Electrostatic chuck including declamping electrode and method of declamping

• US 9,101,038 B2
• Filed: 12/20/2013
• Issued: 08/04/2015
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Kimball, Christopher, Gloski, Tyler, Singh, Harmeet, Gaff, Keith
• Primary Examiner(s): PATEL, DHARTI HARIDAS
• Application Number:
  US14/136,826
• Publication Number:
  US 20150181683A1
• Time in Patent Office: 592 Days
• Field of Search: 361/234
• US Class Current: 1/1
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks

Abstract

A semiconductor wafer processing apparatus for processing semiconductor wafers comprises a semiconductor wafer processing chamber in which a semiconductor wafer is processed, a process gas source in fluid communication with the processing chamber adapted to supply process gas into the processing chamber, a vacuum source adapted to exhaust process gas and byproducts of the processing from the processing chamber, and an electrostatic chuck assembly. The electrostatic chuck assembly comprises a support surface in a layer of ceramic material on which the semiconductor wafer is supported during processing of the wafer in the chamber, at least one electrostatic clamping electrode embedded in the layer of ceramic material, the at least one electrostatic clamping electrode operable to apply an electrostatic clamping force to the wafer on the support surface when an electrostatic clamping voltage is applied to the clamping electrode, and at least one declamping electrode embedded in the layer of ceramic material above the at least one electrostatic clamping electrode operable to provide a path for draining any residual charge between the wafer and the support surface when the electrostatic clamping voltage is no longer applied to the clamping electrode.

Claims

1. A semiconductor wafer processing apparatus for processing semiconductor wafers, comprising:

a processing chamber in which a semiconductor wafer is processed;

a process gas source in fluid communication with the processing chamber adapted to supply process gas into the processing chamber;

a vacuum source adapted to exhaust process gas and byproducts of the processing from the processing chamber; and

an electrostatic chuck assembly comprising a support surface in a layer of ceramic material on which the semiconductor wafer is supported during processing of the wafer in the chamber;

at least one electrostatic clamping electrode embedded in the layer of ceramic material, the at least one electrostatic clamping electrode operable to apply an electrostatic clamping force to the wafer on the support surface when an electrostatic clamping voltage is applied to the clamping electrode; and

at least one declamping electrode embedded in the layer of ceramic material above the at least one electrostatic clamping electrode operable to provide a path for draining any residual charge between the wafer and the support surface when the electrostatic clamping voltage is no longer applied to the clamping electrode.

2. The processing apparatus of claim 1, wherein the electrostatic chuck assembly further comprises a mesa pattern, comprising a plurality of mesas, on the support surface wherein the at least one electrostatic clamping electrode is patterned such that the at least one electrostatic clamping electrode is not directly below a mesa of the plurality of mesas and/or the at least one electrostatic declamping electrode is patterned such that the at least one electrostatic declamping electrode is not directly below a mesa of the plurality of mesas.

3. The processing apparatus of claim 1, wherein

(a) the at least one electrostatic clamping electrode includes at least one pattern of an electrically conductive material, and the at least one declamping electrode includes at least one pattern of an electrically conductive material wherein the at least one pattern of the clamping electrode and the at least one pattern of the declamping electrode overlap and have the same pattern;

and/or

(b) the at least one electrostatic clamping electrode and the at least one declamping are not directly below any surface which supports the wafer.

4. The processing apparatus of claim 1, wherein the at least one electrostatic clamping electrode includes an annular clamping electrode beneath an outer annular edge seal of the support surface and the at least one electrostatic declamping electrode includes an annular declamping electrode beneath the outer annular edge seal of the support surface wherein the annular declamping electrode is above the annular clamping electrode.

5. The process apparatus of claim 1, wherein:

(a) the at least one declamping electrode is about 10 microns or less beneath the upper surface of the support surface of the electrostatic chuck assembly; and

/or

(b) the at least one clamping electrode is about 100 microns or more beneath the upper surface of the support surface of the electrostatic chuck assembly.

6. The processing apparatus of claim 1, wherein:

(a) the electrostatic chuck assembly further comprises at least one outlet in the support surface which delivers a heat transfer gas to an underside of the wafer, and at least one gas passage in the layer of ceramic material connected to a source of heat transfer gas operable to supply heat transfer gas at a desired pressure to the at least one gas passage;

(b) a lower surface of the layer of ceramic material of the electrostatic chuck assembly is bonded to an upper surface of a heater plate, and a lower surface of the heater plate is bonded to an upper surface of a temperature controlled baseplate;

(c) the electrostatic chuck assembly further comprises lift pins operable to lower the wafer onto the support surface of the electrostatic chuck assembly and to raise the wafer from the support surface of the electrostatic chuck assembly;

(d) the processing apparatus further includes a RF energy source adapted to energize the process gas into a plasma state in the processing chamber; and

/or

(e) the electrostatic chuck assembly further includes a heater layer which includes independently controllable heater zones.

7. The processing apparatus of claim 1, wherein the electrostatic clamping electrode is a monopolar or bipolar electrostatic clamping electrode.

8. The processing apparatus of claim 1, further comprising a control system configured to control processes performed by the processing apparatus and a non-transitory computer machine-readable medium comprising program instructions for control of the processing apparatus.

