CN106772923A - Atomatic focusing method and system based on angled slots - Google Patents
Atomatic focusing method and system based on angled slots Download PDFInfo
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- CN106772923A CN106772923A CN201510822396.2A CN201510822396A CN106772923A CN 106772923 A CN106772923 A CN 106772923A CN 201510822396 A CN201510822396 A CN 201510822396A CN 106772923 A CN106772923 A CN 106772923A
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- G02B7/28—Systems for automatic generation of focusing signals
Abstract
The invention discloses a kind of apparatus and method for focusing, the device includes：Lighting unit, it includes light source (101), illuminating lens (102) and illumination slit (103), for providing incident light；Beam splitting unit, for being split to the light received by it；Object lens (107), for being imaged to illumination slit (103) on the surface of object under test (109), and reflex to the beam splitting unit by the imaging of illumination slit (103)；Probe unit, it includes detection slit (113) and detector (114), for receiving the imaging of the illumination slit (103) from the beam splitting unit and recording the confocal signal related to the surface of the object under test (109), wherein, detection slit (113) is respectively relative to respective optical axis and is obliquely installed with identical inclination angle with illumination slit (103), and relative to object lens (107) in confocal position.
Description
Technical field
The invention belongs to Measurement of Semiconductors field, more particularly to there is the detection of pattern wafer to set on surface
Standby Atomatic focusing method and system.
Background technology
In IC chip manufacturing process, finished product rate is to weigh chip manufacturing process
Important indicator.Constantly reduced with integrated circuit critical size and pattern density is continuously increased, its
Technique controlling difficulty is also increased therewith, can may cause device now with ignored defect in the past
Cisco unity malfunction, the critical defect as influence yield rate.Meanwhile, new three-dimension device knot
Structure, such as FinFET, and new semi-conducting material (such as copper-connection, low k and high-k dielectric
Material and metal gate electrode) it is widely used, bring new electrical property defect problem；New
Technological process, such as immersion lithography bring new defect type, including particulate, bubble,
Watermark or bridging (bridge)；Cmp planarization brings new defect etc., and the presence of defect can
Device cisco unity malfunction can be caused, the key factor as influence yield rate.In order to improve work
Skill, improves production yield rate, and it is in technology controlling and process that assessment is detected and analyzed to defect
The necessary and important work of item.
Optical microphotograph imaging device is most commonly used that in testing equipment, it is by record paper pattern
The view data of crystal column surface recognizes device under test by series of process manufacturing process to analyze
Afterwards with the difference of original design index, such as critical size has zero defect and its distributing position.
Band pattern crystal column surface pattern structure be typically periodic, including many repeated arrangements rectangle
Unit, i.e. working cell, working cell are surrounded by horizontal and vertical groove border, internal shape
Into required semiconductor integrated circuit pattern.Crystal column surface diameter generally very it is big (200 or
300mm), and generally the visual field of optical microphotograph is less than 1mm.Therefore will be to whole wafer surface
Carry out micro-imaging, it is necessary to by the way of fractional scanning is recombinated again.Due to currently advanced integrated
The critical size of circuit has been enter into tens nanometer scope, you must use high-resolution (high power
Rate high-NA (NA)) object lens, but its depth of focus is very short, typically only 200-300nm.
In scanning process is detected, it is necessary to ensure that observed region surface is located at the focal plane of object lens always
Or in its focal depth range, clearly view data could be obtained, defocus can cause image blurring.
Cause the factor of defocus a lot, for example, the injustice of crystal column surface, or entirety inclination, especially
It is that wafer is fixed on when on vacuum cup, pull of vacuum can cause crystal column surface deformation, its surface
Cup depth up to tens microns, much larger than depth of focus length.Therefore, in scanning process, from
Dynamic focusing technology is essential.It is a key technology in wafer detection field.
