A CVD coating device and its coating method and application

Abstract

The present invention relates to a CVD coating device, comprising a combined air inlet disposed within the coating chamber, the combined air inlet comprising a first air inlet with a fixed width and a second air inlet with an adjustable width, both having the same initial width D; the second air inlet being close to the substrate; wherein nitrogen is pre-divided into a first nitrogen gas, a second nitrogen gas, and a third nitrogen gas, which are respectively fed into the first air inlet, a transition zone, and the second air inlet, and the temperature of the gas in the transition zone is kept below the lower limit temperature T that triggers the CVD reaction; deposits from the CVD reaction are evenly distributed on the surface of the second air inlet; when deposits accumulate to the point where the width of the second air inlet is less than the lower limit allowed by the coating process, the width of the second air inlet is adjusted until the initial width D is restored. The present invention effectively extends the duration of coating; and, without increasing the total amount of nitrogen, the second and third nitrogen gases are separated to cool the air inlet, greatly improving nitrogen utilization efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of CVD coating, and in particular relates to a CVD coating device, a coating method and an application thereof. Background Art

[0002] Chemical vapor deposition (CVD) is a common method for coating substrate surfaces. This method requires the high temperature of the substrate to cause a precursor gas containing the elements that make up the thin film to react on the substrate surface. The solid-phase products of the reaction are deposited on the substrate surface, forming a thin film. The reaction apparatus is often a coater, which includes at least one inlet and one exhaust. The inlet is typically designed as a narrow, downward-facing slit across the top of the substrate. Nitrogen gas carries the precursor gas from the inlet into the coating chamber, where the CVD reaction occurs. The reaction exhaust is then discharged from the coating chamber through the exhaust.

[0003] The drawback of the existing technology is that the continuous coating time is short. Usually, after 12 to 72 hours of continuous coating, the air inlet opening of the coater will be blocked. The reason is that in order to take advantage of the high temperature of the substrate and improve the utilization rate of the gas, the opening of the air inlet is usually very close to the hot substrate surface, making the opening area of ​​the air inlet very easily heated by the hot substrate, so that the reaction gas is easily heated to a temperature exceeding the minimum temperature of the CVD reaction as soon as it exits the lower port of the air inlet. As a result, deposition occurs not only on the substrate surface, but also at the air inlet opening. The width of the air inlet opening is fixed and the width value is also limited. As the coating process continues, the air inlet opening will gradually narrow or even become blocked, causing the coating production to be interrupted. The production can only be resumed by stopping the machine to clean the air inlet opening, which greatly shortens the coating duration. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a CVD coating device and a coating method and application thereof. The specific technical solutions are as follows:

[0005] The present invention provides a CVD coating device, comprising a coating apparatus consisting of a coating chamber and an exhaust duct, and a substrate to be coated located directly below the coating apparatus. The device also comprises a combined air inlet disposed in the coating chamber, for delivering external nitrogen and precursor gas into the coating chamber; the combined air inlet comprises a first air inlet with a fixed air width and a second air inlet with an adjustable air width, and both have the same initial width D; the first air inlet and the second air inlet are vertically connected to each other, and the second air inlet is close to the substrate;

[0006] The nitrogen gas is pre-divided into a first nitrogen gas, a second nitrogen gas, and a third nitrogen gas, which are respectively fed into the first air inlet, a transition zone between the first and second air inlets, and the second air inlet, and the temperature of the gas in the transition zone is made lower than the lower limit temperature T for triggering the CVD reaction; and the deposits from the CVD reaction are uniformly distributed on the surface of the second air inlet. When the deposits accumulate to the point where the width of the second air inlet is less than the lower limit allowed by the coating process, the width of the second air inlet is adjusted until the initial width D is restored.

[0007] As a preferred technical solution of the present invention, the first air inlet duct is a slit opening downward; a pair of first nitrogen pipes with opposing nozzles are distributed on both sides of the transition zone; a pair of first rollers, a pair of second nitrogen pipes with opposing nozzles, and a pair of second rollers are distributed on both sides of the second air inlet duct from top to bottom; the initial distance between the circumferential surfaces on the line connecting the centers of the first and second rollers is the initial width D.

[0008] As a preferred technical solution of the present invention, the two ends of the first roller and the second roller are respectively rotatably connected to the side wall through the first bearing and the second bearing arranged on the side wall of the coating chamber, and the first bearing and the second bearing are both slidably connected to the side wall in parallel to the moving direction of the substrate.

