CN118098944A - Carbon-rich P-type ohmic contact structure based on silicon carbide and manufacturing method thereof - Google Patents
Carbon-rich P-type ohmic contact structure based on silicon carbide and manufacturing method thereof Download PDFInfo
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Abstract
The invention provides a carbon-rich P-type ohmic contact structure based on silicon carbide and a manufacturing method thereof, comprising the following steps: providing a P-type silicon carbide substrate; forming a carbon-rich structure on the upper surface of the P-type silicon carbide substrate; forming a metal layer on the upper surface of the P-type silicon carbide substrate, wherein the metal layer covers the carbon-rich structure; annealing is performed to react the metal layer with the carbon-rich structure to form an alloy layer, the alloy layer including a metal silicide, a metal carbide, and a graphite layer. According to the invention, the carbon-rich structure is formed between the P-type silicon carbide substrate and the metal layer to form the metal-carbon-silicon carbide structure, and the P-type silicon carbide ohmic contact is realized through the metal silicide annealing step, so that the temperature range in the whole manufacturing method is low, the manufacturing method is flexible, the degradation of the quality and reliability of oxide in the device structure caused by extremely high process temperature when ohmic contact is formed can be effectively avoided, and the performance stability and the use reliability of the device are improved.
Description
Technical Field
The invention belongs to the technical field of semiconductors, and relates to a carbon-rich P-type ohmic contact structure based on silicon carbide and a manufacturing method thereof.
Background
Because Silicon-based devices have approached the material performance limit in the semiconductor field, among many semiconductor materials, silicon Carbide (SiC) is used as a novel wide band gap semiconductor material, and has good physical and electrical properties as a semiconductor material inheriting new generation microelectronic devices and circuits after germanium, silicon and gallium arsenide, and the wide band gap of the SiC material enables the devices to work at quite high temperature and has the capability of emitting blue light; the high critical breakdown electric field determines that the device can be applied to high-voltage and high-power occasions; the high saturated electron drift velocity and the low dielectric constant determine that the device has excellent high-frequency and high-speed working performance; the high thermal conductivity means that the heat conduction performance is good, the integration level of a circuit can be greatly improved, and a cooling and radiating system is reduced, so that the volume of the whole machine is greatly reduced. In addition, the atomic bond energy in the SiC crystal is high, so that the SiC crystal has high electromagnetic wave impact resistance and radiation resistance, and the neutron resistance of the SiC device is at least 4 times that of the Si device. These superior characteristics of SiC make it attractive for applications in high temperature, high frequency, high power, radiation resistant semiconductor devices, and the like. However, there are still some problems in the implementation of the silicon carbide process at present, and the optimization of the high-performance ohmic contact process is an important research direction.
In the implementation process of SiC devices, low ohmic contact resistance is a basic condition that various semiconductor devices can stably operate, and is particularly true for silicon carbide field effect devices having wide application prospects in the fields of high temperature, high frequency and high power. In the conventional ohmic contact process for forming ohmic contacts, silicon carbide can be classified into N-type and P-type contacts according to semiconductor doping types, wherein N-type substrates are mostly nitrogen-doped silicon carbide, and nickel (Ni) -based alloy is deposited thereon; most of the P-type substrates are aluminum doped silicon carbide, and aluminum-containing alloy is deposited above the P-type substrates. The metal/SiC structure, when subjected to high temperature annealing (typically >900 ℃) reacts with the metal-SiC to form a new alloy and thus an ohmic contact. The high temperature requirements in the ohmic contact process may lead to potential risks, whether in diode or MOS transistor processes, where the ohmic contact is formed generally in the latter half of the overall process flow, and extremely high ohmic contact process temperatures may lead to degradation of quality and reliability of the oxide (including gate oxide and field oxide) and ultimately severely impact the performance of the silicon carbide device.
Therefore, how to provide a structure of carbon-rich P-type ohmic contact based on silicon carbide and a manufacturing method thereof to realize the preparation of good ohmic contact at a lower temperature is an important technical problem to be solved by those skilled in the art.
It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present application and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the application section.
Disclosure of Invention
In view of the above drawbacks of the prior art, the present invention is directed to a structure of a carbon-rich P-type ohmic contact based on silicon carbide and a method for manufacturing the same, which are used for solving the problem that the formation of ohmic contact needs to be performed at an extremely high temperature in the prior art, which may cause the degradation of the quality and reliability of oxide in a device, and further seriously affect the performance of the silicon carbide device.
