X-ray characterization of crystal perfection and surface contamination in large-diameter silicon wafers

Materials Science in Semiconductor Processing 5 (2003) 435–444

X-ray characterization of crystal perfection and surface contamination in large-diameter silicon wafers Seiji Kawado* X-ray Research Laboratory, Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima-shi, Tokyo 196-8666, Japan

Abstract This paper reviews recent development of X-ray techniques, which cover laboratory experiments and synchrotron radiation (SR) applications, to detect crystal imperfections and surface contamination in large-diameter Czochralskigrown silicon (CZ-Si) wafers. While process-induced defects can be easily detected by a large-sized Lang camera, it is difficult to observe grown-in microdefects and slight impurity-inhomogeneity even when the double-crystal method is applied. SR plane-wave X-ray topography has overcome this difficulty, except for observing void defects, with the help of its high strain sensitivity although it cannot be directly applied to large Si wafers because of their warpage. Recently, SR X-ray topography using a 300-mm-wide monochromatic beam has been employed for measuring the warpage of 200- and 300-mm wafers as well as inspecting surface damage caused by various steps of wafer-manufacturing. Although energy-dispersive total-reflection X-ray fluorescence analysis using a rotating-anode X-ray generator is now widely used for detecting traces of metallic impurities on the surface of 300-mm Si wafers, the requirement of a large scale integrated circuit miniaturization has promoted the combination of a vapor-phase decomposition technique and the TXRF for lowering the lower-limit of detection (LLD). SR-TXRF using an ED solid-state detector is effective in nondestructive and low LLD features, while newly developed wavelength-dispersive (WD) SR-TXRF in good energy resolution. The combined use of the laboratory and SR experiments leads to precise information about crystal perfection and surface contamination in large-diameter Si wafers. r 2003 Elsevier Science Ltd. All rights reserved. Keywords: X-ray topography; TXRF; Laboratory X-ray sources; Synchrotron radiation; Crystal perfection; Surface contamination; Silicon wafers

1. Introduction Development of crystal-growth and wafer-fabrication technology has led to the era of 300-mm silicon wafers as starting materials for large scale integrated circuit (LSI) fabrication [1]. However, the crystal quality and surface property of the wafers does not necessarily meet the requirement of high performance and high yield of LSIs, which has been more severe with reducing the minimum feature length of devices. To fill the requirement, the growth of defect-free silicon crystals with homogeneous impurity distribution, the reduction in surface strain of

*Tel.: +81-42-545-8139; fax: +81-42-546-7090. E-mail address: [email protected] (S. Kawado).

wafers, and the formation of damage- and contamination-free surfaces are essential. This situation has also accelerated the progress in characterization technology [2]. Characterization of lattice imperfections such as defects and impurityinhomogeneity in silicon crystals, and investigation of strain and damage in wafer surfaces have been made using various techniques, including selective etching [3], X-ray diffraction (goniometry and topography) [4], transmission electron microscopy (TEM), and Fourier transform-infrared spectrometry (FT-IR) [5]. Furthermore, minute metallic contamination of the wafer surfaces has been examined by TXRF [6,7], inductively coupled plasma-atomic emission spectrometry (ICPAES), inductively coupled plasma-mass spectrometry (ICP-MS), etc. [8].

1369-8001/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1369-8001(02)00130-0

436

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

Among these techniques, X-ray diffraction topography [9,10] and TXRF [11] are well known as efficient nondestructive techniques, and have been widely used for inspecting wafers and LSIs during their fabrication processes. Laboratory instruments using X-ray diffraction topography and TXRF have been developed for a long time, and recently synchrotron radiation (SR) has also been successfully applied in the fields of highprecision X-ray diffraction topography [12] and highsensitivity TXRF [13]. This paper reviews recent development of X-ray diffraction topography and TXRF, which cover laboratory experiments and SR applications, for detecting crystal imperfections and surface metallic-contamination in large-diameter CZ-Si wafers.