Realize auto-focusing, it is necessary to detect focus situation first, then control motion
Perform defocusing compensation operation.Therefore, the core of Autofocus Technology is position from defocus method.From
Jiao is directive, positive out of focus or negative defocus, i.e. target is proximate to object lens and is also remote from thing
Mirror.Therefore, the position from defocus method that Autofocus Technology is used must be able to and meanwhile detect from
The size and Orientation of Jiao's amount, and the Autofocus Technology being used in wafer detection equipment, it is necessary to
The influence of crystal column surface integrated circuit patterns and material reflectance differences can be overcome.
In order to realize auto-focusing when wafer is detected, following auto-focusing skill can be typically used
Art：
(1) patent US4639587 is disclosed, and is handed over using left and right two-way light source placed off-axis
For one projection grating of illumination, and with another identical grating as detection grating, with a detection
Device alternately receives total light intensity signal of the two-way light beam in left and right through detection grating, by analyze this two
The difference of road signal obtains defocus information, and defocusing compensation is then performed accordingly to realize focusing.By
It is not to detect simultaneously in two-way, is the different shadows for eliminating light source transient fluctuation to two-way result of detection
Ring, increased light source beam splitting branch road and detected in real time with to light source fluctuation.No matter is the method
Implement in structure or in control all very complicated.
(2) patent US7961763B2 is disclosed, and is entered using the linear light source for favouring optical axis
Row projection, its reflection image is divided into two-way, respectively with two test surfaces perpendicular to optical axis linear array
Detector receive, two detectors respectively be located at image plane before and after symmetric position to form difference structure,
Defocus information is obtained by analyzing the difference of two paths of signals, and realizes focusing accordingly.When realization should
, it is necessary to two sets of receiving light paths and detection system during method, its hardware cost is very high.
(3) patent US7142315 is disclosed, for the detection of multiple film layer body structure surface, profit
With the focusing method of angled slots confocal optical path, two angled slots are the method use, respectively
Used as illumination slit and detection slit, it is in confocal position that both are located at the focal plane of object lens.
The bare bones of the method are：First, the film layer of different depth corresponds to and inclines on crystal column surface
Different pixels point on slit image；Second, by analyzing each peak pixel point in slit confocal image
Position obtain the relative depth figure between each film layer.The premise of the method is：Whole wafer
Superficial film must be perpendicular to the optical axis of object lens.And in fact, due to the inclination of wafer, especially
It is the crystal column surface deformation caused by vacuum suction, the premise of the method for making is difficult in practice
Set up.In addition, the difference of the inhomogeneities of slit illumination and each layer pattern reflectivity, especially
Using the inevitable speckle noise of laser lighting institute, slit confocal image peak pixel can be all influenceed
The position of point is detected, therefore the accuracy of its result is difficult to ensure that.
Therefore, need badly it is a kind of do not influenceed by light source light-intensity variation, not by electronic device on wafer
The influence of pattern topology and different material characteristics, and in optical texture more simple focusing side
Method and system.
The content of the invention
The present invention overcomes above-mentioned the deficiencies in the prior art, proposes a kind of based on the confocal light of angled slots
Learn the new position from defocus and Atomatic focusing method and corresponding system of structure.The system architecture is simple,
Easy to control, cost is lower.
One aspect of the present invention discloses the device for focusing, and it includes：Lighting unit, its bag
Include incoherent light source light source (101), illuminating lens (102) and the photograph for providing incident light
Bright slit (103)；Beam splitting unit, for being split to the light received by it；Object lens (107),
For being imaged to illumination slit (103) on the surface of object under test (109),
And the imaging of illumination slit (103) is reflexed into the beam splitting unit；Probe unit,
It includes detection slit (113) and linear array detector (114), for receiving from described point
The illumination slit (103) of Shu Danyuan as and record and the object under test (109)
The related confocal signal in surface, wherein, it is described to detect slit (113) and illumination slit (103)
The vertical plane of respective optical axis is respectively relative to be obliquely installed with identical inclination angle, and institute
Detection slit (113) is stated with the center of illumination slit (103) relative to the object lens
(107) focus is in optical conjugate position.
