{"id":2580,"date":"2026-08-06T13:43:59","date_gmt":"2026-08-06T05:43:59","guid":{"rendered":"https:\/\/jeez-semicon.com\/?p=2580"},"modified":"2026-08-06T13:43:59","modified_gmt":"2026-08-06T05:43:59","slug":"what-is-colloidal-silica-particles-chemistry-and-how-it-differs-from-other-abrasives","status":"publish","type":"post","link":"https:\/\/jeez-semicon.com\/fr\/blog\/what-is-colloidal-silica-particles-chemistry-and-how-it-differs-from-other-abrasives\/","title":{"rendered":"What Is Colloidal Silica? Particles, Chemistry, and How It Differs from Other Abrasives"},"content":{"rendered":"<style>\n@import url('https:\/\/fonts.googleapis.com\/css2?family=Sora:wght@400;500;600;700&family=IBM+Plex+Sans:ital,wght@0,400;0,500;0,600;1,400&display=swap');\n.jcs-wrap *{box-sizing:border-box}\n.jcs-wrap{font-family:'IBM Plex Sans',system-ui,sans-serif;font-size:16px;line-height:1.8;color:#1a1a2e;max-width:920px;margin:0 auto}\n.jcs-wrap h1{font-family:'Sora',sans-serif;font-size:clamp(1.7rem,4vw,2.2rem);font-weight:700;line-height:1.22;color:#fff;margin:0 0 1rem}\n.jcs-wrap h2{font-family:'Sora',sans-serif;font-size:clamp(1.15rem,2.5vw,1.45rem);font-weight:600;color:#0f1f5c;margin:2.75rem 0 .9rem;padding-bottom:.5rem;border-bottom:2px solid #dbeafe;scroll-margin-top:80px}\n.jcs-wrap h3{font-family:'Sora',sans-serif;font-size:1.07rem;font-weight:600;color:#1e3a8a;margin:1.75rem 0 .65rem}\n.jcs-wrap p{margin:0 0 1.15rem}\n.jcs-wrap ul,.jcs-wrap ol{margin:0 0 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0;display:flex;gap:.65rem;align-items:flex-start;font-size:.88rem;line-height:1.6}\n.jcs-link-box-icon{color:#2563eb;font-weight:700;font-size:1rem;flex-shrink:0;margin-top:.05rem}\n.jcs-link-box a{font-weight:600}\n.jcs-faq-item{border:1px solid #e2e8f0;border-radius:10px;margin-bottom:.9rem;overflow:hidden}\n.jcs-faq-q{background:#f8faff;padding:.88rem 1.2rem;font-family:'Sora',sans-serif;font-weight:600;font-size:.93rem;color:#0f1f5c;border-bottom:1px solid #e2e8f0;line-height:1.45}\n.jcs-faq-a{padding:.95rem 1.2rem;font-size:.9rem;line-height:1.75}\n.jcs-faq-a p{margin:0 0 .65rem;font-size:.9rem}.jcs-faq-a p:last-child{margin:0}\n.jcs-cta{background:linear-gradient(135deg,#0b1840 0%,#0f2868 100%);border-radius:14px;padding:2.5rem 2.25rem;text-align:center;margin:2.75rem 0 1.4rem}\n.jcs-cta h2{color:#fff;font-size:1.35rem;border:none;padding:0;margin:0 0 .65rem}\n.jcs-cta p{color:rgba(255,255,255,.82);margin-bottom:1.5rem;font-size:.97rem}\n.jcs-cta-btn{display:inline-block;background:#fff;color:#0b1840;font-family:'Sora',sans-serif;font-weight:700;font-size:.92rem;padding:.85rem 2.1rem;border-radius:6px;text-decoration:none}\n.jcs-cta-btn:hover{opacity:.9;color:#0b1840;text-decoration:none}\n.jcs-hr{border:none;border-top:1px solid #e2e8f0;margin:2.25rem 0}\n.jcs-footnote{font-size:.82rem;color:#64748b;line-height:1.65;margin-top:1.75rem}\n.jcs-footnote strong{color:#475569}\n@media(max-width:600px){.jcs-hero{padding:1.75rem 1.4rem}.jcs-cta{padding:1.75rem 1.4rem}.jcs-wrap h2{font-size:1.15rem}}\n<\/style>\n\n<article class=\"jcs-wrap\">\n<div class=\"jcs-hero\">\n  <span class=\"jcs-hero-tag\">CMP Fundamentals \u00b7 Cluster C-01<\/span>\n  <p>A ground-up technical explanation of colloidal silica\u2014what defines it as a material, how its SiO\u2082 nanoparticles are structured, the surface chemistry that drives CMP performance, and why it outperforms fumed and precipitated silica for precision polishing applications.