Research on Applications of MOCVD based Automatic Control Circuits

Transcription

1 Reserch on Applictions of MOCVD bsed Automtic Control Circuits YANG Yn-qing 1, SONG Xing 1 1 Tizhou Voctionl nd Technicl College Zhejing Tizhou 318, Chin Abstrct With the rpid development of semi-conductor science nd relted hrdwre devices, the pplictions of MOCVD bsed utomtic control system re becoming populr. MOCVD method of preprtion of thin films is the metl orgnic mtter fter gsifiction, respectively using crrier gs into the rection chmber. In indoor produces chemicl rection, rection products of deposition on the substrte to form thin film. In this pper, we introduce the pplictions of MOCVD bsed utomtic control circuits in detil. The simultion result proves the effectiveness of the system. Keywords - MOCVD; Automtic Control; Circuit Design nd Implementtion; Experimentl Anlysis I. INTRODUCTION Thin films of metl oxides re finding rpidly growing ppliction in dvnced mterils technology. With the rise of very deep sub-micron nd Nno-metric technologies, interconnects re incresingly ffecting the overll power consumption, performnce, nd relibility of the chip. MOCVD method is developed for nerly two hundred nd thirty yers to thin film mteril preprtion technology nd it belongs to the chemicl method which is one of the types of CVD method. MOCVD method of preprtion of thin films is the metl orgnic mtter fter gsifiction, respectively using crrier gs into the rection chmber. In indoor produces chemicl rection, rection products of deposition on the substrte cn form thin film [1-2]. Our experiments nd theoreticl nlysis proved tht if the resonble design deposition rection chmber rection resultnt to fter cooling of collecting re nd t the sme time in the preprtion of thin film preprtion of nnometer powder. The dvntges of MOCVD could be summrized s the following prts: (1) Membrne nd micro powder elements of both in the form of gs into the rection chmber by controlling the crrier gs flow rte nd switch cn esily control it. (2) All the process prmeters cn be controlled independently with generl optimiztion. (3) Suitble for lrge re film nd btch production. (4) The source supply system including gs source supply nd liquid source of supply. Gs source supply is refers to the source gs fter decompression, filtering, mss flow controller nd pneumtic vlve into the rection chmber while the liquid source supply is refers to the liquid metl orgnic mtter in specilly mde bubbler. (5) High deposition rte nd good repetbility. (6) Due to source for metl orgnic deposition temperture decrese. This is done in this work. More precisely, we introduce n exct pproch nd heuristic pproch, respectively, iming t the determintion of fesible coding to be used in order to improve the on-chip interconnections [3]. For this purpose, the generl ide of existing synthesis methods for reversible circuits work serves s the guideline. The receiver in the receiving signl with its input level tends to fluctute. The fctors ffecting the size of the receiver input level my be the size of the trnsmitted power nd receiver from the trnsmitters nd the chnge of signl in free spce propgtion conditions or vrious noise interference, etc. The receiver input signl rnge is clled its dynmic rnge[4]. Generlly speking, the receiver bck end for signl trnsmission or processing convenience nd the required output signl level is reltively stble, if the receiver gin constnt, it will not be ble to chieve this requirement so we need to dopt the utomtic control technology. Received for receiver, due to the externl signl level is not constnt, therefore, when receive the wek signl we lwys hope receiver hs better result. In strong signls, the receiver gin cn reduce some, so we cn ensure the receiver terminl is constnt level. Usully, the reliztion of this gol is through the utomtic gin control circuit to chnge the wy to implement the mplifier gin. The function of utomtic gin control circuit is: when the input signl voltge chnge is very big, the receiver output voltge constnt or unchnged bsiclly. Specificlly, when the input signl is very wek, the receiver obtins utomtic gin control circuit doesn't work [5]. Automtic gin control circuit by mesuring the size of the signl level nd compring with the reference level with fst utomtic djusting the mplifier gin size nd control decreses when the input level big gin which input level hours increse control gin to ensure tht the receiver intermedite frequency signl output level constnt. When the input signl is very strong, the utomtic gin control circuit is to control nd the gin of the receiver [6-7]. Therefore when receiving signl intensity chnges, the receiver output voltge constnts power or constnt. In recent yers, there hs been lrge mount of reserch interest in trcking control problems for probe-bsed imging nd Nno-positioning. In the figure 1, we demonstrte the bsic concept nd the corresponding topology of the MOCVD bsed chip structure. DOI 1.513/IJSSST ISSN: x online, print

