Photoacoustic film thickness measuring device and wafer angle alignment method

Abstract

The application discloses a photoacoustic film thickness measuring device and a wafer angle alignment method. The photoacoustic film thickness measuring device comprises a wafer carrier, a moving platform, a probe light emitter, a probe light detector and a controller. The wafer carrier is used for carrying a wafer, and the wafer comprises a notch. The moving platform is connected with the wafer carrier. Probe light emitted by the probe light emitter is reflected by the edge surface of the wafer or the wafer carrier and then enters the probe light detector. The controller is in communication connection with the moving platform and the probe light detector respectively, is used for controlling the moving platform to drive the wafer carrier and the wafer thereon to move together, acquiring rotation information of the moving platform and a detection signal generated by the probe light detector according to the received probe light, and determining a deviation angle of the notch deviating from a preset notch according to the acquired detection signal and rotation information, and eliminating the deviation angle between the notch and the preset notch according to the deviation angle. The application can reduce the cost of wafer angle alignment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer angle alignment, and in particular to a photoacoustic film thickness measurement device and a wafer angle alignment method. BACKGROUND

[0002] Wafer angle alignment is a necessary function of semiconductor production and measurement equipment, which ensures the consistency of processing or measurement points of different wafers, thereby ensuring the stability of the process.

[0003] The existing wafer angle alignment scheme is mainly laser pre-alignment, in which a laser irradiates the edge of a wafer, and then by rotating the wafer and monitoring the laser signal, the gap of the wafer can be found. However, this scheme requires the addition of a gap finder and a laser in the device structure, which not only increases the cost, but also increases the station and device area. SUMMARY

[0004] The present application provides a photoacoustic film thickness measurement device and a wafer angle alignment method to solve the problem of high cost of the existing wafer angle alignment scheme.

[0005] In a first aspect, an embodiment of the present application provides a photoacoustic film thickness measurement device, comprising a wafer stage, a motion platform, a probe light emitter, a probe light detector and a controller.

[0006] The wafer stage is used to carry a wafer, and the wafer includes a gap; the motion platform is connected to the wafer stage; the controller is in communication connection with the motion platform, and is used to control the motion platform to drive the wafer stage and the wafer on the wafer stage to move together, and to acquire rotation information of the motion platform;

[0007] During the rotation of the motion platform, probe light emitted by the probe light emitter can be incident to the edge surface of the wafer or pass through the gap to be incident to the wafer stage, and after being reflected by the edge surface of the wafer or the wafer stage, the probe light is incident to the probe light detector, and the probe light detector is used to generate a detection signal according to the received probe light;

[0008] The controller is also in communication connection with the probe light detector, and is used to determine a deviation angle of the gap deviating from a preset gap according to the acquired detection signal and the rotation information, and to eliminate the deviation angle between the gap and the preset gap according to the deviation angle.

[0009] Optionally, the controller is configured to determine a preset distance according to a size of the wafer and a position of a light spot formed by the probe light on the wafer, and control the motion platform to move the wafer carrier and the wafer on the wafer carrier together according to the preset distance and the position of the preset gap, so that the probe light emitted by the probe light emitter can be incident on the edge surface of the wafer.

[0010] Optionally, the controller is configured to reconstruct a coordinate system of the motion platform according to the deviation angle, so that the position of the gap is the same as the position of the preset gap.

[0011] Optionally, the wafer moving device is further included.

[0012] The controller is further in communication connection with the wafer moving device, and is configured to control the wafer moving device to move the wafer according to the deviation angle, so as to change the position of the wafer on the wafer carrier, and further make the position of the gap the same as the position of the preset gap.

[0013] Optionally, the first mirror and / or the second mirror are further included.

[0014] The first mirror is located in an optical path between the probe light emitter and the wafer, and is configured to change the optical path of the probe light emitted by the probe light emitter, so that the probe light reflected by the first mirror is incident on the edge surface of the wafer.

[0015] The second mirror is located in an optical path between the wafer and the probe light detector, and is configured to change the optical path of the probe light reflected by the edge surface of the wafer, so that the probe light reflected by the second mirror is incident on the probe light detector.

[0016] Optionally, the first lens and / or the second lens are further included.

[0017] The first lens is located in an optical path between the probe light emitter and the wafer, and is configured to focus the probe light emitted by the probe light emitter.

[0018] The second lens is located in an optical path between the wafer and the probe light detector, and is configured to diffuse the probe light reflected by the wafer.