[0009] As a preferred technical solution of the present invention, the first roller and the second roller rotate at a uniform speed, and the rotation direction is consistent with the airflow direction in the second air inlet duct.

[0010] The present invention also provides a CVD film coating method, which includes the CVD film coating device as described above;

[0011] The method comprises the following steps:

[0012] Step S1, pre-dividing the nitrogen into the first nitrogen, the second nitrogen and the third nitrogen according to the volume ratio of (1-5): (70-95): (5-25) under standard conditions;

[0013] Step S2: heating the first nitrogen gas to the same temperature T1 as the precursor gas, mixing the first nitrogen gas with the precursor gas to form a first mixed gas with a temperature T1, and then feeding the first mixed gas into the first gas inlet duct and then into the transition zone;

[0014] Step S3: After cooling the second nitrogen gas to a temperature lower than T2, the second nitrogen gas is fed into the transition zone through the first nitrogen pipe, mixed with the first mixed gas to form a second mixed gas, and introduced into the second gas inlet channel through the first roller conveyor; the temperature of the second mixed gas in the transition zone is T4, and the temperature T4 is controlled to be lower than the lower limit temperature T for triggering the CVD reaction by controlling relevant parameters including the second nitrogen gas being lower than the temperature T2;

[0015] Step S4: After cooling the third nitrogen gas to a temperature lower than T3, the third nitrogen gas is fed into the second gas inlet through the second nitrogen pipe, mixed with the second mixed gas to form a third mixed gas, and guided toward the substrate via the second roller conveyor; by controlling relevant parameters, including the second nitrogen gas being lower than T2 and the third nitrogen gas being lower than T3, the temperature T4 of the second mixed gas in the transition zone is lower than the lower limit temperature T for triggering the CVD reaction;

[0016] Step S5: After the third mixed gas enters the coating chamber from the second gas inlet, it is heated by the substrate to a temperature T5, such that the temperature T5 is greater than or equal to the lower limit temperature T, triggering a CVD reaction to deposit a thin film on the substrate surface; deposition may also occur on the surface of the first roller or the second roller;

[0017] Step S6. When the thickness of the deposits on the surface of the first roller or the second roller accumulates to the point where the distance between the deposit surfaces on the line connecting the centers of the two first rollers or the second rollers is less than the lower limit allowed by the coating process, the corresponding first bearing or the second bearing will slide outward in a direction parallel to the movement of the substrate until the initial air inlet width D required for the coating process is restored.

[0018] As a preferred technical solution of the present invention, a first cavity is provided inside the coater, and the first cavity is connected to an external refrigeration device through a pipeline. The external refrigeration device passes first cooling water into the first cavity, controls the flow rate of the first cooling water, and makes the temperature of the first cooling water not exceed T2 when it returns to the refrigeration device. The first cooling water then returns to the refrigeration device to be cooled and recirculates into the first cavity.

[0019] The first gas supply main pipe is not immersed in the first cooling water in the first cavity. The first nitrogen pipe is a branch pipe arranged on the first gas supply main pipe and has an opening pointing to the transition zone. By increasing the stroke of the first gas supply main pipe in the first cavity, the first nitrogen is cooled to a temperature lower than T2, and then fed into the transition zone through the first nitrogen pipe, mixed with the first mixed gas to form the second mixed gas, and then introduced into the second air inlet duct through the first roller.

[0020] As a preferred technical solution of the present invention, a second cavity is provided inside the coater, and the second cavity is connected to an external refrigeration device through a pipeline. The external refrigeration device passes second cooling water into the second cavity, controls the flow rate of the second cooling water, and makes the temperature of the second cooling water not exceed T3 when it returns to the refrigeration device. The second cooling water then returns to the refrigeration device to be cooled and recirculates into the second cavity.

[0021] The second main gas supply pipe is immersed in the second cooling water in the second chamber. The second nitrogen pipe is a branch pipe arranged on the second gas supply pipe and has an opening pointing to the second gas inlet channel. By increasing the stroke of the second gas supply pipe in the second chamber, the second nitrogen is cooled to a temperature lower than T3, and then fed into the second gas inlet channel through the second nitrogen pipe, mixed with the second mixed gas to form the third mixed gas, and then guided toward the substrate through the second roller.

[0022] As a preferred technical solution of the present invention, the extension line of the first nitrogen pipe nozzle is close to the circumferential surface corresponding to the upper end of the first roller; the extension line of the second nitrogen pipe nozzle is close to the circumferential surface corresponding to the upper end of the second roller.