2. X-ray characterization of crystal perfection 2.1. Requirement for control and evaluation of defects Commercially available CZ-Si wafers usually include microdefects such as octahedral voids [14], dislocation clusters [15] and oxygen precipitates even if they claim themselves to be dislocation-free. These microdefects often cause the generation of processinduced defects which degrade device characteristics except for intrinsic gettering effects [16]. Efforts have been continued to eliminate microdefects in the surface layer, and have consequently produced various kinds of techniques such as N-doping [17], high-temperature annealing in H2 atmosphere [18], epitaxial overgrowth, etc. Characterization of microdefects in as-grown crystals is not easy because their size is very small. In general, Secco etching [3] and laser scattering tomography [19] are used for survey, while TEM combined with focused ion-beam milling is often used to examine the detail of microdefects [14]. Since these techniques are destructive and time consuming, development of nondestructive and efficient techniques have been desired. Inhomogeneity of concentrations of dopant impurity and oxygen should also be reduced for better imaging devices and higher intrinsic gettering effects. For instance, the use of magnetic Czochralski-grown silicon (MCZ-Si) wafers [20] and epitaxial wafers has shown high performance as imaging devices such as chargecoupled device (CCD) imagers. Fluctuation of dopant impurity and oxygen concentrations in silicon wafers has been often investigated by spreading resistance measurements as an electrical method and micro-FT-IR measurements [5] as an optical method. However, these techniques have the disadvantage that they cannot measure impurity fluctuations over a large area of the wafers.

2.2. Laboratory X-ray topography Laboratory X-ray diffraction topography has been used to observe crystal imperfections in silicon since the 1960s. Techniques often used in laboratory experiments are transmission topography and double-crystal topography [9,10]. The transmission topography is usually carried out with a topographic X-ray camera using the Lang method under easy operation. The camera has gradually become larger with increasing in wafer size, and nowadays the topographic camera that accepts 300-mm silicon wafers is widely used for observing processinduced defects such as slip dislocations and oxygen precipitates generated during thermal processes of the device fabrication. Figs. 1(a) and (b) show the optics of the Lang method [21] and a large-size Lang camera. The X-ray beam emitted from a fine-focus source (Mo) enters the sample wafer, and the beam diffracted by a small part of the sample is recorded on an imaging plate or X-ray film. To cover a wide region of the sample, both the sample and the imaging plate are traversed simultaneously. Crystal imperfections are mainly imaged with extinction contrast [9], and consequently it is difficult to detect microdefects and oxygen striations in as-grown silicon. The differentiation between interstitial-rich regions and vacancy-rich regions, and the feature of oxygen striations are usually examined after copper decoration treatments. Double-crystal topography in the ðþ; Þ setting is more sensitive to minute strain than Lang topography. Fig. 2(a) is an example of the optics of double-crystal topography. In this arrangement, a (0 0 1) floating-zonegrown silicon (FZ-Si) monochromator is employed with the 224 asymmetric reflection of Cu Ka1, and the sample is also arranged with the 224 asymmetric reflection. In general, a double-crystal topograph is obtained from only a part of the sample wafer because the wafer is slightly warped. To cover the whole area of a largediameter wafer is time-consuming. Imperfections are imaged with difference in lattice spacing (Dd=d) and misorientation (Da) in local areas [9]; hence, this technique can be applied to observation of surface strain and growth striations in CZ-Si wafers. Fig. 2(b) is a topograph obtained from a part of a heavily boron-doped, 300-mm silicon wafer. Growth striations are observed with weak contrast, indicating boron- and/or oxygen-concentration fluctuations. No microdefects in as-grown silicon wafers can be observed in laboratory X-ray instruments, except for swirl defects, which are observed by the kinematical image technique [22], because X-ray power and wavelength are limited.

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

X-ray Source (Mo)

monochromator, (001)FZ-Si crystal, 224 reflection

X-ray source (Cu)

1st slit

slits scattered X-rays

traverse

guard imaging plate or X-ray film (a)

Sample, Si wafer 2nd slit

(a)

437

imaging plate or X-ray film

sample, (001)CZ-Si wafer, 224 reflection

TV camera

(b) (b) Fig. 1. (a) Optics of the Lang method. A guard against X-rays scattered from the first slit is attached at the second slit to avoid a fog of an X-ray film. (b) A large-sized Lang camera which can take topographs of 300-mm Si wafers.

g

10 mm

Fig. 2. (a) Example of the optics for double-crystal topography. (b) Growth striations, observed with weak contrast, in a Bdoped (0.015 O cm), 300-mm diameter (0 0 1) CZ-Si wafer.

