Substrate Heating Power Distribution for Temperature Control
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Solution Overview
Problem
Existing substrate treatment devices with zone heating apparatuses face challenges in maintaining robust temperature control, especially when parameters such as thermal conductivity of process gases change, leading to inefficiencies in heating power distribution and temperature gradients.
Innovation Solution
A control apparatus that distributes total heating power among zone heating apparatuses using preselectable distribution parameters, ensuring a fixed ratio among zone heating powers, which are freely adjustable based on process conditions, thereby maintaining consistent temperature control without altering distribution parameters during the coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual zone heating apparatuses are controlled independently with multiple temperature sensors, then temperature control precision is improved, but device complexity and control robustness deteriorate due to thermal interference between zones
Solution Approach 1:
The patent merges multiple independent temperature sensors into a single temperature sensor that measures the susceptor temperature. The control apparatus then distributes this single temperature measurement to control multiple zone heating apparatuses, reducing control system complexity while maintaining temperature control precision through centralized measurement and intelligent power distribution.
Solution Approach 2:
The single temperature sensor serves a universal function by providing temperature measurement data that is used to control all zone heating apparatuses simultaneously. The control apparatus acts as a multi-functional element that distributes the temperature control task across multiple heating zones based on a single measurement, eliminating the need for multiple dedicated sensors per zone.
2Reliability
If heating power is distributed among zone heating apparatuses with fixed ratios, then control robustness is improved, but adaptability to changing process conditions deteriorates
Solution Approach 1:
The patent implements dynamic adaptability by allowing the control apparatus to adjust the power distribution ratios among zone heating apparatuses in response to changing process conditions. The system transitions from static fixed ratios to dynamic adjustable ratios, enabling the control loop to maintain robustness while adapting to variations in thermal conductivity of process gases and other process parameters.
Solution Approach 2:
The control apparatus changes the distribution parameters (power ratios) among zone heating apparatuses based on detected process condition changes. When thermal conductivity or other process parameters change, the control apparatus adjusts the heating power distribution to compensate, maintaining temperature control robustness while adapting to new conditions.
3Measurement precision
If multiple temperature sensors are used for each heating zone, then temperature measurement accuracy is improved, but the number of control variables increases leading to control instability
Solution Approach 1:
The patent combines multiple temperature measurement functions into a single temperature sensor located on the susceptor. This single sensor provides sufficient temperature information for controlling all heating zones, reducing the number of control variables from multiple sensors per zone to a single centralized sensor, thereby improving control stability while maintaining measurement accuracy.
Solution Approach 2:
The susceptor acts as an intermediary that distributes heat from multiple zone heating apparatuses. By placing a single temperature sensor on the susceptor, the system measures the integrated temperature result of all heating zones, using the susceptor as a mediator to translate multiple heating inputs into a single measurable output that guides the control of all zones.
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 results in a robust control loop that maintains consistent substrate temperature, reducing temperature gradients and allowing for precise temperature ramps, even with changing process conditions, enhancing the efficiency of substrate treatment processes like MOCVD.
Implementation Method 1
a heating apparatus (1, 2, 3, 4, 5) having a plurality of zone heating apparatuses (1, 2, 3)
Implementation Method 2
The zone heating apparatuses (1, 2, 3, 4, 5) are preferably water-cooled induction coils
Implementation Method 3
The temperature of the susceptor surface is, inter alia, to be measured pyrometrically
Data Source
AI summary
A heating apparatus includes a plurality of zone heating apparatuses and a control apparatus. The reference variable of the control apparatus is a susceptor temperature. The controlled variable of the control apparatus is an actual temperature of the susceptor measured by a temperature sensor and the manipulated variable of the control apparatus is the total heating power fed into the heating apparatus. A heating power distributor receives the total heating power as an input variable and provides a zone heating power for each of the zone heating apparatuses as output variables. The sum of the zone heating powers corresponds to the total heating power and the zone heating powers have a specified ratio with respect to each other. In order to specify a robust control loop, the specified ratios are defined by distribution parameters, wherein at least one distribution parameter is a quotient of two zone heating powers.