{"id":2267,"date":"2023-11-30T06:00:02","date_gmt":"2023-11-30T06:00:02","guid":{"rendered":"http:\/\/localhost:8080\/c-igzo-transistors-with-high-thermal-stability-show-promise-for-next-gen-memory-channels\/"},"modified":"2026-07-29T14:56:21","modified_gmt":"2026-07-29T05:56:21","slug":"c-igzo-transistors-with-high-thermal-stability-show-promise-for-next-gen-memory-channels","status":"publish","type":"post","link":"https:\/\/news.skhynix.com\/en\/c-igzo-transistors-with-high-thermal-stability-show-promise-for-next-gen-memory-channels\/","title":{"rendered":"Crystalline IGZO Transistors With High Thermal Stability Show Promise for Next-Gen Memory Channels"},"content":{"rendered":"

Amorphous InGaZnO*<\/span>\u00a0(a-IGZO)-based thin-film transistors*<\/span> (TFT) have shown potential as stackable channel materials for next-generation\u00a0memory solutions due to their extremely low off-current (Ioff<\/sub>) and high electron mobility. However, currently there is no active research being conducted on IGZO devices operating at thermal budgets*<\/span> above 550\u00b0C during hydrogen-rich processes, which are normally used in memory development. This results in a-IGZO instability issues driven by hydrogen-related defects during these processes.<\/p>\n

*<\/span>InGaZnO: A semiconducting material consisting of\u00a0indium\u00a0(In),\u00a0gallium\u00a0(Ga),\u00a0zinc\u00a0(Zn), and\u00a0oxygen\u00a0(O).
\n*<\/span>Thin-film transistor (TFT): A type of MOSFET fabricated through thin-film deposition traditionally used in liquid crystal displays (LCDs).
\n*<\/span>Thermal budget: The total amount of thermal energy or heat that can be dissipated or allowed within a device without exceeding its specified temperature limits.<\/p>\n

In light of this, SK hynix\u2019s Revolutionary Technology Center (RTC) conducted research on crystalline IGZO (c-IGZO) TFTs and compared their characteristics with a-IGZO TFTs. Presented at the 2023 Very Large-Scale Integration (VLSI) Symposium, the study aimed to demonstrate that c-IGZO TFTs can be more thermally stable than a-IGZO under hydrogen-rich processes.<\/p>\n

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Demonstrating the Thermal Stability & Hydrogen Process Resistance of c-IGZO<\/h3>\n
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\"(a)<\/p>\n

\u25b2 Figure 1. (a) The various process steps involving hydrogen at 550\u00b0C after IGZO deposition. (b) Transmission electron microscopy (TEM) images of a-IGZO and (c) c-IGZO before and after subsequent deposition processes and electron energy loss spectroscopy (EELS) images after processing.<\/p>\n

\"(a)<\/p>\n

\u25b2 Figure 2. (a) The transfer characteristics of a-IGZO (A\u2019) and c-IGZO TFTs (A-D), which have incrementally increasing amounts of gallium from A to D, at a drain voltage (Vds) of 1V (W\/L=0.8\/0.1 micrometers [\u03bcm]). (b) A comparison of the on-current (drain current [Ids] at gate voltage [Vgs]-threshold voltage [Vth]=3V) with Vth performance for various IGZO conditions.<\/p>\n

As shown in Figures 1 (b) and (c), agglomeration*<\/span>\u00a0was observed in a-IGZO following several high thermal hydrogen-rich deposition processes, while c-IGZO remained stable without structural changes.\u00a0This suggests that c-IGZO is significantly more resistant to hydrogen at high temperatures than a-IGZO and enables additional oxide thickness (Tox<\/sub>)\u00a0scaling. Meanwhile, Figure 2 (b) shows that the threshold voltage (Vth<\/sub>) can be controlled by adjusting the composition of c-IGZO (A to D). When c-IGZO demonstrated a similar Vth <\/sub>to a-IGZO, the on-current (Ion<\/sub>) was 1.8 times higher in c-IGZO (C) than a-IGZO (A\u2019).<\/p>\n

