{"id":2415,"date":"2026-06-30T16:45:33","date_gmt":"2026-06-30T08:45:33","guid":{"rendered":"https:\/\/jeez-semicon.com\/?p=2415"},"modified":"2026-06-30T16:45:33","modified_gmt":"2026-06-30T08:45:33","slug":"how-cmp-machines-work-process-mechanics-forces-planarization-physics","status":"publish","type":"post","link":"https:\/\/jeez-semicon.com\/ja\/blog\/how-cmp-machines-work-process-mechanics-forces-planarization-physics\/","title":{"rendered":"How CMP Machines Work: Process Mechanics, Forces &amp; Planarization Physics"},"content":{"rendered":"<link href=\"https:\/\/fonts.googleapis.com\/css2?family=Syne:wght@600;700&#038;family=Inter:ital,wght@0,400;0,500;0,600;1,400&#038;display=swap\" rel=\"stylesheet\">\n\n<style>\n.jcmp-art {\n  --jc-navy:        #0A2547;\n  --jc-blue:        #1B6FC8;\n  --jc-blue-hover:  #1459A8;\n  --jc-blue-light:  #EEF4FF;\n  --jc-blue-border: #C5D9F6;\n  --jc-text:        #1A1F2E;\n  --jc-text-2:      #4B5563;\n  --jc-text-3:      #9CA3AF;\n  --jc-border:      #E5E7EB;\n  --jc-bg:          #F8FAFF;\n  --jc-white:       #FFFFFF;\n  --jc-green:       #059669;\n  font-family: 'Inter', system-ui, -apple-system, sans-serif;\n  color: var(--jc-text);\n  line-height: 1.8;\n  font-size: 16px;\n  max-width: 860px;\n  margin: 0 auto;\n}\n.jcmp-art *, .jcmp-art *::before, .jcmp-art *::after { box-sizing: border-box; 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}\n  .jcmp-grid { grid-template-columns: 1fr; }\n  .jcmp-toc ol { column-count: 1; }\n  .jcmp-art h1 { font-size: 1.8rem; }\n  .jcmp-art h2 { font-size: 1.35rem; }\n  .jcmp-cta { padding: 1.5rem; }\n  .jcmp-cta-mid { flex-direction: column; align-items: flex-start; }\n}\n<\/style>\n\n<div class=\"jcmp-art\" itemscope itemtype=\"https:\/\/schema.org\/Article\">\n\n  <div class=\"jcmp-meta\">\n    <span>Last updated: July 2026<\/span>\n    <span class=\"jcmp-meta-dot\"><\/span>\n    <span>14 min read<\/span>\n    <span class=\"jcmp-meta-dot\"><\/span>\n    <span>JEEZ Technical Editorial Team \u2014 Jizhi Electronic Technology Co., Ltd.<\/span>\n  <\/div>\n\n\n  <p class=\"jcmp-lead\">\n    Understanding how a CMP machine works requires looking past the hardware and into the physics happening at the wafer-pad interface: a few microns of contact zone where chemistry and mechanics interact thousands of times per second to remove material atom layer by atom layer. This guide breaks down the governing equations, force balances, and reaction mechanisms that determine how CMP machines actually planarize a wafer surface \u2014 the engineering foundation behind every recipe a process engineer writes.\n  <\/p>\n\n  <div class=\"jcmp-stats\">\n    <div class=\"jcmp-stat\">\n      <div class=\"jcmp-stat-num\">2<\/div>\n      <div class=\"jcmp-stat-label\">Simultaneous removal mechanisms: chemical + mechanical<\/div>\n    <\/div>\n    <div class=\"jcmp-stat\">\n      <div class=\"jcmp-stat-num\">1\u201310nm<\/div>\n      <div class=\"jcmp-stat-label\">Typical asperity-scale contact zone at the pad-wafer interface<\/div>\n    <\/div>\n    <div class=\"jcmp-stat\">\n      <div class=\"jcmp-stat-num\">0.5\u20137 psi<\/div>\n      <div class=\"jcmp-stat-label\">Typical carrier head down-pressure range in production CMP<\/div>\n    <\/div>\n    <div class=\"jcmp-stat\">\n      <div class=\"jcmp-stat-num\">30\u2013120<\/div>\n      <div class=\"jcmp-stat-label\">Typical platen rotation speed range (rpm) in production CMP<\/div>\n    <\/div>\n  <\/div>\n\n  <nav class=\"jcmp-toc\" aria-label=\"\u76ee\u6b21\">\n    <div class=\"jcmp-toc-title\">\u76ee\u6b21<\/div>\n    <ol>\n      <li><a href=\"#why-both\">Why CMP Needs Both Chemistry and Mechanics<\/a><\/li>\n      <li><a href=\"#preston\">Preston&#8217;s Equation: The Governing Removal Rate Model<\/a><\/li>\n      <li><a href=\"#forces\">Forces at the Wafer-Pad Interface<\/a><\/li>\n      <li><a href=\"#tribology\">Tribology of the Slurry-Pad-Wafer System<\/a><\/li>\n      <li><a href=\"#chemistry\">Surface Chemistry: How Different Materials Are Removed<\/a><\/li>\n      <li><a href=\"#kinematics\">Dual Rotation Kinematics and Uniformity<\/a><\/li>\n      <li><a href=\"#variables\">Process Variable Summary<\/a><\/li>\n      <li><a href=\"#faq\">\u3088\u304f\u3042\u308b\u8cea\u554f<\/a><\/li>\n    <\/ol>\n  <\/nav>\n\n  <section id=\"why-both\">\n    <h2>Why CMP Needs Both Chemistry and Mechanics<\/h2>\n\n    <p>Material removal processes can be classified along a spectrum from purely mechanical to purely chemical. Pure mechanical abrasion \u2014 grinding, lapping \u2014 removes material quickly but leaves deep subsurface crystal lattice damage, microscopic cracks, and rough surface topography that propagate defects into the device layers above. Pure chemical etching \u2014 wet or dry \u2014 removes material with minimal physical damage but cannot achieve planarization on its own, since chemical etch rates are largely insensitive to surface topography and tend to replicate the existing surface profile rather than flatten it.<\/p>\n\n    <p>CMP machines occupy the productive middle ground between these two extremes by combining both mechanisms in a single, continuous process. The chemical component of the slurry reacts with the wafer surface to form a softened reaction layer \u2014 far easier to remove than the unreacted bulk material beneath it. The mechanical component, delivered by abrasive particles under controlled pressure and relative velocity, then removes this softened layer preferentially from the raised, high-contact-pressure regions of the wafer topography, while leaving recessed, low-contact-pressure regions comparatively untouched. This pressure-dependent removal selectivity is the physical mechanism that produces planarization rather than uniform etching: high points are removed faster than low points until the surface flattens.<\/p>\n\n    <div class=\"jcmp-callout\">\n      <strong>The core insight:<\/strong> CMP achieves planarization not because it removes material everywhere equally, but because it removes material <em>faster where the local contact pressure is higher<\/em> \u2014 which is precisely where wafer topography protrudes. This pressure-dependent removal rate is what distinguishes CMP from a simple chemical etch.\n    <\/div>\n\n    <p>For a foundational overview of what a CMP machine is and where it fits in the broader semiconductor process flow, see our complete guide: <a href=\"https:\/\/jeez-semicon.com\/ja\/blog\/CMP-Machines-The-Complete-Guide-to-Chemical-Mechanical-Planarization-Equipment\/\" target=\"_blank\" rel=\"noopener noreferrer\">CMP Machines: The Complete Guide to Chemical Mechanical Planarization Equipment<\/a>.<\/p>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"preston\">\n    <h2>Preston&#8217;s Equation: The Governing Removal Rate Model<\/h2>\n\n    <p>The foundational mathematical model for CMP removal rate originates from Franklin Preston&#8217;s 1927 work on glass polishing, adapted directly to semiconductor CMP in the early 1990s. Preston&#8217;s Equation expresses the instantaneous material removal rate as a linear function of two mechanical variables: applied pressure and relative sliding velocity.<\/p>\n\n    <div class=\"jcmp-formula\">\n      MRR = K<sub>p<\/sub> \u00d7 P \u00d7 V\n      <div class=\"jcmp-formula-note\">MRR = material removal rate \u00b7 K<sub>p<\/sub> = Preston coefficient \u00b7 P = applied pressure \u00b7 V = relative velocity<\/div>\n    <\/div>\n\n    <p>The <strong>Preston coefficient (K<sub>p<\/sub>)<\/strong> is not a universal constant \u2014 it is an empirically determined value specific to a given combination of slurry chemistry, pad material, and wafer surface material. K<sub>p<\/sub> absorbs all of the chemical reactivity, particle hardness, particle concentration, and pad mechanical properties into a single proportionality factor. In practice, process engineers determine K<sub>p<\/sub> experimentally for each consumable set and process condition through blanket wafer removal rate characterization, then use it to predict removal rate response when pressure or velocity is adjusted.<\/p>\n\n    <h3>Where Preston&#8217;s Equation Breaks Down<\/h3>\n    <p>While Preston&#8217;s Equation provides a useful first-order model, real CMP processes deviate from strict linearity in several well-documented ways that every process engineer must account for:<\/p>\n\n    <ul>\n      <li><strong>Low-pressure threshold effects:<\/strong> Below a critical pressure threshold, removal rate drops faster than linear prediction because asperity contact area \u2014 and therefore actual mechanical engagement \u2014 falls below the level needed to sustain consistent chemical-mechanical synergy.