Inductively coupled plasma （ICP） etching of single crystal 6H-silicon carbide （SIC） is investigated using oxygen （O2）-added sulfur hexafluoride （SF6） plasmas. The relations between the microtrenching effect an...Inductively coupled plasma （ICP） etching of single crystal 6H-silicon carbide （SIC） is investigated using oxygen （O2）-added sulfur hexafluoride （SF6） plasmas. The relations between the microtrenching effect and ICP coil power, the composition of the etch gases and different bias voltages are discussed. Experimental results show that the microtrench is caused by the formation of a SiFxOy layer, which has a greater tendency to charge than SiC, after the addition of O2. The microtrenching effect tends to increase as the ICP coil power and bias voltage increase. In addition, the angular distribution of the incident ions and radicals also affects the shape of the microtrench.展开更多
Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pr...Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pressure and working temperature. The etching process of Si3N4 is studied by inductively coupled plasma (ICP) with a gas mixture of SF6 and O2. The influence of the technique parameters, such as ICP power, DC bias, gas composition, total flow rate, on the etching selectivity of Si3N4/EPG533 which is used as a mask layer and the etching rate of Si3N4 is studied, in order to get a better etching selectivity of Si3N4/EPG533 with a faster etching rate of Si3N4. The optimized process parameters of etching Si3N4 by ICP are obtained after a series of experiments and analysis. Under the conditions of total ICP power of 250 W, DC bias of 50W, total flow rate of 40 sccm and O2 composition of 30%, the etching selectivity of 2.05 can be reached when Si3N4 etching rate is 336 nm/min.展开更多
The influence of deposition, annealing conditions, and etchants on the wet etch rate of plasma enhanced chemical vapor deposition （PECVD） silicon nitride thin film is studied. The deposition source gas flow rate and...The influence of deposition, annealing conditions, and etchants on the wet etch rate of plasma enhanced chemical vapor deposition （PECVD） silicon nitride thin film is studied. The deposition source gas flow rate and annealing temperature were varied to decrease the etch rate of SiNx：H by HF solution. A low etch rate was achieved by increasing the SiH4 gas flow rate or annealing temperature, or decreasing the NH3 and N2 gas flow rate. Concentrated, buffered, and dilute hydrofluoric acid were utilized as etchants for Sit2 and SiNx：H. A high etching selectivity of Sit2 over SiNx：H was obtained using highly concentrated buffered HE展开更多
Spherical Si solar cells were fabricated based on multicrystalline Si spheres produced by a dropping method. The thermal history of Si spheres were calculated by numerical simulation. The simulation result reveals tha...Spherical Si solar cells were fabricated based on multicrystalline Si spheres produced by a dropping method. The thermal history of Si spheres were calculated by numerical simulation. The simulation result reveals that heat transfered by convection is greater than heat transfered by radiation. Considering the calculation results, Si spheres were dropped in the free-fall tower at low pressure state (0.2×105-0.5×105 Pa) to slow heat transfer by convection. After dash etching for 60 min, low pressure Si spheres have less etch pits, i.e., 80% for etch pit density and 8% for etch pit-area ratio compared to normal one. Furthermore, the conversion efficiency was improved from 6.57% (normal pressure spherical Si solar cell) to 9.56% (low one), which is 45% relative increase. The improvement is due to decrease of undercooling and increase of crystal growth duration. These results demonstrate that the dropping method at low pressure state is useful for fabricating high performance spherical Si solar cells.展开更多
基金supported by the Chinese National Advance Research Program of Science and Technology (Nos. 51308030201, 51323040118)
文摘Inductively coupled plasma （ICP） etching of single crystal 6H-silicon carbide （SIC） is investigated using oxygen （O2）-added sulfur hexafluoride （SF6） plasmas. The relations between the microtrenching effect and ICP coil power, the composition of the etch gases and different bias voltages are discussed. Experimental results show that the microtrench is caused by the formation of a SiFxOy layer, which has a greater tendency to charge than SiC, after the addition of O2. The microtrenching effect tends to increase as the ICP coil power and bias voltage increase. In addition, the angular distribution of the incident ions and radicals also affects the shape of the microtrench.
文摘Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pressure and working temperature. The etching process of Si3N4 is studied by inductively coupled plasma (ICP) with a gas mixture of SF6 and O2. The influence of the technique parameters, such as ICP power, DC bias, gas composition, total flow rate, on the etching selectivity of Si3N4/EPG533 which is used as a mask layer and the etching rate of Si3N4 is studied, in order to get a better etching selectivity of Si3N4/EPG533 with a faster etching rate of Si3N4. The optimized process parameters of etching Si3N4 by ICP are obtained after a series of experiments and analysis. Under the conditions of total ICP power of 250 W, DC bias of 50W, total flow rate of 40 sccm and O2 composition of 30%, the etching selectivity of 2.05 can be reached when Si3N4 etching rate is 336 nm/min.
基金Project supported by the National High Technology Research and Development Program of China (No.2007AA04Z322)the State Key Development Program for Basic Research of China (No.2009CB320305)the Hundred Talents Plan of Chinese Academy of Sciences
文摘The influence of deposition, annealing conditions, and etchants on the wet etch rate of plasma enhanced chemical vapor deposition （PECVD） silicon nitride thin film is studied. The deposition source gas flow rate and annealing temperature were varied to decrease the etch rate of SiNx：H by HF solution. A low etch rate was achieved by increasing the SiH4 gas flow rate or annealing temperature, or decreasing the NH3 and N2 gas flow rate. Concentrated, buffered, and dilute hydrofluoric acid were utilized as etchants for Sit2 and SiNx：H. A high etching selectivity of Sit2 over SiNx：H was obtained using highly concentrated buffered HE
基金This work was partly financially supported by NEDO.
文摘Spherical Si solar cells were fabricated based on multicrystalline Si spheres produced by a dropping method. The thermal history of Si spheres were calculated by numerical simulation. The simulation result reveals that heat transfered by convection is greater than heat transfered by radiation. Considering the calculation results, Si spheres were dropped in the free-fall tower at low pressure state (0.2×105-0.5×105 Pa) to slow heat transfer by convection. After dash etching for 60 min, low pressure Si spheres have less etch pits, i.e., 80% for etch pit density and 8% for etch pit-area ratio compared to normal one. Furthermore, the conversion efficiency was improved from 6.57% (normal pressure spherical Si solar cell) to 9.56% (low one), which is 45% relative increase. The improvement is due to decrease of undercooling and increase of crystal growth duration. These results demonstrate that the dropping method at low pressure state is useful for fabricating high performance spherical Si solar cells.
