Coating processes – Electrical product produced – Integrated circuit – printed circuit – or circuit board
Patent
1985-07-10
1986-11-25
Lusignan, Michael R.
Coating processes
Electrical product produced
Integrated circuit, printed circuit, or circuit board
204164, 427 39, 427294, 427 93, 427255, B05D 306, B05D 512
Patent
active
046248595
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of producing silicon dioxide films on a substrate, wherein the resulting film is suitable for use as an insulating film for semiconductor elements.
DESCRIPTION OF THE PRIOR ART
Conventionally, the sputtering method is known in the art to produce silicon dioxide films, and to carry it out the equipment shown in FIG. 1 is employed. In FIG. 1 there are provided a vacuum container 1, electrodes 2 and 3, the electrode 2 being positive and the electrode 3 being negative, a gas inlet 4, a substrate 6 fixed to the surface of the positive electrode 2, and a target 5 fixed to the negative electrode 3 opposite to the substrate 6. The reference numerals 7 and 8 designate an argon gas container and a valve connected to a discharge duct communicating with a vacuum pump (not shown), respectively. The reference numeral 9 designates insulating pillars.
By employing the equipment described above, the known method is carried out as follows:
An argon gas is introduced into the vacuum container 1 through the gas inlet 4, and an electric field is applied between the electrodes 2, 3, whereby the argon gas is ionized into Ar.sup.+ ions. The argon ions collide with the target 5 of silicon dioxide on the negative electrode 3, thereby enabling the molecules of silicon dioxide to dissipate in the vacuum container 1. The dissipating silicon dioxide molecules stick to the surface of the substrate 6 on the positive electrode 2. In this way silicon dioxide films are deposited on the substrate 6.
The known method has the following drawbacks. First of all, it is impossible to form a silicon dioxide film having a perfect composition, proportion and bonding of atoms as a compound, and the films generally lack in oxygen atoms. Second, the films are likely to have pinholes due to the intrusion of the argon gas into the silicon dioxide film. Third, the density is likely to be low, which prohibits the films for use in semiconductor elements where high reliability and high quality are required for the silicon dioxide films. In order to obviate the possibility of oxygen-short films, there is a proposal for heating the substrate 5.degree. to 800.degree. C. or more so as to accelerate oxidizing. However, after an aluminium wiring is produced on the substrate in a semiconductor process using a semiconductor for the substrate 5, the aluminium wiring is likely to melt away at such an elevated temperature.
DISCLOSURE OF THE INVENTION
The present invention provides a method of producing silicon dioxide films, which comprises a first step of heating a material of silicon or silicon oxides thereby to vaporize the same; a second step of ionizing or exciting the vaporized material; and a third step of accelerating the ionized material thereby to enable the same to collide with the substrate, wherein these three steps are carried out in a vacuum container which includes a gas ambient consisting mainly of oxygen atoms, thereby enabling silicon dioxide to be vapor-plated on the substrate to produce a high quality silicon dioxide film.
Under the present invention the vaporized silicon or its oxides is at least partially ionized or excited, and accelerated, thereby ensuring that the silicon atoms are sufficiently activated to be combined while vapor-plating or flying onto the substrate with the oxygen molecules or atoms in the ambient which are also partially ionized or excited. Accordingly, it is not necessary to heat the substrate up to an elevated temperature, which is commonly practiced under the conventional sputtering method, and there is no likelihood of oxygen shortage. The invention uses no argon gas, thereby ensuring pinhole-free, high purity, high density, and high-pressure resistant silicon dioxide films. The method of the invention has many practical advantages as a method for producing an insulating film in semiconductor elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view showing the equipment used for carrying out the conventional method of produc
REFERENCES:
patent: 4004176 (1977-01-01), Otake et al.
patent: 4440804 (1984-04-01), Milgram
patent: 4492717 (1985-01-01), Pliskin et al.
Minowa, Y. et al., SiO.sub.2 Films Deposited on Si by an Ionized Cluster Beam, Journal of Vacuum Science & Technology B, Second Series, vol. 1, No. 4, Oct.-Dec. 1983, pp. 1148-1151.
Akira Shuhara
Kenichiro Yamanishi
Yoshibumi Minowa
Lusignan Michael R.
Mitsubishi Denki & Kabushiki Kaisha
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