建立懸臂針測銲墊尺度之實驗方法與模擬技術

Scrub Mark Scale Experiment and Simulation Method of a Cantilever Needle Used in Wafer Testing

李懿哲(Yi-Che Lee)

指導教授 ： 劉德騏

國立中正大學/工學院/機械工程學系/碩士(2013年)

摘要

探針卡在電子封裝IC測試過程中是相當重要的工具，透過探針卡之探針與晶圓特定銲墊接觸，能夠量得電路的電性，進而判斷出晶粒的好壞。近年來晶片趨向輕薄短小、低成本、多功能與低耗電的需求，晶片上銲墊的面積逐漸縮減且間距愈來愈小，故在封裝第一階段，極需發展超薄化且微細間距晶圓之針測技術(Thin and fine pitch Wafer Probing Techniques)，即時檢測出不良晶粒，取代目前以試誤法來製作探針卡的方法。
本研究中建立了不同行程之晶圓針測實驗，並且利用AFM(Atomic force microscopy)觀察刮痕形狀與量測。此外建立有限元素分析模型來進行晶圓針測模擬，利用3D的模型來模擬銲墊與探針的力學行為，針對銲墊上的刮痕尺度以及針測行程(Over Drive)之間的關係加以討論，且將之模擬結果與實驗做比較，藉由此方法可以更改探針幾何模型來了解探針的幾何參數的選擇對銲墊刮痕尺度的影響，預測不同針測參數及探針尺寸所產生的針痕尺度，找出適當的測試參數，以期降低銲墊損傷風險。

關鍵字

針痕 ； 鋁銲墊 ； 有限元素模擬 ； 懸臂式探針卡 ； 晶圓測試 ； 刮痕尺度

並列摘要

Probe card is a very important tool for electronic packaging wa-fer testing. The electrical properties of the circuit can measured from the contact surface between probes and bonding pads. The above pro-cess is often used to determine the pass or fail of the die.
In recent years, advanced technological trends have required chip to be small, compact, low-cost, multi-functional ,and power consump-tion. These lead to the continuous shrinkage of the chip pad areas and spacing between chip pads. In the first phase of the packaging process, the development of “Thin and fine pitch Wafer Probing Techniques” is highly demanded for the detections of inferior particles within the chips in order to improve the traditional trial methods to design the probe card.
In this thesis, probing needle testing are set up to study the prob-ing mark scale under various over drive distance on Al pad with canti-lever type needles. AFM is employed to observe and measure the size of scratches. A three-dimensional (3D) finite element model was created to simulate the probing behavior to compare with the experimental results. Relationship of scratches size and measurements of override distance was investigated. In order to avoid pad damage, finite element method which is developed in this thesis to analyze the probing behavior during wafer testing, predicts the probing mark.
Furthermore, the mechanism of wafer probing is investigated to derive the relationships among the over drive, probe geometry, mate-rial properties, and scrub mark scale. The finite element method and the experiment are consistent. In addition, the pad criteria are dis-cussed to avoid bonding pad damage. Finally, the effects of various parameters on the probing behavior are investigated and optimized.

並列關鍵字

Al Pad ； Finite Element Method ； Cantilever Type of Probe Card ； Wafer Testing ； Scrub Mark Scale

參考文獻

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