CN113322447A - Graphite substrate for improving wavelength uniformity of epitaxial wafer and manufacturing method thereof - Google Patents

Abstract

The disclosure provides a graphite substrate for improving wavelength uniformity of an epitaxial wafer and a manufacturing method thereof, belonging to the technical field of semiconductors. The graphite substrate is a disc, a plurality of circular grooves used for containing epitaxial wafers are formed in the first surface of the graphite substrate, the centers of the circular grooves are located on at least two first concentric circles, a plurality of circular pits are further formed in the first surface of the graphite substrate, the centers of the circular pits are located on at least one second concentric circle, the centers of the at least one second concentric circle and the at least two first concentric circles are coincident, and the first concentric circles and the second concentric circles are alternately arranged. The graphite substrate can reduce the flow velocity of Mo source airflow flowing to the edge of the graphite substrate, improve the problems of large centrifugal force at the edge of the graphite substrate and overhigh flow velocity of the Mo source, and further improve the problem that the wavelength of the outer ring edge of an epitaxial wafer grown on the graphite substrate is slightly short or long, so that the light-emitting wavelength of each region of the epitaxial wafer is consistent.

Description

Graphite substrate for improving wavelength uniformity of epitaxial wafer and manufacturing method thereof

Technical Field

The disclosure relates to the technical field of semiconductors, and in particular relates to a graphite substrate for improving wavelength uniformity of an epitaxial wafer and a manufacturing method thereof.

Background

A semiconductor Light Emitting Diode (LED) is a kind of semiconductor Diode that can convert electrical energy into Light energy. The LED has the advantages of high efficiency, energy conservation and environmental protection, and has wide application in the fields of traffic indication, outdoor full-color display and the like. Particularly, the semiconductor solid-state lighting is realized by utilizing a high-power LED, and the semiconductor solid-state lighting is expected to become a new generation light source to enter thousands of households, thereby causing the revolution of the human lighting history.

The epitaxial wafer is a primary finished product in the LED manufacturing process. When the epitaxial wafer is formed, the substrate is placed on a tray in a reaction chamber of Metal Organic Chemical Vapor Deposition (MOCVD) equipment, heat energy provided by a heating wire in the MOCVD equipment is conducted to the substrate through the tray, raw materials are introduced into the reaction chamber, and semiconductor materials are epitaxially grown on the substrate to form the epitaxial wafer. Most of the current trays use graphite substrates. The graphite substrate is provided with a plurality of grooves, and one substrate can be accommodated in one groove.

In the course of implementing the present disclosure, the inventors found that the prior art has at least the following problems:

the graphite substrate rotates at a high speed in the epitaxial wafer forming process, and gas flows exist on the surface of the graphite substrate at the high rotating speed, so that the gas distribution of a Mo source introduced into a reaction cavity in the epitaxial wafer growth process can be influenced. And the farther from the center of the graphite substrate, the more uneven the distribution of the MO source occurs. Particularly, the edge position of the graphite substrate is subjected to the largest centrifugal force, and the linear velocity is the largest, so that the flow velocity of the MO source airflow is increased, and the phenomenon that the edge wavelength of the graphite substrate is abnormally shorter or longer is caused.

Disclosure of Invention

The embodiment of the disclosure provides a graphite substrate for improving wavelength uniformity of an epitaxial wafer and a manufacturing method thereof, which can solve the problems of large centrifugal force at the edge of the graphite substrate and over-fast flow speed of a Mo source, and further can solve the problem of short or long wavelength at the outer ring edge of the epitaxial wafer grown on the graphite substrate, so that the light-emitting wavelength of each region of the epitaxial wafer is consistent. The technical scheme is as follows:

the disclosed embodiments provide a graphite substrate for improving wavelength uniformity of an epitaxial wafer, the graphite substrate is a disk, a first surface of the graphite substrate is provided with a plurality of circular grooves for accommodating the epitaxial wafer, the centers of the circular grooves are located on at least two first concentric circles,

the first surface of the graphite substrate is also provided with a plurality of circular pits, the centers of the circular pits are positioned on at least one second concentric circle, the centers of the at least one second concentric circle and the at least two first concentric circles are superposed, and the first concentric circles and the second concentric circles are alternately arranged.

