A New Permanganate-Free Slurry for GaN-SiC CMP Applications

2020 ◽  
Vol 1004 ◽  
pp. 199-205
Author(s):  
Treliant Fang ◽  
Ping Chung Chen ◽  
Ming Hsun Lee
Keyword(s):  
Removal Rate ◽  
Waste Water Treatment ◽  
High Hardness ◽  
Wide Band ◽  
Sodium Chlorite ◽  
Toxic Heavy Metal ◽  
Wafer Polishing ◽  
Single Crystal Sic ◽  
Buffer Control ◽  
Ph Buffer

Single crystal SiC wafers are known to be extremely difficult to polish by conventional CMP slurries because of their high hardness and chemical resistance. Previously only those manganese-containing CMP slurries are capable of producing measurable and useful polishing rates with this versatile wide band-gap substrate. A new permanganate-free SiC polishing slurry containing a generic formula of MXO2 etchant, where M is an alkali metal, X is a halogen, O is oxygen is disclosed. When mixed with an abrasive powder in an aqueous slurry form, the tribochemical reactant that activates under pressure, etches SiC effectively, rendering an enhanced Material Removal Rate (MRR) when processing CMP SiC wafers. The MRR can sometimes go up to a few order of magnitudes, as compared to the abrasive slurry without these chemical etchants. The series of MXO2 compounds that can activate SiC polishing belong to the chemical family of halites. Sodium chlorite, NaClO2, the simplest and most available member of the halites family, is a good example. The accelerated polishing rates offer increased throughput of the slow SiC CMP process. The new slurry is particularly useful for non-oxide wafer polishing, which includes SiC, GaN and AlN wafers. An outstanding character of the new halite-based polishing formulation that is different from the current permanganate-based slurries is that the waste stream produced from the CMP process can be easily treated in the waste water treatment facilities because they do not contain toxic heavy metal ions such as manganese and permanganate in the polishing formulations. Continuous exhaustive CMP polishing test with 32 4” 4H-N SiC wafers using a production CMP tool containing 32L of the alumina-chlorite slurry has demonstrated an MRR of 1.7um/hr (Si-face) when the slurry is fresh, and a final MRR of 1.0um/hr after 16 hours polishing at 800mL/min slurry flow rate with pH buffer control without fresh oxidant addition. The resulting 32 polished 4H-SiC test wafers show overall excellent smooth surface roughness with the best Ra of 0.05nm by AFM after fine CMP polishing.

The Effect of Mixed Abrasive Slurry on CMP of 6H-SiC Substrate

2008 ◽  
Vol 569 ◽  
pp. 133-136 ◽  
Author(s):  
Ho Jun Lee ◽  
Boum Young Park ◽  
Hyun Seop Lee ◽  
Suk Hoon Jeong ◽  
Heon Deok Seo ◽  
...  
Keyword(s):  
Removal Rate ◽  
Substrate Surface ◽  
High Hardness ◽  
Wide Band ◽  
Mechanical Polishing ◽  
Chemical Effect ◽  
Wide Band Gap ◽  
Mechanical Removal ◽  
Device Applications ◽  
Mechanical Factors

Silicon carbide (SiC) is a wide band gap semiconductor being developed for high temperature, high power, and high frequency device applications. For the manufacturing of SiC to semiconductor substrate, many researchers have studied on the subject of SiC polishing. However, SiC faces many challenges for wafer preparation prior to epitaxial growth due to its high hardness and remarkable chemical inertness. A smooth and defect free substrate surface is important for obtaining good epitaxial layers. Therefore, hybrid process, chemical mechanical polishing (CMP) has been proposed to achieve epi-ready surface. In this paper, the material removal rate (MRR) is investigated to recognize how long the CMP process continues to remove a damaged layer by mechanical polishing using 100 nm sized diamond, and the authors tried to find the dependency of mechanical factors such as pressure, velocity and abrasive concentration using single abrasive slurry (SAS). Especially, the authors tried to get an epi-ready surface with mixed abrasive slurry (MAS). The addition of the 25nm sized diamond in MAS provided strong synergy between mechanical and chemical effects resulting in low subsurface damage. Through experiments with SAS and MAS, it was found that chemical effect (KOH based) was essential and atomic-bit mechanical removal was efficient to remove residual scratches in MAS. This paper concluded that SiC CMP mechanism was quite different from that of relatively soft material to achieve both of high quality surface and MRR.

Chemically Assisted Machining of Ceramics

1994 ◽  
Vol 116 (3) ◽  
pp. 423-429 ◽  
Author(s):  
J. C. Wang ◽  
S. M. Hsu
Keyword(s):  
Material Removal ◽  
Removal Rate ◽  
High Hardness ◽  
Chemical Compounds ◽  
Surface Damage ◽  
Diamond Wheel ◽  
Halogenated Hydrocarbons ◽  
Ceramic Machining ◽  
Machining Of Ceramics ◽  
Machining Fluids

Ceramics are hard and brittle. Machining such materials is time-consuming, difficult, and expensive. Current machining technology requires stiff machine, high hardness tools, and small material removal rates to minimize surface damage. This study demonstrates the feasibility of a novel ceramic machining concept that utilizes chemical reactions at the tool-workpiece interface to reduce the stress and minimize the surface damage. A series of cutting tests using a diamond wheel on silicon nitride with different chemical compounds has been performed. The results demonstrate that by using different chemistries, the material removal rate and the surface finish of the machined ceramic can be significantly altered. Some halogenated hydrocarbons show a significant improvement over some commercial machining fluids currently in use.

