Imine curing method for wafer in diffusion furnace

Abstract

The invention relates to an imine curing method for wafers in a diffusion furnace, which comprises the following steps of: putting a plurality of wafers into a quartz boat, covering a protective cover, and introducing inert gas; pushing the quartz boat into the furnace tube, introducing inert gas into the furnace tube and the quartz boat, and heating the furnace tube to a first temperature limit; meanwhile, a switching bin is arranged above the furnace tube, a grabbing device is arranged in the switching bin, and the switching bin is communicated with the furnace tube; a grabbing hand of the grabbing device extends into the furnace tube, grabs the protective cover and brings the protective cover into the switching bin, a second opening between the switching bin and the furnace tube is closed through a switching door, meanwhile, a first opening of the switching bin is opened, the grabbing device is disassembled, the press sealing device is installed, the press sealing device presses the switching door downwards, and the furnace tube is closed; heating the furnace tube and the switching bin at the same time, performing imine curing on the wafer, and drawing an organic solvent volatilized by the wafer out of the furnace tube from a gas pipe of the switching door extending into the furnace tube; and after imine curing is completed, after the furnace tube is cooled, pulling out the quartz boat, covering the protective cover again, and introducing inert gas until the wafer is cooled to room temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of chip manufacturing, and particularly relates to an imide curing method for wafers in a diffusion furnace. Background Art

[0002] In the field of integrated circuit or discrete device chip manufacturing, a horizontal diffusion furnace is used to cure the wafer with imide. Currently, this process has the following problems: (1) Under certain temperature conditions, the metal on the wafer surface is prone to react with the oxygen in the diffusion furnace tube, causing the metal on the wafer surface to be oxidized, resulting in a series of problems such as color difference on the wafer surface, metal shedding, and parameter failure; (2) After the organic solvent in the imide evaporates in the diffusion furnace tube, if it is not discharged in time, it will come into contact with the metal on the wafer surface for a long time, which can easily cause color difference of the metal layer. Summary of the Invention

[0003] In view of the above problems, the present invention provides an imide curing method for wafers in a diffusion furnace, comprising the following steps:

[0004] S1: Place several wafers into a quartz boat one by one, cover it with a protective cover, and introduce inert gas into the quartz boat;

[0005] S2: Push the quartz boat into the furnace tube, introduce inert gas into both the furnace tube and the quartz boat, and heat the furnace tube to a first temperature limit;

[0006] At the same time, a switching chamber is provided above the furnace tube at the position corresponding to the quartz boat. A detachable and liftable grabbing device is provided in the switching chamber, and the switching chamber is connected to the internal space of the furnace tube.

[0007] S3: The gripper of the grabbing device extends into the furnace tube, grabs the protective cover on the quartz boat, and brings the protective cover into the switching chamber. The second opening between the switching chamber and the furnace tube is closed with the switching door. At the same time, the first opening of the switching chamber is opened. The grabbing device and the protective cover are removed, and the pressure sealing device is installed. The pressure sealing device presses down the switching door to seal the furnace tube.

[0008] S4: The furnace tube and the switching chamber are heated simultaneously, and the wafer is cured by imide. The air pipe extending from the switching door into the furnace tube passes through the switching chamber and the volatile organic solvent is extracted from the furnace tube.

[0009] S5: After the imide is cured, wait for the furnace tube to cool down, pull out the quartz boat, replace the protective cover, and introduce inert gas into the quartz boat until the wafer cools to room temperature.

[0010] Optionally, a wafer preservation step may be included before step S1, specifically: after the wafers are imide photolithography, the wafers are packed in batches and then placed in a cabinet filled with inert gas for storage, and a light-shielding film is affixed to the observation window of the cabinet.

[0011] Optionally, in step S1, the quartz boat is long and hollow inside, and the bottom surface of the quartz boat is a downwardly protruding arc surface, on which at least two upwardly protruding edges are provided, and the edges are extended along the length direction of the quartz boat; each edge is evenly provided with a number of downwardly concave grooves, and the grooves on all edges correspond to each other one by one, and the bottom of the wafer is stuck in the grooves at the corresponding positions of each edge to keep the wafer placed vertically.

