We introduced the use of hydrogen during the deposition of spin valves to achieve better control of interfacial mixing, especially for bottom spin valves (B-SV). The hydrogen was introduced during deposition of the CoFe or IrMn layer depending on whether it was a B-SV or a top spin valve (T-SV). The magnetoresistance ratio and Hex increased to 15% and 30%, respectively, when hydrogen (10vol%) was introduced for a B-SV. By contrast, the hydrogen effect for a T-SV was small. Using hydrogen (10vol%), the surface of the SV was smoother (1.01nm) than without hydrogen (1.94nm). In addition, the SV with hydrogen had a well-developed (111) texture and larger grains. By introducing hydrogen, we could control the microstructure and reduce the intermixing between CoFe and IrMn, especially for B-SVs.