Patent Application
20250048662
This application claims the benefit of Korean Patent Application No. 10-2023-0101226, filed on Aug. 2, 2023, which application is hereby incorporated herein by reference.
A semiconductor device and a method of manufacturing the same are disclosed.
Power conversion devices such as inverters, converters, and OBCs (on board chargers) play the role of converting electrical energy into a form suitable for electrical components, and power semiconductors perform switching and rectification operations in the components responsible for power conversion.
Existing power semiconductors mainly use silicon (Si) materials, but recently, gallium nitride (GaN) and silicon carbide (SiC) power semiconductors with improved performance have begun to be mass-produced and installed in vehicles. Recently, demands for ultra-high voltage and power ICs and interest in low-cost materials are increasing, and beta-gallium oxide (ß-Ga2O3) (4.8 eV), which has a wider bandgap than 4H-SiC (3.2 eV), has recently received attention.
Meanwhile, the use of p type materials is necessary for further improvements in power semiconductor diodes and other devices that require lower resistivity (Ron) and higher breakdown voltage. Currently, the development of p-type ß-Ga2O3 is not easy to implement and is not stable for commercialization.
An embodiment provides a semiconductor device having a high breakdown voltage and low leakage current.
Another embodiment provides a method of manufacturing the semiconductor device.
According to an embodiment, a semiconductor device includes an n type layer disposed on a first surface of a substrate and including beta-gallium oxide (ß-Ga2O3), a p type layer disposed on the n type layer and including nickel oxide represented by MyNi1-yOx (Chemical Formula 1), a first electrode disposed on the p type layer, and a second electrode disposed on a second surface of the substrate.
In Chemical Formula 1, M is a doping element, x is 0.8≤x≤1.0, and y is 0≤y<1.
A P-N heterojunction may be formed at the contact surface of the n type layer and the p type layer.
The substrate may include n type gallium oxide (Ga2O3), and the n type gallium oxide may include n type gallium oxide doped with Si or Sn.
The substrate may have a doping concentration of about 1×1016 cm−3 to about 1×1020 cm−3.
A thickness of the substrate may be about 100 μm to about 700 μm.
The beta-gallium oxide may include beta-gallium oxide doped with Si or Sn.
The n type layer may have a doping concentration of about 1×1015 cm−3 to about 1×1017 cm−3.
A thickness of the n type layer may be about 1 μm to about 10 μm.
In Chemical Formula 1, y may be 0<y<1, and in Chemical Formula 1, y may be 0.06≤y≤0.1.
The doping element may include a monovalent element, a divalent element, or a combination thereof, and the monovalent element may include Li, K, Cu, Ag, Cs, or a combination thereof, and the divalent element may include Mg, Ca, Sr, Ba, or a combination thereof.
A thickness of the p type layer may be about 10 nm to about 300 nm.
The first electrode may be an anode, and the second electrode may be a cathode.
According to another embodiment, a method of manufacturing a semiconductor device includes forming an n type layer including beta-gallium oxide (ß-Ga2O3) on a first surface of a substrate, forming a p type layer including the nickel oxide represented by Chemical Formula 1 on the n type layer, forming a first electrode on the p type layer, and forming a second electrode on a second surface of the substrate.
The p type layer may be formed by a radio frequency (RF) sputtering process, and the partial pressure of oxygen injected during the RF sputtering process may be about 5% to about 30%.
A semiconductor device according to an embodiment can have a high breakdown voltage while suppressing leakage current, and accordingly, high performance can be achieved with a simple process in a beta-gallium oxide (ß-Ga2O3)-based device. This is a ß-Ga2O3-based device and can contribute to the development of various device structures, including Schottky and MOS types as well as junction FETs.
The advantages, features, and aspects to be described hereinafter will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. However, the embodiments should not be construed as being limited to the embodiments set forth herein. Although not specifically defined, all of the terms including the technical and scientific terms used herein have meanings understood by ordinary persons skilled in the art. The terms defined in a generally used dictionary may not be interpreted ideally or exaggeratedly unless clearly defined. In addition, unless explicitly described to the contrary, the word “comprise”, and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
Further, the singular includes the plural unless mentioned otherwise.
In the drawings, the thickness of layers, films, panels, regions, etc. are exaggerated for clarity. Like reference numerals designate like elements throughout the specification.
It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
The semiconductor device according to an embodiment is a device based on beta-gallium oxide (ß-Ga2O3), an ultra-wide band gap (UWBG) material, and may have a diode structure, but it is not limited to this structure, and it may achieve high breakdown voltage and low leakage current characteristics through P-N heterojunction.
Referring to
The substrate 100 may include n type gallium oxide (Ga2O3). The n type gallium oxide may be beta-phase of beta-gallium oxide (ß-Ga2O3). The n type gallium oxide may include undoped n type gallium oxide, n type gallium oxide doped with Si or Sn, or a combination thereof, for example, n type gallium oxide doped with Si or Sn may be used.
