Semiconductor device and method of fabricating the same
View Patent ↗A method for simply forming a miniature contact hole in a self-aligned manner with a wiring layer. A gate insulating film, a gate electrode, and a protective insulating layer are formed on the surface of a silicon substrate, and a blanket insulating film is deposited over the entire surface to cover a source/drain diffusion layer. Subsequently, an interlayer insulating film is laminated on the blanket insulating film. Nitrogen is added to a mixture gas of C 5 F 8 and O 2 , and the resulting mixture gas is excited by a plasma for use as an etching gas. The interlayer insulating film is etched by reactive ion etching (RIE) using the blanket insulating film as an etching stopper to form a contact hole. A silicon nitride film is preferably used for the protective insulating layer. A silicon nitride film or a silicon carbide film is preferably used for the blanket insulating film.
1. A method of manufacturing a semiconductor device, comprising:
forming a metal film and a first silicon nitride film laminated in this order over a semiconductor substrate on an insulating film;
processing said first silicon nitride film and said metal film into a wiring pattern to form wires;
depositing a second silicon nitride film on the entire surface such that said second silicon nitride film is applied to a top face and a side face of said first silicon nitride film processed into said wiring pattern, and side faces of said wires, and over the semiconductor substrate between said wires;
forming a silicon interlayer insulating film of an oxide film to cover said second silicon nitride film; and
forming a contact hole which reaches a surface of said semiconductor substrate between wires of said wiring pattern, comprising:
forming an etching mask having a contact hole pattern on said silicon interlayer insulating film;
penetrating said silicon interlayer insulating film between the wires by dry etching using said etching mask; and
subsequently removing said second silicon nitride film over said semiconductor substrate at a bottom of the contact hole by dry etching, using said first silicon nitride film processed into said wiring pattern and said second silicon nitride film on the top and side faces of said first silicon nitride film and the side faces of the wires as an etching mask,
wherein at least the dry etching of said silicon interlaver insulating film is performed with a nitrogen-containing gas added to a reactant gas comprising a fluorocarbon gas, a ratio of nitrogen to the reactant gas being 0.8 or more.
2. A method according to claim 1 , further comprising dry-etching said insulating film using said first silicon nitride film processed into said wiring pattern and said second silicon nitride film on the top and side faces of said first silicon nitride film and the side faces of the wires as an etching mask, wherein a nitrogen containing gas is added to a fluorocarbon gas for use as an etching gas in the dry etching of said insulating film.
3. A method according to claim 1 , wherein said fluorocarbon gas is one or more kinds of gas selected from a group consisting of CF 4 , CHF 3 , CH 2 F 2 , CH 3 F, C 4 F 8 and C 5 F 8.
4. A method according to claim 3 , wherein between the steps of penetrating said silicon interlayer insulating film by dry etching and subsequently removing said second silicon nitride film at the bottom of the contact hole, a step is performed of changing to a different etching gas, the dry-etching of said second silicon nitride film being performed with said different etching gas.
5. A method according to claim 3 , wherein said different etching gas comprises a mixture of CHF 3 and CO.
6. A method according to claim 3 , wherein said reactant gas further comprises O 2.
7. A method according to claim 6 , wherein the dry etching of said silicon interlayer insulating film is reactive ion etching performed using two radio frequencies, and argon gas is further included with said nitrogen-containing gas and said reactant gas.
8. A method according to claim 1 , wherein said nitrogen-containing gas is one or more kinds of gas selected from a group consisting of a nitrogen gas, an ammonia gas and a nitrous oxide gas.
9. A method according to claim 1 , wherein said wires are formed such that said wires run in parallel with one another.
10. A method according to claim 1 , wherein between the steps of penetrating said silicon interlayer insulating film by dry etching and subsequently removing said second silicon nitride film at the bottom of the contact hole, a step is performed of changing to a different etching gas, the dry-etching of said second silicon nitride film being performed with said different etching gas.
11. A method according to claim 1 , wherein said depositing the second silicon nitride film is conformal.
12. A method according to claim 1 , wherein said depositing the second silicon nitride film is performed by chemical vapor deposition with a total gas pressure in a range of 1×10 4 Pa to 6×10 4 Pa.