Optimization of Ammonia-Peroxide Water Mixture (APM) for High Volume Manufacturing through Surface Chemical Investigations

Persistent Link:
http://hdl.handle.net/10150/201511
Title:
Optimization of Ammonia-Peroxide Water Mixture (APM) for High Volume Manufacturing through Surface Chemical Investigations
Author:
Siddiqui, Shariq
Issue Date:
2011
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:
Ammonia-peroxide mixture (APM) is a widely used wet chemical system for particle removal from silicon surfaces. The conventional APM solution in a volume ratio of 1:1:5 (NH4OH:H2O2:H2O) is employed at elevated temperatures of 70-80 °C. At these temperatures, APM solution etches silicon at a rate of ~3 Å/min, which is unacceptable for current technology node. Additionally, APM solutions are unstable due to the decomposition of hydrogen peroxide and evaporative loss of ammonium hydroxide resulting in the change in APM solution composition. This has generated interest in the use of dilute APM solutions. However, dilution ratios are chosen without any established fundamental relationship between particle-wafer interactions and APM solutions.Atomic force microscopy has been used to measure interaction forces between H-terminated Si surface and Si tip in APM solutions of different compositions. The approach force curves results show attractive forces in DI-water, NH4OH:H2O (1:100) and H2O2:H2O (1:100) solutions at separation distances of less than 10 nm for all immersion times (2, 10 and 60 min) investigated. In the case of dilute APM solutions, the forces are purely repulsive within 2 min of immersion time. During retraction, the adhesion force between Si surface and Si tip was in the range of 0.8 nN to 10.0 nN. In dilute APM solutions, no adhesion force is measured between Si surfaces and repulsive forces dominated at all distances. These results show that even in very dilute APM solutions, repulsive forces exist between Si surface and particle re-deposition can be prevented.The stability of APM solutions has been investigated as a function of temperature (24 - 65 °C), dilution ratio (1:1:5 - 1:2:100), solution pH (8.0 - 9.7) and Fe2+ concentration (0 - 10 ppb) using an optical concentration monitor. The results show that the rate of H2O2 decomposition increased with an increase in temperature, solution pH and Fe2+ concentration. The kinetic analysis showed that the H2O2 decomposition follows a first order kinetics with respect to both H2O2 and OH- concentrations. In the presence of Fe2+, hydrogen peroxide decomposition follows a first order reaction kinetics with respect to H2O2 concentration.
Type:
text; Electronic Dissertation
Keywords:
Materials Science & Engineering
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Materials Science & Engineering
Degree Grantor:
University of Arizona
Advisor:
Raghavan, Srini

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleOptimization of Ammonia-Peroxide Water Mixture (APM) for High Volume Manufacturing through Surface Chemical Investigationsen_US
dc.creatorSiddiqui, Shariqen_US
dc.contributor.authorSiddiqui, Shariqen_US
dc.date.issued2011-
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.abstractAmmonia-peroxide mixture (APM) is a widely used wet chemical system for particle removal from silicon surfaces. The conventional APM solution in a volume ratio of 1:1:5 (NH4OH:H2O2:H2O) is employed at elevated temperatures of 70-80 °C. At these temperatures, APM solution etches silicon at a rate of ~3 Å/min, which is unacceptable for current technology node. Additionally, APM solutions are unstable due to the decomposition of hydrogen peroxide and evaporative loss of ammonium hydroxide resulting in the change in APM solution composition. This has generated interest in the use of dilute APM solutions. However, dilution ratios are chosen without any established fundamental relationship between particle-wafer interactions and APM solutions.Atomic force microscopy has been used to measure interaction forces between H-terminated Si surface and Si tip in APM solutions of different compositions. The approach force curves results show attractive forces in DI-water, NH4OH:H2O (1:100) and H2O2:H2O (1:100) solutions at separation distances of less than 10 nm for all immersion times (2, 10 and 60 min) investigated. In the case of dilute APM solutions, the forces are purely repulsive within 2 min of immersion time. During retraction, the adhesion force between Si surface and Si tip was in the range of 0.8 nN to 10.0 nN. In dilute APM solutions, no adhesion force is measured between Si surfaces and repulsive forces dominated at all distances. These results show that even in very dilute APM solutions, repulsive forces exist between Si surface and particle re-deposition can be prevented.The stability of APM solutions has been investigated as a function of temperature (24 - 65 °C), dilution ratio (1:1:5 - 1:2:100), solution pH (8.0 - 9.7) and Fe2+ concentration (0 - 10 ppb) using an optical concentration monitor. The results show that the rate of H2O2 decomposition increased with an increase in temperature, solution pH and Fe2+ concentration. The kinetic analysis showed that the H2O2 decomposition follows a first order kinetics with respect to both H2O2 and OH- concentrations. In the presence of Fe2+, hydrogen peroxide decomposition follows a first order reaction kinetics with respect to H2O2 concentration.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectMaterials Science & Engineeringen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineMaterials Science & Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRaghavan, Srinien_US
dc.contributor.committeememberSeraphin, Supapanen_US
dc.contributor.committeememberZhang, Jinhongen_US
dc.contributor.committeememberKeswani, Manishen_US
dc.contributor.committeememberRaghavan, Srinien_US
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