Optionally, the number of the first concentric circles is n, the number of the second concentric circles is m, m is n-1, and m is a positive integer greater than or equal to 2.

Optionally, the depths H of the circular pits on the same second concentric circle are the same, and H is greater than or equal to 5um and less than or equal to 50 um.

Optionally, when 2 ≦ m, the depth of the circular pits on the ith second concentric circle is less than the depth of the circular pits on the (i + 1) th second concentric circle from the center of the graphite substrate to the edge direction of the graphite substrate, and 1 ≦ i ≦ m.

Optionally, the depth of the plurality of circular shaped dimples on the ith said second concentric circle is 1/2 of the depth of the plurality of circular shaped dimples on the (i + 1) th said second concentric circle.

Optionally, the diameters D of the plurality of circular pits located on the same second concentric circle are the same, and D is greater than or equal to 2um and less than or equal to 20 um.

Optionally, when 2 ≦ m, the diameter of the circular pits on the ith second concentric circle is smaller than the diameter of the circular pits on the (i + 1) th second concentric circle from the center of the graphite substrate to the edge direction of the graphite substrate, and 1 ≦ i ≦ m.

Optionally, the diameter of the plurality of circular dimples on the ith second concentric circle is 1/2 of the diameter of the plurality of circular dimples on the (i + 1) th second concentric circle.

Optionally, a plurality of the circular pits located on the same second concentric circle are equidistantly spaced.

In another aspect, there is provided a method of manufacturing a graphite substrate for improving wavelength uniformity of an epitaxial wafer, the method comprising:

forming a plurality of circular grooves for accommodating epitaxial wafers on the first surface of the graphite substrate, wherein the centers of the circular grooves are located on at least two first concentric circles;

forming a plurality of circular pits on the first surface of the graphite substrate, wherein the centers of the circular pits are located on at least one second concentric circle, the centers of the at least one second concentric circle and the at least two first concentric circles are superposed, and the first concentric circles and the second concentric circles are alternately arranged.

The technical scheme provided by the embodiment of the disclosure has the following beneficial effects:

a plurality of circular recesses are formed in the surface of the graphite substrate on which the plurality of circular grooves are formed. The Mo source gas flows down from above the graphite substrate, and the Mo source gas is sucked down and reaches the first surface of the graphite substrate while the graphite substrate is rotating at a high speed, and then flows toward the edge of the graphite substrate by a centrifugal force. At this time, the first surface of the graphite substrate has a plurality of circular pits, and the plurality of circular pits are located on at least one second concentric circle. Therefore, part of Mo source airflow flowing towards the edge of the graphite substrate can flow into the circular pits, the circular pits can buffer the airflow, the flow rate of the Mo source airflow flowing to the edge of the graphite substrate is reduced, the problems that the centrifugal force of the edge of the graphite substrate is large and the flow rate of the Mo source is too high can be solved, the problem that the wavelength of the outer ring edge of an epitaxial wafer grown on the graphite substrate is short or long can be solved, and the light-emitting wavelength of each region of the epitaxial wafer is consistent. And when the plurality of circular pits are positioned on the plurality of second concentric circles, the Mo source airflow flowing to the edge of the graphite substrate can be buffered and decelerated for a plurality of times, so that the consistency of the light-emitting wavelength of the epitaxial wafer can be better.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a front view of a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure;

fig. 2 is a top view of a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure;

FIG. 3 is a schematic view illustrating a flow direction of a Mo source gas provided by an embodiment of the disclosure;

fig. 4 is a flowchart of a method for manufacturing a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure;

FIG. 5 is a schematic illustration of the emission wavelength of an epitaxial wafer grown on a conventional graphite substrate;

fig. 6 is a schematic diagram of the light emission wavelength of an epitaxial wafer grown on a graphite substrate provided by an embodiment of the present disclosure.

Detailed Description

To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

Fig. 1 is a front view of a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure, and fig. 2 is a top view of a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 1 and fig. 2, a graphite substrate 100 for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure is provided, the graphite substrate 100 is a circular disk, a first surface of the graphite substrate 100 has a plurality of circular grooves 100a for accommodating an epitaxial wafer, and centers of the plurality of circular grooves 100a are located on at least two first concentric circles a.

