subject:(Etch residue)

University of Arizona

1. Padmanabhan Ramalekshmi Thanu, Dinesh. USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION .

Degree: 2011, University of Arizona

URL: http://hdl.handle.net/10150/202981

► Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by… (more)

▼ Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by plasma etching of low-k dielectric layers to form vias and trenches, and this process typically leaves behind polymer-like post etch residues (PER) containing copper oxides, copper fluorides and fluoro carbons, on underlying copper and sidewalls of low-k dielectrics. Effective removal of PER is crucial for achieving good adhesion and low contact resistance in the interconnect structure, and this is accomplished using wet cleaning and rinsing steps. Currently, the removal of PER is carried out using semi-aqueous fluoride based formulations. To reduce the environmental burden and meet the semiconductor industry's environmental health and safety requirements, there is a desire to completely eliminate solvents in the cleaning formulations and explore the use of organic solvent-free formulations.The main objective of this work is to investigate the selective removal of PER over copper and low-k (Coral and Black Diamond®) dielectrics using all-aqueous dilute HF (DHF) solutions and choline chloride (CC) - urea (U) based deep eutectic solvent (DES) system. Initial investigations were performed on plasma oxidized copper films. Copper oxide and copper fluoride based PER films representative of etch products were prepared by ashing g-line and deep UV photoresist films coated on copper in CF4/O2 plasma. PER removal process was characterized using scanning electron microscopy and X-ray photoelectron spectroscopy and verified using electrochemical impedance spectroscopy measurements.A PER removal rate of ~60 Å/min was obtained using a 0.2 vol% HF (pH 2.8). Deaeration of DHF solutions improved the selectivity of PER over Cu mainly due to reduced Cu removal rate. A PER/Cu selectivity of ~20:1 was observed in a 0.05 vol% deaerated HF (pH 3). DES systems containing 2:1 U/CC removed PER at a rate of ~10 and ~20 Å/min at 40 and 70 °C respectively. A mixture of 10-90 vol% de-ionized water (W) with 2:1 U/CC in the temperature range of 20 to 40 °C also effectively removed PER. Importantly, etch rate of copper and low-k dielectric in DES formulations were lower than that in conventional DHF cleaning solutions. Advisors/Committee Members: Raghavan, Srini (advisor), Raghavan, Srini (committeemember), Lucas, Pierre (committeemember), Muralidharan, Krishna (committeemember), Keswani, Manish (committeemember).

Subjects/Keywords: Dilute Hydrofluoric Acid; Integrated Circuit Fabrication; Post Etch Residue Removal; Materials Science & Engineering; Back End of Line Cleaning; Deep Eutectic Solvents

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APA (6^th Edition):

Padmanabhan Ramalekshmi Thanu, D. (2011). USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/202981

Chicago Manual of Style (16^th Edition):

Padmanabhan Ramalekshmi Thanu, Dinesh. “USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION .” 2011. Doctoral Dissertation, University of Arizona. Accessed January 16, 2021. http://hdl.handle.net/10150/202981.

MLA Handbook (7^th Edition):

Padmanabhan Ramalekshmi Thanu, Dinesh. “USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION .” 2011. Web. 16 Jan 2021.

Vancouver:

Padmanabhan Ramalekshmi Thanu D. USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION . [Internet] [Doctoral dissertation]. University of Arizona; 2011. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10150/202981.

Council of Science Editors:

Padmanabhan Ramalekshmi Thanu D. USE OF DILUTE HYDROFLUORIC ACID AND DEEP EUTECTIC SOLVENT SYSTEMS FOR BACK END OF LINE CLEANING IN INTEGRATED CIRCUIT FABRICATION . [Doctoral Dissertation]. University of Arizona; 2011. Available from: http://hdl.handle.net/10150/202981

Georgia Tech

2. Timmons, Christopher L. Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

URL: http://hdl.handle.net/1853/10583

► During fabrication of integrated circuits, fluorocarbon plasma etching is used to pattern dielectric layers. As a byproduct of the process, a fluorocarbon residue is deposited… (more)

