A laser focus image plane rotator and a laser focus image plane rotation method

Abstract

The present invention relates to a laser focus image plane rotator and a method for rotating a laser focus image plane, belonging to the technical field of semiconductor processing, and solves the problem that the traditional wafer cutting width cannot meet the requirements of high-precision processing. A laser focus image plane rotator includes a servo motor, a precision transmission device, a prism base, a Dove prism, a motion control card, and a motor driver. A control method for the laser focus image plane rotator specifically includes the following steps: presetting the motion parameters of the wafer carrier, generating the laser focus image plane rotation parameters, performing cutting with a laser cutter, and controlling the focus along the cutting trajectory. In the present invention, the Dove prism can cooperate with the motion trajectory of the wafer, and the minor axis of the elliptical light spot of the light focus is always perpendicular to the cutting direction, ensuring the cutting effect, meeting the high-precision processing requirements of wafer cutting, realizing real-time and continuous cutting work with different motion trajectories, reducing the production cost, and improving the processing precision and processing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and particularly to a laser focus image plane rotator and a laser focus image plane rotation method. Background Art

[0002] The whole production process of semiconductor devices is usually divided into two parts: wafer manufacturing process and packaging and testing process. The packaging and testing process of chips begins with separating wafers into individual chips, that is, wafer dicing process. Wafer dicing is a post-process in the chip manufacturing process. On a single wafer, usually hundreds to thousands of chips are connected together. The process of separating each chip with independent electrical performance is called dicing or cutting. Laser dicing is currently a relatively common method for wafer cutting, and among them, laser stealth dicing is a relatively advanced method.

[0003] Traditional laser stealth dicing technology uses infrared light with a wavelength of 1064nm. Through optical shaping, it passes through the material surface and focuses inside the material. In the focal area, the energy density is relatively high, and a multi-photon absorption non-linear absorption effect will be formed, making the material modified to form cracks. Then, according to the material thickness, the laser focus is controlled to cut layer by layer from bottom to top. Each laser pulse acts at equal intervals, and an equidistant damage can form a modified layer inside the material. At the position of the modified layer, the molecular bonds of the material are damaged, and the connection of the material becomes fragile and easy to separate. After cutting, by stretching the carrier film, the products are fully separated, and gaps are generated between chips.

[0004] There is a certain astigmatism in the laser output spot of the traditional cutting method, and there is a certain gap in the beam quality in different directions, resulting in a certain ellipticity of the focused laser spot. This makes the processing widths and qualities of two orthogonal processing trajectories different during the process of laser processing of materials. In the existing laser processing, in order to eliminate this problem, the method adopted is to rotate the workpiece so that its cutting trajectory corresponds to and remains the same as the optimal focus direction of the laser spot. This method has a complex structure and a high cost. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a laser focus image plane rotator and a laser focus image plane rotation method to solve the problem that the existing wafer cutting width cannot meet the requirements of high-precision processing.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A laser focus image plane rotator includes a servo motor, a precision transmission device, a prism base, a Dove prism, a motion control card, and a motor driver; the output shaft of the servo motor is connected to the precision transmission device, the precision transmission device is connected to the prism base, and a Dove prism is installed in the middle of the prism base. The servo motor is connected to the motor driver through a first control line, and the motor driver is connected to the motion control card through a second control line.

[0008] Further: The laser focus image plane rotator further includes a connecting device, and the connecting device includes a mounting plate and mounting holes; mounting holes are provided in the mounting plate.

[0009] Further: The precision transmission device includes a first transmission gear and a second transmission gear; the first transmission gear meshes with the second transmission gear.

[0010] Further: The precision transmission device (4) further includes a transmission housing (401), and the transmission housing (401) is rotatably connected to the first transmission gear (402) and the second transmission gear (403).

[0011] Further: The transmission housing (401) is provided with a light passing hole.

[0012] Further: The prism base includes connecting columns, connecting plates, bolts, and pressing sheets; connecting plates are installed in the middle of the connecting columns, threaded holes are provided in the connecting plates, bolts are installed in the threaded holes, and the bolts are connected through the pressing sheets.

[0013] Further: A piezoelectric ceramic is installed on one side of the connecting column, and a focusing lens is installed on the other side of the piezoelectric ceramic.

[0014] Further: The laser focus image plane rotator further includes a prism housing.

