CN120945327B - PVD equipment capable of realizing Cu in-situ reflow and redeposition and control method thereof - Google Patents

Abstract

The invention discloses PVD equipment capable of realizing Cu in-situ reflow and redeposition and a control method thereof, wherein the PVD equipment comprises a first transfer cavity and a second transfer cavity, two sides of the first transfer cavity are respectively provided with an integrated cavity, a pre-cleaning cavity, a reprocessing process cavity and an in-situ reflow compound processing cavity in sequence, the periphery of the second transfer cavity is provided with a plurality of process cavities, a first heating module, a cavity water cooling channel, a wafer support frame and a lifting rotating mechanism are arranged in the integrated cavity, three wafer placing positions are arranged in the integrated cavity, the lifting rotating mechanism can move between the three wafer placing positions along with the wafer support frame, the in-situ reflow compound processing cavity comprises a cooling chassis, a supporting mechanism and a second heating module, the supporting mechanism is used for supporting a wafer and has the functions of rotating and moving up and down, and the three wafer placing positions are arranged in the up-down moving direction. The invention can solve the problems of micro holes, seam defects, uneven side wall coverage and the like in the copper interconnection film deposition high aspect ratio structure.

Description

PVD equipment capable of realizing Cu in-situ reflow and redeposition and control method thereof

Technical Field

The invention relates to PVD (physical vapor deposition) equipment and a preparation method thereof, in particular to PVD equipment capable of realizing Cu in-situ reflow and redeposition and a control method thereof.

Background

The traditional PVD equipment adopts an independent functional chamber design, and comprises a loading chamber, a heating degassing chamber, a pre-cleaning chamber, a process chamber, a cooling chamber and the like, wherein the wafer transmission path in the standard process flow comprises the steps of carrying in, loading in, heating the degassing chamber, pre-cleaning the chamber, the process chamber, the cooling chamber, loading in, carrying out, and the standard process flow comprises the steps of loading the wafer, heating and degassing, pre-cleaning the plasma, depositing the film, cooling and carrying out the wafer.

In semiconductor fabrication, a conventional PVD copper seed layer deposition process is shown in fig. 1. A SiO ₂ layer was deposited on a silicon wafer (①SiO₂ layer growth), then a deposition channel of copper film was etched (② Cu channel etch), and a thin Ta/TaN barrier layer was grown on the channel surface to prevent copper diffusion (③ Ta/TaN layer). When a copper film is deposited using conventional PVD equipment, sidewall coverage non-uniformity problems are prone to occur in high aspect ratio deposition channels and result in hole or seam defects (④ copper deposition). In the prior art, most of the solutions do not perform in-situ treatment on the defect problem generated after the copper film is deposited, but directly transfer the defect problem into a subsequent process after cooling, so that the effect of the subsequent process (such as electroplating) is affected, and the quality and yield of the wafer film are reduced. Some schemes can carry out batch annealing treatment on wafers after PVD, but annealing and deposition are separated, so that vacuum breaking problem can be caused, and local defects cannot be repaired pertinently.

Disclosure of Invention

The invention aims to solve the technical problem of providing PVD equipment capable of realizing Cu in-situ reflow and redeposition and a control method thereof, and can solve the problems of micro holes, seam defects, uneven side wall coverage and the like in a high aspect ratio structure.

The technical scheme adopted by the invention for solving the technical problems is that PVD equipment capable of realizing Cu in-situ reflow and redeposition comprises a first transfer cavity and a second transfer cavity, wherein an integrated cavity, a pre-cleaning cavity, a reprocessing process cavity and an in-situ reflow compound processing cavity are sequentially arranged on two sides of the first transfer cavity, a plurality of process cavities are arranged around the second transfer cavity, the in-situ reflow compound processing cavity is located between the first transfer cavity and the second transfer cavity, a first heating module, a cavity water cooling channel, a wafer support frame and a lifting rotating mechanism are arranged in the integrated cavity, three wafer placing positions which are respectively a first heating position, a first wafer transferring position and a first cooling position are arranged in the integrated cavity, the lifting rotating mechanism can move between the three wafer placing positions along with the wafer support frame, the in-situ reflow compound processing cavity comprises a cooling chassis, a supporting mechanism and a second heating module, the supporting mechanism is used for supporting a wafer and has a rotating and up-down moving function, and the in-down moving direction is provided with three wafer placing positions which are respectively a second wafer placing position and a second wafer placing position.