<\/li>\n      <li><strong>High-velocity saturation:<\/strong> At very high relative velocities, hydrodynamic lubrication effects can partially separate the pad from the wafer surface with a thicker slurry film, reducing direct mechanical contact and causing removal rate to plateau rather than continue increasing linearly.<\/li>\n      <li><strong>Pattern density dependence (the &#8220;loading effect&#8221;):<\/strong> Preston&#8217;s Equation was derived for blanket, unpatterned films. On patterned wafers, the local contact pressure experienced by raised features depends on the fraction of the die area occupied by raised structures (pattern density). Dense feature regions experience lower effective local pressure (the load is distributed across more contact area) and therefore polish more slowly than isolated, low-density features \u2014 a phenomenon with no representation in the basic Preston model and a primary cause of within-die non-uniformity.<\/li>\n      <li><strong>Edge effects:<\/strong> Near the wafer edge, the carrier head&#8217;s retaining ring and the discontinuity in mechanical boundary conditions create localized pressure distortions that cause removal rate to deviate from the Preston prediction within approximately 3\u20135mm of the wafer perimeter.<\/li>\n    <\/ul>\n\n    <p>Advanced CMP modeling extends Preston&#8217;s basic framework with pattern-density-dependent effective pressure terms, time-dependent K<sub>p<\/sub> evolution (accounting for pad conditioning state and slurry depletion), and multi-asperity contact mechanics models that more accurately predict real production removal rate behavior.<\/p>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"forces\">\n    <h2>Forces at the Wafer-Pad Interface<\/h2>\n\n    <p>The force balance acting on a wafer during CMP determines both the bulk removal rate and the local removal rate distribution that governs uniformity. Three categories of force interact at the polishing interface:<\/p>\n\n    <h3>Normal Force (Down-Pressure)<\/h3>\n    <p>Applied by the carrier head&#8217;s pneumatic membrane system through the backing film, normal force presses the wafer against the polishing pad. Production CMP processes typically apply 0.5 to 7 psi of down-pressure depending on the application \u2014 tungsten CMP and other high-removal-rate bulk steps operate toward the higher end of this range, while delicate final-polish and low-k dielectric steps use minimal pressure to avoid film damage. Modern multi-zone carrier heads independently control pressure across 5 to 7 concentric radial zones, allowing the normal force profile to be actively shaped to compensate for systematic radial removal rate non-uniformities.<\/p>\n\n    <h3>Shear Force and Friction<\/h3>\n    <p>As the platen and carrier head rotate, relative sliding motion at the wafer-pad interface generates a friction force opposing that motion. This shear force is what mechanically dislodges the chemically softened reaction layer from the wafer surface \u2014 it is the direct mechanism of material removal, not merely a byproduct of it. The magnitude of this friction force is sensitive to the lubrication regime at the interface (discussed below), the abrasive particle concentration and hardness, and the real area of asperity contact between the pad surface texture and the wafer.<\/p>\n\n    <h3>Hertzian Contact at the Asperity Scale<\/h3>\n    <p>At the microscopic scale, the polishing pad surface is not perfectly smooth \u2014 it consists of a distribution of microscopic asperities (peaks) separated by valleys that channel slurry flow. The wafer does not contact the pad uniformly across its full area; rather, contact occurs at a population of discrete asperity tips, each behaving according to Hertzian elastic contact mechanics. The real contact area \u2014 the sum of all individual asperity contact zones \u2014 is typically only a small fraction of the nominal (apparent) wafer area, meaning the actual local pressure at each asperity contact point is substantially higher than the nominal pressure calculated by dividing carrier head force by wafer area. This asperity-scale pressure concentration is what makes CMP mechanically effective at relatively modest nominal pressures.