Direct Measurement of Planarization Length for Copper Chemical Mechanical Planarization Polishing (CMP) Processes Using a Large Pattern Test Mask

In spite of the fact, that the main purpose of CMP is the planarization of surfaces, most processes are optimized with respect to the removal rate. This might be due to a lack in techniques for the determination of the planarization behavior. The commonly used expression "Planarization Length" implies a maximum lateral extension over which the planarization is obtained and which can not be improved. Several attempts have been made to determine the planarization length by studying the CMP on different test patterns. The general problem in the interpretation of the data is the interaction of neighboring pattern with different pattern densities. This problem does not apply to the most simple pattern possible, which is a single step with an extension of the up and down areas much larger than the planarization length. In this case the spatial derivative of the resulting contour after CMP is directly the demanding transfer function to be used for the convolution. This concept, initially proposed by Boning et. al., was applied to evaluate the polish of copper and silicon oxide. Wafers with concentrically steps in Cu or SiO 2 films with an extension of 1 to 5 cm have been prepared. During polish, the initially infinite steep step widens up, yielding the planarization length as a function of the removal respective the polishing time. Significant differences in the evaluation of the planarization length could be quantified depending on the pad, slurry and tool parameters. Our first experiments revealed a decrease in planarization length by the addition of BTA in a copper slurry. We believe that the SPR method enables a unambiguous, pattern independent determination of the planarization capability in CMP.

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“…used special test patterned wafers with features from the µm to mm scale to investigate the planarization behavior of a CMP process [2]. al.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Planarization length variation by the Step-Polish-Response (SPR) Method

et al. 2004

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“…More detailed information on the relation of interfacial separation to current distribution was provided by experiments on a patterned Cu-damascene test wafer, SEMATECH/MIT 862. 13 This wafer contains square features recessed by 600 nm with a wide range of lateral dimensions. Figure 5 shows part of a static etch pattern which spans the corner of a 5 ϫ 5 mm test feature seen in the lower right corner.…”

Section: Methodsmentioning

confidence: 99%

“…The situation is analogous to the effect of polishing pad stiffness on planarization length in CMP. 13 Accordingly, with suitable refinement of the membrane and/or half-cell, MMEP may be capable of performance equal to that of CMP.…”

Section: H239mentioning

confidence: 99%

Membrane-Mediated Electropolishing of Copper

Mazur

Foggin

Jackson

et al. 2008

J. Electrochem. Soc.

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Membrane-mediated electropolishing (MMEP) is a method for planarizing and polishing a metal anode using a charge-selective ion-conducting membrane to separate the cathode and electrolyte solution from a thin layer of deionized water covering the substrate. Unlike conventional electropolishing, the current density and rate of material removal are controlled by ohmic resistance of the interfacial water layer. By controlling the interfacial pressure and tangential velocity of the membrane with respect to the substrate, the principles of lubrication mechanics can be used to maintain the thickness of the water layer at much less than 1μm , thereby providing a high efficiency for planarizing submicrometer topographic features. This paper describes the process characterization and applications of MMEP for planarizing Cu substrates such as test wafers for the fabrication of Cu damascene circuitry on integrated circuits.

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“…On the other hand, for the integration of low-k dielectric materials, a move towards low-pressure CMP techniques and fixed abrasive polish pads is observed. For these techniques, the CMP planarization length is increased [14,15]. This will have a negative impact on CMP-induced signal strength variations.…”

Section: Future Workmentioning

confidence: 99%

Alignment robustness for 90 nm and 65 nm node through copper alignment mark integration optimization

Warrick¹,

Hinnen

Morton

et al. 2005

Optical Microlithography XVIII

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In this paper, methods for stacking ASML scribe lane alignment marks (SPM) and improving the mark performance at initial copper metal levels are discussed. The new mark designs and the theoretical reasons for mark design and/or integration change are presented. In previous joint publications between ASML and Freescale Semiconductor [1], improved overlay performance and alignment robustness for Back End Of Line (BEOL) layers by the application of stacked scribe lane marks (SPM) was presented.In this paper, further improvements are demonstrated through the use of optimized Versatile Scribe Lane Mark design (VSPM). With the application of stacked optimized VSPM-marks, the alignment signal strength of marks in the copper metal layer is increased compared to stacked SPM marks. The gains in signal strength stability, which is typical for stacked marks, as well as significantly reduced scribe lane usage, are also maintained. Through the placement of specially designed orthogonal scatter-bars in selected layers under the VSPM-marks, the alignment performance of initial inlaid metal layers is improved as well. The integration of these marks has been evaluated for the 90 nm and 65 nm technology nodes as part of a joint development program between the Crolles2 Alliance and ASML. A measured overlay improvement of ~10-15% was obtained by a strategy change from floating copper marks to stacked optimized VSPM marks.

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Direct Measurement of Planarization Length for Copper Chemical Mechanical Planarization Polishing (CMP) Processes Using a Large Pattern Test Mask

Cited by 5 publications

References 3 publications

Assessment of Planarization length variation by the Step-Polish-Response (SPR) Method

Assessment of Planarization length variation by the Step-Polish-Response (SPR) Method

Membrane-Mediated Electropolishing of Copper

Alignment robustness for 90 nm and 65 nm node through copper alignment mark integration optimization

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