CN105988297B - Measuring system and measurement method - Google Patents
Measuring system and measurement method Download PDFInfo
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- CN105988297B CN105988297B CN201510046870.7A CN201510046870A CN105988297B CN 105988297 B CN105988297 B CN 105988297B CN 201510046870 A CN201510046870 A CN 201510046870A CN 105988297 B CN105988297 B CN 105988297B
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Abstract
The present invention provides a kind of measuring system and measurement method, and for measuring the aerial image of mask in the substrate, wherein measuring system includes: lighting unit, and for providing illumination light, illumination light forms initial light after mask；Imaging unit forms imaging for initial light to be imaged；Beam splitting unit, for imaging to be divided into projected light and reference light；Projected light forms the first reflected light for forming the image of mask in substrate, and through substrate reflection；Reflector element forms the second reflected light for receiving reference light；Second reflected light forms interference light after first reflected light interferes；Measuring unit is formed by aerial image for measuring interference light.The present invention utilizes principle of optical interference, by the interference imaging of the first reflected light and the second reflected light, the duplicate figure of actual graphical in copper base is formed, the precision of measurement is improved, photoresist developing is avoided, time and the cost of photoetching process research and development are saved.
Description
Technical field
The present invention relates to semiconductor field, in particular to a kind of measuring system and measurement method.
Background technique
With the development of semiconductor field technology, the critical size (Critical Dimension, CD) of semiconductor devices
Smaller and smaller, the integrated level of chip is also higher and higher, proposes more stringent requirement to semiconductor fabrication process, therefore must
The error of each step must be reduced as far as possible in technical process, component failure caused by reducing because of error.
In semiconductor fabrication, photoetching process is as core technology in occupation of critical positions.In the CMOS work of standard
In skill, needs to use tens of lithography steps, influenced by the factors such as litho machine resolution ratio and the accuracy of alignment, light
There are errors for carving technology.
In a lithographic process, mainly pass through scanning electron microscope (Scanning Electron Microscope, SEM)
To measure using photoresist or other film layers as the pattern that mask is performed etching to substrate and is formed.In scanning electron microscope, electricity
The Electron Beam Focusing that sub- rifle is launched is on patterned surfaces, and reciprocation occurs for high-power electron beam and pattern substance, by production
Secondary electron on pattern is born in collect, on the grid for being sent to kinescope after amplification, formed one can observe that it is various
Characteristic image.
But in existing photoetching process, using the method for scanning electron microscope imaging measurement mask pattern, there is efficiency
Not high problem.
Summary of the invention
Problems solved by the invention is to propose a kind of measuring system and measurement method, saves the time of photoetching process research and development
And cost.
To solve the above problems, the present invention provides a kind of measuring system, for measuring the aerial image of mask in the substrate, institute
Stating measuring system includes:
Lighting unit, for providing illumination light, the illumination light forms initial light after mask；
Imaging unit forms imaging for the initial light to be imaged；
Beam splitting unit, for the imaging to be divided into projected light and reference light；The projected light be projected to substrate and
The image of the mask is formed in substrate；The substrate is used to that the projected light to be made to reflect to form the first reflected light, and will be described
First reflected light projects are to the beam splitting unit；
Reflector element forms the second reflected light for receiving the reference light, and by second reflected light projects to institute
State beam splitting unit；Second reflected light and first reflected light form interference light after interfering；
Measuring unit is formed by aerial image for measuring the interference light.
Optionally, the measuring system further include: the first pipe lens, for assembling the initial light, the imaging unit
It is imaged for the initial light after being assembled to the first pipe lens.
Optionally, the measuring system further include: the first beam-splitting board, for described initial after assembling the first pipe lens
Light reflexes to the imaging unit, is also used to the interference light being transmitted through the measuring unit.
Optionally, the beam splitting unit includes: the second beam-splitting board, for making second reflection formed through reflector element
Light reflexes to the measuring unit, is also used to first reflected light that substrate is formed being transmitted through the measuring unit.
Optionally, the reflector element includes plane mirror, and the plane mirror is arranged in parallel with second beam-splitting board.
Optionally, the measuring system further include: compensating unit is used between the beam splitting unit and the substrate
To compensate the aberration formed during beam splitting.
Optionally, the measuring system further include: diaphragm is set in the first reflected light optical path, for blocking stray light.
