JP3277807B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 2 is a schematic sectional view showing a manufacturing process of a lateral diode of a conventional semiconductor device. A silicon oxide film 2 and a polysilicon layer 6a as an electrode are formed on the n-type single crystal silicon substrate 1 by a plasma CVD method or the like, and a photoresist is applied on the polysilicon layer 6a, and then exposed and developed. By patterning into a predetermined shape and etching the polysilicon layer 6a using the patterned photoresist as a mask,
The polysilicon layer 6a is patterned into a predetermined shape, and the photoresist is removed by plasma ashing or the like (FIG. 2A).

Next, a silicon oxide film 2b is formed on the entire surface of the n-type single crystal silicon substrate 1 on which the polysilicon layer 6a is formed by a plasma CVD method or the like.
b, after applying a photoresist (not shown), patterning into a predetermined shape by performing exposure and development,
The silicon oxide film 2b is etched into a predetermined shape by etching the silicon oxide film 2b using the patterned photoresist as a mask, and the photoresist is removed by plasma ashing or the like (FIG. 2).
(B)).

Subsequently, a polysilicon layer 6b as an electrode is formed by a plasma CVD method or the like.
The polysilicon layer 6b is patterned into a predetermined shape by performing etching using a photoresist (not shown) patterned into a predetermined shape applied on the mask b, and the photoresist is removed (FIG. 2C). ).

Subsequently, a silicon oxide film 8 is formed on the entire surface of the n-type single-crystal silicon substrate 1 on which the polysilicon layer 6b is formed by a plasma CVD method or the like (FIG. 2D), and is patterned into a predetermined shape. An opening 9a is formed by etching the silicon oxide film 8 using the photoresist (not shown) as a mask, the photoresist is removed, and then a photoresist (not shown) is applied again.
Exposure and development are performed to pattern into a predetermined shape, and the patterned photoresist is used as a mask to etch the polysilicon layer 6b and the silicon oxide film 2, thereby forming openings 9b and 9c, and removing the photoresist. (FIG. 2 (e)).

Finally, a horizontal diode is manufactured by forming a metal wiring 10 so as to fill the openings 9a to 9c.

In this lateral diode, when a high voltage is applied between the two metal wirings 10, the potential distribution of the drift region is equalized by the capacitive coupling of the polysilicon layers 6a and 6b as opposing electrodes. And contributed to the high breakdown voltage of the device.

[0008]

However, in the manufacturing process of the lateral diode having the above-described structure, a process of forming the polysilicon layer 6b of the second layer electrode is required as compared with a general manufacturing process of the lateral diode. And the first layer electrode and 2
A step of forming a silicon oxide film 2b, which is an interlayer film between the electrodes of the layer, is added, so that there is a problem that the process time becomes longer and the number of masks increases.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to easily form an electrode having capacitive coupling and to realize a high withstand voltage of an element. It is an object of the present invention to provide a semiconductor device and a method for manufacturing the same.

[0010]

According to the first aspect of the present invention,
A first conductivity type silicon substrate having a convex portion on one main surface, a first conductivity type high concentration impurity region and a second conductivity type impurity region formed on one main surface of the first conductivity type silicon substrate; And removing the first silicon oxide film formed on one main surface of the first conductivity type silicon substrate and the protrusion on the first silicon oxide film so as to have a protrusion near the protrusion. An electrode formed at the location, a second silicon oxide film formed on the protrusion and on the electrode, and the first silicon oxide film on the first conductivity type high concentration impurity region and the second conductivity type impurity region. An opening formed in the film, the electrode, and the second silicon oxide film; and a metal wiring formed so as to fill the opening, and the first conductive type high-concentration impurity is formed through the metal wiring. Region and said electrode, said second conductivity type impurity region and And electrodes are connected, the protrusion through the convex portion is characterized in that it has to be capacitively coupled.

According to a second aspect of the present invention, the first conductivity type high concentration impurity region and the second conductivity type impurity region are formed by performing ion implantation and thermal diffusion at desired positions on the surface of the first conductivity type silicon substrate. By etching a main surface of the first conductivity type semiconductor substrate using a photoresist as a mask to form a plurality of protrusions, the photoresist is removed, and a first silicon oxide film and an electrode are formed. ,
After removing the electrode on the convex portion by etching using a photoresist as a mask, the photoresist is removed, and a second silicon oxide film is formed on the entire surface of the first conductivity type silicon substrate on which the electrode is formed. Using the photoresist as a mask, the first silicon oxide film on the first conductivity type high concentration impurity region and the second conductivity type impurity region,
After forming an opening in the electrode and the second silicon oxide film, the photoresist is removed, a metal wiring is formed so as to fill the opening, and the first conductive type high concentration impurity region is formed through the metal wiring. The electrode, the second conductivity type impurity region, and the electrode are connected to each other, and the electrode has a protrusion near the protrusion, and the protrusion is capacitively coupled via the protrusion. It is a feature.

