JPH04312919A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To reduce an area of a contacting part, and at the same time to isolate surely a conductive film in the vicinity of a contact hole from a wiring film located at the inside wall of the contact hole. CONSTITUTION:The end face of a conductive layer 14 exposed in a contact hole 17 is oxidized so that conductive layer 14 is isolated from a wiring film 16 exposed in a contact hole 17. The oxidized part of the conductive film 14 has merely and altered composition resulting from the same part of the conductive film 14 and in this case, a traditional coating material is not used for covering a part of a secondary insulating film. Therefore, a patterning process becomes unnecessary for a coating part of a conductive film of the secondary insulating film, and moreover a space reserved for misalignment can be saved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a structure in which, for example, a conductive film is provided near a contact hole in which a wiring film is formed, and a method for manufacturing the same.

0002

2. Description of the Related Art A conventional semiconductor device of this type is one shown in FIG. 3, for example. This figure shows an example of a structure in which a capacitor is formed near a contact hole. In the figure, 50 is a semiconductor substrate, 51 is an isolation oxide film, 5
2 is an impurity diffusion layer, 53 is a first insulating film, 54 is a conductive film, 55 is a second insulating film, 56 is a wiring film, and 57 is a contact hole. Note that the first insulating film 53, the conductive film 54, and the second insulating film 55 constitute a capacitor. In this structure, the end face of the conductive film 54 on the contact hole 57 side is covered with a second insulating film 55, and the conductive film 54 and the wiring film 56 are insulated and separated by the second insulating film 55. .

A method of manufacturing a semiconductor device having such a structure will be explained with reference to FIG.

■ LOCO on the surface of the semiconductor substrate 50
An isolation oxide film 51 is formed by the S method, and a first insulating film 53 and a conductive film 54 are sequentially laminated above it [see FIG. 4(a)]. The first insulating film 53 is made of a silicon oxide film or the like, and the conductive film 54 is made of a polysilicon film doped with an impurity such as phosphorus, and both are formed by, for example, a CVD method.

[0005] The conductive film 54 above the portion of the semiconductor substrate 50 where the isolation oxide film 51 does not exist is patterned using photolithography to expose the surface of the first insulating film 53, and a second insulating film 53 is formed on the entire surface above the conductive film 54. An insulating film 55 is laminated (see FIG. 4(b)). This second insulating film 55 is the same as the first insulating film 53.

[0006] ■ The first insulating film 53 and the second insulating film 55 stacked above the portion of the semiconductor substrate 50 where the isolation oxide film 51 is not present are patterned by photolithography to expose the surface of the semiconductor substrate 50. [See Figure 4(c)]. This patterned portion is the contact hole 57. This contact hole 57
The pore diameter is smaller than that of the conductive film 54, and the end surface of the conductive film 54 is covered with a second insulating film 55.

[0007] By ion-implanting impurities such as phosphorus into the exposed surface of the semiconductor substrate 50 through the contact hole 57 and diffusing them, an N+ type impurity diffusion layer 52, for example, is obtained [see FIG. 4(d)].

■ Inside the contact hole 57 and the second
A wiring film 56 made of aluminum or the like is coated on the surface of the insulating film 55 by sputtering technology. This wiring film 56 is made by CVD of a polysilicon film doped with impurities such as phosphorus.
It may be formed by a method. This wiring film 56 is then patterned into a predetermined pattern by photolithography, resulting in a pattern as shown in FIG.

[0009]

However, the conventional semiconductor device described above has the following problems.

That is, in forming the contact hole 57, the conductive film 54 is deposited in step (1) and the second,
The first insulating films 55 and 53 are patterned, respectively.
Misalignment of the exposure mask is likely to occur during the second patterning, and in some cases, a second mask covering the exposed end surface of the conductive film 54 may be used during the second patterning.
There is a risk that the insulating film 55 will be removed. Therefore,
The thickness of the portion of the second insulating film 55 that covers the exposed end surface of the conductive film 54 (see H in FIG. 3) must be set to be large in consideration of the above-mentioned misalignment. For these reasons, conventionally it has not been possible to reduce the area of the contact portion, which has been an obstacle to miniaturization.

