Silicon carbide single crystal wafers, crystals and manufacturing methods, semiconductor devices

Abstract

The present invention provides a silicon carbide single crystal wafer and a method for manufacturing the same, a silicon carbide crystal and a method for manufacturing the same, and a semiconductor device, wherein the surface of the silicon carbide single crystal wafer has an angle between its normal direction and the c-direction that is between 0 and 8 degrees, and the number of agglomerated dislocations on this silicon carbide single crystal wafer is 300 / cm 2 The agglomerated dislocations refer to dislocation agglomerates in which the distance between the geometric centers of any two etch pits obtained after molten KOH etching is less than 80 microns. Even in the case of a relatively high dislocation density, the agglomerated dislocation density is small, improving the yield of silicon carbide-based devices.

Description

Technical Field

[0001] [Cross-reference] This application claims priority based on a Chinese patent application with application number 2020113413474 and invention title "Silicon Carbide Single Crystal Wafer, Crystal and Manufacturing Method, Semiconductor Device", which was filed with the China Patent Office on November 25, 2020, and the entire content thereof is incorporated herein by reference.

[0002] The present invention relates to the technical field of semiconductor materials, and in particular, to silicon carbide single crystal wafers and manufacturing methods thereof, silicon carbide crystals and manufacturing methods thereof, and semiconductor devices.

Background Art

[0003] In the prior art, dislocations are one of the main defects of silicon carbide single crystal wafers; they have a great impact on the performance of silicon carbide devices. Currently, the dislocation density of commercially available products is still high. In recent years, with the progress of technology, the dislocation density has gradually decreased, but still cannot meet the requirements.

[0004] Furthermore, the inventor has found that even if the dislocation density of the wafer decreases, the device yield may not be improved, and the correlation between dislocations and device failures remains almost unknown.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above circumstances, the present invention provides a silicon carbide single crystal wafer and manufacturing method thereof, a silicon carbide crystal and manufacturing method thereof, and a semiconductor device to solve the problem that although the dislocation density has decreased in the prior art, the device yield has not been improved.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A silicon carbide single crystal wafer, wherein the surface of the silicon carbide single crystal wafer is a surface in which the angular range between its normal direction and the c direction is 0 to 8 degrees, including the endpoints;

[0008] The aggregated dislocation density on the silicon carbide single crystal wafer is 300 dislocations / cm³. 2 Less than;

[0009] Here, each The aggregated dislocations result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 80 microns. one This is dislocation aggregation.

[0010] Preferably, the agglomeration dislocation is an agglomeration helical dislocation;

[0011] The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints;

[0012] The aggregated helical dislocation density on the silicon carbide single crystal wafer is 20 dislocations / cm³. 2 Less than;

[0013] Here, each The aggregated helical dislocations result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the aforementioned helical dislocations is less than 80 microns. one This is dislocation aggregation.

[0014] Preferably, the agglomeration dislocation is an agglomeration helical dislocation;

[0015] The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints;

[0016] The aggregated helical dislocation density on the silicon carbide single crystal wafer is 5 dislocations / cm³. 2 Less than;

[0017] Here, each The aggregated helical dislocations result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the aforementioned helical dislocations is less than 60 microns. one This is dislocation aggregation.

[0018] Preferably, the agglomeration dislocation is an agglomeration basal plane dislocation;

[0019] The surface of the silicon carbide single crystal wafer has an angular range of 2 to 8 degrees between its normal direction and the c direction, including the endpoints;

[0020] The aggregated basal plane dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm³. 2 Less than;

[0021] Here, each The aggregated basal plane dislocations result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two etch pits corresponding to the basal plane dislocations is less than 40 microns. one This is dislocation aggregation.

[0022] Preferably, the agglomerative dislocation is an agglomerative edge dislocation;

[0023] The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints;

[0024] The aggregated edge dislocation density on the silicon carbide single crystal wafer is 200 dislocations / cm³. 2 Less than;

[0025] Here, each The aggregated edge dislocations appear as etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 60 microns. one This is dislocation aggregation.

[0026] Preferably, the agglomeration dislocation is an agglomeration complex dislocation;

[0027] The surface of the silicon carbide single crystal wafer has an angular range of 2 to 8 degrees between its normal direction and the c direction, including the endpoints;

[0028] The aggregated composite dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm³. 2 Less than;

[0029] Here, each The aggregated composite dislocations appear as etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two dislocation etch pits of different types is less than 60 microns. one This is dislocation aggregation.

[0030] The present invention further,

[0031] Pretreatment is performed by capping a crucible filled with silicon carbide raw material with a graphite lid without seed crystals;

[0032] Aggregation dislocation density range is 200 dislocations / cm³ 2 To provide a seed crystal that is less than [amount missing];

[0033] Replace the pre-treated graphite lid with the graphite lid containing the seed crystal and attach it to the pre-treated crucible;

[0034] Growing silicon carbide crystals;

[0035] The present invention provides a method for producing silicon carbide crystals, including in-situ annealing.

[0036] Preferably, the density of aggregated spiral dislocations in the seed crystal is in the range of 10 dislocations / cm³. 2 It is less than.

[0037] Preferably, the pretreatment is carried out by capping the crucible filled with the silicon carbide raw material with a graphite lid without seed crystals. Specifically,

[0038] the temperature range of the crucible is set to 2000°C to 2200°C, the pressure is set to less than 10 Pa, and continuous evacuation is performed with a vacuum pump, and

[0039] the pretreatment time includes being 1 hour to 10 hours.

