{"id":1250,"date":"2011-02-25T18:44:34","date_gmt":"2011-02-26T01:44:34","guid":{"rendered":"http:\/\/www.betasights.net\/wordpress\/?p=1250"},"modified":"2011-02-28T18:45:18","modified_gmt":"2011-03-01T01:45:18","slug":"hb-led-mask-aligner-for-hvm","status":"publish","type":"post","link":"http:\/\/www.betasights.net\/wordpress\/?p=1250","title":{"rendered":"HB-LED mask aligner for HVM"},"content":{"rendered":"<p>After successful high-volume manufacturing (HVM) beta-site evaluations, <a href=\"http:\/\/www.evgroup.com\/en\/products\/lithography\/mask_aligners\/evg620hbl\/\" target=\"_blank\">EV Group (EVG) has released an automated mask aligner fine-tuned to maximize yield in high-brightness LED (HB-LED) fabs. The EVG620HBL<\/a> upgrade to the 620-platform creates an automated tool that can align and expose 165 wafers\/hour, with new illumination optics that can easily see alignment marks on the transparent sapphire substrates commonly used for GaN-epi today (<em>figure<\/em>). New to this tool are five cassette stations &#8211; significantly more than competitive offerings &#8211; to enable continuous fabrication of devices at up to 220 wafers per hour in first print mode for substrates up to 150mm diameter.<\/p>\n<div id=\"attachment_1261\" style=\"width: 226px\" class=\"wp-caption alignright\"><a href=\"http:\/\/www.betasights.net\/wordpress\/wp-content\/uploads\/2011\/02\/evg620hbl_alignmarks_sapphire.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1261\" class=\"size-full wp-image-1261\" title=\"evg620hbl_alignmarks_sapphire\" src=\"http:\/\/www.betasights.net\/wordpress\/wp-content\/uploads\/2011\/02\/evg620hbl_alignmarks_sapphire.jpg\" alt=\"HB-LED GaN-epi on sapphire marks, (LEFT) with conventional illumination, and (RIGHT) with new illumination in EVG620HBL tool. (source: EV Group)\" width=\"216\" height=\"141\" \/><\/a><p id=\"caption-attachment-1261\" class=\"wp-caption-text\">HB-LED GaN-epi on sapphire alignment marks, (LEFT) with conventional illumination, and (RIGHT) with new illumination in EVG620HBL tool. (source: EV Group)<\/p><\/div>\n<p>EVG claims that its bonders and mask aligners are being deployed by four of the top five major HB-LED manufacturers, and that customers drove the creation of the 620HBL to increase their line yields and throughputs. Since the next major market for HB-LEDs is general lighting, cost reductions in high-volume manufacturing (HVM) are critical if CFLs and other general purpose lighting technologies are to be replaced. Throughput is critical for overall cost-reduction, to be sure, but yield losses probably dominate cost-of-ownership (CoO) considerations in evaluating competing fab tools.<\/p>\n<p>Typical HB-LED process flows include 4-5 mask steps, and misalignment between masks is a major factor in yield loss. This new aligner now includes special recipe-controlled microscopes with illumination spectra and polarization optimized for pattern contrast with various wafer and layer materials. It is dedicated to high-brightness LED on sapphire, but it can be used equally well with other substrates such as silicon carbide (SiC), aluminum nitride (AlN), other ceramics, or even metal.<\/p>\n<div id=\"attachment_1262\" style=\"width: 298px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/www.betasights.net\/wordpress\/wp-content\/uploads\/2011\/02\/evg620hbl_maskaligner.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1262\" class=\"size-full wp-image-1262\" title=\"evg620hbl_maskaligner\" src=\"http:\/\/www.betasights.net\/wordpress\/wp-content\/uploads\/2011\/02\/evg620hbl_maskaligner.jpg\" alt=\"EVG620HBL mask aligner (source: EV Group)\" width=\"288\" height=\"247\" \/><\/a><p id=\"caption-attachment-1262\" class=\"wp-caption-text\">EVG620HBL mask aligner (source: EV Group)<\/p><\/div>\n<p>Basic tool capabilities include the following:<\/p>\n<ul>\n<li><strong>Wafer diameters<\/strong><strong><span style=\"font-weight: normal;\">: \t50-150 mm, changeable in &lt;1 minute<\/span><\/strong><\/li>\n<li><strong>Substrates: <\/strong>Sapphire, SiC, Si, AlN, \tmetal, ceramic<\/li>\n<\/ul>\n<ul>\n<li><strong>Throughput: <\/strong>max.165 wph (aligned), 220 wph (first print)<\/li>\n<\/ul>\n<ul>\n<li><strong>Top Side Live Alignment Accuracy: +\/- <\/strong>1.0 \tmicron<\/li>\n<\/ul>\n<ul>\n<li><strong>Bottom Side Alignment (option):<\/strong> +\/- \t1.5 micron<\/li>\n<\/ul>\n<ul>\n<li><strong>Exposure: <\/strong>Proximity, Soft-, Hard- \tand