The substrate 100 may have a doping concentration of about 1×1016 cm−3 to about 1×1020 cm−3, for example, about 1×1017 cm−3 to about 1×1019 cm−3. When the substrate has a doping concentration within the ranges, appropriate values for on-resistance and breakdown voltage characteristics in a trade-off relationship may be secured.
The substrate 100 may have a thickness of about 100 μm to about 700 μm, for example, about 200 μm to about 700 μm.
The n type layer 200 is disposed as an epitaxial layer on the first surface of the substrate 100.
The n type layer 200 includes beta-gallium oxide (ß-Ga2O3) as an n type semiconductor material. The beta-gallium oxide may include an undoped beta-gallium oxide, an Si- or Sn-doped beta-gallium oxide, or a combination thereof, for example, the Si- or Sn-doped beta-gallium oxide.
The n type layer 200 may have a doping concentration of about 1×1015 cm 3 to about 1×1017 cm−3, for example, about 1×1016 cm−3 to about 1×1017 cm−3. When the n type layer has a doping concentration within the ranges, appropriate values for on-resistance and breakdown voltage characteristics in a trade-off relationship may be secured.
The n type layer 200 may have a thickness of about 1 μm to about 10 μm, for example, about 2 μm to about 10 μm.
The p type layer 300 is disposed on the n type layer 200 and includes nickel oxide as a p type semiconductor material. The p type layer 300 is disposed between the n type layer 200 and the first electrode 400 to form an interlayer.
According to an embodiment, as the p type layer 300 of a p type nickel oxide material is formed to be inserted between the n type layer 200 of an n type beta-gallium oxide material and the first electrode 400 of a metal material, P-N heterojunctions (hetero junctions) are formed on the contacting surface of the n type layer 200 and the p type layer 300, thereby obtaining a semiconductor device having high breakdown voltage and low leakage current characteristics.
The nickel oxide may be specifically represented by Chemical Formula 1.
MyNi1-yOx Chemical Formula 1:
In Chemical Formula 1, M is a doping element, x is 0.8≤x≤1.0, and y is 0≤y<1.
The nickel oxide, as shown in Chemical Formula 1, may be undoped NiOx or NiOx doped with a doping element.
Since conductivity of the nickel oxide is caused by a hole state induced by Ni vacancies, in oxygen-rich conditions, energy formation for the Ni vacancies is low, while energy formation for oxygen (O) vacancies is high. Accordingly, the Ni vacancies may be increased by adding impurities such as Li, wherein one hole goes to a balance band, keeping the charge neutral. Accordingly, when the nickel oxide is used to form the p type layer, a carrier concentration may be controlled by adjusting an oxygen content or doping.
In other words, when NiOx doped with a doping element is used to form the p type layer 300, the Ni vacancies may be increased to increase the conductivity of the nickel oxide, and the carrier concentration may be controlled, exhibiting more excellent high breakdown voltage and low leakage current characteristics.
The doping element may include a monovalent element, a divalent element, or a combination thereof. The monovalent element may include Li, K, Cu, Ag, Cs, or a combination thereof, for example, Li may be used. The divalent element may include Mg, Ca, Sr, Ba, or a combination thereof.
The doping element may have a content indicated by y, which is about 0≤y<1, for example, about 0<y<1, or for example about 0.06≤y≤0.1. When a nickel oxide doped with the content ranges is used to form a p type layer, conductivity and a carrier concentration may be increased, securing more excellent high breakdown voltage and low leakage current characteristics.
A thickness of the p type layer 300 may be about 10 nm to about 300 nm, for example, about 50 nm to about 300 nm.
The first electrode 400 is disposed on the p type layer 300 in the top of the substrate 100 and may be an anode.
The first electrode 400 may include a metal of Ni, Au, Ag, or a combination thereof, and for example, Ni metal may be used.
The first electrode 400 may have a single-layer or a multi-layer structure.
The second electrode 500 may be disposed at the bottom of the substrate 100, that is, on the second surface of the substrate 100, and may be a cathode.
The second electrode 500 may include metals such as Ti, Au, Al, Mo, or a combination thereof, and for example, metals such as Ti and Au may be used.
The second electrode 500 may have a single-layer or a multi-layer structure, and as for the multi-layer structure, a second electrode may include, for example, a Ti metal layer and an Au metal layer.
The above semiconductor device may exhibit high breakdown voltage and low leakage current characteristics by inserting the p type layer of a nickel oxide material between the n type layer of a ß-Ga2O3 material and the first electrode of a Ni metal to form P-N heterojunctions on the interface thereof. Accordingly, the beta-gallium oxide (ß-Ga2O3)-based device may realize high performance in a simple process, which may lead to developing a beta-gallium oxide (ß-Ga2O3)-based device with various device structures including a junction FET (field effect transistor) as well as Schottky types and MOS (metal oxide semiconductor) types.
