DE2364790C2 - Control device for a transport device for the production and processing of small workpieces of the same type in the manner of planar semiconductor components - Google Patents

Description

The invention relates to a control device for a transport device according to the preamble of the patent claim 1.

During the past decade, the industry has succeeded in making planar semiconductor devices such as silicon diodes and to manufacture transistors in large numbers. When processing semiconductor wafers, z. B. made of silicon, two types of batch processing were found. One concerned the semiconductor disk itself, within or on which a large number of identical transistors or diodes have been fabricated. So on a plate γοη were about 30 mm in diameter z. B. 1000 transistors produced This method is called "plate stacking"

Another method known as "multiple panel stacking" This method was also used. B. in diffusion, with about 200 plates can be treated at the same time.

In order to increase the number of pieces and to reduce the costs, various systems have been developed take advantage of one method or the other. It is clear that the plate stacking increases the processing cost per manufactured Able to significantly reduce the element.

The advantages of stacking panels can be better exploited if larger panels are used. From an initial diameter of around 20 mm, the plates were steadily enlarged up to around 80 mm.

The effort that had to be made for this enlargement was, however, considerable, since brackets, Holders, masks and other equipment each was to be put on tr. For planned changes in the manufacturing process It is not uncommon for the tools and equipment to be used to be taken into account. So like a planned enlargement of the plates would require a new, larger diffusion furnace. It also brings seldom leads to an improved yield, but on the contrary, it usually drops.

The multiple plate stacking has also been significantly improved.For example, the metallization of the lines, originally on 8, then on 18, now mostly on 35 plates at the same time, while epitaxial reactors, which used to hold 8, then 20 plates, now process 70 at the same time can, and diffusions, which were previously carried out on 10 plates, can now be carried out simultaneously on around 300 plates.
This type of stacking has certain significant disadvantages. Initially, it is usually carried out independently for each operation, so improvements only always have an effect on one operation. In addition, the individual stacks vary in size during manufacture, creating significant inventories of panels in progress. Finally, this procedure entails that the time required for the individual work step is increased and the process yield is slightly reduced. It should also be noted that neither stacking method affects the number of panels to be tested and that this part of the production is a significant contributor to the total cost

With the advent of monolithic integrated circuits, a third batch process emerged, the referred to as "chip stacking". This method refers to the integration of a large number of elements, such as it has become common in the semiconductor industry For example, a transistor is not used on a chip, it creates around 1400 individual transistors and resistors. Usually a larger one is added to this Chip used.

It can be assumed that further advances in semiconductor manufacture will be at the slightest Part will be based on the multiple plate stacking

the. Similarly, no further progress can be expected from the stacking of panels, since with increasing Plate size significant difficulties, such as fragility of the plates, mechanical adjustment, temperature

temperature coefficients, etc., greatly affect the yield. The stacking of chips, on the other hand, seems suitable for increasing the production quantity by at least a factor of 10, merely by enlarging the surface of the individual chip by about two to four times. This method reduces the time required for the test as well as the effort for -ze, changing tools and facilities and the mounting of the chips

Regardless of the stacking method, the manufacture of semiconductor devices requires a large one Number of procedural steps. The number of these steps depends on the type of product to be manufactured and its complexity. The sum of the times that are required for all these steps is called "production time" called, and takes about 40 to 60 hours. Manufacturing process with multiple plate stacking require more manufacturing time because the tools and fixtures that handle many parts at the same time work slower, e.g. B. longer heating, cooling. or have evacuation times. Charging also takes time and unloading the used devices longer.

In addition to the production time, there are also »queuing times«, which in practice make up the greater part of the total Make up time. Queuing times of 40 to 60 days are considered normal in today's semiconductor factories. These times arise when the multiple plate stack is put together, due to the time required for repairs or maintenance of facilities is required due to the adjustment time for masks etc. etc. These times can become so long that additional cleaning operations are required, which in turn reduces manufacturing time extend.

The device to be described below for processing workpieces should in particular the Manufacturing time and queuing times for a system of the type described above are significantly reduced will. This object has been achieved by the arrangement specified in claim 1.

AT-PS 2 88 112 is a machine tool system with a central control unit and several numerically controlled machine tools for simultaneous machining of several different workpieces described, of which at least some to be processed only by individual machine tools, of which at least some only need to be processed by individual machine tools, each machine tool over has several programs and several tools to run these programs and from the central Has control unit controlled program changing devices and tool changing devices. "This system contains pallet transport devices controlled by the control unit, by means of which the pallets carrying the workpieces are displayed for each by the control unit Machine tool to be moved back and forth from this. Every pallet and every magazine carries an identification mark, for example a code number, and reading heads are assigned to the transport trolley, which send a signal to the central control unit indicating the presence as well as the identification of each transporting pallet or the magazine being transported.

The particular advantage of the device according to the invention over the prior art is therein seen that the workpiece carriers conveying the workpieces, also referred to as pickups, each initially be started by means of the coarse motor with increased speed and this speed as long is maintained until the difference value between the continuously detected actual position and the target position falls below a specified value Then takes place at a reduced speed, Namely, through the drive by means of the fine motor, the exact approach to the target position takes place.

