CN110246783B - 一种去胶机夹持主轴 - Google Patents

一种去胶机夹持主轴 Download PDF

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CN110246783B
CN110246783B CN201910496414.0A CN201910496414A CN110246783B CN 110246783 B CN110246783 B CN 110246783B CN 201910496414 A CN201910496414 A CN 201910496414A CN 110246783 B CN110246783 B CN 110246783B
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傅立超
魏子尧
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Ningbo All Semi Micro Electronics Equipment Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/687—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches
    • H01L21/68714—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/687—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches
    • H01L21/68714—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support
    • H01L21/68721—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support characterised by edge clamping, e.g. clamping ring

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Abstract

本发明提供一种去胶机夹持主轴，包括气缸、气缸座、主轴安装板、主轴筒、主轴、顶杆、夹持轴套、夹持升降套和晶圆；所述气缸固定安装在所述气缸座下端；所述主轴安装板固定安装在所述气缸座上端；所述主轴筒固定安装在所述主轴安装板上；所述主轴可转动的设置在所述主轴筒内；所述主轴内设置有上下贯穿的第一通孔。本发明能实现快速夹紧或者松开，点夹持保证晶圆的准确定位不会发生位置偏移，还能实现微调夹紧力，充氮气防止主轴发生损坏。

Description

一种去胶机夹持主轴
技术领域
本发明涉及半导体设备技术领域，尤其涉及一种去胶机夹持主轴。
背景技术
晶圆是指硅半导体集成电路制作所用的硅晶片，由于其形状为圆形，故称为晶圆。去胶机是给晶圆进行去胶，去胶机主轴是非常关键的零件，现有的去胶机主轴在定位晶圆的时候一般定位不准，易发生位置偏移。
发明内容
要解决的技术问题
本发明要解决的问题是提供一种去胶机夹持主轴，以克服现有技术中定位不准，易发生位置偏移的缺陷。
技术方案
为解决所述技术问题，本发明提供一种去胶机夹持主轴，包括气缸、气缸座、主轴安装板、主轴筒、主轴、顶杆、夹持轴套、夹持升降套和晶圆；所述气缸固定安装在所述气缸座下端；所述主轴安装板固定安装在所述气缸座上端；所述主轴筒固定安装在所述主轴安装板上；所述主轴可转动的设置在所述主轴筒内；所述主轴内设置有上下贯穿的第一通孔；所述顶杆设置在所述第一通孔内，所述顶杆的下端与所述气缸的活塞杆相配合，所述顶杆的上端与所述夹持升降套固定；所述夹持轴套密封的固定在所述主轴上端；所述夹持升降套可上下滑动的设置在所述夹持轴套上端；所述气缸的活塞杆上下伸缩带动所述顶杆、夹持升降套上下移动；所述夹持升降套上设置有用于定位并夹紧所述晶圆的若干个夹紧装置。
优选的，所述夹紧装置包括夹持座、夹块、等高柱和塑料夹，所述夹持座固定安装在所述夹持轴套一侧；所述等高柱固定安装在所述夹持座上端；所述夹块一端与所述夹持升降套铰接，另一端穿过所述夹持座并与所述夹持座铰接；所述塑料夹固定安装在所述夹块上端；所述晶圆置于所述等高柱上端，所述晶圆外壁还与所述塑料夹接触。
优选的，所述夹块呈L形。
优选的，所述塑料夹呈U形。
优选的，所述去胶机夹持主轴还包括微调装置，所述微调装置包括调节柱、螺纹套、下顶套杆和复位弹簧；所述调节柱与所述螺纹套螺接；所述螺纹套螺接在所述顶杆下端；所述螺纹套与所述主轴留有间隙；所述下顶套杆与所述顶杆套接；所述下顶套杆与所述主轴过盈配合安装；所述复位弹簧设置在所述主轴下端的空腔内，所述复位弹簧上端与所述下顶套杆下端面及主轴内壁相顶，下端与所述螺纹套相顶；所述调节柱下端与所述气缸的活塞杆相配合。
