臺灣博碩士論文加值系統

齊納二極體是基於PN接面二極體的逆向崩潰特性，一般應用於電路中當作電壓調節器。隨著電子產品的供應電壓降低，齊納二極體的低電壓調節器是必要的。通常傳統使用高濃度摻雜PN接面來降低PN二極體的逆向崩潰電壓。然而PN二極體的逆向漏電流會隨逆向崩潰電壓降低而逐漸增加，導致逆向漏電流大於產品的規格。
本研究優化齊納二極體的摻雜濃度以降低逆向漏電流由使用電腦模擬與實驗。一般而言，低逆向崩潰電壓的PN二極體有三種主要的逆向漏電流來源: 飽和電流，空乏區產生電流，與能帶間穿隧電流。根據電性分析，製作在高濃度P型矽晶圓的齊納二極體的主要逆向漏電流來源為能帶間穿隧電流。為了減少由於能帶間穿隧效應引起的漏電流，我們使用具有低摻雜濃度的矽晶片來製造PN接面二極體，並調整優化摻雜的擴散製程來滿足逆向崩潰電壓的產品規格要求。
基於電腦模擬，我們製造具有低穿隧漏電流的齊納二極體。PN接面二極體被製作於低摻雜濃度1.22x1018 /cm3的矽晶圓上，由於降低逆向崩潰的臨界電場與增加空乏區寬度，相較PN接面二極體製作於高摻雜濃度2.35x1019 /cm3的矽晶圓，此低摻雜濃度矽晶圓製作的低崩潰電壓齊納二極體的逆向漏電流可大幅降低。電腦模擬顯示，在5伏逆向測試電壓下，齊納二極體的逆向漏電流密度可由3.07x10-11 A/μm2降低至9.34x10-14 A/μm2。實驗上，優化的齊納二極體展顯出5.51x10-14 A/μm2的逆向漏電流，相較於目前的齊納二極體產品(2.01x10-11 A/μm2)，逆向漏電流改善降低三個次方。此逆向漏電流的降低使良率由74.9%提升至99.3%。

Zener diodes are based on the reverse breakdown characteristic of PN junction diodes, and commonly implemented in circuitry as a voltage regulator. As the supply voltage of electronic products decreases, low voltage regulators based on Zener diodes is needed. High concentration doped PN junction is typically used to reduce the reverse breakdown voltage of PN diode. However, the reverse leakage current of the PN junction diode gradually increases with decreasing the reverse breakdown voltage, resulting in a reverse leakage current larger than the product specification.
The study optimized the doping concentration in a Zener diode to reduce the leakage current by using computer simulations and experiments. In general, a low reverse breakdown voltage PN diode has three major reverse leakage current sources: the saturation current, the generation current in depletion region, and the band-to-band tunneling current. According to electrical analysis, the band-to-band tunneling current is the decisive reverse leakage current source for the Zener diode fabricated with p-type silicon wafers of high dopant concentration. To reduce the leakage current due to band-to-band tunneling, silicon wafers with a low dopant concentration were used to fabricate PN junction diodes, which can meet the product specification requirement for the reverse breakdown voltage by optimizing the dopant diffusion process.
On the basis of computer simulation, Zener diodes with a low tunneling leakage current were manufactured. The PN junction diode fabricated on the silicon wafer with a low doping concentration of 1.22x1018/cm3 has a reduced critical electric field of reverse breakdown and a widened depletion region, as compared with the diode fabricated on a wafer with a high doping concentration of 2.35x1019/cm3. By use of Si wafers of smaller doping concentration, the reverse leakage current of the low breakdown voltage Zener diode can be greatly reduced. The computer simulation indicated that the reverse leakage current density of the Zener diode can be reduced from 3.07x10-11 A/μm2 to 9.34x10-14 A/μm2 at a testing reverse voltage of 5 V. Experimentally, the optimized Zener diode exhibited a reverse leakage current density of 5.51x10-14 A/μm2, which is an improvement by three order of magnitude compared with the present Zener diode product (2.01x10-11 A/μm2). The reduction in the reverse leakage current leads to a yield improvement from 74.9% to 99.3%.

中文摘要 i
英文摘要 iii
誌謝 v
目錄 vi
表目錄 ix
圖目錄 xi
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機 5
1.3 論文架構 6
第二章 文獻回顧 8
2.1 PN接面的介紹 8
2.2 低電壓調節器的漏電流 17
2.3 低電壓調節器元件的電性規格 24
2.3.1 逆向偏壓(VR)與逆向電流(IR) 26
2.3.2 逆向崩潰電壓(VZ) 28
2.3.3 膝部區齊納偏壓(VZK)與電流(IZK) 29
2.3.4 膝部區動態電阻 (ZZK) 31
2.3.5 齊納電壓調節器逆向操作偏壓(VZT)與電流(IZT) 32
2.3.6 動態電阻(ZZT) 33
2.3.7 最大可承受的直流電流(IZM) 35
2.4 探討低電壓調節器漏電流的來源 36
第三章 研究方法 43
3.1 模擬軟體與方法 43
3.2 元件結構介紹與電性量測系統 45
第四章 製程與電性模擬 48
4.1 改善低電壓調節器漏電流的方法 48
4.2 元件模擬之參數與模擬的製程條件分組 50
4.3 元件製程模擬結果與討論 57
第五章 元件實作與電性量測 71
5.1 元件實作 71
5.2 元件實作的製作流程步驟介紹 73
5.3 元件實作的電性測試結果與討論 82
第六章 結果與討論 90
6.1 模擬與元件實作的電性比較與討論 90
6.2 元件實作改善前後的電性比較與討論 110
6.3 元件實作的良率改善結果 120
第七章 結論與未來工作 122
7.1 結論 122
7.2 未來工作 124
參考文獻 125

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