Analysis of in-situ vibration monitoring for end-point detection of CMP planarization processes

Hetherington, Dale L.; Stein, David J.; Lauffer, J.P.; Wyckoff, Edward E.; Shingledecker, David M.

doi:10.1117/12.346902

Cited by 8 publications

(9 citation statements)

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“…The need for such measurements requires the fitting of the polisher with costly friction plates (which are quite large and complex, and may not always be suitable for certain types of polishers), force sensors, multiplexers and signal amplifiers all of which need periodic calibrations. The scientific literature is filled with alternate methods [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] of inferring COF in CMP with the most popular of such approaches being centered around measuring platen motor current (PMC). During CMP, the wafer and the platen corotate at desired angular velocity setpoints.…”

Section: Introductionmentioning

confidence: 99%

Correlating Coefficient of Friction and Shear Force to Platen Motor Current in Tungsten and Interlayer Dielectric Chemical Mechanical Planarization at Steady-State Conditions

Headley¹,

Frank²,

Sampurno³

et al. 2020

ECS J. Solid State Sci. Technol.

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Following up our earlier work that highlighted the relationship between shear force (SF) and platen motor current (PMC), in parallel with the relationship between coefficient of friction (COF) and PMC for various tungsten and interlayer dielectric (ILD) chemical mechanical planarization (CMP) cases at non-steady-state conditions, we explored whether or not PMC could be used as a reliable indicator instead of SF and COF at steady-state conditions. For the 12 cases studied, 72 distinct steps were analyzed. It was determined that PMC somewhat mirrored SF and PMC for long time (i.e. 10 s or longer) intervals after data averaging and applying a trend matching algorithm. SF and PMC trends matched only about 64% of the time (ranges between 45% to 85%) for all 72 steps, while PMC and COF trends matched 62% of the time ranging between 42% and 85%. PMC-SF and PMC-COF correlations were fairly poor at 1-sec time intervals as evidenced by much lower percent match values. Such poor correlations proved that at small time intervals, PMC was not sensitive enough to capture important information regarding myriad fluid dynamics and tribological phenomena and the instantaneous stick-slip occurrences encountered in CMP.

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Section: Introductionmentioning

confidence: 99%

Correlating Coefficient of Friction and Shear Force to Platen Motor Current in Tungsten and Interlayer Dielectric Chemical Mechanical Planarization at Steady-State Conditions

Headley¹,

Frank²,

Sampurno³

et al. 2020

ECS J. Solid State Sci. Technol.

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“…Thus, a "planarization" end-point is determined by the time at which the vibration signal drops to a minimum using a slope detection algorithm. Figure 2 shows data generated from our laboratory using a commercially available accelerometer integrated into an IPEC 472 polishing system [16]. The plot shows spectral analysis of the carrier vibration signal for a family of polishing times.…”

Section: Vibrationmentioning

confidence: 99%

<title>Recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing processes</title>

Stein

Hetherington

2001

SPIE Proceedings

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Executive SummaryWe present a summary of the recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing (CMP) processes. We discuss the technical challenges and review some of the approaches that have been published and/or patented. These methods include optical, thermal (pad temperature), friction (torque motor current), electrochemical, chemical, electrical, and acoustic (vibration). We also present experimental data obtained in our laboratory using selected endpoint methods for metal and oxide CMP.Extended Abstract In-line monitoring and automatic endpoint of chemical-mechanical polishing (CMP) offers many manufacturing advantages such as improved process yields, reduced product variability, closer conformance to target requirements, and higher throughput. There are many potential payoffs however in-line monitoring and automatic endpoint is difficult to implement due to the nature of the CMP process. Ideally, output specifications such as final planarity, film thickness, and defectivity would be monitored directly in real time. There are a number of technical issues associated with equipment design, sensor performance, rotating machinery, and the harsh slurry environment. Currently, on-line metrology equipment that is integrated into the polishing tool is an attractive option for improving throughput while maintaining good quality control.

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“…Vibration spectrum analysis is a popular technique alongside others such as time domain and time-frequency domain for tracking machine operating conditions. There are already some publications in condition monitoring by accelerators [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Monitoring and meaning of vibrations in robot polishing

Schneckenburger¹,

Hoefler²,

Boerret³

et al. 2023

J. Eur. Opt. Society-Rapid Publ.

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Robot polishing is increasingly used in the production of high-end glass work pieces such as astronomy mirrors, lithography lenses, laser gyroscopes or high-precision coordinate measuring machines. The quality of optical components such as lenses or mirrors can be described by shape errors and surface roughness. Whilst the trend towards sub nanometre level surfaces finishes and features progresses, matching both form and finish coherently in complex parts remains a major challenge. With larger or more precise optics, the influence of process instabilities on the quality of the optics to be polished has a greater impact. Vibrations at a polishing head have a negative influence on the polishing result. These vibrations are caused by bearing damage, motors and other excitations (e.g. gears, belts). The aim of this work is the determination of vibrations at a polishing head and their avoidance strategies. Different bearing conditions are considered: new and perfect bearing, a bearing that has been in contact with polish (rust) and a bearing with repeatable damage (groove milled on the running surface). It can be shown that the frequencies of bearings affect the polishing tool. Furthermore, reasons for and against vibrations in the process are discussed. For the case of vibrationless machining, avoidance strategies were presented.

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Analysis of in-situ vibration monitoring for end-point detection of CMP planarization processes

Cited by 8 publications

References 1 publication

Correlating Coefficient of Friction and Shear Force to Platen Motor Current in Tungsten and Interlayer Dielectric Chemical Mechanical Planarization at Steady-State Conditions

Correlating Coefficient of Friction and Shear Force to Platen Motor Current in Tungsten and Interlayer Dielectric Chemical Mechanical Planarization at Steady-State Conditions

<title>Recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing processes</title>

Monitoring and meaning of vibrations in robot polishing

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