利用矽穿孔技術整合微探針陣列以實現高品質神經訊號 擷取研究

Abstract

本論文提出兩種整合微探針陣列(μ-probe array)及矽穿孔(TSV)技術系統之生醫訊號量測系統。此兩種系統皆可應用於大腦電訊號的擷取，將有助於探索大腦功能運作的研究。 在第一代中，成功研發利用矽穿孔(TSV)技術導通雙面之生醫訊號擷取系統。生醫訊號探針提供了穩定且高品質的生醫訊號，對於了解大腦運作及神經訊號的傳遞扮 演重要的腳色。生醫訊號本身具有微弱且容易受雜訊干擾的特性，因此容易受到感測端和量測電路端之間的訊號傳遞路徑所影響。此外，過長的傳遞路徑也會影響整體系統封裝的體積。在此，我們利用矽穿孔(TSV)技術連接感側端和後端量測電路於同一顆晶片的正反兩面。如此將可有效移除大量的焊點及金屬走線讓訊號傳遞路徑大量縮短，如此可以有效提升訊號的品質。此外，我們也提出一低成本、高量率的製程技術，藉由此技術，可以大量提升製程的良率，且有效減低製程所需消耗的成本。經過測試，單一通道的阻抗值於1KHz 時為1.2KΩ，整體晶片面積僅有5 mm × 5 mm 的大小，小體積的晶片有助於提升大鼠的存活率。每個通道包含3 × 8 根矽穿孔陣列。在16 通道的設計方面，總共有30 × 16 根微探針，而4 通道的設計則共有140 × 4 根微探針。不同的通道將可擷取到不同的神經訊號以供神經訊號分析方面的研究。 在第二代中，我們利用2.5D 晶片整合技術整合包覆矽穿孔技術之微探針陣列及生 醫量測系統。此微系統包含包覆矽穿孔之微探針陣列及四顆量測晶片以及一層含有矽穿孔之基板(interposer)。在此系統中，矽穿孔的阻抗量測值於1KHz 時為0.17Ω，而其訊號延遲為-0.5°。在此系統中，每顆晶片大小為5 mm × 5 mm，其上共有24 × 24 根微探針，而每根微探針中間都有一根矽穿孔(TSV)用以導通訊號。此外，每根微探針即為一個通道，也因此，一顆晶片上共有24 × 24 個通道。 在本論文中，共發表了兩種利用矽穿孔技術整合微探針陣列及量測電路之生醫量測系統。藉由矽穿孔和微機電技術之間的整合，提供了高通道密度及高解析度之腦皮質訊號擷取系統的設計及實現。此腦皮質訊號擷取系統將有助於對於大腦功能的探索及神經訊號的研究。

In this thesis, two generation of μ-probe arrays with TSV technology are presented. Both these μ-probe arrays can be used in bio-signal recording to explore operation function of a brain. In generation I, a novel through-silicon-via-based double-side bio-signal recording device is demonstrated and investigated. Bio-signal probes providing stable observation with high quality signals are crucial for understanding how the brain works and how the neural signal transmits. Due to the weak and noisy characteristics of bio-signals, the connected interconnect length between the sensor and CMOS has significant impact on the bio-signal quality. In addition, long interconnections with wire bonding technique introduce noises and lead to bulky packaged systems. This thesis presents an implantable through-silicon via (TSV) technology to connect sensors and CMOS devices located on the opposite sides of the chip for brain neural sensing applications. With the elimination of traditional wire bonding and packaging technologies, the quality of bio-signal can be greatly improved. Moreover, a low-cost and high yield fabrication process for through-silicon-via (TSV)-based bio-signal packaging also presents in this thesis. In measurement results, device impedance is 1.2 KΩ /1 KHz, and total chip size is only 5 mm × 5 mm. Moreover, the rat survival rate increases, owing to the small device size. Additionally, each channel has 3 × 8 TSV arrays, and 16 channels die contains 30 × 16 microprobes, and 4 channels die contains 140 × 4 microprobes. Furthermore, different channels can acquire different neural cell signals, ultimately benefiting neural-signal analysis. In generation II, a 2.5D integration with TSV-inside μ-probes and block diagrams of the bio-sensing microsystem is presented. This microsystem composes of TSV-inside μ-probes, 4 dies and 1 interposer. The measured impedance is 0.17Ω with phase of -0.5° at 1KHz. Total area of μ-probe array chip is 5 mm × 5 mm. One TSV-inside μ-probe signifies one channel. Thus, there are 24 × 24 channels in a chip. In this thesis, two generation integrated bio-signal recorders with μ-probe array and TSV technology for bio-sensing applications are presented. Integration with TSV and MEMS technology achieves high density and high channel resolution brain signal recorder. The brain signal recorder can be helpful for brain function investigation and neural prostheses realization.