JPH06120231A - Diode and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate instability for setting a current and a breakdown voltage, in the case of a voltage lower than or equal to the breakdown voltage at the time of applying a backward bias voltage, which instability is caused by that a PN junction is formed at a crystal defect part generated under the edge a field oxide film which is selectively formed. CONSTITUTION:This diode is manufactured as follows; under the field oxide film 5 edge of an element region where, in a first low concentration diffusion region 1 formed in a semiconductor substrate 9, a first high concentration region 3 of the opposite conductivity type is formed, a second low concentration diffusion region 2 of the same conductivity type is formed. Thereby the crystal defect part formed under the field oxide film 5 edge is covered with the second low concentration diffusion region 2, so that a P-N function is not formed. Hence a current does not flow in the case of low voltage, and the setting of a breakdown voltage is facilitated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a diode and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional diode and a method of manufacturing the same will be described with reference to sectional views of FIGS. 7 to 10 and a graph of voltage-current characteristics of the diode of FIG.

First, a conventional method for manufacturing a diode will be described. First, as shown in FIG. 7, N having a specific resistance of 8 Ωcm
A photosensitive resin (not shown) having a film thickness of 1.1 μm is formed on the entire surface of the semiconductor substrate 9 of the mold by a spin coating method, exposed using a predetermined mask, and subjected to a developing treatment to remove the photosensitive resin. After patterning, phosphorus is accelerated with an acceleration energy of 100 ke using an ion implantation method using this photosensitive resin as a mask.
V and an injection amount of 9.1 × 10 ¹³ atoms / cm ² are injected to form the N-type first low-concentration diffusion region 1, and the photosensitive resin is removed.

Next, as shown in FIG. 8, a temperature of 1140 ° C.
Is heat-treated for 14 hours to activate phosphorus in the first low concentration diffusion region 1. After that, vapor phase chemical growth method (hereinafter, CV
A silicon nitride (not shown) having a film thickness of 150 nm is formed on the entire surface by D), and a photosensitive resin (not shown) having a film thickness of 1.1 μm is formed on the entire surface by spin coating, and a predetermined mask is formed. Is exposed to light and developed, a photosensitive resin is patterned on the silicon nitride on the first low-concentration diffusion region 1, and the photosensitive resin is used as a mask for reactive ion etching (hereinafter referred to as RIE). Is used to pattern the silicon nitride, and then the photosensitive resin is removed. After that, 1000 in the oxygen atmosphere with the addition of water vapor
A heat treatment at 160 ° C. is performed for 160 minutes to form silicon oxide in the element isolation region, that is, by selective oxidation, a film thickness of 710 n is obtained.
A field oxide film 5 of m silicon oxide is formed. At this time, stress is generated under the edge of the field oxide film 5, and a crystal defect 6 is generated in the first low concentration diffusion region 1. Then, the silicon nitride is removed with phosphoric acid heated to 180 ° C.

Next, as shown in FIG. 9, the film thickness is 1.1 μm.
Photosensitive resin (not shown) is formed on the entire surface by a spin coating method, exposed using a predetermined mask, and subjected to development processing.
An opening is formed in a photosensitive resin on a predetermined element region, this photosensitive resin is used as a mask, and an ion implantation method is used to accelerate boron with an acceleration energy of 25 keV and an implantation amount of 2.5 × 10 ¹⁵ a.
toms / cm ² is implanted to form the P-type first high-concentration diffusion region 3 and P with the N-type first low-concentration diffusion region 1.
The N junction is formed, and then the photosensitive resin is removed. After that, a photosensitive resin (not shown) having a film thickness of 1.1 μm is formed on the entire surface by a spin coating method, exposed using a predetermined mask, and developed to form a first high-concentration diffusion region 3. An opening is made in the photosensitive resin on the element region that has not been formed, and using this photosensitive resin as a mask, arsenic is accelerated with an acceleration energy of 60 keV and an injection amount of 3.5 × 10 ¹⁵ ato using an ion implantation method.
ms / cm ² is injected to form an N-type second high-concentration diffusion region 4 as an electrode of the N-type first low-concentration diffusion region 1, and then the photosensitive resin is removed.

