TW202246729A - Three-motors configuration for adjusting wafer tilt and focus - Google Patents

Abstract

A system includes a first interferometer to measure the shape of a first side of a semiconductor wafer, a pallet to hold the semiconductor wafer and expose the first side of the semiconductor wafer to the first interferometer, and three motors coupled to the pallet. The three motors include a first motor coupled to the pallet at a first position, a second motor coupled to the pallet at a second position, and a third motor coupled to the pallet at a third position.

Description

Three-motor configuration for wafer tilt and focus adjustment

The present invention relates to adjusting wafer tilt and focus in a wafer metrology tool.

Semiconductor manufacturing involves depositing layers on a semiconductor wafer and patterning the layers. This deposition stresses the wafer causing warping of the wafer. As the number of layers increases, warpage increases. For modern three-dimensional (3D) semiconductor memories, which can have more than 100 layers, warpage can range from 500 microns to 1 mm or more. Interferometry can be used to measure this warpage. However, for high warpage, the interferometer may not be able to focus over the entire wafer. Even if the wafer is tilted to allow separate measurement of the shape of the wafer in different regions, measuring the shape of the entire wafer may not be feasible.

Therefore, systems and methods are needed to allow efficient measurement of the shape of semiconductor wafers.

In some embodiments, a system includes: a first interferometer for measuring the shape of a first side of a semiconductor wafer; a tray for holding the semiconductor wafer and placing the semiconductor wafer the first side exposed to the first interferometer; and three motors coupled to the tray. The three motors include a first motor coupled to the tray at a first location, a second motor coupled to the tray at a second location, and a third motor coupled to the tray at a third location.

The system can further include a second interferometer for measuring the shape of a second side of the semiconductor wafer, and the tray can have a hole. The tray holds the semiconductor wafer between the first interferometer and the second interferometer.

In some embodiments, a method includes holding a semiconductor wafer in a tray between a first interferometer and a second interferometer. A first side of the semiconductor wafer is exposed to the first interferometer, and a second side of the semiconductor wafer is exposed to the second interferometer. A first motor is coupled to the tray at a first position, a second motor is coupled to the tray at a second position, and a third motor is coupled to the tray at a third position. The method also includes translating the first motor and the second motor so that a tilt of the semiconductor wafer is zero, and if the tilt of the semiconductor wafer is zero, causing the semiconductor wafer to rotate on the first The interferometer is centered with the second interferometer. Centering the semiconductor wafer includes translating the first motor, the second motor, and the third motor.

The method may further include calculating a plurality of tilts for measuring the shape of the semiconductor wafer in a plurality of respective regions after centering the semiconductor wafer between the first interferometer and the second interferometer. For the plurality of tilts, a plurality of sets of target positions for the first motor, the second motor, and the third motor are calculated. Each set of target positions of the plurality of sets of target positions corresponds to a respective one of the plurality of tilts. Translating the first motor, the second motor, and the third motor to each set of target positions of the plurality of sets of target positions to continuously position the semiconductor wafer with each of the plurality of tilts. The shape of the semiconductor wafer is measured in each respective area of the plurality of respective areas with the semiconductor wafer positioned consecutively with each of the plurality of inclinations.

In some embodiments, a system includes: a first interferometer; a second interferometer; a tray for holding a semiconductor wafer between the first interferometer and the second interferometer, wherein a first side of the semiconductor wafer exposed to the first interferometer and a second side of the semiconductor wafer exposed to the second interferometer; and three motors coupled to the tray. The three motors include a first motor coupled to the tray at a first location, a second motor coupled to the tray at a second location, and a third motor coupled to the tray at a third location. The system also includes one or more processors and memory storing one or more programs for execution by the one or more processors. The one or more programs include instructions for performing the methods described above.

In some embodiments, a non-transitory computer readable storage medium stores one or more programs for execution by one or more processors of an interferometric system. The one or more programs include instructions for performing the methods described above.

Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments described. It will be apparent, however, to one of ordinary skill that the various embodiments described may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments.

