DC Lamp Driver for RTP Substrate Heating
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Solution Overview
Problem
Rapid Thermal Processing (RTP) tools face challenges in controlling wafer temperature and providing accurate phase angle control due to limitations in lamp configuration and power distribution when using high voltage AC power sources, leading to issues like thermal shock and arcing in semiconductor manufacturing.
Innovation Solution
The use of a lamp driver system that converts 480V AC power to DC power and further steps it down using a DC/DC converter, allowing for efficient power distribution to arrays of lamps, including halogen lamps, while maintaining balanced current across phases and preventing arcing, through a configuration of lamps wired in series and parallel, and employing a Buck converter for efficient voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage AC power sources are used to power lamp arrays for rapid thermal processing, then heating power and efficiency are improved, but phase angle control accuracy deteriorates and arcing occurs
Solution Approach 1:
The patent replaces the AC power system with a DC power system. Instead of using AC power sources with phase angle control, the invention uses DC power sources to drive the lamp arrays, eliminating the fundamental limitations of AC-based control methods and achieving both high power and precise control without arcing
Solution Approach 2:
The patent changes the electrical parameter from AC to DC. By converting the power source type and reconfiguring the lamp arrays with DC-optimized series-parallel configurations, the system achieves improved voltage matching, current balancing, and control precision while eliminating the harmful effects of AC power delivery
2Power
If high voltage AC power sources are used to power lamp arrays, then heating efficiency is improved, but arcing and thermal shock occur
Solution Approach 1:
The patent substitutes DC power delivery for AC power delivery, eliminating the oscillating current characteristics that cause arcing. The DC system provides smooth, controlled current flow that prevents electrical discharge and enables gradual temperature changes, thereby preventing both arcing and thermal shock while maintaining high heating efficiency
Solution Approach 2:
The DC power system inherently provides cushioning against thermal shock by enabling controlled, gradual power delivery. The system can ramp up power smoothly without the abrupt transitions associated with AC cycling, protecting the substrate from sudden thermal stress before processing begins
3Power
If lamp arrays are configured for high voltage operation, then power delivery is improved, but current balancing across phases deteriorates
Solution Approach 1:
The patent eliminates the multi-phase AC system that suffers from current balancing issues by adopting a DC system. With DC power, all lamp strings can be uniformly configured in series-parallel arrangements, ensuring identical current flow through each string without the phase imbalances that plague AC systems
Solution Approach 2:
The DC-optimized lamp array configuration uses identical series-parallel string arrangements throughout, ensuring homogeneous current distribution. Each string experiences the same electrical conditions, achieving perfect current balance across all lamps without the phase-related variations inherent in AC systems
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 temperature control and efficient heating of substrates in RTP tools, preventing thermal shock and arcing, while allowing for the use of higher voltage AC power sources without exceeding current limits, thus improving the reliability and efficiency of semiconductor processing.
Implementation Method 1
a rectifier coupled to the AC power source to convert the AC input waveform to DC voltage
Implementation Method 2
a direct current to direct current (DC/DC) converter to reduce voltage of the DC power
Implementation Method 3
a lamp group comprising one or more sets of lamps to provide radiant energy to heat a substrate
Data Source
AI summary
Methods and apparatus for heating a substrate in a process chamber are provided herein. In some embodiments, an apparatus for heating a substrate in a process chamber includes a lamp group comprising one or more sets of lamps to provide radiant energy to heat a substrate when disposed in the process chamber, wherein each set of lamps comprises a plurality of lamps wired in series, and wherein each set of lamps is wired in parallel with respect to other sets of the one or more sets of lamps; an alternating current (AC) power source to produce an AC input waveform; and a lamp driver to power the lamp group, the lamp driver including a rectifier coupled to the AC power source to convert the AC input waveform to DC voltage; and a direct current to direct current (DC/DC) converter to reduce voltage of the DC power.