2 Figure 1. The Bsic Topology of the MOCVD bsed Chip Structure. Therefore, to conduct more relted reserch nd nlysis. In this pper, we introduce the pplictions of MOCVD bsed utomtic control circuits in detil in the following sections. The orgniztion of the pper is scheduled s the follows. In the first section, we provide generl introduction to the reserch. In the second section, we discuss the core technique of the reserch which could be summrized s the following prts: (1) the introduction of the MOCVD technique nd the theoreticl nlysis; (2) the nlysis of the circuit structure nd the topology; (3) the combintion nd the bsic concepts of the control system. In the third section, we conduct numericl nd experimentl simultion on the proposed methodology with generl conclusion. In the finl prt, we summry the reserch nd set up the prospect. utomtic control completely. However, the current MOCVD utomtic control circuits re imported from brod which is suffering from the high cost. Becuse metl oxygen bond is lredy present in metl, the deposition of metl oxides cn theoreticlly be chieved without n dded oxidnt. However, especilly t low deposition tempertures, this cn led to hevy crbon contmintion. MOCVD system control is through the computer utomtic control nd mnul control signl switching signl so s to relize the heting system nd gs flow nd the pneumtic control vlve, etc. We design the MOCVD control circuit by using the computer utomtic nd mnul two kinds of control mode, the two kinds of control mode cn t ny time through the utomtic/mnul switch to switch. In the figure 3, we show the curve. II. THE PROPOSED METHODOLOGY The Concepts of the MOCVD Technique. Recently, drstic improvements hve been chieved on 1.55-μm bsed VCSELs by finding solutions to the issues mentioned. An essentil requirement in the commerciliztion of the MOCVD technique is the vilbility of suitble precursors with sufficient voltility nd stbility, s well s dequte purity nd relted fetures which re shown below. Figure 2. The Generl Structure nd Fetures Mentioned. Metl orgnic chemicl vpor deposition to lrge-scle pure multi-kilogrm mounts of precursors nd thus precursor synthesis must expnd the scle of bout three orders of mgnitude kg from lbortory scle. To mke these chrcteristics of MOCVD would be ble to chieve, we must to strictly control the process prmeters nd process prmeters of MOCVD much more specil nd it is to control the methods put forwrd higher nd higher requirements, therefore it is necessry to dopt computer Figure 3. The Corresponding Curve of the Feture Chnging Figure. The Circuit Structure nd System Description. The trditionl three-phse cge type synchronous motor utotrnsformer step-down strt rely contctor utomtic control system for the following disdvntges: rely contctor is hrdwre device, control circuit wiring multifrious, components nd contct nd contct esy wer nd filure rte is high. However, the control function chnge is not convenient with poor universlity or relibility. Automtic nd mnul switch circuit is to implement the entire system of computer utomtic control signls nd mnul switching. Mnul control nd utomtic computer control signls ech wy which uses the rely circuit, through the utomtic/mnul switch to control the control end of the rely so s to relize utomtic computer control signls nd the mnul control switch. Heting system control circuit is responsible for the control of heting component of the whole system. It includes three prts, nmely heting nd control circuit nd digitl output circuit, heting circuit responsible for the control of the temperture controller signls into heting components so s to relize the heting prts of heting. Automtic heting control circuit bsed on the signl nd the signl of the mnul switch, heting control circuit of the c power signl nd the tsk is to cut off the power t ny time, to stop heting prts supply. Digitl output circuit is responsible for the cut off the power supply control signl to the digitl output heting control circuit so s to relize the utomtic control of the power signl. In the figure 4, we show the Butterworth-Vn DOI 1.513/IJSSST ISSN: x online, print