<\/p>\n  <div class=\"jcs-hero-meta\">\n    <span class=\"jcs-meta-pill\">\ud83d\udcc5 <b>August 2026<\/b><\/span>\n    <span class=\"jcs-meta-pill\">\u23f1 <b>~12 min read<\/b><\/span>\n    <span class=\"jcs-meta-pill\">\u270d <b>JEEZ Technical Team<\/b><\/span>\n  <\/div>\n<\/div>\n<span class=\"jcs-updated\">Published by Jizhi Electronic Technology Co., Ltd. (JEEZ) \u00b7 August 2026<\/span>\n\n<nav class=\"jcs-toc\" aria-label=\"Table des mati\u00e8res\">\n  <p class=\"jcs-toc-label\">Table des mati\u00e8res<\/p>\n  <ol>\n    <li><a href=\"#definition\">Colloidal Silica: Core Definition<\/a><\/li>\n    <li><a href=\"#nanoparticle-structure\">SiO\u2082 Nanoparticle Size, Shape, and Structure<\/a><\/li>\n    <li><a href=\"#surface-chemistry\">Surface Chemistry: Silanol Groups and Zeta Potential<\/a><\/li>\n    <li><a href=\"#three-forms\">Three Forms of Amorphous Silica Compared<\/a><\/li>\n    <li><a href=\"#morphology-matters\">Why Particle Morphology Determines CMP Performance<\/a><\/li>\n    <li><a href=\"#key-specs\">Key Specifications for CMP-Grade Colloidal Silica<\/a><\/li>\n    <li><a href=\"#faq\">Questions fr\u00e9quemment pos\u00e9es<\/a><\/li>\n  <\/ol>\n<\/nav>\n\n<p>The term &#8220;colloidal silica&#8221; appears on slurry data sheets, CMP process recipes, and supplier catalogs throughout the semiconductor and precision polishing industries\u2014but what exactly is it, and what makes it different from other silica-based polishing materials? Understanding the physical and chemical identity of colloidal silica is not a purely academic exercise: the material&#8217;s unique particle morphology, surface chemistry, and colloidal behavior directly determine its performance in chemical mechanical planarization (CMP) applications, and a clear grasp of these fundamentals helps engineers make better slurry selection and process optimization decisions.<\/p>\n\n<p>This article provides a complete technical explanation of what colloidal silica is, how its nanoparticles are structured and chemically characterized, how it compares to fumed and precipitated silica, and what specification parameters define a CMP-grade product.<\/p>\n\n<section id=\"definition\">\n  <h2>1. Colloidal Silica: Core Definition<\/h2>\n  <p>Colloidal silica is an aqueous dispersion of amorphous, non-porous silicon dioxide (SiO\u2082) nanoparticles that exist in a stable, uniformly dispersed state due to electrostatic repulsion between particles. The key term in this definition is <strong>colloidal<\/strong>: in colloid science, a colloidal dispersion is a two-phase system in which one phase (the dispersed phase\u2014here, solid SiO\u2082 particles) is finely subdivided and distributed throughout a second continuous phase (the dispersion medium\u2014here, water), with particle sizes typically in the range of 1 nm to 1 \u00b5m.<\/p>\n  <p>Within this size range, particles are too small to settle under gravity on any practical timescale (unlike coarser suspensions, which sediment), yet large enough to interact mechanically with a substrate surface. This size regime is also where the ratio of surface area to volume is extremely high, making surface chemistry\u2014rather than bulk material properties\u2014the dominant factor in particle behavior. A 50 nm SiO\u2082 particle has a surface-to-volume ratio approximately 3,600 times higher than a 180 \u00b5m conventional abrasive grain.<\/p>\n  <p>The SiO\u2082 in colloidal silica is amorphous\u2014meaning its silicon and oxygen atoms are arranged in a random, glass-like network rather than a long-range crystalline structure. This distinguishes it from crystalline silica phases such as quartz (\u03b1-SiO\u2082) and cristobalite, which have defined crystal structures and are classified as hazardous by inhalation (IARC Group 1). Amorphous colloidal silica does not carry this classification and has a substantially more benign safety profile, an important practical consideration for fab environments.<\/p>\n  <div class=\"jcs-note\">\n    <p><strong>Colloidal silica vs silica sol:<\/strong> The two terms are used interchangeably in most industrial contexts. &#8220;Silica sol&#8221; is the older chemical engineering term for a stable colloidal dispersion of amorphous SiO\u2082 in water, while &#8220;colloidal silica&#8221; is the preferred term in semiconductor and CMP contexts. Both describe the same material class.