[0015] A method for rotating the laser focus image plane of a laser focus image plane rotator, the specific steps include:

[0016] Step 1, preset the motion parameters of the wafer carrier: The laser focus image plane rotator is installed in a laser cutting machine, and the laser cutting machine includes a wafer carrier. The wafer in the laser cutting machine moves to realize the cutting of the wafer. The cutting of the wafer is controlled by presetting the motion direction and speed parameters of the wafer carrier.

[0017] Step 2, generate the laser focus image plane rotation parameters: The motion control card generates the laser focus image plane rotation parameters according to the preset motion parameters of the wafer carrier, and generates the laser focus image plane rotation parameters according to the motion trajectory and speed of the preset wafer carrier. The generated laser focus image plane rotation parameters include the rotation time and the rotation angle.

[0018] Step 3: The laser cutting instrument cuts the wafer carrier. The wafer carrier moves according to the preset motion parameters of the wafer carrier. When it reaches the cutting position, the laser generating device is started to generate a laser focus for cutting.

[0019] Step 4: Control the focus following the cutting trajectory: According to the generated laser focus image plane rotation parameter, the laser focus image plane rotator controls the short axis of the elliptical laser focus spot to cut the inside of the wafer.

[0020] Furthermore, step 2.1 is included in step 2. Step 2.1 is the pre-rotation of the first knife focus: Before the laser focus cuts, the short axis of the elliptical laser focus spot is pre-controlled to be perpendicular to the cutting trajectory.

[0021] Furthermore, step 2.2 is included in step 2. Step 2.2 is the calibration of the laser focus image plane rotator: The position of the short axis of the elliptical laser focus spot is determined by the printing method, the inclined plate method or the blue spark method, compared with the preset focus position and focus direction, and adjusted through the prism base according to the comparison difference.

[0022] Furthermore: When the elliptical laser focus spot needs to rotate by an arbitrary angle N°, the Dove prism in the laser focus image plane rotator rotates in the same direction as the elliptical laser focus spot by N° / 2.

[0023] Furthermore: An electric platform is installed at the bottom of the wafer carrier described in step 1.

[0024] Furthermore: Step 2.3 is included in step 2. Step 2.3 is the laser focus height compensation: The laser cutting instrument also includes a laser displacement meter; the laser displacement meter pre-detects the height change of the wafer surface on the cutting trajectory to be cut, and controls the piezoelectric ceramic to control the focusing lens during the laser cutting of the wafer, so that the laser focus changes with the height change of the wafer surface, and the laser focus is always located inside the wafer.

[0025] The beneficial effects of the above technical solutions are as follows:

[0026] 1. The mutual cooperation of the servo motor, the precision transmission device, the prism base, the Dove prism, the motion control card and the motor driver enables the Dove prism to cooperate with the motion trajectory of the wafer. The short axis of the elliptical laser focus spot is always perpendicular to the cutting direction, ensuring the cutting effect, meeting the high-precision processing requirements of wafer cutting, realizing real-time and continuous cutting work of different motion trajectories, and also being able to realize laser processing of special processing trajectories, greatly improving the processing precision and processing efficiency. The equipment used in this method has a simple structure and greatly reduces the production cost.

[0027] 2. The mutual cooperation between the laser displacement gauge and the piezoelectric ceramic inside the laser cutting instrument enables the laser focus to be focused inside the wafer, and cuts the inside of the wafer along the shape of the wafer surface, avoiding the traditional laser cutting where the focus moves linearly to the upper or lower surface of the wafer due to wafer warping and deformation, generating dust, thereby avoiding contamination of the wafer and affecting the subsequent processes, and increasing the yield of the chips.

[0028] 3. The method of using a piezoelectric ceramic for height adjustment has the advantages of fast response speed, large generated pressure, and precise operation compared with electronic and hydraulic actuators. It is beneficial to the height response of the focus in wafer compensation cutting, provides guarantee for the focus to follow the changes of the wafer surface, and at the same time can make the cutting speed of wafer compensation cutting faster, increasing the production efficiency.

[0029] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0030] The drawings are only for the purpose of showing specific embodiments, and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs represent the same components.

[0031] Figure 1 It is a flowchart of a laser focus image plane rotator and a laser focus image plane rotation method according to the present invention.

[0032] Figure 2 It is a schematic structural diagram of a laser focus image plane rotator according to the present invention.

