Method for improving wafer scratch of furnace tube machine and furnace tube machine

Abstract

The present application provides a method for improving wafer scratch of furnace tube machine and furnace tube machine. The method comprises the following steps: step one, in the stage of unloading the boat, opening the first purge part and closing the second purge part, and passing the cooling gas into the boat to cool the wafer; step two, in the stage of unloading the boat, opening the first purge part and the second purge part, and passing the cooling gas into the boat to cool the wafer. The present application controls the opening state and flow of the purge assembly in stages, adopts local small flow purge in the high temperature sensitive period of the boat movement, slows down the cooling rate to reduce the thermal deformation of the wafer, and then carries out overall rapid cooling after the boat is stationary. The present application can effectively prevent the wafer from jumping and scratching in the unloading process, improve the product yield and shorten the production cycle.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing, and in particular to a method for improving wafer scratching on a furnace tube machine and the furnace tube machine itself. Background Technology

[0002] Vertical furnace tube machines play a crucial role in the upstream processes of semiconductor production lines. Typically, by controlling processes such as oxidation, diffusion, annealing, and alloying of semiconductor materials, the electrical properties, thin film structure, defects, and stress of semiconductor materials can be altered, thereby improving the performance and reliability of semiconductor devices and making them more suitable for various applications.

[0003] In existing furnace tube high-temperature annealing processes, the process formulation temperature typically reaches 1000℃~1150℃. Under such high temperatures, uneven heating of different parts of the wafer generates thermal stress. Generally, the temperature difference between the wafer's edge and center is significant, causing the wafer to exhibit an upward or downward bending shape. When the thermal stress exceeds the wafer's tolerance limit, the wafer will warp and deform.

[0004] During boat unloading after the process is complete, the furnace tube machine typically maintains a high temperature of around 700°C. After the wafer exits the furnace, due to the significant temperature difference between the inside and outside, existing standard operating procedures usually employ high-flow-rate nitrogen purging for rapid cooling. However, this direct purging of high-flow-rate gas can cause severe deformation of the wafer at its high temperature (i.e., "wafer skipping"). During the cooling process, the wafer deforms due to heat, and the combined effects of the high-flow-rate gas turbulence and the top-down movement of the boat can easily cause the wafer surface to rub against the edges of the boat teeth, resulting in point-like scratches at the support rod locations.

[0005] Wafer scratches caused by temperature differences and rapid cooling not only reduce product yield but also increase the time cost of downtime to replace wafer boats, severely restricting product circulation efficiency and production cost control.

[0006] Therefore, how to improve the contact temperature of the wafer during unloading, slow down the wafer cooling rate to reduce wafer deformation, and thus reduce the risk of scratches has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The technical problem to be solved by this invention is that during the unloading of the wafer boat in the high-temperature annealing process of the furnace tube, the huge temperature difference between the inside and outside of the furnace and the rapid cooling of the large flow of cooling gas cause the wafer to undergo severe deformation and chipping, which in turn affects the product yield and production efficiency.

[0008] A method for improving wafer scratches on a furnace tube machine is provided, applied to the furnace tube machine, the furnace tube machine including a purging assembly, the purging assembly including a first purging section and a second purging section, the method including: Step 1, during the wafer unloading stage, opening the first purging section and closing the second purging section, and introducing cooling gas into the wafer boat to cool the wafer; Step 2, during the wafer unloading completion stage, simultaneously opening the first purging section and the second purging section, and introducing the cooling gas into the wafer boat to cool the wafer.

[0009] Preferably, the cooling gas includes nitrogen.

[0010] Preferably, in step one, before the unloading stage of the wafer boat, the wafer undergoes an annealing process at a temperature of 1000℃~1150℃.

[0011] Preferably, in step one, the initial temperature of the unloading stage of the crystal boat is 650℃~750℃.

[0012] Preferably, in step one, the flow rate of the cooling gas introduced into the first purging section is a first preset flow rate.

[0013] Preferably, in step one, the second purging section is turned off to prevent the cooling gas from blowing directly onto the wafer surface.

[0014] Preferably, in step two, the crystal boat is in a stationary state.