3 Dyke equivlent circuit. The prmeters re shown s follows. R m Figure 4. The Orgniztion of the Circuit. 8 8 C V 3 r, L 2 m 3 2 Kt AwV w rr AKt 2 8Kt r Awr m, C 3 V d (2) Meter circuit is in chrge of the whole system of gs flow control. It includes digitl/nlog conversion circuit, nlog/digitl conversion circuit nd digitl output circuit nd flow control circuit four prts. Digitl/nlog conversion circuit is responsible for the gs flow utomtic computer signls into nlog signls nd pssed to the flow control circuit. Anlog/digitl conversion circuit's mission is to trnsform from trffic flow control circuit nlog signls into digitl signl feedbck to the computer nd digitl output circuit is responsible for controlling the stte of the flow meter digitl signl to the digitl output flow control circuit. All the utomtic control of flow control circuit implementtion of flowmeter signls nd mnul switch nd to communicte directly with the flowmeter. In the tble 1, we illustrte the prmeter nottion for the circuit. TABLE I 2 K t r THE PARAMETER NOTATION FOR THE SYSTEM Electromechnicl coupling constnt Dielectric constnt A Viscousity Are of resonnce V Phse velocity Density wr Resonnt frequency N w Anti-resonnt frequency d Hrmonic number Thickness of film The Control System nd Theory. In this work, we focus on coding strtegies to improve on chip interconnect rchitectures bsed on the coding templte. Therefore, implementtions of encoders nd decoders re required tht relize the mpping, i.e. tht link the most frequently occurring dt inputs to ptterns with low Hmming weight. The figure 5 shows the device used for controlling. (1) Figure 5. The Device Used for Control System. Exct synthesis lgorithms determine miniml circuit reliztion for given function with respect to given cost metric. Automtic control system ccording to the originl rely contctor circuit digrm to design the ldder digrm is simple nd prcticl method. We build the hot wll of low pressure MOCVD system dopts computer utomtic nd mnul two kinds of control mode which cn t ny time between the two control wys through the utomtic/mnul switch to switch. Control system includes two prts of hrdwre nd softwre, hrdwre including computer, control pnel, control circuit nd the interfce, ll kinds of sensors nd the corresponding control unit. Computer utomtic nd mnul switch control signl fter utomtic/mnul switch circuit nd the control signl control rely which control contctor gin by contctor nd temperture controller to control the volts heting on the solid stte rely signl nd through the seril communiction between computer nd temperture controller circuit of seril communiction. However, to ensure the repetbility of MOCVD process we must crry on the strict control of process prmeters nd the process prmeters nd the MOCVD system much more specil, it is higher nd higher demnds re proposed to control method. Therefore, it is necessry to dopt computer utomtic control completely. Only when necessry to gurntee stbility or performnce requirements, the communiction resources re used. The resulting control strtegy ims t striking blnce between periodic smpled-dt nd event-triggered control. The following formuls formulte the control system description. d x Ax p Bu p Bw w dt (3) In conventionl smpled-dt stte-feedbck setting, the plnt is controlled using controller:,, u t Kx tk for t tk tk 1 (4) Stte mesurements re trnsmitted over communiction network nd the control vlues re updted only when certin event-triggering conditions re stisfied. This modifies the controller into:, u t Kx t for t (5) Gs trnsport pipeline re ll mde of stinless steel pipes, pipe joints connected by wy of rgon rc welding, to keep the rection chmber of low voltge stte, fter the DOI 1.513/IJSSST ISSN: x online, print

