POWER SWITCHING SYSTEM FOR ESC WITH ARRAY OF THERMAL CONTROL ELEMENTS

• US 20140154819A1
• Filed: 11/30/2012
• Published: 06/05/2014
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Gaff, Keith William, Comendant, Keith, Benjamin, Neil, Anderson, Tom, Lu, Ralph Jan-Pin, Robertson, Paul, Pape, Eric A.
• Granted Patent: US 10,049,948 B2
• Time in Patent Office: Days
• US Class Current: 438/17
• CPC Class Codes: H01L 21/67103 mainly by conduction
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/67248 Temperature monitoring
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A semiconductor substrate support for supporting a semiconductor substrate in a plasma processing chamber includes a heater array comprising thermal control elements operable to tune a spatial temperature profile on the semiconductor substrate, the thermal control elements defining heater zones each of which is powered by two or more power supply lines and two or more power return lines wherein each power supply line is connected to at least two of the heater zones and each power return line is connected to at least two of the heater zones. A power distribution circuit is mated to a baseplate of the substrate support, the power distribution circuit being connected to each power supply line and power return line of the heater array. A switching device is connected to the power distribution circuit to independently provide time-averaged power to each of the heater zones by time divisional multiplexing of a plurality of switches.

Claims

1. A semiconductor substrate support for supporting a semiconductor substrate in a plasma processing chamber, comprising:

a heater array comprising thermal control elements operable to tune a spatial temperature profile on the semiconductor substrate, the thermal control elements defining heater zones each of which is powered by two or more power supply lines and two or more power return lines wherein each power supply line is connected to at least two of the heater zones and each power return line is connected to at least two of the heater zones,

a power distribution circuit mated to a baseplate of the substrate support, the power distribution circuit connected to each power supply line and power return line of the heater array; and

a power switching device connected to the power distribution circuit to independently supply power to each one of the heater zones via one of the power supply lines and one of the power return lines so as to provide time-averaged power to each of the heater zones by time divisional multiplexing of a plurality of switches.

2. The semiconductor substrate support of claim 1, wherein the power distribution circuit is formed on a first circuit board, the first circuit board having a conductive common plane that is attached to the baseplate and is at a electrical potential of the baseplate.

3. The semiconductor substrate support of claim 1, wherein the power switching device comprises a switching circuit and a control circuit.

4. The semiconductor substrate support of claim 2, wherein the power switching device is formed on the first circuit board.

5. The semiconductor substrate support of claim 3, wherein the power switching device is formed on the first circuit board

6. The semiconductor substrate support of claim 1, comprising:

a facilities plate attached to the baseplate of the substrate support such that at least the power distribution circuit is located in an electrostatically-shielded volume between the baseplate and the facilities plate.

7. The semiconductor substrate support of claim 6, wherein the power distribution circuit is formed on a first circuit board, the first circuit board having a conductive common plane that is attached to the baseplate and is at a electrical potential the baseplate.

8. The semiconductor substrate support of claim 7, wherein the switching device is formed on a second circuit board, the second circuit board having a conductive common plane that is attached to the facilities plate and is at a DC electrical of the facilities plate.

9. The semiconductor substrate support of claim 8, wherein the second circuit board is attached to an upper surface of the facilities plate and in a recess of the facilities plate, such that the second circuit board is within the RF-shielded volume between the baseplate and the facilities plate.

10. The semiconductor substrate support of claim 6, wherein the RF-shielded volume between the baseplate and the facilities plate is a first RF-shielded volume, the substrate support further comprising:

a metal cage attached to the facilities plate such that a second RF-shielded volume is formed between the metal cage and the facilities plate.

11. The semiconductor substrate support of claim 10, wherein the second RF-shielded volume is below the first RF-shielded volume.

12. The semiconductor substrate support of claim 11, wherein the power distribution circuit is formed on a first circuit board, the first circuit board having a conductive common plane that is attached to the baseplate wherein the conductive common plane is at a DC electrical of the baseplate.