[0023] As a preferred technical solution of the present invention, the precursor gas contains tin, an element constituting a low-emissivity film.

[0024] The present invention also provides an application of the above-mentioned CVD coating method in the online coating production of float glass.

[0025] The beneficial effects of the present invention are:

[0026] The CVD coating device of the present invention configures the original air inlet into a combined air inlet, so that the first air inlet with a fixed opening width is away from the hot substrate, while the second air inlet with an adjustable air channel width is close to the hot substrate. In this way, the deposits from the CVD reaction will preferentially deposit on the surface of the second air inlet.

[0027] Then, by delivering temperature-controlled cold nitrogen gas to the transition zone and the second air inlet, respectively, and bringing the cold nitrogen gas close to the circumferential surfaces of the first and second rollers, the first and second rollers are cooled, reducing the heat transfer from the substrate from the second roller to the first roller, and then from the first roller to the opening of the first air inlet. Ultimately, the temperature of the gas in the transition zone is lower than the lower limit temperature T that triggers the CVD reaction, thus avoiding the occurrence of the CVD reaction in the opening area of ​​the first air inlet, and effectively preventing the narrowing and clogging of the air inlet opening with a fixed width.

[0028] Then, by making the first roller and the second roller rotate at a uniform speed, and by the synergistic effect of the second mixed gas, the third mixed gas, the first nitrogen gas, and the second nitrogen gas, the sediment can be distributed on the circumferential surfaces of the first roller and the second roller with a uniform thickness;

[0029] The width of the second air inlet duct is adjustable by sliding the bearings at both ends of the first and second rollers to the sidewalls of the coating chamber parallel to the substrate movement direction. When the thickness of the deposits on the surfaces of the first and second rollers accumulates to a point where the width of the second air inlet duct is less than the lower limit allowed by the coating process, the initial air inlet duct width D required by the coating process can be restored by simply sliding the corresponding bearings outward without interrupting the coating process, effectively extending the coating duration.

[0030] In addition, the present invention separates the second nitrogen and the third nitrogen to cool the air intake duct without increasing the total amount of nitrogen, thereby greatly improving the utilization efficiency of nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a CVD coating device in the prior art is shown;

[0032] Figure 2 Shown Figure 1 A partial enlarged view of the middle I part;

[0033] Figure 3 It shows a schematic structural diagram of the CVD coating device of the present invention;

[0034] Figure 4 Shown Figure 3 Schematic diagram of the structure in the AA direction;

[0035] Figure 5 The first roller and the second roller in the present invention are shown in FIG.

[0036] Figure 6 A schematic structural diagram (II) of the first roller and the second roller in the present invention is shown.

[0037] As shown in the figure: 1. Coater; 10. Substrate; 11. Air inlet; 12. Exhaust duct; 13. Air inlet opening; 14. Sediment; 2. Combined air inlet; 20. Transition zone; 21. First air inlet; 22. Second air inlet; 3. Coating chamber; 31. Side wall; 4. First nitrogen pipe; 41. First cavity; 42. First air supply main; 5. First roller; 51. First bearing; 6. Second nitrogen pipe; 61. Second cavity; 62. Second air supply main; 7. Second roller; 71. Second bearing. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] In order to solve the technical problems in the background technology, a CVD coating device is provided as follows:

[0040] like Figure 3 As shown, a CVD coating device includes a coating device 1 consisting of a coating chamber 3 and an exhaust duct 12, and a substrate 10 to be coated located directly below the coating device 1. The device also includes a combined air inlet duct 2 disposed in the coating chamber 3, which is used to deliver external nitrogen and precursor gas into the coating chamber 3; the combined air inlet duct 2 includes a first air inlet duct 21 with a fixed air inlet width and a second air inlet duct 22 with an adjustable air inlet width, and the two have the same initial width D; the first air inlet duct 21 and the second air inlet duct 22 are vertically connected to each other, and the second air inlet duct 22 is close to the substrate 10;

[0041] The nitrogen gas is pre-divided into a first nitrogen gas, a second nitrogen gas, and a third nitrogen gas, which are respectively fed into the first air inlet 21, the transition zone 20 between the first air inlet 21 and the second air inlet 22, and the second air inlet 22, and the temperature of the gas in the transition zone 20 is lower than the lower limit temperature T for triggering the CVD reaction; and the deposits 14 of the CVD reaction are uniformly distributed on the surface of the second air inlet 22. When the deposits 14 accumulate to the point where the width of the second air inlet 22 is less than the lower limit allowed by the coating process, the width of the second air inlet 22 is adjusted until the initial width D is restored.

