高頻覆晶連接線之研究

Abstract

本篇論文為覆晶連接線高頻特性之研究，其研究範圍涵蓋了設計、製程、及高頻特性量測。論文中，首先敘述了覆晶連接線之高頻研究議題，同時文獻中覆晶連接線設計之準則亦被回顧。本論文研究主題之一為「熱引洞轉接」（hot-via transition），此一連接線方式可避免以微帶線為設計基礎之微波晶片，在覆晶封裝時引發的失調效應（detuning effect），研究中，設計以熱引洞轉接來連接微帶線（microstrip）與共平面波導（coplanar waveguide）的結構得到非常好的實驗結果，為目前文獻報導中最佳之結果。另一論文研究主題為同軸轉接結構（coaxial transition），其為連接共平面波導之間的覆晶轉接結構，此為文獻中首次被提出之結構。以同軸轉接之覆晶連接線結構在論文研究中已被成功地製作與驗證，其製程在論文中有詳盡的描述，其設計準則同時亦被建立，並且對照實際製作量測之結果進行驗證。其量測結果顯示，從DC頻率至高頻60 GHz皆呈現良好的傳輸特性。此論文研究最主要貢獻為創新設計及開發兩種轉接技術：「熱引洞轉接」及「同軸轉接」，提供不同種高頻傳輸線轉接之可行方案。

The demands for high frequency interconnect techniques for microwave integrated circuits (ICs) are growing with increasing operating frequencies of the wireless communication systems. Interconnects have significant effect and impact on the overall system performance at high frequencies. To provide good performance in high frequency packaging, flip chip interconnect is one of the most potential candidates over other schemes with low reflection and low insertion loss due to the lower parasitics involved. The widely used bond-wire interconnect suffers from serious parasitics when operating frequency reaches the gigahertz range. The tolerances such as the wire length and loop are very tight to enable an acceptable transition. At high frequencies, however, it still encounters stronger parasitics no matter how well it is controlled. This thesis deals with the design, processing, and characterization of the flip chip interconnects at high frequencies. The main issues of the flip chip interconnect are described before the design criteria of the conventional flip chip interconnect are reviewed. The following presented is the work of the hot-via transition. It is a solution to the detuning effect of the microstrip (MS) flip chip assembly. The designs of the hot-via transition for the MS-to-CPW (coplanar waveguide) are presented; the results presented are the best for this technique at the moment to our knowledge. Another part of work in this thesis is the coaxial transition developed for the CPW-to-CPW flip chip interconnects. The coaxial-type transition was successfully fabricated in-house and demonstrated excellent transition performance up to 60 GHz. The entire fabrication processes for all demonstrated flip chip interconnect structures have been in-house developed and are described in details. All the design rules regarding to the different architectures for the flip chip interconnects are described and verified with the measured results. The main contributions of this thesis work are the innovative designs and the developments of both the hot-via transition and coaxial transition for the flip chip interconnects.