13. The semiconductor substrate support of claim 12, wherein the power switching device is formed on a second circuit board, the second circuit board is DC isolated from ground and having a conductive common plane that is floated from ground and electrically connected to the facilities plate to maintain substantially the same DC potential of the facilities plate.

14. The semiconductor substrate support of claim 13, wherein the second circuit board is attached to a lower surface of the facilities plate, such that the second circuit board is within the second RF-shielded volume between the metal cage and the facilities plate.

15. The semiconductor substrate support of claim 6, further comprising:

an electrically conductive gasket between outer peripheries of the baseplate and the facilities plate.

16. The semiconductor substrate support of claim 8, wherein the second circuit board of the power switching device is attached to a first surface of the facilities plate and comprises the plurality of switches as transistors on at least one surface of the second circuit board, each transistor extending between the first surface of the facilities plate and a second surface of the facilities plate, and wherein at a point of termination on the second surface of the facilities plate, the plural transistors are sealed from RF with a sealing member.

17. The semiconductor substrate support of claim 1, comprising:

at least one capacitor between each return line and the baseplate to shunt RF between the baseplate and the heater array so that the baseplate and the heater array are at a same RF potential.

18. The semiconductor substrate support of claim 1, comprising:

at least one RF filter configured to receive one of electrical power from a source and provide conditioned electrical power, respectively to the heater array via the switching device and the distribution circuit.

19. The semiconductor substrate support of claim 7, wherein each of the first and second circuit boards comprise plural signal wiring or traces and filtering elements connected between each trace and respective conductive common voltage planes.

20. The semiconductor substrate support of claim 1, wherein the power distribution circuit includes memory that stores at least one of configuration data, identification data, operating data of the power switching device.

21. The semiconductor substrate support of claim 1, comprising:

a communication module that provides wireless communication between the power switching device and a processor external to the plasma processing chamber.

22. The semiconductor substrate support of claim 21, wherein the power switching device is configured to encrypt and decrypt data signals communicated with the external processor.

23. The semiconductor substrate of claim 9, wherein the first circuit board is attached to a lower surface of the baseplate and in a recess of the baseplate.

24. The semiconductor substrate of claim 23, wherein the recesses of the baseplate and the facilities plate establish an RF shielded volume such that when RF is applied to the facilities plate RF current flows around the first and second circuit boards along outer surfaces of the facilities plate and the baseplate.

25. A method of etching a semiconductor substrate in a plasma processing chamber, the plasma processing chamber having an electrostatic chuck assembly for supporting the substrate during plasma processing, the electrostatic chuck assembly including a baseplate and a heater array comprising thermal control elements operable to tune a spatial temperature profile on the semiconductor substrate, the thermal control elements defining heater zones each of which is powered by two or more power supply lines and two or more power return lines wherein each power supply line is connected to at least two of the heater zones and each power return line is connected to at least two of the heater zones, the electrostatic chuck assembly being mated to a power distribution assembly via the baseplate, the power distribution assembly including a power distribution circuit connected to each power supply line and power return line of the heater array and a power switching device connected to the power distribution circuit, the method comprising:

independently supplying power to each one of the heater zones via one of power supply lines and one of power return lines to provide time-averaged power to each of the heater zones by time-divisional multiplexing of a plurality of switches of the power switching device.

26. The method of claim 25, further comprising:

communicating command and control messages between the power distribution assembly and an external processor.

27. The method of claim 25, wherein electrostatic chuck assembly comprises a facilities plate and the power distribution assembly is mounted to at least the baseplate in an RF-shielded enclosure between the baseplate and the facilities plate, the method further comprising:

supplying RF power to the facilities plate such that RF current flows along outer surfaces of the facilities plate and the baseplate and around the RF-shielded enclosure.

28. The method of claim 25, comprising:

monitoring various parameters including at least one of temperature, voltage, and current via sensors of the power distribution assembly.

29. The method of claim 28, comprising:

storing values associated with the monitored parameters in memory.