{"id":2556,"date":"2026-07-30T15:47:09","date_gmt":"2026-07-30T07:47:09","guid":{"rendered":"https:\/\/jeez-semicon.com\/?p=2556"},"modified":"2026-07-30T15:47:09","modified_gmt":"2026-07-30T07:47:09","slug":"silica-vs-alumina-abrasives-in-copper-cmp-slurry-hardness-defectivity-selectivity","status":"publish","type":"post","link":"https:\/\/jeez-semicon.com\/ru\/blog\/silica-vs-alumina-abrasives-in-copper-cmp-slurry-hardness-defectivity-selectivity\/","title":{"rendered":"Silica vs. Alumina Abrasives in Copper CMP Slurry: Hardness, Defectivity &amp; Selectivity"},"content":{"rendered":"<style>\n@import url('https:\/\/fonts.googleapis.com\/css2?family=Space+Grotesk:wght@400;500;600;700;800&family=Inter:ital,wght@0,300;0,400;0,500;0,600;1,400&display=swap');\n.jz-cl*{box-sizing:border-box}.jz-cl{font-family:'Inter',-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;font-size:17px;line-height:1.75;color:#1e293b;max-width:860px;margin:0 auto}\n.jz-cl h1{font-family:'Space 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Grotesk',sans-serif;font-weight:700;font-size:.97rem;padding:13px 32px;border-radius:8px;transition:background .2s,transform .15s;position:relative}\n.jz-cta-btn:hover{background:#9a6228;color:#fff;text-decoration:none;transform:translateY(-2px)}\n.jz-faq{border-top:1px solid #e2e8f0;margin:.8rem 0}.jz-faq-item{border-bottom:1px solid #f1f5f9;padding:1.15rem 0}\n.jz-faq-q{font-family:'Space Grotesk',sans-serif;font-weight:700;color:#0c2340;font-size:.96rem;margin:0 0 5px}\n.jz-faq-a{font-size:.91rem;color:#475569;margin:0;line-height:1.65}\n.jz-hr{border:none;border-top:1px solid #e2e8f0;margin:2.5rem 0}\n@media(max-width:640px){.jz-cl h1{font-size:1.7rem}.jz-cl h2{font-size:1.15rem}.jz-hero{padding:20px 18px}.jz-cards2{grid-template-columns:1fr}.jz-cta{padding:26px 20px}}\n<\/style>\n\n<div class=\"jz-cl\">\n\n<div class=\"jz-pillar-banner\">\n  <span>\ud83d\udcda<\/span>\n  <p>Part of the <strong>\u041c\u0435\u0434\u043d\u044b\u0439 \u0448\u043b\u0430\u043c CMP<\/strong> knowledge series. For the complete process overview, see the <a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Copper-CMP-Slurry-Complete-Guide-Chemistry-Process-Optimization-Advanced-Node-Applications\/\" target=\"_blank\" rel=\"noopener noreferrer\">Copper CMP Slurry: Complete Guide<\/a>.<\/p>\n<\/div>\n\n\n<div class=\"jz-hero\">\n  <p>The choice of abrasive particle in copper CMP slurry is one of the most consequential formulation decisions a process engineer faces. <strong>Colloidal silica<\/strong> \u0438 <strong>alumina<\/strong> represent fundamentally different mechanical approaches to the same polishing task \u2014 and they produce measurably different outcomes in removal rate, surface defect density, and material selectivity. This article compares both abrasive types across the properties that matter most in production copper CMP: hardness and material removal kinetics, particle size and defectivity, surface chemistry and selectivity, and the process application scenarios where each excels.<\/p>\n<\/div>\n\n<div class=\"jz-toc\">\n  <p class=\"jz-toc-hd\">\u041e\u0433\u043b\u0430\u0432\u043b\u0435\u043d\u0438\u0435<\/p>\n  <ol>\n    <li><span class=\"jz-toc-n\">01.<\/span><a href=\"#role\">The Role of Abrasives in Copper CMP<\/a><\/li>\n    <li><span class=\"jz-toc-n\">02.<\/span><a href=\"#silica\">Colloidal Silica: Properties &amp; Applications<\/a><\/li>\n    <li><span class=\"jz-toc-n\">03.<\/span><a href=\"#alumina\">Alumina Abrasives: Fumed vs. Colloidal<\/a><\/li>\n    <li><span class=\"jz-toc-n\">04.<\/span><a href=\"#hardness\">Hardness, Scratch Mechanisms &amp; Defectivity<\/a><\/li>\n    <li><span class=\"jz-toc-n\">05.<\/span><a href=\"#size\">Particle Size, Distribution &amp; Colloidal Stability<\/a><\/li>\n    <li><span class=\"jz-toc-n\">06.