JPH06196683A - Schottky barrier diode and semiconductor integrated circuit device - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the allowable current of the Schottky barrier diode without increasing the occupied area of the Schottky barrier diode. [Structure] The compound semiconductor substrate 1 is provided with a first groove 3a,
The second recessed groove 3b is provided at a predetermined interval so as to be adjacent to each other, the Schottky electrode 4 is provided in the first recessed groove 3a, and the ohmic electrode 5 is provided in the second recessed groove 3b. Configured 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Schottky barrier diode and semiconductor integrated circuit device technology, and is particularly effective when applied to a Schottky barrier diode (SBD) using a compound semiconductor substrate as a substrate. It is about technology.

[0002]

2. Description of the Related Art An SBD is a diode that utilizes the property of a potential barrier called a Schottky barrier formed on a contact surface of a semiconductor when the metal and the semiconductor are brought into contact with each other.

Conventional SBD using a compound semiconductor substrate
Formed a Schottky electrode and an ohmic electrode forming an SBD on a substantially flat surface of a compound semiconductor substrate.

Regarding the Schottky junction, for example, "Ohm Co., Ltd.," issued November 30, 1984, "L
SI Handbook "P50 to P52, and describes the energy band structure, current-voltage characteristics, etc. in a Schottky junction formed on a normal semiconductor substrate made of silicon (Si) or the like.

[0005]

However, the present inventor has found that the above-mentioned conventional SBD structure has the following problems.

That is, in the conventional SBD structure,
Since the electric field is concentrated on the ends of the Schottky electrode and ohmic electrode, there is a risk of destruction or the like at this part,
There is a problem that a very large current cannot be passed and the improvement of the operation speed of the semiconductor integrated circuit device having the SBD is hindered.

The reason why the electric field is concentrated at the end of the Schottky electrode is that the Schottky electrode 4 is conventionally formed as shown in FIG.
0 and the ohmic electrode 41 form a compound semiconductor substrate 42.
This is because the current I that contributes to the operation of the SBD concentrates on the ends of the Schottky electrode 40 and the ohmic electrode 41 because they are formed on the same flat surface.

On the other hand, the area of the Schottky electrode and the ohmic electrode can be increased in order to increase the amount of current that can flow in the SBD. However, doing so increases the area of the semiconductor chip and improves the degree of integration of elements. There was a problem that was blocked.

The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of increasing the allowable current of the SBD without increasing the area occupied by the SBD.

The above and other objects and novel features of the present invention will be apparent from the description of the specification and the accompanying drawings.

[0011]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, according to the first aspect of the present invention, the first concave groove and the second concave groove are provided in the compound semiconductor substrate so as to be adjacent to each other at a predetermined interval, and the first concave groove is formed. A Schottky barrier diode structure is provided in which a Schottky electrode is provided on the inner surface and an ohmic electrode is provided on the inner surface of the second groove.

According to a second aspect of the present invention, there is provided a Schottky barrier diode structure in which a projection made of a compound semiconductor is provided on at least a part of the inner surfaces of the first groove and the second groove.

[0014]

According to the invention described in claim 1, the SBD
Forming a channel between the side surfaces of the first groove and the second groove having the Schottky electrode and the ohmic electrode, which face each other, facing each other, and the current contributing to the operation of the SBD is mainly the facing side surface. Since it flows from the side surface to the side surface, it is possible to suppress the electric field from concentrating on the end portion of the Schottky electrode. As a result, S
It is possible to increase the allowable current per electrode area of the SBD as compared with the conventional case without increasing the area occupied by the BD.

According to the second aspect of the present invention, the area of the Schottky junction surface can be increased.
It is possible to further increase the permissible current per electrode area of the SBD.

[0016]

1 is a cross-sectional view of a portion where an SBD is formed in a semiconductor integrated circuit device according to an embodiment of the present invention, FIG.
1 is an explanatory diagram for explaining the operation of the SBD of FIG. 1, FIG. 3 is an enlarged cross-sectional view of a main part of the SBD of FIG. 1, and FIGS. 4 to 13 are SBDs.
FIG. 6 is a cross-sectional view of a principal portion of the compound semiconductor substrate during the manufacturing process of

In the semiconductor integrated circuit device of this embodiment, as shown in FIG. 1, a plurality of SBDs 2 to be described later are formed on the compound semiconductor substrate 1. Although not shown, other semiconductor integrated circuit elements such as MES • FETs are formed on the compound semiconductor substrate 1.

The compound semiconductor substrate 1 is composed of a substrate layer 1a, a first growth layer 1b deposited on the substrate layer 1a, and a second growth layer 1c deposited on the first growth layer 1b. .

The substrate layer 1a is made of, for example, gallium arsenide (G
It is made of a compound semiconductor such as aAs) or indium phosphide (InP).

The first growth layer 1b is made of a material having a smaller etching rate than the second growth layer 1c, and is made of, for example, aluminum gallium arsenide (AlGaAs) or indium gallium arsenide (InGaAs). This is to cause the first growth layer 1b to function as an etching stopper layer when forming a groove 3 to be described later in the second growth layer 1c.