[0012] Further optionally, all the grooves on each edge have the same inclination angle toward the front end or rear end of the quartz boat, so that after the wafer is inserted into the groove, it can also be inclined to follow the inclined surface of the groove. Moreover, the front side of the wafer is inclined upward and the back side is inclined downward, which is conducive to the volatilization of the organic solvent on the front side of the wafer.

[0013] Further optionally, an air inlet pipe and an air outlet pipe are respectively provided at both ends in the length direction of the quartz boat for inputting and exhausting gas; in step S2, when the quartz boat is pushed into the furnace tube, the air outlet pipe of the quartz boat can be inserted into the air outlet pipe of the furnace tube to exhaust together. After the position of the quartz boat in the furnace tube is determined, the air inlet pipe of the quartz boat is inserted into the air inlet pipe of the furnace tube, and the air inlet pipe ends of the two air inlet pipes are flush, so that air is input into the furnace tube while also into the quartz boat.

[0014] Optionally, the protective cover is in the shape of an elongated strip, a sealing strip is provided on the upper surface of the bottom edge of the protective cover, a sealing strip is provided on the inner side of the top edge of the quartz boat, and a vertical rebounder is provided at each end in the length direction of the quartz boat, and the elasticity of the rebounder is shortened upward.

[0015] In step S1, after the wafer is placed in the quartz boat, the protective cover is manually closed and buckled onto the top of the quartz boat. The top of the rebounder contacts the lower surface of the top surface of the protective cover. The protective cover is pressed firmly until the sealing strip of the protective cover is squeezed under the sealing strip of the quartz boat. At the same time, the rebounder is pressed into a contracted state, and the sealing strip of the quartz boat is stuck to the sealing strip of the protective cover, thus sealing the protective cover and the quartz boat. At this point, the top of the wafer in the quartz boat is close to but not touching the top surface of the protective cover.

[0016] In step S3, when the gripping device needs to remove the protective cover, the gripper of the gripping device pushes the protective cover downward, then the gripper disengages from the protective cover, pressing down on the protective cover and triggering the rebounder. The top of the rebounder pushes the protective cover upward. The upward force pushes the sealing strip of the protective cover to break through the restraint of the quartz boat sealing strip and move upward, separating the protective cover from the quartz boat. The gripper moves downward again, grabs the protective cover and rises, finally entering the switching chamber.

[0017] Further optionally, before the quartz boat enters the furnace tube, the temperature of the furnace tube is lower than 30°C; the first temperature limit is 50-70°C.

[0018] Optionally, a switching bin is connected to the top of the middle part of the furnace tube, which is in a cubic shape and hollow inside, and the material of the switching bin is the same as that of the furnace tube; an installation position is provided on the top of the switching bin for installing a grabbing device and a pressing device; a first opening is provided on the vertical side of the switching bin, and a second opening is provided on the top of the furnace tube and within the internal range of the switching bin; the first opening and the second opening are the same shape and size as the switching door, so that the switching door closes the first opening and the second opening at different times.

[0019] Further optionally, the switching door is square and has an arc, so that after the switching door closes the second opening, the switching door and the furnace tube form a cylinder; the edge of the inner side surface of the switching door is provided with an inner sealing strip, and the edge of the outer side surface is provided with an outer sealing strip; when the switching door closes the second opening, the inner side surface of the switching door is inside the furnace tube, and the outer side surface is inside the switching chamber, and the sealing effect is exerted by the inner sealing strip; when the switching door closes the first opening, the inner side surface of the switching door is inside the switching chamber, and the outer side surface faces the outside of the switching chamber, and the sealing effect is exerted by the outer sealing strip.

[0020] Optionally, the heating method in step S4 is: heating to 250-260°C at a heating rate of 1-1.5°C / min, and then maintaining the temperature for 80-100 minutes; then heating to 300-310°C at a heating rate of 1.5-2°C / min, and then maintaining the temperature for 140-160 minutes; then cooling to 30-50°C, and then maintaining the temperature for 120-180 minutes, and then stopping heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the furnace tube, quartz boat and switching chamber;

[0022] Figure 2 is a schematic diagram of a quartz boat and a protective cover;

[0023] Figure 3 This is a schematic diagram of the furnace tube and switching chamber when the switching door is closed.

