KR950008853B1 - Method of fabricating a capacitor for semiconductor device - Google Patents

Abstract

depositing a first polysilicon(9) , in which the impurity ions are implanted, on a silicon substrate(8); forming a residual film(10) by reactive ion etching of the first polysilicon(9); inserting a halide in a reactive chamber and applying RF power to the chamber to form a gas plasma; converting the residual film to a SiCxHyFz film by exposing it to the gas plasma; rapidly heat treating a SiCxHyFz film to form a SiC film(11) on the polysilicon(9); removing a carbon layer(12) remained on the SiC film(11) in the rapid heat treatment process; depositing an insulation film(13) on the SiC film(11); depositing a second polysilicon(14) on the insulation film(13) to form an upper electrode; defining a capacitor region using a photosensitive film(15); and removing the photosensitive film after etching the portion except capacitor region. Formation of the SiC film having a high dielectric efficiency provides a higher capacitance.

Description

Capacitor Manufacturing Method of Semiconductor Device

(A)-(j) is sectional drawing which shows the manufacturing process of a capacitor by a conventional method.

(A)-(j) of FIG. 2 is sectional drawing which shows the manufacturing process of the capacitor by the method of this invention.

3 is an X-ray photoelectron spectrometer for detecting a SiC film formed on the surface of a residual film formed by reactive ion dry etching, wherein (a) shows a state before rapid heat treatment and (b) shows a state after rapid heat treatment. .

4 is a view showing the relative change of the SiC composition with the temperature and time of rapid heat treatment.

* Explanation of symbols for main parts of the drawings

1, 8: substrate 2, 6, 9, 14: polycrystalline silicon

3: low temperature oxide film 4: low temperature nitride film

5: thermal oxide film 7, 15: photosensitive film

10 remaining film 11: SiC film

12: graphite carbon 13: insulating film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly, to a method of manufacturing a capacitor using a SiC film formed by rapid heat treatment of a residual film formed by reactive ion dry etching.

In general, in semiconductor integrated circuits, as the storage capacity is increased, the cell area is required to be reduced.

The cell area is greatly influenced by the size of the transistors and capacitors. Therefore, in order to reduce the cell area, the area occupied by the capacitor must be reduced, and the reduction of the capacitor area reduces the capacity of the capacitor.

The capacity of the capacitor is determined by the area and thickness and the dielectric constant of the material.

In manufacturing a capacitor having a constant capacity, a material having a thin thickness and a high dielectric constant is required to reduce the area of the capacitor.

In order to reduce the thickness of the dielectric material in the manufacturing process of the semiconductor device, a variety of difficult problems occur. Therefore, the situation is focused on the development of a new material having a large dielectric constant.

With reference to FIG. 1 attached to the prior art proposed according to the research direction as described above are as follows.

(A) to (j) of FIG. 1 show a method of manufacturing a capacitor having a conventional oxide film-nitride film-oxide film structure.

Referring to the drawings, a conventional method is as follows.

First, a polycrystalline silicon film 2 into which impurities are implanted is deposited on the substrate 1 by low pressure chemical vapor deposition (LPCVD) (FIG. 1B).

Subsequently, a low temperature oxide film 3 is deposited on the polycrystalline silicon 2 to a thickness of about 5 nm (Fig. 1 (c)).

At this time, it is essential that the low temperature oxide film 3 be deposited as thin and uniform as possible.

The low temperature nitride film 4 is deposited on the thin low temperature oxide film 3 by about 50 nm thinly ((d) in FIG. 1), and then thermally oxidized (see (e) in FIG. 1) by an oxygen thermal oxidation method. ) -Nitride film 4 and oxide film 5 are formed (FIG. 1F).

Polycrystalline silicon 6 in which impurities are injected again is deposited on the thermal oxide film 5 to form an upper electrode of the capacitor ((g) of FIG. 1).

The capacitor region is defined using the photosensitive film 7 in the region where the capacitor is to be formed ((h) of FIG. 1).

Subsequently, the dielectric material 2 is removed using a reactive ion dry etching method ((i) in FIG. 1), and then the photosensitive film 7 is removed to prepare a capacitor ((j) in FIG. 1).