[0019] In a second aspect, an embodiment of the present application provides a wafer angle alignment method based on the photoacoustic film thickness measuring device of the first aspect, comprising:

[0020] controlling the motion platform to move the wafer carrier and the wafer on the wafer carrier together, and acquiring rotation information of the motion platform and a detection signal generated by the probe light detector according to the received probe light.

[0021] determine a deviation angle of the gap from a preset gap according to the obtained detection signal and the rotation information;

[0022] eliminate the deviation angle between the gap and the preset gap according to the deviation angle.

[0023] Optionally, the control of the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together comprises:

[0024] determine a preset distance according to the size of the wafer and the position of the light spot formed by the probe light on the wafer;

[0025] control the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together according to the preset distance and the position of the preset gap, so that the probe light emitted by the probe light emitter can be incident to the edge surface of the wafer.

[0026] Optionally, the elimination of the deviation angle between the gap and the preset gap according to the deviation angle comprises:

[0027] reconstruct a coordinate system of the motion platform according to the deviation angle, so that the position of the gap is the same as the position of the preset gap.

[0028] Optionally, the photoacoustic film thickness measuring device further comprises a wafer moving device;

[0029] eliminate the deviation angle between the gap and the preset gap according to the deviation angle, comprising:

[0030] for controlling the wafer moving device to move the wafer according to the deviation angle, so as to change the position of the wafer on the wafer carrier, and thus make the position of the gap the same as the position of the preset gap.

[0031] The technical scheme of the embodiment of the application applies the wafer carrier, the motion platform, the probe light emitter, the probe light detector and the controller in the photoacoustic film thickness measuring device for measuring the thickness of the wafer to the wafer angle alignment, and thus realizes the wafer angle alignment, so that it is not necessary to separately set a device for wafer angle alignment to realize the wafer angle alignment. This scheme developed by using the optical path and the motion structure naturally possessed by the device to realize the wafer angle alignment does not need to additionally add a vision module for wafer angle alignment, and not only reduces the cost of the device, but also reduces the area of the device and the area of the station occupied by the device, and improves the integration degree of the device.

[0032] It is to be understood that the description of the background of the application is not an acknowledgement or admission that any of the information provided in the description of the background of the application is prior art to the application. The information in the description of the background of the application may contain ideas, concepts and / or discoveries not yet known to be prior art to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings should also belong to the protection scope of the present application.

[0034] Figure 1 A structural schematic diagram of a photoacoustic film thickness measurement device provided by an embodiment of the present application.

[0035] Figure 2 A schematic diagram of probe light incident to a preset gap provided by an embodiment of the present application.

[0036] Figure 3 A schematic diagram of probe light incident to a wafer stage through a wafer gap provided by an embodiment of the present application.

[0037] Figure 4 A schematic diagram of a detection signal change in a process of a motion platform driving a wafer to rotate one round provided by an embodiment of the present application.

[0038] Figure 5 Another structural schematic diagram of a photoacoustic film thickness measurement device provided by an embodiment of the present application.

[0039] Figure 6 Still another structural schematic diagram of a photoacoustic film thickness measurement device provided by an embodiment of the present application.

[0040] Figure 7 A flowchart of a wafer angle alignment method based on a photoacoustic film thickness measurement device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the technical personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should belong to the protection scope of the present application.

[0042] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present application and the above-described drawings are intended to distinguish similar objects and are not necessarily intended to describe a particular sequential or chronological order. It should be understood that the data thus used can be interchanged, where appropriate, so that the embodiments of the application described herein can be carried out in other than the order shown or described herein. Furthermore, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or apparatus that includes a list of steps or units need not be limited to those steps or units that are clearly listed, but can include other steps or units that are not clearly listed or inherent to such processes, methods, products, or apparatuses. The terms "up", "down", "left", "right", and the like indicate the orientation or positional relationship shown in the drawings, and are used only to illustrate the relative positional relationship between the components or parts, and do not particularly limit the specific installation orientation of the components or parts.