2.3. SR plane-wave X-ray topography SR application to X-ray diffraction topography has been developed in white-beam topography and monochromatic-beam topography [23]. When higher sensitivity to strain than that of the conventional double-crystal method is needed, we can employ another method called plane-wave X-ray topography [24]. The plane-wave topography is made possible in principle using laboratory X-ray sources; however in practice it is difficult to take topographs for lack of intensity. The use of SR X-rays enables us to construct various X-ray optics for plane-wave X-ray topography and to observe minute strain in silicon crystals. Using extremely

asymmetric reflection of a collimator crystal, we can reduce the angular divergence of the X-ray incident on the sample to about 0.1 arcsec, as is shown in Fig. 3(a), resulting in high strain sensitivity. In this arrangement, the collimator crystal with an asymmetric factor b ¼ 1=64 is aligned to give the same 800 reflection of 11 keV X-ray as the sample crystal [25]. This method is appropriate for observing oxygen striations in as-grown crystals with strong contrast. An example of topograph obtained from a 10-mm-thick, undoped (1 0 0) MCZ-Si crystal is shown in Fig. 3(b). The topograph clearly shows the image of oxygen striations perpendicular to the growth direction [0 0 1].

438

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

monochromatic beam, 30 keV

photographic plate

sample, Si wafer

slit

(a)

collimator, FZ-Si, 220 refl., b~1/60

direct-beam stop

(b) Fig. 3. (a) Optics of plane-wave X-ray topography. (b) Oxygen striations, observed with strong contrast, in an undoped, 10mm-thick (1 0 0) MCZ-Si crystal.

Fig. 4. (a) Example of the optics for ultra-plane-wave X-ray topography. (b) Microdefects, indicated with arrows, in an asgrown, 0.5-mm-thick (0 0 1) CZ-Si wafer.

The quantitative analysis of variations in X-ray intensity results in a good coincidence between the variation in lattice spacing (Dd=d) and the oxygen-concentration fluctuation [4]. In ultra-plane-wave topography, we reduce the angular divergence of the incident X-ray beam to about 0.01 arcsec. The angular divergence of 0.01 arcsec provides an extremely high strain sensitivity and enables us to detect the variation in lattice spacing Dd=d of 109 order; therefore, this technique is appropriate for observing microdefects in as-grown silicon crystals. Such an extremely small divergence can be realized by two collimators using the asymmetric 2 2 0 and 2% 2% 0 reflections (b ¼ 1=36) of 17 keV X-ray [26], or by one collimator using the asymmetric 2 2 0 reflection (b ¼ 1=60) of 30 keV X-ray [27], as shown in Fig. 4(a). Fig. 4(b) is an elongated topograph showing microdefects, identified as dislocation clusters, in a 0.5-mm-thick (0 0 1) CZ silicon wafer that has been grown at a slow

pulling rate of 0.4 mm/min [27]. Arrows indicate small defect images observed with black-and-white contrast. Possibility of X-ray observation of octahedral voids smaller than 0.2 mm in CZ-Si crystals has been discussed [4]; however, these voids have not been detected, while large-sized voids in FZ silicon were observed as 40 mm round images by SR X-ray transmission topography [28]. 2.4. Large-area SR X-ray topography A large-area X-ray topographic technique using asymmetric reflections of X-rays incident at a glancing angle less than 11, has been recently developed by Topography subgroup of the Super Photon ring—8 GeV (SPring-8) users society [29]. Fig. 5 shows a schematic diagram of the X-ray optics, which forms a 300-mm-wide monochromatic beam, at beamline 20B2 in SPring-8. SR emitted from a

