{"id":2514,"date":"2026-07-23T14:12:34","date_gmt":"2026-07-23T06:12:34","guid":{"rendered":"https:\/\/jeez-semicon.com\/?p=2514"},"modified":"2026-07-23T14:12:34","modified_gmt":"2026-07-23T06:12:34","slug":"highly-selective-vs-low-selective-tungsten-cmp-slurry-which-one-does-your-process-need","status":"publish","type":"post","link":"https:\/\/jeez-semicon.com\/ru\/blog\/highly-selective-vs-low-selective-tungsten-cmp-slurry-which-one-does-your-process-need\/","title":{"rendered":"Highly Selective vs. Low Selective Tungsten CMP Slurry: Which One Does Your Process Need?"},"content":{"rendered":"<style>\n.jcms-wrap{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Helvetica Neue',Arial,sans-serif;color:#1a2332;line-height:1.82;font-size:17px;max-width:900px;margin:0 auto;padding:0 2px}\n.jcms-wrap h1{font-size:clamp(26px,3.8vw,40px);font-weight:800;color:#0b1e3a;line-height:1.2;margin:0 0 20px;letter-spacing:-.025em}\n.jcms-wrap h2{font-size:clamp(19px,2.6vw,25px);font-weight:700;color:#0b1e3a;margin:52px 0 16px;padding-bottom:11px;border-bottom:2px solid #e1eaf5;line-height:1.3}\n.jcms-wrap h3{font-size:clamp(16px,2vw,19px);font-weight:700;color:#1a4f91;margin:30px 0 11px;line-height:1.3}\n.jcms-wrap h4{font-size:16px;font-weight:700;color:#0b1e3a;margin:20px 0 7px}\n.jcms-wrap p{margin:0 0 20px}\n.jcms-wrap ul,.jcms-wrap ol{margin:0 0 20px;padding-left:26px}\n.jcms-wrap li{margin-bottom:9px}\n.jcms-wrap strong{font-weight:700;color:#0b1e3a}\n.jcms-wrap sub{font-size:.78em;vertical-align:sub}\n.jcms-wrap sup{font-size:.78em;vertical-align:super}\n.jcms-wrap a{color:#1a4f91;text-decoration:underline;text-underline-offset:3px}\n.jcms-wrap a:hover{color:#0ea5a0}\n.jcms-meta{display:flex;flex-wrap:wrap;gap:16px;align-items:center;font-size:14px;color:#5b6b82;margin-bottom:28px;padding-bottom:18px;border-bottom:1px solid #e1eaf5}\n.jcms-meta-badge{background:#eef5ff;color:#1a4f91;font-size:12px;font-weight:700;padding:3px 11px;border-radius:4px;border:1px solid #c2d8fa;letter-spacing:.04em;text-transform:uppercase}\n.jcms-series-nav{background:#f0f6ff;border:1px solid #c2d8fa;border-radius:8px;padding:13px 17px;margin-bottom:28px;font-size:14px}\n.jcms-series-nav-label{font-size:11px;font-weight:800;letter-spacing:.1em;text-transform:uppercase;color:#5b6b82;margin-bottom:4px}\n.jcms-series-nav a{color:#1a4f91;font-weight:600;text-decoration:none}\n.jcms-series-nav a:hover{text-decoration:underline}\n.jcms-toc{background:#f5f8fd;border:1px solid #dde8f5;border-left:5px solid #1a4f91;border-radius:0 10px 10px 0;padding:24px 28px;margin:0 0 44px}\n.jcms-toc-title{font-size:13px;font-weight:800;letter-spacing:.1em;text-transform:uppercase;color:#1a4f91;margin:0 0 14px}\n.jcms-toc ol{margin:0;padding-left:20px;column-count:2;column-gap:26px}\n.jcms-toc li{margin-bottom:7px;break-inside:avoid;font-size:15px}\n.jcms-toc a{color:#1a4f91;font-weight:500;text-decoration:none}\n.jcms-toc a:hover{text-decoration:underline;color:#0ea5a0}\n.jcms-callout{border-radius:8px;padding:18px 22px;margin:26px 0;border-left:4px solid}\n.jcms-callout p,.jcms-callout ul{margin:0;font-size:15.5px}\n.jcms-callout ul{padding-left:20px;margin-top:8px}\n.jcms-callout-title{font-size:12px;font-weight:800;letter-spacing:.08em;text-transform:uppercase;margin:0 0 7px}\n.jcms-info{background:#eef5ff;border-color:#1a4f91}.jcms-info .jcms-callout-title{color:#1a4f91}.jcms-info p,.jcms-info ul{color:#2d4263}\n.jcms-note{background:#fff8e7;border-color:#d4870a}.jcms-note .jcms-callout-title{color:#944f00}.jcms-note p,.jcms-note ul{color:#4a3200}\n.jcms-teal{background:#e4f8f6;border-color:#0ea5a0}.jcms-teal .jcms-callout-title{color:#077570}.jcms-teal p,.jcms-teal ul{color:#0a4a47}\n.jcms-red{background:#fff0f0;border-color:#d93025}.jcms-red .jcms-callout-title{color:#a31e0e}.jcms-red p,.jcms-red ul{color:#4a100a}\n.jcms-deepdive{display:flex;align-items:center;gap:14px;background:#f0f6ff;border:1px solid #c2d8fa;border-radius:10px;padding:16px 20px;margin:28px 0;text-decoration:none;transition:background .18s,border-color .18s}\n.jcms-deepdive:hover{background:#e4effd;border-color:#1a4f91;text-decoration:none}\n.jcms-deepdive-icon{flex-shrink:0;width:42px;height:42px;background:#1a4f91;border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:19px}\n.jcms-deepdive-body{flex:1}.jcms-deepdive-label{font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:.1em;color:#5b6b82;margin:0 0 3px}\n.jcms-deepdive-title{font-size:15px;font-weight:700;color:#1a4f91;margin:0}\n.jcms-deepdive-arrow{font-size:19px;color:#1a4f91;flex-shrink:0}\n.jcms-stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:12px;margin:26px 0}\n.jcms-stat{background:#f5f8fd;border:1px solid #dde8f5;border-radius:10px;padding:18px 