CN101639630A - Coaxial alignment system in projection lithography - Google Patents
Coaxial alignment system in projection lithography Download PDFInfo
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- CN101639630A CN101639630A CN200910090921A CN200910090921A CN101639630A CN 101639630 A CN101639630 A CN 101639630A CN 200910090921 A CN200910090921 A CN 200910090921A CN 200910090921 A CN200910090921 A CN 200910090921A CN 101639630 A CN101639630 A CN 101639630A
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Abstract
The invention relates to a coaxial alignment system in projection lithography, which can align grating marks on a mask and a silicon wafer through a projection imaging system and detect the change amount of magnification of the projection imaging system. The alignment system comprises the lithography projection imaging system, the reflection type diffraction grating marks and an alignment imagingsystem. A grating of illumination light on the mask and the silicon wafer generates backward diffraction light, so as to generate the interference on the mask and determine the alignment zero positionby using the alignment imaging system for detecting interference patterns. The coaxial alignment system can obtain the alignment precision from nanometer scale to sub-nanometer scale and have very strong technic adaptability.
Description
Technical field
The present invention is a kind of alignment device that is applicable to the step-scan projection optical system, belongs to the nano-device manufacturing technology field in VLSI (very large scale integrated circuit) manufacturing and the optics Micrometer-Nanometer Processing Technology.
Background technology
The microelectronics industry development mainly relies on the continuous progress of ic manufacturing technology so far.Optical projection lithography has because of it that cost is relatively low, productive rate is high, photoetching resolution is high and advantage such as the visual field is big, is the main flow means that small scale integration and even great scale integrated circuit are made always.The optical projection lithography technology has successively experienced g line, i line, 248nm several technical development stages such as 193nm quasi-molecule laser source till now since 1978 are born.No matter which developing stage, optical projection lithography are mainly relying on three big core technologies, i.e. the progress of photoetching projection objective lens, mask silicon chip alignment system, laser Positioning Stage system advances the development of microelectronics industry.The present invention relates generally to the mask silicon chip alignment system in the optical projection lithography.
Repeat to now advanced scanning projecting photoetching from early stage stepping, its ultimate principle all is that the figure that will make in advance on the mask projects on the silicon chip with reduction magnification by projection objective.Because the integrated circuit manufacturing need carry out the multilayer alignment, silicon chip need be treated that therefore the figure on patterned area and the mask aims at.The technical parameter of characterizing lithography development mainly contains characteristic line breadth (being minimum feature) and alignment precision etc.Along with constantly dwindling of characteristic line breadth, alignment precision requires also high more, and general alignment precision will reach 1/5～1/7 of characteristic line breadth.The lithographic features live width develops into submicron order from micron order, nowadays adopt the immersion double-exposure 193nm deep UV (ultraviolet light) lithography of various resolution enhance technology to surmount diffraction limit far away and reach deep-submicron, corresponding alignment precision requires also to reach nanoscale.
A kind of alignment system and method that is used for projection lithography disclosed among the Chinese patent publication number CN 1495540A.This alignment system adopts two kinds of alignment wavelengths and two aligned with channel, determines aligned position information by the non-zero order diffraction light of gathering two aligned with channel, and the information of two passages is weighted the stability that further improves alignment precision and system.Because this patent is determined alignment information by acquired signal intensity, and light intensity is subjected to the influence of technological process easily, so alignment precision is limited.Because the lithographic projection system can only be to single exposure wavelength imaging, there is very big aberration in mutatis mutandis illumination wavelengths with respect to exposure wavelength, therefore many more to mutatis mutandis illumination wavelengths number, the device of the rectification aberration of needs adding camera lens inside is many more, this not only makes the assembling of projection exposure system therefor become difficult, but also has increased the complicacy of alignment system.This patent adopts single aligning illumination wavelengths, the space phase information of the interference fringe by gathering the order of diffraction is aimed at, therefore alignment device is simple, and exposure technology influence that light intensity is produced do not change the cycle and the space phase information of interference fringe, so this patent can reach very high alignment precision.
Summary of the invention
Technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, the system of the coaxial alignment in a kind of projection lithography is provided, this alignment system can obtain the alignment precision of nanometer to Subnano-class, and has very strong Technological adaptability.