[0043] Figure 1 A structural schematic diagram of a photoacoustic film thickness measuring device provided for an embodiment of the present application, Figure 2 A schematic diagram of probe light incident on a preset gap, Figure 3 A schematic diagram of probe light incident on a wafer stage through a wafer gap, Figure 1 、 Figure 2 and Figure 3 The photoacoustic film thickness measuring device in the embodiment of the present application includes a wafer stage 10, a motion platform 20, a probe light emitter 30, a probe light detector 40, and a controller 50. The wafer stage 10 is used to carry a wafer 200, and the wafer 200 includes a gap 201. The motion platform 20 is connected to the wafer stage 10. The controller 50 is in communication connection with the motion platform 20, and is used to control the motion platform 20 to drive the wafer stage 10 and the wafer 200 on the wafer stage 10 to move together, and to acquire rotation information of the motion platform 20. In the process of rotation of the motion platform 20, probe light emitted by the probe light emitter 30 can be incident on an edge surface of the wafer 200 or incident on the wafer stage 10 through the gap 201, and after being reflected by the edge surface of the wafer 200 or the wafer stage 10, the probe light is incident on the probe light detector 40. The probe light detector 40 is used to generate a detection signal according to the received probe light. The controller 50 is also in communication connection with the probe light detector 40, and is used to determine a deviation angle of the gap 201 deviating from a preset gap 201' according to the acquired detection signal and the rotation information, and to eliminate the deviation angle between the gap 201 and the preset gap 201' according to the deviation angle.

[0044] For example, in a photoacoustic film thickness measurement device, the pump-probe laser system used for measurement naturally has a probe light emitter 30 and a probe light detector 40. Referring to Figure 1 The probe light emitter 30 in the embodiment of the present application includes a light source 31 and a probe light shutter 32. It can be understood that the pump light and the probe light in the embodiment of the present application can be two homologous pulsed lasers, and the laser emitted by the light source 31 will be divided into two lasers with different energies after passing through a beam splitter (not shown in the figure), which are the pump light and the probe light, respectively. Among them, the probe light with lower energy will pass through the opened probe light shutter 32 and be incident on the wafer. It can be understood that the energy of the probe light is lower than 10% of the energy of the unsplit laser, and even if it continuously irradiates the wafer 200, it will not cause damage to it. The pump light with higher energy cannot irradiate the wafer because the pump light shutter is closed.

[0045] For example, the probe light detector 40 is a position sensor that can detect changes in the probe light signal. It can be understood that if the reflectivity of the object on which the probe light emitted by the probe light emitter 30 is incident is different, the position of the probe light reflected by the object to the probe light detector 40 will also be different, and the detection signal generated by the probe light detector 40 according to the received probe light will also be different. It should be noted that the above detection signal can be a current signal or a voltage signal.

[0046] For example, referring to Figure 1 The wafer stage 10 includes a wafer taking and placing groove 11. Before angle alignment of the wafer 200, the wafer moving device (not shown in the figure, which can be a mechanical hand capable of grabbing and moving the wafer 200) will be controlled to place the grabbed wafer 200 on the wafer stage 10 after aligning the wafer taking and placing groove 11. The wafer 200 includes a notch 201, which is located at the edge of the wafer. The edges of the wafer 200 other than the notch 201 will cover the corresponding part of the wafer stage 10, and the notch 201 will not cover the corresponding part of the wafer stage 10. In this way, it can be understood that if the probe light is irradiated on the edges of the wafer 200 other than the notch 201, it will be directly reflected to the probe light detector 40 through the wafer 200, and if the probe light is irradiated on the notch 201 of the wafer 200, it will be directly irradiated on the wafer stage 10 through the notch 201, and then reflected to the probe light detector 40 through the wafer stage 10. Since the reflectivity of the wafer 200 is different from that of the wafer stage 10, the detection signal generated by the probe light detector 40 according to the probe light reflected by the wafer 200 is different from the detection signal generated by the probe light detector 40 according to the probe light reflected by the wafer stage 10.

[0047] The motion platform 20 in this embodiment of the present invention has four-axis motion capability. The controller 50 can control the motion platform 20 to move in the plane of the surface on which the wafer stage 10 is placed, along its thickness, and around its center of rotation. The wafer stage 10 and wafer 200 are mounted on the motion platform 20. When the motion platform 20 moves under the control of the controller 50, the wafer stage 10 and wafer 200 also move with the motion platform 20.

[0048] The photoacoustic film thickness measuring device in the embodiment of the present invention is fixed, and the focus of the probe light emitted by the probe light emitter 30 on the plane where the wafer 200 is located is also fixed. Figure 1 It can be seen that before the controller 50 controls the movement of the motion platform 20, the probe light emitted by the probe light emitter 30 is not at the edge of the wafer 200. At this time, no matter how the wafer 200 rotates, the probe light received by the probe light detector 40 is reflected by the wafer 200, and the detection signal generated by it will not have obvious changes during the process of the wafer 200 rotating one circle. Therefore, it is impossible to determine the rotation angle of the motion platform 20 corresponding to the notch 201, and it is even more impossible to determine the deviation angle of the notch 201 from the preset notch 201' based on the rotation angle of the motion platform 20 corresponding to the notch 201 and the rotation angle of the motion platform 20 corresponding to the preset notch, and thus it is impossible to achieve wafer angle alignment.

