CN103217873A - Focus detecting device based on double-grating moire fringes - Google Patents
Focus detecting device based on double-grating moire fringes Download PDFInfo
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- CN103217873A CN103217873A CN2013101625956A CN201310162595A CN103217873A CN 103217873 A CN103217873 A CN 103217873A CN 2013101625956 A CN2013101625956 A CN 2013101625956A CN 201310162595 A CN201310162595 A CN 201310162595A CN 103217873 A CN103217873 A CN 103217873A
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Abstract
The invention relates to a focus detecting device based on double-grating moire fringes. The focus detecting device comprises an incident beam, an extender lens, an object grating, wedge-shaped plates, 4f projection systems, rhombic prisms, a detecting grating and a detector, wherein incident light is perpendicularly projected on the object grating by the extender lens; the 4f systems couple an image of the object grating with the detecting grating to form the moire fringes; the height of a silicon wafer can be obtained by detecting movement of the moire fringes; and inclination of the two gratings in the imaging process can be compensated by matching of a double-wedge mirror. The focus detecting device can achieve high-precision and non-contact measurement of the defocusing amount of the silicon wafer.
Description
Technical field
The present invention relates to a kind of focusing test device, be used to measure silicon chip defocusing amount in vertical direction, belong to the high-precision optical fields of measurement based on the double grating Moire fringe.
Background technology
From the commitment of microelectronics industry development, optical lithography just becomes the mainstream technology of volume production integrated circuit.Optical resolution develops into submicron order, deep-submicron from micron order, and prediction can reach 32nm and even 22nm node.But the optical lithography method that rely on to shorten wavelength and increase numerical aperture is faced with the huge difficult problem that the required huge cost of lithographic equipment under sharp increase, especially the 32nm node of technical very big difficult point and cost has become this field.
And be cost by always shortening exposure wavelength and increase numerical aperture when improving resolving power to sacrifice depth of focus, from the depth of focus formula as can be seen, along with the shortening of exposure wavelength and the raising of numerical aperture, the depth of focus of projection objective is little by little shortening.Though the trend of this shortening is alleviated by increasing process factor k2, need are through PROCESS FOR TREATMENT many times usually for the silicon chip that exposes on production line, so the increase of process factor k2 also is limited.In recent years in the world the depth of focus of state-of-the-art projection mask aligner greatly about the magnitude of hundreds of nanometers.So have only by leveling and focusing and make full use of depth of focus.Generally at 1/10 of effective depth of focus, i.e. the sensitivity of tens nanometer, thereby focusing test should be in nanometer scale to the requirement of the focusing repeatability precision of leveling and focusing system for etching system.
In nano-photoetching, the consistance of CD (Critic (a) l Dimension) is very important performance index
,It directly has influence on the yield rate of alignment success ratio and electronic product.Especially in 32nm and the optical lithography with lower node, the high precision of defocusing amount control and defocusing amount, the detection of high real-time become the most important thing in the lithography measurements undoubtedly.
Be subject to the low situation of domestic litho machine resolving power, what the focusing test technology on its optical projection printing litho machine mainly adopted is slit projecting video image technology.The focusing test incident beam is amplified on the CCD through the silicon chip catoptric imaging by slit, slit image is handled obtaining the height and position of silicon chip with respect to projection objective again, and its focusing test precision reaches 200nm.Comparing with external focusing test technology has very big gap.Therefore press for the new focusing test device of development to realize the focusing test of high precision nanoscale.
Summary of the invention
The technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, a kind of focusing test device based on the double grating Moire fringe is provided, realize that the defocusing amount of high precision, non-cpntact measurement silicon chip is measured.
