KR20150041673A - Semiconductor device - Google Patents

Abstract

A semiconductor device of an embodiment comprises: a first conductivity type nitride semiconductor layer including Al_xIn_yGa_(1-x-y)N (0<=x<=1, 0<=y<=1, 0<=x+y<=1); a second conductivity type nitride semiconductor layer including Al_xIn_yGa_(1-x-y)N (0<=x<=1, 0<=y<=1, 0<=x+y<=1) arranged on the first conductivity type nitride semiconductor layer; and a first electrode including a body unit which penetrates the second conductivity type nitride semiconductor layer and is in contact with the first and the second conductivity type nitride semiconductor layer, and an extension unit which is enlarged from the body unit to the horizontal direction, and arranged on the second conductivity type nitride semiconductor layer.

Description

Semiconductor device

Embodiments relate to semiconductor devices.

In general, a diode used in a circuit suitable for high-voltage switching is reverse-operated, that is, in a situation where the cathode voltage is higher than the anode voltage, the reverse leakage current should be as small as possible and can withstand high voltages, for example at least 600 volts or 1200 volts .

Semiconductor devices such as Schottky barrier diodes (SBDs), which are a kind of diodes, are used as a core part of a switch-mode power supply (SMPS) together with transistors. This is because the SBD has excellent switching speed and on-state performance.

In particular, GaN implementing semiconductor devices has a high breakdown voltage characteristic and a high electron saturation rate, and accordingly has physical properties favoring large current, large power and high voltage devices. Thus, GaN has advantageous physical properties that can be applied to power devices such as wide bandgap, two-dimensional electron channel (2DEG), high mobility, and high breakdown field. However, when a reverse voltage is applied to the SBD implemented using GaN, the electric field can be concentrated in the vicinity of the edge of the electrode. As a result, leakage currents larger than those of GaN are generated, and the yielding phenomenon may occur at a voltage lower than the physical property limit. In order to overcome this, when the substrate is made of SiC, a guard ring formed by implanting impurity ions into a substrate made of SiC can be used. However, when the substrate is implemented with GaN, there is a problem that the guard ring is not formed well even when impurities are implanted and diffused into the GaN.

The embodiment provides a semiconductor device capable of alleviating electric field concentration at the edge of an electrode.

The semiconductor device according to the embodiment includes a first conductivity type nitride semiconductor layer including Al _x In _y Ga _(1-xy) N (0 x 1, 0 y 1, 0 x + y 1) ; _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) disposed on the first conductive type nitride semiconductor layer, A nitride semiconductor layer; And a body portion extending through the second conductive type nitride semiconductor layer and in contact with the first and second conductive type nitride semiconductor layers, and an extension portion extending in the horizontal direction from the body portion and disposed on the second conductive type nitride semiconductor layer And a second electrode.

The semiconductor device may further include a passivation layer disposed between the extended portion of the first electrode and the second conductive type nitride semiconductor layer.

The passivation layer may be disposed to cover upper and side portions of the second conductive type nitride semiconductor layer and an upper surface of the first conductive type nitride semiconductor layer.

The semiconductor device may further include a second electrode disposed below the first conductive type nitride semiconductor layer and facing the first electrode.

Alternatively, the semiconductor device may further include a second electrode disposed on a side of the first electrode so as to be in contact with the first conductive type nitride semiconductor layer.

The second conductive type nitride semiconductor layer may have a thickness of 30 nm to 70 nm.

The width of the second conductive type nitride semiconductor layer may be greater than or equal to the width of the extension of the first electrode.

The first conductive type nitride semiconductor layer may include n-type GaN, and the second conductive type nitride semiconductor layer may include p-type GaN.

The semiconductor device may include a Schottky diode including a cathode that is the first electrode and a cathode that is the second electrode.

The second conductive type nitride semiconductor layer may be an epitaxially grown layer on the first conductive type nitride semiconductor layer.

The semiconductor device according to the embodiment can be applied to an SBD in which a reverse conduction characteristic is stabilized and a leakage current is reduced by epitaxially growing a second conductivity type nitride semiconductor layer on the first conductivity type nitride semiconductor layer and unlike a horizontal SBD, Can be applied to a horizontal SBD with almost no change in size.

