CN103940337A - OCD testing system for critical sizes of micro-structure on basis of micro light spot parallel beam - Google Patents
OCD testing system for critical sizes of micro-structure on basis of micro light spot parallel beam Download PDFInfo
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- CN103940337A CN103940337A CN201410165437.0A CN201410165437A CN103940337A CN 103940337 A CN103940337 A CN 103940337A CN 201410165437 A CN201410165437 A CN 201410165437A CN 103940337 A CN103940337 A CN 103940337A
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Abstract
The invention discloses an OCD testing system for critical sizes of a micro-structure on the basis of a micro light spot parallel beam. The OCD testing system for the critical sizes of the micro-structure on the basis of the micro light spot parallel beam comprises a light source, a compressing lens set, a periodic structure to be tested, a detector and a data processor. The light source stimulates parallel light with the light spot diameter ranging from 4.9 mm to 5.1 mm, the light beam is compressed into parallel light with the diameter ranging from 49 micrometers to 51 micrometers through the compressing lens set, the parallel light enters the surface of the periodic structure to be tested on a containing table, reflection is achieved, the detector detects and extracts parameters of reflected light, finally the parameters of the reflected light are optimized and analyzed through electromagnetic analog/analysis software of the data processor, and the critical sizes of the structure to be tested are developed reversely. The OCD testing system for the critical sizes of the micro-structure on the basis of the micro light spot parallel beam can directly improve the precision and speed greatly for testing of small-size structures through the OCD testing system.
Description
Technical field
The invention belongs to semiconductor microactuator electronic measurement field, relate to optical critical dimension (OCD) test macro of realizing the incident of low-light spot parallel beam.
Technical background
In semiconductor and other microelectronic industrys, chip is being realized the desired structure of deviser by process equipment with processing after integrated circuit (IC) design person's design.The integrated level of chip is very high, need to its structure (Pattern) be realized in chip by series of process such as plate-making, photoetching, etchings, so the structure on chip is substantially all periodic arrangement.But after technique is made, can critical size wherein (CD) meet design requirement needs to test/analyze.Such test/analysis all needs to do after each operation stage and technique complete, and therefore concerning chip manufacturing, is extremely important.The method of CD test/analysis has multiple, as: adopt scanning electron microscope (SEM), atomic force microscope (AFM) etc., but the technology of these microscope tests or vacuum environment that need to be complicated, or can only realize the partial analysis of effects on surface profile, cannot realize the test to non-superficial layer (underlay) in sandwich construction, the more impossible online detection realizing in production run.Adopt optical instrument to CD test/analyze (being commonly referred to OCD) can realize online detection, it is simple to the requirement of test environment, and analysis that can be to non-surface layer structure, therefore becomes CD test/topmost technological means in analyzing.This technology is the developing history of existing two more than ten years in the world, early stage OCD test is as long as adopt common light beam (grade diameter) just can realize, electric field simulation in analytical technology adopts the approximate of scalar analysis, the method proposes (Journal of Electrochemical Socity by people such as Haimann the earliest, v.131, p.881, 1984), afterwards by people (International Conference on Characterization and Metrology for ULSI Technology such as the people such as Maynard (Journal of vacuum Science and Technology) and Lee, Gaithersburg, MD, p.23-27, Mar.1998) in industrial community, be applied, Li etc. have made some improvements method in this in US Patent No. Patent7212293B1.But the raising along with integrated level, physical dimension in microstructure is more and more less, and scalar is analyzed this approximation method and has been difficult to meet the need, more accurately reflects the rigorous method of various diffraction information---and-time-vector method is generally adopted, comprising Coupled Wave Analysis method (RCWA, Moharam etc., Journal of Optical Society of America, A12, n.5, p.1068-1076,1995), and frequency domain, Finite-Difference Time-Domain Method etc.In addition also have some enterprises to adopt some new approximation methods, but the modeling algorithm of nearly all OCD of being applied to all to suppose light source be directional light.Along with take the development of the microelectric technique that SIC (semiconductor integrated circuit) is representative, not only in structure, size is more and more less, and allows the area of test also to reduce.Therefore need corresponding the reducing of hot spot of test macro.The current method of converging beam that generally adopts reduces hot spot, allows test position be positioned at the hot spot point of focusing.But this way is discrepant (directional light that actual light source is no longer supposed for analog light source) with the software analysis model based on modeling algorithm, and this will directly affect test/precision of analysis.In engineering reality, be often all to adopt some approximation method corrects, but normally greatly increased the complicacy of calculating in analytic process, had a strong impact on the efficiency of system works; And in OCD test/analytic system, precision and efficiency are two large key issues, in order to raise the efficiency, adopt these approximation methods need to increase the input on a lot of hardware, even sometimes have to sacrifice some precision for efficiency.Therefore the test macro that, can directly realize low-light spot directional light seems extremely important.