Optionally, the lighting unit includes laser light source, and the laser light source is identical as photo-etching machine exposal for generating
The light of wavelength.
Optionally, the lighting unit further includes lighting device, and the lighting device is for generating the laser light source
Directional light formed different angle be incident on the illumination light on mask.
Optionally, the lighting device is partial coherence illumination, ring illumination, dipole illumination or quadrupole illuminating.
Optionally, the imaging unit includes micro- lens head.
Optionally, the measuring unit includes: the second pipe lens, for assembling the interference light；Imaging sensor is used for
It acquires the interference light after the second pipe lens are assembled and is formed by aerial image.
Optionally, the measuring unit further include: fast between the second pipe lens and described image sensor
Door, for controlling the light exposure of the interference light projection on the image sensor.
Optionally, described image sensor is charge coupled array or complementary MOS light sensing
Device array.
Optionally, the measuring system further includes objective table, and for placing substrate, the objective table is mobile platform.
Correspondingly, the present invention also provides a kind of measurement method, for measuring the aerial image of mask in the substrate, comprising:
Illumination light is provided, the illumination light forms initial light by mask；
The initial light is imaged, imaging is formed；
The imaging is divided into projected light and reference light；
The projected light is transmitted through substrate, and the image of the mask is formed in substrate, and the projected light is through the base
Piece reflects to form the first reflected light；
The reference light is reflected, the second reflected light is formed；
Second reflected light and the first reflection combiner interfere, and form interference light；
Measure the aerial image that the interference light is formed.
Optionally, after the step of forming the initial light, the step of imaging forms imaging is carried out to the initial light
Later, the measurement method further includes assembling the initial light to be imaged.
Optionally, it after the step of imaging is divided into projected light and reference light, is projected in the projected light
Before the step of substrate, the measurement method further includes carrying out aberration compensation to the projected light, to remove in beam splitting
Generated aberration in journey.
Optionally, after the step of forming first reflected light, first reflected light and second reflection are photosynthetic
Before the step of beam interferes, the measurement method further include: the stray light in removal first reflected light.
Optionally, the step of offer illumination light includes that the illumination light has phase with the light that photo-etching machine exposal uses
Co-wavelength.
Compared with prior art, technical solution of the present invention has the advantage that
The present invention makes to be divided into two parts by the initial light of mask by beam splitting unit, and a part projects on substrate,
The image of the mask is formed in substrate, and forms the first reflected light through substrate reflection, is projected to beam splitting unit；Another part is made
For reference light, the second reflected light is reflected to form through reflector element, beam splitting unit of turning back back.First reflected light and described second
Reflected light closes beam in beam splitting unit, interferes, and through measuring unit imaging, measurement, it is complete can to measure actual graphical in same substrate
Complete the same figure, improves the precision of measurement, avoids photoresist developing, saves the time of photoetching process research and development
And cost.
The present invention can be used for measuring the mask for generally exposing and using, and can be used for measurement and covers for the small-sized of research and development
Mould, it might even be possible to for researching and developing the liquid crystal filter for carrying out figure line and being changed to, it is high-precision that production can be saved during research and development
The expense for spending mask, reduces research and development cost.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of one embodiment of measuring system provided by the present invention；
Fig. 2 is the illumination path figure of measuring system shown in Fig. 1；
Fig. 3 is imaging and the optical path figure of measuring system shown in Fig. 1；
Fig. 4 is the index path between measuring system imaging unit shown in Fig. 1, reflector element, beam splitting unit and substrate；
Fig. 5 is the flow chart of one embodiment of measurement method provided by the present invention.
Specific embodiment
It can be seen from background technology that in the prior art, to obtain real space picture of a certain patterned mask in silicon wafer needs
This mask is exposed on given silicon wafer, and the picture in photoresist is recorded using scanning electron microscope.Just
As traditional camera, need then to be recorded with scanner or projecting camera again first by image recording on film.
And present AIMS (Aerial Image Measurement System) is although can carry out given mask
Electronic imaging.But such imaging can not be carried out in actual silicon on piece.Especially when grown above silicon has multilayer film or silicon
When on piece is already formed with some figures by high and low, multilayer film and figure by high and low can be such that incident light scatters,
The imaging of mask graph aerial image is impacted, makes mask graph aerial image that figure deformation or even pattern lacks occur.It is this
Influence is that present technology is inevitable.