14px;text-align:center}\n.jcms-stat-num{font-size:26px;font-weight:800;color:#1a4f91;line-height:1;letter-spacing:-.02em}\n.jcms-stat-unit{font-size:12px;color:#5b6b82;margin-top:3px;font-weight:500}\n.jcms-stat-label{font-size:12px;color:#2d4263;margin-top:9px;font-weight:600;line-height:1.3}\n.jcms-tbl-wrap{overflow-x:auto;margin:26px 0;border-radius:10px;border:1px solid #dde8f5}\n.jcms-tbl{width:100%;border-collapse:collapse;font-size:14.5px}\n.jcms-tbl thead th{background:#1a4f91;color:#fff;padding:12px 15px;text-align:left;font-weight:700;font-size:13px;white-space:nowrap}\n.jcms-tbl thead th:first-child{border-radius:9px 0 0 0}\n.jcms-tbl thead th:last-child{border-radius:0 9px 0 0}\n.jcms-tbl tbody td{padding:11px 15px;border-bottom:1px solid #e8eef7;vertical-align:top;color:#1a2332}\n.jcms-tbl tbody tr:last-child td{border-bottom:none}\n.jcms-tbl tbody tr:nth-child(even) td{background:#f7fafd}\n.jcms-tbl tbody tr:hover td{background:#edf3fb}\n.jcms-tbl .jcms-tbl-cat{font-weight:700;color:#1a4f91}\n.jcms-compare{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:22px 0}\n.jcms-compare-card{border-radius:10px;padding:20px 22px;border:1px solid}\n.jcms-cmp-blue{background:#eef5ff;border-color:#c2d8fa}\n.jcms-cmp-teal{background:#e4f8f6;border-color:#9edbd7}\n.jcms-cmp-amber{background:#fff8e7;border-color:#f5c675}\n.jcms-compare-badge{display:inline-block;font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.07em;padding:3px 9px;border-radius:4px;margin-bottom:9px}\n.jcms-badge-blue{background:#1a4f91;color:#fff}\n.jcms-badge-teal{background:#0ea5a0;color:#fff}\n.jcms-badge-amber{background:#d4870a;color:#fff}\n.jcms-compare-card h4{margin:0 0 10px;color:#0b1e3a;font-size:15px}\n.jcms-compare-card ul{margin:0;padding-left:18px;font-size:14px;color:#2d4263}\n.jcms-compare-card li{margin-bottom:6px}\n.jcms-decision{background:#f5f8fd;border:1px solid #dde8f5;border-radius:10px;padding:22px 24px;margin:24px 0}\n.jcms-decision h4{margin:0 0 14px;color:#0b1e3a;font-size:16px}\n.jcms-decision-row{display:flex;align-items:flex-start;gap:12px;margin-bottom:12px;padding-bottom:12px;border-bottom:1px solid #e8eef7}\n.jcms-decision-row:last-child{margin-bottom:0;padding-bottom:0;border-bottom:none}\n.jcms-decision-q{font-weight:600;font-size:14px;color:#1a4f91;min-width:200px;flex-shrink:0}\n.jcms-decision-a{font-size:14px;color:#2d4263}\n.jcms-cta{background:linear-gradient(135deg,#0b1e3a 0%,#1a4f91 100%);border-radius:12px;padding:36px 38px;margin:50px 0 30px;text-align:center}\n.jcms-cta h3{color:#fff;font-size:21px;margin:0 0 11px;font-weight:700}\n.jcms-cta p{color:rgba(255,255,255,.85);margin:0 0 24px;font-size:16px;line-height:1.7}\n.jcms-cta-btn{display:inline-block;background:#0ea5a0;color:#fff;font-weight:700;font-size:16px;padding:13px 30px;border-radius:7px;text-decoration:none;margin:5px 7px;transition:background .18s}\n.jcms-cta-btn:hover{background:#0b8c88;color:#fff;text-decoration:none}\n.jcms-cta-btn-sec{background:transparent;border:2px solid rgba(255,255,255,.5);color:#fff}\n.jcms-cta-btn-sec:hover{background:rgba(255,255,255,.12);border-color:#fff;color:#fff}\n.jcms-related{margin:36px 0}\n.jcms-related-title{font-size:13px;font-weight:800;text-transform:uppercase;letter-spacing:.1em;color:#5b6b82;margin-bottom:13px}\n.jcms-related-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:10px}\n.jcms-related-item{background:#f5f8fd;border:1px solid #dde8f5;border-radius:8px;padding:13px 15px;text-decoration:none;display:block;transition:border-color .18s,background .18s}\n.jcms-related-item:hover{border-color:#1a4f91;background:#eef5ff;text-decoration:none}\n.jcms-related-item-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:#5b6b82;margin-bottom:4px}\n.jcms-related-item-title{font-size:13.5px;font-weight:700;color:#1a4f91;line-height:1.35}\n.jcms-sep{border:none;border-top:1px solid #e1eaf5;margin:44px 0}\n.jcms-checklist{list-style:none;padding:0;margin:0 0 20px}\n.jcms-checklist li{padding:9px 0 9px 34px;position:relative;border-bottom:1px solid #e8eef7;font-size:15px;color:#1a2332}\n.jcms-checklist li:last-child{border-bottom:none}\n.jcms-checklist li::before{content:\"\\2713\";position:absolute;left:0;top:10px;width:20px;height:20px;background:#1a4f91;color:#fff;border-radius:50%;font-size:11px;font-weight:700;text-align:center;line-height:20px}\n@media(max-width:640px){.jcms-toc ol{column-count:1}.jcms-compare{grid-template-columns:1fr}.jcms-cta{padding:26px 20px}.jcms-cta-btn{display:block;margin:6px 0}.jcms-decision-row{flex-direction:column}.jcms-decision-q{min-width:unset}}\n<\/style>\n<article class=\"jcms-wrap\" id=\"w-cmp-selectivity-guide\">\n\n\n<div class=\"jcms-meta\">\n  <span class=\"jcms-meta-badge\">Process Selection Guide<\/span>\n  <span>&#128197; Updated July 2026<\/span>\n  <span>&#128336; 17 min read<\/span>\n  <span>By JEEZ Engineering Team<\/span>\n<\/div>\n\n<div class=\"jcms-series-nav\">\n  <div class=\"jcms-series-nav-label\">&#128279; Part of the JEEZ Tungsten CMP Slurry Content Series<\/div>\n  <a