The integrated cavity is formed by integrally designing a loading cavity, a heating degassing cavity and a cooling cavity, the integrated cavity comprises a first cavity, a cavity upper cover is arranged above the first cavity, the first heating module is fixedly arranged on the cavity upper cover, quartz plates are fixed in the first heating module and the first cavity, the quartz plates, a quartz mounting seat and the first cavity enclose a first-layer vacuum environment in the cavity, and the quartz plates, the cavity upper cover and the quartz cover enclose a second-layer vacuum environment in the cavity.

Further, the first sheet conveying position is determined according to the telescopic position of the manipulator at the transfer cavity, the first heating position is located between the first heating module and the first sheet conveying position, the first cooling position is close to the position of the cavity water cooling channel below the cavity, the second sheet conveying position is determined according to the telescopic position of the manipulator at the transfer cavity, the second heating position is located between the second heating module and the second sheet conveying position, and the second cooling position is located on the upper surface of the cooling chassis.

Further, the upper end of the supporting mechanism is a circular ring and is provided with supporting points uniformly distributed in the circumferential direction for supporting the wafer, and the inner diameter of the circular ring is larger than the outer diameter of the cooling chassis.

Further, the second heating module is an infrared heating module, an RF induction heating module, a resistance wire heating module or a high-temperature gas heating module, and for the RF induction heating or resistance wire heating mode, the second heating position is located on the surface of the RF induction heating plate or the resistance wire heating plate.

S1, heating and degassing a wafer, namely, transferring the wafer into a first wafer transferring position of an integrated cavity, moving the wafer to a first heating position through a lifting rotating mechanism, vacuumizing a cavity and starting a first heating module to heat and degas in the moving process; after the heating and degassing are finished, the first heating module is closed, and the wafer is moved back to the first wafer conveying position through the lifting rotating mechanism; the method comprises the steps of opening channels of an integrated cavity and a first transfer cavity, transferring a wafer into the first transfer cavity, S2, pre-cleaning the wafer, namely transferring the wafer from the first transfer cavity into the pre-cleaning cavity, pre-cleaning plasma, cleaning the surface of the wafer for 12-16S, and then transferring the wafer into the first transfer cavity, S3, transferring the wafer, namely, transferring the wafer from the first transfer cavity into an in-situ reflow composite processing cavity, transferring the wafer into a second transfer cavity through a second transfer cavity, and then entering the process cavity, S4, depositing a wafer Cu film, namely, performing Cu film deposition on the wafer in the process cavity, transferring the wafer after film deposition into the second transfer cavity, S5, performing Cu film reflow, namely, transferring the wafer from the second transfer cavity into the in-situ reflow composite processing cavity, opening a second heating module, vacuumizing the cavity, enabling the wafer to be quickly heated to a reflow temperature, S6, cooling the wafer, controlling a supporting mechanism in the in-situ reflow composite processing cavity to move downwards, transferring the wafer to the lower part of a cooling chassis, placing the wafer on the cooling chassis, transferring the wafer to the second transfer the wafer to the cooling chassis to the inside the cooling chassis, transferring the wafer to the cooling chassis, and transferring the wafer to the cooling chassis to the in-situ, and transferring the wafer to the cooling chassis to the in-situ and then performing the cooling chassis, and transferring the wafer to the cooling chassis to 100 ℃, the method comprises the steps of reaching a first transfer cavity, S7, carrying out secondary deposition on a wafer, namely, carrying out secondary deposition on a copper film by transferring the wafer from the first transfer cavity to a reprocessing process cavity, S8, carrying out secondary cooling on the wafer, namely, transferring the wafer subjected to secondary deposition into an integrated cavity through the first transfer cavity to cool the wafer to below 100 ℃, S9, carrying out secondary deposition on the wafer, namely, after carrying out secondary cooling on the wafer, moving the wafer to a first wafer transferring position from a first cooling position, and carrying out the wafer out the whole PVD equipment.

