DE10353076A1 - Monitor for drying installation for semiconductor wafers, working according to Marangoni principle, with installation containing dipping bath with lifting chamber, to which is coupled supply of mixture of drying substance and carrier gas - Google Patents

Abstract

Drying installation for flat workpieces, such as semiconductor wafers (4) contains dipping bath (11), above which is fitted lifting chamber (12) to which is coupled supply (2) of drying substance and carrier gas mixture. To lifting chamber is coupled sensor (81) of drying substance concentration in lifting chamber during drying process. To sensor is connected evaluator (82) determining when drying substance concentration is below rated minimum. Preferably to mixture supply is coupled mixture control unit (26,31), to determine necessity for adjusting mixture supply. Independent claims are included for drying installation and its monitoring.

Description

The The invention relates to a monitoring device for one drying machine based on the Marangoni principle flat objects in particular of semiconductor wafers, a dipping bath, an over the Immersion bath arranged lifting chamber and connected to the lifting chamber Having a drying substance / carrier gas mixture feed, a corresponding dryer system and a method for monitoring such a dryer.

to Production of integrated circuits on semiconductor wafers is Absolute cleanliness required, as every pollution becomes one Change in the Structure of the disk surface or the doping and charge conditions in the semiconductor crystal can lead. This then has a negative effect on the yield of functional components as well as on the reliability and long-term stability of the circuits. In the manufacturing process of integrated circuits Therefore, on semiconductor wafers, multiple cleaning sequences are usually incorporated, around the disc surface to eliminate deposited impurities. A cleaning sequence usually includes a treatment of the semiconductor wafer with a chemical substance, a subsequent rinsing with pure water or Ultrapure water or deionized water, these terms in the Further always be used synonymously, and a final drying process.

When Alternative to drying the wafer slice with a spin-dry in nitrogen atmosphere is doing in the youngest Time reinforces that so-called Marangoni drying used. Marangoni drying For example, the semiconductor wafers are made of a bath filled with deionized water in an over the water bath preferably containing isopropanol (IPA) the atmosphere raised. When slowly pulling out the semiconductor wafer from the Water bath forms a thin one Water film on the semiconductor wafers off. This thin film of water becomes stronger with isopropanol from the gas atmosphere as the larger amount Water in a water bath. This difference in concentration causes a osmotic pressure, the thin one Drawing down water film on the semiconductor wafer into the water bath, the so-called Marangoni effect, whereby the semiconductor wafer is dried. Decisive for The drying process is the proportion of isopropanol in the above de-ionized water bath prevailing atmosphere. Alternative to use Of isopropanol but there is the possibility of others easily volatile, hydrophilic substances, e.g. Ethanol, for the Marangoni drying process use.

The Isopropanol atmosphere above the de-ionized Water bath is usually by supplying a nitrogen-isopropanol mixture produced, the gaseous Nitrogen in a liquid Isopropanol filled Gas blender bottle, a so-called bubble bottle is fed, in which the injected nitrogen then entrains isopropanol molecules and so evaporated. When the isopropanol content in the atmosphere is above the de-ionized Water bath during the drying process, z. B. due to a leak in the isopropanol-nitrogen mixture feed to the Marangoni dryer, there is a risk of insufficient drying of the semiconductor wafers, causing water marks on the disk surface, which then increases Defects in the subsequent formation of integrated circuits on the semiconductor wafers and so to a malfunction of this lead integrated circuits can.

Around such a leak in the isopropanol-nitrogen mixture feed during the drying process be able to determine in time is usually in the isopropanol-nitrogen mixture feed a pressure sensor integrated to monitor whether the mixture with defined pressure, indicating a leakage free feed indicates that it will be fed into the Marangoni dryer. Despite one such pressure monitoring However, in practice, deficiencies in the drying process continued to occur due to insufficient drying and thus unwanted water marks on the semiconductor wafers. Besides, it is with the pressure sensor in the mixture feed usually only possible determine the pressure drop itself, but without the leak in the Accurately locate isopropanol-nitrogen mixture feed to be able to. There is also no possibility at the present time known Marangoni dryers actively the isopropanol content in the atmosphere above the Water bath, and so on a defined proportion of isopropanol in the atmosphere above the Water bath.

task The invention is a monitoring device for one according to the Marangoni principle working dryer, a corresponding Drying system and a method for monitoring such a dryer to provide a reliable Dry flat objects in particular semiconductor wafers, through close monitoring allow the drying process.