Next, as shown in FIG. 10, a 550 nm-thickness interlayer insulating film 7 of silicon oxide containing phosphorus and boron is formed by CVD, and the temperature is set to 1000 ° C. in a nitrogen atmosphere.
Is heat-treated for 25 minutes to fluidize the interlayer insulating film 7, so-called reflow is performed, and the surface of the interlayer insulating film 7 is flattened. After that, a photosensitive resin (not shown) having a film thickness of 1.1 μm, which is a photosensitive material, is formed on the entire surface, and exposed and developed using a predetermined mask to pattern the photosensitive resin. After that, the interlayer insulating film 7 is etched by RIE using the photosensitive resin as a mask to form a connection hole, and the photosensitive resin is removed. After that, the wiring 8 made of aluminum is formed by the sputtering method, and the wiring 8 and the first high-concentration diffusion region 3 are connected to each other, and the wiring 8 and the second high-concentration diffusion region 4 are connected to each other.

[0007]

As shown in FIG. 10, the conventional diode produced by the above process has a PN junction with an N type first low concentration diffusion region 1 and a P type first high concentration diffusion region 1. Although formed at the boundary of the concentration diffusion region 3, the first low concentration diffusion region 1 and the first high concentration diffusion region 3 are also formed in the crystal defect 6 portion below the edge of the field oxide film 5 formed by the selective oxidation process.
To form a PN junction. Therefore, when a reverse bias is applied to the P-type first high-concentration diffusion region 3 and the N-type second high-concentration diffusion region 4, that is, more than the voltage applied to the first high-concentration diffusion region 3. , A reverse bias current when a negative voltage is applied to the second high-concentration diffusion region 4 flows from the PN junction formed in the crystal defect 6 portion, and therefore, as shown in the graph of FIG. A current flows even at a voltage of 10 or less. Further, the breakdown voltage 10 is also unstable because the breakdown occurs at the PN junction portion of the crystal defect 6 portion, and it is difficult to set the breakdown voltage 10.

An object of the present invention is to solve the above problems and to provide a diode in which no current flows at a voltage lower than the breakdown voltage and in which the breakdown voltage can be easily set, and a manufacturing method thereof. .

[0009]

In order to achieve the above object, the diode and the manufacturing method thereof according to the present invention employ the diode and the manufacturing method described below.

The diode of the present invention has a high-concentration diffusion region between element isolation regions on a semiconductor substrate, and crystal defects formed at the ends of the high-concentration diffusion region have low-concentration diffusion of the same conductivity type as the high-concentration diffusion region. It is characterized in that it is provided with a structure for covering with a region.

According to the method of manufacturing a diode of the present invention, a step of forming a first low-concentration diffusion region on a semiconductor substrate, and a conductivity type opposite to that of the first low-concentration diffusion region, the first low-concentration diffusion region. Forming a second low-concentration diffusion region on the region;
Selectively forming an element isolation region on the first low-concentration diffusion region and the second low-concentration diffusion region so as to form an edge of the element isolation region on the low-concentration diffusion region. Forming a first high-concentration diffusion region in an element region having a conductivity type opposite to that of the low-concentration diffusion region in which the second low-concentration diffusion region is formed at the end of the element isolation region; A step of forming a second high-concentration diffusion region in an element region that has the same conductivity type as that of the region and in which the first high-concentration diffusion region is not formed, and then a step of forming an interlayer insulating film on the entire surface, A feature is that a connection hole is formed in the film to form a wiring.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5 are cross-sectional views showing a method of manufacturing a diode in the order of steps, and FIG. 6 is a graph showing voltage-current characteristics of the diode of the present invention.

First, the diode of the present invention will be described. As shown in FIG. 5, the PN junction includes an N-type first low-concentration diffusion region 1 and a P-type second low-concentration diffusion region 2 and an N-type first low-concentration diffusion region 1 and P-type. And the first high-concentration diffusion region 3 of. In addition, the crystal defects 6 formed below the edge of the field oxide film 5 are removed from the second low concentration diffusion region 2
Adopt a structure covered with. N-type first low concentration diffusion region 1
The breakdown voltage of the PN junction between the P type second low-concentration diffusion region 2 and the P-type second low-concentration diffusion region 2 is the first because the impurity concentration of the second low-concentration diffusion region 2 is lower than that of the first high-concentration diffusion region 3. It is considerably higher than the breakdown voltage of the PN junction formed between the low concentration diffusion region 1 and the first high concentration diffusion region 3. In addition, the crystal defect 6 portion is replaced with the second low-concentration diffusion region 2
By adopting a structure for covering the crystal defect 6
N-junction is not formed. Therefore, no breakdown occurs at the crystal defect 6 portion, and no current flows at a voltage lower than the breakdown voltage. Further, since the breakdown due to the crystal defect 6 portion where it is difficult to set the breakdown voltage does not occur, the breakdown voltage can be easily set.

