NITRIDE POWER TRANSISTOR AND MANUFACTURING METHOD THEREOF
A nitride power transistor comprises: a silicon substrate comprising a differently doped semiconductor composite structure for forming a space charge depletion region; and a nitride epitaxial layer located on the silicon substrate. With introduction of a differently doped semiconductor composite structure for forming a space charge depletion region inside a silicon substrate of a nitride power transistor, the nitride power transistor is capable of withstanding a relatively high external voltage, and thus a breakdown voltage of the device is improved.
This application is a continuation of International Patent Application No. PCT/CN2014/071352 filed on Jan. 24, 2014, which claims priority of Chinese Patent Application No. 201310482335.7 filed on Oct. 15, 2013, the contents of which are incorporated by reference herein in their entirety.
TECHNICAL FIELDThe present invention relates to microelectronics technology, in particular, relates to a nitride power transistor and a method of manufacturing the nitride power transistor.
BACKGROUNDAs the third-generation semiconductor material, Gallium Nitride (GaN) has become a hot research topic due to its features such as large band gap, high electron saturation velocity, high breakdown voltage and good thermal conductivity. In aspects of electrical devices, compared with silicon and gallium arsenide, gallium nitride material is more suitable to be used to manufacture electronic devices which are capable of withstanding high temperature, high frequency, high pressure and has high power, thus gallium nitride based electronic devices have broad application prospects.
In the past, gallium nitride power transistors were manufactured on sapphire substrates or silicon carbide substrates. Due to particularity and processing difficulty of gallium nitride heterojunction conductive channels, most gallium nitride power transistors have flat structures. Because of thick substrates and high breakdown voltages, the devices are usually broken down transversely. Some plane optimization techniques, such as using field plate structure and increasing the distance between a gate electrode and a drain electrode, can be used to increase the breakdown voltages of the devices, however, the materials used for sapphire substrates and silicon carbide substrates are expensive and difficult to manufacture substrates and epitaxial layers with large sizes, so the gallium nitride power transistors are costly and difficult to be commercialized.
At present, the technology of manufacturing gallium nitride power transistors on large-size silicon substrates is becoming mature and costs are lowering, which facilitates commercialization of gallium nitride power transistors. However, due to the electrical conductivity of the silicon materials and their low critical electric fields, every silicon-based gallium nitride power transistor has a saturation breakdown voltage, which is determined by the thickness of the nitride epitaxial layer grown on a silicon substrate. In addition, to avoid electrostatic discharge (ESD) caused by accumulation of static electricity in the devices and realize voltage matching in the circuits, it is necessary to ground the substrates, which reduces the breakdown voltage half when a substrate of a silicon-based gallium nitride power transistor is grounded. Therefore, improving breakdown voltage of the nitride power transistors on the silicon substrates is an urgent problem currently.
Therefore, in order to address the above-described technical issues, it is required to provide a nitride power transistor and a manufacturing method thereof.
SUMMARYIn view of this, an object of the present invention is to provide a nitride power transistor having a high breakdown voltage and a manufacturing method thereof. With introduction of longitudinal P-type doped semiconductor layers and N-type doped semiconductor layers inside a silicon substrate through epitaxial doping or ion implantation, a space charge region is formed inside the P-type doped semiconductor layers and the N-type doped semiconductor layers. Conductive electrons and holes inside the space charge region are completely exhausted so that conductive channels do not exist, similar to a high-resistance region, thus the nitride power transistor can withstand a certain external voltage. The bearable voltage of the space charge region depends on its height. The higher the space charge region is, the higher voltage it can withstand.
The space charge region formed by the P-type doped semiconductor layers and the N-type doped semiconductor layers introduced in the silicon substrate serves as a high-voltage-resistance layer inserted in the conductive silicon substrate, which improves the voltage resistance of the silicon substrate and hence improves the breakdown voltage of the whole device. Especially when the silicon substrate is grounded, the longitudinal breakdown voltage between the drain electrode and the substrate electrode is greatly increased.
To achieve the above object, a technical scheme according to an embodiment of the present invention is provided as follows.
A nitride power transistor comprises: a silicon substrate comprising a differently doped semiconductor composite structure for forming a space charge depletion region; and a nitride epitaxial layer located on the silicon substrate.
