Radio frequency identification system and method for tracking silicon wafers

• US 6,330,971 B1
• Filed: 10/03/2000
• Issued: 12/18/2001
• Est. Priority Date: 07/07/1998
• Status: Expired due to Term

• Current Assignee: GlobalWafers Co., Ltd. (Sino-American Silicon Products Incorporated)
• Original Assignee: SunEdison, Inc.
• Inventors: Rhodes, James Scott, Mabry, Frank Robert
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): FUREMAN, JARED
• Application Number:
  US09/677,909
• Time in Patent Office: 441 Days
• Field of Search: 235/375, 235/376, 235/384, 235/385, 235/492, 235/383, 340/10.52, 340/10.1, 340/10.5, 340/928, 342/374, 705/28, 705/29
• US Class Current: 235/383
• CPC Class Codes: G03F 7/70541 Tagging, i.e. hardware or software tagging of features or components, e.g. using tagging scripts or tagging identifier codes for identification of chips, shots or wafers
• CPC Class Codes: G03F 7/7075 Handling workpieces outside exposure position, e.g. SMIF box
• CPC Class Codes: H01L 21/67276 Production flow monitoring, e.g. for increasing throughput program-control systems per se G05B19/00, e.g. total factory control G05B19/418
• CPC Class Codes: H01L 21/67294 using identification means, e.g. labels on substrates or labels on containers

Abstract

A system and method for tracking semiconductor wafers through processing operations performed at a plurality of stations. A reader reads information relating to and identifying the wafers from a tag mounted on a wafer carrier. The tag has a memory which includes a plurality of pages storing the information. A plurality of antennas are connected to the reader. The antennas each have a transmission range which defines a reader position and the reader and tag communicate by radio frequency signals via one of the antennas when the carrier is at the respective reader position. A host computer and reader communicate in accordance with an interface protocol by which the host computer commands the reader to read the stored information from one or more selected tag pages and the reader provides the stored information read from the selected tag pages to the host computer.

Claims

1. A system for tracking semiconductor wafers through processing operations performed in a predetermined sequence at a plurality of stations, said wafers being loaded in one or more wafer carriers for transport between the stations, said system comprising:

a passive tag mounted on the carrier, said tag including a memory which has a plurality of pages storing information identifying the carrier and information relating to the wafers in the carrier and the sequence of processing operations to be performed at the stations, said stored information including information identifying the carrier and the processing operations, said information identifying the carrier being stored in a selected one of said tag pages and including data representative of a carrier identification address, said carrier identification address being stored in the selected one of the tag pages storing the information identifying the carrier and being permanently write-locked, said remaining tag pages including at least one reserved page to which information from another one of the pages is transferred in the event that the other page fails;

a reader for reading the stored information from the tag pages;

a plurality of antennas connected to the reader, each antenna being located proximate to one or more of the stations and having a transmission range which defines a reader position, said reader and tag communicating by radio frequency signals via one of the antennas when the carrier is at the respective reader position; and

a host computer for processing the stored information read by the reader to track the wafers, said host computer and reader communicating in accordance with an interface protocol by which the host computer commands the reader to read the stored information from one or more selected tag pages and the reader provides the stored information read from the selected tag pages to the host computer.

2. The system of claim 1 wherein the reader generates a radio frequency interrogation signal to initiate communication between the reader and the tag, said tag being responsive to the interrogation signal for generating a radio frequency reply signal when the carrier is at the respective reader position, said reader receiving the reply signal via the respective antenna and reading the stored information from the selected tag pages in response thereto.

3. The system of claim 1 wherein the reader is responsive to the host computer for writing information to one or more selected tag pages and wherein the interface protocol includes event messages from the reader to the host computer providing status information to the host computer regarding the wafer processing operations and includes associated command messages from the host computer to the reader selecting the tag pages to be read from or written to in response to the event messages.

4. The system of claim 3 wherein the event messages include data representing an event, data identifying the respective antenna and data identifying the carrier.

5. The system of claim 4 wherein the event messages are representative of one or more of the following events:

the reader is active, the carrier has arrived at the reader position, the carrier has been removed from the reader position and an error.

6. The system of claim 3 wherein the command messages include data representing a command, data identifying the respective antenna, data identifying the carrier and data identifying the selected tag pages.

7. The system of claim 6 wherein the command messages are representative of one or more of the following commands:

request information regarding reader position status, request that selected tag pages be read and request that information be written to selected tag pages.

