{"id":1810,"date":"2010-07-13T11:53:31","date_gmt":"2010-07-13T15:53:31","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1810"},"modified":"2010-07-13T11:53:31","modified_gmt":"2010-07-13T15:53:31","slug":"sub-5-kev-scanning-electron-beam-lithography","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/sub-5-kev-scanning-electron-beam-lithography\/","title":{"rendered":"Sub-5 keV Scanning-Electron-Beam Lithography"},"content":{"rendered":"<div class=\"page-restrict-output\"><p>Scanning-electron-beam lithography (SEBL) commonly uses voltages between 10-100\u00a0keV. Higher voltages result in distributed proximity effects, lower sensitivity, and a higher probability of substrate damage. Proximity effects raise concern because these effects limit resolution at voltages 10-50\u00a0keV and complex and computationally-intensive programs are used to correct such effects. Proximity effects can be reduced by using either very high voltages (100\u00a0keV) or very low voltages around 1\u00a0keV<sup>&nbsp;[<a href=\"#footnote_0_1810\" id=\"identifier_0_1810\" class=\"footnote-link footnote-identifier-link\" title=\"L.D. Jackel, R.E. Howard, P.M. Mankeiwich, H.G. Craighead, and R.W. Epworth, &ldquo;Beam energy effects in electron beam lithography: The range and intensity of backscattered exposure,&rdquo; Applied Physics Letters, vol. 45, 1984, p. 698.\">1<\/a>]<\/sup>. Our research efforts have investigated the feasibility of SEBL at energies of 2\u00a0keV and below.<\/p>\n<p>Nested Ls patterned in 15-nm-thick hydrogen silsesquioxane (HSQ) on silicon were used to investigate the resolution limit for dense patterns at low-voltages. Ls at 20-nm pitch were sucessfully patterned at energies of 2\u00a0keV and 1.5\u00a0keV, as shown in Figure\u00a01. At 1\u00a0keV energy, the finest pitch possible was 25\u00a0nm. Nested Ls were also patterned in 11-nm-thick poly methyl methacrylate (PMMA) on silicon, with the minimum resolvable pitch at an energy of 2\u00a0keV being 70\u00a0nm. Monte-Carlo simulations of point-spread and line-spread functions were performed for a 2\u00a0keV, 9-nm diameter electron-beam incident on 15-nm-thick HSQ on silicon. The simulated distributed-energy-profile of dense Ls is in agreement with experimental results. To demonstrate pattern-transfer capability of patterns fabricated with low-voltage SEBL, dense line patterns in HSQ were reactive-ion-etched (RIE) into XHRiC anti-reflective\u00a0 layer with HSQ as the etch mask.<\/p>\n\n\t\t<style type=\"text\/css\">\n\t\t\t#gallery-1 {\n\t\t\t\tmargin: auto;\n\t\t\t}\n\t\t\t#gallery-1 .gallery-item {\n\t\t\t\tfloat: left;\n\t\t\t\tmargin-top: 10px;\n\t\t\t\ttext-align: center;\n\t\t\t\twidth: 50%;\n\t\t\t}\n\t\t\t#gallery-1 img {\n\t\t\t\tborder: 2px solid #cfcfcf;\n\t\t\t}\n\t\t\t#gallery-1 .gallery-caption {\n\t\t\t\tmargin-left: 0;\n\t\t\t}\n\t\t\t\/* see gallery_shortcode() in wp-includes\/media.php *\/\n\t\t<\/style>\n\t\t<div id='gallery-1' class='gallery galleryid-1810 gallery-columns-2 gallery-size-medium'><dl class='gallery-item'>\n\t\t\t<dt class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig1.jpg'><img width=\"300\" height=\"288\" src=\"https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig1-300x288.jpg\" class=\"attachment-medium size-medium\" alt=\"Figure 1\" loading=\"lazy\" aria-describedby=\"gallery-1-1811\" srcset=\"https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig1-300x288.jpg 300w, https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig1.jpg 600w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a>\n\t\t\t<\/dt>\n\t\t\t\t<dd class='wp-caption-text gallery-caption' id='gallery-1-1811'>\n\t\t\t\tFigure 1: Scanning-electron micrographs of nested Ls in 15-nm-thick HSQ patterned at electron energies of a) 2 keV, b) 1.5 keV, and c) 1 keV. The samples were developed in salty developer (4%NaCl, 1%NaOH in de-ionized water) for 60s. d) Scanning electron micrograph of nested Ls in 11-nm-thick PMMA patterned at electron energy of 2 keV.\n\t\t\t\t<\/dd><\/dl><dl class='gallery-item'>\n\t\t\t<dt class='gallery-icon landscape'>\n\t\t\t\t<a href='https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig2.jpg'><img width=\"300\" height=\"296\" src=\"https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig2-300x296.jpg\" class=\"attachment-medium size-medium\" alt=\"Figure 2\" loading=\"lazy\" aria-describedby=\"gallery-1-1812\" srcset=\"https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig2-300x296.jpg 300w, https:\/\/wpmu2.mit.local\/wp-content\/uploads\/2010\/07\/Cheong_Sub-5-keV_Fig2.jpg 600w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a>\n\t\t\t<\/dt>\n\t\t\t\t<dd class='wp-caption-text gallery-caption' id='gallery-1-1812'>\n\t\t\t\tFigure 2: Scanning-electron micrographs of XHRiC cross-sections after reactive-ion-etching for 50s. Electron-beam lithography at an energy of 2 keV was used to pattern HSQ with lines. The HSQ lines was then used as a mask to transfer the pattern into XHRiC. Top micrograph shows the successful pattern transfer with lines at a 30-nm pitch, and the bottom micrograph is a cross-section of lines at 40-nm pitch. The lines are roughly 9-nm wide and the XHRiC approximately 60-nm thick.\n\t\t\t\t<\/dd><\/dl><br style=\"clear: both\" \/>\n\t\t<\/div>\n\n<hr>\r\nReferences<ol class=\"footnotes\"><li id=\"footnote_0_1810\" class=\"footnote\">L.D. Jackel, R.E. Howard, P.M. Mankeiwich, H.G. Craighead, and R.W. Epworth, &#8220;Beam energy effects in electron beam lithography: The range and intensity of backscattered exposure,&#8221; <em>Applied Physics Letters<\/em>, vol. 45, 1984, p. 698. [<a href=\"#identifier_0_1810\" class=\"footnote-link footnote-back-link\">&#8617;<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"<div class=\"page-restrict-output\"><p>Scanning-electron-beam lithography (SEBL) commonly uses voltages between 10-100\u00a0keV. Higher voltages result in distributed proximity effects, lower sensitivity, and a higher&#8230;<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[11],"tags":[41,4199],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1810"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=1810"}],"version-history":[{"count":4,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1810\/revisions"}],"predecessor-version":[{"id":1816,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1810\/revisions\/1816"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=1810"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=1810"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=1810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}