Another aspect of the present invention proposes a kind of Atomatic focusing method, and it includes：A. to determinand
Measurement point carry out Z axis step-scan, and by detect slit obtain with the measurement point and
The related confocal signal of illumination slit, wherein, the illumination slit is distinguished with the detection slit
Vertical plane relative to respective optical axis is obliquely installed with identical inclination angle；B. it is based on and the survey
The related confocal signal of amount point determines a defocus function related to the measurement point, and to it is described from
The curve of burnt function carries out linear fit；C. based on described in the defocus function pair after linear fit
Determinand is measured
The present invention is a kind of based on the confocal method of angled slots for the detection for having pattern wafer is provided
Atomatic focusing method and system.The method uses angled slots confocal optical path structure, using specific
The signal processing algorithm analysis confocal signal of slit detect the size and Orientation of defocusing amount, then evidence
This real-time control relative motion mechanism performs defocusing compensation, so as to realize auto-focusing.This is automatic
The advantage of focusing method is not receive light source light-intensity variation, wafer pattern topology and different material characteristics
Influence, compared with prior art, device and structure are also relatively easy used by the system embodiment,
Cost is lower, because it only needs to a set of light path receiving and detection system.
Brief description of the drawings
By referring to accompanying drawing and the following detailed description to non-limiting example is read,
Other features, objects and advantages of the invention will become more apparent upon.
Fig. 1 is shown according to the embodiment of the present invention based on the automatic right of the confocal method of angled slots
The Organization Chart of burnt system；
Fig. 2 a are according to the position from defocus principle schematic of the embodiment of the present invention；
Fig. 2 b are according to the defocus function curve diagram of the embodiment of the present invention；And
Fig. 3 is according to the auto-focusing FB(flow block) of the embodiment of the present invention.
In figure, through different diagrams, same or similar reference represents identical or phase
As device (module) or step.
Specific embodiment
Patent of the present invention proposes a kind of new position from defocus and Atomatic focusing method and corresponding system.
The Atomatic focusing method that patent of the present invention is proposed, not only also has shadow not by light source light-intensity variation
Ring, do not influenceed by wafer pattern form and difference in reflectivity, and than special on optical texture
Sharp US4639587 and patent US7961763B2 are simpler.
Fig. 1 shows of autofocus system of the present invention based on the confocal method of angled slots
Embodiment.The hardware of the embodiment constitutes as follows：Lighting part is by light source 101 and illuminating lens
102 compositions, light source 101 is incoherent light source (such as LED).Angled slots confocal imaging light
System is by illumination slit 103, lens 104, beam splitter 105, object lens 107, lens 112
Constituted with detection slit 113.Setting of the lens 104 relative to illumination slit 103 and lens 112
Setting relative to detection slit 113 is identical.Illumination slit 103 and detection slit 113
It is identical, and they are respectively relative to the vertical plane of respective optical axis with identical inclination
Overturning angle is set places (out of plumb), detects the center phase of slit 113 and illumination slit 103
Focus for object lens 107 is in optical conjugate position.Two centers of slit are respectively saturating
In the focus of mirror 104 and lens 112, thus the focus with object lens 107 constitutes confocal relation.
It is to make it through the surface to be measured of object lens 107 that the orientation of illumination slit 103 and detection slit 113 is set
On projection with detection scanning direction it is parallel.Detector 114 be linear array detector (CCD or
CMOS), its searching surface also favours optical axis, for receiving being total to through detection slit 113
Burnt optical signal, the electric signal of its output sends computer 115 to, and it is responsible for signal transacting with control.
