{"id":1173,"date":"2025-12-19T10:01:00","date_gmt":"2025-12-19T01:01:00","guid":{"rendered":"https:\/\/rtlearner.com\/?p=1173"},"modified":"2025-12-19T10:03:38","modified_gmt":"2025-12-19T01:03:38","slug":"rram-6-oxram-cbram","status":"publish","type":"post","link":"https:\/\/rtlearner.com\/en\/rram-6-oxram-cbram\/","title":{"rendered":"About RRAM \u2013 6 Filament Materials: OxRAM vs. CBRAM"},"content":{"rendered":"<p>So far, we've been talking about \"when voltage is applied, a filament is formed.\" However, depending on what the filament is made of, RRAM can be broadly divided into two types.<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li><strong>OxRAM (Oxide RRAM):<\/strong> The way defects called oxygen vacancies gather to form filaments.<\/li>\n\n\n\n<li><strong>Conductive Bridge RAM (CBRAM):<\/strong> A method in which \u2018real metals\u2019 such as copper (Cu) or silver (Ag) move to build a bridge.<\/li>\n<\/ol>\n\n\n\n<p>These two devices differ significantly, from the electrodes they use to their operating characteristics. Understanding where your desired device falls into is the first step in device design.<\/p>\n\n\n<style>.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-content-wrap{padding-top:var(--global-kb-spacing-sm, 1.5rem);padding-right:var(--global-kb-spacing-sm, 1.5rem);padding-bottom:var(--global-kb-spacing-sm, 1.5rem);padding-left:var(--global-kb-spacing-sm, 1.5rem);box-shadow:0px 0px 14px 0px rgba(0, 0, 0, 0.2);}.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-contents-title-wrap{padding-top:0px;padding-right:0px;padding-bottom:0px;padding-left:0px;}.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-contents-title{font-weight:regular;font-style:normal;}.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-content-wrap .kb-table-of-content-list{font-weight:regular;font-style:normal;margin-top:var(--global-kb-spacing-sm, 1.5rem);margin-right:0px;margin-bottom:0px;margin-left:0px;}@media all and (max-width: 767px){.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-contents-title{font-size:var(--global-kb-font-size-md, 1.25rem);}.kb-table-of-content-nav.kb-table-of-content-id1173_fa065e-8d .kb-table-of-content-wrap .kb-table-of-content-list{font-size:var(--global-kb-font-size-sm, 0.9rem);}}<\/style>\n\n<style>.kadence-column1173_a796a3-fb > .kt-inside-inner-col{box-shadow:inset 0px 0px 14px 0px rgba(0, 0, 0, 0.2);border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;}.kadence-column1173_a796a3-fb > .kt-inside-inner-col,.kadence-column1173_a796a3-fb > .kt-inside-inner-col:before{border-top-left-radius:0px;border-top-right-radius:0px;border-bottom-right-radius:0px;border-bottom-left-radius:0px;}.kadence-column1173_a796a3-fb > .kt-inside-inner-col{column-gap:var(--global-kb-gap-sm, 1rem);}.kadence-column1173_a796a3-fb > .kt-inside-inner-col{flex-direction:column;}.kadence-column1173_a796a3-fb > .kt-inside-inner-col > .aligncenter{width:100%;}.kadence-column1173_a796a3-fb > .kt-inside-inner-col:before{opacity:0.3;}.kadence-column1173_a796a3-fb{position:relative;}@media all and (max-width: 1024px){.kadence-column1173_a796a3-fb > .kt-inside-inner-col{border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;flex-direction:column;justify-content:center;}}@media all and (max-width: 767px){.kadence-column1173_a796a3-fb > .kt-inside-inner-col{border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;flex-direction:column;justify-content:center;}}<\/style>\n<div class=\"wp-block-kadence-column kadence-column1173_a796a3-fb\"><div class=\"kt-inside-inner-col\">\n<p><strong>Related articles<\/strong><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-1-mechanism\/\">About RRAM - 1 Operation mechanism<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-2-property\/\">About RRAM - 2 Properties<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-3-crossbar-array\/\">About RRAM - 3 Crossbar array and Sneak Path Current<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-4-forming-compliance-current\/\">About RRAM \u2013 4 Forming and Compliance Current<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-5-impedance-matching\/\">About RRAM \u2013 5 Pulse measurement and impedance matching<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-7-stdp-spike-timing-dependent-plasticity\/\">About RRAM \u2013 7 STDP (Spike-Timing-Dependent Plasticity)<\/a><\/p>\n<\/div><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">1. OxRAM: Movement of Oxygen Vacancies (VCM)<\/h2>\n\n\n\n<p>This is the most widely studied standard method in both academia and industry (TSMC, Infineon, etc.). Its official name is VCM (Valence Change Memory).