Technical solution of the present invention: the coaxial alignment system in a kind of projection lithography is characterized in that comprising: comprise lithographic projection imaging system, laser illuminator system, mask, silicon chip, be positioned at reflective gratings mark on the mask, be positioned at the reflective diffraction gratings mark on the silicon chip and aim at imaging system; Optical system object space in the described lithographic projection imaging system is in mask one side, as the side in silicon chip one side; The laser illuminator system is radiated at reflective diffraction gratings mark on the silicon chip in the reflective diffraction gratings mark generation reflection diffraction on the mask and transmission, the angle, Littrow makes illumination light produce the diffraction light that returns by former road on this reflective diffraction gratings, this diffraction light sees through the reflection diffraction interference of light that takes place on mask with aforementioned illumination light after the lithographic projection imaging system and obtains interference fringe on the mask face, aim at imaging system this interference fringe is imaged onto on the detector, survey mask and silicon pad alignment position according to the space phase information of interference fringe.
Described lithographic projection imaging system is one and has two telecentric optical systems that image dwindles effect, the incident ray that promptly is parallel to optical axis is parallel with emergent ray, and incident ray and emergent ray and the ratio of the sine of the angle of optical axis equal the inverse of camera lens reduction magnification.Two telecentric optical systems make illumination path greatly be simplified, be convenient to arrange illumination path and help converting mask and silicon chip on the period-luminosity relation of grating marker.
Described lithographic projection imaging system (a1) can see through visible light and 365nm ultraviolet and the deep UV (ultraviolet light) to the 193nm wavelength, and therefore, the illumination light that adopts different wave length according to the actual requirements is with the raising Technological adaptability.
Described laser illuminator system comprises can provide visible light to arrive the infrared single wavelength or the laser instrument and the half-reflecting half mirror of multi-wavelength illumination light, obtains suitable illumination light incident angle by the angle of regulating half-reflecting half mirror.
The incident angle of the illumination light in the described laser illuminator system make in the order of diffraction that the reflective diffraction gratings mark produces time 0 grade of light transmission diffraction grating and enter the projecting etching imaging system.
Illumination light in the described laser illuminator system is 3 °-18 ° in the incident angle of mask face.This incident angle approximates the angle, Littrow of the grating marker on the mask.Incident angle too little then almost with the same optical axis of lithographic projection imaging system, light path arrangement difficulty; The maximal value of incident angle determines that according to the object space numerical aperture of lithographic projection imaging system general object space numerical aperture is 0.3 to the maximum, so ranges of incidence angles is 3 °-18 °.
The dutycycle of the grating of the reflective diffraction gratings mark on the described mask, promptly the ratio of grating lightproof part and grid seam is not more than 1.Because transmitted light needs twice through the lithographic projection imaging system, light intensity is decayed, and therefore adopts non-equidistant grating to improve the diffraction efficiency of transmitted light.
Described aligning imaging system has the numerical aperture less than 0.1, so its field angle of object is very little, has only b
1And b
2Two-beam can enter optical system, eliminates the influence of other diffraction lights to image quality, improves the signal to noise ratio (S/N ratio) of interference fringe.
The present invention's advantage compared with prior art is: the space phase of the interference fringe that the corresponding order of diffraction that the present invention produces by the anti-reflective diffraction gratings mark of gathering on mask and the silicon chip is inferior is surveyed aligned position, the cycle of the cycle of striped with respect to diffraction grating mark has very big enlargement ratio, and space phase is not subjected to the influence of light intensity, therefore can obtain the alignment precision of nanometer to Subnano-class, and has very strong Technological adaptability, can satisfy the alignment precision requirement of traditional optical projection lithography, especially it can satisfy 32nm and with the alignment precision requirement of lower node immersion double-exposure optical projection lithography, break away from the bottleneck restriction of alignment precision, can be used for the aligning of stepping repetition and step-scan optical projection lithography nano-photoetching.
Description of drawings
Fig. 1 is apparatus of the present invention synoptic diagram;
Fig. 2 is the grating marker on mask and the silicon chip, and wherein Fig. 2 a is the alignment mark on the mask, and Fig. 2 b is the alignment mark on the silicon chip;
Fig. 3 is the diffraction synoptic diagram of illumination light on grating marker;
Fig. 4 is the interference fringe of Sine distribution.
Embodiment
As shown in Figure 1 and Figure 2, the present invention by the a1 of projecting etching imaging system, the a2 of laser illuminator system, mask a3 and silicon chip a4, be positioned at alignment mark a5 on silicon chip and the mask and a6 and aim at imaging system a8 and form.Lithographic projection imaging system a1 is one and has two telecentric optical systems that image dwindles effect, the incident ray that promptly is parallel to optical axis is parallel with emergent ray, incident ray and emergent ray and the ratio of the sine of the angle of optical axis equal the inverse of camera lens reduction magnification, and lithographic projection imaging system a1 can be to visible light and 365nm ultraviolet and the deep UV (ultraviolet light) imaging to the 193nm wavelength.The a1 of laser illuminator system comprises can provide visible light to arrive the infrared single wavelength or the laser instrument and the half-reflecting half mirror of multi-wavelength illumination light, obtain suitable illumination light incident angle by the angle of regulating half-reflecting half mirror, 0 grade of light transmission diffraction grating during the order of diffraction that the incident angle of the illumination light among the a2 of laser illuminator system makes the reflective diffraction gratings mark produce is inferior also enters the projecting etching imaging system, and general incident angle is 3 °-18 °.The dutycycle of the grating of the reflective diffraction gratings mark a6 on the mask a3, promptly the ratio of grating lightproof part and grid seam is not less than 1.