In autofocus system, dichroic beam splitters 106 are typically a necessary device, because
Auto-focusing light path and detection light path share same object lens 107.The work of dichroic beam splitters 106
With being transmission auto-focusing operation wavelength, and reflection measurement operation wavelength makes two kinds of wavelength separateds,
It does not interfere with each other, wherein, measurement operation wavelength can include one group of different wave length.Auto-focusing and
Detection pair as if patterned wafer 109, it is typically fixed on vacuum cup 110, should
Sucker is arranged on three axle translation stages 111, and the motion of its axle of X-Y-Z tri- is controlled by computer 115
System.
The operation principle of the embodiment is：The light that illuminating lens 102 sends light source 101 is focused on
On illumination slit 103, the light through slit sequentially passes through lens 104, beam splitter 105, two
After to color beam splitter 106 and object lens 107, illumination slit is formed in the near focal point of object lens 107
Once as 108, projection of the picture on the surface of wafer 109 is parallel with the scanning direction of wafer.Should
As being then reflected back object lens 107 by the surface of wafer 109, then sequentially pass through dichroic beam splitters 106,
After beam splitter 105 and lens 112, the secondary picture of illumination slit is formed at detection slit 113,
It forms confocal signal through the part light energy of detection slit 113, by linear array detector 114
Recording, and send computer 115 to carries out signal transacting, calculates size and the side of defocusing amount
To.Then, computer 115 is moved according to the Z axis of defocusing amount data control translation stage 111,
Defocusing compensation operation is performed to realize focusing.Position from defocus is repeated with defocusing compensation, then may be used
Realize the auto-focusing in wafer detection process.Due to detection slit 113 and illumination slit 103
Center and object lens 107 focus constitute confocal relation, therefore, above-mentioned secondary picture completely correspond to
In once as light-intensity test will not be produced to lack.
Fig. 2 a are according to the position from defocus principle schematic of the embodiment of the present invention.
The confocal signal that linear array detector 114 is detected is divided into left and right two parts, if through detection
The optical signal overall strength of AB sections of slit 113 is I1, and the optical signal overall strength through BC sections is
I2, wherein AB=BC, and defocus evaluation function (abbreviation defocus function) is defined, it is as follows：
As shown in Figure 2 a, when the surface of wafer 109 is in Z0 positions (focal planes of object lens 107)
When, illumination slit once as 108 central pixel and the surface of wafer 109 intersect at optical axis Z
On, and the picture point of its left and right sides is located at outside the focal plane of object lens 107, is respectively at positive and negative
Out-of-focus appearance, the defocusing amount size of symmetrical point is identical, but in the opposite direction.The central pixel
Confocal picture point is formed at the center B of detection slit 113 after being reflected by wafer, it is through detection
The confocal signal of slit 113 is most strong, and remaining picture point passes through detection slit 113 after being reflected by wafer
Confocal signal it is weaker, the corresponding confocal signal of the bigger picture point of defocus is weaker.
Because illumination slit is once as 108 or so two-part overall defocusing amounts are equal, its throwing
The wafer area equal length that shadow is covered, so through detection slit 113 after it is reflected
AB sections confocal signal overall strength I1 with through BC sections confocal signal overall strength I2 substantially
It is equal, therefore, the value of defocus function is 0, i.e. F0=0.
When the surface of wafer 109 is in the positive out of focus position of Z1, illumination slit is once as 108
With the intersection point on the surface of wafer 109 shift to right side, i.e. illumination slit once as 108 right side
The overall defocusing amount of picture is divided to diminish, and the overall defocus quantitative change of left-half picture is big.Accordingly,
The secondary picture for illuminating slit becomes through the confocal signal overall strength I1 of detect slit 113 AB sections
Greatly, and through BC sections of confocal signal overall strength I2 diminish, now F1 ＞ 0.
When the surface of wafer 109 is in the negative defocus position of Z2, illumination slit is once as 108
With the intersection point on the surface of wafer 109 shift to left side, i.e. illumination slit once as 108 left side
The overall defocusing amount of picture is divided to diminish, and the overall defocus quantitative change of right half part picture is big.Accordingly,
The secondary picture for illuminating slit becomes through the confocal signal overall strength I1 of detect slit 113 AB sections
It is small, and the confocal signal overall strength I2 for passing through BC section becomes greatly, now F2 ＜ 0.
