CN1274074A - Confocal scan method for detecting surface shape of material - Google Patents
Confocal scan method for detecting surface shape of material Download PDFInfo
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- CN1274074A CN1274074A CN99113699A CN99113699A CN1274074A CN 1274074 A CN1274074 A CN 1274074A CN 99113699 A CN99113699 A CN 99113699A CN 99113699 A CN99113699 A CN 99113699A CN 1274074 A CN1274074 A CN 1274074A
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Abstract
A confocal scan method for detecting the surface shape of material includes measuring the response curve Q of the specimen to be detected in Z direction by means of confocal scan system, normalizing the Qi, finding out the slope S of linear segment ab on Q, measuring the light intensity I' at any point in segment ab, normalizing the I' by the maximal light intensity Imas obtained by said scan, measuring the longitunal depth on the surface of said speciment, and constituting its surface shape. It has high longitudinal resolution at nm class.
Description
The present invention is a kind of method of cofocus scanning test material face shape, is applicable to the detection of various solid-state material surface topographies.
Prior art
Because the fast development of X-ray image optics, Optical Disc Data Storage with Ultrahigh Density technology, capital large scale integrated circuit and ultraprecision engineering science in recent years, people opposite shape detect proposed horizontal differentiate to sub-micron, longitudinal resolution to nanometer even higher detection requirement.Horizontal and the longitudinal frame of the type that following table detects existing common surface topography, detection principle and use typical instrument compares.Measurement parameter in the table 1 is used for the surface topography of reconstruct sample.
The method of common several test material face shapes in table 1 prior art
| Type of detection | Principle | Used key instrument during detection | Measurement result | Best resolution characteristic | Relative merits | |
| Laterally | Vertically | |||||
| The Mechanical Contact formula | Diamond stylus | Blue gram Taylor's Ha Bosheng talysurf (Rank Tarlor Hob-son talystep) (prior art [1]) | The contact pilotage displacement | 5μm | 0.1nm | Measurement range is big; Price is low; The easy damaged surface; Detection time is long; |
| Optical non-contact | The twin-beam reflection | Bao Er (Bauer) contourgraph (prior art [2]) | Curvature | 2mm | 0.01nm | Injured surface not; Detection time short (removing the cofocus scanning interference technique); Lateral resolution is subject to the optical system diffraction; |
| The isochrome level is interfered | Fly section's isochrome level interferometer (FECO) (prior art [3]) | Spectrum | 0.3μm | 0.1nm | ||
| Differential is interfered relatively | Color graceful (Chapman MP) 2000 phase contrast interferometers (prior art [4]) | Slope | 5μm | 0.1nm | ||
| Rice draws (Mirau) to interfere | The color song of little Ke Tepu 3D interferometer (WYKO topO-3D) (prior art [5]) is newly looked 100 interferometers (Zygo Newview 100 (prior art [6]) | The position phase | 0.3μm | 0.1nm | ||
| Cofocus scanning is interfered | Cofocus scanning interferometer (prior art [7]) | Light intensity | 0.2μm | 0.1nm | ||
| The nano scanning probe | Scanning tunneling microscopic | Scanning tunnel microscope (prior art [8]) | Electric current | 50nm | ＜0.1nm | The resolution height: sweep velocity is slow; Cost an arm and a leg; Accurate contact measurement is to environment and sample requirement harshness; |
| Atomic force is micro- | Atomic force microscope (prior art [9]) | Power | 1nm | ＜0.1nm | ||
| Near field optic micro-(optical fiber probe) | Near-field Optical Microscope (prior art [10]) | Light intensity | 2nm | ＜0.1nm | ||
Above-mentioned prior art [1] is Talstep Step Height Measuring Instrument, TalydataComputer, and Nanosurftype Profiler manufactured by Rank Taylor Hobson Limited.P.O.Box36, Leicester LE47JQ, England
Prior art [2] is " optical surface roughness progress of research and directions " such as Xu Deyan, optical instrument 18,32 (1996)
Prior art [3] is J.Schwider, etc. " Dispersive interferometric profilometer " Opt.Lett.1994
Prior art [4] is MP2000 Noncontact Surface Profiler Manufactured by ChapmanInstru-ments Inc., 50 Saginaaw Drive, Rochester N.Y.14623, USA
Prior art [5] is Instruction Manual for TOPO-3D Three DimnensionalNoncontact Surface Profiler, WYKO Corporation, 2990 East Fort Lowell Road, Tucson, Arizona 85719, USA, 1986.