These Task is by a monitoring device according to claim 1, a system according to claim 7 and a method according to claim 9 solved. Preferred developments are specified in the dependent claims.

According to the invention is at a dryer working according to the Marangoni principle, below Also known as Marangoni dryer, for drying flat objects, in particular semiconductor wafers, the one dip, one over the immersion bath arranged lifting chamber and connected to the lifting chamber Drying substance carrier gas mixture supply has the drying substance concentration in the lifting chamber during the Drying process by means of a connected to the lifting chamber Dry matter concentration sensor detected and determined Drying substance concentration using an evaluation unit is evaluated to be below a minimum drying substance concentration in the lifting chamber during determine the drying process and then optionally one corresponding alarm signal to an operator of the Marangoni dryer system issue. As drying substance we prefer isopropanol and as a carrier gas preferably nitrogen is used.

By the monitoring of the invention Drying substance concentration in the lifting chamber during the Drying process is ensured that for the success of the drying successively controlled parameters and a drop below a minimum drying substance concentration, which ensures effective drying, is detected. Continue lets by determining the drying substance concentration in the supplied drying substance-carrier gas mixture reliable monitor the course of the drying process and in case of deviations from Expected value for corresponding leaks at the Marangoni plant, especially in the drying substance carrier gas supply.

According to one preferred embodiment dependent from that determined by the drying substance concentration sensor Drying substance concentration, the drying chamber-carrier gas mixture supplied to the lifting chamber in relation to the mixture ratio or the feed rate set. As a result, a continuous adjustment of the drying substance concentration in the Hubkammer during the drying process to one for optimum drying success required value guaranteed.

According to one another preferred embodiment is in addition to the drying substance concentration continuously the Monitors the temperature of the drying substance / carrier gas mixture fed to the Marangoni dryer during the drying process, wherein by means of the evaluation unit of the drying substance concentration sensor determined drying substance concentration with the temperature determined by the temperature sensor is correlated, by falling below a minimum correlation value or exceeding a maximum correlation value determine. By determining the temperature of the drying substance-carrier gas mixture and their correlation with the proportion of drying substance in the mixture can be relatively reliable on the exact cause of error depending on the direction of a deviation from an expected correlation value. This is especially true when the drying substance-carrier gas mixture using a Mixture is produced in which the carrier gas in a tank is introduced with the drying substance. The temperature the drying substance-carrier gas mixture is attached such a mixture preparation in a linear relationship with the drying substance concentration in the mixture, with a tearing of the correlation value up or down each for a specific error image in the drying substance-carrier gas mixture production speaks.

According to one another preferred embodiment In the drying substance-carrier gas mixture production, the Temperature of the drying substance-carrier gas mixture to a predetermined Adjusted temperature value, so as to achieve a desired drying substance concentration in the drying substance-carrier gas mixture to obtain. This temperature control is easy a precise setting of the for the drying success decisive drying substance proportion in the Drying substance-carrier gas mixture guaranteed whereby a particularly simple and highly accurate mixture control achieve.

The Invention will become apparent from the accompanying drawings explained in more detail. It demonstrate:

1 schematically a conventional Marangoni dryer system, with possible leaks are marked;

2 a schematic representation of the Marangoni drier effect;

3 a Marangoni dryer system according to the invention with monitoring device;

4 a course of the isopropanol concentration in the lifting chamber of the Marangoni dryer plant during a drying process;

5 a diagram with the isopropanol concentration and the temperature of the isopropanol carrier gas mixture in a sequence of several, performed in the course of a day Marangoni drying operations;

6 a calibration diagram in which the isopropanol concentration is plotted against the temperature of the isopropanol / carrier gas mixture, with measurements taken, the expected correlation values and the minimum and maximum deviations recorded; and

7 a table with four possible fault scenarios and the associated alarm operations in the monitoring device according to the invention and in the conventional pressure sensor or nitrogen flow sensor device.