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1.1. Operation Mechanism<\/h3>\n\n\n\n<p>Oxygen ions (O<sup>2-<\/sup>) within the insulator (oxide) are pushed out by the voltage. The vacant space becomes an oxygen vacancy, a defect through which electrons can move. When these vacancies are connected in a line, they form a filament through which current flows.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Main materials:<\/strong> HfO<sub>2<\/sub>, Ta<sub>2<\/sub>O<sub>5<\/sub>, TiO<sub>2<\/sub> ... transition metal oxides.<\/li>\n\n\n\n<li><strong>Electrodes (Important):<\/strong> Since only oxygen vacancies need to move, the electrode itself should not react. Therefore, inert electrodes such as <strong>TiN, Pt, W, and Ir<\/strong> are used.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">1.2. Advantages and Disadvantages<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Pros:<\/strong> It uses a semiconductor standard material (HfO<sub>2<\/sub>), providing excellent <strong>CMOS process compatibility<\/strong>. It also boasts excellent thermal stability and data <strong>Retention<\/strong> characteristics.<\/li>\n\n\n\n<li><strong>Cons:<\/strong> The operating voltage is somewhat high, and the movement of oxygen ions may be slower than that of metal ions.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">2. CBRAM: ECM<\/h2>\n\n\n\n<p>It is also called PMC (Programmable Metallization Cell) and is a technology commercialized by companies such as Adesto. Its official name is ECM (Electrochemical Metallization).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">2.1. Operation Mechanism<\/h3>\n\n\n\n<p>This is like a microscopic <strong>Electroplating<\/strong> process.<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li><strong>Oxidation (Anode):<\/strong> At the active electrode (Ag, Cu), the metal is oxidized and dissolves into the insulator in the form of ions (Ag<sup>+<\/sup>, Cu<sup>2+<\/sup>).<\/li>\n\n\n\n<li><strong>Migration:<\/strong> Metal ions move through the electric field to the opposite electrode.<\/li>\n\n\n\n<li><strong>Reduction (Cathode):<\/strong> It meets electrons at the opposite electrode and is reduced back into metal and accumulated.<\/li>\n\n\n\n<li><strong>Growth:<\/strong> This lump of metal grows to form a bridge connecting the two electrodes.<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"translation-block\"><strong>Main materials:<\/strong> GeSe, Ag<sub>2<\/sub>S or porous oxide (SiO<sub>2<\/sub>) acting as a solid electrolyte.<\/li>\n\n\n\n<li><strong>Electrode (core):<\/strong> One electrode must be an active electrode, such as Ag or Cu, which is easily dissolved. The other electrode must be an inactive electrode, such as Pt or W.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">2.2. Advantages and Disadvantages<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Pros:<\/strong> <strong>The operating voltage is very low (Low Power)<\/strong>, and the switching speed is fast. The On\/Off resistance difference (Ratio) is very large, making signal discrimination easy.<\/li>\n\n\n\n<li><strong>Cons:<\/strong> The metal filaments (especially silver and copper) produced are too diffusion-prone. Over time, the filaments tend to melt away, resulting in <strong>poor retention.<\/strong><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">3. OxRAM vs CBRAM<\/h2>\n\n\n\n<p>This is the table you must first decide on when writing a paper or designing a device.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><td><strong>Comparison items<\/strong><\/td><td><strong>OxRAM (Valence Change)<\/strong><\/td><td><strong>CBRAM (Electrochemical)<\/strong><\/td><\/tr><\/thead><tbody><tr><td><strong>filament material<\/strong><\/td><td><strong>Oxygen Vacancy<\/strong><\/td><td><strong>metal atoms (Ag, Cu)<\/strong><\/td><\/tr><tr><td><strong>core electrode<\/strong><\/td><td><strong>Inert (TiN, Pt, W)<\/strong><\/td><td><strong>Active (Ag, Cu)<\/strong> + Inert<\/td><\/tr><tr><td><strong>Switch layer<\/strong><\/td><td>HfO<sub>2<\/sub>, Ta<sub>2<\/sub>O<sub>5<\/sub>, TiO<sub>x<\/sub><\/td><td>GeS<sub>x<\/sub>, Ag<sub>2<\/sub>S, SiO<sub>2<\/sub><\/td><\/tr><tr><td><strong>Operating power<\/strong><\/td><td>Medium to high<\/td><td><strong>Very low<\/strong><\/td><\/tr><tr><td><strong>Retention<\/strong><\/td><td><strong>Stable<\/strong><\/td><td>relatively unstable<\/td><\/tr><tr><td><strong>Application<\/strong><\/td><td><strong>Embedded NVM, AI Synapse<\/strong><\/td><td><strong>Low Power IoT, Security Devices<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">4. RRAM Practical Tips: Where Does My Device Fit?<\/h2>\n\n\n\n<p>Sometimes, during research, the boundaries become blurred. For example, if a Cu electrode is placed on top of a HfO<sub>2<\/sub> layer, is this OxRAM or CBRAM?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The correct answer is \u201cHybrid with strong CBRAM characteristics.