JPH03265172A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To decrease imperfections and uniformize film thickness by forming a semiconductor layer on an Si oxide film, Si nitride film, or Si oxide nitride film, ion-implanting fluorine, chlorine, and bromine, and heat-treating and diffusing them. CONSTITUTION:A silicon oxide film, silicon nitride film, or silicon oxide nitride film 2 is formed on a silicon substrate 1, and on the film 2 a semiconductor layer 3 is formed. In this layer fluorine, chlorine, or bromine ions are implanted, and heat-treated and diffused into the film 2. This makes it possible to form the film 2 by using a thermal oxidation or CVD method, and the fluorine, chlorine, or bromine ions are diffused uniformly in the film 2. Accordingly, imperfections existing in the film 2 are removed by a gettering effect, the film thickness can be made uniform, and the reliability increases.

Description

[Detailed Description of the Invention] (Summary) Regarding a method for manufacturing a semiconductor device, in particular, a method for forming a gate insulating film of an MO3 type transistor, it is possible to create a gate insulating film that has few defects and has a uniform film thickness without causing an economic burden. The purpose of the present invention is to provide a method that can be manufactured without increasing the number of semiconductors, and a semiconductor layer is formed on a silicon oxide film, a silicon nitride film, or a silicon oxynitride film. Bromine ions are implanted and heat treated to diffuse the fluorine, chlorine, or bromine into the silicon oxide film, silicon nitride film, or silicon oxynitride film.

[Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a gate insulating film of an MO3 type transistor.

[Conventional technology]

As a method for forming a highly reliable gate insulating film with few defects, the salt #oxidation method is known, in which a silicon substrate is thermally oxidized in a mixture of oxygen and chlorine gas to form a silicon dioxide insulating film. The impurities and defects in the silicon dioxide insulating film are removed by the gettering effect of the chlorine-based gas mixed into the oxygen, forming a high-quality insulating film.

[Problem to be solved by the invention]

By the way, the equipment used in the hydrochloric acid oxidation method requires special processing equipment to dispose of exhaust gas containing chlorine gas, which has the disadvantage of increasing the size of the equipment and increasing the economic burden. . In addition, since the concentration of chlorine-based gas that comes into contact with the silicon substrate is not uniform within the substrate surface, the thickness of the silicon dioxide film becomes uneven, and the amount of chlorine in the silicon dioxide film becomes uneven. It has the disadvantage of becoming

The purpose of the present invention is to eliminate these drawbacks,
It is an object of the present invention to provide a method of manufacturing a gate insulating film having few defects and having a uniform thickness without increasing the economic burden.

[Means to solve the problem]

The above purpose is to form a semiconductor layer (3) on a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (2), and to add fluorine ions, chloride ions,
Alternatively, bromine ions are implanted, heat treatment is performed, and the fluorine, chlorine, or bromine is added to the silicon oxide film, silicon nitride film, or silicon oxynitride film (2).
This is achieved by a method for manufacturing a semiconductor device that includes a step of diffusing into the semiconductor device.

[Effect]

Silicon oxide film, silicon nitride film, or silicon oxynitride film can be formed using normal thermal oxidation method or CVD method without mixing chlorine-based gas. The thickness is uniform. A semiconductor layer is formed on this insulating film having a uniform thickness, ion implantation of fluorine ions, chlorine ions, or bromine ions is performed, and a desired amount of fluorine, chlorine, or bromine is applied. It diffuses uniformly into the insulating film, and its gettering effect removes defects present in the insulating film, allowing a highly reliable insulating film with uniform thickness to be formed without increasing economic burden.

〔Example〕

Hereinafter, with reference to the drawings, an MO according to an embodiment of the present invention will be described.
A method for manufacturing an S-type diode will be explained.

Referring to FIG. 1(a), silicon dioxide M2 having a thickness of 85 mm is formed on a silicon substrate 1 by normal thermal oxidation.

Referring to FIG. 1(b), a polycrystalline silicon layer 3 having a thickness of 3.000λ is formed using the CVD method.

Refer to Figure 1 (C) Arsenic ions were implanted at an energy of 100 KeV and a dose of 3 x 1015 cm-'', and then fluorine ions extracted by ionizing boron trifluoride (BF) were implanted at an energy of 60 KeV and a dose of ii Ion implantation is performed using I.sub.X 1015 cv-2.The purpose of implanting arsenic ions is to make the polycrystalline silicon layer 3 into a conductive gate electrode.

Refer to FIG. 1(d) Next, heat treatment is performed at a temperature of 850° C. for 120 minutes to form a MOS diode having the polycrystalline silicon Ji3 as the gate electrode and the silicon dioxide film 2 as the gate insulating film.

See FIG. 2 FIG. 2 shows the secondary ion counts of arsenic, fluorine, and oxygen in the depth direction of the MOS diode manufactured by the above-described steps. As is clear from this figure, fluorine is sufficiently introduced into the silicon dioxide film.

See Figure 3. Figure 3 shows the Fowler No. of the MOS diode.
rdhei+n) shows the relationship between the shift amount of flat band voltage after stress generation due to channel current and the amount of fluorine ions implanted into the silicon dioxide film. As is clear from this figure, if sufficient fluorine is introduced into the silicon dioxide film, the amount of shift in the flat band voltage will be reduced.

The fact that the amount of shift in the flat band voltage is small means that
This indicates that the device characteristics are stable.

Note that as the ions to be implanted, in addition to fluorine ions, chlorine ions or bromine ions may be used.

Furthermore, after ion implantation of fluorine ions, chloride ions, or bromine ions and heat treatment, arsenic ions may be ion-implanted and heat treatment performed, or conversely, arsenic ions may be ion-implanted and heat treatment is performed. After that, fluorine ions, chlorine ions, or bromine ions may be implanted and heat treated.

Also, when the gate insulating film is formed using a silicon nitride film, #silicon nitride film, or a laminated film of a silicon oxide film and a silicon nitride film, ion implantation of fluorine ions, chlorine ions, or bromine ions is not necessary. The same effect as in the case of a silicon oxide film can be obtained.

〔Effect of the invention〕

As explained above, in the method for manufacturing a semiconductor device according to the present invention, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film having a uniform thickness formed using a normal thermal oxidation method or a CVD method is used. forming a semiconductor layer on top;
By implanting fluorine ions, chlorine ions, or bromine ions and performing heat treatment, fluorine, chlorine, or bromine can be added to a silicon oxide film, silicon nitride film, or #silicon nitride film with a uniform film thickness. is sufficiently diffused and the defects in those films are removed by the gettering effect, so that an insulating film with a uniform thickness and few defects is formed. If this insulating film is used as a gate insulating film of an MO3 type transistor, the characteristics of the transistor will be stabilized and reliability will be significantly improved.

[Brief explanation of drawings]

1(a), (b), (c), and (d) are manufacturing process diagrams of a MOS diode according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the secondary ion counts of arsenic, fluorine, and oxygen in the insulating film and the etching time. FIG. 3 is a diagram showing the relationship between the shift amount of flat band voltage and the amount of fluorine ion implanted. l...Silicon substrate, 2...Silicon oxide film, silicon nitride film, or silicon oxynitride film, 3...Polycrystalline silicon layer.

Claims (1)

[Claims] A semiconductor layer (3) is formed on a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (2), and the semiconductor layer (3) contains fluorine ions, chlorine ions, or bromine ions. A semiconductor characterized by comprising a step of implanting ions, performing heat treatment, and diffusing the fluorine, chlorine, or bromine into the silicon oxide film, silicon nitride film, or silicon oxynitride film (2). Method of manufacturing the device.