CN114695112A - 一种氮化镓肖特基势垒二极管及制备方法 - Google Patents
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- 239000000377 silicon dioxide Substances 0.000 claims description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 6
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Abstract
一种氮化镓肖特基势垒二极管及制备方法,涉及氮化镓功率半导体器件。包括基板、过渡层、漂移层、有源区、漂移通道、场板和金属电极层;有源区包括依次相接的漂移层和有源区第一半导体层;有源区第一半导体层、漂移层和两个漂移通道构成一个环状的漂移区结构,相对于仅有横向漂移区的横向型氮化镓肖特基势垒二极管结构或者仅有垂直漂移区的垂直型氮化镓肖特基势垒二极管结构,漂移区的路径总长度大于制作在相同基板及外延层尺寸的横向型器件结构,由此增大氮化镓肖特基势垒二极管的阻断电压。本案具有提高器件的阻断电压,同时使阳极电极、阴极电极和场板电极汇集于器件结构的顶面,形成共面的器件输入输出电极结构,便于器件平面集成等特点。
Description
技术领域
本发明涉及氮化镓功率半导体器件,尤其是一种高阻断电压的氮化镓肖特基势垒二极管及制备方法,属于电力电子器件技术领域。
背景技术
作为第三代半导体典型代表的氮化镓材料具备禁带宽度大、击穿电场高、热导率大、电子饱和漂移速率高、抗辐射能力强等优点,氮化镓肖特基势垒二极管(SBD)因其高阻断电压、高开关速度、低功耗等优点在5G移动通信、半导体照明、消费电子等领域具有广阔的应用前景。
现行技术中的氮化镓肖特基势垒二极管主要采用基于GaN体材料的垂直型SBD 和基于AlGaN/GaN 等异质结二维电子气(2DEG) 的横向型SBD 两种结构形式。
垂直型氮化镓肖特基势垒二极管制作在同质外延的氮化镓半导体衬底上,现行技术中的垂直型氮化镓肖特基势垒二极管一般通过增加漂移区纵向厚度来提高阻断电压,实现高功率密度芯片,但氮化镓外延半导体层的缺陷密度与外延层的厚度成正比,较大厚度的氮化镓半导体外延层中的缺陷密度较大,影响了器件关键的阻断电压和反向漏电流等性能指标的提高,且现行氮化镓衬底制备技术在尺寸和成本上的不足限制了基于自支撑氮化镓衬底的氮化镓肖特基势垒二极管的制备与应用。
横向型氮化镓肖特基势垒二极管制作在异质外延的氮化镓半导体衬底上,外延基板为价格低廉的硅基板,或者碳化硅基板、蓝宝石基板。相对于垂直型氮化镓SBD,由于2DEG电子浓度高、迁移率高,基于AlGaN/GaN 异质结横向型氮化镓SBD具有接触电阻小、结电容小、截止频率高等特点,现行技术中的横向型氮化镓肖特基势垒二极管一般通过增大极间间距即增大漂移区长度的方法来获得更高的阻断电压,因此会增大器件的芯片尺寸和导通电阻,减小单位芯片面积上的有效电流密度和芯片性能,且制作在异质材料上的氮化镓半导体外延层的缺陷密度较大,影响器件关键的阻断电压、导通电阻、反向漏电流等性能指标的提高。
并且,垂直结构的氮化镓肖特基势垒二极管中的阳极电极位于器件结构的顶面,阴极电极位于器件结构的底面,或者通过制作台面结构使阴极电极位于台面底部的两侧,均为非共面的输入输出电极结构,不便于器件的平面集成及其在功率集成电路中的应用。
发明内容
本发明针对以上问题,提供了一种采用二维环形漂移区结构,增大器件结构中漂移区的长度,提高器件的阻断电压,同时使阳极电极、阴极电极和场板电极汇集于器件结构的顶面,形成共面的器件输入输出电极结构,便于器件的平面集成和在功率集成电路中应用的一种氮化镓肖特基势垒二极管及制备方法。