<\/span><a href=\"#selectivity\">Selectivity Implications of Abrasive Choice<\/a><\/li>\n    <li><span class=\"jz-toc-n\">07.<\/span><a href=\"#decision\">Abrasive Selection Decision Framework<\/a><\/li>\n    <li><span class=\"jz-toc-n\">08.<\/span><a href=\"#faq\">\u0427\u0430\u0441\u0442\u043e \u0437\u0430\u0434\u0430\u0432\u0430\u0435\u043c\u044b\u0435 \u0432\u043e\u043f\u0440\u043e\u0441\u044b<\/a><\/li>\n  <\/ol>\n<\/div>\n\n<h2 id=\"role\">1. The Role of Abrasives in Copper CMP<\/h2>\n<p>Abrasive particles provide the mechanical component of the CMP process. Without them, the chemical system \u2014 oxidizer, complexing agent, corrosion inhibitor \u2014 would produce isotropic dissolution that removes copper uniformly from all surfaces, including the recessed features that must be preserved. Abrasives are what make material removal selective to pad-contact zones: they concentrate the mechanical energy of the pad-wafer interface into discrete contact events at particle-scale dimensions, enabling removal of the chemically softened copper oxide layer preferentially at elevated surface points.<\/p>\n<p>The performance requirements placed on CMP abrasives span several dimensions simultaneously:<\/p>\n<ul>\n  <li><strong>Hardness:<\/strong> Must be hard enough to mechanically disrupt the BTA-Cu passivation film and abrade the copper oxide layer at the polishing pressure used.<\/li>\n  <li><strong>Size and distribution:<\/strong> D50 must be large enough to make effective contact with the softened copper surface; D99 must be controlled to prevent oversized particles from causing scratch defects.<\/li>\n  <li><strong>Surface chemistry:<\/strong> Surface charge (zeta potential) determines colloidal stability, particle-surface interactions, and the effective selectivity between different materials being polished.<\/li>\n  <li><strong>Chemical inertness:<\/strong> The abrasive must not react chemically with the copper, ILD, or barrier metal in ways that alter the fundamental polishing mechanism or contaminate the wafer surface.<\/li>\n<\/ul>\n\n<h2 id=\"silica\">2. Colloidal Silica: Properties &amp; Applications<\/h2>\n\n<div class=\"jz-cards2\">\n  <div class=\"jz-card\">\n    <div class=\"jz-card-ico\">\ud83d\udd2c<\/div>\n    <h4>Physical Properties<\/h4>\n    <p>Mohs hardness \u2248 7 (bulk fused SiO\u2082). Spherical morphology. D50 range 30\u2013200 nm in production formulations. Point of zero charge (PZC) \u2248 pH 2\u20133. Stable as negative colloid above pH 3.<\/p>\n  <\/div>\n  <div class=\"jz-card\">\n    <div class=\"jz-card-ico\">\u2699\ufe0f<\/div>\n    <h4>Production Synthesis<\/h4>\n    <p>St\u00f6ber process (base-catalyzed TEOS hydrolysis) or ion-exchange process from sodium silicate. Both yield narrow PSD. Surface functionalization possible via silane coupling agents.<\/p>\n  <\/div>\n<\/div>\n\n<p>Colloidal silica is the dominant abrasive in Step 2 barrier CMP slurries and in all advanced-node (7 nm and below) copper CMP applications \u2014 for Step 1 as well as Step 2. Its lower hardness relative to alumina is actually an asset in these contexts: it removes the softened copper oxide layer efficiently without generating sub-surface damage, and it is gentle enough to coexist with fragile ELK dielectric materials (which have mechanical hardness lower than SiO\u2082 itself at k &lt; 2.5).<\/p>\n\n<h3>Surface Chemistry and Selectivity<\/h3>\n<p>The surface of colloidal silica particles at neutral pH is covered with silanol groups (Si\u2013OH) that are fully deprotonated to Si\u2013O\u207b at pH &gt; 5, giving the particles a large negative zeta potential (typically \u221230 to \u221250 mV at pH 7). This strong negative charge provides excellent electrostatic stabilization of the colloidal dispersion and creates an electrostatic barrier between particles and the similarly negative ILD surface (TEOS oxide, ELK OSG) \u2014 reducing abrasive-ILD contact and contributing to the high Cu:ILD selectivity observed with colloidal silica formulations.