CN101221371B - Device and method for detecting pattern positioning precision - Google Patents
Device and method for detecting pattern positioning precision Download PDFInfo
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- CN101221371B CN101221371B CN2008100330576A CN200810033057A CN101221371B CN 101221371 B CN101221371 B CN 101221371B CN 2008100330576 A CN2008100330576 A CN 2008100330576A CN 200810033057 A CN200810033057 A CN 200810033057A CN 101221371 B CN101221371 B CN 101221371B
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Abstract
The invention discloses a figure locating precision detecting device and a detecting method thereof, wherein the device comprises a phase shift module, a transmission focusing optical module, a mask stage, a beam-splitting prism, a collimation module, a spectroscope arranged at 45 degrees, an aligning sensor positioned on the first exit surface of the spectroscope, an illuminated light source module and a laser source module which are arranged in turn along a detecting light path; the exit light of the illuminated light source module irradiates the upper surface of a mask plate through the beam-splitting prism; the exit light of the laser source module is split into reference light and transmitted light through a beam-splitting module; the reference light irradiates the beam-splitting prism via a reference light monomode fiber; the transmitted light irradiates the transmission focusing optical module via a transmitted light monomode fiber; the second exit surface of the spectroscope isprovided with an imaging module and an image sensor; in addition, the device also comprises a main controller connected with the parts. The device can measure the accurate change of figure position and reduces the size of an optical detecting element along with high detecting precision and convenient operation.
Description
Technical field
The present invention relates to a kind of figure locating device and using method thereof, particularly be used for the mask figure bearing accuracy pick-up unit and the detection method thereof of litho machine.
Background technology
In the semiconductor lithography field, semiconductor element production generally all needs to carry out multilayer and exposes and realize, different layers all needs mask separately, and requirement has strict alignment precision between the different layers mask, it is a key factor of limits product performance, in order to improve the yield of product, need accurately measure the pattern positioning precision on the mask.
Present mask graph bearing accuracy all is the position by the method computed image center at accurate positioning image edge, principle is by optical microscope and electron microscope hot spot to be focused on a very little point, obtain the position on a limit then by edge detection method, obtain the position on another one limit again by identical method, position by the center of calculating, the IPRO figure locating and detecting device of LEICA company is exactly (the SPIE Vol.4562 that measures by the method for optical microscope, p.237-246 (2002)), this measuring system light path is divided into imaging optical path (imaging optic), the laser light path (laser autofocus) of focusing automatically, image alignment light path (alignment imaging optic) and perspective illumination path.
The shortcoming of said apparatus is: (1) is owing to need differentiate and imaging tiny lines, need to use short wavelength and bigger numerical aperture (NA), the wavelength of LEICA is 360-410nm, and numerical aperture is 0.9 to the maximum, and this brings bigger difficulty to optics processing and manufacturing; (2) when measuring little lines, the operating distance when selecting to use large-numerical aperture is short especially, has only 250um, just can't measure when on the mask diaphragm being arranged like this; (3) in order to make autofocus system, alignment system and imaging system merge in the system and do not influence each other, this system need adopt the wavelength of three kinds of wave bands, imaging system is 360-410nm, autofocus system is 903nm, alignment system is 440-770nm, and this has increased optically coated difficulty; (4) because locating information is common definite by imageing sensor positioning error and mask plate version measuring system location, the framing error on the imageing sensor will influence final error result to a great extent; (5) imageing sensor imaging optical path error also will cause positioning error.
Summary of the invention
Technical matters solved by the invention provides a kind of change in location by the accurate measurement pattern mark of optical interference, simultaneously with optical system for alignment, illumination path and position sensing light path are integrated into pattern positioning precision pick-up unit and the detection method thereof in the same light path, with raising mask images position detection accuracy, thereby satisfy higher alignment requirement.
In order to solve the problems of the technologies described above, the present invention has adopted following technical scheme:
A kind of figure locating and detecting device, the change in location that is used for the measurement pattern mark, described device comprises that described mask platform is used for the mask that carrying tool has described pictorial symbolization along surveying the spectroscope that phase shift module, transmission focusing optical module, mask platform, Amici prism, collimating module, 45 degree that light path is arranged in order are provided with and being positioned at alignment sensor on described spectroscope first exit facet; Described device also comprises: lighting source module, its emergent light through an illumination focus module after, shine the upper surface of mask by described Amici prism; Laser light source module, its emergent light is divided into a branch of reference light and a branch of transmitted light by a spectral module, described reference light is incident to described Amici prism by a reference light single-mode fiber, and described transmitted light focuses on the figure of described mask through described phase shift module and described transmission focusing optical module by a transmitted light single-mode fiber; Also be provided with an image-forming module and an imageing sensor on described spectroscopical second exit facet; Described device also comprises the main control computer that links to each other with above-mentioned each parts.
