Despite the high level of automation in semiconductor manufacturing processes, many manual operations are still involved in the workplace. Due to inadequate human-machine interface design, stairs are frequently used to help operators perform wafer-handling tasks. This study was designed to evaluate the effects of climbing stairs and carrying wafer containers (pods) on psychophysical responses (maximal acceptable weight of lift--MAWL, and ratings of perceived exertion--RPE), physiological responses (oxygen consumption--VO2, and heart rate--HR), and wrist posture (ulnar and radial deviations). Each of 12 subjects (six males and six females) performed six sessions (3 climbing stairs x 2 pods types). The results indicate that climbing stairs had a significant influence on MAWL and VO2 (p<0.01). The type of pod effect on wrist posture was significant (p<0.01). Gender effect differences on MAWL, VO2 and wrist posture were also significant (p<0.05). Job design implications are discussed.