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

bending-magnet source is monochromatized by a double-crystal monochromator in the optics hutch, and then the monochromatic X-ray beam proceeds to the second experimental hutch, located at a point 200 m from the source, through a long vacuum path [30]. For instance, the whole surface of a silicon wafer less than 300-mm diameter can be irradiated with the 21.45 keV X-ray beam incident at a glancing angle of 0.261, and it causes the 115 reflection in Bragg geometry. This experimental arrangement is useful for characterizing surface-strain distribution caused by different steps of (0 0 1) silicon wafer preparation. The results of X-ray observations for 200-mm-diameter, 700–900-mmthick (0 0 1) silicon wafers whose surfaces were sliced, lapped, etched, ground, or polished, are shown in Fig. 6, together with the sample thickness and surface conditions [31]. Sliced and lapped surfaces give a topographic image over their whole surface area with one shot (see

Experimental hutch 1

Optics hutch

439

Fig. 7(a)) because of their wide rocking curves. On the other hand, etched, ground and polished surfaces need step-scanning of o rotation of the goniometer (see Fig. 7(b)), because of wafer warpage, to cover the whole surface area of their wafers, though their rocking curves are narrow. It should be noted that mechanical– chemical polishing was carried out on one side of the wafer, which is called single-sided polish (SSP). For comparison with 200-mm polished wafers, two topographs of a commercially available 300-mm silicon wafer, prepared by double-sided polish (DSP), are shown in Fig. 8. These topographic images are reconstructed into circular shapes through a digital process. Fig. 8(a) is an o-step-scanned topograph taken with the asymmetric 115 reflection, and Fig. 8(b) is taken with the asymmetric 1% 1 5 reflection, by rotating the sample wafer around the surface normal by 901 to change the direction of the X-ray beam incident on the sample

Long vacuum path

Experimental hutch 2

Double-crystal monochromator: Be window

2nd slit

X-ray source

Be windows Kapton window

(Bending magnet) 1st slit (Water-cooled)

0m

42 m

36 m

200 m Distance from the source

Fig. 5. Optics for large-area X-ray topography. A 300-mm-wide monochromatic X-ray beam (E ¼ 8:4271 keV) obtained at a point 200 m from the bending-magnet source [size; 0.29 mm (H)  0.04 mm (V)] is used to acquire topographs of a large-diameter Si wafer.

slicing

lapping

etching

poor crystallinity over the whole surface area FWHM, 67 → 55 arcsec warp, 1 → 0.4 arcsec/mm large FWHM of rocking curve → oneshot topograph

sample thickness

grinding

drastic improvement in crystallinity FWHM, 4.9 arcsec; reduction of warp 0.3 arcsec/mm small FWHM of rocking curve and large warp → step-scanned topograph

comment

slight degradation in crystallinity FWHM, 5.1 arcsec, increment in warp 1.5 arcsec/mm

polishing improvement in crystallinity FWHM, 3.8 arcsec, the existence of warp 0.75~0.85 arcsec/mm

sample

thickness

comment

1)

880 µm

sliced by a wire saw

4)

725 µm

2)

780 µm

lapped with #1000-meshed powder

5)[A]

730 µm

SSP(Single-Sided Polish)

3)

740 µm

etched with mixed acid

5)[B]

715 µm

SSP

ground with #3000 whetstone

Fig. 6. Summary of X-ray observations for 200-mm (0 0 1) CZ-Si wafers whose surfaces were sliced, lapped, etched, ground or polished.

440

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

surface. In this experiment, a sample holder, composed of a movable circular plastic plate 10-mm thick and a flat plastic plate fixed to the goniometer, was used to change the direction of the sample without resetting. Step scan of o rotation resulted in the movement of the narrow stripe image in the direction indicated with these arrows in both topographs. This result indicates that the mode of the warpage is convex. Hence, the stepscanned topography is a useful tool to reveal the mode of wafer warpage (convex or saddle-backed). Change of the warpage mode is, however, probably caused by the

Fig. 7. (a) One-shot X-ray topograph of a 200-mm CZ-Si wafer with lapped surface. (b) Step-scanned X-ray topograph of a 200-mm CZ-Si wafer with polished surface (SSP). Step interval; 10 arcsec.

slight difference in the contact between the facing surfaces of the wafer and the sample holder. Much attention should be focused on this phenomenon in the measurement of surface strain.

