Wafer

Abstract

To provide a wafer having preferable quality.SOLUTION: A wafer includes a wafer body, a diameter of the wafer body is greater than or equal to 150 mm, a basal plane dislocation of the wafer body is less than or equal to 1000 ea / cm2, and a bar stacking fault of the wafer body is less than or equal to 100 ea / wf.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a crystal growth method and a wafer, and more particularly to a crystal growth method capable of forming a crystal having a large thickness, a large size, and good quality, and a wafer having good quality. [Background technology]

[0002] In the process of crystal formation in the traditional crystal growth method, the crystal in the temperature field of the crystal growth furnace is prone to temperature differences at different positions on the crystal. For example, the temperature difference between the top and bottom faces of the crystal can be as much as 100 degrees. The problem of uneven temperature between both ends of the crystal will cause a large stress difference between the two ends of the crystal, which will affect the thickness, size and quality of the crystal. Summary of the Invention [Problem to be solved by the invention]

[0003] The ingots obtained after processing the crystals formed by the conventional crystal growth methods are thin, difficult to manufacture in large sizes, and of poor quality. Furthermore, the wafers obtained after cutting, grinding, and polishing the ingots are also of poor quality. [Means for solving the problem]

[0004] The present invention provides a crystal growth method that reduces the stress difference between both ends of the crystal, thereby allowing the crystal to have increased thickness, size, and improved quality.

[0005] The present invention provides wafers with favorable quality.

[0006] The crystal growth method of the present invention includes providing a seed crystal in a crystal growth furnace and forming a crystal on the seed crystal along a first direction after a plurality of time points, the crystal including a plurality of sub-crystals stacked along the first direction, where at each time point a corresponding one of the sub-crystals is formed, the sub-crystals including a plurality of end faces remote from the seed crystal, where the maximum temperature difference between any two of the end faces is 20 degrees or less.

[0007] In one embodiment of the invention, the difference in maximum temperature between any two of the end faces is 15 degrees or less.

[0008] In one embodiment of the invention, the difference value of the maximum temperatures of at least two of the end faces is less than or equal to 10 degrees.

[0009] In one embodiment of the invention, the difference value of the maximum temperatures of at least two of the end faces is less than or equal to 5 degrees.

[0010] In one embodiment of the invention, the difference value of the maximum temperatures of at least two of the end faces is less than or equal to 2 degrees.

[0011] In one embodiment of the invention, each end surface includes a center and an edge, and the difference in temperature between the center and the edge is 20 degrees or less.

[0012] The wafer of the present invention includes a wafer body, the diameter of the wafer body being 150 mm or more, and the basal plane dislocations of the wafer body being 1000 ea / cm 2 and the bar stacking faults in the wafer body are less than 100 ea / wf.

[0013] In one embodiment of the present invention, the basal plane dislocations in the wafer body are less than 500 ea / cm 2 , 300ea / cm 2 , or 200 ea / cm 2 The following is the result.

[0014] In one embodiment of the invention, the bar stacking faults in the wafer body are less than or equal to 50 ea / wf, 30 ea / wf, or 10 ea / wf.

[0015] In one embodiment of the invention, the wafer body bow is between plus or minus 15 μm, plus or minus 30 μm, or plus or minus 50 μm.

[0016] In one embodiment of the present invention, the warp of the wafer body is 50 μm or less, 30 μm or less, or 10 μm or less. Effect of the Invention

[0017] As described above, the crystal growth method of the present invention places a seed crystal in a crystal growth furnace to obtain a corresponding sub-crystal at each time point after the time point. The maximum temperature difference between any two end faces of the sub-crystal is 20 degrees or less. With such a design, a crystal having a large thickness, a large size, and good quality can be formed. Also, the wafer of the present invention has good quality. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a crystal-growing furnace system according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of crystals formed according to one embodiment of the present invention. [Diagram 3] 3 is a schematic diagram showing the relationship between temperature at the end face of the crystal of FIG. 2 and radial position of the crystal at multiple points in time. [Figure 4A] FIG. 2 is a schematic diagram showing the relationship between temperature at the end face of a crystal formed in a conventional fixed crystal growing furnace and crystal radial position at multiple points in time. [Figure 4B] FIG. 1 is a schematic diagram showing the relationship between temperature at the end face of a crystal formed in a conventional mobile crystal-growing furnace and crystal radial position at multiple points in time. [Diagram 5] 3 is an ingot of the crystal of FIG. 2 after spheroidization treatment. [Figure 6] 6 is a wafer of the ingot of FIG. 5 after cutting, grinding and polishing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] FIG. 1 is a schematic diagram of a crystal-growing furnace system according to one embodiment of the present invention. Referring to FIG. 1, the crystal-growing furnace system 100 includes an external heating module 110, a furnace 120, a first driving device 130, a second driving device 140, and a control device 150. The external heating module 110 is electrically connected to a power source 10. The furnace 120 is movably disposed in the external heating module 110 and connected to a gas cylinder 50 by a gas tube. The first driving device 130 drives the furnace 120 to move along an axis A1. The second driving device 140 rotates the furnace 120 about the axis A1. The control device 150 is electrically connected to the first driving device 130, the second driving device 140, the external heating module 110, the power source 10, and the thermometer 40.