<\/p>\n<p>Surface functionalization of colloidal silica \u2014 attaching organic groups via silane chemistry \u2014 allows further tuning of selectivity. Amino-functionalized silica particles (positive surface charge at neutral pH) show increased Cu:barrier selectivity at specific pH ranges because of their affinity for the oxidized copper surface (negative). Carboxyl-functionalized particles can be tuned for specific surface selectivity in advanced BEOL processes. This chemistry flexibility is one of colloidal silica&#8217;s key advantages over alumina as abrasive platforms evolve for advanced node requirements.<\/p>\n\n<h2 id=\"alumina\">3. Alumina Abrasives: Fumed vs. Colloidal<\/h2>\n<p>Alumina (Al\u2082O\u2083) exists in several crystallographic phases relevant to CMP: gamma-alumina (\u03b3-Al\u2082O\u2083, Mohs \u2248 7.5\u20138.5, the most common CMP phase) and alpha-alumina (\u03b1-Al\u2082O\u2083, Mohs \u2248 9, harder and more abrasive). In copper CMP, gamma-alumina is predominantly used in both fumed and colloidal forms.<\/p>\n\n<h3>Fumed Alumina<\/h3>\n<p>Fumed alumina is produced by high-temperature vapor-phase hydrolysis of aluminum chloride, producing fractal, chain-like agglomerate structures of primary particles (10\u201350 nm) that form loose secondary agglomerates (100\u2013500 nm). This fractal morphology provides a very high specific surface area (BET \u2248 80\u2013150 m\u00b2\/g) and excellent mechanical cutting efficiency \u2014 the sharp edges and angles of the primary particle chain contacts with the copper surface create higher local stress concentrations than the smooth spherical silica particles, delivering higher removal rates at the same nominal particle size.<\/p>\n<p>The tradeoff of fumed alumina&#8217;s fractal morphology is more difficult colloidal stability: the complex agglomerate structures are prone to further agglomeration under shear stress in the CMP process, and controlling D99 to prevent large agglomerates from causing scratch defects is more challenging than with colloidal silica. Fumed alumina slurries require more aggressive filtration (0.2 \u00b5m absolute POU filter) and tighter pH control to maintain stable colloidal dispersion.<\/p>\n\n<h3>Colloidal Alumina<\/h3>\n<p>Colloidal alumina is produced by precipitation from aluminum salt solutions under controlled pH and temperature, yielding more uniform, pseudo-spherical particles with narrower size distribution than fumed alumina. Colloidal alumina has better colloidal stability than fumed alumina but somewhat lower removal rate per unit mass due to the lower surface energy of its rounder particle morphology. It occupies a performance middle ground between fumed alumina (high rate, high defect) and colloidal silica (lower rate, low defect).<\/p>\n\n<h2 id=\"hardness\">4. Hardness, Scratch Mechanisms &amp; Defectivity<\/h2>\n<p>The scratch risk of an abrasive is determined not simply by its bulk hardness but by the interaction between particle hardness, morphology, size distribution, and the mechanical properties of the surface being polished. In copper CMP, three materials with very different hardness profiles are polished simultaneously: copper (Vickers \u2248 369 MPa), barrier metal (Ta: \u2248 873 MPa, Co: \u2248 1043 MPa), and ILD (TEOS SiO\u2082: \u2248 8,800 MPa).