Pushing and trapping method for improving wafer surface flatness

Abstract

The application provides a push-well method for improving the flatness of a wafer surface, a furnace tube, a plurality of doped wafers arranged on a wafer boat, a buffer path between the wafer boat and the furnace tube opening, a first preset temperature in the furnace tube, and a second preset temperature of the environment where the wafer boat is located; the furnace tube opening is opened, so that the temperature between the furnace tube opening and the wafer boat is gradiently decreased; the wafer boat is moved into the furnace tube, and then the furnace tube opening is closed, and the wafers are subjected to push-well treatment in the furnace tube; the furnace tube opening is opened, so that the temperature between the furnace tube opening and the wafer boat is gradiently decreased; and the wafer boat is moved out of the furnace tube. In the process of lifting the wafer boat in the furnace tube, a certain heat radiation buffer area is formed at the furnace tube opening, so that the thermal stress generated in the process of entering and leaving the furnace tube is reduced, the flatness of the wafer periphery is improved, and the photoetching alignment uniformity is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a push-well method for improving wafer surface flatness. Background Technology

[0002] In semiconductor manufacturing processes, after ion implantation, wafers typically require high-temperature processing. The purpose of this high-temperature process is as follows:

[0003] 1. At high temperatures (1000°C to 1200°C), the wafer undergoes a push-in process for a certain period of time, allowing the injected impurities to diffuse within the wafer and form the desired P / N junction.

[0004] 2. During the entire high-temperature process, impurities will bond with silicon atoms in the crystal lattice, activating the impurity atoms and changing the conductivity of silicon.

[0005] 3. The high-temperature process has an annealing effect, which can repair the damage caused by ion implantation.

[0006] High-temperature processes introduce thermal stress, which can affect wafer warping or cause localized deformation. Wafer deformation can lead to poor photolithography alignment.

[0007] When a high-temperature furnace tube is not in use, it is typically maintained at 800 degrees Celsius. When a wafer at room temperature (23-26 degrees Celsius) enters the furnace tube, the rapid temperature change causes some deformation around the wafer's periphery. Similarly, when a wafer is unloaded from the furnace, it is directly transferred from 800 degrees Celsius to room temperature, which also causes some deformation. Therefore, wafers at the top and bottom ends of the wafer boat are more prone to deformation.

[0008] Traditional high-temperature processes reduce the speed of the wafer boat or lower the temperature to 700 degrees Celsius before use to improve thermal stress, but cannot completely solve the problem of wafer periphery deformation.

[0009] To address the aforementioned issues, a novel push-well method for improving wafer surface flatness is needed. Summary of the Invention

[0010] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a wafer push-in method to improve the surface flatness of wafers, which solves the problem that when wafers at room temperature (23-26 degrees Celsius) enter the furnace tube, the rapid temperature change causes deformation around the wafer periphery. Similarly, when wafers are unloaded from the furnace, they go directly from a high temperature to room temperature, which also causes deformation, with the wafers at the top and bottom ends of the wafer boat being more prone to deformation.

[0011] To achieve the above and other related objectives, the present invention provides a push-well method for improving wafer surface flatness, comprising:

[0012] Step 1: Provide a furnace tube and multiple doped wafers placed on a crystal boat. There is a buffer path between the crystal boat and the furnace tube opening. The temperature in the furnace tube is a first preset temperature, and the ambient temperature of the crystal boat is a second preset temperature.

[0013] Step 2: Open the furnace tube opening to allow the temperature between the furnace tube opening and the crystal boat to decrease in a gradient.

[0014] Step 3: Move the wafer boat into the furnace tube, then close the furnace tube opening and push the wafer into the furnace tube for a trapping process;

[0015] Step 4: Open the furnace tube opening so that the temperature between the furnace tube opening and the crystal boat decreases in a gradient.

[0016] Step 5: Move the crystal boat until it leaves the furnace tube.

[0017] Preferably, the first preset temperature in step one is 700 to 850 degrees Celsius.

[0018] Preferably, the second preset temperature in step one is 23 to 26 degrees Celsius.

[0019] Preferably, the crystal boat in step one is located below the furnace tube opening.

[0020] Preferably, the method for making the temperature between the furnace tube opening and the crystal boat decrease in a gradient in step two includes: moving the crystal boat so that the bottom of the crystal boat moves from the initial position to a first set position at a distance from the furnace tube opening, at which time the top of the crystal boat located at the first set position is close to or located at the furnace tube opening; stopping the crystal boat, and then opening the furnace tube opening so that the temperature between the furnace tube opening and the crystal boat decreases in a gradient.

[0021] Preferably, the stopping time of the crystal boat in step two is 10 to 30 minutes.