3. X-ray analysis of surface contamination 3.1. Requirement for metallic-impurity control and its evaluation In silicon device fabrication processes, surface contaminants deteriorate LSI characteristics. The contaminants on silicon surfaces are classified into two types, namely fine particles and metallic contamination [2]. The fine particles mainly cause short-circuiting between device elements, while metallic contamination causes deterioration of electrical characteristics. The influence of a trace of metallic contamination to electrical characteristics of LSI has been more pronounced as the miniaturization of LSI has been accelerated. Since a permissible contamination–concentration on the surface of silicon wafers as starting materials has become severe year by year, a rapid and correct method for determining concentrations of a wide range of elements on the wafers has been desired. According to the international technology roadmap for semiconductors [32], less than 8.8  109 atoms/cm2 for Ca, Co, Cu, Cr, Fe, K, Mo, Mn, Na and Ni is required as starting materials for the 130 nm node. Determination of such a low concentration has been carried out by wet chemical analysis. In general, natural SiO2 layers covered on silicon surfaces are dissolved with HF-containing solution, and metallic impurities included in the solution are determined by the atomicabsorption spectrophotometry (AAS) [8] or ICP-MS. Since the lower-limit of detection (LLD) of this technique is 108–109 atoms/cm2, it is enough to detect

Fig. 8. Reconstructed step-scanned X-ray topographs of a 300-mm CZ-Si wafer with polished surface (DSP). (a) 115 reflection and (b) 1% 1 5 reflection. Step interval; 10 arcsec.

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

metallic contamination on the surface of silicon wafers. However, this technique needs a high grade of skill for chemical analysis, and it is destructive. Methods which are nondestructive and high-sensitive to metallic impurities are required for contamination control technology. 3.2. Laboratory TXRF TXRF is well used for a nondestructive analysis of metallic contamination on the surfaces of silicon wafers. The principle of TXRF consists of two items [11]. One is, of course, the basic process of fluorescence radiation, and the other is the effect of total reflection of the incident X-ray beam, which results in the reduction of penetration depth. Since the reduction of X-ray penetration causes a decrease in intensity of the scattered X-ray, the background level is reduced. This effect results in the improvement in signal-to-noise ratio (S=N), and finally leads to the improvement in the LLD. Since Yoneda’s proposal [33], laboratory TXRF systems have been greatly modified by adopting a high-brilliance rotating-anode X-ray source (W, Au), a monochromator for X-ray fluorescence excitation, a high-sensitive Li-doped-Si solid-state detector (SSD) and an in-vacuum sample chamber [34,35]. Fig. 9 shows a schematic diagram of a laboratory TXRF system. In this system, a silicon wafer is irradiated at a small glancing angle with W Ma radiation for Na to Al, W Lb radiation for Si to Zn, or 20 keV X-rays for other elements lighter than U, tuned by a double-crystal monochromator using artificial multilayers. In addition, an x; y; y-driven sample stage has been employed for improving S=N by selecting a direction of the incident X-ray beam without diffraction [36], and consequently the LLD for Ni, for instance, has reached to 1  109 atoms/cm2. Combination with vapor-phase decomposition (VPD) is another solution to further improvement of LLD in