[0024] In the accompanying drawings, 1-quartz boat, 2-edge, 3-groove, 4-protective cover, 5-furnace tube, 6-switching chamber, 7-grabbing device, 8-switching door, 9-first opening, 10-second opening, 11-upper top pipe, 12-lower top pipe, 13-inlet pipe, 14-outlet pipe, 15-rebounder, 16-lifter, 17-telescopic rod, 18-gripper, 19-trachea. DETAILED DESCRIPTION

[0025] This embodiment provides a method for curing imide in a diffusion furnace wafer. Figure 1-Figure 3 As shown, the following steps are included:

[0026] S1: Place several wafers one by one into the quartz boat 1, cover it with a protective cover 4, and introduce inert gas into the quartz boat 1;

[0027] S2: Push the quartz boat 1 into the furnace tube 5, introduce inert gas into both the furnace tube 5 and the quartz boat 1, and heat the furnace tube 5 to a first temperature limit;

[0028] At the same time, a switching chamber 6 is provided above the furnace tube 5 at a position corresponding to the quartz boat 1. A detachable and liftable grabbing device 7 is provided in the switching chamber 6. The switching chamber 6 is connected to the internal space of the furnace tube 5.

[0029] S3: The gripper 18 of the grabbing device 7 extends into the furnace tube 5, grabs the protective cover 4 on the quartz boat 1, and brings the protective cover 4 into the switching chamber 6. The second opening 10 between the switching chamber 6 and the furnace tube 5 is closed with the switching door 8. At the same time, the first opening 9 of the switching chamber 6 is opened. The grabbing device 7 and the protective cover 4 are removed, and the pressure sealing device is installed. The pressure sealing device presses down the switching door 8 to seal the furnace tube 5.

[0030] S4: The furnace tube 5 and the switching chamber 6 are heated simultaneously, and the wafer is cured by imide. The air pipe 19 extending from the switching door 8 into the furnace tube 5 passes through the switching chamber 6 to extract the volatilized organic solvent out of the furnace tube 5;

[0031] S5: After the imine is cured, wait for the furnace tube 5 to cool down, pull out the quartz boat 1, re-cover the protective cover 4, and introduce inert gas into the quartz boat 1 until the wafer cools down to room temperature.

[0032] Before the furnace tube 5 heats the wafers at high temperatures, the present invention protects the wafers within a protective chamber formed by the quartz boat 1 and protective cover 4. This prevents the metal on the wafer surface from reacting with the oxygen within the furnace tube 5 during the initial heating phase of the furnace tube 5. Specifically, the wafers are first placed within the protective chamber formed by the quartz boat 1 and protective cover 4, and an inert gas is introduced to protect the wafers. The quartz boat 1 is then pushed into the furnace tube 5, and inert gas is introduced into both the quartz boat 1 and the furnace tube 5 simultaneously, displacing any oxygen already present within the furnace tube 5. The present invention improves the furnace tube 5 by adding a switching chamber 6 above the portion of the furnace tube 5 that faces the quartz boat 1. This chamber is used to open the protective cover 4 and extract the volatile organic solvent within the furnace tube 5. The switching chamber 6 is preferably integrally formed with the furnace tube 5 for ease of processing and to ensure a tight seal at the connection between the switching chamber 6 and the furnace tube 5. A protruding furnace door is provided on the furnace chamber outside the furnace tube 5 at a position corresponding to the switching chamber 6, allowing the chamber to fully cover the furnace tube 5 and the switching chamber 6.

[0033] In step S2, the furnace tube 5 and the switching chamber 6 are heated simultaneously, and the oxygen in the furnace tube 5 and the switching chamber 6 is replaced with an inert gas. Since the heating temperature is not high at this time, the furnace door of the switching chamber 6 is not closed (only the furnace chamber corresponding to the rest of the furnace tube 5 is closed), which will not result in significant heat loss. The operation of step S2 ensures that during the initial stage of heating of the furnace tube 5, the metal on the wafer surface does not come into contact with the oxygen in the furnace tube 5 and does not react with the oxygen.

[0034] After the oxygen in the furnace tube 5 and the switching chamber 6 is basically replaced, the grabbing device 7 grabs the protective cover 4 into the switching chamber 6, exposing the wafers in the quartz boat 1. Then the connection between the switching chamber 6 and the furnace tube 5 is cut off and blocked with the switching door 8. A pressure sealing device is installed for the switching chamber 6 to press and seal the switching door 8. Then, the furnace tube 5 enters the high-temperature heating program to perform imide curing. The volatilized organic solvent is directly extracted by the air pipe on the switching door 8 of the corresponding quartz boat 1, minimizing the time the organic solvent stays in the furnace tube 5, minimizing the contact and reaction between the organic solvent and the wafer, improving the wafer quality, and reducing color difference and metal shedding.

