A low-pressure chemical vapor deposition furnace air intake device

Abstract

The present invention discloses an air intake device for a low-pressure chemical vapor deposition furnace, comprising: a furnace body, wherein a gas mixing mechanism and a reaction mechanism are arranged in the furnace body; the gas mixing mechanism comprises a gas mixing tube; the reaction mechanism comprises an isolation plate; one side surface of the isolation plate is fixedly connected to the other end surface of the gas mixing tube; an outer tube is arranged in the furnace body; an inner tube is arranged inside the outer tube; one end of the inner tube and the outer tube are both fixedly connected to the other side surface of the isolation plate; a rear sealing assembly is fixedly connected to the other end of the inner tube and the outer tube; an annular channel is formed between the inner wall of the outer tube and the outer wall of the inner tube; a plurality of connecting holes are arranged in a circumferential array around the center of the isolation plate on the side surface of the isolation plate; the two ends of the connecting holes are respectively connected to the annular channel and the inner cavity of the gas mixing tube; a plurality of ventilation holes are spirally arranged on the outer wall of the inner tube along the axial direction; the apertures of the plurality of ventilation holes increase successively from the isolation plate to the rear sealing assembly.

Description

Technical Field

[0001] The invention relates to the field of LPCVD technology, and in particular to an air intake device for a low-pressure chemical vapor deposition furnace. Background Art

[0002] LPCVD (Low Pressure Chemical Vapor Deposition) equipment is a type of chemical vapor deposition (CVD) equipment that generates solid products through chemical reactions of mixed gases under low pressure and high temperature conditions and deposits them on the surface of silicon wafers to form thin films. It is mainly used in industries such as integrated circuits, power electronics, photovoltaics, and micro-electromechanical systems. In the photovoltaic industry, LPCVD is mainly used for the growth and deposition of various thin films such as polycrystalline silicon, amorphous silicon, SiO2, Si3N4, phosphosilicate glass (PSG), and boron-doped phosphosilicate glass (BPSG). As a type of CVD equipment, its most important function or ultimate goal is still the CVD reaction, so the reaction chamber is the core of the entire equipment and the core point of the design.

[0003] The existing technology uses LPCVD to produce poly-Si. The LPCVD equipment generates solid products through chemical reactions of mixed gases under low pressure and high temperature conditions and deposits them on the surface of silicon wafers to form thin films. It is a type of chemical vapor deposition (CVD) equipment. The core of the equipment is the CVD reaction, that is, the deposition reaction in the furnace tube. In order to carry out the deposition reaction, the LPCVD equipment often takes in air at the furnace mouth of the furnace tube and exhausts air at the furnace tail. However, when depositing poly-Si on silicon wafers in this way, the poly-Si deposited at the furnace mouth and furnace tail is often thin, and the deposition uniformity between silicon wafers in the furnace and within the wafers is quite different, which seriously affects the yield rate and battery efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide an air intake device for a low-pressure chemical vapor deposition furnace to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solution: The present invention provides a gas inlet device for a low-pressure chemical vapor deposition furnace, comprising: a furnace body, wherein a gas mixing mechanism and a reaction mechanism are arranged in the furnace body;

[0006] The gas mixing mechanism comprises a gas mixing pipe; the gas mixing pipe is arranged on one side of the furnace body; one end of the gas mixing pipe is fixedly connected to a front sealing assembly;

[0007] The reaction mechanism includes an isolation plate; one side of the isolation plate is fixedly connected to the other end face of the mixing tube; an outer tube is arranged in the furnace body; an inner tube is arranged inside the outer tube; one end of the inner tube and the outer tube are both fixedly connected to the other side of the isolation plate; the other ends of the inner tube and the outer tube are fixedly connected to a rear sealing assembly; an annular channel is formed between the inner wall of the outer tube and the outer wall of the inner tube; a plurality of connecting holes are arranged in a circumferential array around the center of the isolation plate on the side of the isolation plate; the two ends of the connecting holes are respectively connected to the annular channel and the inner cavity of the mixing tube; a plurality of ventilation holes are spirally arranged on the outer wall of the inner tube along the axial direction; the apertures of the plurality of ventilation holes increase successively from the isolation plate to the rear sealing assembly.