Vacuum-contact<\/li>\n<\/ul>\n<ul>\n<li><strong>Pattern resolution: <\/strong><span style=\"color: #000000;\"><span style=\"font-family: symbol;\"><span style=\"font-size: small;\"> <\/span><\/span><\/span>2.0 micron (Proximity)<\/li>\n<\/ul>\n<ul>\n<li><strong>Footprint: <\/strong>2.1 m<sup>2<\/sup> (<em>figure<\/em>)<\/li>\n<\/ul>\n<ul>\n<li><strong>SECS II\/GEM interface : <\/strong>optional<\/li>\n<\/ul>\n<p>\u201cJust last month, one of the leading HB-LED manufacturers ordered an EVG560HBL bonder,\u201d stated Paul Lindner, EVG&#8217;s executive technology director, \u201cand the EVG620HBL is the latest result of our ongoing efforts around enabling HB-LED manufacturers to develop more efficient, cost-effective and higher yielding devices to meet their customers&#8217; demands. We look forward to making further inroads with this latest offering, which also features high-accuracy handling and alignment of fragile or warped wafers.\u201d<\/p>\n<p>In an exclusive interview with BetaSights, Thomas Uhrmann, EVG&#8217;s business development manager, explained how the quick-swap (&lt;1 min.) vacuum chucks allows for HVM compensation of the different inherent bows of different epi-wafers. Though the tool can function in contact- and vacuum-modes, proximity-alignment of tens of microns is almost always used to extend mask life and reduce particles in patterning HB-LEDs.<\/p>\n<p>For 150mm-diameter sapphire wafers, the thickness spec. today is 1.0-1.3mm. However, once GaN epi-layers are grown using MOCVD, the mismatch between substrate and epi Coefficients of Thermal Expansion (CTE) always induces stress and warp. A typical process flow to grow the epi stack involves several hours at ~700\u00b0C to grow the buffer layers, followed by ramp to ~1050\u00b0C to grow the multi-quantum well (MQW) and p-GaN layers. As the wafer is heated and then cooled, the CTW-mismatch first creates compression and then tension in the epi layers. EVG&#8217;s applications engineers reportedly see up to a full 1 mm of warpage in GaN-epi on sapphire wafers at room temperature.<\/p>\n<p>Since an LED&#8217;s color is determined by the composition of the epi-layers, and since different epi-layers with have different CTEs, epi-wafers to produce different LED colors will have different extents of bow. Consequently, a HVM LED fab can use this new tool with a different chuck for each product to ensure optimal wafer flatness during proximity alignment.<\/p>\n<p>There seems to be one big variable in the world of GaN-epi growth: the possibility of homo-epitaxy on GaN substrates. Since control of defects is critical for GaN device functioning, and since hetero-epitaxy always induces defects, going to homo-epitaxy offers inherently superior device performance. The ability to use simple back-contacts saves fab costs, too. If <a href=\"http:\/\/www.inlustra.com\/technology\/substrates.html\" target=\"_blank\">UCSB spin-out Inlustra Technologies<\/a> can ramp up 50mm diameter GaN substrates and offer them at reasonable prices this year, then sapphire might start to give way as the substrate of choice for HB-LED HVM. However, since GaN is itself rather transparent, the new EVG aligner seems like an ideal tool for HB-LED patterning. <em>-E.K.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>EV Group upgrades aligner platform with optics for transparent wafers like sapphire to create 200wph proximity aligner for high-brightness LED (HB-LED) high-volume manufacturing (HVM): EVG620HBL<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,3,4,6,8],"tags":[],"class_list":["post-1250","post","type-post","status-publish","format-standard","hentry","category-equipment","category-manufacturing-fabrication-line","category-integrated-circuit","category-micro-electro-mechanical-system","category-market-segment"],"_links":{"self":[{"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1250","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1250"}],"version-history":[{"count":16,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1250\/revisions"}],"predecessor-version":[{"id":1272,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1250\/revisions\/1272"}],"wp:attachment":[{"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1250"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1250"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.betasights.net\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1250"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}