441

TXRF. The VPD has been originally used as a sampling technique, which concentrates contaminants on the surface of the sample wafer for the AAS and ICP-MS analyses. In this technique, clean vapor of hydrogen fluoride dissolves a natural SiO2 layer together with metallic contaminants on the wafer surface, followed by the formation of a droplet including the metallic contaminants. The droplet is dried with an IR lamp in TXRF sample preparation instead of recovering with a micropipette. The combination with VPD has improved the LLD of TXRF by two orders of magnitude [37]. A fully automated VPD preparation system has also been developed for the ultra-trace analytical inspection of 300-mm silicon wafer surfaces [38]. At present, the VPD-integrated TXRF system (Fig. 10) is available, and the LLD reaches to 1  109 atoms/cm2 for Na and 1  107 atoms/cm2 for Ni in a 300-mm wafer. 3.3. SR-TXRF The merits of SR-TXRF are an increase in intensity of the primary X-ray and further lowering of the background owing to the polarization of an SR beam. In an energy-dispersive total-reflection X-ray fluorescence analysis (ED-TXRF) system, which has been constructed at Stanford Synchrotron Radiation Laboratory (SSRL), the SR source is a multipole wiggler, and the monochromator is comprised of two artificial multilayers which can tune the X-ray energy from 6 to 14 keV [39]. The sample wafer is fixed so that the surface is perpendicular to the polarization of the SR beam. Comparison between the results of a laboratory TXRF and an SR-TXRF is shown in Fig. 11. These TXRF spectra were obtained in a cooperative research program of SSRL, Komatsu Electronic Metals and Rigaku [40]. The sample is a silicon wafer intentionally contaminated with Ni of 8  1011 atoms/cm2 by the spin coating method. The excitation energy was 9.67 keV in

Fig. 9. Schematic diagram of a laboratory TXRF system. Excitation energy is selected to be 1.78 keV (W Ma), 9.67 keV (W Lb), or 20 keV using artificial multilayers as a monochromator.

442

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

Fig. 10. Example of VPD-integrated TXRF system. Main parts are (1) load port, (2) outer transfer robot, (3) decomposition chamber, (4) recovering-drying chamber, (5) load lock, (6) inner transfer robot and (7) sample stage.

Intensity of X-rays (cps/10eV)

1000

Si-Kα

Ni-Kα

100

Ni-Kβ

10 1 0.1 0.01 1×10-3

SR TXRF300

-4

1×10

0

5

10

Energy of X-rays (keV) Fig. 11. Comparison between laboratory TXRF and SR-TXRF. Measurements were carried out for a wafer contaminated with Ni of 8  1011 atoms/cm2. (By courtesy of Dr. T. Yamada)

the laboratory TXRF and 11.2 keV in the SR-TXRF. Using a well-known equation for LLD [37], the LLD for Ni is calculated to be 1  109 atoms/cm2 for the laboratory-TXRF. The best LLD obtained at SSRL is 0.8  108 atoms/cm2 [39]. WD-TXRF using SR is also noticeable for its capability for high energy resolution of spectra. A TXRF system, equipped with both a wavelengthdispersive (WD) spectrometer and an ED solid-state detector, has been installed at the industrial-consortium ID beamline (BL16XU) in SPring-8. Test results of the LLD for Ni showed 4.3  108 atoms/cm2 for ED-

TXRF and 6.1  109 atoms/cm2 for WD-TXRF, while the energy resolution of spectra obtained by the WDTXRF was definitely superior to that by the ED-TXRF [41]. Recently, the combination of VPD technique and the WD-TXRF was carried out, and it gave a remarkable LLD for Cu, 4  106 atoms/cm2 for a 200-mm wafer [42]. This concentration corresponds to only 4 atoms/ 10 mm  10 mm. This technique is expected to contribute to the development of advanced semiconductor devices since contamination of rare-earth elements will be noticed in near future.