[0049] The notch 201 of the wafer 200 is located at the edge of the wafer 200. In order to ensure that the wafer angle can be accurately aligned, there is a situation in which the probe light passes through the notch 201 and is incident on the wafer carrier 10 during the process of the motion platform 20 driving the wafer 200 to rotate one circle, it is necessary to first control the motion platform 20 to move so that the probe light is focused on the edge of the wafer, and then control the motion platform 20 to drive the wafer 200 to rotate one circle. It should be noted that in the process of controlling the motion platform 20 to drive the wafer 200 to rotate one circle, the probe light emitted by the probe light emitter 30 will scan the edge of the wafer 200 for one circle. Finally, the deviation angle of the notch 201 from the preset notch 201' is determined based on the detection signal generated by the probe light detector 40 during the process of the motion platform 20 driving the wafer 200 to rotate one circle and the rotation information of the motion platform 20 driving the wafer 200 to rotate one circle. It should be noted that the rotation information of the motion platform 20 in the embodiment of the present invention includes the rotation angle of the motion platform 20.

[0050] The embodiment of the present invention takes the position of the preset notch 201' corresponding to the wafer placement slot of the wafer carrier 10 as an example. Figure 4 A schematic diagram of the change of detection signals during a wafer rotation driven by a motion platform provided by an embodiment of the present invention, with reference to Figure 4After controlling the motion platform 20 to move so that the probe light is focused on the preset notch 201' located at the edge of the wafer 200, the controller 50 will control the motion platform 20 to drive the wafer 200 to start rotating in a preset rotation direction. The surface flatness of the wafer 200 is good, and the reflectivity change is small. The floating range of the detection signal (such as the current signal) generated by the surface of the wafer 200 reflected to the probe light detector 40 is small. When the probe light rotates to be incident on the notch 201, the probe light will pass through the notch 201 and be incident on the wafer carrier 10. At this time, the detection signal generated by the surface of the wafer carrier 10 reflected to the probe light detector 40 will deviate significantly from the original value, such as Figure 4 As shown, after the motion platform 20 rotates by angle θ, the detection signal generated by the probe light detector 40 undergoes a sudden change. As the motion platform 20 continues to rotate the wafer 200, the detection signal generated by the probe light detector 40 returns to normal. The rotation angle of the motion platform 20 corresponding to the sudden change in the detection signal is the deviation angle of the notch 201 from the predetermined notch 201'.

[0051] It should be noted that the position of the preset notch 201 ′ refers to the position of the preset notch 201 ′ on the coordinate system of the motion platform 20 . The embodiment of the present invention does not limit the position of the preset notch 201 ′, and those skilled in the art can set it by themselves.

[0052] In order to ensure that the deviation angle of the notch 201 from the preset notch 201' does not affect the subsequent processing technology of the wafer, the controller 50 needs to be able to eliminate the deviation angle between the notch 201 and the preset notch 201' according to the deviation angle determined above, so that the position of the notch 201 on the coordinate system of the moving platform 20 is the same as the position of the preset notch 201' on the coordinate system of the moving platform 20.

[0053] Specifically, in a feasible implementation manner, the controller 50 is configured to reconstruct the coordinate system of the motion platform 20 according to the deviation angle, so that the position of the notch 201 is the same as the position of the preset notch 201 ′.

[0054] It should be noted that the relative position of the preset notch 201' in the coordinate system of the motion platform 20 remains unchanged. Changes in the coordinate system of the motion platform 20 will also change the position of the preset notch 201'. Simply ensuring that the position of the notch 201 in the reconstructed coordinate system of the motion platform 20 is the same as the position of the preset notch 201' in the original coordinate system of the motion platform 20 will ensure that the position of the preset notch 201' is the same as the position of notch 201. This method eliminates the deviation angle between the notch 201 and the preset notch 201' by simply reconstructing the coordinate system of the motion platform 20. This method is simple to operate and highly accurate.

[0055] Specifically, in another possible implementation, the photoacoustic film thickness measuring device in the embodiment of the present application further comprises a wafer moving device (not shown in the figure). The controller 50 is further connected in communication with the wafer moving device, and is configured to control the wafer moving device to move the wafer according to the deviation angle, so as to change the position of the wafer on the wafer stage 10, and further to make the position of the notch 201 the same as the position of the preset notch 201'.

