Apparatus for producing semiconductor devices

Abstract: An apparatus for producing semiconductor devices in which a plurality of treatment chambers such as a load chamber (1), an etching chamber (2), a sputtering chamber, an ion implantation chamber, a CVD chamber, an unload chamber (3), a transfer chamber (4), a heat treatment chamber (5), a rinsing chamber and the like, are connected in series preferably in the form of U for effecting various treatments of semiconductor wafers. Wafer conveyor and transfer means (8, 9) are provided to move a wafer through the treatment chambers in which the wafer is normally sequentially processed and these conveyor and transfer means are reversible so that a wafer which has been moved into a predetermined treatment chamber can be returned to the inlet of the apparatus, whereby the quantity of dust attached to the wafer in each treatment chamber can be easily and positively detected. In the heat-treatment cham­ ber, the hot air is discharged against the upper surface of the wafer on the belt conveyor while a vertically movable heating plate is made into intimate contact with the under-­ surface of the wafer so that the uniform heat-treatment can be accomplished within a short period of time. Furthermore, the inner surfaces of the etching chamber or the like are lined with detachable linings made of, for instance, aluminum so that the maintenance is much facilitated.

Description: The present invention relates to an apparatus for producing semiconductor devices by, for example, etching, heating and rinsing materials to be treated such as semiconductor wafers. In the case of etching aluminum layers on wafers or materials to be treated, chloride gases such as SiCl₄, CCl₄, BCl₃, Cl₂ have been generally used. Etching proceeds by the chemical reactions of Al with these etching gases. In the case of a sheet type etching process in which wafers are processed or etched one at a time, an etching chamber must be always maintained in a vacuum state in order to prevent corrosion by chlorine produced by the chemical reactions of water in the atmospheric air with the etching gases. Furthermore, after the etching process, when the etched wafers are exposed to the surrounding atmosphere, corrosion occurs so that the etched wafers are subjected to the heat-treatment or water rinsing, thereby removing residual chloride compounds. However, in the prior art apparatus for producing semiconductor devices, an etching unit is disposed independently of post-treatment units so that there arises the problem that a large space is required for the installation of the whole apparatus for producing semiconductor devices. Furthermore, there arises the problem that the etched wafers are corroded because it takes a long period of time to transfer the etched wafers from the etching unit to the post-treatment unit. Recently, the full automatic apparatus for producing semiconductor devices have been developed so that a wafer is automatically transferred through a plurality of treatment chambers for various treatments in vacuum from a load cassette to an unload cassette without requiring any manual handling of wafers, whereby the treatment time is shortened and the attachment of dust or contaminants on the wafers is avoided. However, with the apparatus of the type just described above, there arises the problem that when wafers are attached with dust, abnormal etching results so that the reliability and yield of the finished wafers are decreased. It is considered that dust is introduced because of the friction between moving parts of the apparatus, foreign matter entrained in the gases introduced and the products of chemical reactions. Therefore it becomes very important to find out where wafers which are transferred through a plurality of treatment chambers are contaminated with dust. However, in the case of the prior art apparatus for producing semiconductor devices, it is only possible to detect the quantity of dust attached to a wafer only after this wafer has been discharged out of the last one of a plurality of treatment chambers. That is, it has been impossible to detect the quantity of dust attached to a wafer in one particular treatment chamber. In the case of the prior art etching devices employing fluoride etching gases, when the etched wafer is discharged out of the etching device, corrosion of the wafer occurs because of the chemical reactions between the oxygen in the surrounding atmosphere and the chloride etchant such as AlCl₃ still remaining on the wafer. In order to overcome this problem, an apparatus has been proposed in EP-A-0 047 002 for producing semiconductor device in which a cassette holding a plurality of etched wafers is charged into an electric furnace or a case with an industrial dryer so that the etched wafers are subjected simultaneously to the heat treatment process. More specifically, in other prior art apparatuses as shown in Fig. 1 of the accompanying drawings, a partition plate b formed with a plurality of holes is disposed in a case a so that the case a is divided into an upper chamber and a lower chamber. A cassette c holding a plurality of wafers d is placed upon the partition plate b and the case a is air-tightly closed with a cover e . The wafers d are dried by the hot air discharged from dryers f disposed on the top of the case a and the hot air flows through the holes of the partition plate b and then is discharged through a discharge port g formed at a lower portion of one side wall of the case a into the surrounding atmosphere. With the device of the type just described above, some portions of wafers are not sufficiently heated because of the cassette c so that it takes a long period of time before the cassettes