Schottky barrier diode

Abstract

The present invention relates to a Schottky barrier diode that can be applied to applications requiring a small off-current (Ioff), such as mobile integrated circuits, and the Schottky barrier diode can improve the blocking characteristics of reverse current flow while maintaining the advantages of the turn-on current by improving the structure of the contact surface that pinch-off by depletion.

Description

Technology Field

[0001] The present invention relates to a Schottky barrier diode, and more specifically, to a Schottky barrier diode applicable to applications requiring a small off-current (Ioff), such as mobile integrated circuits. Background Technology

[0002] A Schottky barrier diode is a device that utilizes the potential barrier generated by the contact between a barrier metal and a semiconductor for rectification, and is used for high-speed switching, high-frequency conversion, and detection.

[0003] When forward current flows through the above-described Schottky barrier diode, a large number of carriers in the epitaxial semiconductor layer move to the barrier metal and turn on, and at this time, the voltage-current characteristics follow Schottky characteristics.

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

[0005] For applications requiring fast turn-off and small off-current (Ioff), Schottky barrier diodes require a structure that improves off-current (Ioff) while maintaining the advantages of turn-on current (Ion). The problem to be solved

[0006] The present invention aims to provide a Schottky barrier diode with improved off-current characteristics while maintaining the advantages of turn-on current.

[0007] In addition, the present invention has another objective of providing a Schottky barrier diode having improved off-current characteristics by forming semiconductor regions that form a junction barrier by depletion such that the widths for a first direction and a second direction perpendicular to each other have the same length. means of solving the problem

[0008] The Schottky barrier diode of the present invention comprises: a barrier metal layer; and a semiconductor substrate forming a Schottky contact with the barrier metal layer; wherein the semiconductor substrate comprises: a first semiconductor region forming a first contact surface that contacts the barrier metal layer; and a second semiconductor region forming second contact surfaces that contact the barrier metal layer and are distributed at a plurality of positions within the first contact surface; wherein the first semiconductor region has insulating properties against reverse current flow flowing from the semiconductor substrate to the barrier metal layer; and each of the second contact surfaces is formed such that the widths in a first direction and a second direction perpendicular to each other have the same length. In addition, the first semiconductor region is depleted into the second semiconductor regions by the reverse current flow, thereby blocking the reverse current flow of the second semiconductor regions. An isolation region is formed along the guard ring on the inner side of the guard ring, and the guard ring and the isolation region may be formed by being located inside the semiconductor substrate and filled with an insulating material. The guard ring may be formed for electrical separation between the inner region and the outer region. An anode electrode may be formed on the upper side of the barrier metal, surrounding three sides of the barrier metal. The anode electrode may be in contact with the guard ring, and the barrier metal may be in contact with the isolation region. The guard ring may surround the isolation region, and the isolation region may be arranged to surround the second semiconductor region. The semiconductor substrate may include an N+ type sublayer and an N- type epitaxial layer on the sublayer. The N-type dopant concentration of the N-well may be higher than the N-type dopant concentration of the epitaxial layer. The epitaxial layer and the P-well may be spaced apart in a vertical direction. The lower surface of the guard ring may be positioned lower than the lower surface of the P-well. Effects of the invention

[0009] The present invention can improve the blocking characteristics of reverse current flow while maintaining the advantages of turn-on current by improving the semiconductor region where depletion is formed.

[0010] In addition, the present invention has the advantage of having improved off-current characteristics by forming semiconductor regions that form a junction barrier by depletion such that the widths for a first direction and a second direction perpendicular to each other have the same length. Brief explanation of the drawing

[0011] FIG. 1 is a plan view according to an embodiment of a Schottky barrier diode of the present invention. FIG. 2 is a cross-sectional view of section 2-2 of FIG. 1 to illustrate forward current flow. FIG. 3 is a cross-sectional view of section 2-2 of FIG. 1 to illustrate reverse current flow. FIG. 4 is a plan view according to another embodiment of the Schottky barrier diode of the present invention. Specific details for implementing the invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The terms used in this specification and claims are not to be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical details of the present invention.

[0013] The embodiments described in this specification and the configurations illustrated in the drawings are preferred embodiments of the present invention and do not represent all technical aspects of the present invention; therefore, various equivalents and modifications that can replace them may exist at the time of filing this application.

[0014] A Schottky barrier diode configured as an embodiment of the present invention can be described with reference to FIGS. 1 to 3.

[0015] FIG. 1 illustrates a planar layout of an embodiment of a Schottky barrier diode, in which the barrier metal layer (BM) and the anode electrode (AN) are not formed. FIG. 2 and FIG. 3 are cross-sectional views of section 2-2 of FIG. 1, and include a semiconductor substrate (SM), a barrier metal layer (BM) and an anode electrode (AN) on one side of the semiconductor substrate (SM), and a cathode electrode (CA) on the back side of the semiconductor substrate (SM).