To solve the technical problem, the present invention provides a kind of measuring system, comprising:
Lighting unit, for providing illumination light, the illumination light forms initial light after mask；Imaging unit is used for
The initial light is imaged, imaging is formed；Beam splitting unit, for the imaging to be divided into projected light and reference light；
The projected light is projected to substrate and forms the image of the mask in substrate；The substrate is for reflecting the projected light
Form the first reflected light, and by first reflected light projects to the beam splitting unit；Reflector element, for receiving the reference
Light forms the second reflected light, and by second reflected light projects to the beam splitting unit；Second reflected light and described the
One reflected light forms interference light after interfering；Measuring unit is formed by aerial image for measuring the interference light.
The present invention is based on principle of optical interference, so that part is projected to substrate by the initial light of mask by divided beam system,
Mask images are formed in substrate, and form the first reflected light by substrate；And another part initial light is without substrate reflection,
The second reflected light is directly reflected to form by reflector element.First reflected light and second reflecting interference imaging, through surveying
Cell imaging, measurement are measured, the duplicate figure of actual graphical in same substrate can be measured, the precision of measurement is improved, avoid
Development and etc., save time and the cost of photoetching process research and development.
To make the above purposes, features and advantages of the invention more obvious and understandable, with reference to the accompanying drawing to the present invention
Specific embodiment be described in detail.
Fig. 1 is the structural schematic diagram of one embodiment of measuring system provided by the present invention.
It should be noted that in the present embodiment, the measuring system measurement is the mask 1 formed in the silicon wafer 2
Aerial image.In other embodiments, mask can also be measured and be formed by aerial image on other substrates except silicon wafer.
It is the illumination path figure of measuring system shown in FIG. 1, the measuring system packet in conjunction with reference Fig. 2, Fig. 2 with reference to Fig. 1
It includes:
Lighting unit 10, for providing illumination light 100, the illumination light 100 forms initial light 200 after mask 1.
Specifically, the illumination light 100 that the lighting unit 10 provides is incident on from different perspectives on mask 1, therefore, pass through
The initial light 200 formed after mask 1 includes the image on mask 1.
It should be noted that the lighting unit 10 includes laser light source 11 and lighting device 12 in the present embodiment.
Specifically, what that is, described laser light source 11 exported swashs using photo-etching machine exposal light source as the laser light source 11
Light 101 is identical as the optical maser wavelength that photo-etching machine exposal uses.Therefore it under identical lighting condition, is measured in subsequent measuring unit
Aerial image and actual exposure on a photoresist, it is identical for obtaining the image of mask 1.
It should be noted that using photo-etching machine exposal light source as the light source in lighting unit of the present invention in the present embodiment,
An only example, the present invention with no restrictions, can choose other light sources to the selection of light source.
The lighting device 12 makes laser 101 form the illumination light 100 that different angle is incident on mask.The present embodiment
In, the lighting device 12 is one group of lens, scatters laser 101, forms illumination light 100, is incident on mask 1 from different perspectives
On.
It should be noted that the lighting device 12 can use Kohler illumination principle, provide such as partial coherence illumination,
Ring illumination and dipole illumination or quadrupole illuminating, the present invention to the selection of lighting device 12 with no restrictions.
It continues to refer to figure 1, in conjunction with reference Fig. 2, the measuring system further includes imaging unit 20, and the imaging unit 20 is used
It is imaged in the initial light 200, forms imaging 400.
It should be noted that in the present embodiment, between the imaging unit 20 and the mask 1, the measuring system
It further include the first pipe lens 61 and the first beam-splitting board 62.It should be noted that the direction of the first pipe lens axis is first
Optical axis direction A.
Specifically, the first pipe lens 61 can be improved subsequent by imaging unit for assembling the initial light 200
The light intensity of 20 imagings 400 formed is conducive to improve the quality for being subsequently formed aerial image.
First beam-splitting board 62 is reflected for the initial light 200 after assembling the first pipe lens 61, is formed
Incident light 300 is projected to the imaging unit 20.
In the present embodiment, first beam-splitting board 62 includes reflecting surface 621, and the reflecting surface 621 is described first with incidence
Beginning light 200 is in 45 °, and therefore, the incident light 300 and the incident initial light 200 reflected to form through reflecting surface 621 mutually hangs down
Directly, it is projected to the imaging unit 20.That is, the optical axis direction of the imaging unit 20 is the second optical axis direction B, it is described
Second optical axis direction B is mutually perpendicular to the primary optic axis direction A.Since subsequent first beam-splitting board 62 is also used to transmit institute
Interference light is stated to the measuring unit 50, the optical axis of measuring unit 50 is overlapped with the second optical axis direction B, first beam splitting
Plate 62 is arranged between imaging unit 20 and the measuring unit 50, and such light path design can reduce the measuring system
Length.
