CN111705304A - A kind of continuous uniform coating hot wire chemical vapor deposition equipment and method - Google Patents

Abstract

The invention belongs to the technical field of chemical vapor deposition, and relates to a hot wire chemical vapor deposition device and method. A continuous and uniform coating hot wire chemical vapor deposition equipment, comprising: a coating chamber, a sample feeding and heat preservation chamber, and a sample feeding device, the coating chamber and the sample feeding and heat preservation chamber are connected by a plug valve, and the coating film A hot wire heating system is arranged in the chamber; a water cooling system is arranged below the hot wire heating system; the sample feeding and heat preservation chambers are arranged on both sides of the coating chamber; the sample feeding device passes the sample feeding The sample is fed into the coating chamber from the holding chamber, and the two sides are alternately coated for continuous coating. The device and method of the present invention can precisely control the heating wire heating unit and the water cooling unit, and realize uniform temperature field, thereby realizing the uniformity of the prepared film, optimizing the current and water flow, and saving energy. Cooling, reducing film stress, improving product quality and service life.

Description

A kind of continuous uniform coating hot wire chemical vapor deposition equipment and method

technical field

The invention belongs to the technical field of chemical vapor deposition, and relates to a hot wire chemical vapor deposition device and method.

Background technique

At present, boron-doped diamond film sewage treatment electrodes and diamond-coated tools have become new products in the field of industrial applications. Diamond film sewage treatment electrodes can degrade industrial wastewater and refractory organic wastewater, and have great application prospects in the field of environmental protection. Diamond-coated tools are also widely used in aerospace material processing, microelectronic device processing, etc. The hot filament chemical vapor deposition method can prepare a large area of diamond thin film, but the hot filament needs to be replaced each time, the preparation efficiency is low, and the material cost and time cost are high; in addition, the uneven temperature field of the hot filament leads to poor uniformity of film quality; there is no corresponding The cooling process leads to excessively high stress and poor stability of the film, which seriously hinders its application. In order to improve the production efficiency of thin films and improve the quality of thin films, new vacuum equipment and processes need to be developed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the defects existing in the existing deposition equipment in terms of temperature control, and to provide a continuous and uniform coating hot wire chemical vapor deposition equipment and method. The uniformity of the wire temperature field improves the film quality.

The first technical solution adopted by the present invention to solve the technical problem is: a continuous and uniform coating hot wire chemical vapor deposition equipment, comprising: a coating chamber, a sample feeding and heat preservation chamber, and a sample feeding device, the coating chamber and the feeding The sample insulation chambers are connected by a plug-in valve, a hot wire heating system is arranged in the coating chamber; a water cooling system is arranged below the hot wire heating system; the sample feeding and insulation chambers are symmetrically arranged on the The two sides of the coating chamber; the sample feeding device feeds the sample to the coating chamber through the sample feeding and heat preservation chamber, and the two sides are alternately performed for continuous coating.

As a preferred mode of the present invention, the hot wire heating system is composed of a plurality of hot wire units, each hot wire unit includes a hot wire, and the hot wire is connected to an independent power supply.

Further preferably, the heating wire units are evenly arranged on the heating wire frame, and the heating wire frame is provided with a number of conductive rings, and each group of conductive rings is respectively connected to the positive and negative electrodes of an independent power supply; The ends bypass the conductive rings of the positive and negative poles, and are tensioned by a spring.

As a preferred mode of the present invention, the water cooling system includes a water cooling plate, and the water cooling plate is composed of several parallel water cooling units; the water flow direction of the water cooling units is perpendicular to the current direction of the heating wire.

Further preferably, the water-cooling unit is provided with a flow cut-off valve, and the water flow in the water-cooling unit is controlled by the flow cut-off valve.

Further preferably, a lifting mechanism is provided below the water cooling plate, and the lifting mechanism drives the water cooling plate to move up and down.

As a preferred mode of the present invention, the sample feeding device includes a sample tray, the sample tray is composed of a tray body and a resistance wire, and the resistance wire is circuitously arranged in the tray body; two parts of the resistance wire The ends are respectively connected to the positive and negative wires; the arrangement spacing of the resistance wires is gradually denser from the middle to the two sides.

Further preferably, the sample feeding device further comprises a sample feeding rod, and one end of the sample feeding rod is connected to the sample tray; the joint end of the sample feeding rod and the sample tray is provided with positive and negative connection electrodes. .

Further preferably, the sample feeding device further comprises a transfer rack arranged in the sample feeding holding chamber and the coating chamber, the transfer rack is provided with a sliding device, and the sample tray is in the sample feeding chamber. The push and pull of the rod enters and leaves the coating chamber by means of the sliding device.