<\/p>\n\n    <div class=\"jcmp-callout\">\n      <strong>Engineering implication:<\/strong> Because removal occurs at the asperity scale, pad surface texture, hardness, and conditioning state \u2014 which determine the asperity population density and height distribution \u2014 have a direct first-order effect on removal rate, independent of nominal pressure and velocity settings in the recipe.\n    <\/div>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"tribology\">\n    <h2>Tribology of the Slurry-Pad-Wafer System<\/h2>\n\n    <p>CMP is fundamentally a tribological process \u2014 the study of interacting surfaces in relative motion, including friction, wear, and lubrication. The lubrication regime at the wafer-pad interface, governed by slurry film thickness relative to pad asperity height, determines whether the process behaves more like a lubricated bearing (minimal mechanical contact) or a dry abrasive contact (maximal mechanical contact).<\/p>\n\n    <h3>The Stribeck Curve and CMP Lubrication Regimes<\/h3>\n    <p>The Stribeck curve, a classical tribology framework relating friction coefficient to a dimensionless lubrication parameter (combining viscosity, velocity, and pressure), maps directly onto CMP operating conditions:<\/p>\n\n    <div class=\"jcmp-grid\">\n      <div class=\"jcmp-card\">\n        <div class=\"jcmp-card-head\"><span class=\"jcmp-card-dot\"><\/span>Boundary Lubrication<\/div>\n        <p>At low velocity or high pressure, the slurry film is thin relative to pad asperity height, and direct solid-solid asperity contact dominates. Friction coefficient is relatively high and largely independent of velocity. Most production CMP processes \u2014 particularly metal CMP and STI CMP \u2014 operate predominantly in this regime, since direct mechanical contact is required for effective material removal.<\/p>\n      <\/div>\n      <div class=\"jcmp-card\">\n        <div class=\"jcmp-card-head\"><span class=\"jcmp-card-dot\"><\/span>Mixed Lubrication<\/div>\n        <p>At intermediate conditions, load is partially supported by the hydrodynamic slurry film and partially by direct asperity contact. Friction coefficient decreases as velocity increases. Many oxide CMP processes operate near this transition zone, and small changes in slurry viscosity or flow rate can shift the process between regimes, causing removal rate instability.<\/p>\n      <\/div>\n      <div class=\"jcmp-card\">\n        <div class=\"jcmp-card-head\"><span class=\"jcmp-card-dot\"><\/span>Hydrodynamic Lubrication<\/div>\n        <p>At high velocity or low pressure, a continuous slurry film fully separates the pad and wafer, supporting the entire load hydrodynamically. Direct asperity contact is minimal, and removal rate drops sharply since mechanical abrasion requires contact. This regime is generally avoided in production CMP recipes except for the gentlest final-polish steps.<\/p>\n      <\/div>\n      <div class=\"jcmp-card\">\n        <div class=\"jcmp-card-head\"><span class=\"jcmp-card-dot\"><\/span>Three-Body vs. Two-Body Abrasion<\/div>\n        <p>CMP predominantly operates as a three-body abrasion system: free abrasive particles roll and slide between the pad and wafer surfaces, rather than being fixed in the pad (two-body abrasion, as in fixed-abrasive pads). Three-body abrasion generally produces lower subsurface damage but is more sensitive to particle size distribution and concentration uniformity than two-body systems.<\/p>\n      <\/div>\n    <\/div>\n\n    <p>Understanding which lubrication regime a given recipe operates in is essential for predicting how the process will respond to slurry flow rate changes, pad wear over its service life, and platen temperature drift \u2014 all of which alter the effective viscosity and film thickness at the interface.<\/p>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"chemistry\">\n    <h2>Surface Chemistry: How Different Materials Are Removed<\/h2>\n\n    <p>The specific chemical reaction mechanism by which the slurry softens the wafer surface differs fundamentally by material system. Understanding these mechanisms explains why each CMP application requires a distinctly formulated slurry chemistry.