One-step formation of front ohmic and schottky contacts on SiC power devices using laser annealing

Abstract

Embodiments of the present disclosure relate to one-step formation of front ohmic and Schottky contacts on SiC power devices using laser annealing. Methods, systems, and apparatus are provided for forming ohmic and Schottky contacts for SiC power devices in one step using laser annealing. The SiC power device may include a backside ohmic contact, an n + substrate, an n-epitaxial layer, one or more p + regions, one or more carbon layers, one or more ohmic contacts, and a Schottky contact. One or more ohmic contacts, as well as Schottky contacts, may be formed in a one-step operation, which may include laser annealing. In fabricating the device, a metallization layer applied over the carbon layer and the n-epitaxial layer may form an ohmic contact and a Schottky contact when the anneal is performed.

Description

Technical Field

[0001] Example embodiments of the present disclosure relate generally to silicon carbide (SiC) power devices, and more particularly to SiC power devices having both ohmic contacts and Schottky contacts formed in one step. Background Art

[0002] Silicon carbide (SiC) power devices (such as SiC diodes) may include both ohmic contacts and Schottky contacts. Examples of SiC diodes include JBS (junction barrier Schottky) diodes and MPS (merged PN Schottky) diodes. In these SiC diodes, an ohmic contact may be formed below the Schottky contact. Conventional methods for forming ohmic contacts and Schottky contacts include multiple metallization layers requiring multiple steps. For example, some of these steps include the need for dedicated metal deposition (e.g., Ni) to form an ohmic contact on a p+ region, multiple steps associated with photolithography for metal definition, and a first annealing process performed at a temperature of nearly 1000°C. Subsequently, the formation of the Schottky contact requires a second metal deposition and another separate annealing process at a temperature of up to 500°C. These conventional manufacturing methods (including separate annealing processes to form ohmic contacts and Schottky contacts, respectively) increase process complexity and increase the probability of errors. In addition, they include multi-step photolithography processes, which increase manufacturing costs and the cost of the resulting power device.

[0003] The inventors have identified many areas of improvement in the prior art and technology, which are the subject of the embodiments described herein. Through effort, ingenuity, and innovation, many of these deficiencies, challenges, and problems have been addressed by developing solutions included in the disclosed embodiments, some examples of which are described in detail herein. Summary of the invention

[0004] Various embodiments described herein relate to improved one-step formation of Ohmic and Schottky contacts for SiC power devices. These Ohmic and Schottky contacts are located on the first side (front side) of the SiC power device and can be formed simultaneously using a single annealing operation.

[0005] According to some embodiments of the present disclosure, an example method for manufacturing a SiC power device is provided. The method may include: providing a wafer having a plurality of SiC layers, wherein the plurality of SiC layers include an n-epitaxial layer and one or more p+ regions, wherein the wafer has a first surface, the first surface including one or more surface regions of the n-epitaxial layer and one or more surface regions of the one or more p+ regions; applying a first laser to the first surface; in response to applying the first laser to the first surface, forming one or more carbon layers on the first surface, wherein each of the one or more carbon layers is formed on one or more surface regions of the one or more p+ regions; depositing a metallization layer on the first surface; annealing the wafer; and in response to annealing the wafer, forming one or more ohmic contacts and one or more Schottky contacts.

[0006] In some embodiments, annealing the wafer is performed by an annealing laser.

[0007] In some embodiments, the annealing laser has an energy density of less than 3 J / cm2.

[0008] In some embodiments, annealing the wafer is performed in an annealing furnace.

[0009] In some embodiments, applying the first laser to the first surface includes applying multiple scans of the first laser.

[0010] In some embodiments, applying the first laser to the first surface does not result in one or more carbon formations on the one or more surface regions of the n-epitaxial layer.

[0011] In some embodiments, the one or more p+ regions are arranged in one or more stripes.

[0012] In some embodiments, the one or more p+ regions are arranged in one or more cells.

[0013] In some embodiments, forming the one or more Ohmic contacts and the one or more Schottky contacts includes the one or more Ohmic contacts being positioned below the one or more Schottky contacts.

[0014] In some embodiments, the n-epitaxial layer includes 4H-SiC.