[0008] Preferably, the isolation plate is made of quartz material, which can play a role of high temperature resistance and prevent heat in the reaction mechanism from being transferred to the mixing mechanism; the inner cavity of the mixing tube is separated from the annular channel and the inner cavity of the inner tube by an isolation plate, and the gas enters the annular channel through the connecting hole opened on the isolation plate; the inner cavity of the inner tube is a process cavity, and the gas source enters the annular channel from the air inlet, and then enters the process cavity through the vent. Since the gas source enters the process cavity through the vent, the concentration of the gas source along the cavity is constantly decreasing, so the continuously enlarging vent can make the gas source distribution in the process cavity uniform and optimized; the vent is spirally distributed on the inner tube, and the gas source can be passed longitudinally between the silicon wafers to avoid gas retention between the wafers.

[0009] The front sealing assembly includes a first annular baffle; the first annular baffle is fixedly connected to the end face of one end of the furnace body; the inner wall of the first annular baffle is fixedly connected to the outer wall of the mixing pipe; the end face of the mixing pipe is fixedly connected with a fixed flange; the side of the fixed flange is fixedly connected with a front furnace door; and a spiral air inlet hole is arranged at the center of the side face of the front furnace door.

[0010] Preferably, the spiral air inlet hole can enhance the disturbance of the air source, so that the air source entering the inner cavity of the mixing pipe is more uniform.

[0011] A first sealing ring is fixedly connected between the first annular partition and the fixed flange; and a plurality of first cushion blocks are fixedly connected between the outer wall of the mixing pipe and the inner wall of the furnace body.

[0012] Preferably, the first cushion block can enhance the stability of the gas mixing pipe in the furnace body and enhance the connection strength.

[0013] The rear sealing assembly includes an inner flange; the inner flange is fixedly connected to the inner tube and the inner wall of the outer tube; a second annular baffle is fixedly connected to the other end of the furnace body; the inner wall of the second annular baffle is fixedly connected to the outer wall of the outer tube; a second sealing ring is fixedly connected to the side of the second annular baffle; an outer flange is fixedly connected to the side of the second sealing ring; one side of the outer flange is fixedly connected to the side of the second sealing ring and the other end face of the outer tube; a third sealing ring is fixedly connected to the other side of the outer flange; and an exhaust mechanism is fixedly connected to the side of the third sealing ring.

[0014] Preferably, the air tightness of the mixing pipe is enhanced by providing a fixed flange; and the air tightness between the inner pipe and the outer pipe is enhanced by providing an inner flange and an outer flange respectively.

[0015] The exhaust mechanism includes a rear furnace door; one side of the rear furnace door is fixedly connected to the third sealing ring; the other side of the rear furnace door is fixedly connected to an exhaust pump; the exhaust pump is connected to an exhaust pipe; the exhaust pipe passes through the rear furnace door and is connected to the inner cavity of the inner tube.

[0016] Preferably, an air pump is provided to extract the reaction gas in the inner tube.

[0017] The diameter of the connecting hole is 0.8mm-1.2mm, and the diameter of the exhaust pipe is 12mm-14mm.

[0018] The lengths of the inner tube and the outer tube are both 2.5m-3.5m; the diameter of the inner tube is 0.31m-0.33m; and the diameter of the outer tube is 0.3m-0.5m.

[0019] The inner wall of the outer tube is provided with a heat-insulating layer.

[0020] Preferably, the provided insulation layer can prevent heat loss in the reaction mechanism.

[0021] The inner wall of the thermal insulation layer is provided with a water cooling layer.

[0022] Preferably, the water cooling layer can quickly and evenly reduce the temperature in the reaction mechanism after the reaction is completed.

[0023] A plurality of second cushion blocks are fixedly connected between the outer wall of the outer tube and the inner wall of the furnace body; and a plurality of third cushion blocks are fixedly connected between the outer wall of the inner tube and the inner wall of the outer tube.

[0024] Preferably, the second spacer block can enhance the connection strength between the outer tube and the furnace body, and the third spacer block can enhance the connection strength between the inner tube and the outer tube.