Next, a method of manufacturing the diode of the present invention will be described in the order of steps. First, as shown in FIG.
A photosensitive resin (not shown) having a film thickness of 1.1 μm is formed on the entire surface by a spin coating method on an N-type semiconductor substrate 9 having an Ωcm, exposed by using a predetermined mask, developed, and exposed to light. Patterning a photosensitive resin, using this photosensitive resin as a mask, and using an ion implantation method, phosphorus is accelerated at an acceleration energy of 100 keV and an implantation amount of 9.1 × 10 ¹³ atoms / c.
m ² is injected to form the N-type first low-concentration diffusion region 1, and the photosensitive resin is removed.

Next, as shown in FIG. 2, the temperature is 1140 ° C.
Is heat-treated for 14 hours to activate phosphorus in the first low concentration diffusion region 1. After that, a photosensitive resin 11 having a film thickness of 1.1 μm is formed on the entire surface by a spin coating method, is exposed using a predetermined mask, is subjected to development processing, and is then formed.
Of the high-concentration diffusion region 1 is opened, and using this photosensitive resin 11 as a mask, an ion implantation method is used to accelerate boron with an acceleration energy of 25 keV and an implantation amount of 2.0 × 10 ¹⁴ atoms. / Cm ² is implanted to form the P-type second low-concentration diffusion region 2.

Next, as shown in FIG. 3, the photosensitive resin 11
And a silicon nitride (not shown) having a film thickness of 150 nm is formed on the entire surface by CVD, and the film thickness is 1.1 μm.
Photosensitive resin (not shown) is formed on the entire surface by a spin coating method, exposed using a predetermined mask, and subjected to development processing.
The second low-concentration diffusion region is provided so that the edge of the photosensitive resin is provided on the silicon nitride on the first low-concentration diffusion region 1 and on the silicon nitride on the second low-concentration diffusion region 2. Two
And on the silicon nitride on the first low-concentration diffusion region 1,
The photosensitive resin is patterned, the silicon nitride is patterned by RIE using the photosensitive resin as a mask, and then the photosensitive resin is removed. After that, heat treatment at 1000 ° C. is performed for 160 minutes in an oxygen atmosphere to which water vapor is added,
A field oxide film 5 of silicon oxide having a film thickness of 710 nm is formed by so-called selective oxidation for forming silicon oxide in the element isolation region. At this time, the field oxide film 5
Stress is generated under the edge of the field oxide film at the edge of the element region of the first high-concentration diffusion region 5 formed in the subsequent step, and the crystal defect 6 is The structure is covered with the low-concentration diffusion region 2. Then, the silicon nitride is removed with phosphoric acid heated to 180 ° C.

Next, as shown in FIG. 4, the film thickness is 1.1 μm.
Photosensitive resin (not shown) is formed on the entire surface by a spin coating method, exposed using a predetermined mask, and subjected to development processing.
A photosensitive resin on the element region where the second low-concentration diffusion region 2 is formed is opened below the edge of the field oxide film 5, and using this photosensitive resin as a mask, the boron is accelerated with an acceleration energy of 25 keV by an ion implantation method. , Injection amount 2.5 × 10
Implanting ¹⁵ atoms / cm ² forms a P-type first high-concentration diffusion region 3 and forms a PN junction with the N-type first low-concentration diffusion region 1 and the N-type semiconductor substrate 9. Then, the photosensitive resin is removed.

After that, a photosensitive resin (not shown) having a film thickness of 1.1 μm is formed on the entire surface by a spin coating method, is exposed using a predetermined mask, and is subjected to a developing treatment, so that the P-type first high resin is formed. The photosensitive resin on the element region where the concentration diffusion region 3 is not formed is opened, and using this photosensitive resin as a mask, arsenic is accelerated with an acceleration energy of 60 keV and an implantation amount of 3.5 × 10 ¹⁵ atoms. / Cm ² is injected to form an N-type second high-concentration diffusion region 4 as an electrode of the N-type first low-concentration diffusion region 1, and then the photosensitive resin is removed.