[0040] Preferably, the growth of the silicon carbide crystal is specifically

[0041] using a graphite lid containing seed crystals with an aggregation dislocation density range of less than 200 pieces / cm 2 to grow silicon carbide crystals under growth conditions where the growth temperature range is 2200°C to 2300°C, the pressure range is 50 Pa to 4000 Pa, the temperature fluctuation is less than 2°C, and the pressure fluctuation is less than 0.2 Pa;

[0042] Furthermore, using a graphite lid containing seed crystals with an aggregation dislocation density range of less than 200 pieces / cm 2 to grow silicon carbide crystals under growth conditions where the growth temperature range is 2200°C to 2300°C, the pressure range is 50 Pa to 4000 Pa, the temperature fluctuation is less than 1°C, and the pressure fluctuation is less than 0.1 Pa;

[0043] Furthermore, using a graphite lid containing seed crystals with an aggregation dislocation density range of less than 200 pieces / cm 2 to grow silicon carbide crystals under growth conditions where the growth temperature range is 2200°C to 2300°C, the pressure range is 50 Pa to 4000 Pa, the temperature fluctuation is less than 0.5°C, and the pressure fluctuation is less than 0.05 Pa is included.

[0044] Preferably, the in-situ annealing is specifically

[0045] raising the temperature to a temperature 50°C to 200°C higher than the growth, increasing the pressure to higher than 20000 Pa, and performing annealing for 10 hours to 100 hours.

[0046] The present invention further provides silicon carbide crystals formed by manufacturing them using the manufacturing method described in any one of the above items.

[0047] Furthermore, the present invention provides a method for producing silicon carbide single crystal wafers, and includes the following:

[0048] To provide the silicon carbide crystals described above;

[0049] The silicon carbide crystal is cut, polished, and a silicon carbide single crystal wafer is obtained.

[0050] Furthermore, the present invention provides a semiconductor device manufactured and formed from a silicon carbide single crystal wafer as described in any one of the above items.

[0051] As can be seen from the above technical proposal, the surface of the silicon carbide single crystal wafer provided in the present invention is a surface in which the angle between its normal direction and the c direction is between 0 and 8 degrees, and the aggregated dislocation density on this silicon carbide single crystal wafer is 300 dislocations / cm³. 2 It is less than 1000 dislocations / cm². The aggregated dislocations refer to dislocation aggregates where the distance between the geometric centers of any two etch pits obtained after molten KOH etching is less than 80 microns. Furthermore, the aggregated dislocations can be defined as dislocation aggregates where the distance between the geometric centers of any two etch pits obtained after molten KOH etching is less than 50 microns. When the aggregated dislocation density is low, the dislocation density is not necessarily low, but it can effectively improve the yield of SiC-based devices. Furthermore, the surface of the silicon carbide single crystal wafer provided in the present invention is a surface where the angle between its normal direction and the c direction is between 0 and 8 degrees, and when the aggregated dislocation density on this silicon carbide single crystal wafer is less than a specific value, the dislocation density of the wafer is not necessarily very low at the same time, and is 1000 dislocations / cm². 2 Larger, and even 2000 pieces / cm 2 Larger, and even 4000 pieces / cm 2Larger. However, the dislocation density of the wafer still cannot be too high, as excessively high dislocations will cause some degree of dislocation aggregation. The dislocation density of the wafer of this invention is 10,000 dislocations / cm³. 2 It is less than.

[0052] The present invention further provides a method for manufacturing silicon carbide single crystal wafers having a lower aggregated dislocation density by limiting process conditions, without employing stringent process conditions to unilaterally reduce the dislocation density. This relatively simplifies the manufacturing method of silicon carbide wafers and reduces the technical difficulties in manufacturing silicon carbide single crystal wafers and semiconductor devices. [Brief explanation of the drawing]

[0053] To more clearly describe embodiments of the present invention or prior art, the drawings required for describing embodiments or prior art will be briefly described below. Clearly, the drawings described below are merely embodiments of the present invention, and those skilled in the art can obtain other drawings based on the provided drawings without any creative effort.

[0054] [Figure 1] This is a photograph of a silicon carbide wafer containing various types of dislocations provided in embodiments of the present invention, etched with molten KOH, under an optical microscope. [Figure 2] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 3] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 4] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 5] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 6]This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 7] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 8] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 9] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 10] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 11] This is a photograph of a silicon carbide wafer containing aggregated dislocations, as provided in an embodiment of the present invention, after being etched with molten KOH under an optical microscope. [Figure 12] This is a flowchart of a method for producing silicon carbide crystals provided in an embodiment of the present invention. [Figure 13] This is a schematic diagram of the structure of a growth chamber used to grow SiC crystals by physical vapor transport. [Modes for carrying out the invention]

[0055] As described in the background technology section, even though the dislocation density was significantly reduced in the prior art, the device yield still did not improve.

[0056] As a result of extensive research on silicon carbide dislocations, the inventors have found that dislocation aggregation is a significant factor affecting the quality of silicon carbide crystals, and that unilaterally reducing dislocation density is extremely difficult, making it impossible to effectively improve the quality of silicon carbide, particularly the yield of silicon carbide-based devices.