The starting point of the present invention is a conventional Marangoni-based dryer system, as shown schematically in FIG 1 is shown. Such a plant, also referred to below as the Marangoni dryer plant, has a Marangoni chamber 1 and an isopropanol carrier gas mixture feed 2 on. The Marangoni Chamber 1 in turn, essentially consists of an immersion bath 11 and one above the dipping bath 11 arranged lifting chamber 12 together. The dipping bath 11 contains a rinsing or cleaning fluid 6 , usually de-ionized water. In the dipping bath 11 can a cassette 3 with a plurality of semiconductor wafers arranged in parallel in the cassette 4 be lowered by means of a charging device (not shown) until the semiconductor wafers completely in de-ionized water 6 are immersed. As an alternative to using a cassette, however, a so-called "carrierless" method can also be used for the drying process. To the during the drying process from the dipping bath 11 displaced de-ionized water 6 are laterally around the dip 11 around overflow possibilities 15 provided in 1 are indicated schematically by arrows. The arranged above the immersion Hub Hubkammer 12 Can with the dip 11 be locked and has a gas inlet 16 on, via the isopropanol carrier gas mixture feed 2 can feed the appropriate mixture. Nitrogen is generally used as the carrier gas.

The one with the in 1 Marangoni drying plant executed drying process is shown schematically in 2 shown. For drying the semiconductor wafers, the semiconductor wafers are in a first step 4 in the cassette 3 placed and in the Marangoni chamber 1 brought in. This is usually the Hubkammer 12 from the dipping bath 11 removed and using a loading device, the cassette 3 with the semiconductor wafer 4 over the immersion bath filled with de-ionised water 11 brought. Then the lifting chamber 12 with the dip 11 locked and the cassette 3 with the semiconductor wafers 4 in the dipping bath 11 with the de-ionized water 6 lowered until the semiconductor wafers 4 completely immersed in the deionized water.

After complete immersion is via the gas inlet 16 the isopropanol-nitrogen mixture in the Hubkammer 12 blown. The proportion of isopropanol in the isopropanol / nitrogen mixture is preferably chosen so that it is at least 14%. The deionized water in the dipping bath 11 When adding the isopropanol-nitrogen mixture slightly accumulates with isopropanol. Once the lifting chamber 12 is completely filled with the isopropanol-nitrogen mixture is, as in 2 is shown schematically, the cassette 3 with the semiconductor wafers 4 from the dipping bath 11 in the direction of the lifting chamber 12 raised. It forms, as in 2 shown is a thin film 41 from deionized water on the semiconductor wafer lifted out of the deionized water bath 4 however, due to the Marangoni effect of slowly lifting the semiconductor wafer 4 in the dipping bath 11 is subtracted, as in 2 using arrows 42 is shown.

With this technique based on the Marangoni effect, residue-free drying of the semiconductor wafers can be achieved 4 be achieved. Decisive for the drying success, ie a uniform drying of the surface of the semiconductor wafer 4 with no remaining water spots, that is the isopropanol-nitrogen mixture in the lift chamber 12 has a sufficient proportion of isopropanol. As an alternative to the use of isopropanol, it is also possible to use another volatile, hydrophilic drying substance, such as ethanol, for the Marangoni drying process.