The first surface of the graphite substrate 100 further has a plurality of circular recesses 100B, the centers of the plurality of circular recesses 100B are located on at least one second concentric circle B, the centers of the at least one second concentric circle B and the at least two first concentric circles a are coincident, and the first concentric circles a and the second concentric circles B are alternately arranged.

In the embodiment of the disclosure, the plurality of circular pits are arranged on the surface of the graphite substrate, on which the plurality of circular grooves are arranged. The Mo source gas flows down from above the graphite substrate, and the Mo source gas is sucked down and reaches the first surface of the graphite substrate while the graphite substrate is rotating at a high speed, and then flows toward the edge of the graphite substrate by a centrifugal force. At this time, the first surface of the graphite substrate has a plurality of circular pits, and the plurality of circular pits are located on at least one second concentric circle. Therefore, part of Mo source airflow flowing towards the edge of the graphite substrate can flow into the circular pits, the circular pits can buffer the airflow, the flow rate of the Mo source airflow flowing to the edge of the graphite substrate is reduced, the problems that the centrifugal force of the edge of the graphite substrate is large and the flow rate of the Mo source is too high can be solved, the problem that the wavelength of the outer ring edge of an epitaxial wafer grown on the graphite substrate is short or long can be solved, and the light-emitting wavelength of each region of the epitaxial wafer is consistent. And when the plurality of circular pits are positioned on the plurality of second concentric circles, the Mo source airflow flowing to the edge of the graphite substrate can be buffered and decelerated for a plurality of times, so that the consistency of the light-emitting wavelength of the epitaxial wafer can be better.

Optionally, the number of the first concentric circles a is n, the number of the second concentric circles B is m, m is n-1, and m is a positive integer greater than or equal to 2.

At this time, a second concentric circle B is formed between two adjacent first concentric circles a, that is, a circle of circular recess 100B is formed between two adjacent circles of circular grooves 100 a. The Mo source airflow flowing to the edge of the graphite substrate can be buffered and decelerated for many times, and the effect of improving the excessive flow speed of the Mo source at the edge of the outer ring of the graphite substrate is better.

Fig. 3 is a schematic view illustrating a flow direction of a Mo source according to an embodiment of the disclosure, and as shown in fig. 3, in the embodiment of the disclosure, centers of a plurality of circular grooves 100a are located on three first concentric circles a, and centers of a plurality of circular pits 100B are located on two second concentric circles B.

When the Mo source gas flows down from above the graphite substrate 100, it reaches the first surface of the graphite substrate 100. The centrifugal force causes the graphite substrate 100 to flow toward its edge. Part of the Mo source air flow flowing toward the edge of the graphite substrate 100 flows into the plurality of circular recesses 100B on the two second concentric circles B in sequence, and two times of buffering and deceleration are performed, so as to achieve the effect of reducing the flow velocity of the Mo source air flow flowing to the edge of the graphite substrate 100.

Optionally, the depths H of the plurality of circular pits 100B located on the same second concentric circle B are the same, and H is greater than or equal to 5um and less than or equal to 50 um. The depth H is the same to facilitate the actual growth fabrication.

Here, referring to fig. 1, the depth H of the circular recess 100b is a distance from the bottom of the circular recess 100b to the first surface of the graphite substrate 100.

If the depth H is too small, the effect of improving the flow speed of the Mo source at the outer ring edge of the graphite substrate too fast cannot be obtained. If the depth H is too deep, the processing difficulty is increased, and the airflow on the surface of the graphite substrate 100 may bounce at the position of the circular recess 100b to cause local eddy.

Alternatively, when 2 ≦ m, the depth 100B of the plurality of circular recesses on the ith second concentric circle B is smaller than the depth of the plurality of circular recesses 100B on the (i + 1) th second concentric circle B from the center of the graphite substrate 100 to the edge direction of the graphite substrate 100, and 1 ≦ i ≦ m.

