Abstract
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.