<\/p>\n\n    <h3>Silicon Dioxide (Oxide) CMP Chemistry<\/h3>\n    <p>Oxide CMP proceeds primarily through a hydrolysis mechanism at high pH (typically pH 10\u201311). Hydroxide ions attack strained Si-O-Si bonds at the silica surface, forming silanol (Si-OH) groups that weaken the surface network and create a softened hydrated layer more easily removed by mechanical abrasion. The silica abrasive particles in the slurry are themselves chemically similar to the film being polished, contributing to a self-sharpening removal mechanism sometimes described as a &#8220;chemical tooth&#8221; effect.<\/p>\n\n    <h3>Copper CMP Chemistry<\/h3>\n    <p>Copper CMP relies on an oxidation-dissolution-passivation cycle. An oxidizer (commonly hydrogen peroxide) rapidly oxidizes the copper surface to form a thin copper oxide layer. This oxide layer is then mechanically removed by abrasive action, exposing fresh copper for the next oxidation cycle. Critically, a corrosion inhibitor \u2014 most commonly benzotriazole (BTA) \u2014 forms a passivating complex on the copper surface in non-contact (recessed, low-pressure) regions, protecting them from continued chemical attack while contact regions continue to be removed by the mechanical action. This selective passivation is precisely what enables copper CMP to achieve planarization without excessive dishing or galvanic corrosion in fine interconnect structures.<\/p>\n\n    <h3>Tungsten CMP Chemistry<\/h3>\n    <p>Tungsten CMP also uses an oxidation-based mechanism, typically with strong oxidizers (potassium iodate, hydrogen peroxide, or ferric nitrate-based systems) that form a tungsten oxide surface layer subsequently removed mechanically. Because tungsten is mechanically harder and chemically less reactive than copper, tungsten CMP generally requires more aggressive abrasive content and higher applied pressure than copper CMP, contributing to its position as one of the highest-force CMP applications in a standard process flow.<\/p>\n\n    <h3>Ceria-Based STI CMP Chemistry<\/h3>\n    <p>STI CMP&#8217;s requirement for extremely high oxide-to-nitride selectivity is achieved through the unique chemistry of cerium oxide (CeO<sub>2<\/sub>) abrasive particles, which form strong chemical bonds with the silicon dioxide surface through a ligand-exchange mechanism not significantly active with silicon nitride. This chemistry-driven selectivity \u2014 rather than purely mechanical hardness difference \u2014 is why ceria slurries achieve selectivity ratios that silica-based slurries cannot approach, regardless of mechanical parameter tuning.<\/p>\n\n    <div class=\"jcmp-read-more\">\n      <div class=\"jcmp-read-more-icon\">\u2192<\/div>\n      <span class=\"jcmp-read-more-text\">For a full breakdown of how these chemistries map to specific process steps across the fab flow: <a href=\"https:\/\/jeez-semicon.com\/ja\/blog\/CMP-Machine-Applications-STI-Copper-Interconnect-W-CMP-Advanced-Node-Processing\/\" target=\"_blank\" rel=\"noopener noreferrer\">CMP Machine Applications: STI, Copper Interconnect, W-CMP &amp; Advanced Node Processing<\/a><\/span>\n    <\/div>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"kinematics\">\n    <h2>Dual Rotation Kinematics and Uniformity<\/h2>\n\n    <p>A subtle but critical aspect of CMP machine design addresses a geometric problem inherent to rotational polishing: if a wafer were polished against a pad using pure rotation with no additional motion, points at different radii on the wafer would experience different linear sliding velocities relative to the pad \u2014 points near the wafer center would experience near-zero relative velocity, while points near the wafer edge would experience high relative velocity, since linear velocity scales with radius at constant angular velocity (v = \u03c9r).