[0020] The control device 150 controls the first drive device 130 and the second drive device 140 to operate simultaneously or not simultaneously, so that the furnace 120 moves and / or rotates within the external heating module 110. For example, the furnace 120 can first move up and down, then rotate at the same height, and finally move up and down while rotating at the same time.

[0021] Therefore, compared with the external heating module of a conventional movable crystal growing furnace, which can only move up and down relative to the furnace, the furnace 120 of the crystal growing furnace system 100 can not only move up and down relative to the external heating module 110, but also rotate relative to the external heating module 110, so that the crystal growing furnace system 100 can control the movement and rotation to operate simultaneously or not simultaneously. With such a design, the furnace 120 can be heated more uniformly, and thus the crystal 200 can be heated more uniformly to obtain a thicker crystal 200 with improved quality.

[0022] The external heating module 110 is also a group of heating coils, which cover the range of movement of the furnace 120 moving along the axis A1.

[0023] Meanwhile, the first driving device 130 drives the furnace 120 to move along the axis A1 with a maximum movement distance of 200 mm or less, a minimum movement distance of 0.1 μm or more, and a movement speed between 0.05 mm / hour and 100 mm / minute. Also, the second driving device 140 drives the furnace 120 to rotate about the axis A1 with a maximum rotation speed of less than 20 rpm and a minimum adjustable rotation speed of 0.01 rpm or more.

[0024] As shown in FIG. 1, the crystal growth furnace system 100 further includes an insulating layer 160 for covering the furnace 120 and maintaining the temperature of the furnace 120 in cooperation with the furnace 120, thereby preventing the temperature difference of the furnace 120 from becoming too large. Meanwhile, the crystal growth furnace system 100 further includes a weighing scale 170 located below the furnace 120 to measure the total weight of the furnace 120, the insulating layer 160, the crystal 200, and the silicon carbide raw material 20. With this design, the weight loss of the evaporated silicon carbide raw material 20 can be detected. The maximum load that the weighing scale 170 can withstand is 3 kg or more, for example, 5 kg or 10 kg, and the minimum weight loss rate that can be solved by the weighing scale 170 is 0.1 g / hour or more.

[0025] 1 , when the crystal-growing furnace system 100 is used to carry out the crystal growing method for forming a crystal 200, the furnace 120 of the crystal-growing furnace system 100 is filled with silicon carbide feedstock 20, and a seed crystal 30 is provided on the inner top wall of the furnace 120. After a period of time, a crystal 200 can be formed below the seed crystal 30.

[0026] FIG. 2 is a schematic diagram of a crystal formed according to one embodiment of the present invention. Referring to FIG. 2, a seed crystal 30 forms a crystal 200 along a first direction F1 after multiple time points. The crystal 200 includes multiple sub-crystals 210a-210l stacked along the first direction F1. Corresponding sub-crystals 210a-210l are formed at each time point. In this embodiment, the number of sub-crystals 210a-210l is 12, and the interval between the time points is 10 hours, but the number and interval are not limited thereto. The number of sub-crystals may be 20, and the time interval may be 10 hours. In other embodiments, the number of sub-crystals may be 10, and the time interval may be 5 hours, which can be adjusted according to the manufacturing design, so the present invention is not limited thereto. The sub-crystals 210a-210l include multiple end faces 220a-220l away from the seed crystal 30. Specifically, the end faces 220a-220l are the interfaces between the solid, i.e., the crystal 200, and the gas during the sublimation process. The center O1 of each end face 220a-220l is located at the intersection of the first direction F1 corresponding to the end face 220a-220l, respectively. It should be noted that FIG. 2 is only one embodiment. In other embodiments, the size of the sub-crystals 210a-210l from the center O1 to the maximum crystal radial position O2 may be the same or different, and the present invention is not limited thereto.