Preferably, the semiconductor composite structure is a multi-level structure formed by transversely alternating n-type semiconductor and p-type semiconductor.
Preferably, a longitudinal section of the semiconductor composite structure has one of a longitudinal vertical arrangement, a triangular arrangement and a square arrangement or any combination thereof, a cross section of the semiconductor composite structure has one of a longitudinal alternating grid arrangement, a longitudinal alternating triangular arrangement, a longitudinal alternating polygonal arrangement and a longitudinal alternating circular arrangement or any combination thereof, and the semiconductor composite structure occupies the entire silicon substrate in a transverse direction.
Preferably, a height of the n-type semiconductor and the p-type semiconductor of the semiconductor composite structure is more than 5 nm.
Preferably, doping concentration and doping distribution of each layer of the silicon substrate and the semiconductor composite structure in the silicon substrate includes light doping, graded doping, heavy doping or any combination thereof.
Preferably, the semiconductor composite structure is located at a top layer of the silicon substrate, in the middle of the silicon substrate, or at a bottom of the silicon substrate, or any combination thereof.
Preferably, semiconductor in the semiconductor doped multilayer structure is any one selected from silicon, germanium, germanium silicon, silicon carbide, III-V compound, or any combination thereof.
Preferably, the nitride power transistor further comprises a nitride epitaxial layer disposed on the nitride channel layer, two-dimensional electron gas is formed at an interface between the nitride epitaxial layer and the nitride barrier layer.
Preferably, the nitride power transistor further comprises a dielectric layer disposed on the nitride barrier layer, the dielectric layer includes one selected from SiN, SiO2, SiON, Al2O3, HfO2, HfAlOx and any combination thereof. The nitride power transistor further comprises a GaN capping layer disposed on the nitride barrier layer and/or an AlN insertion layer disposed between the nitride barrier layer and the nitride epitaxial layer.
Preferably, the nitride epitaxial layer comprises: a nitride nucleation layer located on the silicon substrate; a nitride buffer layer located on the nitride nucleation layer; and a nitride channel layer located on the nitride buffer layer. And the nitride power transistor further comprises a source electrode and a drain electrode contacting the nitride channel layer and a gate electrode located between the source electrode and the drain electrode.
Preferably, the nitride power transistor further comprises an AlGaN back barrier layer disposed between the nitride buffer layer and the nitride channel layer.
Preferably, regions of the nitride channel layer which are respectively located below the source electrode and the drain electrode are n-type heavily doped, and a region of the nitride channel layer which is located below the gate electrode is unintentionally doped, p-type lightly doped or n-type lightly doped.
Preferably, the nitride power transistor further comprises metal deposited at a bottom of the silicon substrate.
Corresponding, a method of manufacturing a nitride power transistor comprises: introducing a differently doped semiconductor composite structure for forming a space charge depletion region inside a silicon substrate; and growing a nitride epitaxial layer on the silicon substrate having the semiconductor composite structure.
Preferably, a manufacturing method of the semiconductor composite structure comprises etching and epitaxial growth, or ion implantation.
Preferably, the semiconductor composite structure is a multi-level structure formed by transversely alternating n-type semiconductor and p-type semiconductor.
Preferably, a longitudinal section of the semiconductor composite structure has one of a longitudinal vertical arrangement, a triangular arrangement and a square arrangement or any combination thereof, a cross section of the semiconductor composite structure has one of a longitudinal alternating grid arrangement, a longitudinal alternating triangular arrangement, a longitudinal alternating polygonal arrangement and a longitudinal alternating circular arrangement or any combination thereof, and the semiconductor composite structure occupies the entire silicon substrate in a transverse direction.
With introduction of a differently doped semiconductor composite structure for forming a space charge depletion region inside a silicon substrate of a nitride power transistor, the nitride power transistor is capable of withstanding a relatively high external voltage, and thus a breakdown voltage of the device is improved. Growing a GaN layer on the surface of the barrier layer as a protection layer can effectively decrease impact on the characteristics of the device by the surface defect and the surface state density of the barrier layer material. The AlN insertion layer increases the concentration of the two-dimensional electron gas, improves the mobility of electrons and the overall characteristics of the device. The AlGaN back barrier layer can separate the channel electrons from the buffer layer and effectively confine the two-dimensional electron gas in the channel layer, which avoids the short-channel effect and the current collapse effect.
