A New Mechanism for High Acceleration Wafer Transfer Based on Position and Orientation Adjustment

Transcription

1 A New Mechaism for High Acceleratio Wafer Trasfer Based o Positio ad Orietatio Adjustmet Fag SONG 1,Jiag CHENG 1,Yogjia GONG 1, Tao CHEN 2, Liig SUN 2 1 Laboratory of Itelliget Cotrol ad Robotics, Shaghai Uiversity of Egieerig Sciece, Shaghai, , Chia 2 Research Ceter of Robot ad Micro system, Soochow Uiversity, SuZhou,Jiagsu,215006, Chia Abstract With the icrease of wafer-size ad the decrease of feature-width, the requiremet of the wafer-trasfer eviromet is icreasig more rapidly. Therefore, it is very importat to study the high efficiecy, reliability ad o damage to the wafer i a vacuum eviromet. A method of high acceleratio wafer-trasfer based o positio ad orietatio adjustmet i vacuum eviromet is proposed. Firstly, the acceleratios o the horizotal positio ad posture adjustmet of wafer-trasfer are aalyzed, ad the relatioship betwee the maximum acceleratio of wafer trasfer ad pose agle are obtaied. The a wafer trasmissio experimet simulatio platform is established, the proposed method is the simulated ad aalyzed by the use of Adams software. The simulatio results show that the proposed method is effectiveess with high feasibility. Keywords - Wafer-trasfer; Positio adjustmet; High-acceleratio; Kiematics simulatio I. INTRODUCTION A large area of the wafer fabricatio process, the semicoductor equipmets should possess the characteristics of high-vacuum, high-purity, high-dust ad so o. The wafer-trasfer robot with the efficiet, reliable, o trasmissio i the vacuum eviromet has become a hot issue of curret research [1-3]. At preset, wafer-trasfer robot is maily divided ito cleaig trasport robot ad vacuum trasport robot [4-5]. Oe of the mai differeces betwee vacuum trasport robot ad cleaig trasport robot is the clampig mode of the wafer. Vacuum trasport robot caot use the meas of vacuum adsorptio ad electrostatic adsorptio, ad rely maily o the frictio betwee the wafer ad the ed effector. So it is difficult to esure the stability of the trasmissio. It is hope that the trasmissio speed of the wafer ca be improved further, which will be more difficult. The research of the wafer trasfer robot by the domestic scholars bega i recet decades. At preset, the wafer trasfer robot is maily studied by Harbi Istitute of Techology, Dalia Uiversity of Techology ad Sheyag Istitute of automatio, Chiese Academy of Scieces ad so o [6-8]. Due to the limitatio of the curret wafer maipulator structure form, wafer trasfer by SCARA type mechaical had ad R-θ mechaical hads ca realize horizotal trasmissio, the curret two kids of wafer trasfer maipulator structure is ot able to meet [9]. The structure of the curret wafer maipulator determied by the adhesio betwee the ed effector ad the wafer ca oly be realized by the frictio betwee the wafer itself i the vacuum eviromet, which will limit the acceleratio of the wafer trasfer. The solutio to this problem is the mai trasmissio icrease frictio betwee the wafer ad the ed effector through the research o the cotact characteristics betwee the wafer ad the maipulator ed effector, or by desigig a sesor to detect the stick-slip state of the cotact surface for wafer trasfer [10-11]. I order to further improve the efficiecy of wafer trasfer, high acceleratio wafer trasmissio method based o the pose adjustmet is proposed i this article, the acceleratio of the wafer trasfer is aalyzed i horizotal positio ad posture adjustmet, wafer trasmissio experimet simulatio platform is established ad the kiematics simulatio aalysis of the proposed method is carried out. The effectiveess ad feasibility of the proposed method are proved by simulatio results. II. WAFER TRANSFER ACCELERATION ANALYSIS Wafer trasfer maily rely o the frictio by its ow gravity geerated to achieve i vacuum eviromet, the acceleratio of the maipulator is restricted by the frictio of betwee the wafer ad the maipulator ed effector, which will affect the efficiecy of wafer trasfer. A ew method for the acceleratio of wafer trasfer uder the positio ad attitude adjustmet is proposed based o the aalysis of the acceleratio characteristics of wafer trasfer i the horizotal positio i this paper. The followig will be discussed i details. A. Acceleratio Aalysis of Wafer Trasfer Uder Horizotal Positio Durig the wafer trasfer process of the traditioal frictio cotact type, the acceleratio of the wafer trasfer is provided by the cotact frictio betwee the wafer ad the ed of the maipulator. The force model of wafer trasfer uder horizotal posture is show i figure 1. By the mechaical aalysis of the trasmissio wafer by frictio, f is the maximum static frictio force of the wafer whe the ed effector is i the horizotal state. The calculatio formula of f is expressed as follows. DOI /IJSSST.a ISSN: x olie, prit

