CVD Diamond Production Principles

The growth of CVD rough diamonds starts from qualified CVD seeds, and excellent seeds have the following characteristics: 

1. The inside of the seed crystal is clean 

 3. The four sides and four corners of the seed crystal are not damaged 

 4. Uniform stress distribution 

 5. The same size and color are unified 

 The above four points are to ensure that the seed crystal will not produce cracks during the growth process. Once cracks occur, it is easy to crack during the subsequent rough diamond processing process and become broken diamonds, and the value will be greatly reduced. 

 In addition to the above quality points, the production quality of CVD rough diamonds is also related to the crystal orientation of the seed crystal. Crystal orientation is a relatively complex concept, which is simplified here for readers to understand. If you want to know more about it, you can refer to relevant information. To understand the crystal orientation simply, we divide the crystal orientation of the seeds that can grow into 100 and 110, 110 means that the seed crystal can grow up and down, and 100 means that the seed crystal can grow up and down and around. 

 Speaking of this, some people will say, it must be 100% good, and all eight sides can grow, so can you use small crystal seeds to grow into larger rough diamonds? In principle, this is feasible, but in fact such a technology is far from mature. At present, very few people have mastered the growth technology of 100 crystal orientation seeds, and most lab-grown diamond manufacturers have only mastered the growth of 110 crystal seeds. technology. 

 Therefore, if there is no 100-seed growth technology, it is a waste of cost to purchase 110-seed crystals. If the growth process is not well controlled, a batch of seed crystals may be wasted, and this all depends on a team of engineers with strong enough technology. 

 CVD seeds are grown in MPCVD diamond machines. The full English name of MPCVD is Microwave Plasma Chemical Vapor Deposition, that is, "microwave plasma chemical vapor deposition". This is a process of producing CVD rough diamonds with microwave as energy source and gas CH4, H2, N2, CO2 as raw materials. 

Diamond is composed of C element. One C atom combines with other four C atoms to form a tetrahedral structure similar to CH4. Under the ionization action of microwave source, CH4 gradually ionizes to lose the "-H" group, and the remaining C atoms Gradually deposited on the surface of the seed crystal, forming the chemical structure "C4" of diamond. We only need a certain amount of time, and different sizes of seed crystals take different times to grow into rough diamonds. For example, a furnace of 7x7 seed crystals has 32 pieces, and it takes 350-370 hours to grow, about 14-16 days.