CN113031410A - Wafer back alignment method, wafer back alignment equipment and photoetching machine - Google Patents

Wafer back alignment method, wafer back alignment equipment and photoetching machine Download PDF

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Publication number
CN113031410A
CN113031410A CN202110395085.8A CN202110395085A CN113031410A CN 113031410 A CN113031410 A CN 113031410A CN 202110395085 A CN202110395085 A CN 202110395085A CN 113031410 A CN113031410 A CN 113031410A
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China
Prior art keywords
wafer
laser beam
alignment mark
preset position
alignment
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CN202110395085.8A
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Chinese (zh)
Inventor
李天慧
何学缅
吴永玉
刘佑铭
李剑波
刘金营
李敏
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GTA Semiconductor Co Ltd
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SHANGHAI ADVANCED SEMICONDUCTO
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Priority to CN202110395085.8A priority Critical patent/CN113031410A/en
Publication of CN113031410A publication Critical patent/CN113031410A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
    • G03F9/7046—Strategy, e.g. mark, sensor or wavelength selection
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7049—Technique, e.g. interferometric
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/7076—Mark details, e.g. phase grating mark, temporary mark

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)

Abstract

The invention provides a wafer back alignment method, wafer back alignment equipment and a photoetching machine, wherein the wafer back alignment method comprises the following steps: providing a wafer; emitting a first laser beam to the wafer to etch a front alignment mark at a first preset position on the front of the wafer, and emitting a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system; the front alignment mark is set as a front reference for wafer processing, and the back alignment mark is set as a back reference for wafer processing. According to the invention, the front alignment mark and the back alignment mark are respectively etched by the first laser beam and the second laser beam, so that the etched front alignment mark and the etched back alignment mark are in the same wafer coordinate system, the operation steps are reduced, the corresponding relation of a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation precision is improved.

Description

Wafer back alignment method, wafer back alignment equipment and photoetching machine
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to a wafer back alignment method, wafer back alignment equipment and a photoetching machine.
Background
The wafer back alignment is a process required for producing products such as CIS (CMOS Image Sensor) and IGBT (Insulated Gate Bipolar Transistor).
At present, there are a plurality of wafer back alignment methods, each of which has disadvantages, specifically as follows:
1. CCD (Charge-coupled Device) imaging alignment, which is prone to errors.
2. Aligning visible light (or infrared light) after thinning the wafer back:
to enable alignment, the polished wafer has a thickness of less than 5 μm, which, once thicker, results in poor alignment signal and reject the wafer.
An alignment method after thinning a wafer back adopts infrared light to penetrate through a silicon layer of a wafer and align mark images on the back. This approach is limited by the power limitations of the infrared source, often difficult to image clearly, affecting the alignment effect.
Another alignment method after thinning the wafer back is to directly image the mark on the wafer back by using visible light. In the method, the wafer is in close contact with the workpiece table, the visible light is directly aligned to a plurality of areas needing to be arranged on the workpiece table, the empty areas are fixed and have small areas, and therefore the position range which can be selected by the mark is actually influenced, and the situation that no mark is available often occurs; and the number of the hollow areas cannot be too large, otherwise, the wafer adsorption effect is influenced.
3. Other alignment methods require coordinate system conversion and compensation, as follows:
for example:
chinese patent application publication No. CN108008608A employs the following steps for the back alignment:
1) at least 2 alignment marks are arranged on the front surface of the wafer, so that a Wafer Coordinate System (WCS) is established, and at least 2 transmission marks are arranged on the edge of the wafer, so that a Wafer Geometric Coordinate System (WGCS) is established.
2) And loading the front surface of the wafer into a workpiece table, executing first alignment, and calculating to obtain the relative position relation between the WCS of the front surface and a zero coordinate system (WZCS) of the workpiece table.
3) And executing second alignment to obtain the relative position relationship between the WGCS and the WZCS.
4) And loading the back of the wafer into a workpiece table, performing third alignment, and calculating to obtain the relative position relation between the back WGCS and the WZCS.
