Applications of Raman Spectroscopy in Cu-CMP and in BEOL Cleaning Chemistries

Persistent Link:
http://hdl.handle.net/10150/193710
Title:
Applications of Raman Spectroscopy in Cu-CMP and in BEOL Cleaning Chemistries
Author:
Kondoju, Siddartha
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In copper chemical mechanical planarization (CMP), in situ detection of barrier to dielectric layer transition is typically done using an optical reflectance technique. The introduction of carbon doped oxides (CDOs) as low-dielectric constant (k) materials for dielectric layers has opened up the possibility of using spectroscopic techniques for detecting such transitions more efficiently. The vibrational frequencies of the bonds between C, H, O, and Si in these low-k materials may be readily detected by spectroscopic techniques such as Raman and infrared (IR) spectroscopies. Since CMP is carried out in aqueous media, IR spectroscopy is not very desirable due to strong absorption of water in the same region as C-H vibrations (2800 cm⁻¹ to 3300 cm⁻¹). In contrast, Raman spectroscopy shows minimal water interference and can be used to efficiently monitor the signal from CDO films even in aqueous environments that prevail under CMP conditions. The research reported in this dissertation concerns the use of Raman spectroscopy in detecting the transition from tantalum (Ta) barrier layer to CDO dielectric layer, insitu. Intensities of Raman peaks characteristic of Si-Si vibrations from silicon substrates and C-H vibrations from low-k materials were used for monitoring CDO thickness and detecting removal of Ta layer. An abrasion cell was integrated with a Raman spectrometer to demonstrate the feasibility of Raman monitoring in-situ. Additionally, an alternative method was investigated for monitoring transitions in highly fluorescent low-k materials where Raman can not be used. The fluorescence intensity was used to effectively monitor Ta to low-k transitions. As a secondary objective, the Raman technique was used to monitor the composition of polishing slurries, which in the case of copper CMP, have a rich chemistry, which may change during the course of polishing due to consumption and decomposition of certain constituents. Various aspects, such as small layer thickness (<50 μm), continuous flow of the slurry, and dynamics of the film removal process pose a great challenge to the monitoring of slurry components between the pad and the wafer. The slurry constituents such as oxidants and corrosion inhibitors have unique signatures that can be detected using spectroscopic techniques. In this study Raman spectroscopy was used to detect and quantify chemical species such as hydroxylamine, benzotriazole and hydrogen peroxide in-situ. A more detailed study pertaining to the protonation of hydroxylamine with respect to the pH was also performed. Finally, surface enhanced Raman spectroscopy (SERS) was also investigated to improve the detection of pyridine and benzotriazole at low concentrations (<100 ppm).
Type:
text; Electronic Dissertation
Keywords:
Cu-CMP; Raman Spectroscopy; low-k; CMP
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Materials Science & Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Raghavan, Srini
Committee Chair:
Raghavan, Srini

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleApplications of Raman Spectroscopy in Cu-CMP and in BEOL Cleaning Chemistriesen_US
dc.creatorKondoju, Siddarthaen_US
dc.contributor.authorKondoju, Siddarthaen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn copper chemical mechanical planarization (CMP), in situ detection of barrier to dielectric layer transition is typically done using an optical reflectance technique. The introduction of carbon doped oxides (CDOs) as low-dielectric constant (k) materials for dielectric layers has opened up the possibility of using spectroscopic techniques for detecting such transitions more efficiently. The vibrational frequencies of the bonds between C, H, O, and Si in these low-k materials may be readily detected by spectroscopic techniques such as Raman and infrared (IR) spectroscopies. Since CMP is carried out in aqueous media, IR spectroscopy is not very desirable due to strong absorption of water in the same region as C-H vibrations (2800 cm⁻¹ to 3300 cm⁻¹). In contrast, Raman spectroscopy shows minimal water interference and can be used to efficiently monitor the signal from CDO films even in aqueous environments that prevail under CMP conditions. The research reported in this dissertation concerns the use of Raman spectroscopy in detecting the transition from tantalum (Ta) barrier layer to CDO dielectric layer, insitu. Intensities of Raman peaks characteristic of Si-Si vibrations from silicon substrates and C-H vibrations from low-k materials were used for monitoring CDO thickness and detecting removal of Ta layer. An abrasion cell was integrated with a Raman spectrometer to demonstrate the feasibility of Raman monitoring in-situ. Additionally, an alternative method was investigated for monitoring transitions in highly fluorescent low-k materials where Raman can not be used. The fluorescence intensity was used to effectively monitor Ta to low-k transitions. As a secondary objective, the Raman technique was used to monitor the composition of polishing slurries, which in the case of copper CMP, have a rich chemistry, which may change during the course of polishing due to consumption and decomposition of certain constituents. Various aspects, such as small layer thickness (<50 μm), continuous flow of the slurry, and dynamics of the film removal process pose a great challenge to the monitoring of slurry components between the pad and the wafer. The slurry constituents such as oxidants and corrosion inhibitors have unique signatures that can be detected using spectroscopic techniques. In this study Raman spectroscopy was used to detect and quantify chemical species such as hydroxylamine, benzotriazole and hydrogen peroxide in-situ. A more detailed study pertaining to the protonation of hydroxylamine with respect to the pH was also performed. Finally, surface enhanced Raman spectroscopy (SERS) was also investigated to improve the detection of pyridine and benzotriazole at low concentrations (<100 ppm).en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectCu-CMPen_US
dc.subjectRaman Spectroscopyen_US
dc.subjectlow-ken_US
dc.subjectCMPen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMaterials Science & Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRaghavan, Srinien_US
dc.contributor.chairRaghavan, Srinien_US
dc.contributor.committeememberLucas, Pierreen_US
dc.contributor.committeememberPotter, B. G.en_US
dc.contributor.committeememberParks, Harold G.en_US
dc.contributor.committeememberFischer, Paulen_US
dc.identifier.proquest2174en_US
dc.identifier.oclc659747269en_US
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