Additive Design for High Deposition Rate Permalloy Bath

The electrodeposition of magnetic thin films has found wide application in fabrication of magnetic recording and microelectronics devices. Permalloy, as the most widely used magnetic alloy is finding more and more applications in the situations where thicknesses regime of deposited films is above several microns, (power electronics, analog electronic devices or MEMS). The performance of traditional Permalloy plating baths based on saccharine as an additive are becoming unreliable and new additives and bath designs are necessary to ensure high quality deposits and high deposition rates. In this talk we will present our recent work on additive and bath design for high deposition rate Permalloy baths. The systematic studies of several organic molecules/additives have been performed including L-Cysteine (LC), N-Acetyl L-Cysteine (NAC), L-Methionine (LM), and Thiamine Hydrochloride (THC). The bath design for each additive has been optimized to ensure 80Ni:20Fe at% composition for different additive concentrations. The magnetic properties (Coercivity and magnetic moment) of Permalloy films has been studied as a function of each additive concentration in the bath, and the most optimum bath design for each additive has ben found and compared against the saccharine baths used as benchmark, Figure 1. In addition to magnetic softness as the main control parameter, the different additives were studied as a function of the Permalloy deposition rate. The additives and the bath designs with the highest deposition rates were identified leading to the overall optimum Permalloy bath design yielding the softest films and the highest deposition rates. Figure 2.