CN201166781Y - In situ detection system for image difference of photo-etching machine projection objective - Google Patents

Abstract

The utility model relates to an even aberration in-situ measurement system for a projection objective lens of a photoetching machine. The system comprises a light source, a lighting subsystem, a test mask, a mask platform, a projection objective lens, a workpiece table, an image-sensing device arranged on the workpiece table, a data acquisition card and a computer. The image-sensing device comprises an aperture diaphragm, an imaging objective lens and a photoelectric detector. The test mask comprises test marks used for the even aberration in-situ measurement. The test marks include phase-shift grate marks in the 0-degree, 45-degree, 90-degree and 135-degree directions. The line-space ratio of the grate is optimized so that the aberration sensitivity is maximal. The even aberration in-situ measurement system has the advantage of high accuracy of measuring the even aberration.

Description

Projection lens of lithography machine idol difference in situ detection system

Technical field

The utility model relates to litho machine, particularly a kind of projection lens of lithography machine idol difference in situ detection system.

Background technology

Make the field at great scale integrated circuit, the advanced scanning projecting photoetching machine that is used for photoetching process is known.Projection objective system is one of most important subsystem in the advanced scanning projecting photoetching machine.The wave aberration of projection objective makes the optical patterning deterioration of litho machine, and causes reducing of photoetching process tolerance limit.Wave aberration can be divided into strange aberration and idol poor.Wherein, strange aberration comprises that mainly coma and three ripples are poor, and the idol difference mainly comprises spherical aberration and astigmatism.The coma of projection objective makes the graph exposure on the mask behind silicon chip the image space skew take place, and this imaging offset is relevant with dimension of picture and lighting condition, thereby the coma of projection objective is one of key factor that influences alignment precision.Coma also can cause the symmetric figure on the mask asymmetric at the figure that exposure, the back of developing form on silicon chip, thereby influences the homogeneity of photoetching resolution and live width.The figure that three ripple official post dynamic RAM graph exposures of projection objective form on silicon chip after developing is asymmetric, influences the performance of dynamic RAM.The spherical aberration of projection objective causes the optimal focal plane of figure to be offset, and make different size, different pitch lines optimal focal plane not in one plane.The optimal focal plane that the astigmatism of projection objective mainly makes mutually perpendicular lines is not in one plane.The existence of projection objective idol difference dwindles effective depth of focus of optical patterning system, and the accuracy of detection of focusing leveling system has been proposed harsh more requirement.Along with constantly reducing of lithographic feature size, the use of especially various resolution enhance technology, the idol difference is more and more outstanding to the influence of optical patterning quality.Therefore, quick, high-precision projection lens of lithography machine idol difference in situ detection system is indispensable.

TAMIS (TIS At Multiple Illumination Settings) technology is to be used to one of major technique that detects photo-etching machine projecting objective coma aberration at present in the world.Referring to technology 1 formerly, Hans van der Laan, Marcel Dierichs, Henk van Greevenbroek, Elaine McCoo, Fred Stoffels, Richard Pongers, Rob Willekers. " Aerial image measurement methods for fast aberration set-up and illumination pupilverification. " Proc.SPIE 2001,4346,394-407.The system that the TAMIS technology adopts comprises work stage and is installed in transmission-type image-position sensor, mask platform and test mask, illuminator and computing machine etc. on the work stage.Wherein the transmission-type image-position sensor is made of two parts: a cover is of a size of isolated line and square hole of submicron order, and independently photodiode is all placed in isolated line and square hole below.Wherein isolated line comprises the isolated line of directions X and the isolated line of Y direction, and square hole is used for the light-intensity variation of compensating illumination light source.The transmission-type image-position sensor can be distinguished the three-dimensional imaging position of measured X direction lines and Y direction lines.In the TAMIS technology, make on the transmission-type image-position sensor scanning mask directions X test badge and Y direction test badge through the projection objective imaging by the travelling workpiece platform, can obtain the axial image space of mark, obtain axial imaging offset (Δ Z with the ideal image position after relatively again _X(NA, σ), Δ Z _Y(NA, σ)).In different projection objective numerical apertures and illuminator partial coherence factor the image space of measuring each mark on the mask down is set, obtains the imaging offset Δ Z at diverse location place in the visual field under the different lighting conditions _X(NA _i, σ _i), Δ Z _Y(NA _i, σ _i), (i=1,2,3 ... n), obtain the corresponding zernike coefficient Z of idol difference after utilizing mathematical model to calculate then ₉, Z ₁₂, Z ₁₆, Z ₂₁

Because the transmission-type image-position sensor has special structure, so the shape of test badge generally need be designed to the shape of certain branch of transmission-type image-position sensor, so the design of test badge has been subjected to certain restriction.In addition, in the measuring process of imaging offset, need make the transmission-type image-position sensor carry out 3-D scanning through the projection objective imaging by the travelling workpiece platform, so Measuring Time be longer relatively to test badge on the mask.