<\/p>\n\n    <p>By Preston&#8217;s Equation, this radial velocity gradient would translate directly into a removal rate gradient \u2014 heavy removal at the wafer edge and minimal removal at the wafer center \u2014 producing severe, uncorrectable bowl-shaped non-uniformity. CMP machines solve this problem through <strong>dual independent rotation<\/strong>: both the platen and the carrier head rotate simultaneously, typically at similar but not identical speeds. This dual-rotation kinematic scheme causes every point on the wafer surface to trace a complex, continuously varying relative path across the pad surface over time, averaging out the radial velocity gradient that pure single-axis rotation would produce.<\/p>\n\n    <p>The precise relationship between platen speed and carrier head speed \u2014 and any deliberate offset between them \u2014 is itself a tunable process parameter that process engineers use to fine-tune the residual removal rate uniformity profile, often in combination with multi-zone carrier head pressure adjustment, to achieve the sub-2% WIWNU specifications required at advanced process nodes.<\/p>\n\n    <div class=\"jcmp-read-more\">\n      <div class=\"jcmp-read-more-icon\">\u2192<\/div>\n      <span class=\"jcmp-read-more-text\">For a complete framework on diagnosing and correcting uniformity issues in production: <a href=\"https:\/\/jeez-semicon.com\/ja\/blog\/Optimizing-CMP-Machine-Performance-Removal-Rate-Within-Wafer-Uniformity-Defect-Control\/\" target=\"_blank\" rel=\"noopener noreferrer\">Optimizing CMP Machine Performance: Removal Rate, Within-Wafer Uniformity &amp; Defect Control<\/a><\/span>\n    <\/div>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"variables\">\n    <h2>Process Variable Summary<\/h2>\n\n    <p>The table below summarizes the primary mechanical and chemical process variables governing CMP machine behavior, their typical production ranges, and their first-order effect on process outcomes.<\/p>\n\n    <div class=\"jcmp-table-wrap\">\n      <table class=\"jcmp-table\">\n        <thead>\n          <tr>\n            <th>Variable<\/th>\n            <th>\u5178\u578b\u7684\u306a\u7bc4\u56f2<\/th>\n            <th>Primary Effect<\/th>\n          <\/tr>\n        <\/thead>\n        <tbody>\n          <tr>\n            <td><strong>Down-pressure<\/strong><\/td>\n            <td>0.5 \u2013 7 psi<\/td>\n            <td>Linear driver of removal rate per Preston&#8217;s Equation; affects pattern-density-dependent loading effect<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Platen \/ head rotation speed<\/strong><\/td>\n            <td>30 \u2013 120 rpm<\/td>\n            <td>Linear driver of relative velocity and removal rate; affects lubrication regime<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Slurry flow rate<\/strong><\/td>\n            <td>100 \u2013 300 mL\/min<\/td>\n            <td>Governs chemical reagent availability and abrasive replenishment at the interface<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Slurry pH<\/strong><\/td>\n            <td>2 \u2013 11 (application-dependent)<\/td>\n            <td>Controls chemical reaction rate, particle zeta potential, and material selectivity<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Pad temperature<\/strong><\/td>\n            <td>25 \u2013 45\u00b0C<\/td>\n            <td>Affects chemical reaction kinetics and slurry viscosity \/ lubrication regime<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Abrasive particle size<\/strong><\/td>\n            <td>50 \u2013 200 nm (primary)<\/td>\n            <td>Governs mechanical removal efficiency and scratch defect risk<\/td>\n          <\/tr>\n          <tr>\n            <td><strong>Pad conditioning frequency<\/strong><\/td>\n            <td>In-situ, continuous or cyclic<\/td>\n            <td>Maintains asperity population and pad surface texture for stable removal rate<\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n\n    <p>Each of these variables is in turn influenced by the physical and chemical specification of the polishing slurry and pad \u2014 meaning that consumable selection effectively sets the baseline process window before any recipe-level optimization begins.<\/p>\n\n    <div class=\"jcmp-cta-mid\">\n      <div class=\"jcmp-cta-mid-copy\">\n        <strong>Need slurry chemistry matched to your process physics?