FIG. 1 shows an interferometric metrology system 100 for measuring the shape of a semiconductor wafer 102 according to some embodiments. Interferometry system 100 may be located in a wafer metrology tool (eg, semiconductor wafer metrology tool 730 , FIG. 7 ). The semiconductor wafer 102 may be a patterned wafer on which layers of films have been deposited and patterned (eg, patterning thereof and thus wafer fabrication has been completed or is in progress). For example, the semiconductor wafer 102 may be a three-dimensional (3D) memory wafer (ie, a wafer having a plurality of 3D memory dies) (eg, a 3D flash memory wafer). The semiconductor wafer 102 is held in the interferometry system 100 on a tray 104 . In some embodiments, the tray 104 holds the semiconductor wafer 102 vertically in the interferometric system 100 to minimize the effect of gravity on the warping of the semiconductor wafer 102 .

Interferometry system 100 includes a first interferometer 106-1 for measuring a first side (e.g., top side, or alternatively, bottom side) of semiconductor wafer 102, and a first interferometer 106-1 for measuring A second interferometer 106-2 on a second side (eg, bottom side, or alternatively, top side) of 102. The first side is opposite the second side. In some embodiments, interferometers 106-1 and 106-2 are Fizeau interferometers: first interferometer 106-1 is a first Fizeau interferometer, and second interferometer 106-2 is a Second Fizeau interferometer. Each Fizeau interferometer comprises: a reference plane 108; a lens 110 for focusing a respective laser beam 124-1 or 124-2 onto the reference plane 108 and the semiconductor wafer 102; a beam splitter which for directing the respective laser beam 124-1 or 124-2 to the lens 110 and transmitting the respective laser beam 124-1 or 124-2 reflected by the reference plane 108 and the semiconductor wafer 102; a lens 114 for focusing through the reflected laser beams 124-1 or 124-2 respectively; a digital camera 116 for receiving the reflected laser beams 124-1 or 124-2 focused by the lens 114; and a computer 118 for using Data from the digital video camera 116 is processed. Laser beams 124-1 and 124-2 are generated by a laser 120 and provided to beam splitters 112 of respective interferometers 106-1 and 106-2 via respective optical fibers 122-1 and 122-2.

In each interferometer 106-1 and 106-2, the portion of the respective laser beam 124-1 or 124-2 reflected by the reference plane 108 is in contrast to the portion of the respective laser beam 124-1 or 124-2 reflected by the semiconductor wafer 102 2 to produce an interferogram captured by camera 116. Using interferogram analysis, the distance between a point on the semiconductor wafer 102 and the reference plane 108 is measured, thereby measuring the height of the point. The measured point heights are indicative of the shape of the semiconductor wafer 102 (eg, warpage of the semiconductor wafer 102 due to film deposition). By using two interferometers 106-1 and 106-2, the height and thus the shape of both sides (ie top and bottom sides) of the semiconductor wafer 102 are measured. The cameras 116 of each interferometer 106-1 and 106-2 can have a dedicated computer 118 to process the interferogram data, so that the interferometric measurement system 100 has two computers 118 in total to process the interferogram data. In some embodiments, each camera 116 is a 90 megapixel camera.

2A and 2B show a tray 200 for holding a semiconductor wafer 102 (FIG. 2B) according to some embodiments. Tray 200 may be an example of tray 104 (FIG. 1). In FIG. 2B , tray 200 is shown holding semiconductor wafer 102 , while in FIG. 2A tray 200 is shown without semiconductor wafer 102 . In some embodiments, the tray 200 has a hole 202 (FIG. 2A) (eg, a circular hole) on which the semiconductor wafer 102 can be held to allow the two sides of the semiconductor wafer 102 (ie, the top side and the bottom side) Exposure to respective interferometers (eg, interferometers 106-1 and 106-2, FIG. 1) allows the shape of both sides of the semiconductor wafer 102 to be measured. One side of the semiconductor wafer 102 faces the outside of the tray 200 and is thus exposed to a first interferometer (eg, interferometer 106-1, or alternatively, interferometer 106-2), while the other side of the semiconductor wafer 102 Side through hole 202 is exposed to a second interferometer (eg, interferometer 106-2, or alternatively, interferometer 106-1). In some embodiments, the tray has clamps 218 (eg, three clamps 218 ) for holding the semiconductor wafer 102 . Fixture 218 may use minimal force to avoid or minimize deformation of the shape of semiconductor wafer 102 during measurement.

