Evolution of metal plating for silicon solar cell metallisation

Abstract

Increasing silver prices and reducing silicon wafer thicknesses provide incentives for silicon solar cell manufacturing to develop new metallisation strategies that do not rely on screen printing and preferably reduce silver usage. Recently, metal plating has re‐emerged as a metallisation process that may address these future requirements. This paper reports on the evolution of metal plating techniques, from their use in early silicon solar cells, to current light‐induced plating processes. Unlike screen‐printed metallisation, metal plating typically requires an initial patterning step to create openings in a masking layer for the subsequent self‐aligned metallisation. Consequently, relevant recently‐developed dielectric patterning methods are also reviewed because, in many cases, the plating process must be adapted to the properties of the patterning method used. The potential of new light‐induced plating processes to form cost‐effective copper metallisation is supported by the recent activity in the development of metal plating tools for commercial silicon solar cell manufacture. Copyright © 2012 John Wiley & Sons, Ltd.

Improved adhesion of Ni/Cu/Ag plated contacts with thermally formed nickel silicon interface for C-SI solar cells

“…1(c), confirmed using EDS analysis. This NiSi x layer increases the contact adhesion between Ni and Si and is already been reported [8][9][10][11]. To deposit Cu in the subsequent step the Ni surface was activated by 2 minutes SPM etching at 40 °C.…”

“…The formation of Ni silicides, by heating the stacks of Ni over Si has been a useful way to increase the contact adhesion [8]. There have been reports showing promise to the adhesion promotion by silicide formation through the sintering process [9][10][11]. Si surface pretreatment was also used to achieve excellent adhesion for Ni/Cu plated contacts [11].…”

Recent Developments on Silicon Based Solar Cell Technologies and their Industrial Applications

“…Bifacial cells (device b) with the passivated diffused carrier collectors and either Al/Ag printed grid or Cu plated grid from both sides of the cell are being developed [53,54]. The Cu plated metallization increases both short circuit current and filling factor by achieving very thin fingers down to 30 micron width with low resistance, showing the potential of adopting the plating technology in solar industry [55]. IBC cells (device c) utilize the concept that both carrier collectors are formed at the rear side of the cell [56].…”

Electrical characterization of thermally-formed nickel silicide for nickel-copper plated solar cell contacts

“…Metal plating is one of several promising alternative to traditional silver screenprinted contacts. Many groups have recently studied the possibility of plated nickel-copper contacts, which aside from cost, may offer further benefits through reduced optical and electrical losses [2], [3].…”