Ohmic contacts between Au and p-type $Hg_{0.7}Cd_{0.3}Te$ with low specific contact resistance have been obtained. The contact region of the wafer is first pre-heated for 5 seconds in a rapid thermal processing equipment. Ag is used as a reflective material in a rapid thermal process employing tungsten halogen lamps because it has a high reflectivity over the visible and infrared region. Thus, the direct thermal damage of the wafer can be reduced by coating Ag film over the non-contact surface of the wafer, providing local heating only to the contact region. The radiation intensity of the lamps arriving at the wafer surface is estimated to be about 6w/㎠ and the temperature reaches a maximum value of about 200℃ at the end of the 5 seconds. Next, thin Au film is formed on the contact region by immersing the sample in $AuCl_3$ solution. The sample is then post-annealed in the same condition as that of the pre-heating after Pb/In pad metals are deposited on the electroless Au contacts. The specific contact resistance measured by transmission line model is $5\times10^{-3}$ Ω-㎠ at 80K. Since the proposed method is a rapid process lasting only 5 seconds, it is expected to be harmless to the device performance due to the reduced thermal energy to the HgCdTe substrate which is sensitive to high temperature process.