<\/p>\n  <\/div>\n<\/section>\n\n<section id=\"nanoparticle-structure\">\n  <h2>2. SiO\u2082 Nanoparticle Size, Shape, and Structure<\/h2>\n  <p>The performance of a colloidal silica slurry in CMP begins with the geometry of the individual SiO\u2082 particle. Several structural parameters define a CMP-grade colloidal silica particle population:<\/p>\n  <h3>Primary Particle Size<\/h3>\n  <p>For CMP applications, colloidal silica primary particles range from approximately 20 nm to 150 nm in diameter. This range is deliberately engineered during synthesis\u2014smaller particles (20\u201340 nm) are used for ultra-low-defect applications such as silicon wafer final polishing, while larger particles (80\u2013150 nm) are used in higher-MRR oxide CMP steps where throughput is the primary objective. The primary particle size distribution is characterized by statistical parameters: D50 (median diameter), D90 (90th percentile), and the large particle count (LPC) above threshold sizes such as 0.5 \u00b5m and 1 \u00b5m.<\/p>\n  <h3>Spherical Morphology<\/h3>\n  <p>Colloidal silica particles grown by controlled wet-chemical synthesis (both the St\u00f6ber alkoxide route and the ion-exchange seeded-growth route) produce discrete, nearly spherical primary particles. Sphericity is not merely an aesthetic property\u2014it determines the contact mechanics between the abrasive and the polished surface. A spherical particle distributes contact stress over a well-defined Hertzian contact area, producing predictable, uniform micro-scratching forces. An irregular or angular particle creates stress concentrations at its sharp edges, dramatically increasing peak contact pressure and the probability of deep scratch formation.<\/p>\n  <h3>Amorphous Internal Structure<\/h3>\n  <p>Internally, each colloidal silica particle consists of a continuous, cross-linked SiO\u2082 network with no crystalline long-range order. The material has a density of approximately 2.0\u20132.2 g\/cm\u00b3 (compared to 2.65 g\/cm\u00b3 for quartz and 2.20 g\/cm\u00b3 for vitreous silica), a Mohs hardness of approximately 6\u20137 (vs. 7 for quartz), and a refractive index of approximately 1.44\u20131.46. The amorphous network does not have cleavage planes, which means particles do not fracture to produce sharp new edges during polishing\u2014another key advantage over crystalline abrasives.<\/p>\n<\/section>\n\n<section id=\"surface-chemistry\">\n  <h2>3. Surface Chemistry: Silanol Groups and Zeta Potential<\/h2>\n  <p>The surface of every colloidal silica particle is covered with silanol groups\u2014Si-OH functional groups that form the chemical interface between the SiO\u2082 particle and its aqueous environment. This surface chemistry is the foundation of both colloidal stability and the tribochemical CMP material removal mechanism.<\/p>\n  <h3>Silanol Group Density and Types<\/h3>\n  <p>The silanol surface density on colloidal silica is approximately 4\u20135 OH groups per nm\u00b2. Three types of silanol groups exist at the SiO\u2082 surface: isolated silanols (single Si-OH, the most reactive), geminal silanols (two OH groups on the same Si atom, Si(OH)\u2082), and vicinal or hydrogen-bonded silanols (adjacent Si-OH groups connected by hydrogen bonds). The relative population of these types depends on synthesis conditions and thermal history and influences both the reactivity of the particle surface and its response to chemical additives.<\/p>\n  <h3>pH-Dependent Ionization and Surface Charge<\/h3>\n  <p>At pH values above approximately 4, silanol groups begin to dissociate (ionize) according to: Si-OH \u2192 Si-O\u207b + H\u207a. This ionization increases with pH, giving the particle surface an increasingly negative charge. The degree of ionization\u2014and thus the surface charge density\u2014is described by the Henderson-Hasselbalch relationship for surface acid-base equilibria, with an effective pKa for the silanol-to-siloxide transition of approximately 6\u20137 in aqueous systems.