5) And obtaining the relation between the WCS and the WZCS on the back surface according to the relation between the WCS and the WGCS on the front surface and the relation between the WGCS and the WZCS on the back surface, thereby realizing the alignment.
When the front and back surfaces of the wafer are aligned separately, the front and back surface references must be converted into the same coordinate system, which complicates the operation.
And, chinese patent application publication No. CN109817559 needs to make a front alignment mark and a back alignment mark of a flat-edge wafer, respectively, measure the deviation between the front alignment mark and the back alignment mark, and compensate and make the back alignment mark again according to the deviation, which is complicated in operation.
In view of the above, the invention provides a wafer back alignment method, a wafer back alignment apparatus and a lithography machine.
Disclosure of Invention
The invention provides a wafer back alignment method, wafer back alignment equipment and a photoetching machine, aiming at overcoming the defects that the front side and the back side of a wafer need to be aligned respectively, errors exist commonly, the alignment efficiency and the alignment accuracy are low, and the calculation accuracy is low in the prior art.
The invention solves the technical problems through the following technical scheme:
the invention provides a wafer back alignment method, which comprises the following steps:
providing a wafer;
emitting a first laser beam to the wafer to etch a front alignment mark at a first preset position on the front of the wafer, and emitting a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system;
the front side alignment mark is set as a front side reference for wafer processing, and the back side alignment mark is set as a back side reference for wafer processing.
Preferably, before the step of emitting the first laser beam to the wafer to etch the front alignment mark at the first preset position on the front surface of the wafer, and emitting the second laser beam to the wafer to etch the back alignment mark at the second preset position on the back surface of the wafer, the method for wafer back alignment further includes:
a laser beam is emitted to a beam splitter to split the laser beam into a first laser beam and a second laser beam.
Preferably, in the step of emitting the first laser beam to the wafer to etch the front alignment mark at the first predetermined position on the front surface of the wafer, and emitting the second laser beam to the wafer to etch the back alignment mark at the second predetermined position on the back surface of the wafer,
the first preset position and the second preset position have a preset relative position relation.
Preferably, in the step of emitting the first laser beam to the wafer to etch the front alignment mark at the first predetermined position on the front surface of the wafer, and emitting the second laser beam to the wafer to etch the back alignment mark at the second predetermined position on the back surface of the wafer,
and respectively controlling the time length for emitting the first laser beam and the time length for emitting the second laser beam so as to enable the etching depth of the front alignment mark to be different from the etching depth of the back alignment mark.
Preferably, the time length for emitting the first laser beam and the time length for emitting the second laser beam are controlled according to the medium etching rate.
Preferably, the step of providing a wafer includes:
and clamping the edge of a wafer to suspend the etching areas of the front surface and the back surface of the wafer.
Preferably, before the step of providing a wafer, the method for back-side alignment includes:
and respectively receiving the first laser beam and the second laser beam by two photoreceptors arranged at a preset position to calibrate the position of the laser beam, wherein the distance between the first laser beam and the second laser beam at the preset position is controlled within a preset position distance threshold value.
The invention also provides a wafer back alignment device, which comprises: a controller;
the controller is used for outputting a laser emission control instruction to emit a first laser beam to a wafer to be aligned so as to etch a front alignment mark at a first preset position on the front side of the wafer, and emit a second laser beam to the wafer so as to etch a back alignment mark at a second preset position on the back side of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system;
the controller is also configured to set the front alignment marks as front references for wafer processing and to set the back alignment marks as back references for wafer processing.
Preferably, the back of wafer alignment apparatus further comprises: a laser emitter and a beam splitter;
the laser transmitter is used for generating a laser beam according to a control laser generation instruction sent by the controller and transmitting the laser beam to the optical splitter;
the beam splitter is used for splitting the received laser beam into the first laser beam and the second laser beam according to the control laser emission instruction, emitting the first laser beam to a wafer to be aligned so as to etch the front alignment mark at the first preset position on the front side of the wafer, and emitting the second laser beam to the wafer so as to form the back alignment mark at the second preset position on the back side of the wafer.
