CN103926799B - A kind of focusing leveling measuring method - Google Patents
A kind of focusing leveling measuring method Download PDFInfo
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- CN103926799B CN103926799B CN201310009894.6A CN201310009894A CN103926799B CN 103926799 B CN103926799 B CN 103926799B CN 201310009894 A CN201310009894 A CN 201310009894A CN 103926799 B CN103926799 B CN 103926799B
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Abstract
The present invention proposes a kind of focusing leveling measuring method, goes out two beams measurement light with identical incident angles to silicon chip surface same position by same light source beam splitting, forms the different reflected light of two beams, it is characterised in that this method comprises the following steps：Step 1：Light source beam splitting；Step 2：Optical signal after beam splitting incides silicon chip face same position with equal angular different directions；Step 3：Measure two beam reflected light light intensity；Step 4：Fourier transform is carried out after the two beams reflected light light intensity signal is normalized respectively, a frequency-doubled signal is extracted and takes average, defocusing amount is calculated according to the mapping relations between a frequency-doubled signal average and silicon chip defocusing amountΔZ.Compared with prior art, this invention removes the Technological adaptability ability for due to influence of the silicon chip surface reflectivity heterogeneity to focusing and leveling measurement result, more effectively improving focusing and leveling technology.
Description
Technical field
The present invention relates to a kind of integrated circuit equipment manufacturing field, more particularly to a kind of focusing and leveling for lithographic equipment
Measuring method.
Background technology
Projection mask aligner can be differentiated by reducing exposure wavelength and increasing the numerical aperture of projection objective to improve photoetching
Rate, but available depth of focus can be caused to be decreased obviously simultaneously, silicon chip surface is easier that defocus occurs.In order to solve because depth of focus reduces band
The defocus problem come, high-end projection litho machine control height and the inclination of silicon chip surface in real time using focusing and leveling technology.Adjust
Burnt leveling technology includes the focusing and leveling e measurement technology of silicon chip surface and the technique of real-time control of silicon chip surface position.Silicon chip focusing
Leveling e measurement technology measures to the height of silicon chip surface and inclination, and its measurement data is used for dynamic feedback control silicon chip surface
Relative to the position between the optimal focal plane of projection objective.
Premise and basis of the silicon chip surface focusing and leveling e measurement technology for silicon chip surface position technique of real-time control, Ke Yifen
For several methods such as barometric surveying, capacitance measurement and optical measurement.The principle of wherein measuring method be by detect light with
Big incidence angle is irradiated to silicon chip surface, and detection reflection optical position obtains the positional information of silicon chip surface.
In the actual focusing and leveling measurement process of silicon chip, the diverse location reflectivity of silicon chip surface be it is different, because
This measurement facula information can be made measurement result produce deviation, cause to focus by the heteropical influence of silicon chip surface reflectivity
Undesirable, the quality of reduction photoetching process figure of levelling effect.
The content of the invention
It is an object of the invention to propose a kind of focusing leveling measuring method, overcome because silicon chip surface reflectivity is non-homogeneous
Influence of the property to focusing and leveling measurement result.
In order to realize foregoing invention purpose, the present invention proposes a kind of focusing leveling measuring method, gone out by same light source beam splitting
Two beams measure light with identical incident angles to silicon chip surface same position, form the different reflected light of two beams, its feature
It is, this method comprises the following steps：
Step 1：Light source beam splitting；
Step 2：Optical signal after beam splitting incides silicon chip face same position with equal angular different directions；
Step 3：Measure two beam reflected light light intensity；
Step 4：Fourier transform is carried out after the two beams reflected light light intensity signal is normalized respectively, is carried
Take a frequency-doubled signal and take average, defocusing amount is calculated according to the mapping relations between a frequency-doubled signal average and silicon chip defocusing amountΔ Z。
Wherein, in the step 3, signal gathering unit periodically collection reflective light intensity information.
The present invention also proposes a kind of focusing and leveling measurement apparatus, for lithographic exposure systems, it is characterised in that by same light
The light beam of source outgoing forms two beams after beam splitting and measures light with identical incident angles to silicon chip surface same position, and is formed
The different reflected light of two beams；Two beam reflected lights respectively enter corresponding signal gathering unit.
Wherein, two beam measures light without projection objective light path.