Reflective diffraction gratings mark a6 on the mask a3 is transflective diffraction grating, and therefore the reflective diffraction gratings mark a6 label creating on the mask a3 all has diffraction light in the both sides of mask a3 on quartz substrate.Illumination light is radiated on the reflective diffraction gratings mark a6 by half-reflecting half mirror, produces diffraction as shown in Figure 3, wherein+and n represents n order diffraction light, is distributed in the both sides of mask a3.With b
2Represent diffraction backward+n order diffraction light, with b
0Expression sees through 0 order diffraction light of mark grating.b
0Pass the reflective diffraction gratings mark a5 that is radiated at behind the a1 of projecting etching imaging system on the silicon chip a4, and take place backward and the n order diffraction light that returns along former road, with b
1Expression.b
1After passing the reflective diffraction gratings mark a6 on the mask a3 behind the a1 of projecting etching imaging system diffraction takes place, its 0 grade of optical propagation direction does not change, still with b
1Expression, as shown in Figure 1.b
1And b
2Have very little angle and interfere on mask a3 face, the interference fringe of formation as shown in Figure 4.The effect of aiming at imaging system a8 is to gather interference fringe image and amplify certain multiplying power, images in detector a7 and goes up so that carry out subsequent image processing, surveys the aligned position of mask a3 and silicon chip a4 according to the space phase information of interference fringe.The numerical aperture of aiming at imaging system a8 should be less than 0.1, so its field angle of object is very little, has only b
1And b
2Two-beam can enter optical system, eliminates the influence of environment veiling glare to image quality, improves the signal to noise ratio (S/N ratio) of interference fringe.
Claims (9)
1, the coaxial alignment system in a kind of projection lithography is characterized in that comprising: comprise lithographic projection imaging system (a1), laser illuminator system (a2), mask (a3), silicon chip (a4), be positioned at reflective gratings mark (a6) on the mask (a3), be positioned at the reflective diffraction gratings mark (a5) on the silicon chip (a4) and aim at imaging system (a8); Optical system object space in the described lithographic projection imaging system (a1) is in mask (a3) side, as the side in silicon chip (a4) side; The reflective diffraction gratings mark (a6) of laser illuminator system (a2) on mask (a3) locates to take place reflection and transmission diffraction, transmitted light is radiated at the reflective diffraction gratings mark (a5) on the silicon chip (a4) with the angle, Littrow and makes illumination light go up in this reflective diffraction gratings (a5) and produces the diffraction light that returns by former road, this diffraction light sees through lithographic projection imaging system (a1) back and obtain interference fringe with aforementioned illumination light in the reflection diffraction interference of light that mask (a3) upward takes place on mask (a3) face, aim at imaging system (a8) this interference fringe is imaged onto on the detector, survey mask and silicon pad alignment position according to the space phase information of interference fringe.
2, the coaxial alignment system in the projection lithography according to claim 1, it is characterized in that: described lithographic projection imaging system (a1) is one and has two telecentric optical systems that image dwindles effect, the incident ray that promptly is parallel to optical axis is parallel with emergent ray, and incident ray and emergent ray and the ratio of the sine of the angle of optical axis equal the inverse of camera lens reduction magnification.
3, the coaxial alignment system in the projection lithography according to claim 1 is characterized in that: the optical system in the described lithographic projection imaging system (a1) has the image reduction magnification more than or equal to 1.
4, the coaxial alignment system in the projection lithography according to claim 1 and 2 is characterized in that: described lithographic projection imaging system (a1) can see through visible light and 365nm ultraviolet and the deep UV (ultraviolet light) to the 193nm wavelength.
5, the coaxial alignment system in the projection lithography according to claim 1, it is characterized in that: described laser illuminator system (a2) comprises can provide visible light to arrive the infrared single wavelength or the laser instrument and the half-reflecting half mirror of multi-wavelength illumination light, obtains suitable illumination light incident angle by the angle of regulating half-reflecting half mirror.