However, in the conventional technique as described above, it is extremely difficult to deposit the low temperature oxide film 3 deposited on the polycrystalline silicon film 2, which is the manufacturing process shown in FIG. It is true.

Therefore, the capacitor actually manufactured has a low dielectric constant of about 3.8 to 3.9 and a poor interfacial property with polycrystalline silicon, so that a heat treatment process by an additional oxygen thermal oxidation method is required.

In addition, since the dielectric constant of the low-temperature oxide film is low, it is difficult to manufacture a capacitor having a large capacity with a small area.

Therefore, the conventional technology has a problem that it is not possible to meet the area reduction requirements of the capacitors inevitably for the reduction of the cell area required in manufacturing a large-capacity semiconductor device.

An object of the present invention for solving the above problems is that the polycrystalline is essentially formed on the silicon substrate in the semiconductor manufacturing process so that a large dielectric constant can be easily obtained without using a complex process and a high level of technology to produce a material having a high dielectric constant When the silicon film is etched by the ion dry etching method to a predetermined thickness, the semiconductor film is reduced by rapidly heat-treating the residual film remaining naturally at a uniform thickness and using the same as a dielectric material to reduce the area occupied by the capacitor. The present invention provides a method of manufacturing a capacitor of a semiconductor device capable of improving the degree of integration.

A feature of the present invention for achieving the above object is the step of depositing a first polycrystalline silicon (9) implanted with impurities on a silicon substrate (8) and the method of reactive ion etching the first polycrystalline silicon (9) A method of manufacturing a semiconductor device, comprising: forming a residual film 10 by etching to a predetermined thickness by using the method, wherein the remaining portion is formed on the first polycrystalline silicon 9 at a predetermined thickness according to an ion dry etching method. When the film 10 is formed, a first process of injecting a halogen compound (CHF3, C2F6, CF4, etc.) into the reaction chamber, and a halogen compound injected into the reaction chamber by providing rf power (13.56 MHz) to the first process A second process of forming a gas plasma and a third process of modifying the remaining film 10 to a film made of SiC _X H _Y F _Z by exposing the remaining film 10 to the gas plasma formed by the second process. Process, and in the third process Rapid the fourth step and the fourth step of decomposing the H _Y and F _Z in SiC _X H _Y F _Z membrane to heat treatment rapidly to release the air to remain only the SiC thin film 11 on the polycrystalline silicon thermal treatment been A fifth process of removing the graphite carbon layer 12 remaining on the SiC thin film 11 formed by the above step; a sixth process of depositing the insulating film 13 on the SiC thin film 11; The seventh process of depositing the second polycrystalline silicon 14 on the insulating film 13 to form, the eighth process of defining the capacitor region using the photosensitive film 15 and the dielectric material by the reactive ion dry etching method And a ninth process of removing the photoresist film 15 after etching portions other than the capacitor region.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

(A)-(j) of FIG. 2 is process sectional drawing which showed the manufacturing method of the capacitor by this invention.

First, polycrystalline silicon 9 in which impurities are implanted is deposited on the silicon substrate 8 ((b) of FIG. 2).

Subsequently, when the polycrystalline silicon (9) impurity implanted is etched by using a reactive ion dry etching method, as shown in (c) of FIG. 2, a thickness of several to tens of nm is placed on top of the polycrystalline silicon (9). A residual film 10 having a film is formed.

Thereafter, the silicon substrate on which the residual film 10 is formed is exposed to a gas plasma composed of halogen compounds (CHF 3, C 2 F 6, CF 4, etc.) to form the residual film 10 as a SiC _X H _Y F _Z film, In order to decompose H _Y and F _Z in the formed SiC _X H _Y F _Z film to form a SiC film, rapid heat treatment at 90 ° C. to 1100 ° C. for 1 minute to 10 minutes is performed, as shown in (d) of FIG. 2. 11) is formed to a thickness of 1nm to 2nm and a graphite carbon layer 12 is formed on the surface of the SiC thin film 11.

In this case, in order to form the halogen compound (CHF3, C2F6, CF4, etc.) into a gas plasma, rf power (13.56 MHz) is provided when the halogen compound (CHF3, C2F6, CF4, etc.) is injected.