According to the third aspect of the present invention, the first conductivity type high concentration impurity region and the second conductivity type impurity region are formed by performing ion implantation and thermal diffusion at desired positions on the surface of the first conductivity type silicon substrate. Thereafter, a silicon oxide film and a silicon nitride film are formed on one main surface of the first conductivity type silicon substrate, an opening is formed at a desired position of the silicon oxide film using a photoresist as a mask, and then the photoresist is removed. LOCOS oxidation is performed using the silicon nitride film in which the opening is formed as a mask to form a projection made of a silicon oxide film. Then, the silicon nitride film is removed, and the silicon oxide film and the projection are removed. A plurality of protrusions are formed on one main surface of the silicon substrate of the first conductivity type by being removed by etching, and the first conductivity type formed with the protrusions is formed. Forming a first silicon oxide film and an electrode on one main surface of the silicon substrate, removing the electrode formed on the convex portion by etching using a photoresist as a mask, removing the photoresist, and removing the first conductive film; Forming a second silicon oxide film on the entire surface of the type silicon substrate on which the electrodes are formed, and using the photoresist as a mask to form the first silicon oxide film on the first conductive type high concentration impurity region and the second conductive type impurity region. An opening is formed in the film, the electrode, and the second silicon oxide film, a metal wiring is formed so as to fill the opening, and the first conductivity type high-concentration impurity region, the electrode, and the second electrode are formed through the metal wiring. The two-conductivity-type impurity region and the electrode are connected, and the electrode has a protrusion near the protrusion, and the protrusion is capacitively coupled via the protrusion. Is shall.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the second or third aspect, when the electrode formed on the convex portion is etched, the opening is formed at the same time. It is characterized by doing so.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a manufacturing process of a lateral diode of a semiconductor device according to one embodiment of the present invention. First, after applying a photoresist (not shown) on the n-type single-crystal silicon substrate 1, an opening is formed by performing exposure and development, and boron (B) is formed using the photoresist in which the opening is formed as a mask. The p-type impurity such as ⁺ ) is ion-implanted and thermally diffused to form a p-type impurity diffusion region 1a, and the photoresist is removed by plasma ashing or the like.

Subsequently, after applying a photoresist (not shown) on the n-type single crystal silicon substrate 1, an opening is formed by performing exposure and development, and the photoresist having the opening formed is masked. Then, an n-type high-concentration impurity diffusion region 1b such as high-concentration phosphorus (P ⁺ ) is formed, and the photoresist is removed.

Next, a silicon oxide film 2 and a silicon nitride film 3 are formed on an n-type single crystal silicon substrate 1.
(A)) After applying a photoresist 4 on the silicon nitride film 3, the photoresist 4 is patterned into a predetermined shape by performing exposure and development, and the silicon nitride film 3 is patterned using the patterned photoresist 4 as a mask. The projections 3a made of the silicon nitride film 3 are formed by etching (FIG. 1B), and the photoresist is removed by plasma ashing or the like. Here, an example of a method of forming the silicon oxide film 2 can be formed by a plasma CVD method using silane (SiH ₄ ) as a source gas, and an example of a method of forming the silicon nitride film 3 is silane (SiH _4). ) And ammonia (NH ₃ ) as source gases by a plasma CVD method. An example of the method for etching the silicon nitride film 3 is a method for etching with fluorine radicals in CF ₄ gas plasma.

The projection 3 made of the silicon nitride film 3
LOCOS (Local Oxidation of
Silicon) oxidation is performed to form a convex portion 2a made of a silicon oxide film (FIG. 1C). After removing the convex portion 3a, the silicon oxide film 2 and the convex portion 2a are removed by etching. Forming the convex portion 1c (FIG. 1)
(D)). Here, as an example of the etching of the silicon oxide film 2 and the protrusion 2a, an HF aqueous solution is used.

