In this research, magnetoresistance (MR) ratio (MR), resistivity, and exchange coupling field $(H_{ex})$ behaviors for sputter deposited spin valves with FeMn antiferromagnetic layer have been extensively investigated by rapid thermal annealing (RTA) as well as conventional annealing (CA) method. 10 s of RTA revealed that interdiffusion was not significant up to $325^{circ}C$ at the interfaces between the layers when the RTA time was short. The MR of FeMn spin valves were reduced when the spin valves were exposed to temperature of $250^{circ}C$, even for a short time period of 10 s prior to CA. $H_{ex}$ was maintained up to $325^{circ}C$ of CA when the specimen was subjected to 10 s of RTA at $200^{circ}C$ prior to CA, which is $25^{circ}C$ higher than the result obtained from the CA without prior RTA. Therefore, the stability of $H_{ex}$ could be enhanced by a prior RTA before performing CA up to annealing temperature of $325^{circ}C$. MR and sensitivity of the specimens annealed without magnetic field up to $275^{circ}C$ were recovered to the values prior to CA, but $H_{ex}$ was not recovered. This means that reduced MR sensitivity and MR during the device fabrication can be recovered by a field RTA.