Hot Plate Temperature Control for Resist Film Uniformity
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Solution Overview
Problem
In semiconductor wafer processing, variations in temperature increase times across different heat processing units lead to inconsistencies in device quality due to individual differences in heater capacity and component parts, affecting the thermal history of wafers.
Innovation Solution
A temperature control method that adjusts the target temperature by acquiring adjustment data to optimize the reaching time for each substrate, ensuring uniform temperature stabilization across multiple heat processing units, using a temperature controller that stores and applies this data to maintain a common target reaching time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plurality of heat processing units are used to process multiple wafers, then productivity is improved, but variations in temperature increase times occur due to individual differences in heater capacity and component parts
Solution Approach 1:
The patent adjusts the target temperature parameter dynamically based on the measured temperature increase time for each heat processing unit. By changing the target temperature to compensate for individual unit variations, the system achieves consistent temperature increase times across all units, resolving the contradiction between using multiple units for productivity and maintaining precision.
Solution Approach 2:
The system measures the actual temperature increase time for each heat processing unit and uses this feedback information to adjust the target temperature. This closed-loop control ensures that despite individual differences in heater capacity and components, all units achieve uniform temperature increase times, enabling both high productivity and manufacturing precision.
2Manufacturing precision
If the target temperature is adjusted to optimize reaching time, then manufacturing precision is improved, but the system complexity increases due to additional control mechanisms
Solution Approach 1:
The patent modifies only the target temperature parameter, which is a simple control variable, to achieve optimization of reaching time. This approach improves manufacturing precision without requiring complex control mechanisms, as it leverages the existing temperature control system's ability to respond to target temperature changes.
Solution Approach 2:
Each heat processing unit independently measures its own temperature increase time and adjusts its own target temperature based on this self-diagnosis. This self-service approach eliminates the need for a centralized complex control system, as each unit autonomously optimizes its performance.
3Ease of manufacture
If individual heat processing units have different heater capacities and component parts, then ease of manufacture is improved, but temperature increase times vary leading to quality variations
Solution Approach 1:
The patent compensates for the variations in heater capacity and component parts by adjusting the target temperature parameter for each unit. This allows different units with varying hardware characteristics to achieve consistent temperature increase times and uniform thermal histories, maintaining quality consistency despite ease of manufacture with varied components.
Solution Approach 2:
The system applies individualized target temperature adjustments to each heat processing unit based on its specific characteristics. This local quality approach allows each unit to be optimized for its own hardware variations, enabling diverse components to work together harmoniously to produce uniform results.
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 reduces variations in device quality by ensuring consistent temperature stabilization across all heat processing units, even with differing heater capacities and component parts, thereby improving the uniformity of the thermal history of wafers.
Implementation Method 1
a hot plate, which is provided with a heater and a temperature sensor built therein
Implementation Method 2
a temperature sensor built therein and is controlled to be at a target temperature
Implementation Method 3
when a semiconductor wafer is placed on a hot plate adjusted at a target temperature, the semiconductor wafer takes heat from the hot plate
Data Source
AI summary
A temperature control method is used for controlling a temperature of a hot plate, so that a measured temperature of the hot plate conforms to a target temperature thereof, in a heat processing apparatus for performing a heat process on a substrate placed on the hot plate, which is used in a coating/developing system for applying a resist coating onto the substrate to form a resist film and then performing development on the resist film after light exposure. The method includes acquiring adjustment data necessary for adjusting a reaching time defined by a time period for increasing the temperature of the substrate from a first temperature around an initial temperature to a second temperature around the target temperature; and adjusting the target temperature by use of the adjustment data thus acquired, after starting the process on the substrate.