[0015] Preferably, in step two, after simultaneously activating the first purging section and the second purging section, the cooling gas is continuously supplied at a second preset flow rate.

[0016] Preferably, in step two, the second preset flow rate is greater than the flow rate of the cooling gas introduced into the first purging section in step one.

[0017] Preferably, a furnace tube machine includes: a purging assembly, the purging assembly including a first purging section and a second purging section; and a controller, the controller being communicatively connected to the first purging section and the second purging section, the controller being configured to perform the above method.

[0018] As described above, the method for improving wafer scratching in furnace tube equipment and the furnace tube equipment of the present invention have the following beneficial effects:

[0019] This invention optimizes the purging process into two stages. During the dynamic process of unloading the wafer boat, localized purging slows down the cooling rate, reducing wafer deformation caused by temperature differences and preventing scratches between the wafer surface and the wafer boat teeth. Full-flow purging is then initiated after the wafer boat comes to a stop, ensuring cooling efficiency and reducing the risk of wafer skipping. This solution improves product yield, reduces downtime for maintenance due to scratches, accelerates product flow on the production line, and lowers manufacturing costs. Attached Figure Description

[0020] Figure 1 The diagram shows a process flow diagram of the method for improving wafer scratching in furnace tube equipment according to the present invention.

[0021] Figure 2 The diagram shows the purging state during the unloading stage of the crystal boat according to the present invention.

[0022] Figure 3 This diagram illustrates the purging state at the end of the unloading phase of the crystal boat according to the present invention. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] A method for improving wafer scratches on a furnace tube machine is applied to the furnace tube machine, which includes a purging assembly 10. The purging assembly 10 includes a first purging section 101 and a second purging section 102. The method includes:

[0025] Step 1: During the unloading stage of the crystal boat, the first purging unit 101 is turned on and the second purging unit 102 is turned off, and cooling gas is introduced into the crystal boat 20 to cool the wafer.

[0026] Combination Figure 2 The schematic diagram of step one shown illustrates that during the unloading stage of the crystal boat, the crystal boat 20, driven by the drive mechanism, moves along the vertical direction (e.g., ...). Figure 2The wafer boat 20, carrying a batch of wafers, is uniformly moved out of the high-temperature reaction tube from the interior using a horizontal guide rail (indicated by the black downward arrow in the middle). The furnace tube machine can be configured as a vertical furnace tube, a horizontal furnace tube, an atmospheric pressure chemical vapor deposition machine, a reduced pressure chemical vapor deposition machine, an atomic layer deposition machine, or a diffusion furnace. The purging assembly 10 can be installed in the loading chamber, transition chamber, atmospheric transport module, or wafer boat storage area of ​​the furnace tube machine. The first purging section 101 and the second purging section 102 can respectively include multiple gas nozzles, a gas distribution plate, a porous ceramic plate, a slit-type air outlet, or an annular purging ring. Figure 2 As shown, by activating only the first purging section 101 while keeping the second purging section 102 closed, a controlled initial cooling environment can be established around the crystal boat 20. This asymmetric or localized purging mode effectively reduces the instantaneous thermal shock generated by the cooling gas on the high-temperature wafer, preventing severe thermal stress deformation of the wafer due to excessive internal and external temperature differences. This controlled cooling method ensures that the wafer remains physically stable at the toothed end of the crystal boat 20, reducing scratches caused by wafer warping, jumping, or displacement, thereby improving the manufacturing yield of semiconductor devices.

[0027] In some embodiments, prior to the unloading stage of the wafer boat in step one, the wafer undergoes an annealing process at a temperature of 1000°C to 1150°C. The annealing process may include rapid thermal annealing, peak annealing, laser annealing, or long-time furnace tube annealing. The annealing process can be performed in a process atmosphere containing nitrogen, hydrogen, oxygen, argon, or a combination thereof. The purpose of the annealing process may include activating doped impurities, repairing lattice damage caused by ion implantation, improving the contact characteristics between the metal and the semiconductor, adjusting the thin film stress of the dielectric layer, or promoting the formation of silicides. At such high process temperatures, a large amount of heat accumulates inside the wafer, and its lattice is in a state of thermal expansion, resulting in a decrease in physical strength compared to the room temperature state. Therefore, high requirements are placed on temperature gradient control during the unloading process.

