Schottky barrier diode

Abstract

A Schottky barrier diode is disclosed that can be applied to applications such as mobile integrated circuits that require a low cut-off current (Ioff). The Schottky barrier diode can improve the blocking characteristics for reverse current while maintaining the advantage of on-current by improving the structure of the contact surface pinched off by depletion.

Description

Technical Field

[0001] The present disclosure relates to a Schottky barrier diode, and more particularly, to a Schottky barrier diode that can be applied to applications such as mobile integrated circuits that require a low cut-off current (Ioff). Background Art

[0002] A Schottky barrier diode is a device that uses a barrier generated by the contact between a barrier metal and a semiconductor as a rectifying action. The Schottky barrier diode is used for high-speed switching, high-frequency conversion, high-frequency detection, etc.

[0003] When a forward current flows into the Schottky barrier diode, the Schottky barrier diode is turned on by means of a plurality of carriers in the epitaxial semiconductor layer moving to the barrier metal. In this case, the voltage-current characteristic depends on the Schottky characteristic.

[0004] In addition, if a reverse current is to flow into the Schottky barrier diode, the Schottky barrier diode is turned off by the barrier between the barrier metal and the semiconductor. The Schottky barrier diode is turned off by the junction barrier formed when the P-well region is depleted to the N-well region.

[0005] In order to apply the Schottky barrier diode to applications that require fast turn-off and low cut-off current (Ioff), the Schottky barrier diode needs a structure capable of improving the cut-off current (Ioff) while maintaining the advantage of the on-current (Ion) unchanged. Summary of the Invention

[0006] Various embodiments are directed to providing a Schottky barrier diode having improved cut-off current characteristics while maintaining the advantage of the on-current (Ion).

[0007] In addition, various embodiments are directed to providing a Schottky barrier diode having improved cut-off current characteristics by forming a semiconductor region in which a junction barrier formed by depletion has the same length in a first direction and a second direction perpendicular to each other.

[0008] In an embodiment, a Schottky barrier diode includes a barrier metal layer and a semiconductor substrate configured to form a Schottky contact with the barrier metal layer. The semiconductor substrate includes: a first semiconductor region configured to form a first contact surface in contact with the barrier metal layer; and a second semiconductor region distributed at a plurality of positions within the first contact surface and configured to form respective second contact surfaces in contact with the barrier metal layer. The first semiconductor region has an insulating property for reverse current flow from the semiconductor substrate to the barrier metal layer. Each second contact surface is formed to have a width with the same length in a first direction and a second direction perpendicular to each other. By the reverse current flow, the first semiconductor region is depleted into the second semiconductor region to block the reverse current flow through the second semiconductor region. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a plan view of a Schottky barrier diode according to an embodiment.

[0010] Figure 2 is along Figure 1 a partial cross-sectional view taken along line 2-2 in

[0011] Figure 3 is along Figure 1 a partial cross-sectional view taken along line 2-2 in

[0012] Figure 4 is a plan view of a Schottky barrier diode according to another embodiment. DETAILED DESCRIPTION

[0013] Exemplary embodiments will be described in detail below with reference to the accompanying drawings. However, the present disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Throughout the present disclosure, the same reference numerals refer to the same parts in various drawings and embodiments.

[0014] The following will refer to Figures 1 to 3 describe a Schottky barrier diode according to an embodiment.

[0015] Figure 1 is a planar layout of a Schottky barrier diode according to an embodiment and shows a state in which the barrier metal layer BM and the anode electrode AN have not been formed. Further, Figure 2 and Figure 3 is along Figure 1Partial cross-sectional view taken along line 2-2 in. The Schottky barrier diode includes a semiconductor substrate SM, a barrier metal layer BM, an anode AN on one side of the semiconductor substrate SM, and a cathode CA on the other side of the semiconductor substrate SM.

[0016] The anode AN, the cathode CA, and the barrier metal layer BM include a conductive material and can be formed to have a thickness designed by the manufacturer. Among these elements, the barrier metal layer BM can be formed to include a metal material such as titanium (Ti) or a Ti alloy, a silicide, or cobalt silicide.

[0017] The barrier metal layer BM defines a contact area in contact therewith in the semiconductor substrate SM through the protection ring 10. The contact area can be understood as the internal area of the protection ring 10.