[0035] Optionally, a wafer preservation step may be included before step S1, specifically: after the wafers are imide photolithography, the wafers are packed in batches and then placed in a cabinet filled with inert gas, such as a nitrogen cabinet. Nitrogen is introduced into the cabinet, and a light-shielding film is affixed to the observation window of the cabinet to protect the wafers inside and provide them with an inert, light-proof storage environment.

[0036] Before heating, use a high temperature resistant suction pen to suck up the back of the wafer, arrange several wafers side by side in the quartz boat 1, and heat the wafers in batches.

[0037] Optionally, in step S1, the quartz boat 1 is long and hollow inside, the longitudinal section of the quartz boat 1 is an inverted trapezoid (large at the top and small at the bottom), the bottom surface of the quartz boat 1 is a downwardly convex arc surface, and the arc surface is provided with at least two upwardly protruding edges 2, and the edges 2 are extended along the length direction of the quartz boat 1; each edge 2 is evenly provided with a number of downwardly concave grooves 3, and the grooves 3 on all edges 2 correspond to each other one by one, that is, all edges 2 are provided with only one groove 3 at corresponding positions, and the bottom of the wafer is stuck in the grooves 3 at corresponding positions of each edge 2 to keep the wafer placed vertically.

[0038] Further optionally, the bottoms of the two side surfaces of the quartz boat 1 are lower than the lowest point of the arc surface of the bottom of the quartz boat 1 , and the bottom edges of the two side surfaces are flush, which can stably support the quartz boat 1 .

[0039] Further optionally, all the grooves 3 on each edge 2 have the same inclination angle toward the front end or rear end of the quartz boat 1, so that after the wafer is inserted into the groove 3, it can also be inclined to follow the inclined surface of the groove 3, and the front side of the wafer is inclined upward and the back side is inclined downward, which is conducive to the volatilization of the organic solvent on the front side of the wafer.

[0040] Further optionally, the inclination angle of the groove 3 is 3-10°, and the spacing between adjacent grooves 3 is 5-10 mm. Multiple wafers can be arranged in a quartz boat 1, and one wafer is placed in one groove 3, so that wafers can be processed in batches.

[0041] The appropriate wafer spacing within the quartz boat 1 (i.e., the spacing of the grooves 3) and the tilt angle of the wafers allow for the timely and effective removal of organic solvents and other substances during imide curing, minimizing contact time with the metal front of the wafers, ensuring a clear, color-free wafer surface and maximizing single-furnace throughput. The tilt angle of the grooves 3 also prevents wafers from falling over.

[0042] Further optionally, an air inlet pipe 13 and an air outlet pipe 14 are respectively provided at both ends in the length direction of the quartz boat 1 for inputting and exhausting gas; in step S2, when the quartz boat 1 is pushed into the furnace tube 5, the air outlet pipe of the quartz boat 1 can be inserted into the air outlet pipe of the furnace tube 5 to exhaust together. After the position of the quartz boat 1 in the furnace tube 5 is determined, the air inlet pipe of the quartz boat 1 is inserted into the air inlet pipe of the furnace tube 5, and the air inlet pipe ends of the two air inlet pipes are flush, so that air is introduced into the furnace tube 5 while also into the quartz boat 1.

[0043] Optionally, the protective cover 4 is in the shape of an elongated strip, a sealing strip is provided on the upper surface of the bottom edge of the protective cover 4, a sealing strip is provided on the inner side of the top edge of the quartz boat 1, and a vertical rebounder 15 is provided at each end in the length direction, and the elasticity of the rebounder 15 is shortened upward.

[0044] In step S1, after the wafer is placed in the quartz boat 1, the protective cover 4 is manually closed and buckled onto the top of the quartz boat 1. The top of the rebounder 15 contacts the lower surface of the top of the protective cover 4. The protective cover 4 is pressed hard until the sealing strip of the protective cover 4 is squeezed under the sealing strip of the quartz boat 1. At the same time, the rebounder 15 is pressed to a retracted state. The sealing strip of the quartz boat 1 is stuck with the sealing strip of the protective cover 4, thus sealing the protective cover 4 and the quartz boat 1. At this time, the top of the wafer in the quartz boat 1 is close to but not in contact with the top surface of the protective cover 4.

