應用於三維積體電路傳輸系統中的磁感應無線傳輸模組

Magnetic Wireless Interlayer Transmission Module through Perpendicular MTJ for 3D-IC Applications

張良順(Liang-Shun Chang)

指導教授 ： 金雅琴

國立清華大學/電機資訊學院/電子工程研究所/博士(2016年)

摘要

近年來，人們對於電子產品的需求越來越高，在達到多功能的同時更須伴隨輕量化的產品重量及更快速的產品效能。透過連接數個積體電路基板與電路晶片，在複合基板上建立起一個或數個多功能晶片，是多功能電子產品的基本架構，因此晶片與晶片之間的封裝技術擔任了電子產品效能好壞與成敗的重要角色。封裝技術是提供不同晶片或不同晶粒之間作訊號傳遞的橋梁，而訊號傳輸的方法又根據使用的基本架構不同而在性能表現上有所差異與區隔。在眾多封裝技術當中，我們可將其大致歸納成以下三類：(1) 系統級晶片 (2) 系統級封裝 (3) 三維積體電路封裝。
一般來說，系統級晶片是將多顆功能性IC整合成一個產品，系統級封裝則是將多顆晶粒整合成一個功能性IC。近年來，三維技術的概念除了被提出之外，更被廣泛地與傳統的二維技術作結合；因為三維傳輸技術在使用上多了一個維度的使用空間，封裝整合後的積體電路面積可大幅下降，頻寬表現上也得以改善。現行的三維積體電路傳輸技術可大致分以下三類，分別是矽穿孔技術、電容耦合模組、及電感耦合模組等三種不同的三維訊號傳遞技術。矽穿孔連線因為能夠提供到目前最高的傳輸密度，加上其異質基板間整合的高相容性，不管在業界與學界都是三維訊號傳遞技術發展的重點項目。但是因為製作時的額外成本較高以及此種技術所面對到的挑戰，像是孔洞完美填充的難度、製作過程中晶圓薄化增加後續製程困難，以及本身的良率檢測方面等重多問題，都影響著矽穿孔技術接下來是否能夠有更進一步的發展。相較之下，另外兩種無線傳輸技術雖然目前在訊號傳輸密度上無法與矽穿孔技術相比較，但是更高的傳輸速度以及製作上的額外成本相對低廉，加上可直接在邏輯製程中加以製作，各種優勢促使著無線傳輸技術在近年來受到越來越多的關注。
本論文以無線傳輸的電感耦合技術作為出發點，透過改變原本的電感接收端架構，改以使用穿隧式磁性接面元件來當作功率接收的角色，期望在整體的功率損耗上能夠有更佳的表現。在本篇論文中，提出一種新型的磁感應無線傳輸模組，而此模組更可應用在三維積體電路傳輸系統當中，我們稱此傳輸技術為磁性傳輸介面。透過高靈敏度的垂直磁場感測元件搭配上微型線圈，本論文成功的將磁感應無線傳輸模組實際應用在數位訊號以及類比訊號的無線傳輸，並成功地驗證其傳輸特性。除此之外，關於訊號接收端、訊號發射端、設計上的擺放考量以及讀取電路等等，本論文也逐一的作出深入的研究與探討。磁性傳輸介面不僅提供了三維積體電路發展的另一種可能性，製作上更能夠透過標準的邏輯製程技術加以完成，在成本的控制上與其他封裝技術相比，並不會造成額外的高成本。相較於傳統的電感耦合技術，除了在持續微縮的可能性上可以透過改變磁性穿隧介面對於線圈的依賴性，更因為使用的磁性穿隧介面作為新的接收端架構，在傳輸的功率損耗上更勝於傳統的電感耦合。
本論文不僅驗證了訊號的無線傳輸，同時也針對發射端的微型線圈進行優化，以及接收端的垂直磁場感測元件結構分析、整體模組的在傳輸時的溫度探討等相關分析也在本論文中加以討論。同時，在本論文中更針對磁性傳輸模組進行改良，提出了多通式磁性傳輸介面的概念，在搭配多組線圈與陣列式磁場感測元件的架構之下，針對模組的傳輸密度以及傳輸功率作進一步的改善，並比較各類型模組之間的特性差異。論文最後，為了讓整體的磁感應傳輸模組效能有更優化的功率表現，在磁性傳輸模組的框架下更進一步地提出了數種磁場集中器架構，同時透過模擬軟體的輔助，驗證磁場集中器對於磁性傳輸介面的傳輸效率優化。
最後，磁性傳輸介面不僅提供了三維積體電路訊號傳輸的一種可能性，同時更可以在標準邏輯製程中製作完成，針對發射端以及接收端的分析討論也在本論文中有著詳細探討。在磁感應傳輸模組的建立之外，多通道的磁感應無線傳輸模型也在本論文中被加以討論。最後，為了達到更佳的傳輸表現，磁場集中器概念的提出也讓磁性傳輸介面的發展，有了另外一種優化的可能性。

