Graphite carrier and MOCVD reaction device having the same

Abstract

The present invention discloses a graphite carrier and an MOCVD reaction device having the same. The graphite carrier is circular, and in the direction from the center of the graphite carrier toward the edge, the graphite carrier includes an inner circle area, a middle circle area and an outer circle area. The graphite carrier is provided with a plurality of grooves for carrying a 4-inch substrate, the grooves include an inner circle groove located in the inner circle area, a middle circle groove located in the middle circle area and an outer circle groove located in the outer circle area, and the inner circle area is provided with 6 inner circle grooves. The present invention adjusts the position of the inner circle groove so that 6 inner circle grooves can be placed in the inner circle area, thereby achieving the maximum number of carriers for 4-inch epitaxial production, and at the same time, can effectively improve the circle position voltage difference generated by the existing graphite carrier technology during the epitaxial wafer growth process.

Description

Technical Field

[0001] The invention relates to the field of vapor deposition, and in particular to a graphite carrier and an MOCVD reaction device having the same. Background Art

[0002] MOCVD (Metal-Organic Chemical Vapor Deposition) is a new type of vapor phase epitaxial growth technology developed on the basis of vapor phase epitaxy (VPE). MOCVD is the core equipment for preparing compound semiconductor epitaxial materials. It uses organic compounds of group III and group II elements and hydrides of group V and VI elements as crystal growth source materials, and performs vapor phase epitaxy on the substrate by thermal decomposition reaction. It is mainly used to grow various group III-V, group II-VI compound semiconductors and their multi-component solid solutions of thin-layer single crystal materials, covering all common semiconductors, and has a very broad market prospect.

[0003] The MOCVD reaction device in the prior art generally includes: a shower head and a graphite carrier that are arranged opposite to each other, the shower head is used to provide reaction gas, the graphite disk has a plurality of grooves, each groove has a corresponding substrate, and there is also a heating device under the graphite carrier to heat the graphite carrier. The graphite carrier is heated and the substrate can be heated by thermal radiation and heat conduction. When the MOCVD process is performed, the reaction gas enters the reaction area above the graphite carrier from the small hole of the shower head. The substrate has a certain temperature due to the heat conduction heating of the heating device. This temperature causes a chemical reaction between the reaction gases, thereby depositing an epitaxial material layer on the substrate surface.

[0004] The existing graphite carrier has defects in production capacity and performance due to the placement of the grooves. Under the current requirements of LED epitaxial plants to pursue production capacity and improve performance, there is an urgent need for a new type of graphite carrier that can have higher yield and better performance. Summary of the invention

[0005] The object of the present invention is to provide a graphite carrier and an MOCVD reaction device having the same, which can greatly improve the production capacity and chip performance.

[0006] To achieve one of the above-mentioned purposes of the invention, an embodiment of the present invention provides a graphite carrier, which is circular, and in the direction from the center of the graphite carrier toward the edge, the graphite carrier includes an inner circle area, a middle circle area and an outer circle area, and the graphite carrier is provided with a plurality of grooves for carrying a 4-inch substrate, the grooves include an inner circle groove located in the inner circle area, a middle circle groove located in the middle circle area and an outer circle groove located in the outer circle area, and the inner circle area is provided with 6 inner circle grooves.

[0007] As a further improvement of an embodiment of the present invention, the graphite carrier further includes a plurality of support members located in the groove, and the plurality of support members have the same height in the thickness direction of the graphite carrier.

[0008] As a further improvement of one embodiment of the present invention, the middle circle area is provided with 12 middle circle grooves, and the outer circle area is provided with 18 outer circle grooves.

[0009] As a further improvement of an embodiment of the present invention, the groove is a circular groove.

[0010] As a further improvement of one embodiment of the present invention, the centers of several inner circle grooves are connected to form an inner circle center line, and the center lines of several middle circle grooves are connected to form a middle circle center line, and an intermediate area is formed between the middle circle center line and the inner circle center line, and the intermediate area includes a first area corresponding to the several inner circle grooves, a second area corresponding to the several middle circle grooves, and an intersection area corresponding to the remaining part, and the substrate is used to form an epitaxial wafer, the working voltage of the epitaxial wafer corresponding to the inner circle groove is a first voltage, and the working voltage of the epitaxial wafer corresponding to the middle circle groove is a second voltage, there is a voltage difference between the first voltage and the second voltage, and the area of ​​the intersection area is positively correlated with the voltage difference.

