Bake Plate Temperature Control via Face Plate Feedback
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Solution Overview
Problem
The semiconductor industry faces challenges in maintaining process uniformity and repeatability due to variations in temperature control during lithography processing, particularly in track lithography tools, where conventional methods like optical pyrometers are insufficiently repeatable and direct wafer contact can generate particles.
Innovation Solution
A method and system for temperature control of semiconductor substrates between a bake plate and a face plate, where the bake plate temperature is adjusted based on measured face plate temperature differences, using a controller to modify heating element power and maintain steady-state wafer temperature by compensating for face plate temperature drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical pyrometers are used to measure wafer temperature, then non-contact temperature measurement is achieved, but measurement repeatability is insufficient
Solution Approach 1:
The patent introduces the face plate as an intermediary object to indirectly measure wafer temperature. Instead of directly measuring the wafer (which causes contact particles or insufficient repeatability), the system measures the face plate temperature that is in thermal contact with the wafer, providing a reliable proxy measurement that resolves the contradiction between non-contact requirement and measurement repeatability
Solution Approach 2:
The system implements a feedback control loop where face plate temperature measurements are continuously monitored and used to adjust the bake plate temperature. This closed-loop feedback mechanism ensures measurement repeatability by using consistent face plate readings to drive temperature adjustments, resolving the reliability issue with optical pyrometers
2Measurement precision
If direct wafer contact is used for temperature measurement, then temperature data is obtained, but particle generation occurs
Solution Approach 1:
The face plate serves as an intermediary between the temperature measurement system and the wafer. By measuring the face plate temperature instead of directly contacting the wafer, the system obtains the necessary temperature data without generating particles from direct wafer contact, effectively resolving this contradiction
Solution Approach 2:
The patent replaces direct mechanical contact measurement with an indirect thermal field measurement approach. Instead of physically touching the wafer with sensors, the system measures the face plate temperature which thermally couples to the wafer, substituting mechanical contact with thermal field sensing to eliminate particle generation
3Stability of the object's composition
If bake plate temperature is increased to compensate for face plate temperature loss, then wafer temperature stability is improved, but energy consumption increases
Solution Approach 1:
The system uses feedback control to adjust bake plate temperature based on actual face plate temperature measurements. Rather than continuously increasing temperature, the system makes precise, targeted adjustments only when and where needed to maintain wafer temperature stability, optimizing energy consumption while achieving the stability goal
Solution Approach 2:
The patent implements dynamic temperature adjustment where the bake plate temperature is continuously adapted based on real-time face plate temperature readings. This dynamic control allows the system to maintain wafer temperature stability by making incremental adjustments rather than sustained high-temperature operation, reducing overall energy consumption
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 reduces process variability, eliminates particle generation from direct wafer contact, and achieves repeatable temperature control, ensuring consistent wafer processing by accurately monitoring and adjusting the bake plate temperature in response to face plate temperature changes.
Implementation Method 1
adjusting bake plate temperature by modifying a temperature control signal provided to one or more heating elements associated with the bake plate
Implementation Method 2
a bake plate on which a wafer substrate can be loaded opposing a face plate. The loaded wafer substrate usually is supported on a plurality of proximity pins forming a thermal conductive air gap
Implementation Method 3
measuring a face plate temperature associated with the face plate... determining a difference between the face plate temperature and a predetermined temperature... modifying the temperature control signal in response to the determined difference
Data Source
AI summary
A method of operating a bake plate disposed in a semiconductor processing chamber having a face plate opposing the bake plate includes providing a temperature control signal to the bake plate and measuring a face plate temperature associated with the face plate. The method also includes determining a difference between the face plate temperature and a predetermined temperature and modifying the temperature control signal provided to the bake plate in response to the determined difference.