[0045] In step S3, when the gripping device 7 needs to remove the protective cover 4, the gripper 18 of the gripping device 7 pushes the protective cover 4 downward, and the gripper 18 then detaches from the protective cover 4. The protective cover 4 is pressed down and triggers the rebounder 15. The top of the rebounder 15 pushes the protective cover 4 upward. The upward force pushes the sealing strip of the protective cover 4 to break through the restraint of the sealing strip of the quartz boat 1 and move upward, so that the protective cover 4 is separated from the quartz boat 1. The gripper 18 moves downward again and grabs the protective cover 4 and rises, finally entering the switching chamber 6.

[0046] Optionally, in step S1, according to the above method, the protective cover 4 is closed, the inert gas source is connected to the air inlet pipe of the quartz boat 1 with an air pipe, and the air outlet pipe of the quartz boat 1 is connected to the waste gas tank or the fume hood. After replacing the oxygen in the quartz boat 1 and the protective cover 4, the air inlet and outlet pipes of the quartz boat 1 are closed.

[0047] Optionally, in step S2, according to the above method, use a quartz short hook to push the quartz boat 1 together with the protective cover 4 into the mouth of the furnace tube 5, then hang one end of the quartz push-pull rod on the quartz boat 1 and the other end on the manipulator, cover the quartz opening furnace cap, and close the open furnace door; connect the inlet pipe of the furnace tube 5 to an inert gas source, and connect the outlet pipe of the furnace tube 5 to an exhaust gas tank or a fume hood;

[0048] Close the furnace chamber outside the furnace tube 5, leaving only the furnace door of the furnace chamber corresponding to the switching chamber 6 open; start the heating device in the furnace chamber to perform the first stage of heating.

[0049] Optionally, before the quartz boat 1 enters the furnace tube 5, the temperature of the furnace tube 5 is below 30°C; the first temperature limit is 50-70°C. The wafers enter the furnace at a low temperature and are protected by the nitrogen environment within the quartz boat 1 and the protective cover 4. This effectively prevents the oxygen in the furnace tube 5 from reacting with the metal on the front surface of the wafers at a higher temperature during the entry process.

[0050] Optionally, a switching bin 6 is connected to the top of the middle part of the furnace tube 5. The switching bin 6 is cubic in shape and hollow inside. The material of the switching bin 6 is the same as that of the furnace tube 5. An installation position is provided on the top of the switching bin 6 for installing a grabbing device 7 and a pressure sealing device. A first opening 9 is provided on the vertical side of the switching bin 6, and a second opening 10 is provided on the top of the furnace tube 5 and within the internal range of the switching bin 6. The first opening 9 and the second opening 10 are the same shape and size as the switching door 8, so that the switching door 8 closes the first opening 9 and the second opening 10 at different times.

[0051] Further optionally, the switching door 8 is square and has a curvature, so that after the switching door 8 closes the second opening 10, the switching door 8 and the furnace tube 5 form a cylinder; the edge of the inner side surface of the switching door 8 is provided with an inner sealing strip, and the edge of the outer side surface is provided with an outer sealing strip; when the switching door 8 closes the second opening 10, the inner side surface of the switching door 8 is inside the furnace tube 5, and the outer side surface is inside the switching chamber 6, and the sealing effect is exerted by the inner sealing strip; when the switching door 8 closes the first opening 9, the inner side surface of the switching door 8 is inside the switching chamber 6, and the outer side surface faces the outside of the switching chamber 6, and the sealing effect is exerted by the outer sealing strip.

[0052] Optionally, in step S2, the switching chamber 6 is connected to the internal space of the furnace tube 5, which means that the switching door 8 closes the first opening 9, and a handle is provided on the outer side of the switching door 8, and a stepped groove 3 is provided on the inner side of the edge of the first opening 9, corresponding to the outer sealing strip. The handle is pulled outward manually or mechanically, so that the groove 3 on the edge of the switching door 8 and the inner side of the first opening 9 squeezes the outer sealing strip from both sides, thereby closing the switching chamber 6.