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444

4. Summary In this paper, recent topics of X-ray diffraction topography and TXRF for characterizing crystal imperfections and metallic contamination have been reviewed. The state of the technology is summarized as follows. For X-ray diffraction topography, laboratory topographic camera system, especially transmission topography, is useful for detecting process-induced defects in large-diameter silicon wafers. SR X-ray topography extends the range of observable imperfections such as microdefects and slight impurity-inhomogeneity in asgrown silicon crystals, and enables us to measure surface-strain distribution in large-diameter wafers. For TXRF, LSI miniaturization has promoted the combination of VPD and laboratory ED-TXRF because of the improvement in LLD. SR-TXRF is an effective method for improving the LLD nondestructively. In conclusion, it should be noted that the combined use of the laboratory and SR experiments provides precise information about crystal perfection and surface contamination in large-diameter silicon wafers. Acknowledgements The author expresses his sincere appreciation to Dr. S. Kojima, Dr. Y. Kudo, Mr. K.-Y. Liu and Mr. I. Maekawa of Sony Corporation, and Dr. T. Ishikawa (present address; RIKEN), Dr. K. Hirano, Dr. Zhang Xiaowei and Prof. A.Iida of Photon Factory for joint researches of SR-X-ray topography and SR-TXRF. Acknowledgment is given to the members of Topography SG of SPring-8 Users Society, especially Prof. Y. Chikaura, Prof. S. Iida, Prof. M. Umeno, Dr. S. Kimura, Dr. K. Kajiwara and Mr. Y. Hirose for joint researches at SPring-8. The author wishes to thank Dr. Y. Suzuki, Dr. K. Umetani and Dr. K.Uesugi of SPring8 for their technical support of SR experiments, and the members of Industrial Consortium ID Beamline, especially Dr. S. Komiya (present address; JASRI), Dr. Y. Hirai, Dr. N. Awaji, Dr. M. Takemura and Dr. T. Shoji (Rigaku) for constructing a TXRF system. He is also deeply indebted to Prof. J. Harada, Dr. T. Yamada, Dr. M. Yamagami, Mr. T. Kikuchi of Rigaku and Rigaku Industrial Corporation for their fruitful discussion and supplying experimental data, and Shin-Etsu Handotai, Mitsubishi Materials, and Komatsu Electronic Metals for supplying test samples. References [1] Hahn PO. Microelectron Eng 2001;56:3. [2] Takahashi K, Kawashima K. Microelectron 2001;56:27.

Eng

443

[3] Yamagishi H, Fusegawa I, Fujimaki N, Katayama M. Semicond Sci Technol 1992;7:A135. [4] Kawado S. Jpn J Appl Phys 1999;18(Suppl. 38-1):520. [5] Fusegawa I, Yamagishi H. Semicond Sci Technol 1992;7:A304. [6] Berneike W. Spectrochim Acta 1993;48B:269. [7] Hockett RS. Proceedings of the ECS, Contamination Control and Defect Reduction in Semiconductor Manufacturing III. Pennington: Electrochemical Society, 1994. p. 323. [8] Shimazaki A. Proceedings of the ECS, Defects in Silicon II. Pennington: Electrochemical Society, 1991. p. 47. [9] Tanner BK. X-ray diffraction topography. Oxford: Pergamon Press, 1976. [10] Authier A. Dynamical theory of X-ray diffraction. Oxford: Oxford University Press, 2001 [chapter 17]. [11] Klockenk.amper R. Total-reflection X-ray fluorescence analysis. New York: Wiley, 1997. [12] Ishikawa T. J Cryst Growth 1990;103:131. [13] Liu K-Y, Kojima S, Kawado S, Iida A. Adv X-ray Chem Anal Jpn 1995;26s:107. [14] Itsumi M. Mater Sci Eng 2000;B73:184. [15] Takeno H, Ushio S, Takenaka T. Proceedings of the Material Research Society, Defect Engineering in Semiconductor Growth, Processing and Device Technology. Pittsburgh: Material Research Society, 1992. p. 51. [16] Tan TY, Gardner EE, Tice WK. Appl Phys Lett 1977;30:175. [17] Nakai K, Inoue Y, Yokota H, Ikari A, Takahashi J, Ohashi W. Proceedings of the JSPS, Advanced Science and Technology of Silicon Materials III JSPS, Tokyo, 2000. p. 88. [18] Kashima K, Izunome K, Goto H, Kurokawa M, Minami T, Takeda R. Proceedings of the JSPS, Advanced Science and Technology of Silicon Materials III JSPS, Tokyo, 2000. p. 181. [19] Umeno S, Sadamitsu S, Murakami H, Hourai M, Sumita S, Shigemitsu T. Jpn J Appl Phys 1993;36:L699. [20] Hoshi K, Isawa N, Suzuki T, Ohkubo Y. J Electrochem Soc 1985;132:693. [21] Lang AR. Acta Cryst 1959;12:249. [22] Chikawa J, Asaeda Y, Fujimoto I. J Appl Phys 1970;41:1922. [23] Bowen DK, Tanner BK. High resolution X-ray diffractometry and topography. London: Taylor & Francis, 1998 [chapter 10]. [24] Ishikawa T, Kohra K In: Handbook on synchrotron radiation, vol. 3. Amsterdam: Elsevier, 1991. [chapter 3]. [25] Kudo Y, Liu K-Y, Kojima S, Kawado S, Ishikawa T. J Electrochem Soc 1997;144:4035. [26] Kawado S, Kojima S, Kato Y, Hayashi H, Ishikawa T. Defect control in semiconductors. Amsterdam: Elsevier, 1990. p. 175. [27] Iida S, Chikaura Y, Kawado S, Kimura S. J Synchrotron Radiat 2002;9:169. [28] Tuomi T, Rantam.aki R, McNally PJ, Lowney D, Danilewsky AN, Becker PJ. Phys D: Appl Phys 2001;34:A133. [29] Kawado S, Iida S, Ishikawa K, Chikawa Y, Suzuki Y, Kajiwara K, Kimura S, Matsui J, Umeno M, Shimura T,