[0042] like Figures 3 to 6 As shown, the first air inlet duct 21 is a slit opening downward; a pair of first nitrogen pipes 4 with nozzles facing each other are distributed on both sides of the transition zone 20; a pair of first rollers 5, a pair of second nitrogen pipes 6 with nozzles facing each other, and a pair of second rollers 7 are distributed on both sides of the second air inlet duct 22 from top to bottom; the initial distance between the circumferential surfaces on the line connecting the centers of the first rollers 5 and the second rollers 7 is the initial width D.

[0043] like Figure 3 and 4 As shown, the two ends of the first roller 5 and the second roller 7 are rotatably connected to the side wall 31 through a first bearing 51 and a second bearing 71 respectively provided on the side wall 31 of the coating chamber 3, and the first bearing 51 and the second bearing 71 are both slidably connected to the side wall 31 in parallel with the moving direction of the substrate 10.

[0044] like Figure 3 As shown, the first roller 5 and the second roller 7 rotate at a uniform speed, and the rotation direction is consistent with the air flow direction in the second air inlet duct 22.

[0045] By adopting the above technical solution, the CVD coating device is configured to replace the original air inlet 11 with a combined air inlet 2, so that the first air inlet 21 with a fixed opening width is away from the hot substrate 10, while the second air inlet 22 with an adjustable air inlet width is close to the hot substrate 10. In this way, the deposit 14 of the CVD reaction will preferentially deposit on the surface of the second air inlet 22.

[0046] Then, by sending the temperature-controlled cold nitrogen gas to the transition zone 20 and the second air inlet 22 respectively, and making the cold nitrogen gas close to the circumferential surfaces of the first roller 5 and the second roller 7, the first roller 5 and the second roller 7 are cooled, and the heat transfer from the substrate 10 from the second roller 7 to the first roller 5 and then from the first roller 5 to the opening of the first air inlet 21 is reduced. Finally, the temperature of the gas in the transition zone 20 is lower than the lower limit temperature T that triggers the CVD reaction, thereby avoiding the CVD reaction from occurring in the opening area of ​​the first air inlet 21, and effectively preventing the narrowing and clogging of the air inlet opening 13 with a fixed width;

[0047] Then, by rotating the first roller 5 and the second roller 7 at a uniform speed and by the synergistic effect of the second mixed gas, the third mixed gas, the first nitrogen gas, and the second nitrogen gas, the sediment 14 can be distributed on the circumferential surfaces of the first roller 5 and the second roller 7 with a uniform thickness;

[0048] The width of the second air inlet 22 is adjustable by sliding the bearings at both ends of the first roller 5 and the second roller 7 to the side wall 31 of the coating chamber 3 in a direction parallel to the movement of the substrate 10. When the thickness of the deposits 14 accumulated on the surfaces of the first roller 5 and the second roller 7 reaches a level that makes the width of the second air inlet 22 smaller than the lower limit allowed by the coating process, the initial air inlet width D required by the coating process can be restored by simply sliding the corresponding bearings outward without interrupting the coating process, effectively extending the coating duration.

[0049] In addition, the device separates the second nitrogen and the third nitrogen to cool the air intake without increasing the total amount of nitrogen, which greatly improves the utilization efficiency of nitrogen.

[0050] Online coating of float glass is a typical CVD coating method, which will be explained below using online coating of float glass as an example.

[0051] like Figure 1The figure shows an apparatus for producing float online coated glass using the prior art CVD coating method, comprising a coater 1, provided with an air inlet 11 and an exhaust 12, the openings of which both extend into the coating chamber 3; a substrate 10 made of glass, placed in the coating chamber 3, and moving to the right in the figure; the air inlet 11 spans above the substrate 10, and is a downward-opening slit with a fixed spacing D; nitrogen carrying the precursor gas enters the coating chamber 3 from the air inlet 11 in the form of a mixed gas, and is then heated by the hot substrate 10 to a temperature exceeding the lower limit temperature T of the CVD reaction, triggering the CVD reaction and depositing a thin film on the surface of the substrate 10, and the reaction exhaust is discharged from the coating chamber 3 from the exhaust 12. In the prior art, in order to take advantage of the heat of the substrate 10 and improve gas utilization, the air inlet opening 13 is usually very close to the substrate 10, and the distance H between the air inlet opening 13 and the substrate 10 is usually 10 to 100 mm, so that the air inlet opening 13 area is very easily heated by the hot substrate 10, and the reaction gas is easily heated to a temperature exceeding the lower limit of the CVD reaction just after leaving the air inlet opening 13. Therefore, deposition occurs not only on the surface of the substrate 10, but also at the position of the air inlet opening 13. The width D of the air inlet opening 13 is fixed and the width value is also limited. As the coating process continues, the air inlet opening 13 will gradually narrow or even be blocked, thereby interrupting the coating production. The machine can only be shut down to clean the air inlet opening and remove the deposits 14 before resuming production.

