CN113314588A - 一种具有高抗闩锁能力的iegt器件 - Google Patents

一种具有高抗闩锁能力的iegt器件 Download PDF

Info

Publication number
CN113314588A
CN113314588A CN202110518236.4A CN202110518236A CN113314588A CN 113314588 A CN113314588 A CN 113314588A CN 202110518236 A CN202110518236 A CN 202110518236A CN 113314588 A CN113314588 A CN 113314588A
Authority
CN
China
Prior art keywords
region
type
base region
emitter
iegt
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110518236.4A
Other languages
English (en)
Inventor
吴磊
陆界江
桜井建弥
李娇
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Ruiqu Microelectronics Technology Co ltd
Original Assignee
Shanghai Ruiqu Microelectronics Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Ruiqu Microelectronics Technology Co ltd filed Critical Shanghai Ruiqu Microelectronics Technology Co ltd
Priority to CN202110518236.4A priority Critical patent/CN113314588A/zh
Publication of CN113314588A publication Critical patent/CN113314588A/zh
Pending legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0684Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by the shape, relative sizes or dispositions of the semiconductor regions or junctions between the regions
    • H01L29/0692Surface layout
    • H01L29/0696Surface layout of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007Multistep manufacturing processes
    • H01L29/66075Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
    • H01L29/66227Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
    • H01L29/66234Bipolar junction transistors [BJT]
    • H01L29/66325Bipolar junction transistors [BJT] controlled by field-effect, e.g. insulated gate bipolar transistors [IGBT]
    • H01L29/66333Vertical insulated gate bipolar transistors
    • H01L29/66348Vertical insulated gate bipolar transistors with a recessed gate
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/70Bipolar devices
    • H01L29/72Transistor-type devices, i.e. able to continuously respond to applied control signals
    • H01L29/739Transistor-type devices, i.e. able to continuously respond to applied control signals controlled by field-effect, e.g. bipolar static induction transistors [BSIT]
    • H01L29/7393Insulated gate bipolar mode transistors, i.e. IGBT; IGT; COMFET
    • H01L29/7395Vertical transistors, e.g. vertical IGBT
    • H01L29/7396Vertical transistors, e.g. vertical IGBT with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions
    • H01L29/7397Vertical transistors, e.g. vertical IGBT with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Ceramic Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • Insulated Gate Type Field-Effect Transistor (AREA)

Abstract

本发明公开了一种具有高抗闩锁能力的IEGT器件,在N‑型漂移层的上方间隔设置P型基区和栅极,栅极之间设置所述浮动P区,P沟道MOSFET管设置在浮动P区,除设置有P沟道MOSFET管的P型基区以外的其它P型基区表面一侧设有P+型基区、另一侧设有N+型发射区,N+型发射区上方设有与n+型发射区连接的发射极;N‑型漂移层的下方设置N型缓冲区,N型缓冲区的下方设置所述P‑型集电极区,P‑型集电极区的下方连接集电极。本发明通过在浮动P区增加P沟道MOSFET作为空穴分流器,旁路空穴电流以降低高空穴密度,提高抗闩锁能力。