To achieve the above and other related objects, the present invention provides a method for fabricating a silicon carbide-based carbon-rich P-type ohmic contact structure, comprising the steps of:
Providing a P-type silicon carbide substrate;
Forming a carbon-rich structure on the upper surface of the P-type silicon carbide substrate;
Forming a metal layer on the upper surface of the P-type silicon carbide substrate, wherein the metal layer covers the carbon-rich structure;
annealing is performed to react the metal layer with the carbon-rich structure to form an alloy layer, the alloy layer including a metal silicide, a metal carbide, and a graphite layer.
Optionally, the doping concentration range of the P-type silicon carbide substrate is 1×10 17cm-3～5×1019cm-3.
Optionally, the method for forming the P-type silicon carbide substrate comprises the following steps: providing an N-type silicon carbide substrate, and obtaining the P-type silicon carbide substrate based on the epitaxy of the N-type silicon carbide substrate; or carrying out ion implantation on a preset area of the N-type silicon carbide substrate to obtain the P-type silicon carbide substrate.
Optionally, the thickness of the carbon-rich structure ranges from 2nm to 15nm.
Optionally, the method for forming the carbon-rich structure includes at least one of a carbon ion implantation method, a vapor deposition method, a photoresist carbonization method, and a silicon element sublimation method.
Optionally, the vapor deposition method includes at least one of a magnetron sputtering method and a chemical vapor deposition method.
Optionally, the photoresist carbonization method comprises a photoresist homogenizing step and a carbonization annealing step, wherein the thickness range of the photoresist is 0.4-4 mu m, the carbonization annealing temperature range is 150-250 ℃, and the carbonization annealing time range is 60-180 min.
Optionally, the carbon ion implantation method includes forming a carbon-rich region on the surface of the P-type silicon carbide substrate, and then forming the carbon-rich structure through annealing activation.
Optionally, the sublimation method of silicon element includes sublimating silicon element on the surface of the P-type silicon carbide substrate at a preset temperature, and the carbon layer remained serves as the carbon-rich structure.
Optionally, the material of the metal layer includes Al, and at least one of Ni, ti, cu, and W.
Optionally, the annealing includes a first annealing step and a second annealing step, wherein the temperature of the second annealing step is higher than the temperature of the first annealing step.
Optionally, the temperature range of the first annealing step is 550-650 ℃, and the time range of the first annealing step is 30 s-10 min; the temperature range of the second annealing step is 650-900 ℃, and the time range of the second annealing step is 20 s-10 min.
The invention also provides a carbon-rich P-type ohmic contact structure based on silicon carbide, which comprises a P-type silicon carbide substrate and an alloy layer positioned on the upper surface of the P-type silicon carbide substrate, wherein the alloy layer comprises metal silicide, metal carbide and a graphite layer.
As described above, according to the structure of the carbon-rich P-type ohmic contact based on silicon carbide and the manufacturing method thereof, the carbon-rich structure is formed between the P-type silicon carbide substrate and the metal layer to form the metal-carbon-silicon carbide structure, and the P-type silicon carbide ohmic contact is realized through the metal silicidation annealing step, so that the temperature range in the whole manufacturing method is low, the manufacturing method is flexible, and the quality and reliability degradation of oxides (such as gate oxide and field oxide) in the device structure due to extremely high process temperature during ohmic contact formation can be effectively avoided, thereby improving the performance stability and the use reliability of the device.
Drawings
Fig. 1 is a flow chart showing the steps of a method for fabricating a silicon carbide-based carbon-rich P-type ohmic contact structure according to the present invention.
Fig. 2 is a schematic cross-sectional view of a structure obtained after performing step S1 in the first embodiment in the method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present invention.
Fig. 3 is a schematic cross-sectional view of a structure obtained after performing step S2 in the first embodiment in the method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present invention.
Fig. 4 is a schematic cross-sectional view of a structure obtained after performing step S3 in the first embodiment in the method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present invention.
Fig. 5 is a schematic cross-sectional view of a structure obtained after performing step S4 in the first embodiment in the method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present invention.