In order to more clearly illustrate the technical schemes according to the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments of the present invention or the prior art will be introduced briefly. Apparently, the accompanying drawings described below illustrate only some of the embodiments of the present invention, other accompanying drawings can be obtained by those skilled in the art based on these accompanying drawings without creative efforts.
The present invention will be described in detail with reference to specific embodiments illustrated in the accompanying drawings. However, the present invention is not limited to the disclosed embodiments, rather, modifications on structures, methods or functions made by those skilled in the art based on the embodiments are included within the scope of the present invention.
Further, duplicate reference numerals or identifications may be used in different embodiments. These duplications are just for describing the present invention briefly and clearly, and do not mean that there is any association between different embodiments and/or structures.
Referring to
In the present embodiment, etching and epitaxially growing is used to form the differently doped semiconductor composite structure, in other embodiments, ion implantation may be used instead to form the differently doped semiconductor composite structure. The above-described semiconductor composite structure 10 is a multi-level structure formed by transversely alternating n-type semiconductor and p-type semiconductor. The semiconductor composite structure occupies the entire silicon substrate in the transverse direction. The semiconductor in the composite structure may be any one selected from silicon, germanium, germanium silicon, silicon carbide, III-V compound, or any combination thereof. The n-type semiconductor and the p-type semiconductor generally have a height of more than 5 nm. Doping concentration, doping distribution and the overall height of the differently doped semiconductor composite structure can be adjusted according to the required bearable voltage.
With a certain external voltage, each layer of doped semiconductor will be completely exhausted so as to form a space charge depletion region, and the whole differently doped semiconductor composite structure will form a thick space charge depletion region, as if a relatively thick high resistance region is inserted inside the silicon substrate, thus a relatively high external voltage can be withstood. With this method, the resistance to pressure of the silicon substrate is improved, and the breakdown voltage of the nitride power transistor is improved accordingly.
Further, on the basis of the present invention, an enhanced nitride power transistor device can be manufactured by changing the structure or manufacturing process of the nitride channel layer or the barrier layer on the silicon substrate, for example, by bombarding the material region below the gate metal with fluorine ions.
With the above-described embodiments, the nitride power transistor obtained by the method of manufacturing the nitride power transistor according to the present invention has the following advantageous effects.
With introduction of a differently doped semiconductor composite structure for forming a space charge depletion region inside a silicon substrate of a nitride power transistor, the nitride power transistor is capable of withstanding a relatively high external voltage, and thus a breakdown voltage of the device is improved. Growing a GaN layer on the surface of the barrier layer as a protection layer can effectively decrease impact on the characteristics of the device by the surface defect and the surface state density of the barrier layer material. The AlN insertion layer increases the concentration of the two-dimensional electron gas, improves the mobility of electrons and the overall characteristics of the device. The AlGaN back barrier layer can separate the channel electrons from the buffer layer and effectively confine the two-dimensional electron gas in the channel layer, which avoids the short-channel effect and the current collapse effect.
For those skilled in the art, apparently the present invention is not limited to the details of the above-described exemplary embodiments, rather, other implementations can be used to realize the present invention without departing from the spirit or essential characteristics of the present invention. Thus, in all cases the embodiments should be construed as exemplary, rather than limiting. The scope of the present invention is defined by the appended claims rather than the foregoing description, thus all modifications within meaning and range of the appended claims and equivalents thereof are included in the present invention. Any reference numeral in the claims should not be construed as limiting the claims.
Further, it should be understood that although the present specification is described with reference to embodiments, not each embodiment contains only one independent technical scheme. The specification is so described just for clarity. Those skilled in the art should regard the specification as a whole, technical schemes of various embodiments can be combined appropriately to form other implementations which can be understood by those skilled in the art.
Claims
1. A nitride power transistor, comprising:
- a silicon substrate comprising a differently doped semiconductor composite structure for forming a space charge depletion region; and
- a nitride epitaxial layer located on the silicon substrate.
2. The nitride power transistor according to claim 1, wherein the semiconductor composite structure is a multi-level structure formed by transversely alternating n-type semiconductor and p-type semiconductor.