Characterizations of Removal Rate and Temperature in the Inductively Coupled Plasma Etching of Silicon Carbide

2016 ◽  
Vol 679 ◽  
pp. 85-90
Author(s):  
Na Li ◽  
Peng Zhang ◽  
Qiang Xin ◽  
Jiang Jin ◽  
Bo Wang
Keyword(s):  
Silicon Carbide ◽  
Inductively Coupled Plasma ◽  
Processing Time ◽  
Removal Rate ◽  
Influence Factors ◽  
High Hardness ◽  
Input Power ◽  
Processing Temperature ◽  
Space Applications ◽  
Inductively Coupled

Silicon carbide (SiC) is widely used in terrestrial and space applications because of its good mechanical, thermal and optical properties. Nevertheless, traditional grinding and polishing technologies cannot meet the machining requirements due to the high hardness and brittleness. In this paper, Inductively Coupled Plasma (ICP) is utilized to process the SiC optics. The effects of different processing recipes on the removal rate and temperature are investigated. The results show that the removal rate almost keeps stable with processing time and changes with the flow rate of plasma gas, reaction gas, the ratio of CF4/O2 and the power. The input power and processing time are the two main influence factors on the processing temperature.

Experimental Investigation on Wafer Polishing of Oxide and Copper Layers

2002 ◽  
Author(s):  
Jhy-Cherng Tsai
Keyword(s):  
Process Parameters ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Back Pressure ◽  
Copper Layer ◽  
Wafer Polishing ◽  
Critical Technology ◽  
And Performance ◽  
Polishing Pressure

Polishing, in particular chemical-mechanical polishing (CMP), is a critical technology for the planarization of wafers. This paper investigates, via experiments, and compares the performance of CMP process with different process parameters for wafers with silicon-dioxide (SiO2) layer and for wafers with copper (Cu) layer. Polishing pressure (P), speed (V), and back pressure (BP) are used as process parameters in this study. Different pads and slurries are also experimented for copper layer as its properties are different from that of conventional oxide layer. Material removal rate (RR) and non-uniformity (NU) are used as indices to measure the performance. Experimental data on oxide layers show RR increases as P and V increase but NU gets worse at the same time. This condition can be improved, for both oxide and copper layers, with suitable BP. Experiments on copper CMP using slurry with abrasives show that RR increases with higher P and V. While NU gets worse with higher P, it can be reduced as V increases using a soft pad. Better NU can be obtained using soft pad though RR is lower in this case. For abrasive-free polishing of copper layer, RR, though relatively lower compared to CMP with regular slurry, is unstable using hard pad despite that NU becomes better at higher P. NU of polished wafer is best at certain pressure but becomes worse at low pressure for hard pad and at high P for soft pad. It is also observed that NU of AFP can be improved with BP and softer pad. Soft pad gives better polishing quality and performance though RR is lower than that using slurry with abrasives.

scholarly journals Preparation of N-Doped Carbon Nanosheets from Sewage Sludge for Adsorption Studies of Cr(VI) from Aqueous Solution

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 265 ◽  
Author(s):  
Yi Wang ◽  
Weinan Zhao ◽  
Wanlan Zheng ◽  
Shuang Chen ◽  
Jinsheng Zhao
Keyword(s):  
Sewage Sludge ◽  
Porous Carbon ◽  
Removal Rate ◽  
Low Cost ◽  
Waste Water Treatment ◽  
Grand Challenge ◽  
Koh Activation ◽  
Thermal Regeneration ◽  
Carbon Nanosheets ◽  
Pore Size Distributions

Porous activated carbon with specific morphology and structure are of particular importance for waste water treatment, especially for the adsorption of toxic hexavalent chromium Cr(VI). However, the scalable and cheap production of such absorbents still suffer a grand challenge. Herein, a new type of N-doped nanosheet was innovatively prepared from easily available and low-cost sewage sludge via a facile and recyclable KOH activation method. The N-doped porous carbon nanosheets (N-SAC) produced by introduction of KOH and dicyandiamide, which performed favourable features for metal ions adsorption (93.2% for Cr(VI)) due to its high specific surface area, tuneable pore size distributions and good hydrophilicity. Additionally, the capacity also remained high after two cycles of adsorption by thermal regeneration, with 90.8% removal rate. The DFT calculation also approved that the doping of N could optimize the Mulliken charges distribution and improve the HOMO energy and improve the adsorption ability of N-SAC. This original proposal may inspire new possibility of creating porous carbon absorbents in a recyclable method.