The second growth layer 1c is a compound semiconductor layer serving as a main active layer of the SBD 2, and is formed by introducing an n-type impurity such as Si into a compound semiconductor such as GaAs. In the second growth layer 1c, the first groove 3a
And the second concave groove 3b are formed at a predetermined interval so as to be adjacent to each other. The angle θ between the side surface and the bottom surface of the groove 3 is, for example, 90 degrees to 170 degrees.

A Schottky electrode 4 is formed in the first groove 3a. The Schottky electrode 4 is made of a refractory metal silicide such as WSi ₂ , MoSi ₂ or TaSi ₂ . Further, the ohmic electrode 5 is formed in the second groove 3b. The ohmic electrode 5 is made of, for example, gold-germanium (AuGe) alloy, nickel (Ni), Au, or the like.

That is, in this embodiment, the SBD2
Is a Schottky electrode 4 formed in the first groove 3a,
It is composed of an ohmic electrode 5 formed in the second groove 3b adjacent thereto and a second growth layer 1c sandwiched between these electrodes 4 and 5.

In the SBD 2 of the present embodiment, it is sandwiched between the side surface of the first groove 3a having the Schottky electrode 4 formed therein and the side surface of the second groove 3b having the ohmic electrode 5 formed therein. A channel is formed in the second growth layer 1c.

Then, as shown in FIG. 2, the current I that contributes to the operation of the SBD 2 is changed to the first groove 3a and the second groove 3a.
It flows from the side surfaces facing each other with b to the side surfaces.

Therefore, it is possible to suppress the electric field from concentrating on the end portion of the Schottky electrode 4, and it is possible to increase the permissible current per electrode area of the SBD 2 as compared with the conventional case. Note that, in FIG. 2, hatching of the second growth layer 1c is omitted in order to make the current I easy to see.

Further, in this embodiment, as shown in FIG. 3, projections 6 made of a compound semiconductor are formed on the bottom surface and the side surfaces of the concave groove 3. As a result, the area of the Schottky junction surface can be increased, so that the allowable current per electrode area of the SBD 2 can be further increased.

Next, an example of the method of forming the SBD of this embodiment will be described with reference to FIGS. 4 to 7 and 8 to 13.

First, as shown in FIG. 4, an insulating film pattern 7 is formed on the main surface of the compound semiconductor substrate 1 so that the formation region of the groove 3 (see FIG. 1) is exposed. The first growth layer 1b and the second growth layer 1c are formed by, for example, an epitaxial growth method.

Then, as shown in FIG. 5, the first growth layer 1c is formed on the second growth layer 1c using the insulating film pattern 7 as an etching mask.
The recessed groove 3 reaching the upper surface of the growth layer 1b is formed by a wet etching method or the like. At this time, the first growth layer 1b
To function as an etching stopper.

After that, as shown in FIG. 6, MOCVD is performed.
A protrusion 6 made of a compound semiconductor is formed on the inner surface of the groove 3 by a (Metal Organic CVD) method or the like.

Next, after removing the insulating film pattern 7,
As shown in FIG. 7, a conductor film 8a for forming an electrode is deposited on the compound semiconductor substrate 1 by a vapor deposition method, a sputtering method, or the like.

After that, a photoresist pattern 9a is formed on a region of the conductor film 8a where an electrode (not shown in FIG. 7) is formed, and then the conductor film 8a is patterned using the photoresist pattern 9a as an etching mask. Electrodes to form the SBD 2 shown in FIG.

Further, for example, the SBD 2 may be formed as follows.

First, as shown in FIG. 8, after the first growth layer 1b is formed on the substrate layer 1a by an epitaxial method or the like, insulation is formed so that only the electrode formation region is exposed on the first growth layer 1b. The film pattern 7 is formed.

Subsequently, as shown in FIG. 9, using the insulating film pattern 7 as a mask, a protrusion 6 made of a compound semiconductor is formed on the exposed surface of the first growth layer 1b by MOCVD or the like.

After removing the insulating film pattern 7,
As shown in FIG. 10, after depositing the conductor film 8b on the first growth layer 1b by vapor deposition or sputtering,
A photoresist pattern 9b is formed on the conductor film 8b in the electrode formation region.

Then, the photoresist pattern 9b
Using as a etching mask, the conductor film pattern 8b ₁ is patterned on the first growth layer 1b as shown in FIG.

Subsequently, using the conductor film pattern 8b ₁ as a mask, as shown in FIG. 12, the conductor film pattern 8b _{1 is formed.}
After the second growth layer 1c is formed around the substrate by the epitaxial method or the like, as shown in FIG.
A conductor film 8c is deposited on the top by vapor deposition or sputtering.

Then, after forming a photoresist pattern (not shown) in the electrode forming region on the conductor film 8c,
Using the photoresist pattern as an etching mask, the conductor film 8c is patterned to form electrodes, and the SBD 2 shown in FIG. 1 is formed.

As described above, according to this embodiment, the following effects can be obtained.