1 is a block diagram of a semiconductor device according to an embodiment.
2A to 2C show cross-sectional views of an SBD according to an embodiment.
3A to 3D are process cross-sectional views illustrating a manufacturing method according to an embodiment of the semiconductor device illustrated in FIG.
Figure 4 shows a cross-sectional view of a typical horizontal SBD.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

In the description of the embodiment according to the present invention, in the case of being described as being formed on the "upper" or "on or under" of each element, on or under includes both elements being directly contacted with each other or one or more other elements being indirectly formed between the two elements. Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

It is also to be understood that the terms "first" and "second", "upper" and "lower", etc., as used below, do not necessarily imply or imply any physical or logical relationship or order between such entities or elements And may be used only to distinguish one entity or element from another entity or element.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size.

1 shows a block diagram of a semiconductor device 100 according to an embodiment.

Referring to FIG. 1, a semiconductor device 100 includes a first conductive type nitride semiconductor layer 110, a second conductive type nitride semiconductor layer 120, a passivation layer 130, and a first electrode 140 .

FIG. 1 shows an example in which the semiconductor device 100 is applied to a vertical Schottky barrier diode (SBD), but the embodiment is not limited to this. In other words, the semiconductor device 100 may be applied to other devices than the SBD.

Whether the SBD is vertical or horizontal is determined by the current flowing in the SBD. That is, in the case of a vertical SBD, current flows vertically from the anode to the cathode, and in the case of the horizontal SBD, current flows horizontally from the anode to the cathode.

The second conductive type nitride semiconductor layer 120 is disposed on the first conductive type nitride semiconductor layer 110.

The first conductive type nitride semiconductor layer 110 is a substrate, and may be formed of a compound semiconductor such as a group III-V element or a group II-VI element. For example, the first conductive type nitride semiconductor layer 110 may have a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + And the like. When the first conductive type nitride semiconductor layer 110 is an n-type nitride semiconductor layer, the first conductive type dopant may include n-type dopants such as Si, Ge, Sn, Se, and Te. The first conductive type nitride semiconductor layer 110 may be formed as a single layer or a multilayer, but the present invention is not limited thereto.

The second conductive type nitride semiconductor layer 120 may be formed of a compound semiconductor such as a group III-V element or a group II-VI element. For example, the second conductive type nitride semiconductor layer 120 may have a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + And the like. When the second conductive type nitride semiconductor layer 120 is a p-type nitride semiconductor layer, the second conductive type dopant may include a p-type dopant such as Mg, Zn, Ca, Sr, and Ba. The second conductive type nitride semiconductor layer 120 may be formed as a single layer or a multilayer, but the present invention is not limited thereto.

For example, the first conductive type nitride semiconductor layer 110 may be an n-type GaN layer, and the second conductive type nitride semiconductor layer 120 may be a p-type GaN layer.

Meanwhile, the first electrode 140 includes a body portion 142 and extension portions 144-1 and 144-2. The first electrode 140 may correspond to the anode (A: anode) of the SBD.

The body portion 142 passes through the second conductive type nitride semiconductor layer 120 and is in schottky contact with the first conductive type nitride semiconductor layer 110. In addition, the body portion 142 also contacts the second conductive type nitride semiconductor layer 120. The thickness t of the second conductive type nitride semiconductor layer 120 may be several tens nm. For example, when the thickness t of the second conductive type nitride semiconductor layer 120 is less than 30 nm or greater than 70 nm, the edges (x1, x2) of the first electrode 140 The electric field dispersion effect at the edge (x2) may be insignificant. Therefore, the second conductivity type nitride semiconductor layer 120 may have a thickness t of 30 nm to 70 nm.

The extension portions 144-1 and 144-2 extend in the horizontal direction from the body portion 142 and are disposed on the second conductive type nitride semiconductor layer 120. [ At this time, the width of the second conductive type nitride semiconductor layer 120 may be equal to or greater than the width of the extended portions 144-1 and 144-2 of the first electrode 140. For example, as illustrated in FIG. 1, the width of the second conductive type nitride semiconductor layer 120 may be greater than the width of the extended portions 144-1 and 144-2 by a predetermined width W. Here, when the predetermined width W is a positive real number, the phenomenon that the electric field concentrates at the edges (x1, s2) 145, 143 of the first electrode 140 can be further mitigated.

The first electrode 140 may be a refractory metal or a mixture of such refractory metals. Alternatively, the first electrode 140 may be formed of one selected from the group consisting of Pt (Platinum), Ge (Germanium), Cu (Copper), Cr (Chromium), Ni (Tantalum), TaN (Tantalum Nitride), TiN (Titanium Nitride), Pd (Palladium), W (tungsten) or WSi ₂ (Tungstem silicide).