[0025] The present invention discloses the following technical effects: since a gas mixing chamber is added to the front section of the furnace body, the gas will enter the inner cavity of the gas mixing tube through the spiral air inlet before entering the reaction mechanism. The spiral air inlet can enhance the disturbance of the gas source, and the gas source entering the inner cavity of the gas mixing tube is more uniform. The temperature in the gas mixing tube is lower, and the gas mixing does not react. In addition, due to the existence of the gas mixing mechanism, the gas source entering the reaction mechanism is more uniform. In addition, since the horizontal air supply is changed to the longitudinal air supply, the influence of the spacing of the silicon wafers in the graphite boat on the uniformity between the wafers is reduced, the spacing of the silicon wafers can be shortened, the capacity of the graphite boat can be increased, and the working efficiency of the LPCVD can be greatly improved; in the traditional tubular LPCVD, the gas source comes in from the air inlet, flows through the entire furnace cavity, and is discharged from the air outlet, so different positions and reaction temperatures also have a certain influence on the uniformity within the wafer. In the part near the furnace mouth, the source supply is sufficient, and the concentration of each point in the silicon wafer is relatively consistent. However, in the furnace tail part, due to the consumption of the front reaction, the air source concentration is low, making it difficult for the source concentration of each point on the silicon wafer surface to reach equilibrium, and the high reaction temperature strengthens this result, resulting in an increase in the non-uniformity from the furnace mouth to the furnace tail. The front and rear uniform air supply achieved by the present invention can effectively avoid the dissipation effect, achieve uniform front and rear temperatures, avoid the non-uniformity of front and rear silicon wafer deposition, and improve the thermal deformation of the silicon wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 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 labor.

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 It is a partial enlarged view of A1 of the present invention;

[0029] Figure 3 It is a structural schematic diagram of the inner tube of the present invention;

[0030] Figure 4 It is a schematic diagram of the structure of the spiral air inlet of the present invention;

[0031] Among them, 1-furnace body, 2-mixing pipe, 3-isolation plate, 4-outer pipe, 5-inner pipe, 6-annular channel, 7-connecting hole, 8-vent, 9-first annular partition, 10-fixed flange, 11-front furnace door, 12-spiral air inlet, 13-first sealing ring, 14-first pad, 15-inner flange, 16-second annular partition, 17-second sealing ring, 18-outer flange, 19-third sealing ring, 20-rear furnace door, 21-exhaust pump, 22-exhaust pipe, 23-insulation layer, 24-water cooling layer, 25-second pad, 26-third pad. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in 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.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] The present invention provides a low-pressure chemical vapor deposition furnace gas intake device, comprising: a furnace body 1, wherein a gas mixing mechanism and a reaction mechanism are arranged in the furnace body 1;

[0035] The gas mixing mechanism comprises a gas mixing pipe 2; the gas mixing pipe 2 is arranged on one side of the furnace body; one end of the gas mixing pipe 2 is fixedly connected to a front sealing component;

[0036] The reaction mechanism includes an isolation plate 3; one side of the isolation plate 3 is fixedly connected to the other end face of the mixing tube 2; an outer tube 4 is arranged in the furnace body 1; an inner tube 5 is arranged in the outer tube 4; one end of the inner tube 5 and the outer tube 4 are both fixedly connected to the other side of the isolation plate 3; the inner tube 5 and the other end of the outer tube 4 are fixedly connected with a rear sealing assembly; an annular channel 6 is formed between the inner wall of the outer tube 4 and the outer wall of the inner tube 5; a plurality of connecting holes 7 are arranged in a circumferential array around the center of the isolation plate 3 on the side of the isolation plate 3; the two ends of the connecting holes 7 are respectively connected to the annular channel 6 and the inner cavity of the mixing tube 2; a plurality of ventilation holes 8 are spirally opened on the outer wall of the inner tube 5 along the axial direction; the apertures of the plurality of ventilation holes 8 increase successively from the isolation plate 3 to the rear sealing assembly.

[0037] The inner tube 5 and the outer tube 4 are both made of quartz.

[0038] The inner tube 5 is connected to the outer tube 4 only through the vent hole 8 .

[0039] The front sealing assembly includes a first annular baffle 9; the first annular baffle 9 is fixedly connected to the end face of one end of the furnace body 1; the inner wall of the first annular baffle 9 is fixedly connected to the outer wall of the mixing pipe 2; a fixing flange 10 is fixedly connected to the end face of the mixing pipe 2; a front furnace door 11 is fixedly connected to the side of the fixing flange 10; a spiral air inlet hole 12 is provided at the center of the side of the front furnace door 11.

[0040] A first sealing ring 13 is fixedly connected between the first annular partition plate 9 and the fixing flange 10 ; and a plurality of first cushion blocks 14 are fixedly connected between the outer wall of the mixing pipe 2 and the inner wall of the furnace body.