The present invention further provides a continuous uniform coating hot wire chemical vapor deposition method, comprising:

(1) Close the flapper valves on both sides of the coating chamber, turn on the power, and wait for the carbonization of the hot wire;

(2) Adjust the current of each hot wire heating unit, so that the current increases uniformly from the middle unit to the two units;

(3) Open the plug valve on one side and place the sample to be coated on the sample tray;

(4) Use the sample delivery rod to push the sample tray to the middle of the water cooling tray, pull out the sample delivery rod, and close the plug valve;

(5) The water-cooling plate is raised to a distance of 10mm below the hot wire, and the shut-off valve of each water-cooling unit is adjusted so that the water flow rate in the middle of the water-cooling plate decreases to both sides, and the process parameters are adjusted to start depositing the coating;

(6) In the later stage of coating, the water-cooling plate is lowered, the side plate valve is opened, the sample feeding rod is connected to the sample feeding tray, and the sample tray is powered on for heating.

(7) Open the plug valve on the other side, send the sample to be coated into the coating chamber through the sample feeding and holding chamber on the other side, and repeat steps (4)-(6) to coat another sample;

(8) Take out the cooled coating sample, place a new sample to be coated, circulate in sequence, and alternate the sample feeding and holding chambers on both sides to continuously coat.

Compared with the prior art, the present invention has the following beneficial effects:

Achieve one-time drawing, multiple, large-area, continuous coating, reducing coating costs;

Precisely control the hot wire heating unit and water cooling unit to achieve uniform temperature field, so as to achieve uniformity of the prepared film, optimize current and water flow, and save energy;

Add a temperature-controlled sample tray to achieve automatic heat preservation and cooling, reduce film stress, and improve product quality and service life;

High automation control, one person can control multiple equipments and reduce labor costs.

Description of drawings

1 is a schematic diagram of the overall structure of a continuous uniform coating hot wire chemical vapor deposition equipment provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of an external chamber;

Figure 3 is a schematic diagram of the structure and spatial position relationship between the internal hot wire heating system and the water cooling system;

Figure 4 is a schematic diagram of the structure of the hot wire unit;

Figure 5 is a schematic diagram of a hot wire heating system composed of several hot wire units;

Fig. 6 is the structural representation of water cooling plate;

7 is a schematic diagram of the internal structure of the circulation chamber;

8 is a schematic diagram of a water-cooled plate lifting mechanism;

Figure 9 is a perspective view of the structure of the sample feeding tray;

Figure 10 is a schematic diagram of the internal resistance wire arrangement of the sample feeding tray;

Figure 11 is a schematic diagram of the connection between the sample feeding rod and the sample feeding tray;

FIG. 12 is a schematic flowchart of a chemical vapor deposition method for continuous uniform coating hot wire provided by an embodiment of the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure is provided.

One of the embodiments provided by the present invention is: a continuous uniform coating hot wire chemical vapor deposition equipment, the overall structure of the equipment is shown in Figures 1 and 2, and is composed of a double-layer water-cooled outer shell processed from 304 stainless steel The chambers of the entire equipment are respectively the left sample feeding and holding chamber 2, the middle coating chamber 4, and the right sample feeding and holding chamber 5. The left sample feeding and heat preservation chamber 2 and the right sample feeding and heat preservation chamber 5 are respectively separated from the middle coating chamber 4 by the plug-in valve 3 .

As shown in Figures 1 and 3, in the coating chamber 4, there is a hot wire heating system running front and rear and a water cooling system running left and right, wherein the water cooling system is placed below the hot wire heating system, and there is a space between the two. are separated by a distance and are in a vertical relationship.

As shown in FIGS. 3 and 4 , the hot wire heating system consists of several hot wire units 6 arranged in parallel on the hot wire rack 11 . The hot wire rack 11 is supported by four vertical copper rods 17, and a ceramic beam 14 is installed between the two copper rods. The copper rod 17 is a hollow rod body, and water flows through it, which cools the high temperature ceramic beam 14 during the coating process.

As shown in FIG. 4 , each heating wire unit includes a heating wire 8 and two high-temperature-resistant conductive molybdenum rings: a negative electrode molybdenum ring 12 and a positive electrode molybdenum ring 13 . A plurality of molybdenum rings are connected in series on the ceramic beam 14 with a certain distance between adjacent molybdenum rings. The heating wire 8 is a tantalum wire with a diameter of 0.5-0.8 mm. Both ends of the heating wire 8 bypass the positive molybdenum ring 13 and the negative molybdenum ring 12 respectively, and are tensioned by the high temperature resistant spring 16 fixed on the insulating ceramic 18 . The negative electrode molybdenum ring 12 and the positive electrode molybdenum ring 13 are respectively connected to the positive and negative electrodes of an independent power supply through high temperature resistant wires 15 .

