Thin wafer transport method

Abstract

The present invention discloses a thin wafer transport method. The Bernoulli manipulator uses different gas flow rates at different transport stages for thin wafers of different thicknesses, thereby solving the problem of wafer chipping during transport. Specifically, in the process of removing the wafer from the wafer cassette, the Bernoulli manipulator uses a small gas flow rate, which reduces the suction force on the wafer, weakens the warpage deformation of the wafer, and reduces the risk of cracking or chipping during the process of removing the wafer from the wafer cassette. In the process of transporting the wafer to a processing chamber after removing the wafer from the wafer cassette, the Bernoulli manipulator uses a large gas flow rate, which increases the suction force on the wafer, stably adsorbing the wafer to the Bernoulli manipulator during transport, and prevents the wafer from slipping.

Description

[Technical field]

[0001] TECHNICAL FIELD This application relates to the field of semiconductor manufacturing, and more particularly to thin wafer transport methods. [Background technology]

[0002] As chips become more complex and highly integrated, heat dissipation has become an important factor affecting the performance and lifespan of the chip. Thin wafers have excellent heat dissipation properties, but they are prone to chipping and cracking due to their large warpage.

[0003] At present, Bernoulli manipulators are generally used to transport wafers. According to the thickness of the wafer, a corresponding gas flow is provided to the Bernoulli manipulator, so that the Bernoulli manipulator can stably adsorb the wafer. However, in actual operation, the wafer is often chipped or broken during the process of removing it from the wafer cassette. Summary of the Invention

[0004] An object of the present application is to provide a thin wafer transport method capable of reducing the risk of chipping of the thin wafer during transport, particularly during the process of removing the thin wafer from a wafer cassette.

[0005] In order to achieve the above object, the present invention provides a thin wafer transport method that is applied to a Bernoulli manipulator for transporting a wafer between a wafer cassette and a processing chamber. The Bernoulli manipulator includes a gas path for supplying gas to the Bernoulli manipulator. The method includes the following steps: Identifying the thickness of wafers in a wafer cassette. Obtain gas flow parameters suitable for the thickness of the wafer. Each gas flow parameter includes two gas flow rates, a first gas flow rate and a second gas flow rate, where the first gas flow rate is smaller than the second gas flow rate, the first gas flow rate is a gas flow rate provided to the Bernoulli manipulator by the gas path in a process of removing the wafer from the wafer cassette, and the second gas flow rate is a gas flow rate provided to the Bernoulli manipulator by the gas path in a process of transferring the wafer to the processing chamber after being removed from the wafer cassette. A gas having a first gas flow rate suitable for the thickness of the wafer to be transported is supplied to the Bernoulli manipulator via a gas path, and the Bernoulli manipulator removes the wafer from the wafer cassette at the first gas flow rate. Thereafter, gas at a second gas flow rate that is suitable for the thickness of the wafer to be transported is supplied to the Bernoulli manipulator via the gas path, and the Bernoulli manipulator transports the wafer to the processing chamber at the second gas flow rate.

[0006] The present invention discloses a thin wafer transport method. The Bernoulli manipulator uses different gas flow rates at different transport stages for thin wafers of different thicknesses, thereby solving the problem of wafer chipping during transport. Specifically, in the process of removing the wafer from the wafer cassette, the Bernoulli manipulator uses a small gas flow rate, which reduces the suction force on the wafer, weakens the warpage deformation of the wafer, and reduces the risk of cracking or chipping during the process of removing the wafer from the wafer cassette. In the process of transporting the wafer to a processing chamber after removing the wafer from the wafer cassette, the Bernoulli manipulator uses a large gas flow rate, which increases the suction force on the wafer, stably adsorbing the wafer to the Bernoulli manipulator during transport, and prevents the wafer from slipping. [Brief description of the drawings]

[0007] [Figure 1] 1(a) and 1(b) are diagrams for explaining the cause of chipping that occurs in the process in which the Bernoulli manipulator transfers a wafer from a wafer cassette. [Diagram 2] FIG. 2 shows a flowchart of a thin wafer transport method according to an embodiment of the present invention. [Diagram 3] FIG. 3 shows a gas path configured by a Bernoulli manipulator according to one embodiment of the present invention. [Figure 4] FIG. 4 shows a gas path formed by a Bernoulli manipulator according to another embodiment of the present invention. [Diagram 5] FIG. 5 shows a gas path formed by a Bernoulli manipulator according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In order to explain in detail the technical contents, structural features, objectives and effects achieved by the present invention, the following detailed description will be given with reference to embodiments and drawings.