Preferably, the back of wafer alignment apparatus further comprises: the device comprises a first focusing mirror, a second focusing mirror, a first reflecting mirror and a second reflecting mirror;
the beam splitter is specifically configured to emit the first laser beam to the first focusing mirror, and emit the second laser beam to the first reflecting mirror;
the first focusing lens is used for enabling the first laser beam to form focusing at the first preset position on the front surface of the wafer so as to etch the front surface alignment mark.
The first mirror is used for reflecting the second laser beam to the second mirror so as to adjust the direction of the second laser beam;
the second reflector is used for reflecting the second laser beam to the second focusing mirror so as to adjust the direction of the second laser beam;
the second focusing mirror is used for enabling the second laser beam to form a focus at the second preset position on the back surface of the wafer so as to etch the back surface alignment mark.
Preferably, the back of wafer alignment apparatus further comprises: a clamping portion;
the first focusing lens and the second focusing lens are oppositely arranged based on the clamping part;
the clamping part is used for clamping the edge of a wafer so as to suspend the etching areas of the front surface and the back surface of the wafer.
The invention also provides a photoetching machine which comprises the wafer back alignment equipment.
The positive progress effects of the invention are as follows: the front alignment mark and the back alignment mark are respectively etched through the first laser beam and the second laser beam, and the first preset position and the second preset position corresponding to the front alignment mark and the back alignment mark are respectively positioned in the same wafer coordinate system, so that the etched front alignment mark and the etched back alignment mark are positioned in the same wafer coordinate system, operation steps are reduced, the corresponding relation of calculating a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation accuracy is improved.
Drawings
Fig. 1 is a flowchart of a wafer back alignment method according to embodiment 1 of the present invention.
Fig. 2 is a flowchart of a wafer back alignment method according to embodiment 2 of the present invention.
Fig. 3 is a block diagram of a back side alignment apparatus according to embodiment 3 of the present invention.
Fig. 4 is a schematic structural diagram of a back side alignment apparatus according to embodiment 3 of the present invention.
Fig. 5 is a schematic diagram of a beam splitter in a wafer back alignment apparatus according to embodiment 3 of the present invention.
FIG. 6 is a block diagram of a lithography machine according to embodiment 4 of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
The invention provides a wafer back alignment method. Referring to fig. 1, the method for aligning the back of a wafer includes:
s11, a wafer is provided.
And S12, emitting a first laser beam to the wafer to etch a front alignment mark at a first preset position on the front surface of the wafer, and emitting a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back surface of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system. The front and back surfaces of the wafer use the same coordinate system, that is, the X-axis direction is from left to right with the center of the wafer as the origin coordinate, and the Y-axis direction is from notch (notch) of the wafer upward. The front (X, Y) coordinates are the back point coordinates.
S13, the front alignment mark is set as the front reference of the wafer processing, and the back alignment mark is set as the back reference of the wafer processing.
In step S12, the first preset position and the second preset position have a predetermined relative position relationship. The positions of the front alignment mark and the back alignment mark on the horizontal plane may be the same or different. The first preset position and the second preset position can be set according to actual conditions.
In step S12, the duration of emitting the first laser beam and the duration of emitting the second laser beam are controlled respectively so that the etching depth of the front alignment mark is different from the etching depth of the back alignment mark. Designs having different requirements for the etch depth of the front alignment marks and the etch depth of the back alignment marks may be adapted. Specifically, the time length for emitting the first laser beam and the time length for emitting the second laser beam are controlled according to the medium etching rate. Etching the given dielectric layer by using a set laser beam, wherein the change of the film thickness per minute is the dielectric etching rate, and the dielectric etching rate of the given dielectric layer can be measured in advance. The etching depth of the front alignment mark and the etching depth of the back alignment mark can be the same, and the front alignment mark and the back alignment mark can be set according to actual needs.
