T25高壓製程之高頻特性研究測試元件

Abstract

近年來，高功率積體電路興起並有廣泛的應用，而具有平面結構的LDMOS有高崩潰電壓，於焉成為主要的驅動元件。LDMOS特有的低掺雜區域能分散電場，是其能耐高壓的原因。現今除了三五族主動元件外，LDMOS也是手機基地台中作為功率放大器的元件選擇之一。目前CIC尚未提供此製程之高頻特性模型，利用下線的方式取得元件進行高頻特性分析。在尺寸的選取方面，經由經由模擬軟體的驗證，依電流反推得Total width倍數，再利用Finger數進行排列組合。 Total width = width × finger. 我們選了30×16、25×20、20×25，共三種尺寸。 利用TCAD元件模擬器，對元件結構的參數進行比較，比對出濃度以及各層尺寸大小對元件輸出直流的影響。元件的直流特性上，由於要對元件進行高頻量測，在下線時特別將Drain與Bulk分開接，量測時須分別給偏壓，在量測崩潰電壓的時候，發現Bulk電壓與崩潰電壓存在線性關係，在第三章有專節介紹。量測上，為了要量到元件的最高效能，所以在量測期間，嘗試各種偏壓點，找出元件可操作的最高頻率，以及最高的PAE，在第四章有詳細的分析。對高壓元件進行高頻量測，所以儀器輸出限制通常不能滿足元件需求，所以再儀器輸出串接一個功率放大器，已增加訊號產生端的功率，最後量測得以順利進行。

In recent years, the rise of high-power integrated circuits has good application. The LDMOS has high breakdown voltage with a planar structure , which become the major drive components. The LDMOS unique low-doped regions can scatter electric field, it’s the reason that can receive high voltage. Besides the III-V active devices, LDMOS is also a mobile phone base stations as one of the components of the power amplifier to choose. CIC do not provide the high-frequency characteristics of the model of this process now. We taped out to get the device, then analysis of high frequency characteristics. Size selection is through the results of TCAD, according to the current value to calculate the total width factors, and then use the finger number to permutations and combinations. Total width = width × finger. We select three sizes, 30 × 16, 25 × 20, and 20 × 25. Using TCAD device simulator compare how much do concentration and layers of the size impact DC output to device. In dc characteristics of the devices, because we want to measure at high-frequency, we separate Drain and Bulk particularly when tape out. Drain and Bulk have to give bias respectively in measurement. Then, we found that there is a linear relationship between Bulk voltage and breakdown voltage when the measured of breakdown voltage, and there is a detail presentation in Chapter 3. In order to measure the highest performance of the devices, we try a variety of bias points during measurement, to find the highest frequency that device can operates, and highest PAE, there is a detailed analysis in Chapter 4. In measurement, we use high voltage components doing high-frequency measurement, so the instrument output limit usually can’t meet the device requirements. The instrument output series with a power amplifier to increase the power of the signal generator side, then measurement can be carried out smoothly.