[0009] Thin wafers are usually 50-400 μm thick, and have low rigidity and are prone to bending. Experiments have shown that when using a Bernoulli manipulator to transport thin wafers, chipping problems frequently occur, especially in the process of transporting the wafer from the wafer cassette. Research has shown that the Bernoulli manipulator adopts a constant gas flow rate Q0 in the entire process of transporting the wafer from the wafer cassette to the processing chamber, and this gas flow rate Q0 ensures that the Bernoulli manipulator provides sufficient suction force to the wafer and ensures that the wafer is stably sucked into the Bernoulli manipulator. Preferably, the wafer is stably sucked into the Bernoulli manipulator without contact. However, as shown in FIG. 1(a), the edge of the wafer 10 is horizontally supported by the support member 21 of the wafer cassette 20. When the Bernoulli manipulator 30 sucks the wafer 10 from below at a gas flow rate Q0, the Bernoulli manipulator 30 applies a large downward suction force F1 to the wafer 10, and at the same time, the support member 21 of the wafer cassette 20 applies an upward support force F2 to the wafer 10. When two forces in opposite directions (the suction force and the support force) act, as shown in FIG 1(b), a thin wafer with low rigidity is significantly warped, causing chipping or cracking.

[0010] Based on the above findings, in the present invention, the Bernoulli manipulator adopts different gas flow rates for different stages of transporting the thin wafer. Specifically, in the process of removing the wafer from the wafer cassette, the Bernoulli manipulator adopts a smaller gas flow rate, thereby reducing the suction force on the wafer, weakening the warpage deformation of the wafer, and reducing the risk of cracking or chipping in the process of removing the wafer from the wafer cassette. After being removed from the wafer cassette, in the process of transporting the wafer from the wafer cassette to the processing chamber, the Bernoulli manipulator adopts a larger gas flow rate to increase the suction force on the wafer, so that the wafer is stably adsorbed to the Bernoulli manipulator during transport and prevents slipping.

[0011] FIG. 2 shows a flow chart of a wafer transfer method according to an embodiment of the present invention. The thin wafer transfer method is mainly used to transfer a thin wafer between a wafer cassette and a process chamber using a Bernoulli manipulator. The Bernoulli manipulator is provided with a gas path, and gas is supplied to the Bernoulli manipulator using this gas path. Specifically, the gas path adjusts the gas flow rate supplied to the Bernoulli manipulator according to the thickness of the thin wafer to be transferred and the transfer stage of the wafer. The gas path of the Bernoulli manipulator will be described in detail later.

[0012] The specific steps of the thin wafer transport method will be described in detail with reference to FIG.

[0013] First, the thickness of the wafers in the wafer cassette is identified. The wafer cassette is provided with an identification code, which contains information regarding the thickness of the thin wafers in the wafer cassette. The wafer thickness is identified by reading the identification code of the wafer cassette. In one embodiment, the identification code can be a bar code containing the wafer thickness information and is read by a code scanner or identification sensor to identify the thickness of the wafers in the wafer cassette. In another embodiment, the identification code is a label affixed to the wafer cassette, with the thickness of the wafers in the wafer cassette written on the label. An operator can identify the thickness of the wafers in the wafer cassette from the contents of the label.

[0014] Further, a plurality of gas flow parameters suitable for a plurality of thicknesses of the wafer are obtained. Each gas flow parameter includes a first gas flow rate and a second gas flow rate. The first gas flow rate is smaller than the second gas flow rate. The first gas flow rate is a gas flow rate provided by the gas path to the Bernoulli manipulator in a process of removing the wafer from the wafer cassette. The second gas flow rate is a gas flow rate provided by the gas path to the Bernoulli manipulator in a process of transferring the wafer to the process chamber after removing the wafer from the wafer cassette. Table 1 shows the gas flow parameters according to the wafer thickness. [Table 1] For example, when the wafer thickness is 15 μm, the corresponding gas flow parameters are 30 L / min for the first gas flow rate and 73 L / min for the second gas flow rate. When the wafer thickness is 200 μm, the corresponding gas flow parameters are 30 L / min for the first gas flow rate and 90 L / min for the second gas flow rate. The gas flow parameter table can be obtained according to experiments.