href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-The-Complete-Technical-and-Procurement-Guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">&#8592; Complete Guide: Tungsten CMP Slurry &#8212; Technical &amp; Procurement Overview<\/a>\n<\/div>\n\n<p>The single most consequential formulation decision in tungsten CMP is choosing the right selectivity profile for each process step. Selectivity&#8202;&#8212;&#8202;the ratio of tungsten removal rate to oxide removal rate&#8202;&#8212;&#8202;governs the outcome of every critical dimension in the finished structure: contact recess (dishing), dielectric loss (erosion), surface planarity after clearing, and the process window within which all of these parameters can be simultaneously controlled.<\/p>\n\n<p>Despite its central importance, the selection between highly selective and low selective (non-selective) slurry formulations is poorly understood outside of specialist CMP engineering roles. Slurry data sheets present selectivity as a single number, but that number only has meaning in the context of the process step it is intended for, the pattern geometry of the device it is applied to, and the performance trade-offs that a given selectivity ratio implies. This guide provides the framework for making this decision correctly, with specific guidance for logic, 3D NAND, and DRAM applications.<\/p>\n\n<nav class=\"jcms-toc\">\n  <p class=\"jcms-toc-title\">\u041e\u0433\u043b\u0430\u0432\u043b\u0435\u043d\u0438\u0435<\/p>\n  <ol>\n    <li><a href=\"#c1-definition\">What Is Selectivity in Tungsten CMP?<\/a><\/li>\n    <li><a href=\"#c1-highly-selective\">Highly Selective Slurry: Mechanism and Properties<\/a><\/li>\n    <li><a href=\"#c1-low-selective\">Low Selective (Non-Selective) Slurry: Mechanism and Properties<\/a><\/li>\n    <li><a href=\"#c1-framework\">Decision Framework: Which to Use at Each Step<\/a><\/li>\n    <li><a href=\"#c1-logic\">Logic Applications: Contact and Gate CMP<\/a><\/li>\n    <li><a href=\"#c1-nand\">3D NAND Applications: Wordline and Staircase CMP<\/a><\/li>\n    <li><a href=\"#c1-dram\">DRAM Applications: Buried Wordline and SNC<\/a><\/li>\n    <li><a href=\"#c1-overpolish\">Overpolish Strategy and Selectivity Interaction<\/a><\/li>\n    <li><a href=\"#c1-process-window\">Process Window: How Conditions Modify Effective Selectivity<\/a><\/li>\n    <li><a href=\"#c1-mistakes\">Common Mistakes in Selectivity Selection<\/a><\/li>\n  <\/ol>\n<\/nav>\n\n<section id=\"c1-definition\">\n<h2>1. What Is Selectivity in Tungsten CMP?<\/h2>\n<p>In tungsten CMP, selectivity is defined as the ratio of the tungsten material removal rate (W MRR) to the silicon dioxide dielectric material removal rate (Oxide MRR), measured under identical polishing conditions on blanket film test wafers:<\/p>\n\n<div class=\"jcms-callout jcms-info\">\n  <p class=\"jcms-callout-title\">&#128161; Selectivity Definition<\/p>\n  <p><strong>Selectivity = W MRR (&#197;\/min) &#247; Oxide MRR (&#197;\/min)<\/strong><br><br>\n  A selectivity of 50:1 means tungsten is removed 50 times faster than oxide under the same polishing conditions. A selectivity of 1:1 means both materials are removed at equal rates.<\/p>\n<\/div>\n\n<p>This ratio is a formulation property&#8202;&#8212;&#8202;determined primarily by the slurry&#8217;s oxidizer concentration, pH, abrasive type, and the presence or absence of selective inhibitor additives&#8202;&#8212;&#8202;but it is also a process variable that shifts with downforce, rotation speed, temperature, and pad condition. A selectivity value on a data sheet applies only at the test conditions stated; understanding how selectivity changes with process parameters is as important as knowing the nominal value.<\/p>\n\n<p>Selectivity values encountered in commercial tungsten CMP slurries span a wide range:<\/p>\n<ul>\n  <li><strong>Hyper-selective:<\/strong> W:Oxide &gt;100:1 &#8212; oxide MRR so low it is essentially negligible during Step 1<\/li>\n  <li><strong>Highly selective:<\/strong> W:Oxide 25:1&#8211;100:1 &#8212; standard Step 1 bulk removal range<\/li>\n  <li><strong>Moderately selective:<\/strong> W:Oxide 5:1&#8211;25:1 &#8212; endpoint clearing or transitional step applications<\/li>\n  <li><strong>Low selective (non-selective):<\/strong> W:Oxide 0.5:1&#8211;3:1 &#8212; Step 2 buff and barrier step range<\/li>\n<\/ul>\n<\/section>\n\n<section id=\"c1-highly-selective\">\n<h2>2. Highly Selective Slurry: Mechanism, Properties, and Trade-offs<\/h2>\n<p>A highly selective tungsten CMP slurry achieves its elevated W:Oxide ratio through formulation design that accelerates tungsten oxidation and removal while simultaneously protecting the oxide surface from significant abrasive attack. The primary mechanisms are:<\/p>\n\n<p><strong>Elevated oxidizer and catalyst activity toward tungsten:<\/strong> Higher H<sub>2<\/sub>O<sub>2<\/sub> concentration (within the optimal window) and well-tuned Fe<sup>3+<\/sup> catalyst loading ensure rapid WO<sub>3<\/sub> formation at the tungsten surface, maintaining a high tungsten MRR.