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

[0017] A semiconductor substrate (SM) has a contact area defined to contact the barrier metal (BM) by a guard ring (10), and the contact area can be understood as an internal area of ​​the guard ring (10).

[0018] In FIG. 1, the guard ring (10) is exemplarily formed in a rectangular shape, and an isolation area (20) is formed along the guard ring (10) on the inner side of the guard ring (10). The guard ring (10) and the isolation area (20) can be understood as an insulating material filled in a trench formed on one side of a semiconductor substrate (SM). Among these, the guard ring (10) is formed for electrical separation between an inner region and an outer region, and the trench isolation area (20) can be understood as being formed as an auxiliary component.

[0019] As shown in FIGS. 2 and 3, a barrier metal layer (BM) is formed on the upper part of a contact area defined by the guard ring (10) described above, and an anode electrode (AN) is formed on the upper part of the barrier metal layer (BM).

[0020] Also, referring to FIG. 1, a first contact surface (30) and second contact surfaces (40) are formed inside the contact area of ​​the guard ring (10).

[0021] The first contact surface (30) is formed in a rectangular shape on the inner side of the guard ring (10). The second contact surfaces (40) are distributed at multiple locations within the first contact surface (30). Each of the second contact surfaces (40) is formed such that the widths for the first direction (e.g. X in FIG. 1) and the second direction (e.g. Y in FIG. 1), which are perpendicular to each other, have the same length, and is exemplified as a circle.

[0022] Referring to FIGS. 2 and 3, the first contact surface (30) can be understood as an upper surface formed by the first semiconductor region of the inner region of the guard ring (10), and the second contact surfaces (40) can be understood as upper surfaces formed by the second semiconductor region of the inner region of the guard ring (10).

[0023] The first semiconductor region can be formed by a P-type semiconductor, and for example, by a P-well (130). The second semiconductor region can be formed by an N-type semiconductor, and for example, by an N-well (140). Hereinafter, the first semiconductor region is described as a P-well (130) and the second semiconductor region is described as an N-well (140).

[0024] The P-well (130) is formed to have a first depth, and the N-well (140) is formed to have a depth equal to or greater than the first depth. FIGS. 2 and 3 illustrate the N-well (140) being formed as a lower well and the P-well (130) being formed as an upper well.

[0025] With reference to FIGS. 2 and FIGS. 3, the structure of a semiconductor substrate (SM) is described.

[0026] A semiconductor substrate (SM) includes a sublayer (100) and an epitaxial layer (110), wherein the sublayer (100) may be formed as an N+ type semiconductor, and the epitaxial layer (110) may be formed as an N- type semiconductor. The epitaxial layer (110) is formed on the upper side of the sublayer (100), and a cast electrode (CA) is formed on the lower side of the sublayer (100), that is, on the back side of the semiconductor substrate (SM).

[0027] In the epitaxial layer (110), the above-described N-well (140) is formed as a lower well, and a P-well (130) is formed as an upper well on top of the N-well (140). Here, the N-well (140) is formed as a high voltage N-well, and the amount of impurities can be determined by considering the epitaxial layer (110) and the sublayer (100).

[0028] Meanwhile, the second contact surfaces (40) formed by the above-mentioned N-well (140) are formed to have a plurality of rows within the first contact surface (30). And, the second contact surfaces (40) of adjacent rows are positioned alternately with each other. Therefore, the second contact surfaces (140) can be uniformly distributed within the first contact surface (30).

[0029] As described above, as the Schottky barrier diode of the present invention is implemented, forward current flow can be ensured as shown in FIG. 2 and reverse current flow can be effectively blocked as shown in FIG. 3.

[0030] More specifically, the P-well (130) forming the first contact surface (30) and the N-well (140) forming the second contact surfaces (40) have Schottky characteristics due to Schottky contact with respect to the forward current flow flowing from the barrier metal layer (BM) to the semiconductor substrate (SM). As a result, as shown in FIG. 2, the forward current flow, i.e., the turn-on current Ion flow, is guaranteed.

[0031] Meanwhile, the P-well (130) has insulating properties against reverse current flow from the semiconductor substrate (SM) to the barrier metal layer (BM).

[0032] Then, the P-well (130) is depleted into the N-well (140) region, i.e., the second contact surfaces (40), by reverse current flow. The depletion region (DP) of the P-well (130) gradually grows, and as a result, the second contact surfaces (40) by the N-well (140) pinch off the depletion region (DP), and the depletion region (DP) forms a junction barrier, and consequently, reverse current flow through the contact surfaces (40) is blocked. That is, the turn-off current Ioff is blocked.