[0052] Figure 3 and Figure 4 The present invention is a CVD coating device for producing float online coated glass, comprising a coating device 1, provided with a combined air inlet 2, comprising a first air inlet 21 with a fixed air inlet width and a second air inlet 22 with an adjustable air inlet width. The first and second air inlet 21 have the same initial width D, and the second air inlet 22 is closer to the substrate 10. The space between the first air inlet 21 and the second air inlet 22 constitutes a transition zone 20.

[0053] In this embodiment, the first air inlet channel 21 is a downwardly opening slit with a fixed spacing D, and has the same width and structure as the air inlet channel 11 of the prior art, except that the vertical height is reduced, so that the opening of the first air inlet channel 21 is away from the substrate 10;

[0054] A pair of first nitrogen pipes 4 with nozzles facing each other are distributed on both sides of the transition zone 20; a pair of first rollers 5, a pair of second nitrogen pipes 6 with nozzles facing each other, and a pair of second rollers 7 are distributed on both sides of the second air inlet duct 22 from top to bottom. The initial distance between the circumferential surfaces of the first rollers 5 and the second rollers 7 on the line connecting the centers of the circles is the initial width D of the second air inlet duct 22; the ends of the first rollers 5 and the second rollers 7 are respectively connected to the side wall 31 of the coating chamber 3 through first bearings 51 and second bearings 71 provided on the side wall 31. The first bearings 51 and the second bearings 71 are both connected to the side wall 31 in a sliding manner parallel to the moving direction of the substrate 10. The first rollers 5 and the second rollers 7 rotate at a constant speed, and the rotation direction is consistent with the airflow direction in the second air inlet duct 22;

[0055] The distance between the lower end of the circumference of the second roller 7 and the substrate 10 is the same as the distance between the air inlet opening 13 and the substrate 10 in the prior art, both being H, so that the opening of the second air inlet 22 is close to the substrate 10 .

[0056] The present invention provides a CVD coating method for online coating production of float glass. In this embodiment, a precursor gas containing tin, an element constituting a low-emissivity film, is used. The temperature T1 of the precursor gas is 180°C, the trigger temperature T of the CVD reaction is 620°C, the moving speed of the float glass is 0.15m / s, the width of the glass plate is 4m, and the volume of the required precursor gas under standard conditions is 6Nm 3 / h, the volume of nitrogen required under standard conditions is 200Nm 3 / h;

[0057] The method comprises the following steps:

[0058] Step S1, referring to the volume ratio under standard conditions (1-5): (70-95): (5-25), pre-divide the nitrogen into three parts at a ratio of 2:85:13, and prepare the first nitrogen 4Nm 3 / h, second nitrogen 170Nm 3 / h and the third nitrogen 26Nm 3 / h;

[0059] Step S2: After heating the first nitrogen gas to the same temperature T1 (180° C.) as the precursor gas, the first nitrogen gas is mixed with the precursor gas to form a first mixed gas at a temperature T1, which is then fed into the first gas inlet 21 and then into the transition zone 20;