The reduction of the speed setpoint to creep speed is known for storage and retrieval vehicles (BBC News, May / June 1970, pp. 121-24).

Embodiments of the invention are explained below with reference to the drawings

F i g. 1 shows a device for processing workpieces, in which the process steps are carried out in processing stations IA to IF, each station being able to carry out different process steps, during and after which the product can be stored for some time without impairment. It is clear that the number of processing stations must be so large that the entire quantity of products to be manufactured can be processed, the individual stations being selected by control devices to which the products are fed by the transport device 2 depending on their occupancy.

The products or workpieces are transported by the transport device 2 to the entrance of each processing station A controller causes a workpiece to be detected as being at the input is fed to the processing station and subjected to the whole series of processing steps that can be executed in this station. When these steps have been completed, the workpiece will be brought to the exit of the station, where it is loaded onto the transport device, which takes it to the next Processing to the next station.

The transport device can comprise movable workpiece carriers which, under the influence of a Control picking up a workpiece at the exit of one station and taking it to the entrance of any other the prescribed station. A servo control ensures that the transport device to all Entrance and exit points of all processing stations can get to pick up workpieces or discontinue.

In semiconductor manufacture, the processing stations \ A to IF are set up to carry out suitable manufacturing processes, such as epitaxy, metal deposition from the vapor phase, photo masking steps, oxide etching, photomask removal, impurity diffusion, metal etching, production of dielectric coatings, cathode sputtering, ion implantation, etc.

It is now assumed that the device of FIG. 1 is designed for the production of field effect transistor circuits. For this purpose, the device should have all the equipment required to produce the finished field effect transistor circuits from the raw plate. For example, an initial oxidation station IA is available, a source and drain deposition station Iß, a gate oxidation station IC, a line pattern generation station ID, a metallization station \ E and a sintering station IF. Apart from the adjustment and exposure stations, the equipment of all other stations should be provided for these process steps. Usually, individual plates are fed to the stations of the device in a steady flow in a regular sequence. Intermediate storage is provided at the output of stations 1Λ, IB, IC and 1 E to

to compensate for any unreliability of the facility.

Plates of the device is supplied by a suitable charging device 3, which is included in the first processing station \ A, In this station, a number of cleaning operations are performed, an oxide layer is formed on the plate and a layer of photosensitive lacquer is applied. It should be noted that the operations for applying, drying, developing, etching and stripping of photoresist are attached to the corresponding stations for heat treatment in order to ensure the required cleanliness. These photolithographic operations occur several times in manufacturing. The stations are designed for maximum yield with the simplest control. The alignment and exposure devices are the same in all stations, although different ones can be used if cost and yield warrant it.

The processing stations connected to one another by the transport device 2 contain one Disk receiver that can pick up a disk in one sector and place it in another. Of the For the sake of simple control and mechanical construction, the pick-up handles a plate after the others. In the FET fabrication of the present example each plate is transported eight times.

The individual workplaces within the station are set up like satellites around the transducer. Stations for heat treatment are summarized, as well as stations for alignment and exposure, thereby simplifying the facility and facilitating maintenance. For example, the Alignment and exposure stations require an air-conditioned room, whereas the heat treatment stations require good ventilation and a hood.

The processing device contains four main buffers, one each at the exit of a heat treatment station, namely initial oxidation stations \ A, source and drain diffusion station 15, gate oxidation station IC and metallization station 1 £ At the output of the pattern generator 6 in the photoresist hardening station \ D is usually no intermediate storage is required as it can only handle one disk. However, a single disk storage is provided at the entrance to the etching and stripping operation of the other stations in the event that one station goes out of service while a disk to be added is in an alignment and exposure station. It is clearly desirable, the pattern generator β in the exposure station to be kept free D 1; so that other steps can be performed.

Disk buffers 4 are provided at those points in the process where storage cannot affect the process yield. For example, after the photoresist application and drying device 5 in stations \ A, \ B, IC and IZf, which is carried out in the pattern generators 6 in station \ D before the adjustment and exposure operation. In practice, all stations of the facility will be equipped with a certain overcapacity so that the queuing time after a possible interruption of the station due to maintenance or repair is not too long. The operation of the entire facility is asynchronous, and each station or substation processes any disk that arrives as long as it is not overloaded.

The processing of the panels one after the other in the order in which they arrive provides an overview about the manufacture of various products. A number of different products can be used at the same time, so to speak are manufactured with minimal monitoring and control to identify the individual panels in the transfer line. The individual plate number or part number can be added in front of each adjustment and Exposure step can be determined. The easiest way to do this is in a known manner and by known means happen during the handling of the plates by the pickup of the transport device 2. For example can handle a mixture of different parts of a board or circuit family at the same time in the parameters of the various treatment stations with the exception of the pattern generators 6 are the same. Different circuits are generated by reading the plate or part numbers and by selecting the appropriate masks for exposing the photoresist.

The transport device 2 can have one or more movable plate carriers 7, FIG a disk holding and depositing mechanism 8 on a carriage 9 runs along a rail 10. the Rail 10, which stands on supports 11, leads over the loading and unloading point of the various processing stations. All entry and exit positions of the processing stations are located below the rail 10. The panels are in a horizontal position upwards oriented moves.

