Phase-Change Hot Plate for Stable Wafer Bake Temperature
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Solution Overview
Problem
Existing hot plates in semiconductor manufacturing struggle to maintain precise temperature control during bake steps, particularly when a cold wafer is introduced, leading to temperature drops and increased heating time to reach the desired temperature.
Innovation Solution
A hot plate with a housing structure containing a non-eutectic alloy, such as Bismuth, Lead, Tin, and Cadmium, which has a melting temperature range, allowing the heating element to transition the alloy from a solid to a liquid state, providing high specific heat capacity and minimizing temperature drops when a cold wafer is placed on it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional hot plate is used to heat a wafer, then the hot plate can reach the desired temperature, but the temperature drops significantly when a cold wafer is introduced and takes a long time to stabilize
Solution Approach 1:
The patent changes the physical state parameter of the thermal mass material by utilizing its phase transition from solid to liquid at the target temperature. This phase change absorbs significant latent heat, creating a thermal buffer that stabilizes the hot plate temperature when cold wafers are introduced, thereby reducing temperature fluctuations and stabilization time
Solution Approach 2:
The patent employs a material that undergoes phase transition (melting) at the desired operating temperature range. During the phase transition, the material absorbs latent heat of fusion, which acts as a thermal buffer to maintain stable temperature despite the introduction of cold wafers, directly addressing the temperature stability and time-to-stabilize contradiction
2Temperature
If the hot plate uses a simple heating element without phase-change material, then the device complexity is low, but the temperature control precision deteriorates during wafer loading
Solution Approach 1:
The patent modifies the thermal properties of the hot plate by incorporating a phase-change material whose melting point matches the target operating temperature. This material dynamically adjusts its heat absorption capacity based on temperature, providing passive thermal regulation that improves temperature control precision without requiring complex active control systems
Solution Approach 2:
The patent utilizes the phase transition phenomenon of a carefully selected material to provide automatic temperature regulation. As the material melts at the target temperature, it absorbs excess heat, preventing overheating and maintaining precision temperature control during wafer loading events without adding complex control mechanisms
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
The hot plate effectively maintains the desired temperature with minimal temperature fluctuation upon wafer introduction, reducing the time required to stabilize the temperature and ensuring consistent semiconductor processing conditions.
Implementation Method 1
The heating element is configured to transition the alloy from a solid state to a liquid state at a set temperature between the melting temperature range
Implementation Method 2
The alloy has a melting temperature range... providing high specific heat capacity
Data Source
AI summary
According to an embodiment, an apparatus for a hot plate apparatus is disclosed. The hot plate apparatus includes a housing structure, an alloy, and a heating element. The housing structure includes an outer shell surrounding a cavity. The alloy is disposed of within the cavity. The alloy has a melting temperature range. The heating element is configured to transition the alloy from a solid state to a liquid state at a set temperature between the melting temperature range.