GaN基垂直功率器件擊穿機理與新結構研究
發(fā)布時間：2018-10-30 16:08
【摘要】：目前全球的半導體產(chǎn)業(yè)發(fā)展如火如荼,特別是近年來在全球能源短缺、環(huán)境惡化等考驗下,GaN基垂直結構是實現(xiàn)高電壓大電流器件的最佳選擇,不會受到因薄膜表面質(zhì)量差而引起的熱問題,可以在晶片上提供較多的管芯,能夠滿足工業(yè)領域?qū)Υ蠊β�、低功耗的需求。本文簡要敘述了GaN材料的基本性質(zhì),并對GaN垂直功率二極管的工作機制做了分析,重點探討了影響垂直器件優(yōu)值的結構參數(shù),并對橫向和垂直二極管做了詳細對比,指出了垂直二極管的優(yōu)勢以及橫向二極管的不足,接著提出了兩種新型耐壓結構:新型電荷補償結構、高/低K復合介質(zhì)層耐壓結構,經(jīng)過仿真計算可知,新結構均可以明顯提升器件擊穿電壓的同時具有低導通電阻。本論文針對pn結邊緣電場線集中而導致器件提前擊穿以及n型GaN體內(nèi)電場分布不均的問題,提出一種新型的GaN基垂直功率二極管,該垂直二極管具有電荷補償結構,其可以利用負的固定電荷可以引起n型半導體界面形成反型層,產(chǎn)生高濃度的空穴擴展了體內(nèi)耗盡區(qū)寬度,大幅度提升了擊穿電壓。經(jīng)仿真優(yōu)化驗證,結果表明在n型GaN厚度為17.5μm,摻雜濃度為2×1016cm-3時實現(xiàn)了功率二極管的擊穿電壓5965V、導通電阻為1.52mΩ·cm~2,接近GaN材料的極限。該新結構工藝可行性尚需時間驗證,但是卻為高功率GaN基垂直二極管的研究設計提供了新的思路。為了進一步提升器件的性能,并基于現(xiàn)有的工藝條件,本文提出了一種具有高/低K復合介質(zhì)層的GaN基垂直功率二極管,復合介質(zhì)層結構具有一層介電常數(shù)較高的介質(zhì)層和多層介電常數(shù)較低的介質(zhì)層,并沿電流方向交替排列形成。不同介質(zhì)層之間的介電常數(shù)不同,從而引起電場分布在介質(zhì)層界面不連續(xù),這將會將會影響pn結內(nèi)的電場分布,可以有效降低pn結結面處電場峰值,而遠離pn結結面的電場可以得到明顯提升,從而使二極管體內(nèi)中電場分布變得均勻,因此能夠顯著提高器件的反向耐壓能力。仿真優(yōu)化結果表明在n型GaN厚度為34.5μm,摻雜濃度為1×1016cm-3時擊穿電壓達到10650V,相比常規(guī)結構,耐壓提升了近216%,而且導通電阻僅為5.83mΩ·cm~2,平均擊穿電場強度達到3.1MV/cm,功率優(yōu)值達到19GW/cm~2。
[Abstract]:At present, the semiconductor industry in the world is developing in full swing, especially under the test of global energy shortage and environmental deterioration in recent years, GaN based vertical structure is the best choice to realize high voltage and high current devices. Without the heat problem caused by the poor surface quality of the thin film, more cores can be provided on the wafer, which can meet the demand of high power and low power consumption in the industrial field. In this paper, the basic properties of GaN materials are briefly described, and the working mechanism of GaN vertical power diodes is analyzed. The structural parameters affecting the excellent values of vertical devices are discussed, and the comparison between transverse and vertical diodes is made in detail. The advantages of vertical diodes and the shortcomings of transverse diodes are pointed out. Then two new types of voltage-resistant structures are proposed: a new charge compensation structure, a high / low K composite dielectric layer structure, and a simulation calculation. The new structure can obviously increase the breakdown voltage of the device and have low on-resistance. In this paper, a novel pn based vertical power diode with charge compensation structure is proposed to solve the problems of early breakdown and uneven electric field distribution in n-type GaN due to the concentration of the electric field line at the edge of the pn junction. The negative fixed charge can lead to the formation of a inversion layer at the n-type semiconductor interface, resulting in a high concentration of holes extending the width of the depletion region in the body and greatly increasing the breakdown voltage. The simulation results show that when the thickness of n-type GaN is 17.5 渭 m and the doping concentration is 2 脳 1016cm-3, the breakdown voltage of power diode is 5965 V and the on-resistance is 1.52m 惟 cm~2, close to the limit of GaN material. It still needs time to verify the feasibility of the new structure, but it provides a new idea for the research and design of high power GaN based vertical diodes. In order to further improve the performance of the device, and based on the existing process conditions, a GaN based vertical power diode with high / low K composite dielectric layer is proposed in this paper. The structure of composite dielectric layer has a dielectric layer with high dielectric constant and a dielectric layer with low dielectric constant and is arranged alternately along the current direction. The dielectric constant of different dielectric layers is different, which causes the electric field distribution to be discontinuous at the interface of the dielectric layer, which will affect the electric field distribution in the pn junction, and can effectively reduce the peak electric field at the junction surface of the pn junction. The electric field far away from the junction surface of pn can be obviously enhanced, so that the electric field distribution in the diode becomes uniform, so the reverse voltage resistance of the device can be improved significantly. The simulation results show that the breakdown voltage reaches 10650V when the thickness of n-type GaN is 34.5 渭 m and the doping concentration is 1 脳 1016cm-3. Compared with the conventional structure, the breakdown voltage is increased by 216m and the on-resistance is only 5.83m 惟 cm~2,. The average breakdown electric field intensity is 3.1 MV / cm, and the power excellent value is 19 GW / cm ~ 2.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN31
