INSTALLATION FOR VACUUM PROCESSING OF SUBSTRATES

Abstract: Installation (10) for vacuum processing of substrates (12), including a vacuum module (14), in which processing under vacuum of said substrates (12) takes place, a pressure reduction module (16), including gate means (24), in which a pressure drop from atmospheric pressure down to vacuum takes place, and a pressure raise module (18), including gate means (76), in which a pressure increase upward from a vacuum to atmospheric pressure occurs.

Description: ϊnstallation for vacuum processing of substrates The invention relates to an improved installation for vacuum processing of substrates. In the Dutch Patent Applications No's 8203318 and 8300443 of applicant installations for double-floating transport and processing of substrates are described * Thereby often in related process modules transport and processing takes place under vacuum condition, -..hereby in their supply- and dis¬ charge modules aside transport and cleaning of the wafers (substrates) also a pressure reduction down from atmospheric pressure or a pressure raise from vacuum on occurs. In such an installation an inert gas is us.ed, which whether or not is recirculated for re-use. Thereby it is required, that in such a supply- and discharge mo¬ dule the consumption of gaseous medium per period of time iβ restricted as much as possible because of the following: 1. The capacities of both the ultra-fine filter units and pumps for these gases have to be as small as possible; and 2. The main processing may not be affected by a not proper vacuum. Furthermore, it is wanted that the length of these modules for pressure reduction and pressure increase is limited in view αf the * high cost price of their transport/processing systems, ωhich usually are made of stainless steel. With the installation according to the invention it is inteπted to meet such conditions and it is mainly characterized, that in its supply— and discharge module a gate section is located, ωhich includes a blockable entrance portal and exit portal. In the pressure reduction module with open entrance portal and closed exit portal the substrate enters the tunnel through this entrance portal, whereafter a sensor, positioned in this gate, is activated by the substrate, providing such an impulse to the controlling means of the en¬ trance portal, that this portal is closed. Thereafter in this gate a pressure reduction down to the required vacuum takes place, whereafter the exit portal is opened. Thereafter the removal of the substrate is accomplished from the gate through the exit portal in ' direction αf the vacuum module. A sensor, located in between the gate and the vacuum module, is then activated by the substrate, whereafter the exit portal is closed. Thereafter the entrance portal is opened again and the following substrate can enter this gate. With the pressure raise module this gate system operates opposite¬ ly. A following positive feature of the installation is, that the gate sections at least have an own discharge of transport gases, including in such discharge a sealing-off system for regulation thereofβ With a pressure reduction module with an almost completely sealed— off discharge of its gate, therein a pressure can be maintained, ωhich * is somewhat lower than the pressure in the supply section, whereby by means of gas flows a displacement of the substrate can take place towards this gate. Furthermore, with an open discharge in this gate a vacuum can be established and temporarily maintained and which vacuum is less deep as that in the-transport section of the vacuum module. As a result, by means of the transport medium this substrate can be moved out of this gate towards the passage of this process module. With a pressure raise module and an open discharge αf the gate section a pressure- can be maintained in this section, ωhich is somewhat lower than the pressure in the transport section αf the vacuum module. As a result, by means of gas flows a discharge of this substrate can take place out of this module and towards this gate. With an almost sealed-off discharge of transport medium, in this gate such a pressure increase is accomplished, that with open exit portal by means of gas flows a discharge can take place of the substrate out of the gate and towards a following section of the pressure raise module. In both gate systems a double—floating condition for the substrate in the tunnel passage is maintained and such without any mechanic con¬ tact thereof with the tunnel walls or portal sections. During the movement of the substrate into the gate at least tempo— rarily a gaseous buffer can prevent a collision of the substrate with the valve plate of the closed exit portal. Such structure is described in the Dutch Patent Application Wo. 83 00443 αf the applicant. However, in a very favourable structure * of the installation such a gaseous buffer consists of a locally increased discharge of the trans— port medium, whereby in that tunnel section the substrate remains in that gate area under double-floating condition. A following favourable structure of the installation is characteri¬ zed by the gate, having such a length, that even with a relatively high velocity of the substrate, for instance 100 - 200 mm/sec, still suffi¬ cient time remains available to open the exit gate. In the process module by means of a gaseous buffer a receiver buffer section for a substrata can be created for collecting successive wafers, ωhich under a high velocity are discharged from the processing area. Thereby approximately every. . 