<\/p>\n  <h3>Zeta Potential and Colloidal Stability<\/h3>\n  <p>The negative surface charge at alkaline pH creates an electrical double layer around each particle\u2014a layer of counterions (positively charged species from the solution) attracted to the negatively charged surface. The potential at the boundary between the immobile Stern layer and the diffuse outer layer is the zeta potential (\u03b6), which quantifies the electrostatic repulsion between approaching particles. For colloidal silica at typical CMP pH values (pH 9\u201312), \u03b6 is typically \u221235 to \u221265 mV\u2014well beyond the \u00b130 mV stability threshold, giving the dispersion excellent long-term stability. Near the isoelectric point of SiO\u2082 (pH ~2\u20133), \u03b6 approaches zero and the dispersion is unstable, leading to rapid particle aggregation.<\/p>\n  <div class=\"jcs-link-box\">\n    <span class=\"jcs-link-box-icon\">\u2192<\/span>\n    <span>For a full treatment of how pH, zeta potential, and storage conditions determine slurry stability and shelf life, see: <a href=\"https:\/\/jeez-semicon.com\/fr\/blog\/Colloidal-Silica-Slurry-Stability-pH-Control-Shelf-Life-and-Dilution-Best-Practices\/\" target=\"_blank\" rel=\"noopener noreferrer\">Colloidal Silica Slurry Stability: pH Control, Shelf Life, and Dilution Best Practices<\/a><\/span>\n  <\/div>\n<\/section>\n\n<section id=\"three-forms\">\n  <h2>4. Three Forms of Amorphous Silica: Colloidal vs Fumed vs Precipitated<\/h2>\n  <p>Amorphous SiO\u2082 is commercially available in three distinct forms, produced by fundamentally different manufacturing routes that result in very different particle morphologies and application properties. Understanding these differences is critical for CMP abrasive selection.<\/p>\n  <div class=\"jcs-table-wrap\">\n    <table>\n      <thead><tr><th>Propri\u00e9t\u00e9<\/th><th>Colloidal Silica<\/th><th>Fumed Silica<\/th><th>Precipitated Silica<\/th><\/tr><\/thead>\n      <tbody>\n        <tr><td>Synthesis route<\/td><td>Wet-chemical (St\u00f6ber or ion exchange)<\/td><td>Flame hydrolysis of SiCl\u2084<\/td><td>Acid precipitation from water glass<\/td><\/tr>\n        <tr><td>Particle form<\/td><td>Discrete spheres, non-porous<\/td><td>Branched aggregates of fused primary spheres<\/td><td>Porous agglomerates, irregular<\/td><\/tr>\n        <tr><td>Primary particle D50<\/td><td>20\u2013150 nm<\/td><td>5\u201330 nm (primary), 100\u2013400 nm aggregate<\/td><td>100\u2013500 nm primary<\/td><\/tr>\n        <tr><td>Surface area (BET)<\/td><td>20\u2013150 m\u00b2\/g<\/td><td>100\u2013380 m\u00b2\/g<\/td><td>30\u2013800 m\u00b2\/g<\/td><\/tr>\n        <tr><td>Dispersion form<\/td><td>Stable aqueous suspension<\/td><td>Dry powder; dispersed as aggregate slurry<\/td><td>Dry powder; wet dispersions are unstable<\/td><\/tr>\n        <tr><td>PSD control<\/td><td class=\"td-hi\">Excellent (\u00b15% D50)<\/td><td class=\"td-mid\">Moderate (aggregate size varies)<\/td><td class=\"td-lo\">Pauvre<\/td><\/tr>\n        <tr><td>CMP defectivity<\/td><td class=\"td-hi\">Faible<\/td><td class=\"td-mid\">Moderate\u2013High<\/td><td class=\"td-lo\">High (not used in semiconductor CMP)<\/td><\/tr>\n        <tr><td>Primary CMP use<\/td><td>Final polish, oxide CMP, barrier CMP<\/td><td>Commodity oxide CMP<\/td><td>Not typically used in semiconductor CMP<\/td><\/tr>\n      <\/tbody>\n    <\/table>\n  <\/div>\n  <p>The key structural difference between colloidal and fumed silica is that colloidal silica consists of <strong>discrete, non-aggregated primary particles<\/strong>, while fumed silica consists of <strong>aggregates of fused primary particles<\/strong>. Fumed silica&#8217;s primary particles (5\u201330 nm) are irreversibly fused during synthesis into chain-like three-dimensional aggregates that cannot be broken down into individual primary particles by any practical dispersing method. These aggregates have irregular shapes with sharp edges and are the fundamental abrasive unit in fumed silica slurry\u2014not the individual primary particles.