本文編號：2300491
[Abstract]:At present, the semiconductor industry in the world is developing in full swing, especially under the test of global energy shortage and environmental deterioration in recent years, GaN based vertical structure is the best choice to realize high voltage and high current devices. Without the heat problem caused by the poor surface quality of the thin film, more cores can be provided on the wafer, which can meet the demand of high power and low power consumption in the industrial field. In this paper, the basic properties of GaN materials are briefly described, and the working mechanism of GaN vertical power diodes is analyzed. The structural parameters affecting the excellent values of vertical devices are discussed, and the comparison between transverse and vertical diodes is made in detail. The advantages of vertical diodes and the shortcomings of transverse diodes are pointed out. Then two new types of voltage-resistant structures are proposed: a new charge compensation structure, a high / low K composite dielectric layer structure, and a simulation calculation. The new structure can obviously increase the breakdown voltage of the device and have low on-resistance. In this paper, a novel pn based vertical power diode with charge compensation structure is proposed to solve the problems of early breakdown and uneven electric field distribution in n-type GaN due to the concentration of the electric field line at the edge of the pn junction. The negative fixed charge can lead to the formation of a inversion layer at the n-type semiconductor interface, resulting in a high concentration of holes extending the width of the depletion region in the body and greatly increasing the breakdown voltage. The simulation results show that when the thickness of n-type GaN is 17.5 渭 m and the doping concentration is 2 脳 1016cm-3, the breakdown voltage of power diode is 5965 V and the on-resistance is 1.52m 惟 cm~2, close to the limit of GaN material. It still needs time to verify the feasibility of the new structure, but it provides a new idea for the research and design of high power GaN based vertical diodes. In order to further improve the performance of the device, and based on the existing process conditions, a GaN based vertical power diode with high / low K composite dielectric layer is proposed in this paper. The structure of composite dielectric layer has a dielectric layer with high dielectric constant and a dielectric layer with low dielectric constant and is arranged alternately along the current direction. The dielectric constant of different dielectric layers is different, which causes the electric field distribution to be discontinuous at the interface of the dielectric layer, which will affect the electric field distribution in the pn junction, and can effectively reduce the peak electric field at the junction surface of the pn junction. The electric field far away from the junction surface of pn can be obviously enhanced, so that the electric field distribution in the diode becomes uniform, so the reverse voltage resistance of the device can be improved significantly. The simulation results show that the breakdown voltage reaches 10650V when the thickness of n-type GaN is 34.5 渭 m and the doping concentration is 1 脳 1016cm-3. Compared with the conventional structure, the breakdown voltage is increased by 216m and the on-resistance is only 5.83m 惟 cm~2,. The average breakdown electric field intensity is 3.1 MV / cm, and the power excellent value is 19 GW / cm ~ 2.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN31
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相關期刊論文 前1條
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相關碩士學位論文 前1條
1 劉東;垂直AlGaN/GaN HFETs耐壓機理與新結構研究[D];電子科技大學;2016年
，本文編號：2300491
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