GASEOUS LOCK FOR ENTRANCE AND EXIT OF TUNNEL, IN WHICH TRANSPORT AND PROCESSING OF WAFERS TAKE PLACE UNDER DOUBLE FLOATING CONDITION

Abstract: Apparatus (10), comprising a tunnel (14) for transport and processing of wafers (12) under double floating condition by means of at least a gaseous medium, said tunnel (14) is connected with an entrance dome (16) and an exit dome (18) and both domes are at least partly filled with said gaseous medium to such extent, that during operation said tunnel by means of a gaseous lock in said domes is kept separated from the outer air.

Description: Oaseoua lock for entrance and exit of tunnel,in wicn transport and. processing of wafers take plaoe under double floating condition In for instance the Dutch Patent Applications No's 8 103 979 and B 300649 of applicant double floating wafer transport and processing ' systems are described, wherein the transport of the wafers occur in a very narrow tunnel by means of numerous flows of fluid medium, It is desirable, that during the transport and processing of the wafers in the tunnel the outer air is exchanged for an inert gas. Such to prevent as much as possible a contamination of the wafers during the transport and processing. Thereby a leakage of this relatively expensive and possibly poisi- nous medium has to be avoided as much as possible. In addition, the ente¬ ring of the outer air through the entrance and exit of this tunnel has to be prevented as much as possible, A positive feature of the apparatus according to the invention is characterized in making use of entrance— and exit domes, o which the tun- nel is secured in that way, that during operatxon the tunnel is connected with such domes, filled with an inert gas. Another positive feature is that the gaseous medium in such domes is identical with one of the gaseous media, used in this tunnel. Furthermore, that the gaseous medium is lighter than air, Such dome is at its to side sealed off from the outer air, in a sidewall thereof an opening is located, which corresponds with the tunnel passageway , this dome further extends in downward direction as buffer compartment and whereby its bottom side at least temporary can be opened to enable the entering or removal of wafers or cassettes with wafers, In the tunnel the wafers, supplied in the intrance dome, are suc¬ cessively transported towards the exit dome. By transporting the wafer into the tunnel passageway it is desira¬ ble, that at least temporary the thrust on the wafer in this entrance dome is higher than the opposite thrust on this wafer in the entrance section of this tunnel A following positive feature now is, that in this dome at least during the transport of a wafer towards the tunnel passageway the pres¬ sure of the inert gas is higher than that in the tunnel. Thereby the pressure in this dome is also higherThan the pressure of the outer air and during at least such wafer transport this dome is sufficiently sealed off from the outer air. Furthermore it is desirous, that to enable the wafer transport by means of gaseous medium from the tunnel into the exit dome, the pressure in Thereby the pressure in this exit dome is preferably higher than that of the outer air. Other positive feaures follow from the description of the Figures, Figure 1 shows a longitudinal sectional view of an apparatus accor- ding to the invention. Figure 2 shows the entrance dome of the apparatus according to Figure 1 in the supply position of the wafer cassette. Figure 3 is a cross section of a modified apparatus with a supply of a wafer cassette from a cassette track, Figure 4 is a cross section over line 4-4 of the aσparatus accor¬ ding to Figure 1, Figure 5 shows a detail of the take-over section of the entranca dome. Figure S is an enlarged detail of the section according to Figure 5. Figure 7 shows a longitudinal sectional view of a modified dome structure with a sideward displacement of the cassette holder towards the tunnel entrance. Figure 8 shows enlarged details of the apparatus according to Digure 7. In Figure 1 apparatus 10 for processing of wafers 12 is shown. Thereby this apparatus mainly consists of tunnel 14, ith the entrance dome 1G and the exit dome 15 connected therewith. In the unnel 14 wafer transport and processing takes place under double floating condition, During operation of the apparatus in this tunnel 14 an overpressure of an inert caseous medium is maintained, replacing the air. The botton ends 20 and 22 of the respective domes 1β and 13 are open and each is provided with a seal rim 2;5 respectively 26, Thereby by means of the respective mounting plates 30 and 32 s sufficient sealing off of these domes can be accomplished. The plates also function as carrier for cassette 34, wherein the wafers 12 can be stored. On such carrier a mechanism 36 is mounted for thE__displacemant in vertical direction of this carrier, whereby a stepper motor provides the correct vertical positions of the cassette in relation to the tunnel 14. By means of a structure for displacement, such as air cylinders 33 and 40, the carriers 30 and 32 can also be displaced in upward direction, whereby in the highest position of such carrier it rests against the respective sealing-off rims 26 and 28, In the lowest position of such mounting plate 30 the emptied cas¬ sette 34 can be replaced by a new cassette, filled with wafers. This is shown in Figure 2. 5 In Figure 3 is shown, how in a modified entrance dome 16» mounting plates 30* together with cassettes 34" are withdrawn from the cassette track 42 and after emptying thereof can be brought towards this track. In the entrance dome 16 at least during the sealing off thereof a higher pressure is maintained than that in tunnel 14, As a result, wafers 1012 can be successively suctioned into this tunnel. Thereby such wafer is already brought to the correct take-over position and by means of a flow of gaseous medium from supply manifolds 46 and 4B is urged towards the entrance 50 of the tunnel 14, see also Figures 4, 5 and 6, . The sidewalls 52 and 54 of the cassette 34 provides " sufficient 15 guidance for the wafer 12, The thereby eventually produced contamination of the wafer is very limited and is removed in the tunnel 14 by means of cleaning thereof. However, if such contamination has to be reduced, it is possible, that even in the cassette a double floating transport of the wafer takes 20 place. This is shown in Figures 7 and 8, Thereby the cassette is repeatedly displaced in direction of the tunnel 14, creating a double floating condition for this wafer in the adapted front end 50* of this tunnel. Such displacement of the cassette in sideward direction cooperates 25 with a displacement in sideward direction of the adapted thrust block 56 for these wafers. In the exit dome 1B the wafers 12 are successively brought into the cassette by means of a lower pressure in this dome than in the tunnel 14. Such in cooperation with the flows of gaseous medium from the manifolds 3058 and 60, The sidewalls of the cassette provide sufficient guidance for the wafers without the developing of contamination, which cannot easily be removed. Here it is also possible, that the cassette is moved in sideward 5 direction with the double floating transport therein, as is shown in Figures 7 and B. With the double floating wafer transport and processing at least with every main processing of the wafers a pre-cleaning thereof takes a post cleaning under double loating condition occurs. Thereby the domes 16 and 13 are applicable for an installation, . wherein pre-cleaning under double floating condition, main processing and post cleaning under double floating condition of the wafers take place. With a following making use of the cassette, filled with wafers in the exit dome, it thereafter functions as sender cassette in the entrance dome of a following proces installation. Thereby removal of gathered con¬ tamination takes place in the cleaning section of the other proces in- stallation, under the application of the dome structure according to the invention. Uithin the scope of the invention modified structures of the appa¬ ratus including entrance dome and exit dome are possible. - For instance, such apparatus might consist of an installation, wherein pre-cleaning takes place under double floating condition, there¬ after one or more main processings of the wafers under for instance high - vacuum and thereafter post cleaning under double floating condition. Furthermore it is possible, that thereby only pre-cleaning of the " wafers cooperates with such processing.