Subsequently, when ultraviolet rays are irradiated in an ozone (O ₃ ) atmosphere, the graphite carbon layer 12 is removed and only the SiC layer 11 remains (FIG. 2E).

(A) and (b) of FIG. 3 show the detection of the SiC film formation state before the rapid heat treatment and after the rapid heat treatment, respectively, by X-ray photoelectron spectroscopy.

Comparing (a) and (b) of FIG. 3, it can be seen that the formation of the SiC film becomes apparent by rapid heat treatment.

The SiC layer formed after the rapid heat treatment has an extremely thin thickness of about 1 nm to 2 nm and a dielectric constant of about 10. Therefore, the SiC film has a dielectric constant of 2.5 to 3 times that of the conventional oxide film.

This means that in the case of integrated circuits, the area of the capacitor can be greatly contributed to improving the degree of integration.

The thickness of the SiC film is increased in proportion to the increase in the temperature of the rapid heat treatment, and the thickness of the SiC film is similarly increased even if the rapid heat treatment time is increased.

4 is a view showing the change in thickness of the SiC film according to the heat treatment time when the temperature of the rapid heat treatment is 1000 ℃ and 1100 ℃, respectively.

It can be understood that the thickness of the SiC thin film can be adjusted by adjusting the temperature and time of the rapid heat treatment when referring to the drawings.

When the process of removing the graphite carbon layer 12 (see (e) of FIG. 2) is completed, the insulating film 13 is deposited on the SiC film 11 by several nm to form a constituent material of the capacitor (see FIG. (f)).

Subsequently, polycrystalline silicon 14 implanted with impurities to form the upper electrode is deposited on the insulating film 13 ((g) in FIG. 2).

After the capacitor region is defined (H) in FIG. 2 using the photosensitive film 15 on the portion where the capacitor is to be formed, the dielectric material is etched using the reactive ion dry etching method (FIG. 2 (i)).

Finally, the photosensitive film 15 is removed to produce a capacitor as shown in FIG. 2 (j).

As described above, the method of the present invention can contribute greatly to the integration density of an integrated circuit because the area occupied by the capacitor can be reduced by manufacturing the capacitor using a material having a high dielectric constant (SiC thin film).

In addition, the present invention manufactures a capacitor having a large capacity by using a SiC film produced by the reactive ion dry etching method and a rapid heat treatment method instead of the oxide film mainly used in capacitor manufacturing and having a dielectric constant of about 2.5 to 3 times that of the oxide film. can do.

Claims (3)

Depositing a first polycrystalline silicon (9) in which impurities are implanted on the silicon substrate (8) and etching the first polycrystalline silicon (9) to a predetermined thickness by using a reactive ion etching method. In the method of manufacturing a semiconductor device comprising the step of forming the residual film 10 on top of the first polycrystalline silicon 9 to a predetermined thickness according to the ion dry etching method, a halogen compound ( CHF 3, C 2 F 6, CF 4, etc.); Providing a rf power (13.56 MHz) simultaneously with the first process to form a halogen compound injected into the reaction chamber into a gas plasma; Exposing the residual film (10) to the gas plasma formed by the second process to denature the residual film (10) into a film made of SiC _X H _Y F _Z ; A fourth step of rapidly heat-treating the SiC _X H _Y F _Z film denatured in the third process to decompose H _Y and F _Z into the air and to leave only the SiC thin film 11 on the polycrystalline silicon; A fifth process of removing the graphite carbon layer 12 remaining on the SiC thin film 11 generated by the rapid heat treatment of the fourth process; A sixth step of depositing an insulating film (13) on the SiC thin film (11); Depositing second polycrystalline silicon (14) on the insulating film (13) to form an upper electrode; An eighth step of defining a capacitor region by using the photosensitive film 15; And a ninth process of removing portions of the photoresist layer after etching portions other than the capacitor region to a dielectric material by a reactive ion dry etching method. The method of claim 1, wherein the rapid heat treatment temperature for forming the SiC thin film (11) is 900 ° C to 1100 ° C, the rapid heat treatment time is 1 minute to 10 minutes. The method of manufacturing a capacitor of a semiconductor device according to claim 1, wherein the SiC thin film (11) has a thickness of 1 nm to 2 nm.