[0018] For example, Figure 1 shows that the protection ring 10 is formed in a quadrilateral shape. An isolation region 20 is formed along the protection ring 10 within the protection ring 10. The protection ring 10 and the isolation region 20 can be understood as grooves formed on one side of the semiconductor substrate SM and filled with an insulating material. Among the elements, the protection ring 10 can be understood as being formed for electrical separation between the internal area and the external area of the protection ring 10. The isolation region 20 can be understood as being formed assistingly for isolation.

[0019] As Figure 2 and Figure 3 shown, the barrier metal layer BM is formed above the contact area defined by the protection ring 10. The anode AN is formed above the barrier metal layer BM.

[0020] In addition, referring to Figure 1 , a first contact surface 30 and a second contact surface 40 are formed in the contact area of the protection ring 10.

[0021] The first contact surface 30 is formed in a rectangle within the protection ring 10. The second contact surfaces 40 are distributed at multiple positions within the first contact surface 30. The width of each second contact surface 40 has the same length in a first direction (e.g., Figure 1 X in Figure 1 ), and a second direction (e.g.,

[0022] Y in Figure 2 and Figure 3 ). For example, each second contact surface is shown as a circle.

[0023] The first semiconductor region may be formed of a P-type semiconductor. For example, the first semiconductor region may be formed by a P-well 130. The second semiconductor region may be formed of an N-type semiconductor. For example, the second semiconductor region may be formed by an N-well 140. Hereinafter, the first semiconductor region is referred to as the P-well 130, and the second semiconductor region is referred to as the N-well 140.

[0024] The P-well 130 is formed to have a first depth. The N-well 140 is formed to have a depth equal to or greater than the first depth. Figure 2 and Figure 3 It is shown that the N-well 140 is formed as a lower well, and the P-well 130 is formed as an upper well.

[0025] Referring to Figure 2 and Figure 3 describe the structure of the semiconductor substrate SM.

[0026] The semiconductor substrate SM includes a sub-layer 100 and an epitaxial layer 110. For example, the sub-layer 100 may be formed of an N+-type semiconductor. For example, the epitaxial layer 110 may be formed of an N-type semiconductor. The epitaxial layer 110 is formed on the sub-layer 100. The cathode electrode CA is formed under the sub-layer 100, that is, on the other side of the semiconductor substrate SM.

[0027] The N-well 140 is formed as a lower well in the epitaxial layer 110. The P-well 130 is formed as an upper well on the N-well 140. In this case, the N-well 140 may be formed as a high-voltage N-well. The amount of impurities may be determined by considering the epitaxial layer 110 and the sub-layer 100.

[0028] The second contact surfaces 40 formed by the N-well 140 are spaced apart from each other and are formed to include a plurality of columns within the first contact surface 30. In addition, the adjacent columns of the second contact surfaces 40 are arranged in a staggered manner. Accordingly, the second contact surfaces 40 may be uniformly distributed in the first contact surface 30.

[0029] Since the Schottky barrier diode according to the embodiment is implemented as described above, as Figure 2 shown, the forward current flow can be ensured, and as Figure 3 shown, the reverse current flow can be effectively blocked.

[0030] More specifically, for the forward current flow from the barrier metal layer BM to the semiconductor substrate SM, the P-well 130 forming the first contact surface 30 and the N-well 140 forming the second contact surface 40 have Schottky characteristics according to the Schottky contact. As a result, as Figure 2 shown, the forward current flow, that is, the flow of the on-current (Ion), is ensured.

[0031] The P-well 130 has insulating properties with respect to reverse current flow from the semiconductor substrate SM to the barrier metal layer BM.

[0032] In addition, the P-well 130 forms a depletion region DP that extends into the region of the N-well 140 (i.e., the second contact surface 40) through reverse current flow. The depletion region DP of the P-well 130 gradually grows through reverse current. As a result, the second contact surface 40 formed by the N-well 140 is pinched off by the depletion region DP. The depletion region DP forms a junction barrier. As a result, the reverse current flowing through the second contact surface 40 is blocked. That is, the cut-off current (Ioff), which is the reverse current, is blocked.

[0033] Each second contact surface 40 according to the embodiment is formed in a circular shape. Therefore, through the growth of the P-well 130, the depletion region DP can grow uniformly on all sides of the second contact surface 40. Through the growth of the depletion region DP, the second contact surface 40 can be effectively pinched off.

[0034] Therefore, since the circle formed by each second contact surface 40 in which the depletion region is formed has a width of the same length in the first direction and the second direction perpendicular to each other, Figures 1 to 3 the embodiment can improve the characteristics of forming a pinch-off. As a result, the Schottky barrier diode can improve the blocking characteristics for reverse current flow while maintaining the advantage of the on-current, and can have improved cut-off current characteristics.