Three motors (a first motor 204 , a second motor 208 and a third motor 212 ) are coupled to the tray 200 to tilt and translate the tray 200 . The first motor 204 is coupled to the tray 200 in a first position, the second motor 208 is coupled to the tray 200 in a second position, and the third motor 212 is coupled to the tray 200 in a third position. In some embodiments, the first location is along a first side 206 of the tray 200 , the second location is at a first corner 210 of the tray 200 , and the third location is at a second corner 214 of the tray 200 . The first corner 210 and the second corner 214 are at opposite ends of a second side 216 of the tray 200 , which is opposite the first side 206 .

In some embodiments, the first motor 204, the second motor 208, and the third motor 212 can translate in substantially the same direction 220 (eg, the same direction within manufacturing tolerances). For example, first motor 204 , second motor 208 , and third motor 212 may each have a single degree of freedom such that they only move back and forth in direction 220 . Direction 220 may be substantially parallel (eg, within manufacturing tolerances) to optical axis 111 ( FIG. 1 ) of first interferometer 106-1 and/or second interferometer 106-2. Motors (eg, one or both) 204 , 208 , and/or 212 may be used to achieve a desired tilt of tray 200 and thus semiconductor wafer 102 . All three of motors 204, 208, and 212 may be used to (eg, simultaneously) translate the position of tray 200 and semiconductor wafer 102 while maintaining a desired tilt. In some embodiments, motors 204, 208, and 212 have a minimum motion of one of 50 nm with a repeatability of 2 microns. In some embodiments, motors 204, 208, and 212 each have a stroke (ie, maximum possible translation) in the range of +/- 4 to 5 microns. Different ones of the motors 204, 208, and 212 may have different strokes (eg, each within a range of +/- 4 microns to 5 microns).

3A to 3C are cross-sectional side views of the semiconductor wafer 102 , and the warpage of the semiconductor wafer 102 is exaggerated for effect. 3A-3C show respective tilts 300A, 300B, and 300C that may be achieved using tray 200 and motors 204, 208, and/or 212 (FIGS. 2A-2B ), according to some embodiments. 3A shows a zero tilt 300A: the motors 204, 208 and/or 212 have been used to zero the tilt of one of the semiconductor wafers 102 (held by the tray 200), so that a tangent to a central portion of the semiconductor wafer 102 is not tilted (eg, vertical such that semiconductor wafer 102 is oriented vertically). With zero tilt 300A (eg, and a center position between interferometers 106-1 and 106-2), interferometers 106-1 and/or 106-2 (FIG. 1) can focus on semiconductor wafer 102 The shape of a central region 302 of the semiconductor wafer 102 is measured on and thus measured. With zero tilt 300A (and appropriate translational positioning), central region 302 may thus be within the depth of focus of interferometers 106-1 and/or 106-2. However, in the case of tilt 300A, the high warpage of semiconductor wafer 102 prevents interferometers 106 - 1 and/or 106 - 2 from focusing on a top region 304 and a bottom region 306 of semiconductor wafer 102 . With tilt 300A, regions 304 and 306 are thus defocused such that interferometers 106-1 and/or 106-2 cannot measure the shape of regions 304 and 306. That is, in the case of zero tilt 300A, regions 304 and 306 are outside the depth of focus of interferometers 106-1 and/or 106-2.

3B shows a tilt 300B in which motors 204, 208, and/or 212 have been used to tilt semiconductor wafer 102 forward (held by tray 200) to allow interferometers 106-1 and/or 106-2 to focus on area 304 on. Tilt 300B (along with appropriate translational positioning) allows interferometers 106-1 and/or 106-2 to measure the shape of top region 304. With tilt 300B (and appropriate translational positioning), top region 304 is within the depth of focus of interferometers 106-1 and/or 106-2. 3C shows a tilt 300C where the motors 204, 208 and/or 212 have been used to tilt the semiconductor wafer 102 back (held by the tray 200) to allow the interferometers 106-1 and/or 106-2 to focus on the area 306 on. Tilt 300C (along with appropriate translational positioning) allows interferometers 106-1 and/or 106-2 to measure the shape of bottom region 306. With tilt 300C (and appropriate translational positioning), bottom region 306 is within the depth of focus of interferometers 106-1 and/or 106-2.