Further, in the step S1, the chamber is vacuumized to 5-7 torr in the moving process, the first heating module adopts an infrared radiation lamp array capable of rapidly increasing and decreasing the temperature, so that the wafer is heated to 300 ℃ within 10 seconds, the temperature of 300 ℃ is maintained for heating and degassing, the first heating module is closed after the heating and degassing is finished, and meanwhile, the vacuum is continuously pumped until the vacuum degree of the chamber is less than or equal to 1 multiplied by 10 < -6 > torr.

Further, the step S5 comprises the steps of firstly transferring the wafer from the second transfer cavity to a second wafer transferring position of the in-situ reflow composite processing cavity, then moving the supporting mechanism upwards, enabling the wafer to enter the second heating position, vacuumizing the cavity to 5-7 torr and starting the second heating module, monitoring the temperature of the surface of the wafer in real time through the temperature monitoring system in the reflow process, controlling the power of the heating module in real time through the PLC, and adjusting the surface temperature of the wafer.

Further, in the step S5, for the film with the temperature of less than 30nm, the reflux temperature is 200-300 ℃, the heating time is 20-40S, and for the film with the temperature of more than or equal to 30nm, the reflux temperature is 300-400 ℃, and the heating time is 50-70S.

Further, the step S8 comprises the step of transferring the wafer after the secondary deposition from the first wafer transferring position to the first cooling position in the integrated cavity through the lifting rotating mechanism, inflating the integrated cavity to the atmospheric pressure, simultaneously opening the gas flow channel and the lower water cooling channel, wherein the gas flow speed is 150-200 SLM, the water cooling flow is 5-10L/min, and the time for cooling the wafer to below 100 ℃ is within 30S.

Compared with the prior art, the PVD equipment and the control method thereof have the advantages that the PVD equipment capable of realizing Cu in-situ reflow and redeposition has Cu in-situ reflow function, and realizes full vacuum consecutive treatment of deposition, reflow and secondary deposition, so that the film quality is improved under the condition of no vacuum breaking, the wafer yield is improved, and the service life of devices is prolonged.

Drawings

FIG. 1 is a flow chart of a conventional Cu thin film deposition process;

FIG. 2 is a schematic diagram of a PVD apparatus capable of performing Cu in-situ reflow and redeposition in accordance with the present invention;

FIG. 3 is a schematic view of the basic structure of the integrated cavity of the present invention;

FIG. 4 is a schematic view of the basic structure of an in-situ reflow composite processing chamber of the present invention;

FIG. 5 is a schematic view showing the reflow and deposition effects of the Cu thin film of the present invention.

The device is characterized by comprising 1/1', an integrated cavity, 2/2', a pre-cleaning cavity, 3/3', a reprocessing process cavity, 4/4', a process cavity, 5, a first transfer cavity, 5', a second transfer cavity, 6/6', an in-situ reflow compound processing cavity, 7, a first cavity, 8, a wafer support frame, 9, a wafer, 10, a quartz plate, 11, a quartz mounting seat, 12, a quartz cover plate, 13, a cavity upper cover, 14, a first heating module, 15, a cavity water cooling channel, 16, a lifting rotating mechanism, 17, a sliding block, 18, a motor, 19, a first heating position, 20, a first sheet conveying position, 21, a first cooling position, 22, a cooling chassis, 23, a second cavity, 24, a supporting mechanism, 25, a second heating module, 26, a temperature monitoring system, 27, a second heating position, 28, a second sheet conveying position, 29 and a second cooling position.

Detailed Description

The invention is further described below with reference to the drawings and examples.

FIG. 2 is a schematic diagram of a PVD apparatus capable of performing Cu in-situ reflow and redeposition in accordance with the present invention.

Referring to fig. 2, the PVD apparatus capable of implementing Cu in-situ reflow and redeposition provided by the present invention includes an integrated chamber 1/1', a pre-cleaning chamber 2/2', a reprocessing process chamber 3/3', a process chamber 4/4', a transfer chamber 5/5', and an in-situ reflow composite process chamber 6/6'.