[0022] Preferably, in step three, the wafer boat is moved to a third position where it enters the furnace tube, and then the furnace tube opening is closed, and the wafer is pushed into the furnace tube at a temperature of 800 to 1200 degrees Celsius.

[0023] Preferably, the method of opening the furnace tube opening in step four to make the temperature between the furnace tube opening and the crystal boat decrease in a gradient includes: opening the furnace tube opening to make the temperature between the furnace tube opening and the initial position decrease in a gradient; moving the bottom of the crystal boat to a second set position and stopping the crystal boat, wherein the second set position is a position where the bottom of the crystal boat is close to the furnace tube opening and located outside the furnace tube opening, or a position located at the furnace tube opening.

[0024] Preferably, the stopping time of the crystal boat in step four is 10 to 30 minutes.

[0025] Preferably, in step five, the crystal boat at the second setting position is moved to the initial position.

[0026] As described above, the push-well method for improving wafer surface flatness of the present invention has the following beneficial effects:

[0027] This invention creates a certain thermal radiation buffer zone at the furnace tube opening during the process of raising and lowering the wafer boat in the furnace tube, thereby reducing the thermal stress generated during the wafer's entry and exit from the furnace tube, improving the flatness of the wafer's periphery, and enhancing the uniformity of photolithography alignment. Attached Figure Description

[0028] Figure 1 The diagram shows the first to third installation positions of the present invention.

[0029] Figure 2 The diagram shown is a schematic representation of the process flow of this invention. Detailed Implementation

[0030] 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.

[0031] Please see Figure 2 This invention provides a push-well method for improving wafer surface flatness, comprising:

[0032] Step 1: Provide furnace tube 101 and multiple doped wafers 104 mounted on a crystal boat 103. A buffer path exists between the crystal boat 103 and the furnace tube opening 102. The temperature in the furnace tube 101 is a first preset temperature, and the ambient temperature of the crystal boat 103 is a second preset temperature, i.e., room temperature. Normally, the length of the crystal boat is close to the length of the furnace tube. The bottom of the crystal boat 103 is located at the initial position (physical position cannot be set) HP. It takes about 20 minutes to load the wafers 104 onto the crystal boat 103. The stopping position of the bottom of the crystal boat 103 as it enters the furnace tube is the third position (physical position cannot be set) PP. A buffer path exists between the initial position HP and the fourth position PP.

[0033] In an embodiment of the present invention, the first preset temperature in step one is 700 to 850 degrees Celsius, preferably 800 degrees Celsius.

[0034] In an embodiment of the present invention, the second preset temperature in step one is 23 to 26 degrees Celsius.

[0035] In an embodiment of the present invention, in step one, the crystal boat 103 is located below the furnace tube opening 102.

[0036] Step 2: Open the furnace tube opening 102 so that the temperature between the furnace tube opening 102 and the crystal boat 103 decreases in a gradient, that is, a certain heat radiation buffer zone is formed in the furnace tube opening 102.

[0037] Please see Figure 1 During the movement of the crystal boat 103, parameters such as the movement position and movement speed can be set in advance. For example, the height can be set from bottom to top, with the first setting position P1 and the second setting position P2 located between the initial position HP and the third position PP.

[0038] In an embodiment of the present invention, the method for making the temperature between the furnace tube opening 102 and the crystal boat 103 decrease in a gradient in step two includes: moving the crystal boat 103 so that the bottom of the crystal boat 103 moves from the initial position HP to a first setting position P1 at a distance from the furnace tube opening 102, at which time the top of the crystal boat 103 at the first setting position P1 is close to or located at the furnace tube opening 102; stopping the crystal boat 103, and then opening the furnace tube opening 102 so that the temperature between the furnace tube opening 102 and the crystal boat 103 decreases in a gradient.

[0039] For example, the time it takes for the crystal boat 103 to move from the initial position HP to the first set position P1 is 1 minute, and the speed at which the crystal boat 103 moves is 50 to 100 mm / min.

[0040] In an embodiment of the present invention, the stopping time of the crystal boat 103 in step two is 10 to 30 minutes, preferably 10 minutes.

[0041] Step 3: Move the crystal boat 103 into the furnace tube 101, then close the furnace tube opening 102, and push the wafer 104 into the furnace tube 101 for a trapping process.

[0042] In an embodiment of the present invention, in step three, the bottom of the crystal boat 103 is moved to the third position PP in the furnace tube 101, and then the furnace tube opening 102 is closed, and the wafer 104 is pushed into the furnace tube 101 at a temperature of 800 to 1200 degrees Celsius.