<\/p>\n  <div class=\"jcs-link-box\">\n    <span class=\"jcs-link-box-icon\">\u2192<\/span>\n    <span>For a dedicated head-to-head comparison of colloidal and fumed silica slurry performance in CMP, including MRR, defectivity, pH stability, and cost analysis: <a href=\"https:\/\/jeez-semicon.com\/fr\/blog\/Colloidal-Silica-vs-Fumed-Silica-Slurry-Which-Abrasive-Is-Right-for-Your-CMP-Process\/\" target=\"_blank\" rel=\"noopener noreferrer\">Colloidal Silica vs Fumed Silica Slurry: Which Abrasive Is Right for Your CMP Process?<\/a><\/span>\n  <\/div>\n<\/section>\n\n<section id=\"morphology-matters\">\n  <h2>5. Why Particle Morphology Determines CMP Performance<\/h2>\n  <p>The difference between a spherical, discrete colloidal silica particle and an angular fumed silica aggregate is not merely aesthetic\u2014it has direct, quantifiable consequences for CMP process performance, especially defectivity.<\/p>\n  <h3>Contact Mechanics and Stress Distribution<\/h3>\n  <p>When an abrasive particle contacts a polished surface under the normal force applied by the CMP pad, the resulting contact stress follows the Hertz contact model for spherical indenters. For a spherical particle of radius R in contact with a flat surface under load F, the maximum contact pressure P\u2080 = (3F\/2\u03c0a\u00b2) where a is the contact radius determined by R, F, and the elastic moduli of the particle and substrate. A smooth spherical particle distributes the load over this well-defined contact area, producing manageable, uniform contact stresses.<\/p>\n  <p>For an irregular fumed silica aggregate, the same applied force is concentrated at its sharpest asperity\u2014a point contact that can be modeled as an effectively much smaller radius particle. This geometric stress concentration multiplies the local contact pressure by a factor potentially 10\u2013100\u00d7 compared to an equivalent-mass spherical particle, dramatically increasing the probability of plastic deformation (scratching) of the polished surface rather than the controlled elastic-regime tribochemical removal that characterizes ideal colloidal silica CMP.<\/p>\n  <h3>Implications for Final Polish and Advanced Oxide CMP<\/h3>\n  <p>For silicon wafer final polish\u2014where the surface roughness specification is below 0.1 nm RMS and the LPD count specification is below 50 particles at >0.09 \u00b5m detection\u2014even a small population of irregularly shaped or large particles will exceed the defect budget. Colloidal silica&#8217;s tight size distribution and spherical morphology are the only abrasive characteristics currently capable of meeting these specifications in production. Fumed silica&#8217;s aggregate morphology makes it fundamentally incompatible with sub-0.3 nm RMS surface finish requirements.<\/p>\n<\/section>\n\n<section id=\"key-specs\">\n  <h2>6. Key Specifications for CMP-Grade Colloidal Silica<\/h2>\n  <p>When evaluating a colloidal silica slurry for CMP use, the following specification parameters\u2014all of which should be reported on the Certificate of Analysis (CoA) for each production lot\u2014are the primary decision variables:<\/p>\n  <ul>\n    <li><strong>D50 (median particle diameter by DLS)<\/strong>: The primary MRR-governing parameter; must match the application requirement (see selection guide)<\/li>\n    <li><strong>D90 (90th percentile by DLS)<\/strong>: D90\/D50 ratio should be \u22642.0 for well-controlled production lots<\/li>\n    <li><strong>Large Particle Count (LPC) by SPOS<\/strong>: At >0.5 \u00b5m and >1 \u00b5m thresholds; the primary defect risk parameter; specify LPC by SPOS explicitly\u2014laser diffraction data cannot reliably quantify this tail<\/li>\n    <li><strong>pH at 25\u00b0C<\/strong>: Must fall within the specified stability window; verify against the declared IEP-safe range<\/li>\n    <li><strong>Solids content (wt%) by TGA<\/strong>: Determines working concentration and dilution factor<\/li>\n    <li><strong>Zeta potential (mV)<\/strong>: Should be more negative than \u221230 mV at working pH; confirms stability<\/li>\n    <li><strong>Metallic impurities (ppb, ICP-MS)<\/strong>: Na, K, Fe, Cu, Ni; critical for gate-oxide-proximate processes<\/li>\n  <\/ul>\n  <div class=\"jcs-link-box\">\n    <span class=\"jcs-link-box-icon\">\u2192<\/span>\n    <span>For a quantitative deep-dive into how D50, D90, and LPC each affect CMP process outcomes\u2014MRR, defect density, surface roughness, and selectivity\u2014see: <a href=\"https:\/\/jeez-semicon.com\/fr\/blog\/Colloidal-Silica-Particle-Size-How-Abrasive-Diameter-Drives-MRR-Selectivity-and-Scratch-Risk\/\" target=\"_blank\" rel=\"noopener noreferrer\">Colloidal Silica Particle Size: How Abrasive Diameter Drives MRR, Selectivity, and Scratch Risk<\/a><\/span>\n  <\/div>\n  <p>For a complete overview of colloidal silica slurry applications, selection criteria, and product options, see our master reference: <a href=\"https:\/\/jeez-semicon.com\/fr\/blog\/Colloidal-Silica-Slurry-The-Complete-Guide-to-CMP-Applications-Properties-and-Selection\/\" target=\"_blank\" rel=\"noopener noreferrer\">Colloidal Silica Slurry: The Complete Guide to CMP Applications, Properties, and Selection<\/a>.<\/p>\n<\/section>\n\n<section id=\"faq\">\n  <h2>7. Questions fr\u00e9quemment pos\u00e9es<\/h2>\n  <div class=\"jcs-faq-item\">\n    <div class=\"jcs-faq-q\">Is colloidal silica the same as silica sol?<\/div>\n    <div class=\"jcs-faq-a\"><p>Yes\u2014the two terms describe the same class of material. &#8220;Silica sol&#8221; is the traditional chemical engineering term for a stable colloidal dispersion of amorphous SiO\u2082 in water, widely used in catalyst manufacturing and paper coating industries. &#8220;Colloidal silica&#8221; is the preferred terminology in semiconductor CMP and precision polishing contexts. Both refer to stable aqueous dispersions of discrete, nanometer-scale SiO\u2082 particles.<\/p><\/div>\n  <\/div>\n  <div class=\"jcs-faq-item\">\n    <div class=\"jcs-faq-q\">Is the SiO\u2082 in colloidal silica amorphous or crystalline?<\/div>\n    <div class=\"jcs-faq-a\"><p>Colloidal silica is exclusively amorphous\u2014its silicon and oxygen atoms form a random, glass-like network with no long-range crystalline order. This is an important safety distinction: crystalline silica phases (quartz, cristobalite, tridymite) are classified as Group 1 human carcinogens by IARC when inhaled as respirable dust. Amorphous colloidal silica does not share this classification and is considered significantly less hazardous. From a CMP performance standpoint, amorphous SiO\u2082 also lacks cleavage planes, so particles do not fracture to produce sharp new abrasive edges during polishing\u2014a key advantage over crystalline abrasives.<\/p><\/div>\n  <\/div>\n  <div class=\"jcs-faq-item\">\n    <div class=\"jcs-faq-q\">Can colloidal silica slurry be used on substrates other than silicon?<\/div>\n    <div class=\"jcs-faq-a\"><p>Yes. Colloidal silica is used across a wide range of substrate materials beyond silicon. At alkaline pH (10\u201312), it is effective for polishing silicon dioxide (SiO\u2082) dielectric layers, sapphire (Al\u2082O\u2083) wafers for LED and power device substrates, optical glass (borosilicate, fused silica), display glass, and hard disk substrates. The tribochemical removal mechanism adapts to the specific substrate chemistry: on Al\u2082O\u2083, OH\u207b ions attack Al-O bonds analogously to how they attack Si-O bonds on SiO\u2082, forming a softer aluminum hydroxide hydration layer that the colloidal silica abrasive removes mechanically.<\/p><\/div>\n  <\/div>\n  <div class=\"jcs-faq-item\">\n    <div class=\"jcs-faq-q\">What is the typical shelf life of colloidal silica CMP slurry?