FIG. 4 shows a simulated example of a wafer map 400 of semiconductor wafer 102 according to some embodiments. Wafer diagram 400 shows a central region 402 and a plurality of regions 404 covering semiconductor wafer 102 together. Each region 404 of the plurality of regions 404 corresponds to a respective tilt (i.e., a non-zero tilt) of the semiconductor wafer 102 (held by the tray 200), which can be achieved using the motors 204, 208, and/or 212 (FIGS. 2B). For example, both of regions 404 correspond to respective slopes 300B and 300C ( FIGS. 3B-3C ), and thus are examples of regions 304 and 306 . Central region 402 corresponds to a zero tilt of semiconductor wafer 102 held by tray 200 (eg, zero tilt 300A, FIG. 3A ), and thus is an example of central region 302 . The shape of semiconductor wafer 102 in each region 404 may be measured by interferometer 106-1 and/or 106-2 (FIG. 1), wherein semiconductor wafer 102 (held by tray 200) is measured using motors 204, 208, and/or 212 Positioned to have respective tilts (and appropriate translational positions) corresponding to regions 404 . The shape of semiconductor wafer 102 in central region 402 may be measured by interferometers 106-1 and/or 106-2 (FIG. 1), where semiconductor wafer 102 (held by tray 200) is measured using motors 204, 208, and/or 212 Positioned to have zero tilt (and proper translational positioning).

For comparison, FIG. 5 shows one of the semiconductor wafers 102 for a version in which the motor 212 ( FIGS. 2A-2B ) is omitted and replaced with a pivot joint so that only two motors can be used to tilt the tray 200. A simulated instance of graph 500 . In this approach, a slope can be achieved for the central region 402 and the respective regions 504 . Interferometers 106-1 and/or 106-2 (FIG. 1) may measure the shape of semiconductor wafer 102 in central region 402 and respective region 504, but not in regions outside respective region 504 and central region 402. . The respective regions 504 and the central region 402 do not jointly cover the semiconductor wafer 102 . Therefore, without the third motor 212 , the interferometer 106 - 1 and/or 106 - 2 ( FIG. 1 ) cannot measure the shape of the entire semiconductor wafer 102 .

FIG. 6A illustrates positioning a semiconductor wafer (eg, semiconductor wafer 102 , FIGS. 1-4 ) in an interferometric metrology system (eg, interferometric system 100 , FIG. 1 ) to prepare for volume, according to some embodiments. A flowchart of a method 600A of measuring the shape (eg, warpage) of a semiconductor wafer. In method 600A, a semiconductor wafer is held (602) in a tray between a first interferometer and a second interferometer. A first side of the semiconductor wafer is exposed to the first interferometer. A second side of the semiconductor wafer is exposed to the second interferometer. A first motor (eg, motor 204, FIGS. 2A-2B ) is coupled to the tray in a first position. A second motor (eg, motor 208, FIGS. 2A-2B ) is coupled to the tray in a second position. A third motor (eg, motor 212, FIGS. 2A-2B ) is coupled to the tray in a third position. In some embodiments, the first interferometer (e.g., interferometer 106-1, FIG. 1 ) is (604) a first Fizeau interferometer, and the second interferometer (e.g., interferometer 106-2, FIG. 1 ) is a second Fizeau interferometer.

The first and second motors are translated ( 606 ) to zero one of the semiconductor wafer tilts (eg, to have a zero tilt 300A, FIG. 3A ). Zeroing the tilt of the semiconductor wafer may involve translating the first motor and the second motor by different amounts to tilt the tray by an amount such that the tilt of the semiconductor wafer is zero.

With one of the semiconductor wafers tilted to zero, the semiconductor wafer is centered between the first interferometer and the second interferometer (608). To center the semiconductor wafer, the first motor, the second motor, and the third motor are translated (eg, all three motors are translated the same distance). In some embodiments, the first motor, the second motor, and the third motor are translated (610) to cause the semiconductor wafer to interfere with the second Fizeau interferometer at one of the first reference planes 108 (FIG. 1) of the first Fizeau interferometer. centered between a second reference plane 108 (FIG. 1) of the instrument while maintaining zero tilt of the semiconductor wafer. Centering the semiconductor wafer brings the semiconductor wafer (eg, a central region 402 of the semiconductor wafer, FIG. 4 ) into focus for both the first and second interferometers.

