Cluster tool techniques with improved efficiency

A method, comprising:

• sending a first lot of wafers from a first load port to a transfer load lock in a cluster tool;
• transferring the first lot of wafers from the transfer load lock to a designated storage load lock through a first transfer chamber in the cluster tool;
• sending a second lot of wafers from a second load port to the transfer load lock;
• and
• transferring the second lot of wafers from the transfer load lock to the designated storage load lock through the first transfer chamber while the first lot of wafers is in the transfer load lock or the designated storage load lock;
• wherein the designated storage load lock has the same structure as the transfer load lock and respectively has an inner load lock portal at an interface with the first transfer chamber, wherein the inner load lock portal of the designated storage load lock is retained opened during processing;
• wherein the designated storage load lock and the transfer load lock respectively has an outer load lock portal on a sidewall of a front end interface, wherein the outer load lock portal of the designated storage load lock is retained closed during processing.

A method, comprising:

• providing a plurality of wafer carriers to a front end interface of a cluster tool, wherein each of the plurality of wafer carriers holds a lot of wafers;
• transferring N+1 or more lots of wafers from the front end interface to a transfer load lock;
• transferring the N+1 or more lots of wafers from the transfer load lock to a designated storage load lock in the cluster tool such that the N+1 or more lots of wafers are present in the cluster tool at the same time, wherein N is an amount of wafer carriers in the front end interface, wherein the N+1 or more lots of wafers transferred to the designated storage load lock form initial lots of wafers;
• transferring a first group of wafers of the initial lots of wafers from the designated storage load lock to a pre-clean chamber in the cluster tool for a pre-clean process;
• transferring the first group of wafers of the initial lots of wafers to an epitaxial deposition chamber in the cluster tool after the pre-clean process;
• transferring the first group of wafers of the initial lots of wafers to the designated storage load lock after the first group of wafers of the initial lots of wafers has passed through the epitaxial deposition chamber;
• transferring the first group of wafers of the initial lots of wafers from the designated storage load lock back to the transfer load lock;
• and
• sending the first group of wafers of the initial lots of wafers out of the cluster tool from the transfer load lock;
• wherein the designated storage load lock has the same structure as the transfer load lock, and wherein the designated storage load lock and the transfer load lock respectively has an inner load lock portal and an outer load lock portal on a sidewall of the front end interface;
• wherein the outer load lock portal of the designated storage load lock is retained fixedly closed during loading, unloading and processing the wafer;
• and wherein the inner load lock portal of the designated storage load lock is retained opened during loading, unloading and processing the wafer.