2 Y F F=ma the wafer f X G=mg the maipulator ed effector By meas of formula (4)-(6), the maximum acceleratio of the wafer trasfer that ca be provided with a acceleratio adjustmet is : si u cos amax g (7) cos u si To take a typical wafer trasfer cotact surface material, its specific structure parameters are: μ=0.28, g=9.8m/s 2.By use of the meas of positio ad attitude adjustmet, the relatioship betwee the maximum acceleratio of the wafer trasfer ad the attitude agle of the wafer is show i Figure 3. Fig.1 Force model of wafer i horizotal positio f=μ s mg (1) By Newto's secod law of motio, F is give as follows. F=ma (2) Therefore, the maximum trasfer acceleratio a is expressed. a=μ s g (3) If the acceleratio of the etire trasmissio maipulator exceeds the maximum value, the wafer will slip. The stability of the trasmissio will be affected. B. Aalysis of the Acceleratio of Wafer Trasfer Uder the Positio ad Attitude Adjustmet The force model of the wafer is show i Figure 2, i the case of the ed effector positio adjustmet. Y F F=ma f G=mg the wafer X the maipulator ed effector Fig. 2 Force model of wafer uder positio ad orietatio Accordig to the mechaical aalysis, the followig relatios are obtaied whe the wafer is trasmitted i a vacuum eviromet. f uf (4) F cos mg f si (5) ma F si f cos (6) Fig. 3 Simulatio diagram of wafer trasfer acceleratio Accordig to the above aalysis, the movemet of wafer trasfer process is adjusted by usig the positio ad attitude adjustmet. The obtaied acceleratio is much larger tha the maximum acceleratio obtaied from the horizotal positio. Therefore, this method ca effectively improve the acceleratio of wafer trasfer, ad further improve the wafer trasfer efficiecy of the whole system. III. MODELING OF WAFER TRANSFER EXPERIMENTAL PLATFORM The trasmissio process of the wafer trasfer robot is as follows: firstly, the uprocessed wafer is removed from the wafer cassette, the positioed by meas of pre aligmet ad calibratio device, ad machied after the processig equipmet. The processed wafers are placed i a wafer box. This paper is maily to verify the feasibility of the proposed method of high acceleratio wafer trasfer based o the positio ad attitude adjustmet ad to desig the ed effector with positio ad orietatio adjustmet. The liear motor is used to provide high acceleratio for the ed effector, ad the ed effector wafer trasfer experimet platform usig NX8.5 UG software is desiged. The overall experimetal platform model is show i Figure 4. DOI /IJSSST.a ISSN: x olie, prit

3 the ed effector the rotatig joit part the liear motor the mobile platform Fig.4 Model diagram of high-acceleratio wafer trasmissio experimet platform I this paper, the desig of high-acceleratio wafer trasfer platform maily cosists of a liear motor, a mobile platform, a rotary joit coectig compoet ad a series of compoets. The liear motor ca achieve the rage of acceleratio of 0-2g, which ca provide the ecessary acceleratio of the experimet. The positio ad posture agle adjustmet of the ed effector is realized through the coectio of the rotary motor ad the rotatig joit parts. This structure ca meet the requiremets of high acceleratio wafer trasfer, that is, may achieve the adjustmet betwee the high acceleratio liear motio ad the attitude of the ed effector. IV. KINEMATICS SIMULATION ANALYSIS I order to verify the feasibility of the high-acceleratio wafer trasfer method based o positio ad attitude adjustmet, the established 3D wafer trasmissio experimet platform usig ADAMS software is aalyzed by the simulatio[12]. Firstly, Descartes's geeralized coordiates are defied i the three-dimesioal model, ad a complete costrait or icomplete costrait system is solved accordig to the Lagrage equatio with multipliers. Fially, the kiematics equatios of the system are calculated. A. ADAMS Kiematics simulatio aalysis Fig.5 The movig assistat betwee the ed effector ad the wafer Three dimesioal models were established by usig UG software, ad the