The test mask that the TAMIS technology adopts is a binary mask, and with respect to various phase shifting masks, the idol difference is less to the influence of binary mask image space skew.Therefore the TAMIS technology uses binary mask to carry out the detection of idol difference, and the variation range of sensitivity coefficient is less, and the precision that causes the idol difference to detect is limited.

At the deficiency that the TAMIS technology exists, people such as FAN WANG have proposed a kind of projection lens of lithography machine idol difference in situ detection technology based on the phase shift mask mark.Referring to technology 2 formerly, Fan Wang, XiangzhaoWang, Mingying Ma, Dongqing Zhang, Weijie Shi and Jianming Hu, " Aberrationmeasurement of projection optics in lithographic tools by use of an alternatingphase-shifting mask; " Appl.Opt.45,281-287 (2006), this technology adopts the binary raster mark that adopts in the alternate type phase shift grating marker replacement TAMIS technology of horizontal direction and vertical direction to carry out the detection of idol difference.The idol difference sensitivity coefficient variation range of alternate type phase shift grating marker is bigger, and accuracy of detection is significantly improved than the TAMIS technology.

Formerly technology 1 and formerly technology 2 when detecting spherical aberration, the optimal focal plane side-play amount that spherical aberration caused is the mean value of the optimal focal plane side-play amount of the optimal focal plane side-play amount of horizontal direction lines and vertical direction lines, and has ignored the influence of 45 ° of directions and 135 ° of direction lines optimal focal plane side-play amounts.Formerly technology 1 and formerly technology 2 when detecting astigmatism, only considered horizontal/vertical astigmatism (Z ₁₂, Z ₂₁), and ignored ± 45 ° of astigmatism (Z ₁₃, Z ₂₂).Yet, along with constantly reducing of integrated circuit pattern characteristic dimension, integrated circuit pattern density improves constantly, and integrated circuit pattern is more sophisticated also, 45 ° of directions and 135 ° of direction lines are applied even more extensively among integrated circuit (IC) design, especially among the design of memory device.Therefore, when detecting projection lens of lithography machine idol difference, must measure the optimal focal plane side-play amount of 45 ° of directions and 135 ° of direction lines, thereby record ± 45 ° of astigmatism (Z ₁₃, Z ₂₂), and the accuracy of detection of spherical aberration is improved.

Summary of the invention

The purpose of this utility model is to overcome the deficiency of above-mentioned technology formerly, a kind of projection lens of lithography machine idol difference in situ detection system is provided, the utility model will be considered the processing of the optimal focal plane skew of 0 °, 45 °, 90 °, 135 ° direction lines comprehensively, improve the precision that the idol difference detects, improve the detection speed of idol difference simultaneously.

Technical solution of the present utility model is as follows:

A kind of projection lens of lithography machine idol difference in situ detection system, comprise the light source that produces illuminating bundle, be used to adjust the beam waist of the light beam that described light source sends, the illuminator of light distribution and partial coherence factor and lighting system, energy bearing test mask and pinpoint mask platform, can be with mask graph imaging and the adjustable projection objective of its numerical aperture, the pinpoint work stage of energy, be installed in the picture sensing device of the pattern imaging position on the measurement test mask on the work stage, be characterized in that described test mask is by 0 ° of direction idol difference measurements mark, 45 ° of direction idol difference measurements marks, 90 ° of direction idol difference measurements marks and 135 ° of direction idol difference measurements marks are formed, described 0 ° of direction idol difference measurements mark, 45 ° of direction idol difference measurements marks, 90 ° of direction idol difference measurements marks and 135 ° of direction idol difference measurements are labeled as phase shift grating marker, and described picture sensing device is by the aperture diaphragm that links to each other successively, image-forming objective lens, photodetector, data collecting card and computing machine are formed.