[0041] The rear sealing assembly includes an inner flange 15; the inner flange 15 is fixedly connected to the inner tube 5 and the inner wall of the outer tube 4; a second annular baffle 16 is fixedly connected to the other end of the furnace body 1; the inner wall of the second annular baffle 16 is fixedly connected to the outer wall of the outer tube 4; a second sealing ring 17 is fixedly connected to the side of the second annular baffle 16; an outer flange 18 is fixedly connected to the side of the second sealing ring 17; one side of the outer flange 18 is fixedly connected to the side of the second sealing ring 17 and the other end face of the outer tube 4; a third sealing ring 19 is fixedly connected to the other side of the outer flange 18; and an exhaust mechanism is fixedly connected to the side of the third sealing ring 19.

[0042] The exhaust mechanism includes a rear furnace door 20; one side of the rear furnace door 20 is fixedly connected to the third sealing ring 19; the other side of the rear furnace door 20 is fixedly connected to an exhaust pump 21; the exhaust pump 21 is connected to an exhaust pipe 22; the exhaust pipe 22 passes through the rear furnace door 20 and is connected to the inner cavity of the inner tube 5.

[0043] The diameter of the connecting hole 7 is 0.8 mm-1.2 mm, and the diameter of the exhaust pipe 22 is 12 mm-14 mm.

[0044] The projection distance of the center of the vent hole 8 opened on the inner tube 5 along the direction of the furnace body 1 is 20 mm.

[0045] The lengths of the inner tube 5 and the outer tube 4 are both 2.5m-3.5m; the diameter of the inner tube 5 is 0.31m-0.33m; and the diameter of the outer tube 4 is 0.3m-0.5m.

[0046] The inner wall of the outer tube 4 is provided with a heat-insulating layer 23 .

[0047] The inner wall of the thermal insulation layer 23 is provided with a water cooling layer 24 .

[0048] The heating of the furnace body 1 is segmented heating, the temperature of the gas mixing mechanism in the front half is lower, and the temperature of the reaction mechanism in the rear half is higher; the segmented heating of the furnace body 1 can ensure that the gas source does not react in the gas mixing mechanism and complete the deposition effect in the reaction mechanism.

[0049] The heating area of ​​the furnace body 1 is limited to the reaction mechanism area, and the gas mixing mechanism in the front half is in the low temperature section.

[0050] A plurality of second cushion blocks 25 are fixedly connected between the outer wall of the outer tube 4 and the inner wall of the furnace body 1 ; a plurality of third cushion blocks 26 are fixedly connected between the outer wall of the inner tube 5 and the inner wall of the outer tube 4 .

[0051] Example 1

[0052] The opening of the spiral air inlet 12 increases in diameter from the outside of the furnace body 1 to the inner cavity of the mixing tube 2, and a number of spiral grooves are provided on the wall of the spiral air inlet 12. The gas first passes through the spiral air inlet 12, which can enhance the disturbance of the gas, and the gas can be evenly distributed in the mixing tube 2. Then, the gas enters the annular channel 6 through the connecting hole 7 on the isolation plate 3, and then enters the process chamber through the gradually changing air holes 8 on the inner tube 5 for reaction. It enables the gas to pass longitudinally into the interval between the wafers, avoiding the problem of gas accumulation between wafers in the previous conventional LPCVD equipment, and improving the deposition effect of the silicon wafer. At the same time, it can effectively reduce the problems caused by the dissipation effect, and avoid considering the setting of the temperature increase at the front, middle and rear ends of the furnace body 1.

[0053] Example 2

[0054] The area of ​​the vent hole 8 is gradually increased, and the area of ​​the vent hole 8 at the end of the furnace is 2-4 times the area of ​​the vent hole 8 at the beginning of the furnace. In this way, the gas with a lower concentration at the end of the outer tube 4 can be passed into the process chamber more quickly, effectively avoiding the dissipation effect.