<\/p>\n\n<p><strong>Selective surface passivation of oxide:<\/strong> Some highly selective formulations incorporate additive molecules (typically organic amines, polyelectrolytes, or surfactants) that adsorb preferentially onto the oxide surface and reduce the contact probability between abrasive particles and the dielectric, lowering the effective oxide MRR without significantly affecting tungsten removal. This is distinct from simply using a softer or smaller abrasive&#8202;&#8212;&#8202;the selective passivation mechanism specifically targets the oxide-abrasive interaction.<\/p>\n\n<p><strong>pH optimization for tungsten vs. oxide abrasion balance:<\/strong> At lower pH within the acidic W CMP window, the surface chemistry of both the abrasive and the oxide surface can be tuned to favor mechanical removal of the softer WO<sub>3<\/sub> while leaving the harder SiO<sub>2<\/sub> dielectric relatively unaffected.<\/p>\n\n<div class=\"jcms-compare\">\n  <div class=\"jcms-compare-card jcms-cmp-blue\">\n    <span class=\"jcms-compare-badge jcms-badge-blue\">Advantages<\/span>\n    <h4>Why to Use a Highly Selective Slurry<\/h4>\n    <ul>\n      <li>Maximizes tungsten MRR for short process times and high tool throughput<\/li>\n      <li>Protects the inter-layer dielectric from loss during bulk overburden removal<\/li>\n      <li>Creates a self-limiting process at the W\/Oxide interface&#8202;&#8212;&#8202;natural process-stop<\/li>\n      <li>Reduces total dielectric loss even with extended overpolish times<\/li>\n      <li>Enables wider process window for endpoint detection tolerance<\/li>\n    <\/ul>\n  <\/div>\n  <div class=\"jcms-compare-card jcms-cmp-amber\">\n    <span class=\"jcms-compare-badge jcms-badge-amber\">Trade-offs<\/span>\n    <h4>Limitations of High Selectivity<\/h4>\n    <ul>\n      <li>Generates dishing in isolated and wide tungsten features (&gt;2&#8202;&#956;m)<\/li>\n      <li>Dishing accumulates with every second of overpolish in Step 1<\/li>\n      <li>Does not correct topographic non-uniformity left by the CVD deposition step<\/li>\n      <li>Requires a Step 2 buff to correct dishing and clear the Ti\/TiN liner<\/li>\n      <li>Highly selective formulations with selective passivation additives may have higher cost<\/li>\n    <\/ul>\n  <\/div>\n<\/div>\n<\/section>\n\n<section id=\"c1-low-selective\">\n<h2>3. Low Selective (Non-Selective) Slurry: Mechanism, Properties, and Trade-offs<\/h2>\n<p>A low selective or non-selective tungsten CMP slurry removes tungsten and oxide at comparable rates, typically within a 3:1 ratio or better (some formulations achieve near-unity 1:1 selectivity). This behavior results from formulations that do not include selective passivation additives for oxide, use abrasive types and sizes that effectively remove both tungsten oxide and silicon dioxide, and operate at pH conditions where both materials are susceptible to mechanical abrasion at similar rates.<\/p>\n\n<div class=\"jcms-compare\">\n  <div class=\"jcms-compare-card jcms-cmp-teal\">\n    <span class=\"jcms-compare-badge jcms-badge-teal\">Advantages<\/span>\n    <h4>Why to Use a Low Selective Slurry<\/h4>\n    <ul>\n      <li>Removes W and oxide at comparable rates&#8202;&#8212;&#8202;planarizes topographic variation uniformly<\/li>\n      <li>Limits dishing in wide features by removing oxide at feature edges while removing W at the center<\/li>\n      <li>Effective at removing Ti\/TiN barrier liner materials (with appropriate abrasive)<\/li>\n      <li>Improves global wafer-level planarity after Step 1<\/li>\n      <li>Reduces surface roughness and microscratch count when properly formulated<\/li>\n    <\/ul>\n  <\/div>\n  <div class=\"jcms-compare-card jcms-cmp-amber\">\n    <span class=\"jcms-compare-badge jcms-badge-amber\">Trade-offs<\/span>\n    <h4>Limitations of Low Selectivity<\/h4>\n    <ul>\n      <li>Higher oxide MRR increases erosion risk in dense W array regions during overpolish<\/li>\n      <li>Lower W MRR than Step 1 slurry&#8202;&#8212;&#8202;not efficient for bulk overburden removal<\/li>\n      <li>Requires tight overpolish time control to stay within erosion specification<\/li>\n      <li>Must be carefully managed in transition zone between dense array and isolated features<\/li>\n    <\/ul>\n  <\/div>\n<\/div>\n<\/section>\n\n<section id=\"c1-framework\">\n<h2>4. Decision Framework: Which to Use at Each Step<\/h2>\n\n<div class=\"jcms-decision\">\n  <h4>&#128736;&#65039; Process Step Selection Guide<\/h4>\n  <div class=\"jcms-decision-row\">\n    <div class=\"jcms-decision-q\">Need to remove thick W overburden (100&#8211;300&#8202;nm) efficiently?