Therefore, the defocus of object lens 107 can be determined by the light signal strength of AB sections, BC sections
Direction and defocusing amount, and then used for follow-up measurement.
Because I1 and I2 are the overall strengths of two sections of confocal signal or so, and defocus function F is only
Ratio I 1/I2 with both is relevant, so, defocus function F will not by light source light-intensity variation and
The influence of wafer pattern topology and different material characteristics.
It is understood that due to being using the optical signal of two sections of AB, BC in the present embodiment
The difference of intensity carries out defocus evaluation, therefore, AB sections of length can also be not equal to BC sections
Length.
Based on above-mentioned algorithm, Z axis step-scan is performed by controlling translation stage 111, and record
The corresponding confocal signal in different defocus positions, it is bent by just can obtain defocus function after data processing
Line.Fig. 2 b give the defocus Function experiment curve of one embodiment of the present of invention acquisition.
Fig. 2 b acceptances of the bid show corresponding defocus functional value F0 under above-mentioned three kinds of out-of-focus appearances, F1,
Positions of the F2 on curve.Linear zone to defocus function curve carries out linear fit, just can obtain
Obtain the linear relationship between defocusing amount and defocus function.When being detected to wafer, in scanning
During, the confocal signal of angled slots is recorded in real time, and F values are calculated, recycle above-mentioned
Linear relationship just can calculate defocusing amount Z, realize position from defocus.If by computer 115 according to this
Through focus value controls Z axis motion, is operated to realize that wafer was detected by performing defocusing compensation
Auto-focusing in journey.
For the defocus function curve in Fig. 2 b, scope and slope and the slit of its linear zone incline
The size at oblique angle is relevant.Inclination angle is bigger, and its range of linearity is smaller, and slope is bigger, also
It is to say, when inclination angle change is big, focusing range diminishes, and resolution ratio of focusing becomes big.Therefore,
The actual size at slit inclination angle should be selected according to the requirement of system focusing range and focusing resolution ratio
Select.In the present embodiment, slit inclination angle is 15 ° to 25 °.
Fig. 3 is according to the auto-focusing FB(flow block) of the embodiment of the present invention.
The implementation process of the Atomatic focusing method based on the confocal method of angled slots in the present embodiment
Including two stages：First stage is calibration process, i.e., before detection work starts, demarcate
Focusing working curve, i.e. defocus function curve, to obtain defocusing amount and defocus functional relation；
Second stage is focus process, i.e., after detection work starts, defocus function is measured in real time
Value, calculates defocusing amount, and feeds back to Z axis motion execution defocus and mend using calibration formula
Operation is repaid, so as to realize auto-focusing.
First stage：Demarcate focusing working curve
Step 201：Z axis are scanned and record confocal signal
In this step, Z axis step-scan is carried out by computer controls D translation platform, makes crystalline substance
Circular surfaces are progressively transitioned into positive out of focus state from negative out-of-focus appearance, and translation stage does not make X and Y-axis side
To scanning.Synchronously, crystal column surface correspondence under each out-of-focus appearance is recorded using detector
Confocal signal.The confocal signal is related to measurement point and illumination slit, wherein, illuminate narrow
The vertical plane for being respectively relative to respective optical axis with detection slit is stitched to be set with identical inclination overturning angle
Put.
Step 202：Calculate defocus function
In this step, confocal signal is processed, each defocusing amount is calculated using formula (1)
Corresponding defocus function F values, that is, obtain the curve shown in Fig. 2 b.
