Workpiece Temperature Control in Ion Implantation
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Solution Overview
Problem
Ion implantation systems face challenges in accurately controlling workpiece temperatures due to the impact of ion beam power, which leads to less stable and less accurate temperature control, especially with higher-powered beams, as conventional thermocouples have slow response times and are not thermally coupled close enough to the workpiece.
Innovation Solution
A system and method that dynamically control the thermal energy delivered to the workpiece by characterizing the ion implantation system, including the use of a heated chuck with embedded heaters, backside gas, and coolant sources, to maintain a desired temperature within +/-5°C, by accounting for the power imparted from the ion beam and using a controller to adjust heating zones and gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional thermocouples are used to measure workpiece temperature, then temperature measurement is possible, but the response time is slow and temperature control accuracy deteriorates
Solution Approach 1:
The patent introduces an optical pyrometer as an intermediary measurement device that measures workpiece temperature through non-contact optical means. The pyrometer measures the spectral radiance of the workpiece and converts it to temperature readings, serving as a mediator between the high-power ion beam environment and the temperature control system. This intermediary approach enables fast, accurate temperature measurement without physical contact that would slow response time.
Solution Approach 2:
The patent replaces the mechanical contact-based thermocouple measurement system with an optical-based pyrometer system. By substituting the mechanical thermal conduction method with optical radiation detection, the system achieves faster response times and higher measurement accuracy while avoiding the thermal mass and response delays inherent in contact thermocouples.
2Productivity
If higher-powered ion beams are used for ion implantation, then processing efficiency is improved, but workpiece temperature stability deteriorates
Solution Approach 1:
The patent implements a closed-loop feedback control system where the optical pyrometer continuously measures workpiece temperature during ion implantation, and the controller dynamically adjusts the ion beam power or duration based on real-time temperature readings. This feedback mechanism enables the system to maintain temperature stability even when using higher-powered ion beams by automatically compensating for excessive heating.
Solution Approach 2:
The patent introduces dynamic control of the ion implantation process by continuously adjusting beam parameters based on real-time temperature measurements. The system transitions from static, pre-programmed implantation sequences to dynamic, adaptive control where beam power, pulse duration, or scanning patterns are modified on-the-fly to maintain optimal workpiece temperature throughout the processing cycle.
3Loss of time
If contact thermocouples are placed on the workpiece for fast temperature measurement, then response time is improved, but system reliability and particle contamination increase
Solution Approach 1:
The optical pyrometer serves as a non-contact intermediary that measures workpiece temperature through optical radiation without physical contact. This eliminates the need for thermocouples to touch the workpiece or be placed in the ion beam path, avoiding particle contamination sources while maintaining fast response times through optical detection methods.
Solution Approach 2:
The patent replaces the mechanical contact thermocouple system with a non-contact optical pyrometer system. This substitution eliminates the mechanical and thermal contact requirements, thereby removing the sources of particle contamination and reliability issues associated with physical thermocouple placement while achieving comparable or superior response times through optical detection.
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 more accurate and stable temperature control of the workpiece during ion implantation, preventing overheating and maintaining precise temperature within the desired range, even with varying ion beam powers, thereby ensuring the quality and integrity of the semiconductor processing.
Implementation Method 1
The heated chuck, for example, comprises one or more heaters embedded therein
Implementation Method 2
a heated chuck configured to selectively secure and selectively heat a workpiece
Implementation Method 3
a thermal energy imparted into the workpiece from the ion beam during the implantation
Implementation Method 4
a coolant source configured to provide a coolant fluid through one or more passages through the heated chuck
Implementation Method 5
a clamping voltage is typically applied between the wafer and the electrode, wherein the wafer is clamped against the chuck surface by electrostatic forces
Data Source
AI summary
A system and method is provided maintaining a temperature of a workpiece during an implantation of ions in an ion implantation system, where the ion implantation system is characterized with a predetermined set of parameters. A heated chuck is provided at a first temperature and heats the workpiece to the first temperature. Ions are implanted into the workpiece concurrent with the heating, and thermal energy is imparted into the workpiece by the ion implantation. A desired temperature of the workpiece is maintained within a desired accuracy during the implantation of ions by selectively heating the workpiece on the heated chuck to a second temperature. The desired temperature is maintained based, at least in part, on the characterization of the ion implantation system. Thermal energy imparted into the workpiece from the implantation is mitigated by the selective heating of the workpiece on the heated chuck at the second temperature.