| 摘要: | 「探針卡」為「晶圓測試」產業的關鍵組件，晶圓的受測晶粒需透過固定於探針卡探針模組上的「微探針」做為媒介，藉探針與銲墊的直接接觸，測試它的電氣特性。微探針的直徑在0.762~2.54mm(3~10mils)之間，探針針尖與銲墊的接觸面積在 0.1016~0.254mm (0.4~1mils)直徑範圍內，微探針會因接觸因素，導致懸臂式探針的撓曲(deflection)或垂直式探針的挫屈(buckling)現象，使微探針失去了應有的強度，造成「跪針」；或因，針測過程的電熱效應，而發生「燒針」現象。在製造階段，探針卡的功能可以應用專業的測試機(圖十)逐針測試，得到每支探針的接觸電阻、漏電流、與接觸壓力；然而，影響晶粒測試結果的因素包括：探針材質、探針幾何、測試電流、接觸時間、針測行程、以及針測次數。為了在設計開發階段，即能瞭解微探針的「跪針」與「燒針」過程與成因，本研究提出三年期的研究計畫：(第一年) 規劃執行微探針接觸實驗 與 線型探針數值分析，建構單軸向接觸壓力測試平台，應用電腦視覺模組記錄觀察針測過程中微探針的幾何變化，量測它的接觸壓力；並建立垂直式「線型探針」的有限元素分析模型。(第二年) 進行微探針電熱實驗與 電熱耦合數值分析，根據第一年所發展的測試平台，發展電熱測試模組，分析探針材質、針尖接觸面積、測試電壓、針測行程對微探針接觸電阻與溫度之影響；並建立多重物理場之探針有限元素模型，以模擬針測過程的電熱耦合效應。(第三年) 以探針接觸力與接觸電阻為指標之可靠度實驗，擴增X-Y 電控測試平台，執行可靠度實驗，觀察針測次數對探針幾何變化、接觸電阻、以及接觸應力的影響，並進行探針壽命評估。、本計畫以實驗與數值方法探討微探針針測過程的接觸現象、電熱反應、與可靠度分析，研究中建構適用於開發階段的微探針測試平台，可觀察探針的接觸壓力、探針幾何變化、接觸電阻、與針尖溫度，非常有助於「微探針」的設計，以獲得可以針測正確訊號與穩健性能的「晶圓探針卡」。
Probe card is an critical instrument in wafer probing. Electric characteristics of the examined die are detected through micro-probes mounted on the probe module in probe card by direct contacts between the probes and welding pads. Diameters of the micro-probes are within 0.762~0.245mm (3~10 mils). Contact area between the needle tip and the pad is under a diameter of 0.1016~0.254mm (0.4~1mils). In probing, the needle tip sustains a large contact force. The probe would lose it strength due to deflection for a cantilever needle or buckling for a vertical needle, and then results in a ‘kneeling needle’. Moreover, since electrothermal effect during probing, the needle tip would bring on a ‘burning needle’. In probe card fabrication, functions of the probe card can be tested by a PRVS machine (Figure 10), to measure the contact resistance, leakage current, pin alignment, and contact force one pin after another. This study proposes a three-year project to investigate the process and causes of the ‘kneeling needle’ and ‘burning needle’. In the first year plan, a single-axis contact force test platform is constructed, which involves a computer vision device to observe needle’s geometric deformation during probing and a load cell to measure its contact force. In addition, a numerical simulation of vertical ‘wire needle’ is performed. In the second year plan, based on the test platform developing in the first year, an electrothermal test module is built to analyze the influences of needle material, needle tip contact area, volume of probing voltage, and probing overdrive on contact resistance and temperature of the needle tip. In addition, multi-physic finite element models are established to simulate the electothermal coupled problem. In the third year plan, the test platform is improved to a three-axis moving device to carry out reliability experiments. Relationships between the number of probing stroke and needle geometric deformation, contact resistance, and contact force will be discussed systematically, and to evaluate tool life of the micro-probe. This project studies contact problem, electrothermal reaction, and reliability of the micro-probe in wafer probing by experimental and numerical methods. The testing platform constructed can be used to measure the contact force, geometric change, contact resistance, and temperature of the needle tip of the examined probe. It is very useful in micro-probe design, to obtain an excellent wafer probe card detecting correct signals and providing robust performances. |