Step 203：Linear fit is carried out to defocus function
In this step, the range of linearity to defocusing amount-defocus function F value curves is carried out linearly
Fitting, obtains linear fit formula.For example, the plan of the F linear with Z can be obtained
Formula, i.e. F=k*Z+b are closed, wherein, k is the slope of the linearity range of curve in Fig. 2 b, and b is
The intercept of the curve.It is understood that the fitting formula of F is only as an example, not herein
For limiting the form of fitting.
Second stage：Focus process
Step 204：Positioning wafer, and carry out X, Y axis scanning
In this step, wafer is positioned, control D translation platform carries out X, Y axis scanning, with
Perform detection record by imaging.
Step 205：Record confocal signal and calculate defocus function
In this step, confocal signal, and base are recorded in real time during X, Y axis scanning
F values are calculated in formula (1).
Step 206：Defocusing amount is calculated using linear fit formula
In this step, defocusing amount Z is determined based on being fitted the linear relationship that obtains in step 203；
Step 207：According to defocusing amount, defocusing compensation is carried out
In this step, according to defocusing amount Z, control Z axis motion performs defocusing compensation,
Realize focusing in real time.
It is to be capable of achieving based on focusing working curve to one the one of measurement point by step 204-207
Secondary auto-focusing.
Hereafter, autofocus system just can click through repeat step 204-207 to other measurements
Row scanning, to realize the automatic focusing in real time in whole disc scanning process.
It is understood that the focusing working curve staking-out work of first stage is disposable appointing
Business, that is to say, that performed before the first wafer is detected, once obtain required linear pass
System, the task is to accuse to complete.When then being detected to all wafers, it is only necessary to perform
Position from defocus of the two-stage since step 204 and auto-focusing flow.In addition, in Fig. 3
Auto-focusing flow be applicable not only in previous embodiment based on the automatic of the confocal method of angled slots
Focusing system, is also applied for other without prejudice to the autofocus system of present inventive concept.
The present invention can not receive the shadow of light source light-intensity variation and wafer pattern when being focused
Ring, the pattern big for difference in reflectivity is also suitable, and its focal plane is objective angular field region
Average aspect.
Technical scheme is by using angled slots confocal optical path structure, it is only necessary to a set of
Light path is received and detection system just can realize auto-focusing, simplifies the light of automatic focusing mechanism
Line structure and reduce cost.In addition, the present invention additionally uses the analysis confocal signal of slit
Difference determines the size and Orientation of defocusing amount, then real-time control relative motion mechanism performs accordingly
Defocusing compensation.Therefore, the differential analysis method can eliminate light source intensity fluctuation, wafer pattern shape
The influence of shape and difference in reflectivity.
It is obvious to a person skilled in the art that the invention is not restricted to above-mentioned one exemplary embodiment
Details, and without departing from the spirit or essential characteristics of the present invention, can be with it
His concrete form realizes the present invention.Therefore, from the point of view of anyway, embodiment all should be regarded as
It is exemplary, and is nonrestrictive.Additionally, it will be evident that " including " word do not arrange
Except other elements and step, and wording " one " is not excluded for plural number.In device claim
The multiple element of statement can also be realized by an element.The first, the second grade word is used for table
Show title, and be not offered as any specific order.
Claims (10)
1. it is a kind of for focus device, it is characterised in that including：
Lighting unit, it includes saturating for the incoherent light source (101) that provides incident light, illumination
Mirror (102) and illumination slit (103)；
Beam splitting unit, for being split to the light received by it；
Object lens (107), on the surface of object under test (109) to the illumination slit
(103) it is imaged, and the imaging of illumination slit (103) is reflexed to described point
Shu Danyuan；
Probe unit, it includes detection slit (113) and linear array detector (114), is used for
Receive the picture of the illumination slit (103) from the beam splitting unit and record to be measured with described
The related confocal signal in the surface of object (109), wherein, detection slit (113) with
The vertical plane that illumination slit (103) is respectively relative to respective optical axis is inclined with identical
Overturning angle is set, and in detection slit (113) and illumination slit (103)
The heart is in optical conjugate position relative to the focus of the object lens (107).