Described phase shift grating marker is the alternate type phase shift grating marker, or the attenuation type phase shift grating marker, or the Chrome-free phase shift grating marker.

Described photodetector is CCD, or photodiode array.

The utility model has been owing to adopted technique scheme, compares with technology formerly, has the following advantages and good effect:

1. the utility model is measured by the alternate type phase shift grating marker optimal focal plane side-play amount of 0 °, 45 °, 90 °, 135 ° four direction, has considered the optimal focal plane side-play amount of all directions lines comprehensively, thereby has improved the accuracy of detection of spherical aberration.

2. the utility model is by measuring 45 ° of directions and 135 ° of direction lines optimal focal plane side-play amounts, realized ± detection of 45 ° of astigmatisms.

3. adopted the empty phase shift grating marker than optimization of line in the test mask of the present utility model, the antithesis aberration is more responsive, can improve the precision that idol difference difference detects.

4. during the utility model measurement markers optimal focal plane side-play amount, need not test badge on the mask is carried out 3-D scanning through the projection objective imaging, after utilizing the accurate leveling of sextuple scanning platform, directly on the axial scan mask test badge through the projection objective imaging, thereby obtain the optimal focal plane side-play amount of test badge.

5. the utility model also can be by the conversion lighting system, and methods such as use pupil filtering increase idol difference sensitivity coefficient transformation range, thereby have improved idol difference accuracy of detection.

Description of drawings

Fig. 1 is the structural representation of the utility model projection lens of lithography machine idol difference in situ detection system.

Fig. 2 is the synoptic diagram of the test badge on the utility model institute use test mask.

Fig. 3 is the picture sensing device structural representation that the utility model adopts.

Fig. 4 is the Z of the test badge that adopts among the utility model embodiment ₉Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.

Fig. 5 is the Z of the test badge that adopts among the utility model embodiment ₁₆Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.

Fig. 6 is the Z of the test badge that adopts among the utility model embodiment ₁₂/ Z ₁₃Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.

Fig. 7 is the Z of the test badge that adopts among the utility model embodiment ₂₁/ Z ₂₂Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.

Embodiment

The utility model is described in further detail below in conjunction with embodiment and accompanying drawing, but should not limit protection domain of the present utility model with this.

The utility model projection lens of lithography machine idol difference in situ detection system, as shown in Figure 1.This system comprises the light source 1 that produces illuminating bundle; Be used to adjust the illuminator 2 of beam waist, light distribution, partial coherence factor and the lighting system of the light beam that described light source sends; Energy bearing test mask 3 and pinpoint mask platform 4; Can be with pattern imaging on the test mask 3 and the adjustable projection objective 5 of numerical aperture; The pinpoint sextuple scanning platform 6 of energy; Be installed in the picture sensing device 7 of the pattern imaging position that is used to measure on the sextuple scanning platform 6 on the test mask 3.

Described light source 1 can be ultraviolet, deep ultraviolet and extreme ultraviolet light sources such as mercury lamp, excimer laser, laser plasma light source and discharge plasma light source.

Described illuminator 2 comprises extender lens group 21, beam shaping 22 and beam homogenizer 23.

Described lighting system comprises traditional lighting, ring illumination, secondary illumination, level Four illumination etc.

As shown in Figure 2, on the described test mask 3, comprise 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34.

33,135 ° of direction idol difference measurements of described 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34 is alternate type phase shift grating markers, or attenuation type phase shift grating marker, or the Chrome-free phase shift grating marker etc., its line is empty than reaching maximum idol difference sensitivity by optimizing.

Described projection objective 5 can be total transmissivity formula projection objective, catadioptric formula projection objective, total-reflection type projection objective etc.

As shown in Figure 3, described picture sensing device 7 is made up of the aperture diaphragm 71, image-forming objective lens 72, photodetector 73, data collecting card 74 and the computing machine 75 that link to each other successively.

Described photodetector 73 can be that CCD, photodiode array or other have the detector array of photosignal translation function.During measurement markers optimal focal plane side-play amount, need not test badge on the mask is carried out 3-D scanning through the projection objective imaging, after utilizing sextuple scanning platform 6 accurate leveling, directly on the axial scan mask test badge through the projection objective imaging, thereby obtain the optimal focal plane side-play amount of test badge.