[0027] 3 is a schematic diagram showing the relationship between the temperature of the end face of the crystal 200 of FIG. 2 and the crystal radial position at multiple time points. As shown in FIG. 3, each line represents the temperature measured at the sub-crystals 210a-210l stacked along the first direction F1 and each end face 220a-220l of the sub-crystals 210a-210l, the crystal radial position 0 mm on the horizontal axis represents the center O1 of each end face 220a-220l, and the remaining crystal radial positions are the distances from the center O1 of the end face 220a-220l along the radial direction R1 to the center O1. It should be noted that the process of the seed crystal 30 forming the crystal 200 after the time points can include growing along the first direction F1 and the radial direction R1, but the present invention is not limited thereto.

[0028] In the temperature curves of the end faces 220a to 220l, when comparing the temperature differences of the end faces 220a to 220l, that is, from the center O1 of the end faces 220a to 220l to the maximum crystal radial position O2, the end face 220a has the smallest temperature difference, which is about 3 to 5 degrees. The end face 220l has the largest temperature difference, which is about 10 to 15 degrees. On the other hand, when comparing the temperature differences of the end faces 220a to 220l at the same crystal radial position, the center O1 of the end faces 220a to 220l has a relatively small temperature difference, which is about 0 to 3 degrees. The maximum crystal radial position O2 of the end faces 220a to 220l has a relatively large temperature difference, which is about 10 to 20 degrees. In other words, the difference between any two temperatures among the end faces 220a-220l, whether at the same radius or different radii, is about 20 degrees or less, for example, 15 degrees, 10 degrees, 5 degrees, or 2 degrees. In other words, regardless of which of the sub-crystals 210a-210l the crystal 200 is stacked on along the first direction F1, the difference between any two temperatures measured at any time and at any position is about 20 degrees or less. By reducing the temperature gradient fluctuation of the temperature field during the growth process of the crystal 200 of this embodiment, high quality, large, thick crystals 200 and wafers 400 (FIG. 6) are grown with low stress.

[0029] FIG. 4A is a schematic diagram showing the relationship between the temperature of the end faces of a crystal formed in a conventional fixed-type crystal growth furnace and the crystal radial position at multiple time points. Referring to FIG. 4A, when comparing the temperature differences of the end faces 220a-220l themselves in the temperature curves of the end faces 220a-220l, the end face 220a has the smallest temperature difference, which is about 5 degrees. The end face 2201 has the largest temperature difference, which is about 15 degrees. On the other hand, when comparing the temperature differences of the end faces 220a-220l at the same crystal radial position, the temperature difference at the center of the end faces 220a-220l is a maximum of about 70 degrees, and the maximum temperature difference at the maximum crystal radial position O2 of the end faces 220a-220l is about 80 degrees.

[0030] FIG. 4B is a schematic diagram showing the relationship between the temperature of the end face of a crystal formed in a conventional movable crystal growth furnace and the crystal radial position at multiple time points. Referring to FIG. 4B, when comparing the temperature differences of the end faces 220a-220l themselves in the temperature curves of the end faces 220a-220l, the end face 220a has the smallest temperature difference, which is about 5 degrees. The end face 2201 has the largest temperature difference, which is about 15 degrees. On the other hand, when comparing the temperature differences of the end faces 220a-220l at the same crystal radial position, the temperature difference at the center of the end faces 220a-220l is a maximum of about 12 degrees, and the maximum temperature difference at the maximum crystal radial position O2 of the end faces 220a-220l is about 20 degrees or more.

[0031] As can be seen from the results in Figures 3, 4A, and 4B, when the crystal growing method for forming the crystal 200 is performed by the crystal growing furnace system 100, the temperature difference of the end faces 220a-220l of the crystal 200 and the temperature difference between the end faces 220a-220l are significantly reduced. As a result, the stress difference between the crystals 200 is reduced, thereby increasing the thickness T1 and size, and improving the quality of the crystals 200.

[0032] It should be noted that the crystal 200 is not limited to being formed in the crystal growing furnace system 100. In other embodiments, the effect of a larger thickness and a more favorable quality can also be achieved as long as the maximum temperature difference between any two of the end faces of the crystal 200 is controlled to be 20 degrees or less.

[0033] FIG. 5 is an ingot of the crystal of FIG. 2 after spheroidization. The ingot 300 shown in FIG. 5 is a finished product after spheroidization of the crystal 200 formed by the crystal growth method, and the ingot 300 has the advantages of the preferred thickness and quality of the crystal 200. Therefore, the diameter D1 of the ingot body 310 of the ingot 300 is 150 mm or more, and the thickness T1 is 15 mm or more. For example, the diameter D1 is 150 mm, and the thickness T1 is 25 mm or more, or the diameter D1 is 200 mm, and the thickness T1 is 15 mm or more. The thickness T1 of the ingot body 310 is not limited thereto. In other embodiments, the thickness T1 of the ingot body 310 may be as thick as 100 mm.