[0056] Specifically, in another possible implementation, the photoacoustic film thickness measuring device in the embodiment of the present application further comprises a wafer moving device (not shown in the figure). The controller 50 is further connected in communication with the wafer moving device, and is configured to control the wafer moving device to move the wafer according to the deviation angle, so as to change the position of the wafer on the wafer stage 10, and further to make the position of the notch 201 the same as the position of the preset notch 201'.

[0057] The wafer angle alignment device in the embodiment of the present application is used for wafer angle alignment, and thus it is not necessary to additionally set a wafer angle alignment device including a notch finder and a laser, which is conducive to reducing the cost of wafer angle alignment.

[0058] In the above embodiment, the controller 50 is configured to determine the preset distance according to the size of the wafer 200 and the position of the light spot formed by the probe light on the wafer 200, and to control the motion platform 20 to drive the wafer stage 10 and the wafer 200 on the wafer stage 10 to move together according to the preset distance and the position of the preset notch, so that the probe light emitted by the probe light emitter 30 can be incident to the edge surface of the wafer 200.

[0059] The photoacoustic film thickness measuring device in the embodiment of the present application is applicable to wafers of various sizes, such as 6-inch, 8-inch, 12-inch, etc. It can be understood that the size of the wafer 200 is different, and the distance that the motion platform 20 needs to be controlled to move in order to focus the probe light on the edge of the wafer 200 is also different. Therefore, in order to ensure that the motion platform 20 can be controlled to move to the position where the probe light is focused on the preset gap 201' located on the edge of the wafer 200, it is necessary to first determine the preset distance according to the size of the wafer 200 and the position of the light spot formed by the probe light on the wafer 200, and then control the motion platform 20 to move to the position of the preset gap 201' according to the preset distance determined above so that the probe light is first focused on the preset gap 201' located on the edge of the wafer 200, and finally control the motion platform 20 to rotate the wafer 200 along the preset rotation direction. It should be noted that the above-mentioned preset distance refers to the distance between the light spot formed by the probe light on the wafer 200 and the edge of the wafer.

[0060] It can be understood that, based on the movement accuracy of the existing wafer moving device, it can be ensured that when wafers of different sizes are placed, the center of the wafer 200 and the rotation center of the motion platform 32 are almost coincident in the thickness direction of the wafer 200, and the position of the light spot formed by the probe light on the wafer 200 is unchanged relative to the center of the wafer 200. On this basis, as long as the wafer angle alignment of a wafer of a certain size is first implemented, the preset distance can be determined according to the size of the wafer 200 and the position of the light spot formed by the probe light on the wafer 200, and the motion platform 20 can be successfully controlled to move to the position where the probe light is focused on the preset gap 201' located on the edge of the wafer 200 according to the preset distance and the position of the preset gap 201', and then for wafers of the same size, it is not necessary to first determine the preset distance according to the size of the wafer 200 and the position of the light spot formed by the probe light on the wafer 200, but the motion platform 20 can be directly controlled to move to the position of the preset gap 201' according to the preset distance determined at the beginning so that the probe light is focused on the preset gap 201' located on the edge of the wafer 200. In this way, it is beneficial to realize the function of universal wafer angle alignment.

[0061] Figure 5 Another structure schematic diagram of the photoacoustic film thickness measuring device provided by the embodiment of the present application is provided, referring to Figure 5The photoacoustic film thickness measuring device in the embodiment of the present application further comprises a first mirror 60 and / or a second mirror 70. The first mirror 60 is located in the light path between the probe light emitter 30 and the wafer 200, and is used to change the light path of the probe light emitted by the probe light emitter 30, so that the probe light reflected by the first mirror 60 is incident to the edge surface of the wafer 200. The second mirror 70 is located in the light path between the wafer 200 and the probe light detector 40, and is used to change the light path of the probe light reflected by the edge surface of the wafer 200, so that the probe light reflected by the second mirror 70 is incident to the probe light detector 40.