4 rection chmber is equipped with vcuum unit nd pressure sensor; In order to quickly trnsform rection of indoor gs, the gs trnsport system with bypss; In order to mke the rection gs into the rection chmber fter mixing, in front of the rection chmber is equipped with the mixing chmber. Heting system is minly including of diffusion furnce nd heting pipes. In order to ensure tht the rection gs in chemicl rection under certin temperture nd the temperture of the rection chmber with lrge re uniformity, we three sections of heting for the diffusion furnce; In order to prevent liquid source gs deposits in the pipe, must to het source of liquid pipelines. MOCVD system control is through the computer utomtic control nd mnul control signl switching signl, so s to relize the heting system, gs flow nd the pneumtic control vlve, etc. Due to the low rection chmber pressure, gs diffusion coefficient incresed significntly, the film growth rte is strongly dependent on deposition temperture, nd is controlled by surfce rection nd the correct control of thickness of the film is very good. Other smpling intervl implying tht no control computtions re needed nd no new stte mesurements nd control vlues hve to be trnsmitted shown in the formul 6 with relted optiml description. dt dt, i j j 1,2,..., M (6) In the next section, we will test the effectiveness of the proposed methodology. While the event-triggering condition still hs periodic chrcter. The ltter spect leds to severl benefits s the event-triggering condition hs to be verified only t the periodic smpling times, insted of continuously, which mkes it suitble for implementtion in stndrd time-sliced embedded system rchitectures. Therefore, we illustrte the control simultion in the figure 7. III. EXPERIMENT AND SIMULATION RESULT Figure 7. The Control Result for the Proposed System. Figure 6. The Structure of the Generted Nno-tips. We firstly show the generl structure of the generted Nno-tips in the figure 6. These two crystllogrphic plnes hve opposite polrity hence hs different surfce relxtion energies, resulting in high growth rte long the c-xis. Lter, to test the efficiency of the proposed control system, we undertke numericl simultion on the item. IV. CONCLUSION With the rpid development of semi-conductor science nd relted hrdwre devices, the pplictions of MOCVD bsed utomtic control system re becoming populr. To mke these chrcteristics of MOCVD would be ble to chieve, we must to strictly control the process prmeters nd process prmeters of MOCVD much more specil nd it is to control the methods put forwrd higher nd higher requirements, therefore it is necessry to dopt computer utomtic control completely. Therefore, we conduct relted reserch on the topic of the system design nd implementtion. The experimentl result proves the effectiveness of the system. We could conclude tht the system is efficient nd robust. In the ner future, we pln to conduct more relted reserch to polish the current orgniztion pttern of the system. DOI 1.513/IJSSST ISSN: x online, print

5 ACKNOWLEDGMENT This work is supported by the Key Project of Gungxi Socil Sciences, Chin (No.gxsk21424), the Eduction Science fund of the Eduction Deprtment of Gungxi, Chin (No.214JGA268), nd Gungxi Office for Eduction Sciences Plnning, Chin (No.213C18). REFERENCES [1] LI, Jinwei, Xioqing CHENG, Yong QIN, Yun ZHANG, nd Zongyi XING. "Relibility prediction of urbn ril trnsit vehicle bsed on BP neurl network." Journl of Centrl South University (Science nd Technology) (213): S1, 213. [2] Müller, A., G. Konstntinidis, V. Buiculescu, A. Dinescu, A. Stvrinidis, A. Stefnescu, G. Stvrinidis, I. Gingu, A. Cismru, nd A. Modovenu. "GN/Si bsed single SAW resontor temperture sensor operting in the GHz frequency rnge." Sensors nd Actutors A: Physicl 29: ,214. [3] Hirt, Koru, Mski Ngse, Atsushi Hidk, Atsushi Mtsumoto, Ryousuke Dohi, Kouji Nishino, nd Nobukzu Iked. "Evportion supply pprtus for rw mteril nd utomtic pressure regulting device used therewith." U.S. Ptent 8,47,51, issued November 1, 211. [4] Creighton, Jmes Rndll, et l. "Emissivity-correcting mid-infrred pyrometry for group-iii nitride MOCVD temperture mesurement nd control." Journl of Crystl Growth no. 6, pp , 28. [5] Lin, To, Hoqing Zhng, Hng Sun, Chen Yng, nd Nn Lin. "Impurity free vcncy diffusion induced quntum well intermixing bsed on hfnium dioxide films." Mterils Science in Semiconductor Processing, pp ,215. [6] Stnkevič, T., et l. "Pulsed mgnetic field mesurement system bsed on colossl mgnetoresistnce-b-sclr sensors for rilgun investigtion." Review of Scientific Instruments ,214. [7] Girudin, J-G., et l. "Development of Embedded Three-Dimensionl 35-nF/mm MIM Cpcitor nd BiCMOS Circuits Chrcteriztion." Solid-Stte Circuits, IEEE Journl of, vol. 42, no. 9, pp , 27. [8] Hongsingthong, Aswin, et l. "Preprtion of ZnO thin films using MOCVD technique with D 2 O/H 2 O gs mixture for use s TCO in silicon-bsed thin film solr cells." Solr Energy Mterils nd Solr Cells ,211. DOI 1.513/IJSSST ISSN: x online, print