d are elevated to a predetermined temperature. Furthermore, there is the problem that the wafers d are not uniformly heated so that the variations in properties of wafers result in the post-treatment processes. Furthermore the device of the type described above is of the batch type because the cassette c holding a plurality of wafers d is charged into the device. There arises the problem that such batch type heat-treatment device cannot be directly connected to an etching device. Meanwhile, recently in the production of semiconductor devices, there has been a strong increasing demand for a higher packaging density and a higher rate of production. Therefore, there has been employed a reactive ion etching process which can extremely fine elements and can obtain the vertical side walls without undercuts. For instance, in the case of etching aluminum which has been widely used as a material for defining conduction paths between electrodes, the chloride gases are used. That is, a semiconductor wafer is charged into a reaction vessel and then the reaction vessel is evacuated so that the glow discharge is produced in the reaction gas atmosphere. Then the reaction between a material to be etched on the wafer and the etching gases proceeds so that the material to be etched is changed into a volatile chemical compound. In this manner, the etching process proceeds. When the etching process is completed and the etched wafer is discharged from the reaction vessel into the surrounding atmosphere, the etched wafer still includes the etching gases. As a result, the chemical reactions proceed between these remaining etching gases and the water in the surrounding air so that a conductor pattern of the material not etched and remained on the wafer is attached. As a consequence, the conductor paths are broken and short-circuited. It follows therefore that it is imperative to remove the reaction gases still remaining on the etched wafer immediately after the completion of the etching cycle. This process can be very effectively accomplished by blowing the hot air against the etched wafer and/or heating the etched wafer. Therefore, the etched wafers are heated in an electric furnace or by an industrial dryer, but such heating process has the defects that it takes a long period of time to heat the etched wafer to a predetermined temperature; a uniform temperature distribution cannot be attained so that the properties of the heat-treated wafer vary; and it takes a long period of time before the etched wafer is subjected to the heat-treatment. In order to overcome the above and other problems, there has been proposed a heat-treatment device which can be directly connected to an etching device. A wafer etched in the etching device is immediately transferred by a conveyor or the like from the etching device into the heat-treatment chamber in which the transferred wafer is immediately subjected to the heat-treatment process by means of a normally heated heating plate and an air-heating device. However, since the conveyor or the like is extended into the heat-treatment chamber, a drive means for driving such conveyor or the like from the exterior of the heat-treatment chamber is needed. Therefore, a power transmission means must interconnect between the exterior driving means and the conveyor or the like in the heat-treatment chamber through a hole formed through one side wall thereof. As a result, the hot gases are discharged out of the heat-treatment chamber through this hole into the surrounding atmosphere so that the operations of various devices disposed adjacent to the heat-treatment chamber are adversely affected by the temperature rise. Furthermore, there arises the problem that corrosion of these peripheral devices results because the discharged gases contain the reaction or etching gases. Therefore, it may be proposed to dispose the complex driving means for driving the conveyor or the like within the heat-treatment chamber. However, it is impossible to do so because the driving means is exposed to high temperatures and the reaction gases within the heat-treatment chamber causes corrosion of the driving means. As a consequence, the driving means must be minimized as much as possible and the conveyor system or the like must be simplified as much as possible. Therefore, a belt conveyor is employed. Since a wafer is transported by the belt conveyor, it cannot be made into direct contact with a heating plate. As a result, there arise the problems that the wafer heating efficiency is considerably low, and that the positive and fast heat-treatment cannot be accomplished. In the RIE device (Reactive Ion Etching device) which is one of the types of plasma etching devices, a pair of parallel electrodes are disposed within a vacuum vessel into which is introduced an etching gas, and a wafer is securely held in position on one of the electrodes. RF power is applied to one of the electrodes so that the plasma is produced, whereby the wafer is etched. However, when the vacuum vessel is made of stainless steel and a chloride etching gas is introduced into the vacuum chamber, iron, nickel and chromium are discharged out of the vacuum vessel so that the wafer is contaminated and the properties or characteristics of the wafer are considerably degraded. In order to overcome the above problem, the vacuum vessel is made of alumina or the inner aluminum surfaces of the vacuum vessel are oxidized. However, since alumina is very expensive and has low strength, it is not preferable to use it to fabricate a vacuum chamber. Furthermore, the compounds resulting from the etching process tend to attach the inner surfaces of the vacuum chamber so that in order to prevent the adverse effects of such