the established model is itroduced ito the ADAMS eviromet through some ecessary simplificatio. Accordig to the followig steps, the dyamic simulatio of maipulator is completed i ADAMS: set the gravity, defie the part material properties, add the costraits, as show i figure 5. The add the frictio ad the drive. The simulatio calculatio is performed. After the model of the high acceleratio wafer trasfer platform is itroduced, the costrait betwee each compoet is established i ADAMS. A movig assistat betwee the bracket ad the guide rail, the movig assistat betwee the wafer ad the ed effector ad the fixed assistat betwee the guide rail ad the earth are separately established. The whole assembly model is defied as a system with relative motio relatio. The special processig module ADAMS/Postprocess provided by ADAMS/View is used to simulate the model. After the simulatio, the data of the force, speed, acceleratio ad displacemet ca be output, ad the displacemet, velocity ad acceleratio curve of the parts ca be also output. After the kiematics simulatio of the high acceleratio wafer trasfer platform is performed, the displacemet, velocity, acceleratio ad other characteristic curve of the wafer, the ed effector, ad other compoets ca be obtaied to call the simulatio postprocessig module of ADAMS/Postprocess. B. Wafer trasfer kiematic simulatio of the ed effector o the horizotal positio Fig.6 The acceleratio curve of the ed effector ad the wafer by the ADAMS software I the process of wafer trasfer i the horizotal positio, the horizotal directio of the wafer is oly affected by the frictio force, that is, the iteractio betwee the wafer ad the ed effector provides the power for the wafer motio. Whe the ed effector lies i the horizotal positio, the wafer trasfer kiematics simulatio of high-acceleratio wafer trasfer motio platform is show i figure 6. The solid lie represets the ed effector acceleratio curve ad the dotted lie represets the acceleratio curve of wafer. I the iitial movemet stage, the acceleratio of the ed effector ad the wafer is gradually icreased, ad at the momet the frictioal force actig o the wafer ca provide the correspodig acceleratio. With the further growth acceleratio, the wafer is gradually icreased by the combied force. Whe the acceleratio reaches 4.5m/s 2, the frictio betwee the wafer ad the ed is ot sufficiet to provide the further acceleratio, so that the wafer will lead to gradually slip. Accordig to the theoretical calculatios, the DOI /IJSSST.a ISSN: x olie, prit

4 maximum acceleratio of the wafer trasport i the horizotal posture is 4.38m/s 2, but the frictio affected by may factors that lead to be more complex. Therefore, the simulatio results is slightly larger tha the theoretical value at here. As ca be see from the simulatio curve, the ed of acceleratio gradually icreases to 5m / s 2, while the wafer after a = 4.5m / s 2 ca ot keep pace with the movemet of the ed effector. The displacemet curve simulatio of the trasmissio of the wafer ad the ed effector i a horizotal positio is as show i figure 7. I the iitial stage of motio, the displacemet curves of the wafer ad the ed effector are overlapped. It idicates that there is o relative slippage betwee the wafer ad the ed effector, which ca esure the reliable trasmissio of the wafer. Whe movig to the A poit i the diagram, the displacemet curves of the wafer ad the ed effector happe to deviate. After the A poit positio, two curves are o loger overlappig. It idicates that the wafer is slidig relative to the ed effector. The wafer ad the ed effector are ot able to maitai the sychroous trasport movemet. effector is aalyzed. Figure 8 is the acceleratio curve of high acceleratio wafer trasfer o the positio adjustmet. By adjustig the agle of the ed positio, the acceleratio of the wafer trasfer ca be effectively improved, ad the acceleratio of the sychroous movemet of the wafer ad the ed effector ca reach 10m/s 2. Figure 9 is the displacemet curve of high acceleratio of wafer trasmissio o the positio adjustmet. The displacemet curve of the wafer ad the ed effector is overlapped, which idicates that the adjustmet of the positio agle ca effectively improve the reliability of the wafer trasfer ad prevet the wafer from slippig. Fig.9 The displacemet curve of high acceleratio of wafer trasmissio o the positio adjustmet Fig.7 Displacemet curve of the wafer ad the ed effector by ADAMS