[0015] According to some embodiments of the present disclosure, an example SiC power device is provided. The SiC power device may include: a plurality of SiC layers, wherein the plurality of SiC layers include an n-epitaxial layer and one or more p+ regions; one or more carbon layers, wherein each of the one or more carbon layers is above one of the one or more p+ regions; one or more ohmic contacts, wherein each of the one or more ohmic contacts is associated with one of the one or more carbon layers and is above one of the one or more carbon layers; one or more Schottky contacts, wherein each of the one or more Schottky contacts is above the n-epitaxial layer and is associated with the n-epitaxial layer; and wherein the one or more ohmic contacts and the one or more Schottky contacts are formed simultaneously using annealing.

[0016] In some embodiments, the one or more carbon layers include graphite.

[0017] In some embodiments, each of the one or more carbon layers is aligned over an associated p+ region.

[0018] In some embodiments, there is no carbon layer over the n-epitaxial layer.

[0019] In some embodiments, the SiC power device further includes an n+ substrate in contact with the n- epitaxial layer.

[0020] In some embodiments, the N+ substrate includes 4H-SiC.

[0021] In some embodiments, the SiC power device further includes a backside ohmic contact to the n+ substrate.

[0022] In some embodiments, one or more Ohmic contacts are positioned below the Schottky contact.

[0023] In some embodiments, the n-epitaxial layer includes 4H-SiC.

[0024] In some embodiments, the p+ region includes doped 4H-SiC.

[0025] The above invention content is only used to summarize some example embodiments to provide a basic understanding of some aspects of the present disclosure. Therefore, it should be understood that the embodiments described above are merely examples and should not be interpreted as narrowing the scope or spirit of the present disclosure in any way. It should also be understood that in addition to the embodiments summarized here, the scope of the present disclosure also covers many potential embodiments, some of which will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Having thus generally described certain example embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0027] Figure 1 illustrates a first cross-sectional view of a block diagram of a first exemplary power device according to one or more embodiments of the present disclosure;

[0028] Figure 2A illustrates a first plan view of a block diagram of a first exemplary semiconductor wafer according to one or more embodiments of the present disclosure;

[0029] Figure 2B a second plan view illustrating a block diagram of a second exemplary semiconductor wafer according to one or more embodiments of the present disclosure;

[0030] FIG. 3A to FIG. 3D illustrates an example block diagram associated with operations for preparing a power device according to one or more embodiments of the present disclosure;

[0031] Figure 4 illustrates a graph associated with the formation of a carbon layer according to one or more embodiments of the present disclosure;

[0032] Figure 5A and Figure 5B illustrates a cross-sectional view associated with the formation of a carbon layer according to one or more embodiments of the present disclosure; and

[0033] Figure 6 An example flow chart of operations for forming ohmic contacts and Schottky contacts according to one or more embodiments of the present disclosure is illustrated. DETAILED DESCRIPTION

[0034] Some embodiments of the present disclosure will now be described more fully with reference to the accompanying drawings, in which some but not all embodiments of the present disclosure are shown. Indeed, various embodiments of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments described herein; rather, these embodiments are provided so that the present disclosure satisfies applicable legal requirements. The same reference numerals refer to the same elements throughout.

[0035] As used herein, the term "comprising" means including, but not limited to, and should be interpreted in the manner in which it is commonly used in a patent context. The use of broader terms such as "including," "comprising," and "having" should be understood to provide support for narrower terms such as "consisting of," "consisting essentially of," and "consisting essentially of."

[0036] Phrases such as "in various embodiments," "in one embodiment," "according to one embodiment," "in some embodiments," etc. generally mean that the specific feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure, and may be included in multiple embodiments of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0037] The word “example” or “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0038] If the specification states that a component or feature "may", "could", "might", "should", "will", "preferably", "likely", "usually", "optionally", "for example", "often", or "might" (or other such language) is included or has a property, the specific component or feature need not be included or have that property. In some embodiments, such a component or feature may be optionally included, or may be excluded.

[0039] Overview

[0040] Various embodiments of the present disclosure are directed to improving the one-step formation of Ohmic and Schottky contacts for SiC power devices by using annealing.

[0041] Various embodiments of SiC power devices may include diodes and rectifiers. For example, the SiC power device may be a junction barrier Schottky (JBS) diode or a merged PN Schottky (MPS) diode. The power devices of JBS or MPS are each a combination of different diodes, such as a Schottky diode and a PN diode in parallel. Fabrication of SiC power diodes (including JBS diodes and MPS diodes) includes forming both ohmic contacts and Schottky contacts.

