JPH0883917A - Semiconductor device - Google Patents

Abstract

PURPOSE: To reduce crystal grain boundaries and to decrease the leakage current of the boundaries by providing a first conductivity type high concentration impurity layer, a first conductivity type low concentration impurity layer, and a second conductivity type high concentration impurity layer, forming the first conductivity type low concentration impurity layer of a polycrystalline silicon film and containing halogen in the first conductivity type low concentration impurity layer. CONSTITUTION: An insulating film 13 made of a silicon dioxide film is provided on a semiconductor substrate 11, and a polycrystalline silicon film 17 for crystallizing an amorphous silicon film is provided on the film 13. A first conductivity type low concentration impurity layer 19 containing fluorine is provided on the film 17. Further, a first conductivity type high concentration impurity layer 21 and a second conductivity type high concentration impurity layer 23 are provided on the film 17. Thus, the grain size of the film 17 is increased to reduce the number of the grains. Further, a dangling bond existing in the boundary is terminated to be stabilized, thereby reducing a leakage current. As a result, excellent diode characteristics are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a semiconductor device, and more particularly to a structure of a diode provided on a semiconductor substrate via an insulating film.

[0002]

2. Description of the Related Art The structure of a conventional diode made of a polycrystalline silicon film provided via an insulating film on a semiconductor substrate will be described with reference to the sectional view of FIG.

As shown in FIG. 5, an insulating film 13 is provided on the semiconductor substrate 11. A polycrystalline silicon film 25 is provided on this insulating film 13.

Further, a polycrystalline silicon film 25 is provided with a high-concentration impurity layer 21 of the first conductivity type and a high-concentration impurity layer 23 of the second conductivity type to form a semiconductor device having a diode.

[0005]

In the diode described with reference to FIG. 5, the leakage current in the boundary region between the high-concentration impurity layer 21 of the first conductivity type and the high-concentration impurity layer 23 of the second conductivity type. Becomes large, and sufficient diode characteristics cannot be obtained.

This is because the conventional semiconductor device uses the polycrystalline silicon film 25.
A stable crystal was formed during the formation of the film of No. 5. Even if a heat treatment is applied to the polycrystalline silicon film 25 having this stable crystal structure, it is difficult for the crystal to grow and there are many crystal grain boundaries.

Further, at the boundary between the first-conductivity-type high-concentration impurity layer 21 and the second-conductivity-type high-concentration impurity layer 23, a large number of these crystal grain boundaries exist, so that a large amount of leak current flows through the crystal grain boundaries. Occurs and does not exhibit diode characteristics.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a structure of a semiconductor device having excellent diode characteristics with reduced leakage current.

[0009]

In order to achieve the above object, the semiconductor device of the present invention employs the following means.

In the semiconductor device of the present invention, a first-conductivity-type high-concentration impurity layer, a first-conductivity-type low-concentration impurity layer, and a second-conductivity-type low-concentration impurity layer which are provided on a semiconductor substrate via an insulating film made of a silicon oxide film.
A high-concentration impurity layer of a conductive type is provided, and the low-concentration impurity layer of the first conductive type is made of a polycrystalline silicon film and contains halogen.

In the semiconductor device of the present invention, a first-conductivity-type high-concentration impurity layer, a first-conductivity-type low-concentration impurity layer, and a second-conductivity-type low-concentration impurity layer which are provided on a semiconductor substrate via an insulating film made of a silicon oxide film.
A high-concentration impurity layer of a conductive type is provided, and the low-concentration impurity layer of the first conductive type is made of a polycrystalline silicon film and contains fluorine.

[0012]

In the semiconductor device of the present invention, the polycrystalline silicon film obtained by crystallizing the amorphous silicon film is used as the low concentration impurity layer of the first conductivity type. Therefore, the first-conductivity-type low-concentration impurity layer of the present invention is approximately three times as large as the crystal grain size of the conventional polycrystalline silicon film, and the number of crystal grain boundaries can be reduced.

Further, by introducing fluorine into the polycrystalline silicon film, dangling bonds existing at the crystal grain boundaries are terminated and stabilized by the fluorine.
With these, the leak current at the crystal grain boundary can be reduced. As a result, it becomes possible to reduce the leakage current, and it is possible to obtain a diode characteristic with good characteristics.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. The structure of the semiconductor device of the present invention will be described with reference to the sectional view of FIG.

As shown in FIG. 3, an insulating film 13 made of a silicon dioxide film is provided on a semiconductor substrate 11, and a polycrystalline silicon film 17 for crystallizing an amorphous silicon film is provided on the insulating film 13.

Then, a first conductivity type low concentration impurity layer 19 containing fluorine is provided on the polycrystalline silicon film 17. Further, by providing the high-concentration impurity layer 21 of the first conductivity type and the high-concentration impurity layer 23 of the second conductivity type in the polycrystalline silicon film 17, a semiconductor device having a diode is obtained.

As shown in FIG. 3, the semiconductor device of the present invention uses a polycrystalline silicon film 17 obtained by crystallizing the amorphous silicon film 15. Therefore, as compared with the crystal grain size of the conventional polycrystalline silicon film 25 shown in FIG. 5, the crystal grain size of the polycrystalline silicon film 17 of the present invention is approximately three times as large as the crystal grain size of the conventional polycrystalline silicon film 25. Can be reduced.

Further, by introducing fluorine into the polycrystalline silicon film 17, dangling bonds existing at the crystal grain boundaries are terminated by the fluorine and stabilized. With these, the leak current at the crystal grain boundary can be reduced.

As a result, in the diode of the present invention, it is possible to obtain good diode characteristics with reduced leakage current.