Prior art [6] is Heterodyne Profiler, Model 5500, and Laser InterferometricMicroscope, Maxim 3D, manufactured by Zygo Corporation, Laurel Brook Road, P.O.Box 448, Middle-field, Conn.06455, USA.
Prior art [7] is R.Juskaitia, etc. " Compact confocal interference microscopy ", Opt.Comm.109 (1994) 167-177
Prior art [8] is Scanning Probe Microscopes, Digital Instruments, and Inc., 520 EastMontecito Street, Santa Barbara, California 93103, USA.
Prior art [9] is J.M.Bennett.etc. " Scanning force microscope as a tool forstudying g optical surfaces ", Appl.Opt.34,213 (1995)
Prior art [10] is E.Betzig, etc. " Near-field optics:Microscopy, spectroscopy, andsurface modification beyond the diffraction limit " Science 257,189 (1992)
Should be noted that the quality of estimating detection method must be taken all factors into consideration the multiple factors such as possibility of resolution, measuring speed and precision, employed instrument cost and reliability, online detection.For example, the optical interference face shape detection method of prior art [2]-[6] is subject to optical diffraction and object lens operating distance, is difficult to differentiate the following horizontal information of micron; Prior art [8] scanning tunnel microscopy STM (Scanning Tunneling Microscopy), prior art [9] atomic force microscopy AFM (Atomic Force Microscopy) and prior art [10] scanning near-field optical microscopy SNOM (Scanning Near Field Optical Microscopy) etc. can satisfy sub-micron and laterally differentiate and the nanometer longitudinal resolution, even higher detection requirement, but have employed instrument cost height, to problems such as environment and sample requirement harshnesses;
The lateral resolution of confocal scanning system under identical image-forming condition be conventional optical microscope system 1.2-1.5 doubly, and confocal scanning system has transmission chromatography ability, can effectively suppress the scattered noise of material surface, and sample is not had strict demand.It is one of developing direction of detection technique in recent years that the cofocus scanning microscopic method is used for the detection of face shape.People such as R.Juskaitis are used for surface shape of material with the method for interfering and detect the resolution amount that has obtained the vertical nanometer of confocal scanning system in document Opt.Comm.109 (1994) 167-177.The deficiency of this method is, employed system architecture complexity, data processing are slow.People such as Chau-Hwang have proposed to utilize one section light intensity of response curve hypotenuse and zone that be linear change responsive with change in location to obtain the longitudinal resolution amount (Opt.Comm.135 (1997) 233-247) of nanometer, promptly are called difference cofocus scanning microscopic method.But this method is only applicable to detect the material of surface reflectivity unanimity.
In a word, at present people are still exploring new way, the new method that realizes that high-resolution surface shape of material detects, and trend is that the direction towards high spatial resolution, scene, real time implementation and miniaturization develops.
The objective of the invention is provides a kind of method of utilizing confocal scanning system that surface shape of material is detected in order to overcome the deficiency in the above-mentioned prior art.The simple confocal scanning system of utilization structure of the present invention just can obtain horizontal sub-micron, vertical nano level resolution, and detection speed will be faster than the cofocus scanning interference technique in the above-mentioned prior art.
Method of the present invention is to adopt 1 pair of sample of confocal scanning system 2 to carry out scanning survey.The sample 2 that records after the response curve q on the vertical Z direction and the sample 2 lip-deep light intensity I ' that record carry out normalized, is reconstructed the surface topography of sample 2 in response curve q linearity range ab.Its concrete steps are:
1, adopts 1 pair of sample of confocal scanning system 2 to carry out the scanning of vertical Z direction, record response curve q,, try to achieve the slope S of the linearity range ab of response curve q response curve q normalized.
As shown in Figure 1, scanning light beam G focuses on sample 2 surfaces through confocal scanning system 1, and sample 2 can obtain the vertical response curve q that confocal scanning system 1 scans out vertically moving on the Z direction.Response curve q is carried out normalized, and obtain the slope S of response curve q linearity range ab.Curve q as shown in Figure 1 and Figure 2.