本发明的技术方案是:一种氮化镓肖特基势垒二极管及制备方法,包括以下步骤:
1)准备基板;
2)在基板上生长过渡层;
3)在过渡层上生长漂移层;
4)在漂移层上生长欧姆接触层;
5)采用深反应离子干法刻蚀方法刻蚀欧姆接触层和漂移层,形成漂移通道内隔离层沟槽和漂移通道外隔离层沟槽;
6)淀积绝缘氧化物填充漂移通道内隔离层沟槽和漂移通道外隔离层沟槽,形成漂移通道内隔离层和漂移通道外隔离层;
7)刻蚀两个漂移通道内隔离层,形成场板沟槽;
8)淀积场板金属层填充场板沟槽,形成场板;
9)刻蚀两个漂移通道内隔离层之间的欧姆接触层和漂移层,形成有源区凹槽;
10)在有源区凹槽内生长连通漂移层的有源区第一半导体层,并填充有源区凹槽;
11)采用光刻方法形成用于制作场板绝缘层的光刻胶掩模层;
12)淀积用于制作场板绝缘层的二氧化硅层或者氮化硅层;
13)剥离方法形成场板绝缘层;
14)采用光刻方法形成用于制作阳极电极的光刻胶掩模层;
15)淀积阳极电极金属层;
16)采用剥离方法形成阳极电极;
17)采用光刻方法形成用于制作阴极电极、场板电极的光刻胶掩模层;
18)淀积阴极电极、场板电极金属层,并采用剥离方法形成阴极电极和场板电极;
19)退火方法形成阴极电极与相应半导体层的欧姆接触。
包括基板、过渡层、漂移层、有源区、漂移通道、场板和金属电极层;
所述基板、过渡层、漂移层自下而上依次相接设置;
所述漂移通道设有两个,和所述有源区分别与漂移层的上端相接;
两个所述漂移通道分别位于有源区的两侧,并通过漂移通道内隔离层与有源区相隔离;
所述有源区包括自下而上依次相接的漂移层和有源区第一半导体层;
所述漂移通道包括自下而上依次相接的通道漂移层和漂移通道欧姆接触层以及位于通道漂移层和漂移通道欧姆接触层内外两侧的漂移通道内隔离层和漂移通道外隔离层;
所述场板设有两个;两个所述场板分别内嵌入于对应的漂移通道内隔离层中;
所述金属电极层包括阳极电极、阴极电极和场板电极;
所述阳极电极位于所述有源区的顶部并与所述有源区第一半导体层相接;
所述阴极电极位于所述漂移通道的顶部并与所述漂移通道欧姆接触层相接;
所述场板电极相接于场板的顶部,并通过场板绝缘层与有源区隔离。
所述基板为Si基板、SiC基板或蓝宝石基板。
所述过渡层包括AlN外延层。
还包括自下而上相接于AlN外延层上的AlGaN外延层。
所述有源区第一半导体层、漂移层、通道漂移层分别为N―-GaN外延层或P―-GaN外延层;
所述漂移通道欧姆接触层为N+-GaN外延层或P+-GaN外延层。
所述漂移通道内隔离层、漂移通道外隔离层和场板绝缘层分别为二氧化硅层或氮化硅层。
所述场板为Ti/Au双金属层。
所述阳极电极为Ni/Au双金属层。
所述阴极电极和场板电极分别为Ti/Al/Ti/Au多金属层或Cr/Al/Ti/Au多金属层。
本发明包括基板、过渡层、漂移层、有源区、漂移通道、场板和金属电极层;有源区包括自下而上依次相接的漂移层和有源区第一半导体层;漂移通道包括自下而上依次相接的通道漂移层和漂移通道欧姆接触层以及位于通道漂移层和漂移通道欧姆接触层内外两侧的漂移通道内隔离层和漂移通道外隔离层;有源区第一半导体层、漂移层和两个漂移通道构成一个环状的漂移区结构,相对于仅有横向漂移区的横向型氮化镓肖特基势垒二极管结构或者仅有垂直漂移区的垂直型氮化镓肖特基势垒二极管结构,本发明中的漂移区的路径总长度大于制作在相同基板及外延层尺寸的横向型器件结构或者垂直型器件结构的氮化镓肖特基势垒二极管中的漂移区的路径长度,由此增大氮化镓肖特基势垒二极管的阻断电压。本发明具有提高器件的阻断电压,同时使阳极电极、阴极电极和场板电极汇集于器件结构的顶面,形成共面的器件输入输出电极结构,便于器件的平面集成和在功率集成电路中应用等特点。
附图说明
图1是本发明的结构示意图,
图2是本发明步骤4的结构示意图,
图3是本发明步骤6的结构示意图,
图4是本发明步骤8的结构示意图,
图5是本发明步骤10的结构示意图,
图6是本发明步骤13的结构示意图,
图7是本发明步骤18的结构示意图。
具体实施方式
下面详细描述本发明的实施例,所述实施例的示例在附图中示出,其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的,仅用于解释本发明,而不能理解为对本发明的限制。
本发明如图1-7所示,一种氮化镓肖特基势垒二极管及制备方法,包括以下步骤:
1)准备6英寸Si基板或者SiC基板或者蓝宝石基板;
2)采用金属有机化学气相沉积(MOCVD)方法在基板上生长0.5μm厚的AlN过渡层;
3)采用MOCVD方法在过渡层上生长8μm厚的N―-GaN漂移层,Si掺杂浓度为1x1016cm-3;
4)采用MOCVD方法在漂移层上生长1μm厚的N+-GaN欧姆接触层,Si掺杂浓度为6x1019 cm-3;如图2所示;
5)采用反应离子刻蚀(RIE)或者感应耦合等离子体(ICP)等深离子干法刻蚀方法刻蚀N+-GaN欧姆接触层和N―-GaN漂移层,形成漂移通道内隔离层沟槽和漂移通道外隔离层沟槽;
6)采用等离子体增强化学气相沉积(PECVD)方法淀积绝缘氧化物(SiO2)填充漂移通道内隔离层沟槽和漂移通道外隔离层沟槽,形成漂移通道内隔离层和漂移通道外隔离层;如图3所示;
7)采用RIE或者ICP方法刻蚀两个漂移通道内隔离层,形成场板沟槽;
8)采用电子束溅射或者磁控溅射方法淀积Ti/Au填充场板沟槽,形成场板;如图4所示;
9)采用RIE或者ICP方法刻蚀两个漂移通道内隔离层之间的N+-GaN欧姆接触层和部分N―-GaN漂移层,形成有源区凹槽;
10)采用MOCVD方法在有源区凹槽内生长5.5μm厚的连通漂移层的N―-GaN有源区第一半导体层,并填充有源区凹槽,Si掺杂浓度为1x1016 cm-3;如图5所示;
11)采用光刻方法形成用于制作场板绝缘层的光刻胶掩模层;
12)采用低压化学气相沉积(LPCVD)方法淀积用于制作场板绝缘层的二氧化硅层或者氮化硅层;
13)剥离方法形成场板绝缘层;如图6所示;
14)采用光刻方法形成用于制作阳极电极(肖特基电极)的光刻胶掩模层;
15)采用电子束溅射或者磁控溅射的方法淀积Ni/Au多金属层;
16)采用剥离方法形成阳极电极(肖特基电极);
17)采用光刻方法形成用于制作阴极电极、场板电极的光刻胶掩模层;
18)采用电子束溅射或者磁控溅射的方法淀积Ti/Al/Ti/Au多金属层,并采用剥离方法形成阴极电极和场板电极;如图7所示;
19)采用600℃,N2气氛中退火的方法形成阴极电极与相应半导体层的欧姆接触。
一种氮化镓肖特基势垒二极管,包括基板、过渡层、漂移层、有源区、漂移通道、场板和金属电极层;
所述基板、过渡层、漂移层自下而上依次相接设置;
所述漂移通道设有两个,和所述有源区分别与漂移层的上端相接;
两个所述漂移通道分别位于有源区的两侧,并通过漂移通道内隔离层与有源区相隔离;
所述有源区包括自下而上依次相接的漂移层和有源区第一半导体层;
所述漂移通道包括自下而上依次相接的通道漂移层和漂移通道欧姆接触层以及位于通道漂移层和漂移通道欧姆接触层内外两侧的漂移通道内隔离层和漂移通道外隔离层;(图1中虚线框漂移通道应向漂移通道内隔离层方向扩展,应包括整个漂移通道内隔离层,但这样就会将场板包括进来,所以就框出了漂移通道内隔离层的一部分)
所述场板设有两个;两个所述场板分别内嵌入于对应的漂移通道内隔离层中;
所述金属电极层包括阳极电极(肖特基电极)、阴极电极和场板电极;
