Different Types of SiC Polishing

Silicon carbide SiC is an inert material and presents many challenges when it comes to polishing it precisely.

Chemical mechanical polishing (CMP) is a popular means to achieve subsurface flatness and damage-free surfaces on an atomic scale, but the material removal rate (MRR) remains relatively low due to mechanical wear-and-oxidation reactions occurring during CMP processing.

Chemical Mechanical Polishing (CMP)

Chemical mechanical polishing (CMP) is the dominant strategy for planarizing material layers in integrated circuit manufacturing. CMP utilizes nano-sized abrasive particles suspended in either acidic or basic solutions as part of its slurries to mechanically remove material from wafer surfaces, eventually softening material for removal by mechanical abrasion; hence its other name “mechanochemical polishing (MCP).”

CMP slurries may contain an array of ingredients, varying in composition, surface chemistry, temperature, pH levels, additives and concentration levels. Particle size distribution plays an essential role in determining process metrics like removal rate and wafer defect rates; particle characterization via quantitative confocal microscopy-D can give researchers an accurate and comprehensive view of these interactions between particles, substrate and slurry.

This article presents a method for measuring particle size distribution in CMP slurry using QCM-D, an essential step towards improving CMP slurry performance and reducing overall consumption for any given process. Furthermore, environmental sustainability demands minimization of abrasive consumption through shorter polishing times at optimal flow rates; this allows a significant decrease in overall consumption without impacting wafer defect rates or MRR requirements.

Electrochemical Mechanical Polishing (ECMP)

ECMP is an emerging low down-pressure planarization technology for copper. This process combines chemically controlled surface degradation and mechanical polishing for uniform wafer level uniformity without using abrasive particles, offering an alternative to CMP for low-k copper interconnects that offers better within-wafer uniformity while decreasing particle coagulation, slurry handling and waste disposal issues.

ECMP uses an electrical potential applied to the polishing pad to increase chemical reactions, increasing material removal rate (MRR) and planarizing wafers more effectively than CMP. Furthermore, it allows lower polishing pressures which in turn lower energy costs and environmental concerns associated with this processing method.

This invention provides polishing pads and other shaped articles used in electrochemical mechanical polishing (ECMP) with stable physical and electrical properties as well as increased durability and service life. More specifically, its polishing pads comprise layers made up of an electrically conductive compound made up of an admixture of polymeric component and filler component to form an electrically-conductive compound.

This paper employs tribology and electrochemistry techniques to explore the corrosion/erosion behaviors of an abrasive-free conductive polishing slurry during Ta ECMP, and its subsequent impact on surface morphology and distribution of Cu 2p orbital elements. Results demonstrate that although effective at removing Ta from substrate surfaces, such slurry cannot completely prevent pits and cracks forming in MPE pads as seen via SEM images.

Mechanical Polishing (MP)

By employing this process, the surface of a wafer is polished using mechanical abrasives and chemicals for planarization purposes, producing very smooth surfaces that meet high levels of precision planarization requirements – often used for critical processes like shallow trench isolation (STI) or metal interconnects.

CMP is an intricate process requiring both chemical and mechanical methods in tandem to ensure optimal planarization of wafers. While chemical components soften up materials that must be removed through chemical means, mechanical abrasives remove it through physical friction. CMP has long been employed within the semiconductor industry to planarize silicon and other semiconductor materials allowing for higher levels of flatness and smoothness for finished wafers.

SiC requires careful balance between chemical and mechanical removal processes; too weak mechanical removal prevents timely removal of an oxidized layer on its surface, thus decreasing MRR of CMP; while excessive mechanical removal results in scratches appearing on wafer surfaces and thus reduces MRR.

Researchers have created various efficiency-boosting approaches for CMP that have proven successful, such as Fenton-like reactions, core/shell abrasive particles, FAP and PCMP. Each of these techniques aims to enhance particle performance in different CMP processes – and their effectiveness has been confirmed in laboratory trials.

Electrochemical Electrochemical Polishing (ECEP)

Electropolishing is an electrochemical process that removes surface imperfections on metal workpieces to give them a flawless, polished appearance. Electropolishing is commonly employed by industries such as medical device and aerospace to finish metal components and improve smoothness while increasing corrosion resistance.

Polishing processes utilize an electrolytic solution as an electrolyte, breaking apart metal ions into positive and negative charges that travel towards electrodes. The workpiece is connected to the positive terminal of the power supply as its anode; while its counter electrode connects to its negative terminal as its cathode. As electric current runs through it, electrolytic solution becomes split up into its constituent ions creating an active area on the workpiece which stimulates chemical reactions between anode and cathode to remove unwanted surface materials from component surfaces.

Electrolytic passivation films produce an electrolytic passivation film with superior corrosion protection and provide a glossy mirrored appearance, ideal for medical devices or parts subject to strict quality standards.

ECEP electrolytes will vary depending on the type of metal being polished and desired surface finish. Most commonly, an acid mix containing phosphoric and sulfuric acids must be handled carefully to avoid respiratory issues while adhering to safety regulations; alternatively, some companies opt for safer electrolyte solutions like ethylene glycol or choline chloride.