A MOCVD reaction chamber and a method for adjusting the ceiling level thereof

Abstract

The present invention proposes an MOCVD reaction chamber and a ceiling level adjustment method thereof, which belongs to the field of chemical deposition, wherein the top plate is arranged at intervals just below the top cover; the adjustment parts are evenly distributed between the top plate and the top cover around the center of the top plate surface, each adjustment part applies a force in the vertical direction of the top cover surface, and adjusts the distance between the top plate and the top cover where the adjustment part is located; the detection part is arranged on the edge of the top plate and detects the distance between the top plate and the top cover where it is located in real time; the control part controls the magnitude of the force applied by the adjustment part according to the detection data of the detection part. The present invention determines whether the top plate is horizontal through the detection part, controls the adjustment part to adjust the level of the top plate according to the collected detection data, and applies an upward or downward force to the top plate through the adjustment parts distributed in various directions of the top plate edge to offset the top plate level imbalance caused by the deformation of the top plate edge, and solves the negative impact of the top plate caused by its non-level surface during the deposition process.

Description

Technical Field

[0001] The invention relates to the technical field of chemical deposition, and in particular to an MOCVD reaction chamber and a ceiling level adjustment method thereof. Background Art

[0002] The MOCVD (Metal-Organic Chemical Vapor Deposition) reaction chamber is an important device for achieving high-quality thin film deposition. The reaction chamber is the core part of the MOCVD system and is usually made of stainless steel or other highly corrosion-resistant materials to withstand high temperatures and corrosive gases. The design of the reaction chamber must ensure the uniformity of gas flow and deposition. The existing MOCVD reaction chamber ceiling, also known as the "reaction chamber top plate", is generally designed as an annular disc, fixed to the upper part of the reaction chamber, and the fixed point is the center area of ​​the ceiling. An air intake component is set at the center of the lower surface of the ceiling. When working, the air intake component throws the reaction gas and MO source around in a parabolic form, forming a uniform reactant receiving area under the ceiling, and the substrate is placed in this area for epitaxial growth. Under normal circumstances, a relatively stable epitaxial growth environment can be formed.

[0003] However, in the current reaction chamber design, the following problems exist on the top plate: 1) Affected by the gravity of the ceiling itself, the edge of the ceiling sags more than the center; 2) After multiple furnaces of epitaxial growth, the amount of deposits on the ceiling surface increases. Affected by the tensile stress of the deposits, the amount of sag on the outer part of the ceiling increases, causing the ceiling to take the shape of an inverted pot bottom. As the number of epitaxial growth RUNs increases, the amount of deposits on the edge of the ceiling is more than that on other parts of the ceiling, and the by-products gather at the edge of the ceiling, further aggravating the deformation of the ceiling; 3) When the by-products gather at the edge of the ceiling and accumulate to a certain thickness, they are more likely to fall off, seriously affecting the quality of the epitaxial crystal surface growing below.

[0004] Therefore, after the multi-furnace epitaxial growth, the lower surface of the ceiling is usually cleaned to remove the surface deposits, but the problem of the imbalance of the horizontal state of the ceiling surface caused by the drooping deformation of the ceiling edge is still difficult to solve. Summary of the invention

[0005] In view of this, the present invention proposes an MOCVD reaction chamber and a method for adjusting the ceiling level thereof, which are used to solve the problem that the edge drooping deformation of the ceiling of the current reaction chamber will cause the horizontal state of the ceiling surface to be unbalanced.

[0006] The technical solution of the present invention is implemented as follows: the present invention provides an MOCVD reaction chamber, including a top cover, which is arranged on the top of the MOCVD reaction chamber; a top plate, which is arranged at intervals just below the top cover; a plurality of adjustment parts, which are evenly distributed between the top plate and the top cover around the center of the top plate surface, and the two ends of the adjustment parts are respectively connected to the top cover and the edge of the top plate, each adjustment part applies a force in the vertical direction of the top cover surface, and adjusts the distance between the top plate and the top cover at the position where the adjustment part is located; a detection part, which is arranged on the edge of the top plate and detects the distance between the top plate and the top cover at its position in real time; and a control part, which controls the magnitude of the force applied by the adjustment part according to the detection data of the detection part.

