Selectively etching silicon using fluorine without plasma

Details Selectively etching silicon using fluorine without plasma Selectively etching silicon using fluorine without plasma

2000-03-27

2002-12-31

Gulakowski, Randy (Department: 1746)

Etching a substrate: processes

Gas phase etching of substrate

Etching a multiple layered substrate where the etching...

C216S079000, C438S715000, C438S719000, C438S738000

Reexamination Certificate

active

06500356

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to processes for etching a silicon film on a workpiece. More specifically, the invention relates to processes for selectively etching silicon without etching silicon oxide or silicon nitride.
BACKGROUND OF THE INVENTION
Electronic devices containing silicon-based semiconductors, such as integrated circuits and flat panel displays, generally are fabricated by depositing many successive layers of silicon, metal and dielectric and patterning the layers to form various electronic circuitry components such as transistors, resistors, capacitor, and interconnect conductors.
The most commonly used dielectric materials are silicon oxide and silicon nitride. Silicon layers can function as semiconductors or conductors depending on their level of impurity doping.
To form the desired electronic component structures, it is necessary to etch a pattern in one layer of material without etching adjacent layers. However, most etch processes intended to selectively etch one specific material, such as silicon, unavoidably etch to some extent layers of other materials, such as silicon oxide or silicon nitride, that are adjacent to or underlying the layer that is intended to be etched.
Selective etch processes can be characterized by a selectivity ratio, which is the ratio between the amount of desired material removed to the amount of undesired material removed by the etch process per unit time. An etch process generally will have different selectivity ratios relative to different undesired materials. High selectivity is very difficult to achieve.
Therefore, a need exists for a process for selectively etching silicon without etching silicon oxide or silicon nitride.
SUMMARY OF THE INVENTION
The invention is a process for selectively etching silicon without etching silicon oxide or silicon nitride. The principal etchant gas is molecular fluorine gas (F
2
) that is not excited to a plasma state.
I discovered that, when not decomposed in a plasma, molecular fluorine gas effectively etches silicon without etching silicon oxide or silicon nitride to any measurable extent. Therefore, a silicon etch process using molecular fluorine can achieve essentially infinite etch selectivity relative to silicon oxide and silicon nitride.


REFERENCES:
patent: 4498953 (1985-02-01), Cook et al.
patent: 4786361 (1988-11-01), Sekine et al.
patent: 4854263 (1989-08-01), Chang et al.
patent: 5000113 (1991-03-01), Wang et al.
patent: 5129958 (1992-07-01), Nagashima et al.
patent: 5180466 (1993-01-01), Shin
patent: 5302236 (1994-04-01), Tahara et al.
patent: 5366585 (1994-11-01), Robertson et al.
patent: 5425842 (1995-06-01), Zijlstra
patent: 5534107 (1996-07-01), Gray et al.
patent: 5620526 (1997-04-01), Watatani et al.
patent: 5726480 (1998-03-01), Pister
patent: 5756400 (1998-05-01), Ye et al.
patent: 5770098 (1998-06-01), Araki et al.
patent: 5830807 (1998-11-01), Matsunaga et al.
patent: 5844205 (1998-12-01), White et al.
patent: 5922219 (1999-07-01), Fayfield et al.
patent: 5958801 (1999-09-01), Langley
patent: 6117793 (2000-09-01), Tang
Flamm, J. et al., “XeF2 and F-Atom Reactions with Si: Their Significance for Plasma Etching, Solid State Technology,” Apr. 1983, pp. 117-121.*
Ibbotson, D.E. et al., “Plasmaless Dry Etching of Silicon with Fluorine-Containing Compounds,” Jun. 6, 1984.*
Ibbotson, D.E. et al., Comparison of XeF2 and F-Atom Reactions with Si and SiO2, Mar. 28, 1984.*
Aliev, V.S. et al., “Development of Si(100) Surface Roughness at the Initial Stage of Etching in F2 and XeF2 Gases: Ellipsometric Study,” Surface Science, pp. 206-214 (1999).*
Wang, X. et al., “Gas-Phase Silicon Etching with Bromine Trifluoride,” Transducers, 1997 International Conference on Solid-State Sensors and Actuators (1997).*
Streller, U. et al., “Selectivity in Dry Etching of Si(100) with XeF2 and VUV Light,” Applied Surface Science, pp. 341-346 (1996).*
Habuka, H. et al., “Dominant Overall Chemical Reaction in a Chlorine Trifluoride-Silicon-Nitrogen System at Atmospheric Pressure,” Jpn. J. Appl. Phys., vol. 38 pp. 6466-6469 (1999).*
Flamm et al., “Reaction of fluorine atoms with SiO2,” J. Appl. Phys., 50 (10), pp. 6211-6213, American Institute of Physics (Oct. 1979).
Donnelly et al., “Studies of chemiluminescence accompanying fluorine atom etching of silicon,” J. Appl. Phys., 51 (10), pp. 5273-5276, American Institute of Physics (Oct. 1980).
Flamm et al., “The reaction of fluorine atoms with silicon,” J. Appl. Phys., 52 (5), pp. 3633-3639, American Institute of Physics (May 1981).
Mucha et al., “Chemiluminescence and the reaction of molecular fluorine with silicon,” J. Phys. Chem., vol. 85, pp. 3529-3532, American Chemical Society (1981).
Mucha et al., “Chemiluminescent reaction of SiF2with fluorine and the etching of silicon by atomic and molecular fluorine,” 53 (6), pp. 4553-4554, American Institute of Physics (Jun. 1982).
Flamm et al., “XeF2and F-atom reactions with Si: their signifance for plasma etching,” Solid State Technology, Apr. 1993, pp. 117-121.

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