[0055] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A low-pressure chemical vapor deposition furnace air intake device, characterized in that: It comprises: a furnace body (1), wherein a gas mixing mechanism and a reaction mechanism are arranged in the furnace body (1); The gas mixing mechanism comprises a gas mixing pipe (2); the gas mixing pipe (2) is arranged on one side of the furnace body; one end of the gas mixing pipe (2) is fixedly connected to a front sealing component; The reaction mechanism comprises an isolation plate (3); one side of the isolation plate (3) is fixedly connected to the other end face of the mixing tube (2); an outer tube (4) is arranged inside the furnace body (1); an inner tube (5) is arranged inside the outer tube (4); one end of the inner tube (5) and the outer tube (4) are both fixedly connected to the other side face of the isolation plate (3); a rear sealing assembly is fixedly connected to the other end of the inner tube (5) and the outer tube (4); an annular channel (6) is formed between the inner wall of the outer tube (4) and the outer wall of the inner tube (5); a plurality of connecting holes (7) are arranged in an array around the center of the isolation plate (3) on the side face of the isolation plate (3); two ends of the connecting holes (7) are respectively connected to the annular channel (6) and the inner cavity of the mixing tube (2); a plurality of ventilation holes (8) are spirally opened on the outer wall of the inner tube (5) along the axial direction; the apertures of the plurality of ventilation holes (8) increase in sequence from the isolation plate (3) to the rear sealing assembly; The front sealing assembly comprises a first annular baffle (9); the first annular baffle (9) is fixedly connected to an end face of the furnace body (1); the inner wall of the first annular baffle (9) is fixedly connected to the outer wall of the mixing pipe (2); a fixing flange (10) is fixedly connected to the end face of the mixing pipe (2); a front furnace door (11) is fixedly connected to the side of the fixing flange (10); a spiral air inlet hole (12) is arranged at the center of the side face of the front furnace door (11); the diameter of the spiral air inlet hole (12) increases from the outside of the furnace body (1) to the inner cavity of the mixing pipe (2); a plurality of spiral grooves are arranged on the wall of the spiral air inlet hole (12); the gas first passes through the spiral air inlet hole (12); the spiral air inlet hole (12) can strengthen the disturbance of the gas, and the gas can be evenly distributed in the mixing pipe (2); The rear sealing assembly comprises an inner flange (15); the inner flange (15) is fixedly connected to the inner wall of the inner tube (5) and the outer tube (4); a second annular baffle (16) is fixedly connected to the other end of the furnace body (1); the inner wall of the second annular baffle (16) is fixedly connected to the outer wall of the outer tube (4); a second sealing ring (17) is fixedly connected to the side surface of the second annular baffle (16); an outer flange (18) is fixedly connected to the side surface of the second sealing ring (17); one side of the outer flange (18) is fixedly connected to the side surface of the second sealing ring (17) and the other end surface of the outer tube (4); A third sealing ring (19) is fixedly connected to the other side of the outer flange (18); and a vacuum mechanism is fixedly connected to the side of the third sealing ring (19); The diameter of the connecting hole (7) is 0.8 mm to 1.2 mm, and the diameter of the exhaust pipe (22) is 12 mm to 14 mm; The lengths of the inner tube (5) and the outer tube (4) are both 2.5 m to 3.5 m; the diameter of the inner tube (5) is 0.31 m to 0.33 m; and the diameter of the outer tube (4) is 0.3 m to 0.5 m.

2. The low-pressure chemical vapor deposition furnace air intake device according to claim 1, characterized in that: A first sealing ring (13) is fixedly connected between the first annular partition plate (9) and the fixed flange (10); and a plurality of first cushion blocks (14) are fixedly connected between the outer wall of the mixing pipe (2) and the inner wall of the furnace body.

3. The low-pressure chemical vapor deposition furnace air intake device according to claim 1, characterized in that: The exhaust mechanism comprises a rear furnace door (20); one side of the rear furnace door (20) is fixedly connected to the third sealing ring (19); the other side of the rear furnace door (20) is fixedly connected to an exhaust pump (21); the exhaust pump (21) is connected to an exhaust pipe (22); the exhaust pipe (22) passes through the rear furnace door (20) and is connected to the inner cavity of the inner tube (5).

4. The low-pressure chemical vapor deposition furnace air intake device according to claim 1, characterized in that: The inner wall of the outer tube (4) is provided with a heat-insulating layer (23).

5. The low-pressure chemical vapor deposition furnace air intake device according to claim 4, characterized in that: The inner wall of the thermal insulation layer (23) is provided with a water cooling layer (24).

6. The low-pressure chemical vapor deposition furnace air intake device according to claim 1, characterized in that: A plurality of second cushion blocks (25) are fixedly connected between the outer wall of the outer tube (4) and the inner wall of the furnace body (1); and a plurality of third cushion blocks (26) are fixedly connected between the outer wall of the inner tube (5) and the inner wall of the outer tube (4).

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