The passivation layer 130 is disposed between the extension portions 144-1 and 144-2 of the first electrode 140 and the second conductive type nitride semiconductor layer 120. [ In particular, the passivation layer 130 is disposed to cover the top and sides of the second conductivity type nitride semiconductor layer 120.

In addition, when the upper portion of the first conductive type nitride semiconductor layer 110 is exposed, the performance of the semiconductor device 100 may not be predicted. Accordingly, the passivation layer 130 may be disposed such that the upper surface of the first conductive type nitride semiconductor layer 110 is not exposed while covering the upper portion of the first conductive type nitride semiconductor layer 110.

The passivation layer 130 may comprise an insulating material and may include at least one of, for example, SiN _x (where x is a positive integer), MgO, Sc ₂ O ₃ , SiO ₂ , SOG, or SOD have.

The passivation layer 130 disposed between the extensions 144-1 and 144-2 of the first electrode 140 and the second conductive type nitride semiconductor layer 120 is formed of a field plate It also plays a role.

The second electrode corresponding to the cathode of the SBD implemented by the semiconductor device 100 may be arranged in various forms as illustrated in FIGS. 2A to 2C.

2A to 2C show cross-sectional views of the SBDs 100A, 100B and 100C according to the embodiment.

The semiconductor device 100 illustrated in FIG. 1 may be implemented with various types of SBDs 100A, 100B, and 100C as illustrated in FIGS. 2A to 2C. The SBDs 100A, 100B, and 100C illustrated in FIGS. 2A to 2C have the same configuration except that only the cathodes 150A, 150B, and 150C are disposed.

The SBD 100A illustrated in FIG. 2A may further include a second electrode 150A disposed below the first conductive type nitride semiconductor layer 110 to face the first electrode 140 as a cathode.

The SBDs 100B and 100C illustrated in FIGS. 2B and 2C are formed by sequentially forming second electrodes 150B and 150C disposed on the sides of the first electrode 140 in contact with the first conductive type nitride semiconductor layer 110 as cathodes . In the case of the SBD 100B illustrated in FIG. 2B, the second electrode 150B is disposed on the upper surface of the first conductive type nitride semiconductor layer 110. FIG. On the other hand, in the case of the SBD 100C illustrated in FIG. 2C, the second electrode 150C is disposed more deeply than the upper surface of the first conductive type nitride semiconductor layer 110.

The SBDs 100A, 100B, and 100C illustrated in FIGS. 2A to 2C are all vertical, and current flows from the anode 140 toward the cathodes 150A, 150B, and 150C. That is, in the SBD 100A illustrated in FIG. 2A, a current flows in a vertical direction as indicated by an arrow 162 from the first electrode 140 to the second electrode 150A. In the SBDs 100B and 100C illustrated in FIGS. 2B and 2C, the current flows from the first electrode 140 to the second electrode 150B and 150C in the vertical direction as indicated by arrows 164 and 166 Next, it flows in the horizontal direction and then flows in the vertical direction again.

The horizontal SBD saturates current, while the SBD illustrated in Figs. 2A to 2C is vertical type (100A, 100B, 100C), and current is not saturated.

In addition, when the cathode 150A of the SBD 100A is disposed as illustrated in FIG. 2A, when the cathodes 150B and 150C of the SBDs 100B and 100C are arranged as illustrated in FIG. 2B or FIG. 2C, Multiple heat release can be excellent.

The second electrodes 150A, 150B, and 150C illustrated in FIGS. 2A to 2C are in ohmic contact with the first conductive type nitride semiconductor layer 110. FIG. Accordingly, the second electrodes 150A, 150B, and 150C can serve as the cathodes of the SBDs 100A, 100B, and 100C. The second electrodes 150A, 150B and 150C may be formed of a metal material having an ohmic characteristic such as aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni) (Au), and may have a single-layer structure or a multi-layer structure.

The first electrode 140 and the second electrodes 150A, 150B, and 150C may include different metal materials.

Hereinafter, the manufacturing method according to the embodiment of the semiconductor device 100 illustrated in FIG. 1 will be described with reference to the accompanying drawings, but it goes without saying that the semiconductor device 100 can also be manufactured by other methods.