[0011] As a further improvement of an embodiment of the present invention, the area of ​​the intersection region is not greater than 30000mm 2 .

[0012] As a further improvement of one embodiment of the present invention, the graphite carrier has a center point, and there is an outer ring intersection area between any two outer ring grooves. A reference line is formed between the center point and the outer ring intersection area, and the minimum angle between the first line between the center point and the center of the inner ring groove and the reference line is 10°, the minimum angle between the second line between the center point and the center of the middle ring groove and the reference line is 5°, and the minimum angle between the third line between the center point and the center of the outer ring groove and the reference line is 10°.

[0013] As a further improvement of an embodiment of the present invention, a line connecting the center of any inner circle groove and the centers of two adjacent middle circle grooves forms an equilateral triangle.

[0014] As a further improvement of an embodiment of the present invention, any inner circle groove is in contact with the adjacent inner circle groove or middle circle groove.

[0015] To achieve one of the above-mentioned purposes of the invention, one embodiment of the present invention provides an MOCVD reaction device, comprising a graphite carrier as described in any one of the above technical solutions, a heating device located below the graphite carrier, a reaction chamber and a source supply system, wherein the graphite carrier is located in the reaction chamber, and the source supply system is used to provide reaction gas to the reaction chamber.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: an embodiment of the present invention adjusts the position of the inner ring groove so that 6 inner ring grooves can be placed in the inner ring area, thereby achieving the maximum number of carriers for 4-inch epitaxial production. At the same time, it can effectively improve the ring position voltage difference generated by the existing graphite carrier technology during the epitaxial wafer growth process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a MOCVD reaction device according to one embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of a graphite carrier according to an embodiment of the present invention;

[0019] Figure 3 is another schematic diagram of a graphite carrier according to an embodiment of the present invention;

[0020] Figure 4 1 is a graph showing the relationship between the area of ​​the junction region corresponding to a single inner ring groove and the voltage difference according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0022] In the various figures of the present application, for the convenience of illustration, some dimensions of structures or parts are exaggerated relative to other structures or parts, and therefore, are only used to illustrate the basic structure of the subject matter of the present application.

[0023] In addition, terms such as "upper", "above", "lower", "below", etc. used herein to indicate spatial relative positions are used for the purpose of convenience to describe the relationship of one unit or feature relative to another unit or feature as shown in the accompanying drawings. Terms of spatial relative position may be intended to include different orientations of the device in use or operation other than the orientation shown in the drawings. For example, if the device in the figure is turned over, the units described as being "below" or "beneath" other units or features will be located "above" the other units or features. Therefore, the exemplary term "below" can encompass both the above and below orientations. The device may be oriented in other ways (rotated 90 degrees or other orientations), and the spatially related descriptors used herein interpreted accordingly.

[0024] Combination Figure 1 , is a schematic diagram of a MOCVD reaction device 100 according to an embodiment of the present invention.

[0025] The MOCVD reaction device 100 here takes the Veeco K868 model as an example.

[0026] The MOCVD reaction device 100 includes a graphite carrier 10 , a baffle 20 , a heating device 30 , a cover 40 , an ash collecting ring 50 , and the like.

[0027] In this embodiment, the graphite carrier 10 is located in the reaction chamber S of the MOCVD reaction device 100 . The graphite carrier 10 is formed by pressing graphite. A plurality of grooves 101 for supporting the substrate are formed on the graphite carrier 10 .

[0028] The graphite carrier 10 is circular, and the center of the graphite carrier 10 is fixed on the driving shaft 60 to realize the rotation of the graphite carrier 10. The MOCVD reaction device 100 also includes a source supply system 70 and other structures. The source supply system 70 is used to provide reaction gas to the reaction chamber S. The rotation of the graphite carrier 10 can make the reaction gas evenly deposited on each substrate.