Description

一种具有高抗闩锁能力的IEGT器件
技术领域
本发明属于半导体技术领域,具体涉及一种具有高抗闩锁能力的IEGT器件。
背景技术
如今,在许多应用中都使用了采用IGBT和IEGT的功率逆变器***。特别在由电池供电的电动汽车背景下,IEGT器件的改善和功率损耗的减少变得越来越重要。功率转换器应用中最严重的问题是在同时施加高电流,高电压和高温的情况下的灾难性故障。一般而言,在IGBT和IEGT应用中,内置晶闸管的闩锁现象会导致灾难性故障,而该故障是IGBT和IEGT应用中最严重的问题。
IEGT器件闩锁现象的原因是:IEGT器件内存在寄生的晶闸管,即NPNP结构。在器件正常工作的过程中,不希望开通所述寄生的晶闸管。若所述寄生晶闸管处于开通状态,那么IEGT器件的栅极将失去对电流的控制。然而,在IEGT工作过程中,如果流过发射极下方的空穴电流太大,那么发射极和基区的PN结就会正偏,即发射极开始向基区注入电子,基区开始向源极注入空穴,此时寄生的晶闸管导通,即IGBT器件处于闩锁状态。
图1显示了常规IEGT的横截面图,图2显示了导通期间IEGT中的电流流动,很明显横向孔流来自相邻的浮动p区。高空穴电流流过n+发射极区域下方的p-和p+区域,n+发射极区域下方的p-区域的电阻产生电压降,使n+和p-区域之间的结正向偏置。当正向偏压足以促进电子从n+发射区的注入时,寄生晶闸管被触发,导致发生闩锁故障。
因此如何提高IEGT器件的抗闩锁能力是急需解决的技术问题。
发明内容
本发明的目的在于克服现有技术中的不足,提供了一种具有高抗闩锁能力的IEGT器件,在浮动P区增加P沟道MOSFET作为空穴分流器,旁路空穴电流以降低高空穴密度,提高抗闩锁能力。
为解决上述技术问题,本发明提供了一种具有高抗闩锁能力的IEGT器件,包括:发射极、N+型发射区、栅极、浮动P区、P型基区、P+型基区、P沟道MOSFET 管、N-型漂移层、N型缓冲区、P-型集电极区、以及集电极;
所述N-型漂移层的上方间隔设置所述P型基区和栅极,所述栅极之间设置所述浮动P区,所述P沟道MOSFET管设置在所述浮动P区,除设置有所述P沟道MOSFET管的所述P型基区以外的其它P型基区表面一侧设有所述P+型基区、另一侧设有所述N+型发射区,所述N+型发射区上方设有与所述N+型发射区连接的所述发射极;
所述N-型漂移层的下方设置所述N型缓冲区,所述N型缓冲区的下方设置所述P-型集电极区,所述P-型集电极区的下方连接所述集电极。
可选的,所述P沟道MOSFET管在IEGT器件的导通周期被关断,在IEGT器件的关断期间打开。
可选的,所述N+型发射区为垂直设置。
可选的,所述垂直的N+型发射区域使用CVD PSG的横向扩散技术形成。
可选的,在所述P+型基区和N+型发射区的下方布置反向P+型基区。
可选的,所述反向P+型基区使用高压离子注入。
与现有技术相比,本发明所达到的有益效果是:本发明通过在浮动P区增加P沟道MOSFET作为空穴分流器,旁路空穴电流以降低高空穴密度,提高抗闩锁能力,并且通过设置垂直的N+型发射区以缩短N+型发射区的长度,在N+型发射区下方增加反向P+型基区以降低P区的寄生电阻,进一步提高器件的抗闩锁能力。
附图说明
图1为现有技术中IEGT的横截面;
图2为现有技术中IEGT导通时的电流流向;
图3为本发明带空穴分流器的IEGT结构;
图4为本发明IEGT器件在导通和关断时的电流流向:(1)是导通时候的电流流向,(2)是关断时候的电流流向;
图5为本发明IEGT器件的工艺流程;
图6为增加反向P+区的横截面器件结构;
图7为沿图6中A-A’线施加在反向P+区的详细掺杂分布。
具体实施方式
下面结合附图对本发明作进一步描述。以下实施例仅用于更加清楚地说明本发明的技术方案,而不能以此来限制本发明的保护范围。
在本发明专利的描述中,需要说明的是,术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含,除了包含所列的那些要素,而且还可包含没有明确列出的其他要素。
在本发明专利的描述中,需要说明的是,术语“中心”、“上”、“下”、“左”、“右”、“竖直”、“水平”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系,仅是为了便于描述本发明专利和简化描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本发明专利的限制。此外,术语“第一”、“第二”、“第三”仅用于描述目的,而不能理解为指示或暗示相对重要性。