In the invention, the integrated cavity 1/1' has the functions of load loading, heating and degassing and cavity cooling through the integrated design of the loading cavity, the heating and degassing cavity and the cooling cavity, and the basic structure is shown in figure 3, and the integrated cavity comprises a first cavity 7, a wafer support frame 8, a wafer 9, a quartz plate 10, a quartz mounting seat 11, a quartz cover plate 12, a cavity upper cover 13, a first heating module 14, a cavity water cooling channel 15, a lifting and rotating mechanism 16, a sliding block 17 and a motor 18, and is provided with three wafer placing positions with the integrated functions, wherein the three wafer placing positions comprise a first heating position 19, a first wafer conveying position 20 and a first cooling position 21. The first slice transferring position 20 is determined according to the telescopic position of the manipulator at the transfer cavity, and is preferably the middle position of the first cavity 7, the first heating position 19 is positioned between the first heating module 14 and the first slice transferring position 20, and is preferably the middle position of the first heating module 14 and the first slice transferring position 20, the first cooling position 21 is selected to be closest to the cavity water cooling channel 15 below the cavity, and in the wafer cooling process, the air cooling and the cavity water cooling are simultaneously conducted in the first cavity 7. The wafer 9 and the wafer support 8 are moved and changed by the lifting and rotating mechanism 16 at three positions. The upper part of the first cavity 7 is provided with a cavity upper cover 13 for installing and fixing a first heating module 14 (such as an infrared lamp array), a quartz plate 10 is fixed between the first heating module 14 and the inside of the first cavity 7, transparent quartz with transmittance more than or equal to 93% is preferred, the quartz plate 10, a quartz mounting seat 11 and the first cavity 7 enclose a first layer of vacuum environment in the cavity, the space size of the vacuum environment where the wafer 9 is positioned is reduced, the internal air charging and exhausting time is reduced, and the efficiency is improved.

In the invention, the 3/3' of the retreatment process chamber is a process chamber for Cu secondary deposition after in-situ reflow, and is used for continuously growing a layer of simple film after in-situ reflow, so that the film quality is further improved, and the basic structure of the retreatment process chamber is consistent with that of the process chamber in the traditional PVD equipment.

In the invention, the in-situ reflow composite processing cavity 6/6' is used for modifying a cooling cavity in the traditional PVD equipment, so that the cooling cavity has in-situ reflow and cooling functions. The improvement mode is that a heating module is added on the basis of a cooling chassis in the traditional cooling cavity, and the heating module comprises, but is not limited to, infrared heating, RF induction heating, resistance wire heating, high-temperature gas heating and the like, and is provided with a corresponding temperature monitoring system. The basic structure of the in-situ reflow composite processing chamber is schematically shown in fig. 4, and includes a cooling chassis 22, a second chamber 23, a support mechanism 24, a wafer 9, a second heating module 25, and a temperature monitoring system 26. The supporting mechanism 24 has a function of rotating or moving up and down, the upper end of the supporting mechanism 24 is a circular ring, and is provided with circumferentially uniformly distributed supporting points for supporting the wafer, and the inner diameter of the circular ring is larger than the outer diameter of the cooling chassis 22. The displacement position of the support means 24 is equipped with a respective second heating station 27, second sheet transfer station 28, second cooling station 29. The second slice transferring position 28 is determined according to the telescopic position of the manipulator at the transfer cavity, and is preferably a cavity middle position, the second heating position 27 is located between the second heating module 25 and the second slice transferring position 28, and is preferably a middle position of the second heating module 25 and the second slice transferring position 28, for RF induction heating or resistance wire heating, the second heating position 27 is located on the surface of the heating plate, and the second cooling position 29 is located on the upper surface of the cooling chassis 22.