Fig. 6 is a schematic cross-sectional view of the structure obtained after step S2 is performed in the second to third embodiments in the method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present invention.
Description of element reference numerals
1P silicon carbide substrate
2N silicon carbide substrate
3. Carbon-rich structure
4. Metal layer
5. Alloy layer
S1 to S4 steps
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1 to 6. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
Example 1
The embodiment provides a method for manufacturing a carbon-rich P-type ohmic contact structure based on silicon carbide, referring to fig. 1, which is a step flow chart of the manufacturing method of the embodiment, and includes the following steps:
s1: providing a P-type silicon carbide substrate;
s2: forming a carbon-rich structure on the upper surface of the P-type silicon carbide substrate;
S3: forming a metal layer on the upper surface of the P-type silicon carbide substrate, wherein the metal layer covers the carbon-rich structure;
S4: annealing is performed to react the metal layer with the carbon-rich structure to form an alloy layer, the alloy layer including a metal silicide, a metal carbide, and a graphite layer.
First, step S1 is performed to provide a P-type silicon carbide substrate 1.
As an example, the doping concentration range of the P-type silicon carbide substrate 1 is 1×10 17cm-3～5×1019cm-3, and the doping concentration of the P-type silicon carbide substrate 1 includes, but is not limited to 5×1017cm-3、1×1018cm-3、5×1018cm-3、1×1019cm-3, in this embodiment, to implement ohmic contact, the P-type silicon carbide substrate 1 is heavily doped, that is, the doping concentration should be higher, so as to form a good ohmic contact.
As an example, the method of forming the P-type silicon carbide substrate 1 includes: providing an N-type silicon carbide substrate 2, and obtaining the P-type silicon carbide substrate 1 based on the epitaxy of the N-type silicon carbide substrate 2; or ion implantation is performed on a preset area of the N-type silicon carbide substrate 2 to obtain the P-type silicon carbide substrate 1. Referring to fig. 2, a schematic cross-sectional view of the P-type silicon carbide substrate 1 is shown after the P-type silicon carbide substrate 1 is formed according to the present embodiment, the P-type silicon carbide substrate 1 is formed by an ion implantation method, the ion implantation method can accurately control the doping depth, concentration and region by precisely controlling the ion implantation energy and dosage, shallow implantation can be performed, and the pattern size of the implantation region can be smaller due to small lateral diffusion of the implantation doping, which is beneficial to the integration level, and can be performed at a lower temperature. Of course, the P-type silicon carbide substrate 1 may be formed by epitaxial growth, and may be selected according to actual needs.
Step S2 is performed to form a carbon-rich structure 3 on the upper surface of the P-type silicon carbide substrate 1.
As an example, the method of forming the carbon-rich structure 3 includes at least one of a carbon ion implantation method, a vapor deposition method, a photoresist carbonization method, and a silicon element sublimation method. In this embodiment, the method for forming the carbon-rich structure 3 is a carbon ion implantation method, and please refer to fig. 3, which is a schematic cross-sectional view of the carbon-rich structure 3 formed by the carbon ion implantation method.
As an example, the carbon ion implantation method includes forming a carbon-rich region on the surface of the P-type silicon carbide substrate 1, and then forming the carbon-rich structure 3 through annealing activation. The method can be compatible with the whole device production process, and the annealing step of the carbon-rich region can be synchronously carried out with the subsequent activation annealing after other N-type and P-type injection. In addition, since the carbon ion implantation is a patterning process, the carbon-rich structure 3 can be formed on the upper surface of the P-type silicon carbide substrate 1, and an additional photolithography etching step is not required to remove the redundant carbon-rich structure outside the P-type silicon carbide substrate.
As an example, the carbon ion implantation method may select normal temperature implantation and high temperature implantation, and when the temperature is Wen Zhu, silicon oxide, silicon carbide, or the like is used as a hard mask, and a photoresist cannot be directly used to form a mask. In this embodiment, high-temperature implantation is adopted to obtain the carbon-rich structure 3 with less surface damage, which is favorable for reducing the specific contact resistance of ohmic contact, thereby improving the performance of the device.
As an example, the thickness of the carbon-rich structure 3 ranges from 2nm to 15nm, including but not limited to 6nm, 8nm, 10nm, 12nm, and the thickness of the carbon-rich structure 3 is reasonably adjusted based on the actual ohmic contact requirements.