The plates are in the manner of a Bernoulli button as shown in FIG. 3 taken. The plate carrier 8 has a base plate 15 with various openings 14 located near the periphery through which various flexible hoses 17 which can be evacuated via a line 16. The cunning 17 carry a strap 18 which is attached to a light leaf spring 19 which is clamped in the body 20, to project the free end of the hose 17 evenly from the underside of the plate 14 under slight pressure so that a plate can be gripped when negative pressure is applied. An air duct 21 leads through the body 20 so that a slight air or Gas stream flows out of the nozzle 22, which by means of the Bernoulli effect, the plate 23 against the open ends the tubing 17 moves where it is held.

The hoses 17 are arranged so that a distance exists between the base plate 24 and the semiconductor plate 23 so that it only touches its periphery will.

The trolley 9 comprises the plate carrier 8, a motor 7 for vertical movement and a Motor 25 which, by means of the gear mechanism 12, drives a gearwheel which is connected to the toothing 26 of the running rail 10 The information to control the movement of the transport device 2 is this via a flexible Cable 27 fed

As already noted, each processing station is designed to carry out certain process steps it should be carried out as quickly as possible and with a high yield. Each station has its own time-dependent one Controls for movements and other parameters for both operation and maintenance are also included Connections are provided for a data collection system that keeps records of the individual panels and if necessary allows external control of critical parameters

To take the device into operation, plates are inserted into the initial Oxydationsstation \ A, where they are dry cleaned, after which thermally crushed oxide and photoresist is applied.

Five treatment steps are provided in station IA , namely

1. disk storage and loading,

2. cleaning,

3. Oxide formation,

4. Oxide thickness measurement and

5. Application and drying of photoresist.

The station is shown in detail in FIG. 4 shown.

Before being introduced into the oxidation station IA , the silicon plates are checked in order to then be loaded into the station. The plates are transported by the input carrier 103 from the loading station 30 to the cleaning station 32. This comprises a number of wet treatment vessels 32A to 32A and a drying vessel into which the plates are placed one after the other by the receiver 31. Two such transducers are intended for parallel operation.

A further pick-up 34 places the plates in the correct orientation on movable carriers 33 loaded, which pass through the oxidation furnace 35 continuously. The plates lie horizontally for oxidation on a quartz support 33. When leaving the furnace, they are cooled and then by the transducer 36 on a transfer table 38 placed, wherein they pass the oxide thickness measuring device 37. The transducer 39 sets the Plates on the turntable 40, where the photoresist is applied and distributed by the rotation of the plate, then on the heating plate 41, where the paint is dried, and, if necessary, in the intermediate storage 4, from where the plate is brought into the unloading position 43 in order to be picked up again by the central transport device 2 to become. The automatic oxide thickness measurement is used, on the one hand, to determine the parameters of the Oven 35, on the other hand, the subsequent etching operation for the source and drain diffusion in station 1J9 steer. A visual inspection of the disk is best done at location 4, though the plate is controlled so that it stands still there for a sufficient time. There is also a Inspection possible to check the previous process steps and any errors early on turn off. Such inspection stations are distributed over the entire transfer line. The photoresist station 40 and the drying station 41 are shown as a photoresist unit 5 in FIG. 1 shown

The mechanical pick-up 39 grips the plate lying on the storage table 38 and transports it to the photoresist stations 40 and 41. The station 40 consists of a simple turntable and the station 41 from a hot plate. The semiconductor plate that is removed from the heating plate can be stored in the buffer 4 are deposited, from where it is brought by the transport device 2 to the mask alignment and exposure station ID.

The transport device 2 now brings the plate to the entry position 30 of one of the pattern generators 6 in the exposure station ID. Each pattern generator can be connected to a mask magazine 54, where the masks for the various operations of the various components to be manufactured are stored. A pick-up brings the semiconductor plate to an alignment station and from there to the exposure station. There are various options for imaging the desired etching pattern on the photoresist, such as exposure through a contact mask, projection imaging and step-by-step imaging. Then a plate is first aligned and adjusted for exposure, whereupon the desired conduction or diffusion pattern, which is stored in the data memory of the device, is written into the photoresist by means of an ion beam. Several such patterns are each stored in memory and selected as required. However, conventional masks can be stored in a magazine, as indicated by 54, and selected as required.