The present invention was devised in view of the above circumstances, and an object thereof is to simplify the manufacturing process and reduce the area of the contact portion.

0012

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the present invention has the following configuration.

In the semiconductor device of the present invention, a large number of films including conductive films are stacked on a semiconductor substrate, and an impurity diffusion layer formed on the surface of the semiconductor substrate is exposed in a predetermined portion of the large number of films. A structure in which a contact hole is provided and a wiring film is coated from the surface of the impurity diffusion layer of the semiconductor substrate to the inner surface of the contact hole, that is, the exposed end surfaces of the plurality of films and the top layer surface of the plurality of films, The conductive film is characterized in that an end face portion exposed to the contact hole side is oxidized.

A method for manufacturing a semiconductor device according to the present invention includes the steps of: stacking a large number of films including conductive films on a semiconductor substrate; forming contact holes in predetermined portions of the large number of films; a step of forming an impurity diffusion layer on the surface of the semiconductor substrate exposed from the contact hole, a step of oxidizing the exposed end surface portion of the conductive film among the many films exposed on the inner surface of the contact hole, and a step of forming an impurity diffusion layer on the surface of the impurity diffusion layer of the semiconductor substrate. The method is characterized in that it includes a step of covering the inner surface of the contact hole, that is, the exposed end surfaces of the plurality of films, and the surface of the uppermost layer of the plurality of films with a wiring film.

[0015]

[Operation] Since the end face portion of the conductive film exposed in the contact hole is oxidized, this oxidized portion insulates and separates the wiring film formed on the inner surface of the contact hole from the conductive film. Since the conventional insulating film cover is not used, the area of the contact portion can be reduced. Moreover, since the conventional patterning of the insulating film cover is not required, there is no need to secure a large space for misalignment.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a semiconductor device according to an embodiment of the present invention. The figure shows an example of a structure in which a capacitor is formed near a contact hole. In the figure, 1
0 is a semiconductor substrate, 11 is an isolation oxide film, 12 is an impurity diffusion layer, 13 is a first insulating film, 14 is a conductive film, 15 is a second insulating film, 16 is a wiring film, and 17 is a contact hole. Note that the first insulating film 13, the conductive film 14, and the second insulating film 15
A capacitor is constructed with. In this structure,
The exposed end face portion of the conductive film 14 on the side of the contact hole 17 is oxidized, and the conductive film 14 and the wiring film 16 are insulated and separated by this oxidized portion, that is, the oxidized portion 18 .

A method of manufacturing a semiconductor device having such a structure will be explained with reference to FIG.

■ LOCO on the surface of the semiconductor substrate 10
An isolation oxide film 11 is formed by the S method, and above this a first insulating film 13, a conductive film 14, a second insulating film 15,
Nitride films 20 are sequentially laminated [see FIG. 2(a)]. First,
The second insulating films 13 and 15 are made of a silicon oxide film, etc., and the conductive film 14 is made of a polysilicon film doped with impurities such as phosphorus, and both are made by, for example, CVD.
Formed by law. The nitride film 20 is also formed by the CVD method.

■ Patterning the nitride film 20, second insulating film 15 and conductive film 14 above the portion of the semiconductor substrate 10 where the isolation oxide film 11 does not exist by photolithography to expose the surface of the first insulating film 13 let [
See Figure 2(b)].

■ The patterned nitride film 20 and the second insulating film 1 are heat-treated in a quartz furnace.
5 and each end face portion of the conductive film 14, the conductive film 1
The exposed end face portion of No. 4 is oxidized [see FIG. 2(c)]. Note that the patterned nitride film 20 and the second insulating film 15
A thin thermal oxide film (not shown) is formed on the end face portion of the conductive film 14, the surface of the first insulating film 13, and the like. The end face portion of the conductive film 14 is oxidized and therefore bulges out a little more than the end faces of the other films.