3A to 3D are process cross-sectional views for explaining a manufacturing method according to an embodiment of the semiconductor device 100 illustrated in FIG.

Referring to FIG. 3A, a second conductive type nitride semiconductor layer 120A is formed on the first conductive type nitride semiconductor layer 110. Referring to FIG. For example, the second conductive type nitride semiconductor layer 120A may be formed on the first conductive type nitride semiconductor layer 110 by epitaxial growth.

The first conductive type nitride semiconductor layer 110 may be formed of a compound semiconductor such as a group III-V element or a group II-VI element. For example, the first conductive type nitride semiconductor layer 110 may have a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + Or the like. The first conductive type nitride semiconductor layer 110 may be formed as a single layer or a multilayer, but the present invention is not limited thereto.

The second conductive type nitride semiconductor layer 120A may be formed of a compound semiconductor such as a group III-V element or a group II-VI element. For example, the second conductive type nitride semiconductor layer 120A may have a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + Or the like. The second conductive type nitride semiconductor layer 120A may be formed as a single layer or a multilayer, but is not limited thereto.

Referring to FIG. 3B, the second conductive type nitride semiconductor layer 120A is patterned and etched so that the upper surface of the first conductive type nitride semiconductor layer 110 in the portion where the first electrode 140 is to be formed is exposed. Such an etching process can be performed by photolithography, e-bem lithography, or nano-imprinted lithography.

Referring to FIG. 3C, a portion of the upper surface of the first conductive type nitride semiconductor layer 110 exposed by the patterned second conductive type nitride semiconductor layer 120, except for a portion to be in contact with the first electrode 140, A passivation layer 130 is formed on the upper and side portions of the second conductive type nitride semiconductor layer 120.

For example, a metal organic chemical vapor deposition (MOCVD), a chemical vapor deposition (CVD), a PECVD, an LPCVD, a molecular beam epitaxy (MBE), an inductively coupled plasma chemical vapor deposition The upper part and the side of the second conductive type nitride semiconductor layer 120 and the exposed part of the first conductive type nitride semiconductor layer 120 are formed by a method such as Coupled Plasma Chemical Vapor Deposition (HVPE) or Hydride Vapor Phase Epitaxy (HVPE) The passivation layer 130 may be formed on the passivation layer 110.

The passivation layer 130 is then etched to expose the top surface of the first conductive nitride semiconductor layer 110 where the body portion 142 of the first electrode 140 is to be formed. In this embodiment, the etching process can be performed by photolithography, e-bem lithography, or nano-imprinted lithography.

The passivation layer 130 may be formed of an insulating material and may be formed by at least one of SiN _x (where x is a positive integer), MgO, Sc ₂ O ₃ , SiO ₂ , SOG, or SOD .

Referring to FIG. 3D, a first electrode 140 is formed on an upper portion of the first conductive type nitride semiconductor layer 110 and an upper portion of the passivation layer 130, which are not covered by the passivation layer 130. That is, the body portion 142 of the first electrode 140 is disposed to pass through the passivation layer 130 and the second conductive type nitride semiconductor layer 120, and the extension portion 144 -1, and 144-2 extend in the horizontal direction from the body portion 142 and are disposed on the upper portion of the passivation layer 120.

The first electrode 140 may be formed of a refractory metal or a mixture of these refractory metals. Alternatively, the first electrode 140 may be formed of one selected from the group consisting of Pt (Platinum), Ge (Germanium), Cu (Copper), Cr (Chromium), Ni (Tantalum), TaN (Tantalum Nitride), TiN (Titanium Nitride), Pd (Palladium), W (tungsten) or WSi ₂ (Tungstem silicide).

Generally, when semiconductor devices are fabricated, the characteristics of semiconductor devices vary greatly depending on how the edge portions of the first electrode 140 are terminated. Since it is not easy to introduce a guard ring by doping impurity ions into the first conductive type nitride semiconductor layer 110, according to the embodiment, the first conductive type nitride semiconductor layer 110 The second conductive type nitride semiconductor layer 120 is formed so as to be in contact with the edge x2 of the first electrode 140.

If the second conductive type nitride semiconductor layer 120 is not present in the semiconductor device 100 illustrated in FIG. 1, a depletion area DA1 (Depletion Area 1) formed in the first conductive type nitride semiconductor layer 110 The electric field can be concentrated by rapidly changing at the corner (x2) of the one electrode (140).