The isopropanol-nitrogen mixture feed 2 as shown schematically in 1 is shown, has as a central element known as a bubble bottle gas mixing bottle 21 on that in a lower area 22 with isopropanol 5 is filled. To the gas mixing bottle 21 are still a gas supply 24 and a gas discharge 25 connected, the gas supply 24 into the gas mixing bottle 21 down to the bottom 22 with the liquid isopropanol 5 extends to nitrogen in the isopropanol liquid 7 be able to feed as a carrier gas. The gas discharge 25 extends into the upper area used for gas evolution 23 the gas mixing bottle 21 , The nitrogen supply 24 the gas mixing bottle 21 is via a first nitrogen flow regulator 26 and a first nitrogen flow valve 27 to a nitrogen supply 28 connected. The gas removal 25 the gas mixing bottle 21 in turn, is via an isopropanol-nitrogen flow-through valve 29 to the isopropanol-nitrogen mixture inlet 16 the lifting chamber 12 the Marangoni dryer 1 connected. Out going from the nitrogen supply 28 and the first nitrogen flow valve 27 closes another nitrogen supply line 32 in which a second nitrogen flow regulator 31 is provided via a second nitrogen flow valve 30 to the isopropanol-nitrogen mixture inlet 16 at.

To generate the isopropanol-nitrogen mixture, nitrogen from the nitrogen supply 28 via the first nitrogen flow valve 27 , the first nitrogen flow regulator 26 and the gas supply 24 in the gas mixture bottle 21 in the lower part 22 contained isopropanol liquid 5 blown. The injected nitrogen 7 then rises through the isopropanol liquid and thereby rips isopropanol molecules, so that in the upper part 23 the gas mixing bottle 21 forms an isopropanol-nitrogen mixture, via the gas discharge 25 the isopropanol-nitrogen flow-through valve 29 the isopropanol-nitrogen mixture inlet 16 the Marangoni Chamber 1 is supplied.

During the drying process, the nitrogen or isopropanol nitrogen supply via the gas inlet 16 controlled so that after dipping the cassette 3 with the semiconductor wafer 4 in dipping the first nitrogen flow valve 27 after the nitrogen supply and the isopropanol-nitrogen flow valve 29 after the gas mixing bottle 21 be opened to an isopropanol-nitrogen mixture in the Hubkammer 12 above the dipping bath 11 blow. To determine if a sufficient amount of isopropanol carrier gas mixture in the Hubkammer 12 is reached, is in front of the gas inlet 16 the Marangoni Chamber 1 a pressure sensor 33 provided the gas pressure in the lifting chamber 12 determined. After reaching a stable state then the cassette 3 with the semiconductor wafers 4 from the dipping bath 11 pulled out to dry the surfaces of the semiconductor wafers using the Marangoni effect. After complete withdrawal of the cassette with the semiconductor wafers, the deionized water then becomes 6 from the dipping bath 11 drained and then the Marangoni chamber 1 with nitrogen 7 rinsed. This is the isopropanol-nitrogen flow valve 29 in the gas discharge 25 after the mixture bottle 21 closed and at the same time becomes the second nitrogen flow valve 30 in front of the gas inlet 16 the Marangoni Chamber 1 opened to nitrogen over the first nitrogen flow valve 27 , the second nitrogen flow regulator 31 and the second nitrogen flow valve 30 in the lifting chamber 12 to blow in and so the Marangoni chamber 1 to wash. Then, the first nitrogen flow valve will be activated 27 closed and the drying process ended.

An essential parameter for the success of the drying process is the isopropanol concentration in the lifting chamber 12 the Marangoni Chamber 1 during the lifting of the cassette 3 with the semiconductor wafers 4 , In the conventional Marangoni plants, the isopropanol content in the isopropanol-nitrogen mixture is determined using the first nitrogen flow regulator 26 after the nitrogen supply 28 adjusted the flow of the liquid in the isopropanol 5 fed nitrogen 7 controls and thus the nitrogen vaporized as a carrier gas isopropanol content. At the same time, using the upstream of the isopropanol carrier gas inlet 16 arranged in the Marangoni chamber pressure sensor 33 the possibility to monitor the pressure of the isopropanol-nitrogen mixture and, if appropriate, to trigger an alarm in the event of a pressure drop which indicates an insufficient supply of the Marangoni chamber with isopropanol-nitrogen mixture.