(2) The oxidized bulge portion of the conductive film 14 and the first insulating film 13 are removed by anisotropic etching using the nitride film 20 as a mask, and the surface of the semiconductor substrate 10 is exposed. A contact hole 17 is now obtained. After that, from the contact hole 17 to the semiconductor substrate 1
Impurities such as phosphorus are ion-implanted into the exposed surface of 0.
By diffusing, for example, an N+ type impurity diffusion layer 1
2 [see Figure 2(d)].

■ The nitride film 20 is removed by selective etching to remove the inside of the contact hole 17 and the second insulating film 1.
A wiring film 16 made of aluminum or the like is coated on the surface of 5 by sputtering technique. This wiring film 16 can be formed by a CVD method, such as a polysilicon film doped with an impurity such as phosphorus. This wiring film 16 is
Thereafter, it is patterned into a predetermined pattern using photolithography technology, resulting in the result as shown in FIG.

It should be noted that the present invention is not limited to the above embodiments, but also includes the following. For example, the conductive film 14 may be anything as long as it can be oxidized. Further, in the above embodiment, the contact portion of the wiring film 16 with respect to the impurity diffusion layer 12 of the semiconductor substrate 10 is taken as an example, but the present invention can also be applied to, for example, a contact structure of the wiring film with respect to the wiring film on the semiconductor substrate. . Furthermore, although an example is given in which the present invention is applied to a structure in which a capacitor is formed near a contact hole, the present invention can also be applied to insulation separation between a gate electrode and a drain wiring film or a source wiring film of a CMOS transistor. can.

[0025]

[Effects of the Invention] As explained above, according to the present invention,
The end face portion of the conductive film exposed inside the contact hole is oxidized, and this oxidized portion insulates and separates the conductive film from the wiring film formed on the inner surface of the contact hole, so there is no need to use a conventional insulating film cover. disappears. Therefore, patterning of the conventional insulating film cover is no longer necessary, simplifying the manufacturing process, and there is no need to secure space for misalignment, making it possible to reduce the area of the contact area and achieve miniaturization. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view showing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process diagram showing a manufacturing method according to an embodiment of the present invention.

FIG. 3 is a vertical side view showing a conventional semiconductor device.

FIG. 4 is a process diagram showing a conventional manufacturing method.

[Explanation of symbols]

10 Semiconductor substrate
12 Impurity diffusion layer 13 First insulating film
14 Conductive film 15 Second insulating film 16 Wiring film 17 Contact hole 18
Oxidized part of conductive film

Claims (2)

[Claims] Claims: 1. A number of films including conductive films are stacked on a semiconductor substrate, and a contact hole is provided in a predetermined portion of the number of films to expose an impurity diffusion layer formed on the surface of the semiconductor substrate. , a semiconductor device having a structure in which a wiring film is coated from the surface of the impurity diffusion layer of the semiconductor substrate to the inner surface of the contact hole, that is, the exposed end surfaces of the plurality of films and the top layer surface of the plurality of films, A semiconductor device characterized in that an end face portion of the film exposed to the contact hole side is oxidized. 2. A step of stacking a large number of films including conductive films on a semiconductor substrate, a step of forming a contact hole in a predetermined portion of the plurality of films, and a step of stacking a plurality of films including a conductive film on a semiconductor substrate, and a step of stacking a plurality of films including a conductive film on a semiconductor substrate. a step of forming an impurity diffusion layer; a step of oxidizing the exposed end surface portion of the conductive film among the many films exposed on the inner surface of the contact hole; A method for manufacturing a semiconductor device, comprising the step of covering the exposed end surface of the film and the surface of the uppermost layer of the plurality of films with a wiring film.