The technology of the present invention solution: a kind of focusing test device based on the double grating Moire fringe, for realizing the defocusing amount of high precision, non-cpntact measurement silicon chip, based on the reflective triangulation method of focusing test device employing of double grating Moire fringe.Incident beam, is received with detector at opposite side by silicon chip surface with bigger incident angle irradiation.The grating fringe information that collects according to detector can calculate the defocusing amount of silicon chip in vertical direction; Specifically comprise: incident light source 101, extender lens 102, thing grating 103, a pair of clapboard 104, a 4f optical projection system 105, the 2nd 4f optical projection system 105 ', rhombic prism 106, detection grating 103 ' and detector 107; Incident light source 101 outgoing are wide spectral light, this light beam process extender lens (102) vertical incidence is on thing grating (103), a pair of clapboard (104) is placed perpendicular to the incident light optical axis, is used for the non-normal incidence angle between indemnity grating 103 and the incident beam 101; Thing grating 103 is positioned on the front focal plane of first 4f optical projection system 105, and the picture of thing grating 103 is projected in silicon chip 202 surfaces by 4f projection objective 105 through rhombic prism 106 deviations, and rhombic prism 106 can make the optical axis translation, but does not change optical axis direction; Second 4f projection objective 105 ' is projected in 103 pictures of the thing grating on the silicon chip 202 and detects in the plane, grating 103 ' place; When silicon chip 202 the picture of Z thing grating 103 when being moved will with detect grating 103 ' the formation Moire fringe that relatively moves, detector 107 is gathered the Moire fringe image that double gratings relatively move and produced, by the analysis diagram picture obtain silicon chip Z to defocusing amount.
Described thing grating 103 and detection approaching amplitude grating of 103 ' employing cycle of grating utilize the optics enlarge-effect of Moire fringe to carry out the focal plane detection.
The present invention's beneficial effect compared with prior art is:
(1) the present invention adopts close thing grating and the superimposed formation Moire fringe of detection grating of cycle, utilizes this optics amplification of Moire fringe to detect silicon chip in the defocusing amount that Z makes progress, and has realized high precision, non-cpntact measurement.
(2) the present invention has also introduced the angle problem after a pair of clapboard is used for indemnity grating picture and detects the grating stack, makes that measurement is more accurate.
(3) the present invention utilizes rhombic prism to carry out light beam translation in addition, and this prism does not change the direction of propagation of light beam, and it is easier to make it debug, and has strengthened to environmental perturbation the antijamming capability of physical construction vibrations.
Description of drawings
Fig. 1 is a double grating focusing test device synoptic diagram of the present invention;
Fig. 2 (a) is for being respectively the side view and the vertical view of clapboard among the present invention;
Fig. 2 (b) is respectively through 180 ° of postrotational double-wedge plate 104 side views and vertical view among the present invention;
Fig. 3 is a rhombic prism synoptic diagram used in the present invention.
Embodiment
For making purpose of the present invention, organization plan and beneficial effect more clear, the present invention is described in further details below in conjunction with accompanying drawing.
As shown in Figure 1, double grating Moire fringe focusing test device of the present invention adopts the method for triangle incident, incident light source 101 outgoing are wide spectral light, this light beam is incident on silicon chip 202 surfaces with the wide-angle (the present invention adopts 84 °) that can guarantee total reflection, be detected device 107 through thing grating 103 and the modulation that detects grating 103 ' and receive, the Moire fringe that detector 107 receives comprise silicon chip 202 Z to defocusing amount.
Whole device is made up of incident light source 101, extender lens 102, thing grating 103, clapboard 104,4f optical projection system 105 and 105 ', rhombic prism 106, detection grating 103 ' and detector 107.The broad spectrum light source that incident light source 101 adopts away from the photo-etching machine exposal optical source wavelength utilizes extender lens 102 to expand the even illumination in bundle back on thing grating 103.The front focal plane of optical projection system 105 is positioned at plane, thing grating 103 place, and back focal plane is positioned at silicon chip 202 surfaces, and the front focal plane of optical projection system 105 ' is positioned at silicon chip 202 surfaces, and back focal plane is positioned at and detects plane, grating 103 ' place.When there was vertical direction (Z to) out of focus in silicon chip, the picture of thing grating 103 can be subjected to displacement with respect to detecting grating 103 '.The pass of relative displacement Δ Z and defocusing amount Δ X be Δ Z=sin2 (90 °-θ)/(90 °-θ) * Δ X of sin.The different stacks with the detection 103 ' cycle of grating of thing grating 103 can produce Moire fringe, and detector 107 is gathered the stripe pattern of Moire fringes, can obtain Δ Z through processing, and then calculate defocusing amount Δ X.
What describe in Fig. 2 (a), Fig. 2 (b) is that clapboard 104 changes the beam direction schematic diagram, be respectively clapboard 104 side views and vertical view among Fig. 2 (a), and two clapboard 104 stack backs do not have change to incident light source 101 directions, and a side-play amount is only arranged in the horizontal direction.Be respectively among Fig. 2 (b) through 180 ° of postrotational double-wedge plate 104 side views and vertical view, and make incident beam 101 direction deviations 2 θ angles after 104 stacks of two clapboards.By rotating two clapboards 104 light beam deviation angle is freely switched between 0～2 θ, compensated the angle between thing grating 103 pictures and the detection grating 103 ', avoided thing grating 103 pictures and detected the Moire fringe cycle variation that causes when there is angle in grating 103 ', made that the Moire fringe image of measuring is more accurate.