Summary of the invention
For traditional OCD measuring technique, along with the development of integrated technology, the size of microstructure is more and more less.Mainly contain at present the difficulty of two aspects: the one, the restriction of optical diffraction limit; The 2nd, spot size is excessive with respect to chip size, affects measuring accuracy and even cannot realize test/analysis.In order to overcome the excessive problem of spot size, generally adopt at present the type of focusing, although this has solved test problem, but the difference due to test macro and sunykatuib analysis model, under many circumstances, in the analytic process after test, need to expend the end product that a lot of time just can be tested/analyze more.In order to address this problem, the invention discloses a kind of microstructure critical size OCD test macro based on low-light spot parallel beam, make light source by cemented doublet group, become the directional light of beam diameter approximately 50 μ m, thereby reach the object that improves chip testing precision, shortens the numerical analysis time after testing.
System shown in Figure 1 is a kind of microstructure critical size OCD test macro based on low-light spot parallel beam of the present invention, comprises light source, compression lens combination, periodic structure to be measured, detecting device and data processor.The directional light that light source excitation glossing up diameter is 4.9-5.1mm, this light beam is compressed to by compression lens combination the directional light that diameter is 49-51 μ m, this directional light incides the Periodic structure surface to be measured of settling on platform, realize reflection, detecting device detects and extracts reflected light parameter, finally by electromagnetical analogies/analysis software optimization of data processor, analyze reflected light parameter, counter spreading out to treat the critical size of geodesic structure.
Consider level of processing and feasibility, Choice and process of the present invention is convenient for production and test easy optical element---spherical lens; Enough large for making incident light source can see through the operating wavelength range of compression lens combination, select to be applicable to the glass material of ultraviolet band.
As shown in Figure 2, cemented doublet group comprises first lens and the second lens, and two lens axis overlap, and whole clear aperture d is 3mm, and lens combination peripheral environment is air; First lens is placed in dipped beam source, and the second lens are placed in distance light source.
As shown in Figure 3, in first lens, the radius-of-curvature of the first surface 1-1 of dipped beam source is 15.63mm, and the radius-of-curvature of second surface 1-2 is 9.26mm, and the radius-of-curvature of the 3rd surperficial 1-3 is 1691.9mm; Material between first surface 1-1 and second surface 1-2 is lithium fluoride, and center thickness w3 is 28.78mm, and edge thickness w4 is 28.99mm; Between second surface 1-2 and the 3rd surperficial 1-3, material is calcium fluoride, and center thickness w5 is 1.13mm, and edge thickness w6 is 0.64mm.
As shown in Figure 4, in the second lens, the radius-of-curvature of the 4th surperficial 2-1 of close first lens is-56.38mm, the edge of the 5th surperficial 2-2 is plane, centre is sphere, and the radius-of-curvature of sphere is 2.21mm, and the 6th surperficial 2-3 edge is plane, centre is sphere, and the radius-of-curvature of sphere is 0.42mm.Between the 4th surperficial 2-1 and the 5th surperficial 2-2, material is quartzy, and center thickness w7 is 1mm, and edge thickness w8 is 3.29mm; Between the 5th surperficial 2-2 and the 6th surperficial 2-3, material is calcium fluoride, and center thickness w9 is 30mm, and edge thickness w10 is 28.21mm.