The imaging unit 20 is used to form imaging 400.In the present embodiment, the imaging unit 20 is used for described the
The incident light 300 of one beam-splitting board 62 reflection is imaged, and forms imaging 400, and the imaging 400 is projected to beam splitting unit 30.Institute
Stating imaging unit 20 includes micro- lens head 21.
It should be noted that including a micro- lens head 21 only example, the present invention in imaging unit 20 in the present embodiment
It is without limitation, in other embodiments of the invention, it can choose other image-forming components and the initial light be imaged, formed
The imaging 400.
It should also be noted that, the imaging region for the aerial image that the measuring system measures is than in practical litho machine photoetching
It is small, therefore the imaging unit 20 can use the design of micro- lens head, and it is the same not need similar litho machine imaging lens
Enormousness and cost.
It continues to refer to figure 1, in combination with reference Fig. 2, the measuring system further includes beam splitting unit 30, the beam splitting unit
30 for dividing the imaging 400 for projected light 500 and reference light 600.
In conjunction with reference Fig. 3, described Fig. 3 is imaging and the optical path figure of measuring system shown in Fig. 1.Specifically, the throwing
Shadow light 500 is projected to silicon wafer 2, and the image of the mask 1 is formed in silicon wafer 2.The silicon wafer 2 then projected light
500 reflect to form the first reflected light 700, and first reflected light 700 is reflexed to the beam splitting unit 30.
It should be noted that the measuring system further includes objective table 65, the silicon wafer 2 is located on the objective table 65.
In the present embodiment, the objective table 65 is mobile platform, can have 6 freedom degrees to change the position of silicon wafer 2,6 freedom
Degree is along the translation in the second direction optical axis B, around the rotation of the second optical axis direction B and along perpendicular to the second optical axis direction
The inclination of B.
The beam splitting unit 30 includes the second beam-splitting board 31, and second beam-splitting board 31 is half-reflecting mirror.Make the imaging
Light 400 divides for projected light 500 and reference light 600.Specifically, second beam-splitting board 31 includes reflecting surface 311, the reflecting surface
311 reflect a part of imaging 400, form reference light 600, reflex to the reflector element 40；Second beam splitting
The remaining imaging 400 of plate 31 transmits, and forms projected light 500, is projected on the silicon wafer 2 on the objective table 65, and
The silicon wafer 2 reflects the projected light 500, forms the first reflected light 700, and first reflected light 700 is reflected
The second beam-splitting board 31 in the beam splitting element 30.
It should be noted that using half-reflecting mirror to divide the imaging 400 for projected light and reference light in the present embodiment
Setting be only an example, the present invention is without limitation, it is also an option that other beam splitting devices in other embodiments of the invention
It is that the imaging 400 divides for projected light and reference light.
Also need bright, in the present embodiment, the silicon wafer 2 is the silicon wafer for being formed with photoresist layer.In conjunction with reference Fig. 4,
Fig. 4 shows the index path between measuring system imaging unit shown in Fig. 1 20, beam splitting unit 30, reflector element 40 and silicon wafer 2,
Illumination path and imaging, optical path are denoted in figure.The projected light 500 is projected in the silicon wafer 2, in the silicon wafer
The image of the mask 1 is formed in the photoresist on 2 surfaces.Due to be already formed in silicon wafer 2 multilayer film and it is some by high and low
Figure, multilayer film and figure by high and low can scatter incident projected light 500.
Furthermore it should be noted that the measuring system further includes compensating unit 63, the compensating unit 63 is located at described
Between beam splitting unit 30 and the silicon wafer 2, it is formed by aberration in the process to compensate beam splitting.Specifically, the compensating unit
63 include optical aberration compensating lens, by this present embodiment, during initial light 200 forms projected light 500, and through beam splitting twice,
Aberration generation is had, during beam splitting in order to make the figure in the figure formed in the photoresist and the mask 1 as far as possible
It is close, therefore optical aberration compensating lens are provided in the optical path before the projected light 500 is projected to silicon wafer 2 in the present embodiment,
To compensate the aberration formed during beam splitting.But whether the present invention is to being arranged the compensation lens with no restriction.