Fig. 3 is described to be the device rhombic prism 106 that makes incident light source 101 translations.Emergent light 101 when the vibrations of environmental perturbation or physical construction cause the rotation of rhombic prism 106 " outgoing light source 101 ' direction when not rotating with rhombic prism 106 is identical.The antijamming capability that the present invention has strengthened the focusing test device is simultaneously debug rhombic prism 106 when the system of establishment also very convenient.
Claims (2)
1. the focusing test device based on the double grating Moire fringe is characterized in that comprising: incident light source (101), extender lens (102), thing grating (103), a pair of clapboard (104), a 4f optical projection system (105), the 2nd 4f optical projection system (105 '), rhombic prism (106), detection grating (103 ') and detector (107); Incident light source (101) outgoing is wide spectral light, this light beam process extender lens (102) vertical incidence is on thing grating (103), a pair of clapboard (104) is placed perpendicular to the incident light optical axis, is used for the non-normal incidence angle between indemnity grating (103) and the incident beam (101); Thing grating (103) is positioned on the front focal plane of first 4f optical projection system (105), the picture of thing grating (103) is projected in silicon chip (202) surface by 4f projection objective (105) through rhombic prism (106) deviation, rhombic prism (106) can make the optical axis translation, but does not change optical axis direction; Second 4f projection objective (105 ') detects the thing grating (103) on the silicon chip (202) in the plane, grating (103 ') place as being projected in; When silicon chip (202) the picture of Z thing grating (103) when being moved will with detect grating (103 ') the formation Moire fringe that relatively moves, detector (107) is gathered the Moire fringe image that double grating relatively moves and produced, by the analysis diagram picture obtain silicon chip Z to defocusing amount.
2. a kind of focusing test device according to claim 1 based on the double grating Moire fringe, it is characterized in that: described thing grating (103) and detection approaching amplitude grating of grating (103 ') employing cycle, utilize the optics enlarge-effect of Moire fringe to carry out the focal plane detection.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104165596A (en) * | 2014-09-02 | 2014-11-26 | 南京中科神光科技有限公司 | Method and system for measuring defocusing amount |
| CN107643162A (en) * | 2017-08-28 | 2018-01-30 | 南京理工大学 | A kind of scaling method of double grating focimeter |
| CN111656260A (en) * | 2018-01-24 | 2020-09-11 | 赛博光学公司 | Structured light projection for mirrored surfaces |
| CN114688972A (en) * | 2020-12-31 | 2022-07-01 | 深圳中科飞测科技股份有限公司 | Detection device and detection method thereof |
| WO2023020324A1 (en) * | 2021-08-17 | 2023-02-23 | 深圳市卡提列光学技术有限公司 | Automatic focusing system |
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| US20020000520A1 (en) * | 2000-04-12 | 2002-01-03 | Toru Kawaguchi | Surface position detection device and exposure apparatus and exposure method achieved by utilizing detection device |
| CN101187783A (en) * | 2007-12-07 | 2008-05-28 | 上海微电子装备有限公司 | Focusing and leveling measuring system and its measuring method |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104165596A (en) * | 2014-09-02 | 2014-11-26 | 南京中科神光科技有限公司 | Method and system for measuring defocusing amount |
| CN107643162A (en) * | 2017-08-28 | 2018-01-30 | 南京理工大学 | A kind of scaling method of double grating focimeter |
| CN107643162B (en) * | 2017-08-28 | 2019-08-09 | 南京理工大学 | A kind of scaling method of double grating focimeter |
| CN111656260A (en) * | 2018-01-24 | 2020-09-11 | 赛博光学公司 | Structured light projection for mirrored surfaces |
| CN114688972A (en) * | 2020-12-31 | 2022-07-01 | 深圳中科飞测科技股份有限公司 | Detection device and detection method thereof |
| CN114688972B (en) * | 2020-12-31 | 2024-04-02 | 深圳中科飞测科技股份有限公司 | Detection device and detection method thereof |
| WO2023020324A1 (en) * | 2021-08-17 | 2023-02-23 | 深圳市卡提列光学技术有限公司 | Automatic focusing system |
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Application publication date: 20130724 |