In above-mentioned figure locating and detecting device, described transmission focusing optical module is fixed on the described phase shift module, and this phase shift module can vertically move.
In above-mentioned figure locating and detecting device, described transmitted light and reference light are the coherent lights from the same emergent light of described laser light source module.
In above-mentioned figure locating and detecting device, described reference light and transmitted light merge by described Amici prism.
In above-mentioned figure locating and detecting device, described mask platform can accurately move in X, Y, Z direction.
In above-mentioned figure locating and detecting device, described main control computer control laser light source module produces laser and regulates light intensity, control lighting source module switch and light intensity, control phase shift module and move, control the image information analysis that mask platform moved and controlled sensor.
Adopting the detection method of figure locating and detecting device of the present invention, is the method for interfering by described transmitted light and reference light, measures the wavefront variation of transmitted light, thereby calculates the position of figure, and described method comprises the following steps:
(1) light intensity is opened and regulated to main control computer control lighting source module, allows illumination light shine figure on the mask;
(2) receive the image information of described figure by imageing sensor;
(3) do the image analysis by imageing sensor and find and to carry out pinpoint figure, and figure is carried out coarse positioning by main control computer control;
(4) close the lighting source module, open laser light source module;
(5) out of focus by alignment sensor analyzed pattern surface and departing from;
(6) shift position of control figure makes it the focal plane and the obliquity that reach best;
(7) main control computer calculates the precise position information of this figure according to the graph position of alignment sensor record.
The present invention makes it compared with prior art owing to adopted above-mentioned technical scheme, has following advantage and good effect:
1, simplifies the optical texture of positioning measurment system, increase the reliability and stability of system;
2, do not need to use short wavelength and bigger numerical aperture, just can realize the accurate localization measurement;
3, bigger operating distance can be arranged, when on the mask diaphragm being arranged, also can carry out high-acruracy survey;
4, illumination and aligning all use visible waveband to measure, and the plated film design of simplified system reduces cost;
5, wavefront information rather than the picture position information that receives perspective figure by imageing sensor positions calculating, the effectively influence of the framing error on the removal of images sensor;
6, transmitted light adopts identical light path with reference light, effectively eliminates colimated light system to affect positioning.
Description of drawings
To the description of the embodiment of the invention, can further understand purpose, specific structural features and the advantage of its invention by following in conjunction with its accompanying drawing.
Fig. 1 is a pattern positioning precision pick-up unit light channel structure synoptic diagram of the present invention.
Embodiment
Pattern positioning precision pick-up unit of the present invention is to utilize optical fiber as the transmission light path, utilize lamp optical system to carry out graphic searching, and the employing common-circuit interference method, obtaining the locating information of image by the perspective figure wavefront information, its concrete structure and working method are as follows:
See also Fig. 1, at first open lighting source module 14 by main control computer 18, the wave band of its outgoing is 400～600nm, after over-illumination focus module 13 focuses on, illumination light is thrown light on mask 16 upper surfaces by Amici prism 12, after being refracted to image-forming module 7 through spectroscope 10 after through Amici prism 12 and collimating module 11, the light of mask 16 upper surfaces reflections reaches imageing sensor (CCD) 6, the catching range of imageing sensor 6 is bigger, the information that the main control computer 18 analysis image sensors 6 that link to each other with imageing sensor 6 capture, can realize the rough measure of graph position, the mobile mask platform 15 of main control computer 18 controls, after finding mask 16 all figures that need position roughly, lighting source module 14 is closed.