[0060] Step S3, cool the second nitrogen gas to a temperature lower than T2. ​​In this embodiment, T2 is 20°C. The method for obtaining T2 is as follows: a first cavity 41 is set inside the coating device 1, and the first cavity 41 is connected to an external refrigeration device through a pipeline. The external refrigeration device passes the first cooling water of 0°C into the first cavity 41, and controls the flow of the first cooling water so that the temperature of the first cooling water does not exceed T2 when it returns to the refrigeration device. That is, the first cooling water is heated by the coating chamber 3 and the substrate 10 and the temperature does not exceed 20°C. Then, it returns to the refrigeration device to be cooled to 0°C and recirculates into the first cavity 41; the first nitrogen pipe 4 is a series of pipes arranged on the first gas supply main 42. The branch pipe opening points toward the transition zone 20. The first gas supply main pipe 42 is immersed in the first cooling water within the first chamber 41. By increasing the travel of the first gas supply main pipe 42 within the first chamber 41, the first nitrogen gas is cooled to a temperature below 20°C before being delivered to the transition zone 20 via the first nitrogen pipe 4. It is mixed with the first mixed gas to form a second mixed gas, which is then introduced into the second gas inlet duct 22 by the first roller 5. In this embodiment, by controlling relevant parameters, including the second nitrogen gas being kept below 20°C, the temperature T4 of the second mixed gas in the transition zone 20 is kept below 570°C, with T4 (570°C) < T (620°C), thereby preventing the CVD reaction from being triggered.

[0061] In this embodiment, the extension line of the nozzle of the first nitrogen pipe 4 is closer to the circumferential surface of the upper end of the first roller 5, so that the ejected first nitrogen gas with a temperature below 20°C flushes and cools the circumferential surface of the first roller 5, thereby reducing the temperature of the circumferential surface of the first roller 5, thereby reducing the heat transfer from the first roller 5 to the opening of the first air inlet 21, helping to achieve the temperature T4 of the second mixed gas in the transition zone 20 below 570°C, thereby avoiding the occurrence of CVD reaction at the opening of the first air inlet 21, and effectively preventing the narrowing and blockage of the opening of the first air inlet 21 with a fixed width;

[0062] Step S4, cool the third nitrogen to a temperature lower than T3. In this embodiment, T3 is 50°C. The method for obtaining T3 is as follows: a second cavity 61 is set inside the coating device 1, and the second cavity 61 is connected to the external refrigeration device through a pipeline. The external refrigeration device passes the second cooling water at 20°C into the second cavity 61, and controls the flow of the second cooling water so that the temperature of the second cooling water does not exceed T3 when it returns to the refrigeration device. That is, the second cooling water is heated by the coating chamber 3 and the substrate 10 and the temperature rises by no more than 30°C, and then returns to the refrigeration device. The second nitrogen gas is cooled to 20°C and then recirculated into the second chamber 61. The second nitrogen pipe 6 is a branch pipe arranged on the second gas supply main pipe 62, with an opening pointing to the second gas inlet channel. The second gas supply main pipe 62 is immersed in the second cooling water in the second chamber 61. By increasing the stroke of the second gas supply main pipe 62 in the second chamber 61, the second nitrogen gas is cooled to a temperature below 50°C. It is then sent into the second gas inlet channel 22 through the second nitrogen pipe 6, mixed with the second mixed gas to form a third mixed gas, and then guided by the second roller 7 toward the substrate 10.

[0063] In this embodiment, the extension line of the nozzle of the second nitrogen pipe 6 is closer to the circumferential surface of the upper end of the second roller 7, so that the ejected second nitrogen gas with a temperature below 50°C flushes and cools the circumferential surface of the second roller 7, thereby reducing the temperature of the circumferential surface of the second roller 7, reducing the heat transfer from the second roller 7 to the first roller 5, and also contributing to reducing the heat transfer from the first roller 5 to the outlet of the first air inlet 21, that is, helping to achieve the temperature T4 of the second mixed gas in the transition zone 20 below 570°C. The relevant parameters also include T3. By controlling the relevant parameters including the second nitrogen gas below 20°C and the third nitrogen gas below 50°C, the temperature T4 of the second mixed gas in the transition zone 20 is lowered to below 570°C, thereby avoiding the occurrence of CVD reaction at the outlet of the first air inlet 21, and effectively preventing the narrowing and blockage of the first air inlet 21 with a fixed opening width.

[0064] Step S5: After the third mixed gas enters the coating chamber 3 from the second air inlet, it is heated to T5 by the substrate 10. In this embodiment, T5 is 630°C, T5>T, triggering the CVD reaction and depositing a thin film on the surface of the substrate 10. The reaction exhaust is discharged from the exhaust duct 12 of the coater 1.

[0065] At the same time, deposition may also occur on the surfaces of the first roller 5 and the second roller 7, especially on the surface of the second roller 7 close to the substrate 10 where there will be thicker deposits;

[0066] Since the first and second rollers are in a uniform rotation state, coupled with the synergistic effect of the second and third mixed gases, as well as the first and second nitrogen gases, the deposits are evenly distributed on the circumferential surfaces of the first and second rollers, that is, the deposits are evenly distributed on the surface of the second air inlet duct 22.