[0007] On the basis of the above technical solution, preferably, the detection part includes a plurality of detection units, which are evenly distributed around the center of the top plate surface on the edge of the end surface of the top plate facing the top cover; wherein each detection unit and each adjustment part are arranged one-to-one on the same radial axis of the top plate.

[0008] More preferably, it also includes a ring body, which is arranged on the end surface of the top plate facing the top cover; wherein the center of the ring body is coaxially arranged with the center of the top plate; and a plurality of adjustment parts are evenly distributed on the ring body and apply force synchronously.

[0009] More preferably, the control unit controls the force applied by the adjustment unit according to the detection data of the detection unit, and the calculation formula is: N=1 / (a×m×g×K)+N 0 , where a is the number of detection units; m is the mass of the top plate; g is the gravitational acceleration; K is the deformation distance coefficient of the top plate, which is expressed as the initial distance h from the top cover when the top plate is installed and leveled. 0 The measured distance h from the top cover after the top plate is deformed 1 The coefficient corresponding to the absolute value Δh of the difference; N 0 It is the compensation force for leveling when the top plate is installed.

[0010] More preferably, the absolute value of Δh is less than 5 mm; assuming that every 0.5 mm in the absolute value of Δh is a value range, the absolute value of Δh includes n value ranges, and the deformation distance coefficient corresponding to each value range of the absolute value of Δh is K=0.1n.

[0011] More preferably, when the absolute value of Δh is greater than 5 mm, the system alarms and replaces the top plate.

[0012] More preferably, when h 0 >h 1 When K takes a negative value; when h 0 <h 1 When , K takes a positive value.

[0013] More preferably, the force applied by the adjusting portion is a thrust toward the top cover or a pull toward the top plate; when h0 >h 1 When h 0 <h 1 When , the force applied by the adjusting part is a tensile force.

[0014] More preferably, the value range of a is a positive integer from 4 to 16.

[0015] On the other hand, the present invention provides a method for adjusting the ceiling level of an MOCVD reaction chamber, using the above-mentioned MOCVD reaction chamber, comprising the following steps: step 1, in a state where the top plate is installed and leveled, a detection unit detects an initial distance h between the top plate and the top cover; 0 Step 2: When the top plate is deformed, the detection unit detects the measured distance h between the top plate and the top cover. 1 ; Step 3, the control unit determines h 0 >h 1 When h 0 <h 1 When the control unit controls the adjusting unit to apply a pulling force to the top plate.

[0016] The MOCVD reaction chamber and the ceiling level adjustment method thereof of the present invention have the following beneficial effects compared with the prior art:

[0017] (1) The present invention determines whether the top plate is horizontal through the detection part, and feeds back the detection information to the control part, so that the control part controls the adjustment part to adjust the horizontal situation of the top plate according to the collected detection data. The adjustment parts distributed in various directions of the edge of the top plate apply an upward or downward force to the top plate to offset the horizontal imbalance of the top plate caused by the deformation of the edge of the top plate, solve the negative impact caused by the uneven surface of the top plate during the deposition process, and make the airflow field in the reaction chamber more balanced during growth.

[0018] (2) This patent ensures that the top plate surface is in a horizontal state during the growth process by adjusting the top plate in real time, ensuring a stable environment during the epitaxial growth process, reducing the concentration of by-products at the edge of the top plate, and making the by-products on the top plate more uniform, thereby reducing the shedding of by-products and improving the appearance quality of the epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the ceiling level adjustment method of the MOCVD reaction chamber of the present invention;

[0021] Figure 2 It is a structural schematic diagram of another embodiment of the MOCVD reaction chamber of the present invention;

[0022] Figure 3 It is a schematic diagram of the control part connected to the adjustment part and the detection part of the present invention;

[0023] Figure 4 A top view of the top plate of the present invention;

[0024] Figure 5 It is a top view of another embodiment of the top plate of the present invention.

[0025] In the figure: 1. top cover; 2. top plate; 3. adjustment part; 4. detection part; 41. detection unit; 5. control part; 6. ring body. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, combined Figure 3 An MOCVD reaction chamber of the present invention includes a top cover 1, a top plate 2, an adjustment part 3, a detection part 4 and a control part 5.

[0028] The top cover 1 is arranged on the top of the MOCVD reaction chamber and is generally made of an alloy material with rigidity and thermal stability that is not easily changed.

