隨著3C電子產品需求遽增以及物聯網 (Internet of Things, IoT)、大數據 (Big Data) 和人工智慧 (Artificial Intelligence, AI) 等技術的快速發展，小尺寸、傳輸速度快、高效能及低能耗等高性能特性已儼然成為微機電系統 (Micro-Electro Mechanical Systems, MEMS) 與半導體發展的主流。這些特性與早期晶片設計中較大體積和較慢傳輸速度形成對比。然而，尺寸縮小及性能需求的提高，為製程開發帶來了諸多限制和挑戰。在黃光製程中，需要使用波長更短的極紫外光 (EUV) 來實現更細的線寬極限。在薄膜製程方面，晶片尺寸的限縮使得每層堆疊的厚度需要變得更薄，不僅使得薄膜厚度及均勻度控制上的難度，更影響薄膜的片阻及電性。此外，若材料間熱膨脹係數 (CTE) 差異過大，當元件受熱後亦會造成更顯著的問題，進而導致薄膜破裂或元件損壞。
為了解決這些問題，本研究聚焦於氮化鈦 (Titanium Nitride, TiNx) 和鉭化氮 (Tantalum Nitride, TaNx) 兩種薄膜，這兩種薄膜在半導體及微機電製程中廣泛用作擴散阻障層 (Barrier layer)、銅導線種晶層 (Seed layer)和黏著層 (Adhesive layer)。利用直流磁控濺射的物理氣相沉積 (Physical Vapor Deposition, PVD) 技術，以不同氣體比 (RN = N2/(N2+Ar))沉積厚度約10nm的超薄薄膜，並在製程參數中調整氮氣 (N2) 和氬氣 (Ar) 的氣體比例，以調變這兩種超薄膜的機械性質，包括楊氏係數 (Young’s modulus)、殘留應力 (Residual Stress) 和熱膨脹係數 (Coefficients of thermal expansion, CTE)。在本研究實驗中為驗證此方法的可行性，將RN值為0.3、0.5、0.8之 TiNx 薄膜和 RN 值為 0.3、0.4、0.5之 TaNx 薄膜沉積於以微機電技術製作的 SiO2 懸臂樑上，使其形成複合測試懸臂樑。由實驗萃取結果得知，透過調變PVD 製程中的氣體比例，TiNx 及TaNx薄膜其楊氏係數、殘留應力及熱膨脹係數皆產生了顯著變化，為此本研究提供了一種簡便的方法和指南，讓研究開發者得以根據特定應用需求量身定制 TiNx 和 TaNx 薄膜。

With the rapid increase in demand for 3C electronic products and the fast-paced advancements in technologies such as the Internet of Things (IoT), Big Data, and Artificial Intelligence (AI), high performance characteristics such as compact size, fast transmission speed, high efficiency, and low energy consumption have become widely adopted in the development of micro-electromechanical systems (MEMS) and semiconductors. These characteristics contrast with the larger size and slower transmission speeds of earlier chip designs. However, miniaturization and increased performance demands have introduced numerous limitations and challenges in process development. In photolithography processes, shorter wavelength extreme ultraviolet (EUV) lithography is required to achieve finer line width limits. In thin film processes, the reduction in chip size necessitates thinner layers for each stack, which not only increases the difficulty in precisely controlling film thickness but also impacts the uniformity, sheet resistance, and electrical properties of the films. Furthermore, differences in coefficients of thermal expansion (CTE) between materials may lead to more pronounced effects upon heating, potentially resulting in film cracking or device failure.

To address these issues, this study focuses on two types of thin films, Titanium Nitride (TiNx) and Tantalum Nitride (TaNx), which are widely used in semiconductor and MEMS processes as diffusion barrier layers, copper seed layers, and adhesive layers. Ultrathin films of approximately 10 nm thickness were deposited using Physical Vapor Deposition (PVD) with DC magnetron sputtering, and the gas ratio of nitrogen (N2) and argon (Ar) was adjusted to modulate the mechanical properties of these ultrathin films, including Young’s modulus, residual stress, and coefficients of thermal expansion (CTE). In the experimental setup, TiNx and TaNx films with three different gas ratios (RN = N2/(N2+Ar)) were extracted. To validate the feasibility of this approach, TiNx films with RN values of 0.3, 0.5, and 0.8, and TaNx films with RN values of 0.3, 0.4, and 0.5 were deposited on SiO2 cantilever beams fabricated using MEMS technology, forming composite test cantilevers. Results from the experiment reveal significant changes in Young’s modulus, residual stress, and CTE of the TiNx and TaNx films due to variations in gas ratio during the PVD process, thereby verifying that this study provides a straightforward method and guideline for users to customize TiNx and TaNx thin films according to specific application requirements.

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