[0033] Figure 3 It is a schematic structural diagram of the other side of the laser focus image plane rotator according to the present invention.

[0034] Figure 4 It is a schematic structural diagram of the Dove prism of the laser focus image plane rotator according to the present invention.

[0035] Figure 5 It is a schematic structural diagram of the prism base of the laser focus image plane rotator according to the present invention.

[0036] Figure 6 It is a schematic structural diagram of the first transmission gear of the laser focus image plane rotator according to the present invention.

[0037] Figure 7 It is an optical path diagram of the laser passing through the Dove prism image according to the present invention.

[0038] Figure 8 This is the schematic diagram of the laser passing through the Dove prism image in the present invention.

[0039] In the figure: 1. Connecting device, 2. Prism housing, 3. Servo motor, 4. Precision transmission device, 5. Prism base, 6. Piezoelectric ceramic, 7. Focusing lens, 8. Motor driver, 9. Motion control card, 10. Dove prism, 101. Mounting plate, 102. Mounting hole, 401. Transmission housing, 402. First transmission gear, 403. Second transmission gear, 501. Connecting column, 502. Connecting plate, 503. Compression sheet, 504. Bolt. Specific embodiments

[0040] The following will specifically describe the preferred embodiments of the present invention in conjunction with the accompanying drawings, where the accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention.

[0041] Embodiment 1

[0042] A specific embodiment of the present invention is as Figure 2 shown. A laser focus image plane rotator includes a servo motor 3, a precision transmission device 4, a prism base 5, a Dove prism 10, a motion control card 9, and a motor driver 8; the output shaft of the servo motor 3 is connected to a precision transmission device 4, the precision transmission device 4 is connected to a prism base 5, a Dove prism 10 is installed in the middle of the prism base 5, the servo motor 3 is connected to a motor driver 8 through a first control line, and the motor driver 8 is connected to a motion control card 9 through a second control line.

[0043] The servo motor 3 is used to drive the precision transmission device 4 to move, the precision transmission device 4 drives the prism base 5 to rotate, the prism base 5 drives the Dove prism 10 to rotate, the rotation angle of the Dove prism 10 is half of the rotation angle of the short axis of the elliptical light spot of the focus, the motion control card 9 is used to generate the time, speed, and angle data of the motor movement, and the motor driver 8 is used to convert the data generated by the motion control card 9 into pulses for controlling the servo motor 3.

[0044] Preferably: as Figure 3 shown, the laser focus image plane rotator further includes a connecting device 1, and the connecting device 1 includes a mounting plate 101, and mounting holes 102 are formed in the mounting plate 101.

[0045] The mounting plate 101 is used to fix the relative positions of the servo motor 3 and the precision transmission device 4, and the mounting holes 102 are used to fix the relative positions of the laser cutting instrument and the laser focus image plane rotator.

[0046] Preferably: as Figure 6As shown, the precision transmission device 4 includes a transmission housing 401, a first transmission gear 402, and a second transmission gear 403; the first transmission gear 402 meshes with the second transmission gear 403, and both the first transmission gear 402 and the second transmission gear 403 are connected to the transmission housing 401 through bearings.

[0047] The servo motor 3 drives the first transmission gear 402 to rotate, the first transmission gear 402 drives the second transmission gear 403 to rotate, the second transmission gear 403 drives the prism base 5 to rotate, and the setting of the precision transmission device 4 ensures that the laser light path in the vacant position in the middle of the second transmission gear 403 can propagate without interference.

[0048] Preferably: As Figure 5 shown, the prism base 5 includes a connecting column 501, a connecting plate 502, bolts 504, and a pressing piece 503; the middle parts of the connecting columns 501 are all connected with connecting plates 502, threaded holes are formed in the connecting plates 502, bolts 504 are installed in the threaded holes, and the bolts 504 are connected through the pressing piece 503.

[0049] The upper end of the connecting column 501 is connected to the second transmission gear 403, so that the connecting column 501 rotates following the rotation of the second transmission gear 403. The settings of the connecting plate 502, the bolts 504, and the pressing piece 503 fix the Dove prism 10 on the connecting column 501, and the position of the Dove prism 10 can be finely adjusted by loosening the bolts 504 to ensure that the laser light path coincides with the longitudinal axis of the Dove prism 10.