The invention further provides a process flow of the improved PVD equipment platform:

The method comprises the steps of entering an integrated cavity 1/1' (a first transfer position 20, a first heating position 19, a first transfer position 20), a first transfer cavity 5, a pre-cleaning cavity 2/2', a first transfer cavity 5, an in-situ reflow compound processing cavity 6/6' (a second transfer position 28), a second transfer cavity 5', a process cavity 4/4', a second transfer cavity 5', an in-situ reflow compound processing cavity 6/6' (a second transfer position 28, a second heating position 27, a second cooling position 29, a second transfer position 28), a first transfer cavity 5, a retreating process cavity 3/3', a first transfer cavity 5, an integrated cavity 1/1' (a first transfer position 20, a first cooling position 21, a first transfer position 20) and an outgoing.

(1) The wafer heating and degassing, namely, the wafer 9 is transferred into a first wafer transferring position 20 of an integrated cavity, the wafer is moved to a first heating position 19 through a lifting rotating mechanism 16, the cavity is vacuumized to 5-7 torr in the moving process, a first heating module 14 is started, an infrared radiation lamp array capable of rapidly lifting and lowering the temperature is adopted, the temperature of the wafer 10s is raised to 300 ℃ and maintained at 300 ℃ for about 30s (heating and degassing), the first heating module 14 is closed, meanwhile, the vacuum is continuously pumped until the cavity vacuum degree is less than or equal to 1 multiplied by 10 < -6torr, and the wafer 9 is moved back to the first wafer transferring position 20 through the lifting rotating mechanism 16. And opening the channels of the integrated cavity and the first transfer cavity 5, and transferring the wafer 9 into the first transfer cavity 5.

(2) And (3) wafer pre-cleaning, namely, transferring the wafer 9 into a pre-cleaning cavity 2/2' from the first transfer cavity 5, performing plasma pre-cleaning, cleaning the surface of the wafer 9 for about 12-16 s, and then transferring the wafer into the first transfer cavity 5.

(3) The wafer is transferred, namely the wafer 9 enters the in-situ reflow compound processing cavity 6/6' from the first transfer cavity 5, is transferred to the second transfer cavity 5' through the second transfer position 28, and then enters the process cavity 4/4'.

(4) Wafer Cu film deposition, namely, performing Cu film deposition on a wafer 9 in a process cavity 4/4', wherein the surface effect of the wafer after deposition is shown as a in fig. 5, the outer side of a channel of a wafer deposition groove is provided with sharper protrusions, the whole side wall inside the groove is covered unevenly, the hole and joint defect problem exists inside the groove, and the wafer 9 after film deposition is transferred into a second transfer cavity 5' from the process cavity.

(5) Wafer Cu film reflow, namely, the wafer 9 is transferred into an in-situ reflow composite processing cavity 6/6 'from a second transfer cavity 5', firstly, at a second transfer position 28, then a supporting mechanism 24 moves upwards, the wafer 9 enters a second heating position 27, and meanwhile, the cavity is vacuumized to 5-7 torr and a second heating module 25 is started, so that the wafer 9 is quickly heated to a reflow temperature. The temperature of the surface of the wafer 9 can be monitored in real time through the temperature monitoring system 26 in the reflow process, and the power of the heating module is controlled in real time through the PLC to adjust the temperature of the surface of the wafer. In the reflow process, the upper computer, the PLC and the temperature monitoring system 26 are used for selecting reflow parameters according to requirements to automatically match and set, for example, for a film with the temperature of <30nm, the reflow temperature is 200-300 ℃, the heating time is about 20-40s, preferably 30s, for a film with the temperature of more than or equal to 30nm, the reflow temperature is 300-400 ℃, and the heating time is about 50-70s, preferably 60s. The surface state of the wafer 9 after in-situ reflow is shown as b in fig. 5, cu outside the deposited trench channel flows into the trench, the Cu thin film outside the channel is empty, but the sidewall inside the trench is uniformly covered, and the hole and joint defects are substantially eliminated.

(6) And (3) cooling the wafer, namely moving down the supporting mechanism 24 in the in-situ reflow compound processing cavity 6/6', moving the wafer 9 from the second heating position 27 to the second cooling position 29, continuing to move down the supporting mechanism 24 to the lower part of the cooling chassis 22, placing the wafer 9 on the cooling chassis 22, cooling the wafer 9 by water in the cooling chassis 22, moving up the supporting mechanism 24 to move the wafer 9 to the second wafer transfer position 28 after cooling to the temperature of <100 ℃, and then conveying the wafer 9 out of the in-situ reflow compound processing cavity 6/6' to the first transfer cavity 5.