20 seconds a substrate can be dischar¬ ged by this section, whereby during a short time, for instance 2 seconds, such a-substrate is fed into the open gate by means of a temporarily in— creased vacuum. Thereby a favourable structure of the gate- contains a relatively wide discharge channel, ωhich is connected with an own high vacuum dis¬ charge for transport gases, whereas in the other discharge channels of this gate a less deep vacuum is maintained, Furthermore, it is possible, that during a longer period of time •the supply of the transport medium tα this gate is closed and only during this 2 seconds transport time the supply of this transport medium to this gate and even to the transporters betωeeπ the vacuum module and the gate is open. "* The valve plates of both portals have to be displaced only over a very restricted length, for instance 1,5 mm. Consequently, it is possible to make use of a valve plate, ωhich by means of an inert gas can be dis¬ placed up and downwardly in a corresponding chamber. Within the scope of the invention other structures αf the gates are possible. Additional positive features of the installation follow from the description of the following Figures: Figure 1 is a longitudinal cross section of the installation accor¬ ding to the invention, including two gates. Figure 2 is an enlarged detail of the gate, which is part αf the installation according to Figure 1. Figures 3 9 show schematically the functioning of the gate structure in the pressure reduction module αf the installation according to Figure 1. Figure 4 9 show schematically tha functioning of the gate structure in the pressure raise module αf the installation according to Figure 1. Figure 5 shows a detail of the passage of the gate structure or other section αf the pressure reduction module or pressure raise module with under 45 positioned supply and discharge channels of the transport medium. Figure 6 shows a gate structure, in which in the centra an enlarged discharge is located for the transport medium to enable a hold of the substrate under double—floating condition. In Figure 1 the process installation 10 for processing of substrates 12 is shown. Thereby this installation mainly consists of module 14, in which processing under vacuum of the substrates 12 takes place, the pressure reduction module 15, in which in addition to the ' supply αf substrate 12 and possibly a cleaning thereof also a pressure drop down from atmospheric pressure to vacuum takes place, and the pressure raise module 18, in which a pressure increase upwardly from vacuum to atmospheric pressure occurs with in addition a possible cleaning and drying of the substrates 12. Supply αf substrates takes place successively from a sender cassette 20, ωhereas the collection of processed substrates (ωafers) takes place in the receiver cassette 22. In module 16 the gate 24 is located in between the supply section 26 and the vacuum section 28. The discharge of the transport medium 30 from the vacuum section 28 occurs together with the medium from the process module 14 through the common discharge duct 32, ωhereas both gate 24 and supply section 26 have their own discharge ducts 34 and 36. Furthermore, the gate 24, see also Figure 2, contains the entrance portal 38,with in its chamber 40 positioned the valve plate 42 and the exit portal 44, with in the chamber 46 thereof positioned the valveplatε 48. . * Gaseous medium 58 is supplied to chamber 40 through supply channels 50 and 52 and such medium is supplied to chamber 46 through the supply channels 54 and 56 for displacement of the valve plates 42 and 48. This medium can be the same as that of the transporters. Thereby within the scope of the invention one of the supplies can be replaced by a spring structure to accomplish the return of the valve pla¬ tes to their rest position. Furthermore, in the valve plates 42 and 48 the openings 60 and 62 are located for passing through of a substrate to and from the gate pas¬ sage 64. In Fioures 3 A throu 9 π D tha functioning αf the .ate 24 is shown schematically. In Figure 3 the substrate 12 has entered the supply section 26 and is displaced in the direction of gate 24 by means of multiple miπifloωs 5 αf gas 36, see also Figure 2. In this gate the pressure in passage 64 is somewhat lower than that in section 26, which is accomplished by means of a somewhat higher va¬ cuum