More preferably, in addition to first, second measurement branches, the one the second measurement branches structure is identical, includes respectively
First speculum, beam splitting unit, the second speculum, slit, first, second measurement branches enter the two beams measurement light respectively
The same position of silicon chip surface is mapped to, the two beams reflected light enters described corresponding via the second, first measurement branches respectively
Signal gathering unit.
Compared with prior art, this invention removes focusing and leveling is surveyed due to silicon chip surface reflectivity heterogeneity
The influence of result is measured, more effectively improves the Technological adaptability ability of focusing and leveling technology.
Brief description of the drawings
It can be obtained further by following detailed description of the invention and institute's accompanying drawings on the advantages and spirit of the present invention
Solution.
Fig. 1 is focusing and leveling measuring principle index path of the present invention；
Fig. 2 is focusing leveling measuring method flow chart of the present invention；
Fig. 3 is a kind of typical technique silicon chip surface film structure；
Fig. 4 is the scan variations curve of light intensity signal that detector collects in the case of silicon chip surface reflectivity is uniform；
Fig. 5 is the scan variations curve of light intensity signal that detector collects when silicon chip surface reflectivity is uneven；
Fig. 6 is the two-way light intensity signal curve collected using the focusing leveling measuring method of the present invention.
Embodiment
The specific embodiment that the invention will now be described in detail with reference to the accompanying drawings.
Single beam measurement light is used to measure single beam flare letter with large angle incidence to silicon chip surface in traditional measurement scheme
Silicon chip surface defocusing amount is calculated in breath.Due to the influence that silicon chip surface reflectivity heterogeneity is brought, can make to measure anti-
Penetrate spot signal and produce deviation, so as to which correct defocusing amount result can not be calculated.
In order to solve produced problem in traditional scheme, it is proposed that a kind of new focusing leveling measuring method.This method
Two beams measurement light is gone out with identical incident angles to silicon chip surface same position by same light source beam splitting, it is different to form two beams
Reflected light, gather the processing of this two-beam signal of change, extract the defocusing amount size of silicon chip surfaceΔZ。
Fig. 1 is the light channel structure schematic diagram that the present invention uses.As shown in figure 1, light source 1 sends illumination light, after beam splitting respectively
Reflected from the both sides of projection objective 8 into speculum 2a, 2b, then be irradiated to light with identical incidence angle by speculum 3a, 3b
The surface of silicon chip 4, silicon chip face reflection light is again by, to beam splitting unit 5a, 5b, optical signal passes through after beam splitting after speculum 3a, 3b reflection
Slit 6a, 6b arriving signal collecting unit 7a, 7b.
Silicon chip technique can cause flare Energy distribution inhomogeneities, so that the energy barycenter of flare occurs partially
Move.In slit 6a, 6b positions, the light spot energy barycenter offset direction caused by technique and caused by silicon chip surface defocus
Spot motion direction is respectively consistent and opposite.So defocusing amount difference is calculated according to the measurement signal of two detectors
Include a positive error and a negative error.Then to after two results averageds mistake can be measured caused by subtractive processes
Difference.
Fig. 2 is focusing leveling measuring method flow chart of the present invention, is comprised the following steps：Step 1：Light source beam splitting, light source point
Beam is in order to avoid due to being had an impact using different light sources to result of calculation；Step 2：Optical signal after beam splitting passes through twice
After reflection silicon chip face same position is incided with equal angular different directions；Step 3：Measure two beam reflected light informations；Step
Four：Calculating takes average to extract defocusing amount, and calculating extraction according to the different reflected light information of two beams by optical signal processing unit obtains
The numerical result of silicon chip defocusing amount size.
Fig. 3 is a kind of typical silicon chip surface film structure（Cu and fluorine silica glass FSG periodic structures）, for illustrating to adjust
A kind of Typical process conditions in burnt leveling sensor FLS measurement process, just exist due to silicon chip table in this process conditions
Influence caused by the reflectivity heterogeneity of face.
FLS processes are emulated, add silicon chip surface reflectivity Heterogeneous distribution function, signal gathering unit cycle
Property collection reflective light intensity information, carry out Fourier transform after light intensity signal is normalized, extract a frequency-doubled signal, root
Defocusing amount is calculated according to the mapping relations between a frequency-doubled signal and silicon chip defocusing amountΔZ。The method used in the present invention is collection
Two optical path signals, average is taken after processing by a Clock Multiplier Factor, and silicon chip defocusing amount is calculated by the valueΔZSize.