(7) Wafer secondary deposition-the wafer 9 is transferred from the first transfer chamber 5 to the reprocessing chamber 3/3' for secondary deposition of copper films. For copper deposition processes requiring a total thickness of α nm, the thickness of the trench channel outside is typically about (α -10) nm after the primary deposition and reduced to (α -30 to α -20) nm after reflow, so the relative secondary deposition thickness is typically set to (α -20 to α -10) nm. For example, for a copper deposition process requiring a total thickness of 40nm, the thickness of the trench outside the first deposition is generally about 30nm, and is reduced to 10-20 nm after reflow, so that the relative second deposition thickness is generally set at 20-30 nm. The effect of the film on the surface of the wafer after the secondary deposition is shown as c in fig. 5, the Cu film vacancies outside the channel of the groove are supplemented, and the Cu film on the whole surface is uniformly covered without obvious defects.

(8) And (3) carrying out secondary cooling on the wafer, namely conveying the wafer 9 subjected to secondary deposition into an integrated cavity 1/1' through a first transfer cavity 5, transferring the wafer 9 from a first wafer conveying position 20 to a first cooling position 21 through a lifting rotating mechanism 16, inflating the first cavity 7 to the atmospheric pressure, simultaneously opening a gas flow channel and a lower water cooling channel, wherein the gas flow speed is 150-200 SLM, the water cooling flow is 5-10L/min, and the time for cooling the wafer 9 to below 100 ℃ is 30 s.

(9) The wafer is transferred out, after the wafer 9 is cooled again, from the first cooling station 21 to the first transfer station 20 and out of the whole PVD system.

After the deposition-reflow-redeposition process, the depth-width ratio range with excellent copper deposition effect can be increased from 4:1 to 8:1 and above.

Further, the above-mentioned process parameters and process flows of the present invention can be modified appropriately according to the actual requirements to adapt to the best PVD process effect. For example, for trench aspect ratios >8:1, multi-stage reflow and secondary deposition cycles may be employed to enhance the reflow and deposition effects. For example, a dedicated reflow profile is customized for different film materials or different process requirements, and the reflow process is controlled by a closed loop temperature control system, including but not limited to staged reflow, etc.

Further, the temperature measuring mode of the temperature monitoring system is not limited to any temperature measuring instrument, including but not limited to an infrared temperature measuring instrument, a thermocouple, an optical pyrometer, a thermal imager and the like. The temperature monitoring mode of the invention is that the temperature measuring equipment monitors the surface temperature of the wafer in real time and feeds back the surface temperature to the PLC, and the input power of the heating module is regulated in real time through PID calculation so as to approach and reach the required target temperature and maintain certain heat preservation time.

Further, the location of the heating module of the present invention is not limited to the top of the chamber, but may be replaced with any other reasonable heating location, including but not limited to the side wall of the chamber, the bottom of the chamber, etc. The heating mode of the invention is not limited to infrared heating, but also comprises but is not limited to resistance wire heating, electromagnetic induction heating and the like.

Further, the rotation or up-and-down movement functions of the lifting and rotating mechanism 16 and the supporting mechanism 24 are realized by a precise mechanical transmission system, for example, a servo motor is adopted to drive a screw nut mechanism or a gear rack mechanism, so that the movement precision and stability of the supporting mechanism are ensured. The position precision of the heating position, the sheet conveying position and the cooling position is critical to the stability and the repeatability of the process, and in the process of equipment installation and debugging, high-precision measuring instruments (such as a laser range finder, a three-coordinate measuring instrument and the like) are required to be used for precise calibration, so that the error of each position is ensured to be within a specified range (+ -0.1 mm).

Further, the PVD equipment integrating the in-situ reflow function can be used for in-situ reflow of metal films (such as Cu and the like), and further comprises, but is not limited to, the processing requirements of in-situ annealing of metal films (such as Al, cu and the like).