[0042] Various embodiments of the present disclosure include forming an ohmic contact on an implanted p+ region and simultaneously forming a Schottky contact on an epitaxial layer that is not an implanted p+ region. The ohmic contact and the Schottky contact can be formed simultaneously in one step as described herein. The ohmic contact can be formed by a reaction between a metallization layer (e.g., Ni) and a carbon layer (e.g., graphite). A carbon layer can be formed on (multiple) p-implanted SiC regions by applying a laser with low laser energy. Forming a carbon layer using a laser allows the carbon layer to be aligned with the p-implanted region. This alignment can make the carbon layer directly on top of the p-implanted region, rather than being formed on an adjacent epitaxial layer while extending to the edge of the p-implanted region. The metallization layer can be deposited on the carbon layer and the surrounding epitaxial layer. Then, by applying an annealing operation (e.g., laser annealing), an ohmic contact and a Schottky contact can be formed in one step. The ohmic contact is formed just above the carbon layer, and the Schottky contact is formed above the epitaxial layer where the carbon layer is not present.

[0043] The present disclosure includes several advantages, including one metallization layer for forming both ohmic and Schottky contacts, lower annealing temperatures, and omitting photolithography operations for forming both ohmic and Schottky contacts.

[0044] Exemplary Systems and Apparatus

[0045] Embodiments of the present disclosure include systems and apparatuses in which Ohmic contacts and Schottky contacts for SiC power devices are formed in one step, such as by using a laser, which are described herein and can be implemented in various embodiments.

[0046] Figure 1 A first cross-sectional view of a block diagram of a first exemplary power device according to one or more embodiments of the present disclosure is illustrated. The power device 100 has a front side 102 and a back side 104 .

[0047] The power device 100 includes multiple layers and multiple regions. The power device 100 may include a backside ohmic contact 110, an n+ substrate 120, an n- epitaxial layer 130, one or more p+ regions 140 (e.g., 140A, 140B), one or more carbon layers 142 (e.g., 142A, 142B), one or more ohmic contacts 150 (e.g., 150A, 150B), and a Schottky contact 160. Therefore, the SiC power device has one or more ohmic contacts 150, and a Schottky contact 160. In various embodiments, the side of the SiC device 100 illustrated at the bottom of the figure is the backside, and the side of the SiC device 100 illustrated at the top of the figure is the frontside.

[0048] The p+ region 140 may be formed from the n-epitaxial layer 130 via implantation, which may dope the n-epitaxial layer 130 with a metal (e.g., aluminum) to form a doped p+ region 140. In various embodiments, multiple power devices 100 may be fabricated simultaneously on a wafer, and the p+ region may be formed in stripes or cells on the wafer, as will be further described herein.

[0049] In various embodiments, the n+ substrate may be a 4H-SiC substrate. The n-epitaxial layer 130 may be a 4H-SiC epitaxial layer. This n-epitaxial layer 130 may maintain a certain (multiple) breakdown voltages and control the doping of the p+ region 140. The p+ region 140 may be a p-doped 4H-SiC region.

[0050] The ohmic contact 150 may be formed over the p+ region 140. In particular, the carbon layer 142 may be formed over the p+ region 140, and the ohmic contact 150 may be formed from the carbon layer 142 during annealing. The ohmic contact 150 may be aligned with the associated p+ region 140 such that the ohmic contact 150 is directly over the carbon layer 142 and the p+ region without extending or overflowing onto adjacent portions of the n-epitaxial layer 130. Furthermore, such alignment of the ohmic contact 150 may include the ohmic contact being formed such that it reaches the lateral edge of the associated carbon layer 142 and the lateral edge of the associated p+ region 140. In various embodiments, if the ohmic contact 150 is misaligned (i.e., outside the p+ region 140 and overlapping the n-epitaxial layer 130), the device may perform poorly and may not be suitable for use. The alignment is due in part to the one-step formation of the ohmic contact and the Schottky contact described herein.

[0051] In various embodiments, multiple SiC power devices 100 may be fabricated on a wafer, and the wafer may have multiple p+ regions 140 formed from the n-epitaxial layer 130. The p+ regions 140 may be formed in different patterns. For example, the p+ regions may be formed in one or more strips and / or in one or more cells. These different patterns may be formed in different patterns. Figure 2A and Figure 2B is shown in the figure.

