¹InGaZnO: A semiconducting material consisting of indium (In), gallium (Ga), zinc (Zn), and oxygen (O).
²Thin-film transistor (TFT): A type of MOSFET fabricated through thin-film deposition traditionally used in liquid crystal displays (LCDs).
³Thermal budget: The total amount of thermal energy or heat that can be dissipated or allowed within a device without exceeding its specified temperature limits.

In light of this, SK hynix’s 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.

Demonstrating the Thermal Stability & Hydrogen Process Resistance of c-IGZO

Figure 1. (a) The various process steps involving hydrogen at 550°C 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.

Figure 2. (a) The transfer characteristics of a-IGZO (A’) and c-IGZO TFTs (A-D), which have incrementally increasing amounts of gallium from A to D, at a drain voltage (V_ds) of 1V (W/L=0.8/0.1 micrometers [μm]). (b) A comparison of the on-current (drain current [I_ds] at gate voltage [V_gs]-threshold voltage [V_th]=3V) with V_th performance for various IGZO conditions.

As shown in Figures 1 (b) and (c), agglomeration⁴ was observed in a-IGZO following several high thermal hydrogen-rich deposition processes, while c-IGZO remained stable without structural changes. This suggests that c-IGZO is significantly more resistant to hydrogen at high temperatures than a-IGZO and enables additional oxide thickness (T_ox) scaling. Meanwhile, Figure 2 (b) shows that the threshold voltage (V_th) can be controlled by adjusting the composition of c-IGZO (A to D). When c-IGZO demonstrated a similar V_th to a-IGZO, the on-current (I_on) was 1.8 times higher in c-IGZO (C) than a-IGZO (A’).

⁴Agglomeration: The process of particles or granules sticking together to form larger clusters or agglomerates.

Figure 3. An off-current at 25°C of c-IGZO (C) TFT with a channel length of 70 nanometers (nm) extracted from an Arrhenius plot

Figure 4. The transfer characteristics of a-IGZO (T_ox=100Å) and optimized c-IGZO TFT (T_ox= 50Å). (V_ds = 1V)

Figure 5. The optimized c-IGZO (T_ox =50Å) TFT after positive bias temperature stress (PBTS) testing for 1,000 seconds (s).

Figure 3 shows that extremely low I_off of 1.82×10⁻¹⁸ A/micrometers (μm) was demonstrated in the c-IGZO TFT with a channel length⁵ (L_g) 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.

The researchers also found that, through composition control and T_ox scaling, the subthreshold swing⁶ and I_on of the optimized c-IGZO showed significant improvement (Figure 4). Furthermore, Figure 5 shows that despite the relatively thin T_ox of 50Å, the optimized c-IGZO device demonstrated similar V_th shift (ΔV_th) as a-IGZO (+19 millivolts [mV]) after the positive bias temperature stress⁷ (PBTS) test. This indicates that c-IGZO has better V_th stability than a-IGZO.

⁵Channel length: A critical dimension of a MOSFET which represents the length of the semiconductor channel between the source and drain terminals.
⁶Subthreshold swing: The amount of change in the gate voltage required to change the drain current by a factor of 10.
⁷Positive 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.

C-IGZO: The Future of Next-Gen Memory Channel Materials

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.

For more information regarding RTC’s research, please visit the center’s research website (https://research.skhynix.com). The RTC operates the site to share insights on its ongoing research of future technologies and to actively communicate with various global research organizations.

The post Crystalline IGZO Transistors With High Thermal Stability Show Promise for Next-Gen Memory Channels first appeared on SK hynix Newsroom.

SEOUL, September 6, 2001

hynix Semiconductor Inc. announced today that it has signed a definitive agreement with an investor group led by Cando Corporation to establish an international joint venture for its Thin Film Transistor Liquid Crystal Display (TFT LCD) business.

hynix will transfer its TFT LCD business to a joint venture to be formed by the investor group and hynix, with hynix retaining a 19.9% minority equity interest in the joint venture. hynix will receive US $400 million in cash on closing, the retained 19.9% interest in the joint venture, and a purchase price for the buildings and structures which may be deferred for five years, for a total consideration of US $650 million. The transaction is expected to close by the end of November 2001.

“We are very pleased to have entered this partnership with Cando for our TFT LCD business,” said Dr. C.S. Park, Chairman and CEO of hynix. “The transaction also shows hynix’s strong commitment to its restructuring program it announced early this year.” Dr. Harry Ling, President and CEO of Cando Corporation, explained, “Following our successful acquisition of New STI (a leading player in the color filter industry based in Japan), the acquisition of hynix’s TFT LCD business represents a quantum leap forward in achieving our ultimate goal of becoming a global leader in the TFT LCD industry.” Cando Corporation, based in Taiwan, specializes in making color filters for TFT LCD displays. Salomon Smith Barney is acting as financial advisor to hynix, and PricewaterhouseCoopers is acting as financial advisor to the Cando group.