The higher the linear velocity, the more the flow velocity of the MO source gas flow is increased due to the closer the edge of the graphite substrate 100. And the deeper the depth of the circular recess 100b, the better the buffering deceleration effect on the MO source gas flow. Therefore, in this implementation, the depth of the plurality of circular recesses 100B is deeper as the second concentric circle B is closer to the edge of the graphite substrate 100, which is advantageous for maintaining uniformity of the MO source gas flow in the center and edge regions of the graphite substrate 100.

In one implementation manner of the embodiment of the present disclosure, the depth of the plurality of circular pits 100B on the ith second concentric circle B is 1/2 of the depth of the plurality of circular pits 100B on the ith +1 th second concentric circle B, so that the depth of the plurality of circular pits 100B on each second concentric circle B is linearly and gradually changed, which is beneficial to reducing the generation of local eddy currents.

In another implementation manner of the embodiment of the present disclosure, the depths of the plurality of circular pits 100B on the m second concentric circles B may also be all equal, so as to facilitate manufacturing.

Alternatively, referring to FIG. 2, the diameters D of the plurality of circular recesses 100B located on the same second concentric circle B are the same, 2um ≦ D ≦ 20 um.

If the diameter D of the circular recess 100b is too large, local eddy current may be caused by bouncing at the position of the circular recess 100 b. If the diameter of the circular recess 100b is too small, the number of the circular recesses 100b to be processed is large, and the processing is complicated.

Alternatively, when 2 ≦ m, the diameter of the plurality of circular recesses 100B on the ith second concentric circle B is smaller than the diameter of the plurality of circular recesses 100B on the (i + 1) th second concentric circle B in the direction from the center of the graphite substrate 100 to the edge of the graphite substrate 100, and 1 ≦ i ≦ m.

The higher the linear velocity, the more the flow velocity of the MO source gas flow is increased due to the closer the edge of the graphite substrate 100. While the larger the diameter of the circular recess 100b, the better the buffering deceleration effect on the MO source gas flow. In this implementation, therefore, the diameter of the plurality of circular recesses 100B is larger closer to the second concentric circle B of the edge of the graphite substrate 100, which is advantageous for maintaining uniformity of the MO source gas flow in the center and edge regions of the graphite substrate 100.

In one implementation of the disclosed embodiment, the diameter of the plurality of circular shaped dimples 100B on the ith second concentric circle B is 1/2 of the diameter of the plurality of circular shaped dimples 100B on the (i + 1) th second concentric circle B.

In another implementation manner of the embodiment of the present disclosure, the diameters of the plurality of circular pits 100B on the m second concentric circles B may also be all equal, so as to facilitate production and manufacturing.

Alternatively, a plurality of circular recesses 100B on the same second concentric circle B are equally spaced, which is advantageous in maintaining uniformity of the MO source gas flow in the center and edge regions of the graphite substrate 100.

The number of the circular recesses 100B on each second concentric circle B should be set to a proper amount. If the amount of the Mo source is too large, the Mo source cannot be used for improving the too fast flowing speed of the Mo source at the edge of the outer ring of the graphite substrate.

As shown in fig. 2, in the embodiment of the present disclosure, 8 circular recesses 100B are provided on each second concentric circle B. In practice, a plurality of the carriers may be provided, for example, 6, 10, etc., as needed.

Alternatively, when 2 ≦ m, the number of the plurality of circular recesses 100B on the m second concentric circles B gradually increases from the center of the graphite substrate 100 to the edge direction of the graphite substrate 100.

The disclosed embodiment also provides a method for manufacturing a graphite substrate with improved wavelength uniformity of an epitaxial wafer, which is used for manufacturing the graphite substrate shown in fig. 1 and 2. Fig. 4 is a flowchart of a method for manufacturing a graphite substrate for improving wavelength uniformity of an epitaxial wafer according to an embodiment of the present disclosure, where as shown in fig. 4, the method includes:

step 201, forming a plurality of circular grooves for accommodating epitaxial wafers on the first surface of the graphite substrate.

Wherein the centers of the plurality of circular grooves are located on at least two first concentric circles.

Step 202, forming a plurality of circular pits on the first surface of the graphite substrate.

The centers of the circular pits are located on at least one second concentric circle, the centers of the at least one second concentric circle and the at least two first concentric circles are overlapped, and the first concentric circles and the second concentric circles are alternately arranged.