關鍵字

三維積體訊號傳輸 ； 磁感應無線傳輸 ； 線圈應用 ； 磁性穿隧介面

並列摘要

Recently, there has been an increase in the demand for smaller and lighter electronic equipment with response and multi-function capabilities data. These multi-function systems required the integration of the IC chips by same/or special process, hence, transmission between chips is critical to the performance of these systems. While packaging technologies have rapidly developed, various system integration schemes have been implemented in recent years, such as, system on chip (SoC), system in package (SiP), and 3D integrated circuit (3D-IC).
In general, there are three types of data transmission schemes in 3D-IC technologies: (1) through-silicon via (TSV), (2) capacitive coupling module and (3) inductive coupling module. TSV technology belongs to “direct contact” transmission method, and has received considerable attention because of its ability to achieve high density connection in heterogeneous integration. However, TSV technologies faces challenges in a lot of problems, such as (a) Additional process flow resulting in high cost, (b) The difficult of perfect via filling (voidless), (c) Wafer thinning resulting in harder manufacturing, (d) Chemical Mechanical Planarization (CMP) uniformity, (e) Yield inspection, etc. Compared to TSV technology, the capacitive coupling module and the inductive coupling module attract more and more interesting by their high data transmission rate, low additional cost, and can directly manufacture in the standard CMOS process. Moreover, those two transmission module featured in high packaging reliability due to wireless characteristic. The capacitive coupling module is the wireless transmission of energy within an electrical network by means of the capacitance between circuit nodes. And a capacitive channel is created by placing small metal plates on two silicon dies and stacking the two dies so that the metal plates are parallel, creates a capacitor. This capacitor connects two circuits by passing an AC signal through it. Capacitive coupling methods have the advantages of simple channel modelling and less crosstalk due to a more confined electrical field. However, its distance of communication is limited to only several microns. Similar to capacitive coupling, inductive coupling is a wireless transmission module, but the transmission mechanism is magnetic rather than electrical. Wireless inductive coupling methods rely on the coupled magnetic field between a planar spiral inductor pair. Chips are stacked face-up and inductively coupled by metal inductors to form a multi-drop bus. However, the challenges of implementing an inductive coupling link include larger inductor area and relatively higher power consumption, as compared to TSVs.
In this thesis, a new wireless 3D IC connection method, Magnetic-sensing Transmission Interface (MTI), is reported for the first time. From the view of inductive coupling but changing the sensor structure, it is expected to achieving a higher operation frequency and a lower power consumption. Signal transmission through the MTI implemented by placing a high-sensitivity sensor with perpendicular magnetic anisotropy on the top of a micro-coil transmitter is successfully demonstrated. This novel embedded perpendicular MTJ (p-MTJ) based on the MTI is proposed for wireless connections in 3D-ICs. The magnetic field of a micro-coil can be centralized on the magnetic sensor for best response, enabling localized data transmission. Compared with inductive coupling between two coils, the receiving end of the magnetic-sensing transmission is replaced by a p-MTJ, which enables highly efficient and localized transmission, leading to lower power and faster connection speed of the module. In addition, the concept of multiple channel MTI module is also introduced and discussed in this thesis. A further design of transmitter-end and receiver-end, the multi-channel MTI can achieve a higher data transmission density and a better power consumption. As last, magnetic field concentrator applied on MTI module is introduced, and four type of concentrator structure are purposed and analysed. Under the same way of transmission but changes the entire transmission structure, the p-MTJ sensor can detect stronger field intensity to reduce the driving coil current, achieving a further better power consumption.
In summary, a new 3D-IC connection method using an MTI has been demonstrated for low power and wide bandwidth data transmission in 3D-IC integration technology. And two types of receiver circuits based on the MTI were proposed and applied in the 3D-IC connection. Moreover, the performance of both receiver circuits has been successfully demonstrated with 0.18 μm CMOS technologies. Using a highly sensitive magnetic sensor, the proposed MTI receives signals at a low vertical magnetic field, leading to much lower transmitting power, whereas its fast spin response and light capacitive load allow for high-speed, low-power and wireless 3D connections.

並列關鍵字

Three Dimensional Transmission System ； Magnetic Wireless Transmission ； Micro-Coil Application ； Magnetic Tunneling Junction

參考文獻

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