With the pressure sensor 33 However, it is not possible to monitor the concentration of isopropanol in the Marangoni chamber during the drying process and then, if necessary, take measures based on the determined concentration value to ensure adequate supply of the Marangoni chamber with isopropanol during the drying process. Furthermore, it is not possible to conclude with the pressure sensor on the exact cause of the pressure drop in the isopropanol-nitrogen mixture supply. In particular, the pressure sensor does not strike when, although the pressure of the supplied isopropanol-nitrogen mixture remains the same, but the proportion of isopropanol in this mixture decreases.

Improved monitoring is achieved when, in addition to the gas pressure of the mixture monitored by the pressure sensor, the nitrogen flow rate regulator is positioned after the nitrogen supply 26 . 31 the nitrogen supply to the gas mixing bottle 21 or to the Marangoni Chamber 1 is monitored. However, even with such monitoring, not all of the errors occurring in the isopropanol-nitrogen mixture feed can be clearly identified. In particular, one can be in the isopropanol-nitrogen mixture feed 2 Do not detect the leak that occurs. Possible leaks in the isopropanol carrier gas feed 2 In particular at the connection points in the area of the flow valves, the flow regulator, the inlet and outlet in the gas mixing bottle and at the feed to the Marangoni chamber and are indicated by arrows in 1 characterized.

To ensure reliable monitoring and control of the drying process in a Marangoni dryer plant, in particular with regard to the decisive for the drying process Isopro To make panol concentration during the drying process, according to the invention is a monitoring device 8th for a conventional, in 2 featured Marangoni dryer plant, as in 3 is shown schematically. The central element of the monitoring device is an isopropanol concentration sensor 81 that with the lifting chamber 12 the Marangoni Chamber 1 is connected to running, especially during the drying process, in which the isopropanol-nitrogen mixture in the lifting chamber 12 blown in and the cassette 3 with the semiconductor wafers 4 from the de-ionized water 6 filled dipping bath 12 is being monitored. The isopropanol concentration sensor 81 in turn is with an evaluation unit 82 connected to the isopropanol concentration sensor 81 The measured isopropanol concentration values are continuously recorded and displayed to the operator of the Marangoni system.

4 shows the of the concentration sensor 81 measured isopropanol concentration in the atmosphere of the lifting chamber 12 during a drying process. Between time T0 to time T1, at which the cassette 3 with the semiconductor wafers 4 into the deionized water 6 contained immersion bath 11 is lowered, no isopropanol-nitrogen mixture in the Hubkammer 12 blown in, leaving the isopropanol concentration sensor 81 measured concentration 0 is. At time T1, the isopropanol-nitrogen pass valve then becomes 29 opened and isopropanol-nitrogen mixture in the Hubkammer 12 initiated, at the same time the cassette 3 with the semiconductor wafers 4 from the dipping bath 11 is raised. This lifting and drying process is then completed at time T2. At the beginning of the lifting and drying process rises from the isopropanol concentration sensor 81 measured isopropanol concentration quickly to reach the desired for the drying process isopropanol saturation value, which preferably corresponds to an isopropanol content of 15%.

At time T2, when the cassette 3 with the semiconductor wafers 4 completely from the dip 11 lifted and the disc surfaces are dried, then the deionized water 6 from the dipping bath 11 drained again. During this venting process, which is completed at time T3, the isopropanol concentration continues to increase because there is no isopropanol enrichment of the deionized water 6 more is done. At time T3 then the isopropanol-nitrogen flow valve 29 closed and nitrogen by opening the second nitrogen flow valve 30 in the lifting chamber 12 blown in for rinsing. The isopropanol concentration sensor therefore measures a rapidly decreasing isopropanol concentration until time T4, when the isopropanol is completely removed from the lift chamber 12 is rinsed out.