优选的，所述去胶机夹持主轴还包括氮气套，所述氮气套密封(用螺钉)固定安装在所述主轴筒的下端；所述氮气套一侧密封连接有氮气接头，所述氮气接头与外部氮气相连接；所述主轴下端与所述氮气套相对应处设置有第二通孔；所述氮气套内壁设置有凹槽，所述凹槽与所述第二通孔相对应；所述第二通孔还与所述第一通孔相连通。
优选的，所述去胶机夹持主轴还包括销钉和销钉套；若干所述销钉均布固定在所述夹持轴套的上端，若干所述销钉套设置在所述夹持升降套的第三通孔内，所述销钉与所述销钉套滑动配合。
优选的，所述主轴与所述夹持轴套通过免键轴衬配合固定。
有益效果为：与现有技术相比本发明的去胶机夹持主轴，能实现快速夹紧或者松开，点夹持保证晶圆的准确定位不会发生位置偏移，还能实现微调夹紧力，充氮气防止主轴发生损坏。
附图说明
图1为本发明一种去胶机夹持主轴的结构示意图；
图2为本发明一种去胶机夹持主轴的主视图；
图3为图2中A-A方向的剖视图；
图4为图3中B的局部放大图；
图5为图3中C的局部放大图；
图6为夹持轴套、夹持升降套、销钉和销钉套的相互配合的爆炸图。
具体实施方式
下面结合附图和实施例，对本发明的具体实施方式作进一步详细描述。以下实施例用于说明本发明，但不用来限制本发明的范围。
如图3所示，本发明的一种去胶机夹持主轴，包括气缸1、气缸座2、主轴安装板3、主轴筒4、主轴5、顶杆6、夹持轴套7、夹持升降套8和晶圆9；所述气缸1用螺钉固定安装在所述气缸座2下端；所述主轴安装板3用螺钉固定安装在所述气缸座2上端；所述主轴筒4用螺钉固定安装在所述主轴安装板3上；所述主轴5可转动的设置在所述主轴筒4内；所述主轴5内设置有上下贯穿的第一通孔10；所述顶杆6设置在所述第一通孔10内，所述顶杆6的下端与所述气缸1的活塞杆相配合，所述顶杆6的上端与所述夹持升降套8通过内外螺纹固定；所述夹持轴套7密封的固定在所述主轴5上端；所述夹持升降套8可上下滑动的设置在所述夹持轴套7上端；所述气缸1的活塞杆上下伸缩带动所述顶杆6、夹持升降套8上下移动；所述夹持升降套8上设置有用于定位并夹紧所述晶圆9的若干个夹紧装置。
如图3所示，所述夹紧装置包括夹持座11、夹块12、等高柱13和塑料夹14，所述夹持座11用螺钉固定安装在所述夹持轴套7一侧；所述等高柱13插接的固定安装在所述夹持座11上端；所述夹块12一端与所述夹持升降套8铰接，另一端穿过所述夹持座11并与所述夹持座11铰接；所述塑料夹14用螺钉固定安装在所述夹块12上端；所述晶圆9置于所述等高柱13上端，所述晶圆9外壁还与所述塑料夹14接触。夹紧装置结构设计巧妙，能快速定位并夹紧晶圆9。
如图3所示，所述夹块12呈L形。所述塑料夹14呈U形。均为了快速夹紧晶圆9而设计。
如图4所示，所述去胶机夹持主轴还包括微调装置，所述微调装置包括调节柱15、螺纹套16、下顶套杆17和复位弹簧18；所述调节柱15与所述螺纹套16螺接；所述螺纹套16螺接在所述顶杆6下端；所述螺纹套16与所述主轴5留有间隙；所述下顶套杆17与所述顶杆6套接；所述下顶套杆17与所述主轴5过盈配合安装；所述复位弹簧18设置在所述主轴5下端的空腔内，所述复位弹簧18上端与所述下顶套杆17下端面及主轴5内壁相顶，下端与所述螺纹套16相顶；所述调节柱15下端与所述气缸1的活塞杆相配合。微调装置的作用是给夹紧装置进行夹紧力的微调，调节的时候，螺纹套16旋转，螺纹套16上下位移，从而带动顶杆6微微的上下升或降，从而调节夹块12的夹紧力，复位弹簧18起到快速将顶杆6复位的作用。
如图5所示，所述去胶机夹持主轴还包括氮气套19，所述氮气套19密封用螺钉固定安装在所述主轴筒4的下端；所述氮气套19一侧密封连接有氮气接头20，所述氮气接头20与外部氮气相连接；所述主轴5下端与所述氮气套19相对应处设置有第二通孔21；所述氮气套19内壁设置有凹槽22，所述凹槽22与所述第二通孔21相对应；所述第二通孔21还与所述第一通孔10相连通。主轴内冲入氮气，形成内外压差，从而液体不会进入主轴，并降低含氧量，防止发生氧气爆炸等危险事故发生。
如图1和图6所示，所述去胶机夹持主轴还包括销钉23和销钉套24；若干所述销钉23均布用螺钉固定在所述夹持轴套7的上端，若干所述销钉套24过盈配合的设置在所述夹持升降套8的第三通孔25内，所述销钉23与所述销钉套24滑动配合；销钉23和销钉套24使夹持升降套8非常顺滑的在夹持轴套7上下移动。
如图3所示，所述主轴5与所述夹持轴套7通过免键轴衬26配合固定，安装稳固。
本实施夹紧装置设置有三组，销钉23和销钉套24也为三组。
工作时，气缸1开始工作，带动顶杆6往上顶起，同时带动夹持升降套8往上顶起，之后带动夹块12和塑料夹14往外张开，此时另外的机械手将晶圆9放置到等高柱13上，然后气缸1复位，顶杆6在复位弹簧18的作用下自动复位，从而带动夹持升降套8、夹块12和塑料夹14复位，使塑料夹14夹紧晶圆9，之后就可以进行晶圆9的加工工作，实现晶圆9的点夹持，保证晶圆9的准确定位。
综上所述，上述实施方式并非是本发明的限制性实施方式，凡本领域的技术人员在本发明的实质内容的基础上所进行的修饰或者等效变形，均在本发明的技术范畴。

Claims (7)

1.一种去胶机夹持主轴，其特征在于：包括气缸(1)、气缸座(2)、主轴安装板(3)、主轴筒(4)、主轴(5)、顶杆(6)、夹持轴套(7)、夹持升降套(8)和晶圆(9)；所述气缸(1)固定安装在所述气缸座(2)下端；所述主轴安装板(3)固定安装在所述气缸座(2)上端；所述主轴筒(4)固定安装在所述主轴安装板(3)上；所述主轴(5)可转动的设置在所述主轴筒(4)内；所述主轴(5)内设置有上下贯穿的第一通孔(10)；所述顶杆(6)设置在所述第一通孔(10)内，所述顶杆(6)的下端与所述气缸(1)的活塞杆相配合，所述顶杆(6)的上端与所述夹持升降套(8)固定；所述夹持轴套(7)密封的固定在所述主轴(5)上端；所述夹持升降套(8)可上下滑动的设置在所述夹持轴套(7)上端；所述气缸(1)的活塞杆上下伸缩带动所述顶杆(6)、夹持升降套(8)上下移动；所述夹持升降套(8)上设置有用于定位并夹紧所述晶圆(9)的若干个夹紧装置；
所述去胶机夹持主轴还包括微调装置，所述微调装置包括调节柱(15)、螺纹套(16)、下顶套杆(17)和复位弹簧(18)；所述调节柱(15)与所述螺纹套(16)螺接；所述螺纹套(16)螺接在所述顶杆(6)下端；所述螺纹套(16)与所述主轴(5)留有间隙；所述下顶套杆(17)与所述顶杆(6)套接；所述下顶套杆(17)与所述主轴(5)过盈配合安装；所述复位弹簧(18)设置在所述主轴(5)下端的空腔内，所述复位弹簧(18)上端与所述下顶套杆(17)下端面及主轴(5)内壁相顶，下端与所述螺纹套(16)相顶；所述调节柱(15)下端与所述气缸(1)的活塞杆相配合。
2.根据权利要求1所述的去胶机夹持主轴，其特征在于：所述夹紧装置包括夹持座(11)、夹块(12)、等高柱(13)和塑料夹(14)，所述夹持座(11)固定安装在所述夹持轴套(7)一侧；所述等高柱(13)固定安装在所述夹持座(11)上端；所述夹块(12)一端与所述夹持升降套(8)铰接，另一端穿过所述夹持座(11)并与所述夹持座(11)铰接；所述塑料夹(14)固定安装在所述夹块(12)上端；所述晶圆(9)置于所述等高柱(13)上端，所述晶圆(9)外壁还与所述塑料夹(14)接触。
3.根据权利要求2所述的去胶机夹持主轴，其特征在于：所述夹块(12)呈L形。
4.根据权利要求2所述的去胶机夹持主轴，其特征在于：所述塑料夹(14)呈U形。
5.根据权利要求1所述的去胶机夹持主轴，其特征在于：所述去胶机夹持主轴还包括氮气套(19)，所述氮气套(19)密封固定安装在所述主轴筒(4)的下端；所述氮气套(19)一侧密封连接有氮气接头(20)，所述氮气接头(20)与外部氮气相连接；所述主轴(5)下端与所述氮气套(19)相对应处设置有第二通孔(21)；所述氮气套(19)内壁设置有凹槽(22)，所述凹槽(22)与所述第二通孔(21)相对应；所述第二通孔(21)还与所述第一通孔(10)相连通。
6.根据权利要求1所述的去胶机夹持主轴，其特征在于：所述去胶机夹持主轴还包括销钉(23)和销钉套(24)；若干所述销钉(23)均布固定在所述夹持轴套(7)的上端，若干所述销钉套(24)设置在所述夹持升降套(8)的第三通孔(25)内，所述销钉(23)与所述销钉套(24)滑动配合。
7.根据权利要求1至6任一项所述的去胶机夹持主轴，其特征在于：所述主轴(5)与所述夹持轴套(7)通过免键轴衬(26)配合固定。
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58178533A (ja) * 1982-04-14 1983-10-19 Hitachi Ltd ウエ−ハ押上げ装置
CN104576493A (zh) * 2013-10-29 2015-04-29 沈阳芯源微电子设备有限公司 一种夹持晶圆的承片台装置
CN208527279U (zh) * 2018-02-13 2019-02-22 山东宇世巨化工有限公司 一种粉碎车间用氮气保护防爆装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6777985B2 (ja) * 2015-11-19 2020-10-28 株式会社荏原製作所 基板保持装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58178533A (ja) * 1982-04-14 1983-10-19 Hitachi Ltd ウエ−ハ押上げ装置
CN104576493A (zh) * 2013-10-29 2015-04-29 沈阳芯源微电子设备有限公司 一种夹持晶圆的承片台装置
CN208527279U (zh) * 2018-02-13 2019-02-22 山东宇世巨化工有限公司 一种粉碎车间用氮气保护防爆装置

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