ίο After the exposure, the pick-up 52 brings the plate to the starting position 55, where it waits for the transport device 2 to take it over. Under the influence of a central control, the one in FIG. 2 up the plate from the starting position 55 of the station \ D and transports it to the input position 56 of the source and drain station 1 B. This is shown in FIG. 6 shown in detail. A pick-up 31 grips the plate at the entry point 56, rotates it through 90 ° and dips it one after the other into several containers for the purpose of developing, etching and removing the remaining photoresist, for which purpose the containers are filled with appropriate liquids. The setup for this operation is essentially the same as that for the cleaning operation described in connection with station 1/4 and which occurs elsewhere as well. Once the openings for the source and drain of the transistors have been created as a result, the plate is fed in a horizontal position to a station 59 for visual inspection and plate alignment and then to a diffusion furnace 61 by means of a conveyor belt 58. The picker 60 loads the plates onto a series of quartz supports. As they exit the oven 61, the plates are picked up by the picker 62 which takes them to station 37 where measurements can be taken and where photoresist is applied, then to a heating plate 41 to dry the lacquer and to a station 38Λ for visual inspection A conveyor belt 63 finally conveys the plates to the exit station 64, where they are removed from the transport device 2. If necessary, the plates are still stored in the buffer memory 4 on the road under the influence of the central control The transport device 2 brings the plates to a free entry point 54 of a mask-and -belichtungsstation \ D for imaging the gate electrode on the resist. After exposure, the plate is brought by the pick-up 52 to an output point 55, where it is again taken over by the transport device 2 and brought to the gate oxidation station 1C and placed flat on its input point 66.

The gate oxidation station 1C is shown in FIG. 7 shown Under the influence of a control, the plate is gripped by the pickup 67, rotated 90 °, and into the Dividing the vessel 68Λ developed and rinsed Then the plate comes to a heating device 68 to Post-curing of the photoresist. From there it is gripped again by one of the pickups 69 and into the six compartments of the vessel 70 immersed for etching, rinsing, paint stripping and drying of the plate. Finally, the plate comes onto the conveyor belt 71, where it first goes to the inspection point 72 and then on one of the supports 73 passes through the oxidation furnace 74. There an oxide layer is measured more precisely Thickness generated During and after the generation of the oxide layer, the panels are placed in the furnace with a suitable substance such as phosphorus oxychloride (POCI3) doped, whereby the oxide layer has the desired properties

contains shafts. After leaving the oven, the pick-up 75 grabs the plates and brings them to station 76, where photoresist has recently been applied, and to the heating plate: 77, where it is dried. The plate is then, possibly after a visual inspection, on the conveyor belt 78 and possibly via the intermediate storage 4 to the exit point 79, where it is in turn taken over by the transport device 2 for transfer to station XD.

In the masking and exposure station XD , the mask for the line pattern to be metallized is now imaged under the influence of the controller, whereupon the plate is taken over again by the transport device 2 and brought to the metallization station XE .

The metallization station XE is shown in detail in FIG. A pick-up 81 takes over the plate from the entry point 80 and ensures the development of the photoresist in the vessel 82 with subsequent hardening on the heating plate 83. A pick-up 84 then takes over the plate for the purpose of etching the oxide layer at the exposed locations, rinsing and drying and depositing it on point 85. The pick-up 86 now brings the plate onto one of the plate carriers of the metallization station 87.

After metallization has taken place, a pickup 89 takes over the plates from point 88 and brings them to a photoresist station 90 and then to a heating plate 91 for the purpose of drying. The plate comes last on the conveyor belt 92, is, if necessary, stored in the buffer store 4, and arrives at the output point 93, where it is taken over by the transport device 2 in order to be brought to the masking and exposure station XD. In the exposure station, the line pattern to be etched out of the metallization is transferred to the plate. The transport device 2 then brings the plate to the sintering station IF.

The sintering block IF is in A b b. 9 shown in detail. Again, the plate is gripped by the receiver 95 and developed in the vessel 96, rinsed and dried The photoresist is hardened on the heating plate 97. One of the transducers SS takes care of the etching, Rinsing and drying in vessel 99, whereupon the plate is transferred to the ICO station for visual inspection and then on is brought from the receiver 101 into the sintering furnace 102. After exiting the oven 102, the plate is on one of the carriers 103 brought to the processing facility at 104;: u exit.

F i g. 10 shows a schematic overview of the transport device 2 and its control. The device comprises one or more plate carriers 9, which run on a rail, and by means of the cable 27 of FIG the pickup firing 111 can be influenced. As already determined, the transport device can be called to the entry and exit points of the processing stations which are located along the rail 10 are arranged. Each of these input or output points has a workpiece sensor that sends an electrical signal outputs to a sensor monitoring device 112, which in turn causes the control to check the workpieces of their Determination to be moved further.

The sensor monitor 112 checks the workpiece sensors 113 at regular time intervals. If a workpiece is at the exit point of a processing station, various decisions must be made before an egg movement can be initiated. The sensor monitoring 112 decides to which processing station the workpiece is to be brought next. It now checks whether the entry point of the next processing station is free and there is no longer any workpiece. It then sends the address of the station at whose output the workpiece is located to the pick-up control 111, which receives the address depending on the position of a control system to be described. When the movement has been completed and the pick-up 9 has gripped the workpiece, the pick-up control controls the transport device to the specified address. The workpiece is thereby transported to the new processing station and deposited. Then the Aufnehmersteuerung sends an end-of-signal sensor monitoring 112 now checks you '* Jagänge of the processing stations again.

The drive of the already introduced in connection with F i g. 2 described disk receiver 9 is in F i g. 12th shown in more detail. In addition to the main drive motor 25, a fine drive motor 12 is provided. To the Coarse setting potentiometer 115 is a fine setting sensor 120 and a clutch brake 116 assigned

The servo control of the disk pickup is shown schematically in FIG. 11 The fast or coarse position lag uses a DC motor with potentiometer feedback. The fine or slow follow-up uses a DC ^{servo controller: sr ":} »: *> nem contactless position sensor 120, which can detect a sensing element 121 attached to the rail 10, which is attached to each processing station.

The pickup control comprises a servo amplifier 123, Fig. 11, an address matrix 124, which serves as a digital / analog converter, a coarse position amplifier 125, a fine position demodulator 122, which converts the alternating current signal of the fine position sensor into direct current, and a coarse comparator 126 and a fine comparator 127 the necessary logic circuits and a power supply are provided.
First of all, the system should be considered when it is at a standstill. The pickup carriage 9 is normally above an exit or entry point along the rail 10. The brake ί 16 is closed and holds the carriage 9 on the rail 10 positive input of the coarse amplifier 125 generates the position of the carriage 9 a G'eichspannung is indicated by the potentiometer 115 in the form that the corresponding voltage appears as a coarse error at the output in any case appear at the negative input of the coarse amplifier 125 at the beginning is greater than the voltage a EC. and the coarse comparator therefore switches to coarse operation. The circuit connects the coarse error signal to the input of the servo amplifier 123 and the output of the servo amplifier to the coarse motor 25.

At the same time, the brake 116 and the clutch 123 are actuated. The brake releases the carriage 9, and the clutch disconnects the fine motor 12 so that the coarse motor 25 can drive the car. The acceleration of the carriage is given by the maximum output current of the servo amplifier 123. The maximal Speed is given by the voltage of the amplifier. The gain factor is usually so high that the amplifier works in the range of current or voltage limitation until the Car 9 has reached approximately the position of its address

At this point the gross error signal becomes so small that the servo amplifier 123 is in its linear range device. Since the mass of the carriage 9 is large and the rolling friction is low, the carriage must be braked. This is done electrically by the servo amplifier 123. When the carriage 9 approaches its address, the compensation voltage of the servo amplifier decreases faster than the counter voltage generated by the coarse motor 25. This changes the direction of the motor current and creates a negative torque at the Axis. The size of the countercurrent is limited by the amplifier, causing the negative acceleration is limited.

As the carriage 9 approaches the address, the gross error signal decreases proportionally until it becomes smaller than Δ EC. This value is determined by the coarse comparator 126, which then switches to fine operation. The switchover level ΔEC is selected so that the carriage is in the range of the fine adjustment sensor 120 at the time of switchover. The input of the servo amplifier 123 is also switched from the coarse potentiometer 115 to the demodulator 122. The carriage 9 is now driven by the fine adjustment motor 12 to the zero position of the position guide 120. The zero position is determined at the output of the demodulator by a second comparator 127. If this output is smaller than Δ EF , the carriage 9 is within the required tolerance of the addressed point, and the comparator 127 switches to stop. This actuates the brake 116 in order to hold the carriage on the rail 10. In addition, a signal is sent to the sterndrive so that it can pick up or set down a workpiece.

When the carriage 9 has stopped over the addressed entry or exit point of a processing station recording or filing can begin. If a workpiece is in the holder, it will be on the now stored downstairs; but if the carrier is empty, it becomes one above the point of departure Are in the processing station and have to pick up a workpiece that is available there. This operation is supposed to on the basis of FIG. 13 should be explained. The charge or discharge cycle begins with a signal to the drive motor 140, which is connected to the coupling 142, each engages for exactly one revolution. The corresponding movement is determined by the gears 143 in the ratio 1: 2 ratio and reaches the gear 147, its eccentric 147/4 accordingly two revolutions carry out. The output crank 148 moves the part 151 downwards and once via the guide slot 150 up again, with a certain dwell time at the bottom. The transducer 8 is in this movement guided by the rods 149

During this movement, the holding fingers 160 are opened or closed as the case may be. you will be controlled by the cam disks 145 and 146, which are driven by the gearbox 144 with a 2: 1 ratio, perform half a turn during the cycle. They pneumatically control the fingers 160. The The cams are set so that the fingers close a little later than the downward movement, so that they close when the sensor is practically stationary at the bottom

The fingers 160 are actuated by means of the plunger 170, FIG. 14, which carries a drive plate 171, which engages in recesses 172 of the fingers 160, and an opening and closing of the fingers causes the up and down movement of the plunger Piston 173 driven which slides in bore 174 of block 175. The upper part of the block has a Cylinder head 176, on which the spiral spring 178 is supported, which by means of the support ring 177 the plunger pulls up. The cylinder chamber 179 can be supplied with compressed air through the opening 180 and the connection 181 will. The cap 182 is fastened to the cylinder block, which in turn is connected to the push rod 183 connected is. The push rod is attached to slider 184. A workpiece that is pinched by your fingers can also be held in place by openings at the tips of the fingers that lead to negative pressure will. In order to protect the sensitive semiconductor plates from contamination, the pick-up wears a Cover 185, to which a protective gas can be fed through the hose 186. The operation of the Finger is timed by eccentrics 147Λ and 147B, which actuate valves 145Λ and 146Λ initiate.