[0062] Considering the application scenario of the photoacoustic film thickness measuring device in the embodiment of the present application, it can be understood that the upper side of the wafer 200 can not have installation space for the probe light emitter 30 and the probe light detector 40 due to the arrangement of many other devices, and therefore, in the embodiment shown in the figure, the probe light emitter 30 and the probe light detector 40 are arranged on the two sides of the wafer 200, and the probe light emitted by the probe light emitter 30 cannot be directly incident to the wafer 200. In order to ensure that the probe light emitted by the probe light emitter 30 can be incident to the edge surface of the wafer 200, a first mirror 60 capable of reflecting the probe light emitted by the probe light emitter 30 to the wafer 200 needs to be arranged in the light path between the probe light emitter 30 and the wafer 200. Similarly, in order to ensure that the probe light detector 40 can receive the probe light reflected by the edge surface of the wafer 200, a second mirror 70 capable of reflecting the probe light reflected by the edge surface of the wafer 200 to the probe light detector 40 needs to be arranged in the light path between the wafer 200 and the probe light detector 40. Figure 5 In the embodiment shown in the figure, the probe light emitter 30 and the probe light detector 40 are not arranged directly above the wafer 200, but are arranged on the two sides of the wafer 200, and the probe light emitted by the probe light emitter 30 cannot be directly incident to the wafer 200. In order to ensure that the probe light emitted by the probe light emitter 30 can be incident to the edge surface of the wafer 200, a first mirror 60 capable of reflecting the probe light emitted by the probe light emitter 30 to the wafer 200 needs to be arranged in the light path between the probe light emitter 30 and the wafer 200. Similarly, in order to ensure that the probe light detector 40 can receive the probe light reflected by the edge surface of the wafer 200, a second mirror 70 capable of reflecting the probe light reflected by the edge surface of the wafer 200 to the probe light detector 40 needs to be arranged in the light path between the wafer 200 and the probe light detector 40.

[0063] Figure 6 Another photoacoustic film thickness measuring device structure schematic diagram provided by the embodiment of the present application is shown in the figure. Figure 6 The photoacoustic film thickness measuring device in the embodiment of the present application further comprises a first lens 80 and / or a second lens 90. The first lens 80 is located in the light path between the probe light emitter 30 and the wafer 200, and is used to focus the probe light emitted by the probe light emitter 30. The second lens 90 is located in the light path between the wafer 200 and the probe light detector 40, and is used to diffuse the probe light reflected by the wafer 200.

[0064] It is understandable that in order to avoid the situation where the probe light spot formed on the wafer 200 is too large, resulting in a portion of the spot passing through the notch 201 and incident on the wafer stage 10, while a portion of the spot is incident on the wafer 200, thereby causing the detection signal corresponding to the notch to be not significantly different from the detection signals at other edge positions, the embodiment of the present invention can reduce the size of the spot formed by the probe light on the wafer 200 by providing a first lens 80 in the optical path between the probe light emitter 30 and the wafer 200. It should be noted that the embodiment of the present invention does not limit whether the first lens 80 is provided in the optical path between the probe light emitter 30 and the first reflector 60, or in the optical path between the first reflector 60 and the wafer 200. Those skilled in the art can provide the first lens 80 according to actual conditions.

[0065] To avoid a situation where the probe light detector 40 is unable to detect the probe light due to the probe light reflected by the wafer forming a spot that is too small, thereby causing the generated detection signal to continuously change suddenly, the embodiment of the present invention can increase the size of the spot formed by the probe light on the probe light detector 40 by disposing a second lens 90 in the optical path between the wafer 200 and the probe light detector 40. It should be noted that the embodiment of the present invention does not limit whether the second lens 90 is disposed in the optical path between the probe light detector 40 and the second reflector 70, or in the optical path between the second reflector 70 and the wafer 200. Those skilled in the art can arrange it according to actual circumstances.

[0066] An embodiment of the present invention further provides a wafer angle alignment method based on the photoacoustic film thickness measurement device provided by the above embodiment of the present invention. Figure 7 A flowchart of a wafer angle alignment method based on a photoacoustic film thickness measurement device provided by an embodiment of the present invention, referring to Figure 7 The wafer angle alignment method based on the photoacoustic film thickness measurement device in the embodiment of the present invention includes:

[0067] S110 , controlling the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together, and obtaining the rotation information of the motion platform and the detection signal generated by the probe light detector according to the received probe light.

[0068] Exemplary, reference Figure 1 、 Figure 5 and Figure 6The controller 50 is in communication connection with the motion platform 20 and the probe light detector 40 respectively, and can control the motion platform 20 to drive the wafer carrier 10 and the wafer 200 on the wafer carrier 10 to move first, so that the probe light is focused on the edge of the wafer 200, and then control the motion platform 20 to drive the wafer carrier 10 and the wafer 200 on the wafer carrier 10 to rotate one circle, and in the process of rotating one circle, the detection signal generated by the probe light detector 40 and the rotation information of the motion platform 20 are acquired.

[0069] As a feasible implementation, the control of the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together includes: determining a preset distance according to the size of the wafer and the position of the probe light spot formed on the wafer; and controlling the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together according to the preset distance and the position of the preset gap, so that the probe light emitted by the probe light emitter can be incident to the edge surface of the wafer.