在本发明专利的描述中,需要说明的是,除非另有明确的规定和限定,术语“安装”、“相连”、“连接”应做广义理解,例如,可以是固定连接,也可以是可拆卸连接,或一体地连接;可以是机械连接,也可以是电连接;可以是直接相连,也可以通过中间媒介间接相连,可以是两个元件内部的连通。对于本领域的普通技术人员而言,可以具体情况理解上述术语在本发明专利中的具体含义。
图2显示了现有IEGT接通时的电流流向。从图2可以看出,空穴电流从p区集中到相邻的有源单元中,导致n+发射区下方p区的电压降增加。用Rb1和Rb2来表示寄生电阻,空穴电流流过这些电阻。当电压降超过n+发射极和p基区之间的p-n+结的内建电压Vbi时,寄生晶闸管发生闭锁,导致IEGT的灾难性失效。并且n+发射区长度越小,锁存电流越大。为了防止寄生晶闸管的闭锁(即提高抗闩锁能力),可以采用的技术方案有增加空穴分流器(p沟道MOSFET)、减小n+发射极长度和p区电阻。
本发明的一种具有高抗闩锁能力的IEGT器件,参见图3所示,包括:发射极、N+型发射区、栅极、浮动P区、P型基区、P+型基区、P沟道MOSFET 管、N-型漂移层、N型缓冲区、P-型集电极区、以及集电极;
所述N-型漂移层的上方间隔设置所述P型基区和栅极,所述栅极之间设置所述浮动P区,所述p 型MOSFET管设置在所述浮动P区,除设置有所述P沟道MOSFET管的所述P型基区以外的其它P型基区表面一侧设有所述P+型基区、另一侧设有所述N+型发射区,所述N+型发射区上方设有与所述N+型发射区连接的所述发射极;
所述N-型漂移层的下方设置所述N型缓冲区,所述N型缓冲区的下方设置所述P-型集电极区,所述P-型集电极区的下方连接所述集电极。
其中P沟道MOSFET 管作为空穴旁路、空穴分流器,布置在有源沟道栅极之间的浮动P区中,相对较宽的浮动P区可以在不牺牲任何性能的情况下提供空穴旁路。在IEGT器件的导通周期,图3中的附加P沟道MOSFET被关断,如图4(1)所示。在IEGT器件的关断期间,可以打开浮动P区中的附加P沟道MOSFET,P沟道MOSFET将提供空穴旁路,如图4(2)所示。在关断期间,空穴旁路的存在可以在有源单元的n+发射极区域下方实现较低的空穴电流密度。
进一步地,所述N+型发射区为垂直设置。 垂直N+型发射区域如图6所示形成,并且该结构导致使用垂直结构的非常短的N+型发射区长度,该垂直结构应用了使用来自固体源CVD PSG的横向扩散的新处理技术。图6显示了完成的横截面器件结构以及N+发射极和P+区域下方的反向P+区域。图7示出了沿图6中的A–A'线施加在反向P+区的详细掺杂分布,并实现了在N+发射区下方的较低电阻。
与传统的IGBT和IEGT相比,由横向N+发射区转变为垂直N+发射区的新型N+发射区结构在减小N+发射区长度和N+发射区下寄生电阻方面具有极大的优势。利用CVD-PSG形成的固体源扩散和自对准电极接触法。横截面图如图6所示,可以清楚地看出,准垂直n+发射极区域是使用CVD PSG的横向扩散形成的,并且使用锥形蚀刻形成具有倾斜角度的PSG和BPSG,并且它能够实现自对准电极接触。
进一步地,在P+型基区和N+型发射区的下方布置了使用高压离子注入的反向P+型基区。该技术的应用导致了N+型发射区下方P型基区寄生电阻的显著降低。
图5示出了实现本发明的IEGT器件的构建方法,图5表示如下的过程步骤顺序,
(a) 采用化学气相沉积法(CVD)沉积Si3N4,然后进行光刻和刻蚀;
(b) 局部氧化SiO2生长;
(c) 用RIE(反应离子腐蚀技术)进行氧化物刻蚀和用CDE(化学干法刻蚀技术)进行浅Si刻蚀;
(d) 采用RIE和H2退火进行Si沟道刻蚀,获得沟道顶部和底部的软角;
(e) 牺牲SiO2生长,刻蚀出SiO2,形成栅氧化层,然后进行掺杂多晶硅沉积;
(f) 多晶硅和栅极SiO2的刻蚀直至设计深度在硅表面下1μm左右;
(g) PSG(磷硅玻璃)、BPSG(硼磷硅玻璃)和Si3N4沉积;
(h) 无需任何光刻工艺的Si3N4 RIE蚀刻;
(i) PSG和BPSG采用逐渐改变刻蚀速率的锥形干法刻蚀,然后采用BPSG回流工艺进行n+型发射区扩散,并采用干法刻蚀去除接触区中的残余氧化物,采用溅射沉积Al-Si-Cu电极。
本发明的IEGT器件进行试验,得到作为P沟道MOSFET的空穴分流器布置在浮动P区,使RBSOA(反向偏置安全工作区)的耐压性能提高了约35%。在FBSOA(正向偏置安全工作区)和SCSOA(短路安全工作区)测试中,缩短N+发射极长度和降低N+发射极下的P区寄生电阻可以提高30%左右。在FBSOA和SCSOA测试中,反向扩散的p+基区获得了25%的改善。总的来说,SOA测试的改进比传统的IGBT和IEGT提高了25-35%。
以上所述仅是本发明的优选实施方式,应当指出,对于本技术领域的普通技术人员来说,在不脱离本发明技术原理的前提下,还可以做出若干改进和变型,这些改进和变型也应视为本发明的保护范围。