The device for processing workpieces will normally be controlled by a computer which is in the control unit 112, Fi g. 10, is included. Programs for the production of various workpieces are stored in the computer's memory, e.g. B. on magnetic tape or disk, available. The programs contain precise instructions for the processing of a workpiece as well as the parameters of the individual treatment steps for each processing station and for the regulation of these parameters depending on the values measured in the individual tests. In addition, the program should determine the sequence of the process steps to be applied and contain the necessary information for the selection of the processing stations that carry out these. Subprograms should be available for all parts to be manufactured, and space should be provided for the inclusion of new such subprograms when new or changed parts are to be manufactured.
To initiate the manufacture of a part, a command is issued to the control device, e.g. B. by an operator at a terminal, with the desired part number, whereupon the associated program part is looked up in the computer memory and transmitted together with the part number of the control device. The various parts of the device are then put into operation, ie caused to assume the state which is necessary for the machining of workpieces. In addition to the main control device, each machining station can have its own control

thus have for the exact setting of the process parameters and for the flow of semiconductor wafers within the station. The processing station can be set so that when a semiconductor wafer is deposited at its entrance, it wanders through the station to the exit, the station control precisely defining the path within the station and the individual process steps and their parameters, such as temperature, gas flow, etc.
The controls of the individual processing stations are connected to the main control, which monitors the flow of workpieces from station to station, performs additional control functions and records the required process parameters. In addition, the main control can be connected to other facilities to support production control, development and construction, quality testing and the overall automation of a company.
The control of process parameters, such as temperature

temperature, flow rate, etc., can be analogous to known or digital means. The selection of these means is based on the required precision, Reliability, costs, compatibility with the control and other common considerations. Sometimes it is desirable that the main control system have certain parameters For example, in semiconductor manufacture, the duration of the process can be a function of the material thickness of the previously machined disc can be controlled. A controller can be provided replacing the station-internal control system. If the main control system fails, the station control system should return to their normal value given by the last signal from the main controller was.

The monitoring of the function also means that the failure of individual devices does not result in too great a loss or the failure of the entire facility, but that still a product of acceptable quality will be produced. The monitoring can be done by additional sensing elements for the parameters in the individual Stations take place. The main control can also set critical parameter values with predetermined limit values Compare and arrange appropriate measures to prevent a Compensate parameter by changing another parameter.

A signal can be generated at essential points through the passage or the presence of a workpiece which makes it possible to track the path of certain workpieces through the facility, and so to determine the quality on the basis of individual workpieces and on the influence of individual parts of the Establishment to draw conclusions.

The logic of the control system is matched to the workpiece path specified for each product through the individual processing stations. The logic is therefore dependent on the status of the output points of the stations, d. H. of the sensor, which indicates whether a workpiece is on these points. In addition, the logic can recognize the state of the transport device, ur-i to decide whether this is for a certain Movement is available. A sequential query of many different sensing elements is therefore necessary.

Based on FIG. 15 it will now be explained how a workpiece is fed through the device. Of the Start 200 puts the control into operation. If it is actuated, control passes to step 201 where determined whether the transport device 2 is available. If the device is busy, so the query is repeated after a short time, until it is found free. If the transport device is free, control passes to step 202; H. to check all processing stations until a station is found that meets the following conditions:

1. The starting point of station K should be occupied;

2. the next station in the process, K + 1 should be ready for operation and

3. The entry point of station K + 1 should be free.

If the answer to at least one of these conditions is no, the control goes to step 208 in order to check whether the exit of the last station K + η is occupied by a finished workpiece. If this is not the case, control returns to 201.

If, however, the exit of the last station is busy, control goes to step 209 for the transport device to cause this workpiece to be removed, and to step 210 which the transport device as occupied. If the movement is ended, then checks whether the workpiece to be contacted is the last one, otherwise control returns to step 201

If a processing station K is found which fulfills the conditions of step 202, control goes to step 203 and causes the transport device to pick up a workpiece at the exit point of station K and to transport it to the entry point of station K + 1. At the same time, according to step 204, the "transport device occupied" signal is switched on, which remains until the transport movement has been completed. If this is the case, the control system returns to the starting point, ie step 201, and the program starts again .
Another operating mode of the control consists in that a workpiece has to pass through certain machining stations 11 several times, either in order to be subsequently fed to the other stations K, K + 1... K + π , or after it has passed through these 16, the program begins again with the start step now designated as 205. It runs first to step 206 for sampling the "transport busy" signal. If this is the case, step 206 is repeated until the transport device is once found to be free, whereupon the control goes to step 207. Here, it is first checked whether a workpiece is at an exit point of a certain station L , which is twice a workpiece is to be run through. If this is the case, step 213 follows, otherwise step 214 takes place.

In step 213 it is determined whether the Operation was the second L operation on this workpiece. If so, step 215 follows, i.e. the Transport device is caused to pick up the workpiece in question, as well as step 216 with the "Transport occupied" signal. After the movement has ended, it is checked in step 217 whether the relevant Workpiece was the last. If this is the case, step 218 follows, the stop. Otherwise the control goes back to the beginning of the program, step 206.