compounds on the wafer, the interior of the vacuum chamber must be frequently cleaned. However, with the prior art vacuum vessels, cleaning and maintenance are difficult. A first object of the present invention is to provide an apparatus for producing semiconductor devices provided with a heat-treatment chamber which can uniformly heat a material to be treated within a short period of time; which is provided with a transport means; and which is provided with an etching device so that materials to be treated can be automatically and continuously treated. A second object of the present invention is to provide an apparatus for producing semiconductor devices provided with a heat-treatment device capable of uniform heat-treatment at an extremely high rate. The above and other objects of the present invention can be attained by an apparatus for producing semiconductor devices including arranged sequentially in the order named, a load chamber; an etch chamber; an unload chamber; a buffer chamber; and a heat treatment chamber including endless (conveyer) belts for transporting a wafer through the heat treatment chamber and a heating plate for providing contact heating to said wafer, the surface of said heating plate being formed with two grooves extended in the longitundinal direction thereof, the upper runs of said endless belts being fitted into said grooves, the depth of said grooves being such that the upper surface of said heating plate can be raised above the upper surfaces of said endless belts and lowered below the upper surface of said endless belts. Further embodiments of the invention provide an improved apparatus for producing semiconductor devices in which the post-treatment of materials to be treated can be immediately effected and which has a high degree of space efficiency, as well as an apparatus for producing semiconductor devices in which the quantity of dust attached to a material to be treated in each treatment chamber can be easily and positively detected. The features and advantages of the present invention will become apparent from the following description of preferred embodiments thereof taken in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view of a prior art heat-treatment chamber; FIG. 2 is a longitudinal sectional view of a first embodiment of an apparatus for producing semiconductor devices according to the present invention; FIG. 3 is a sectional view of a second embodiment of the present invention; FIG. 4 is a longitudinal sectional view of a further apparatus which does not form a part of the present invention; FIGS. 5 and 6 are a top view and a side view, respectively, of a transport device of the apparatus shown in FIG. 4; FIG. 7 is a longitudinal sectional view of a heat-treatment device incorporated in a fifth embodiment of the present invention; FIG. 8 shows a time-temperature characteristic curve of the heat-treatment device shown in FIG. 8 in comparison with the time-temperature characteristic curve of a prior art heat-treatment device. First Embodiment Referring first to FIG. 2, a first embodiment of an apparatus for producing semiconductor devices according to the present invention comprises a load chamber 1, an etch chamber 2, an unload chamber 3, a buffer chamber 4, and a heat-treatment chamber 5 which are arranged sequentially in the order named. An electrode 6 is disposed at a lower portion in the etch chamber 2 and pusher pins 7 which are disposed below the electrode 6 can vertically move through the electrode 6. Feeders 8 and 9 are disposed in the load and unload chambers 1 and 3, respectively, and each feeder 8 or 9 comprises two pairs of arms interconnected in the form of a pantograph and a supporting plate at the top of the feeder 8 or 9. When the arms are rotated, a material to be treated; that is, a semiconductor wafer is linearly transported. A belt conveyor 11 with pusher pins 10 is disposed within the buffer chamber 4 and a belt conveyor 12 is disposed within the heat-treatment chamber 5. A vertically movable hot plate 13 is disposed below the conveyor belt 12 in such a way that when the hot plate 13 is lifted to its uppermost position, the top surface of the hot plate 13 is higher than the top surface of the belt conveyor 12. A dryer 15 having two nozzles 14a and 14b is disposed above the conveyor belt 12. Heating elements 16 and 17 are disposed within the hot plate 13 and the dryer 15, respectively. A gate valve 18a is disposed between the load chamber 1 and its exterior; a gate valve 18b is interposed between the load chamber 1 and the etch chamber 2; a gate valve 18c is interposed between the etch chamber 2 and the unload chamber 3; and a gate valve 18d is interposed between the unload chamber 3 and the buffer chamber 4. A gas introduction pipe 30 is connected to the etch chamber 2. The gas introduction pipe 30 introduces etching gases into the etch chamber 2. The etch chamber 2 is communicated with an exhaust pipe 20 with a valve 19b while the load and unload chambers 1 and 3 are communicated with an exhaust pipe 21 with valves 19a and 19c. The exhaust pipes 20 and 21 are communicated with vacuum pumps (not shown). A belt conveyor 23 with a water-rinse chuck 22, which is vertically movable and rotatable, is disposed at the downstream side of the heat-treatment chamber 5. A vertically movable load, cassette 24, a conveyor belt 25 and a conveyor belt with a vertically movable setter 26 are disposed at the upstream side of the load chamber 1. A conveyor belt 28 and an unload cassette 29 are disposed at the downstream side of the water-rinse chuck 22. Next, the mode of operation of the first embodiment with the above-described construction will be described. First, the load cassette 24 is lowered so