Between first lens and the second lens, be air, the centre distance w1 of two lens is 1mm, and Edge Distance w2 is 0.92mm.
In a kind of microstructure critical size OCD test macro based on low-light spot parallel beam of the present invention, the operating wavelength range of cemented doublet group is 190-1000nm; The present invention is realized and is different from the directional light low-light spot that background technology converges light hot spot by cemented doublet group, in test macro, directional light is differentiated with the spectral response of converging light, if adopt and converge light in OCD test macro, the analog computation based on directional light assumed conditions obviously has certain error so.And the error of analog computation is by carry over score analysis system, affects the accuracy of systematic analysis, thereby affect the measuring accuracy of OCD test macro.If realization meets the optical analog that converges of accuracy requirement, calculate, need to carry out directional light analog computation to converging a plurality of sampling spots of light, finally average.Conventionally calculate cone shape converging beam, need at least get five sampling points at its hot spot xsect, even more.This processing mode, how many residual some errors also, and also very serious on the impact of analysis efficiency.
Therefore the test macro that, the present invention directly realizes low-light spot parallel beam can improve precision and the speed of OCD test system and test small scale structures to a great extent.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of a kind of microstructure critical size OCD test macro based on low-light spot parallel beam of the present invention;
Fig. 2 cemented doublet group of the present invention schematic diagram;
Fig. 3 cemented doublet group of the present invention first lens schematic diagram;
Fig. 4 cemented doublet group the second lens schematic diagram of the present invention;
Fig. 5 background technology converges 0 grade of reflectance spectrum comparison diagram of light OCD test macro and a kind of microstructure critical size OCD test macro based on low-light spot parallel beam of the present invention;
Fig. 6 One Dimension Periodic structure light beam irradiates physical model figure;
Fig. 7 two-dimensionally periodic structure physical model figure.
In figure: 1. first lens, 2. the second lens, 1-1. first surface 1,1-2. second surface 2,1-3. the 3rd surface, 2-1. the 4th surface, 2-2. the 5th surface, 2-3. the 6th surface.
Embodiment
As shown in Figure 1, a kind of microstructure critical size OCD test macro based on low-light spot parallel beam, comprises light source, compression lens combination, periodic structure to be measured, detecting device and data processor.
As shown in Figure 2, cemented doublet group comprises first lens and the second lens, two lens center deads in line, and whole clear aperture d is 3mm, lens combination peripheral environment is air; First lens is placed in dipped beam source, and the second lens are placed in distance light source.
As shown in Figure 3, in first lens, the radius-of-curvature of the first surface 1-1 of dipped beam source is 15.63mm, and the radius-of-curvature of second surface 1-2 is 9.26mm, and the radius-of-curvature of the 3rd surperficial 1-3 is 1691.9mm; Material between first surface 1-1 and second surface 1-2 is lithium fluoride, and center thickness w3 is 28.78mm, and edge thickness w4 is 28.99mm; Between second surface 1-2 and the 3rd surperficial 1-3, material is calcium fluoride, and center thickness w5 is 1.13mm, and edge thickness w6 is 0.64mm.
As shown in Figure 4, in the second lens, the radius-of-curvature of the 4th surperficial 2-1 of close first lens is-56.38mm, the edge of the 5th surperficial 2-2 is plane, centre is sphere, and the radius-of-curvature of sphere is 2.21mm, and the 6th surperficial 2-3 edge is plane, centre is sphere, and the radius-of-curvature of sphere is 0.42mm.Between the 4th surperficial 2-1 and the 5th surperficial 2-2, material is quartzy, and center thickness w7 is 1mm, and edge thickness w8 is 3.29mm; Between the 5th surperficial 2-2 and the 6th surperficial 2-3, material is calcium fluoride, and center thickness w9 is 30mm, and edge thickness w10 is 28.21mm.