[0028] In some embodiments, the initial temperature during the unloading stage of the wafer boat in step one is 650°C to 750°C. The initial temperature can also be set within the range of 600°C to 800°C. The furnace tube system uses a heater to programmatically control the cooling of the reaction tube. When the temperature sensor detects that the temperature inside the reaction tube has reached this preset temperature range, the controller issues a command to open the unloading gate mechanism. Controlling the initial unloading temperature within this range helps to provide a temperature buffer before the wafer enters the external atmosphere. Combined with the subsequent controlled purging of the first purging section 101, it can smoothly release the thermal stress inside the wafer, preventing microcracks or severe geometric distortions on the wafer surface due to rapid cooling.

[0029] In some embodiments, in step one, the flow rate of cooling gas introduced into the first purging section 101 is a first preset flow rate. The first preset flow rate can be precisely adjusted by a mass flow controller. The value of the first preset flow rate can be dynamically set according to the wafer diameter, the slot spacing of the wafer boat 20, and the wafer loading density. A smaller first preset flow rate can form a stable laminar or quasi-laminar airflow, uniformly removing heat from the wafer edges, thereby maintaining the wafer's static state within the wafer boat 20.

[0030] In some embodiments, in step one, the second purging section 102 is shut down to prevent cooling gas from directly blowing onto the wafer surface. By shutting down the second purging section 102 during the initial unloading phase, the direct impact of high-velocity cold airflow on the high-temperature central region of the wafer can be eliminated. This localized purging strategy enables the wafer to achieve more uniform radial shrinkage from the edge to the center, preventing severe warping or bowl-shaped deformation. This approach ensures that the contact stress between the wafer and the support teeth of the wafer boat 20 remains within a safe threshold, effectively preventing wafer skipping and subsequent pinhole scratches caused by thermal deformation.

[0031] In some embodiments, the cooling gas includes nitrogen. The cooling gas may also be selected from inert gases such as argon, helium, neon, and krypton, or mixtures thereof. In some oxidation-insensitive processes, the cooling gas may also include dry air that has undergone ultra-clean filtration and deionization. Nitrogen, due to its chemical stability, good thermal conductivity, and low cost, can effectively perform cooling tasks and prevent unintended oxidation reactions or organic contamination of the wafer surface during cooling. The purity of the cooling gas can be set according to the requirements of the process node.

[0032] Step 2: At the end of the unloading stage of the crystal boat, the first purging unit 101 and the second purging unit 102 are turned on at the same time to introduce cooling gas into the crystal boat 20 to cool the wafer.

[0033] Combination Figure 3 The schematic diagram of step two shows that after the wafer boat 20 is completely removed from the reaction tube and reaches the predetermined position of the unloading station, the wafer temperature has dropped from the initial unloading temperature to a lower level. At this point, the physical structure of the wafer has become stable and is no longer prone to drastic thermal deformation. Figure 3 As shown, by simultaneously activating the first purging section 101 and the second purging section 102, the total supply and coverage area of ​​cooling gas can be significantly increased, thereby accelerating the cooling process of the wafer to ambient temperature. This dual purging mode can significantly shorten the auxiliary cooling time of the entire production cycle and improve the output efficiency of the machine.

[0034] In some embodiments, during step two, the crystal boat 20 is in a stationary state. For example... Figure 3As shown, after the crystal boat 20 stops moving, the wafer is no longer affected by the vibration generated by the mechanical transmission. At this time, the mechanical strength of the wafer has been basically restored, and its sensitivity to airflow impact has been greatly reduced. Increasing the purging intensity in a static state can ensure that the cooling gas fully penetrates into every slot of the crystal boat 20, achieving highly consistent cooling of batch wafers without inducing dynamic frictional scratches between the wafer and the support structure.