<\/p>\n\n<div class=\"jz-tw\">\n  <table class=\"jz-tab\">\n    <thead><tr><th>\u0410\u0431\u0440\u0430\u0437\u0438\u0432<\/th><th>Mohs Hardness<\/th><th>Vickers Hardness (MPa)<\/th><th>Scratch Risk on Cu<\/th><th>Scratch Risk on ELK ILD<\/th><\/tr><\/thead>\n    <tbody>\n      <tr><td>\u041a\u043e\u043b\u043b\u043e\u0438\u0434\u043d\u044b\u0439 SiO\u2082<\/td><td>\u22487.0<\/td><td>\u22485,500\u20137,000<\/td><td>\u041d\u0438\u0437\u043a\u0438\u0439<\/td><td>Low\u2013Medium<\/td><\/tr>\n      <tr><td>\u03b3-Al\u2082O\u2083 (colloidal)<\/td><td>\u22487.5\u20138.5<\/td><td>\u224815,000\u201320,000<\/td><td>\u0421\u0440\u0435\u0434\u043d\u0438\u0439<\/td><td>\u0421\u0440\u0435\u0434\u043d\u0438\u0439<\/td><\/tr>\n      <tr><td>Fumed Al\u2082O\u2083<\/td><td>\u22487.5\u20138.5<\/td><td>\u224815,000\u201320,000<\/td><td>Medium\u2013High<\/td><td>\u0412\u044b\u0441\u043e\u043a\u0438\u0439<\/td><\/tr>\n      <tr><td>\u03b1-Al\u2082O\u2083<\/td><td>\u22489.0<\/td><td>\u224822,000\u201325,000<\/td><td>\u0412\u044b\u0441\u043e\u043a\u0438\u0439<\/td><td>\u041e\u0447\u0435\u043d\u044c \u0432\u044b\u0441\u043e\u043a\u0438\u0439<\/td><\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>Scratch formation in copper CMP follows a plastic deformation model: a particle indent into the surface creates a groove when the local contact pressure exceeds the surface&#8217;s yield strength. For a given polishing pressure, smaller particles create smaller contact areas and therefore higher local stress concentrations \u2014 counter-intuitively, smaller particles can produce deeper scratches than larger ones if they are harder. However, this effect is secondary to the dominant scratch mechanism in production: oversized particles (agglomerates, hard inclusions, pad debris) with D &gt; 500 nm are responsible for the vast majority of critical scratches in production copper CMP. This is why D99 control and POU filtration are more important defect-reduction levers than the choice of nominal abrasive type.<\/p>\n\n<h2 id=\"size\">5. Particle Size, Distribution &amp; Colloidal Stability<\/h2>\n<p>The ideal abrasive particle size for copper CMP involves competing tradeoffs. Larger particles (D50 &gt; 150 nm) create larger contact areas per particle, reducing local stress concentration and scratch depth \u2014 but also reducing the number of contact events per unit area at fixed particle mass concentration, potentially reducing removal rate uniformity. Smaller particles (D50 &lt; 60 nm) provide more contact points and better surface conformality but generate lower removal rate per contact event due to lower mechanical energy per impact.<\/p>\n<p>Production copper CMP slurries use D50 values in the range of <strong>60\u2013150 nm<\/strong> for both silica and alumina abrasives \u2014 a range that balances removal rate efficiency with defect risk. The D99 control is more critical than D50: the presence of even a small number of large particles (D &gt; 500 nm) in the abrasive distribution dramatically increases scratch density. Colloidal silica typically achieves D99\/D50 ratios of 2.5\u20133.5 in production formulations; fumed alumina typically shows D99\/D50 ratios of 5\u201315, reflecting its less uniform agglomerate structure.<\/p>\n<p>Colloidal stability \u2014 the resistance of the particle dispersion to agglomeration under slurry delivery conditions (pump recirculation, temperature variation, pH change) \u2014 is better for colloidal silica than alumina at most conditions. The highly negative zeta potential of silica at neutral pH (\u221230 to \u221250 mV) provides strong electrostatic repulsion between particles, while alumina has a PZC near pH 8\u20139, meaning it is near-zero or positively charged in the typical copper CMP pH range of 4\u20137, with weaker electrostatic stabilization.