End Effector Thermocouple for Wafer Thermal Stress Reduction
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Solution Overview
Problem
Conventional ion implantation systems face issues with thermal stress, warpage, and cracking of workpieces due to rapid heating and thermal non-uniformities when a cool workpiece is placed on a heated chuck, particularly in high-temperature processes like hot implants.
Innovation Solution
A system with a workpiece transfer apparatus equipped with temperature sensors to measure the workpiece's temperature before placement on a heated support, allowing controlled preheating and radiative heating to minimize thermal shock, and a controller to manage the workpiece's distance from the heated chuck based on measured temperatures, ensuring uniform heating and reducing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cool workpiece is placed directly on a heated chuck to achieve high process temperature, then heating efficiency is improved, but thermal stress and warpage increase due to rapid heating and thermal non-uniformities
Solution Approach 1:
The system performs preliminary heating of the workpiece using a radiant heater before the workpiece contacts the heated chuck. This pre-heating action reduces the temperature differential between the workpiece and chuck, preventing thermal shock and warpage when the workpiece is subsequently placed on the chuck surface.
Solution Approach 2:
The patent introduces a radiant heater as an intermediary heating device between the workpiece and the heated chuck. This intermediary provides controlled thermal energy to the workpiece before contact, mediating the thermal transition and avoiding direct thermal shock from the high-temperature chuck surface.
2Speed
If a cool workpiece is placed on a heated chuck to achieve process temperature, then heating speed is improved, but thermal non-uniformities across the workpiece increase leading to stress and breakage
Solution Approach 1:
The system applies preliminary radiant heating to the workpiece before chuck contact to establish more uniform initial temperature distribution. This preliminary action ensures that when the workpiece contacts the heated chuck, thermal non-uniformities are minimized while maintaining efficient heating speed.
Solution Approach 2:
The radiant heater provides localized pre-heating to specific areas of the workpiece surface before chuck contact. This local quality approach ensures uniform temperature distribution across the workpiece, particularly addressing edge and center temperature differences that would otherwise cause thermal stress.
3Productivity
If the workpiece is heated rapidly to achieve high temperature implantation, then process efficiency is improved, but warpage and cracking occur due to thermal expansion constraints
Solution Approach 1:
The system performs preliminary radiant heating to gradually warm the workpiece before chuck contact, allowing controlled thermal expansion. This preliminary action maintains implantation throughput by enabling rapid subsequent heating while preventing warpage and cracking through staged thermal management.
Solution Approach 2:
The system changes the heating parameters by introducing a two-stage heating process: initial radiant heating at controlled rate followed by chuck heating. This parameter change allows the workpiece to thermally expand progressively, preventing structural failure while maintaining process efficiency.
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 enables precise temperature control, reducing the risk of warpage, cracking, and thermal stress, while improving heating uniformity and throughput by allowing the workpiece to thermally expand before contact with the heated chuck.
Implementation Method 1
a thermocouple or other temperature sensor embedded in the end effector and configured to contact the workpiece backside
Implementation Method 2
a heated apparatus configured to be selectively heated to the predetermined temperature, and is configured to radiate heat from the support surface
Implementation Method 3
the workpiece thermally expands or grows with respect to the clamping surface due to the increase in temperature
Data Source
AI summary
A workpiece processing system and method provides an end effector coupled to a workpiece transfer apparatus. The end effector has support members for selectively contacting and supporting a workpiece. One or more temperature sensors are coupled to the support members and are configured to contact a backside of the workpiece to measure and define one or more measured temperatures of the workpiece. A heated chuck has a support surface at a predetermined temperature, and is configured to radiate heat from the support surface. A controller control the workpiece transfer apparatus to selectively support the workpiece at a predetermined distance from the support surface of the heated chuck to radiatively heat the workpiece, and to selectively transfer the workpiece from the end effector to the support surface of the heated chuck based, at least in part, on the one or more measured temperatures.