Single-crystal SiC is a third-generation semiconductor power device material. To meet industry specifications for manufacturing power devices using this material, precision polishing must be used to achieve an ultrasmooth surface that is free of scratches and subsurface damage (SSD). Polishing alone cannot achieve such an atomic surface finish.
Lee [25] conducted experiments using an alkaline MAS to polish 6H-SiC and found a higher MRR than with traditional colloidal silica slurry, as well as evidence that performance could be enhanced further with an oxidant additive.
Chemical Mechanical Polishing (CMP)
CMP uses chemical and physical abrasive action on a wafer surface to combine chemical and physical abrasion for smoothing and planarization, unlike pure physical abrasion which may damage delicate wafer structures and leave behind irregularities that cannot be corrected. Chemical etching softens materials for mechanical abrasion to remove them more effectively than physical abrasion would alone. CMP can address materials ranging from silicon dioxide to copper with ease.
STI (Shallow Trench Isolation) is an efficient technique used for electrically isolating active regions on microprocessor chips. This technique uses etched trenches filled with undoped CVD polysilicon or silicon dioxide as electrical isolation between these regions and the substrate, and has become the go-to method in silicon circuit design due to its superior performance, cost effectiveness and environmental friendliness.
Engineers seeking to avoid dishing, a form of planarization defect which occurs when different materials are removed at different rates, must understand how a wafer interacts with its polishing slurry and the relative removal rates for all layers on a chip.
QSense Quantum Cathode Microscopy-D (QCM-D) allows engineers to observe in real time how various slurry additives, abrasive particles, and mixtures interact with wafers during CMP processes. The comprehensive information gained through QCM-D analysis allows engineers to optimize slurry composition while improving CMP processes.
Physical Abrasive Polishing (PAP)
Physical abrasive polishing is an economical and versatile way to create smooth surfaces, and is great for use on different materials such as metal, ceramic and even wood. It can also be used with both coarse grits for roughing/shaping purposes and finer ones for polishing. Protective eyewear and gloves should also be worn to avoid injury during this process.
As part of this polishing process, it is imperative that the surface of the wafer be deformation free and scratch-free in order to accurately represent microstructure for subsequent testing, analysis or interpretation. A deformation free surface also reduces extraneous structures such as pitting, dragging out inclusions or comet tailing which might otherwise arise during analysis, testing or interpretation.
For optimal results when polishing materials of various hardnesses, the hardness of abrasive particles must match that of their target material. Furthermore, to get optimal results with each type of abrasive and reduce risks such as damage or contamination it may be wise to mix different abrasives together – this allows them to play to their strengths while at the same time taking advantage of any advantages offered by each.
Selection of an appropriate abrasive is key to providing quality polishing services. Working with a reliable supplier ensures they supply specific materials required by each task and offer technical support and certifications as proof of their quality, while offering advice about which abrasives would best fit specific applications.
Electrochemical Mechanical Polishing (ECMP)
Electrochemical polishing refers to various processes used to refine metal surfaces by controlled chemical reactions. Electrochemical polishing can often serve as an effective replacement for complex mechanical polishing or passivation procedures as it requires less physical abrading while still producing comparable results with lower roughness values and increased surface quality.
ECMP is an environmentally-friendly alternative to traditional polishing methods, which rely on harsh chemicals like perchloric acid that are hard to dispose of and pollute the environment. Instead, ECMP utilizes deep eutectic solvents (DES) such as choline chloride and ethylene glycol that have minimal environmental impacts and toxicity levels.
ECMP is a process used to remove impurities, debris and oils embedded within the microscopic surface texture of stainless steel components and leave them with a high-gloss, bright shiny finish that’s more corrosion resistant than chemical polishing’s passivation layer. It can be applied to many materials; making ECMP ideal for applications including stainless steel tanks, piping & fittings, nickel alloys such as Hastelloy as well as large parts & surfaces that must remain corrosion resistant.
ECMP not only removes imperfections from stainless steel surfaces but also increases corrosion resistance by creating an enhanced oxide film with a higher ratio of Chromium oxide to Iron oxide and thicker than standard chrome plating – something particularly relevant to industries using 316L grade stainless steel, such as pharmaceutical and biopharmaceutical manufacturing facilities.
Ultrasonic Vibration-Assisted Polishing
Ultrasonic-vibration assisted polishing can be used to improve the surface quality of various workpiece materials. The ultrasonic-vibration assisted polishing process combines benefits from both physical abrasion and chemical mechanical polishing; its results surpassing either method alone. Furthermore, this type of polishing is automated on machining centers for efficiency and repeatability as well as used for difficult-to-polish materials like STAVAX mold steel.
[2] conducted a predictive modeling and experimental research on UVAP polishing slurry consumption model. Amplitude, working frequency, spindle speed, grain size of abrasives used and concentration were the most influential factors that affected UVAP local surface profiles during polishing process. To identify optimal polishing parameters using Taguchi method.
Silicon carbide (SiC) and binderless tungsten carbide (WC) are highly desirable mold materials for glass molding of microstructured optical elements due to their superior physical and mechanical properties, but produce difficult-to-grind surfaces with high quality gratings or pyramids via conventional grinding processes. In this study, however, UVAP process was applied on these two materials with great success, improving their surface qualities significantly – even producing improved pyramid surfaces! Specifically for SiC and WC. In both cases the application of UVAP process enhanced the surface quality improvement for these two mold materials significantly improving both their surface qualities for glass molding microstructured optical elements production through glass mold making processes.
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