[0070] For example, referring to Figure 1 , Figure 5 and Figure 6 , the controller 50 first determines a preset distance according to the size of the wafer 200 and the position of the probe light spot formed on the wafer 200, and then controls the motion platform 20 to move towards the position of the preset gap 201' according to the preset distance determined above, so that the probe light is first focused on the preset gap 201' located at the edge of the wafer 200, and finally controls the motion platform 20 to drive the wafer 200 to rotate in a preset rotation direction.

[0071] In other feasible implementations, the controller 50 only needs to determine a preset distance according to the size of the wafer 200 and the position of the probe light spot formed on the wafer 200 when the wafer angle alignment of a wafer of a certain size is implemented for the first time, and then, for wafers of the same size, the motion platform 20 can be directly controlled to move towards the position of the preset gap 201' according to the preset distance determined at the beginning, so that the probe light is focused on the preset gap 201' located at the edge of the wafer 200. In this way, it is beneficial to realize the function of universal wafer angle alignment.

[0072] S120, determining the deviation angle of the gap deviating from the preset gap according to the acquired detection signal and rotation information.

[0073] For example, referring to Figure 1 , Figure 5 and Figure 6For example, the position of the preset gap 201' corresponds to the wafer pick-and-place slot of the wafer stage 10, after the motion platform 20 is controlled to focus the probe light on the preset gap 201' located at the edge of the wafer 200, the controller 50 can determine the deviation angle of the gap deviating from the preset gap according to the acquired detection signal and rotation information, as shown in Figure 4 The rotation angle of the motion platform 20 corresponding to the sudden change of the detection signal is the deviation angle of the gap 201 deviating from the preset gap 201'.

[0074] S130, eliminate the deviation angle between the gap and the preset gap according to the deviation angle.

[0075] For example, referring to Figure 1 , Figure 5 and Figure 6 , the controller 50 can eliminate the deviation angle between the gap 201 and the preset gap 201' according to the above-mentioned deviation angle, so that the position of the gap 201 in the coordinate system of the motion platform 20 is the same as the position of the preset gap 201' in the coordinate system of the motion platform 20.

[0076] Specifically, in one possible implementation, eliminating the deviation angle between the gap and the preset gap according to the deviation angle includes: reconstructing the coordinate system of the motion platform according to the deviation angle, so that the position of the gap is the same as the position of the preset gap.

[0077] For example, referring to Figure 1 , Figure 5 and Figure 6 , the controller 50 only needs to ensure that the position of the gap 201 in the coordinate system of the motion platform 20 after reconstruction is the same as the position of the preset gap 201' in the original coordinate system of the motion platform 20, so that the position of the preset gap 201' is the same as the position of the gap 201. This method only needs to reconstruct the coordinate system of the motion platform 20 to eliminate the deviation angle between the gap 201 and the preset gap 201', which is simple and has high precision.

[0078] Specifically, in another possible implementation, the photoacoustic film thickness measuring device in the embodiment of the application further includes a wafer moving device. Eliminating the deviation angle between the gap and the preset gap according to the deviation angle includes: controlling the wafer moving device to move the wafer to change the position of the wafer on the wafer stage, so that the position of the gap is the same as the position of the preset gap.

[0079] For example, referring to Figure 1 , Figure 5 and Figure 6The controller 50 is connected with a wafer moving device (not shown in the figure) in communication, and can control the wafer moving device to grab the wafer 200 placed on the wafer stage 10, and then control the wafer moving device to rotate the wafer 200 by the deviation angle in the same rotating direction as the motion platform 20 according to the deviation angle between the gap 201 and the preset gap 201', and finally control the wafer moving device to place the rotated wafer 200 on the wafer stage 10, so that the position of the gap 201 of the wafer 200 coincides with the position of the preset gap 201', and the position of the gap 201 in the coordinate system of the motion platform 20 is the same as the position of the preset gap 201' in the coordinate system of the motion platform 20. The method can directly determine that the deviation angle between the gap 201 and the preset gap 201' has been eliminated.

[0080] The wafer angle alignment method is realized by the wafer stage 10, the motion platform 20, the probe light emitter 30, the probe light detector 40 and the controller 50 in the photoacoustic film thickness measuring device for measuring the thickness of the wafer, so that it is not necessary to additionally set the wafer angle alignment device including the gap finder and the laser to realize the wafer angle alignment, and the cost of the wafer angle alignment is reduced.