<\/div>\n    <div class=\"jcms-decision-a\">&#10145; Use <strong>highly selective slurry<\/strong> (W:Oxide &gt;25:1). Maximize throughput, protect ILD, allow endpoint detection at W\/Oxide interface.<\/div>\n  <\/div>\n  <div class=\"jcms-decision-row\">\n    <div class=\"jcms-decision-q\">Need to clear Ti\/TiN liner after W bulk removal?<\/div>\n    <div class=\"jcms-decision-a\">&#10145; Use <strong>low selective or non-selective slurry<\/strong> with alumina or fine silica abrasive (W:Oxide ~1:1&#8211;3:1). Clear liner without building excessive dielectric erosion.<\/div>\n  <\/div>\n  <div class=\"jcms-decision-row\">\n    <div class=\"jcms-decision-q\">Have dishing in isolated features from Step 1 that needs correction?<\/div>\n    <div class=\"jcms-decision-a\">&#10145; Use <strong>low selective slurry<\/strong> in Step 2 to re-planarize topography. The comparable W and oxide MRR allows the surface to level out. Monitor erosion in dense arrays.<\/div>\n  <\/div>\n  <div class=\"jcms-decision-row\">\n    <div class=\"jcms-decision-q\">Processing a 3D NAND wordline stack (&gt;150 layers)?<\/div>\n    <div class=\"jcms-decision-a\">&#10145; Use <strong>moderate selectivity slurry<\/strong> (5:1&#8211;25:1) with attention to downforce to manage stack stress. Full hyper-selectivity may not be needed or desired.<\/div>\n  <\/div>\n  <div class=\"jcms-decision-row\">\n    <div class=\"jcms-decision-q\">Processing DRAM buried wordline with tight recess control (&#177;5&#8202;&#197;)?<\/div>\n    <div class=\"jcms-decision-a\">&#10145; Use <strong>highly selective slurry<\/strong> with strong endpoint detection. Any overpolish in a low-selectivity step would blow the recess budget within seconds at typical MRRs.<\/div>\n  <\/div>\n<\/div>\n\n<a class=\"jcms-deepdive\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Dishing-Erosion-and-Defects-in-Tungsten-CMP-Root-Causes-and-Slurry-Level-Solutions\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n  <div class=\"jcms-deepdive-icon\">&#128301;<\/div>\n  <div class=\"jcms-deepdive-body\">\n    <p class=\"jcms-deepdive-label\">Related Guide &#8212; Defect Engineering<\/p>\n    <p class=\"jcms-deepdive-title\">Dishing, Erosion, and Defects in Tungsten CMP: Root Causes and Slurry-Level Solutions<\/p>\n  <\/div>\n  <span class=\"jcms-deepdive-arrow\">&#8594;<\/span>\n<\/a>\n<\/section>\n\n<section id=\"c1-logic\">\n<h2>5. Logic Applications: Contact and Gate CMP<\/h2>\n<p>At sub-14&#8202;nm logic nodes, the combination of very small feature sizes, extreme dishing tolerances, and tight dielectric loss budgets makes selectivity management one of the most precision-sensitive aspects of tungsten CMP process development.<\/p>\n\n<p><strong>MOL Contact CMP:<\/strong> Contacts at sub-5&#8202;nm nodes are below 15&#8202;nm in diameter, but dishing and erosion tolerances are in the sub-50&#8202;&#197; range because any concavity in the contact surface directly increases electrical contact resistance at the transistor terminal. A two-step process with highly selective Step&#8202;1 (W:Oxide &gt;50:1) and a very brief, carefully timed non-selective Step&#8202;2 (limited erosion budget) is the standard approach. Step&#8202;1 overpolish time is minimized to limit dishing: with contact diameters below 15&#8202;nm, even isolated features (essentially every contact in a logic context) do not generate significant pad-deflection dishing, but the overpolish rate is still the primary dishing accumulation mechanism.<\/p>\n\n<p><strong>RMG Gate CMP:<\/strong> Replacement metal gate polishing requires high selectivity in the clearing step to protect the high-k dielectric and surrounding ILD from removal, followed by a buff step tuned for low surface roughness and minimal residue. The gate height uniformity budget (which maps to transistor V<sub>th<\/sub> spread) may require even tighter endpoint control than the contact CMP step.<\/p>\n\n<p>For logic applications at leading-edge nodes, colloidal silica abrasive&#8202;&#8212;&#8202;with its narrow PSD and lower scratch risk&#8202;&#8212;&#8202;is strongly preferred over fumed silica, because the sub-50&#8202;&#197; dishing and &lt;10 defects\/cm<sup>2<\/sup> post-clean targets leave essentially zero tolerance for abrasive-induced scratch events.<\/p>\n<\/section>\n\n<section id=\"c1-nand\">\n<h2>6. 3D NAND Applications: Wordline and Staircase CMP<\/h2>\n<p>3D NAND tungsten CMP presents a unique selectivity challenge because the structure being polished is not a simple metal-in-dielectric pattern but a multi-layer stack of alternating oxide and tungsten films, each potentially several nanometers thick, stacked to heights of 5&#8202;&#956;m or more. The CMP process must planarize this structure without causing delamination between the oxide\/tungsten interfaces under the applied mechanical stress.