Query: Chemical mechanical polishing for sapphire wafers using a developed slurry

Candidate papers:

abstract: Abstract At present, corrosive ingredients are widely employed in chemical mechanical polishing (CMP) of sapphire, bringing a potential threat to both people and environment. This results in high cost and long processing time on the treatment of CMP slurry of sapphire. It is a challenge to develop a novel green CMP for sapphire to meet the stringent requirements of high performance products. In this study, a novel green CMP is proposed for sapphire, consisting of silica nanoparticles of 50 nm, triethanolamine (TEA) sodium metasilicate nonahydrate, and deionized water. After green CMP, surface roughness Ra, root mean square (rms) and peak to valley (PV) are 0.11, 0.139, and 1.65 nm, respectively. Material removal rate is 3.31 mm/h during green CMP. To the best of our knowledge, surface roughness Ra and rms after green CMP developed are the lowest on a sapphire wafer, compared with those reported previously. The CMP mechanism is elucidated by X ray photoelectron spectroscopy (XPS) and infrared (IR) spectra. Sapphire formed Al(OH)4 ions in an alkaline environment, which was chelated by TEA, and removed from the surface of sapphire. These findings provide new insights to fabricate high performance devices of sapphire for the use in semiconductor and microelectronic industries.
author_names: Zhenyu J Zhang

Weibing Hu

Lezhen Zhang

Longxing Liao
title: Chemical mechanical polishing for sapphire wafers using a developed slurry
year: 2021

abstract: Toxic and corrosive solutions are widely used in the preparation of abrasives and chemical mechanical polishing (CMP) of sapphire wafers, resulting in potential environmental pollution. Developing a novel green CMP technique to achieve light emitting diode sapphire wafers is a significant challenge. In this study, a novel green CMP slurry, consisting of silica, sorbitol, aminomethyl propanol, and deionized water was developed for sapphire wafers. After CMP, the sapphire wafers were cleaned with deionized water and dried with compressed air, which is a green process. After CMP, the surface roughness Ra of the sapphire wafer surface with an area of 5 x 5 mm2 was 0.098 nm, which is the lowest surface roughness reported to date for sapphire wafers. Tetrahydroxy coordinated Al(OH)4 ions were produced in the alkaline CMP slurry, and chelation occurred between sorbitol and these ions. The proposed green CMP has potential applications in the semiconductor and microelectronics industries.
author_names: Wenxiang Xie

Zhenyu J Zhang

Longxing Liao

Jia-wen Liu

Hongjiu Su

Shudong Wang

Dongming Guo
title: Green chemical mechanical polishing of sapphire wafers using a novel slurry.
venue: Nanoscale
year: 2020

abstract: A novel chemical mechanical polishing (CMP) solution was developed. The CMP solution developed consisted of mainly silica, hydrogen peroxide, and malic acid. CMP solution is environment friendly, which is different from those used in conventional CMP, consisting of acids or organic solvents. Fixed abrasive waterproof paper of alumina with mesh size of 3000 was used as lapping tool, to avoid embedding of free abrasives on soft cadmium zinc telluride (CdZnTe or CZT) surfaces employed in traditional lapping processes. The diameter of silica was varied from several tens of nanometers to 100 nanometers. Surface roughness Ra, and PV achieved using fixed abrasive lapping and developed CMP solution are 0.6 nm and 6.3 nm, respectively. The polished CZT surface was cleaned by deionized water and dried using compressed air, to avoid damages induced by conventional physical wiping and ultrasonic cleaning on soft brittle CZT wafers.
author_names: Zhenyu J Zhang

Bo Wang

Y X Song
title: Chemical Mechanical Polishing of Soft Brittle Cadmium Zinc Telluride Wafers Using a Developed Environment Friendly Solution
year: 2014

abstract: AUTHORS AND INSTITUTIONS Yan Zhou Guoshun Pan a,b, Hua Gong Chunli Zou Li Xu a,b,c a State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China, pangs@tsinghua.edu.cn b Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China c Guangdong Provincial Key Laboratory of Optomechatronics, Shenzhen 518057, China
author_names: Yan Zhou