[0081] The specific embodiments described above do not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A photoacoustic film thickness measurement device, characterized in that: It includes a wafer stage, a motion platform, a probe light emitter, a probe light detector and a controller; The wafer stage is used to carry a wafer, and the wafer includes a notch; the motion platform is connected to the wafer stage; the controller is in communication with the motion platform, and is used to control the motion platform to drive the wafer stage and the wafer on the wafer stage to move together, and obtain rotation information of the motion platform; the controller first controls the motion platform to move so that the probe light emitted by the probe light emitter is focused on the edge of the wafer, and then controls the motion platform to drive the wafer to rotate one circle; During the rotation of the motion platform, the probe light emitted by the probe light emitter can be incident on the edge surface of the wafer or pass through the notch to be incident on the wafer carrier, and then be incident on the probe light detector after being reflected by the edge surface of the wafer or the wafer carrier. The probe light detector is used to generate a detection signal according to the received probe light; The controller is also in communication with the probe light detector, and is used to determine a deviation angle of the gap from a preset gap based on the acquired detection signal and the rotation information, and to eliminate the deviation angle between the gap and the preset gap based on the deviation angle.

2. The photoacoustic film thickness measurement device according to claim 1, characterized in that: The controller is used to determine a preset distance according to the size of the wafer and the position of the light spot formed by the probe light on the wafer, and control the motion platform to drive the wafer carrier and the wafer on the wafer carrier to move together according to the preset distance and the position of the preset notch, so that the probe light emitted by the probe light emitter can be incident on the edge surface of the wafer.

3. The photoacoustic film thickness measurement device according to claim 1, characterized in that: The controller is used to reconstruct the coordinate system of the motion platform according to the deviation angle, so that the position of the gap is the same as the position of the preset gap.

4. The photoacoustic film thickness measurement device according to claim 1, characterized in that: Also included are wafer moving equipment; The controller is also in communication with the wafer moving device, and is used to control the wafer moving device to move the wafer according to the deviation angle to change the position of the wafer on the wafer carrier, thereby making the position of the notch the same as the position of the preset notch.

5. The photoacoustic film thickness measurement device according to claim 1, characterized in that: Also includes a first reflector and / or a second reflector; The first reflector is located in the optical path between the probe light emitter and the wafer, and is used to change the optical path of the probe light emitted by the probe light emitter so that the probe light reflected by the first reflector is incident on the edge surface of the wafer; The second reflector is located in the optical path between the wafer and the probe light detector, and is used to change the optical path of the probe light reflected by the edge surface of the wafer so that the probe light reflected by the second reflector is incident on the probe light detector.

6. The photoacoustic film thickness measurement device according to claim 1, characterized in that: Also includes a first lens and / or a second lens; The first lens is located in the optical path between the probe light emitter and the wafer, and is used to focus the probe light emitted by the probe light emitter; The second lens is located in the optical path between the wafer and the probe light detector, and is used to diffuse the probe light reflected by the wafer.

7. A wafer angle alignment method based on the photoacoustic film thickness measurement device according to any one of claims 1 to 6, characterized in that: include: Controlling the motion platform to drive the wafer stage and the wafer on the wafer stage to move together, and obtaining rotation information of the motion platform and a detection signal generated by the probe light detector according to the received probe light; determining a deviation angle of the gap from a preset gap based on the acquired detection signal and the rotation information; The deviation angle between the notch and the preset notch is eliminated according to the deviation angle.

8. The wafer angle alignment method according to claim 7, wherein: Controlling the motion platform to drive the wafer stage and the wafer on the wafer stage to move together includes: determining a preset distance according to the size of the wafer and the position of the light spot formed by the probe light on the wafer; The motion platform is controlled according to the preset distance and the position of the preset notch to drive the wafer carrier and the wafer on the wafer carrier to move together, so that the probe light emitted by the probe light emitter can be incident on the edge surface of the wafer.

9. The wafer angle alignment method according to claim 7, wherein: Eliminating the deviation angle between the gap and the preset gap according to the deviation angle includes: The coordinate system of the motion platform is reconstructed according to the deviation angle so that the position of the notch is the same as the position of the preset notch.

10. The wafer angle alignment method according to claim 7, wherein: The photoacoustic film thickness measurement device further includes a wafer moving device; Eliminating the deviation angle between the gap and the preset gap according to the deviation angle includes: It is used to control the wafer moving device to move the wafer according to the deviation angle to change the position of the wafer on the wafer carrier, thereby making the position of the notch the same as the position of the preset notch.

Images