[0029] In this embodiment, the baffle 20 is in a hollow ring shape and is disposed around the graphite carrier 10. The baffle 20 can move up and down, thereby fully meeting the requirements of MOCVD automated production.

[0030] In the design of MOCVD, the most important part is the design of the flow field and thermal field inside the reaction chamber S. Only by designing the most appropriate flow field and thermal field can the reaction process inside the reaction chamber S proceed smoothly, the utilization rate of the reactant source materials be improved, and the quality of the deposited film be improved. In the vertical MOCVD, the baffle 20 arranged next to the graphite carrier 10 is particularly important. It directly affects the flow field distribution above the graphite carrier 10, and because the baffle 20 is very close to the graphite carrier 10, it also has a certain degree of influence on the temperature field distribution on the surface of the graphite carrier 10. The baffle 20 can provide a surrounding stable space for the reaction chamber S during the growth process, and the airflow will not be chaotic when passing through the reaction chamber S.

[0031] The heating device 30 is located below the graphite carrier 10. The heating device 30 is used to heat the graphite carrier 10 so that the graphite carrier 10 remains within the epitaxial growth temperature range, thereby realizing the forming of the thin film. Currently, the commonly used heating method is radiation heating, which relies on the thermal radiation of the heating device 30 to heat the graphite carrier 10.

[0032] The cover body 40 is disposed around the heating device 30 .

[0033] Here, the cover body 40 is a molybdenum cover, which can protect the heating device 30. The cover body 40 can prevent impurities generated by the reaction from entering the bottom of the heating device 30. When air flows in, the airflow can be stabilized due to the blocking effect of the cover body 40.

[0034] The ash collecting ring 50 is provided with a plurality of exhaust holes, and the growing airflow and the reacted compounds are discharged from the reaction chamber S through the exhaust holes in the ash collecting ring 50 , and the residual impurities are retained in the ash collecting ring 50 .

[0035] Ginseng Figure 2 , is a schematic diagram of a graphite carrier 10 according to an embodiment of the present invention.

[0036] From the center of the graphite carrier 10 toward the edge, the graphite carrier 10 includes an inner circle area 10a, a middle circle area 10b and an outer circle area 10c.

[0037] The graphite carrier 10 is provided with a plurality of grooves 101 for carrying 4-inch substrates.

[0038] The groove 101 is a circular groove 101 .

[0039] The grooves 101 include an inner groove 101 a located in the inner region 10 a , a middle groove 101 b located in the middle region 10 b , and an outer groove 101 c located in the outer region 10 c .

[0040] The inner ring area 10a is provided with six inner ring grooves 101a.

[0041] The middle circle area 10b is provided with 12 middle circle grooves 101b.

[0042] The outer ring region 10c is provided with 18 outer ring grooves 101c.

[0043] This implementation can increase production capacity and improve the performance of formed chips.

[0044] In this embodiment, the graphite carrier 10 further includes a plurality of support members located in the groove 101 . In the thickness direction of the graphite carrier 10 , the plurality of support members have the same height. That is, when the substrate is disposed in the groove 101 , the plurality of substrates have the same height.

[0045] In this embodiment, a plurality of inner circle grooves 101a are adjacently arranged, a plurality of middle circle grooves 101b are adjacently arranged, a plurality of outer circle grooves 101c are adjacently arranged, and the corresponding inner circle grooves 101a, middle circle grooves 101b and outer circle grooves 101c are adjacently arranged.

[0046] Here, “adjacent arrangement” means that the grooves 101 are arranged as close as possible, and it is only necessary to ensure that there is no conduction between adjacent grooves 101 .

[0047] The graphite carrier 10 has a center point A. An outer ring intersection area is formed between any two outer ring grooves 101c. A reference line L is formed between the center point A and the outer ring intersection area.

[0048] Here, the adjacent outer ring grooves 101c are distributed in a substantially tangent form, and the outer ring junction area is the junction point of two adjacent outer ring grooves 101c.

[0049] The minimum angle α1 between the first line L1 between the center point A and the center of the inner circle groove 101a and the reference line L is 10°, the minimum angle α2 between the second line L2 between the center point A and the center of the middle circle groove 101b and the reference line L is 5°, and the minimum angle α3 between the third line L3 between the center point A and the center of the outer circle groove 101c and the reference line L is 10°.