As shown in Figures 4 and 5, different from the traditional heating wire that is powered by the same power supply in parallel, in the entire heating wire heating system of this embodiment, each heating wire unit is connected to an independent power supply, and the independent power supply is a single heating wire. The wire is powered separately to achieve precise control of the current of a single hot wire, and then to achieve precise temperature control.

When the traditional hot wire is energized, the current of each hot wire is the same, and the heat generation is the same, resulting in the phenomenon of high temperature in the middle and low temperature on both sides of the entire hot wire temperature field, resulting in uneven film growth thickness and quality. In this embodiment, the heating wire unit structure realizes the current control of a single heating wire, and the current from both sides to the middle heating wire is gradually decreased, so that the heat production of the heating wire on both sides is higher than that of the middle heating wire, and the horizontal direction of the heating wire is relieved. temperature field difference.

As shown in FIG. 6 , the water cooling system consists of a water cooling plate 9 , a circulation chamber 20 and a water inlet and outlet pipe 21 . Among them, the water cooling plate 9 is composed of several water cooling units 19 side by side, and the water cooling units 19 use non-standard pipe fittings processed by red copper. Both ends of the water cooling unit 19 are connected to both ends of the circulation chamber 20 , a flow cut-off valve 22 is installed at the inlet end of each water-cooled unit, and the water flow in each pipe can be controlled by the flow cut-off valve 22 .

The internal structure of the circulation chamber 20 is shown in FIG. 7 , a partition 23 is provided inside, and the partition divides the circulation chamber 20 into a left water inlet chamber and a right water outlet chamber, wherein the water inlet chamber and the water cooling unit The inlet end of 19 is connected, and the water outlet chamber is connected with the outlet end of the water cooling unit. The bottom of the circulation chamber 20 is connected to the water inlet and outlet pipes 21, the water inlet and outlet pipes 21 are casing structures, the inner pipe is a water outlet pipe, and the outer pipe is a water inlet pipe. The water inlet pipe is communicated with the water inlet chamber. The partition plate 23 is connected with the water outlet pipe, and the water outlet chamber is communicated with the water outlet pipe through the return hole 24 opened on the partition plate. The water inlet pipe outside the water inlet and outlet pipe 21 carries cold water, and the inner water outlet pipe carries hot water that returns. The lower end of the water inlet and outlet pipes 21 is provided with inlet and outlet ports.

As shown in FIG. 8 , a vacuum tray 25 is installed on the water inlet and outlet pipes 21 . The function of the vacuum plate 25 is to close the bottom of the coating chamber 4 during the coating process, so that the coating chamber forms a closed space.

A hydraulic ejector rod 26 is provided at the bottom of the water inlet and outlet pipes 21 , and under the action of the hydraulic ejector rod 26 , the entire water-cooling plate 9 can be moved up and down.

During the lifting and lowering process of the water-cooled plate 9, in order to maintain the sealing state between the vacuum plate 25 and the bottom of the coating chamber 4, the vacuum plate 25 and the bottom of the circulation chamber 20 are connected through the corrugated expansion tube 27, so that during the lifting and lowering of the water-cooled plate 9, the vacuum The position of the disk 25 remains unchanged, thereby sealing the bottom of the coating chamber 4 .

In this embodiment, the water cooling unit in the water cooling plate 9 and the heating wire unit 6 in the heating wire heating system are vertically placed in space, that is, the current direction in the heating wire unit is spatially perpendicular to the water flow direction of the water cooling unit. The non-uniformity of the heating wire temperature field is divided into two directions: the direction perpendicular to the heating wire and the direction parallel to the heating wire. The vertical direction of the heating wire can be controlled by adjusting the current difference of the heating wire unit, but the temperature difference in the parallel direction of the heating wire still exists, because the heat generated by each position of the same heating wire is basically the same, but due to the heat radiation received in the middle of the sample stage more than both ends. The water-cooling unit of the water-cooling plate can control the flow of water passing through each tube, so that the water flow of the two ends of the unit shows an increasing trend to the middle, then the heat taken by the middle water-cooling unit is higher than the two sides, and the temperature field difference in the parallel direction of the heating wire can be alleviated. .

In this embodiment, the independent control of the current of the hot wire unit and the independent control of the water flow of the water cooling unit, as well as the vertical layout of the two, play a decisive role in solving the technical problem of the uneven distribution of the hot wire temperature field.

