High productivity in-line screen printing system for crystalline solar cell manufacturing
To develop a high performance in-line screen-printing system, the NPC Group defined an appropriate benchmark for characterizing the industrial efficiency of the operation and carried out a full analysis of the factors affecting this benchmark. A screen-printing system design based on careful cost analysis can produce a machine with a high effective throughput and low cell breakage. As a result, NPC is now offering advanced in-line, high precision systems to the photovoltaic industry. Future design changes results in machine speeds of 1,600 wafers per hour at a breakage below 0.5% for the three prints typical of the current cell manufacturing process.
Hot melt ink technology for crystalline silicon solar cells
This paper presents a new thick film system for forming front and rear contacts on crystalline solar cells; the aim is to improve manufacturing throughput, reduce wafer breakage and improve cell efficiency. The Hot Melt ink technology presented differs from conventional thick film because unlike thick film ink that is a liquid at room temperature, the Hot Melt ink is a solid. The solid ink is processed using a resistively heated screen to melt the ink which then allows conventional screening. Once the ink is transferred to the wafer, maintained at approximately 25/spl deg/C, it instantly resolidifies, traditional drying processes are therefore unnecessary. By eliminating the drying processes, throughput and yield is increased due to reduced substrate handling. The resolidification property of the hot melt ink may be used to reduce line spreading of the front side contact and reduce shadow losses.
Anomalous Annealing Behavior of Arsenic Implanted Silicon as a Function of Dose and Energy
Anomalous annealing behavior of damage in As implanted Si has been investigated by channeling effect measurements. Room temperature As implants with doses from 1014 to 2 × 1016cm-2 at energies ranging from 50 to 250 keV into Si were annealed over the range of 600°C to 1100°C. Anneal temperatures ≥ 950°C reduce the disorder for ion doses of 0.5 to 1 × 1016 cm-2 at energies between 50 and 250 keV. Anomalously high residual disorder was found for the intermediate doses of 2 × 1014 to 2 × 10/cm2 implanted above 100 keV. For this intermediate dose, annealing of implants performed at liquid nitrogen temperatures did not show significant reduction in this damage. However implants at 200° to 300°C indicate a lower amount of damage compared to the room temperature implants.