Diamond Growth

 

Cardiff Diamond Foundry operates four Microwave Plasma Chemical Vapour Deposition systems. Our main doping workhorse is a Seki 6500 series system equipped with Trimethylboron as the doping source. This reactor routinely grows superconducting diamond films with transition temperatures around 5K as well as electrochemical electrode grade material. A second load-locked UHV system (Seki SDS5250) is being installed  for our SQUIDs and superconducting nanoelectromechanical systems.


For intrinsic diamond growth we operate a Carat Systems CTS6U which is basically an enhanced 6500 series with differentially pumped seals and conflat windows. It has a far lower leak rate than a standard 6500 reactor.


Our fourth reactor is a home built quartz tube (NIRIM) style reactor. This system is for the production of diamond with novel colour centres. We openly share the design of this system to other users. This system has a liquid precursor option for incorporating novel materials into the CVD process. Our open source design is available at this wiki.


All reactors have comprehensive in-situ monitoring including pyrometers covering the temperature ranges 200-600ºC, 300-1000ºC and 475-1475ºC. These are two colour / ratio pyrometers which have been calibrated and demonstrated their accuracy on numerous substrates. However, the use of pyrometry is fraught with dangers and their accurate use requires some skill and experience. We also have a disappearing filament pyrometer for difficult samples as well as access to an IR camera.


Growth rates can be monitored in-situ either by laser interferometry (for films thicker than 100nm) or by Spectroscopic Ellipsometry (films from 10nm thick). We also operate a k-Space MOS for in-situ stress characterisation.


All deposition equipment is fully automated with safety systems that allow long term unsupervised operation with process logging.


Nucleation areas are entirely under (class 100) lamina flow to reduce contamination from dust particles etc. Substrates are immersed in aqueous colloids of mono-disperse diamond particles under ultrasound. After this they are rinsed and spun dry with a wafer spinner. These techniques have been demonstrated to yield the ultra-high nucleation densities required for nanocrystalline diamond growth.


For post growth planarisation, the laboratory is equipped with a Logitech Tribo Chemo-Mechanical Polishing facility. Processes to planarise nanocrystalline diamond films from their as grown roughness of the order of 20 nm rms (over several micron) down to below 2nm rms have been developed in collaboration with Logitech Ltd. This process is based around Syton SF1 slurry (colloidal silica). This process has been demonstrated to be effective on both nanocrystalline diamond and single crystal materials ({100} and {111}).


Seki 6500 series Microwave Plasma Chemical Vapour Deposition system for diamond growth (boron doping).

Logitech Tribo Chemo-Mechanical Polishing (CMP) system for planarising wafers up to 4” diameter.

Carat Systems CTS6U deposition system for high purity intrinsic diamond.

Seki SDS5350 series Microwave Plasma Chemical Vapour Deposition system for diamond growth (superconductivity). This system is load locked with online mass spectrometry.

This system can also be configured with k-Space MOS (right) and Spectroscopic Ellipsometry for comprehensive in-situ monitoring.

Quartz tube reactor for single photon source production (silane, metal organic sources etc).