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Method of etching self-aligned vias and trenches in a multi-layer film stack

  • US 8,668,835 B1
  • Filed: 01/23/2013
  • Issued: 03/11/2014
  • Est. Priority Date: 01/23/2013
  • Status: Active Grant
First Claim
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1. A method of etching self-aligned vias and trenches in a multi-layer film stack supported by a temperature controlled electrostatic chuck in a plasma processing apparatus wherein the temperature controlled electrostatic chuck adjusts the temperature of the multi-layer film stack during etching of the self-aligned vias and trenches, the method comprising:

  • etching via openings into a planarization layer beneath a previously patterned photo resist mask while maintaining the multi-layer film stack at a temperature of about 30 to 50°

    C., the planarization layer overlying and filling trench openings in a metal hard mask previously patterned to form trenches, the via openings in the planarization layer being larger than the trench openings, the etching being carried out until planarization material in the trench openings is removed and elliptical via openings are formed in areas of the trench openings where the planarization material is removed;

    etching elliptical via openings into a hard mask layer beneath the metal hard mask while maintaining the multi-layer film stack at a temperature of about 0 to 20°

    C.;

    etching elliptical via openings into a dielectric layer beneath the hard mask layer by transferring the pattern of elliptical via openings in the hard mask layer into the dielectric layer and continuing the etching until the elliptical via openings reach an etch stop layer beneath the dielectric layer while the multi-layer stack is maintained at a temperature below about 50°

    C.;

    stripping the planarization layer to expose the pattern of trench openings in the metal hard mask;

    etching trenches into the dielectric layer by transferring the pattern of trench openings in the hard mask layer into the dielectric layer, while etching the elliptical via openings through the etch stop layer, wherein the trench etch is performed while the multi-layer stack is maintained at a temperature of above about 55°

    C.

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