JPH11224938A5 - - Google Patents

Description

[Claims]
1. A method for manufacturing a semiconductor device, comprising the steps of: forming a semiconductor film connected to a semiconductor substrate, the semiconductor film containing impurities at a concentration of 5×10 ²⁰ atoms/cm ³ or more;
a step of reacting a tungsten-containing gas with the semiconductor film to selectively form a lower electrode of a capacitor made of a tungsten film on the surface of the semiconductor film;
forming a tungsten nitride film on the surface of the tungsten film using nitrogen gas or a nitrogen-containing gas;
forming a capacitor dielectric film made of an oxygen compound on the tungsten nitride film;
a step of heat-treating the capacitor dielectric film in an oxygen-containing gas;
forming an upper electrode of the capacitor made of a conductive film on the capacitor dielectric film.
2. A semiconductor film including impurities connected to an impurity diffusion region of a semiconductor substrate;
a tungsten film formed on the semiconductor film as a lower electrode of a capacitor;
a tungsten nitride film formed on the tungsten film;
a capacitor dielectric film containing oxygen formed on the tungsten nitride film;
and an upper electrode of the capacitor, the upper electrode being made of a conductive film formed on the capacitor dielectric film.
3. A process for forming a semiconductor film made of silicon or a silicon compound into which an impurity has been introduced, in contact with a semiconductor substrate;
a step of introducing a refractory metal halide gas into an atmosphere not containing a reducing gas, and selectively forming a refractory metal film on the surface of the semiconductor film in the atmosphere;
a step of nitriding a surface of the refractory metal film to form a refractory metal nitride film;
forming a dielectric film of an oxide of a Group 4A element or a Group 5A element on the refractory metal nitride film ;
and crystallizing the oxide dielectric film by heat treatment at 500° C. or higher.
4. The method for manufacturing a semiconductor device according to claim 3, further comprising a step of supplementing said oxide with oxygen before or after said step of crystallizing said oxide dielectric film.
5. The method for manufacturing a semiconductor device according to claim 3, wherein the semiconductor film is amorphous or polycrystalline.

Furthermore, as described in Japanese Patent Laid-Open Publication No. 6-275776 , if a silicon oxide film is interposed between the lower electrode made of polysilicon and the tantalum oxide film, the capacitance of the entire capacitor decreases.

This makes it possible to create a capacitor with a complex structure and to suppress the leakage current of the entire capacitor.
(2) The above-mentioned problems are solved by a method for manufacturing a semiconductor device, as illustrated in FIGS. 12, 13, 14, and 15 , which comprises the steps of: forming a semiconductor film 13 made of silicon or a silicon compound doped with an impurity in contact with a semiconductor substrate 11; introducing a refractory metal halide gas into an atmosphere not containing a reducing gas and selectively forming a refractory metal film 14 on the surface of the semiconductor film 13 in the atmosphere; nitriding the surface of the refractory metal film 14 to form a refractory metal nitride film 15; forming an oxide dielectric film 16 of a Group 4A element or a Group 5A element on the refractory metal nitride film 15; and crystallizing the oxide dielectric film 16 by heat treatment at 500° C. or higher.

The above -mentioned problems are solved by a method for manufacturing a semiconductor device, which comprises the steps of forming a semiconductor film containing an impurity, forming a refractory metal film on the semiconductor film, forming a refractory metal nitride film on the refractory metal film, and forming a capacitor dielectric film of an oxygen compound on the refractory metal nitride film, as illustrated in Figures 1 and 2. In this case, the refractory metal nitride film may be a tungsten nitride film, and the metal film may be ruthenium.

Therefore, the refractory metal nitride film obtained by nitriding the refractory metal film does not contain any semiconductor elements, so even if the refractory metal nitride film is heated at 500°C during or after the formation of the oxide dielectric film on the refractory metal nitride film, the formation of an oxide film with a low dielectric constant , such as silicon oxide, between the refractory metal nitride film and the oxide dielectric film is prevented.

As shown in FIG. 1 , an impurity diffusion layer 2a into which phosphorus or arsenic has been introduced may be formed in advance in the silicon substrate 11 below the capacitor formation region.

The amorphous silicon film 13 shown in FIG. 14(b) is patterned by photolithography and remains on the field oxide film 12 in the capacitor formation region and its periphery.