[0050] Here, since there are multiple reference lines L, first connecting lines L1, second connecting lines L2 and third connecting lines L3, the “minimum angle” is defined as the angle between the two most adjacent lines.

[0051] The line connecting the center of any inner circle groove 101a and the centers of two adjacent middle circle grooves 101b forms an equilateral triangle.

[0052] Any inner circle groove 101a contacts the adjacent inner circle groove 101a or the middle circle groove 101b.

[0053] That is to say, the inner circle groove 101a is in a tangent state with the adjacent inner circle groove 101a or the middle circle groove 101b.

[0054] It can be seen that the plurality of grooves 101 of this embodiment are tightly matched with each other, which can greatly improve the production capacity.

[0055] This embodiment adjusts the position of the inner ring groove 101a so that 6 inner ring grooves 101a can be placed in the inner ring area 10a, thereby achieving the maximum number of carriers for 4-inch epitaxial production. That is, the graphite carrier 10 can carry 36 4-inch substrates at the same time. At the same time, it can effectively improve the ring position voltage difference generated by the existing graphite carrier technology during the epitaxial wafer growth process.

[0056] Specific, combined Figure 3 The centers of several inner circle grooves 101a are connected to form an inner circle center line 11a, and the center lines of several middle circle grooves 101b are connected to form a middle circle center line 11b.

[0057] An intermediate area 12 is formed between the middle circle center line 11b and the inner circle center line 11a. The intermediate area 12 includes a first area 12a corresponding to a plurality of inner circle grooves 101a, a second area 12b corresponding to a plurality of middle circle grooves 101b, and a connecting area 12d corresponding to the remaining portion.

[0058] Here, the first area 12a is the portion of the inner circle groove 101a located in the middle area 12, the second area 12b is the portion of the middle circle groove 101b located in the middle area 12, and the intersection area 12d is the area of ​​the middle area 12 excluding the first area 12a and the second area 12b. The intersection area 12d is the area between the inner circle groove 101a and the middle circle groove 101b where no groove 101 is set.

[0059] The circular area formed by the inner circle center line 11a is S1, the area of ​​the inner circle groove 101a located inside the area formed by the inner circle center line 11a is S2, the circular area formed by the middle circle center line 11b is S3, the area of ​​the middle circle groove 101b located inside the area formed by the middle circle center line 11b is S4, and the area of ​​each inner circle groove 101a is S5.

[0060] The area of ​​the intersection region 12d is defined as S, then, at this time, the area S of the intersection region 12d = S3-S4-6*S5-S1+S2.

[0061] The substrate carried in the groove 101 is subsequently used to form an epitaxial wafer, that is, various thin film layers are deposited on the substrate by the reaction gas provided by the source supply system 70 to form an epitaxial wafer.

[0062] In actual operation, the source supply system 70 provides reaction gas from top to bottom, and the graphite carrier 10 rotates to deposit the reaction gas on each substrate. At this time, a large amount of sediment will also be generated in the intersection area 12d. A large amount of sediment will affect the flow field inside the reaction chamber S, that is, the speed and direction of the gas flow will be affected, resulting in the quality of the thin film layer deposited on each substrate being affected, for example, the thickness and uniformity of the thin film layer will deviate from the ideal value.

[0063] The epitaxial wafers are ultimately used to form diode chips. Due to differences in the molding process of each epitaxial wafer, epitaxial wafers grown in the same batch will show different electrical levels, which in turn results in poor chip yield or inability to ship.

[0064] Specifically, due to differences in the forming processes of each epitaxial wafer, the working voltages of the epitaxial wafers will also be different. For example, the working voltage of the epitaxial wafer corresponding to the inner circle groove 101a is a first voltage V1, and the working voltage of the epitaxial wafer corresponding to the middle circle groove 101b is a second voltage V2. There is a voltage difference V=V1-V2 between the first voltage V1 and the second voltage V2, and the voltage difference V is the circle position voltage difference. The area S of the junction region 12d is positively correlated with the voltage difference V.

