Abstract: Magnetron sputtering is a semiconductor processing technology which sputters large area and high quality films such as GMR which is widely used in magnetic sensor and magnetic storage.As GMR element in small size has Barkhausen noise problem,a CoCrPt hard magnetic film is sputtered right next to the GMR element to provide magnetic bias and largely reduce the noise.A wet etching with 1:5 BHF solution is used to align the two films.The etching rate is 25 Å/s.A new structure of the seed layer for CoCrPt is used which makes it possible to sputter this film at room temperature.All the processes enhance application scope of micro-devices base on GMR.