2, measure the interior light intensity I of response curve q linearity range ab that each point is gone up on sample 2 surfaces
1', I
2', I
3' ... I
n' ..., and the largest light intensity I that correspondingly obtains by scanning on the vertical Z direction of each point
1max, I
2max, I
3max... I
Nmax... normalization, try to achieve normalization light intensity I
1, I
2, I
3... I
n....
As shown in Figure 1, sample 2 is left the O of focus O to the focus O outside
1The place, and guarantee that surface undulation is in the linear zone ab of vertical response curve q.Record the light intensity I that any 1 n is gone up on sample 2 surfaces
n'.Sample 2 is vertical Z scanning direction to focus O direction, obtains largest light intensity I
N_maxWith I
n' press I
N_maxBe normalized to I
n Sample 2 is vertically got back to O
1
Measurement to the each point of sample 2 on X or XY direction repeats above-mentioned steps 2, obtains the normalization light intensity I of sample 2 surperficial arbitrfary points
1, I
2, I
3... I
n....N be sample 2 surfaces more arbitrarily, n 〉=1.
3, measure vertical depth delta h of sample 2 surface undulations:
To go up any 2 n by sample 2 surfaces that above-mentioned steps 2 records, the difference DELTA I of the light intensity of k (is Δ I=I
n-I
k, n wherein, K 〉=1, and k ≠ n, n as shown in Figure 1, k 2 points) and divided by the slope S of above-mentioned vertical response curve q linear zone ab, obtain the surface height difference Δ h of sample, i.e. Δ h=Δ I/S, Δ h is called vertical degree of depth.Δ h has reflected the fluctuating on sample 2 surfaces, and repeated measurement reconstructs the pattern on sample 2 surfaces.Can carry out the groove depth of sample 2, the detection of roughness etc. thus.
Idiographic flow as shown in Figure 4.
There is the regional ab of response light intensity I with the lengthwise position linear change in method of the present invention according to the vertical response curve q that is confocal scanning system.C.J.R.Sheppard people such as (Appl.Phys.Lett.38,858,1981) utilizes the paraxial approximation theory, has analyzed under confocal scanning system pointolite, some detection condition, and confocal scanning system to vertical light intensity response of ideal mirror is:
Wherein, u is vertical normalization coordinate, has
In the following formula, λ is the wavelength of the scanning light beam G that sends of light source, and z is a defocusing amount; Vertical depth delta h of above-mentioned sample 2 surface undulations is the difference of any 2 defocusing amount z, is expressed as Δ h=z
n-z
k, n wherein, k 〉=1, and k ≠ n; Sin α is the effective numerical aperture of the focusing objective len in the confocal scanning system 1.I (u) curve is shown in solid line among Fig. 5-1.To I (u) differentiate, can obtain the slope of each point on the curve, shown in Fig. 5-2.When u=± 2.62, calculate | I ' (u) | reach very big.By seeing among Fig. 5-2 | I ' (u) | greatly have a gradual zone near the place, it is corresponding near the gradual zone of slope I (u) curve u=± 2.62.The curve of (Δ u) carries out least-squares algorithm linear fitting between near the first order derivative u=2.62 is equated 2, and the dotted line among Fig. 5-1 has provided u
∈ (3.48 ,-1.8)The fit line of scope.Can calculate the maximum error δ u of match in any range
MaxFig. 6 has provided fit range Δ u-maximum error δ u
MaxCurve.As seen from Figure 6, fit range is more little, and fitting precision is big more.This means the case depth amount Δ h corresponding to certain sample 2, the measurement that utilization the present invention carries out will have corresponding error of fitting.For example, as λ=0.6328 μ m, sin α=0.65 o'clock, the maximum vertically degree of depth is Δ h
MaxThe sample 2 of=300nm by formula (2) fit range Δ u=1.43 as can be known, is known δ u by Fig. 6
Max=0.0072, the actual vertically degree of depth maximum error δ h=δ z=1.5nm of match then, relative error δ h/ Δ h
MaxBe 0.5%.In like manner, the maximum vertically degree of depth is Δ h
MaxThe sample 2 of=600nm, Δ u=2.86, δ u
Max=0.075, error of fitting δ h=15nm then, relative error δ h/ Δ h
MaxBe 2.5%.As seen, under the condition of the focusing objective len effective numerical aperture of given scanning light beam G wavelength and confocal scanning system 1, in certain sample 2 depth rangees, utilization the present invention carries out the detection on sample surface, can guarantee high fitting precision, realize accurately measuring.