For the drying process is crucial that between the time T1 and T2 a defined isopropanol concentration in the Hubkammer 12 present on the semiconductor wafers 4 when pulling out forming water film 41 into that with de-ionized water 6 filled immersion bath 11 to displace. The evaluation unit 82 is therefore set so that if, between time T1 and T2, the isopropanol concentration reached falls below a minimum isopropanol concentration level again, an alarm is issued indicating that there is a problem with isopropanol gas production which is the drying process endangered. The in the evaluation unit 82 set minimum isopropanol concentration is preferably set to 14%.

By the procedure according to the invention of monitoring the proportion of isopropanol in the lifting chamber of the Marangoni dryer during the drying process, it can be reliably determined whether a residue-free drying of the pane surfaces takes place. By monitoring a lower limit for the minimum isopropanol concentration, the operator of the Marangoni dryer plant will still be given the opportunity to take countermeasures that stabilize the isopropanol content in the lift chamber, if necessary. This can preferably also be done automatically by the evaluation unit 82 via the nitrogen flow regulator 26 . 31 actively the nitrogen supply into the gas mixing bottle 21 or the Marangoni dryer 1 is regulated. Furthermore, it is also possible to monitor, in addition to a limit value for the minimum isopropanol concentration, a limit value for a maximum isopropanol concentration and, if necessary, countermeasures via activation of the passage controllers, in particular of the first nitrogen passage regulator 26 to ensure a uniform mixture of isopropanol and nitrogen within a permitted range.

Furthermore, a drop below a minimum isopropanol concentration during the drying process is an indication of a possible leak in the Isopropanpol-nitrogen mixture feed 2 so that the operator is prompted to perform a check on the feeder. In the prior art, such a defect image is not displayed during the drying process, so that generally time-consuming test drying was carried out in order to be able to determine a plant test and possibly leaks.

In case of falling below a minimum correlation value or exceeding a maximum correlation value a corresponding alarm give or

In order to achieve a further improved monitoring of the drying process, according to the invention with the gas mixing bottle 21 connected temperature sensor 83 provided with the evaluation unit 82 connected to the temperature of the gas mixing bottle 21 during the mixing process constantly hold. It has been shown that the temperature of the gas mixing bottle 21 is linearly correlated with the isopropanol content in the isopropanol-nitrogen mixture. In addition, the inventors have found that the time sequence of the drying operations of semiconductor wafers has a significant influence on the temperature of the gas mixing bottle and thus on the isopropanol content in the gas mixture.

5 shows the measured isopropanol content for semiconductor wafer drying operations over the course of a day, with a different time interval between successive drying processes. Furthermore, the respectively measured temperature of the gas mixing bottle 21 in 5 shown. During the measurements, the plant conditions for the successive drying processes, in particular the time and quantity control of the nitrogen feed in the gas mixing bottle and the lifting chamber, were kept constant. Out 5 shows that despite constant plant conditions, the isopropanol concentration varies between the various drying processes in a proportion of 17% to 30%, at the same time the temperature varies between 12 ° and 21 °. Furthermore, from the in 5 derived measurements, that when time closely consecutive drying operations are carried out, at the same time the proportion of isopropanol and the temperature of the gas mixing bottle from drying process to drying process fall. Conversely, the isopropanol concentration and temperature increase over a long period of time between two consecutive drying operations.

reason for the Fluctuations in the isopropanol content of the gas mixture and in the Temperature of the gas mixing bottle is the evaporation cold that is in the production of the isopropanol-nitrogen mixture by feeding of gaseous nitrogen in liquid Isopropanol gives. The energy needed to vaporize the isopropanol molecules takes care of a cool down of the liquid Isopropanol in the gas mixing bottle, which in turn reduces the evaporation energy for the Isopropanol molecules increased. This then has the consequence that the proportion of isopropanol in the gas mixture is reduced.

According to the invention, therefore, it is provided that the temperature of the gas mixing bottle during the drying process continuously through the temperature sensor 83 to monitor, with the evaluation unit 81 records and evaluates the measured temperature values. If the temperature falls below a minimum temperature or a minimum concentration determined therefrom for the gas mixing bottle, then an alarm can be output by the evaluation unit, so that the operator of the Marangoni dryer installation can initiate countermeasures if necessary. However, preferred is an automatic temperature control, using a heater 84 the temperature of the gas mixing bottle is increased. The heating is preferably as in 3 shown in the field of nitrogen supply 28 arranged to heat the nitrogen gas fed into the liquid isopropanol of the gas mixing bottle. A direct heating of the gas mixing bottle could in fact lead to an explosion of the explosive isopropanol gas.