6B illustrates measuring the shape of a semiconductor wafer (eg, semiconductor wafer 102 , FIGS. 1-4 ) in an interferometric metrology system (eg, interferometric system 100 , FIG. 1 ), according to some embodiments. A flowchart of a method 600B of (eg, warping). Method 600B may be performed as a continuation of one of method 600A.

In method 600B, a calculation ( 612 ) is performed to measure a plurality of tilts (eg, including tilts 300B and 300C ) of the shape of the semiconductor wafer in a plurality of respective regions (eg, plurality of regions 404 and central region 402 , FIG. 4 ). (Figures 3B-3C) along with other tilts). In some embodiments, the plurality of respective regions collectively cover ( 614 ) the entire semiconductor wafer (eg, as shown in FIG. 4 ).

In some embodiments, to calculate the plurality of tilts, a first interferometer or a second interferometer (eg, the first and/or second interferometer of step 602 of method 600A, FIG. 6A ) is used (eg, interferometer 106-1 and/or 106-2, FIG. 1) to measure (616) the shape of a central region of the semiconductor wafer (e.g., central region 302, FIG. 3A; central region 402, FIG. 4) . A wafer map of the semiconductor wafer is predicted (618) using the measured shape of the central region. The wafer map shows a predicted wafer shape (ie, the predicted height of the wafers at their respective locations on the wafer). The wafer map may be predicted assuming that the semiconductor wafer has a specified shape (eg, the shape of the semiconductor wafer is parabolic). For example, the wafer map may be predicted by extrapolating from the shape of the central region based on the assumption that the shape of the entire wafer is as specified (eg, parabolic). A plurality of tilts are determined (620) using the predicted wafer map.

For the plurality of tilts, a plurality of sets of target positions for the first motor, the second motor, and the third motor are calculated (622). Each set of target positions of the plurality of sets of target positions corresponds to a respective one of the plurality of tilts.

Translating (624) the first, second, and third motors (e.g., motors 204, 208, and 212, FIGS. 2A-2B ) to one of the plurality of sets of target positions to position the semiconductor wafer as One of the plurality of slopes is sloped. With the semiconductor wafer positioned to have such a tilt, the shape of the semiconductor wafer is measured (626) in a respective one of the plurality of respective areas. If after measuring the shape of the semiconductor wafer in the respective regions there is any remaining set of target positions where the first motor, the second motor, and the third motor have not been translated to allow measurement of any of the respective regions (628—Yes), then select Next set of target locations (630), and steps 624, 626 and 628 are performed again. If there are no group target locations remaining (628-NO), then method 600B ends (632).

The loop of steps 624, 626, 628, and 630 results in translating the first motor, the second motor, and the third motor to each set of target positions of the plurality of sets of target positions to sequentially position the semiconductor wafer at each of the plurality of tilts. tilt. And in the case where the semiconductor wafer is positioned consecutively with each of the plurality of tilts, the shape of the semiconductor wafer can be measured in each of the plurality of respective areas. Thus, by compiling the shape measurements for each region (ie, for a plurality of respective regions), a complete measure of the shape of the semiconductor wafer can be obtained.

The shape measurement data generated by method 600B can be used for program control. For example, the measured warpage of the semiconductor wafer 102 can be used to feed back process control to identify changes to previous processing steps to reduce warpage or variations in warpage of subsequent processed wafers. In another example, the measured warpage of the semiconductor wafer 102 can be used in feed-forward process control to identify changes to be made to subsequent processing steps to accommodate the measured warpage. The shape measurement data can also be used to dispose of the semiconductor wafer 102 (eg, to determine whether to continue processing, rework, or scrap the semiconductor wafer 102).