Guoshun Pan

Hua Gong

Chunli Zou

Li Xu
title: CHEMICAL MECHANICAL POLISHING OF SAPPHIRE WAFER USING MIXED SILICA NANOPARTICLES
year: 2016

abstract: The study mainly explores the fabrication mechanism for fabricating sapphire wafer substrate, by using chemical mechanical polishing (CMP) method. A slurry containing the abrasive particles of SiO2 is used to contact with the sapphire substrate polish and to produce chemical reaction for removal of sapphire wafer substrate when CMP method is used. The study observes the changes of the removal amount of sapphire wafer substrate when the pattern free polishing pad and hole pattern polishing pad are used under different down forces, polishing velocities, abrasive particle sizes and slurry concentrations. Employing regression analysis theory, the study makes improvement of the equation of material removal rate (MRR) to be the material removal height per 30 minutes (MRRh) and develops a compensation parameter Crv of the error caused by the volume concentration of slurry. The results of experimental analysis show that under a certain down force, if the polishing velocity is greater, the material removal amount will be greater. Generally speaking, the material removal amount of hole pattern polishing pad is greater than that of pattern free polishing pad. As to the relationship between abrasive particle size and slurry concentration, when particle size is smaller, the volume concentration of slurry will be higher, and the number of abrasives for polishing wafer will be greater. As a result, a better material removal depth can be acquired. Through the above analytical results, considerable help is offered to the polishing of sapphire wafer.
author_names: Zone-Ching Lin

Wei-Shuen Huang

Ju-Shiau Tsai
title: A study of material removal amount of sapphire wafer in application of chemical mechanical polishing with different polishing pads
year: 2012

abstract: Abstract A novel semi empirical model was developed for predicting the material removal rate (MRR) during chemical mechanical polishing (CMP) based on the following assumptions: plastic contact at the wafer particle interface, elastic contact at the pad particle interface, a particle size distribution, and a randomly distributed surface roughness of the polishing pad. The proposed model incorporates the effects of particle size, concentration, and distribution, as well as the slurry flow rate, pad surface topography, material properties, and chemical reactions during the silicon dioxide (SiO 2 CMP. To obtain the unknown parameters and ensure the validity of the model, a SiO 2 CMP experiment was conducted by using various sized CMP slurries. The spatial distribution of the MRRs is expressed with respect to the normal contact stress distribution and the relative velocity distribution. The proposed MRR model can be used for the development of a CMP simulator, the optimization of CMP process parameters, and the design of next generation CMP machines.
author_names: H S Lee

Hae-do Jeong

David A Dornfeld
title: Semi empirical material removal rate distribution model for SiO2 chemical mechanical polishing (CMP) processes
year: 2013

abstract: This paper presents the results of a study to develop chemical mechanical polishing (CMP) processes for 3C SiC films using commercial polishing pads in conjunction with basic colloidal SiO 2 acidic colloidal Al 2 O 3 and near neutral SiC slurries. The removal rate and surface roughness of the 3C SiC surfaces were measured for the three slurries. The SiC based slurry had the highest removal rate at 0.58 mm/h. while the colloidal SiO 2 slurry produced surfaces with the lowest average roughness at 15 A. The removal rates of the Al 2 O 3 slurries were found to be too low for practical applications. The surface chemistry and morphology of the as deposited and polished 3C SiC films were characterized using X ray photoelectron spectroscopy and atomic force microscopy in order to gain insight into the physical and chemical mechanisms in the process.
author_names: Xiao-an Fu