The water cooling plate 9 in the coating chamber 4 realizes the lifting function under the action of the hydraulic ejector rod 26 . Generally, during coating, the distance between the hot wire and the sample tray is about 8mm~10mm, the temperature of the hot wire is 2400~2600℃, and the radiation temperature of the sample tray is as high as 800~1000℃. , so it is difficult to achieve. In addition, the hot wire at high temperature requires a very stable surrounding environment, and the disturbance caused by the transmission may cause the hot wire to break. Therefore, after the sample is coated, the hydraulic ejector rod 26 is slowly lowered to a reasonable position, so that the sample can be transferred at a suitable temperature without disturbing the hot wire.

As shown in Figures 1 and 2, in this embodiment, a sample tray 1 and a sample feeding rod 7 are respectively provided in the left sample feeding and holding chamber 2 and the right sample feeding and holding chamber 5, and in the sample feeding and holding chamber And a transfer rack 10 is arranged in the coating chamber, as shown in FIG. 3 . The conveying frame 10 is made of high temperature resistant ceramics, which will not deform under high temperature conditions. A pulley is mounted on the transfer frame 10 . The sample tray 1 is placed on the transfer rack 10, and under the push-pull action of the sample feeding rod 7, the sample is transferred in the coating chamber 4 and the sample feeding and holding chambers on both sides through the rolling of the pulley.

As shown in FIG. 9 , the sample feeding tray 1 is composed of a ceramic tray body 33 and a heating wire 28 inside. The heating wire 28 is a heatable resistance wire, which is arranged in a circuitous manner inside the ceramic disc body 33, and from the middle to the two sides, the spacing of the heating wires gradually becomes smaller, and the arrangement is gradually denser, as shown in FIG. 10 . The purpose of adopting this arrangement is to allow a large area of the sample to be cooled uniformly during the cooling process.

As shown in FIGS. 9 and 11 , both ends of the heating wire 28 are connected to the positive electrode lead 29 and the negative electrode lead 30 , respectively. The sample feeding rod 7 is connected to the sample feeding tray 1 by plugging, and a positive electrode 31 and a negative electrode 32 are provided at the joint of the sample feeding rod 7 . When the sample feeding rod 7 and the sample feeding tray 1 are plugged together, the positive electrode 31 and the negative electrode 32 are respectively connected to the negative electrode lead 30 and the positive electrode lead 29, and the positive electrode 31 and the negative electrode 32 are connected to the power supply, and the heating wire 28 can be energized and heated. The coating sample placed on the ceramic disc body 33 is heated and kept warm.

Based on the equipment provided in the above embodiment, the present invention also provides another embodiment: a continuous uniform coating hot wire chemical vapor deposition method, the process flow of the method is shown in Figure 12, and the specific steps are:

1. The coating chamber in the middle is separated from the sample feeding and insulation chambers on both sides by the flapper valve, and the power supply of the hot wire heating system is turned on, as shown in (1) in Figure 12;

2. After the carbonization of the hot wire is completed, adjust the current of each hot wire unit, increasing from the middle to both sides;

3. Open the right plug valve, place the sample to be coated on the sample tray, push the right sample tray to the middle of the water cooling tray with the sample feed rod, pull out the sample feed rod, and close the right plug valve;

4. Start the night pressing rod to raise the water cooling plate to a distance of 10mm from the hot wire, adjust the flow shut-off valve of each water cooling unit so that the flow rate of the middle water flow is greater than that of both sides, adjust the process parameters, and start to deposit the coating, as shown in Figure 12 ( 2) shown;

5. In the later stage of coating, start the pressure night ejector to lower the water cooling plate to a certain position, open the right plug valve, connect the sample feeding rod to the sample feeding tray, and turn on the power supply to heat the sample tray, that is, during the sample transfer process , the coated sample is heated and kept warm by the sample pan to keep it at a constant temperature or a stable state with little fluctuation, as shown in (3) in Figure 12;

6. Close the plug-in valve on the right, and gradually reduce the current of the sample plate. As the temperature of the sample plate gradually decreases, the sample cools down uniformly with a certain gradient to reduce the stress state of the film, as shown in (4) in Figure 12;

7. Push the sample from the left sample feeding holding chamber to the cooling tray, as shown in (5) in Figure 12. At the same time, take out the cooled sample from the right sample feeding holding chamber and place a new one without coating. sample;

8. Repeat steps 3-6 to complete the coating and uniform cooling of the sample in the left-hand sample feeding and holding chamber, as shown in (6) in Figure 12;

9. Re-open the right side flap valve, repeat steps 3-6, cycle in turn, and alternate left and right.

In the above method, the heating wire of the coating chamber is always in a heated state and is not open to the atmosphere. The left and right sample feeding and heat preservation chambers play the role of circulating sample feeding and heat preservation to realize continuous coating.