A kind of method that adopts described projection lens of lithography machine idol difference in situ detection system to carry out projection lens of lithography machine idol difference in situ detection.May further comprise the steps:

The extender lens group 21 of the illumination light that light source 1 sends in illuminator 2 expands Shu Houjin and goes into light beam reshaper 22, obtains needed lighting system, enters the light intensity homogenising that beam homogenizer 23 makes illumination light again; Test mask 3 on the illumination beam mask platform 4 after the light intensity homogenising makes 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32, the 90 ° of direction idol difference measurements mark mark 34 on the test mask 3 be imaged on aperture diaphragm 71 surfaces of picture on the sensing device 7 that are installed in sextuple scanning platform 6 through projection objective 5 by regulating sextuple scanning platform 6; The picture of 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34 by aperture diaphragm 71 filtering after image-forming objective lens 72 be imaged on photodetector 73 surface and be converted into electric signal, send into computing machine 75 after this signal is gathered by data collecting card 74 and carry out data processing, can obtain under current numerical aperture NA and partial coherence factor σ condition the optimal focal plane of 0 ° of direction idol difference measurements mark 31 and the offset Z between the desirable focal plane by calculating ₃₁(NA, σ), the optimal focal plane of 45 ° of direction idol difference measurements marks 32 and the offset Z between the desirable focal plane ₃₂(NA, σ), the optimal focal plane of 90 ° of direction idol difference measurements marks 33 and the offset Z between the desirable focal plane ₃₃(NA, σ), and the optimal focal plane of 135 ° of direction idol difference measurements marks 34 and the offset Z between the desirable focal plane ₃₄(NA, σ); The numerical aperture of partial coherence factor, lighting system and projection objective 5 by changing illuminator 2 is utilized describedly to record the described optimal focal plane offset Z of many groups as sensing device 7 ₃₁(NA _i, σ _i), Δ Z ₃₂(NA _i, σ _i), Δ Z ₃₃(NA _i, σ _i), Δ Z ₃₄(NA _i, σ _i) (i=1,2,3 ... n); Utilize lithography simulation software to demarcate the idol difference sensitivity coefficient S of described projection objective 5 under different numerical apertures and partial coherence factor condition ₁(NA, σ) and S ₂(NA, σ); Utilize described idol difference sensitivity coefficient to calculate the size of the zernike coefficient relevant with the idol difference of projection objective 5.Detailed demarcation and calculation process are as described below.

The wave aberration of projection objective is represented by zernike polynomial usually:

$W(\mathrm{\ρ},\mathrm{\θ})=\underset{n=1}{\overset{\∞}{\mathrm{\Σ}}}{Z}_n\·R_n(\mathrm{\ρ},\mathrm{\θ}),n\∈Z$

$={\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2\mathrm{\&rho;}\cos \mathrm{\&theta;}+{\mathrm{<figure-callout\; id="3"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_3\mathrm{\&rho;}\sin \mathrm{\&theta;}+Z_4({2\mathrm{\&rho;}}^2-1)+{\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5{\mathrm{\&rho;}}^2\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">cos</figure-callout>}2\mathrm{\&theta;}+{\mathrm{<figure-callout\; id="6"\; label="Z"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">Z</figure-callout>}}_6{\mathrm{\&rho;}}^2\sin 2\mathrm{\&theta;}+\&CenterDot;\&CenterDot;\&CenterDot;+$

$Z_9({6\mathrm{\&rho;}}^4-{6\mathrm{\&rho;}}^2+1)+\&CenterDot;\&CenterDot;\&CenterDot;+Z_{12}({4\mathrm{\&rho;}}^2-3){\mathrm{\&rho;}}^2\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">cos</figure-callout>}2\mathrm{\&theta;}+Z_{13}({4\mathrm{\&rho;}}^2-3){\mathrm{\&rho;}}^2\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">sin</figure-callout>}2\mathrm{\&theta;}---\left(1\right)$

$+\&CenterDot;\&CenterDot;\&CenterDot;+Z_{16}({20\mathrm{\&rho;}}^6-30{\mathrm{\&rho;}}^4+12{\mathrm{\&rho;}}^2-1)+Z_{21}({15\mathrm{\&rho;}}^4-{20\mathrm{\&rho;}}^2+6){\mathrm{\&rho;}}^2\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">cos</figure-callout>}2\mathrm{\&theta;}$