所述阳极电极位于所述有源区的顶部并与所述有源区第一半导体层相接;
所述阴极电极位于所述漂移通道的顶部并与所述漂移通道欧姆接触层相接;
所述场板电极相接于场板的顶部,并通过场板绝缘层与有源区隔离。
所述基板为Si基板、SiC基板或蓝宝石基板。
所述过渡层包括AlN外延层。
还包括自下而上相接于AlN外延层上的AlGaN外延层。
所述有源区第一半导体层、漂移层、通道漂移层为N―-GaN外延层,或者P―-GaN外延层;
所述漂移通道欧姆接触层为N+-GaN外延层,或者P+-GaN外延层。所述漂移通道内隔离层、漂移通道外隔离层和场板绝缘层分别为二氧化硅层或氮化硅层。
所述场板为Ti/Au双金属层。
所述阳极电极(肖特基电极)为Ni/Au双金属层。
所述阴极电极和场板电极分别为Ti/Al/Ti/Au多金属层或Cr/Al/Ti/Au多金属层。
本发明器件的工作流程:
所述本发明中的第一半导体层和阳极电极(肖特基电极)形成肖特基接触,构成本发明的氮化镓肖特基势垒二极管的功能区结构,第一半导体层同时用作漂移层,第二半导体层用作形成阴极电极的欧姆接触。正向偏置时,所述氮化镓肖特基势垒二极管导通。反向偏置时,氮化镓肖特基势垒二极管因氮化镓材料所具有的大禁带宽度、高击穿电场特点而具有较高的阻断电压,并且由于本发明特有的环状漂移区的路径总长度大于制作在相同尺寸的基板及外延层上的横向结构或者垂直件结构的氮化镓肖特基势垒二极管中漂移区的路径长度,由此进一步提高氮化镓肖特基势垒二极管的阻断电压,同时使器件的阳极电极、阴极电极和场板电极汇集于其结构的顶面,形成共面的器件输入输出电极结构,便于实现器件的平面集成以及在功率集成电路中的应用。
本发明中的有源区第一半导体层、漂移层和两个漂移通道构成一个环状的漂移区结构,相对于仅有横向漂移区的横向型氮化镓肖特基势垒二极管结构或者仅有垂直漂移区的垂直型氮化镓肖特基势垒二极管结构,本发明中的漂移区的路径总长度大于制作在相同基板及外延层尺寸的横向型器件结构或者垂直型器件结构的氮化镓肖特基势垒二极管中的漂移区的路径长度,由此增大氮化镓肖特基势垒二极管的阻断电压。
本发明中场板或者通过场板电极单独施加电位,或者连接阳极电极施加电位,或者连接阴极电极施加电位,优化环状漂移路径上的电场分布,进一步提高氮化镓肖特基势垒二极管的阻断电压。
相比于要求较长横向漂移区的横向型氮化镓肖特基势垒二极管或者要求较厚垂直漂移区的垂直型氮化镓肖特基势垒二极管,本发明特有的环状电流漂移区结构不要求较长或者较厚的氮化镓外延层,可以利用现行技术中工艺比较成熟,价格比较低廉的硅基氮化镓衬底材料制作高阻断电压的氮化镓肖特基势垒二极管,满足大规模应用的需求。
同时,本发明特有的环状电流漂移区结构,将器件的阳极电极、阴极电极和场板电极汇集在结构的顶面,即本发明的氮化镓肖特基势垒二极管具有共面的输入输出电极结构特点,便于实现器件平面集成化以及应用于功率集成电路中。
本发明中用于调整结终端电场的场板可以通过场板电极单独施加电源,或者连接阳极电极施加同一电源电位,或者连接阴极电极施加同一电源电位。
本发明的各个结构要素呈圆形或者任意多边形结构,相应地,本发明的器件芯片外形呈圆形或者任意多边形。
对于本案所公开的内容,还有以下几点需要说明:
(1)、本案所公开的实施例附图只涉及到与本案所公开实施例所涉及到的结构,其他结构可参考通常设计;
(2)、在不冲突的情况下,本案所公开的实施例及实施例中的特征可以相互组合以得到新的实施例;
以上,仅为本案所公开的具体实施方式,但本公开的保护范围并不局限于此,本案所公开的保护范围应以权利要求的保护范围为准。
Claims (10)
1.一种氮化镓肖特基势垒二极管及制备方法,其特征在于,包括以下步骤:
1)准备基板;
2)在基板上生长过渡层;