Combined with process experience, the present invention finds that in the later stage of film preparation, in addition to slow cooling, a lower constant temperature stage is also required to release stress. Therefore, the device and method of the present invention are proposed, which can realize automatic thermal insulation and thermal stability of samples after coating. Gentle and uniform cooling reduces film stress and improves product quality and service life.

Claims (10)

1. A continuous uniform coating film hot wire chemical vapor deposition device comprises: the sample feeding device comprises a coating chamber, a sample feeding heat-insulation chamber and a sample feeding device, wherein the coating chamber is connected with the sample feeding heat-insulation chamber through a gate valve, and a hot wire heating system is arranged in the coating chamber; a water cooling system is arranged below the hot wire heating system; the method is characterized in that: the sample feeding heat-preservation chamber is arranged on two sides of the coating chamber; and the sample feeding device feeds a sample into the coating chamber through the sample feeding heat-insulating chamber, and the two sides of the sample feeding device are alternately coated with the film continuously.

2. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 1, wherein: the hot wire heating system is composed of a plurality of hot wire units, each hot wire unit comprises a hot wire, and the hot wires are connected with an independent power supply.

3. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 2, wherein: the hot wire units are uniformly distributed on the hot wire frame, a plurality of conducting rings are arranged on the hot wire frame, and each group of conducting rings is respectively connected with the positive electrode and the negative electrode of the independent power supply; two ends of the hot wire bypass the conducting rings of the positive electrode and the negative electrode and are tensioned through the spring.

4. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 2, wherein: the water cooling system comprises a water cooling disc, and the water cooling disc consists of a plurality of water cooling units which are arranged in parallel; and the water flow direction of the water cooling unit is vertical to the current direction of the hot wire.

5. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 4, wherein: and a flow stop valve is arranged on the water cooling unit, and the flow of water in the water cooling unit is controlled by the flow stop valve.

6. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 4, wherein: and a lifting mechanism is arranged below the water-cooling disc and drives the water-cooling disc to move up and down.

7. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 1, wherein: the sample feeding device comprises a sample disc, the sample disc consists of a disc body and heating wires, the heating wires are arranged in the disc body in a winding way, and two ends of the heating wires are respectively connected with a positive wire and a negative wire; the arrangement intervals of the heating wires are gradually dense from the middle to the two sides.

8. The continuous and uniform coating hot-wire chemical vapor deposition apparatus according to claim 7, wherein: the sample feeding device also comprises a sample feeding rod, and one end of the sample feeding rod is connected with the sample disc in an inserting manner; and the joint ends of the sample feeding rod and the sample disc are provided with positive and negative connecting electrodes.

9. The continuous and uniform coating hot-wire chemical vapor deposition device according to claim 8, wherein: the sample feeding device further comprises a conveying frame arranged in the sample feeding heat-insulation chamber and the coating chamber, a sliding device is arranged on the conveying frame, and the sample plate can enter and exit the coating chamber by virtue of the sliding device under the push-and-pull of the sample feeding rod.

10. A continuous and uniform coating hot wire chemical vapor deposition method is characterized by comprising the following steps:

(1) closing gate valves at two sides of the coating cavity, switching on a power supply, and waiting for carbonization of the hot wire;

(2) adjusting the current of each hot wire heating unit to enable the current to be uniformly increased from the middle unit to the two side units;

(3) opening a gate valve on one side, and placing a sample to be coated on a sample disc;

(4) pushing the sample disc to the middle position of the water cooling disc by using the sample feeding rod, drawing out the sample feeding rod, and closing the gate valve;

(5) the water cooling disc is lifted to a position 10mm below the hot wire, the stop valve of each water cooling unit is adjusted to enable the flow velocity of cold water in the middle of the water cooling disc to be gradually reduced towards two sides, technological parameters are adjusted, and deposition coating is started;

(6) in the later stage of film coating, the water-cooling disc descends, the gate valve is opened, the sample feeding rod is connected with the sample feeding disc, the sample feeding disc is powered on to be heated, and the sample disc is pulled out to the sample feeding heat preservation chamber to be kept stand and cooled;

(7) opening a gate valve on the other side, conveying the sample to be coated into the coating chamber through the sample conveying heat-preserving chamber on the other side, and repeating the steps (4) to (6) to coat the other sample;

(8) and taking out the cooled film coating sample, placing a new sample to be coated, circulating in sequence, alternately carrying out sample feeding and heat preservation chambers on two sides, and continuously coating.

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