$+\&CenterDot;\&CenterDot;\&CenterDot;+Z_{22}({15\mathrm{\&rho;}}^4-20{\mathrm{\&rho;}}^2+6){\mathrm{\&rho;}}^2\sin 2\mathrm{\&theta;}+\&CenterDot;\&CenterDot;\&CenterDot;$

Wherein, ρ, θ are the normalization polar coordinates of object lens emergent pupil face.Zernike coefficient Z ₉And Z ₁₆Represent three rank spherical aberrations and five rank spherical aberrations respectively, Z ₄With Z ₅H/V astigmatism and ± 45 ° of astigmatisms on difference three rank, Z ₁₂With Z ₂₁H/V astigmatism and ± 45 ° of astigmatisms on difference five rank, Z ₂₁With Z ₂₂H/V astigmatism and ± 45 ° of astigmatisms on difference seven rank.Ignoring under the situation of higher order aberratons, the figure optimal focal plane side-play amount that the idol difference causes can be expressed as

ΔZ _s(ρ)∝Z ₄+Z ₉(3ρ ²-1.5)+Z ₁₆(10ρ ⁴-10ρ ²+1)，(2)

${\mathrm{\&Delta;Z}}_a^{H/V}\left(\mathrm{\&rho;}\right)\&Proportional;{\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5+Z_{12}({4\mathrm{\&rho;}}^2-3)+Z_{21}(15{\mathrm{\&rho;}}^4-20{\mathrm{\&rho;}}^2+6),---\left(3\right)$

${\mathrm{\&Delta;Z}}_a^{\&PlusMinus;45}\left(\mathrm{\&rho;}\right)\&Proportional;{\mathrm{<figure-callout\; id="6"\; label="Z"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">Z</figure-callout>}}_6+Z_{13}({4\mathrm{\&rho;}}^2-3)+Z_{22}(15{\mathrm{\&rho;}}^4-20{\mathrm{\&rho;}}^2+6),---\left(4\right)$

Wherein, Δ Z _s(ρ) be the optimal focal plane side-play amount that spherical aberration causes, Δ Z _a ^H/V(ρ) be the optimal focal plane side-play amount that causes by the H/V astigmatism, Δ Z _a ^{± 45}(ρ) be the optimal focal plane side-play amount that causes by ± 45 ° of astigmatisms.Can find out that by (2)～(4) formula the idol difference depends on the spectrum distribution of measurement markers at pupil plane to the influence of figure optimal focal plane skew.

The optimal focal plane side-play amount that spherical aberration causes is the mean value of the optimal focal plane side-play amount of 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34, can be calculated by following formula

${\mathrm{\&Delta;Z}}_s(\mathrm{NA},\mathrm{\&sigma;})=\frac{{\mathrm{\&Delta;Z}}_{31}(\mathrm{NA},\mathrm{\&sigma;})+{\mathrm{\&Delta;Z}}_{32}(\mathrm{NA},\mathrm{\&sigma;})+{\mathrm{\&Delta;Z}}_{33}(\mathrm{NA},\mathrm{\&sigma;})+{\mathrm{\&Delta;Z}}_{34}(\mathrm{NA},\mathrm{\&sigma;})}{4}---\left(5\right)$

The optimal focal plane side-play amount that the H/V astigmatism causes is the distance between the optimal focal plane of the optimal focal plane of 0 ° of direction idol difference measurements mark 31 and 90 ° of direction idol difference measurements marks 33

${\mathrm{\&Delta;Z}}_a^{H/V}(\mathrm{NA},\mathrm{\&sigma;})={\mathrm{\&Delta;Z}}_{31}(\mathrm{NA},\mathrm{\&sigma;})-{\mathrm{\&Delta;Z}}_{33}(\mathrm{NA},\mathrm{\&sigma;})---\left(6\right)$

The optimal focal plane side-play amount that ± 45 ° of astigmatisms cause is the distance between the optimal focal plane of the optimal focal plane of 45 ° of direction idol difference measurements marks 32 and 135 ° of direction idol difference measurements marks 34

${\mathrm{\&Delta;Z}}_a^{\&PlusMinus;45}(\mathrm{NA},\mathrm{\&sigma;})={\mathrm{\&Delta;Z}}_{32}(\mathrm{NA},\mathrm{\&sigma;})-{\mathrm{\&Delta;Z}}_{33}(\mathrm{NA},\mathrm{\&sigma;})---\left(7\right)$