[0053] Optionally, in step S3, the use of the switching door 8 to close the second opening 10 between the switching chamber 6 and the furnace tube 5 refers to manually or mechanically pushing the handle and the switching door 8 into the switching chamber 6 quickly, and the switching door 8 drives its own outer sealing strip to leave the first opening 9, so that the first opening 9 is open; the outer side surface of the edge of the second opening 10 (that is, the outer side of the furnace tube 5) is provided with a stepped groove 3, which corresponds to the inner sealing strip, and at the same time, the switching door 8 quickly covers the second opening 10, so that the groove 3 on the edge of the switching door 8 and the outer side surface of the second opening 10 squeezes the inner sealing strip from both sides, thereby closing the furnace tube 5.

[0054] Further optionally, a plurality of air pipes 19 are evenly arranged on the switching door 8. The air pipes 19 are made of metal and can withstand high temperatures. The air pipes 19 are provided with sealing rings at the locations where they pass through the switching door 8 to prevent air leakage. The air pipes 19 pass out of the furnace chamber and are connected to an external waste bottle or fume hood to drain the organic solvent volatilized in the furnace tube 5. The air pipes outside the furnace chamber can be connected to rubber pipes.

[0055] In steps S2 and S3, the air outlet end of the trachea remains closed.

[0056] The gripping device 7 can be a conventional gripping device 7, for example, comprising, from top to bottom, a lifter 16, two telescopic rods 17, and two grippers 18. The top ends of the telescopic rods 17 are connected to the lifting shaft of the lifter 16, and the bottom ends of the telescopic rods 17 are connected to the grippers 18. The grippers 18 are connected to a controller inside the lifter 16 via wiring arranged within the corresponding telescopic rods 17. The controller controls the grippers 18 to close or release. After the protective cover 4 is lifted by the rebounder 15 according to the above method, it is separated from the quartz boat 1, facilitating the grippers 18 to grasp the protective cover 4 in step S3.

[0057] In step S3, the gripping device 7 and the protective cover 4 are removed. The mounting position can be connected to the gripping device 7 in a variety of ways, such as snap connection or screw connection. When removing the gripping device 7, it can be removed in a corresponding manner according to the installation form of the gripping device 7. This belongs to the prior art.

[0058] Optionally, the pressure sealing device is made of metal and includes an upper top tube 11, a lower top tube 12 and a spring. The upper top tube 11 and the lower top tube 12 are both hollow cylinders. The top end of the upper top tube 11 is sealed and the bottom end is open, and the top end of the lower top tube 12 is open and the bottom end is sealed; the middle and lower part of the upper top tube 11 is inserted into the middle and upper part of the lower top tube, the bottom of the spring is connected to the bottom end of the lower top tube, and the top of the spring is connected to the top end of the upper top tube. The length of the upper top tube extending out of the lower top tube is adjusted according to the expansion and contraction of the spring, thereby adjusting the total length of the pressure sealing device.

[0059] The spring is a strong spring. When the pressure sealing device is pressed against the top of the switching door and the switching chamber, the elastic force of the spring supports and presses the upper top tube upward and the lower top tube downward, so as to press the switching door tightly.

[0060] In step S3, the pressure-sealing device is installed. The pressure-sealing device presses down the switching door 8 to seal the furnace tube 5. This means that the upper and lower top tubes 11 and 12 are shortened so that they can be placed into the switching chamber 6 through the first opening 9. The pressure-sealing device stands upright, with the bottom end of the lower top tube 12 pressing against the switching door 8 and the top end of the upper top tube 11 pressing against the mounting position at the top of the switching chamber 6. The strong spring naturally extends, causing the pressure-sealing device to apply downward pressure (i.e., pressure on the switching door 8), thereby pressing the switching door 8 tightly against the second opening 10 of the furnace tube 5. The top end of the upper top tube 11 can be pressed into contact with the mounting position.

[0061] Optionally, the furnace bin is arranged outside the furnace tube 5 and the switching bin 6, and is responsible for heating and insulating the furnace tube 5 and the switching bin 6. The shape of the furnace bin conforms to and fits the outer shape of the furnace tube 5 and the switching bin 6. The furnace bin is provided with a protruding furnace door at the position corresponding to the switching bin 6. The shape of the furnace door conforms to and fits the outer shape of the switching bin 6. The furnace door is hinged on the furnace bin and can be opened and closed. In step S4, after the furnace door is closed and covers the switching bin 6, thermal insulation material can be set at the connecting seam between the furnace door and the furnace bin.

