Susceptor Temperature Control for Semiconductor Wafer Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermal processing methods for semiconductor wafers face challenges in achieving uniform temperature history across multiple wafers due to temperature differences between the susceptor and the wafer, leading to potential warpage and inefficiencies, particularly when starting a new lot without preheating the susceptor, which requires dummy running to stabilize temperatures.
Innovation Solution
A thermal processing method and apparatus that measures the susceptor temperature before processing and adjusts heating based on these measurements to ensure uniform temperature across all wafers, eliminating the need for dummy running by using a control unit to manage light irradiation from both halogen and flash lamps, ensuring accurate heating control for each region of the susceptor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the susceptor is not preheated before processing, then the apparatus can start processing immediately, but the temperature history becomes non-uniform across multiple wafers causing warpage
Solution Approach 1:
The patent applies preliminary action by measuring the susceptor temperature before processing begins and preheating the susceptor to an appropriate temperature. This ensures that when wafers are processed, the susceptor is already at the correct temperature, eliminating temperature history differences and preventing wafer warpage while allowing immediate processing without dummy runs.
Solution Approach 2:
The patent implements feedback by measuring the susceptor temperature using a temperature measurement unit and using this measurement to control the heating process. The control unit adjusts the heating based on the measured temperature to achieve uniform temperature history across all wafers in a lot, resolving the contradiction between quick startup and temperature uniformity.
2Manufacturing precision
If dummy running is performed to stabilize susceptor temperature, then uniform temperature history is achieved, but processing time increases
Solution Approach 1:
The patent eliminates dummy running by performing preliminary temperature measurement and controlled preheating of the susceptor before actual processing. This allows the susceptor to reach the appropriate temperature in advance, achieving uniform temperature history without the time loss associated with processing dummy wafers.
Solution Approach 2:
The system performs self-service by automatically measuring its own susceptor temperature and adjusting its heating accordingly. This self-regulation eliminates the need for dummy running while ensuring uniform temperature history, reducing processing time while maintaining precision.
3Ease of operation
If the susceptor temperature varies between wafers, then processing can be performed without preheating, but wafer warpage occurs
Solution Approach 1:
The patent uses feedback control by measuring the susceptor temperature with a temperature measurement unit and using this information to control the heating process. This ensures the susceptor maintains a stable, uniform temperature across all wafers, preventing wafer warpage while keeping the operation simple through automated control.
Solution Approach 2:
The patent changes the temperature parameter of the susceptor from variable to controlled and uniform by implementing measurement and heating control based on actual temperature readings. This stabilizes the susceptor temperature parameter, preventing wafer shape changes while maintaining ease of operation through automated parameter management.
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 uniform temperature history for all substrates in a lot without dummy running, preventing warpage and enhancing operational efficiency by ensuring consistent susceptor temperatures before processing begins, thus improving the thermal processing of semiconductor wafers.
Implementation Method 1
irradiating the substrate placed on the susceptor with light... the semiconductor wafer is preheated to a certain temperature by, for example, a halogen lamp
Implementation Method 2
rising temperature only at the surface of a semiconductor wafer in which impurities are implanted, in an extremely short time (several milliseconds or less) by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp
Implementation Method 3
measuring the temperature of the susceptor before the first substrate of a lot is transferred into the chamber
Data Source
AI summary
A susceptor is preheated through light irradiation by a halogen lamp before the first semiconductor wafer of a lot as a processing target is transferred into a chamber. The temperature of the susceptor is measured by a radiation thermometer. A control unit is configured to control the output of the halogen lamp so that the temperature of the susceptor reaches a stable temperature based on a result of the measurement of the temperature of the susceptor by the radiation thermometer. The stable temperature of the susceptor is the temperature of the susceptor when the temperature of the susceptor is risen to a constant temperature by continuously performing light irradiation heating on a plurality of semiconductor wafers in the chamber without heating the susceptor.