Meanwhile, the measurement markers optimal focal plane side-play amount that causes of idol difference also depends on the partial coherence factor of the numerical aperture and the illuminator of projection objective.Under the certain situation of idol difference, change the numerical aperture of projection objective and the partial coherence factor of illuminator the light distribution of the light of different space frequency will be changed, thereby the measurement markers optimal focal plane that the idol difference is caused changes.Regulate the partial coherence factor and the lighting system of beam shaping 22 change illuminators, and the numerical aperture of regulating projection objective 5, the optimal focal plane side-play amount that is caused by the idol difference can be expressed as

ΔZ _s(NA _i，σ _i)＝S ₁(NA _i，σ _i)Z ₄+S ₂(NA _i，σ _i)Z ₉+S ₃(NA _i，σ _i)Z ₁₆，(i＝1，2，3……n)，(8)

${\mathrm{\&Delta;Z}}_a^{H/V}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=S_4({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i){\mathrm{<figure-callout\; id="5"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_5+S_5({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i){\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="Y20082005517700142.png,Y20082005517700143.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+S_6({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i){\mathrm{<figure-callout\; id="21"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{21},(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(9\right)$

${\mathrm{\&Delta;Z}}_a^{\&PlusMinus;45}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=S_7({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i){\mathrm{<figure-callout\; id="6"\; label="Z"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">Z</figure-callout>}}_6+S_8({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)Z_{13}+S_9({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i){\mathrm{<figure-callout\; id="22"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{22},(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(10\right)$

Wherein, Δ Z _s(NA _i, σ _i) be the optimal focal plane side-play amount that spherical aberration causes under given numerical aperture NA and partial coherence factor σ condition, Δ Z _a ^H/V(NA _i, σ _i) be the optimal focal plane side-play amount that the H/V astigmatism causes under given numerical aperture NA and partial coherence factor σ condition, Δ Z _a ^{± 45}(NA _i, σ _i) under given numerical aperture NA and partial coherence factor σ condition ± 45 ° of optimal focal plane side-play amounts that astigmatism causes.S ₁(NA _i, σ _i), S ₂(NA _i, σ _i), S ₃(NA _i, σ _i), S ₄(NA _i, σ _i), S ₅(NA _i, σ _i), S ₆(NA _i, σ _i), S ₇(NA _i, σ _i), S ₈(NA _i, σ _i) and S ₉(NA _i, σ _i) be idol difference sensitivity coefficient, by following formula definition

$S_1({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{{\&PartialD;\mathrm{\&Delta;Z}}_s({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_4}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(11\right)$

$S_2({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{{\&PartialD;\mathrm{\&Delta;Z}}_s({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_9}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(12\right)$

$S_3({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{{\&PartialD;\mathrm{\&Delta;Z}}_s({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_{16}}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(13\right)$

$S_4({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{H/V}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_5}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(14\right)$

$S_5({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{H/V}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_{12}}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(15\right)$

$S_6({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{H/V}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_{21}}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(16\right)$

$S_7({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{\&PlusMinus;45}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_6}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(17\right)$

$S_8({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{\&PlusMinus;45}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_{13}}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n),---\left(18\right)$

$S_9({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)=\frac{\&PartialD;\mathrm{\&Delta;}{Z}_a^{\&PlusMinus;45}({\mathrm{NA}}_i,{\mathrm{\&sigma;}}_i)}{{\&PartialD;Z}_{22}}(i=\mathrm{1,2,3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;n).---\left(19\right)$

Sensitivity coefficient changes with the numerical aperture of projection objective and the partial coherence factor of illuminator, can utilize lithography simulation software to demarcate and obtain.As demarcating the sensitivity coefficient S under certain numerical aperture and partial coherence factor condition ₁(NA _i, σ _i) time, can set certain Z ₄Value and to get other zernike coefficient be zero uses the lithography simulation software emulation to calculate by Z ₄The optimal focal plane offset Z that causes _s(NA _i, σ _i), Ci Shi sensitivity coefficient S then ₁(NA _i, σ _i) can be Δ Z _s(NA _i, σ _i) and Z ₄Ratio, S ₂(NA _i, σ _i), S ₃(NA _i, σ _i), S ₄(NA _i, σ _i), S ₅(NA _i, σ _i), S ₆(NA _i, σ _i), S ₇(NA _i, σ _i), S ₈(NA _i, σ _i) and S ₉(NA _i, σ _i) scaling method and S ₁(NA _i, σ _i) similar.