Fig. 4 is scan variations curve of the light intensity signal that collects of detector in the case of silicon chip surface reflectivity is uniform,
Scan period 1kHz, to obtain a Clock Multiplier Factor be 1.5220e+004 after light intensity signal normalization frequency-domain transform.When silicon chip surface is anti-
Penetrate rate it is uneven when, the light intensity signal that collects is as shown in figure 5, produce the obvious deviation with preferable light intensity signal in Fig. 4, one times
Frequency coefficient is 1.4194e+004, it is impossible to obtains correct defocusing amount result of calculation.Using new FLS measuring methods, increase is all the way
The optical path of symmetry angle, the two-way light intensity signal curve collected is as shown in fig. 6, the frequency multiplication obtained after frequency-domain transform
Coefficient signal composition is respectively 1.4194e+004 and 1.6246e+004, and it is 1.5220 e+004 to take after average, with silicon chip surface
Result of calculation in the case of reflectivity is uniform is identical, so as to eliminate the influence that silicon chip surface reflectivity heterogeneity is brought.
The preferred embodiment of the simply present invention described in this specification, above example is only illustrating the present invention
Technical scheme rather than limitation of the present invention.All those skilled in the art pass through logic analysis, reasoning under this invention's idea
Or the limited available technical scheme of experiment, all should be within the scope of the present invention.
Claims (2)
1. a kind of focusing leveling measuring method, two beams are gone out by same light source beam splitting and measure light with identical incident angles to silicon
Piece surface same position, form the different reflected light of two beams, it is characterised in that this method comprises the following steps：
Step 1：Light source beam splitting；
Step 2：Optical signal after beam splitting incides silicon chip face same position with equal angular different directions；
Step 3：Measure two beam reflected light light intensity；
Step 4：Fourier transform, extraction one are carried out after the two beams reflected light light intensity signal is normalized respectively
Frequency-doubled signal simultaneously takes average, measurement error caused by subtractive processes, according between a frequency-doubled signal average and silicon chip defocusing amount
Mapping relations calculate defocusing amountΔZ, measurement error caused by the technique is because silicon chip technique causes flare energy point
Cloth inhomogeneities, so that the energy barycenter of flare shifts and caused error.
2. focusing leveling measuring method as claimed in claim 1, it is characterised in that in the step 3, signal gathering unit
Periodically collection reflective light intensity information.
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| CN201310009894.6A CN103926799B (en) | 2013-01-11 | 2013-01-11 | A kind of focusing leveling measuring method |
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| CN201310009894.6A CN103926799B (en) | 2013-01-11 | 2013-01-11 | A kind of focusing leveling measuring method |
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| CN103926799B true CN103926799B (en) | 2018-02-06 |
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| CN104165596B (en) * | 2014-09-02 | 2017-01-25 | 南京中科神光科技有限公司 | Method and system for measuring defocusing amount |
| CN105806239B (en) * | 2016-05-16 | 2018-07-24 | 北京控制工程研究所 | A kind of laser scan type star sensor defocus quantity measuring method |
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| KR0132269B1 (en) * | 1994-08-24 | 1998-04-11 | 이대원 | Alignment apparatus of stepper and control method therefor |
| DE4434822C1 (en) * | 1994-09-29 | 1996-01-11 | Schott Glaswerke | Optical thickness measuring device for transparent objects |
| JP2002156578A (en) * | 2000-11-20 | 2002-05-31 | Olympus Optical Co Ltd | Focus detector as well as objective lens, optical microscope or optical test apparatus having the same |
| CN101276160B (en) * | 2008-05-09 | 2010-09-15 | 上海微电子装备有限公司 | Focusing and leveling device for photo-etching machine as well as measuring method |
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Address after: 201203 Shanghai Zhangjiang High Tech Park of Pudong New Area Zhang Road No. 1525 Applicant after: Shanghai microelectronics equipment (Group) Limited by Share Ltd Address before: 201203 Shanghai Zhangjiang High Tech Park of Pudong New Area Zhang Road No. 1525 Applicant before: Shanghai Micro Electronics Equipment Co., Ltd. |
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