software C. High acceleratio wafer trasmissio kiematics simulatio i the posture adjustmet Fig.8 The acceleratio curve of high acceleratio wafer trasfer o the positio adjustmet The acceleratio drive fuctio is reset, kiematics simulatio is carried out uder the coditio that the maximum acceleratio of the wafer trasfer platform is up to 10m/s 2. The motio statemet of the wafer ad the ed By comparig the above kiematic simulatio aalysis, the maximum acceleratio of traditioal horizotal pose trasmissio mode of wafer trasmissio is sigificatly restricted, the acceleratio icreasig will cause the wafer to slip. I the case of the ed effector positio adjustmet, the maximum acceleratio of the wafer trasfer is about 10m/s 2, ad it ca prevet the wafer from slidig ad esure the reliable trasmissio of the wafer. Therefore, the adjustmet of the ed effector pose agle ca effectively improve the wafer trasmissio acceleratio, which will achieve the highacceleratio motio of the wafer trasmissio. Therefore, to adjust the ed effector pose agle ca effectively improve the wafer trasmissio acceleratio, which will achieve the high-acceleratio motio of the wafer trasmissio. V. CONCLUSION Wafer trasfer maipulator is a importat part of the itegrated circuit maufacturig equipmet idustry. How to improve the efficiecy of the wafer trasfer system ad esure the smooth trasmissio ad accurate positioig of the wafer is the focus of the curret research. For the purpose of the high-acceleratio wafer trasfer maipulator research, the acceleratio characteristics of the wafer trasfer system are aalyzed i detail cosiderig the particularity of the workig eviromet of the wafer trasfer system. The experimet platform of high-acceleratio wafer trasfer is desiged ad the kiematics simulatio aalysis is carried out by usig ADAMS software. Aalysis results show that the timely adjustmet of the ed effector pose ca achieve higher trasmissio acceleratio i the wafer trasfer process, ad effectively improve the trasmissio efficiecy DOI /IJSSST.a ISSN: x olie, prit

5 of the whole system, improve the reliability ad the stability of the wafer trasfer. ACKNOWLEDGMENT This work is supported by NSFC Projects ( ), Exteral-Plaed Task (No. SKLRS-2014-MS-10) of State Key Laboratory of Robotics ad System (HIT), Kowledge Iovatio Team Orieted Task (No.2016td06) ad Jiagsu Provicial Key Laboratory of Advaced Robotics Fud Projects (JAR201401). REFERENCES [1] Fusaro D, Teach your robots well, Cotrol desig magazie, vol.10, pp26-29,2003 [2] Itel White Paper: Itroductio to Itel's 32m Process Techology.USA: Itel Co., 2010 [3] J. Wag, H. Chug, H. Wu, Evaluatig the 300mm wafer-hadlig task i semicoductor idustry, Iteratioal Joural of Idustrial Ergoomics, vol.34, pp , 2004 [4] Hiromitsu K, Wafer processig system icludig a robot, US Patet, NO B1, 2003 [5] Katsuma, Takashi, Vacuum maipulator for semicoductor maufacturig equipmet, Idustrial Robot,vol.29, o.4,pp ,2002 [6] Y. J. Liu, Y. M. Cao, L.N. Su, X. F. Zheg, Accurate ad steady cotrol o trajectory trackig for the wafer trasfer robot, Idustrial Robot, vol.37, o.6, pp ,2010 [7] M. Cog, X. Yu, B. H. She, J. Liu, Research o a Novel R- wafer-hadlig robot. Proceedigs of the IEEE Iteratioal Coferece o Automatio ad Logistics, August 18-21, 2007, Jia, Chia.2007: [8] yuchua HUANG,Daokui QU,Fag XU.FROG- LEG vacuum robot dyamics cotrol research, Sichua Uiversity (Egieerig Sciece Editio),2013,45(3): [9] [9] Mig CONG,Xu YU,Xiaofei XU.Developmet ad Curret Research wafer robot, the robot techology ad applicatio, 2007,4: [10] Wu J,Liu Y J, Ha H J,etc.Desig of Tactile Sesor for Measurig Orthoceter Deviatio ad Frictio i Wafer Trasmissio Process. Advaced Material Research,2012, : [11] Yajie LIU,Yumei CAO,Liig SUN.Vibratio Suppressio for Wafer Trasfer Robot Durig Trajectory Trackig[J].Iteratioal Coferece o Mechatroics ad Automatio.2010,10(01): [12] Cheg WANG,Xiaoyue WANG.Virtual prototypig techology ad ADAMS[J]. mechaical egieerig ad automatio, 2004, 06: [13] Tigtig XING.Kiematics ad dyamics aalysis ad Simulatio of [13] upper ad lower material maipulator [D]. Qigdao Uiversity of Sciece & Techology, [14] Alexei Sokolov,Paul Xirouchakis.Dyamics aalysis of a 3-DOF parallel maipulator with R P S joit structure[j].mechaism ad Machie Theory,2006,04(25) [15] Xiog HE.ADAMS dyamics simulatio algorithm ad parameter settig aalysis [J]. trasmissio techology, 2005, 03: DOI /IJSSST.a ISSN: x olie, prit