In specific implementation, before step S11, the method for aligning the wafer back includes:
and S10, respectively receiving the first laser beam and the second laser beam through two photoreceptors arranged at preset positions to calibrate the laser beam positions, wherein the distance between the first laser beam and the second laser beam at the preset positions is controlled within a preset position distance threshold value. Preferably, the predetermined position distance threshold may be 1 micron, and the predetermined position distance threshold may be set according to actual requirements.
According to the wafer back alignment method of the wafer, the front alignment mark and the back alignment mark are respectively etched through the first laser beam and the second laser beam, and the first preset position and the second preset position respectively corresponding to the front alignment mark and the back alignment mark are located in the same wafer coordinate system, so that the etched front alignment mark and the etched back alignment mark are located in the same wafer coordinate system, operation steps are reduced, the corresponding relation of calculating a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation accuracy is improved.
Example 2
The method for aligning the wafer back of the wafer in the embodiment is a further improvement of embodiment 1, and specifically includes:
referring to fig. 2, step S11 specifically includes:
s111, clamping the edge of a wafer to enable the etching areas of the front surface and the back surface of the wafer to be suspended.
Before step S12, the method for aligning a wafer back further includes:
and S14, emitting a laser beam to the beam splitter to split the laser beam into a first laser beam and a second laser beam.
After step S13, the method for back alignment further includes:
and S15, filling and polishing the etched grooves of the front alignment marks, and filling and polishing the etched grooves of the back alignment marks.
According to the wafer back alignment method of the wafer, the front alignment mark and the back alignment mark are respectively etched through the first laser beam and the second laser beam which are separated from the same laser beam, and the first preset position and the second preset position which respectively correspond to the front alignment mark and the back alignment mark are located in the same wafer coordinate system, so that the etched front alignment mark and the etched back alignment mark are located in the same wafer coordinate system, operation steps are reduced, the corresponding relation of calculating a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation accuracy is improved.
Example 3
The embodiment provides a wafer back alignment apparatus. The wafer back alignment apparatus implements the wafer back alignment method of the wafer in embodiment 1 or embodiment 2.
Referring to fig. 3 and 4, the back alignment apparatus includes: a controller 101. The control system includes a controller 101 (not shown in fig. 4).
The controller 101 is configured to output a control laser emission instruction to emit a first laser beam to a wafer to be aligned to etch a front alignment mark at a first preset position on the front side of the wafer, and emit a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back side of the wafer, where the first preset position and the second preset position are in the same wafer coordinate system, that is, the X-axis direction is from left to right with the wafer center as an origin coordinate, and the Y-axis direction is from notch (notch) of the wafer upwards. The front (X, Y) coordinates are the back point coordinates.
In the case where no wafer is placed, the laser beam position is calibrated by receiving a first laser beam and a second laser beam, respectively, by two photoreceptors placed at predetermined positions, the spacing of the first laser beam and the second laser beam at the predetermined positions being controlled within a predetermined position distance threshold. Preferably, the predetermined position distance threshold may be 1 micron, and the predetermined position distance threshold may be set according to actual requirements.
The controller 101 is also configured to set the front alignment marks as front references for wafer processing and to set the back alignment marks as back references for wafer processing.
In specific implementation, the back of wafer alignment apparatus further comprises: a laser transmitter 102 and a beam splitter 103.
The laser transmitter 102 is configured to generate a laser beam according to a control laser generation instruction sent by the controller 101 and transmit the laser beam to the beam splitter 103.
The beam splitter 103 is configured to split the received laser beam into a first laser beam and a second laser beam according to the control laser emission instruction, emit the first laser beam to the wafer to be aligned to etch a front alignment mark at a first preset position on the front side of the wafer, and emit the second laser beam to the wafer to etch a back alignment mark at a second preset position on the back side of the wafer.
Referring to fig. 5, the most common shape of the beam splitter 103 is a cube made of two triangular glass prisms glued together on a substrate using a polyester, epoxy or polyurethane type adhesive. The thickness of the resin layer is adjusted so that half (a certain wavelength) of the light incident through one "port" (i.e. the face of the cube) is reflected and the other half is transmitted further due to total internal reflection.