<\/strong>\n        <p>JEEZ formulates CMP slurries with controlled particle size distribution, zeta potential, and reaction kinetics engineered for predictable Preston coefficient behavior across oxide, copper, tungsten, and ceria-based STI applications.<\/p>\n      <\/div>\n      <a href=\"https:\/\/jeez-semicon.com\/ja\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"jcmp-btn-outline\">Contact JEEZ<\/a>\n    <\/div>\n\n    <p>This article is part of the JEEZ CMP knowledge base. For the complete equipment overview, components breakdown, manufacturer landscape, and consumable selection guidance, return to our pillar guide: <a href=\"https:\/\/jeez-semicon.com\/ja\/blog\/CMP-Machines-The-Complete-Guide-to-Chemical-Mechanical-Planarization-Equipment\/\" target=\"_blank\" rel=\"noopener noreferrer\">CMP Machines: The Complete Guide to Chemical Mechanical Planarization Equipment<\/a>.<\/p>\n  <\/section>\n\n  <hr class=\"jcmp-hr\">\n\n  <section id=\"faq\">\n    <h2>\u3088\u304f\u3042\u308b\u8cea\u554f<\/h2>\n\n    <div class=\"jcmp-faq-item\">\n      <div class=\"jcmp-faq-q\">What is Preston&#8217;s Equation in CMP?<\/div>\n      <div class=\"jcmp-faq-a\">\n        <p>Preston&#8217;s Equation (MRR = K<sub>p<\/sub> \u00d7 P \u00d7 V) is the foundational model describing CMP material removal rate as a linear function of applied pressure (P) and relative sliding velocity (V), scaled by an empirically determined Preston coefficient (K<sub>p<\/sub>) specific to the slurry, pad, and wafer material combination. While useful as a first-order model, real CMP processes deviate from strict linearity due to pattern density effects, edge effects, and lubrication regime transitions.<\/p>\n      <\/div>\n    <\/div>\n\n    <div class=\"jcmp-faq-item\">\n      <div class=\"jcmp-faq-q\">Why does CMP use both chemical and mechanical removal instead of just one?<\/div>\n      <div class=\"jcmp-faq-a\">\n        <p>Pure mechanical removal (grinding) causes excessive subsurface damage and cannot selectively planarize topography. Pure chemical removal (etching) cannot planarize because etch rate is largely insensitive to surface topology. CMP combines both: chemistry softens the surface to form an easily removed reaction layer, while mechanical abrasion removes that layer preferentially from high-pressure contact points \u2014 which correspond to raised topography \u2014 producing planarization with acceptable surface damage levels.<\/p>\n      <\/div>\n    <\/div>\n\n    <div class=\"jcmp-faq-item\">\n      <div class=\"jcmp-faq-q\">What is the loading effect in CMP?<\/div>\n      <div class=\"jcmp-faq-a\">\n        <p>The loading effect (or pattern density effect) describes how local removal rate on a patterned wafer depends on the fraction of the surrounding area occupied by raised features. Dense feature regions distribute the carrier head&#8217;s applied load across more total contact area, reducing the effective local pressure and slowing removal rate relative to isolated, low pattern-density features. This effect is not captured by the basic Preston model and is a major contributor to within-die non-uniformity.<\/p>\n      <\/div>\n    <\/div>\n\n    <div class=\"jcmp-faq-item\">\n      <div class=\"jcmp-faq-q\">Why do CMP machines rotate both the platen and the carrier head?<\/div>\n      <div class=\"jcmp-faq-a\">\n        <p>Dual independent rotation of both the platen and carrier head prevents the radial velocity gradient that would occur with single-axis rotation alone, where wafer edge points move faster relative to the pad than center points (since linear velocity scales with radius). Without dual rotation, this gradient would produce severe edge-to-center removal rate non-uniformity. Dual rotation kinematics average out this effect across the full wafer surface.<\/p>\n      <\/div>\n    <\/div>\n\n    <div class=\"jcmp-faq-item\">\n      <div class=\"jcmp-faq-q\">What role does benzotriazole (BTA) play in copper CMP?<\/div>\n      <div class=\"jcmp-faq-a\">\n        <p>Benzotriazole (BTA) is a corrosion inhibitor added to copper CMP slurries that forms a passivating complex on copper surfaces in low-pressure, non-contact regions, protecting them from continued chemical oxidation. In high-pressure contact regions, mechanical abrasion continuously disrupts this passivation layer, allowing removal to continue. This selective passivation mechanism is essential for achieving copper planarization without excessive dishing or surface corrosion.