[0035] According to the embodiment as in Figure 4 , each second contact surface 45 can be formed in a square shape. Except for the shape of the second contact surface 45, Figure 4 the embodiment is configured in the same manner as the embodiment of Figure 3 and thus redundant descriptions are omitted.

[0036] Each second contact surface 45 is formed in a square shape, which is one of the figures. Each second contact surface 45 has a width of the same length in the first direction and the second direction perpendicular to each other.

[0037] Therefore, through reverse current flow, the depletion region DP of the P-well 130 grows at a uniform speed on the four surfaces. As a result, the second contact surface 45 formed by the N-well 140 can be effectively pinched off by the depletion region DP. The reverse current flowing through the second contact surface 45 can be effectively blocked.

[0038] That is, since the square formed by each second contact surface 45 in which the depletion region is formed has a width of the same length in the first direction and the second direction perpendicular to each other (i.e., an example in the figure), Figure 4Embodiments can improve the characteristics of pinch-off formation. As a result, the Schottky barrier diode can improve the blocking characteristics for reverse current flow while maintaining the advantage of on-current, and can have improved cut-off current characteristics.

[0039] In addition to Figure 1 the circular shape shown and Figure 4 the square shape shown in, among regular polygons, each second contact surface 45 can be configured to have a regular octagon with a width having the same length in a first direction and a second direction perpendicular to each other.

[0040] That is, the Schottky barrier diode according to the embodiment can be applied to applications such as mobile integrated circuits that require fast turn-off and low cut-off current (Ioff).

[0041] The present disclosure can improve the blocking characteristics for reverse current flow while maintaining the advantage of on-current by improving the semiconductor region in which the depletion region is formed.

[0042] In addition, the advantage of the present disclosure is that, since each semiconductor region forming the junction barrier by depletion has a width having the same length in a first direction and a second direction perpendicular to each other, it has improved cut-off current characteristics.

[0043] Although various embodiments have been described above, those skilled in the art will understand that the described embodiments are merely exemplary. Therefore, the disclosure described herein should not be limited based on the described embodiments.

Claims

1. Schottky barrier diode, comprising: a barrier metal layer; and a semiconductor substrate configured to form a Schottky contact with the barrier metal layer, an isolation region is formed along a guard ring within the guard ring, and the guard ring and the isolation region are located inside the semiconductor substrate and filled with an insulating material, an anode electrode is formed on the barrier metal layer, wherein, the semiconductor substrate includes: a first semiconductor region configured to form a first contact surface in contact with the barrier metal layer; and a second semiconductor region respectively distributed at multiple positions within the first contact surface and configured to form respective second contact surfaces in contact with the barrier metal layer, for reverse current flow from the semiconductor substrate to the barrier metal layer, the first semiconductor region has insulating properties; each of the second contact surfaces is formed to have a width with the same length in a first direction and a second direction perpendicular to each other; and through the reverse current flow, the first semiconductor region is depleted into the second semiconductor region to block the reverse current flow through the second semiconductor region, wherein, the anode electrode contacts the guard ring, and the barrier metal layer contacts the isolation region, wherein, the guard ring surrounds the isolation region, and the isolation region surrounds the second semiconductor region.

2. The Schottky barrier diode according to claim 1, wherein: the first semiconductor region and the second semiconductor region have Schottky characteristics for forward current flow from the barrier metal layer to the semiconductor substrate.

3. The Schottky barrier diode according to claim 1, wherein: the first semiconductor region is formed using a P-type semiconductor, and the second semiconductor region is formed using an N-type semiconductor.

4. The Schottky barrier diode according to claim 1, wherein: the first semiconductor region is formed by a P-well having a first depth, and the second semiconductor region is formed by an N-well having a depth equal to or greater than the first depth.

5. The Schottky barrier diode according to claim 4, wherein, the N-well is formed as a high-voltage N-well.

6. The Schottky barrier diode according to claim 1, wherein, each of the second contact surfaces is formed as a circle.

7. The Schottky barrier diode according to claim 1, wherein, each of the second contact surfaces is formed as a square.

8. The Schottky barrier diode according to claim 1, wherein: the second contact surfaces are formed to have multiple columns within the first contact surface, and adjacent columns of the second contact surfaces are arranged in a staggered manner.

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