AVS2004 Session MS+AS-WeA: Non-Destructive Analysis and Metrology for Advanced Manufacturing

Wednesday, November 17, 2004 2:00 PM in Room 303B

Wednesday Afternoon

Start	Invited?	Item
2:00 PM		MS+AS-WeA-1 Advances in X-ray Reflectivity (XRR) and X-ray Fluorescence (XRF) Measurements Provide Unique Advantages for Barrier and Metal Layer Measurements of 65 nm Node Devices J.S. Spear (Technos International); H. Murakami, S. Terada (Technos Company Limited, Japan) We have developed a thin-film metrology tool that fulfills the metrology requirements for the production of 65nm node technology and beyond. This tool combines X-ray Reflectivity (XRR) and X-ray Fluorescence (XRF) measurements to provide accurate, high throughput, measurements. Improvements in both the XRR and XRF configurations were made to allow high throughput measurements on films as thin as 0.5 nm. One of the challenges for the 65nm node is measuring the Cu metal layers and their accompanying barrier layers. The difficulty in measuring these layers is increased since the barrier is often a bi-layer composed of both TaN and Ta. This paper describes how a combined XRR XRF tool can be used to accurately measure these individual layers with optimum throughput.
2:20 PM	Invited	MS+AS-WeA-2 Non-Destructive Ultra-Thin Film (0-100A) Analysis in the Lab and the Fab. C.R. Brundle (C. R. Brundle and Associates) Whether for characterization or failure analysis work in the support laboratory, or for rapid quality control/metrology in a wafer processing fab, the need for analytical techniques capable of determining thickness, composition, and composition as a function of depth (including differences at interfaces) is increasing as the variety of film material used in processing expands, and as films and stacks get thinner. The current materials roster, and the stringency of analytical requirements are briefly reviewed, then four non-destructive techniques being deployed in lab and fab situations are discussed and their capabilities compared for these two different environments. They are X-Ray Fluorescence, XRF; X-Ray Reflectivity, XRR; X-Ray Photoelectron Spectroscopy, (XPS and angle resolved XPS); and Low Energy X-Ray Emission spectroscopy, LEXES.
3:00 PM		MS+AS-WeA-4 Crystalline Structure and Stress Characterization in Thin Films by Means of Optical Spectroscopy G. Conti, Y. Uritsky (Applied Materials, Inc.) Nondestructive characterization techniques are crucially important in developing new materials. Raman Spectroscopy is a powerful and versatile tool. Its capabilities range from structural identification and conformation of molecules, to identification of crystalline structure of materials. This power and versatility has led to its progressively more extensive applications to semiconductor industry as an analytical tool. In this paper we present some applications of Raman analysis to the characterization of thin films. The present challenge in thin films characterization is on one hand the determination of the film composition and/or crystalline phase; on the other the stress to which the film is subjected as it is deposited under different temperatures, chemical conditions of depositions, and substrates. In the first part, we report on the Raman characterization of silicides films generated on a Si surface. In particular we determine the stoichiometric composition of the silicides, their crystalline phase and their thickness. In the second part, we determine the stress of Si deposited on SiGe. The main advantage of Raman versus conventional X-ray diffraction is the ability to measure strain in thin layers (from 5 nm and above). We show here that Raman is the ideal method for characterizing strained cap Si layers with critical thickness in the range of 100-200 Å., and for characterizing stresses in quantum wires, quantum dots and other hetero-structures, which are becoming more and more important for fabricating devices with enhanced performance.
3:20 PM		MS+AS-WeA-5 Optical Properties (IR to VUV) and Birefringence of Graphite-like Amorphous Carbon S. Zollner, R. Liu, R.B. Gregory, W. Qin, J. Kulik, N.V. Edwards, K. Junker (Motorola); T.E. Tiwald (J.A. Woollam Co.) Amorphous carbon films of 50 nm thickness, low surface roughness, and low densities (1.5-1.7 g/cm³) were deposited on Si using plasma-enhanced chemical vapor deposition (PECVD) between 300 and 550°C. With increasing deposition temperature, the hydrogen content (determined with elastic recoil detection) is reduced from 35% to 15%. For films grown at lower temperatures, ellipsometry data (0.7 to 9.5 eV photon-energy range, taken at 35-75° angle of incidence on a rotating-analyzer ellipsometer with a computer-controlled Berek waveplate) can be fitted very well by a single optically isotropic layer with low visible absorption (ε₂<1 below 4 eV) and two broad absorption peaks at 4.5 and 6.5 eV, a pronounced absorption minimum between 7 and 8 eV, and another strong rise of the absorption above 9 eV. At higher growth temperature, the visible absorption rises, the absorption peaks sharpen and red-shift, and the film becomes birefringent with the optical axis oriented normal to the substrate. The extraordinary absorption also shows two peaks at 3 and 4.5 eV, but the magnitude is much larger than the ordinary absorption peaks. The amorphous character of the films was confirmed by high-power powder x-ray diffraction. At our growth pressure (>1 Torr), the ion energy is expected to be very low, which leads to dominant sp² character of our films¹ (verified by electron energy loss spectrometry) and low density (<1.8 g/cm³). The birefringence is thus explained by alignment of the amorphous sp² clusters along or perpendicular to the Si substrate. Birefringence and a double-peak absorption structure has not previously been reported for amorphous carbon. Vibrational properties of the films will also be discussed. Proper consideration of the birefringence is crucial to determine the thickness and optical constants of such layers. ¹J. Robertson, Mat. Sci. Eng. R 37, 129 (2002).