[0029] The top plate 2 is arranged at a distance just below the top cover 1. A component is connected between the top plate 2 and the top cover 1, and the component is cylindrical. The top plate 2 is the ceiling of the reaction chamber, which is generally made of graphite or quartz. A conveying mechanism is installed at the center of the lower surface of the top plate 2, which is responsible for the transportation of gas, MO source, etc. in the reaction chamber.

[0030] Several adjusting parts 3 are evenly distributed between the top plate 2 and the top cover 1 around the center of the top plate 2 surface. The adjusting parts 3 can be telescopic gas rods, hydraulic cylinders or hydraulic rods. Since the edge of the top plate 2 has a significant deformation, the two ends of the adjusting parts 3 are connected to the top cover 1 and the edge of the top plate 2 respectively. Each adjusting part 3 applies a force in the vertical direction of the top cover 1 surface. In essence, the adjusting part 3 will change the magnitude of the applied force by expanding and contracting in the length direction, thereby adjusting the distance between the top plate 2 and the top cover 1 where the adjusting parts 3 are located.

[0031] The detection unit 4 is arranged on the edge of the top plate 2 and detects in real time the distance between the top plate 2 and the top cover 1 at the position where the detection unit 4 is located. The detection unit 4 can adopt a photoelectric sensor to realize distance detection through a light emitting and reflected light receiving device.

[0032] The control unit 5 controls the magnitude of the force applied by the regulating unit 3 according to the detection data of the detection unit 4. The control unit 5 can be a single chip microcomputer or a PCB board, which has the functions of data reception and data processing, and controlling the opening and closing of the regulating unit 3, and is electrically connected to the detection unit 4 and the regulating unit 3.

[0033] After multiple furnaces of epitaxial growth, a layer of sediment with a stable structure, namely a coating layer, will be formed on the lower surface of the top plate 2. The coating layer has a certain tensile stress, and the gravity of the top plate 2 itself will cause the edge of the top plate 2 to deform downward significantly, resulting in the formation of byproducts such as reaction gas and MO aggregation near the edge of the top plate 2 during the epitaxial growth process. Figure 1 The shaded part in the figure below, as the number of epitaxial furnaces increases, the thickness of the coating layer increases, the stability of the by-products deteriorates, and they will fall off and contaminate the growing product during the epitaxial growth process, causing its appearance to deteriorate, and then the edge of the top plate 2 will deform downward more obviously. After adopting the above technical solution, after the detection unit 4 detects that the distance between the edge of the top plate 2 and the top cover 1 changes, the control unit 5 drives the adjustment unit 3 to contract and apply an upward pulling force to the top plate 2. The edge deformation of the top plate 2 is flattened under the action of the pulling force, and the lower surface of the top plate 2 returns to the state of a horizontal surface, thereby eliminating the negative impact caused by the horizontal imbalance of the top plate 1, and making the airflow field more balanced during growth in the reaction chamber.

[0034] exist Figure 4 In a preferred embodiment shown, in order to accurately detect the deformation of various parts of the top plate 2, the detection part 4 includes a detection unit 41.

[0035] Among them, a plurality of detection units 41 are evenly distributed around the center of the top plate 2 surface on the edge of the end surface of the top plate 2 facing the top cover 1; each detection unit 41 and each adjustment part 3 are arranged on the same radial axis of the top plate 2 in a one-to-one correspondence. When the edge of the top plate 2 at the position where the detection unit 41 is located is deformed downward, the distance between the edge of the top plate 2 at this position and the top cover 1 will change, and the detection unit 41 can accurately detect the change in distance; different positions of the edge of the top plate 2 have different distance changes, and the detection units 41 at the corresponding positions can perform accurate detection.

[0036] exist Figure 2 and Figure 5 In a preferred embodiment shown, since the conveying mechanism on the lower surface of the top plate 2 can uniformly spray the reaction gas to all sides, the deposition conditions of the edge parts of the top plate 2 are basically consistent, so that the downward deformation of the entire edge of the top plate 2 is also basically consistent. Therefore, this embodiment also includes a ring body 6.