Be provided with down in a series of different numerical apertures and partial coherence factor, can obtain its light distribution and calculate the optimal focal plane side-play amount by the aerial image that is installed on the sextuple scanning platform 6, can represent by following matrix equation as 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34 on the sensing device 7 probing test masks 3:

$\left[\begin{array}{c}{\mathrm{\&Delta;Z}}_s({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ {\mathrm{\&Delta;Z}}_s({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\end{array}\right]=\left[\begin{array}{ccc}{S}_1({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_2({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_3({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ S_1({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_2({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_3({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \end{array}\right]\left[\begin{array}{c}{Z}_4\\ Z_9\\ {\mathrm{<figure-callout\; id="16"\; label="Z"\; filenames="Y20082005517700142.png,Y20082005517700143.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{16}\end{array}\right],---\left(20\right)$

$\left[\begin{array}{c}\mathrm{\&Delta;}{Z}_a^{H/V}({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ \mathrm{\&Delta;}{Z}_a^{H/V}({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\end{array}\right]=\left[\begin{array}{ccc}{S}_4({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_5({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_6({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ S_4({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_5({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_6({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \end{array}\right]\left[\begin{array}{c}{Z}_5\\ Z_{12}\\ {\mathrm{<figure-callout\; id="21"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{21}\end{array}\right].---\left(21\right)$

$\left[\begin{array}{c}{\mathrm{\&Delta;Z}}_a^{\&PlusMinus;45}({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ {\mathrm{\&Delta;Z}}_a^{\&PlusMinus;45}({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\end{array}\right]=\left[\begin{array}{ccc}{S}_7({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_8({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)& S_9({\mathrm{<figure-callout\; id="1"\; label="NA"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">NA</figure-callout>}}_1,{\mathrm{\&sigma;}}_1)\\ S_7({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_8({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)& S_9({\mathrm{<figure-callout\; id="2"\; label="NA"\; filenames="Y20082005517700131.png,Y20082005517700142.png"\; state="\{\{state\}\}">NA</figure-callout>}}_2,{\mathrm{\&sigma;}}_2)\\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \\ \&CenterDot;& \&CenterDot;& \end{array}\right]\left[\begin{array}{c}{Z}_6\\ Z_{13}\\ {\mathrm{<figure-callout\; id="22"\; label="Z"\; filenames="Y20082005517700131.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{22}\end{array}\right].---\left(22\right)$

Above-mentioned equation is an overdetermined equation, can find the solution by least square method.Utilization is provided with the optimal focal plane side-play amount of measuring 33,135 ° of direction idol difference measurements of diverse location place 0 ° of direction idol difference measurements mark, 31,45 ° of direction idol difference measurements mark, 32,90 ° of direction idol difference measurements mark mark 34 in the visual field down as sensing device 7 in series of values aperture and partial coherence factor, utilizes the sensitivity coefficient of demarcating can calculate the zernike coefficient Z of relevant position in the visual field ₉, Z ₁₆, Z ₁₂, Z ₁₃, Z ₂₁And Z ₂₂

The system architecture of the utility model embodiment as shown in Figure 1, it is the ArF excimer laser of 193nm that light source 1 adopts wavelength, the lighting system that illuminator 2 provides is a traditional lighting, the partial coherence factor variation range is 0.3～0.8.The numerical aperture variation range of projection objective 5 is 0.5～0.8.33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34 on the test mask 3 is the alternate type phase shift grating marker that live width is 250nm, and its line is empty than being 1: m.Projection objective 5 is total transmissivity formula projection objectives.Photodetector 73 among Fig. 3 is a photodiode array.

With 90 ° of direction idol difference measurements marks 33 is example, and its multiple transmittance function is

$t\left(x\right)=\underset{n=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\mathrm{\&delta;}[x-2n(m+1)w]*\left\{\mathrm{rect}\right[\frac{x+(m+1)w/2}{\mathrm{mw}}]-\mathrm{rect}[\frac{x-(m+1)w/2}{\mathrm{mw}}\left]\right\},n\&Element;Z,,---\left(23\right)$

Wherein, w is the live width of alternate type moving phase grating.The alternate type moving phase grating is the Fourier transform of its multiple transmittance function in the spectrum distribution of objective lens pupil face:

$U\left(f_x\right)=j\frac{m}{m+1}\underset{n=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\mathrm{\&delta;}[f_x-\frac{n}{2(m+1)w}]\sin c\left(\mathrm{mwfx}\right)\sin \left[\mathrm{\&pi;}(m+1){\mathrm{wf}}_x\right],n\&Element;Z,,---\left(24\right)$

F wherein _x=sin θ/λ is the spatial frequency variable.