in discharge 34 than in duct 36. Furthermore, the valve plate 42 of the entrance portal 38 is located 10 in its lowest position with its opening 60 free for passing therethrough of the substrate. The valve plate 48 αf the exit portal 44 is located in its upper po¬ sition and seals off tha passage 64 from the vacuum section 28. In that way the substrate can be displaced in the direction of gate 15 24. g In Figure 3 this substrate 12 has entered gate 24, ωhereby a photo¬ cell 68 as sensor is activated and has sent such a signal tα the control¬ ling means of entrance portal 33, that by means of gaseous medium 58 through channel 52 and a discharge of this m e dium through channel 50 the 20 valve plate 42 is brought to its upper sealiπg-off position, see also Figure 2. The substrate is then displace'd in this gate by means of gas flows 30. By means of a delayed signal, for instance 0.2 second later, to the 25 controlling means of the exit portal 44, the valve plate 48 is opened, C ωhich is shown in Figure 3 , whereafter the substrate is displaced through the opening 62 thereof. This is also accomplished by means of the higher vacuum in the va¬ cuum section 28. 30 In Figure 3 the substrate has entirely entered section 28, ωhereby the photocell 70 as sensor is activated. This sensor provides a signal to the controlling means of exit portal 44, causing this portal to be closed. In addition, this sensor has sent a signal to the control of portal 35 38, through ωhich this portal is again opened. In that way the operation cycle has been completed and the following substrate can be supplied through the supply section 26 and such whether or not from a sender cassette. In process module 14 the velocity of the substrate 12 is limited to only approximately 5 mm per second, with a substrate(wafer) processing αf approximately 150 per hour, providing each 24 seconds a passing through the installation of a substrate. As the passing-through velocity of the substrates in the supply module can even amount 100 mm per second, there is ample time to enable a perfect operation of gate 24. Behind the " exit 72 of vacuum module 14 the pressure raise module 18 is located. Thereby a wafer 12 is displaced through the vacuum section 74 towards gate 76 and from this gate through a cleaning module 78 towards a receiver cassette 22. Thereby the functioning of the gate 76, see also Figures 4 , is as follows: In gate 76 the exit portal 80 is closed, with consequently in this gate by means of an increased discharge αf transport medium 30 through the then opened discharge channel 82 a vacuum is established and maintai¬ ned, ωhich to a small extent is deeper than the vacuum in the transporter section 116 of the module 14, see also Figure 1. In addition, the entrance portal 86 is opened. In that way substrate 12 can enter the gate 76 through the opened entrance portal. Thereby the photocell 88 as sensor is activated, has provided a signal to bath controls af this entrance portal 86 and the valve 84, causing these to be brought to a sealing-off position, see Figure 4 • Within a short time, less than 0.3 second, by means of the supply of transport medium 30 tα the transporters of the gate, the pressure in this mini tunnel is increased towards even a-higher value as the atmospheric pressure. Sensor 88 also provides a delayed impulse-to the control of exit portal 80, which after for instance 0,5 second is opened. As a result, the substrate 12 is urged out of this gate through this r opened exit portal 80 and into section 78, which is shown in Figures and 4 D , In Figure 4 the valve 84 is still in closed position, enabling the urging αf this substrate 12 out-of the gate 76 by means of the established overpressure in the tunnel passage 90. However, as soon as the photocell 92 is activated by a passing sub¬ strate 12 and consequently provides an impulse to the control of the exit portal 80, the gate passage 90 is blocked off, ωhich is shown in Figure 4 . The substrate 12 is then fed through the cleaning section 78 for cleaning thereof and through a drying section and at the end enters the receiver cassette 22. By means αf the activated sensor 92 also an impulse is forwarded to the control of the entrance portal 86 and valve 84, whereby at first the discharge of medium through the opened discharge channel 82 takes place and then the portal 86 is opened. As a result, the pressure in the gate drops to below the vacuum of the ' transporter section 116 of the module 14. After the opening αf portal 86 the cycle repeats for the following substrate. Within the scope of the invention the structure and the system of the installation can be var * Led, whereby for instance no cassettes are used and the substrates are received from and forwarded to transport mo¬ dules, wherein whether or not a double-floating transport of the substra¬ tes takes place. The transporter structure under 45 , which is. shown in Figure 5, pro- vides a considerable thrust of the transport