Claims: c l. A I r-l s 1. Apparatus, comprising: a tunnel for double floating transport and processing of wafers by means of at least a highly filtered gaseous medium; and at least one dome , structured such, that therewith by'means of an established gas lock the passageway of said tunnel is separated froπ the outer air. 2. Apparatus according to Claim 1, wherein said dome is structured in that way, that at least temporary it contains a seat for at least one wafer. 3. Apparatus according to Claim 2, wherein said dome is structured such, that therein at least temporary a wafer cassette is located. 4. Apparatus according to Claim 2, wherein the top of said dome is sealed off, in the sidewall an opening is located, which corresponds with said passageway of said tunnel and said dome over some distance extends i downward direction beyond said opening. 5. Method of said apparatus according to Claim 4, wherein in said dome at least temporary a gaseous medium is supplied, which is similar to the gaseous medium, used in said tunnel passageway for transport of said wafers under double floating condition. 6,Method according to Claim 5, wherein said gaseous medium is lighter than air. 7. Apparatus according to Claim 4, wherein said dome contains 3t its lower end such a sealing-off plate, that therewith at least temporary said lousr end of said dome is sealed off and said platε at least tempora is rsmovsc! fror,ι said done, 3, riethod according to lai 1 -: 5, wherein in said sntrance dom:= du¬ ring the transport of a wafer towards said tunnel passareuay,a higher pressure of the gaseous medium is maintained than in said passageway. 9. Rethod according to Claim S, wherein the transport of a wafer towards said tunnel passageway is accomplished by means of a block, provi ding a thrust on the rear end of said wafer in direction of said passage¬ way. 10, Method accoding to Claim 9, wherein said thrust is accomplished by means of a flow of gaseous medium, 11, Method according to Claim 5, wherein in an exit dome during the successive receipts of wafers out of said tunnel passageway a lower pres¬ sure of saici gaseous medium is maintained than in said tunnel pas'.ageω-.y. 12, Method accordin to Clain 11 wherein durin th9 transport of a wafer from said tunnel passageway towards said exit done at the end of said passageway flows of gaseous medium provide a thrust on said wafer in direction of said exit dome. 13. Method according to Claim 12, wherein in said exit dome at least temporary a higher pressure is maintained than the pressure of the outer air. 14. Apparatus according to Claim 7, wherein in said entrance dome the sealing-off plate also functions as bearer for the cassette carrier and includes means to provide successive vertical positions of said cas- in relation to said tunnel passageway. 15. Apparatus according to Claim 7, wherein said sealing-off plate is structured such, that said wafer cassette is displaceable in direction towards and from said tunnel passageway. 16. Apparatus according to Claim 15, wherein both tunnel ends are provided with sections, temporary extending into said cassette over some distance for transport of said wafer in said cassette under at least partly a double floating condition. 17. Apparatus according to Claim 4, including a process installation, in which at least pre-cleaning of wafers as secundary processing and one main processing takes place.

Inventors: BOK EDWARD, BOK, EDWARD
Applicants: BOK EDWARD, BOK, EDWARD
Application year: 1985
Main classification: H05K13
IPC codes: B65G51, H01L21