About hynix Semiconductor Inc.

hynix Semiconductor Inc. (HSI) of Ichon, Korea, is an industry leader in the development, sales, marketing and distribution of high-quality semiconductors, including DRAM, SRAM, Flash memory and system IC devices. hynix Semiconductor is the world’s leading DRAM supplier with thirteen semiconductor-manufacturing facilities worldwide, and production capacity of over 300,000 wafer starts per month. In addition, hynix is expanding its system IC business unit with leading technology and added deep-submicron foundry services to strategically broaden its overall semiconductor presence and achieve its goal of leading the global semiconductor market. Based in Korea, hynix maintains development, manufacturing, sales and marketing facilities strategically located worldwide. ###

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Seoul, Korea, June 21, 2001

hynix Semiconductor Inc. announced today that it has signed a letter of intent with Beijing Orient Electronics Group Co., Ltd. (BOE) and Cando Corporation to establish an international joint venture for its Thin Film Transistor Liquid Crystal Display (TFT LCD) business.

hynix will transfer its TFT LCD business to a joint venture to be formed by BOE, Cando and hynix. Subject to final negotiations and structuring, the contemplated transfer price for the business is up to USD 700 million, or not less than USD 400 million ~ 450 million. hynix will receive a combination of cash, minority equity interests in the joint venture, and other consideration. hynix expects that the cash portion that it will receive will be at least USD 350 million. The parties anticipate signing a definitive agreement by August, and closing the transaction by December 2001. The transaction is a part of hynix’s previously announced plan to divest assets outside of its core semiconductor business.

hynix’s TFT LCD business unit designs, develops and manufactures LCD screens used in Notebook PCs, high-end computer monitors and other applications. Beijing Orient Electronics Group Co., Ltd.(BOE), based in Beijing, is a computer monitor and display device manufacturer with A and B shares listed on Shenzen Stock Exchange. Cando Corporation, based in Taiwan, specializes in making color filters for TFT LCD displays. The letter of intent is non-binding and its terms are subject to revision by the parties, Salomon Smith Barney is acting as financial advisor to hynix.

About hynix Semiconductor Inc.

hynix Semiconductor Inc. (HSI) of Ichon, Korea, is an industry leader in the development, sales, marketing and distribution of high-quality semiconductors, including DRAM, SRAM, Flash memory and system IC devices. hynix Semiconductor is the world’s largest DRAM supplier with eleven semiconductor-manufacturing facilities worldwide, and production capacity of over 300,000 wafer starts per month. In addition, hynix is expanding its system IC business unit with leading technology and added deep-submicron foundry services to strategically broaden its overall semiconductor presence and achieve its goal of leading the global semiconductor market. Based in Korea, hynix maintains development, manufacturing, sales and marketing facilities strategically located worldwide.

### “These materials are not an offer for sale of the Securities in the United States. The Securities may not be sold in the United States absent registration or an exemption from registration under the U.S. Securities Act of 1933, as amended. hynix Semiconductor Inc. does not intend to register any portion of the offering in the United States or to conduct a public offering of Securities in the United States.” amended. hynix Semiconductor Inc. does not intend to register any portion of the offering in the United States or to conduct a public offering of Securities in the United States.”

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The new product, HT18E22, is the first to utilize Hyundai’s proprietary Fringe Field Switching (FFS) technology. This innovative FFS technology enables an ultra-wide viewing angle of up to 170 degrees in all directions, a high transmittance rate of 4.8 percent, a contrast ratio of more than 400:1, and natural color reproducibility of 68 percent. With its high transmittance characteristics, the HT18E22 module easily achieves luminance of typically 200 nits, and can exceed 210 nits. It can display 16.7 million full colors, a capability unmatched by similar products from other LCD manufacturers. The HT18E22 monitor module also features an extremely thin and light-weight design (weight: 2.6kg, thickness: 18.6 mm). The introduction of FFS technology positions Hyundai as the high-end LCD monitor module provider, surpassing rival suppliers with superior optical and electrical features. Through FFS innovation and derivative technology, HEI anticipates continuing leadership in the large-sized monitor (up to the 21.3-inch UXGA grade) market. Follow-on development of the next-generation Ultra-FFS technology is focused on achieving a response time faster than 30 ms and completely eliminating color shift. The Ultra-FFS product is targeted for introduction at the LCD/PDP International 2000 exhibition scheduled to take place in Yokohama, Japan this October. The rapidly growing LCD monitor market is projected to reach a worldwide volume of 2.8 million units by 2002, up from 1.4 million units in 2001.

The post Hyundai Electronics to Begin Mass Production of World-Class 18.1-Inch TFT LCD Monitors first appeared on SK hynix Newsroom.