Secondly, open laser light source module 1 and rationally regulate light intensity by main control computer 18, this light source is the 650nm laser instrument, laser light source module 1 emitting laser is divided into two bundles by spectral module 2 with laser, a branch of reference light enters in the reference light single-mode fiber 4, another bundle transmitted light is coupled in the transmitted light single-mode fiber 5, focus on the figure on mask 16 surfaces through phase shift module 3 and transmission focusing optical module 17, the spot that transmitted light impinges upon on the mask 16 can not be too big, because once can only measure the position of a figure, when shining other position, can cause crosstalking between the different graphic, cause the figure positioning error, in order effectively to control the size of irradiation spot, transmission focusing optical module 17 is fixed on the vertical phase shift module 3 that can accurately move, phase shift module 3 can realize the accurately adjustable of transmission focusing spot size, to realize the control of different regional transmissions, through before the transmitted wave of mask 16 diffraction and behind the wavefront of the reference optical fiber outgoing process Amici prism 12, shine on the alignment sensor 9 by collimating module 11, before the transmitted wave of mask figure outgoing, interfere simultaneously with reference wavefront, main control computer 18 can obtain the accurate horizontal level and the vertical position information of figure by wavefront analysis, by the alignment sensor analysis obtain patterned surface out of focus and depart from.What imageing sensor 6 obtained is the stripe information of interference strength, just can reduce the wavefront analysis positional information of figure by the phase shift fringe analysis method, the information analysis that 18 pairs of imageing sensors 6 of main control computer and alignment sensor 9 receive obtains the accurate horizontal level and the vertical position information of figure, and judges whether pattern positioning precision reaches requirement.Because the light intensity of optical fiber diffraction is inhomogeneous, the phase shift fringe analysis method is the wavefront analysis error that causes because of the light intensity unevenness of removal of images sensor 6 at utmost, the phase shift fringe analysis method can also effectively reduce imageing sensor 6 ground unrests, influences such as intrinsic electronics and photon noise in addition.
Once more, concrete phase shift fringe analysis method can adopt for three steps, four steps, seven step or more multistep phase shifts, be the analytic process that example is analyzed wavefront information with four step phase shifts below: main control computer 18 allows phase shift module 3 highly carry out stepping at four, the mobile size in per step is a quarter-wave, collect four width of cloth interference images by imageing sensor 6, the image that utilizes these four imageing sensors 6 to gather just can calculate wavefront, relevant with reference to corrugated and tested corrugated, the light distribution of interference field can be expressed as:
I(x，y，t)＝I
d(x，y)+I
a(x，y)cos[φ(x，y)-δ(t)]
In the formula, I
d(x y) is the direct current light distribution of interference field;
I
a(x y) is the interchange light distribution of interference field;
φ (x, y) be tested corrugated and phase differential with reference to the corrugated distributes, i.e. the measuring object of phase shift interference;
δ (t) is the variable phase in two optical interference circuits.
Change phase place δ (t) by top method, measure light distribution I in the interferogram of four width of cloth phase change (x, y, t), and to φ (x y) accurately finds the solution.
Following formula can be rewritten as:
I(x，y，δ
i)＝a
0(x，y)+a
1(x，y)cosδ
i+a
2(x，y)sinδ
i
In the formula, a
0(x, y)=I
d(x, y)
a
1(x，y)＝I
a(x，y)cos[φ(x，y)]
a
2(x，y)＝-I
a(x，y)sin[φ(x，y)]
(x y) can pass through a to tested phase
2(x, y) and a
1(x, ratio y) is tried to achieve:
For four step phase shift: δ of the present invention
1=0, δ
2=pi/2, δ
3=π, δ
4=3 pi/2s, the above formula of substitution obtains:
I in the following formula
1, I
2, I
3, I
4Be respectively the light intensity value in four width of cloth images, obtain the phase value of each point of wavefront like this by four light intensity values of each pixel location, preferably by fitting the phase value that obtains whole wavefront.
Obtain vertical position and horizontal level runout information that wavefront information just can obtain figure by the inclination and the out of focus information of wavefront later.When the mask graph along continuous straight runs carries out translation, with reference to corrugated and tested corrugated with run-off the straight.
From the light beam numerical aperture of reference light single-mode fiber 4 outgoing is 0.2, and the focal length of alignment optical system is 15mm, and when the deviation of 1nm took place horizontal level, the maximum deviation after subtract each other on two corrugateds was 0.4nm from two marginal positions of wavefront intersection region.The Wave-front phase that it is introduced is changed to:
θ＝(0.4/λ)*360＝(0.4/650)*360°＝0.22°
Because the light intensity I of imageing sensor 6 changes and the relation of Wave-front phase deviation is as follows:
I＝A×(1+cos(θ))+C
In the following formula:
The degree of depth that the A representative is interfered or effective interference strength;
C represents noncoherent light intensity background, is about 1/5th of A;
Largest light intensity on the imageing sensor 6 is A+C=1.2A; If adopt 12 bit image sensors, the resolution of light intensity is 1/4096; So the minimum intensity of light that it can be differentiated is changed to 1.2A/4096, take the lead in to the 90 ° of fixing phasic differences in two corrugateds in order to improve to differentiate, obtain light intensity like this and change as follows:
ΔI＝|A×(cos(90°)-cos(90.22°))|＝A/260；
Such light intensity changes and can effectively be distinguished by imageing sensor 6, can instead release the minimum transversal displacement of differentiating from following formula to be:
ΔX＝1nm*(1.2A/4096)/(A/260)＝0.08nm；
When mask graph generation out of focus, corresponding reference corrugated and perspective corrugated reflection focal plane depart from, and just can realize nano level vertical position resolution by the defocusing amount of judging two corrugateds.
