Pre-cooling Photolithographic Substrate for Plasma Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional plasma etch processes for photolithographic substrates lack effective temperature control, leading to temperature increases during processing, which can result in imperfections and degrade the quality of the photomask, especially for dielectric substrates like quartz, where mechanical and electrostatic clamping methods have limitations.
Innovation Solution
A method involving pre-cooling the photolithographic substrate using a heat transfer fluid to a target temperature before plasma processing, allowing the substrate to be cooled to below zero degrees Celsius, and then transferring it to a plasma chamber for etching, where the temperature is maintained below initial levels to prevent overheating during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used for photolithographic substrates, then the etching process can be completed, but the substrate temperature increases during processing leading to thermal stress and quality degradation
Solution Approach 1:
The substrate is pre-cooled to a target temperature (e.g., -30°C to -40°C) before entering the plasma etch process. This preliminary cooling action compensates for the temperature rise that will occur during etching, allowing the substrate to maintain an optimal temperature range throughout the process and prevent thermal stress and quality degradation
Solution Approach 2:
The substrate temperature parameter is actively changed and controlled by introducing a heat transfer fluid (such as nitrogen or helium gas) at controlled rates (e.g., 1 Torr per second) to achieve desired cooling effects. The temperature is maintained within specific ranges (e.g., below 0°C to -40°C) to optimize etching precision while preventing thermal damage
2Reliability
If mechanical or electrostatic clamping methods are used to hold the substrate, then the substrate can be secured during processing, but these methods have limitations especially for dielectric substrates like quartz
Solution Approach 1:
Mechanical clamping systems are replaced with a gas-based heat transfer fluid system that can effectively cool and hold dielectric substrates like quartz without the limitations of mechanical or electrostatic methods. The heat transfer fluid (e.g., nitrogen or helium) provides reliable thermal management for substrates that are difficult to clamp mechanically or electrostatically
Solution Approach 2:
A heat transfer fluid acts as an intermediary between the cooling system and the photolithographic substrate. This intermediary medium enables effective thermal management and substrate control without requiring direct mechanical or electrostatic contact, thereby improving compatibility with dielectric materials like quartz while maintaining reliable substrate holding
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 method effectively controls the substrate temperature, reducing thermal stress and maintaining the quality of the photomask by preventing excessive heating during plasma etching, thus improving the precision and accuracy of the etching process.
Implementation Method 1
introducing a heat transfer fluid into the chamber to cool the photolithographic substrate to a target temperature
Implementation Method 2
subjecting the cooled photolithographic substrate to a plasma process before the temperature of the cooled photolithographic substrate reaches its initial temperature
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a method for processing a photolithographic substrate, comprising the placement of the photolithographic substrate on a support member in a chamber wherein the photolithographic substrate has an initial temperature of about zero degrees Celsius to about fifty degrees Celsius. A heat transfer fluid is introduced into the chamber to cool the photolithographic substrate to a target temperature of less than about zero degrees Celsius to less than about minus forty degrees Celsius. The cooled photolithographic substrate is subjected to a plasma process before the temperature of the cooled photolithographic substrate reaches the initial temperature.