FIG. 7 is a block diagram of a semiconductor wafer metrology system 700 according to some embodiments. Semiconductor wafer metrology system 700 has a semiconductor wafer metrology tool 730 that includes one or more (eg, two) interferometers 732 (eg, interferometers 106-1 and 106-2, FIG. 1 ) and a Three-motor tray 734 (eg, tray 200 with motors 204, 208, and 212, FIGS. 2A-2B ).

Semiconductor wafer metrology system 700 also includes a computer system 709 (e.g., a host computer) having one or more processors 702 (e.g., CPUs), optional user interface 706, memory 710, and the The class assembly interconnects one or more communication buses 704 with a semiconductor wafer metrology tool 730 . The user interface 706 may include a display 707 and one or more input devices 708 (eg, a keyboard, mouse, touch-sensitive surface of the display 707, etc.). The display can show results from semiconductor wafer metrology system 700 and their status (eg, status and measurement results of methods 600A and/or 600B, FIGS. 6A-6B ).

Memory 710 includes volatile and/or non-volatile memory. Memory 710 (eg, non-volatile memory within memory 710 ) includes a non-transitory computer-readable storage medium. Memory 710 optionally includes one or more storage devices located remotely from processor 702 and/or a non-transitory computer-readable storage medium removably inserted into computer system 709 . In some embodiments, memory 710 (e.g., the non-transitory computer-readable storage medium of memory 710) stores the following modules and data, or a subset or superset thereof: an operating system 712, which includes Various basic system services and programs for performing hardware-related tasks; a motor control module 714 for controlling the motors of the three-motor tray 734 (eg, for controlling the motors 204, 208, and 212, FIGS. 2A-2B ) (e.g., for translating the motor according to method 600A, FIG. 6A; for performing step 624 of method 600B, FIG. 6B); an illumination module 716 for controlling illumination in interferometer 732 (e.g., for controlling laser 120, FIG. 1); an inclination calculation module 718 (for example, for calculating the zero inclination of step 606 of method 600A, FIG. 6A; for performing step 612 of method 600B, FIG. 6B); a target position calculation module set 720 (eg, for performing step 622 of method 600B, FIG. 6B ), and a wafer metrology module 722 (eg, for performing step 626 of method 600B, FIG. 6B ).

Memory 710 (eg, a non-transitory computer-readable storage medium of memory 710 ) includes instructions for performing all or a portion of methods 600A and/or 600B ( FIGS. 6A-6B ). Each of the modules stored in memory 710 corresponds to a set of instructions for performing one or more functions described herein. Individual modules need not be implemented as individual software programs. Modules and various subsets of modules may be combined or otherwise rearranged. In some embodiments, memory 710 stores a subset or a superset of the modules and/or data structures described above.

FIG. 7 is intended to be a functional description of various features that may exist in the semiconductor wafer metrology system 700 rather than a schematic structural diagram. For example, the functionality of computer system 709 may be divided among multiple devices. All or a portion of the modules stored in memory 710 may alternatively be stored in one or more other computer systems communicatively coupled to semiconductor wafer metrology system 700 via one or more networks.

The foregoing description, for purposes of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the scope of patentable inventions to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen in order to best explain the basic principles of the claimed invention and their practical application, thereby enabling others skilled in the art to best utilize the embodiments with various modifications as are suited to the particular use contemplated.

100:Interferometric measurement system 102: Semiconductor wafer 104: tray 106-1: The first interferometer 106-2: The second interferometer 108: Reference plane 110: lens 111: optical axis 112: beam splitter 114: lens 116: Digital video camera 118: computer 120:Laser 122-1: Optical fiber 122-2: Optical fiber 124-1: Laser Beam 124-2: Laser Beam 200: tray 202: hole 204: The first motor 206: First side 208:Second motor 210: first angle 212: The third motor 214: second angle 216: second side 218: Fixture 220: direction 300A: inclined 300B: Tilt 300C: inclined 302: central area 304: top area 306: Bottom area 400:Wafer map 402: central area 404: area 500:Wafer map 504: area 600A: Method 600B: Method 602: Step 604: Step 606: Step 608: Step 610: Step 612: Step 614:Step 616: Step 618:Step 620: Step 622: Step 624: step 626: step 628:step 630: step 632: end 700:Semiconductor Wafer Measurement System 702: Processor 704: communication bus 706: user interface 707: display 708: input device 709:Computer systems 710: Memory 712: operating system 714:Motor control module 716: Lighting module 718: Tilt calculation module 720: Target position calculation module 722: Wafer measurement module 730:Semiconductor Wafer Measurement Tools 732:Interferometer 734: Three motor tray

For a better understanding of the various embodiments described, reference should be made to the following [Embodiments] in conjunction with the following figures.