Next, a manufacturing method for forming the structure of the semiconductor device shown in FIG. 3 will be briefly described with reference to the sectional views of FIGS.

First, as shown in FIG. 1, the semiconductor substrate 11 is oxidized at a temperature of 1000 ° C. to form an insulating film 13 made of a silicon dioxide film.

After that, a film thickness of 450 is obtained by a chemical vapor deposition method using monosilane as a reaction gas at a temperature of 540 ° C.
An amorphous silicon film 15 having a thickness of nm is formed.

Thereafter, as shown in FIG. 2, the amorphous silicon film 15 is crystallized in a nitrogen atmosphere at a temperature of 1000 ° C. for a time of 30 minutes to form a polycrystalline silicon film 17.

The polycrystalline silicon film 17 formed by crystallizing the amorphous silicon film 15 is ion-implanted with boron difluoride (BF2) at an ion implantation amount of about 1 × 10 ¹³ atoms / cm ^-2. To introduce the low-concentration impurity layer 19 of the first conductivity type.

Then, in a nitrogen atmosphere, a temperature of 1000
Fluorine is diffused into the crystal grain boundaries by heat treatment under the conditions of 30 ° C. and 30 minutes.

Subsequently, as shown in FIG. 3, a photosensitive resin (not shown) is formed on the entire surface of the polycrystalline silicon film 17 by a spin coating method, and exposed to light and developed using a predetermined photomask. Then, the photosensitive resin is patterned into islands forming a diode.

The polycrystalline silicon film 17 is etched by using a reactive ion etching apparatus and a mixed gas of sulfur hexafluoride and oxygen as an etching gas. Then, the photosensitive resin used for the etching mask is removed.

Subsequently, a photosensitive resin (not shown) is formed on the entire surface of the polycrystalline silicon film 17 by a spin coating method. Then, a predetermined photomask is used to perform exposure and development, and the photosensitive resin is patterned so that the formation region of the high-concentration impurity layer 21 of the first conductivity type is opened.

After that, the high-concentration impurity layer 21 of the first conductivity type is formed.
In order to form the film, boron is ion-implanted by the ion-implantation method under the condition of about 3 × 10 ¹⁵ atoms / cm ⁻² . Then, the photosensitive resin used for ion implantation is removed.

Subsequently, a photosensitive resin (not shown) is formed on the entire surface of the polycrystalline silicon film 17 by a spin coating method. After that, exposure and development processing is performed using a predetermined photomask, and the photosensitive resin is patterned so that the formation region of the second conductivity type high concentration impurity layer 23 is opened.

After that, the second-conductivity-type high-concentration impurity layer 23 is formed.
By using an ion implantation method for forming Pd with phosphorus as an ion implantation amount of about 3 × 10 ¹⁵ atoms / cm ⁻² . Then, the photosensitive resin used for ion implantation is removed.

Although not shown in the subsequent steps, an interlayer insulating film made of a silicon oxide film containing phosphorus and boron is formed by a chemical vapor deposition method, and a photosensitive resin is used as an etching mask to contact the interlayer insulating film. A semiconductor device having a diode, in which a hole is formed, a wiring material made of aluminum containing silicon and copper is formed by a sputtering method, and the wiring material is etched by using a photosensitive resin as an etching mask to form a wiring. Can be obtained.

In the above description of the examples, the example in which fluorine is introduced into the low concentration impurity layer 19 of the first conductivity type has been explained, but halogen such as chlorine, bromine or iodine may be introduced in addition to fluorine. .

[0034]

As is clear from the above description, in the structure and manufacturing method of the semiconductor device of the present invention, a polycrystalline silicon film obtained by crystallizing an amorphous silicon film is used,
Furthermore, by introducing fluorine into the crystal grain boundaries in this polycrystalline silicon film, it is possible to reduce the number of crystal grain boundaries and the leakage current generated at the crystal grain boundaries.

The diode characteristics of the semiconductor device of the present invention and the conventional semiconductor device are shown in the graph of FIG. The characteristic of the present invention is shown by the solid line 27, and the characteristic of the prior art is shown by the broken line 29. As shown in FIG. 4, the semiconductor device of the present invention has good diode characteristics as compared with the conventional one, and the leakage current when reverse bias is applied is about 1/100. As a result, it is possible to obtain a semiconductor device having a diode having better characteristics than the conventional semiconductor device.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a semiconductor device according to an embodiment of the present invention.

FIG. 4 is a graph showing the diode characteristics of the semiconductor device of the present invention and a conventional example in comparison.

FIG. 5 is a cross-sectional view showing a semiconductor device in a conventional example.

[Explanation of symbols]

 Reference Signs List 11 semiconductor substrate 13 insulating film 17 polycrystal silicon film 19 first conductivity type low concentration impurity layer 21 first conductivity type high concentration impurity layer 23 second conductivity type high concentration impurity layer

Claims (2)

[Claims] 1. A first-conductivity-type high-concentration impurity layer, a first-conductivity-type low-concentration impurity layer, and a second-conductivity-type high-concentration impurity layer which are provided on a semiconductor substrate with an insulating film made of a silicon oxide film interposed therebetween. And a first conductivity type low-concentration impurity layer made of a polycrystalline silicon film containing halogen. 2. A first-conductivity-type high-concentration impurity layer, a first-conductivity-type low-concentration impurity layer, and a second-conductivity-type high-concentration impurity layer which are provided on a semiconductor substrate through an insulating film made of a silicon oxide film. And a low-concentration impurity layer of the first conductivity type is made of a polycrystalline silicon film and contains fluorine.