高介電係數介電層材料二氧化鋯應用在碳化矽金氧半電容之光電特性研究

Study of Optical and Electrical Properties of 3C-SiC MOS Capacitor with High Dielectric material: ZrO2

黃彥豪(Yan-Hao Huang)

指導教授 ： 李坤彥

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02144

摘要

本論文旨從立方碳化矽的材料分析開始，探討在不同離子佈值下及不同退火情況下，對內部晶格所造成之影響；之後再將以上樣品作為基板，並且搭配高介電值 (high-κ) 介電層材料：二氧化鋯 (ZrO2) ，製作金氧半電容 (MOS-C)。碳化矽因由於擁有寬能隙、高導熱係數、高崩潰電場的優越材料特性，使得它在高壓、高溫半導體元件方面有無可比擬的優勢。在製作金氧半電容 (MOS-C) 上，因ZrO2擁有寬能隙以及高的介電係數 ( =25-29)，可以有較高的等效氧化層厚度，以防止電流穿隧效應，降低漏電流密度，所以選用此材料做為介電層。

實驗上使用了KrF準分子雷射，在離子佈值後但未退火的樣品上，採用複合式能量密度及發數去執行雷射退火，修補因高劑量離子佈植所造成的碳化矽表面晶格缺陷，並且和本質生長的、未退火的及熱退火的樣品做比較。藉由各種光學量測技術，如 X光粉末繞射儀 (XRD)、傅立葉轉換紅外線光譜儀 (FTIR)、拉曼光譜儀 (Raman) 及霍爾量測 (Hall effect measurement)，對本質生長的、及摻雜鋁 (Al)、氮 (N)、磷 (P) 分別在未退火、雷射退火以及熱退火的情況下之樣品，進行光學量測及頻譜分析，藉此了解其晶格結構與自由載子之間，對材料特性所造成的影響。

從XRD頻譜中，可看出鋁摻雜的樣品，隨著雷射能量密度不段的疊加，主峰旁由缺陷所引起的峰胞，逐漸的往高角度偏移，並且融入主峰中；由FTIR頻譜可知，使用150發的複合式能量密度去執行雷射退火，可以部份修復因離子佈值所造成的晶格缺陷；Raman頻譜可看出經過熱退火的樣品，可有效提升樣品表面結晶性；Hall effect measurement可得知各樣品的載子濃度。

光學量測分析完後，使用濺鍍機濺鍍上74.3nm的ZrO2，成功製作五種不同面積的金氧半電容元件，分析其在不同離子佈植下及不同形式退火下，其MOS-C介面特性在C-V及J-E (Leakage current density – Electric field) 所造成的影響。

C-V圖譜顯示，各個樣品都有隨著電容面積的變化，有平帶電壓偏移的現象； J-E (Leakage current density – Electric field) 圖譜結果顯示，未退火的樣品以及經過雷射退火的樣品持續的有漏電流發生，而本質生長的以及經過熱退火的樣品，因介面接觸品質較好，可以有效降低漏電流密度。

關鍵字：金氧半電容、立方碳化矽、二氧化鋯、準分子雷射、X光粉末繞射儀、傅立葉轉換紅外線光譜儀、拉曼光譜儀、霍爾量測、晶格缺陷、雷射退火

關鍵字

金氧半電容 ； 立方碳化矽 ； 二氧化鋯 ； 準分子雷射 ； X光粉末繞射儀 ； 傅立葉轉換紅外線光譜儀 ； 拉曼光譜儀 ； 霍爾量測 ； 晶格缺陷 ； 雷射退火

並列摘要

This thesis aims to analyze the material properties of cubic silicon carbide (3C-SiC) and study the effects of internal lattice in different ion implantation and annealing conditions. This research used the 3C-SiC samples as substrate and high dielectric constant (high - κ) material zirconium dioxide (ZrO2) as insulation layer to produce the cubic silicon carbide metal oxide semiconductor – capacitor (3C-SiC MOS-C). SiC has superior material properties such as wide band, high thermal conductivity, and high breakdown field. Those make it an unparalleled advantage in the high-voltage and temperature semiconductor components. ZrO2 has a wide bandgap and high dielectric constant (κ = 25-29) , so it can prevent the current tunneling effect and reduce the leakage current density with the higher equivalent oxide thickness.Therefore, this material is used to product the dielectric layer in MOS-C in this research.

The pulsed KrF excimer laser treatment with composite energy density and number of shots have been applied for the post-implant anneals in the non-annealed samples to recover the crystal defects caused by the high-dose ion implantation. And then the laser-annealed samples are compared with the samples of as-grown, non-annealed and thermal-annealed. Many optical measurement technology, such as XRD, FTIR, Raman scattering and Hall effect measurement, are used to analyze the as-grown and Al-, N-, and P-implanted 3C-SiC samples in the conditions of non-annealed, laser-annealed and thermal- annealed. This is used to figure out the effects on the properties of materials caused by the lattice structure and free carriers.

From the XRD spectrum, Al-implanted samples with laser annealing can be shifted to higher 2θ angles and merged with the major peak at higher energy densities. From the FTIR spectrum, this damage caused by ion implantation can be partially recovered by around 150 shots of laser pulses at various energy densities. From the Raman spectrum, the thermal-annealed samples can effeciently enhance the surface crystallinity. Besides, Hall effect measurements reveals the carrier concentration in each samples.

After finishing the optical measurements, this research takes the as-grown, Al-, N-, and P-implanted samples with non-annealed, laser-annealed and thermal-annealed to sputter the high-κ dielectric material ZrO2 on surface with the thickness of 74.3 nm. Therefore, five different areas of the MOS capacitor components were produced successfully. This theis analyzes the impact of the MOS-C interface with the different ion implantation and annealing condition from the C-V and J-E (Leakage current density - Electric field) graphs.

C-V graphs show the shift of flat-band voltage with the changes of the capacitor area in each 3C-SiC samples. The J-E graphs show the continuous leakage current in non-annealed and laser-annealed samples. However the as-grown sample and the thermal-annealed samples can effectively reduce the leakage current density with the better interface contact quality.

Keywords: metal oxide semiconductor – capacitor (MOS-C), cubic silicon carbide (3C-SiC), zirconium dioxide (ZrO2), eximer laser, X-Ray powder Diffractometer (XRD), Fourier Transform Infrared (FTIR), Raman spectroscopy, Hall effect measurement, Lattice defect, laser anneal

並列關鍵字

metal oxide semiconductor – capacitor (MOS-C) ； cubic silicon carbide (3C-SiC) ； zirconium dioxide (ZrO2) ； eximer laser ； X-Ray powder Diffractometer (XRD) ； Fourier Transform Infrared (FTIR) ； Raman spectroscopy ； Hall effect measurement ； Lattice defect ； laser anneal

參考文獻

[3] H. X. Zhang, P. X. Feng, V. Makarov, B. R. Weiner, and G. Morell, "Synthesis of nanostructured SiC using the pulsed laser deposition technique," Materials Research Bulletin, vol. 44, pp. 184-188, 2009.

[4] Z. C. Feng, "Optical properties of cubic SiC grown on Si substrate by chemical vapor deposition," Microelectronic Engineering, vol. 83, pp. 165-169, 2006.

[5] H.S.Lee, High power bipolar Junction Transistor in Silicon Carbide, 2005.

[7] C. Locke, Growth of 3C-SiC on (111)Si using hot-wall chemical vapor deposition, 1 ed.: University of South Florida, 2009.

[8] Wikipedia, "Dielectric strength," ed.