Electrostatic chuck

• US 5,671,117 A
• Filed: 03/27/1996
• Issued: 09/23/1997
• Est. Priority Date: 02/28/1994
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Birang, Manoocher, Sherstinsky, Semyon, Mak, Alfred, Shamouilian, Shamouil, Tam, Simon W.
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US08/626,667
• Time in Patent Office: 545 Days
• Field of Search: 361/233, 361/234, 361/235, 279/128, 269/8, 269/903
• US Class Current: 361/234
• CPC Class Codes: C23C 16/4586 Elements in the interior of the support, e.g. electrodes, heating or cooling devices
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect
• CPC Class Codes: Y10T 279/23 with magnetic or electrostatic means
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An electrostatic chuck for securing a semiconductor wafer on a pedestal having multiple apertures for the introduction of cooling gas beneath the wafer. The multiple apertures reduce overheating near the wafer edge and provide lower temperature gradients across the wafer. The wafer is held by electrostatic force against a laminate of an electrode layer sandwiched between two dielectric layers in such a way that the laminate presents a planar surface to the wafer for a substantial distance beyond the outer edge of the electrode layer. The laminate construction ensures that a large wafer area beyond the outer edge of the electrode is in contact with the laminate, to minimize cooling gas leakage near the edge, and provides a longer useful life by increasing the path length of dielectric material between the electrode layer and potentially damaging plasma material surrounding the chuck.

Claims

1. An electrostatic chuck, comprising:

a pedestal having a generally flat upper surface for supporting a workpiece;

a laminate including an insulated electrode, attached to the pedestal, wherein the workpiece is electrostatically clamped to the laminate upon application of a voltage to the electrode; and

a plurality of holes extending up through the pedestal and the laminate, to carry a gas for cooling the workpiece from beneath, wherein many of the holes are positioned near the outer periphery of the workpiece;

wherein the pedestal includes a cooling gas reservoir formed beneath the pedestal and extending across all of the holes, and a cooling gas supply passage into the reservoir;

and wherein the laminate includes

a first insulating layer extending over substantially all of the upper surface of the pedestal;

an electrode layer extending over the first insulating layer except for a relatively small outer peripheral portion thereof; and

a second insulating layer extending over the electrode layer and the outer peripheral portion of the first insulating layer around a peripheral edge of the electrode layer, to provide insulation of the electrode material from a process environment in which the electrostatic chuck is installed wherein the second insulating layer presents an upper surface that is substantially planar over the entire width of the laminate, whereby contact is maintained with the workpiece beyond the outer edge of the electrode and over the entire width of the laminate, and whereby the electrode is widely separated from the effects of the process environment to increase the useful life of the electrostatic chuck; and

wherein the pedestal has a recess formed in its upper surface, the recess being generally commensurate with the electrode layer.

2. An electrostatic chuck as defined in claim 1, wherein the electrode is made of copper.

3. An electrostatic chuck, comprising:

a pedestal having a generally flat upper surface for supporting a semiconductor substrate; and

a laminate including an insulated electrode, formed on the pedestal, wherein the workpiece is electrostatically clamped to the laminate upon application of a voltage to the electrode;

wherein the laminate includes

a first dielectric layer extending over substantially all of the upper surface of the pedestal,

an electrode layer formed over the first dielectric layer and extending over substantially the entire first dielectric layer except for a relatively small outer peripheral portion thereof, and

a second dielectric layer formed over the electrode layer and the outer peripheral portion of the first dielectric layer around a peripheral edge of the electrode layer, to provide insulation of the electrode material from a process environment in which the electrostatic chuck is installed;

and wherein the second dielectric layer presents an upper surface that is substantially planar over the entire width of the laminate, whereby contact is maintained with the workpiece beyond the outer edge of the electrode and over the entire width of the laminate, and whereby the electrode is widely separated from the effects of process plasma particles, to increase the useful life of the electrostatic chuck

and wherein the pedestal has a recess formed in its upper surface, the recess being generally commensurate with the electrode layer.

