Implementation of a Multicrystalline ALD-Al2O3-PERC Technology into an Industrial Pilot Production
Creators: name: Sastrawan, R.
name: Pysch, D.
name: Bijker, M.
name: Delahaye, F.
name: Dielissen, B.
name: Eipert, W.
name: Gay, X.
name: Görtzen, R.
name: Hoffmann, A.
name: Latzel, B.
name: Lenes, M.
name: Mao, X.
name: Patzig-Klein, S.
name: Qu, X.
name: Sander, B.-U.
name: Schmitt, C.
name: Souren, F.M.M.
name: Träger, A.
name: Weise, K.
name: Yang, S.
name: Nussbaumer, H.
Publisher: name: WIP
Year: 2013
Subjects: WAFER-BASED SILICON SOLAR CELLS AND MATERIALS TECHNOLOGY
Silicon Solar Cell Improvements

description: 28th European Photovoltaic Solar Energy Conference and Exhibition; 1861-1866
description: In this paper, we present results of the implementation of the InPERC technology into an industrial pilot
production of a major Chinese cell manufacturer. The process sequence utilizes all production equipment of the
standard production line for screen printed full area Al+BSF solar cells. In addition, the rear surface is
smoothened. For this purpose, the hardware of one existing standard InOxSide for wet chemical edge isolation is
upgraded to InOxSide
+
without changing the footprint of the tool. The rear side is passivated using SoLayTec’s
InPassion ALD mass production machine for ultrafast spatial atomic layer deposition (ALD) of Al2O3. The SiNx
capping layer is deposited using standard PECVD equipment of the existing production line. Furthermore, a laser
is used to open the rear side contacts prior to screen printing the metallization.
In a first step, the InPERC ALD technology was developed on CZ+Si 156 x 156 mm² wafers at RENA. Average
cell efficiencies of 19.5% were achieved with screen+printed metallization and without selective emitters: an
increase of about 1%abs compared to our full Al+BSF baseline of about 18.5%. It was found that a surface
smoothening by removal of about 4 μm is sufficient to reach implied Voc values of over 700 mV and 680 mV for
CZ+Si and mc+Si material, respectively. This leads to an efficiency gain of up to 0.5%abs due to surface
smoothening. The passivation quality of the layer stack is significantly improved by an annealing step after the
ALD process. It was successfully shown that by using an optimized recipe for the PECVD process of the capping
layer this post deposition anneal (PDA) can be skipped. Thus, the full potential of the excellent passivation
quality of ALD Al2O3 can be obtained at lowest cost of ownership. It was found, that – by use of a suited laser
and aluminum paste – damage to the silicon by the laser ablation can be healed effectively by a deep formation of
the local Al+BSF. The full potential of the InPERC technology was demonstrated at RENA with direct Ni/Ag
plating as front side metallization and FireFOXTM as front passivation. A best efficiency of 20.3% was achieved.
The InPERC ALD technology on CZ+Si was transferred to a mc+Si industrial pilot production of a major Chinese
cell manufacturer. It was found that an Al2O3 layer thickness of 7 nm and even 4 nm could be applied without
loss in efficiency, further reducing cost of ownership. On mc+Si material efficiency gains of about 0.6%abs were
demonstrated. Top average efficiencies of 18.0% could already be achieved up to now without a selective emitter.