Tempress a subsidiary of Amtech has developed an alternative atmospheric process called ‘High Density POCl3’ (Phosphorus Diffusion). The HD system benefits from the throughput advantage of small pitch, back-to-back, and long flatzone, while using improved chemistry and hardware upgrades to provide excellent uniformity and high efficiencies.
Problem
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POCl3 is a simple and well known process with excellent track record in process performance. The POCl3 process controls the formation of the emitter and defines the interface with the contacts. However, the drive to higher cell conversion efficiencies places increasingly more strict process control requirements for the POCl3 process, notably emitter resistivities, lower surface concentrations, better uniformities, while cost per-watt reductions and higher throughputs are required.
Solution
With the HD-POCl3 diffusion process, Tempress has focused on process innovation to increase throughput without the drawbacks (high cost/high maintenance) of complex low pressure systems. Tempress has increased the batch load of the POCl3 process to reduce the cost per-watt. The HDPOCl3 platform is said to enable emitter formation at around 35% lower cost per-watt compared to the conventional atmospheric POCl3 systems, and >10% lower cost per-watt compared to low pressure processing and produces stable high ohmic processing with up to 140 Ω/sq sheet resistance.
Applications
POCl3 diffusion process.
Platform
The HD-POCl3 platform contains improvements in furnace hardware, process gas chemistry and recipe structure. The 5-stack HD POCl3 the system is fully designed to processing >3200 wph. The furnace comes with an integrated automation system employing a 6 axis robot that allows that loading/unloading of a full HD
POCl3 load of 1000 wafers in under 15 minutes.
Availability
Currently available.