<\/p>\n\n<p>Selectivity in the 3D NAND context affects two somewhat different objectives:<\/p>\n\n<p><strong>Wordline tungsten removal:<\/strong> The top surface of the deposited tungsten must be cleared uniformly from both the dense array region and the stepped staircase contact region, which have very different pattern densities. A moderately selective slurry (10:1&#8211;25:1) balances the competing requirements of efficient tungsten clearing in the array with adequate oxide protection at the staircase contacts where the oxide surface is exposed at different wordline levels.<\/p>\n\n<p><strong>Stack stress management:<\/strong> Very high downforce in combination with high-selectivity slurry formulations that drive high MRR can generate mechanical stress on the 3D NAND stack that risks delamination at the oxide\/nitride and oxide\/tungsten interfaces. 3D NAND-specific slurry formulations typically target lower downforce operation with enhanced chemical contribution to MRR, achieving the needed tungsten removal rate through chemistry rather than pressure&#8202;&#8212;&#8202;reducing the risk of mechanical stack damage.<\/p>\n<\/section>\n\n<section id=\"c1-dram\">\n<h2>7. DRAM Applications: Buried Wordline and Storage Node Contact<\/h2>\n<p>DRAM tungsten CMP applications require a different balance of selectivity requirements than logic or NAND, driven by the specific geometry and tolerance stack of DRAM cell structures.<\/p>\n\n<p><strong>Buried Wordline (bWL) CMP:<\/strong> After tungsten fills the narrow bWL trenches (recessed below the active silicon surface), the overburden must be cleared and the tungsten must be recessed to a precisely controlled depth. This depth tolerance is extremely tight&#8202;&#8212;&#8202;&#177;5&#8202;&#197; in advanced DRAM&#8202;&#8212;&#8202;because the wordline recess determines the gate-to-active overlap and thus the cell&#8217;s threshold voltage and read\/write margin. A highly selective Step&#8202;1 slurry with strong endpoint detection is required; any low-selectivity buff step must be extremely brief and tightly timed to avoid additional recess beyond specification.<\/p>\n\n<p><strong>Storage Node Contact (SNC) CMP:<\/strong> The storage node contact connects the bitline to the capacitor electrode through a high aspect ratio via filled with tungsten. SNC CMP is primarily a surface quality and contamination control step&#8202;&#8212;&#8202;the contact must be flat, clean, and free of metallic contamination that could increase capacitor leakage. A moderate selectivity slurry with excellent defect performance (particularly Fe and other metallic impurity control) is appropriate, as the electrical sensitivity of the capacitor to surface metallic contamination is higher than for logic contacts.<\/p>\n<\/section>\n\n<section id=\"c1-overpolish\">\n<h2>8. Overpolish Strategy and Selectivity Interaction<\/h2>\n<p>Overpolish&#8202;&#8212;&#8202;the additional polish time beyond the nominal endpoint of tungsten clearance&#8202;&#8212;&#8202;is an unavoidable component of production CMP processes because within-wafer non-uniformity means the fastest-polishing region of the wafer clears before the slowest. The amount of overpolish needed is set by the WIWNU of Step&#8202;1; tighter WIWNU requires less overpolish, which in turn reduces both dishing (in Step&#8202;1) and the need for a long Step&#8202;2 buff.<\/p>\n\n<p>The relationship between selectivity and overpolish outcomes is straightforward:<\/p>\n<ul>\n  <li>For every 10 seconds of overpolish at 2,000&#8202;&#197;\/min W MRR with a 50:1 selective slurry, approximately 330&#8202;&#197; of tungsten recess accumulates in a feature where the pad can contact the tungsten center&#8202;&#8212;&#8202;a significant fraction of the dishing budget at advanced nodes.<\/li>\n  <li>For every 10 seconds of overpolish in Step&#8202;2 at 500&#8202;&#197;\/min oxide MRR with a 2:1 selective slurry, approximately 83&#8202;&#197; of oxide erosion accumulates in high-density array regions&#8202;&#8212;&#8202;a tolerable rate if Step&#8202;2 time is carefully controlled.<\/li>\n<\/ul>\n\n<p>These calculations make clear why the two-step overpolish allocation&#8202;&#8212;&#8202;how much time in Step&#8202;1 vs. Step&#8202;2&#8202;&#8212;&#8202;is the primary lever for balancing dishing and erosion simultaneously, and why improving Step&#8202;1 WIWNU (to reduce required overpolish) has compound benefits on both defect metrics.<\/p>\n<\/section>\n\n<section id=\"c1-process-window\">\n<h2>9. Process Window: How Conditions Modify Effective Selectivity<\/h2>\n<p>The selectivity value on a slurry data sheet is measured at a specific set of process conditions. In production, process conditions vary within a tool-to-tool and lot-to-lot range, and selectivity varies with them. Understanding these dependencies prevents misinterpretation of qualification data.