Method for manufacturing a semiconductor device having a stepped contact hole
First Claim
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1. A method for manufacturing a semiconductor device comprising:
- forming a dielectric film on an underlying structure including a semiconductor substrate;
etching said dielectric film in a first anisotropic dry etching step using a first gas including rare gas, oxygen gas and carbon-rich gas, which is richer than CF4 in carbon content, and a photoresist mask as an etching mask to a specified depth of said dielectric film, to thereby form a first contact hole in said dielectric film;
depositing a specific film at least within said first contact hole by using a second gas as a source gas;
etching a first potion of said specific film on a bottom of said first contact hole selectively from a second portion of said specific film on a sidewall thereof in a second anisotropic dry etching step using a third gas as an etching gas, to expose said dielectric film through said bottom of said first contact hole;
etching said dielectric film exposed from said bottom of said first contact hole in a third anisotropic dry etching step using a fourth gas as an etching gas and said second portion of said specific film as an etching mask, to form a second contact hole extending stepwise from said first contact hole and exposing therefrom said underlying structure; and
removing said second portion of said specific film on said sidewall of said first contact hole.
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Abstract
A process for forming a stepped contact hole includes: dry-etching a portion of a silicon oxide film using a mixed gas including carbon-rich fluorocarbon gas to form a first contact hole, forming a specific film on the sidewall of the first contact hole; dry-etching the remaining portion of the silicon oxide film at the bottom of the first contact hole by using the specific film as a mask to form a second contact hole extending from the first contact hole; and removing the specific film.
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Citations
12 Claims
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1. A method for manufacturing a semiconductor device comprising:
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forming a dielectric film on an underlying structure including a semiconductor substrate;
etching said dielectric film in a first anisotropic dry etching step using a first gas including rare gas, oxygen gas and carbon-rich gas, which is richer than CF4 in carbon content, and a photoresist mask as an etching mask to a specified depth of said dielectric film, to thereby form a first contact hole in said dielectric film;
depositing a specific film at least within said first contact hole by using a second gas as a source gas;
etching a first potion of said specific film on a bottom of said first contact hole selectively from a second portion of said specific film on a sidewall thereof in a second anisotropic dry etching step using a third gas as an etching gas, to expose said dielectric film through said bottom of said first contact hole;
etching said dielectric film exposed from said bottom of said first contact hole in a third anisotropic dry etching step using a fourth gas as an etching gas and said second portion of said specific film as an etching mask, to form a second contact hole extending stepwise from said first contact hole and exposing therefrom said underlying structure; and
removing said second portion of said specific film on said sidewall of said first contact hole. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification