GaN基垂直功率器件击穿机理与新结构研究
发布时间：2018-10-30 16:08
【摘要】：目前全球的半导体产业发展如火如荼,特别是近年来在全球能源短缺、环境恶化等考验下,GaN基垂直结构是实现高电压大电流器件的最佳选择,不会受到因薄膜表面质量差而引起的热问题,可以在晶片上提供较多的管芯,能够满足工业领域对大功率、低功耗的需求。本文简要叙述了GaN材料的基本性质,并对GaN垂直功率二极管的工作机制做了分析,重点探讨了影响垂直器件优值的结构参数,并对横向和垂直二极管做了详细对比,指出了垂直二极管的优势以及横向二极管的不足,接着提出了两种新型耐压结构:新型电荷补偿结构、高/低K复合介质层耐压结构,经过仿真计算可知,新结构均可以明显提升器件击穿电压的同时具有低导通电阻。本论文针对pn结边缘电场线集中而导致器件提前击穿以及n型GaN体内电场分布不均的问题,提出一种新型的GaN基垂直功率二极管,该垂直二极管具有电荷补偿结构,其可以利用负的固定电荷可以引起n型半导体界面形成反型层,产生高浓度的空穴扩展了体内耗尽区宽度,大幅度提升了击穿电压。经仿真优化验证,结果表明在n型GaN厚度为17.5μm,掺杂浓度为2×1016cm-3时实现了功率二极管的击穿电压5965V、导通电阻为1.52mΩ·cm~2,接近GaN材料的极限。该新结构工艺可行性尚需时间验证,但是却为高功率GaN基垂直二极管的研究设计提供了新的思路。为了进一步提升器件的性能,并基于现有的工艺条件,本文提出了一种具有高/低K复合介质层的GaN基垂直功率二极管,复合介质层结构具有一层介电常数较高的介质层和多层介电常数较低的介质层,并沿电流方向交替排列形成。不同介质层之间的介电常数不同,从而引起电场分布在介质层界面不连续,这将会将会影响pn结内的电场分布,可以有效降低pn结结面处电场峰值,而远离pn结结面的电场可以得到明显提升,从而使二极管体内中电场分布变得均匀,因此能够显著提高器件的反向耐压能力。仿真优化结果表明在n型GaN厚度为34.5μm,掺杂浓度为1×1016cm-3时击穿电压达到10650V,相比常规结构,耐压提升了近216%,而且导通电阻仅为5.83mΩ·cm~2,平均击穿电场强度达到3.1MV/cm,功率优值达到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.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN31
本文编号：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.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN31
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，本文编号：2300491
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