*<\/span>Agglomeration: The process of particles or granules sticking together to form larger clusters or agglomerates.<\/p>\n

\"An<\/p>\n

\u25b2 Figure 3. An off-current at 25\u00b0C of c-IGZO (C) TFT with a channel length of 70 nanometers (nm) extracted from an Arrhenius plot<\/p>\n

\"The<\/p>\n

\u25b2 Figure 4. The transfer characteristics of a-IGZO (Tox=100\u212b) and optimized c-IGZO TFT (Tox= 50\u212b). (Vds = 1V)<\/p>\n

\"The<\/p>\n

\u25b2 Figure 5. The optimized c-IGZO (Tox =50\u212b) TFT after positive bias temperature stress (PBTS) testing for 1,000 seconds (s).<\/p>\n

Figure 3 shows that extremely low Ioff<\/sub> of 1.82\u00d710\u221218<\/sup> A\/micrometers (\u03bcm) was demonstrated in the c-IGZO TFT with a channel length*<\/span>\u00a0(Lg<\/sub>) of 70 nanometers (nm). This suggests that c-IGZO can be a feasible material for DRAM cells as it offers a long data retention time.<\/p>\n

The researchers also found that, through composition control and Tox<\/sub> scaling, the subthreshold swing*<\/span>\u00a0and Ion<\/sub> of the optimized c-IGZO showed significant improvement (Figure 4). Furthermore, Figure 5 shows that despite the relatively thin Tox<\/sub>\u00a0of 50\u212b, the optimized c-IGZO device demonstrated similar Vth\u00a0<\/sub>shift (\u0394Vth<\/sub>) as a-IGZO (+19 millivolts [mV]) after the positive bias temperature stress*<\/span>\u00a0(PBTS) test. This indicates that c-IGZO has better Vth<\/sub>\u00a0stability than a-IGZO.<\/p>\n

*<\/span>Channel length: A critical dimension of a MOSFET which represents the length of the semiconductor channel between the source and drain terminals.
\n*<\/span>Subthreshold swing: The amount of change in the gate voltage required to change the drain current by a factor of 10.
\n*<\/span>Positive bias temperature stress (PBTS): A reliability test for a semiconductor device which involves subjecting the device to elevated temperatures while applying a positive bias voltage to the gate terminal.<\/p>\n

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C-IGZO: The Future of Next-Gen Memory Channel Materials<\/h3>\n
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The researchers found that c-IGZO has better thermal stability and is more immune to hydrogen processes than a-IGZO. Due to these characteristics, c-IGZO can be an excellent candidate for new channel materials in future memory devices with high thermal budgets.<\/p>\n

For more information regarding RTC\u2019s research, please visit the center\u2019s <\/em>research website (<\/em>https:\/\/research.skhynix.com<\/em><\/a><\/span>). The RTC operates the site to<\/em> share insights on its ongoing research of future technologies and to actively communicate with various global research organizations.<\/em><\/p>\n

\"The<\/p>\n","protected":false},"excerpt":{"rendered":"

Amorphous InGaZnO*\u00a0(a-IGZO)-based thin-film transistors* (TFT) have shown potential as stackable channel materials for next-generation\u00a0memory solutions due to their extremely low off-current (Ioff) and high electron mobility. However, currently there is no active research being conducted on IGZO devices operating at<\/p>\n","protected":false},"author":6,"featured_media":2260,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_migrated_source_id":13563,"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[5],"tags":[644,645,600,473,643,646],"class_list":["post-2267","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tech-and-ai","tag-c-igzo","tag-crystalline-igzo","tag-revolutionary-technology-center","tag-rtc","tag-tft","tag-thin-film-transistors"],"acf":[],"_links":{"self":[{"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/posts\/2267","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/comments?post=2267"}],"version-history":[{"count":4,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/posts\/2267\/revisions"}],"predecessor-version":[{"id":11719,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/posts\/2267\/revisions\/11719"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/media\/2260"}],"wp:attachment":[{"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/media?parent=2267"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/categories?post=2267"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/news.skhynix.com\/en\/wp-json\/wp\/v2\/tags?post=2267"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}