9. The processing apparatus of claim 1, wherein the at least one declamping electrode is an annular declamping electrode beneath an outer annular edge seal of the support surface wherein the annular declamping electrode is above the clamping electrode and/or the at least one declamping electrode is an annular declamping electrode beneath an inner annular edge seal of the support surface wherein the annular declamping electrode is above the clamping electrode.

18. A method of declamping a semiconductor wafer from a support surface of an electrostatic chuck assembly after processing the semiconductor wafer in the apparatus according to claim 1, comprising:

supplying the process gas from the process gas source into the processing chamber; and

processing a semiconductor wafer in the processing chamber while applying a voltage to the at least one electrostatic clamping electrode so as to clamp the semiconductor wafer to the support surface of the electrostatic chuck assembly while electrically floating the at least one declamping electrode during the processing; and

shutting off the voltage to the electrostatic clamping electrode and electrically connecting the declamping electrode to a conductive path after processing the semiconductor wafer to provide a path for draining any residual charge between the wafer and the support surface with the at least one declamping electrode thereby declamping the wafer from the support surface of the electrostatic chuck assembly.

19. The method of claim 18, and

(a) grounding the conductive path or connecting the conductive path to a voltage source to drain any residual charge between the wafer and the support surface;

and/or

(b) raising the wafer from the support surface of the electrostatic chuck while draining any residual charge between the wafer and the support surface.

20. The method of claim 18, wherein the processing comprises supplying RF energy into the plasma processing chamber thereby generating the process gas into plasma and plasma etching the wafer, or performing a deposition process.

10. An electrostatic chuck assembly useful in a processing chamber of a wafer processing apparatus, comprising:

a support surface in a layer of ceramic material on which a semiconductor wafer is supported during processing of the wafer in the chamber;

at least one electrostatic clamping electrode embedded in the layer of ceramic material, the at least one electrostatic clamping electrode operable to apply an electrostatic clamping force to a wafer on the support surface when an electrostatic clamping voltage is applied to the clamping electrode; and

at least one declamping electrode embedded in the layer of ceramic material above the at least one electrostatic clamping electrode operable to provide a path for draining any residual charge between the wafer and the support surface when the electrostatic clamping voltage is no longer applied to the clamping electrode.

11. The electrostatic chuck assembly of claim 10, further comprising a mesa pattern, comprising a plurality of mesas, on the support surface wherein the at least one electrostatic clamping electrode is patterned such that the at least one electrostatic clamping electrode is not directly below a mesa of the plurality of mesas and/or the at least one electrostatic declamping electrode is patterned such that the at least one electrostatic declamping electrode is not directly below a mesa of the plurality of mesas.

12. The electrostatic chuck assembly of claim 10, wherein

(a) the at least one electrostatic clamping electrode includes at least one pattern of an electrically conductive material, and the at least one declamping electrode includes at least one pattern of an electrically conductive material wherein the at least one pattern of the clamping electrode and the at least one pattern of the declamping electrode overlap and have the same pattern;

and/or

(b) the at least one electrostatic clamping electrode and the at least one declamping are not directly below any surface which supports the wafer.

13. The electrostatic chuck assembly of claim 10, wherein the at least one electrostatic clamping electrode includes an annular clamping electrode beneath an outer annular edge seal of the support surface and the at least one electrostatic declamping electrode includes an annular declamping electrode beneath the outer annular edge seal of the support surface wherein the annular declamping electrode is above the annular clamping electrode.

14. The electrostatic chuck assembly of claim 10, wherein:

(a) the at least one declamping electrode is about 10 microns or less beneath the upper surface of the support surface of the electrostatic chuck assembly; and

/or

(b) the at least one clamping electrode is about 100 microns or more beneath the upper surface of the support surface of the electrostatic chuck assembly.

15. The electrostatic chuck assembly of claim 10, wherein

(a) the electrostatic chuck assembly further comprises at least one outlet in the support surface which delivers a heat transfer gas to an underside of the wafer, and at least one gas passage in the layer of ceramic material connected to a source of heat transfer gas operable to supply heat transfer gas at a desired pressure to the at least one gas passage;

and/or

(b) a lower surface of the layer of ceramic material is bonded to an upper surface of a heater plate, and a lower surface of the heater plate is bonded to an upper surface of a temperature controlled baseplate;

(c) the electrostatic chuck assembly further comprises lift pins operable to lower the wafer onto the support surface of the electrostatic chuck assembly and to raise the wafer from the support surface of the electrostatic chuck assembly; and

/or

(d) the electrostatic chuck assembly further includes a heater layer which includes independently controllable heater zones.

16. The electrostatic chuck assembly of claim 10, wherein the electrostatic clamping electrode is a monopolar or bipolar electrostatic clamping electrode.

17. The electrostatic chuck assembly of claim 10, wherein the at least one declamping electrode is an annular declamping electrode beneath an outer annular edge seal of the support surface wherein the annular declamping electrode is above the clamping electrode and/or the at least one declamping electrode is an annular declamping electrode beneath an inner annular edge seal of the support surface wherein the annular declamping electrode is above the clamping electrode.