[0052] Figure 2A A first plan view of a block diagram of a first exemplary semiconductor wafer according to one or more embodiments of the present disclosure is illustrated. Figure 2A The plan view of FIG. 1 illustrates a top view of a wafer 200A having two strips 240A, 240B of p+ regions 140 on the n- epitaxial layer 130 .

[0053] Figure 2B A first plan view of a block diagram of a first exemplary semiconductor wafer according to one or more embodiments of the present disclosure is illustrated. Figure 2BThe plan view of FIG. 1 illustrates a top view of a wafer 200B having a plurality of p+ regions 140 of cells 240C- 240J on or in the n-epitaxial layer 130 .

[0054] It should be understood that although Figure 2A An example of two strips 240A, 240B is shown, and Figure 2B An example of eight cells 240C-240J is illustrated, but various embodiments may include wafers having more or fewer strips and / or cells.

[0055] FIG. 3A to FIG. 3D An example block diagram associated with operations for fabricating a power device according to one or more embodiments of the present disclosure is illustrated. In various embodiments, a power device 100 may be fabricated as described herein. FIG. 3A to FIG. 3D The examples illustrated in provide illustrations based on these operations.

[0056] Figure 3A A wafer 300A is illustrated that is provided with a backside ohmic contact 110, an n+ substrate 120, an n-epitaxial layer 130, and a plurality of p+ regions 140. In various embodiments, the present disclosure may be used to manufacture or form a plurality of diodes on a single wafer. A first surface 132, which is a topside surface, includes a first surface of a plurality of p+ regions 140 and a first surface of the n-epitaxial layer 130. A laser annealing operation may be performed on the first surface 132 as described herein to form or generate a carbon layer 142 above or on the p+ regions without forming a carbon layer above or on the n-epitaxial layer 130.

[0057] Figure 3B Wafer 300B is illustrated after a first anneal. The first anneal may be performed using a laser, and may form or generate a carbon layer 142 above or on the p+ region without forming a carbon layer above or on the n- epitaxial layer 130. As described herein, this may be achieved, among other aspects, by using an annealing laser having a power density that is higher than a first threshold and lower than a second threshold. The first threshold may be a power density that would form a carbon layer 142 on the p+ region. The second threshold may be a power density that would form a carbon layer on the n- epitaxial layer. The second threshold is greater than the first threshold. Using laser annealing that is higher than the first threshold and lower than the second threshold, a carbon layer 142 is formed only above the p+ region 140 without forming (multiple) carbon layers on the n- epitaxial layer 130. In various embodiments, this laser may be an excimer laser.

[0058] As a result of the laser annealing, carbon layer(s) 142 formed on or over p+ region(s) 140 are aligned with corresponding p+ region(s) 140. This alignment allows carbon layer 142 to be directly on or over p+ region 140 without overlapping or overflowing on or over n-epitaxial layer 130. This may be due to the fact that portions of p+ region 140 are formed into carbon layer 142. Furthermore, the formation of carbon layer(s) 142 allows first surface 132 to include the surface of n-epitaxial layer 130 as well as the surface of carbon layer 132B.

[0059] In various embodiments, the carbon layer 142 may be a carbon-induced-forming layer including 3C-SiC regions and / or 6H-SiC regions, as described herein.

[0060] Figure 3C Wafer 300C is illustrated having a metallization layer 362 deposited on first surface 132. In various embodiments, the metal of metallization layer 362 may be titanium or nickel. This metallization layer 362 may be deposited with a thickness associated with or based on the desired barrier for Schottky contact. This barrier height may also be based on the metal of metallization layer 362. The deposition of metallization layer 362 covers the exposed top side at surface 132 of n-epitaxial layer 130 and carbon layer 142.

[0061] The formation of the ohmic contact 150 is by a reaction between the metal of the metallization layer 362 and the carbon layer 142. The formation of the (multiple) Schottky contacts 160 is by a reaction between the metal of the metallization layer 362 and the n-epitaxial layer 130. The reaction is obtained by thermal annealing, such as by laser annealing or by using an oven. In various embodiments using laser annealing, the laser used can be an excimer laser.

[0062] Figure 3D The wafer 300D is illustrated after an annealing operation in which the ohmic contact 150 and the Schottky contact 160 are formed. The Schottky contact 160 covers the ohmic contact 150. The Schottky contact 160 and the ohmic contact 150 are simultaneously formed by the annealing process.