FIG. 1 shows an interferometric metrology system for measuring the shape of a semiconductor wafer according to some embodiments.

2A and 2B show a tray for holding a semiconductor wafer according to some embodiments.

3A-3C are cross-sectional side views of a warped semiconductor wafer showing respective tilts that can be achieved using the tray and three motors of FIGS. 2A and 2B , according to some embodiments.

4 shows a simulated example of a wafer map of a semiconductor wafer in which a central region and a plurality of regions collectively cover the semiconductor wafer, according to some embodiments.

5 shows a simulated example of a wafer map of a semiconductor wafer for a scenario in which the third motor of FIGS. 2A and 2B is omitted and replaced with a pivot joint.

6A is a flowchart showing a method of positioning a semiconductor wafer in an interferometric metrology system in preparation for measuring the shape of the semiconductor wafer, according to some embodiments.

6B is a flowchart showing a method of measuring the shape of a semiconductor wafer in an interferometric metrology system, according to some embodiments.

FIG. 7 is a block diagram of a semiconductor wafer metrology system according to some embodiments.

The same reference numerals refer to corresponding parts throughout the drawings and the specification.

102: Semiconductor wafer

200: tray

204: The first motor

206: First side

208:Second motor

210: first corner

212: The third motor

214: second corner

216: second side

218: Fixture

220: direction

Claims (23)