Studies on Process Parameter Optimization of Inconel 718 Turning Operation using Taguchi based Grey Relational Analysis

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
B.S. Raju ◽  
U. Chandrasekhar ◽  
L.H. Manjunath
Keyword(s):  
Inconel 718 ◽  
Metal Removal ◽  
Removal Rate ◽  
Impact Resistance ◽  
High Hardness ◽  
Cutting Parameters ◽  
Process Parameter ◽  
Depth Of Cut ◽  
Grey Relational Grade ◽  
Grey Relational

Accompanying the development of mechanical industry, the demand for alloy materials having high hardness, toughness and impact resistance are increasing. Nevertheless, such materials are difficult to be machined by traditional machining method. Hence CNC machines are used to machine such materials, which are capable of producing fine, precise, corrosion and wear resistance surfaces. The problem of arriving at optimal levels of operating parameters has attracted the attention of the researchers and practicing engineers, for a very long time. Thus, this paper demonstrates the optimization of the process parameter of machining Inconel 718 super alloy material via., the Taguchi methodbased grey analysis. The modified algorithm adopted here was successfully used for both detraining the optimum settings of machine parameters and for combining multiple quality characteristics into one integrated numerical value called grey relational grade. An attempt has been made to identify the influence of various cutting parameters i.e., speed, feed rate and depth of cut on physical part characteristics i.e., metal removal rate and surface roughness. The predictions of optimal process parameter with respect to the response are the end results of the paper.

Challenges and State-of-the-Art of Oxides on SiC

2000 ◽  
Vol 640 ◽  
Author(s):  
Lori Lipkin ◽  
Mrinal Das ◽  
John Palmour
Keyword(s):  
Single Crystal ◽  
Band Gap ◽  
High Voltage ◽  
State Of The Art ◽  
Wide Band ◽  
High Current ◽  
Power Devices ◽  
Wide Band Gap ◽  
Single Crystal Sic ◽  
Lower Temperature

ABSTRACTSingle crystal SiC is a wide band-gap semiconductor with material characteristics that make it quite suitable for high voltage and high current applications. However, these devices are currently limited by their passivation. Significant improvements have been made with oxides on SiC. The most notable oxide processes are the re-oxidation anneal, a stacked ONO dielectric, and nitridation using an NO or N2O anneal. Additional improvements in lateral MOSFET mobility have been achieved using a surface channel implant, and lower temperature implant activation anneals. However, the passivation remains a significant limitation for SiC power devices.

Study on Effect of Composite Particles in Polishing Process and Its Mechanism

2007 ◽  
Vol 24-25 ◽  
pp. 155-159 ◽  
Author(s):  
Xue Feng Xu ◽  
B.X. Ma ◽  
Feng Chen ◽  
Wei Peng
Keyword(s):  
Removal Rate ◽  
High Surface ◽  
Composite Particles ◽  
Particle Interactions ◽  
Polymer Particles ◽  
Layer Model ◽  
Polishing Process ◽  
High Surface Quality ◽  
Wafer Polishing ◽  
Double Layer Model

In this paper, mixed slurries containing silica abrasives and polystyrene (PS) polymer particles in deionized water at pH 10.5 have been evaluated for silicon wafer polishing. By applying the theory of electric double layer model, the effect of the particle interactions in mixed slurry is investigated. Zeta potential measurements and TEM images have been used to show the formation of composite particles. The polishing mechanism with composite particles slurries is discussed. Polishing experiments with the mixed slurries formed by coating smaller (~30nm) abrasives onto softer and larger (~2000nm) polymer particles have shown the superior characteristic with higher removal rate and high surface quality.

Effect of Rare Earths on Iron-Carbon Micro Electrolysis in Dyeing Wastewater Treatment

2014 ◽  
Vol 1010-1012 ◽  
pp. 190-194
Author(s):  
Xiao Gang Chen ◽  
Ju Chi Kuang ◽  
Min Hua Chen
Keyword(s):  
Wastewater Treatment ◽  
Removal Rate ◽  
Waste Water Treatment ◽  
Sewage Treatment ◽  
Main Role ◽  
Dyeing Wastewater ◽  
Related Factors ◽  
Orthogonal Experiments ◽  
Cerium Ion ◽  
Cod Removal Rate

In the paper we first discussed the principle of wastewater treatment by iron-carbon micro electrolysis. And the experimental methods were stated clear soon afterwards. Then we designed the micro electrolysis orthogonal experiments. Discussion of influences of related factors on waste water treatment followed. The main factors are cerium ion additive quantity, ratio of La3+/Ce4+ and pH in wastewater. The experimental results show that 1) The sequence of factors influence on wastewater micro-electrolysis treatment is Ce4+ > pH > La3+ > iron/carbon ratio; 2) The lanthanum and cerium ions have a synergistic effect in the wastewater treatment, and cerium ion plays a main role; 3) When pH is 6, COD removal rate arrives at maximum 89%, however when the pH is in the case of too high or too low, the effect of sewage treatment is not good.

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