Substrate holder for retaining a substrate within a processing chamber

• US 6,909,588 B2
• Filed: 11/10/2003
• Issued: 06/21/2005
• Est. Priority Date: 08/06/1999
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Moffatt, Stephen
• Primary Examiner(s): Wells, Nikita
• Assistant Examiner(s): SMITH, JOHNNIE L
• Application Number:
  US10/705,182
• Publication Number:
  US 20040084633A1
• Time in Patent Office: 589 Days
• Field of Search: 250/492.2, 361/234, 364/525, 430/311, 118/5, 118/725
• US Class Current: 361/234
• CPC Class Codes: H01L 21/6831 using electrostatic chucks
• CPC Class Codes: H01L 21/68757 characterised by a coating or a hardness or a material

Abstract

A wafer chuck is designed to allow the substrate to thermally deform during charged particle beam lithography. The wafer chuck includes a compliant layer disposed over an chuck body. During lithography processing the wafer is electrostatically held in contact with a flexible compliant layer and the wafer is exposed to the charged particle beam resulting in thermal deformation of the wafer. The compliant layer deforms with the substrate and allows the wafer to deform in a predictable manner.

Claims

1. A wafer holder for retaining a substrate within a processing chamber comprising:

an electrode; and

one or more layers covering a portion of said wafer holder which contacts a wafer, where at least one of said layers is compliant, so that said portion of said wafer holder which contacts said wafer deforms with said wafer, avoiding relative movement between said wafer and said contacted portion of said wafer holder, when there is localized thermal deformation of said wafer surface during processing.

2. The wafer holder of claim 1 wherein said compliant layer is an electrical insulator having a dielectric constant between 1 and 3.

3. The wafer holder of claim 1 wherein said compliant layer can withstand at least 10% shear stress without exceeding the yield strength of the said compliant layer material.

4. The wafer holder of claim 1 wherein the electrode comprises at least one conductive material selected from the group consisting of:

copper, nickel, chromium, aluminum, iron, and mixtures or alloys thereof.

5. The wafer holder of claim 1 wherein said compliant layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

6. The wafer holder of claim 1 wherein said compliant layer is between 1 and 10 μ

m thick.

7. An apparatus for projecting patterned charged particles onto a substrate comprising:

a processing chamber;

a charged particle source for generating a charged particle beam that impinges on the substrate; and

an electrostatic chuck comprising an electrode and one or more layers covering a portion of a substrate holder which contacts a substrate, where at least one of the layers is compliant, so that the portion of the substrate holder which contacts the substrate deforms with the substrate avoiding relative movement between the substrate and the contacted portion of the substrate holder, when there is localized thermal deformation of the substrate during processing.

8. The apparatus of claim 7 further comprising:

a computer for calculating an estimated charged particle beam deflection to compensate for the actual deformation of the substrate caused by the exposure of the substrate to the charged particle beam, wherein the computer generates a deflection signal corresponding to the calculated deflection; and

a beam deflector for deflecting the charged particle beam in response to the deflection signal from the computer.

9. The apparatus of claim 7 wherein the compliant layer is an electrical insulator having a dielectric constant between 1 and 3.

10. The apparatus of claim 7 wherein the compliant layer can withstand at least 10% shear stress without exceeding the yield strength of the said compliant layer material.

11. The apparatus of claim 7 wherein the electrode is comprises a conductive material selected from the group consisting of:

copper, nickel, chromium, aluminum, iron, and mixtures thereof.

12. The apparatus of claim 7 wherein the compliant layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

13. The apparatus of claim 7 further comprising:

a lithography mask positioned between the charged particle source and the substrate; and

an electron sensor disposed within the processing chamber for detecting backscattered electrons emanating from the substrate.

14. The apparatus of claim 7 further comprising a substrate temperature sensor for measuring the temperature of the substrate during processing and for sending a signal corresponding to the measured substrate temperature to the computer.

15. The apparatus of claim 7 wherein the compliant layer is between 1 and 10 μ

m thick.