While the invention has been described with reference to the preferred embodiments, it is not intended to limit the invention thereto, and it is to be understood that other modifications and improvements may be made by those skilled in the art without departing from the spirit and scope of the invention, which is therefore defined by the appended claims.

Claims (10)

1. A PVD device capable of in-situ Cu reflow and redeposition, characterized in that it includes a first transfer chamber (5) and a second transfer chamber (5'), wherein an integrated chamber (1/1'), a pre-cleaning chamber (2/2'), a reprocessing chamber (3/3'), and an in-situ reflow composite processing chamber (6/6') are arranged sequentially on both sides of the first transfer chamber (5), and a plurality of process chambers (4/4') are arranged around the second transfer chamber (5'), and the in-situ reflow composite processing chamber (6/6') is located between the first transfer chamber (5) and the second transfer chamber (5'); the integrated chamber is provided with a first heating module (14), a chamber water cooling channel (15), a wafer support frame (8), and a lifting and rotating mechanism (16), and the integrated chamber is provided with three wafer placement positions, namely a first heating position (19), a first wafer transfer position (20), and a first cooling position (21); the lifting and rotating mechanism (16) can move the wafer support frame (8) between the three wafer placement positions; The in-situ reflow composite processing cavity (6/6’) includes a cooling chassis (22), a support mechanism (24) and a second heating module (25). The support mechanism (24) is used to support the wafer (9) and has rotation and up-down movement functions. It is equipped with three wafer placement positions in the up-down movement direction, namely the second heating position (27), the second wafer transfer position (28) and the second cooling position (29). 2. The PVD equipment for in-situ Cu reflux and redeposition as described in claim 1, characterized in that the integrated cavity (1/1’) is designed as an integrated loading cavity, heating and degassing cavity and cooling cavity, the integrated cavity includes a first cavity (7); a cavity cover (13) is provided above the first cavity (7), and the first heating module (14) is installed and fixed on the cavity cover (13); a quartz plate (10) is fixed inside the first heating module (14) and the first cavity (7), the quartz plate (10), the quartz mounting base (11) and the first cavity (7) form a first vacuum environment inside the cavity, and the quartz plate (10), the cavity cover (13) and the quartz cover plate (12) form a second vacuum environment inside the cavity. 3. The PVD equipment for in-situ Cu reflux and redeposition as described in claim 1, characterized in that the first transfer position (20) is determined according to the extendable position of the robot arm at the transfer chamber, the first heating position (19) is located between the first heating module (14) and the first transfer position (20), and the first cooling position (21) is located near the water cooling channel (15) of the chamber below the chamber; the second transfer position (28) is determined according to the extendable position of the robot arm at the transfer chamber, the second heating position (27) is located between the second heating module (25) and the second transfer position (28), and the second cooling position (29) is located on the upper surface of the cooling chassis (22). 4. The PVD equipment for in-situ Cu reflow and redeposition as described in claim 1, characterized in that the upper end of the support mechanism (24) is a ring and equipped with circumferentially distributed support points for supporting the wafer, and the inner diameter of the ring is larger than the outer diameter of the cooling base (22). 5. The PVD equipment that enables Cu in-situ reflux and redeposition as described in claim 1, characterized in that the second heating module (25) is an infrared heating module, an RF induction heating module, a resistance wire heating module or a high-temperature gas heating module, and for RF induction heating or resistance wire heating, the second heating position (27) is located on the surface of the RF induction heating plate or the resistance wire heating plate. 