If, however, step 213 shows that the checked station L has not performed the last operation of the prescribed series, control goes to step 219 to determine whether the address register associated with station L contains the address of a station Kx whose entry point is vacant. If this is not the case, step 214 follows, which, as already noted, can also follow step 217. However, if such an address is found, the transport device is caused to bring the workpiece from the exit of station L to the entrance of station L + 1. This takes place in step 220. At the same time, the "transport occupied" signal is switched on in step 221, which disappears when the movement has ended, whereupon the program returns to the beginning, ie to step 206.

In step 214, which follows step 207 and step 219, it is determined whether the entry point of a specific station L is occupied by a workpiece. If this is not the case, step 222 follows, otherwise step 223 follows.

In step 222, all stations Kx are checked for five conditions: Is the exit point of such a station occupied by a workpiece? Lies

there is a plate that is to be processed by station L in the next operation? Is there a station K + 1 whose entry point is free and does this station perform an operation following that of station L ? If a workpiece determined for K + 1 is at the output of L, the important thing here is that no workpiece is there If all the conditions are not met, the control goes to step 223, which also follows step 214 If, however, all conditions are met, thus the transport device is made to pick up a workpiece at the exit of station K and bring it to the entrance of the particular station L. At the same time, in step 225, the K + 1 address corresponding to the subsequent method step is loaded into the register assigned to station L. Here, too, the "transport busy" signal is on during the transport movement, which ensures that the program returns to the beginning of step 206 after the movement has ended

In step 223 the stations Kx are checked in order to find a station which fulfills the following conditions: Is its starting point occupied by a workpiece? Is there a station K + I ₁ that can carry out a subsequent operation? Is K + 1 available and ready? Does K + 1 have a free entry point? If all conditions are not met, then step 224 follows, otherwise step 225 follows, which causes the transport device to bring a workpiece from the exit of station K to the entrance of station K + 1. The "transport busy" signal monitors the movement and, when it ends, causes the program to return to the beginning of step 206. If all the conditions of step 223 are not met, a check is made in step 224 to determine whether a station Kx is performing the last operation on a workpiece. If this is not the case, the program goes back to the beginning, to step 206. If, however, a station Kx has carried out the last operation on its workpiece, then in step 227 the transport device is caused to remove the relevant finished workpiece from the device. Again, the movement is monitored by the "transport occupied" signal. When it has ended, the check follows again as to whether the workpiece was the last, and if that is the case, stop 230. Otherwise, the program returns to the beginning, to step 206.

In Fig. 17 shows the principle of a control system in which processing stations for the same process steps are available two or more times in order to increase the capacity. For example, two pattern generators 6, FIG. 1, can be present if the capacity of one generator is insufficient. In this operating mode, the program begins again with start 240, whereupon it comes to step 241, which determines whether the transport device is occupied because it is currently occupied moving a plate. If it is busy, the step is repeated until it is found free, whereupon the program continues to step 442. Here, the starting points of the multiple stations L are first checked to determine whether there is a workpiece. If this is the case, step 243 follows, otherwise step 244.

In step 243 it is checked whether the station in question that is present multiple times is the last station in the manufacturing process. If this is the case, step 245 follows, otherwise step 246. In step 245 the transport device is caused to pick up the workpiece at the exit of station L and to bring it to the exit of the device. The transport movement is monitored in step 247 with subsequent determination as to whether the workpiece is the last with either a subsequent stop or a return to the start of the program, to step 241.

If, however, it is determined in step 243 that the duplicate station L is not the last station in the manufacturing process, then in step 246 it is determined whether a station L + 1, which can carry out the next operation, has a free entry point. assign a register to each station L which contains the address of station L + 1 for the subsequent operation

If there is no free entrance to a station L + 1, the program goes to step 244, which optionally also follows step 242. If, however, the entrance to station L + 1 is free, the program goes to step 250, where the transport device is initiated to pick up the workpiece lying at the exit of station L and bring it to the entrance of that station L + 1 whose address is read in the register assigned to station L. The movement is monitored in step 251 occupied by the "Transport" -Signai, the disappearance of the program to the beginning, leads back to step 241. If it is determined in step 242 that no starting a station L is occupied by a workpiece, or if the In step 246 it is determined that no entry of a station L + 1 is free, the program goes to step 244. There it is determined whether a station L has a free entry point. If this is the case, step 252 follows.

In step 252 the existing stations K are checked one after the other with regard to five different conditions: Is their starting point occupied? Should the next operation be carried out by a station L ? Is the entrance of a station K + 1 free? Is there a workpiece in a station L on which the next operation is to be carried out by a station K + 1? Is a workpiece determined for K + 1 in an L output, whereby the important thing here is that this is not the case? If a station is found which fulfills all the conditions, step 253 follows, which causes the transport device to pick up a workpiece at the exit of a station K and bring it to the entrance of a station L. In step 254 the address of the next station K + 1 is simultaneously set in the register of station L , in step 255 the transport device is monitored and, after its completion, the program is switched back to the starting point in step 241.

If the conditions of steps 244 or 252 were not or not all met, in program step 251 the stations K are checked for four further conditions: Does a station K have an exit point occupied by a workpiece? Should the next operation after the one carried out by K be carried out by a station K + 1? Is station K + 1 ready for work? Is the entrance point of station K + 1 free? If no station fulfills all of these conditions, step 258 follows, otherwise in step 256 the transport device is caused to pick up a workpiece at the exit of K and bring it to the entrance of K + 1. The movement is monitored in step 257, and then the program goes back to the beginning, to step 241.