<\/p>\n      <\/div>\n    <\/div>\n\n  <\/section>\n\n<\/div>\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is Preston's Equation in CMP?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Preston's Equation (MRR = Kp \u00d7 P \u00d7 V) is the foundational model describing CMP material removal rate as a linear function of applied pressure (P) and relative sliding velocity (V), scaled by an empirically determined Preston coefficient (Kp) specific to the slurry, pad, and wafer material combination. Real CMP processes deviate from strict linearity due to pattern density effects, edge effects, and lubrication regime transitions.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Why does CMP use both chemical and mechanical removal instead of just one?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Pure mechanical removal causes excessive subsurface damage and cannot selectively planarize topography. Pure chemical removal cannot planarize because etch rate is largely insensitive to surface topology. CMP combines both: chemistry softens the surface to form an easily removed reaction layer, while mechanical abrasion removes that layer preferentially from high-pressure contact points corresponding to raised topography, producing planarization.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the loading effect in CMP?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The loading effect describes how local removal rate on a patterned wafer depends on the fraction of surrounding area occupied by raised features. Dense feature regions distribute load across more contact area, reducing effective local pressure and slowing removal rate relative to isolated low-density features. This is not captured by the basic Preston model and is a major cause of within-die non-uniformity.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Why do CMP machines rotate both the platen and the carrier head?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Dual independent rotation prevents the radial velocity gradient that single-axis rotation alone would create, since linear velocity scales with radius. Without dual rotation, this gradient produces severe edge-to-center removal rate non-uniformity. Dual rotation kinematics average out this effect across the wafer surface.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What role does benzotriazole (BTA) play in copper CMP?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"BTA is a corrosion inhibitor in copper CMP slurries that forms a passivating complex on copper surfaces in low-pressure, non-contact regions, protecting them from oxidation. In high-pressure contact regions, mechanical abrasion disrupts this passivation, allowing removal to continue. This selective passivation enables copper planarization without excessive dishing or corrosion.\"\n      }\n    }\n  ]\n}\n<\/script>","protected":false},"excerpt":{"rendered":"<p>Last updated: July 2026 14 min read JEEZ Technical Editorial Team \u2014 Jizhi Electronic Technology Co., Ltd. Understanding how a CMP machine works requires looking past the hardware and into  &#8230;<\/p>","protected":false},"author":1,"featured_media":2417,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[9,59],"tags":[],"class_list":["post-2415","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry"],"acf":[],"_links":{"self":[{"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/posts\/2415","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/comments?post=2415"}],"version-history":[{"count":2,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/posts\/2415\/revisions"}],"predecessor-version":[{"id":2418,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/posts\/2415\/revisions\/2418"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/media\/2417"}],"wp:attachment":[{"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/media?parent=2415"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/categories?post=2415"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ja\/wp-json\/wp\/v2\/tags?post=2415"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}