[0037] Among them, the ring body 6 is arranged on the end surface of the top plate 2 facing the top cover 1; the center of the ring body 6 is coaxially arranged with the center of the top plate 2, and the maximum outer diameter of the ring body 6 is as close to the edge contour of the top plate 2 as possible; a plurality of adjustment parts 3 are evenly distributed on the ring body 6 and apply force synchronously, so that the entire edge of the top plate 2 can be pulled upward more consistently, so that the lower surface of the top plate 2 is more horizontal.

[0038] exist Figure 1 In a preferred embodiment shown in the figure, the control unit 5 controls the adjustment unit 3 to apply a force according to the detection data of the detection unit 4. The calculation formula is:

[0039] N=1 / (a×m×g×K)+N 0 ,

[0040] Wherein, a is the number of detection units 41; m is the mass of the top plate 2; and g is the gravitational acceleration.

[0041] K is the deformation distance coefficient of the top plate 2, which is expressed as the initial distance h from the top cover 1 when the top plate 2 is installed and leveled. 0 The measured distance h from the top cover 1 after the top plate 2 is deformed 1 The coefficient corresponding to the absolute value Δh of the difference. The calculation formula for the distance between the top plate 2 and the top cover 1 is,

[0042] h=t×c / 2,

[0043] Here, t is the time from the emission of light to the reception of reflected light by the detection unit 41 as a photoelectric sensor, and c is the speed of light.

[0044] N 0It is the compensation force for leveling the top plate 2 when it is installed, which is related to the natural horizontal degree of the top plate 2 when it is installed for the first time. Specifically, it is the upward pulling force to compensate for the influence of gravity on the top plate 2 after the first installation, or the downward thrust that needs to be applied artificially due to the large natural upward deformation of the top plate 2 when it is installed for the first time. Therefore, N 0 It is a man-made value.

[0045] exist Figure 1 In a preferred embodiment shown, specifically, the absolute value of Δh is less than 5 mm; assuming that every 0.5 mm in the absolute value of Δh is a value range, the absolute value of Δh includes n value ranges, and the deformation distance coefficient corresponding to each value range of the absolute value of Δh is,

[0046] K=0.1n,

[0047] For example, when the absolute value of Δh is 0-0.5 mm, K takes a value of 0.2; when the absolute value of Δh is 0.5-1 mm, K takes a value of 0.3; when the absolute value of Δh is 1-1.5 mm, K takes a value of 0.4, and so on. Different deformation conditions of the edge of the top plate 2 correspond to different deformation distance coefficients K of the top plate 2.

[0048] exist Figure 1 In a preferred embodiment shown, when the absolute value of Δh is greater than 5 mm, it indicates that too much byproduct has accumulated on the top plate 2 , so the control unit 5 system alarms to remind the operator to replace the top plate 2 or perform maintenance on the top plate 2 .

[0049] exist Figure 1 In a preferred embodiment shown in FIG. 1 , the edge of the top plate 2 may deform upward or downward according to different situations. Specifically, when h 0 >h 1 When K takes a negative value, the edge of the top plate 2 deforms upward; when h 0 <h 1 When , K takes a positive value, and the edge of the top plate 2 deforms downward.

[0050] exist Figure 1 In a preferred embodiment shown in the figure, the force applied by the adjusting portion 3 is a thrust toward the top cover 1 or a pull toward the top plate 2, and N is a positive number; when h 0 >h 1 When h 0 <h 1 When the force applied by the adjusting part 3 is a pulling force, N is a negative number. From practical experience, except when installing a new ceiling or a clean ceiling, N may take a negative value, and in other cases it is generally a positive value.

[0051] exist Figure 4In a preferred embodiment shown, the value of a is related to the number of detection units 41 set, and the value range of a is a positive integer from 4 to 16. If the number of detection units 41 is too small, it is impossible to accurately and effectively detect the deformation of the entire edge of the top plate 2, and if the number of detection units 41 is too large, it is not conducive to each adjustment part 3 to accurately control the reset of the edge of a certain part of the top plate 2.

[0052] like Figure 1 As shown, combined Figure 3 A method for adjusting the ceiling level of an MOCVD reaction chamber of the present invention adopts an MOCVD reaction chamber of any of the above embodiments and includes the following steps.

[0053] Step 1: When the top plate 2 is installed and leveled, the detection unit 4 detects the initial distance h between the top plate 2 and the top cover 1. 0 .