[0057] Based on this, the present invention provides a silicon carbide single crystal wafer, wherein the surface of the silicon carbide single crystal wafer is a surface in which the angular range between its normal direction and the c direction is 0 to 8 degrees, including the endpoint value.

[0058] The aggregated dislocation density on the silicon carbide single crystal wafer is 300 dislocations / cm³. 2 Less than 150 pieces / cm 2 Less than 70 pieces / cm², more preferably 70 pieces / cm² 2 Less than, more preferably 35 pieces / cm 2 Less than 10 pieces / cm 2 Less than, more preferably 5 pieces / cm 2 Less than 1 piece / cm 2 Less than, more preferably 0.5 pieces / cm 2 Less than 0.1 pieces / cm 2 It is less than.

[0059] Here, each The aggregated dislocations result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 80 microns. one This is dislocation aggregation. Furthermore, each The aforementioned aggregated dislocation is defined as an etch pit obtained after molten KOH etching, where the distance between the geometric centers of any two etch pits is less than 60 microns. one It can be defined as referring to dislocation aggregation.

[0060] The silicon carbide single crystal wafers having low dislocation aggregation provided in the present invention solve important factors that limit the quality of silicon carbide crystals, improving the yield of silicon carbide wafers and also improving the yield of silicon carbide-based devices.

[0061] The technical concepts in the embodiments of the present invention will be described clearly and completely below with reference to the drawings of the embodiments of the present invention, and it is clear that the embodiments described are only a part of the embodiments of the present invention, and not all embodiments. According to the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without creative effort are included within the scope of protection of the present invention.

[0062] The silicon carbide single crystal wafer provided in the embodiment of the present invention has an angular range of 0 to 8 degrees between its surface normal direction and the c direction, including the endpoint value, where the c direction refers to the direction perpendicular to the (0008) plane of the seed crystal (c-axis direction). The surface of the silicon carbide single crystal wafer in this embodiment is a surface with an angular range of 0 to 8 degrees between its normal direction and the c direction, and typically the above angle of the wafer is about 4 degrees or 0 degrees.

[0063] The aggregated dislocation density on the silicon carbide single crystal wafer provided in this embodiment is 300 dislocations / cm³. 2 It is less than; however, in the embodiments of the present invention, each Aggregated dislocations are exposed as etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two such etch pits is less than 80 microns. one It is defined as dislocation aggregation. That is, dislocations that aggregate when the distance between the geometric centers of two etch pits is less than 80 microns are defined as aggregated dislocations. However, the aggregated dislocation density on silicon carbide single crystal wafers provided in embodiments of the present invention is low.

[0064] It should be noted that agglomerated dislocations refer to the degree of dislocation aggregation, while agglomerated dislocation density refers to the number of agglomerated dislocations per unit area. Agglomerated dislocation density and dislocation density are two different concepts. In a unit area, the dislocation density may be high, but the agglomerated dislocation density may not be high. For example, in a unit area, the dislocation density may be high, but the distribution is relatively uniform, and there are almost no agglomerated dislocations as defined above, so the density of agglomerated dislocations is low. Similarly, in a unit area, the dislocation density may be low, but the agglomerated dislocation density may be high. For example, in a unit area, the dislocation density may be low, but multiple dislocations may be divided into multiple groups and aggregate to form agglomerated dislocations as defined above, and the density of agglomerated dislocations will be higher than in the case where there are almost no agglomerated dislocations.

[0065] In this embodiment, for the sake of explanation, the aggregation of two dislocations satisfying the above definition can also be defined as one dislocation cluster region; the aggregation of three dislocations is defined as 1.5 dislocation cluster regions. Furthermore, the number of dislocation cluster regions is the number of dislocations satisfying the dislocation aggregation conditions defined above divided by 2. The aggregated dislocation density is the total number of aggregated dislocations on the wafer divided by the wafer area. This is the aggregated dislocation density obtained. .

[0066] In this embodiment, the type of dislocation is not limited, nor is the type of dislocation in a single silicon carbide wafer limited. Silicon carbide wafers typically inevitably contain various types of dislocations, such as helical dislocations (TSDs), edge dislocations (TEDs), and basal plane dislocations (BPDs). Referring to Figure 1, a silicon carbide wafer contains multiple helical dislocations (TSDs), edge dislocations (TEDs), and basal plane dislocations (BPDs) simultaneously. The density of each dislocation differs.

[0067] On the other hand, in this embodiment, the individual dislocation densities of various types of dislocations are relatively low and not limited as long as they can meet the basic requirements of semiconductor devices. Based on this, the aggregated dislocation density on the silicon carbide single crystal wafer provided in this embodiment is 300 dislocations / cm³. 2 Less than; preferably 150 pieces / cm 2 Less than 70 pieces / cm², more preferably 70 pieces / cm² 2Less than, more preferably 35 pieces / cm 2 Less than 10 pieces / cm 2 It is less than [value]. Specifically, in this embodiment, specific examples of aggregated dislocation densities corresponding to various types of dislocations will be described below with reference to the drawings.

[0068] In this embodiment, the agglomeration dislocation may be an agglomeration helical dislocation; specifically, as shown in Figure 2, each The aggregated helical dislocations 20 appear as etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 80 microns. one This is dislocation aggregation.

