Influence Of Process Parameters On The Growth Of Diamond Films

Chemical vapor deposition (CVD) diamond films and natural diamond havemany excellent prospects in many areas. Studies show that the performance of CVDdiamond films depend on crystal orientation、grain size and content of sp3carbon.These properties are available system controlled through the growth conditions.Therefore, the study of growth conditions of CVD diamond films is necessary. In thispaper, we choose microwave plasma chemical vapor deposition (MPCVD) to preparediamond films, and study regular pattern of the nucleation density, carbonconcentration and substrate temperature about the growth of diamond films.Nucleation of CVD diamond films is mainly affected by the nucleation time andthe carbon concentration. Experimental results show that the nucleation densityincreases as with the nucleation time increasing when certain other conditions areunchanged; at the same time the nucleation density increases as with carbonconcentration increasing. The grow of different nucleation density of diamond filmswas studied, and the results showed that the higher the nucleation density is, the betterof the density of films is, meanwhile, particles arrange orderly, but grain sizes aresmall; nucleation density is low, and particle size of surface of the films is larger, butthe denseness is relatively poor, there are holes in some regions, meanwhile, particlesare disorderly.When selecting a relatively higher concentration of methane2%to grow films,the grain sizes of the surface of diamond films are gradually decreasing as thetemperature increasing. The density of films surface is good, and there is no hole.Raman shift peak of the diamond and first-order FWHM values continuously becomesmall, which indicates that amorphous phases gradually are less and content of sp3carbon continues to increase. And a high concentration of methane at the highsubstrate temperature, films select (100) plane to grow firstly. Its growth rate is6.0μm/h.When the methane concentration is0.75%, the particle sizes of surface of thefilms increase as the temperature increasing. The half-value width of Raman peaks ofdiamond gradually becomes smaller, which indicates that, high temperature is benefitto obtain a higher content of diamond phase in deposition process. Further, the surfaceof the films at low methane concentration are emerging (111) plane. As the substrate temperature increasing, the size of (111) plane increases.