medium on the substrate, with only a very limited consumption thereof. A supply of the transport medium takes place per group and through a common channel 94,. through interconnecting channels 96, common channels 98 and a great number of grooves 100, positioned aside each other in the segments 102, tαωards the tunnel passage 104. Thereby a discharge of this medium out of passage 104 takes place through the discharge grooves 106 and connecting channels toωards common discharge channels 108. The segments 102 are positioned in the mounting plate 110. In Figure 6 the gate structure 24' is shαωn, ωhereby in the centre thereof an enlarged discharge channel 112 for the transport medium is lo¬ cated. Thereby with open discharge 34' the substrate 12' is brought into passage 64', is urged towards a position in between these channels 112 and remains there temporarily under double-floating condition. If thereafter the discharge channels 112 are closed, then immediately a further lineair- isplacement αf the substrate takes place through pasage. 64'. Furthermore, it is possible, that the same type of transporters, ωhich are used in module 14 with process chambers in between, extend to¬ wards such a gate structure. Thereby discharge channels are located in between successive trans¬ porters, in which supply of transport madiun occurs.

Claims: 1. Installation for processing of substrates (wafers), comprising: a. a vacuum module in which processing of said substrates takes place under vacuum; b. a pressure reduction module, ωhich is connected with the entrance of said vacuu -module; and c. a pressure raise module, which is connected with the exit αf said vacuum module; said pressure reduction module and said pressure increase module each comprising ab least one gate means in their passage¬ way. 2. Installation as in Claim 1, said vacuum ' odule comprising at least in its entrance section and in its exit section a passageway including series of transporters, arranged in longitudinal direction of said passageway, for transport of said substrates by means of gaseous medium. 3. Installation according to Claim 1, said pressure reduction module and said pressure raise module each comprising: a confined longitudinal passageway; series of fluid medium supply channels, arranged in longitudinal direction of said passageway and extending on both sides of said passageway into said passageway; fluid medium discharge channels, arranged in longitudinal direction of said passageway in between said series of fluid medium supply channels and extending on both sides of said passageway from said passageway; said combination of channels arranged in that way, that at least locally and at least temporary a double-floating condition for said substrates is maintained in said passageway. 4. Method of said installation according to Claim 3, wherein with at least part αf said fluid medium wafer transport/processing takes place in said passageway under double-floating condition. 5. Method according to Claim 4, wherein at least part of said fluid medium is a gaseous medium. 6. Method according tα Claim 5, wherein in said pressure reduction module and/jr pressure raise module wafer cleaning by means of at least fluid medium and wafer drying by means of at least gaseous medium takes place. 7. Installation according to Claim 2, said transporters comprising series of gaseous medium supply channels, extending on both sides αf said passageway into said passageway, in between successive supply channels the arrangement of gaseous medium discharge channels, and said combina— tiαπ of channels arranged in that way, that in said passageway at least locally a double-floating condition under vacuum is at least temporary maintained for transport of said .substrates. 8. Installation according to Claim 1 , said gate means comprising at least one sealable portal far a temporary blocking off of said passage- way of said gate. 9. Installation according to Claim 8, said " gate means comprising a sealable entrance portal near its entrance and a scalable exit portal near its exit. 10. Method of said installation of Claim 9, wherein said entrance portal is opened and said exit pαrtal is closed; a substrate is fed into said passageway αf said gate means through said open entrance pαrtal; and at least one sensor, located in said gate means, is activated by said substrate, moving in said passageway beyond said entrance pαrtal , causing said entrance pαrtal to be closed and with an interval said exit portal to be opened. 11. Installation according to Claim 9, said gate means comprising at least one separate discharge duct for discharge αf transport medium. 12. Installation according to Claim 11, said discharge duct cαmpri- sing a valve far a temporary sealing off of said duct on command αf said sensor arrangement in said gate. 13. Method αf said installation according to Claim 12, wherein , as said substrate is fed through said passageway of said gate with open entrance pαrtal and closed exit pαrtal, said valve in said discharge duct is in open position, and after the activating of the sensor arrange¬ ment in said gate both entrance portal and valve are closed and with an interval said exit portal is opened. 