Diamond

Diamond is the ultimate material which has the best physical properties of all materials in terms of hardness, acoustic velocity, thermal conductivity, Young's modulus, etc. Additional properties include transmittance of a broad wavelength spectrum from ultraviolet to infrared, thermal and chemical stability, and controllable electrical resistance/conductivity. These properties make diamond useable in a variety of applications, such as heat sinks, machining tools, optical components, audio components, and semiconductors.

Diamond Production Method

The present diamond synthesis method is high-pressure, high-temperature (HPHT) method. The homoepitaxial diamond growth process on HPHT-diamond substrate by Chemical Vapor Deposition (CVD) is also well known method for producing diamond substrate. This method is superior in the quality but limits the substrate size.

World's first, large diameter diamond production method

Orbray employs Heteroepitaxy targeting large diamond substrates.
In principal, hetroepitaxy, which uses a foreign material as a basal substrate, has theoretical possibility of producing diamond substrates with the same size as basal foreign substrates.
However, due to the heteroepitaxial strain owing to the lattice and thermal expansion differences of diamond and basal substrate, quality degradation and crack generation still occur in thick bulk diamond growth.

We made a new approach to overcome the above mentioned issues in heteroepitaxy. Based on the world's first Ir/Sapphire basal substrate process technology, we combined with our own newly developed microneedle growth technology (JP Patent 6142415B) which enables to prevent crack generation and allow to grow stress-free, high quality, large diameter diamond substrate for stable production. The diamond wafer has been named KENZAN Diamond™.
In addition, a novel step flow growth technology was developed to grow two-inch (50 mm) diameter diamond crystals which are needed for industrial applications. We capitalized on our sapphire substrate technology to precisely control the base sapphire wafer. The inclined Ir/sapphire surface results in lateral growth of the diamond crystal, which alleviates stress accumulation during the growth process. We are now tackling the challenge of further increasing the wafer size, with four-inch diameter as the next stage.

Fabrication technique of KENZAN Diamond™

Novel technology (Step-flow growth)

Step-flow growth:strain in the
lateral directionThe crystal grows
in the lateral direction（Sapphire step substrate, Ir buffer, Diamond）

Simple manufacturing process leads to cost reduction.

Conventional technology (Microneedle growth)

Conventional structure

A large amount of stress is applied to the grown diamond, causing cracks.
Microneedles are needed to prevent the diamond from breaking.
Microneedle fabrication process was complex and costly.

Novel structure

Step flow growth uses sapphire step substrate.
Stress on the diamond layer is applied laterally, eliminating the need for microneedles.
Significant reductions in production time and cost make step-flow growth an appropriate technique for mass production. Two-inch diamond substrate is available.