[0069] Since dislocations are inherited from the seed crystal during its growth, most helical and edge dislocations are along the c-direction, and the intersections of the dislocation lines with the wafer surface enlarge after etching, becoming etch pits. When the seed crystal is grown at a small off-angle (angle between the normal to the surface of the silicon carbide single crystal wafer and the c-direction), the basic travel distance is small, and the 0-degree etch pits become more pronounced; on the other hand, basal plane dislocations move within the c-plane, and since the dislocation lines do not intersect the surface of the 0-degree wafer, they are etched at the off-angle surface. Thus, helical and edge dislocations themselves, as well as dislocation aggregates between them, are basically inherited, but dislocation aggregates related to basal plane dislocations are not usually inherited during growth. In the following embodiments of the present invention, helical and edge dislocations are etched from surfaces where the angle range with respect to the c-direction is 0 to 8 degrees (including endpoint values); for statistical convenience, basal plane dislocations are etched from surfaces where the angle range with respect to the c-direction is limited to 1 to 8 degrees (including endpoint values).

[0070] The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal and the c-direction, including the endpoints; and the aggregated helical dislocation density on the silicon carbide single crystal wafer is 20 dislocations / cm³. 2It is less than. In other embodiments of the present invention, in order to improve the performance of the silicon carbide wafer, dislocation aggregates in which the distance between the geometric centers of any two etch pits is less than 60 microns may be defined as aggregated helical dislocations. Or, more preferably, dislocation aggregates in which the distance between the geometric centers of any two etch pits is less than 40 microns may be defined as aggregated helical dislocations. On the other hand, the aggregated helical dislocation density is 10⁻¹ / cm³ 2 It can also be limited to less than 5 pieces / cm², and in other embodiments, more preferably 5 pieces / cm². 2 Less than 2 pieces / cm 2 Less than 1 piece / cm 2 Less than, or 0.5 pieces / cm 2 Less than 0.1 pieces / cm 2 It may be less than this. The lower the aggregated helical dislocation density, the worse the dislocation density becomes, so even with a high dislocation density, the product yield of silicon carbide-based devices can be further improved.

[0071] In another embodiment of the present invention, the agglomeration dislocation may be an agglomeration helical dislocation; specifically, as shown in Figure 3, each The aggregated helical dislocations 30 result in etch pits appearing on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 60 microns. one This is dislocation aggregation. The surface of the silicon carbide single crystal wafer has an off-angle range of 0 to 8 degrees in the c-direction, including the endpoints; and the aggregated helical dislocation density on the silicon carbide single crystal wafer is 10 dislocations / cm². 2 It is less than.

[0072] In another embodiment of the present invention, the agglomeration dislocation may be an agglomeration basal plane dislocation; specifically, as shown in Figure 4, each The aggregated basal plane dislocation 40 causes etch pits to appear on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 40 microns. oneThis is dislocation aggregation. As can be seen from Figure 4, basal dislocations have a smaller diameter or size than helical dislocations. Therefore, in this embodiment, dislocation aggregation in which the distance between the geometric centers of any two etch pits is less than 40 microns is defined as aggregated basal dislocations.

[0073] The surface of the silicon carbide single crystal wafer has an off-angle range of 2 to 8 degrees in the c-direction, including the endpoints; and the aggregate basal plane dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm². 2 It is less than 50 dislocations / cm³. Since there are more basal dislocations than helical dislocations, in this example the aggregated basal dislocation density is 50 dislocations / cm³. 2 It is limited to less than the aggregated helical dislocation density, but both have been verified by numerous experiments by the inventors and can improve the limiting conditions for silicon carbide yield.

[0074] In another embodiment of the present invention, to improve the performance of the silicon carbide wafer, dislocation aggregates where the distance between the geometric centers of any two etch pits is less than 30 microns may be defined as aggregated basal plane dislocations. Alternatively, more preferably, dislocation aggregates where the distance between the geometric centers of any two etch pits is less than 20 microns may be defined as aggregated basal plane dislocations. In this case, the aggregated basal plane dislocation density is 20 dislocations / cm³. 2 It may also be limited to less than 10 pieces / cm², and in other embodiments, more preferably 10 pieces / cm². 2 Less than 5 pieces / cm 2 Less than 2 pieces / cm 2 Less than, or 1 piece / cm 2 Less than 0.5 pieces / cm 2 It may be less than this. The smaller the dislocation density at the aggregated basal plane, the worse the dislocation density becomes, so even when the dislocation density is high, the yield of silicon carbide wafers can be further improved.

[0075] In another embodiment of the present invention, the aggregated dislocation may be an aggregated edge dislocation; specifically, as shown in Figure 5, eachThe aggregated edge dislocations 50 appear as etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 60 microns. one This is dislocation aggregation. As can be seen from Figure 5, edge dislocations have a smaller diameter or size than helical dislocations. Therefore, in this embodiment, dislocation aggregation in which the distance between the geometric centers of any two etch pits is less than 60 microns is defined as aggregated edge dislocations.

[0076] The surface of the silicon carbide single crystal wafer has an off-angle range of 0 to 8 degrees in the c-direction, including the endpoints; and the aggregated edge dislocation density on the silicon carbide single crystal wafer is 200 dislocations / cm². 2 It is less than 200 dislocations / cm³. Since there are more edge dislocations than helical dislocations, in this embodiment the aggregated edge dislocation density is 200 dislocations / cm³. 2 It is limited to less than the aggregated helical dislocation density, but both have been verified by numerous experiments by the inventors and can improve the limiting conditions for silicon carbide yield.