In this embodiment, the LOCOS
Although the projections 1c are formed on the surface of the n-type single-crystal silicon substrate 1 by performing oxidation, the present invention is not limited to this.
The protrusion 1c may be formed by performing etching using a photoresist as a mask.

Subsequently, a silicon oxide film 5 and a polysilicon layer 6 as an electrode are formed on the entire surface of the n-type single-crystal silicon substrate 1 on which the projections 1c are formed, and a photoresist 7 is formed on the polysilicon layer 6. After the application, patterning into a predetermined shape is performed by performing exposure and development, and etching is performed using the patterned photoresist 7 as a mask to remove the polysilicon layer 6 formed on the projection 1c (FIG. 1 (f) After that, the photoresist 7 is removed by plasma ashing or the like. Here, as an example of a method for forming the polysilicon layer 6, it can be formed by a plasma CVD method using silane (SiH ₄ ) as a source gas. In the present embodiment, phosphoryl trichloride ( POCl ₃ ) ion implantation and thermal diffusion are performed. As an example of the etchant for the polysilicon layer 5, a mixed solution of hydrogen fluoride (HF) and nitric acid (HNO ₃ ) is used.

Subsequently, a silicon oxide film 8 is formed on the entire surface of the n-type single crystal silicon substrate 1 on which the projections 1c are formed by a plasma CVD method or the like, and a photoresist (not shown) is formed on the silicon oxide film 8. Is applied, patterning is performed to a predetermined shape by performing exposure and development, an opening 9a is formed by etching the silicon oxide film 8 using the patterned photoresist as a mask, and after removing the photoresist, A photoresist (not shown) is applied again, exposed and developed to be patterned into a predetermined shape, and the polysilicon layer 6 and the silicon oxide film 5 are etched using the patterned photoresist as a mask to form an opening. 9b and 9c are formed, and the photoresist is removed (FIG. 1 (g)).

In this embodiment, after the silicon oxide film 8 is formed, the openings 9a to 9a are formed by etching.
Although the opening 9b is formed at the same time when the polysilicon layer 6 formed on the projection 1c is etched, the mask is not limited to this. Can be reduced.

Finally, a lateral diode can be manufactured by forming a metal wiring 10 of aluminum or the like so as to fill the openings 9a to 9c. Here, as an example of a method for forming the metal wiring 10, the metal wiring 10 can be formed by forming an aluminum layer by performing sputtering using aluminum as a target and patterning the aluminum layer into a predetermined shape by using a photolithography technique and an etching technique.

Accordingly, in the present embodiment, the convex portion 1c
Is formed, the polysilicon layer 6 serving as a single-layer electrode is formed.
Is formed, a capacitive coupling structure can be realized, and the process time can be reduced. In addition, since the convex portion 1c is formed on one main surface of the n-type single crystal silicon substrate 1, when obtaining a desired thickness of the silicon oxide film 5, the silicon oxide film 6 is formed by thermal oxidation. Even so, the step of the convex portion 1c does not decrease. Furthermore, since the convex portion 1c is formed by LOCOS oxidation,
The shape of the convex portion 1c is on a curved surface, which makes it easier to apply the photoresist when applying the photoresist, thereby preventing the occurrence of uneven coating.

[0024]

According to the first to third aspects of the present invention, a first conductivity type silicon substrate having a convex portion on one main surface;
A first-conductivity-type high-concentration impurity region and a second-conductivity-type impurity region formed on one main surface of the first-conductivity-type silicon substrate; and a first-silicon oxide formed on one main surface of the first-conductivity-type silicon substrate. A film, an electrode formed on a portion of the first silicon oxide film excluding the protrusion so as to have a protrusion near the protrusion, and a second silicon oxide film formed on the protrusion and the electrode. An opening formed in the first silicon oxide film, the electrode and the second silicon oxide film on the first conductivity type high concentration impurity region and the second conductivity type impurity region, and a metal wiring formed so as to fill the opening. And the first conductive type high-concentration impurity region and the electrode, the second conductive type impurity region and the electrode are connected via the metal wiring, and the protrusion is capacitively coupled via the protrusion. Therefore, a capacitive coupling structure is realized by forming one layer of electrodes. They are possible to, an electrode having a capacitive coupling can be easily formed, and it is possible to provide a semiconductor device and a manufacturing method thereof capable of realizing a high breakdown voltage of the device.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the second or third aspect, the opening is formed at the same time as etching the electrode formed on the projection. Therefore, the number of masks can be reduced, and the process time and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process of a lateral diode of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a manufacturing process of a lateral diode of a semiconductor device according to a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 n-type single-crystal silicon substrate 1 a p-type impurity diffusion region 1 b n-type high-concentration impurity diffusion region 1 c convex portion 2 silicon oxide film 2 a convex portion 2 b silicon oxide film 3 silicon nitride film 3 a convex portion 4 photoresist 5 silicon oxide film 6 Polysilicon layer 7 Photoresist 8 Silicon oxide film 9a-9c Opening 10 Metal wiring