<\/p>\n\n<h2 id=\"selectivity\">6. Selectivity Implications of Abrasive Choice<\/h2>\n<p>The choice of abrasive significantly affects the material removal selectivity between copper, barrier metal, and ILD \u2014 independently of the chemical component of the slurry. This mechanical selectivity contribution arises from the different hardness ratios between the abrasive and each material being polished.<\/p>\n<p>For <strong>colloidal silica<\/strong>: SiO\u2082 (hardness \u2248 7,000 MPa) is harder than copper oxide (\u2248 150\u2013400 MPa as the polished species, after H\u2082O\u2082 oxidation) and softer than ILD SiO\u2082 (\u2248 8,800 MPa) and barrier Ta (\u2248 8,000 MPa). This means silica abrasives preferentially scratch the softer copper oxide while making minimal contact with the harder ILD \u2014 contributing a mechanical component to high Cu:ILD selectivity.<\/p>\n<p>For <strong>alumina<\/strong>: Al\u2082O\u2083 (hardness \u2248 15,000\u201320,000 MPa) is harder than all three materials being polished \u2014 copper, ILD, and barrier metals. This means alumina removes all three at rates proportional to their hardness, with no mechanical selectivity contribution. The Cu:ILD selectivity of alumina-based slurries is driven entirely by the chemical components (BTA passivation of ILD vs. copper oxidation), making it harder to achieve high Cu:ILD selectivity with alumina than with silica.<\/p>\n\n<h2 id=\"decision\">7. Abrasive Selection Decision Framework<\/h2>\n<p>The practical guide for abrasive selection in copper CMP reduces to a small number of process-condition-driven rules:<\/p>\n<ul>\n  <li><strong>Step 1 at conventional nodes (\u226528 nm, \u22651.5 psi):<\/strong> Fumed or colloidal alumina for maximum removal rate. The higher defect risk is tolerable because Step 1 defects are partially removed in Step 2. Use POU 0.2 \u00b5m filtration to control D99.<\/li>\n  <li><strong>Step 1 at advanced nodes (&lt;7 nm, &lt;1 psi, ELK ILD present):<\/strong> Engineered colloidal silica with chemically enhanced formulations (higher H\u2082O\u2082, optimized glycine). Alumina&#8217;s defect risk is unacceptable on ELK dielectrics and narrow copper features at sub-nm dishing tolerance.<\/li>\n  <li><strong>Step 2 (all nodes):<\/strong> Colloidal silica, always. The need for high Cu:ILD selectivity and low defectivity at Step 2 makes alumina unsuitable in essentially all production applications.<\/li>\n  <li><strong>Step 3 buff (advanced nodes):<\/strong> Sub-40 nm colloidal silica or abrasive-free formulations for minimum surface roughness and maximum planarity restoration.<\/li>\n<\/ul>\n\n<div class=\"jz-callout jz-ct\">\n  <p><strong>2026 trend:<\/strong> The industry-wide push to lower polishing pressures for ELK compatibility is steadily shifting abrasive choices in Step 1 from alumina toward advanced colloidal silica \u2014 even at conventional nodes where ELK is not used \u2014 because the defect reduction benefits of silica outweigh the removal rate advantage of alumina once a slurry&#8217;s chemical activity is sufficiently enhanced to compensate mechanically. JEEZ&#8217;s CuB-S (silica-based Step 1) series reflects this trend.<\/p>\n<\/div>\n\n<hr class=\"jz-hr\">\n\n<h2 id=\"faq\">8. Frequently Asked Questions<\/h2>\n<div class=\"jz-faq\">\n  <div class=\"jz-faq-item\">\n    <p class=\"jz-faq-q\">Can colloidal silica achieve the same removal rate as alumina in Step 1 copper CMP?<\/p>\n    <p class=\"jz-faq-a\">At equivalent polishing pressure, colloidal silica typically delivers 30\u201350% lower removal rate than alumina for bulk copper Step 1. However, this gap can be substantially narrowed by increasing oxidizer concentration (more H\u2082O\u2082), reducing BTA loading, and increasing particle loading. At advanced-node low-pressure conditions (&lt;1 psi), the practical removal rate gap between optimized silica and alumina formulations narrows to &lt;20%, making silica the preferred choice given its much better defect profile on ELK dielectric stacks.