3:40 PM	Invited	MS+AS-WeA-6 Metrology for Advanced Manufacturing M.I. Current (Frontier Semiconductor) Metrology for process controls for manufacturing of advanced semiconductor devices faces an unprecedented number of challenges, well beyond the continued scaling to smaller transistors and denser functional arrays. Some common themes are the sharp increase in the introduction of new materials, new materials combination and interfaces and new device structures. This review will consider the metrology challenges and some new methods in four areas: (1) ultra-shallow doped junctions, including dopant activation and leakage currents, (2) stress and adhesion characteristics of metal/dielectric interfaces for gate and interconnect stacks, (3) local strain characterization of isolation structures, gates and channels as well as wafer-scale, strained materials systems and (4) bonding and layer transfer methods for integration of heterogeneous materials and devices such as, multi-level SOI wafers for logic, memory and photonic devices, 3-D packaging of functionally diverse devices and integration of MEMS/photonic structures with CMOS devices.
4:20 PM		MS+AS-WeA-8 Total Analysis of the Gases in Semiconductor Manufacturing Process: Use of Ion Attachment Mass Spectrometry M. Nakamura, Y. Taneda, Y. Hirano, Y. Shiokawa (ANELVA Technix Corporation, Japan); M. Takayanagi, M. Nakata (Tokyo University of Agriculture and Technology, Japan) Ion attachment mass spectrometry (IAMS)¹ is a powerful tool to monitor semiconductor manufacturing process^2-3 by analyzing the molecules in the gas because with IAMS fragment-free mass spectra can be obtained; i.e. only quasi-molecular ions without being suffered by dissociation are observed. The fragment-free detection is impossible with other ionization techniques such as the electron ionization. There are two-type equipments of IAMS; one for the process at the pressure from 100 Pa to atmospheric pressure, and the other for the process at several Pa. We analyzed the process for manufacturing semiconductor by measuring mass spectra of gases in the reaction chamber and of the exhaust gas simultaneously with these equipments. Very high frequency capacitively coupled plasma (VHF-CCP) (60 MHz, 1000 W) was produced in the reaction chamber by providing 2 Pa of Ar/c-C₄F₈/O₂ (100, 2, and 6 sccm, respectively). The equipment for gases at several Pa was installed on the sidewall of the reaction chamber with a connection pipe of 100-mm length. At the same time the exhaust gas from the reaction chamber was analyzed after the rough pump with the other IAMS equipment. Polymerized compounds such as carbonyl fluoloride (C₄OF₈, C₅OF₁₀, and so on) and other compounds were found not only in the exhaust gas² but also in the reaction chamber. The kinds of compounds in the exhaust gas are less than those at the reaction chamber, suggesting the dissociation and the polymerization at the pumping line. We present in our talk about c-C₄F₈ plasma in other conditions, SiH₄ plasma, and other processes to show the applicability of IAMS. The authors are grateful to Dr. H. Ito et al. of ASET for their support to the experiments. 1 T. Fujii, Mass Spectrom. Rev. 19, 111 (2000). 2 M. Nakamura et al., J. Vac. Sci. Technol. A 19, 1105(2001). 3 Y. Shiokawa et al., AVS Int. Sympo., PS-ThA1 (2003).
4:40 PM		MS+AS-WeA-9 Optimizing and Managing Calibration Gas Inventories to Address Accuracy, Analysis Shelf Life and the Cost of Ownership P. Somssich (Osram Sylvania, Inc.) Today's analytical laboratories must meet ever-stricter quality controls and tracking requirements to maintain accreditation. Maintaining the usability of certified gas standards can be both time-consuming and costly. An ACCESS-based database was developed at Osram Sylvania Inc. to serve both cost management needs and the scientific requirements. The essentials of such a database required addressing critical issues: e.g., the shelf life of the certification, the traceability and cost of ownership. Almost 28 certified gas mixtures have since been recertified with initial fill and analysis dates going back 16 years. While some older mixtures were initially thought to be no longer useable, actual analysis results indicated that in most cases the vendor stated shelf life was far too short. However, there were a few dramatic exceptions. In addition to the costs associated with maintaining the certification, significant costs can occur by way of cylinder rentals, i.e., long term rental. This data is currently being evaluated to minimize the cost of ownership of the inventory, which includes 140 mixtures. The importance of good and accurate (or even very accurate) gas calibration standards has recently been highlighted by the use of EPA protocol gases associated with continuous emission monitors (CEMs). Since the Clean Air Act of 1990 makes the use of such monitors necessary, proper calibration standards and procedures can contribute to a sizeable financial windfall, while poor calibration can result in possible stiff penalties. Applications from lamp manufacturing will also be discussed showing a significant quality and financial benefit when lighting products are filled accurately resulting in optimal light output and performance as well as energy savings.