[0063] Figure 4 A graph associated with the formation of a carbon layer according to one or more embodiments of the present disclosure is illustrated. Graph 400 has the energy of the laser used to form the carbon layer on the x-axis, and the current on the y-axis. The current on the y-axis is measured for the conductivity of the first surface, and when carbon formation (e.g., graphite) is formed or induced on the surface, the current begins to conduct. When the current begins to flow, it indicates that carbon formation is occurring. Before (multiple) carbon layers are formed, the current is zero.

[0064] It takes almost twice as much energy to get carbon formation on areas without n-epitaxial layers (no implants). In various embodiments, this is because performing the implantation causes damage to the SiC crystal. This damage helps to grow the carbon layer at a lower energy density than in areas that were not implanted. In contrast, the energy to break the epitaxial covalent bonds is higher for areas that were not implanted.

[0065] The first line 410 is associated with a carbon layer formed on the p+ region, and the second line 420 is associated with a carbon layer formed on the n-epitaxial layer. The first line 410 begins to conduct or does not have zero current at an energy of 1.6 J. The second line 420 begins to conduct or does not have zero current at an energy greater than 3 J. As shown, the carbon layer formed on the p+ region is formed at an amount of energy density applied to the surface, which is lower than the amount of energy density when the carbon layer on the n-epitaxial layer is formed at line 420.

[0066] As shown in the figure, when a laser higher than 1.5J and lower than 3J is used, the laser annealing process will form a carbon layer only on the surface of the p+ region but will not form a carbon layer on the n- epitaxial layer.

[0067] This formation of the carbon layer only on the p+ region by the laser annealing process allows the formation of a carbon layer that is aligned with the p+ region without overlapping the n- epitaxial layer. In various embodiments, the alignment can be a perfect alignment to help the formation of the carbon layer be perfectly aligned over the p+ region. The alignment of the carbon layer allows for the formation of an improved ohmic contact. The ohmic contact behavior is primarily related to the formation of the carbon layer.

[0068] Using a laser annealing process to form the carbon layer, the laser annealing can be applied to the entire surface. This allows for a laser annealing process without the need for shielding or masking.

[0069] Figure 5A A cross-sectional view associated with the formation of a carbon layer according to one or more embodiments of the present disclosure is illustrated. The cross-sectional view includes a carbon layer 142, a silicon layer 548, a second layer 546, a first layer 544, and a p+ region 140. Figure 5A The cross-sectional view of shows layers formed in response to the application of laser light, such as during the operations described herein. Carbon layer 142 can cover silicon layer 548. Silicon layer 548 can cover second layer 546. Second layer can cover first layer 544. First layer can cover p+ region 140.

[0070] In various embodiments, the p+ region may include 4H—SiC. Applying laser to the p+ region may cause one or more bonds of the p+ 4H—SiC to break, which may form the first layer 544 , the second layer 546 , the silicon layer 548 , and the carbon layer 142 .

[0071] In various embodiments, the first layer 544 may include 6H-SiC and the second layer 548 may include 3C-SiC. The silicon layer 548 may include silicon. The carbon layer 142 may include graphite. In various embodiments, these layers may be within the first 50 nanometers of the p+ region 140.

[0072] It should be understood that Figure 5A The layers shown in the figure may not be Figure 5A The layers may include crystalline structures that can be rearranged when bonds are broken.

[0073] In various embodiments, the first layer 544 and the second layer 546 may be formed side by side rather than as Figure 5A As shown in the figure, they are formed on top and bottom of each other.

[0074] Figure 5B Illustrated are cross-sectional views associated with the formation of a carbon layer according to one or more embodiments of the present disclosure. Figure 5B In the exemplary embodiment Figure 5A A magnified image of the layer. Figure 5B As shown in FIG, the layers are not evenly separated.

[0075] It should be readily appreciated that the embodiments of the systems and apparatus described herein may be configured in various additional and alternative ways besides those explicitly described herein.

[0076] Exemplary Methods

[0077] Figure 6 An example flow chart of operations for forming ohmic contacts and Schottky contacts according to one or more embodiments of the present disclosure is illustrated.

[0078] At operation 602, a wafer having a plurality of SiC layers is provided, the plurality of SiC layers including an n-epitaxial layer and one or more p+ regions. In various embodiments, the plurality of SiC layers may include an n+ substrate 120 and an n-epitaxial layer 130. In various embodiments, one or more p+ regions 140 may be formed in strips (e.g., 240A, 240B) and / or in cells (e.g., 240C-240J). In various embodiments, the wafer may also include a backside ohmic contact 110. The wafer may have a first surface 132 as a topside surface. The first surface 132 may include one or more surface regions of the n-epitaxial layer 130 and one or more surface regions of the one or more p+ regions 140.