Christian A Zorman

Mehran Mehregany
title: Chemical Mechanical Polishing of Cubic Silicon Carbide Films Grown on Si(100) Wafers
year: 2002

abstract: Diamond disk conditioners have long served the semiconductor chemical mechanical polishing (CMP) process for polish pad dressing. While the diameter of wafers has steadily increased and the lower line gap distance is developing in order to improve its efficiency, a better polish performance is our pursuing target. However, the slurry in polishing processes, which can lead not only to uniform corrosion but also to crevice attack and pitting for pad conditioners. To further improve the performance and quality of diamond disk conditioners, the corrosion Fang Shi Gong Cheng Di Er Shi Juan Di Er Qi Di 163~ 168 Ye 2006 Nian 6 Yue Journal of Chinese Corrosion Engineering, Vol. 20, No. 2, pp. 163~168 (2006) ________________________________________________ 1 Qing Yun Ke Ji Da Xue 1 Ching Yun University 2 Zhong Guo Sha Lun 2 KINIK Company Lian Luo Zuo Zhe :ahtan@cyu.edu.tw Fang Shi Gong Cheng Di Er Shi Juan Di Er Qi 2006 Nian 6 Yue 164resistance is the first consideration of dressing in the CMP corrosive slurry. Diamond like carbon (DLC) for protecting applications were of great interest to researchers in recent years because of their excellent properties such as dielectric insulation, low friction, high wear resistance, high hardness and corrosion resistance. Improving the corrosion resistance and keeping the diamond powder working well become very challengeing when pad conditioners are immersed in a corrosive environment. In this study, DLC were deposited on the mixed surface layer of diamond powder and Ni/Cr alloy for a protective layer by physical vapor deposition. This study investigated the corrosion behavior of DLC protective layers in the slurry by electrochemical techniques, including the potentio dynamic polarization test and electrochemical impedance spectroscopy (EIS) SEM was used to analyze the surface morphology of the conditioner after corrosion.
author_names: A H Tan

Y C Cheng

Chi Kang Lee

Jacky Chou

James C Sung
title: Corrosion Investigation of Diamond Disk Conditioner in the Slurry of Chemical Mechanical Polishing
year: 2006

abstract: Polydimethylsiloxane (PDMS) posts with a diameter of 80 m were used to measure the shearing forces at the wafer pad interface during chemical mechanical planarization (CMP) Measurements are made at 10 kHz with measurable forces between 40 and 400 N. The structures were polished using a stiff, ungrooved pad and 3 wt fumed silica slurry at velocities of 0.3 and 0.6 m/s and average wafer pad normal load of 5.0 and 9.1 kPa. Due to the small fraction of the pad that contacts the wafer, the local microscale forces can be much larger than the global average force might suggest. Observed lateral forces on the structures averaged, in time, between 230 and 310 N with RMS deviations of the force about the mean between 47 and 64 N. The faster polishing case shows a 30% higher mean force, and a 20% reduction in the RMS variation of force. Little change is seen in the force characteristics when increasing from 5.0 to 9.1 kPa downforce. A mathematical model is developed to interpret these forces, allowing estimation of the local pad properties. The model suggests that 5000 asperity contacts are present per square millimeter, asperity lateral stiffness is 0.3 N/m, and asperity slip off force is 19 N. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3616021] All rights reserved.
author_names: Robert D White

Andrew Mueller

Minchul Shin

Douglas A Gauthier

Vincent P Manno

Chris Rogers
title: Measurement of Microscale Shear Forces during Chemical Mechanical Planarization
year: 2011

abstract: The mechanism of chemical mechanical polishing (CMP) is so complicated because there is synergy between chemical and mechanical action. We studied the effect of particels in CMP by MD simulation theoreticaly and liquid jet simulation experimentaly. The results show that MD simulation and slurry jet test have the similar result. For MD simulation, during the collision there are material adhesion and transfer between particle and surface. The pit bottom is not flat in both MD simulation and collision test, this is because the particle rotates during the collision. The pit area and depth increase with the particle energy. The effect of chemical reaction under mechanical action in CMP is studied. With mechanical action, the density of exposed fresh surface increases during the CMP process. The thoretical analysis shows that the corrosion current with the mechanical action is extremely increased at least 100 times than the static corrosion. CMP applications in SKLT are also introduced in this presentation. We have developed CMP slurries for hard disk substrate, silicon wafer and sapphire wafer as LED substrate. These slurries have already been used in China.
author_names: Xinchun Lu

Guoshun Pan

Jianbin Luo
title: Mechanism and Applications of Chemical and Mechanical Polishing
year: 2009