▼ During fabrication of integrated circuits, fluorocarbon plasma etching is used to pattern dielectric layers. As a byproduct of the process, a fluorocarbon residue is deposited on exposed surfaces and must be removed for subsequent processing. Conventional fluorocarbon cleaning processes typically include at least one plasma or liquid treatment that is oxidative in nature. Oxidative chemistries, however, cause material degradation to next generation low-dielectric constant (low-k) materials that are currently being implemented into fabrication processes. This work addresses the need for alternative fluorocarbon-residue removal chemistries that are compatible with next generation low-k materials. Radical anion chemistries are known for their ability to defluorinate fluorocarbon materials by a reductive mechanism. Naphthalene radical anion solutions, generated using sodium metal, are used to establish cleaning effectiveness with planar model residue films. The penetration rate of the defluorination reaction into model fluorocarbon film residues is measured and modeled. Because sodium is incompatible with integrated circuit processing, naphthalene radical anions are alternatively generated using electrochemical techniques. Using electrochemically-generated radical anions, residue removal from industrially patterned etch structures is used to evaluate the process cleaning efficiency. Optimization of the radical anion concentration and exposure time is important for effective residue removal. The efficiency of removal also depends on the feature spacing and the electrochemical solvent chosen. The synergistic combination of radical anion defluorination and wetting or swelling of the residue by the solvent is necessary for complete removal. In order to understand the interaction between the solvent and the residue, the surface and interfacial energy are determined using an Owens/Wendt analysis. These studies reveal chemical similarities between specific solvents and the model residue films. This approach can also be used to predict residue or film swelling by interaction with chemically similar solvents. Advisors/Committee Members: Hess, Dennis (Committee Chair), Kohl, Paul (Committee Member), Liotta, Charles (Committee Member), Meredith, Carson (Committee Member), Schork, Joseph (Committee Member).

Subjects/Keywords: Radical anions; Fluorocarbon post-etch residue; Semiconductors Cleaning; Anions; Semiconductor wafers Cleaning

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APA (6^th Edition):

Timmons, C. L. (2004). Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/10583

Chicago Manual of Style (16^th Edition):

Timmons, Christopher L. “Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry.” 2004. Doctoral Dissertation, Georgia Tech. Accessed January 16, 2021. http://hdl.handle.net/1853/10583.

MLA Handbook (7^th Edition):

Timmons, Christopher L. “Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry.” 2004. Web. 16 Jan 2021.

Vancouver:

Timmons CL. Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1853/10583.

Council of Science Editors:

Timmons CL. Fluorocarbon Post-Etch Residue Removal Using Radical Anion Chemistry. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/10583

3. Taubert, Jenny. Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication .

Degree: 2013, University of Arizona

URL: http://hdl.handle.net/10150/283692

► Interconnection layers fabricated during back end of line processing in semiconductor manufacturing involve dry etching of a low-k material and deposition of copper and metal… (more)

▼ Interconnection layers fabricated during back end of line processing in semiconductor manufacturing involve dry etching of a low-k material and deposition of copper and metal barriers to create copper/dielectric stacks. After plasma etching steps used to form the trenches and vias in the dielectric, post etch residues (PER) that consist of organic polymer, metal oxides and fluorides, form on top of copper and low-k dielectric sidewalls. Currently, most semiconductor companies use semi aqueous fluoride (SAF) based formulations containing organic solvent(s) for PER removal. Unfortunately, these formulations adversely impact the environmental health and safety (EHS) requirements of the semiconductor industry. Environmentally friendly "green" formulations, free of organic solvents, are preferred as alternatives to remove PER. In this work, a novel low temperature molten salt system, referred as deep eutectic solvent (DES) has been explored as a back end of line cleaning (BEOL) formulation. Specifically, the DES system comprised of two benign chemicals, malonic acid (MA) and choline chloride (CC), is a liquid at room temperature. In certain cases, the formulation was modified by the addition of glacial acetic acid (HAc). Using these formulations, selective removal of three types of PER generated by timed CF₄/O₂ etching of DUV PR films on Cu was achieved. Type I PER was mostly organic in character (fluorocarbon polymer type) and had a measured thickness of 160 nm. Type II PER was much thinner (25 nm) and consisted of a mixture of organic and inorganic compounds (copper fluorides). Further etching generated 17 nm thick Type III PER composed of copper fluorides and oxides. Experiments were also conducted on patterned structures. Cleaning was performed by immersing samples in a temperature controlled (30 or 40° C) double jacketed vessel for a time between 1 and 5 minutes. Effectiveness of cleaning was characterized using SEM, XPS and single frequency impedance measurements. Type II and III residues, which contained copper compounds were removed in CC/MA DES within five minutes through dissolution and subsequent complexation of copper by malonic acid. Removal of Type I PER required the addition of glacial acetic acid to the DES formulation. Single frequency impedance measurement appears to be a good in situ method to follow the removal of the residues. High water solubility of the components of the system in conjunction with their environmental friendly nature, make the DES an attractive alternative to SAF. Advisors/Committee Members: Raghavan, Srini (advisor), Uhlmann, Donald R. (committeemember), Saez, Eduardo A. (committeemember), Muralidharan, Krishna (committeemember), Raghavan, Srini (committeemember).

Subjects/Keywords: Characterization of Post Etch Residue; Deep Eutectic Solvents; Post Etch Residue Cleaning; Materials Science & Engineering; Back End of Line Cleaning

…APPENDIX A. POST ETCH RESIDUE REMOVAL USING CHOLINE CHLORIDEMALONIC ACID DEEP EUTECTIC SOLVENT… …cleaning formulation to remove predominantly inorganic post etch residue. This basic formulation… …x28;hydroxystyrene) (PHOST) backbone. Post etch residue of different chemical… …and ashing are followed by wet cleaning to remove any post etch residue. Figure 1.2 Copper… …systematic study of post etch residue formation during reactive ion plasma etching (RIE)…

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Taubert, J. (2013). Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/283692

Chicago Manual of Style (16^th Edition):

Taubert, Jenny. “Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication .” 2013. Doctoral Dissertation, University of Arizona. Accessed January 16, 2021. http://hdl.handle.net/10150/283692.