Between first lens and the second lens, be air, the centre distance w1 of two lens is 1mm, and Edge Distance w2 is 0.92mm.
In test macro, directional light is differentiated with the spectral response of converging light.Fig. 5 has 5 ° to converge the light at angle and the comparison of the lower 0 grade of reflectance spectrum of directional light condition of incidence.
The one-dimensional grating that the silicon of take is substrate, its physical model is as Fig. 6.Cycle is 500nm, and grating dutycycle is 1, and silicon and air respectively account for half of one-period, and grating thickness is 200nm, and the incident angle of its light is 10 degree, considers TE ripple, the plane of incidence of incident light perpendicular to the situation of one-dimensional grating lines (θ=10 °,
,?=90 °).
For above-mentioned example, the simulation of parallel incident light only needs to calculate the plane of an incident light perpendicular to the situation of one-dimensional grating lines
; And converge simulation that incident light meets accuracy requirement, to take 5 minimum sampling spots be example, needs to calculate cone angle condition of incidence twice
with the plane of three incident lights situation perpendicular to one-dimensional grating lines
.Calculate the plane of an incident light perpendicular to the situation of one-dimensional grating lines
approximately 2 seconds time, and calculate a cone angle incident
approximately 6.6 seconds time, therefore calculate the time of once converging 0 grade of reflectance spectrum of light and be about (2 * 6.6+3 * 2=) 19.2 seconds than approximately many ten times of the time 2s of 0 grade of reflectance spectrum of a directional light of calculating.
It is more than the example for one-dimentional structure, in engineering reality, more situation is two-dimensional structure (as Fig. 7), and it is a lot of that it calculates the upper complexity of wanting, adopt focused beam also can increase the more time in time, even may make test/analytic system be difficult to realize.Take in engineering reality that the most frequently used algorithm---rigorous couple-wave analysis method (RCWA) is example, the in the situation that of one dimension, therefore only, because only need consider that one direction diffraction effect need block the order of diffraction time of a dimension in the Fourier expansion process of algorithm, the required matrix exponent number of analog computation is less; And for two-dimensional periodic structure, needing to consider that the diffraction effect of both direction blocks the order of diffraction time of two dimensions, the needed matrix exponent number of analog computation reflectance spectrum will increase greatly.The required matrix to be processed of analog computation process of two-dimensional structure is much larger than one-dimentional structure, and approximately become 3 powers to increase with respect to one-dimentional structure its computing time.Therefore,, during directional light low-light spot OCD test system and test two-dimensional structure, with respect to converging the time that its analog computation of light OCD test macro saves, will be very considerable.
A kind of microstructure critical size OCD test macro based on low-light spot parallel beam of the present invention, makes its analog computation/optimization analytic process have more high-level efficiency, has greatly saved the time of whole test/analytic process.
Claims (3)
1. the microstructure critical size OCD test macro based on low-light spot parallel beam, comprise light source, compression lens combination, periodic structure to be measured, detecting device and data processor, it is characterized in that the directional light that light source excitation glossing up diameter is 4.9-5.1mm, this light beam is compressed to by compression lens combination the directional light that diameter is 49-51 μ m, this directional light incides the Periodic structure surface to be measured of settling on platform, realize reflection, detecting device detects and extracts reflected light parameter, finally by electromagnetical analogies/analysis software optimization of data processor, analyze reflected light parameter, counter spreading out to treat the critical size of geodesic structure.
2. a kind of microstructure critical size OCD test macro based on low-light spot parallel beam as claimed in claim 1, is characterized in that the lens in compression lens combination of the present invention are spherical lens; Material is the glass material that is applicable to ultraviolet band.