Next, as shown in FIG. 5, a 550 nm-thickness interlayer insulating film 7 of silicon oxide containing phosphorus and boron is formed by CVD, and the temperature is set to 1000 ° C. in a nitrogen atmosphere.
Is heat-treated for 25 minutes to fluidize the interlayer insulating film 7, so-called reflow is performed, and the surface of the interlayer insulating film 7 is flattened. After that, a photosensitive resin (not shown) having a film thickness of 1.1 μm, which is a photosensitive material, is formed on the entire surface, and exposed and developed using a predetermined mask to pattern the photosensitive resin. After that, the interlayer insulating film 7 is etched by RIE using the photosensitive resin as a mask to remove the photosensitive resin. After that, the wiring 8 made of aluminum is formed by the sputtering method, and the wiring 8 and the first high-concentration diffusion region 3 are connected to each other, and the wiring 8 and the second high-concentration diffusion region 4 are connected to each other.

The diode produced by this process forms crystal defects 6 in the second low-concentration diffusion region 2 and a PN junction is not formed in the crystal defect 6 portions. Down does not occur. Therefore, in FIG.
As shown in the graph, the current does not flow at a voltage equal to or lower than the breakdown voltage 10 and the breakdown due to the crystal defect 6 portion does not occur, so that the breakdown voltage 10 can be easily set.

[0021]

According to the diode and the method of manufacturing the same according to the present invention, a crystal defect is formed in the second low concentration diffusion region under the edge of the field oxide film, and a PN junction is not formed in the crystal defect portion. Breakdown does not occur at the defective part. Therefore, no current flows at a voltage lower than the breakdown voltage. Further, since the breakdown of the crystal defect portion where it is difficult to set the breakdown voltage does not occur, the breakdown voltage can be set easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a method for manufacturing a diode showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a method for manufacturing a diode showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a method for manufacturing a diode showing an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a method for manufacturing a diode showing an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a method for manufacturing a diode showing an embodiment of the present invention.

FIG. 6 is a graph of voltage-current characteristics of a diode showing an example of the present invention.

FIG. 7 is a cross-sectional view of a method for manufacturing a diode showing a conventional example.

FIG. 8 is a cross-sectional view of a method for manufacturing a diode showing a conventional example.

FIG. 9 is a cross-sectional view of a method for manufacturing a diode showing a conventional example.

FIG. 10 is a cross-sectional view of a method for manufacturing a diode showing a conventional example.

FIG. 11 is a graph of voltage-current characteristics of a diode showing a conventional example.

[Explanation of symbols]

 1 first low concentration diffusion region 2 second low concentration diffusion region 3 first high concentration diffusion region 4 second high concentration diffusion region 5 field oxide film 6 crystal defect 7 interlayer insulating film

Claims (2)

[Claims] 1. A structure in which a high-concentration diffusion region is provided between element isolation regions on a semiconductor substrate, and a crystal defect formed at an end of the high-concentration diffusion region is covered with a low-concentration diffusion region of the same conductivity type as the high-concentration diffusion region. A diode characterized by comprising. 2. A step of forming a first low concentration diffusion region on a semiconductor substrate, and a second low concentration diffusion region having a conductivity type opposite to that of the first low concentration diffusion region. A step of forming a concentration diffusion region, and selectively forming an end of an element isolation region on the second low concentration diffusion region on the first low concentration diffusion region and the second low concentration diffusion region. The step of forming the element isolation region and the conductivity type opposite to that of the first low-concentration diffusion region, and the first high-concentration diffusion region is formed in the element region where the second low-concentration diffusion region is formed at the end of the element isolation region. A step of forming, a step of forming a second high-concentration diffusion region in an element region having the same conductivity type as that of the first low-concentration diffusion region, and in which the first high-concentration diffusion region is not formed, and then over the entire surface. Die characterized by forming an interlayer insulating film, forming a connection hole in the interlayer insulating film, and forming a wiring Aether manufacturing method.