[0050] Preferably: As Figure 4 shown, a piezoelectric ceramic 6 is installed on one side of the connecting column 501, and a focusing lens 7 is installed on the other side of the piezoelectric ceramic 6.

[0051] The piezoelectric ceramic 6 can control the height of the focusing lens 7 to achieve the control of the laser focus height, which is convenient for adjusting the laser focus height when processing wafers of different thicknesses.

[0052] Preferably: The laser focus image plane rotator further includes a prism housing 2.

[0053] The prism housing 2 is used to ensure the cleanliness of the reflecting surface of the Dove prism 10 and prevent dust and other sundries from affecting the reflection of the Dove prism 10.

[0054] As Figure 1 shown, a laser focus image plane rotation method of a laser focus image plane rotator:

[0055] Step 1, preset the motion parameters of the wafer carrier stage: The laser focus image plane rotator is installed in the laser cutting instrument. The laser cutting instrument includes a wafer carrier stage. The wafer in the laser cutting instrument moves to realize the cutting of the wafer. The cutting of the wafer is controlled by presetting the motion direction and speed parameters of the wafer carrier stage.

[0056] Place the wafer to be cut on the wafer carrier stage of the laser cutting instrument. The laser cutting instrument will form a modified layer inside the wafer through the laser focus, making the connections between the chips inside the wafer fragile and easy to separate. The cutting trajectory and cutting speed of the laser cutting instrument for the wafer are preset. After being set, the laser cutting instrument will control the wafer carrier stage to move along the preset trajectory.

[0057] Step 2, generate the laser focus image plane rotation parameters: The motion control card 9 generates the laser focus image plane rotation parameters according to the preset motion parameters of the wafer carrier stage.

[0058] Obtain the preset cutting trajectory and cutting speed on the wafer carrier stage of the laser cutting instrument, and generate the motion parameters of the motion control card 9 in the laser focus image plane rotator according to the cutting trajectory and cutting speed. The motion parameters include the time, speed, and angle for controlling the rotation of the servo motor 3 by the motor driver 8.

[0059] Step 3, the laser cutting instrument performs cutting: The wafer carrier stage moves according to the preset motion parameters of the wafer carrier stage. When reaching the cutting position, the laser generating device is started to generate a laser focus for cutting.

[0060] The laser generated by the laser generating device undergoes propagation and refraction. The emitted laser spot is reflected by multiple mirrors and finally vertically reflected downward onto the workpiece on the lower platform. During the propagation of the laser, the laser passes through the Dove prism 10. The rotation of the laser focus by the Dove prism 10 finally passes through the focusing device, making the focus of the laser act inside the wafer. The refraction principle of the Dove prism 10 is that in the Dove prism 10, the light usually propagates along the longitudinal axis of the prism. When placed, the longitudinal axis of the Dove prism 10 is along the optical axis direction of the output light. The light is reflected once on the bottom surface, forming an inverted image on the other side of the prism. Rotating the prism along the longitudinal axis, i.e., the optical axis, will make the image rotate at twice the rotation angle of the prism. That is to say, when the longitudinal axis of the Dove prism 10 coincides with the laser optical axis and rotates 45 degrees around the optical axis, the spot emitted from the prism will rotate 90 degrees in the same rotation direction. In this way, the image plane direction of the optimal focus can be rotated to another direction perpendicular to the original cutting direction for cutting, and the 360° rotation of the focus can be controlled by controlling the rotation of the prism.

[0061] Step 4, controlling the focus along the cutting trajectory: According to the generated laser focus image plane rotation parameters, the laser focus image plane rotator controls the short axis of the elliptical laser focus spot to cut the inside of the wafer.

[0062] The motor driver 8 in the laser focus image plane rotator controls the rotation time, speed, and angle of the servo motor 3. The output shaft of the servo motor 3 drives the precision transmission device 4 to rotate. The precision transmission device 4 drives the prism base 5 to rotate. The prism base 5 drives the Dove prism 10 to rotate. When the Dove prism 10 rotates a certain angle, as Figure 8 shown, the rotation angle of the short axis of the elliptical laser focus spot passing through the Dove prism 10 is twice the rotation angle of the Dove prism 10. Based on this principle, the rotation of the elliptical laser focus spot is achieved, enabling the laser focus image plane rotator to control the short axis of the elliptical laser focus spot to cut the inside of the wafer.