8. The system of claim 3 wherein the interface protocol includes a status message from the host computer to the reader representative of the host computer being active.

9. The system of claim 1 wherein the information stored in the tag pages includes data representative of one or more of the following:

carrier identification address, wafer lot number, plant order, current operation, next operation and wafer count.

10. The system of claim 1 wherein the tag comprises a first tag and further comprising a second tag mounted on another carrier located at a different reader position, said first tag storing information relating to the wafers loaded in the respective carrier, and wherein the reader is responsive to the host computer for reading the stored information from the first tag and writing the stored information to the second tag.

11. The system of claim 1 further comprising a serial interface between the host computer and the reader.

12. The system of claim 1 further comprising a visual indicator associated with each antenna for providing status information to an operator of the system of the wafer processing operations occurring at the respective reader position.

13. The system of claim 12 wherein the visual indicator comprises a green light emitting diode and a red light emitting diode responsive to signals generated by the reader and/or the host computer.

14. A method of tracking semiconductor wafers through processing operations performed in a predetermined sequence at a plurality of stations, said wafers being loaded in one or more wafer carriers for transport between the stations, said method comprising the steps of:

mounting a passive tag on the carrier, said tag including a memory which has a plurality of pages storing information identifying the carrier and information relating to the wafers in the carrier and the sequence of processing operations to be performed at the stations;

storing information in the memory of the tag identifying the carrier and the processing operations, said information identifying the carrier being stored in a selected one of said tag pages and including data representative of a carrier identification address, said carrier identification address being stored in the selected one of the tag pages storing the information identifying the carrier, said remaining tag pages including at least one reserved page;

permanently write-locking the selected tag page storing the information identifying the carrier;

connecting a plurality of antennas to a reader for reading the stored information from the tag pages;

locating each antenna proximate to one or more of the stations, each antenna having a transmission range which defines a reader position;

communicating between the tag and the reader by radio frequency signals via one of the antennas when the carrier is at the respective reader position;

interfacing a host computer with the reader in accordance with an interface protocol by which the host computer commands the reader to read the stored information from one or more selected tag pages and the reader provides the stored information read from the selected tag pages to the host computer;

processing the stored information read by the reader with a host computer to track the wafers; and

transferring information to the reserved page from another one of the pages in the event that the other page fails.

15. A method of interfacing a radio frequency identification (RFID) system to a host computer, said RFID system including a tag having a memory which includes a plurality of pages for storing information and including a reader for reading information from the tag pages, said tag being mounted on a carrier for transporting semiconductor wafers between a plurality of stations in a predetermined sequence, said method comprising the steps of:

storing information identifying the carrier including data representative of a carrier identification address in a selected one of the tag pages, said remaining tag pages including at least one reserved page;

permanently write-locking the selected tag page storing the information identifying the carrier;

generating a radio frequency interrogation signal with the reader, said tag being responsive to the interrogation signal for initiating communication between the reader and the tag;

transmitting the interrogation signal with an antenna connected to the reader, said antenna having a transmission range which defines a reader position, said tag receiving the interrogation signal when the tag is at the reader position;

generating a radio frequency reply signal with the tag in response to the interrogation signal when the carrier is at the reader position; and

interfacing the host computer with the reader in accordance with an interface protocol, said interfacing step being responsive to the reply signal and including communicating unsolicited data messages from the reader to the host computer and communicating query commands from the host computer to the reader in response to the unsolicited data messages, said commands causing the reader to read the information from one or more selected tag pages in response to the data messages and to provide the information read from the selected tag pages to the host computer, said information identifying the carrier and relating to the wafers in the carrier and the sequence of processing operations to be performed at the stations; and

transferring information to the reserved page from another one of the pages in the event that the other page fails.

16. The method of claim 15 wherein the commands cause the reader to write information to one or more selected tag pages in response to the data messages.

17. The method of claim 15 wherein the data messages include data representing status information of an event, data identifying the respective antenna and data identifying the tag.

18. The method of claim 15 wherein the commands include data representing a command message, data identifying the respective antenna, data identifying the tag and data identifying the selected tag pages.

19. The method of claim 15 wherein the interfacing step includes communicating a status message from the host computer to the reader representative of the host computer being active.

20. The method of claim 15 further comprising the steps of reading the information from the selected tag pages and writing the information read from the selected tag pages to one or more selected pages of another tag.