2. device according to claim 1, it is characterised in that the beam splitting unit includes：
First beam splitter (105)；
Second beam splitter (106), it is dichroic beam splitters and is arranged on first beam splitting
Between device and the object lens (107), for transmission focusing operation wavelength and reflection measurement work
Wavelength, measurement operation wavelength can include one group of different wave length, so as to by two kinds of wavelength separateds.
3. device according to claim 1, it is characterised in that also include：
Signal processing unit (115), it is used to locate linear array probe unit (114) described in reason
The confocal signal of record, and then determine the size and Orientation of defocusing amount.
4. device according to claim 1, it is characterised in that the illumination slit (103)
Swept with detection with projection of detection slit (113) through object lens (107) on surface to be measured
Retouch direction parallel, and illumination slit (103) and detection slit (113) are relative
Optics confocal arrangement is formed in the object lens (107).
5. device according to claim 3, it is characterised in that the signal processing unit
(115) following operation is performed：
I. the survey is determined based on the confocal signal related to the surface of the object under test (109)
The defocus function of point is measured, and linear fit is carried out to the defocus function curve；
Ii. surveyed based on object under test (109) described in the defocus function pair after linear fit
Amount.
6. device according to claim 1, it is characterised in that the inclination angle is in 15 °
Into 25 ° of scopes.
7. a kind of Atomatic focusing method, it is characterised in that including：
A. the measurement point to determinand carries out Z axis step-scan, and is obtained and institute by detecting slit
State measurement point and the related confocal signal of illumination slit, wherein, the illumination slit with it is described
The vertical plane that detection slit is respectively relative to respective optical axis is obliquely installed with identical inclination angle；
B. based on the confocal signal related to the measurement point determine with measurement point correlation from
Burnt function, and curve to the defocus function carries out linear fit；
C. measured based on determinand described in the defocus function pair after linear fit.
8. method according to claim 7, it is characterised in that
When carrying out Z axis step-scan to the measurement point, make the measurement point from negative out-of-focus appearance
Positive out of focus state is progressively transitioned into, and the confocal signal includes being associated with the measurement point
Defocusing amount and Z axis position corresponding with the defocusing amount.
9. method according to claim 7, it is characterised in that the confocal signal is divided
Into two parts, defocus functional value is determined using below equation：
Wherein, I1 is the light signal strength of the Part I through the detection slit, and 12 are
Cross the light signal strength of the Part II of the detection slit.
10. method according to claim 7, it is characterised in that the inclination angle is in
In 15 ° to 25 ° of scope.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107656364A (en) * | 2017-11-16 | 2018-02-02 | 宁波舜宇仪器有限公司 | A kind of micro imaging system and its real-time focusing method |
| CN108254853A (en) * | 2018-01-17 | 2018-07-06 | 宁波舜宇仪器有限公司 | A kind of micro imaging system and its real-time focusing method |
| CN109506570A (en) * | 2017-09-14 | 2019-03-22 | 横河电机株式会社 | Displacement sensor |
| CN111381355A (en) * | 2018-12-29 | 2020-07-07 | 南京培轩雅谱光电科技有限公司 | Optical imaging apparatus and method |
| JP2021006903A (en) * | 2019-06-27 | 2021-01-21 | カール・ツァイス・エスエムティー・ゲーエムベーハー | Device for measuring microlithography masks and autofocusing method |
| US11356594B1 (en) | 2019-08-29 | 2022-06-07 | Kla Corporation | Tilted slit confocal system configured for automated focus detection and tracking |
| CN116045841A (en) * | 2022-11-23 | 2023-05-02 | 深圳市中图仪器股份有限公司 | Fitting method, fitting device and measuring system of focusing curve |
| CN116540393A (en) * | 2023-07-07 | 2023-08-04 | 睿励科学仪器（上海）有限公司 | Automatic focusing system and method, semiconductor defect detection system and method |
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