(1). First concave groove 3a in compound semiconductor substrate 1
And second recessed grooves 3b are provided so as to be adjacent to each other at a predetermined interval, Schottky electrodes 4 are provided in the first recessed grooves 3a, and ohmic electrodes 5 are provided in the second recessed grooves 3b.
By configuring D2, the current I that contributes to the operation of the SBD 2 flows from the side surfaces of the first groove 3a and the second groove 3b facing each other to the side surface.
It becomes possible to suppress the concentration of the electric field at the end of the Schottky electrode 4. As a result, the permissible current per electrode area of the SBD 2 can be increased more than before without increasing the occupied area of the SBD 2.

(2). Since the projections 6 made of a compound semiconductor are formed on the bottom surface and the side surfaces of the recessed groove 3, the area of the Schottky junction surface can be increased.
It is possible to further increase the permissible current per electrode area of.

(3) Due to the above (1) and (2), it is possible to improve the operating speed of the semiconductor integrated circuit device having the SBD 2.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the above embodiment, the case where the substrate layer is a compound semiconductor has been described, but the present invention is not limited to this. For example, the substrate layer may be made of a semiconductor such as Si.

Further, in the above-mentioned embodiment, the case where the first growth layer functioning as an etching stopper is interposed between the substrate layer and the second growth layer has been described, but the present invention is not limited to this. It is not necessary to interpose the first growth layer.

[0048]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

(1). According to the invention of claim 1, the SBD
A channel is formed between the mutually facing side surfaces of the first groove and the second groove formed with the Schottky electrode and the ohmic electrode, respectively, and currents contributing to the operation of the SBD mainly oppose each other. Since it flows from the side surface to the side surface, it is possible to suppress the electric field from being concentrated on the end portion of the Schottky electrode. As a result, SBD
It is possible to increase the permissible current per electrode area of the SBD as compared with the prior art without increasing the occupied area of the SBD. Therefore, it is possible to improve the operation speed of the semiconductor integrated circuit device using this SBD.

(2) According to the second aspect of the invention, since the area of the Schottky junction surface can be increased, SB
It is possible to further increase the allowable current per electrode area of D. Therefore, it is possible to improve the operation speed of the semiconductor integrated circuit device using this SBD.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a portion where an SBD is formed in a semiconductor integrated circuit device that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the Schottky barrier diode of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of the Schottky barrier diode shown in FIG.

FIG. 4 is a fragmentary cross-sectional view of a compound semiconductor substrate during a manufacturing process of a Schottky barrier diode.

FIG. 5 is a cross-sectional view of an essential part of the compound semiconductor substrate during the manufacturing process of the Schottky barrier diode following FIG.

FIG. 6 is a cross-sectional view of an essential part of the compound semiconductor substrate during the manufacturing process of the Schottky barrier diode subsequent to FIG.

FIG. 7 is a cross-sectional view of an essential part of the compound semiconductor substrate during the manufacturing process of the Schottky barrier diode subsequent to FIG.

FIG. 8 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing process of a Schottky barrier diode by another manufacturing method.

9 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing step of a Schottky barrier diode by another manufacturing method following FIG. 8. FIG.

10 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing step of a Schottky barrier diode by another manufacturing method following FIG. 9. FIG.

11 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing step of a Schottky barrier diode by another manufacturing method following FIG. 10. FIG.

12 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing step of a Schottky barrier diode by another manufacturing method subsequent to FIG. 11. FIG.

13 is a fragmentary cross-sectional view of the compound semiconductor substrate during a manufacturing step of a Schottky barrier diode by another manufacturing method following FIG. 12. FIG.

FIG. 14 is an explanatory diagram of a conventional Schottky barrier diode.

[Explanation of symbols]

1 Compound Semiconductor Substrate 1a Substrate Layer 1b First Growth Layer 1c Second Growth Layer 2 Schottky Barrier Diode (SBD) 3 Recessed Groove 3a First Recessed Groove 3b Second Recessed Groove 4 Schottky Electrode 5 Ohmic Electrode 6 Protrusion 7 Insulation Film Pattern 8a Conductor film 8b Conductor film 8b ₁ Conductor film pattern 8c Conductor film 9a Photoresist pattern 9b Photoresist pattern

Claims (4)

[Claims] 1. A compound semiconductor substrate is provided with a first groove and a second groove so as to be adjacent to each other at a predetermined distance, and a Schottky electrode is provided on an inner surface of the first groove, A Schottky barrier diode characterized in that an ohmic electrode is provided on the inner surface of the second groove. 2. The Schottky barrier diode according to claim 1, wherein a projection made of a compound semiconductor is provided on at least a part of the inner surfaces of the first groove and the second groove. 3. A semiconductor integrated circuit device comprising a Schottky barrier diode in which a Schottky electrode is provided on an inner surface of a groove provided in a compound semiconductor substrate. 4. The semiconductor integrated circuit device according to claim 3, wherein a projection made of a compound semiconductor is provided on at least a part of the inner surface of the groove.