6, the coaxial alignment system in the projection lithography according to claim 1 or 5 is characterized in that: the incident angle of the illumination light in the described laser illuminator system (a2) makes 0 grade of light transmission diffraction grating in the order of diffraction that the reflective diffraction gratings mark produces time also enter the projecting etching imaging system.
7, the coaxial alignment system in the projection lithography according to claim 5, it is characterized in that: the illumination light in the described laser illuminator system (a2) is 3 °-18 ° in the incident angle of mask (a3) face, and this incident angle approximates the angle, Littrow of the grating marker on the mask.
8, the coaxial alignment system in the projection lithography according to claim 1 is characterized in that: the dutycycle of the grating of the reflective diffraction gratings mark (a6) on the described mask (a3), promptly the ratio of grating lightproof part and grid seam is not less than 1.
9, the coaxial alignment system in the projection lithography according to claim 1 is characterized in that: described aligning imaging system (a8) has the numerical aperture less than 0.1.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101876538A (en) * | 2010-05-07 | 2010-11-03 | 中国科学院光电技术研究所 | Method for measuring clearance in proximity nanometer lithography |
| CN101968611A (en) * | 2010-09-08 | 2011-02-09 | 中国科学院光电技术研究所 | Phase distribution-based single point mask silicon wafer leveling method |
| CN102141738A (en) * | 2011-04-02 | 2011-08-03 | 中国科学院光电技术研究所 | Nanometer-level automatic focusing system for projection lithography |
| CN105057228A (en) * | 2015-08-05 | 2015-11-18 | 罗颖 | Connector pin needle hole online detection device |
| CN108036732A (en) * | 2017-11-30 | 2018-05-15 | 中国科学院光电技术研究所 | A kind of gap detection device based on super resolution lithography |
| CN110103015A (en) * | 2019-04-28 | 2019-08-09 | 西安交通大学 | It is a kind of for by multichannel sample introduction valve body zero-bit and grating encoder zero-bit to positive aligning device and its application method |
| CN110553583A (en) * | 2018-05-31 | 2019-12-10 | 佳能株式会社 | Inspection apparatus, inspection method, imprint apparatus, planarization apparatus, and article manufacturing method |
| CN113655695A (en) * | 2021-09-02 | 2021-11-16 | 西华大学 | Composite photoetching alignment system and method based on medium microsphere super-resolution imaging |
-
2009
- 2009-08-14 CN CN2009100909210A patent/CN101639630B/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101876538A (en) * | 2010-05-07 | 2010-11-03 | 中国科学院光电技术研究所 | Method for measuring clearance in proximity nanometer lithography |
| CN101968611A (en) * | 2010-09-08 | 2011-02-09 | 中国科学院光电技术研究所 | Phase distribution-based single point mask silicon wafer leveling method |
| CN102141738A (en) * | 2011-04-02 | 2011-08-03 | 中国科学院光电技术研究所 | Nanometer-level automatic focusing system for projection lithography |
| CN102141738B (en) * | 2011-04-02 | 2012-09-19 | 中国科学院光电技术研究所 | Nanometer-level automatic focusing system for projection lithography |
| CN105057228A (en) * | 2015-08-05 | 2015-11-18 | 罗颖 | Connector pin needle hole online detection device |
| CN108036732A (en) * | 2017-11-30 | 2018-05-15 | 中国科学院光电技术研究所 | A kind of gap detection device based on super resolution lithography |
| CN110553583A (en) * | 2018-05-31 | 2019-12-10 | 佳能株式会社 | Inspection apparatus, inspection method, imprint apparatus, planarization apparatus, and article manufacturing method |
| CN110553583B (en) * | 2018-05-31 | 2021-11-16 | 佳能株式会社 | Inspection apparatus, inspection method, imprint apparatus, planarization apparatus, and article manufacturing method |
| CN110103015A (en) * | 2019-04-28 | 2019-08-09 | 西安交通大学 | It is a kind of for by multichannel sample introduction valve body zero-bit and grating encoder zero-bit to positive aligning device and its application method |
| CN110103015B (en) * | 2019-04-28 | 2020-06-19 | 西安交通大学 | Alignment device for aligning zero position of valve body of multi-path sample injection valve with zero position of grating code disc and use method of alignment device |
| CN113655695A (en) * | 2021-09-02 | 2021-11-16 | 西华大学 | Composite photoetching alignment system and method based on medium microsphere super-resolution imaging |
| CN113655695B (en) * | 2021-09-02 | 2023-11-07 | 西华大学 | Composite photoetching alignment system and method based on medium microsphere super-resolution imaging |
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| CN101639630B (en) | 2011-04-20 |
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