[0015] Next, the gas path supplies gas at a first gas flow rate that is compatible with the thickness of the wafer being transferred to the Bernoulli manipulator, and the Bernoulli manipulator removes the wafer from the wafer cassette at the first gas flow rate.

[0016] The gas path then supplies gas at a second gas flow rate that is compatible with the thickness of the wafer being transferred to the Bernoulli manipulator, which transfers the wafer to the processing chamber at the second gas flow rate.

[0017] In one embodiment, the gas flow parameters are pre-stored in the controller of the wafer processing device. After receiving the identified wafer thickness, the controller automatically obtains the gas flow parameters that match the identified wafer thickness, and sends instructions to the gas path of the Bernoulli manipulator according to the obtained gas flow parameters, so that the gas path can provide the Bernoulli manipulator with corresponding gas flow rates at different wafer transport stages.

[0018] In one embodiment, the process chamber is a backside cleaning chamber. Before the Bernoulli manipulator transfers the wafer to the backside cleaning chamber, the Bernoulli manipulator inverts the wafer so that the front side of the wafer faces down and the back side of the wafer faces up. Before the Bernoulli manipulator inverts the wafer, the gas flow rate supplied to the Bernoulli manipulator by the gas path is increased from a first gas flow rate that matches the thickness of the wafer to be transferred to a second gas flow rate. When the Bernoulli manipulator attracts the wafer with the second gas flow rate, the suction force is increased, and the wafer can be prevented from falling off the Bernoulli manipulator during and after the inversion, thereby generating debris.

[0019] Referring to FIG. 3, a gas path 100 configured by a Bernoulli manipulator according to an embodiment of the present invention is disclosed. The gas path 100 includes a main gas path 101. One end of the main gas path 101 is connected to a gas source 40, and the other end of the main gas path 101 is connected to the Bernoulli manipulator 30. In the main gas path 101, a main flow rate adjustment valve 1011, a main switching valve 1012, and a main mass flow controller (MFC) 1013 are sequentially arranged along the gas flow direction. The main mass flow controller 1013 is used to adjust the gas flow rate in the main gas path 101. In this embodiment, the main mass flow controller 1013 adjusts the gas flow rate in the main gas path 101 according to the thickness of the wafer and the transport stage of the wafer, so that the Bernoulli manipulator 30 can obtain the corresponding gas flow rate.

[0020] In actual operation, gas flow parameters corresponding to the thickness of the wafer are obtained. For example, when the thickness of the wafer stored in the wafer cassette is 180 μm, the gas flow parameters corresponding to the wafer thickness can be obtained from Table 1, and the first gas flow rate is 30 L / min and the second gas flow rate is 82 L / min. Then, while the wafer is taken out of the wafer cassette, the main mass flow controller 1013 adjusts the gas flow rate in the main gas path 101 according to the obtained gas flow parameters so that the main gas path 101 supplies gas at a gas flow rate of 30 L / min to the Bernoulli manipulator. After the wafer is taken out of the wafer cassette, in the process of transferring the wafer to the processing chamber, the main mass flow controller 1013 adjusts the gas flow rate in the main gas path 101 so that the main gas path 101 supplies gas at a gas flow rate of 82 L / min to the Bernoulli manipulator. This not only prevents the wafer from being chipped or cracked due to excessive suction force when the wafer is removed from the wafer cassette, but also ensures that the Bernoulli manipulator has sufficient suction force when transporting the wafer to the processing chamber, allowing the wafer to be stably transported to the processing chamber.