However, according to the embodiment, since the second conductive type nitride semiconductor layer 120 is formed on the first conductive type nitride semiconductor layer 110 so as to be in contact with the edge x2 of the first electrode 140, The depletion region DA2 of the nitride semiconductor layer 110 does not change rapidly but changes slowly. This causes the electric field 210 rapidly changing at the edge x2 of the first electrode 140 to spread over the entire first conductive type nitride semiconductor layer 110 so that the edge x2 of the first electrode 140 The electric field 220 can be relaxed. Also, since the second conductive type nitride semiconductor layer 120 is formed on the first conductive type nitride semiconductor layer 110, the electric field at the other edge x 1 of the first electrode 140 can also be gradually changed.

The passivation layer 130 disposed between the extension portions 144-1 and 144-2 and the second conductive type nitride semiconductor layer 120 as well as the second conductive type nitride semiconductor layer 120 may be formed on the field plate The electric field at the corners 143 and 145 (x2, x1) of the first electrode 140 can be more smoothly changed.

Thus, the reverse voltage characteristic of the SBD implemented by the semiconductor device 100 can be stabilized and the leakage current can be reduced.

Figure 4 shows a cross-sectional view of a typical horizontal SBD.

The horizontal SBD illustrated in FIG. 4 includes a substrate 300, a GaN layer 310 and an AlGaN layer 320, an anode (A), and a cathode (C). A two dimensional electron gas (2-DEG: two-dimensional electron gas) may be generated in the channel layer 312 by hetero-junction having different band gap energy between the AlGaN layer 320 and the GaN layer 310 . In the case of such a horizontal SBD, the current flows horizontally through the channel layer 312.

In the case of a horizontal SBD as illustrated in FIG. 4, the overall length L1 of the SBD in the horizontal direction must be increased to increase the breakdown voltage. Therefore, the size of the SBD must be increased.

On the other hand, in the case of the SBD including the semiconductor device 100 according to the embodiment illustrated in FIG. 1, in order to increase the breakdown voltage, it is not necessary to increase the horizontal length L2 of the SBD, H). The length H in the vertical direction is much smaller than the thickness T of the first conductive type nitride semiconductor layer 110. Therefore, unlike the horizontal SBD illustrated in FIG. 4, there is almost no change in the size of the semiconductor device 100 when the breakdown voltage is to be increased.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

100: Semiconductor devices 100A to 100C: SBD
110: first conductivity type nitride semiconductor layer
120: second conductive type nitride semiconductor layer 130: passivation layer
140: first electrode 142:
144-1 and 144-2: Extension parts 150A to 150C:

Claims (10)

A first conductive type nitride semiconductor layer including Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + y?
_(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) disposed on the first conductive type nitride semiconductor layer, A nitride semiconductor layer; And
A body portion passing through the second conductive type nitride semiconductor layer and in contact with the first and second conductive type nitride semiconductor layers, and an extension portion extending in the horizontal direction from the body portion and disposed on the second conductive type nitride semiconductor layer And a second electrode formed on the first electrode. The semiconductor device of claim 1, further comprising a passivation layer disposed between the extension of the first electrode and the second conductive type nitride semiconductor layer. 3. The device of claim 2, wherein the passivation layer
And the second conductive type nitride semiconductor layer is disposed to cover upper and side portions of the second conductive type nitride semiconductor layer and the upper surface of the first conductive type nitride semiconductor layer. The semiconductor device according to claim 1, further comprising a second electrode disposed below the first conductive type nitride semiconductor layer and facing the first electrode. The semiconductor device according to claim 1, further comprising a second electrode disposed on a side of the first electrode so as to be in contact with the first conductive type nitride semiconductor layer. The semiconductor device according to claim 1, wherein the second conductivity type nitride semiconductor layer has a thickness of 30 nm to 70 nm. The semiconductor device according to claim 1, wherein a width of the second conductive type nitride semiconductor layer is equal to or greater than a width of an extended portion of the first electrode. 2. The nitride semiconductor light emitting device according to claim 1, wherein the first conductive type nitride semiconductor layer comprises n-type GaN,
And the second conductive type nitride semiconductor layer comprises p-type GaN. The semiconductor device according to claim 4 or 5, comprising a Schottky diode including a cathode which is the first electrode and a cathode which is the second electrode. The semiconductor device according to claim 8, wherein the second conductive type nitride semiconductor layer is an epitaxially grown layer on the first conductive type nitride semiconductor layer.

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