Particulate-contamination-free wafer-handling systems for gas, liquid and vacuum environments used in a 64 Mbyte dynamic random-access memory process

Abstract

Devices which establish particle-free wafer handling for gas, liquid and vacuum environments used in a 64 Mbyte dynamic random-access memory (DRAM) process were developed. A non-contact handler was developed as a handling device for use in a gas environment, such as air or nitrogen, which keeps wafers clean without touching them through the mutual action of gas suction and blow-out. Also, a non-contact gas levitation track was developed for use in a gas environment, which levitates, transfers and guides wafers without any contact using the fluid force of gas blow-out with a very low velocity. A liquid levitation transport track was developed for use in a liquid environment, which transports wafers without exposing them to atmosphere using the fluid forces of liquid jets. An electrostatic chuck was developed as a device for use in a vacuum environment which holds a wafer by a Coulomb attractive force. This electrostatic chuck is used as the hand of a wafer handler and the holding system of a wafer stage. These devices were applied to actual manufacturing processes and it was confirmed that they are effective for reducing wafer contamination. Automation of the manufacturing line in the 64 Mbyte DRAM process for the future is attempted with these devices.