Different applications of single and polycrystalline diamond

As we all know, diamond semiconductor materials can be divided into single crystal and polycrystal, and their preparation requirements and application directions are very different.

1. Diamond polycrystal and its application

The preparation methods of CVD polycrystalline diamond film include high power DC arc plasma injection CVD, hot wire CVD and MPCVD. The preparation of optical and electronic grade polycrystalline diamond films requires ideal deposition rate and extremely low or controllable defect density. MPCVD without electrode contamination discharge is bound to be an ideal method for the preparation of electronic and optical grade diamond films. But the growth rate of polycrystalline diamond is slow, and the consistency of crystal direction is very important for processing.

Compared with the harsh preparation and application conditions of optical grade and electronic grade polycrystalline diamond film, polycrystalline diamond film is widely used as the heat sink of semiconductor power device heat dissipation, and the demand is greater and more urgent. At present, the technical level of precipitation is also relatively easy to achieve.

In addition, the preparation cost of polycrystalline diamond is more obvious than that of single crystal diamond. In the past 30 years, MPCVD polycrystalline diamond film has been used as heat sink in semiconductor devices. At present, the heat sink of inch Si based polycrystalline diamond is used in HEMTs devices. The RF power density of the devices has been effectively improved to more than 23W/ mm.

2, diamond single crystal and its application

Compared with polycrystalline diamond, single crystal diamond (SCD) without grain boundary restriction has better optical and electrical properties. It has outstanding application effect in frontier science and technology fields such as quantum communication/computational radiation detector, cold cathode field emission display, semiconductor laser, multi-dimensional integrated circuit of supercomputer CPU chip and thermal conduction support rod of microwave travelling wave tube of military high power radar. The premise is to prepare large size and high quality SCDS.

Diamond as a wafer must be at least 2 inches in size. At present, the main techniques for preparing large size diamond and wafer are homoepitaxial growth, Mosaic wafer preparation and heteroepitaxial growth.

After breakthrough in the microwave plasma chemical vapor deposition (MPCVD) growth technology, such as high speed growth with nitrogen addition, high efficiency growth with pulse discharge and ion implantation stripping, it has realized the multi-direction repeated 3D MPCVD high speed epitaxial growth (growth rate 100 μm·h-1) in the past 10 years. The growth of large, thick and polycrystalline diamond edges and the use of plasma CVD in (H, C, N, O) system for 200 h continuous growth without boundaries and other innovative technologies.

With the capability of MPCVD equipment design, the company is the first in China to master the core process of MPCVD preparation of high-quality diamond and achieve mass production. Moreover, it has created an efficient precision processing method for atomic diamond surface based on plasma assisted polishing. The wafer-grade diamond Ra<1nm and the thermal conductivity of diamond heat sink sheet 1000-2000W/m.k. GaN on diamond, Diamond on GaN, diamond-based aluminum nitride, single crystal and other products, to provide you with the most complete diamond thermal management solutions.