The first preset position and the second preset position have a preset relative position relation. The positions of the front alignment mark and the back alignment mark on the horizontal plane may be the same or different. The first preset position and the second preset position can be set according to actual conditions.
The beam splitter 103 is specifically configured to control a duration of emitting the first laser beam and a duration of emitting the second laser beam respectively so that an etching depth of the front alignment mark is different from an etching depth of the back alignment mark. Specifically, the time length for emitting the first laser beam and the time length for emitting the second laser beam are controlled according to the medium etching rate. Etching the given dielectric layer by using a set laser beam, wherein the change of the film thickness per minute is the dielectric etching rate, and the dielectric etching rate of the given dielectric layer can be measured in advance.
In specific implementation, referring to fig. 3 and 4, the back of wafer alignment apparatus further includes: a first focusing mirror 104, a second focusing mirror 105, a first reflecting mirror 106, a second reflecting mirror 107, and a holding part 108.
The beam splitter 103 is specifically configured to split the received laser beam into a first laser beam and a second laser beam, and to emit the first laser beam to the first focusing mirror 104 and the second laser beam to the first reflecting mirror 106.
The first focusing mirror 104 is used to focus the first laser beam at a first predetermined position on the front surface of the wafer to etch the front surface alignment mark.
The first mirror 106 is used for reflecting the second laser beam to the second mirror 107 to adjust the direction of the second laser beam.
The second mirror 107 is used for reflecting the second laser beam to the second focusing mirror 105 to adjust the direction of the second laser beam.
The second focusing mirror 105 is used to focus the second laser beam at a second predetermined location on the backside of the wafer to etch the backside alignment mark.
The first focusing mirror 104 and the second focusing mirror 105 are disposed oppositely based on the holding portion 108.
The clamping portion 108 is used for clamping the edge of a wafer to suspend the etching areas of the front and back surfaces of the wafer.
According to the wafer back alignment equipment for the wafer, the front alignment mark and the back alignment mark are respectively etched through the first laser beam and the second laser beam which are separated from the same laser beam, the first preset position and the second preset position which respectively correspond to the front alignment mark and the back alignment mark are located in the same wafer coordinate system, so that the etched front alignment mark and the etched back alignment mark are located in the same wafer coordinate system, operation steps are reduced, the corresponding relation of calculating a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation accuracy is improved.
Example 4
The embodiment provides a lithography machine. Referring to fig. 6, the lithography machine includes the back alignment apparatus in embodiment 3, that is, the lithography machine includes a controller 101, a laser emitter 102, a beam splitter 103, a first focusing mirror 104, a second focusing mirror 105, a first reflecting mirror 106, a second reflecting mirror 107, and a clamping portion 108.
The controller 101 is configured to output a control laser emission instruction to emit a first laser beam to a wafer to be aligned to etch a front alignment mark at a first preset position on the front side of the wafer, and emit a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back side of the wafer, where the first preset position and the second preset position are in the same wafer coordinate system, that is, the X-axis direction is from left to right with the wafer center as an origin coordinate, and the Y-axis direction is from notch (notch) of the wafer upwards. The front (X, Y) coordinates are the back point coordinates.
In the case where no wafer is placed, the laser beam position is calibrated by receiving a first laser beam and a second laser beam, respectively, by two photoreceptors placed at predetermined positions, the spacing of the first laser beam and the second laser beam at the predetermined positions being controlled within a predetermined position distance threshold. Preferably, the predetermined position distance threshold may be 1 micron, and the predetermined position distance threshold may be set according to actual requirements.
The controller 101 is also configured to set the front alignment marks as front references for wafer processing and to set the back alignment marks as back references for wafer processing.
The laser transmitter 102 is configured to generate a laser beam according to a control laser generation instruction sent by the controller 101 and transmit the laser beam to the beam splitter 103. The laser transmitter 102 is embodied as an infrared laser.
