JPH0697691B2 - Semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device, and more particularly to the structure of an annular region (guard ring) of a Schottky barrier diode.

[Conventional technology]

FIG. 3 is a sectional view showing an example of a guard ring structure of a conventional Schottky barrier diode, in which 1 is a p-type semiconductor substrate and 2 is a p-type semiconductor layer deposited on the p-type semiconductor substrate 1. 3 is a metal deposited on the p-type semiconductor layer 2, 4 is an n-type guard ring formed in the p-type semiconductor substrate 1, 5 is an insulating film, and 6 is an electrode for applying a potential to the metal 3. , 7 are electrodes for applying a potential to the guard ring 4.

Next, the operation will be described.

FIG. 4 is an enlarged view of the vicinity of the guard ring 4 in FIG. 3, in which 9 represents the depletion region and 11 represents the leakage current around the Schottky junction. The figure (a) shows a threshold voltage V with a positive potential + V _G given to the guard ring 4.
_The case is lower than _th , and (b) shows the case higher than V _th .

In FIG. 4A, since a positive potential is applied to the guard ring 4, the pn junction is reverse biased and a depletion region 9 is formed at the junction. However, since the positive potential applied to the guard ring 4 is small (+ V _G <V _th ), the expansion of the depletion region 9 is insufficient, and the leak current 11 generated around the Schottky junction is generated between the guard ring 4 and the metal 3. Flow through to the p-type semiconductor substrate 1.

On the other hand, giving the same figure (b) in sufficient positive potential to the guard ring _{4 (+ V G> V th} ), during the guard ring 4 and the metal 3 is filled with the depletion region 9. Therefore, the leak current 11 is blocked by the high potential of the depletion region 9,
It cannot flow to the p-type semiconductor substrate 1.

Even in the semiconductor device in which the p-type and the n-type are opposite to each other in the above conventional example, the same holds if the positive and negative potentials are switched.

[Problems to be Solved by the Invention]

The conventional Schottky barrier diode is configured as described above, and in the p-type semiconductor layer 2, many crystal defects and localized levels due to misfit of the crystal lattice exist near the boundary with the insulating film 5. Therefore, near this boundary, the guard ring 4 and the p-type semiconductor layer 2 do not form a normal pn junction. Therefore, even if a potential is applied to the guard ring 4 so that the pn junction between the guard ring and the semiconductor layer 2 is reversely biased, between the guard ring 4 and the peripheral portion of the p-type semiconductor layer 2 in the vicinity of the boundary with the insulating film 5. There is a problem that a leak current is generated in the metal and further flows into the metal 3.

The present invention has been made to solve the above problems, and prevents leakage current between a guard ring and a metal caused by a crystal defect or a localized level of a semiconductor layer near an insulating film. An object is to obtain a semiconductor device that can be suppressed.

[Means for Solving the Problems]

In the semiconductor device according to the present invention, an annular region having the same conductivity type as that of the semiconductor layer is formed along the position where the contact ends of the semiconductor layer and the insulating film contact each other on the main surface of the guard ring formed in the substrate. It was done like this.

[Action]

In the present invention, since the annular region of the same conductivity type as the semiconductor layer is formed along the position where the contact ends of the semiconductor layer and the insulating film contact each other on the guard ring main surface formed in the substrate, The pn junction between the layer and the guard ring is perfect and the leakage current between the guard ring and the metal can be controlled.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a Schottky barrier diode according to an embodiment of the present invention, in which the same reference numerals as those in FIGS. 3 and 4 indicate the same or corresponding portions, and 4 is inside a p-type semiconductor substrate 1. The formed n-type guard ring, 8 is a p-type annular region formed on the main surface of the guard ring 4.

Next, the operation will be described.

FIG. 2 is an enlarged view of the vicinity of the guard ring 4 in FIG. 1, in which 9 is a depletion region and 10 is a p-type semiconductor layer 2.
3 shows a crystal defect and a localized level due to a misfit of the crystal lattice between the insulating film 5 and the insulating film 5. Since the p-type annular region 8 formed on the main surface of the guard ring 4 has the same conductivity type as the p-type semiconductor layer 2, it may be considered to be functionally integral with the p-type semiconductor layer 2. That is, when a high positive potential is applied to the guard ring 4, the depletion region 9 at the pn junction expands as shown in the figure. Then, a part of the p-type semiconductor layer 2 is completely depleted,
The leak current around the Schottky junction formed by the metal 3 and the p-type semiconductor layer 2 is blocked by the high potential of the depletion region.

Further, since the p-type annular region 8 on the main surface of the guard ring 4 is formed by a method such as impurity diffusion or ion implantation, the pn junction with the n-type guard ring 4 is a perfect junction having no crystal defects or localized levels. Therefore, no leak current occurs. Therefore, no leak current flows between the guard ring 4 and the metal 3.

As described above, according to this embodiment, the annular region 8 of the same conductivity type as that of the semiconductor layer 2 is formed on the main surface of the guard ring 4 at the position where the contact end between the guard ring 4 and the semiconductor layer 2 is on the main surface.
Since the pn junction between the semiconductor layer 2 and the guard ring 4 is completed, the leak current between the guard ring 4 and the metal 3 can be controlled.

Even if the p-type and the n-type are interchanged in the above embodiment,
It goes without saying that the same effect can be obtained by switching the positive and negative potentials.

〔The invention's effect〕

As described above, according to the semiconductor device of the present invention, the same conductivity type as the semiconductor layer is formed on the main surface of the guard ring formed in the substrate along the position where the contact ends of the semiconductor layer and the insulating film contact each other. Since the annular region is formed, the pn junction between the semiconductor layer and the guard ring is completed, and the leak current between the metal and the guard ring can be controlled.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a sectional view of a conventional semiconductor device, and FIGS. 4 (a) and 4 (b).
FIG. 4 is an enlarged view of a main part of FIG. In the figure, 1 is a p-type semiconductor substrate, 2 is a p-type semiconductor layer, 3
Is a metal, 4 is a guard ring, 5 is an insulating film, 6 and 7 are electrodes, 8 is a p-type annular region, 9 is a depletion region, 10 is a mark indicating a crystal defect or a localized level, and 11 is a leak current. It is an arrow. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A second-conductivity-type annular region provided on the main surface of a first-conductivity-type semiconductor substrate, and its contact end located on the main surface between the inner peripheral edge and the outer peripheral edge of the annular region. Provided on the main surfaces of the insulating film and the semiconductor substrate, the insulating film and the annular region, the contact end of which is in contact with the contact end of the insulating film,
A first-conductivity-type semiconductor layer that constitutes an element, and the first-conductivity-type semiconductor substrate that is provided on the first-conductivity-type semiconductor layer and has a contact end located outside the annular region or outside the annular region. The Schottky junction metal layer having an electrode located on the main surface of the second conductive layer, and the contact surface of the insulating film and the contact edge of the first conductive type semiconductor layer contact each other on the main surface of the second conductivity type annular region. A semiconductor device comprising: a first conductivity type annular region provided along a contact position. 2. The semiconductor device according to claim 1, further comprising an electrode for applying a predetermined voltage to the second conductivity type annular region.