[0062] Optionally, in step S4, the air pipe 19 passes through the switching chamber 6, then passes through the furnace door, and is then connected to the air pump; the air inlet end of the air pipe 17 is inside the furnace tube 5 and above the quartz boat 1, that is, the air inlet end of the air pipe 17 corresponds to above the wafer, and can specifically absorb the organic solvent volatilized from the wafer and discharge it immediately from the furnace tube 5 and the switching chamber 6.

[0063] Optionally, the heating method in step S4 is: heating to 250-260°C at a heating rate of 1-1.5°C / min, and then maintaining the temperature for 80-100 minutes; then heating to 300-310°C at a heating rate of 1.5-2°C / min, and then maintaining the temperature for 140-160 minutes; then cooling to 30-50°C, and then maintaining the temperature for 120-180 minutes, and then stopping heating.

[0064] Optionally, in steps S2-S4, an inert gas, such as nitrogen, is continuously introduced into the furnace tube 5, and the flow rate of the inert gas is 50-80 L / min; in step S5, during the cooling process of the wafer in the furnace tube 5, an inert gas is continuously introduced into the furnace tube 5 at a flow rate of 50-80 L / min.

[0065] Optionally, in step S5, outside the furnace tube, after the wafer is cooled in the quartz boat 1 and the protective cover 4, the protective cover 4 is removed, the wafer and the quartz boat 1 are placed in a clean bench, and then cooled for another 5-10 minutes, and then a high-temperature resistant suction pen is used to suck the back of the wafer, and the wafer is placed in a box and sent to the next step.

[0066] In step S5, the wafer is taken out of the oven at a low temperature, which effectively prevents the metal on the front from oxidizing with the oxygen in the clean bench due to the high temperature of the wafer itself.

[0067] The sealing materials used in the present invention, such as the inner sealing strip, the outer sealing strip, the sealing ring, etc., are all high-temperature resistant sealing materials, such as special silicone rubber or fluororubber.

Claims

1. A method for curing wafers with imide in a diffusion furnace, characterized in that: include: S1: Place several wafers into a quartz boat, cover it with a protective cover, and introduce inert gas into the quartz boat; S2: Push the quartz boat into the furnace tube, introduce inert gas into both the furnace tube and the quartz boat, and heat the furnace tube to a first temperature limit; At the same time, a switching chamber is provided above the furnace tube at the position corresponding to the quartz boat. A detachable and liftable grabbing device is provided in the switching chamber, and the switching chamber is connected to the internal space of the furnace tube. S3: The gripper of the grabbing device extends into the furnace tube, grabs the protective cover on the quartz boat, and brings the protective cover into the switching chamber. The second opening between the switching chamber and the furnace tube is closed with the switching door. At the same time, the first opening of the switching chamber is opened. The grabbing device and the protective cover are removed, and the pressure sealing device is installed. The pressure sealing device presses down the switching door to seal the furnace tube. S4: The furnace tube and the switching chamber are heated simultaneously, and the wafer is cured by imide. The air pipe extending from the switching door into the furnace tube passes through the switching chamber and the volatile organic solvent is extracted from the furnace tube. S5: After the imide is cured, wait for the furnace tube to cool down, pull out the quartz boat, replace the protective cover, and introduce inert gas into the quartz boat until the wafer cools to room temperature.

2. The imide curing method for wafers in a diffusion furnace according to claim 1, characterized in that: Before step S1, a wafer preservation step is also included, specifically: after the wafer is imide photolithography, the wafer is packed into a box and then placed in a cabinet filled with inert gas for storage, and a light-shielding film is attached to the observation window of the cabinet.

3. The imide curing method for wafers in a diffusion furnace according to claim 1, characterized in that: In step S1, the quartz boat is long and hollow inside. The bottom surface of the quartz boat is a downwardly convex arc surface with at least two upwardly convex edges provided on the arc surface. The edges are arranged along the length of the quartz boat. Each edge is evenly provided with a plurality of downwardly concave grooves. The grooves on all edges correspond to each other one by one. The bottom of the wafer is inserted into the grooves at the corresponding positions on each edge. All the grooves on each edge have the same inclination angle toward the front end or rear end of the quartz boat, so that after the wafer is clamped into the groove, it can also be inclined according to the inclined surface of the groove.