<\/p>\n  <\/div>\n  <div class=\"jz-faq-item\">\n    <p class=\"jz-faq-q\">Why does particle zeta potential matter for abrasive selectivity?<\/p>\n    <p class=\"jz-faq-a\">Zeta potential determines the electrostatic interaction between abrasive particles and the surfaces being polished. A negatively charged colloidal silica particle (zeta \u2248 \u221240 mV at pH 7) experiences electrostatic repulsion from the negatively charged ILD surface (SiO\u2082 and OSG are also negative at neutral pH) \u2014 reducing effective contact with the ILD and contributing to high Cu:ILD selectivity. Alumina near its PZC (pH 8\u20139) has near-zero zeta potential at copper CMP pH ranges, providing no electrostatic selectivity contribution \u2014 removal rates are determined almost entirely by the mechanical hardness ratio.<\/p>\n  <\/div>\n  <div class=\"jz-faq-item\">\n    <p class=\"jz-faq-q\">How does abrasive type affect post-CMP cleaning requirements?<\/p>\n    <p class=\"jz-faq-a\">Alumina abrasives tend to adhere more tenaciously to the polished surface than colloidal silica \u2014 alumina&#8217;s positive surface charge (at pH &lt; PZC) causes electrostatic adhesion to the negatively charged wafer surface and to the BTA-Cu complex film. This means alumina-containing slurries typically require more aggressive post-CMP cleaning (higher citric acid concentration, longer brush scrub time) than silica-based slurries. The cleaning chemistry must also be verified to be free of alumina re-deposition risk after the brush step.<\/p>\n  <\/div>\n  <div class=\"jz-faq-item\">\n    <p class=\"jz-faq-q\">Is ceria (CeO\u2082) relevant for copper CMP?<\/p>\n    <p class=\"jz-faq-a\">Ceria is primarily used in shallow trench isolation (STI) and oxide CMP applications where its ability to chemically attack Si\u2013O bonds provides extremely high SiO\u2082 removal rate and selectivity. In copper CMP, ceria&#8217;s strong oxide removal mechanism is generally undesirable \u2014 it would cause excessive ILD erosion in Step 2. However, as of 2026, some research groups and advanced packaging applications are exploring ceria-hybrid formulations for planarization of copper\/oxide stacks in redistribution layer (RDL) CMP, where the primary polishing surface is oxide rather than copper. This remains a non-mainstream application and is not used in front-end-of-line copper interconnect CMP.<\/p>\n  <\/div>\n<\/div>\n\n<div class=\"jz-related\">\n  <h3>Related Articles in This Series<\/h3>\n  <ul>\n    <li><a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Copper-CMP-Slurry-Chemistry-Oxidizers-Complexing-Agents-Corrosion-Inhibitors\/\" target=\"_blank\" rel=\"noopener noreferrer\">Copper CMP Slurry Chemistry: Oxidizers, Complexing Agents &amp; Corrosion Inhibitors<\/a><\/li>\n    <li><a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Dishing-and-Erosion-in-Copper-CMP-Causes-Pattern-Density-Effects-Mitigation\/\" target=\"_blank\" rel=\"noopener noreferrer\">Dishing and Erosion in Copper CMP: Causes, Pattern Density Effects &amp; Mitigation<\/a><\/li>\n    <li><a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Copper-CMP-at-Advanced-Nodes-7-nm-and-Below-ELK-Dielectrics-Cobalt-Liners-Slurry-Innovations\/\" target=\"_blank\" rel=\"noopener noreferrer\">Copper CMP at Advanced Nodes (7 nm and Below)<\/a><\/li>\n    <li><a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Copper-CMP-Slurry-Complete-Guide-Chemistry-Process-Optimization-Advanced-Node-Applications\/\" target=\"_blank\" rel=\"noopener noreferrer\">Copper CMP Slurry: Complete Guide (Pillar)<\/a><\/li>\n  <\/ul>\n<\/div>\n\n<div class=\"jz-cta\">\n  <h2>Need Help Choosing the Right Abrasive for Your Copper CMP Process?