that a material to be treated, or wafer A is placed upon the conveyor belt 25 so that the wafer A is transported at a position above the setter 26. Thereafter the wafer A is positioned at one end of the setter 26 and when the setter 26 is lifted, the wafer A is also lifted. At the same time, the gate valve 18a is opened and the feeder 8 is driven in such a way that the supporting plate thereof is located below the wafer A. Next the setter 26 is lowered so that the wafer A is placed on the supporting plate of the feeder 8 and moved into the load chamber 1. Next, the gate valve 18 is closed and the load chamber 1 is evacuated through the exhaust pipe 21 and then the gate valve 18b of the etch chamber 2 is opened so that the wafer A is moved into the etch chamber 2. Thereafter the pusher pins 7 are lifted so that the wafer A is lifted above the supporting plate of the feeder 8. Next the feeder 8 returns to the load chamber 1 while the pusher pins 7 are lowered so that the wafer A is placed upon the electrode 6. Under these conditions, the wafer A is etched and after etching the pusher pins 7 are lifted so that the wafer A is also lifted. Then the gate valve 18c of the unload chamber 3 is opened and the supporting plate of the feeder 9 is located below the wafer A. As the pusher pins 7 are lowered, the wafer A is placed on the supporting plate of the feeder 9 and is moved into the unload chamber 3. Thereafter the gate valve 18c is closed while the gate valve 18d of the buffer chamber 4 is opened and the pusher pins 10 are moved upward so that the wafer A is lifted. After the feeder 9 has returned to the unload chamber 3, the pusher pine 10 are lowered so that the wafer A is placed on the conveyor belt 11. As the conveyor belt 11 is driven, the wafer A is moved into the heat-treatment chamber 5 and when the wafer A is located below the nozzzle 14, the hot plate 13, which is heated by the heating element 16, is raised above the belt conveyor 12 so that the wafer A is transferred onto the top surface of the hot plate 13. In this case, the air which is heated by the heating element 17 is discharged through the nozzles 14a and 14b against the wafer A so as to dry the same. Thereafter the hot plate 13 is lowered and the conveyor belt 12 conveys the wafer A from the heat-treatment chamber to a position immediately above the water-rinse chuck 22. Next, the water-rinse chuck 22 is moved upward and attached to the rear surface of the wafer A. While the wafer A is rotated, pure water is discharged against the wafer A through a water-rinse nozzle (not shown) so that the wafer A is uniformly water rinsed. After the water-rinse treatment has been accomplished, the air is discharged through the same nozzle against the wafer A which is rotated at a high speed so that the wafer A is dried. After drying, the chuck 22 is lowered and the vacuum suction is released so that the wafer A is placed on the belt conveyor 23 and then transported by the conveyor 28 to the unload cassette 29. As described above, according to the first embodiment, the post-treatment of the wafer can be immediately accomplished after the etching process so that corrosion of the wafer A can be effectively prevented. Second Embodiment A second embodiment of the present invention is shown in FIG. 3 while the chambers are connected linearly in the first embodiment, they are connected in the form of a U in the second embodiment so that the apparatus for producing semiconductor devices can be made compact in size and therefore the installation space can be minimized. That is, according to the second embodiment, a load chamber 101, an etch chamber 102, an unload chamber 103, a buffer chamber (transfer station or stage) 104 and a heat treatment chamber 105 are connected in the form of a U. The etch chamber 102 is connected to the load chamber 101 and the unload chamber 103 through gate valves 118b and 118c, respectively. One surface of the entrance and another surface of the exit of the heat treatment chamber 105 are adjacent to each other. The transfer stage 104 is communicated through an air valve 118d with the unload chamber 103 and is directly communicated with the heat-treatment chamber 105. A water-rinse chuck 122 and a belt conveyor 123 are disposed at the downstream side of the heat treatment chamber 105 and a belt conveyor 128, an unload cassette 129 and an elevator 130 are disposed at the downstream side of the belt conveyor 123. A load cassette 124, an elevator 131, a belt conveyor 125, a setter 126 and a belt coneyor 127 are disposed at the upstream side of the load chamber 101. The load chamber 101 is communicated through an air valve 118a with the setter 127. A gas introduction pipe (not shown) which introduces etch gases into the etch chamber 102 is connected to the etch chamber 102. An electrode 106 is disposed in the etch chamber 102 and pusher pins 107 are disposed below the electrode 106 in such a way that they are movable through the electrode 106. Feeders 108 and 109 are disposed in the load chamber 101 and the unload chamber 103. Each of the feeders comprises two pairs of arms 108a (109a) interconnected in the form of a pantograph and a supporting plate 108b (109b) at the leading end of the feeder. When the arms are rotated, a wafer is transported linearly. A belt conveyor 111 with pusher pins (not shown) is disposed within the transfer stage 104 and an L-shaped belt conveyor 112 is disposed in the heat treatment chamber 105. A vertically movable hot plate 113 is disposed below the belt conveyor 112 in such a way that when the hot plate 113 is lifted to its uppermost position, the top surface of the hot plate 113 is higher than the top surface of the belt conveyor 112. Next the mode of operation of the second embodiment with the above-described construction will be described. The wafers in the load cassette 124 are moved one at a time by the conveyor belt 125 to the feeder assembly 108 within the load chamber 101. The load chamber gate valve 118a is then closed and the load chamber 101 is evacuated. The gate valve 118b between the etch and load chambers is opened and the wafer is placed on the etching cathode 106. The gate valve 118b is closed, reactive gases are introduced, the RF power supply is activated and etching is started. When the etching cycle has been completed, the etch chamber gate valves 118c are opend, the wafer is removed from the etch chamber 102 and transferred to the unload chamber 103. A new wafer is then loaded into the etch chamber 102. The etched wafer is moved onto the transfer stage 104 and then into the heat-treatment chamber 105 for treatment. After heat-treatment, the etched wafer is transferred onto the water rinse/spin dry station for final passivation treatment. Finally the etched wafer is then transferred into the unload cassette 129 by the conveyor belt 128. As described above, according to the second embodiment of the present invention, the post treatment chambers are sequentially connected at the downstream side of the etch chamber so that the post treatments of the etched wafer can be accomplished immediately after the etching cycle. As a result, corrosion due to the reaction of the etched wafer with the surrounding atmosphere can be prevented. Furthermore, it is not needed to provide the post-treatment chambers independently of each other so that the installation space required can be minimized and the production efficiency can be improved. In the first and second embodiments, the post treatments include the heat treatment and the water rinse/spin drying cleaning treatment, but it is to be understood that only the heat-treatment may be employed and that any other required post-treatments may succeed to the etching process. A further apparatus which does not form a part of the invention is shown in FIG. 4 and has a first treatment chamber 201, a second treatment chamber 202 and a third treatment chamber 203 connected with each other in the order named. An electrode 204 is disposed at a lower portion of the second treatment chamber 202 and pusher pins 206 which are moved vertically by means of an air cylinder 205 is disposed below the electrode 204. Feeders 207a and 207b are disposed in the first and third treatment chambers 201 and 203, respectively. As shown in FIGS. 5 and 6, the feeder 207 includes two first arms 208a and 208b and the upper ends of driving shafts 209a and 209b are securely joined to the lower surfaces at one ends of the first arms 208a and 208b, respectively. These driving shafts 209a and 209b carry gears 210a and 210b, respectively. The first arms 208a and 208b are so disposed symmetrically that the gears 210a and 210b engage with each other. The driving shafts 209a and 209b are rotatably supported by a supporting base 211. The first arms 208a and 208b are symmetrically rotated about the axes of the driving shafts 209a and 209b, respectively. One ends of second arms 212a and 212b, which are equal in length to the first arms 208a and 208b, are connected through rotary shafts 213a and 213b to the other ends of the first arms 208a and 208b, respectively, so that the second arms 212a and 212b are rotated about the rotary shafts 213a and 213b, respectively, in parallel with the first arms 208a and 208b. Gears 214a and 214b are carried by the other ends of the second arms 212a and 212b, respectively, and the other ends of the second arms 212a and 212b are rotatably fixed to a wafer supporting plate 215 in such a way that the gears 214a and 214b are in mesh with each other. In the third embodiment, one of the first arms 208a (the left arm in FIGS. 5 and 6) is extended through the supporting base 211 and connected to a rotary drive means such as an electric motor 216. A stationary wheel 217 is disposed on the supporting base 211 in coaxial relationship with the driving shaft 209a connected to the motor 216. A rotating wheel 218 whose diameter is one half of that of the stationary wheel 217, is carried at the lower end of the rotary shaft 213a of the second arm 212a connected to the first arm 208a. A belt 219 is wrapped around the stationary wheel 217 and a rotating wheel 218 so that the rotation of the first arm 208a is transmitted to the second arm 212a. Therefore, when the motor 216 is energized so that the driving shaft 209a is rotated, the other driving shaft 209b is caused to rotate in the opposite direction because of the engagement of the gears 210a and 210b so that the first arms 208a and 208b are caused to rotate symmetrically. Upon rotation of the first arm 208a, the rotating wheel 218 is rotated so that the second arm 212a is rotated in the direction opposite to the direction in which the first arm 208a rotates and concurrently the second arm 212b is also rotated because of the engagement between the gears 214a and 214b. As a result, a wafer placed on the supporting plate 215 is transported linearly. Referring back to FIG. 4. the first treatment chamber 201 is communicated with the surrounding atmosphere through a gate valve 220a and with the second treatment chamber 202 through a gate valve 220b. The second treatment chamber 202 is communicated through a gate valve 220c with the third treatment chamber 203 which in turn is communicated with the surrounding atmosphere through a gate valve 220d. The first and third treatment chambers 201 and 203 are communicated through valves 221 to an exhaust pipe 223 which in turn is communicated with a vacuum pump (not shown). In like manner, the