螢石結構之氧化鉿鋯於先進製程中應用

Abstract

螢石結構之氧化鉿鋯展現出於先進電晶體技術中的潛在價值。隨著元件微縮至GAA（Gate-All-Around）與CFET（Complementary FET）架構，對於高介電常數（k）材料在閘極氧化層的需求愈加迫切。藉由其可調控的鐵電性與穩定的高介電特性，HfO₂-基超晶格有望同時達到低漏電、優化臨界電壓控制以及新型非揮發性邏輯功能，成為未來邏輯與記憶體整合的重要材料。 本研究提出兩種基於形態相邊界（MPB）之氧化鉿鋯（HfO₂）超晶格結構，為DZZ，展現出高介電常數（k = 65）、低矯頑場（Ec = 0.8 MV/cm）以及大殘餘極化（2Pr = 41 μC/cm²），並僅需450 °C退火即可符合後段製程（BEOL）需求。 其介電常數的提升來自於離子與電子的共同貢獻，並在正交（Orthorhombic Phase）與四方相（Tetragonal Phase）交替之界面進一步增強。可靠度測試顯示，薄膜於10¹⁰次循環後仍維持 k > 60，2 × 10¹⁰次循環後仍具備2Pr > 30 μC/cm²，且在超過10⁸次1/3 Vop擾動測試下未觀察到明顯衰退。陣列架構與操作機制驗證亦證明DZZ可同時支援DRAM與 NVDRAM (FeRAM)應用，為突破Tera世代記憶體牆提供潛在解決方案。 此外，本研究亦提出應用於電源管理之鐵電閘極堆疊氮化鎵高電子遷移率電晶體（FeMHEMT），可實現雙模操作之E-mode（Vth⁺ = 3.7 V）與D-mode（Vth⁻ = –1.1 V）的動態閾值電壓調控。透過最佳化AMFM:AGaN 比例，有效抑制極化鎖定效應。FeMHEMT在E-mode與D-mode下分別達到VBD = 878 V與900 V，完全符合 12 V供電網路（PDN）之應用需求。耐久性測試亦證實，元件於10⁹次擾動循環後仍可維持穩定的ΔVth = 3 V，展現優異可靠度。E-mode與D-mode FeMHEMT之整合能實現高效率DC-DC轉換器，為異質整合3D PDN系統中電壓調節器提供高效能且具散熱優勢的解決方案。

Fluorite-phase HfO₂ demonstrates significant potential for advanced transistor technologies. As devices scale to gate-all-around (GAA) and complementary FET (CFET) architectures, the demand for high-k gate dielectrics becomes increasingly critical. By leveraging its tunable ferroelectricity and stable high-k properties, HfO₂-based superlattices can simultaneously achieve low leakage, optimized threshold voltage control, and novel non-volatile logic functionalities, positioning themselves as strong material candidates for future logic–memory co-integration. In this work, two kinds of morphotropic phase boundary (MPB) based HfO₂ superlattice structures DZZ, are proposed, demonstrating a high dielectric constant (k = 65), low coercive field (Ec = 0.8 MV/cm), and large remnant polarization (2Pr = 41 μC/cm²), with a thermal budget of only 450 °C annealing compatible with Back-End-of-Line (BEOL) processing. The enhancement of dielectric constant originates from the combined contributions of ionic and electronic polarization, further reinforced at domain boundaries formed by alternating orthorhombic and tetragonal phases. Reliability assessments reveal that the films maintain k > 60 after 10¹⁰ cycles, preserve 2Pr > 30 μC/cm² after 2 × 10¹⁰ cycles, and exhibit no observable degradation under 1/3 Vop disturbance stress for more than 10⁸ cycles. Array-level validation further confirms that DZZ can simultaneously support DRAM and NVDRAM (FeRAM) operation, offering a promising pathway to overcome the memory wall in the Tera-generation era. Furthermore, this work introduces ferroelectric-gated GaN high-electron-mobility transistor (FeMHEMT) for power management applications, enabling dynamic threshold voltage modulation dual-mode operation of E-mode (Vth⁺ = 3.7 V) and D-mode (Vth⁻ = –1.1 V). By optimizing the AMFM:AGaN ratio, the polarization lock effect is effectively mitigated. The FeMHEMT achieves breakdown voltages of VBD = 878 V in E-mode and 900 V in D-mode, fully meeting the requirements of 12 V power delivery network (PDN) operation. Endurance testing further confirms robust reliability, maintaining stable ΔVth = 3 V after 10⁹ disturb cycles. The co-integration of E-mode and D-mode FeMHEMT enables the realization of high-efficiency DC-DC converters, providing thermally advantageous and performance-enhanced voltage regulators for heterogeneous 3D PDN systems.