3. The nitride power transistor according to claim 2, wherein a longitudinal section of the semiconductor composite structure has one of a longitudinal vertical arrangement, a triangular arrangement and a square arrangement or any combination thereof, a cross section of the semiconductor composite structure has one of a longitudinal alternating grid arrangement, a longitudinal alternating triangular arrangement, a longitudinal alternating polygonal arrangement and a longitudinal alternating circular arrangement or any combination thereof, and the semiconductor composite structure occupies the entire silicon substrate in a transverse direction.
4. The nitride power transistor according to claim 2, wherein a height of the n-type semiconductor and the p-type semiconductor of the semiconductor composite structure is more than 5 nm.
5. The nitride power transistor according to claim 2, wherein doping concentration and doping distribution of each layer of the silicon substrate and the semiconductor composite structure in the silicon substrate includes light doping, graded doping, heavy doping or any combination thereof.
6. The nitride power transistor according to claim 1, wherein the semiconductor composite structure is located at a top layer of the silicon substrate, in the middle of the silicon substrate, or at a bottom of the silicon substrate, or any combination thereof.
7. The nitride power transistor according to claim 1, wherein semiconductor in the semiconductor doped multilayer structure is any one selected from silicon, germanium, germanium silicon, silicon carbide, III-V compound, or any combination thereof.
8. The nitride power transistor according to claim 1, further comprising a nitride epitaxial layer disposed on the nitride channel layer,
- wherein two-dimensional electron gas is formed at an interface between the nitride epitaxial layer and the nitride barrier layer.
9. The nitride power transistor according to claim 8, further comprising a dielectric layer disposed on the nitride barrier layer,
- wherein the dielectric layer includes one selected from SiN, SiO2, SiON, Al2O3, HfO2, HfAlOx and any combination thereof.
10. The nitride power transistor according to claim 8, further comprising a GaN capping layer disposed on the nitride barrier layer.
11. The nitride power transistor according to claim 8, further comprising an AlN insertion layer disposed between the nitride barrier layer and the nitride epitaxial layer.
12. The nitride power transistor according to claim 1, wherein the nitride epitaxial layer comprises:
- a nitride nucleation layer located on the silicon substrate;
- a nitride buffer layer located on the nitride nucleation layer; and
- a nitride channel layer located on the nitride buffer layer, and
- wherein the nitride power transistor further comprises a source electrode and a drain electrode contacting the nitride channel layer and a gate electrode located between the source electrode and the drain electrode.
13. The nitride power transistor according to claim 12, further comprising an AlGaN back barrier layer disposed between the nitride buffer layer and the nitride channel layer.
14. The nitride power transistor according to claim 12, wherein regions of the nitride channel layer which are respectively located below the source electrode and the drain electrode are n-type heavily doped, and a region of the nitride channel layer which is located below the gate electrode is unintentionally doped, p-type lightly doped or n-type lightly doped.
15. The nitride power transistor according to claim 1, further comprising metal deposited at a bottom of the silicon substrate.
16. A method of manufacturing a nitride power transistor, comprising:
- introducing a differently doped semiconductor composite structure for forming a space charge depletion region inside a silicon substrate; and
- growing a nitride epitaxial layer on the silicon substrate having the semiconductor composite structure.
17. The method according to claim 16, wherein a manufacturing method of the semiconductor composite structure comprises etching and epitaxial growth.
18. The method according to claim 16, wherein a manufacturing method of the semiconductor composite structure comprises ion implantation.
19. The method according to claim 16, wherein the semiconductor composite structure is a multi-level structure formed by transversely alternating n-type semiconductor and p-type semiconductor.
20. The method according to claim 16, wherein a longitudinal section of the semiconductor composite structure has one of a longitudinal vertical arrangement, a triangular arrangement and a square arrangement or any combination thereof, a cross section of the semiconductor composite structure has one of a longitudinal alternating grid arrangement, a longitudinal alternating triangular arrangement, a longitudinal alternating polygonal arrangement and a longitudinal alternating circular arrangement or any combination thereof, and the semiconductor composite structure occupies the entire silicon substrate in a transverse direction.
Type: Application
Filed: Apr 15, 2016
Publication Date: Aug 11, 2016
Inventor: Kai CHENG (Suzhou)
Application Number: 15/099,662