4. An electrostatic chuck as defined in claim 3, wherein the electrode is made of copper.

5. An electrostatic chuck, comprising:

a pedestal having a generally flat upper surface for supporting a workpiece;

a laminate including an insulated electrode, attached to the pedestal, wherein the workpiece is electrostatically clamped to the laminate upon application of a voltage to the electrode; and

a plurality of holes extending up through the pedestal and the laminate, to carry a gas for cooling the workpiece from beneath, wherein many of the holes are positioned near the outer periphery of the workpiece;

wherein the pedestal includes a cooling gas reservoir formed beneath the pedestal and extending across all of the holes, and a cooling gas supply passage into the reservoir;

and wherein the laminate includes

a first insulating layer extending over substantially all of the upper surface of the pedestal;

an electrode layer extending over the first insulating layer except for a relatively small outer peripheral portion thereof; and

a second insulating layer extending over the electrode layer and the outer peripheral portion of the first insulating layer around a peripheral edge of the electrode layer, to provide insulation of the electrode material from a process environment in which the electrostatic chuck is installed;

and wherein the second insulating layer presents an upper surface that is substantially planar over the entire width of the laminate, whereby contact is maintained with the workpiece beyond the outer edge of the electrode and over the entire width of the laminate, and whereby the electrode is widely separated from the effects of the process environment to increase the useful life of the electrostatic chuck;

and wherein the pedestal has a generally circular recess formed in its upper surface and extending to near a peripheral edge of the pedestal;

and wherein the first insulating layer when placed over the pedestal conforms with the recess in the pedestal, and the first insulating layer presents an upper surface having a recessed region corresponding approximately in depth and area to the recess in the pedestal;

and wherein the electrode layer is of approximately the same shape and dimensions as the recess, and substantially fills the recessed region of the first insulating layer, thereby presenting a composite upper surface that is substantially planar;

and wherein the second insulating layer is applied to the composite upper surface of the electrode layer and the first insulating layer.

6. An electrostatic chuck as defined in claim 5, wherein the electrode is made of copper.

7. An electrostatic chuck, comprising:

a pedestal having a generally flat upper surface for supporting a semiconductor substrate; and

a laminate including an insulated electrode, formed on the pedestal, wherein the workpiece is electrostatically clamped to the laminate upon application of a voltage to the electrode;

wherein the laminate includes

a first dielectric layer extending over substantially all of the upper surface of the pedestal,

an electrode layer formed over the first dielectric layer and extending over substantially the entire first dielectric layer except for a relatively small outer peripheral portion thereof, and

a second dielectric layer formed over the electrode layer and the outer peripheral portion of the first dielectric layer around a peripheral edge of the electrode layer, to provide insulation of the electrode material from a process environment in which the electrostatic chuck is installed;

and wherein the second dielectric layer presents an upper surface that is substantially planar over the entire width of the laminate, whereby contact is maintained with the workpiece beyond the outer edge of the electrode and over the entire width of the laminate, and whereby the electrode is widely separated from the effects of process plasma particles, to increase the useful life of the electrostatic chuck;

and wherein the pedestal has a generally circular recess formed in its upper surface and extending near to a peripheral edge of the pedestal;

and wherein the first dielectric layer when placed over the pedestal conforms with the recess in the pedestal, wherein the first dielectric layer presents an upper surface having a recessed region corresponding approximately in depth and area to the recess in the pedestal;

and wherein the electrode layer is of approximately the same shape and dimensions as the recess, has a thickness approximately the same as the depth of the recess, and substantially fills the recessed region of the first dielectric layer, thereby presenting a composite upper surface that is substantially planar;

and wherein the second dielectric layer is applied to the composite upper surface of the electrode layer and the first dielectric layer.

8. An electrostatic chuck as defined in claim 7, wherein the electrode is made of copper.