[Brief explanation of the drawings]
Figure 1
1A to 1C are cross-sectional views (part 1) illustrating a process for fabricating a capacitor according to a first embodiment of the present invention.
Figure 2
2A to 2C are cross-sectional views (part 2) illustrating the steps of forming the capacitor according to the first embodiment of the present invention.
Figure 3
3A to 3C are cross-sectional views (part 3) illustrating the method for producing a capacitor according to the first embodiment of the present invention.
Figure 4
FIG. 4 is a distribution diagram of constituent elements in the film thickness direction in a conventional capacitor in which a Ta ₂ O ₅ film is formed directly on a tungsten film without nitriding the surface of the tungsten film.
Figure 5
FIG. 5 is a distribution diagram of the constituent elements in the film thickness direction in the case where the surface of the tungsten film is nitrided and a _Ta2O5 film is formed on the tungsten film via a tungsten _nitride film in the capacitor according to the first embodiment of the present invention.
Figure 6
FIG. 6 is a cross-sectional photograph of a film constituting a conventional capacitor.
Figure 7
FIG. 7 is a diagram that schematically illustrates FIG.
Figure 8
FIG. 8 is a cross-sectional photograph of a film constituting the capacitor according to the first embodiment of the present invention.
Figure 9
FIG. 9 is a diagram that schematically illustrates FIG.
Figure 10
FIG. 10 is a diagram showing the relationship between the leakage current and the applied voltage of the capacitor according to the first embodiment of the present invention.
Figure 11
FIG. 11 is a diagram showing the relationship between the leakage current and the applied voltage of a conventional capacitor.
Figure 12
12A to 12C are cross-sectional views showing a process for fabricating a capacitor according to a second embodiment of the present invention.
Figure 13
FIG. 13 is a cross-sectional view showing a capacitor portion of a DRAM according to a third embodiment of the present invention.
FIG. 14
14A to 14C are cross-sectional views (part 1) showing the steps of forming a capacitor according to the fourth embodiment of the present invention.
Figure 15
15A to 15C are cross-sectional views (part 2) showing the steps of forming a capacitor according to the fourth embodiment of the present invention.
FIG. 16
FIG. 16 shows XRD spectra of a tungsten film and a silicon film formed on a silicon film with a high impurity concentration after heating in the manufacturing process of a capacitor according to the fourth embodiment of the present invention.
FIG. 17
FIG. 17 shows XRD spectra of a tungsten film and a silicon film formed on a silicon film with a low impurity concentration in a conventional capacitor manufacturing process after heating.
FIG. 18
FIG. 18 shows an XRD spectrum of a tungsten film grown without using silane and an underlying silicon film after heating in the manufacturing process of a capacitor according to the fourth embodiment of the present invention.
FIG. 19
FIG. 19 shows an XRD spectrum of a tungsten film grown using silane and an underlying silicon film after heating in a conventional capacitor manufacturing process.
Figure 20
FIG. 20 is a diagram showing the generation of tungsten silicide depending on the heating temperature after forming a silicon film and a tungsten film having an impurity concentration of 1×10 ²⁰ atoms/cm ³ in the manufacturing process of the capacitor of the present invention.
Figure 21
FIG. 21 is a diagram showing the generation of tungsten silicide depending on the heating temperature after forming a silicon film and a tungsten film having an impurity concentration of 5×10 ²⁰ atoms/cm ³ in the manufacturing process of the capacitor of the present invention.
Figure 22
FIG. 22 is a diagram showing the generation of tungsten silicide depending on the heating temperature after forming a silicon film and a tungsten film having an impurity concentration of 1×10 ²¹ atoms/cm ³ in the manufacturing process of the capacitor of the present invention.
Figure 23
FIG. 23 is a cross-sectional view showing a capacitor according to a fifth embodiment of the present invention.
[Explanation of symbols]
1...silicon substrate, 2a...source diffusion region, 2b...drain diffusion region, 3...insulating film, 4...contact hole, 5...polysilicon film, 6...tungsten film, 7, 9...tungsten nitride film (barrier metal film), 8...tantalum oxide film, 101, 101a...lower electrode, 102, 102a...upper electrode, 103, 103a...capacitor, 11...silicon substrate (semiconductor substrate), 12...field oxide film, 13...silicon film, 14...tungsten film, 15...tungsten _nitride film, 16... _Ta2O5 film, 17...titanium nitride film, 18...interlayer insulating film, 30...ruthenium metal film.