It continues to refer to figure 1, in conjunction with referring to figs. 2 and 3, the measuring system further includes reflector element 40, for receiving
Reference light 600 is stated, reference light 600 is made to reflect to form the second reflected light 800.
Specifically, the reflector element 40 includes plane mirror 41, the plane mirror 41 is parallel with second beam-splitting board 31
Setting, and the reflecting surface 311 of the reflecting surface of plane mirror 41 and second beam-splitting board 31 is opposite.The projected light 500 is incident on
After on the reflecting surface 311 of second beam-splitting board 31, a part of projected light 500 reflexes to the plane mirror 41 by reflecting surface 311,
Form reference light 600.The plane mirror 41 reflects the reference light 600, forms the second reflected light 800, and makes described second anti-
Penetrate the second beam-splitting board 31 that light 800 is projected in the beam splitting unit 30.
Second reflected light 800 is projected to second in the beam splitting unit 30 with first reflected light 700
Beam-splitting board 31.Second reflected light 800 is interfered with first reflected light 700, forms interference light 1000.
It should be noted that the actual imaging in the imaging and photoresist of the interference light 1000 be it is duplicate, because
Image for mask 1 described in photoresist is by incident projected light 500 from the top down and scattering light interference shape from bottom to top
At.And the first reflected light 700 for being reflected the projected light 500 by the silicon wafer 2 and being formed, only by photoresist under
Upward scattering light is constituted, without including incident light projected light 500 from the top down.Therefore only the first reflected light 700 at
Picture cannot obtain the full graphics of the mask 1 in photoresist, it may appear that anamorphose even lacks.And second reflection
Light 800 only passes through the reflection of the plane mirror 41 in reflector element 20, is one with the projected light 500 without the reflection of silicon wafer 2
Sample.Therefore second reflected light 800 and first reflected light 700 interfere, with the projection in the silicon wafer 2
Light 500 and the interfering for light of scattering are the same.So the actual imaging in the imaging and photoresist of interference light 1000
It is duplicate.
It should also be noted that, higher image quality in order to obtain, in the present embodiment, in the silicon wafer 2 and described point
Diaphragm 64 is additionally provided between Shu Danyuan 30, to block stray light.
It continues to refer to figure 1, in conjunction with reference Fig. 3, the measuring system further includes measuring unit 50, for measuring the interference
Light 1000 is formed by aerial image.
It should be noted that the silicon wafer 2 reflects the projected light 500, the first reflected light 700 is formed, and will
First reflected light 700 reflexes to the second beam-splitting board 31 in the beam splitting unit 30；The plane mirror 41 reflects the ginseng
Light 600 is examined, forms the second reflected light 800, and second reflected light 800 is made to be projected to second point in the beam splitting unit 30
Beam plate 31.Therefore, second beam-splitting board 31 is also used to that the second reflected light 800 is made to reflex to measuring unit 50, and makes described
First reflected light 700 is also projected to measuring unit 50.
Specifically, the measuring unit 50 includes:
Second pipe lens 51, for assembling the interference light 1000, the measuring unit 50 measures the second pipe lens
Interference light 1000 after convergence is formed by aerial image.It is measured using the aerial image that the interference light 1000 after convergence is formed,
Be conducive to improve the quality of aerial image, improve the precision of measurement and reduce the difficulty of measurement.
Imaging sensor 52 is formed by aerial image for acquiring the interference light 1000 after the second pipe lens 51 are assembled.Tool
Body, described image sensor 52 can be charge coupling component array (Charge Coupled Device, CCD) or mutual
Apotype Metal-oxide-semicondutor sensor array (Complementary Metal Oxide Semiconductor,
CMOS) etc..Specifically, described image sensor 52 is ultraviolet enhancing charge coupling component array in the present embodiment.
It should be noted that being located at the second pipe lens 51 and described image sensor to improve image quality
Between 52, in the present embodiment, it is additionally provided with shutter 53, is incident upon described image sensor 52 for controlling the interference light 1000
On light exposure.
It should also be noted that, the measuring system measures mask 1 and is formed by the silicon wafer 2 in the present embodiment
Aerial image, only an example, in other embodiments of the present invention, the measuring system can also be to measure for the small of research and development
The imaging of type mask, it might even be possible to measure the imaging of the liquid crystal filter of Programming in Digital Image Processing.The present invention to the mask 1 and
The silicon wafer 2 does not do any restrictions.