[0034] Figure 6 is a wafer of the ingot of Figure 5 after cutting, grinding and polishing. The diameter D2 of the wafer 400 shown in Figure 6 is close to the diameter D1 of the ingot 300 shown in Figure 5. Therefore, the diameter D2 of the wafer body 410 of the wafer 400 is 150 mm or more or 200 mm or more.

[0035] The wafer 400 after cutting, grinding and polishing also has the favorable quality of the ingot 300. Thus, the basal plane dislocations (BPD) of the wafer body 410 are less than 1000 ea / cm 2 The bar stacking fault of the wafer body 410 is 100 ea / wf or less. The BPD is, for example, 500 ea / cm 2 , 300ea / cm 2 , or 200 ea / cm 2 The bar stacking faults are, for example, less than or equal to 50 ea / wf, 30 ea / wf, or 10 ea / wf.

[0036] Meanwhile, the curvature of the wafer body 410 is between plus or minus 15 μm, plus or minus 30 μm, or plus or minus 50 μm. The warp of the wafer body 410 is 50 μm or less, 30 μm or less, or 10 μm or less.

[0037] As described above, the crystal growth method of the present invention forms a corresponding sub-crystal at each time point by placing a seed crystal in the furnace of a crystal growth furnace system. The sub-crystals are heated evenly, so the maximum temperature difference between any two end faces of the sub-crystals may be 20 degrees or less. This design can reduce the stress difference of the crystal, thereby increasing the overall thickness and size and improving the quality of the crystal. After spheroidizing the crystal formed by the crystal growth method of the present invention, a thicker ingot with favorable quality can be produced, and after cutting the ingot, a wafer with favorable quality can be produced. [Industrial Applicability]

[0038] The crystal growing method and wafer of the present invention can be applied to a crystal growing furnace system for growing crystals. [Explanation of symbols]

[0039] A1 axis F1 1st direction D1, D2 diameter O1 center O2 maximum crystal radial position R1 Radial direction T1 Thickness 10 Power supply 20 Silicon carbide raw materials 30 seed crystals 40 thermometer 50 Gas Cylinders 100 Crystal Growth Furnace System 110 External Heating Module 120 Furnace 130 First Drive Unit 140 Second Drive Unit 150 Control device 160 Insulation Layer 170 Weight scale 200 crystals 210a, 210b, 210c, 210d, 210e, 210f, 210g, 210h, 210i, 210j, 210k, 210l Sub-crystal 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220h, 220i, 220j, 220k, 220l end face 300 Ingots 310 Ingot body 400 wafers 410 Wafer body

Claims

1. 1. A method of growing a crystal comprising: providing a seed crystal in a crystal growing furnace; and forming a crystal on the seed crystal along a first direction after a plurality of time points, the crystal comprising a plurality of sub-crystals stacked along the first direction, wherein at each of the time points a corresponding one of the sub-crystals is formed, the sub-crystals comprising a plurality of end faces remote from the seed crystal, and wherein a maximum temperature difference between any two of the end faces is 20 degrees or less.

2. 2. The method of claim 1, wherein the difference between the maximum temperatures of any two of the end faces is 15 degrees or less.

3. 2. The method of claim 1, wherein the difference between the maximum temperatures of at least two of the end faces is 10 degrees or less.

4. 2. The method of claim 1, wherein the difference between the maximum temperatures of at least two of the end faces is 5 degrees or less.

5. 2. The method of claim 1, wherein the difference between the maximum temperatures of at least two of the end faces is less than or equal to 2 degrees.

6. 2. The method of claim 1, wherein each of the end faces includes a center and an edge, and the difference in temperature between the center and the edge is 20 degrees or less.

7. The wafer body has a diameter of 150 mm or more, and the wafer body has a basal plane dislocation density of 1000 ea / cm ２ and wherein the bar stacking faults in the wafer body are 100 ea / wf or less.

8. The basal plane dislocations of the wafer body are less than 500 ea / cm ２ , 300ea / cm ２ , or 200 ea / cm ２ 8. The wafer of claim 7, wherein:

9. 8. The wafer of claim 7, wherein the bar stacking faults in the wafer body are less than or equal to 50 ea / wf, 30 ea / wf, or 10 ea / wf.

10. 8. The wafer of claim 7, wherein the wafer body curvature is between plus or minus 15 μm, plus or minus 30 μm, or plus or minus 50 μm.

11. The wafer according to claim 7 , wherein the warpage of the wafer body is 50 μm or less, 30 μm or less, or 10 μm or less.

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