[0079] In various embodiments, only the n-epitaxial layer may be provided to the wafer, and doping may be performed to form the p+ region 140 before providing the wafer.

[0080] At operation 604, the first surface of the wafer may be laser annealed. The first surface 132 may be exposed and may be laser annealed. In various embodiments, the laser annealing may use an excimer laser.

[0081] In various embodiments, this laser annealing can be performed with a pulse duration of 160 ns. The laser annealing can have a pulse duration of 1 J / cm 2 With 3J / cm 2 The laser may be scanned once or more times to perform laser annealing. For example, 1 to 20 scans may be used. In other embodiments, the number of scans may vary with the energy density of the laser. The laser annealing of operation 604 is performed so that a carbon layer is not formed on the surface of the n-epitaxial layer 130.

[0082] At operation 606, one or more carbon layers are formed on the surface of the p+ region. The carbon layer 142 is formed on the p+ region 140 in response to the laser annealing. Thus, each of the one or more carbon layers 142 is uniquely associated with one or more surface regions of the one or more p+ regions 140 in which the corresponding carbon layer 140 is formed.

[0083] The carbon layer(s) 140 may be formed such that they are aligned with the corresponding p+ regions 140. This alignment may be due to the use of laser annealing in operation 604. The carbon layers 142 are aligned with the associated p+ regions 140 such that the carbon layers 142 do not overlap with the nearby n-epitaxial layers 130. The carbon layers 142 are formed or grown on the p+ regions 140. Thus, the first surface 132 now includes the n-epitaxial surface region 132A, and one or more surface regions of one or more carbon layers 132B.

[0084] At operation 608, a metallization layer is deposited on the first surface. The metal of the metallization layer 362 is deposited to cover the first surface 132, thereby covering the n-epitaxial surface region 132A and one or more surface regions of the one or more carbon layers 132B.

[0085] At operation 610 , a second anneal is performed. The second anneal forms one or more ohmic contacts 150 and one or more Schottky contacts 160 simultaneously.

[0086] In various embodiments, the second annealing may be performed at a moderate annealing temperature of 400° C. to 500° C.

[0087] In various embodiments, the second annealing may be performed using an annealing laser. The laser may be an excimer laser. In various embodiments, the second annealing may be performed in an oven.

[0088] At operation 612, ohmic contact(s) and Schottky contact(s) are formed. In response to the second annealing operation, one or more ohmic contacts 150 may be formed at the carbon layer 142, and Schottky contacts 160 may be formed at the n-epitaxial layer.

[0089] The second annealing operation creates an alloy that acts as an ohmic contact for the carbon layer 142. In various embodiments, the entire carbon layer 142 may not interact to form an ohmic contact, so some carbon layer 142 may remain.

[0090] It should be readily appreciated that the embodiments described herein may be configured in various additional and alternative ways, including adding or omitting one or more operations, in addition to those explicitly described herein.

[0091] in conclusion

[0092] The operation and / or function of the present disclosure has been described herein such as in a flow chart.It is understood that computer program instructions can be loaded onto a computer or other programmable device (e.g., hardware) to produce a machine so that the computer or other programmable device produced realizes the operation and / or function described in the flow chart frame herein.These computer program instructions can also be stored in a computer-readable memory, which can instruct a computer, a processor, or other programmable device to operate and / or function in a particular manner so that the instructions stored in the computer-readable memory produce a manufactured product, and the execution of the manufactured product realizes the operation and / or function described in the flow chart frame.The computer program instructions can also be loaded onto a computer, a processor, or other programmable device so that a series of operations are performed on a computer, a processor, or other programmable device to produce a computer-implemented process so that the instructions executed on a computer, a processor, or other programmable device provide for realizing the operation of the function and / or operation specified in the flow chart frame.The flow chart frame supports a combination of components for performing specified operations and / or functions, and a combination of operations and / or functions for performing specified operations and / or functions. It will be understood that one or more blocks in the flowchart, and combinations of blocks in the flowchart, can be implemented by a special purpose hardware-based computer system that performs specified operations and / or functions, or a combination of special purpose hardware and computer instructions.