Explanation is needed further exist for, the measuring system is used to measure imaging of the mask 1 in the silicon wafer 2,
Can be to confirm design rule, can be to confirm the process windows such as contrast, depth of focus possessed by image, it can also be to
Confirm the performance and quality of mask.
To sum up, for the present invention by the method using optical interference imaging, the present invention is based on principle of optical interference, pass through beam splitting
System makes part be projected to substrate by the initial light of mask, mask images is formed in substrate, and form first by substrate
Reflected light；And another part initial light directly reflects to form the second reflected light by reflector element without substrate reflection.Described
One reflected light and second reflecting interference imaging, through measuring unit imaging, measure, can measure actual graphical in same substrate
Duplicate figure improves the precision of measurement, avoid development and etc., save photoetching process research and development time and at
This.
Correspondingly, being used to measure the aerial image of mask in the substrate the present invention also provides a kind of measurement method, feature exists
In including:
Illumination light is provided, the illumination light forms initial light by mask；The initial light is imaged, imaging is formed
Light；The imaging is divided into projected light and reference light；The projected light is transmitted through substrate, and the mask is formed in substrate
Image, the projected light through the substrate reflection formed the first reflected light；The reference light is reflected, the second reflected light is formed；
Second reflected light and the first reflection combiner interfere, and form interference light；Measure the sky that the interference light is formed
Between picture.
It should be noted that this measurement method, to measure aerial image of the mask in silicon wafer, in the present embodiment, institute
It states silicon chip surface and is formed with photoresist etc.
With reference to Fig. 5, the flow chart of one embodiment of measurement method provided by the present invention is shown.
Step S1 provides illumination light, and the illumination light is incident on mask from different perspectives, is formed initially by mask
Light.
Specifically, the illumination light provides light source for measurement method imaging.In the present embodiment, exposed using with litho machine
The same laser of light provides illumination light.Therefore under identical lighting condition, the aerial image that is measured in subsequent measuring unit with
Actual exposure on photoresist, obtained image are identical.Therefore, by scattering, formation illumination light is incident on to be covered the laser
On mould.It include the image of mask by the initial light of mask.
The initial light is imaged in step S2, forms imaging.
It the region measured by the measurement method, can be using micro- lens head to described than small in photoetching
Initial light imaging, does not need litho machine imaging lens the same enormousness and cost.
It should be noted that after the step of forming the initial light, the step of initial light is imaged it
Before, the measurement method further includes assembling the initial light, to improve image quality.
The imaging is divided into projected light and reference light by step S3.Specifically, using semi-transflective reflective in the present embodiment
Mirror is split the imaging, and imaging is made to be divided into projected light and reference light.
Step S4, projected light are imaged in silicon wafer, form the first reflected light；Specifically, the projected light is projected to silicon
Piece, to form the image of the mask in silicon wafer；The silicon wafer reflects the projected light, forms the first reflected light.
In the present embodiment, the half-reflecting mirror makes to project the part imaging, forms projected light, the projection light projection
Onto silicon wafer, the figure of the mask is formed in the photoresist of silicon chip surface.
It should be noted that being already formed with multiple film layers in the silicon wafer in the present embodiment and some height rising and falling
Figure.Multilayer film and figure in silicon wafer can scatter incident projected light.Therefore mask is formed by the photoresist
Figure is that have the scattering light interference of incident from the top down projected light and reflection from bottom to top to be formed.
It should be noted that after the step of imaging is divided into projected light and reference light, in the projected light
Before the step of projecting the silicon wafer, the measurement method further includes being existed to the projected light process aberration compensation with removal
Aberration caused by during beam splitting.In the present embodiment, the aberration is removed using optical aberration compensating lens compensation.
Step S5, non-reflective reference are executed while the projected light is projected to silicon wafer imaging with continued reference to Fig. 5
Form the second reflected light.
Specifically, reflecting the reference light in the present embodiment using plane mirror, forming the second reflected light.
Step S6, described to interfere second reflected light and the first reflection combiner, formation interference light.
It should be noted that forming first reflected light to improve the progress of the quality of subsequent imaging, measurement
After step, first reflected light and described second reflects before the step of combiner interferes, and the measurement method is also
It include: stray light in removal first reflected light.