second treatment chamber 202 is communicated through a valve 221 to an exhaust valve 222 which in turn is communicated with a vacuum pump (not shown). Belt conveyors 226a and 226b are disposed adjacent to the gate valves 220a and 220d, respective1y, of the first and third treatment chambers 201 and 203 and have pusher pins 225a and 225b, respectively, which are moved upward or downward by means of air cylinders 224a and 224b. A load cassette 227 is disposed at the upstream end of the belt conveyor 226a while an unload cassette 228 is disposed at the downstream end of the belt conveyor 226b. Next, the mode of operation of the third embodiment with the above-described construction will be described. First the load cassette 227 is lowered so that a wafer A is placed over the belt conveyor 226a which in turn moves the wafer A at a position immediately above the pusher pins 225a. Next, the belt conveyor 226a is stopped and the pusher pins 225a are lifted so that the wafer A is also raised. Next the gate valve 220a is opened and the feeder 207a is energized in such a way that the supporting plate 215 is located immediately below the wafer A. Thereafter the pusher pins 225a are lowered so that the wafer A is placed on the supporting plate 215 and is transferred into the first treatment chamber 201. Next the gate valve 220b between the first and second treatment chambers 201 and 202 is opened so that the wafer A is transferred into the second treatment chamber 202. In this case, the pusher pins 206 are raised so that the wafer A is raised to a position above the supporting plate 215. Thereafter while the feeder 207a returns into the first treatment chamber 201, the pusher pins 206 are lowered so that the wafer A is placed upon the electrode 204. Under these conditions the wafer A is etched and upon completion of the etching cycle, the pusher pins 206 are again raised so that the wafer A is also raised. Next the gate valve 220c between the second and third treatment chambers 202 and 203 is opened and the supporting plate 215 of the feeder 207b is brought to a position immediately below the wafer A. Thereafter the pusher pins 206 are lowered so that the wafer A is transferred onto the supporting plate 215 of the feeder 207b. After the wafer A has been placed into the third treatment chamber 203, it is transferred onto the unload cassette 228 in reverse sequence to the transfer sequence described above. In the third embodiment, the feeders 207a and 207b and the belt conveyors 226a and 226b are so designed and constructed that the wafers are transported in the opposite directions. Therefore, for instance, the wafer A which has once been placed into the first treatment chamber 201 can be returned to the load cassette 227. In this case, the quantity of dust which has adhered to the wafer in the first treatment chamber 201 can be measured by comparing the quantity of dust adhered to the wafer before the latter is charged into the first treatment chamber 201 with the quantity of dust adhered to the wafer after the latter is discharged out of the first treatment chamber 201. The quantity of dust adhered to a wafer can be measured with the aid of a microscope. Furthermore, the wafer which has been placed into the second treatment chamber 202 can be returned to the load cassette 227 by means of the feeder 207a and the belt conveyor 226a. In this case, the quantity of dust adhered to the wafer in the second treatment chamber can be measured by subtracting from the quantity of dust adhered to the wafer returned to the load cassette 227 the quantity of dust adhered to the wafer before the latter was placed into the first treatment chamber 201 and the quantity of dust adhered to the wafer in the first chamber 201. In like manner, the quantity of dust adhered to the wafer in the third treatment chamber 203 can be measured. Furthermore, even when more than four treatment chambers are connected in series, the quantity of dust adhered to the wafer in each treatment chamber can be measured in a manner substantially similar to that described above. In the apparatus for producing semiconductor devices in accordance with the present invention, a wafer or a material to be treated which has been transferred into any desired treatment chamber can be returned to the entrance of the apparatus. Therefore, the quantity of dust adhered to a wafer in a specific treatment chamber can be easily and correctly measured by comparing the quantity of dust originally adhered to the wafer before it was charged into the apparatus with the quantity of dust adhered to the wafer discharged from said specific treatment chamber of the apparatus. Therefore, the quantity of dust or contaminants produced in each treatment chamber can be measured so that suitable countermeasures can be taken to avoid contamination of a wafer in each treatment chamber. As a result, a high yield can be ensured and the production efficiency can be improved. FIG. 10 shows a heat-treatment device incorporated in the apparatus for producing semiconductor devices according to the present invention. An air-heating device 402 which is disposed at an upper portion of a closed treatment chamber 401 has hot-air discharge openings extended from the bottom of the air-heating device 402 and opened downwardly. The hot air heated in the air-heating device 402 is discharged downwardly through the hot air discharge openings 403. A heating plate 404 which is disposed immediately below the hot air discharge openings 403 is vertically movable by means of an air cylinder 405 or driving means disposed outside of the closed heat-treatment chamber 401. It is to be understood that instead of the air cylinder 405 any other suitable driving means such as a