14. Installation according to Claim 9, wherein in said passageway of said pressure adaption modules, as seen in direction of wafer move— ment, in front of said gate a sensor is located, which is structured such, that it can be activated by a passing substrate and so can provide impul¬ ses to the controlling means αf said entrance portal and said exit portal. 15. Installation according to Claim 14, said sensor structured such, that it also provides impulses to the controlling means of said valve in said separate discharge duct. 16. Method of said installation according to Claim 15, wherein in 5 a pressure reduction module ωith-open entrance portal and closed exit portal by means of a discharge of transport medium from said gate passageway through said discharge, duct in said gate passageway temporary a lower pressure is established as in the passageway αf the entrance section of said module, enabling the entering of a substrate into said 0 gate passageway; after entering of said substrate in said passageway, said entrance portal is closed, said pressure in said gate passageway is reduced to a vacuum, with an interval said exit gate is opened and said substrate is urged out of said gate passageway towards, said vacuum module; 5 thereafter said exit portal is closed and said entrance potal is opened, causing the pressure in said gate to raise to the required level for ' receiving a following substrate. 17. Method of said installation according to Claim 15, wherein in a pressure raise module with an open entrance portal and closed exit » 0 portal in said gate passageway by means of a discharge of transport medium through the then open discharge duct a vacuum is established, ωhich is deeper then the vacuum in the transporter section of said vacuum module, enabling a substrate to enter said gate passageway from said module; 5 after said substrate has entered said gate passageway both entrance por¬ tal and said valve in said discharge duct are closed and in said gate passageway the pressure is increased to such a level, that after opening of said exit portal said substrate is urged into the passageway of tha exit section of said pressure raise module; 0 after the closing of said exit portal and opening of said entrance por¬ tal and said valve in said discharge duct the cycle can be repeated for a following substrate. 18. Installation according to Claim 9, said gate passageway compri¬ sing in addition gaseous buffer means for a temporary storage αf said substrate in said passageway. 19. Installation according to Claim 18, said gaseous buffer means comprising a gate passageway area with such a set of discharge channels on both sides of said passageway and extending from said pas-a^aωay, that at their entrances a lower pressure is maintained as at the entran¬ ces of adjacent discharge channels, extending from said passageway. 20. "'lethod αf said installation according to Claim , ωhereiπ a substrate, entered into said gats passageωay through an open entrance portal, is urged toωards said passage area, wherein at that time and temporary a lower pressure is maintained and flows of transport medium, moving in opposite direction to said wafer (substrate) movement towards said passage area, provide as a gaseous buffer such counter thrusts on said substrate, that the linear displacement of said substrate towards the then closed exit portal of said gate passageway is ended and whereby said substrate remains in said area under double—floating condition for a buffer period αf time. 21. Method according to Claim 20, wherein after opening of said exit portal said substrate by means of an overpressure is urged from said buffer area through said opened portal towards an adjacent passage¬ way of said module. 22. -ressure reduction module, comprising in succession: a. a double—floating wafer transport section; b. a double—floating wafer cleaning section; c. a double—floating drying section; d. a ' double-floating pressure reduction section, including gate means; an e. a double—floating wafer transport section. 23. Pressure raise module, comprising in succession: a. a double—floating wafer transport section; b. a double-floating pressure raise section, including gate means; c. a double floating cleaning section; d. a double—floating drying section; and e a double—floating wafer transport section. 24, Installation according to one of foregoing Claims, wherein it is structured such, that in such pressure adaption section inside said gate passageωay the combination of transport and processing under double- floating condition takes place αf said substrates.

Inventors: BOK EDWARD, BOK, EDWARD
Applicants: BOK EDWARD, BOK, EDWARD
Application year: 1985
Main classification: H05K13
IPC codes: C23C14, H01L21