Substrate processing system, load port and method

A load port for a wafer processing system, the load port comprising:

• a first cassette support configured to support thereon a first cassette containing a first lot of wafers;
• at least one first sensor coupled to the first cassette support and configured to generate a first weight signal corresponding to a first total weight of the first cassette and the first lot of wafers;
• a second cassette support configured to support thereon a second cassette containing a second lot of wafers;
• at least one second sensor coupled to the second cassette support and configured to generate a second weight signal corresponding to a second total weight of the second cassette and the second lot of wafers;
• and
• a microcontroller (MCU) coupled to the at least one first sensor and the at least one second sensor to receive the first weight signal and the second weight signal, respectively, the MCU configured to
• convert a weight difference between the first total weight and the second total weight into a number of wafers each having a predetermined weight,
• generate an indicator indicating whether the first lot of wafers is heavier or lighter than the second lot of wafers, and
• output the indicator and the converted number of wafers to a controller of a processing apparatus of the wafer processing system to enable the controller to control the processing apparatus to balance a rotation of the first lot of wafers and the second lot of wafers simultaneously.

A method, comprising:

• obtaining a weight difference between a first weight of a first lot of substrates and a second weight of a second lot of substrates;
• converting the weight difference into a number of substrates each having a predetermined weight;
• generating an indicator indicating whether the first weight is heavier or lighter than the second weight;
• and
• based on the converted number of substrates and the indicator, controlling a processing apparatus to balance a rotation of the first lot of substrates and the second lot of substrates simultaneously.