RTP Lamp Base Thermal Management via High Conductivity Potting
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Solution Overview
Problem
Conventional semiconductor processing lamps face premature failure due to excessive heating, which reduces their lifespan, as the lamp base and reflector sleeve absorb significant radiant energy, leading to high temperatures and oxidation of molybdenum foils, causing seal ruptures and open circuits.
Innovation Solution
A lamp assembly with a metal sleeve surrounding the lamp base filled with a high thermal conductivity potting compound, such as magnesium phosphate bonded aluminum nitride, exceeding 100 W/(K-m), and a thicker sleeve to enhance heat dissipation, combined with a secondary potting compound for improved reflectivity, aids in efficiently conducting heat away from the bulb and base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling mechanisms (porous potting compound, water-cooled stainless steel tubes, reflector sleeves) are used to cool the lamp base, then the lamp base temperature is reduced, but the lamp lifetime is still substantially reduced due to oxidation of molybdenum foils above 300°C
Solution Approach 1:
The patent changes the thermal conductivity parameter of the potting compound from conventional low values to extremely high values (greater than 100 W/m-K, preferably greater than 200 W/m-K). This parameter change enables the potting compound to effectively conduct heat away from the lamp base and foils, maintaining them below 300°C to prevent oxidation and extend lamp lifetime
Solution Approach 2:
The patent employs composite material structures including: (1) a bulb made of material with high thermal conductivity greater than 10 W/m-K (such as sapphire, diamond, or cubic boron nitride) to conduct heat away from the filament; and (2) a potting compound with extremely high thermal conductivity greater than 100 W/m-K to conduct heat away from the lamp base. These composite materials work together to achieve effective heat management
2Loss of energy
If elaborate cooling structures (water-cooled stainless steel tubes, reflector sleeves) are implemented to conduct heat away from the lamp, then heat dissipation is improved, but the device complexity increases
Solution Approach 1:
The patent merges the cooling function directly into the lamp structure by using a bulb made of high thermal conductivity material and filling the lamp base with high thermal conductivity potting compound. This integration eliminates the need for separate water-cooled stainless steel tubes and reflector sleeves, simplifying the overall device while maintaining effective heat dissipation
Solution Approach 2:
By changing the thermal conductivity parameter of the bulb material and potting compound to extremely high values, the patent achieves effective heat dissipation through material properties rather than through complex geometric cooling structures, thereby reducing device complexity
3Temperature
If a heat shield or reflector plate is added within the lamp bulb to conduct heat away, then heat dissipation is improved, but the manufacturing complexity increases due to additional parts
Solution Approach 1:
The patent changes the thermal conductivity parameter of the bulb material itself to greater than 10 W/m-K (using materials like sapphire, diamond, or cubic boron nitride), enabling the bulb to conduct heat away from the filament without requiring internal heat shields or reflector plates. This parameter change eliminates additional parts and simplifies manufacturing
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 solution significantly extends lamp life by reducing bulb and base temperatures, preventing premature failures and improving heat transfer efficiency, with temperature reductions of 75° C to 100° C at critical locations within the RTP chamber.
Implementation Method 1
a metal sleeve surrounding the lamp base filled with a high thermal conductivity potting compound, such as magnesium phosphate bonded aluminum nitride, exceeding 100 W/(K-m)... significantly extends lamp life by reducing bulb and base temperatures... with temperature reductions of 75° C to 100° C at critical locations
Implementation Method 2
a bulb enclosing at least one radiation generating filament... The lamps are electrically powered and can be very quickly turned off and on and a substantial fraction of their radiation can be directed to the substrate... During processing, infrared radiation from the lamps radiates... onto a rotating semiconductor substrate
Implementation Method 3
a metal sleeve surrounding the lamp base filled with a high thermal conductivity potting compound... the sleeve having a wall thickness of at least about 0.020 inches... aids in efficiently conducting heat away from the bulb and base
Data Source
AI summary
A lamp assembly adapted for use in a substrate thermal processing chamber to heat the substrate to temperatures up to at least about 1100° C. is disclosed. In one embodiment, the lamp assembly comprises a bulb enclosing at least one radiation generating filament attached to a pair of leads, a lamp base configured to receive the pair of leads, a sleeve having a wall thickness of at least about 0.013 inches and a potting compound having a thermal conductivity greater than about 100 W/(K-m).