[0093] Although this specification includes many specific embodiments and implementation details, these embodiments and implementation details should not be interpreted as limiting the scope of any disclosure or possible content to be protected, but should be interpreted as a description of the features specific to the specific embodiments of the specific disclosure. Certain features described herein in the context of a single embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. In addition, although the features may be described above as working in certain combinations and even initially claimed, in some cases, one or more features from the claimed combination may be cut out from the combination, and the claimed combination may be a variant for a sub-combination or a sub-combination.

[0094] Although the operations and / or functions are illustrated in a particular order in the figures, this should not be understood as requiring that such operations and / or functions be performed in the particular order or sequential order shown, or requiring that all illustrated operations be performed to achieve the desired result. In some cases, it may be advantageous to perform the operations and / or functions in an alternative order. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Therefore, although specific embodiments of the subject matter have been described, other embodiments are also within the scope of the appended claims.

[0095] Although this detailed description has set forth some embodiments of the invention, the appended claims cover other embodiments of the invention which differ from the described embodiments according to various modifications and improvements.

[0096] In the following claims, unless the specific terms "means for" or "step for" are used in a given claim, it is not intended that the claims be interpreted under 35 U.S.C. 112, paragraph 6.

Claims

1. A method for manufacturing a SiC power device, comprising: Providing a wafer having a plurality of SiC layers, wherein the plurality of SiC layers comprises an n-epitaxial layer and one or more p+ regions, wherein the wafer has a first surface, the first surface comprising one or more surface regions of the n-epitaxial layer and one or more surface regions of the one or more p+ regions; applying a first laser to the first surface; forming one or more carbon layers on the first surface in response to applying the first laser to the first surface, wherein each of the one or more carbon layers is formed on the one or more surface regions of the one or more p+ regions; depositing a metallization layer on the first surface; annealing the wafer; as well as In response to annealing the wafer, one or more Ohmic contacts and one or more Schottky contacts are formed.

2. The method of claim 1, wherein annealing the wafer is performed by an annealing laser. The method according to claim 2 , wherein the annealing laser has an energy density lower than 3 J / cm 2 . The method of claim 1 , wherein annealing the wafer is performed in an annealing furnace.

5. The method of claim 1, wherein applying the first laser to the first surface comprises: Multiple scans of the first laser are applied. 6 . The method of claim 1 , wherein applying the first laser to the first surface does not result in one or more carbon formations on the one or more surface regions of the n-epitaxial layer. The method of claim 1 , wherein the one or more p+ regions are arranged in one or more stripes. The method according to claim 1 , wherein the one or more p+ regions are arranged in one or more units.

9. The method of claim 1 , wherein forming the one or more Ohmic contacts and the one or more Schottky contacts comprises: The one or more Ohmic contacts are positioned below the one or more Schottky contacts.

10. The method of claim 1, wherein the n-epitaxial layer comprises 4H-SiC.

11. A SiC power device, comprising: a plurality of SiC layers, wherein the plurality of SiC layers comprises an n-epitaxial layer and one or more p+ regions; one or more carbon layers, wherein each of the one or more carbon layers is over one of the one or more p+ regions; one or more ohmic contacts, wherein each of the one or more ohmic contacts is associated with and over one of the one or more carbon layers; one or more Schottky contacts, wherein each of the one or more Schottky contacts is above and associated with the n-epitaxial layer; and Wherein the one or more Ohmic contacts and the one or more Schottky contacts have been formed simultaneously using annealing. 12 . The SiC power device of claim 11 , wherein the one or more carbon layers comprise graphite. 13 . The SiC power device of claim 11 , wherein each of the one or more carbon layers is aligned over an associated p+ region. The SiC power device of claim 11 , wherein there is no carbon layer over the n-epitaxial layer. 15 . The SiC power device according to claim 11 , further comprising an n+ substrate in contact with the n− epitaxial layer. The SiC power device according to claim 15 , wherein the N+ substrate comprises 4H-SiC. 17 . The SiC power device according to claim 15 , further comprising a backside ohmic contact in contact with the n+ substrate. 18 . The SiC power device of claim 11 , wherein the one or more Ohmic contacts are positioned below the Schottky contact.

19. The SiC power device of claim 11, wherein the n-epitaxial layer comprises 4H-SiC.

20. The SiC power device of claim 11, wherein the p+ region comprises doped 4H-SiC.

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