MLA Handbook (7^th Edition):

Taubert, Jenny. “Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication .” 2013. Web. 16 Jan 2021.

Vancouver:

Taubert J. Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication . [Internet] [Doctoral dissertation]. University of Arizona; 2013. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/10150/283692.

Council of Science Editors:

Taubert J. Use of Formulations Based On Choline Chloride-Malonic Acid Deep Eutectic Solvent for Back End of Line Cleaning in Integrated Circuit Fabrication . [Doctoral Dissertation]. University of Arizona; 2013. Available from: http://hdl.handle.net/10150/283692

Georgia Tech

4. Myneni, Satyanarayana. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

URL: http://hdl.handle.net/1853/7605

► As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several… (more)

▼ As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several challenges. A cleaning process should be environmentally benign, compatible with dielectric materials and copper, and provide residue removal from narrow and high aspect ratio features. In this work, sub-critical CO2 based mixtures have been developed to remove the etch residues; these mixtures satisfy the above requirements and can potentially replace the two step residue removal process currently used in the integrated circuit (IC) industry. Based on the chemical nature of the residue being removed, additives or co-solvents to CO2 have been identified that can remove the residues without damaging the dielectric layers. Using the phase behavior of these additives as a guide, the composition of the co-solvent was altered to achieve a single liquid phase at moderate pressures without compromising cleaning ability. The extent of residue removal has been analyzed primarily by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Various techniques such as attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy, angle-resolved XPS (ARXPS), and interferometry were used to probe the interaction of cleaning fluids with residues. Model films of photoresists and plasma deposited residues were used to assist in understanding the mechanism of residue removal. From these studies, it was concluded that residue removal takes place primarily by attack of the interface between the residue and the substrate; a solvent rinse then lifts these residues from the wafer. It has been shown that transport of the additives to the interface is enhanced in the presence of CO2. From positronium annihilation lifetime spectroscopy (PALS) studies on a porous dielectric film, it has been shown that these high pressure fluids do not cause significant changes to the pore sizes or the bonding structure of the film. Hence, this method can be used to remove post etch residues from low-k dielectric films. Advisors/Committee Members: Dr. Dennis W. Hess (Committee Chair), Dr. Amyn S. Teja (Committee Member), Dr. Charles A. Eckert (Committee Member), Dr. Charles L. Liotta (Committee Member), Dr. J. Carson Meredith (Committee Member).

Subjects/Keywords: Low-K; Angle resolved XPS; Surface cleaning; Supercritical carbon dioxide; ATR-FTIR; Fluorocarbon residue; Etch residue; Semiconductors Cleaning; Plasma etching; Liquid carbon dioxide Industrial applications

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Myneni, S. (2004). Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/7605

Chicago Manual of Style (16^th Edition):

Myneni, Satyanarayana. “Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.” 2004. Doctoral Dissertation, Georgia Tech. Accessed January 16, 2021. http://hdl.handle.net/1853/7605.

MLA Handbook (7^th Edition):

Myneni, Satyanarayana. “Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids.” 2004. Web. 16 Jan 2021.

Vancouver:

Myneni S. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1853/7605.

Council of Science Editors:

Myneni S. Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/7605

Georgia Tech

5. Song, Ingu. Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue.

Degree: PhD, Chemical Engineering, 2007, Georgia Tech

URL: http://hdl.handle.net/1853/26473

► Progress in the microelectronics industry is driven by smaller and faster transistors. As feature sizes in integrated circuits become smaller and liquid chemical waste becomes… (more)

Subjects/Keywords: Etch residue; GXL; Photoresist; Gas expanded liquids; Carbon dioxide; Solvents; Carbon dioxide; Microelectronics industry; Sustainable engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Song, I. (2007). Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26473

Chicago Manual of Style (16^th Edition):

Song, Ingu. “Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue.” 2007. Doctoral Dissertation, Georgia Tech. Accessed January 16, 2021. http://hdl.handle.net/1853/26473.

MLA Handbook (7^th Edition):

Song, Ingu. “Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue.” 2007. Web. 16 Jan 2021.

Vancouver:

Song I. Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue. [Internet] [Doctoral dissertation]. Georgia Tech; 2007. [cited 2021 Jan 16]. Available from: http://hdl.handle.net/1853/26473.

Council of Science Editors:

Song I. Role of carbon dioxide in gas expanded liquids for removal of photoresist and etch residue. [Doctoral Dissertation]. Georgia Tech; 2007. Available from: http://hdl.handle.net/1853/26473

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