crank mechanism can be used. The upper surface of the heating plate 404 is formed with two grooves 480 extended in the longitudinal direction thereof and the upper runs of at least a pair of endless belts 407 (which is a wafer transport means) which are wrapped around belt wheels 406 disposed at both ends of the heating plate 404, are fitted into these grooves 408, The depth of the grooves 408 is so selected that the upper surface (upon which are placed wafers) of the heating plate 404 can be raised above the upper surfaces of the endless belts 407 and lowered below the upper surfaces of the endless belts 407. Disposed in opposed relationship with both ends of the heating plate 404 are shutters 411 and 412 which are adapted to open or close a wafer inlet 409 and a wafer outlet 410, respectively. The shutters 411 and 412 are made of a fluoro plastic and are securely attached to arms 415 and 416, respectively, which in turn are connected to the lower ends of heat-insulating members 413 and 414, respectively, depending from the lower surface of the heat plate 404. Therefore, when the heat plate 404 is raised, the shutters 411 and 412 close the wafer inlet and outlets 409 and 410, but when the heat plate 404 is lowered, the shutters 411 and 412 open the wafer inlet and outlet 409 and 410. A power transmission shaft 417 extended upwardly from the air cylinder 405 through the bottom of the heating chamber 401 is securely joined to the lower end of a heat-insulating member 418 depending from the lower surface of the heating plate 404. A ring member 419 made of a material such as fluoro plastic which will not chemically react with etching gases produced in the closed heat-treatment chamber 401, is fitted over the shaft 417 and made into contact with the bottom of the heat-treatment chamber 401 and is securely held in position by means of a retainer 420 in such a way that any gap between the shaft 417 and the bottom of the heat-treatment chamber 401 is eliminated and the free vertical movement of the shaft 417 is permitted. Next the mode of operation of the fith embodiment with the above-described construction will be described. In order to charge a wafer 421 into the heat-treatment chamber 401, the heating plate 404 is lowered so that the shutters 411 and 412 are also lowered, opening the wafer inlet and outlet 409 and 410. As the heating plate 404 is lowered, the upper-run surfaces of the endless belts 407 are raised above the upper surface of the heating plate 404 and the wafer 241 is transferred onto the endless belts 407. When the wafer 241 is transported through the heat-treatment chamber 401 and reaches a predetermined position, it is stopped by means of stoppers (not shown) so that it is located immediately below the hot air discharge opening 403. Thereafter the heating plate 404 is raised above the upper-run surfaces of the endless belts 407 so that the wafer 421 is transferred onto the heating plate 404 and is made into intimate contact with the upper surface thereof. As the heating plate 404 is raised, the shutters 411 and 412 are also raised, thus closing the wafer inlet 409 and 410. Thus the interior of the heat-treatment chamber 401 is kept air-tight and the hot air heated in the air-heating device 402 is discharged through the hot air discharge opening 403 against the wafer 421 for treatment. Upon completion of the heat-treatment cycle, the heating plate 404 is lowered so that the wafer 421 which has been placed upon the upper surface of the heating plate 404 is now transferred onto the upper-run surfaces of the endless belts 417 and is transported. As the heating plate 404 is lowered, the shutters 411 and 412 are also lowered, opening the wafer inlet and outlet 409 and 410. Therefore while the treated wafer 421 is discharged through the wafer outlet 410 out of the closed treatment chamber 401, a new wafer is charged through the wafer inlet 409 and transferred onto the endless belts 407. Thereafter the new wafer 421 is subjected to the heat-treatment cycle in the manner described above. As described above, according to the fifth embodiment, the wafers are automatically charged into and discharged out of the closed heat-treatment chamber and in the heat-treatment chamber the wafers are subjected to the heat-treatment cycle by both the hot air discharged from the hot-air discharge openings and the heating plate. The heating plate is vertically movable between a position at which the upper surface (upon which is placed a material to be treated) of the heating plate is higher than the upper surface of the transport mechanism and a position at which the upper surface of the heating plate is lower than the upper surface of the transport mechanism. When the heating plate is raised, a wafer on the transport mechanism is transferred onto the upper surface of the heating plate and made into intimate contact therewith so that the wafer is heated. Thus, the contact of the wafer with the upper surface of the heating plate can be easily and positively effected so that, as shown in FIG. 11, the wafer heat-treatment by the present invention (indicated by the solid-line curve B) becomes about three times as fast as the wafer heat-treatment by the prior art (indicated by the broken-line curve A). Thus the heat-treatment capacity can be remarkably improved. So far the wafer heat-treatment has been described as being effected by both the hot air discharged through the hot-air discharge openings and the heating plate, but it is to be understood that the wafer heat-treatment can be effected only by the heating plate. Furthermore, the shutters 411 and 412 may be opened or closed by an independent mechanism, not by the mechanism for vertically moving the heating plate 404.