It is furthermore preferred that the evaluation unit 82 the at the gas mixing bottle 21 from the temperature sensor 83 measured temperature with the in the Hubkammer 12 the Marangoni dryer from the isopropanol concentration sensor 81 measured isopropanol concentration correlated to output when falling below a minimum correlation value or exceeding a maximum correlation value, a corresponding alarm or via control of the heating 84 and the pass-through controller 26 . 31 , in particular the first nitrogen passage regulator 26 to carry out a corresponding readjustment in order to bring the correlation value back into the permitted bandwidth.

In 6 is one of the evaluation unit 82 used calibration program in which the target correlation value between isopropanol content and measured at the gas mixing bottle temperature for a temperature range of 10 ° to 25 ° is specified. In addition, the respective upper and lower limit values are provided for the minimum correlation value and the maximum correlation value, ie a possible bandwidth for measured values. Furthermore, correlation values calculated in the form of points measuring data of the isopropanol concentration and the associated temperature are drawn. For the measuring points above the maximum correlation values or below the minimum correlation values, which are not in the band width around the target corridor, then the evaluation unit 82 Alarm triggered or carried out the explained readjustment.

7 lists in tabular form various defect images that have been generated as part of a simulation, and provides the associated response of the isopropanol temperature sensor according to the invention and the pressure and stick available in conventional Marangoni plants substance flow regulator facing each other. The table clearly shows that the combined monitoring of isopropanol concentration and temperature of the gas mixing bottle according to the invention responds to all defects, whereas the conventional pressure sensor or nitrogen flow regulator does not respond.

All Systems give alarm when there is no nitrogen flow and no isopropanol-nitrogen flow available. The isopropanol temperature sensor then determines no isopropanol content, the pressure sensor one Pressure drop and the nitrogen flow regulator a reduced flow. If, however, only the Isopropanpol-nitrogen flow is interrupted, this is indeed from the isopropanol temperature sensor determined, since then again no isopropanol is present and continue also from the nitrogen flow regulator, which has a reduced flow not against the pressure sensor. This also applies to the case that no nitrogen flow is present, the isopropanol temperature sensor then determines that the correlation value is above the threshold. The nitrogen flow regulator will then turn lower Flow firmly. In the event, however, that a leak in the isopropanol-nitrogen mixture feed after the gas mixing bottle occurs, this is only by the isopropanol temperature sensor by a correlation value below the threshold detected, but not by the pressure sensor or the nitrogen flow controller. About that In addition, the isopropanol temperature sensor monitoring device may individual errors, but not the conventional one Pressure or nitrogen flow controller.

1

Marangoni chamber

2

Isopropanol-carrier gas mixture feed

3

cassette

4

Semiconductor wafer

5

isopropanol

6

de-ionized water

7

nitrogen

8th

monitoring device

11

dip

12

stroke chamber

15

Overflow facility

16

gas inlet

21

Gas mixing bottle

22

lower Area of the gas mixing bottle

23

upper Area of the gas mixing bottle

24

gas supply

25

gas discharge

26

first Nitrogen flow regulator

27

first Nitrogen flow valve

28

nitrogen supply

29

Isopropanol nitrogen flow valve

30

second Nitrogen flow valve

31

second Nitrogen flow regulator

32

nitrogen inlet

33

pressure sensor

41

water film

42

Wasserabstreifrichtung (Arrow)

81

Isopropanol concentration sensor

82

evaluation

83

temperature sensor

84

heater

Claims (14)