[0077] In another embodiment of the present invention, to improve the performance of the silicon carbide wafer, dislocation aggregates where the distance between the geometric centers of any two etch pits is less than 50 microns may be defined as aggregated edge dislocations. Alternatively, more preferably, dislocation aggregates where the distance between the geometric centers of any two etch pits is less than 40 microns may be defined as aggregated edge dislocations. Meanwhile, the aggregated edge dislocation density is 100 dislocations / cm³. 2 It may also be limited to less than 50 pieces / cm², and in other embodiments, more preferably 50 pieces / cm². 2 Less than 20 pieces / cm 2 Less than 10 pieces / cm 2 Less than 5 pieces / cm 2 Less than 1 piece / cm 2 It may be less than this. The smaller the aggregated edge dislocation density, the worse the dislocation density becomes, and even when the dislocation density is high, the yield of silicon carbide wafers can be further improved.

[0078] Furthermore, in silicon carbide single crystal wafers, various types of dislocations may form aggregated composite dislocations, and in this embodiment, aggregated dislocations may be aggregated composite dislocations; specifically, as shown in Figures 6 to 11, each The aggregated composite dislocation A is characterized by the appearance of etch pits on the surface of the silicon carbide wafer after molten KOH etching, and the geometric distance between the etch pits corresponding to the helical dislocation and the etch pits corresponding to any one edge dislocation is less than 60 microns. one This is dislocation aggregation. Of course, other embodiments may also include other composite dislocations such as dislocation aggregation where the distance between the geometric centers of the etch pit corresponding to a helical dislocation and the etch pit corresponding to any one basal dislocation is less than a certain micron, dislocation aggregation where the distance between the geometric centers of the etch pit corresponding to a basal dislocation and the etch pit corresponding to any one edge dislocation is less than a certain micron, or dislocation aggregation where the distance between the geometric centers of the etch pit corresponding to a helical dislocation and the etch pit corresponding to any one basal dislocation or the etch pit corresponding to any one edge dislocation is less than a certain micron; that is, aggregation of any two or more dislocations can also be called aggregated composite dislocation. This embodiment is not limited to this. In this embodiment, in Figures 6 to 11, aggregation of a helical dislocation and a basal dislocation is referred to as aggregated composite dislocation B, aggregation of a basal dislocation and an edge dislocation is referred to as aggregated composite dislocation C, and aggregation of the three dislocations of helical dislocation, edge dislocation and basal dislocation is referred to as D.

[0079] The surface of the silicon carbide single crystal wafer has an angular range of 2 to 8 degrees between its normal direction and the c direction, including the endpoints; and the aggregated composite dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm³. 2It is less than. In other embodiments of the present invention, in order to improve the performance of silicon carbide wafers, dislocation aggregates in which the distance between the geometric centers of an etch pit corresponding to a helical dislocation and an etch pit corresponding to any one edge dislocation is less than 50 microns can be defined as aggregated composite dislocations. Or, more preferably, dislocation aggregates in which the distance between the geometric centers of an etch pit corresponding to a helical dislocation and an etch pit corresponding to any one edge dislocation is less than 40 microns can be defined as aggregated composite dislocations. On the other hand, the aggregated composite dislocation density is 50 dislocations / cm³. 2 It can be limited to less than, and in other embodiments, more preferably 20 pieces / cm 2 Less than 10 pieces / cm 2 Less than 5 pieces / cm 2 Less than 2 pieces / cm 2 It may be less than this. The lower the aggregated dislocation density, the worse the dislocation density becomes, so a low dislocation density can further improve the yield of silicon carbide wafers.

[0080] The silicon carbide single crystal wafer provided in this invention has a surface where the angle between its normal direction and the c direction is between 0 and 8 degrees, and the number of aggregated dislocations on this silicon carbide single crystal wafer is 300 dislocations / cm². 2 It is less than, each The aforementioned aggregated dislocation is defined as an etch pit obtained after molten KOH etching, where the distance between the geometric centers of any two etch pits is less than 80 microns. one This refers to dislocation aggregation. When the dislocation density is low, the aggregated dislocation density also decreases, resulting in improved device yield.

[0081] Based on the silicon carbide wafer or single crystal substrate provided in the above embodiments, the present invention further provides a semiconductor device manufactured and formed using the silicon carbide wafer or single crystal substrate provided in the above embodiments, thereby improving the performance and yield of the corresponding semiconductor device by improving the yield of the silicon carbide wafer.

[0082] Furthermore, embodiments of the present invention further provide a method for producing silicon carbide crystals, referring to Figure 12, which is a flowchart of the method for producing silicon carbide crystals provided in embodiments of the present invention; the method for producing silicon carbide crystals includes:

[0083] S101: Pre-treatment is performed by capping a crucible filled with silicon carbide raw material with a graphite lid without seed crystals;

[0084] Furthermore, in the initial stages of silicon carbide growth, various defects such as carbon coatings and polytypoids occur at the extension interface. Through extensive research and analysis of these mechanisms, the inventors have discovered that aggregated helical dislocations are easily formed at the location of coating defects, and that polytypoid defects lead to aggregated basal plane dislocations, aggregated edge dislocations, and so on.