Claims: An apparatus for producing semiconductor devices including, arranged sequentially in the order named, a load chamber (1; 101); an etch chamber (2; 102); an unload chamber (3; 103); a buffer chamber (4; 104) and a heat treatment chamber (5; 105; 401) including endless (conveyer) belts (407) for transporting a wafer (241) through the heat treatment chamber and a heating plate (13; 113; 404) for providing contact heating to said wafer, the surface of said heating plate being formed with two grooves (480) extended in the longitundinal direction thereof, the upper runs of said endless belts being fitted into said grooves, the depth of said grooves being such that the upper surface of said heating plate can be raised above the upper surfaces of said endless belts and lowered below the upper surface of said endless belts. An apparatus for producing semiconductor devices according to claim 1, characterized in that said unload chamber (3; 103) communicates with said etch chamber; a feeder (9; 109) is provided for transferring the material to be treated from said etch chamber into said unload chamber; said buffer chamber (4; 104) communicates with said unload chamber of said dry etching unit and provides a conveyer (11; 111) for transferring the material to be treated from said unload chamber, said heat-treatment chamber (5; 105; 401) communicates with said buffer chamber; and a water cleaning unit (22, 23; 122, 123) is provided with a chuck (22, 122) for cleaning said material heat-treated with water while said chuck holds in position and rotates said material. An apparatus as set forth in claim 2, characterized by, a load cassette (24; 124) disposed at the inlet side of said unload chamber for holding a plurality of materials to be treated; a first conveyor belt (25; 125) for transferring said material to be treated from said load cassette into said load chamber; a second conveyor belt (28; 128) disposed at the outlet side of said water cleaning unit for transporting said treated materials one by one at a time; and an unload cassette (29; 129) for holding the treated materials transported by said second conveyor belt. An apparatus as set forth in claim 2, characterized in that, one side wall of said load chamber is connected to one side wall of said etch chamber; one side wall of said unload chamber is connected to the side wall adjacent to said one side wall of said etch chamber; one side wall of said buffer chamber is connected to the side wall opposite to said one side wall to said unload chamber; one side wall of said heat-treatment chamber is connected to the side wall opposite to said one side wall of said buffer chamber; and said water cleaning unit is connected to the side wall adjacent to said one side wall of said heat-treatment chamber, whereby units are arranged in a "U"-form. An apparatus as set forth in claim 3, characterized in that, one side wall of said etch chamber is connected to the side wall opposite to the inlet side wall of said load chamber; one side wall of said unload chamber is connected to the side wall adjacent to said one side wall of said etch chamber; one side wall of said buffer chamber is connected to the side wall opposite to said one side wall of said unload chamber; one side wall of said heat-treatment chamber is connected to the side wall opposite to said one side wall of said buffer chamber; and the side wall opposite to said inlet side wall of said water cleaning unit is connected to the side wall adjacent to said one side wall of said heat-treatment chamber; whereby said inlet side wall of said load chamber and the outlet side wall of said water cleaning unit are directed in the same direction. An apparatus for producing semiconductor devices according to claim 1 characterized in that, said material to be treated which has been transported to one of the plurality of units can be reversed to the inlet of said plurality of units. An apparatus as set forth in claim 6, characterized by, a load cassette (24; 124) disposed at the inlet side of said load chamber for holding a plurality of materials to be treated; a first conveyor belt (25; 125) for transferring said materials to be treated, which is held in said load cassette (24; 124), one by one at a time; a second conveyor belt (27; 127) disposed at the outlet side of said plurality of units for transferring one of said treated materials at a time; and an unload cassette (29; 129) for holding the treated materials transferred by said second conveyor belt. An apparatus as set forth in claim 1, characterized in that, said heating means further includes a hot-air heating means (15; 16; 17; 402; 403) disposed adjacent to said endless belts, said hot-air heating means operable to discharge hot air against the material in position by being transported by said endless belts to heat said material. An apparatus as set forth in claim 8 characterized in that, said heat-treatment unit further includes shutter means (411, 412) which open or close an inlet and outlet of said case in response to vertical movement of said heating plate (13; 113; 404).

Inventors: HAZANO SHIGEKI, IWAMI MUNENORI, JYO HIDETAKA, SENSUI REIICHIRO, SHIBAGAKI MASAHIRO, SUZUKI NOBORU, HAZANO, SHIGEKI, IWAMI, MUNENORI, JYO, HIDETAKA, SENSUI, REIICHIRO, SHIBAGAKI, MASAHIRO, SUZUKI, NOBORU
Applicants: SHIBAURA ENG WORKS LTD, TOSHIBA KK, KABUSHIKI KAISHA SHIBAURA SEISAKUSHO, KABUSHIKI KAISHA TOSHIBA
Application year: 1985
Main classification: H01J37
IPC codes: H01L21, B25J9