the chuck to control the uniformity of processing of the wafer. Ports in the support are grouped, and gas to or from the groups is separately controlled by different valves responsive to a controller that controls gas pressure in each of the areas to spatially and preferably dynamically control wafer temperature to compensate for system and process non-uniformities.