16. The apparatus of claim 7 wherein localized heating of the substrate due to exposure to the charged beam is between 1°

C. and 50°

C.

17. A method for patterning a photoresist layer on a substrate comprising the steps of:

forming a photoresist layer on the substrate;

positioning the substrate on an electrostatic chuck having one or more layers covering a portion of the substrate chuck which contacts the substrate, where at least one of the layers is compliant, so that the portion of the electrostatic chuck which contacts the substrate deforms with the substrate, avoiding relative movement between the substrate and the contacted portion of the electrostatic chuck, when there is localized thermal deformation of the substrate during processing; and

exposing portions of the photoresist layer on the substrate to a charged particle beam.

18. The method of claim 17 further comprising the steps:

computing an estimated deformation of the substrate caused by exposure of the substrate to the charged particle beam; and

deflecting the particle beam in response to the estimated deformation.

19. The method of claim 17 further comprising:

using a charged particle beam to scan a first mark on a photo lithography mask onto a second mark on said substrate;

detecting backscattered electrons from said scanning step;

determining the position of the substrate using the detected backscattered electrons; and

deflecting the charged particle beam in response to the measured position of the substrate.

20. The method of claim 17 wherein the compliant layer is an insulator having a dielectric constant between 1 and 3.

21. The method of claim 17 wherein the compliant layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

22. The method of claim 17 wherein the exposing step is performed using a SCALPEL lithography system.

23. An electrostatic chuck for use in substrate processing, the chuck having an electrode covered by an electrically insulative layer for receiving the substrate, comprising:

the electrically insulative layer which is elastic, in a manner such that the portion of the electrostatic chuck which contacts the substrate deforms with the wafer, avoiding relative movement between the substrate and the contacted portion of the electrostatic chuck, when there is localized thermal deformation of the substrate during processing and can withstand at least 10% shear stress without exceeding the material yield strength.

24. The electrostatic chuck of claim 23 wherein the electrically insulative layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

25. A method for holding a wafer on a chuck having an electrode and one or more layers covering a portion of the chuck which contacts the wafers, the method comprising the steps of:

selecting the layers so that at least one of the layers covering the portion of the chuck which contacts the wafer is compliant so that the portion of the chuck which contacts the wafer deforms with the wafer, avoiding relative movement between the wafer and the contacted portion of the chuck, when there is localized thermal deformation of the wafer during processing;

placing the wafer on one of the layers of the chuck, and energizing the electrode.

26. The method of claim 25 wherein the compliant layer is an electrical insulator having a dielectric constant between 1 and 3.

27. The method of claim 25 wherein the compliant layer can withstand at least 10% shear stress without exceeding a yield strength of the said compliant layer material.

28. The method of claim 25 wherein the electrode comprises at least one conductive material selected from the group consisting of:

copper, nickel, chromium, aluminum, iron, and mixtures or alloys thereof.

29. The method of claim 25 wherein the compliant layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

30. The method of claim 25 wherein the compliant layer is between 1 and 10 μ

m thick.

31. An apparatus for handling a substrate for use in semiconductor processing comprising:

a substrate holder; and

one or more layers covering a portion of the substrate holder which contacts the substrate, where at least one of the layers is compliant, so that the portion of the substrate holder which contacts the substrate deforms with the substrate, avoiding relative movement between the substrate and the contacted portion of the substrate holder, when there is localized thermal deformation of the substrate during processing.

32. The apparatus of claim 31 wherein the compliant layer can withstand at least 10% shear stress without exceeding a yield strength of the said compliant layer material.

33. The apparatus of claim 31 wherein the compliant layer comprises an insulative material selected from the group consisting of:

fluorosilicones, polyamides, polyimides, polyketones, polyetherketones, polysulfones, polycarbonates, polystyrenes, polyurethanes, nylons, polyvinylchlorides, polypropylenes, polyethersulfones, polyethylene terephthalate, fluoroethylene propylene copolymers, cellulose, triacetates, silicones and rubbers, and combinations thereof.

34. The apparatus of claim 31 wherein the compliant layer is between 1 and 10 μ

m thick.