Monitoring device for a Marangoni-operated dryer for drying flat objects, in particular semiconductor wafers ( 4 ), which is a dip ( 11 ), a lifting chamber arranged above the immersion bath ( 12 ) and a drying substance-carrier gas mixture feed connected to the lifting chamber ( 2 ), characterized by a with the Hubkammer ( 12 ) drying substance concentration sensor ( 81 ) for determining the drying substance concentration in the lifting chamber during the drying process and an evaluation unit connected to the drying substance concentration sensor ( 82 ) for detecting a drop below a minimum drying substance concentration in the lifting chamber during the drying process. Monitoring device according to claim 1, characterized by a with the drying substance-carrier gas mixture supply ( 2 ) connected mixture control unit ( 26 . 31 ), depending on the drying substance concentration determined by the drying substance concentration sensor, that via the drying substance-carrier gas mixture feed ( 2 ) in the Hubkammer ( 12 ) to adjust supplied drying substance-carrier gas mixture. Monitoring device according to claim 1 or 2, characterized by a with the drying substance-carrier gas mixture supply ( 2 ) connected temperature sensor ( 83 ) for determining the temperature of the drying substance / carrier gas mixture supplied to the dryer during the drying process, wherein the evaluation unit ( 82 ) from the drying substance concentration sensor ( 81 ) determined drying substance concentration correlates with the temperature detected by the temperature sensor and detects a falling below a minimum correlation value and exceeding a maximum correlation value. Monitoring device according to claim 3, characterized by a with the drying substance-carrier gas mixture supply ( 2 ) connected temperature control unit ( 84 ), depending on the temperature sensor ( 83 ) determined temperature the drying substance-carrier gas mixture to adjust the temperature of the drying substance-carrier gas mixture supplied to the Marangoni dryer during the drying process. monitoring device according to one of the claims 1 to 4, characterized in that the drying substance isopropanol is. monitoring device according to one of the claims 1 to 5, characterized in that the carrier gas is nitrogen. Installation for drying flat objects, in particular semiconductor wafers, with a dryer operating according to the Marangoni principle (US Pat. 1 ), which is a dip ( 11 ), a lifting chamber arranged above the immersion bath ( 12 ) and a drying substance-carrier gas mixture feed connected to the lifting chamber ( 2 ), and with a monitoring device according to one of claims 1 to 6. Plant according to Claim 7, characterized in that the drying substance / carrier gas mixture feed comprises a mixture production unit ( 21 ) with a drying substance tank ( 5 ) and a carrier gas feed connected to the drying substance tank ( 24 ) by introducing carrier gas ( 7 ) into the drying substance tank ( 5 ) to produce a drying substance-carrier gas mixture, wherein the temperature sensor ( 83 ) at the mixture production unit and temperature control unit ( 84 ) at a carrier gas feed ( 28 ) is arranged. Method of monitoring one according to the Marangoni principle working dryer for drying flat Ge objects, in particular of semiconductor wafers, which is a dip bath, one above the immersion bath Hubkammer and having a lifting chamber connected drying substance-carrier gas mixture supply, marked by the method steps determining the drying substance concentration in the lifting chamber during the drying process, and  Evaluating the determined drying substance concentration, around below a minimum drying substance concentration in the lifting chamber during to determine the drying process. Method according to claim 9, characterized by the further process step adjusting the drying substance-carrier gas mixture depending on that of the drying substance concentration sensor determined drying substance concentration. A method according to claim 9 or 10, characterized through the further process steps Determine the temperature of the dryer during the Supplied drying process Drying substance-carrier gas mixture, Correlate the determined drying substance concentration with the determined Temperature of the drying substance-carrier gas mixture correlates, and Evaluate the correlation value to a fall below a minimum correlation value and exceeding a maximum correlation value. Method according to one of claims 9 to 11, characterized by the further process step setting the temperature of Drying substance-carrier gas mixture, to a desired drying substance concentration in the drying substance-carrier gas mixture to obtain. Method according to one of claims 9 to 12, characterized that isopropanol is used as the drying substance. Method according to one of claims 9 to 13, characterized that as carrier gas nitrogen is used.