<\/div>\n    <div class=\"jcs-faq-a\"><p>Properly formulated colloidal silica CMP slurry typically has a shelf life of 12\u201324 months from the manufacture date when stored at 10\u201335\u00b0C in sealed original containers. The primary stability risks are: gelation from temperatures below 5\u00b0C (irreversible); pH drift toward the isoelectric point from CO\u2082 absorption or contamination (triggers aggregation); and introduction of high-ionic-strength contaminants (tap water dilution, incompatible chemical contact) that compress the electrical double layer and reduce zeta potential. Verify pH against the CoA specification before every production lot use; discard or return any lot with pH drift exceeding \u00b10.3 units from the declared value.<\/p><\/div>\n  <\/div>\n<\/section>\n\n<div class=\"jcs-cta\">\n  <h2>Need the Right Colloidal Silica Slurry for Your Process?<\/h2>\n  <p>JEEZ offers CMP-grade colloidal silica in three particle size series (CS-20, CS-60, CS-100) covering final silicon polish through high-MRR oxide CMP. Request a sample or discuss your process requirements with our application engineering team.<\/p>\n  <a href=\"https:\/\/jeez-semicon.com\/fr\/contact\/\" class=\"jcs-cta-btn\" target=\"_blank\" rel=\"noopener noreferrer\">Contact JEEZ \u2192<\/a>\n<\/div>\n\n<hr class=\"jcs-hr\">\n<p class=\"jcs-footnote\">Published by <strong>Jizhi Electronic Technology Co., Ltd. (JEEZ)<\/strong> \u00b7 August 2026. For process-specific advice, <a href=\"https:\/\/jeez-semicon.com\/fr\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\">contact our application engineering team<\/a>.<\/p>\n<\/article>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Is colloidal silica the same as silica sol?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. Silica sol is the older industrial term for a stable colloidal dispersion of amorphous SiO2 nanoparticles in water. Colloidal silica is the preferred term in semiconductor CMP contexts. Both describe the same material.\"}},{\"@type\":\"Question\",\"name\":\"Is the SiO2 in colloidal silica amorphous or crystalline?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Colloidal silica is exclusively amorphous, with a random glass-like SiO2 network. Unlike crystalline silica phases (quartz, cristobalite), it is not classified as a Group 1 carcinogen by IARC, and its particles lack cleavage planes so they do not produce sharp new edges during polishing.\"}},{\"@type\":\"Question\",\"name\":\"Can colloidal silica slurry be used on substrates other than silicon?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. Colloidal silica at alkaline pH is effective for polishing SiO2 dielectrics, sapphire wafers, optical glass, display glass, and hard disk substrates. 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Verify pH against CoA before use; discard lots with more than +\/-0.3 unit pH drift.\"}}]}\n<\/script>","protected":false},"excerpt":{"rendered":"<p>CMP Fundamentals \u00b7 Cluster C-01 A ground-up technical explanation of colloidal silica\u2014what defines it as a material, how its SiO\u2082 nanoparticles are structured, the surface chemistry that drives CMP performance,  &#8230;<\/p>","protected":false},"author":1,"featured_media":2583,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[9,59],"tags":[],"class_list":["post-2580","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry"],"acf":[],"_links":{"self":[{"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/posts\/2580","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/comments?post=2580"}],"version-history":[{"count":2,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/posts\/2580\/revisions"}],"predecessor-version":[{"id":2582,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/posts\/2580\/revisions\/2582"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/media\/2583"}],"wp:attachment":[{"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/media?parent=2580"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/categories?post=2580"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jeez-semicon.com\/fr\/wp-json\/wp\/v2\/tags?post=2580"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}