Illustratively, the number of the first concentric circles is n, the number of the second concentric circles is m, m is n-1, and m is a positive integer greater than or equal to 2.

In this case, a second concentric circle is formed between two adjacent first concentric circles, that is, a circle of circular recess is formed between two adjacent circles of circular grooves. The Mo source airflow flowing to the edge of the graphite substrate can be buffered and decelerated for many times, and the effect of improving the excessive flow speed of the Mo source at the edge of the outer ring of the graphite substrate is better.

Optionally, the depths H of the plurality of circular pits located on the same second concentric circle are the same, and H is greater than or equal to 5um and less than or equal to 50 um. The depth H is the same to facilitate the actual growth fabrication.

Wherein, referring to fig. 1, the depth H of the circular recess is the distance from the bottom of the circular recess to the first surface of the graphite substrate.

If the depth H is too small, the effect of improving the flow speed of the Mo source at the outer ring edge of the graphite substrate too fast cannot be obtained. If the depth H is too deep, the processing difficulty is increased, and meanwhile, airflow on the surface of the graphite substrate plate rebounds at the position of the circular concave pit to cause local eddy.

Optionally, when 2 ≦ m, the depth of the plurality of circular pits on the ith second concentric circle is less than the depth of the plurality of circular pits on the (i + 1) th second concentric circle from the center of the graphite substrate to the edge direction of the graphite substrate, and 1 ≦ i ≦ m.

The higher the linear velocity, the more the flow velocity of the MO source gas stream is increased due to the closer to the edge of the graphite substrate. The deeper the depth of the circular pits, the better the buffering and decelerating effect on the MO source gas flow. Thus, in this implementation, the deeper the second concentric circle near the edge of the graphite substrate, the greater the depth of the plurality of circular depressions therein, which is beneficial in maintaining uniformity of the MO source gas flow in the center and edge regions of the graphite substrate.

In one implementation manner of the embodiment of the present disclosure, the depths of the circular pits on the ith second concentric circle are 1/2 of the depths of the circular pits on the (i + 1) th second concentric circle, so that the depths of the circular pits on the respective second concentric circles are gradually changed in a linear manner, which is beneficial to reducing the generation of local eddy currents.

In another implementation manner of the embodiment of the present disclosure, the depths of the plurality of circular pits on the m second concentric circles may also be all equal, so as to facilitate production and manufacturing.

Optionally, referring to FIG. 2, the diameters D of the plurality of circular pits located on the same second concentric circle are the same, and D is greater than or equal to 2um and less than or equal to 20 um.

If the diameter D of the circular pit is too large, local eddy current is caused by rebound at the position of the circular pit. If the diameter of the circular pits is too small, the number of the circular pits required to be processed is large, and the processing is complex.

Optionally, when 2 ≦ m, the diameter of the plurality of circular pits on the ith second concentric circle is smaller than the diameter of the plurality of circular pits on the (i + 1) th second concentric circle from the center of the graphite substrate to the edge direction of the graphite substrate, and 1 ≦ i ≦ m.

The higher the linear velocity, the more the flow velocity of the MO source gas stream is increased due to the closer to the edge of the graphite substrate. The larger the diameter of the circular pits, the better the buffering and decelerating effect on the MO source gas flow. Thus, in this implementation, the diameter of the plurality of circular recesses in the second concentric circle is larger closer to the edge of the graphite substrate, which is beneficial for maintaining uniformity of the MO source gas flow in the center and edge regions of the graphite substrate.

In one implementation of the disclosed embodiment, the diameter of the plurality of circular shaped dimples on the ith second concentric circle is 1/2 times the diameter of the plurality of circular shaped dimples on the (i + 1) th second concentric circle.

In another implementation manner of the embodiment of the present disclosure, the diameters of the plurality of circular pits on the m second concentric circles may also be all equal, so as to facilitate production and manufacturing.

Alternatively, a plurality of circular pits located on the same second concentric circle are equally spaced, which is advantageous to maintain uniformity of the MO source gas flow in the center and edge regions of the graphite substrate.