<\/p>\n\n<div class=\"jcms-tbl-wrap\">\n  <table class=\"jcms-tbl\">\n    <thead>\n      <tr><th>Process Variable<\/th><th>Effect on W MRR<\/th><th>Effect on Oxide MRR<\/th><th>Net Effect on Selectivity<\/th><\/tr>\n    <\/thead>\n    <tbody>\n      <tr><td class=\"jcms-tbl-cat\">&#8593; Downforce<\/td><td>Increases (more abrasive contact)<\/td><td>Increases (more abrasive contact)<\/td><td>Typically decreases selectivity (oxide MRR increases faster)<\/td><\/tr>\n      <tr><td class=\"jcms-tbl-cat\">&#8593; Platen\/Head speed<\/td><td>Increases (higher abrasive velocity)<\/td><td>Increases (higher abrasive velocity)<\/td><td>Roughly neutral; specific behavior depends on slurry<\/td><\/tr>\n      <tr><td class=\"jcms-tbl-cat\">&#8593; H<sub>2<\/sub>O<sub>2<\/sub> concentration<\/td><td>Increases (more oxidation of W)<\/td><td>Minimal change (oxide not chemically oxidized)<\/td><td>Increases selectivity<\/td><\/tr>\n      <tr><td class=\"jcms-tbl-cat\">&#8593; Temperature<\/td><td>Increases (faster H<sub>2<\/sub>O<sub>2<\/sub> kinetics)<\/td><td>Small increase (thermal softening of SiO<sub>2<\/sub>)<\/td><td>Typically increases selectivity modestly<\/td><\/tr>\n      <tr><td class=\"jcms-tbl-cat\">&#8593; Abrasive concentration<\/td><td>Increases (more mechanical removal of WO<sub>3<\/sub>)<\/td><td>Increases (more mechanical removal of SiO<sub>2<\/sub>)<\/td><td>Complex; depends on relative hardness and surface chemistry<\/td><\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>The most critical practical implication: increasing downforce&#8202;&#8212;&#8202;a tempting lever for improving throughput on a low-MRR process&#8202;&#8212;&#8202;tends to reduce effective selectivity, increasing oxide erosion risk in the dense array regions. If throughput improvement is needed, increasing downforce on a Step&#8202;1 process should be accompanied by a re-characterization of dishing and erosion performance, not just W MRR.<\/p>\n\n<a class=\"jcms-deepdive\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-Chemistry-and-Mechanism-How-Oxidizers-and-Abrasives-Work-Together\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n  <div class=\"jcms-deepdive-icon\">&#128300;<\/div>\n  <div class=\"jcms-deepdive-body\">\n    <p class=\"jcms-deepdive-label\">Related Guide &#8212; Chemistry Background<\/p>\n    <p class=\"jcms-deepdive-title\">Tungsten CMP Slurry Chemistry and Mechanism: How Oxidizers and Abrasives Work Together<\/p>\n  <\/div>\n  <span class=\"jcms-deepdive-arrow\">&#8594;<\/span>\n<\/a>\n<\/section>\n\n<section id=\"c1-mistakes\">\n<h2>10. Common Mistakes in Selectivity Selection<\/h2>\n<p>The following errors in selectivity selection or application are observed frequently in process development and production CMP engineering:<\/p>\n\n<p><strong>Using Step&#8202;1 selectivity to evaluate Step&#8202;2 performance:<\/strong> Requesting selectivity data on a buff slurry and comparing it to a bulk removal slurry&#8217;s selectivity, as if a higher selectivity is always better, misses the purpose of the buff step. Low selectivity in Step&#8202;2 is a feature, not a deficiency&#8202;&#8212;&#8202;it is what enables topography correction and surface planarization.<\/p>\n\n<p><strong>Running Step&#8202;1 overpolish with Step&#8202;2 selectivity:<\/strong> Using a non-selective slurry on Platen&#8202;1 in a misguided attempt to eliminate the buff step entirely is a common process simplification that typically produces unacceptable levels of array erosion. The two steps have different objectives; the step structure exists for a reason.<\/p>\n\n<p><strong>Assuming high selectivity eliminates dishing:<\/strong> Very high selectivity (&gt;100:1) does not prevent dishing&#8202;&#8212;&#8202;it eliminates the planarizing effect that lower selectivity would provide. Dishing in Step&#8202;1 is primarily a function of overpolish time and feature geometry, not simply selectivity. High selectivity makes dishing worse by continuing to remove tungsten without removing the surrounding oxide to compensate.<\/p>\n\n<p><strong>Using a single selectivity number for process design without verifying temperature and downforce dependence:<\/strong> A 50:1 selectivity number measured at 2&#8202;psi and 25&#176;C may be 20:1 or 30:1 at the actual production downforce and slurry temperature at your facility. Always request selectivity characterization across your production operating window, not just at a single test condition.