Referring to fig. 4, step S3 is performed to form a metal layer 4 on the upper surface of the P-type silicon carbide substrate 1, where the metal layer 4 covers the carbon-rich structure 3.
As an example, the material of the metal layer 4 includes Al, and at least one of Ni, ti, cu, and W. The structure of the metal layer 4 includes at least one of a multi-layered metal stack structure and a single-layer alloy structure, and in an embodiment, the metal layer 4 is a single-layer NiAl structure.
Referring to fig. 5, step S4 is performed to anneal the metal layer 4 and the carbon-rich structure 3 to form an alloy layer 5, wherein the alloy layer 5 includes metal silicide, metal carbide and graphite layers.
As an example, the annealing includes a first annealing step and a second annealing step, wherein the second annealing step has a temperature higher than the first annealing step. In view of the carbon-rich structure 3 generated in step S3, the annealing temperature during annealing to form the alloy layer 5 can be significantly reduced compared with the annealing temperature and time in the conventional method, so that the heat in the whole process is reduced, and adverse effects of the high-temperature environment on other structures in the device are avoided.
As an example, the temperature range of the first annealing step is 550 to 650 ℃, and the time range of the first annealing step is 30s to 10min; the temperature range of the second annealing step is 650-900 ℃, and the time range of the second annealing step is 20 s-10 min. Wherein the temperature of the first annealing step comprises, but is not limited to, 580 ℃, 600 ℃, 620 ℃, and the time of the first annealing step comprises, but is not limited to, 1min, 2min, 5min, 8min; the temperature of the second annealing step includes but is not limited to 680 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, the time of the second annealing step includes but is not limited to 30s, 1min, 2min, 4min, 6min and 8min, and in practical application, the time and the temperature of the first annealing step and the second annealing step are reasonably set based on practical conditions.
Specifically, the first annealing step is performed to cause a preliminary melting reaction between the metal structure 4, the carbon-rich structure 3 and the P-type silicon carbide substrate 1 to form a silicide or carbide containing Ni/Ti/Cu, so that the carbon-rich structure 3 is uniformly distributed in the alloy structure. The second annealing step is performed to make the carbon in the carbon-rich structure 3 complete the morphological transformation, so that, in view of the fact that the carbon-rich structure 3 formed by the first three methods (carbon ion implantation, vapor deposition and photoresist carbonization) among the four methods for forming the carbon-rich structure 3 is cubic carbon or amorphous carbon (amorphous carbon layer), there is no additional contribution to the ohmic contact formation itself, and the P-shaped ohmic contact is only formed by transformation into a graphite layer (carbon with a lamellar structure, sp 2 is facilitated, and this transformation requires a relatively high temperature, and the annealing conditions (annealing temperature, annealing time, etc.) required for the subsequent steps are not the same, and need to be properly adjusted according to the selected scheme. In addition, the upper temperature limit of the second annealing step is higher, but it does not mean that the temperature must be reached to form an ohmic contact, but the higher the annealing temperature, the lower the specific contact resistance of the resulting ohmic contact. Commercial silicon carbide devices typically reach the order of 10 -5Ωcm2 to meet the demand, which means that the actual process can be temperature-adjusted according to the demand.
According to the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide, a carbon ion implantation method is adopted to form a carbon-rich structure between a P-type silicon carbide substrate and a metal layer to form a metal-carbon-silicon carbide structure, and then the P-type silicon carbide ohmic contact is realized through a metal silicide annealing step, so that the temperature range in the whole manufacturing method is low, the process steps can be compatible with the production process steps of the whole device, the process time is shortened, and the production efficiency is improved.
Example two
The present embodiment provides a method for manufacturing a silicon carbide-based carbon-rich P-type ohmic contact structure, which is different from the embodiment in that the method for forming the carbon-rich structure 3 in the present embodiment is a vapor deposition method.
Referring to fig. 1, a step flow chart of a method for fabricating a silicon carbide-based carbon-rich P-type ohmic contact structure according to the present embodiment is shown, and includes steps S1 to S4, wherein the method for forming the carbon-rich structure 3 in step S2 is a vapor deposition method, and referring to fig. 6, a schematic cross-sectional view of the carbon-rich structure 3 formed in step S2 by the vapor deposition method is shown.
