Loadlock Heat Transfer via Dynamic Gas Pressure Control
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Solution Overview
Problem
Current semiconductor wafer processing systems face challenges in throughput due to variable heat transfer rates during heating and cooling cycles, which can lead to wafer distortion and excessive processing times, as they typically operate at a single pressure and geometry, compromising between thermal stress and cycle duration.
Innovation Solution
The method involves varying the heat transfer coefficient by manipulating gas pressure in the loadlock chamber to control the rate of heat transfer, allowing for aggressive cooling or heating throughout the cycle while maintaining acceptable temperature change rates, and moving the wafer closer to the heat source to increase temperature change at later stages, thereby improving overall heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer is moved closer to the heating or cooling source to increase heat transfer rate, then the overall processing time is reduced, but thermal stress and wafer distortion increase
Solution Approach 1:
The patent applies dynamics by making the heat transfer coefficient variable throughout the processing cycle. The system dynamically adjusts the heat transfer coefficient to be higher at the beginning and end of the cycle (when the wafer is closer to the source) and lower in the middle portion, allowing aggressive heat transfer when geometric constraints permit while avoiding thermal stress when the wafer is closer to the heating/cooling source
Solution Approach 2:
The patent changes the parameter of heat transfer coefficient throughout the processing cycle. By varying this parameter based on the cycle stage, the system achieves high heat transfer rates when the wafer is positioned closer to the source while maintaining acceptable thermal stress levels, thus resolving the contradiction between productivity and reliability
2Device complexity
If a single pressure and geometry are used in the loadlock, then the system design is simplified, but the heat transfer rate varies excessively causing wafer distortion
Solution Approach 1:
Rather than using complex variable geometry, the patent applies dynamics by varying the heat transfer coefficient through pressure control. This dynamic adjustment of the heat transfer coefficient compensates for the fixed geometry, maintaining manufacturing precision without increasing device complexity
Solution Approach 2:
The patent changes the pressure parameter throughout the cycle to modulate the heat transfer coefficient. This parameter change approach allows the system to maintain consistent heat transfer rates and prevent wafer distortion while keeping the physical geometry simple and fixed
3Productivity
If aggressive cooling or heating is applied throughout the cycle, then processing time is reduced, but thermal stress causes wafer breakage
Solution Approach 1:
The patent applies dynamics by making the heat transfer coefficient time-dependent. Aggressive heat transfer is applied at the beginning and end of the cycle when thermal stress is lower, while milder conditions are used in the middle portion when the wafer is more vulnerable, thus achieving high productivity without compromising wafer integrity
Solution Approach 2:
The patent uses periodic action by applying different heat transfer coefficients at different stages of the cycle. The heat transfer coefficient is increased during periods when the wafer can tolerate aggressive treatment and reduced during periods when the wafer is more susceptible to thermal stress, resolving the contradiction between productivity and strength
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 wafer processing time by maintaining a consistent heat transfer rate throughout the cycle, avoiding thermal stress and distortion, and allows for more aggressive cooling or heating without risking wafer breakage, thus enhancing the overall throughput of the semiconductor fabrication process.
Implementation Method 1
heat transfer coefficient of a heat transfer gas
Implementation Method 2
heat transfer gas in the loadlock
Implementation Method 3
positioned within about 2 inches of the heating element
Data Source
AI summary
Methods that increase the overall rate of heat transfer between a substrate and a heat sink or source, e.g., in a loadlock are provided. According to various embodiments, the methods involve varying the heat transfer coefficient of a heat transfer gas in the loadlock or other chamber. The heat transfer coefficient is varied to reduce the time-dependent variation of the rate of heat transfer. As a result, the overall rate of heat transfer is improved. In certain embodiments, the methods involve varying the gas pressure of a chamber in order to affect the rate of heat transfer to a wafer within a system. By manipulating the gas pressure accordingly, the rate of heat transfer is controlled throughout the heating or cooling cycle.