<\/h2>\n  <p>Jizhi Electronic Technology Co., Ltd. (JEEZ) offers alumina-based CuB and colloidal silica-based CuB-S Step 1 slurries, as well as the full CuS Step 2 series \u2014 all with application engineering support for abrasive selection and process optimization at any node and barrier stack.<\/p>\n  <a href=\"https:\/\/jeez-semicon.com\/ru\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"jz-cta-btn\">Contact JEEZ Application Engineering \u2192<\/a>\n<\/div>\n\n<\/div>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Can colloidal silica achieve the same removal rate as alumina in Step 1 copper CMP?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"At equivalent pressure, colloidal silica delivers 30-50% lower removal rate than alumina. This gap narrows to less than 20% at advanced-node low-pressure conditions with optimized chemical formulations, making silica the preferred choice given its much better defect profile on ELK dielectric stacks.\"}},{\"@type\":\"Question\",\"name\":\"Why does abrasive zeta potential matter for copper CMP selectivity?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Negatively charged colloidal silica (zeta \u2248 -40 mV at pH 7) is electrostatically repelled from the negative ILD surface, reducing particle-ILD contact and contributing to high Cu:ILD selectivity. Alumina near its PZC at CMP pH ranges provides no electrostatic selectivity \u2014 removal rates are determined by mechanical hardness ratios only.\"}},{\"@type\":\"Question\",\"name\":\"How does abrasive type affect post-CMP cleaning requirements?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Alumina adheres more tenaciously to the wafer surface than silica due to its positive surface charge at typical CMP pH, causing electrostatic adhesion to the negatively charged wafer. Alumina-based slurries require more aggressive cleaning (higher citric acid concentration, longer brush time) than silica-based formulations.\"}},{\"@type\":\"Question\",\"name\":\"Is ceria relevant for copper CMP slurry?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Ceria is primarily used in STI and oxide CMP. In front-end copper interconnect CMP, ceria's strong oxide removal mechanism would cause excessive ILD erosion in Step 2. Limited research explores ceria-hybrid formulations for advanced packaging RDL CMP, but this is not mainstream in front-end copper interconnect applications.\"}}]}\n<\/script>","protected":false},"excerpt":{"rendered":"<p>\ud83d\udcda Part of the Copper CMP Slurry knowledge series. For the complete process overview, see the Copper CMP Slurry: Complete Guide. The choice of abrasive particle in copper CMP slurry  &#8230;<\/p>","protected":false},"author":1,"featured_media":2560,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[9,59],"tags":[],"class_list":["post-2556","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry"],"acf":[],"_links":{"self":[{"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts\/2556","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/comments?post=2556"}],"version-history":[{"count":2,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts\/2556\/revisions"}],"predecessor-version":[{"id":2561,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts\/2556\/revisions\/2561"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/media\/2560"}],"wp:attachment":[{"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/media?parent=2556"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/categories?post=2556"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/tags?post=2556"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}