[0021] Referring to FIG. 4, a gas path 200 configured by a Bernoulli manipulator according to another embodiment of the present invention is disclosed. The gas path 200 includes not only the main gas path 101 but also a branch gas path 201. One end of the branch gas path 201 is connected to the downstream side of the main switching valve 1012, and the other end is connected to the upstream side of the main mass flow controller 1013. The branch gas path 201 is provided with a branch flow rate control valve 2011 for adjusting the gas flow rate in the branch gas path 201. The branch flow rate control valve 2011 is used to adjust the gas flow rate in the branch gas path 201. The main switching valve 1012 is a three-way valve, and the gas path supplied from the gas source 40 is switched between the main gas path 101 and the branch gas path 201 via the main switching valve 1012.

[0022] In actual operation, in the process of removing a wafer from a wafer cassette, a gas flow rate suitable for the thickness of the wafer being transported is supplied to the Bernoulli manipulator 30 by the branch gas path 201, and the gas flow rate in the branch gas path 201 is adjusted by a branch flow rate adjustment valve 2011. In the process of transporting a wafer from the wafer cassette to a processing chamber, a second gas flow rate suitable for the thickness of the wafer being transported is supplied to the Bernoulli manipulator by the main gas path 101, and the gas flow rate in the main gas path 101 is controlled by a main mass flow controller 1013.

[0023] Experimental calculations show that the first gas flow rates suitable for thin wafers of different thicknesses can be set to the same gas flow rate. As shown in Table 1, the gas flow rate in the branch gas path 201 does not need to be adjusted according to the change in thickness of the wafer being transported. Therefore, the branch flow rate control valve 2011 provided in the branch gas path 201 can use a manual flow rate control valve, thereby reducing costs.

[0024] Referring to FIG. 5, a gas path 300 configured by a Bernoulli manipulator according to another embodiment of the present invention is disclosed. The gas path 300 includes a first gas path 301 and a second gas path 302. The first gas path 301 has one end connected to a gas source 41 and the other end connected to the Bernoulli manipulator 30. In the first gas path 301, a first flow rate adjustment valve 3011, a first switching valve 3012, and a first mass flow controller 3013 are sequentially arranged along the gas flow direction. The first mass flow controller 3013 is used to adjust the gas flow rate in the first gas path 301. The second gas path 302 has one end connected to a gas source 42 and the other end connected to the Bernoulli manipulator 30. In the second gas path 302, a second flow rate adjustment valve 3021, a second switching valve 3022, and a second mass flow controller 3023 are sequentially arranged along the gas flow direction. A second mass flow controller 3023 is used to adjust the gas flow rate in the second gas path 302. In one embodiment, gas source 41 and gas source 42 may be the same gas source or may be two relatively independent gas sources.

[0025] In actual operation, in the process of removing a wafer from a wafer cassette, the first gas path 301 supplies gas to the Bernoulli manipulator 30 at a first gas flow rate that is suitable for the thickness of the wafer being transported, and in the process of transporting the wafer from the wafer cassette to a processing chamber, the second gas path 302 supplies gas to the Bernoulli manipulator at a second gas flow rate that is suitable for the thickness of the wafer being transported.

[0026] It should be noted that in the three gas paths 100, 200, and 300 of the above-mentioned three Bernoulli manipulator configurations, the mass flow controllers are disposed below the various valves (switching valves, flow rate control valves) in the gas paths, i.e., near the Bernoulli manipulators. This makes it possible to avoid a peak value of pressure or flow rate that occurs at the moment the gas paths are connected, which would cause the suction force of the Bernoulli manipulator to exceed a threshold value and chip or crack the wafer.

[0027] In summary, the present invention discloses the relevant technology in detail through the above-mentioned embodiments and related drawings, and those skilled in the art can implement it accordingly. The above-mentioned embodiments do not limit the present application, but are only used to explain the present application, and the scope of the present application should be defined by the claims of the present application. The change in the number of elements described in this specification or the replacement of equivalent elements still belongs to the scope of the present application.

Claims

1. A thin wafer transport method for use with a Bernoulli manipulator that transports a thin wafer between a wafer cassette and a processing chamber, the Bernoulli manipulator having a gas path for supplying gas to the Bernoulli manipulator, comprising: identifying a thickness of the wafers in a wafer cassette; obtaining gas flow parameters compatible with a thickness of the wafer, the gas flow parameters including a first gas flow rate and a second gas flow rate greater than the first gas flow rate; supplying gas at the first gas flow rate suitable for a thickness of the wafer to be transported to the Bernoulli manipulator through the gas path, and the Bernoulli manipulator removing the wafer from the wafer cassette at the first gas flow rate; Thereafter, gas having the second gas flow rate suitable for the thickness of the wafer being transported is supplied to the Bernoulli manipulator through the gas path, and the Bernoulli manipulator transports the wafer to the processing chamber at the second gas flow rate.