[0063] Preferably, step 2 includes step 2.1, and step 2.1 is the pre-rotation of the first knife focus: Before the laser focus cuts, first control the short axis of the elliptical laser focus spot to be perpendicular to the cutting trajectory, so that the focus at the initial position uses the short axis of the elliptical laser focus spot for cutting.

[0064] The Dove prism 10 is pre-rotated in advance to ensure that when the laser generating device emits laser light, the short axis of the elliptical laser focus spot is perpendicular to the cutting direction, ensuring the overall cutting effect and avoiding the cutting line width at the initial cutting point being inconsistent with the overall cutting line width.

[0065] Preferably, step 2 includes step 2.2, and step 2.2 is the calibration of the laser focus image plane rotator: Determine the position of the short axis of the elliptical laser focus spot through the printing method, the inclined plate method, or the blue spark method, compare it with the preset focus position and focus direction, and adjust it through the prism base 5 according to the difference obtained from the comparison;

[0066] Compare the angle of the short axis of the elliptical laser focus spot with the preset position, and perform calibration when there is a deviation to ensure that the laser cutting always uses the short axis of the elliptical laser focus spot for cutting, meeting the high-precision processing requirements of wafer cutting.

[0067] Preferably: As Figure 7 shown, when the elliptical laser focus spot in step 4 needs to rotate an arbitrary angle N°, the Dove prism (10) in the laser focus image plane rotator rotates N° / 2 in the same direction as the elliptical laser focus spot.

[0068] The rotation angle of the Dove prism 10 is twice the rotation angle of the elliptical laser focus spot, which is the rotation angle of the prism.

[0069] Preferably, an electric platform is installed at the bottom of the wafer carrier. The electric platform is used to control the movement of the wafer carrier, and the wafer carrier drives the wafer placed on its surface to rotate. The electric platform includes an X-axis displacement mechanism and a Y-axis displacement mechanism. One end of the X-axis displacement mechanism is installed with the Y-axis displacement mechanism, and the electric platform can drive the wafer carrier to move along any trajectory in the X and Y axis directions.

[0070] Embodiment 2

[0071] Based on Embodiment 1, in this Embodiment 2, the structure of the laser cutting machine and the method of wafer compensation cutting in Embodiment 1 are added. Preferably, step 2.3 is added between step 2 and step 3. Step 2.3 is laser focus height compensation: The laser cutting machine further includes a laser displacement meter; the laser displacement meter pre-detects the height change of the wafer surface on the trajectory to be cut, and when the wafer is laser cut, the piezoelectric ceramic 6 is controlled to control the focusing lens 7 so that the laser focus is always located inside the wafer.

[0072] The mutual cooperation between the laser displacement meter and the piezoelectric ceramic 6 in the laser cutting machine enables the laser focus to be focused inside the wafer, and cuts inside the wafer along the shape of the wafer surface, avoiding the traditional laser cutting that is prone to the focus moving linearly to the upper or lower surface of the wafer due to wafer warping and deformation, generating dust, thereby avoiding contamination of the wafer and affecting the subsequent processes, and increasing the yield of the chip.

[0073] The principle of laser focus height compensation is as follows: The laser displacement meter is used to detect the height change of the wafer surface. The laser displacement meter pre-detects the height change on the trajectory of the wafer to be cut once, and feeds back the height changes at different cutting positions detected to the control card of the laser cutting machine. The control card generates a program for controlling the height voltage of the piezoelectric ceramic 6 according to the actual movement speed of the wafer carrier during laser cutting. During actual laser cutting, the piezoelectric ceramic 6 is actuated, the voltage of the piezoelectric ceramic 6 is controlled, and the piezoelectric ceramic 6 undergoes a height change under the received voltage change. The piezoelectric ceramic 6 drives the focusing lens 7 to move up and down, thereby realizing the height change of the laser focus.

[0074] The method of using the piezoelectric ceramic 6 for height adjustment has the advantages of fast response speed, large generated pressure, and precise operation compared with electronic and hydraulic actuators. It is beneficial to the height response of the focus in wafer compensation cutting, provides guarantee for the focus to follow the change of the wafer surface, and at the same time can make the cutting speed of wafer compensation cutting faster and increase production efficiency.