[0043] For example, the time it takes for the crystal boat 103 to move from the first setting position P1 to the third position PP is 30 minutes, the speed of the crystal boat 103 is 100mm / min, and then a furnace tube port 102 closing signal is sent for one minute.

[0044] Step 4: Open the furnace tube opening 102 so that the temperature between the furnace tube opening 102 and the crystal boat 103 decreases in a gradient, that is, a certain heat radiation buffer zone is formed in the furnace tube opening 102.

[0045] In an embodiment of the present invention, the method of opening the furnace tube opening 102 in step four to make the temperature between the furnace tube opening 102 and the crystal boat 103 decrease in a gradient includes: opening the furnace tube opening 102 to make the temperature between the furnace tube opening 102 and the initial position HP decrease in a gradient; moving the bottom of the crystal boat 103 to the second setting position P2, stopping the crystal boat 103, wherein the second setting position P2 is a position where the bottom of the crystal boat 103 is close to the furnace tube opening 102 and located outside the furnace tube opening 102, or a position located at the furnace tube opening 102.

[0046] In an embodiment of the present invention, the stopping time of the crystal boat 103 in step four is 10 to 30 minutes, preferably 10 minutes.

[0047] For example, a furnace tube opening signal 102 is sent for one minute, and then the time for the crystal boat 103 to move from the third position PP to the second setting position P2 is 30 minutes, and the speed of the crystal boat 103 is 50 mm / min.

[0048] Step 5: Move the crystal boat 103 until it leaves the furnace tube 101.

[0049] In an embodiment of the present invention, in step five, the crystal boat 103 at the second setting position is moved to the initial position HP.

[0050] For example, the time taken for the crystal boat 103 to move from the second setting position P2 to the initial position HP is 30 minutes, the speed of the crystal boat 103 is 100 mm / min, and then the wafer 104 on the crystal boat 103 is unloaded.

[0051] 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.

[0052] In summary, this invention creates a thermal radiation buffer zone at the furnace tube opening during the raising and lowering of the wafer boat, thereby reducing the thermal stress generated during the wafer's entry and exit from the furnace tube, improving the flatness of the wafer periphery, and enhancing the uniformity of photolithography alignment. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0053] 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 push-well method for improving wafer surface flatness, characterized in that, At least including: Step 1: Provide a furnace tube and multiple doped wafers placed on a crystal boat. There is a buffer path between the crystal boat and the furnace tube opening. The temperature in the furnace tube is a first preset temperature, and the ambient temperature of the crystal boat is a second preset temperature. Step 2: Open the furnace tube inlet, causing the temperature between the furnace tube inlet and the crystal boat to decrease gradually. The method for causing this temperature gradient in Step 2 includes: moving the crystal boat so that its bottom moves from an initial position to a first set position away from the furnace tube inlet, at which point the top of the crystal boat at the first set position is close to or located near the furnace tube inlet; stopping the crystal boat, and then opening the furnace tube inlet again, causing the temperature between the furnace tube inlet and the crystal boat to decrease gradually; the stopping time for the crystal boat is 10 to 30 minutes. Step 3: Move the wafer boat into the furnace tube, then close the furnace tube opening and push the wafer into the furnace tube for a trapping process; Step 4: Open the furnace tube opening to allow the temperature between the furnace tube opening and the crystal boat to decrease gradually. The method for opening the furnace tube opening to allow the temperature between the furnace tube opening and the crystal boat to decrease gradually in step 4 includes: opening the furnace tube opening to allow the temperature between the furnace tube opening and the initial position to decrease gradually; moving the bottom of the crystal boat to a second set position and stopping the crystal boat, wherein the second set position is a position where the bottom of the crystal boat is close to and outside the furnace tube opening, or a position located at the furnace tube opening; the stopping time of the crystal boat is 10 to 30 minutes. Step 5: Move the crystal boat until it leaves the furnace tube.

2. The push-well method for improving wafer surface flatness according to claim 1, characterized in that: The first preset temperature in step one is 700 to 850 degrees Celsius.

3. The push-well method for improving wafer surface flatness according to claim 1, characterized in that: The second preset temperature in step one is 23 to 26 degrees Celsius.

4. The push-well method for improving wafer surface flatness according to claim 1, characterized in that: The crystal boat mentioned in step one is located below the furnace tube opening.

5. The push-well method for improving wafer surface flatness according to claim 1, characterized in that: In step three, the crystal boat is moved to the third position where it enters the furnace tube, and then the furnace tube opening is closed. The wafer is then pushed into the furnace tube at a temperature of 800 to 1200 degrees Celsius.

6. The push-well method for improving wafer surface flatness according to claim 5, characterized in that: In step five, the crystal boat at the second setting position is moved to the initial position.

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