[0085] On the one hand, the inventors, through numerous tests and studies, proposed a method of pre-treating the crucible filled with raw materials together, using a high temperature of 2000°C to 2200°C, a pressure lower than 10 Pa, and keeping the vacuum on at all times, with a treatment time of 1 to 10 hours. On the other hand, the surface of the raw materials and impurities and volatile components in the crucible are treated, and the impurities are left to coat the crystal during initial growth, forming inclusions. On the other hand, the SiC raw material is carbonized, and under low pressure conditions, the sublimated silicon-rich components preferentially volatilize and are rapidly extracted by a vacuum pump, forming a uniform graphene or carbon layer on the surface of the SiC raw material. In this way, when growing directly using fresh silicon carbide raw materials, if the concentration of silicon-rich components is too high in the initial stage, silicon coating inclusions occur, avoiding the occurrence of agglomerative dislocations, especially agglomerative helical dislocations.

[0086] S102: Aggregation dislocation density range is 200 dislocations / cm³ 2 To provide a seed crystal that is less than [amount missing];

[0087] Since dislocations are inherited from the seed crystal, most helical and edge dislocations are along the c-direction, and the basic migration distance is small when the seed crystal is grown at a small off-angle. Because basal plane dislocations move within the C-plane, helical and edge dislocations themselves, as well as dislocation aggregation between them, are basically inherited, but dislocation aggregation related to basal plane dislocations fluctuates during growth.

[0088] Therefore, in this embodiment, in order to reduce the generation of dislocations, a seed crystal with a low dislocation aggregation density was selected, and the dislocation aggregation density range of the seed crystal was 200 dislocations / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 100 dislocations / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 50 dislocations / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 10 dislocations / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 5 dislocations / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 1 dislocation / cm³. 2 Furthermore, the seed crystal aggregation dislocation density range is less than 0.5 dislocations / cm³. 2 It is less than.

[0089] More selectively, the seed crystal aggregation spiral dislocation density range is 10 dislocations / cm². 2 Below this level, the seed crystal aggregation spiral dislocation density range is 5 dislocations / cm³. 2 Below this level, the seed crystal aggregation spiral dislocation density range is 1 dislocation / cm³. 2 Below this level, the seed crystal aggregation spiral dislocation density range is 0.5 dislocations / cm³. 2 It is less than.

[0090] S103: Replace the pre-treated graphite lid with the graphite lid containing the seed crystal and attach it to the pre-treated crucible;

[0091] After pre-treatment and removal from the furnace, the pre-treated crucible lid without a seed crystal is replaced with a lid fitted with a SiC seed crystal. The crucible is then reassembled, the furnace is attached, and the crystal is grown.

[0092] S104: Growing silicon carbide crystals;

[0093] During the growth process, it is necessary to control the temperature fluctuations to be less than 2°C and the pressure fluctuations to be less than 0.2 Pa to ensure that the pressure and temperature remain stable. This is to avoid the instability of the growth interface due to temperature fluctuations, which can lead to the occurrence of aggregated dislocations, especially aggregated basal plane dislocations, as basal plane dislocations are greatly affected by temperature fluctuations.

[0094] Specifically, to grow silicon carbide crystals, the aggregation dislocation density range is 200 dislocations / cm³. 2 By using a graphite lid containing a seed crystal of less than 100°C, silicon carbide crystals can be grown under growth conditions that control the growth temperature range to 2200°C to 2300°C, the pressure range to 50 Pa to 4000 Pa, the temperature fluctuation to less than 2°C, and the pressure fluctuation to less than 0.2 Pa.

[0095] Silicon carbide crystals are grown under selectively controlled growth conditions: growth temperature of 2300°C, pressure of 2000 Pa, temperature fluctuation of less than 2°C, and pressure fluctuation of less than 0.2 Pa.

[0096] S105: Annealing on the spot.

[0097] In this example, the temperature is raised to 50°C to 200°C above the crystal growth temperature, preferably 100°C to 150°C, the pressure is increased to more than 20,000 Pa, and annealing is performed for 10 to 100 hours, preferably 20 to 30 hours, after which the temperature is gradually lowered and cooled.

[0098] Numerous studies have shown that to effectively repair aggregated dislocations, particularly aggregated edge dislocations that promote dislocation migration, the crystal annealing temperature must be higher than the crystal growth temperature. Aggregated dislocations, due to their close proximity, may fuse and disappear after migration or migrate to crystal boundaries, potentially reducing dislocation aggregation. On the other hand, annealing at a temperature close to the crystal growth temperature stabilizes the dislocations at this temperature, making it difficult to effectively reduce dislocation aggregation. Conversely, if the temperature is too high, silicon carbide becomes more susceptible to sublimation and decomposition, even under higher pressures.

[0099] In this embodiment, the temperature is optionally increased to 50°C to 200°C higher than the growth temperature, the pressure is increased to more than 20,000 Pa, and annealing is performed for 10 to 100 hours.

[0100] Based on the same concept of the invention, embodiments of the present invention further provide silicon carbide crystals formed by the above method, and further include cutting, polishing, and forming a silicon carbide single crystal wafer after forming the silicon carbide crystals by the above method, wherein the silicon carbide single crystal wafer is a silicon carbide single crystal wafer having low dislocation aggregation.

[0101] In the embodiments of this invention, a method for producing low-aggregation dislocations is creatively proposed, and by controlling the pretreatment of raw materials and increasing the annealing temperature, the dislocation aggregation problem is effectively solved, product quality is improved, and silicon carbide single crystal substrate products with low aggregate dislocations are creatively developed.