As an example, the vapor deposition method includes at least one of a magnetron sputtering method and a chemical vapor deposition method. In this embodiment, the carbon-rich structure 3 is formed by chemical vapor deposition, and a mixed gas of CH 4 and He is used as a precursor, and the carbon-rich structure 3 is formed in a cavity environment of 380-450 ℃, 450-550W and 6 mTar-10 mTar, preferably 400 ℃,500W and 8mTar, and the thickness of the carbon-rich structure 3 is precisely controlled by the process time. Further, the carbon-rich structure 3 can be formed by ion-enhanced chemical vapor deposition, and the process steps are relatively simple and stable, and have high efficiency.
As an example, the vapor deposition method is used to form the carbon-rich structure 3 further includes a photolithography step, where the photolithography step is performed after the step of forming the carbon-rich structure 3, that is, after the step of forming the carbon-rich structure 3, a photolithography step is required to remove the carbon-rich structure 3 in other areas except the P-type silicon carbide substrate, so that the carbon-rich structure 3 only exists on the upper surface of the P-type silicon carbide substrate 1, and the etching method includes Ar ion physical etching or oxygen reaction etching.
According to the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide, the carbon-rich structure 3 is formed between the P-type silicon carbide substrate 1 and the metal layer 4 by adopting a vapor deposition method to form a metal-carbon-silicon carbide structure, the P-type silicon carbide ohmic contact is realized by a metal silicide annealing step, the temperature requirement in the whole manufacturing method is low, the process steps are simple and stable, and the manufacturing efficiency is high.
Example III
The difference between the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide and the first and second embodiments is that the method for forming the carbon-rich structure 3 in the present embodiment is a photoresist uniformity method.
Referring to fig. 1, a step flow chart of a method for manufacturing a silicon carbide-based carbon-rich P-type ohmic contact structure according to the present embodiment is shown, and includes steps S1 to S4, wherein a method for forming the carbon-rich structure 3 in step S2 is a photoresist uniformity method, and referring to fig. 6, a schematic cross-sectional view of the carbon-rich structure 3 formed in step S2 by using the photoresist uniformity method is shown.
As an example, the photoresist carbonization method includes a photoresist homogenizing step and a carbonization annealing step, wherein the thickness of the photoresist ranges from 0.4 μm to 4 μm, including but not limited to 0.5 μm, 0.8 μm, 1.0 μm, 2.0 μm, 2.5 μm, 3.5 μm; the carbonization annealing temperature ranges from 150 ℃ to 250 ℃, including but not limited to 180 ℃,200 ℃, 220 ℃; the carbonization annealing time ranges from 60min to 180min, including but not limited to 90min, 120min, 150min. The carbon-rich structure 3 is formed by adopting a photoresist carbonization method and mainly depends on photoresist carbonization, the types of the photoresist are not limited, and the thickness range is optimally 0.6-3 mu m. Taking AZ5214 type photoresist as an example, setting the rotating speed of the photoresist homogenizing process to 6000s -1, stopping photoresist homogenizing after the thickness of the photoresist reaches 1.50 mu m, and annealing the substrate coated with the photoresist at 180 ℃ for 120min to form the carbon-rich structure 3.
As an example, the formation of the carbon-rich structure 3 by using the photoresist carbonization method further includes a photolithography step, where the photolithography step is performed after the step of forming the carbon-rich structure 3, that is, after the step of forming the carbon-rich structure 3, a photolithography step is performed to remove the carbon-rich structure 3 in other areas except the P-type silicon carbide substrate, so that the carbon-rich structure 3 only exists on the upper surface of the P-type silicon carbide substrate 1, and the etching method includes Ar ion physical etching or oxygen reaction etching.
According to the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide, the carbon-rich structure 3 is formed between the P-type silicon carbide substrate 1 and the metal layer 4 by adopting a photoresist spin coating method to form a metal-carbon-silicon carbide structure, and the P-type silicon carbide ohmic contact is realized by a metal silicidation annealing step, so that the temperature range in the whole manufacturing method is low, the process step flow is simple, and the cost is low.
Example IV
The difference between the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide and the first, second and third embodiments is that the method for forming the carbon-rich structure 3 in this embodiment is a silicon element sublimation method.