The number of the circular pits on each second concentric circle is properly set. If the amount of the Mo source is too large, the Mo source cannot be used for improving the too fast flowing speed of the Mo source at the edge of the outer ring of the graphite substrate.

In the disclosed embodiment, there are 8 circular dimples on each second concentric circle. In practice, a plurality of the carriers may be provided, for example, 6, 10, etc., as needed.

Alternatively, when 2 ≦ m, the number of the plurality of circular recesses 100B on the m second concentric circles B gradually increases from the center of the graphite substrate 100 to the edge direction of the graphite substrate 100.

For example, in the embodiments of the present disclosure, a plurality of circular grooves and a plurality of circular recesses may be formed on the first surface of the graphite substrate by using a mechanical cutting grinding method or a laser cutting grinding method. This is conventional technology and embodiments of the present disclosure are not described in detail herein.

In the embodiment of the disclosure, the plurality of circular pits are arranged on the surface of the graphite substrate, on which the plurality of circular grooves are arranged. The Mo source gas flows down from above the graphite substrate, and the Mo source gas is sucked down and reaches the first surface of the graphite substrate while the graphite substrate is rotating at a high speed, and then flows toward the edge of the graphite substrate by a centrifugal force. At this time, the first surface of the graphite substrate has a plurality of circular pits, and the plurality of circular pits are located on at least one second concentric circle. Therefore, part of Mo source airflow flowing towards the edge of the graphite substrate can flow into the circular pits, the circular pits can buffer the airflow, the flow rate of the Mo source airflow flowing to the edge of the graphite substrate is reduced, the problems that the centrifugal force of the edge of the graphite substrate is large and the flow rate of the Mo source is too high can be solved, the problem that the wavelength of the outer ring edge of an epitaxial wafer grown on the graphite substrate is short or long can be solved, and the light-emitting wavelength of each region of the epitaxial wafer is consistent. And when the plurality of circular pits are positioned on the plurality of second concentric circles, the Mo source airflow flowing to the edge of the graphite substrate can be buffered and decelerated for a plurality of times, so that the consistency of the light-emitting wavelength of the epitaxial wafer can be better.

One specific implementation of the graphite substrate shown in fig. 1 comprises: the graphite substrate 100 has a plurality of circular grooves 100a for receiving epitaxial wafers on a first surface thereof, and the circular grooves 100a are centered on two first concentric circles a. The first surface of the graphite substrate 100 further has a plurality of circular recesses 100B, and the centers of the plurality of circular recesses 100B are located on a second concentric circle B. The centers of a second concentric circle B and two first concentric circles A are superposed, and a second concentric circle B is arranged between every two adjacent first concentric circles A.

Wherein, have 8 circular pit 100B on the second concentric circle B, 8 circular pit 100B's diameter is 10um, and the degree of depth is 20 um.

Fig. 5 is a schematic view of the emission wavelength of the epitaxial wafer grown on the conventional graphite substrate, and referring to fig. 5, it can be seen that the region of the same epitaxial wafer near the center of the graphite substrate 100 and the region far from the center of the graphite substrate 100 are different in emission wavelength (i.e., the difference in gray scale between the regions near the graphite substrate and far from the graphite substrate in the same epitaxial wafer in fig. 5 is large), and particularly, the difference in emission wavelength of ten epitaxial wafers far from the center of the graphite substrate 100 is relatively significant (i.e., the difference in gray scale between the ten epitaxial wafers located at the outermost circle in fig. 5 is large).

Fig. 6 is a schematic diagram of the emission wavelengths of the epitaxial wafers grown on the graphite substrate according to the embodiment of the present disclosure, and referring to fig. 6, compared to fig. 5, the difference between the emission wavelengths of the region close to the center of the graphite substrate 100 and the region far from the center of the graphite substrate 100 of the same epitaxial wafer is small (i.e., the difference between the gray levels of the region close to the graphite substrate and the region far from the graphite substrate in the same epitaxial wafer in fig. 6 is small), and particularly, the difference between the emission wavelengths of the ten epitaxial wafers far from the center of the graphite substrate 100 is significantly reduced (i.e., the difference between the gray levels of the ten epitaxial wafers located at the outermost circles in fig. 6 is small).