[0102] To explain the effect of the silicon carbide wafer with low aggregation dislocations provided in the present invention, the following comparative tests are conducted.

[0103] In this embodiment, SiC crystals are grown by a physical vapor transport method, and as shown in Figure 13, this is a schematic diagram of the structure of a growth chamber for growing SiC crystals by a physical vapor transport method. This growth chamber includes a graphite lid 1, a graphite crucible 2, SiC raw material 3, a binder 4, a seed crystal 5, and a grown crystal 6.

[0104] Example 1 - A crucible filled with silicon carbide raw material was capped with a graphite lid without seed crystals and placed in a silicon carbide single crystal furnace at a high temperature of 2200 degrees Celsius, a pressure lower than 0.1 Pa, and with the vacuum pump constantly on. The processing time was 5 hours. After stopping the furnace and allowing it to cool, the crucible filled with silicon carbide raw material was removed and weighed. The weight decreased by 3%, indicating that silicon-rich components such as impurities on the surface of the raw material and crucible were effectively processed.

[0105] A seed crystal was selected from a 6-inch, 4-degree SiC sheet with a low density of aggregated dislocations, and the seed crystal was fixed to the lid. The graphite lid without the seed crystal was replaced, and the lid with the seed crystal was installed. After assembly, the furnace was reattached and growth was carried out at a temperature of 2300 degrees Celsius with a fluctuation of less than 1 degree Celsius, and a pressure of 2000 Pa with a fluctuation of less than 0.1 Pa. After growth was complete, the temperature was raised 180 degrees Celsius higher than the crystal growth temperature, the pressure was increased to 60,000 Pa, and annealing was performed for 50 hours, after which the temperature was gradually lowered to cool. The obtained crystal was cut and processed into a 6-inch, 350-micron thick SiC wafer, and KOH etching was performed to detect the number of various aggregated dislocations and calculate their density. The aggregated dislocation density was found to be 157 dislocations / cm³. 2 The aggregated spiral dislocation density is 1.3 dislocations / cm³. 2 The aggregated basal plane dislocation density is 3.5 dislocations / cm³. 2 The aggregated edge dislocation density is 48 dislocations / cm³. 2 The density of aggregated complex dislocation A is 3.2 particles / cm³. 2 This demonstrated that...

[0106] Comparative Example 1 - A crucible filled with silicon carbide raw material was grown using a conventional method and directly assembled with a lid containing a 4° 6-inch seed crystal; a furnace was then attached and growth was carried out at a temperature of 2300°C, with a maximum temperature fluctuation of 12°C during the long growth period, and a pressure of 2000 Pa, with a maximum pressure fluctuation of 8 Pa during the long growth period. After growth was complete, it was annealed at a constant temperature of 2300°C for 5 hours at a pressure of 60,000 Pa, and then cooled by gradually lowering the temperature. Finally, a 6-inch crystal was obtained, cut and processed into a 6-inch thick 350-micron wafer, and KOH etching was performed to detect the number of various aggregated dislocations and calculate their density, resulting in an aggregated dislocation density of 832 dislocations / cm³. 2 The aggregated spiral dislocation density is 23 dislocations / cm³. 2 The aggregated basal plane dislocation density is 68 dislocations / cm³. 2 The aggregated edge dislocation density is 366 dislocations / cm³. 2 The density of aggregated complex dislocation A is 82 particles / cm³. 2 This demonstrated that...

[0107] Next, 10 units each of the 6-inch products from Example 1 and Comparative Example 1 were used as tape-outs, epitaxials, and devices in the same batch. The results showed that the average yield of the devices from the batch of Example 1 was 19% higher than the yield of Comparative Example 1.

[0108] The present invention demonstrates that the product provided significantly improves the quality of silicon carbide single crystal products and offers significant technical advantages compared to prior art. Furthermore, it shows that using the device significantly improves device yield, increases output, and provides substantial economic value.

[0109] Furthermore, each example in this specification is described progressively, and each example focuses on the differences between the main points described and the other examples, and the same and similar parts between the examples should be referenced to one another.

[0110] In this specification, relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, the terms "includes," "incorporates," or any other variations thereof mean non-exclusive inclusion, such that an article or apparatus containing a set of elements includes not only those elements but also other elements not explicitly mentioned, or elements specific to such an article or apparatus. Unless otherwise specified, an element limited by the phrase "includes one of..." does not preclude the presence of other identical elements in an article or apparatus containing the aforementioned element.

[0111] The above description of the disclosed embodiments enables those skilled in the art to achieve or use the present invention. Various modifications to these embodiments are readily apparent to those skilled in the art, and the general principles defined herein can be achieved in other embodiments without departing from the spirit or scope of the invention. Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but rather to conform to the broadest scope that is consistent with the principles and novel features disclosed herein.

Claims

1. The surface of a silicon carbide single crystal wafer is a surface in which the angular range between its normal direction and the c direction is 0 to 8 degrees, including the endpoints; The dislocation density of the silicon carbide single crystal wafer is 2000 dislocations / cm³. ２ Larger, 10,000 pieces / cm ２ It is less than, The aggregated dislocation density on the silicon carbide single crystal wafer is 300 dislocations / cm³. ２ Less than; Herein, each aggregated dislocation is a single dislocation aggregate in which an etch pit appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits is less than 80 microns.