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yosuke Hagiwara 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. ) Surveyed field (Int.Cl. ⁷ , DB name) H01L 29/861 H01L 29/06 H01L 21/28 H01L 21/768

Claims (4)

(57) [Claims] A first conductive type silicon substrate having a convex portion on one main surface; a first conductive type high-concentration impurity region formed on one main surface of the first conductive type silicon substrate; A conductive type impurity region, a first silicon oxide film formed on one main surface of the first conductive type silicon substrate, and the protrusion on the first silicon oxide film having a protrusion near the protrusion. An electrode formed at a position except on the portion, a second silicon oxide film formed on the protrusion and on the electrode, and a first conductive type high-concentration impurity region and a second conductive type impurity region. An opening formed in the first silicon oxide film, the electrode and the second silicon oxide film; and a metal wiring formed so as to fill the opening, and the first wiring is formed through the metal wiring. The conductive type high-concentration impurity region, the electrode, and the second conductive type A semiconductor device, wherein a pure region and the electrode are connected, and the protrusion is capacitively coupled via the protrusion. 2. A first conductivity type high concentration impurity region and a second conductivity type impurity region are formed by performing ion implantation and thermal diffusion at desired positions on a surface of the first conductivity type silicon substrate,
By performing etching on one main surface of the first conductivity type semiconductor substrate using a photoresist as a mask, after forming a plurality of protrusions, removing the photoresist, forming a first silicon oxide film and an electrode, After removing the electrode on the convex portion by etching using a photoresist as a mask, the photoresist is removed, and a second silicon oxide film is formed on the entire surface of the first conductivity type silicon substrate on which the electrode is formed. After forming openings in the first silicon oxide film, the electrode and the second silicon oxide film on the first conductivity type high concentration impurity region and the second conductivity type impurity region using a photoresist as a mask, the photoresist is removed. Removing, forming a metal wiring so as to fill the opening, and through the metal wiring, the first conductivity type high concentration impurity region, the electrode, and the second conductive type. A method of manufacturing a semiconductor device, wherein an impurity region is connected to the electrode, and the electrode has a protrusion near the protrusion, and the protrusion is capacitively coupled via the protrusion. . 3. After forming a first conductive type high concentration impurity region and a second conductive type impurity region by performing ion implantation and thermal diffusion at a desired position on the surface of the first conductive type silicon substrate, Forming a silicon oxide film and a silicon nitride film on one main surface of a mold type silicon substrate, forming an opening at a desired position of the silicon oxide film using a photoresist as a mask, removing the photoresist, and removing the opening; LOCO is performed using the formed silicon nitride film as a mask.
After forming a convex portion made of a silicon oxide film by performing S oxidation, the silicon nitride film is removed, and the silicon oxide film and the convex portion are removed by etching, thereby forming one of the first conductivity type silicon substrates. Forming a plurality of convex portions on the surface, forming a first silicon oxide film and an electrode on one main surface of the first conductivity type silicon substrate having the convex portions formed thereon, and forming the first silicon oxide film and the electrode on the convex portion using a photoresist as a mask. After removing the electrode formed by etching, the photoresist is removed, a second silicon oxide film is formed on the entire surface of the first conductivity type silicon substrate on which the electrode is formed, and the photoresist is used as a mask. An opening is formed in the first silicon oxide film, the electrode, and the second silicon oxide film on the first conductivity type high concentration impurity region and the second conductivity type impurity region, and the opening is formed. A metal wiring formed to writing because,
The first conductive type high-concentration impurity region and the electrode, and the second conductive type impurity region and the electrode are connected through the metal wiring, and the electrode has a protrusion near the protrusion, and the electrode has a protrusion. A method of manufacturing a semiconductor device, wherein the protrusion is capacitively coupled via a portion. 4. The manufacturing of the semiconductor device according to claim 2, wherein the opening is formed at the same time as the etching of the electrode formed on the projection is performed. Method.