Claims (6)

1. 一种具有高抗闩锁能力的IEGT器件,其特征是,包括:发射极、N+型发射区、栅极、浮动P区、P型基区、P+型基区、P沟道MOSFET 管、N-型漂移层、N型缓冲区、P-型集电极区、以及集电极;
所述N-型漂移层的上方间隔设置所述P型基区和栅极,所述栅极之间设置所述浮动P区,所述P沟道MOSFET管设置在所述浮动P区内,除设置有所述P沟道MOSFET管的所述P型基区以外的其它P型基区表面一侧设有所述P+型基区、另一侧设有所述N+型发射区,所述N+型发射区上方设有与所述N+型发射区连接的所述发射极;
所述N-型漂移层的下方设置所述N型缓冲区,所述N型缓冲区的下方设置所述P-型集电极区,所述P-型集电极区的下方连接所述集电极。
2.根据权利要求1所述的一种具有高抗闩锁能力的IEGT器件,其特征是,所述P沟道MOSFET管在IEGT器件的导通周期关断,在IEGT器件的关断期间打开。
3.根据权利要求1所述的一种具有高抗闩锁能力的IEGT器件,其特征是,所述N+型发射区为垂直设置。
4. 根据权利要求3所述的一种具有高抗闩锁能力的IEGT器件,其特征是,所述垂直的N+型发射区域使用CVD PSG的横向扩散技术形成。
5.根据权利要求1所述的一种具有高抗闩锁能力的IEGT器件,其特征是,在所述P+型基区和N+型发射区的下方布置反向P+型基区。
6.根据权利要求5所述的一种具有高抗闩锁能力的IEGT器件,其特征是,所述反向P+型基区使用高压离子注入。
CN202110518236.4A 2021-05-12 2021-05-12 一种具有高抗闩锁能力的iegt器件 Pending CN113314588A (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110518236.4A CN113314588A (zh) 2021-05-12 2021-05-12 一种具有高抗闩锁能力的iegt器件

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110518236.4A CN113314588A (zh) 2021-05-12 2021-05-12 一种具有高抗闩锁能力的iegt器件

Publications (1)

Publication Number Publication Date
CN113314588A true CN113314588A (zh) 2021-08-27

Family

ID=77373097

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110518236.4A Pending CN113314588A (zh) 2021-05-12 2021-05-12 一种具有高抗闩锁能力的iegt器件

Country Status (1)

Country Link
CN (1) CN113314588A (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117476757A (zh) * 2023-12-28 2024-01-30 深圳天狼芯半导体有限公司 一种具有高抗闩锁能力的igbt及制备方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117476757A (zh) * 2023-12-28 2024-01-30 深圳天狼芯半导体有限公司 一种具有高抗闩锁能力的igbt及制备方法

Similar Documents

Publication Publication Date Title
US8564097B2 (en) Reverse conducting IGBT
CN104465734A (zh) 绝缘栅双极型晶体管及其制造方法
US20150187877A1 (en) Power semiconductor device
WO2020151088A1 (zh) 一种极低反向恢复电荷超结功率vdmos
JPH0730105A (ja) 半導体装置
CN213459736U (zh) 一种SiC IGBT器件
CN115020479B (zh) 一种耗尽型碳化硅双极器件结构及制作方法
CN117476774B (zh) 垂直型碳化硅晶体管的结构、制造方法及电子设备
CN117497600B (zh) 超结碳化硅晶体管的结构、制造方法及电子设备
CN117497579B (zh) 碳化硅igbt的结构、制造方法及电子设备
CN113314588A (zh) 一种具有高抗闩锁能力的iegt器件
JPH03155677A (ja) 伝導度変調型mosfet
US20220157976A1 (en) Semiconductor device and semiconductor apparatus
JP2002261281A (ja) 絶縁ゲートバイポーラトランジスタの製造方法
CN107134488B (zh) 一种载流子存储增强的绝缘栅双极型晶体管
CN117497601A (zh) 平面型碳化硅晶体管的结构、制造方法及电子设备
CN217426757U (zh) 一种具有高抗闩锁能力的iegt器件
JP3935343B2 (ja) 絶縁ゲート型バイポーラトランジスタ及びその製造方法
JP2000164859A (ja) 半導体装置及びその製造方法
JP2000183340A (ja) 半導体装置およびその駆動方法
JPH023980A (ja) 縦型電界効果トランジスタ
JP2009176891A (ja) 半導体装置
CN112216694B (zh) 一种SiC IGBT器件及其制备方法
CN112018162B (zh) 一种4H-SiC侧栅集成SBD MOSFET器件及其制备方法
JP2003218354A (ja) 半導体装置およびその製造方法

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
CB03 Change of inventor or designer information
CB03 Change of inventor or designer information

Inventor after: Lu Jiejiang

Inventor after: Wu Lei

Inventor after: Li Jiao

Inventor before: Wu Lei

Inventor before: Lu Jiejiang

Inventor before: Jianmi Sakai

Inventor before: Li Jiao