2. Agglomeration dislocations include agglomeration helical dislocations. The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints; The aggregated helical dislocation density on the silicon carbide single crystal wafer is 20 dislocations / cm². ２ Less than; The silicon carbide single crystal wafer according to claim 1, characterized in that each of the aggregated helical dislocations is a single dislocation aggregate in which an etch pit corresponding to the helical dislocation appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits corresponding to the helical dislocations is less than 80 microns.

3. Agglomeration dislocations include agglomeration helical dislocations. The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints; The aggregated helical dislocation density on the silicon carbide single crystal wafer is 5 dislocations / cm². ２ Less than; The silicon carbide single crystal wafer according to claim 2, characterized in that each of the aggregated helical dislocations is a single dislocation aggregate in which an etch pit corresponding to the helical dislocation appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits corresponding to the helical dislocations is less than 60 microns.

4. The aforementioned aggregated dislocation includes aggregated basal plane dislocations. The surface of the silicon carbide single crystal wafer has an angular range of 2 to 8 degrees between its normal direction and the c direction, including the endpoints; The aggregated basal plane dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm². ２ Less than; Hereinafter, each aggregated basal plane dislocation is a single dislocation aggregate in which an etch pit corresponding to the basal plane dislocation appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits corresponding to the basal plane dislocations is less than 40 microns, characterized in that the silicon carbide single crystal wafer according to claim 1.

5. A aggregated dislocation includes aggregated edge dislocations, The surface of the silicon carbide single crystal wafer has an angular range of 0 to 8 degrees between its normal direction and the c direction, including the endpoints. The density of aggregated edge dislocations on the silicon carbide single crystal wafer is 200 dislocations / cm³. ２ Less than; The silicon carbide single crystal wafer according to claim 1, characterized in that each aggregated edge dislocation is a single dislocation aggregate in which an etch pit corresponding to the edge dislocation appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two of the etch pits corresponding to the edge dislocations is less than 60 microns.

6. Agglomeration dislocations include agglomeration complex dislocations. The surface of the silicon carbide single crystal wafer has an angular range of 2 to 8 degrees between its normal direction and the c direction, including the endpoints; The aggregated composite dislocation density on the silicon carbide single crystal wafer is 50 dislocations / cm³. ２ Less than; The silicon carbide single crystal wafer according to claim 1, characterized in that each aggregated composite dislocation is a single dislocation aggregate in which an etch pit appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two dislocation etch pits of different types is less than 60 microns.

7. The crucible filled with silicon carbide raw material is pre-treated by capping it with a graphite lid without seed crystals. Select a seed crystal with an agglomeration dislocation density range of less than 200 / cm ２ and Here, each aggregated dislocation is a single dislocation aggregate in which an etch pit appears on the surface of the seed crystal after molten KOH etching, and the distance between the geometric centers of any two such etch pits is less than 80 microns. The pre-treated graphite lid is replaced with the graphite lid containing the seed crystal, and then attached to the pre-treated crucible. Growing silicon carbide crystals, Annealing on the spot Includes, The pretreatment process, specifically, involves capping a crucible filled with the aforementioned silicon carbide raw material with a graphite lid without seed crystals, Set the crucible temperature range to 2000°C to 2200°C, the pressure to less than 10 Pa, and continuously evacuate it with a vacuum pump, and The pretreatment time is 1 to 10 hours, A method for manufacturing silicon carbide crystals, characterized in that when a silicon carbide single crystal wafer is formed from annealed silicon carbide crystals, the surface has an angular range of 0 to 8 degrees between the surface normal direction and the c direction, including the endpoints, the dislocation density on the surface of the silicon carbide single crystal wafer is greater than 2000 dislocations / cm² and less than 10000 dislocations / cm², and the aggregated dislocation density is less than 300 dislocations / cm²; where each aggregated dislocation is a single dislocation aggregate in which an etch pit appears on the surface of the silicon carbide wafer after molten KOH etching, and the distance between the geometric centers of any two such etch pits is less than 80 microns.

8. The density range of aggregated spiral dislocations in the aforementioned seed crystal is 10 dislocations / cm². ２ A method for producing silicon carbide crystals according to claim 7, characterized in that the amount is less than [amount missing].

9. Growing the aforementioned silicon carbide crystals specifically involves, Aggregation dislocation density range is 200 dislocations / cm ２ A method for producing silicon carbide crystals according to claim 7, characterized in that it includes growing silicon carbide crystals using a graphite lid containing a seed crystal of less than 0.5 mm, under growth conditions in which the growth temperature range is controlled to 2200°C to 2300°C, the pressure range to 50 Pa to 4000 Pa, the temperature fluctuation to less than 2°C, and the pressure fluctuation to less than 0.2 Pa.

10. The aforementioned in-situ annealing specifically means, A method for producing silicon carbide crystals according to claim 7, characterized by comprising raising the temperature to 50°C to 200°C higher than the growth temperature, raising the pressure to more than 20,000 Pa, and performing annealing for 10 to 100 hours.

11. To provide silicon carbide crystals produced by the manufacturing method described in any one of claims 7 to 10; A method for manufacturing a silicon carbide single crystal wafer, characterized by cutting the silicon carbide crystal, polishing it, and obtaining a silicon carbide single crystal wafer according to any one of claims 1 to 6.

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