[0054] Step 2: When the top plate 2 is deformed, the detection unit 4 detects the distance h between the top plate 2 and the top cover 1. 1 .

[0055] Step 3: The control unit 5 determines h 0 >h 1 When h 0 <h 1 When , the control unit 5 controls the adjustment unit 3 to apply a pulling force to the top plate 2 .

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A MOCVD reaction chamber, characterized in that: include: A top cover (1) is arranged on the top of the MOCVD reaction chamber; A top plate (2) arranged at a distance just below the top cover (1); A plurality of adjusting parts (3) are evenly distributed around the center of the surface of the top plate (2) and between the top plate (2) and the top cover (1), the two ends of the adjusting parts (3) are respectively connected to the edge of the top cover (1) and the top plate (2), and each of the adjusting parts (3) applies a force in a vertical direction along the surface of the top cover (1) and adjusts the distance between the top plate (2) and the top cover (1) at the position where the adjusting parts (3) are located; A detection unit (4) is arranged on the edge of the top plate (2) and detects in real time the distance between the top plate (2) and the top cover (1) at its location; A control unit (5) controls the magnitude of the force applied by the adjustment unit (3) according to the detection data of the detection unit (4); Wherein, the detection unit (4) comprises: A plurality of detection units (41) are evenly distributed around the center of the surface of the top plate (2) and on the edge of the end surface of the top plate (2) facing the top cover (1); Wherein, each of the detection units (41) and each of the adjustment parts (3) are arranged on the same radial axis of the top plate (2) in a one-to-one correspondence; The control unit (5) controls the adjustment unit (3) to apply a force according to the detection data of the detection unit (4). The calculation formula is: N=1 / (a×m×g×K)+N0, Wherein, a is the number of the detection units (41); m is the mass of the top plate (2); g is the gravitational acceleration; K is the deformation distance coefficient of the top plate (2), which is expressed as the coefficient corresponding to the absolute value Δh of the difference between the initial distance h0 of the top plate (2) from the top cover (1) when it is installed and leveled and the measured distance h1 of the top plate (2) from the top cover (1) after deformation; and N0 is the compensation force for leveling the top plate (2) when it is installed.

2. The MOCVD reaction chamber according to claim 1, characterized in that: Also includes: A ring body (6) is arranged on the end surface of the top plate (2) facing the top cover (1); The center of the ring body (6) is coaxially arranged with the center of the top plate (2); and a plurality of the adjusting parts (3) are evenly distributed on the ring body (6) and apply force synchronously.

3. The MOCVD reaction chamber according to claim 1, characterized in that: The absolute value of Δh is less than 5mm. Assume that every 0.5mm in the absolute value of Δh is a value range, and the absolute value of Δh includes n value ranges. The deformation distance coefficient corresponding to each value range of the absolute value of Δh is, K=0.1n.

4. The MOCVD reaction chamber according to claim 3, characterized in that: When the absolute value of Δh is greater than 5 mm, the system alarms and replaces the top plate (2).

5. The MOCVD reaction chamber according to claim 3, characterized in that: When h0>h1, K takes a negative value; when h0<h1, K takes a positive value.

6. The MOCVD reaction chamber according to claim 1, characterized in that: The force applied by the adjusting portion (3) is a thrust in the direction of the top cover (1) or a pull in the direction of the top plate (2); when h0>h1, the force applied by the adjusting portion (3) is a thrust, and when h0<h1, the force applied by the adjusting portion (3) is a pull.

7. The MOCVD reaction chamber according to claim 1, characterized in that: The value of a is a positive integer between 4 and 16.

8. A method for adjusting the ceiling level of a MOCVD reaction chamber, characterized in that: Using an MOCVD reaction chamber as claimed in any one of claims 1 to 7, comprising the following steps: Step 1: when the top plate (2) is in an installed and leveled state, the detection unit (4) detects an initial distance h0 between the top plate (2) and the top cover (1); Step 2: when the top plate (2) is in a deformed state, the detection unit (4) detects a measured distance h1 between the top plate (2) and the top cover (1); Step three: when the control unit (5) determines that h0>h1, the control unit (5) controls the adjustment unit (3) to apply a thrust to the top plate (2); when the control unit (5) determines that h0<h1, the control unit (5) controls the adjustment unit (3) to apply a pulling force to the top plate (2).

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