Magnetoresistive head production method

In a production process for producing an MR head having a lower shield layer formed on a substrate;

• a lower electrode layer formed on the lower shield layer or shared with the lower shield layer;
• a longitudinal bias layer formed at two positions on the lower electrode layer viewed from an ABS;
• a free layer formed on the longitudinal bias layer and the lower electrode layer;
• a barrier layer formed on the free layer;
• a tunnel junction film having the free layer, the barrier layer, a pinned layer, and a pinning layer successively formed in this order on the barrier layer where the longitudinal bias layer is not formed;
• a first upper electrode layer formed on the pinning layer;
• an insulation layer formed on the barrier layer where the longitudinal bias layer is formed;
• a second upper electrode layer formed on the insulation layer and the first upper electrode layer;
• and an upper shield layer formed on the second upper electrode layer or shared with the second upper electrode layer;
• the improvement comprising the steps of:
• a first step of forming a production resistance value during the production process of the MR head, between the free layer and the pinned layer smaller than a MR head resistance value when used as the MR head;
• and
• a second step of increasing the production resistance value formed in the first step during the production process of the MR head, to the MR head resistance value when used as the MR head.