The semiconductor device can be manufactured in the following manner.
A substrate 100 is prepared, an n type layer 200, a p type layer 300, and a first electrode 400 are sequentially formed on the first surface of the substrate 100, and the second electrode 500 is formed on the second surface of the substrate 100.
For example, the second electrode 500, the substrate 100, the n type layer 200, the p type layer 300, and the first electrode 400 are sequentially deposited to form a desired structure through a lift-off process or an etching process.
The p type layer 300 may be formed by a radio frequency (RF) sputtering process.
In the RF sputtering process, an injected oxygen partial pressure may be about 5% to about 30% or, for example, about 10% to about 30%. When oxygen is injected within the ranges, the conductivity and carrier concentration of the nickel oxide may be controlled to exhibit more excellent high breakdown voltage and low leakage current characteristics.
According to the aforementioned method of manufacturing a semiconductor device, a semiconductor device having high performance such as low leakage current and high breakdown voltage characteristics in a simple process may be manufactured.
Hereinafter, the embodiments are illustrated in more detail with reference to examples. However, these examples are exemplary, and the scope of the claims is not limited thereto.
With the same structure as in
Herein, the substrate 100 was prepared by using Sn-doped n type Ga2O3 to have a doping concentration of 4.3×1018 cm−3 and a thickness of 642 μm. The n type layer 200 was prepared by using Si-doped n type ß-Ga2O3 to have a doping concentration of 3.5×1016 cm−3 and a thickness of 10 μm. The p type layer 300 was prepared by using undoped NiOx to have a thickness of 300 nm. The first electrode 400 was an anode prepared by using a Ni metal to have a thickness of 100 nm. The second electrode 500 was a cathode prepared by forming a 160 nm-thick Au metal layer and a 20 nm-thick Ti metal layer on the Au metal layer to have a multi-layer structure.
The p type layer was formed through a RF sputtering process and specifically through deposition by injecting 20% of an oxygen partial pressure into a NiO (Ni:O=1:1) target. As a result of X-ray photoelectron spectroscopy (XPS) analysis, the formed NiO thin film had 49.59 atom % of nickel (Ni) and 50.41 atom % of oxygen (O), which had an atomic ratio of about 1:1 and thus confirmed that the NiO thin film was stable.
A semiconductor device was manufactured in the same manner as in Example 1 except that the p type layer 300 was prepared by using Li-doped NiOx.
A semiconductor device was manufactured in the same manner as in Example 1 except that the p type layer 300 was not formed.
(1) In order to evaluate electrical characteristics of an undoped NiOx thin film used for forming a p type layer in Example 1, an undoped NiOx thin film was deposited on a slide glass through a RF sputtering process, while increasing the oxygen content, and then measured with respect to electrical characteristics, and the results are shown in
Referring to
(2) In order to evaluate electrical characteristics of the Li-doped NiOx thin film used for forming a p type layer in Example 2, a Li-doped NiOx thin film was deposited on a slide glass through a RF sputtering process, while increasing an oxygen content, and then evaluated with respect to electrical characteristics through a hall effect measurement method, and the results are shown in
Referring to
(1) In order to evaluate optical characteristics of the undoped NiOx thin film for forming a p type layer in Example 1, a NiOx thin film was formed through RF sputtering and then measured with respect to transmittance of through UV-visible spectroscopy, and the results are shown in
Referring to
(2) In order to examine optical characteristics of the Li-doped NiOx thin film for using a p type layer in Example 2, a Li-doped NiOx thin film was formed through RF sputtering and then measured with respect to transmittance by using a UV-visible spectrometer, and the results are shown in
Referring to
Referring to
Referring to
Accordingly, when a p type layer formed of NiOx was inserted on the interface between the n type layer and the electrode, a breakdown voltage was increased, improving the on-resistance characteristics. Accordingly, conductivity may be inferred to be effectively controlled by doping NiOx with Li to substitute Ni sites and thus to produce LiNi receptors or supplying reactive oxygen during deposition of the NiO thin film to induce formation of empty spaces in Ni.
Referring to
Li-doped NiOx is expressed by LiyNi1-yOx, wherein y indicates a Li doping content (concentration), d indicates a thickness, σ indicates conductivity, Ea indicates a bandgap, S indicates conductivity, p indicates a hole carrier concentration, μ indicates hole effect mobility, and T indicates transmittance in a visible light region in Table 2.
Referring to
While embodiments of this invention have been described in connection with what is presently considered to be practical example embodiments, it is to be understood that the embodiments of invention are not limited to the disclosed embodiments. On the contrary, they are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
The following reference identifiers may be used in connection with the drawings to describe various features of embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0101226 | Aug 2023 | KR | national |