<\/p>\n\n<a class=\"jcms-deepdive\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-for-Advanced-Nodes-Logic-3D-NAND-and-DRAM-Requirements\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n  <div class=\"jcms-deepdive-icon\">&#128736;&#65039;<\/div>\n  <div class=\"jcms-deepdive-body\">\n    <p class=\"jcms-deepdive-label\">Related Guide &#8212; Application Requirements<\/p>\n    <p class=\"jcms-deepdive-title\">Tungsten CMP Slurry for Advanced Nodes: Logic, 3D NAND, and DRAM Requirements<\/p>\n  <\/div>\n  <span class=\"jcms-deepdive-arrow\">&#8594;<\/span>\n<\/a>\n<\/section>\n\n<hr class=\"jcms-sep\">\n<div style=\"background:#f5f8fd;border-radius:10px;padding:24px 28px;margin:36px 0\">\n  <h3 style=\"margin-top:0;color:#0b1e3a\">Summary<\/h3>\n  <p>Selectivity is not a feature to maximize in every context&#8202;&#8212;&#8202;it is a tool to match to the objective of each process step. Highly selective slurries belong in Step&#8202;1 for efficient bulk tungsten removal with dielectric protection. Low selective (non-selective) slurries belong in Step&#8202;2 for topography correction, liner removal, and surface quality improvement. The two-step process architecture manages the inherent dishing&#8202;&#8212;&#8202;erosion trade-off by assigning each selectivity class to the phase where its benefits dominate. Effective selectivity also shifts with downforce and temperature&#8202;&#8212;&#8202;characterize it across your full production operating window, not just at a single data sheet condition.<\/p>\n<\/div>\n\n<div class=\"jcms-cta\">\n  <h3>Match the Right JEEZ Slurry to Your Process Step<\/h3>\n  <p>JEEZ offers both high-selectivity (W-CMP-HS Series) and low-selectivity (W-CMP-LS Series) tungsten CMP slurries, with selectivity characterization data available across standard process condition ranges. Contact us to match the right formulation to your application.<\/p>\n  <a class=\"jcms-cta-btn\" href=\"https:\/\/jeez-semicon.com\/ru\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\">Request Selectivity Data &amp; Sample<\/a>\n  <a class=\"jcms-cta-btn jcms-cta-btn-sec\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-The-Complete-Technical-and-Procurement-Guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Read the Complete W CMP Guide<\/a>\n<\/div>\n\n<div class=\"jcms-related\">\n  <p class=\"jcms-related-title\">&#128279; More in the Tungsten CMP Series<\/p>\n  <div class=\"jcms-related-grid\">\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-The-Complete-Technical-and-Procurement-Guide\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Complete Guide<\/p><p class=\"jcms-related-item-title\">Tungsten CMP Slurry: Technical &amp; Procurement Overview<\/p><\/a>\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-Chemistry-and-Mechanism-How-Oxidizers-and-Abrasives-Work-Together\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Chemistry Guide<\/p><p class=\"jcms-related-item-title\">Tungsten CMP Slurry Chemistry and Mechanism<\/p><\/a>\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Dishing-Erosion-and-Defects-in-Tungsten-CMP-Root-Causes-and-Slurry-Level-Solutions\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Defect Engineering<\/p><p class=\"jcms-related-item-title\">Dishing, Erosion, and Defects in Tungsten CMP<\/p><\/a>\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-for-Advanced-Nodes-Logic-3D-NAND-and-DRAM-Requirements\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Application Guide<\/p><p class=\"jcms-related-item-title\">Tungsten CMP Slurry for Advanced Nodes<\/p><\/a>\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-Suppliers-Compared-Entegris-DuPont-Merck-EMD-and-When-to-Consider-Alternatives\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Supplier Guide<\/p><p class=\"jcms-related-item-title\">Tungsten CMP Slurry Suppliers Compared<\/p><\/a>\n    <a class=\"jcms-related-item\" href=\"https:\/\/jeez-semicon.com\/ru\/blog\/Tungsten-CMP-Slurry-Market-2026-Size-Growth-Drivers-and-Global-Outlook\/\" target=\"_blank\" rel=\"noopener noreferrer\"><p class=\"jcms-related-item-label\">Market Analysis<\/p><p class=\"jcms-related-item-title\">Tungsten CMP Slurry Market 2026<\/p><\/a>\n  <\/div>\n<\/div>\n<\/article>","protected":false},"excerpt":{"rendered":"<p>Process Selection Guide &#128197; Updated July 2026 &#128336; 17 min read By JEEZ Engineering Team &#128279; Part of the JEEZ Tungsten CMP Slurry Content Series &#8592; Complete Guide: Tungsten CMP  &#8230;<\/p>","protected":false},"author":1,"featured_media":2528,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[9,59],"tags":[],"class_list":["post-2514","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\/2514","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=2514"}],"version-history":[{"count":2,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts\/2514\/revisions"}],"predecessor-version":[{"id":2516,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/posts\/2514\/revisions\/2516"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/media\/2528"}],"wp:attachment":[{"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/media?parent=2514"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/categories?post=2514"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jeez-semicon.com\/ru\/wp-json\/wp\/v2\/tags?post=2514"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}