Referring to fig. 1, a step flow chart of a method for fabricating a carbon-rich P-type ohmic contact structure based on silicon carbide according to the present embodiment is shown, and includes steps S1 to S4, wherein a method for forming the carbon-rich structure 3 in step S2 is a silicon element sublimation method, and referring to fig. 3, a schematic cross-sectional view of the silicon element sublimation method is shown after the carbon-rich structure 3 is formed in step S2.
As an example, the silicon element sublimation method includes sublimating silicon element on the surface of the P-type silicon carbide substrate 1 at a preset temperature, and the remaining carbon layer serves as the carbon-rich structure 3.
As an example, the temperature range of the elemental silicon sublimation method is 1100 ℃ to 1800 ℃, and the elemental silicon sublimation method is performed under Ar atmosphere conditions. According to the method, silicon elements on the surface of the P-type silicon carbide substrate 1 can be sublimated and separated from the P-type silicon carbide substrate 1 under the high temperature condition, so that only graphite structural carbon remains on the surface of the P-type silicon carbide substrate 1, the structural morphology of a substance is not required to be converted by subsequent annealing, and compared with other three schemes, the method is more beneficial to the conduction of a contact structure, the subsequent annealing can adopt lower temperature conditions, and the loss of device performance is not caused.
As an example, the formation of the carbon-rich structure 3 by using a silicon element sublimation method further includes a photolithography step, where the photolithography step is performed after the step of forming the carbon-rich structure 3, that is, after the step of forming the carbon-rich structure, a photolithography step is performed to remove the carbon-rich structure 3 in other areas except the P-type silicon carbide substrate, so that the carbon-rich structure 3 only exists on the upper surface of the P-type silicon carbide substrate 1, and the etching method includes Ar ion physical etching or oxygen reaction etching.
According to the manufacturing method of the carbon-rich P-type ohmic contact structure based on silicon carbide, a carbon-rich structure is formed between a P-type silicon carbide substrate and a metal layer by adopting a silicon element sublimation method to form a metal-carbon-silicon carbide structure, the P-type silicon carbide ohmic contact is realized through a metal silicidation annealing step, the temperature of the step of forming the carbon-rich structure in the whole manufacturing method is high, but the formed carbon-rich structure is in a graphite structure state directly, so that the conductivity of the ohmic contact structure is facilitated, the temperature of subsequent silicidation annealing is relatively low, and no obvious loss is caused to the performance of a device.
Example five
The present embodiment provides a carbon-rich P-type ohmic contact structure based on silicon carbide, which is manufactured by any one of the manufacturing methods of the first to fourth embodiments or other suitable methods, referring to fig. 6, which is a schematic cross-sectional view of the carbon-rich P-type ohmic contact structure based on silicon carbide of the present embodiment, and includes:
the invention also discloses a carbon-rich P-type ohmic contact structure based on silicon carbide, which is characterized in that: the silicon carbide substrate comprises a P-type silicon carbide substrate 1 and an alloy layer 5 positioned on the upper surface of the P-type silicon carbide substrate 1, wherein the alloy layer 5 comprises a metal silicide, a metal carbide and a graphite layer.
As an example, the method for forming the P-type silicon carbide substrate 1 includes at least one of an epitaxial growth method and an ion implantation method, the doping concentration range of the P-type silicon carbide substrate 1 is 1×10 17cm-3～5×1019cm-3, and the P-type silicon carbide substrate 1 is formed by the ion implantation method in this embodiment.
As an example, the forming step of the alloy layer 5 includes forming a carbon-rich structure 3 on the upper surface of the P-type silicon carbide substrate 1, forming a metal layer 4 on the P-type silicon carbide substrate 1, covering the carbon-rich structure 3 by the metal layer 4, and annealing the whole structure after forming the metal layer 4 so that the carbon-rich structure 3 and the metal layer 4 finally form the alloy layer 5. Specifically, the main components of the alloy layer 5 include a metal alloy and elemental carbon, wherein the metal alloy is a metal silicide or a metal carbide.
The carbon-rich P-type ohmic contact structure based on the silicon carbide has a higher-quality ohmic contact structure, and is beneficial to improving the performance and reliability of a device.