[0075] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for rotating the laser focus image plane of a laser focus image plane rotator, characterized in that, The laser focus image plane rotator includes a servo motor (3), a precision transmission device (4), a prism base (5), a Dove prism (10), a motion control card (9), a motor driver (8), and a laser displacement meter; the output shaft of the servo motor (3) is connected to the precision transmission device (4), the precision transmission device (4) is connected to the prism base (5), a Dove prism (10) is installed in the middle of the prism base (5), the servo motor (3) is connected to the motor driver (8) through a first control line, and the motor driver (8) is connected to the motion control card (9) through a second control line; The precision transmission device (4) includes a transmission housing (401), a first transmission gear (402), and a second transmission gear (403); the transmission housing (401) is rotationally connected to the first transmission gear (402) and the second transmission gear (403), and the first transmission gear (402) meshes with the second transmission gear (403); the servo motor (3) drives the first transmission gear (402) to rotate, the first transmission gear (402) drives the second transmission gear (403) to rotate, and the second transmission gear (403) drives the prism base (5) to rotate. The setting of the precision transmission device (4) ensures that the laser light path can propagate in the vacant position in the middle of the second transmission gear (403) without interference; The prism base (5) includes a connecting column (501), a connecting plate (502), bolts (504), and a pressing piece (503); the middle of the connecting column (501) is connected and installed with connecting plates (502), threaded holes are opened in the connecting plates (502), bolts (504) are installed in the threaded holes, and the bolts (504) are connected through the pressing piece (503); The upper end of the connecting column (501) is connected to the second transmission gear (403), so that the connecting column (501) rotates following the rotation of the second transmission gear (403). The setting of the connecting plate (502), bolts (504), and pressing piece (503) fixes the Dove prism (10) on the connecting column (501). The position of the Dove prism (10) is finely adjusted by loosening the bolts (504) to ensure that the laser light path coincides with the longitudinal axis of the Dove prism (10); A piezoelectric ceramic (6) is installed on one side of the connecting column (501), and a focusing lens (7) is installed on the other side of the piezoelectric ceramic (6); the piezoelectric ceramic (6) is used to control the height of the focusing lens (7) to realize the control of the laser focus height; The laser focus image plane rotation method of the laser focus image plane rotator includes the following steps: Step 1, preset the motion parameters of the wafer carrier: The laser focus image plane rotator is installed in a laser cutting machine. The laser cutting machine includes a wafer carrier. The wafer in the laser cutting machine moves to realize the cutting of the wafer. The cutting of the wafer is controlled by presetting the motion direction and speed parameters of the wafer carrier; Step 2, generate the laser focus image plane rotation parameters: The motion control card (9) generates the laser focus image plane rotation parameters according to the preset motion parameters of the wafer carrier; The laser focus image plane rotator further includes a laser displacement meter, which is arranged on the laser cutting instrument. The laser displacement meter pre-detects the height change of the wafer surface on the to-be-cut track, and during the laser cutting of the wafer, the piezoelectric ceramic (6) is controlled to further control the focusing lens (7) so that the laser focus is always located inside the wafer; Step 3: The laser cutting instrument performs cutting. The wafer carrier moves according to the preset movement parameters of the wafer carrier. When it reaches the cutting position, the laser generating device is started to generate a laser focus for cutting; Step 4: Control the focus following the cutting track. According to the generated laser focus image plane rotation parameters, the laser focus image plane rotator controls the short axis of the laser focus elliptical spot to cut inside the wafer.

2. The method for rotating the laser focus image plane of a laser focus image plane rotator according to claim 1, characterized in that, The laser focus image plane rotator further includes a connecting device (1), and the connecting device (1) includes a mounting plate (101), and a mounting hole (102) is formed in the mounting plate (101).

3. The method for rotating the laser focus image plane of a laser focus image plane rotator according to claim 1, characterized in that, The laser focus image plane rotator further includes a prism housing (2).

4. The method for rotating the laser focus image plane of a laser focus image plane rotator according to claim 1, characterized in that, The transmission housing (401) is provided with a light passing hole.

5. The method for rotating the laser focus image plane of a laser focus image plane rotator according to claim 1, characterized in that, When the laser focus elliptical spot in Step 4 needs to rotate by an arbitrary angle N°, the Dove prism (10) in the laser focus image plane rotator rotates in the same direction as the laser focus elliptical spot by N° / 2.

6. The method for rotating the laser focus image plane of a laser focus image plane rotator according to claim 1, characterized in that, An electric platform is installed at the bottom of the wafer carrier described in Step 1.

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