可應用於光學影像防手振系統之新型微機電雙軸平台設計、整合與實現

Abstract

近年來可攜式電子產品之相機模組已朝向高畫素、小尺寸與低功耗的方向發展，為了在不犧牲影像畫素的前提下補償手振所產生的影像模糊，高階相機模組廣泛的使用光學影像防手振系統(Image Stabilizer, IS)來補償手振所造成的模糊影像，然而現行"精密機械加工技術"所製作之IS中無論音圈或是壓電馬達，在元件尺寸上皆已至技術極限，尤其在厚度方面更是如此；以光學式影像防手振智慧型手機Sharp SH-01D為例，其所使用的IS模組尺寸為11x11x5.47 mm3，由於IS模組厚度的限制造成手機總厚度大於9.7mm；為了達到光學式防手振超薄手機相機的目標，本論文利用"微機電技術"設計並製作微型防手振平台，所研發之元件包括靜電式與熱電式雙軸防手振平台。在製作技術方面，主要利用雙層矽基板製程(Silicon on Silicon, SOS)與絕緣層覆矽基板製程(Silicon on Insulator, SOI)製作元件，關鍵製程部份包括使用感應式電漿耦合(Inductive Coupled Plasma, ICP)蝕刻系統進行高深寬比乾式蝕刻製程、氫氟酸蒸氣(HF vapor)與反應式離子蝕刻(Reaction Ion Etching, RIE)系統進行元件結構之釋放。製作完成元件其懸浮結構厚度為50μm-120μm，加上承載基板後的總體厚度可降低至400μm以下；封裝的部分則使用覆晶封裝(Flip-chip bonding)技術與打線封裝(Wire bonding)技術來完成影像感測元件與雙軸平台間之整合與封裝。在系統實現方面，利用市售加速規感測拍照瞬間手振，並與控制器、位置感測器與驅動電路等單元整合以補償手振位移訊號，進而達到防手振的效果。根據量測結果顯示，本論文研發之雙軸平台皆可驅動至三倍光學變焦等效最大手振位移24.42μm，其中靜電式IS的部分利用佈局設計使驅動電壓降低至51V以下，熱電式IS則利用運算放大器與達靈頓電路使的驅動電壓電流小於5V與155mA，在與控制器整合後可達到1.86級之防手振效果；故本論文所實現之微機電雙軸防手振平台具有手振補償功能與小尺寸優勢，十分適合應用於未來可攜式電子產品如超薄智慧型手機相機模組。

In recent years, the camera of portable electronics has been developed to high definition, small size and low power consumption, to compensate image blurs, the image stabilizer (IS) had been comprehensively used in digital single-lens reflex cameras, to fabricate IS small enough to be embedded in ultra thin portable electronics, Micro-Electro-Mechanical Systems (MEMS) manufacturing technique is used to develop MEMS-based IS in this dissertation, which includes the electrostatically-actuated XY stage and thermally-actuated XY stages. In fabrication part, the MEMS manufacturing processes include silicon on silicon (SOS), silicon on insulator (SOI), inductive coupled plasma (ICP), HF vapor and reaction ion etching (RIE), the suspended structures of developed devices are 50-120μm thick and the whole device is thinner than 400μm. Besides, flip-chip bonding and wire bonding technologies are utilized in packaging process. According to the experimental results, all of the developed micro XY stages are exceed the maximally hand-shaking displacement of 3X cellular phone camera requirement 24.42μm. In the part of electrostatically-actuated XY stage, the driving voltage is reduced to 51V or smaller by using the structure designs, in the other part of thermally-actuated XY stage, the driving voltage and current are reduced to 5V and 155mA or smaller by using operational amplifiers and Darlington pairs. After integrating units of driving circuits, sensors and a controller, the proposed IS can provide the equivalent effect of a shutter speed approximately 1.86 stops faster. In short, the proposed image stabilization devices not only have the ability to compensate hand-shaking, but also the advantage of device minimization, therefore, the developed image stabilization devices are very suitable to integrate with cameras of ultra thin portable electronics.