In summary, the preparation method of the carbon-rich P-type ohmic contact based on silicon carbide of the invention comprises the following steps: providing a P-type silicon carbide substrate; forming a carbon-rich structure on the upper surface of the P-type silicon carbide substrate; forming a metal layer on the upper surface of the P-type silicon carbide substrate, wherein the metal layer covers the carbon-rich structure; annealing is performed to react the metal layer with the carbon-rich structure to form an alloy layer, the alloy layer including a metal silicide, a metal carbide, and a graphite layer. According to the manufacturing method, the carbon-rich structure is formed between the P-type silicon carbide substrate and the metal layer to form the metal-carbon-silicon carbide structure, the P-type silicon carbide ohmic contact is realized through the metal silicide annealing step, the temperature range in the whole manufacturing method is low, the manufacturing method is flexible, the quality and reliability degradation of oxides (such as gate oxide and field oxide) in the device structure caused by extremely high process temperature when the ohmic contact is formed can be effectively avoided, and therefore the performance stability and the use reliability of the device are improved. The carbon-rich P-type ohmic contact structure based on the silicon carbide has a higher-quality ohmic contact structure, and is beneficial to improving the performance and reliability of devices. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (13)
1. The manufacturing method of the carbon-rich P-type ohmic contact structure based on the silicon carbide is characterized by comprising the following steps of:
Providing a P-type silicon carbide substrate;
Forming a carbon-rich structure on the upper surface of the P-type silicon carbide substrate;
Forming a metal layer on the upper surface of the P-type silicon carbide substrate, wherein the metal layer covers the carbon-rich structure;
annealing is performed to react the metal layer with the carbon-rich structure to form an alloy layer, the alloy layer including a metal silicide, a metal carbide, and a graphite layer.
2. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the doping concentration range of the P-type silicon carbide substrate is 1 multiplied by 10 17cm-3～5×1019cm-3.
3. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the method for forming the P-type silicon carbide substrate comprises the following steps: providing an N-type silicon carbide substrate, and obtaining the P-type silicon carbide substrate based on the epitaxy of the N-type silicon carbide substrate; or carrying out ion implantation on a preset area of the N-type silicon carbide substrate to obtain the P-type silicon carbide substrate.
4. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the thickness range of the carbon-rich structure is 2 nm-15 nm.
5. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the method for forming the carbon-rich structure comprises at least one of a carbon ion implantation method, a vapor deposition method, a photoresist carbonization method and a silicon element sublimation method.
6. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 5, wherein the method comprises the following steps: the vapor deposition method comprises at least one of a magnetron sputtering method and a chemical vapor deposition method.
7. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 5, wherein the method comprises the following steps: the photoresist carbonization method comprises a photoresist homogenizing step and a carbonization annealing step, wherein the thickness range of the photoresist is 0.4-4 mu m, the carbonization annealing temperature range is 150-250 ℃, and the carbonization annealing time range is 60-180 min.
8. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 5, wherein the method comprises the following steps: the carbon ion implantation method comprises the steps of forming a carbon-rich region on the surface of the P-type silicon carbide substrate, and then forming the carbon-rich structure through annealing activation.
9. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 5, wherein the method comprises the following steps: the silicon element sublimation method comprises the step of sublimating silicon element on the surface of the P-type silicon carbide substrate at a preset temperature, and the residual carbon layer is used as the carbon-rich structure.
10. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the material of the metal layer comprises Al and at least one of Ni, ti, cu and W.
11. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 1, wherein the method comprises the following steps: the annealing comprises a first annealing step and a second annealing step, wherein the temperature of the second annealing step is higher than that of the first annealing step.
12. The method for manufacturing the carbon-rich P-type ohmic contact structure based on silicon carbide according to claim 11, wherein the method comprises the following steps: the temperature range of the first annealing step is 550-650 ℃, and the time range of the first annealing step is 30 s-10 min; the temperature range of the second annealing step is 650-900 ℃, and the time range of the second annealing step is 20 s-10 min.
13. A carbon-rich P-type ohmic contact structure based on silicon carbide is characterized in that: the silicon carbide substrate comprises a P-type silicon carbide substrate and an alloy layer positioned on the upper surface of the P-type silicon carbide substrate, wherein the alloy layer comprises metal silicide, metal carbide and a graphite layer.
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