4. The imide curing method for wafers in a diffusion furnace according to claim 3, characterized in that: The quartz boat is provided with an air inlet pipe and an air outlet pipe at both ends in the length direction for inputting and exhausting gas respectively; in step S2, when the quartz boat is pushed into the furnace tube, the air outlet pipe of the quartz boat can be inserted into the air outlet pipe of the furnace tube to exhaust together. After the position of the quartz boat in the furnace tube is determined, the air inlet pipe of the quartz boat is inserted into the air inlet pipe of the furnace tube, and the air inlet pipe ends of the two air inlet pipes are flush, so that air is input into the furnace tube and the quartz boat at the same time.

5. The imide curing method for wafers in a diffusion furnace according to claim 4, characterized in that: The protective cover is in the shape of an elongated strip, and a sealing strip is provided on the upper surface of the bottom edge of the protective cover, and a sealing strip is provided on the inner side of the top edge of the quartz boat. A vertical rebounder is provided at each end in the length direction of the quartz boat, and the elasticity of the rebounder is shortened upward.

6. The imide curing method for wafers in a diffusion furnace according to claim 5, characterized in that: In step S1, after the wafer is placed in the quartz boat, the protective cover is buckled on the top of the quartz boat, the top of the rebounder contacts the lower surface of the top surface of the protective cover, and the protective cover is pressed hard until the sealing strip of the protective cover is squeezed under the sealing strip of the quartz boat. At the same time, the rebounder is pressed to a contracted state, and the sealing strip of the quartz boat is stuck with the sealing strip of the protective cover, thus achieving the sealing of the protective cover and the quartz boat; In step S3, when the gripping device needs to take out the protective cover, the gripper of the gripping device pushes the protective cover downward, and the gripper then separates from the protective cover. The protective cover is pressed down and triggers the rebounder. The top of the rebounder pushes the protective cover upward. The lifting force pushes the sealing strip of the protective cover to break through the restraint of the sealing strip of the quartz boat and move upward, so that the protective cover is separated from the quartz boat; the gripper moves down again and grabs the protective cover and rises into the switching chamber.

7. The imide curing method for wafers in a diffusion furnace according to claim 1, characterized in that: In step S2, before the quartz boat enters the furnace tube, the temperature of the furnace tube is lower than 30°C; the first temperature limit is 50-70°C.

8. The imide curing method for wafers in a diffusion furnace according to claim 1, characterized in that: The top of the middle part of the furnace tube is connected to a switching bin, which is cubic in shape and hollow inside. The material of the switching bin is the same as that of the furnace tube. An installation position is provided on the top of the switching bin for installing a grabbing device and a pressing and sealing device. A first opening is provided on the vertical side of the switching bin, and a second opening is provided on the top of the furnace tube and within the internal range of the switching bin. The first opening and the second opening are the same in shape and size as the switching door, so that the switching door closes the first opening and the second opening at different times.

9. The imide curing method for wafers in a diffusion furnace according to claim 8, characterized in that: The switching door is square and has an arc, so that after the switching door closes the second opening, the switching door and the furnace tube form a cylinder; the edge of the inner side surface of the switching door is provided with an inner sealing strip, and the edge of the outer side surface is provided with an outer sealing strip; when the switching door closes the second opening, the inner side surface of the switching door is inside the furnace tube, and the outer side surface is inside the switching chamber, and the sealing effect is exerted by the inner sealing strip; when the switching door closes the first opening, the inner side surface of the switching door is inside the switching chamber, and the outer side surface faces the outside of the switching chamber, and the sealing effect is exerted by the outer sealing strip.

10. The imide curing method for wafers in a diffusion furnace according to claim 1, characterized in that: The heating method in step S4 is: heating to 250-260°C at a heating rate of 1-1.5°C / min, and then maintaining the temperature for 80-100 minutes; then heating to 300-310°C at a heating rate of 1.5-2°C / min, and then maintaining the temperature for 140-160 minutes; then cooling to 30-50°C, and then maintaining the temperature for 120-180 minutes, and then stopping heating.

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