[0065] Specific, combined Figure 4 , the area of ​​the intersection region 12d corresponding to a single inner ring groove 101a is S', S'=S / 6.

[0066] The area S' of the junction region 12d corresponding to a single inner ring groove 101a and the voltage difference V are related by:

[0067] y=5E-10x 2 -3E-06x-0.0193;

[0068] Wherein, x is the area S' of the intersection region 12d corresponding to a single inner circle groove 101a, and y is the voltage difference V of the epitaxial wafer formed at the middle circle groove 101b and the inner circle groove 101a.

[0069] In this embodiment, by adjusting the position of the inner ring groove 101a, six inner ring grooves 101a are placed in the inner ring area 10a, so that the area S of the intersection area is not greater than 30000mm. 2 , that is, S' is not greater than 5000mm 2 , then, the voltage difference V at this time can be controlled below 0.01V.

[0070] That is to say, this embodiment can effectively improve the circle position voltage difference generated by the existing graphite carrier technology during the epitaxial wafer growth process, thereby improving the chip yield.

[0071] In summary, the present invention adjusts the position of the inner ring groove 101a so that 6 inner ring grooves 101a can be placed in the inner ring area 10a, thereby achieving the maximum number of carriers for 4-inch epitaxial production. That is, at this time, the graphite carrier 10 can simultaneously carry 36 4-inch substrates. At the same time, it can effectively improve the ring position voltage difference generated by the existing graphite carrier technology during the epitaxial wafer growth process.

[0072] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0073] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A graphite carrier, characterized in that: The graphite carrier is circular, and in the direction from the center of the graphite carrier toward the edge, the graphite carrier includes an inner circle area, a middle circle area and an outer circle area. The graphite carrier is provided with a plurality of grooves for carrying a 4-inch substrate, the grooves include an inner circle groove located in the inner circle area, a middle circle groove located in the middle circle area and an outer circle groove located in the outer circle area. The inner circle area is provided with 6 inner circle grooves, the grooves are circular grooves, the centers of a plurality of inner circle grooves are connected to form an inner circle center line, the center lines of a plurality of middle circle grooves are connected to form a middle circle center line, and an intermediate area is formed between the middle circle center line and the inner circle center line, the intermediate area includes a first area corresponding to a plurality of inner circle grooves, a second area corresponding to a plurality of middle circle grooves and an intersection area corresponding to the remaining part, the substrate is used to form an epitaxial wafer, the working voltage of the epitaxial wafer corresponding to the inner circle groove is a first voltage, the working voltage of the epitaxial wafer corresponding to the middle circle groove is a second voltage, there is a voltage difference between the first voltage and the second voltage, the area of ​​the intersection area is positively correlated with the voltage difference, and the area of ​​the intersection area is not greater than 30000mm 2 The graphite carrier has a center point, and there is an outer ring intersection area between any two outer ring grooves. A reference line is formed between the center point and the outer ring intersection area. The minimum angle between the first line between the center point and the center of the inner ring groove and the reference line is 10°, the minimum angle between the second line between the center point and the center of the middle ring groove and the reference line is 5°, and the minimum angle between the third line between the center point and the center of the outer ring groove and the reference line is 10°.

2. The graphite carrier according to claim 1, characterized in that: The graphite carrier also includes a plurality of support members located in the groove, and the plurality of support members have the same height in the thickness direction of the graphite carrier.

3. The graphite carrier according to claim 1, characterized in that: The middle circle area is provided with 12 middle circle grooves, and the outer circle area is provided with 18 outer circle grooves.

4. The graphite carrier according to claim 1, characterized in that: The line connecting the center of any inner circle groove and the centers of two adjacent middle circle grooves forms an equilateral triangle.

5. The graphite carrier according to claim 1, characterized in that: Any inner circle groove contacts the adjacent inner circle groove or middle circle groove.

6. A MOCVD reaction device, characterized in that: It comprises a graphite carrier as described in any one of claims 1 to 5, a heating device located below the graphite carrier, a reaction chamber and a source supply system, wherein the graphite carrier is located in the reaction chamber, and the source supply system is used to provide reaction gas to the reaction chamber.

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