Another specific implementation of the graphite substrate shown in fig. 1 comprises: the graphite substrate 100 has a plurality of circular grooves 100a for receiving epitaxial wafers on a first surface thereof, and the circular grooves 100a are centered on three first concentric circles a.

The first surface of the graphite substrate 100 further has a plurality of circular recesses 100B, and the centers of the plurality of circular recesses 100B are located on two second concentric circles B. The centers of the two second concentric circles B and the three first concentric circles A are superposed, the first concentric circles A and the second concentric circles B are alternately arranged, and one second concentric circle B is arranged between every two adjacent first concentric circles A.

Wherein, lie in 8 circular pit 100B on the second concentric circle B of inner circle most on two second concentric circles B, 8 circular pit 100B's diameter is 10um, and the degree of depth is 20 um.

Two second concentric circles B on the outermost circle have 16 circular recesses 100B. The diameters of the 16 circular pits 100b are all 5um, and the depths are all 10 um.

The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.

Claims (10)

1. A graphite substrate for improving the wavelength uniformity of epitaxial wafers, the graphite substrate being a circular disk, the graphite substrate (100) having a first surface with a plurality of circular grooves (100a) for receiving epitaxial wafers, the plurality of circular grooves (100a) having centers on at least two first concentric circles (A),

the first surface of the graphite substrate (100) is further provided with a plurality of circular pits (100B), the centers of the circular pits (100B) are located on at least one second concentric circle (B), the centers of the at least one second concentric circle (B) and the at least two first concentric circles (A) are superposed, and the first concentric circles (A) and the second concentric circles (B) are alternately arranged.

2. The graphite substrate according to claim 1, wherein the number of the first concentric circles (a) is n, the number of the second concentric circles (B) is m, and m is n-1, wherein m is a positive integer of 2 or more.

3. The graphite substrate according to claim 2, wherein the depths H of the circular pits (100B) on the same second concentric circle (B) are the same, and H is greater than or equal to 5um and less than or equal to 50 um.

4. The graphite substrate according to claim 3, wherein when 2. ltoreq. m, a depth (100B) of the plurality of circular recesses on the ith second concentric circle (B) is smaller than a depth (100B) of the plurality of circular recesses on the (i + 1) th second concentric circle (B) in a direction from a center of the graphite substrate (100) to an edge of the graphite substrate (100), and 1. ltoreq. i.ltoreq.m.

5. The graphite substrate according to claim 4, wherein the depth of the plurality of circular recesses (100B) on the ith second concentric circle (B) is 1/2 of the depth of the plurality of circular recesses (100B) on the (i + 1) th second concentric circle (B).

6. The graphite substrate according to claim 2, wherein the diameters D of the plurality of circular pits (100B) on the same second concentric circle (B) are the same, and D is greater than or equal to 2um and less than or equal to 20 um.

7. The graphite substrate according to claim 6, wherein when 2. ltoreq. m, the diameter of the plurality of circular recesses (100B) on the ith second concentric circle (B) is smaller than the diameter of the plurality of circular recesses (100B) on the (i + 1) th second concentric circle (B) in a direction from the center of the graphite substrate (100) to the edge of the graphite substrate (100), and 1. ltoreq. i.ltoreq.m.

8. The graphite substrate according to claim 7, wherein the diameter of the plurality of circular recesses (100B) on the ith second concentric circle (B) is 1/2 times the diameter of the plurality of circular recesses (100B) on the (i + 1) th second concentric circle (B).

9. The graphite substrate according to any one of claims 1 to 8, wherein a plurality of the circular recesses (100B) on the same second concentric circle (B) are equidistantly spaced.

10. A method for manufacturing a graphite substrate for improving wavelength uniformity of an epitaxial wafer, the method comprising:

forming a plurality of circular grooves for accommodating epitaxial wafers on the first surface of the graphite substrate, wherein the centers of the circular grooves are located on at least two first concentric circles;

forming a plurality of circular pits on the first surface of the graphite substrate, wherein the centers of the circular pits are located on at least one second concentric circle, the centers of the at least one second concentric circle and the at least two first concentric circles are superposed, and the first concentric circles and the second concentric circles are alternately arranged.

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