By (24) formula as can be known, the spectrum distribution of alternate type moving phase grating depends on the empty ratio of line of grating.When the line of grating empty when being 1: 2, have only ± 1 grade and ± 5 order diffraction light can enter pupil, and ± 5 order diffraction light are arranged in the zone that pupil idol difference has the greatest impact just, therefore can obtain bigger idol difference sensitivity coefficient variation range, and be suitable for use in the idol difference and detect.Therefore, in the present embodiment, 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32, the 90 ° of direction idol difference measurements mark mark 34 among Fig. 3 all adopts line empty than the alternate type moving phase grating that is 1: 2.

In the present embodiment, by measure the optimal focal plane side-play amount of 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32,90 ° of direction idol difference measurements mark mark 34 under different numerical apertures and partial coherence factor condition, utilization (5)～(7) and (20)～(22) formula calculate the zernike coefficient with the idol difference correlation.

The variation range of sensitivity coefficient is the key factor that influences idol difference accuracy of detection.Provide the simulation result of present embodiment part idol difference sensitivity coefficient below.Fig. 4 is the Z of the mean value of the optimal focal plane side-play amount of 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32, the 90 ° of direction idol difference measurements mark mark 34 on the utility model employing test mask 3 ₉Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.Fig. 5 is the Z of the mean value of the optimal focal plane side-play amount of 33,135 ° of direction idol difference measurements of 0 ° of direction idol difference measurements mark 31,45 ° of direction idol difference measurements mark 32, the 90 ° of direction idol difference measurements mark mark 34 on the utility model employing test mask 3 ₁₆Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.Fig. 6 adopts the Z of distance between the optimal focal plane of the optimal focal plane of 0 ° of direction idol difference measurements mark 31 on the test mask 3 and 90 ° of direction idol difference measurements marks 33 for the utility model ₁₂/ Z ₁₃Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.Fig. 7 adopts the Z of the distance between the optimal focal plane of the optimal focal plane of 45 ° of direction idol difference measurements marks 32 on the test mask 3 and 135 ° of direction idol difference measurements marks 34 for the utility model ₂₁/ Z ₂₂Relation between sensitivity coefficient and numerical aperture, the partial coherence factor.

Experimental result shows that the utility model has improved idol difference accuracy of detection and detection speed.

Claims (3)

1, a kind of projection lens of lithography machine idol difference in situ detection system, comprise the light source (1) that produces illuminating bundle, be used to adjust the beam waist of the light beam that described light source (1) sends, the illuminator of light distribution and partial coherence factor and lighting system (2), energy bearing test mask (3) and pinpoint mask platform (4), can be with mask graph imaging and the adjustable projection objective (5) of its numerical aperture, energy pinpoint work stage (6), be installed in the picture sensing device (7) of the pattern imaging position on the measurement test mask (3) on the work stage (6), it is characterized in that described test mask (3) is by 0 ° of direction idol difference measurements mark (31), 45 ° of direction idol difference measurements marks (32), 90 ° of direction idol difference measurements marks (33) and 135 ° of direction idol difference measurements marks (34) are formed, described 0 ° of direction idol difference measurements mark (31), 45 ° of direction idol difference measurements marks (32), the phase shift grating marker of 90 ° of direction idol difference measurements marks (33) and 135 ° of direction idol difference measurements marks (34), described picture sensing device (7) is by the aperture diaphragm (71) that links to each other successively, image-forming objective lens (72), photodetector (73), data collecting card (74) and computing machine (75) are formed.

2, projection lens of lithography machine idol difference in situ detection according to claim 1 system is characterized in that described phase shift grating marker is the alternate type phase shift grating marker, or the attenuation type phase shift grating marker, or the Chrome-free phase shift grating marker.

3, projection lens of lithography machine idol difference in situ detection according to claim 1 system is characterized in that described photodetector (73) is CCD, or photodiode array.

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