Method for patterning magnetic films

Abstract

A method of patterning magnetic devices and sensors by double etching, which includes forming a layer of dielectric on a substrate; depositing a thin adhesion layer and a thin seed layer; applying a thin resist frame to pattern a structure; cleaning the metal surface to prepare for plating; electroplating to fill up the structure and the uncovered field area, which uses a paddle cell with a permanent magnet providing magnetic field to induce magnetic orientation; stripping the resist frame; etching the seed layer/adhesion layer exposed below the resist frame down to the dielectric surface; etching the rest of magnetic materials and the seed layer using electrolytic etching in the field; etching the adhesion layer in the field, and repeating the steps for building structures with multiple levels.

1 . A method of patterning magnetic devices and sensors by double etching, which comprises:
 forming a layer of dielectric on a substrate;   depositing a thin seed layer or a combination of adhesion layer and seed layer;   applying a thin resist frame to pattern a structure;   cleaning the metal surface to prepare for plating;   electroplating to fill up the structure and the uncovered field area, which uses a paddle cell with a permanent magnet providing magnetic field to induce magnetic orientation stripping the resist frame;   etching the seed layer/adhesion layer exposed below the resist frame down to the dielectric surface;   etching the rest of magnetic materials and the seed layer by electrolytic etch.; and   etching the adhesion layer in the field.   
     
     
         2 . The method of  claim 1 , above steps are repeated for a multiple level build. 
     
     
         3 . The method according to  claim 1 , wherein the substrate is selected from the group consisting of silicon, quartz, glass, sapphire, metal, gallium nitride, gallium arsenide, germanium, silicon-germanium, indium-tin-oxide, alumina, and plastic. 
     
     
         4 . The method according to  claim 1 , wherein the dielectric layer is selected from the group consisting of silicon oxide, silicon oxynitride, low-k dielectric, and a polymer such as a polyimide, or resist; 
     
     
         5 . The method according to  claim 1 , wherein the thin adhesion layer is selected from the group consisting of Ta, TaN, Ti, TiN, Cr, combinations thereof. 
     
     
         6 . The method according to  claim 1 , wherein the thin seed layer is selected from Ni, Fe, Co, Cu, Ru, Rh, Ag, Ag, Zn, and the alloys thereof. 
     
     
         7 . The method according to  claim 1 , wherein the thin seed layer/adhesion layer has a thickness from about 5 nm to about 500 nm. 
     
     
         8 . The method according to  claim 1 , wherein the thin seed layer/adhesion layer is deposited by PVD, CVD, or by electroless techniques. 
     
     
         9 . The method according to  claim 1 , wherein the cleaning before electrodeposition can be ashing in reducing gas, such as forming gas, ammonia, or hydrogen, or chemical cleaning, such as acid rinse, or physical clean, such as sputtering etch. 
     
     
         10 . The method according to  claim 1 , wherein the electroplating is carried out employing a current density of about 1 to about 100 milliamps/cm 2 . 
     
     
         11 . The method according to  claim 1 , wherein the electroplating is carried out at temperatures of about 10° C. to about 80° C. 
     
     
         12 . The method according to  claim 1 , wherein the electroplating is carried out employing a current waveform of about 5 to about 20 milliamps/cm 2 . 
     
     
         13 . The method according to  claim 1 , wherein the electroplating is carried out by a paddle cell with a magnetic field applied during the deposition. 
     
     
         14 . The method according to  claim 1 , wherein the seed layer/adhesion layer etching is carried out by dry etching, sputtering etch, reactive-ion etching (RIE), wet-chemical etching, or ion-beam etching. 
     
     
         15 . The method according to  claim 1 , wherein the electrolytic etching uses external current/potential supply to dissolve the metal film in contact with the power, with the metal film being electrically connected to the anode (or positive potential), and a counter electrode connected to the cathode. The solution can be sodium chloride with pH range between −1 to 3 or any other desired chemicals specific to the metal to be etched. 
     
     
         16 . The method according to  claim 1 , wherein the electrolytic etching uses a current density range between 10 milliamps to 10 amps.