Key factors to note when cultivating diamonds for microwave CVD equipment

We all know that microwave plasma CVD equipment can cultivate the growth of diamond, but there are two key factors that must be paid special attention to when using this type of equipment, as follows:

1. Gas composition and flow rate

Gas composition is one of the key factors in the cultivation of diamond in microwave plasma CVD equipment. Hydrogen and methane are the most common gas combinations, but their proportions have a significant impact on diamond cultivation growth. In general, a higher ratio of hydrogen helps to maintain plasma stability while inhibiting the formation of the graphite phase. For example, a 95:5 ratio of hydrogen to methane promotes better diamond growth.

The gas flow rate also needs to be precisely controlled. If the gas flow rate is too high, it will lead to pressure fluctuations within the reaction chamber, affecting the stability of the plasma; while too little flow rate may not provide enough carbon atoms for diamond growth. Just like cooking, the ratio of ingredients and the rate of delivery need to be just right to make a delicious dish.

2. Substrate material and pretreatment

The choice of substrate material determines the basis of diamond cultivation in microwave plasma CVD equipment. Different substrate materials have different properties such as adhesion and thermal expansion coefficient with diamond. For example, silicon substrate is a commonly used substrate material because a better adhesion between silicon and diamond can be formed by some special treatment.

The pretreatment of the substrate is equally important. Before diamond cultivation and growth, pretreatment operations such as cleaning and etching of the substrate can improve the activity of the substrate surface and increase the adhesion of carbon atoms. For example, by ion etching the substrate surface, the impurities and oxide layer on the surface can be removed, providing a clean and active surface for diamond growth.

Therefore, we judge the quality of diamond cultivated by a CVD equipment, we can't just blame it on the quality of the CVD equipment, but also need to use the process of gas ratio mixing whether it is correct or not, and whether the quality of the substrate material they choose is reliable.