Second reflected light is merely through two secondary reflections, therefore second reflected light and the projected light that is incident on silicon wafer
It is the same.Therefore the phase for interfering with projected light in photoresist and scattering light of second reflected light and the first reflected light
Mutually interference is the same.So the actual imaging in the imaging and photoresist of the interference light is completely the same.
With continued reference to Fig. 5, after forming interference light, step S7 is executed, interference light is imaged, is measured.
The interference light can be imaged, measured using imaging sensor.Specifically, described image sensor can be with
It is ccd array (Charge Coupled Device, CCD) or CMOS array etc..In the present embodiment, described image sensor
For ultraviolet intensified CCD array.
It should be noted that the interference light is imaged using pipe lens in the present embodiment, to improve into image quality
Amount.And it is provided with speed device, before imaging sensor to control exposure of the interference light on the ccd array
Amount, to further increase image quality.
It should also be noted that, the measurement method measures mask formed aerial image in silicon wafer, only in the present embodiment
For an example, in other embodiments of the present invention, the measurement method can also be to measure the small-sized mask for research and development
Imaging, it might even be possible to which, to measure the imaging of the liquid crystal filter of Programming in Digital Image Processing, the present invention does not do any restrictions to this.
Further, the measurement method, can be to confirm design rule for measuring imaging of the mask in silicon wafer, can
It, can also be to go the performance and quality of people's mask with to confirm the process windows such as contrast, depth of focus possessed by image.
Measurement method provided by the present invention can be, but not limited to realize using above-mentioned measuring system.
To sum up, using optical interference image-forming principle, measurement method provided by the present invention, by the beam splitting to imaging,
It is to make to be divided into two parts by the initial light of mask, a part projects on substrate, the image of the mask is formed in substrate,
And the first reflected light is formed through substrate reflection, and another part directly reflects to form the second reflected light as reference light, and described first
Reflected light and the second reflected light economic cooperation beam interferometer form interference light, to interference light imaging, measurement, can measure real in same substrate
The duplicate figure of border figure, improve the precision of measurement, avoids photoresist developing, saves photoetching process and grind
The time of hair and cost.
Although present disclosure is as above, present invention is not limited to this.Anyone skilled in the art are not departing from this
It in the spirit and scope of invention, can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the range of restriction.
Claims (20)
1. a kind of measuring system, for measuring the aerial image of mask in the substrate, which is characterized in that the measuring system includes:
Lighting unit, for providing illumination light, the illumination light forms initial light after mask；
Imaging unit forms imaging for the initial light to be imaged；
Beam splitting unit, for the imaging to be divided into projected light and reference light；The projected light is projected to substrate and in substrate
The interior image for forming the mask；The substrate is for making the projected light reflect to form the first reflected light, and by described first
Reflected light projects are to the beam splitting unit；
Reflector element forms the second reflected light for receiving the reference light, and by second reflected light projects to described point
Shu Danyuan；Second reflected light and first reflected light form interference light after interfering；
Measuring unit is formed by aerial image for measuring the interference light.
2. measuring system as described in claim 1, which is characterized in that the measuring system further include: the first pipe lens are used for
The initial light is assembled, the initial light after the imaging unit is used to assemble the first pipe lens is imaged.
3. measuring system as claimed in claim 2, which is characterized in that the measuring system further include: the first beam-splitting board is used for
The initial light after assembling the first pipe lens reflexes to the imaging unit, is also used to for the interference light being transmitted through described
Measuring unit.
4. measuring system as described in claim 1, which is characterized in that the beam splitting unit includes: the second beam-splitting board, for making
For second reflected light back formed through reflector element to the measuring unit, be also used to form substrate described first is anti-
Light transmission is penetrated to the measuring unit.
5. measuring system as claimed in claim 4, which is characterized in that the reflector element includes plane mirror, the plane mirror
It is arranged in parallel with second beam-splitting board.
6. measuring system as described in claim 1, which is characterized in that the measuring system further include: compensating unit is located at institute
It states between beam splitting unit and the substrate, to compensate the aberration formed during beam splitting.
7. measuring system as described in claim 1, which is characterized in that the measuring system further include: diaphragm is set to first
In reflected light optical path, for blocking stray light.
8. measuring system as described in claim 1, which is characterized in that the lighting unit includes laser light source, the laser
Light source is used to generate the light with photo-etching machine exposal phase co-wavelength.
