Method of etching self-aligned vias and trenches in a multi-layer film stack
First Claim
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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Abstract
A multi-step etch process wherein elliptical via openings and trench openings are formed in a dielectric layer includes supporting a multi-layer film stack on a temperature controlled electrostatic chuck in a plasma etch reactor. The multi-layer film stack has a dielectric layer and a patterned metal hard mask layer above the dielectric layer. An etchant gas is supplied to the plasma etch reactor. The etchant gas is energized into a plasma state, and via openings in a photo resist are transferred into a planarization layer and then into elliptical portions of the trench openings in a patterned hard mask layer while maintaining the chuck at a temperature of about 30 to 50° C. The elliptical openings are extended into a lower layer of the hard mask and into an underlying dielectric layer while maintaining the chuck at a temperature of 20° C. or below. After stripping the planarization layer to expose the trench pattern in the hard mask, trench openings are formed in the dielectric layer while maintaining the chuck at a temperature of about 55° C. or higher. The process can thus provide enlarged via contact areas while etching trenches with pitches of 80 nm or less.
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Citations
20 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of etching self-aligned vias and trenches in a multi-layer film stack wherein patterns of openings in layers of the multi-layer film stack are transferred into one or more underlying layers of the multi-layer film stack by performing a multi-step plasma etching process in a plasma etching apparatus wherein a semiconductor substrate is supported on a temperature controlled chuck;
- the method comprising;
transferring a pattern of via openings having a critical dimension (CD1) in a patterned mask layer into an underlying planarization layer, wherein the planarization layer overlies and fills a pattern of trench openings having a critical dimension (CD2) in a patterned hard mask layer, CD1 is larger than CD2 and at least some of the via openings in the patterned mask layer are vertically aligned with the trench openings in the hard mask layer; transferring the via openings in the planarization layer into the filled trench openings in the hard mask layer so as to form elliptical via openings, the elliptical via openings having critical dimensions CD1 in a direction along a length of the trenches and critical dimensions CD2 in a transverse direction across a width of the trenches; transferring the elliptical via openings into an underlying dielectric layer; stripping the planarization layer such that the patterned hard mask layer is exposed; transferring the pattern of trench openings in the hard mask layer into the underlying dielectric layer such that at least some of the trenches are formed over the elliptical via openings and the elliptical via openings are extended further into the dielectric layer, the trench openings and elliptical via openings having substantially the same critical dimension CD1 in the transverse direction. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- the method comprising;
Specification