[0067] Step S6: When the thickness of the deposit 14 on the surface of the second roller 7 is first accumulated to the point where the distance C between the deposit surfaces on the line connecting the centers of the pair of second rollers 7 is less than the lower limit allowed by the coating process ( Figure 5 As shown), the second bearing 71 is slid outward in a direction parallel to the movement of the substrate 10, so that the distance between the sediment surfaces on the line connecting the centers of the pair of second rollers 7 is increased to D ( Figure 6 As shown), the initial width D of the air inlet required for the coating process is restored;

[0068] The coating production continues. When the thickness of the deposit 14 on the surface of the second roller 7 accumulates again to the point where the distance between the deposit surfaces on the line connecting the centers of the pair of second rollers 7 is less than the lower limit allowed by the coating process, the above operation is repeated.

[0069] Similarly, when the thickness of the deposit on the surface of the first roller 5 accumulates to the point where the distance between the deposit surfaces on the line connecting the centers of a pair of first rollers 5 is less than the lower limit allowed by the coating process, the same operation as above is performed;

[0070] The first bearing 51 and the second bearing 71 are rotatably connected to the side wall 31, and the first bearing 51 and the second bearing 71 are both slidably connected to the side wall 31 in a direction parallel to the moving direction of the substrate 10. The ends of one side of the first roller 5 and the second roller 7 are provided with sprockets connected to the synchronous belt, and the synchronous belt is connected to the driving mechanism. The above are all existing technologies and will not be repeated here.

[0071] 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 and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A CVD coating device, comprising a coating device (1) consisting of a coating chamber (3) and an exhaust duct (12), and a substrate (10) to be coated located directly below the coating device (1), characterized in that: The device further comprises a combined air inlet (2) disposed in the coating chamber (3) and used for delivering external nitrogen and precursor gas into the coating chamber (3); the combined air inlet (2) comprises a first air inlet (21) with a fixed air inlet width and a second air inlet (22) with an adjustable air inlet width, and both have the same initial width D; the first air inlet (21) and the second air inlet (22) are vertically connected to each other, and the second air inlet (22) is close to the substrate (10); The nitrogen gas is pre-divided into a first nitrogen gas, a second nitrogen gas and a third nitrogen gas, and respectively fed into the first air inlet (21), the transition zone (20) between the first air inlet (21) and the second air inlet (22), and the second air inlet (22), and the temperature of the gas in the transition zone (20) is lower than the lower limit temperature T for triggering the CVD reaction; and the deposits (14) of the CVD reaction are uniformly distributed on the surface of the second air inlet (22). When the deposits (14) accumulate to the point where the width of the second air inlet (22) is less than the lower limit allowed by the coating process, the width of the second air inlet (22) is adjusted until the initial width D is restored.

2. The CVD coating device according to claim 1, characterized in that: The first air inlet (21) is a slit opening downward; a pair of first nitrogen pipes (4) with nozzles facing each other are distributed on both sides of the transition zone (20); a pair of first rollers (5), a pair of second nitrogen pipes (6) with nozzles facing each other, and a pair of second rollers (7) are distributed on both sides of the second air inlet (22) from top to bottom; the initial distance between the circumferential surfaces on the line connecting the centers of the first rollers (5) and the second rollers (7) is an initial width D.

3. The CVD coating device according to claim 2, wherein: The two ends of the first roller (5) and the second roller (7) are rotatably connected to the side wall (31) of the coating chamber (3) through a first bearing (51) and a second bearing (71) respectively provided on the side wall (31), and the first bearing (51) and the second bearing (71) are both slidably connected to the side wall (31) in a direction parallel to the moving direction of the substrate (10).

4. The CVD coating device according to claim 3, characterized in that: The first roller (5) and the second roller (7) rotate at a uniform speed, and the direction of rotation is consistent with the direction of air flow in the second air inlet duct (22).

