Material and process evaluation

In addition to reference solar cell processes, ISFH also offers cross-processing for the evaluation of individual processes and materials. This allows you to compare your materials (e.g. Si wafers or metal pastes) and processes (e.g. wet-chemical cleaning, diffusion, laser processing) with our established benchmark or have interactions with other processes investigated (e.g. your new dielectric layer with laser ablation). Depending on customer requirements, this also includes the provision of different silicon materials as well as the electrical and optical characterization.

We have very extensive and state-of-the-art equipment for the processing of semiconductors: starting with cleaning and etching processes, plasma-assisted deposition of passivation layers, laser processing, diffusion and oxidation up to metallization by screen printing, evaporation or sputtering processes.

A selection of individual processes:

Wet-chemical processes

• Etch-back of saw damage or highly doped surfaces
• Alkaline texture
• PSG/BSG etch
• RCA cleaning
• HF/HCl cleaning
• Chemical polishing
• Edge isolation
• One-sided etching of SiO_x

Plasma deposition

• PECVD-SiN (SiNA, Roth&Rau)
• Plasma and Spatial ALD AlO_x (Oxford Instruments and SolayTec)
• PECVD deposition of SiO₂ layers containing boron and phosphorus (“doped oxides”, for use as dopant source)
• TCO

Laser processing

• Ablation of dielectric layers
• Laser doping to form the selective emitter or front surface field
• Melting of metallic or metal-containing layers for electrical (LFC) and/or mechanical (AMELI) contacting
• Cutting, drilling and marking of silicon, glass and metallic foils

High-temperature processes

• Phosphorus diffusion (POCl₃)
• Boron diffusion (BBr₃)
• Oxidation (wet and dry)
• Annealing process after ion implantation
• Formation of POLO contacts
• Co-Diffusion with doped oxides

Metallization

• Screen printing (single, dual, triple print)
• Aluminum PVD
• Sputtering of Ag, Ni, SiO