Source: {"pile_set_name": "USPTO Backgrounds"}

Electronic device manufacturing systems may include multiple process chambers and load lock chambers. Such chambers may be included in cluster tools where a plurality of process chambers may be distributed about a transfer chamber, for example. These tools may employ articulated robots or multi-arm robots, which may be housed within the transfer chamber and transport substrates between the various process chambers and load lock chambers. For example, the robot may transport substrates from chamber to chamber, from load lock chamber to process chamber, and/or from process chamber to load lock chamber. Efficient and precise transport of substrates between the various system chambers may improve system throughput, thus lowering overall operating costs.
Furthermore, precise substrate placement may improve overall processing quality. In many dual-bladed robots, Selective Compliant Articulated Robot Arm (SCARA) robots are employed. Each SCARA robot employs three arms (upper arm, forearm, and wrist) driven by one motor. An end effector may be coupled to the wrist and may be used to carry a substrate to or from a pick or place destination such as a process chamber or a load lock chamber. In dual-bladed SCARA robots, where a SCARA robot is coupled to opposite ends of a boom, problematically, such SCARA robots may suffer from certain misalignment problems. Additionally, in SCARA robots that are not dual-bladed, certain misalignment problems may also occur.
Accordingly, this disclosure is directed at improved methods, systems, and apparatus for efficient and precise orientation of end effectors.