2. 2. The thin wafer transport method according to claim 1, A thin wafer conveying method, characterized in that the thickness of the wafer is 50 μm to 400 μm.

3. 2. The thin wafer transport method according to claim 1, the gas path formed by the Bernoulli manipulator includes a main gas path having one end connected to a gas source and the other end connected to the Bernoulli manipulator, the main gas path including a main flow rate regulating valve, a main switching valve, and a main mass flow controller sequentially arranged along a gas flow direction, and the method for transporting a thin wafer includes a step of adjusting a gas flow rate in the main gas path via the main mass flow controller.

4. 4. The thin wafer transport method according to claim 3, In a process of removing the wafer from the wafer cassette, the main mass flow controller adjusts a gas flow rate in the main gas path so that the main gas path supplies gas at the first gas flow rate suitable for a thickness of the wafer to be transported to the Bernoulli manipulator; a main mass flow controller for adjusting a gas flow rate in the main gas path so that the main gas path supplies gas at the second gas flow rate suitable for a thickness of the wafer being transported to the Bernoulli manipulator during a process of transporting the wafer to the processing chamber after the wafer is removed from the wafer cassette.

5. 4. The thin wafer transport method according to claim 3, the gas path formed by the Bernoulli manipulator further includes a branch gas path having one end connected to the downstream side of the main switching valve and the other end connected to the upstream side of the main mass flow controller, and the branch gas path is provided with a branch flow rate control valve that adjusts a gas flow rate in the branch gas path.

6. 6. The thin wafer transport method according to claim 5, the branch gas path is used to supply gas at the first gas flow rate that is suitable for a thickness of the wafer to be transported to the Bernoulli manipulator in a process of removing the wafer from the wafer cassette; a main gas path that is used to supply gas at the second gas flow rate that is suitable for the thickness of the wafer being transported to the Bernoulli manipulator during the process of transporting the wafer removed from the wafer cassette to the processing chamber.

7. 2. The thin wafer transport method according to claim 1, the gas path configured by the Bernoulli manipulator includes a first gas path and a second gas path; the first gas path has one end connected to a gas source and the other end connected to the Bernoulli manipulator, the first gas path is provided with a first flow rate control valve, a first switching valve, and a first mass flow controller in sequence along a gas flow direction, the first mass flow controller being used to adjust the gas flow rate in the first gas path; the second gas path has one end connected to a gas source and the other end connected to the Bernoulli manipulator, the second gas path has a second flow rate adjustment valve, a second switching valve, and a second mass flow controller sequentially installed along a gas flow direction, the second mass flow controller being used to adjust the gas flow rate in the second gas path.

8. The thin wafer transport method according to claim 7, further comprising the steps of: the first gas path is used to supply gas to the Bernoulli manipulator at the first gas flow rate that is adapted to a thickness of the wafer being transported in a process of removing the wafer from the wafer cassette; a second gas path that is used to supply gas at the second gas flow rate that is suitable for the thickness of the wafer being transported to the Bernoulli manipulator during the process of transporting the wafer removed from the wafer cassette to the processing chamber.

9. 2. The thin wafer transport method according to claim 1, A thin wafer transport method, characterized in that an identification code including wafer thickness information is provided on the wafer cassette, and the thickness of the wafer in the wafer cassette is identified by reading the identification code of the wafer cassette.

10. 2. The thin wafer transport method according to claim 1, a gas flow rate supplied to the Bernoulli manipulator by the gas path before the Bernoulli manipulator inverts the wafer so that the front surface of the wafer faces downward and the back surface of the wafer faces upward, the gas flow rate being increased from the first gas flow rate, which is suitable for the thickness of the wafer being transported, to the second gas flow rate before the Bernoulli manipulator inverts the wafer.

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