5. A CVD coating method, characterized in that: The method comprises the CVD coating apparatus according to claim 4; The method comprises the following steps: Step S1, pre-dividing the nitrogen into the first nitrogen, the second nitrogen and the third nitrogen according to the volume ratio of (1-5): (70-95): (5-25) under standard conditions; Step S2, heating the first nitrogen gas to the same temperature T1 as the precursor gas, mixing it with the precursor gas to form a first mixed gas with a temperature T1, and then sending it into the first gas inlet (21), and then into the transition zone (20); Step S3, after cooling the second nitrogen gas to a temperature lower than T2, the second nitrogen gas is fed into the transition zone (20) through the first nitrogen pipe (4), mixed with the first mixed gas to form a second mixed gas, and introduced into the second gas inlet (22) through the first roller (5); the temperature of the second mixed gas in the transition zone (20) is T4, and by controlling relevant parameters including the second nitrogen gas being lower than the temperature T2, the temperature T4 is lower than the lower limit temperature T for triggering the CVD reaction; Step S4, after cooling the third nitrogen gas to a temperature lower than T3, the third nitrogen gas is fed into the second gas inlet channel (22) through the second nitrogen pipe (6), mixed with the second mixed gas to form a third mixed gas, and guided to the direction of the substrate (10) through the second roller (7); by controlling relevant parameters including the second nitrogen gas being lower than the temperature T2 and the third nitrogen gas being lower than the temperature T3, the temperature T4 of the second mixed gas in the transition zone (20) is lower than the lower limit temperature T for triggering the CVD reaction; Step S5: After the third mixed gas enters the coating chamber (3) from the second air inlet (22), it is heated by the substrate (10) to a temperature T5, such that the temperature T5 is greater than or equal to the lower limit temperature T, triggering a CVD reaction to deposit a thin film on the surface of the substrate (10); at the same time, deposition may also occur on the surface of the first roller (5) or the second roller (7); Step S6: When the thickness of the deposit (14) on the surface of the first roller (5) or the second roller (7) accumulates to the point where the distance between the surfaces of the deposit (14) on the line connecting the centers of the two first rollers (5) or the second rollers (7) is less than the lower limit allowed by the coating process, the corresponding first bearing (51) or the second bearing (71) is slid outward in a direction parallel to the movement of the substrate (10) until the initial air inlet width D required for the coating process is restored.

6. A CVD coating method according to claim 5, characterized in that: A first cavity (41) is provided inside the coating device (1), and the first cavity (41) is connected to an external refrigeration device through a pipeline. The external refrigeration device passes first cooling water into the first cavity (41), controls the flow rate of the first cooling water, and ensures that the temperature of the first cooling water does not exceed T2 when it returns to the refrigeration device. The first cooling water then returns to the refrigeration device to be cooled and recirculates into the first cavity (41); The first air supply main pipe (42) is not immersed in the first cooling water in the first cavity (41). The first nitrogen pipe (4) is a branch pipe arranged on the first air supply main pipe (42) and openings pointing to the transition zone (20). By increasing the stroke of the first air supply main pipe (42) in the first cavity (41), the first nitrogen is cooled to a temperature lower than T2, and then sent into the transition zone (20) through the first nitrogen pipe (4), mixed with the first mixed gas to form the second mixed gas, and then introduced into the second air inlet duct (22) through the first roller (5).

7. A CVD film coating method according to claim 6, characterized in that: A second cavity (61) is provided inside the coating device (1), and the second cavity (61) is connected to an external refrigeration device through a pipeline. The external refrigeration device passes second cooling water into the second cavity (61), controls the flow rate of the second cooling water, and ensures that the temperature of the second cooling water does not exceed T3 when it returns to the refrigeration device. The second cooling water then returns to the refrigeration device to be cooled and recirculates into the second cavity (61); The second gas supply pipe (62) is not immersed in the second cooling water in the second cavity (61); the second nitrogen pipe (6) is a branch pipe arranged on the second gas supply pipe (62) and having an opening pointing to the second gas inlet channel (22); by increasing the stroke of the second gas supply pipe (62) in the second cavity (61), the second nitrogen is cooled to a temperature lower than T3, and then is sent into the second gas inlet channel (22) through the second nitrogen pipe (6), mixed with the second mixed gas to form the third mixed gas, and is guided to the direction of the substrate (10) through the second roller (7).

8. A CVD film coating method according to claim 7, characterized in that: The extension line of the nozzle of the first nitrogen pipe (4) is close to the circumferential surface corresponding to the upper end of the first roller (5); the extension line of the nozzle of the second nitrogen pipe (6) is close to the circumferential surface corresponding to the upper end of the second roller (7).

9. A CVD coating method according to any one of claims 5 to 8, characterized in that: The precursor gas contains tin, an element constituting a low-emissivity film.

10. Use of the CVD coating method according to claim 9 in online coating production of float glass.

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