In step 258 it is checked whether a station K is carrying out the last operation of the manufacturing method. If this is not the case, the program goes back to step 241, otherwise in step 259 the transmission

causes port device to pick up a workpiece at the output of K and lead it out of the device. The movement is monitored in step 260, whereupon it is determined in step 261 whether the workpiece is the last of the series, and accordingly either the stop 262 follows or the program returns to the beginning, to step 241

FIG. 18 shows an adaptation of the control described in connection with FIG. 17 for the production of field effect transistors, as it was discussed earlier in connection with FIG. As mentioned there, one needs an oxidation station \ A, a source drain diffusion station IS ₁ a gate oxidation station IC two pattern generators 6, which are in the treatment station IZ? are combined, a metallization station IE and a sintering station IF. For the sake of simplicity of description, the stations are grouped into two groups. The first group includes the pattern generators 6, through which the semiconductor wafers pass several times. The stations of the other group are to be called "manufacturing stations" here. The semiconductor wafers to be processed follow a fixed path through the device which has branches to the production stations and to the pattern generators

In step 267, FIG. 18A, become the exit points the pattern generator 6 checked. If there is no plate at any output, then step 268 follows Plate found, step 269 follows which causes the transport device to pick up this plate and close it to bring the station, the address of which is read in a register assigned to the pattern generator will. The movement is monitored in step 270, and upon completion, the program returns to the beginning, step 266. In step 268 the inputs the pattern generator 6 checked. If no free input is found, the program returns to Start, back to step 266, otherwise step 271 follows.

Regarding steps 267, 268 and 271 it should be noted that if several movements appear possible at the same time, the priority is determined by the scanning order. For step 269 it is not necessary to check the status of the following station, as a plate cannot get to a pattern generator can if the entrances of the following stations are occupied.

In step 251 the stations K, that is to say here all stations with the exception of the pattern generators, are checked for four conditions: Is a plate at the exit of a station K ? This check is repeated for different stations until an occupied exit is found. If a plate is found at an exit, the check continues, is the entrance of a station K + 1, to which the plate is to be brought via the pattern generator 6, free? Is station K + 1 ready for operation? Is a plate intended for station K + 1 already in a pattern generator? If no station is found which fulfills all of the conditions, step 272 follows, where a check is made to determine whether the last disk has been processed. If this is the case, then step 273 follows, the stop. Otherwise the program loops back to the beginning, step 266.

If a station K can be found in step 271 which fulfills all conditions, then step 274 follows, picking up a workpiece at the output of station K and depositing it at the input of the pattern generator 6, which was determined to be free in step 268. At the same time, in step 275, the address of the previously determined station K + 1, to which the plate is to come from the pattern generator, is set in the register assigned to it. The "transport busy" signal monitors the movement in step 276 and ensures that the program returns Beginning after its completion.

In addition 18 sheets of drawings

Claims (3)

Patent claims: 1. Control device for a transport device for the production and processing of small workpieces of the same type in the manner of planar semiconductor components in automatically successive processing steps in a plurality of processing stations, the transport device connecting the processing stations with transport paths for the individual transport of the workpieces on workpiece carriers between any individual processing stations in any desired Has feed direction and sequence, with workpiece mills for identifying the individual workpieces or workpiece carriers provided with corresponding codes and their respective position, characterized in that for controlling the transport of the workpieces by means of a sensor monitoring device, which the determined addresses of a recording control ( 111) , an A.dreßinatrix (124) constantly the respective position of a «workpiece carrier (8, 9; 31, 34, 36, 39, 52, 60, 62, 67, 69, 75, 81, 84, 86, 95, 98, 101) supplies first analog signals indicating the target address and a second analog signal indicating the target address to a coarse comparator (126) which continuously determines the difference values and these for controlling the workpiece carriers (8,9; 31,34,36 ...) a coarse position amplifier (125) that supplies while initially the difference exceeds a predetermined first difference value (JEC) and feeds it to a Feinstellungsdemodulator (122) falls below this first difference value (AEC), and that corresponding to the turned-amplifier (125, 122) by means of a coarse motor (25) or a fine motor (12) the transport speed of the workpiece carrier (8, 9; 31,34,36 ...) is determined differently. 2. Device according to claim 1, characterized in that at each possible destination address one with one on the workpiece carrier (8, 9; 31, 34, 36, 39, 52, 60, 62, 67, 69, 75, 81, 84, 86 , 89,95,98, 101) located fine adjustment sensor (120) interacting sensing element (121) is arranged and adjusted such that when switching from coarse to fine drive, the fine adjustment sensor (120) is in the area of the sensing element (121) 3. Device according to claims 1 and 2, characterized in that the fine adjustment motor (12) can be controlled by means of a fine comparator (127) which can be switched on by the fine adjustment modulator (122), in such a way that when the value falls below a second differential value (J EF) asr fine comparator (127 ) supplies a stop signal to the fine motor (12).