3)在过渡层上生长漂移层;
4)在漂移层上生长欧姆接触层;
5)采用深反应离子干法刻蚀方法刻蚀欧姆接触层和漂移层,形成漂移通道内隔离层沟槽和漂移通道外隔离层沟槽;
6)淀积绝缘氧化物填充漂移通道内隔离层沟槽和漂移通道外隔离层沟槽,形成漂移通道内隔离层和漂移通道外隔离层;
7)刻蚀两个漂移通道内隔离层,形成场板沟槽;
8)淀积场板金属层填充场板沟槽,形成场板;
9)刻蚀两个漂移通道内隔离层之间的欧姆接触层和漂移层,形成有源区凹槽;
10)在有源区凹槽内生长连通漂移层的有源区第一半导体层,并填充有源区凹槽;
11)采用光刻方法形成用于制作场板绝缘层的光刻胶掩模层;
12)淀积用于制作场板绝缘层的二氧化硅层或者氮化硅层;
13)剥离方法形成场板绝缘层;
14)采用光刻方法形成用于制作阳极电极的光刻胶掩模层;
15)淀积阳极电极金属层;
16)采用剥离方法形成阳极电极;
17)采用光刻方法形成用于制作阴极电极、场板电极的光刻胶掩模层;
18)淀积阴极电极、场板电极金属层,并采用剥离方法形成阴极电极和场板电极;
19)退火方法形成阴极电极与相应半导体层的欧姆接触。
2.一种氮化镓肖特基势垒二极管,其特征在于,包括基板、过渡层、漂移层、有源区、漂移通道、场板和金属电极层;
所述基板、过渡层、漂移层自下而上依次相接设置;
所述漂移通道设有两个,和所述有源区分别与漂移层的上端相接;
两个所述漂移通道分别位于有源区的两侧,并通过漂移通道内隔离层与有源区相隔离;
所述有源区包括自下而上依次相接的漂移层和有源区第一半导体层;
所述漂移通道包括自下而上依次相接的通道漂移层和漂移通道欧姆接触层以及位于通道漂移层和漂移通道欧姆接触层内外两侧的漂移通道内隔离层和漂移通道外隔离层;
所述场板设有两个;两个所述场板分别内嵌入于对应的漂移通道内隔离层中;
所述金属电极层包括阳极电极、阴极电极和场板电极;
所述阳极电极位于所述有源区的顶部并与所述有源区第一半导体层相接;
所述阴极电极位于所述漂移通道的顶部并与所述漂移通道欧姆接触层相接;
所述场板电极相接于场板的顶部,并通过场板绝缘层与有源区隔离。
3.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述基板为Si基板、SiC基板或蓝宝石基板。
4.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述过渡层包括AlN外延层。
5.根据权利要求4所述的一种氮化镓肖特基势垒二极管,其特征在于,还包括自下而上相接于AlN外延层上的AlGaN外延层。
6.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述有源区第一半导体层、漂移层、通道漂移层分别为N―-GaN外延层或P―-GaN外延层;
所述漂移通道欧姆接触层为N+-GaN外延层或P+-GaN外延层。
7.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述漂移通道内隔离层、漂移通道外隔离层和场板绝缘层分别为二氧化硅层或氮化硅层。
8.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述场板为Ti/Au双金属层。
9.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述阳极电极为Ni/Au双金属层。
10.根据权利要求2所述的一种氮化镓肖特基势垒二极管,其特征在于,所述阴极电极和场板电极分别为Ti/Al/Ti/Au多金属层或Cr/Al/Ti/Au多金属层。
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