444

[30] [31]

[32] [33] [34]

[35]

[36]

S. Kawado / Materials Science in Semiconductor Processing 5 (2003) 435–444 Mizuno K, Ozaki T, Izumi K, Ishikawa T. Abstract X-TOP, Fifth Biennial Conference on High Resolution X-ray Diffraction and Topography, Ustron-Jaszowiec, September, 2000. p. 107. Kawado S, Iida S, Chikaura Y. SPring-8 Research Frontiers 1999/2000 JASRI, Hyogo, 2001. p. 89. Kawado S, Iida S, Yamaguchi S, Kimura S, Horose Y, Kajiwara K, Chikaura Y, Umeno M. J Synchrotron Radiat 2002;9:166. International Technology Roadmap for Semiconductors 1999. Semiconductor Industry Association, San Jose, 1999. Yoneda Y, Horiuchi T. Rev Sci Instrum 1971;42:1069. Nishihagi K, Kawabata A, Taniguchi T, Ikeda S. Proceedings of the ECS, First Cleaning Technology in Semiconductor Device Manufacturing. Pennington: Electrochemical Society, 1989. p. 243. Utaka T, Sako Y, Kojima S, Iwamoto K, Kohno H, Atsumi J. Adv X-ray Chem Anal Jpn 1992;23:225 [in Japanese]. Funabashi M, Utaka T, Arai T. Spectrochim Acta B 1997;52:887.

[37] Yamagami M, Nonoguchi M, Yamada T, Shoji T, Utaka T, Nomura S, Taniguchi K, Wakita H, Ikeda S. X-Ray Spectrom 1999;28:451. [38] Pahlke S, Kotz L, Ehmann T, Eichinger P, Huber A. Proceedings of the ECS, Semiconductor Silicon 1998, vol. 1. Pennington: Electrochemical Society, 1998. p. 1524. [39] Pianetta P, Baur K, Singh A, Brennan S, Kerner J, Werho D, Wang J. Thin Solid Films 2000;373:222. [40] Yamada T, Yamagami M, Harada J, Iwamoto K, Shibata H, Nagai K, Watanabe M, Baur K, Pianetta P. Abstract the 2001 Spring Meeting of JSAP JSAP, Tokyo, 2001 31aD-7 [in Japanese]. [41] Awaji N, Ozaki S, Nishino J, Noguchi S, Yamamoto T, Syoji T, Yamagami M, Kobayashi A, Hirai Yo, Shibata M, Yamaguchi K, Liu K-Y, Kawado S, Takahashi M, Yasuami S, Konomi I, Kimura S, Hirai Ya, Hasegawa M, Komiya S, Hirose T, Okajima T. Jpn J Appl Phys 2000;39:L1252. [42] Awaji N, Takemura M, Ozaki S, Iihara J, SPring-8 Information, vol. 7, No. 1, Hyogo: JASRI. 2002. p. 28 [in Japanese].