9. measuring system as claimed in claim 8, which is characterized in that the lighting unit further includes lighting device, the photograph
The directional light that bright device is used to that the laser light source to be made to generate forms the illumination light being incident on mask with different angle.
10. measuring system as claimed in claim 9, which is characterized in that the lighting device is partial coherence illumination, annular photograph
Bright, dipole illumination or quadrupole illuminating.
11. measuring system as described in claim 1, which is characterized in that the imaging unit includes micro- lens head.
12. measuring system as described in claim 1, which is characterized in that the measuring unit includes:
Second pipe lens, for assembling the interference light；
Imaging sensor is formed by aerial image for acquiring the interference light after the second pipe lens are assembled.
13. measuring system as claimed in claim 12, which is characterized in that the measuring unit further include: be located at described second
Shutter between pipe lens and described image sensor, for controlling the exposure of the interference light projection on the image sensor
Amount.
14. measuring system as claimed in claim 13, which is characterized in that described image sensor be charge coupled array or
Complementary MOS photosensor array.
15. measuring system as described in claim 1, which is characterized in that the measuring system further includes objective table, for placing
Substrate, the objective table are mobile platform.
16. a kind of measurement method, for measuring the aerial image of mask in the substrate characterized by comprising
Illumination light is provided, the illumination light forms initial light by mask；
The initial light is imaged, imaging is formed；
The imaging is divided into projected light and reference light；
The projected light is transmitted through substrate, and the image of the mask is formed in substrate, and the projected light is anti-through the substrate
It penetrates to form the first reflected light；
The reference light is reflected, the second reflected light is formed；
Second reflected light and the first reflection combiner interfere, and form interference light；
Measure the aerial image that the interference light is formed.
17. measurement method as claimed in claim 16, which is characterized in that after the step of forming the initial light, to described
After initial light carries out the step of imaging forms imaging, the measurement method further includes assembling the initial light to be imaged.
18. measurement method as claimed in claim 16, which is characterized in that the imaging is being divided into projected light and reference light
The step of after, before the step of projected light projects the substrate, the measurement method further includes to the projection
Light carries out aberration compensation, to remove generated aberration during beam splitting.
19. measurement method as claimed in claim 16, which is characterized in that after the step of forming first reflected light, institute
It states the first reflected light and described second to reflect before the step of combiner interferes, the measurement method further include: removal institute
State the stray light in the first reflected light.
20. measurement method as claimed in claim 16, which is characterized in that the step of offer illumination light includes the photograph
Mingguang City has phase co-wavelength with the light that photo-etching machine exposal uses.
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| JP7124277B2 (en) * | 2016-12-13 | 2022-08-24 | 東京エレクトロン株式会社 | Optical processing device and substrate processing device |
| CN107367850B (en) * | 2017-05-31 | 2020-08-21 | 京东方科技集团股份有限公司 | Detection device, detection method, liquid crystal dripping equipment and liquid crystal dripping method |
| CN109283796B (en) * | 2017-07-21 | 2021-08-17 | 中芯国际集成电路制造(上海)有限公司 | Photoetching simulation system |
| CN108827188B (en) * | 2018-09-07 | 2020-04-14 | 苏州瑞霏光电科技有限公司 | Three-dimensional profile microscopic measurement method based on maskless photoetching machine |
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| CN101114135A (en) * | 2007-07-24 | 2008-01-30 | 上海微电子装备有限公司 | Aligning system photolithography equipment |
| CN102486623A (en) * | 2010-12-03 | 2012-06-06 | 上海微电子装备有限公司 | Focusing control device and method used for photoetching equipment |
| CN103207532A (en) * | 2013-04-21 | 2013-07-17 | 中国科学院光电技术研究所 | Coaxial focus detection measuring system and measuring method thereof |
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| JP2006278960A (en) * | 2005-03-30 | 2006-10-12 | Canon Inc | Exposure equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101114135A (en) * | 2007-07-24 | 2008-01-30 | 上海微电子装备有限公司 | Aligning system photolithography equipment |
| CN102486623A (en) * | 2010-12-03 | 2012-06-06 | 上海微电子装备有限公司 | Focusing control device and method used for photoetching equipment |
| CN103207532A (en) * | 2013-04-21 | 2013-07-17 | 中国科学院光电技术研究所 | Coaxial focus detection measuring system and measuring method thereof |
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