The beam splitter 103 is configured to split the received laser beam into a first laser beam and a second laser beam according to the control laser emission instruction, emit the first laser beam to the wafer to be aligned to etch a front alignment mark at a first preset position on the front side of the wafer, and emit the second laser beam to the wafer to etch a back alignment mark at a second preset position on the back side of the wafer.
Referring to fig. 5 of example 3, the most common shape of the beam splitter 103 is a cube made of two triangular glass prisms glued together on a substrate using a polyester, epoxy or polyurethane type adhesive. The thickness of the resin layer is adjusted so that half (a certain wavelength) of the light incident through one "port" (i.e. the face of the cube) is reflected and the other half is transmitted further due to total internal reflection.
The first preset position and the second preset position have a preset relative position relation. The positions of the front alignment mark and the back alignment mark on the horizontal plane may be the same or different. The first preset position and the second preset position can be set according to actual conditions.
The beam splitter 103 is specifically configured to control a duration of emitting the first laser beam and a duration of emitting the second laser beam respectively so that an etching depth of the front alignment mark is different from an etching depth of the back alignment mark. Specifically, the time length for emitting the first laser beam and the time length for emitting the second laser beam are controlled according to the medium etching rate. Etching the given dielectric layer by using a set laser beam, wherein the change of the film thickness per minute is the dielectric etching rate, and the dielectric etching rate of the given dielectric layer can be measured in advance.
Specifically, the beam splitter 103 is specifically configured to split the received laser beam into a first laser beam and a second laser beam, and to emit the first laser beam to the first focusing mirror 104 and the second laser beam to the first reflecting mirror 106.
The first focusing mirror 104 is used to focus the first laser beam at a first predetermined position on the front surface of the wafer to etch the front surface alignment mark.
The first mirror 106 is used for reflecting the second laser beam to the second mirror 107 to adjust the direction of the second laser beam.
The second mirror 107 is used for reflecting the second laser beam to the second focusing mirror 105 to adjust the direction of the second laser beam.
The second focusing mirror 105 is used to focus the second laser beam at a second predetermined location on the backside of the wafer to etch the backside alignment mark.
The first focusing mirror 104 and the second focusing mirror 105 are disposed oppositely based on the holding portion 108.
The clamping portion 108 is used for clamping the edge of a wafer to suspend the etching areas of the front and back surfaces of the wafer.
The photoetching machine provided by the embodiment respectively etches the front alignment mark and the back alignment mark through the first laser beam and the second laser beam which are separated from the same laser beam, and the first preset position and the second preset position which respectively correspond to the front alignment mark and the back alignment mark are in the same wafer coordinate system, so that the etched front alignment mark and the etched back alignment mark are in the same wafer coordinate system, operation steps are reduced, the corresponding relation of calculating a plurality of coordinate systems is reduced, the alignment efficiency and the alignment accuracy are improved, and the calculation accuracy is improved.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.

Claims (12)

1. A wafer back alignment method is characterized by comprising the following steps:
providing a wafer;
emitting a first laser beam to the wafer to etch a front alignment mark at a first preset position on the front of the wafer, and emitting a second laser beam to the wafer to etch a back alignment mark at a second preset position on the back of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system;
the front side alignment mark is set as a front side reference for wafer processing, and the back side alignment mark is set as a back side reference for wafer processing.
2. The wafer backside alignment method of claim 1, wherein before the step of emitting the first laser beam to the wafer to etch a front side alignment mark at a first predetermined position on the front side of the wafer and emitting the second laser beam to the wafer to etch a back side alignment mark at a second predetermined position on the back side of the wafer, the backside alignment method further comprises:
a laser beam is emitted to a beam splitter to split the laser beam into a first laser beam and a second laser beam.
3. The wafer backside alignment method of claim 1, wherein in the step of emitting the first laser beam to the wafer to etch a front side alignment mark at a first predetermined position on the front side of the wafer, and emitting the second laser beam to the wafer to etch a back side alignment mark at a second predetermined position on the back side of the wafer,
the first preset position and the second preset position have a preset relative position relation.