Another source of error of the surface shape of material detection method that the present invention carried is the systematic error delta h ' that light source, detector noise and external disturbance δ I cause, is expressed as:
Wherein, S is the slope S of the linearity range ab of vertical response curve q.If δ is I=0.5%, and be still λ=0.6328 μ m, sin α=0.65 o'clock is Δ h for above-mentioned depth capacity
Max=300nm, the sample 2 of 600nm, the slope S of vertical response curve q linearity range ab is respectively 0.263,0.252.δ h ' be can get by formula (3) and 4.0nm and 4.2nm are respectively.The total error of surface shape measurement is error of fitting δ h and systematic error delta h ' sum.To depth capacity Δ h
MaxLower sample is measured, and systematic error delta h ' is main, to depth delta h
MaxBigger sample, error of fitting δ h are main.
Detector for confocal scanning system 1 is not the situation of a detection, will comprise detector aperture parameter and light collecting lens parameter in the expression formula of I (μ), and form is complicated.Correspondingly, confocal scanning system vertical response curve q has broadening to a certain degree, but the method for above-mentioned linear fit analysis is still set up.
The invention has the advantages that:
1. the present invention uses said method can realize in conventional confocal scanning system that the pattern of nano-resolution detects, having broken through needs in the prior art to realize the method that the confocal scanning system nanotopography detects with interference technique, and the simple surveying instrument of utilization structure of the present invention can obtain the result of nanoscale longitudinal frame.
2. only relate to basic skills such as linear interpolation, normalization owing in the above-mentioned data processing, so the speed of data processing and pattern reconstruct is fast than the interference technique in the prior art.
3. the invention solves the non-interference difference of prior art cofocus scanning microscopic method and only can carry out the problem that face shape is detected the material of surface reflectivity unanimity.Because I is respectively to separately largest light intensity I in step 3
MaxBe normalized into comparable light intensity I, so just got rid of sample 2 surfaces everywhere difference in reflectivity the influence of surface shape measurement is obtained sample surface information accurately, as shown in Figure 8.
4. the employed confocal scanning system of method of the present invention is than the high 1.2-1.5 of lateral resolution times of the optical surface shape detection system in the prior art, and easily miniaturization; Antijamming capability than nano-probe scanning system in the prior art is strong, and online detection possibility is big; Therefore the present invention being used for confocal scanning system carries out surface shape of material and detects big application prospect will be arranged.
Description of drawings
The rough schematic of Fig. 1 cofocus scanning test material of the present invention face shape method
The vertical response curve q that records among Fig. 2 embodiment
The enlarged drawing of the vertical response curve q linearity range ab section that obtains among Fig. 3 embodiment, "+" be the actual samples point, solid line is the linear fit straight line of ab section (4.0 μ m-4.9 μ m) scope
The particular flow sheet of Fig. 4 cofocus scanning test material of the present invention face shape method
Fig. 5 is under pointolite, some detection condition, and Fig. 5-1 is a confocal scanning system vertical response curve (solid line); The dotted line on limit, solid line left side is the linear fit line; Fig. 5-2 is a vertical response slope of a curve change curve
Fig. 6 is under pointolite, some detection condition, and confocal scanning system vertical response curve q is at the relation curve of focus O both sides linear fit scope and match maximum error
Among Fig. 7 embodiment, sample 2 is the illustraton of model of resolution chart
The actual sample that records 2 is the altitude curve of 7 μ m lines in the resolution chart among Fig. 8 embodiment.Solid line is for carrying out obtaining after the normalized chromium layer height curve of normalization light intensity I among Fig. 8 to the light intensity I ' that records, dotted line for the light intensity I ' that records is carried out without normalized altitude curve (promptly adopting the cofocus scanning difference method in the prior art).
The actual sample that records 2 is the surface topography of resolution chart among Fig. 9 embodiment.