A system comprising: a first interferometer for measuring the shape of a first side of a semiconductor wafer; a tray for holding the semiconductor wafer and exposing the first side of the semiconductor wafer to the first interferometer; and Three motors, which are coupled to the tray, the three motors include a first motor coupled to the tray in a first position, a second motor coupled to the tray in a second position, and a third motor coupled to the tray in a second position. Position coupled to a third motor of the tray. The system of claim 1, wherein: the first location is along a first side of the tray; the second location is at a first corner of the tray; the third location is at a second corner of the tray; and The first corner and the second corner are at opposite ends of a second side of the tray, wherein the second side is opposite the first side. The system of claim 1, wherein the first motor, the second motor and the third motor can translate in substantially the same direction. The system of claim 3, wherein the same direction is substantially parallel to an optical axis of the first interferometer. The system of claim 1, wherein the first interferometer is a Fizeau interferometer. The system of claim 1, further comprising a second interferometer for measuring the shape of a second side of the semiconductor wafer, wherein: the tray has an aperture to expose the second side of the semiconductor wafer to the second interferometer; and The tray is used to hold the semiconductor wafer between the first interferometer and the second interferometer. As the system of claim 6, wherein: the first interferometer is a first Fizeau interferometer; and The second interferometer is a second Fizeau interferometer. The system of claim 7, wherein the first motor, the second motor and the third motor can translate in substantially the same direction. The system of claim 8, wherein the same direction is substantially parallel to the optical axes of the first interferometer and the second interferometer. A method comprising: A semiconductor wafer is held in a tray between a first interferometer and a second interferometer, wherein: a first side of the semiconductor wafer is exposed to the first interferometer, a second side of the semiconductor wafer is exposed to the second interferometer, a first motor coupled to the tray at a first position, a second motor is coupled to the tray at a second position, and a third motor coupled to the tray at a third position; translating the first motor and the second motor to zero a tilt of the semiconductor wafer; and With the tilt of the semiconductor wafer being zero, centering the semiconductor wafer between the first interferometer and the second interferometer includes translating the first motor, the second motor, and the first interferometer Three motors. The method of claim 10, wherein: The first interferometer system includes a first Fizeau interferometer of a first reference plane; the second interferometer is a second Fizeau interferometer comprising a second reference plane; and Centering the semiconductor wafer between the first interferometer and the second interferometer includes translating the first motor, the second motor, and the third motor to align the semiconductor wafer between the first reference plane and the Center between the second reference planes. The method of claim 10, wherein: the first location is along a first side of the tray; the second location is at a first corner of the tray; the third location is at a second corner of the tray; and The first corner and the second corner are at opposite ends of a second side of the tray, wherein the second side is opposite the first side. The method of claim 10, further comprising after centering the semiconductor wafer between the first interferometer and the second interferometer: calculating a plurality of tilts for measuring the shape of the semiconductor wafer in a plurality of respective regions; For the plurality of inclinations, calculating a plurality of sets of target positions of the first motor, the second motor, and the third motor, wherein each set of target positions of the plurality of sets of target positions corresponds to a respective inclination of one of the plurality of inclinations; translating the first motor, the second motor, and the third motor to each set of target positions of the plurality of sets of target positions to sequentially position the semiconductor wafer with each of the plurality of tilts; and With the semiconductor wafer positioned consecutively with each of the plurality of tilts, the shape of the semiconductor wafer is measured in each respective region of the plurality of respective regions. The method of claim 13, wherein the plurality of respective regions collectively cover the entire semiconductor wafer. The method of claim 13, wherein calculating the plurality of tilts comprises: measuring the shape of a central region of the semiconductor wafer using at least one of the first interferometer or the second interferometer; predicting a wafer map of the semiconductor wafer using the measured shape of the central region; and The plurality of tilts are determined using the predicted wafer map. The method of claim 15, wherein predicting the wafer map includes assuming that the semiconductor wafer has a parabolic shape. A system comprising: a first interferometer; a second interferometer; a tray for holding a semiconductor wafer between the first interferometer and the second interferometer, wherein a first side of the semiconductor wafer is exposed to the first interferometer and one of the semiconductor wafers the second side is exposed to the second interferometer; Three motors, which are coupled to the tray, the three motors include a first motor coupled to the tray in a first position, a second motor coupled to the tray in a second position, and a third motor coupled to the tray in a second position. a third motor positionally coupled to the tray; one or more processors; and memory storing one or more programs for execution by the one or more processors, the one or more programs including instructions for: translating the first motor and the second motor to zero a tilt of the semiconductor wafer; and With the tilt of the semiconductor wafer being zero, centering the semiconductor wafer between the first interferometer and the second interferometer includes translating the first motor, the second motor, and the first interferometer Three motors. The system of claim 17, wherein: The first interferometer system includes a first Fizeau interferometer of a first reference plane; the second interferometer is a second Fizeau interferometer comprising a second reference plane; and The instructions for centering the semiconductor wafer between the first interferometer and the second interferometer include translating the first motor, the second motor, and the third motor to center the semiconductor wafer An instruction to center between the first reference plane and the second reference plane. The system of claim 17, wherein: the first location is along a first side of the tray; the second location is at a first corner of the tray; the third location is at a second corner of the tray; and The first corner and the second corner are at opposite ends of a second side of the tray, wherein the second side is opposite the first side. As the system of claim 17, the one or more programs further include instructions executed after centering the semiconductor wafer between the first interferometer and the second interferometer, the instructions for: calculating a plurality of tilts for measuring the shape of the semiconductor wafer in a plurality of respective regions; For the plurality of inclinations, calculating a plurality of sets of target positions of the first motor, the second motor, and the third motor, wherein each set of target positions of the plurality of sets of target positions corresponds to a respective inclination of one of the plurality of inclinations; translating the first motor, the second motor, and the third motor to each set of target positions of the plurality of sets of target positions to sequentially position the semiconductor wafer with each of the plurality of tilts; and With the semiconductor wafer positioned consecutively with each of the plurality of tilts, the shape of the semiconductor wafer is measured in each respective region of the plurality of respective regions. The system of claim 20, wherein the plurality of respective regions collectively cover the entire semiconductor wafer. The system of claim 20, wherein the instructions for calculating the plurality of tilts include instructions for: measuring the shape of a central region of the semiconductor wafer using at least one of the first interferometer or the second interferometer; predicting a wafer map of the semiconductor wafer using the measured shape of the central region; and The plurality of tilts are determined using the predicted wafer map. The system of claim 22, wherein the instructions for predicting the wafer map assume that the semiconductor wafer has a parabolic shape.

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