CN114566551A - 一种宽沟槽大功率肖特基二极管及其制备方法 - Google Patents
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Abstract
本发明提供了一种宽沟槽大功率肖特基二极管及其制备方法,所述肖特基二极管包括阴极金属、设置在所述阴极金属上端的硅衬底、设置在所述硅衬底上端的第一硅外延层、设置在所述第一硅外延层上端的阳极金属、二氧化硅保护层。本发明的肖特基二极管及其制备方法,能够适应于中小型企业的生产制备,在保证不影响肖特基二极管正向导通功率大小的前提下,还能填充更多的多晶硅,以提升肖特基二极管的ESD和抗浪涌电流能力。
Description
技术领域
本发明涉及肖特基二极管技术领域,具体涉及一种宽沟槽大功率肖特基二极管及其制备方法。
背景技术
肖特基二极管是以其发明人肖特基博士命名的,一般是指平面型肖特基势垒二极管。自从平面肖特基二极管产生以来,就受到了人们的关注。平面肖特基二极管具有优异的高频特性和较低的正向开启电压,这些独特的性质使得其在太阳能电池、开关电源、汽车以及手机等多个领域都有着较大的应用潜力。但是,在反向偏压下,镜像力使势垒降低的效应,导致了平面肖特基二极管存在阻断能力差的缺点。
沟槽型肖特基二极管是在平面型二极管的基础上,利用了金属-半导体-硅的MOS效应而发明出来的沟槽型肖特基势垒二极管。其主要特点是随着反向电压升高,通过MOS效应,沟槽之间提前夹断,电场强度在到达硅表面之前,降为零,避免在表面击穿,提高了阻断能力。另外,其相对于平面二极管还有着其它不可比拟的优势,主要表现在ESD和抗浪涌电流能力增强,更小的芯片面积,相同的衬底和金属条件下,反向漏电流较低,Vf较低等。
目前,沟槽型肖特基二极管的普遍存在以下问题:①中小型企业受限于技术的不成熟以及刻蚀工艺的局限性,沟槽的深度普遍不高于15um;②部分厂商为了提升肖特基二极管的 ESD和抗浪涌电流能力,通常采用加大沟槽宽度的手段,以填充更多的多晶硅,而沟槽直接与阳极金属连接,由于沟槽太宽,牺牲了阳极金属与硅外延层接触形成的肖特基势垒面积,即影响了沟槽型肖特基二极管正向导通功率大小。因此,亟需一种肖特基二极管,能够适应于中小型企业的生产制备,在保证不影响沟槽型肖特基二极管正向导通功率大小的前提下,还能填充更多的多晶硅,以提升肖特基二极管的ESD和抗浪涌电流能力。
发明内容
针对以上问题,本发明提供一种宽沟槽大功率肖特基二极管及其制备方法,能够适应于中小型企业的生产制备,在保证不影响肖特基二极管正向导通功率大小的前提下,还能填充更多的多晶硅,以提升肖特基二极管的ESD和抗浪涌电流能力。
为实现上述目的,本发明通过以下技术方案来解决:
一种宽沟槽大功率肖特基二极管,所述肖特基二极管包括阴极金属、设置在所述阴极金属上端的硅衬底、设置在所述硅衬底上端的第一硅外延层、设置在所述第一硅外延层上端的阳极金属、二氧化硅保护层;
所述第一硅外延层上端形成有多个沟槽,所述沟槽包括第一填充区域、位于所述第一填充区域上侧的第二填充区域,所述第一填充区域内填充有多晶硅,所述第二填充区域内填充有第二硅外延层,所述第二硅外延层内侧形成有向下凹陷的避让槽,所述阳极金属上形成有多个向下弯折的接触部,所述接触部固定在所述避让槽内并且其底部与所述多晶硅上端连接。
具体的,所述沟槽的宽度为L,所述接触部底部的宽度为D,L≥2D。
具体的,所述沟槽的宽度不小于0.7μm。
具体的,所述沟槽的深度为H,H<10μm。
具体的,所述第一硅外延层上端经过掺硼后形成P型保护环,所述P型保护环位于所述阳极金属边缘下方。
一种肖特基二极管的制备方法,包括以下步骤:
S1准备硅衬底,在硅衬底上生长第一硅外延层,在第一硅外延层上端生长掩蔽层,经过光刻、刻蚀后形成多个沟槽,去除掩蔽层;
S2在沟槽内先填充多晶硅;
S3在多晶硅上端再生长第二硅外延层;
S4在第二硅外延层上端生长掩蔽层,经过光刻、刻蚀后形成向下凹陷的避让槽;
S5在第一硅外延层上端生长一层二氧化硅保护层;
S6刻蚀去除二氧化硅保护层中部;
S7在二氧化硅保护层中部沉积一层阳极金属,在硅衬底下端沉积一层阴极金属。
具体的,完成步骤S1/S2/S3/S4/S6后,还需要对硅外延层上端扩散硼,使述阳极金属边缘下方形成P型保护环。
本发明的有益效果是:
本发明的肖特基二极管及其制备方法,将沟槽分成第一填充区域和第二填充区域,在第一填充区域内填充有多晶硅,在第二填充区域内填充有第二硅外延层,并使第二硅外延层内侧形成有向下凹陷的避让槽,将阳极金属上的接触部固定在避让槽内并且底部与多晶硅上端连接,对于无法刻蚀深沟槽的中小型企业的来说,也能够实现生产制备,在保证不影响肖特基二极管正向导通功率大小的前提下,加大沟槽的宽度,还能填充更多的多晶硅,以提升肖特基二极管的ESD和抗浪涌电流能力。
附图说明
图1为本发明的肖特基二极管的结构示意图。
图2为本发明的肖特基二极管的制备流程图。
附图标记为:阴极金属1、硅衬底2、第一硅外延层3、阳极金属4、二氧化硅保护层5、沟槽6、多晶硅7、第二硅外延层8、避让槽9、接触部10、P型保护环11。
具体实施方式
下面结合实施例和附图对本发明作进一步详细的描述,但本发明的实施方式不限于此。
如图1所示:一种宽沟槽大功率肖特基二极管,肖特基二极管包括阴极金属1、设置在阴极金属1上端的硅衬底2、设置在硅衬底2上端的第一硅外延层3、设置在第一硅外延层3上端的阳极金属4、二氧化硅保护层5;第一硅外延层3上端形成有多个沟槽6,沟槽6包括第一填充区域、位于第一填充区域上侧的第二填充区域,第一填充区域内填充有多晶硅7,第二填充区域内填充有第二硅外延层8,第二硅外延层8内侧形成有向下凹陷的避让槽9,阳极金属4上形成有多个向下弯折的接触部10,接触部10固定在避让槽9内并且其底部与多晶硅7上端连接,阳极金属4与第一硅外延层3的接触面形成肖特基势垒,接触部10下端两侧面与第二硅外延层8的接触面形成肖特基势垒。
优选的,沟槽6的宽度为L,接触部10底部的宽度为D,L≥2D。
优选的,沟槽6的宽度不小于0.7μm。
优选的,沟槽6的深度为H,H<10μm。
优选的,第一硅外延层3上端经过掺硼后形成P型保护环11,P型保护环11位于阳极金属4边缘下方。
如图2所示:一种肖特基二极管的制备方法,包括以下步骤:
S1准备硅衬底2,在硅衬底2上生长第一硅外延层3,在第一硅外延层3上端生长掩蔽层,经过光刻、刻蚀后形成多个沟槽6,去除掩蔽层;
S2在沟槽6内先填充多晶硅7;
S3在多晶硅7上端再生长第二硅外延层8;
S4在第二硅外延层8上端生长掩蔽层,经过光刻、刻蚀后形成向下凹陷的避让槽9;
S5在第一硅外延层3上端生长一层二氧化硅保护层5;
S6刻蚀去除二氧化硅保护层5中部;
S7在二氧化硅保护层5中部沉积一层阳极金属4,在硅衬底2下端沉积一层阴极金属1。
以上实施例仅表达了本发明的1种实施方式,其描述较为具体和详细,但并不能因此而理解为对本发明专利范围的限制。应当指出的是,对于本领域的普通技术人员来说,在不脱离本发明构思的前提下,还可以做出若干变形和改进,这些都属于本发明的保护范围。因此,本发明专利的保护范围应以所附权利要求为准。
Claims (7)
1.一种宽沟槽大功率肖特基二极管,所述肖特基二极管包括阴极金属(1)、设置在所述阴极金属(1)上端的硅衬底(2)、设置在所述硅衬底(2)上端的第一硅外延层(3)、设置在所述第一硅外延层(3)上端的阳极金属(4)、二氧化硅保护层(5),其特征在于:
所述第一硅外延层(3)上端形成有多个沟槽(6),所述沟槽(6)包括第一填充区域、位于所述第一填充区域上侧的第二填充区域,所述第一填充区域内填充有多晶硅(7),所述第二填充区域内填充有第二硅外延层(8),所述第二硅外延层(8)内侧形成有向下凹陷的避让槽(9),所述阳极金属(4)上形成有多个向下弯折的接触部(10),所述接触部(10)固定在所述避让槽(9)内并且其底部与所述多晶硅(7)上端连接。
2.根据权利要求1所述的一种宽沟槽大功率肖特基二极管,其特征在于,所述沟槽(6)的宽度为L,所述接触部(10)底部的宽度为D,L≥2D。
3.根据权利要求1所述的一种宽沟槽大功率肖特基二极管,其特征在于,所述沟槽(6)的宽度不小于0.7μm。
4.根据权利要求1所述的一种宽沟槽大功率肖特基二极管,其特征在于,所述沟槽(6)的深度为H,H<10μm。
5.根据权利要求1所述的一种宽沟槽大功率肖特基二极管,其特征在于,所述第一硅外延层(3)上端经过掺硼后形成P型保护环(11),所述P型保护环(11)位于所述阳极金属(4)边缘下方。
6.一种如权利要求1~5任意一项所述肖特基二极管的制备方法,其特征在于,包括以下步骤:
S1准备硅衬底(2),在硅衬底(2)上生长第一硅外延层(3),在第一硅外延层(3)上端生长掩蔽层,经过光刻、刻蚀后形成多个沟槽(6),去除掩蔽层;
S2在沟槽(6)内先填充多晶硅(7);
S3在多晶硅(7)上端再生长第二硅外延层(8);
S4在第二硅外延层(8)上端生长掩蔽层,经过光刻、刻蚀后形成向下凹陷的避让槽(9);
S5在第一硅外延层(3)上端生长一层二氧化硅保护层(5);
S6刻蚀去除二氧化硅保护层(5)中部;
S7在二氧化硅保护层(5)中部沉积一层阳极金属(4),在硅衬底(2)下端沉积一层阴极金属(1)。
7.根据权利要求6所述的一种肖特基二极管的制备方法,其特征在于,完成步骤S1/S2/S3/S4/S6后,还需要对硅外延层上端扩散硼,使述阳极金属(4)边缘下方形成P型保护环(11)。
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CN109037354A (zh) * | 2018-08-03 | 2018-12-18 | 深圳市晶相技术有限公司 | 肖特基二极管及其制作方法 |
CN113130624A (zh) * | 2021-03-26 | 2021-07-16 | 先之科半导体科技(东莞)有限公司 | 一种低损耗肖特基整流管及其成型工艺 |
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US5365102A (en) * | 1993-07-06 | 1994-11-15 | North Carolina State University | Schottky barrier rectifier with MOS trench |
CN205900555U (zh) * | 2016-08-12 | 2017-01-18 | 淄博汉林半导体有限公司 | 一种大导电面积高效率的沟槽式肖特基芯片 |
CN109037354A (zh) * | 2018-08-03 | 2018-12-18 | 深圳市晶相技术有限公司 | 肖特基二极管及其制作方法 |
CN113130624A (zh) * | 2021-03-26 | 2021-07-16 | 先之科半导体科技(东莞)有限公司 | 一种低损耗肖特基整流管及其成型工艺 |
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