The shift position of main control computer 18 control mask graphs, and constantly revise, make it the focal plane and the obliquity that reach best.
That more than introduces only is based on preferred embodiment one by one of the present invention, can not limit scope of the present invention with this.Any device and method of the present invention is done replacement, the combination, discrete of step well know in the art, and the invention process step is done well know in the art being equal to change or replace and all do not exceed exposure of the present invention and protection domain.
Claims (7)
1. figure locating and detecting device, the change in location that is used for measurement pattern, it is characterized in that, described device comprises that described mask platform is used for the mask that carrying tool has described figure along surveying the spectroscope that phase shift module, transmission focusing optical module, mask platform, Amici prism, collimating module, 45 degree that light path is arranged in order are provided with and being positioned at alignment sensor on described spectroscope first exit facet; Described device also comprises: lighting source module, its emergent light through an illumination focus module after, shine the upper surface of mask by described Amici prism; Laser light source module, its emergent light is divided into a branch of reference light and a branch of transmitted light by a spectral module, described reference light is incident to described Amici prism by a reference light single-mode fiber, and described transmitted light focuses on the figure of described mask through described phase shift module and described transmission focusing optical module by a transmitted light single-mode fiber; Also be provided with an image-forming module and an imageing sensor on described spectroscopical second exit facet; Described device also comprises the main control computer that links to each other with above-mentioned each parts.
2. figure locating and detecting device as claimed in claim 1 is characterized in that: described transmission focusing optical module is fixed on the described phase shift module, and this phase shift module can vertically move.
3. figure locating and detecting device as claimed in claim 1 is characterized in that: described transmitted light and reference light are the coherent lights from the same emergent light of described laser light source module.
4. figure locating and detecting device as claimed in claim 1 is characterized in that: described reference light and transmitted light merge by described Amici prism.
5. figure locating and detecting device as claimed in claim 1 is characterized in that: described mask platform can accurately move in X, Y, Z direction.
6. figure locating and detecting device as claimed in claim 1 is characterized in that: described main control computer control laser light source module produces laser and regulates light intensity, control lighting source module switch and light intensity, control phase shift module and move, control the image information analysis that mask platform moved and controlled sensor.
7. adopt the detection method of figure locating and detecting device as claimed in claim 1, it is characterized in that,, measure the wavefront variation of transmitted light by the method that described transmitted light and reference light are interfered, thereby calculate the position of figure, described method comprises the following steps:
(1) light intensity is opened and regulated to main control computer control lighting source module, allows illumination light shine figure on the mask;
(2) receive the image information of described figure by imageing sensor;
(3) do the image analysis by imageing sensor and find and to carry out pinpoint figure, and figure is carried out coarse positioning by main control computer control;
(4) close the lighting source module, open laser light source module;
(5) out of focus by alignment sensor analyzed pattern surface and departing from;
(6) shift position of control figure makes it the focal plane and the obliquity that reach best;
(7) main control computer calculates the precise position information of this figure according to the graph position of alignment sensor record.
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| CN106647213B (en) * | 2017-01-19 | 2019-10-29 | 中国人民解放军装甲兵工程学院 | The dry plate precision positioning device and method that laser hologram directly prints |
| US10274836B2 (en) * | 2017-06-23 | 2019-04-30 | International Business Machines Corporation | Determination of lithography effective dose uniformity |
| JP2019028171A (en) * | 2017-07-27 | 2019-02-21 | Hoya株式会社 | Inspection method of photomask, production method of photomask, and inspection equipment of photomask |
| CN108897153B (en) * | 2018-08-10 | 2024-08-23 | 宁波舜宇仪器有限公司 | Automatic visual detection device for conductive particles of liquid crystal panel |
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| CN1983037A (en) * | 2002-05-22 | 2007-06-20 | 尼康株式会社 | Exposure method, exposure device, and method of manufacturing device |
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|---|---|---|---|---|
| CN1983037A (en) * | 2002-05-22 | 2007-06-20 | 尼康株式会社 | Exposure method, exposure device, and method of manufacturing device |
Non-Patent Citations (3)
| Title |
|---|
| JP特开2005-175177A 2005.06.30 |
| JP特开2005-300250A 2005.10.27 |
| JP特开2006-47669A 2006.02.16 |
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Address after: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Patentee after: Shanghai microelectronics equipment (Group) Limited by Share Ltd Address before: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Patentee before: Shanghai Micro Electronics Equipment Co., Ltd. |