Multiplexed Heated Array Current Peak Spreading
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Solution Overview
Problem
Semiconductor substrate processing requires precise and uniform temperature control to maintain critical dimension uniformity, which is challenging due to complex heat transfer dynamics and non-equilibrium phenomena like plasma, especially as transistor sizes decrease and substrate diameters increase.
Innovation Solution
A heating plate with multiple independently controllable planar heater zones, connected through a scalable multiplexing layout of power supply and return lines, allows for precise spatial and temporal temperature profiling, using diodes to prevent reverse current flow and minimize crosstalk, and a controller calculates time durations for each heater zone to reach setpoint temperatures efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple heater zones are used to improve temperature uniformity, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The heating plate is divided into multiple independently controllable heater zones (M x N zones) that can be selectively activated. This segmentation allows precise spatial temperature control by turning on only the zones needed for specific substrate regions, achieving uniform temperature distribution without requiring excessive heating power anywhere in the system.
Solution Approach 2:
The patent implements time-multiplexed control where heater zones are activated sequentially in periodic cycles rather than simultaneously. Each cycle activates a subset of heater zones, and the pattern repeats. This periodic activation distributes the thermal load over time, reducing peak current demands while maintaining temperature uniformity through strategic sequencing of heater activation.
2Speed
If all heater zones are powered simultaneously to reach setpoint temperature, then temperature control speed improves, but current peaks increase causing temperature fluctuations
Solution Approach 1:
Instead of activating all heater zones simultaneously, the system uses time-multiplexed periodic activation where zones are powered in sequential batches. This spreads the current demand over multiple time periods, eliminating dangerous current peaks while still achieving temperature control through repeated cycling. The periodic nature ensures all zones receive adequate heating duty cycle to reach setpoint temperatures.
Solution Approach 2:
The system calculates and sequences heater activation in advance, determining optimal activation patterns before executing temperature control. By pre-planning the temporal distribution of heater activation based on thermal models and substrate requirements, the system achieves efficient temperature control without inducing current peaks that would cause fluctuations.
3Reliability
If heater zones are activated in sequential batches to reduce current peaks, then temperature stability improves, but temperature control time increases
Solution Approach 1:
The sequential batch activation is optimized through periodic cycling where multiple heater zones are activated in parallel within each batch, and batches are executed in sequence. This creates an efficient rhythm where heating actions are distributed but maintained continuously through repeated cycles, achieving temperature stability without excessive total heating time.
Solution Approach 2:
The system dynamically adjusts heating parameters including activation timing, duration, and intensity based on real-time temperature feedback and substrate requirements. By changing these parameters adaptively rather than using fixed sequential patterns, the system optimizes the balance between temperature stability and control time, achieving both goals simultaneously.
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 solution enables precise radial and azimuthal temperature control, reducing non-uniformity in substrate processing and enhancing critical dimension uniformity, even at sub-100 nm scales, by actively compensating for adverse factors affecting temperature profiles.
Implementation Method 1
M electrically conductive power supply lines, N electrically conductive power return lines, a planar heater zone Zij connected to an i-th power supply line and a j-th power return line for every pair of i and j wherein 1≦i≦M, 1≦j≦N, i and j are integers, and the planar heater zone Zij comprises one or more heater elements
Data Source
AI summary
A method of operating a heating plate for a substrate support assembly used to support a semiconductor substrate in a semiconductor processing apparatus, wherein the heating plate comprises power supply lines and power return lines and respective heater zone connected between every pair of power supply line and power return line. The method reduces maximum currents carried by the power supply lines and power return lines by temporally spreading current pulses for powering the heater zones.