[0033] The second contact surfaces (40) formed by the embodiment of the present invention are formed in a circular shape. Therefore, the growth of the depletion region (DP) due to the growth of the P-well (130) can proceed uniformly on all sides of the second contact surfaces (40), and the pinch-off of the second contact surfaces (40) due to the growth of the depletion region (DP) can proceed efficiently.

[0034] Therefore, the embodiments of FIGS. 1 to 3 can improve the pinch-off characteristics by forming the second contact surfaces (40) where the depletion is formed in a circular shape with widths of equal length in the first and second directions perpendicular to each other. As a result, the Schottky barrier diode can have improved blocking characteristics of reverse current flow while maintaining the advantages of the turn-on current, and can have improved off-current characteristics.

[0035] As shown in FIG. 4 of the present invention, the second contact surfaces (45) may be formed in a square shape. Since FIG. 4 is identical to FIG. 1 except for the shape of the second contact surfaces (45), a redundant description thereof is omitted.

[0036] The second contact surfaces (45) are formed as squares, which are shapes having equal lengths for the widths of the first and second directions perpendicular to each other.

[0037] Therefore, due to the reverse current flow, the depletion region (DP) of the P-well (130) grows at a uniform rate on all four sides. As a result, the pinch-off by the depletion region (DP) of the second contact surfaces (45) by the N-well (140) proceeds efficiently, and the reverse current flow through the contact surfaces (45) can be effectively blocked.

[0038] That is, in the embodiment of FIG. 4, the second contact surfaces (45) where the depletion is formed are formed as squares, which are examples of shapes having equal lengths for the widths of the first and second directions perpendicular to each other, thereby improving the pinch-off characteristics. As a result, the Schottky barrier diode can have improved blocking characteristics of reverse current flow while maintaining the advantages of the turn-on current, and can have improved off-current characteristics.

[0039] The second contact surfaces (45) may be composed of regular polygons such as a regular octagon, in addition to the circle of FIG. 1 and the square of FIG. 4, in which the widths for the first and second directions perpendicular to each other have the same length.

[0040] That is, the Schottky barrier diode of the present invention can be applied to applications requiring fast turn-off and small off-current (Ioff), such as mobile integrated circuits.

Claims

Claim 1 A barrier metal layer defined by a guard ring filled with an insulating material; and a semiconductor substrate forming a Schottky contact with the barrier metal layer; wherein the semiconductor substrate comprises: a first semiconductor region formed by a P-well having a first depth and forming a first contact surface that contacts the barrier metal layer; and a second semiconductor region formed by an N-well that is equal to or deeper than the first depth and forming second contact surfaces distributed at a plurality of locations within the first contact surface that contact the barrier metal layer; wherein the first semiconductor region has insulating properties against reverse current flow flowing from the semiconductor substrate to the barrier metal layer; and each of the second contact surfaces is formed such that the widths in a first direction and a second direction perpendicular to each other have equal lengths; And, the first semiconductor region is depleted into the second semiconductor regions by the reverse current flow, so that the second contact surfaces are pinch-off, thereby the second semiconductor regions block the reverse current flow, and an isolation region is formed along the guard ring on the inner side of the guard ring, and the guard ring and the isolation region are located inside the semiconductor substrate and formed by being filled with an insulating material, and the guard ring is formed for electrical separation between the inner region and the outer region, and an anode electrode is formed on the upper side of the barrier metal, surrounding three sides of the barrier metal, and the anode electrode is in contact with the guard ring, and the barrier metal is in contact with the isolation region, and the guard ring surrounds the isolation region, and the isolation region surrounds the second semiconductor region, and the semiconductor substrate includes an N+ type sublayer and an N- type epitaxial layer on the sublayer, and the N-type dopant concentration of the N-well is of the epitaxial layer A Schottky barrier diode in which the concentration is higher than that of an N-type dopant, the epitaxial layer and the P-well are spaced apart in a vertical direction, and the lower surface of the guard ring is positioned lower than the lower surface of the P-well. Claim 2 In claim 1, the first semiconductor region and the second semiconductor region are Schottky barrier diodes having Schottky characteristics with respect to forward current flow from the barrier metal layer to the semiconductor substrate. Claim 3 In claim 1, the N-well is a Schottky barrier diode formed as a high-voltage N-well. Claim 4 In claim 1, each of the second contact surfaces is a Schottky barrier diode formed in a circular shape. Claim 5 In claim 1, each of the second contact surfaces is formed as a square Schottky barrier diode. Claim 6 In claim 1, the second contact surfaces are formed to have a plurality of rows within the first contact surface, and the second contact surfaces of adjacent rows are positioned staggered with respect to each other, forming a Schottky barrier diode.

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