\u201d<\/strong><\/li>\n\n\n\n<li>HfO<sub>2<\/sub>is a material originally developed for OxRAM, utilizing oxygen vacancies. However, the moment a <strong>Cu electrode<\/strong>is used, copper ions penetrate the HfO<sub>2<\/sub> . Because the mobility of copper ions is much faster than that of oxygen vacancies, switching occurs primarily through copper filaments (CBRAM).<\/li>\n<\/ul>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p><strong>\u26a0\ufe0f Caution:<\/strong> If you're researching OxRAM, never use electrodes like <strong>Ag, Cu, Au<\/strong> recklessly. These metals have strong penetrative properties and can contaminate the device's characteristics. The gold standard for OxRAM research is a MIM structure like <strong>TiN\/HfO2\/TiN<\/strong> .<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">5. Conclusion: Choose the right material for your purpose.<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Reliability (Retention, Endurance) is important and you want to apply it directly to the foundry process? -&gt; Choose OxRAM (HfO<sub>2<\/sub>\/TiN).<\/li>\n\n\n\n<li><strong>Need low power operation<\/strong> or very high on\/off ratio? -&gt; Choose CBRAM (Ag\/GeS).<\/li>\n<\/ul>\n\n\n<style>.kadence-column1173_3aaff8-9d > .kt-inside-inner-col{box-shadow:inset 0px 0px 14px 0px rgba(0, 0, 0, 0.2);border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;}.kadence-column1173_3aaff8-9d > .kt-inside-inner-col,.kadence-column1173_3aaff8-9d > .kt-inside-inner-col:before{border-top-left-radius:0px;border-top-right-radius:0px;border-bottom-right-radius:0px;border-bottom-left-radius:0px;}.kadence-column1173_3aaff8-9d > .kt-inside-inner-col{column-gap:var(--global-kb-gap-sm, 1rem);}.kadence-column1173_3aaff8-9d > .kt-inside-inner-col{flex-direction:column;}.kadence-column1173_3aaff8-9d > .kt-inside-inner-col > .aligncenter{width:100%;}.kadence-column1173_3aaff8-9d > .kt-inside-inner-col:before{opacity:0.3;}.kadence-column1173_3aaff8-9d{position:relative;}@media all and (max-width: 1024px){.kadence-column1173_3aaff8-9d > .kt-inside-inner-col{border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;flex-direction:column;justify-content:center;}}@media all and (max-width: 767px){.kadence-column1173_3aaff8-9d > .kt-inside-inner-col{border-top:0px solid transparent;border-right:0px solid transparent;border-bottom:0px solid transparent;border-left:0px solid transparent;flex-direction:column;justify-content:center;}}<\/style>\n<div class=\"wp-block-kadence-column kadence-column1173_3aaff8-9d\"><div class=\"kt-inside-inner-col\">\n<p><strong>Related articles<\/strong><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-1-mechanism\/\">About RRAM - 1 Operation mechanism<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-2-property\/\">About RRAM - 2 Properties<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-3-crossbar-array\/\">About RRAM - 3 Crossbar array and Sneak Path Current<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-4-forming-compliance-current\/\">About RRAM \u2013 4 Forming and Compliance Current<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-5-impedance-matching\/\">About RRAM \u2013 5 Pulse measurement and impedance matching<\/a><\/p>\n\n\n\n<p>\u2705<a href=\"https:\/\/rtlearner.com\/en\/rram-7-stdp-spike-timing-dependent-plasticity\/\">About RRAM \u2013 7 STDP (Spike-Timing-Dependent Plasticity)<\/a><\/p>\n<\/div><\/div>\n\n\n\n<p>References: <em><a href=\"https:\/\/www.nature.com\/articles\/nmat2023\" target=\"_blank\" rel=\"noopener\">Nanoionics-based resistive switching memories<\/a><\/em><\/p>","protected":false},"excerpt":{"rendered":"<p>So far, we've been talking about \"when voltage is applied, a filament is formed.\" But \"that...\"<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"categories":[114],"tags":[20,21],"class_list":["post-1173","post","type-post","status-publish","format-standard","hentry","category-rram-research","tag-memristor","tag-rram"],"_links":{"self":[{"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/posts\/1173","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/comments?post=1173"}],"version-history":[{"count":5,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/posts\/1173\/revisions"}],"predecessor-version":[{"id":1212,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/posts\/1173\/revisions\/1212"}],"wp:attachment":[{"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/media?parent=1173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/categories?post=1173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rtlearner.com\/en\/wp-json\/wp\/v2\/tags?post=1173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<!-- This website is optimized by Airlift. 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