3. a kind of microstructure critical size OCD test macro based on low-light spot parallel beam as claimed in claim 1, it is characterized in that compressing lens combination and comprise first lens and the second lens, two lens axis overlap, and whole clear aperture is 3mm, and lens combination peripheral environment is air; First lens is placed in dipped beam source, and the second lens are placed in distance light source;
In first lens, the radius-of-curvature of the first surface of dipped beam source is 15.63mm, and the radius-of-curvature of second surface is 9.26mm, and the radius-of-curvature on the 3rd surface is 1691.9mm; Material between first surface and second surface is lithium fluoride, and center thickness is 28.78mm, and edge thickness is 28.99mm; Between second surface and the 3rd surface, material is calcium fluoride, and center thickness is 1.13mm, and edge thickness is 0.64mm;
In the second lens, the radius-of-curvature on the 4th surface of close first lens is-56.38mm that the edge on the 5th surface is plane, centre is sphere, and the radius-of-curvature of sphere is 2.21mm, and the 6th marginal surface is plane, centre is sphere, and the radius-of-curvature of sphere is 0.42mm.Between the 4th surface and the 5th surface, material is quartzy, and center thickness is 1mm, and edge thickness is 3.29mm; Between the 5th surface and the 6th surface, material is calcium fluoride, and center thickness is 30mm, and edge thickness is 28.21mm;
Between first lens and the second lens, be air, the centre distance of two lens is 1mm, and Edge Distance is 0.92mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410165437.0A CN103940337B (en) | 2014-04-23 | Micro structure critical size OCD based on low-light speckle collimated light beam tests system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410165437.0A CN103940337B (en) | 2014-04-23 | Micro structure critical size OCD based on low-light speckle collimated light beam tests system |
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| CN103940337A true CN103940337A (en) | 2014-07-23 |
| CN103940337B CN103940337B (en) | 2016-11-30 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107345788A (en) * | 2016-05-04 | 2017-11-14 | 中国科学院福建物质结构研究所 | A kind of directional light low-light spot optical critical dimension analytical equipment and detection method |
| CN108120371A (en) * | 2016-11-30 | 2018-06-05 | 中国科学院福建物质结构研究所 | Sub-wavelength dimensions microelectronic structure optical critical dimension method for testing and analyzing and device |
| CN110823089A (en) * | 2018-08-10 | 2020-02-21 | 睿励科学仪器（上海）有限公司 | Method and apparatus for measuring optical critical dimension of semiconductor device |
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| JPH0442117A (en) * | 1990-06-07 | 1992-02-12 | Olympus Optical Co Ltd | Confocal optical system |
| CN1255625A (en) * | 1998-12-02 | 2000-06-07 | 西门子公司 | Device and method for measuring critical measurement by ellipsometry |
| US7732109B2 (en) * | 2007-04-04 | 2010-06-08 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method and system for improving critical dimension uniformity |
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0442117A (en) * | 1990-06-07 | 1992-02-12 | Olympus Optical Co Ltd | Confocal optical system |
| CN1255625A (en) * | 1998-12-02 | 2000-06-07 | 西门子公司 | Device and method for measuring critical measurement by ellipsometry |
| US7732109B2 (en) * | 2007-04-04 | 2010-06-08 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method and system for improving critical dimension uniformity |
Non-Patent Citations (1)
| Title |
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| 田尧: "法向矢量耦合波分析法在微电子结构CD分析中的应用", 《中国优秀硕士学位论文全文数据库 信息科技辑》, no. 1, 15 January 2013 (2013-01-15) * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107345788A (en) * | 2016-05-04 | 2017-11-14 | 中国科学院福建物质结构研究所 | A kind of directional light low-light spot optical critical dimension analytical equipment and detection method |
| CN108120371A (en) * | 2016-11-30 | 2018-06-05 | 中国科学院福建物质结构研究所 | Sub-wavelength dimensions microelectronic structure optical critical dimension method for testing and analyzing and device |
| CN110823089A (en) * | 2018-08-10 | 2020-02-21 | 睿励科学仪器（上海）有限公司 | Method and apparatus for measuring optical critical dimension of semiconductor device |
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