6. A control method for a PVD apparatus capable of in-situ Cu reflux and redeposition as described in any one of claims 1-5, characterized in that it comprises the following steps: S1. Wafer heating and degassing: The wafer (9) is transferred to the first transfer position (20) of the integrated cavity (1/1’), and moved to the first heating position (19) by the lifting and rotating mechanism (16). During the movement, the cavity is evacuated and the first heating module (14) is turned on for heating and degassing. After the heating and degassing is completed, the first heating module (14) is turned off, and the wafer (9) is moved back to the first transfer position (20) by the lifting and rotating mechanism (16). The channel between the integrated cavity (1/1’) and the first transfer cavity (5) is opened, and the wafer (9) is transferred to the first transfer cavity (5). S2. Wafer pre-cleaning: The wafer (9) is transferred from the first transfer cavity (5) to the pre-cleaning cavity (2/2’) for plasma pre-cleaning. The surface of the wafer (9) is cleaned for 12~16s, and then transferred to the first transfer cavity (5). S3, Wafer transfer: The wafer (9) enters the in-situ reflow composite processing cavity (6/6’) from the first transfer cavity (5), and is transferred to the second transfer cavity (5’) through the second transfer position (28), and then enters the process cavity (4/4’). S4. Wafer Cu thin film deposition: Cu thin film deposition is performed on the wafer (9) in the process cavity (4/4’), and the wafer (9) after film deposition is transferred from the process cavity to the second transfer cavity (5’). S5, Wafer Cu Thin Film Reflow: The wafer (9) is transferred from the second transfer cavity (5’) to the in-situ reflow composite processing cavity (6/6’), the second heating module (25) is turned on and the cavity is evacuated at the same time, so that the wafer (9) is heated to the reflow temperature quickly; S6. Wafer Cooling: Control the support mechanism (24) in the in-situ reflow composite processing cavity (6/6’) to move down to below the cooling chassis (22). The wafer (9) is placed in the second cooling position (29) on the cooling chassis (22). Water is circulated inside the cooling chassis (22) to cool the wafer (9). After cooling to a temperature <100℃, the support mechanism (24) moves up to move the wafer (9) to the second transfer position (28). Then the wafer (9) is transferred out of the in-situ reflow composite processing cavity (6/6’) and arrives at the first transfer cavity (5). S7. Wafer secondary deposition: The wafer (9) is transferred from the first transfer cavity (5) to the reprocessing cavity (3/3’) for secondary deposition of copper thin film; S8. Secondary cooling of wafer: After secondary deposition, the wafer (9) is transferred to the integrated cavity (1/1’) through the first transfer cavity (5) to cool the wafer (9) to below 100°C; S9, Wafer Transfer: After the wafer (9) is cooled twice, it moves from the first cooling position (21) to the first transfer position (20) and is transferred out of the entire PVD equipment. 7. The control method as described in claim 6, characterized in that, during the movement of step S1, the chamber is simultaneously evacuated to 5~7 torr, the first heating module (14) adopts an infrared radiation lamp array that can rapidly heat up and cool down, so that the wafer (9) is heated to 300°C within 10s and maintained at 300°C for heating and degassing; after the heating and degassing is completed, the first heating module (14) is turned off, and the chamber is continuously evacuated to a vacuum degree ≤1×10^-6 torr. 8. The control method as described in claim 6, wherein step S5 includes: firstly, the wafer (9) is transferred from the second transfer cavity (5’) to the second transfer position (28) of the in-situ reflow composite processing cavity (6/6’), then the support mechanism (24) moves upward, the wafer (9) enters the second heating position (27), and at the same time, the cavity is evacuated to 5~7 torr and the second heating module (25) is turned on; during the reflow process, the temperature of the wafer (9) surface is monitored in real time by the temperature monitoring system (26), and the power of the heating module is controlled in real time by the PLC to adjust the wafer surface temperature. 9. The control method as described in claim 8, wherein, in step S5, for films <30nm, the reflow temperature is 200~300℃ and the heating time is 20~40s; for films ≥30nm, the reflow temperature is 300~400℃ and the heating time is 50~70s. 10. The control method as described in claim 6, wherein step S8 includes: the wafer (9) after secondary deposition is transferred from the first wafer transfer position (20) to the first cooling position (21) in the integrated cavity (1/1’) by the lifting and rotating mechanism (16), the first cavity (7) is filled with gas to atmospheric pressure, and the gas flow channel and the lower water cooling channel are opened at the same time. The gas flow rate is between 150 and 200 SLM, and the water cooling flow rate is between 5 and 10 L/min, so that the wafer (9) is cooled to below 100°C within 30 seconds.