4. The wafer backside alignment method of claim 1, wherein in the step of emitting the first laser beam to the wafer to etch a front side alignment mark at a first predetermined position on the front side of the wafer, and emitting the second laser beam to the wafer to etch a back side alignment mark at a second predetermined position on the back side of the wafer,
and respectively controlling the time length for emitting the first laser beam and the time length for emitting the second laser beam so as to enable the etching depth of the front alignment mark to be different from the etching depth of the back alignment mark.
5. The method of claim 4, wherein the wafer is processed by a wafer back side alignment method,
and controlling the time length for emitting the first laser beam and the time length for emitting the second laser beam according to the medium etching rate.
6. The method of claim 1, wherein the step of providing a wafer comprises:
and clamping the edge of a wafer to suspend the etching areas of the front surface and the back surface of the wafer.
7. The method of claim 1, wherein prior to the step of providing a wafer, the method comprises:
and respectively receiving the first laser beam and the second laser beam by two photoreceptors arranged at a preset position to calibrate the position of the laser beam, wherein the distance between the first laser beam and the second laser beam at the preset position is controlled within a preset position distance threshold value.
8. A wafer back alignment apparatus, comprising: a controller;
the controller is used for outputting a laser emission control instruction to emit a first laser beam to a wafer to be aligned so as to etch a front alignment mark at a first preset position on the front side of the wafer, and emit a second laser beam to the wafer so as to etch a back alignment mark at a second preset position on the back side of the wafer, wherein the first preset position and the second preset position are in the same wafer coordinate system;
the controller is also configured to set the front alignment marks as front references for wafer processing and to set the back alignment marks as back references for wafer processing.
9. The wafer back side alignment apparatus of claim 8, further comprising: a laser emitter and a beam splitter;
the laser transmitter is used for generating a laser beam according to a control laser generation instruction sent by the controller and transmitting the laser beam to the optical splitter;
the beam splitter is used for splitting the received laser beam into the first laser beam and the second laser beam according to the control laser emission instruction, emitting the first laser beam to a wafer to be aligned so as to etch the front alignment mark at the first preset position on the front side of the wafer, and emitting the second laser beam to the wafer so as to form the back alignment mark at the second preset position on the back side of the wafer.
10. The wafer back side alignment apparatus of claim 9, further comprising: the device comprises a first focusing mirror, a second focusing mirror, a first reflecting mirror and a second reflecting mirror;
the beam splitter is specifically configured to emit the first laser beam to the first focusing mirror, and emit the second laser beam to the first reflecting mirror;
the first focusing lens is used for enabling the first laser beam to form a focus at the first preset position on the front surface of the wafer so as to etch the front surface alignment mark;
the first mirror is used for reflecting the second laser beam to the second mirror so as to adjust the direction of the second laser beam;
the second reflector is used for reflecting the second laser beam to the second focusing mirror so as to adjust the direction of the second laser beam;
the second focusing mirror is used for enabling the second laser beam to form a focus at the second preset position on the back surface of the wafer so as to etch the back surface alignment mark.
11. The wafer back side alignment apparatus of claim 10, further comprising: a clamping portion;
the first focusing lens and the second focusing lens are oppositely arranged based on the clamping part;
the clamping part is used for clamping the edge of a wafer so as to suspend the etching areas of the front surface and the back surface of the wafer.
12. Lithography machine, characterized in that it comprises a back-side alignment device for wafers according to any one of claims 8 to 11.
CN202110395085.8A 2021-04-13 2021-04-13 Wafer back alignment method, wafer back alignment equipment and photoetching machine Pending CN113031410A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109270807A (en) * 2018-12-06 2019-01-25 复旦大学 A kind of dual sided tag laser explosure equipment
CN209297103U (en) * 2019-01-25 2019-08-23 中山新诺科技股份有限公司 Digitize dual surface lithography or exposure system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109270807A (en) * 2018-12-06 2019-01-25 复旦大学 A kind of dual sided tag laser explosure equipment
CN209297103U (en) * 2019-01-25 2019-08-23 中山新诺科技股份有限公司 Digitize dual surface lithography or exposure system

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