Patent ID: 6197364
Filing Date: 2001-03-06
Classification: C23C,G11B,H01F

Abstract:
A method of depositing from a single electroless plating bath a Co(P) magnetic film on a substrate, said Co(P) film having a variable coercivity of between about 510 Oe and 1.6 Oe, comprising the following steps:(a) preparing an electroless plating solution consisting essentially of a source of cobalt ions, a source of citrate ions, a buffering compound to stabilize the pH of said plating solution, a source of hypophosphite ions and sufficient hydroxide anions to obtain a pH between about 7 and 9 and a sulfamate non-reactant compound selected from the group consisting of sodium sulfamate, potassium sulfamate, and sulfamic acid, said sulfamate compound present in concentrations ranging from trace amounts to 0.2M to obtain a plating solution; and(b) immersing said substrate in said plating solution for a time sufficient to produce, at a constant rate, a film on said substrate, said film having a range of coercivities between about 1.6 Oe and 510 Oe, the exact coercivity of said film having a direct linear relationship to the concentration of said sulfamate compound, such that trace amounts of sulfamate compound result in a film having a coercivity of about 510 and 0.2M sulfamate compound results in a film having a coercivity of about 1.6 Oe, any specific concentration of sulfamate compound in said plating solution resulting in a corresponding specific coercivity as a result of the proportional relationship between sulfamate concentration and coercivity,said variation in coercivity of said Co(P) film being achieved by varying the concentration of said sulfamate compound while concurrently holding constant the concentration of reactants, complexing agents, --OH, pH, of said plating solution and the temperature thereof and agitation during plating.