Embodiment:
The amount that the vertical response of ab section among table 2 Fig. 2 (3.8 μ m-5.1 μ m) is measured
| Analyzing spot (μ m) on vertical Z direction | ??3.8 | ??3.9 | ??4.0 | ??4.1 | ??4.2 | ??4.3 | ??4.4 |
| Normalization light intensity I | ??0.22 | ??0.24 | ??0.28 | ??0.34 | ??0.41 | ??0.48 | ??0.55 |
| Analyzing spot (μ m) on vertical Z direction | ??4.5 | ??4.6 | ??4.7 | ??4.8 | ??4.9 | ??5.0 | ??5.1 |
| Normalization light intensity I | ??0.61 | ??0.68 | ??0.74 | ??0.81 | ??0.87 | ??0.93 | ??0.97 |
Above-mentioned δ I need take all factors into consideration the influence to vertical depth survey such as the laser stabilization degree, detector dark current of light source and piezoelectric ceramics platform mobile accuracy that control sample 2 moves, the disturbance δ I of actual measurement confocal scanning system 1 is 0.5%, and utilizing formula (3) to get systematic error delta h is 7.6nm.
In the present embodiment, record respectively in the resolution chart that chromium laminar surface height Δ h is respectively into 254nm (shown in solid line among Fig. 8) 241nm (as shown in Figure 9) among the 7 μ m and 1 μ m line.
Find out by the foregoing description, the reality that the result that the result's (shown in Fig. 8 solid line) who uses method of the present invention to measure measures than the non-interference difference cofocus scanning method (shown in Fig. 8 dotted line) of prior art presses close to sample 2 more, its measuring accuracy is than the height of prior art.
Claims (1)
1. the method for a cofocus scanning test material face shape, adopt confocal scanning system (1) that sample (2) is carried out scanning survey, it is characterized in that the sample (2) that records after the response curve q on the vertical Z direction and the lip-deep light intensity I ' of sample (2) that records in response curve q linearity range ab carry out normalized, reconstruct the surface topography of sample (2), its concrete steps are:
＜1〉adopts confocal scanning system (1) that sample (2) is carried out the scanning of vertical Z direction, record response curve q,, try to achieve the slope S of the linearity range ab of response curve q response curve q normalized;
＜2〉measure the light intensity I of each point in response curve q linearity range ab on sample (2) surface
1', I
2', I
3' ... I
n' ..., and the largest light intensity I that correspondingly obtains by scanning on the vertical Z direction of each point
1max, I
2max, I
3max... I
Nmax... normalization, try to achieve normalization light intensity I
1, I
2, I
3... I
n..., n 〉=1 wherein;
＜3〉vertical depth delta h of measurement sample (2) surface undulation, vertical depth delta h=Δ I/S of sample (2) surface undulation, wherein Δ I is the poor of any 2 normalization light intensity, i.e. Δ I=I
n-I
k, n herein, k 〉=1, and n ≠ k, S is the slope S of the above-mentioned response curve q linearity range ab that tries to achieve.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103842770A (en) * | 2011-09-26 | 2014-06-04 | 西门子公司 | Method and device for measuring homogeneously reflective surfaces |
| CN106352798A (en) * | 2015-07-14 | 2017-01-25 | 台湾积体电路制造股份有限公司 | 3D IC bump height metrology APC |
| CN109405770A (en) * | 2018-11-02 | 2019-03-01 | 上海华力微电子有限公司 | A method of passing through photoresist film thickness monitoring gelatinizing developer coating groove horizontality |
-
1999
- 1999-05-13 CN CN 99113699 patent/CN1122821C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103842770A (en) * | 2011-09-26 | 2014-06-04 | 西门子公司 | Method and device for measuring homogeneously reflective surfaces |
| CN106352798A (en) * | 2015-07-14 | 2017-01-25 | 台湾积体电路制造股份有限公司 | 3D IC bump height metrology APC |
| US10181415B2 (en) | 2015-07-14 | 2019-01-15 | Taiwan Semiconductor Manufacturing Co., Ltd. | 3D IC bump height metrology APC |
| US10541164B2 (en) | 2015-07-14 | 2020-01-21 | Taiwan Semiconductor Manufacturing Co., Ltd. | 3D IC bump height metrology APC |
| US11075097B2 (en) | 2015-07-14 | 2021-07-27 | Taiwan Semiconductor Manufacturing Company, Ltd. | 3D IC bump height metrology APC |
| CN109405770A (en) * | 2018-11-02 | 2019-03-01 | 上海华力微电子有限公司 | A method of passing through photoresist film thickness monitoring gelatinizing developer coating groove horizontality |
| CN109405770B (en) * | 2018-11-02 | 2020-12-25 | 上海华力微电子有限公司 | Method for monitoring level degree of glue coating tank of glue coating developing machine through thickness of photoresist film |
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