Convert CVD Diamond Growing Reactors from Gem to Tech

Is it possible to convert reactors?

Yes, it is possible in some cases to change diamond gem growing reactors to grow diamond for Tech applications. There are different criteria needed for different Tech usage. For example, microwave will be different than aerospace or photonic. Once you use different gases in your chamber, you cannot grow for gem without a large amount of work on the chamber. We recommended that you start with just a few chambers. Working with your in-house engineers, their first step should be to speak with the manufacturer of your chambers to completely understand how they work before making any changes. 

There is some information publicly available on the Internet showing them some of the latest scientific information available. This will allow them to test and retest growing methods. The next step may be to bring in specialists for the categories that you want to focus on. Each category may have different finished diamond requirements. One of the largest and most important need for grown diamond now is used for thermal management in high-powered electronics. Semiconductors lead the way with battery cooling systems close behind. Other focuses are aerospace, laser, microwave, optics, photonics, and quantum sensors. 

Modified CVD Reactor for Electronics-Grade Diamond Growth

This schematic illustrates a modified Chemical Vapor Deposition (CVD) reactor designed for the growth of electronics-grade synthetic diamond. Key modifications include the use of ultra-high purity gases, precise dopant control, single-crystal diamond substrates, stable thermal regulation, and contamination-free chamber materials. These enhancements enable the production of high-quality diamond films suitable for power electronics, quantum devices, and photonic applications.

To transition from growing CVD gem-quality diamonds to producing CVD diamonds suitable for high-power electronic applications, a grower must make several technical, equipment, and process modifications. The core objective is to shift from aesthetic quality (color, clarity, size) to electronic-grade purity, thermal conductivity, and structural integrity.

1. Chamber Environment and Gas Chemistry

• Gas purity upgrades: Use ultra-high-purity (UHP) gases—especially hydrogen and methane—with impurity levels in the parts-per-billion (ppb) range. This minimizes defect formation.
• Gas mixture adjustment: The methane-to-hydrogen ratio may need to be adjusted to grow at slower, more controlled rates, reducing defects critical to electronic applications.
• Inert or dopant gas introduction: For electronic-grade diamond (e.g., for semiconductors), controlled doping (e.g., boron for p-type or phosphorus for n-type) must be introduced using specialized gas handling systems.

2. Substrate Material and Preparation

• Switch to high-quality diamond substrates: Single-crystal synthetic diamond substrates are needed to grow high-quality homoepitaxial layers with minimal lattice mismatch.
• Surface polishing and cleaning: Substrates must be polished to atomic smoothness (Ra < 1 nm) and cleaned in ultra-clean environments to prevent nucleation of non-diamond phases.

3. Reactor Design Modifications

• Temperature control enhancement: Electronic-grade diamond requires extremely stable growth temperatures (~800–1000°C), so reactors need precision thermal management.
• Microwave or plasma field tuning: Uniform plasma density and microwave field distribution are essential for consistent diamond layer growth.
• Contamination control: Reactor materials and internal components must be non-reactive and outgas-free at high temperatures (e.g., molybdenum, tantalum, or coated graphite), to prevent trace metal contamination.

4. Growth Rate Control

• Lower growth rates (~0.1–1 µm/hr): While gem-quality diamond can tolerate higher growth rates for larger volume, electronic-grade diamond requires low and controlled growth to avoid dislocations and non-diamond carbon incorporation.

5. Cleanroom and Process Control

• Move the entire process to a Class 100 or better cleanroom.
• Implement in-situ diagnostics (e.g., optical emission spectroscopy) to monitor the plasma and ensure consistency.
• Strict process repeatability and calibration protocols must be enforced.

6. Post-Growth Characterization

• Equipment must be added to evaluate:
  • Raman spectroscopy (for phase purity)
  • Photoluminescence and cathodoluminescence (for defects and dopants)
  • X-ray topography (for dislocation density)
  • Electrical testing (for resistivity and carrier mobility)

7. Target Applications & Requirements

Depending on the end-use (e.g., power transistors, heat spreaders, diodes), the diamond may need:

• High thermal conductivity (>2000 W/m·K)
• High breakdown voltage (~10 MV/cm)
• Low defect density (<10⁴ cm⁻²)
• Specific doping profiles

Area

Gem-Quality Focus

Electronic-Grade Focus