[0035] In some embodiments, in step two, after simultaneously activating the first purge unit 101 and the second purge unit 102, a second preset flow rate of cooling gas is maintained. This second preset flow rate can be shared by the first purge unit 101 and the second purge unit 102, forming an all-around cooling air curtain surrounding the wafer boat 20. Through the synergistic effect of multiple gas streams, it can be ensured that the wafer cools to a safe temperature accessible to subsequent handling robots or operators within a short time.

[0036] In some embodiments, in step nine, the second preset flow rate is greater than the flow rate of the cooling gas introduced into the first purging section 101 in step one. This stepped flow control strategy follows the physical characteristics of wafers, which have different levels of thermal stress tolerance at different temperature stages. Low flow rate is used for localized protection during high-temperature sensitive periods, while high flow rate is used for overall cooling during low-temperature stable periods. This flow gradient design effectively optimizes the heat removal rate, protecting wafer surface quality while minimizing non-productive time on the equipment and reducing the manufacturing cost per wafer.

[0037] A furnace tube machine, characterized in that it comprises:

[0038] The purging assembly 10 includes a first purging section 101 and a second purging section 102; and

[0039] The controller is communicatively connected to the first purge unit 101 and the second purge unit 102, and is configured to execute the above method.

[0040] The furnace tube assembly may also include a reaction tube, a multi-stage resistance heater surrounding the reaction tube, a furnace door mechanism for sealing the bottom of the reaction tube, a quartz or silicon carbide wafer boat 20 for carrying the wafer, and a screw drive mechanism for driving the wafer boat 20 to move up and down. The wafer boat 20 may be made of high-purity quartz, silicon carbide, silicon nitride, or a material coated with a diamond-like carbon layer. The purging assembly 10 may be integrated into the frame of the furnace tube assembly or mounted on the side wall of the unloading path of the wafer boat 20. The first purging section 101 and the second purging section 102 may use independent gas supply lines, each line equipped with an independent pressure regulating valve, a solenoid switching valve, and a mass flow meter. The controller may include a central processing unit, non-volatile memory, and a digital input / output interface. The controller receives feedback signals from thermocouples, optical position sensors, and pressure sensors, calculates in real time, and outputs a pulse width modulation signal or an analog voltage signal to the actuator of the purging assembly 10. This highly automated control system ensures that each batch of wafers is unloaded under strictly consistent cooling conditions, eliminating the uncertainty of manual operation and thus improving the stability and repeatability of semiconductor manufacturing processes.

[0041] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0042] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for improving wafer scratches on a furnace tube machine, applied to a furnace tube machine, the furnace tube machine comprising a purging assembly, the purging assembly comprising a first purging section and a second purging section, characterized in that, The method includes: Step 1: During the unloading stage of the wafer boat, the first purging section is turned on and the second purging section is turned off, and cooling gas is introduced into the wafer boat to cool the wafer. Step 2: At the end of the unloading stage of the crystal boat, the first purging unit and the second purging unit are turned on simultaneously to introduce the cooling gas into the crystal boat to cool the wafer.

2. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: The cooling gas includes nitrogen.

3. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step one, before the unloading stage of the wafer boat, the wafer undergoes an annealing process at a temperature of 1000℃~1150℃.

4. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step one, the initial temperature of the unloading stage of the crystal boat is 650℃~750℃.

5. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step one, the initial temperature of the unloading stage of the crystal boat is 650℃~750℃.

6. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step one, the second purging section is turned off to prevent the cooling gas from blowing directly onto the wafer surface.

7. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step two, the crystal boat is in a stationary state.

8. The method for improving wafer scratches on a furnace tube machine according to claim 1, characterized in that: In step two, after simultaneously activating the first purging section and the second purging section, the cooling gas is continuously supplied at a second preset flow rate.

9. The method for improving wafer scratches on a furnace tube machine according to claim 8, characterized in that: In step two, the second preset flow rate is greater than the flow rate of the cooling gas introduced into the first purging section in step one.

10. A furnace tube machine, characterized in that, include: A purging assembly, comprising a first purging section and a second purging section; as well as A controller, which is communicatively connected to the first purge unit and the second purge unit, is configured to perform the method as described in any one of claims 1 to 9.

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