Pedestal Heaters
One of the critical application needs for semiconductor processing in CVD (chemical vapor deposition) is high-temperature processing (450°C to 650°C). The use of aluminum nitride (AlN) for the wafer pedestal is critical for meeting this temperature requirement.
Fralock meets this need with a novel technology using machined, green AlN to create a contiguous AlN pedestal heater with integrated tungsten heater traces and RTDs.
Several Heating Zones for Effective Thermal Uniformity
Multi-Layer Platen and Pedestal Heaters
- Groundbreaking AlN Technology
Using multi-layer technology, we can create multiple zones to fit specific uniformity needs and chamber environments for high-temperature applications. Screen printing of tungsten (W) resistance and measurement traces on individual layers provides in-layer and through-layer connections for creating zones and measurement within each zone.
Fralock has patented the ability to create a fully integrated, hermetically-sealed AlN stem-to-platen system. Utilizing this in-plane technology, the tungsten traces running from the platen through the stem are in the “stem wall”. Both electrical connections and the vacuum interface are positioned at the bottom of the stem, away from the high temperatures of the platen.
These distal temperatures are under 300°C, significantly lower than the platen temperatures, thereby extending the life of electrical connections and vacuum interface materials when compared to simple machined AlN technologies.
Further, the use of integrated RTDs within the zone allows for extremely high ramp rates, due to the immediate feedback within each zone. By using W for the heater traces and RTDs, the ramp rates can be very high as the TCE (thermal coefficient of expansion) of W and AlN or so closely matched.
- Design Spec Capabilities
- Sizes up to 380mm diameter
- Integral stems up to 6” using patented pressure-less bonding stem to patent
- Multi-zone heater and integrated RTD for temperature sensor capability
- Ground planes knitted with vias for electrical isolation cages
- Possibility for RF plane integrated into the platen
- Ceramic vacuum groove/wafer chuck configurations available
- Internal gas delivery passages
- Thermal breaks between heated zones
- Connections at bottom of platen for low temperature or through-stem for high temperature stemmed platen applications
Fralock can fabricate internal cooling channels, internal and external vacuum or gas delivery channels, and surface vacuum grooves (ceramic vacuum wafer chucks) with both green state and final state machining capabilities. A wide range of external features are also available by green machining for feature customization with lower cost when compared to post fire machining.
