EP3688394A1

EP3688394A1 - Real-time monitoring of a multi-zone vertical furnace with early detection of a failure of a heating zone element

Info

Publication number: EP3688394A1
Application number: EP18799591.5A
Authority: EP
Inventors: Sven GRUBER
Original assignee: X Fab Semiconductor Foundries GmbH
Current assignee: X Fab Semiconductor Foundries GmbH
Priority date: 2017-09-25
Filing date: 2018-09-25
Publication date: 2020-08-05
Also published as: TW201923368A; DE102018101010A1; JP2023109763A; WO2019058358A1; JP7271520B2; CN111433547A; JP2020535646A; KR20200100602A; KR102598971B1; US20200411343A1; TWI808996B

Abstract

The aim of the invention is to help avoid wafer losses in thermal treatment. Wafers have values of up to 150,000 euros per batch. Therefore, unplanned failure of the thermal device for treating the wafers should be avoided. The method according to the invention for monitoring the thermal device(s) (100) for receiving and controlling the temperature of wafer lots or batches of wafers uses a continuously applied measurement of a resistance value (R1) in at least one heating zone (1') of a plurality of heating zones (1', 2', 3', 4', 5') of the thermal device. The currently measured value (R1(i)) of the resistance (1) in the associated heating zone (1') is compared with a previously measured value (R1(i-1)) of the same resistance (1). A warning or an alarm (90) for the thermal device (100) is already generated when a deviation (ΔRi) of the two resistance values from the same heating zone (1') is detected by means of the comparison, said warning or alarm occurring temporally before a failure of a whole heating zone (1) of the thermal device (100). Improved ability to plan resources is a further goal.

Description

Real-time monitoring of a multi-zone vertical furnace

with early detection of a failure of a

Heating zones element

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For wafers US 2010/14749 (Turlure, STM) relates to a wafer oven (there page 10, column 3, paragraphs 45, 46) in which a temperature sensor 29 is arranged. If the measured temperature exceeds a threshold set by the camera 26 mounted there, the oven becomes too hot, or too hot, and the camera used to position the wafer could be damaged. A detection of a failure of the furnace for wafers is not intended here (and also impossible).

US 2009/237102 AI (Lou, Star Technologies) describes a heater for semiconductors and has a temperature control to control the temperature of the furnace. In addition, test signals are provided for the semiconductors in the oven.

DE 39 10 676 AI (Pierburg, Lösing) relates in a remote field a measuring device for air mass flow, this in combustion engines, ie vehicles. Operational measurement errors, e.g. due to deposits or aging, should be avoided. Measurements are taken at intervals, the result of which is compared with the result of a correction caused thereby, cf. there column 5, line 40 to 51 or column 1 from line 52 or for ohmic resistors column 4,

Line 12 ff.

The claimed invention, however, relates to monitoring of the aforementioned individual heating zones (in each of which at least one heating element is located) on premature wear, and thus all heating zones together. Also several systems, each with several heating zones.

Currently, there is no possibility of premature failure of a heating zone

(= Heating zone) to recognize. Thus, there is a high risk for a wafer loss of 150 wafers per system. The Japanese plant manufacturer Tokyo Electron (TEL) has only one method of detecting an actual failure of a heating zone. This kind of thermal monitoring, which reduces the error by dropping the Temperature detects, and a temperature alarm generated at the plant is also offered by other manufacturers.

The mentioned heater from TEL is a vertical 5-zone heater operating in the range of 600 ° C to 1150 ° C. Due to the vertical arrangement and the high

Temperatures deform the individual, just arranged coil (windings) with time and it can come to a contact of two adjacent sections of a winding within a zone (see Figure 1). Due to this effect, the resistance is reduced by a few percent and after a certain time, the winding will break at this point.

Up to now it has not been possible to prematurely detect a heating failure of the five zones during standby or in the process of the system. In the past, several cases of failure occurred. These events occurred on the one hand during the process, by generating a temperature alarm (leads to

Process termination), but also in standby occurred such a termination.

In case of a standby failure, the process of tempering the wafers could still be started because no alarm was generated on the system. The preloaded with valuable wafers process started and was then stopped by a temperature alarm.

Every process loss has a production loss of at least 150 wafers

(300,000 EUR loss costs), a whole lot (or batch) and a long unavailability of about 12 days of the plant result.

Based on the above-described prior art, the invention is based on the following technical problem ... The invention is concerned with the prevention of wafer losses with values of up to 150,000 EUR per batch. In addition, there should be no unplanned failure of the thermal device and better planning of resources.

The claimed invention (claim 1 or claim 18 or claim 20) detects early wear (touching the elements or areas of

Heating winding or the occurrence of a punctual control center in the

Heater winding) to minimize or eliminate the loss of the wafer and to better plan the availability of personnel and materials.

According to the invention, this is done by a permanent measurement of the resistance (obtained from measurements of voltage and current) of each heating zone. The current value of the resistor is compared with the previous value. Even at a low Deviation in the resistance value, an alarm (a warning) is generated for the system, well in time before a failure of an entire heating coil.

The invention uses the effect that a real-time detection in the individual heating zones is permanently implemented and thus early contact within the winding is detected before it finally comes to the winding break. These are the expected error (which is already issued as an alarm message) and the real error (which comes as a winding break).

A detection of an expected error before the actual operation, in the so-called. Standby mode, is possible (claim 5). If the error expectation occurs here, it will not be switched on at all.

The advantages achieved by the invention are in particular that the risk of wafer loss can be significantly minimized by detection of an impending failure, the system is already stopped and z. B. the five-zone heater can be replaced preventively, or even individual heating zones are renewed, or the thermal device is not started before a repair is not done.

The claimed screen display (e.g., claim 20) enables a

Clear monitoring of multiple thermal devices and allows the user to immediately detect system status, even when monitoring a wide variety of equipment or resistors.

Also for carrying out the method according to one of claims 1 to 17 is the

Screen display (efficient) suitable.

It has a configuration pane for displaying technical

Parameters of the thermal devices and a measurement and detection window area for representing technical measured values calculated values of the thermal devices, preferably several independent latter

Window areas, one of which is assigned to one thermal installation only. Several systems are individually represented on the screen in this way, but not confused.

The respective dependent claims are incorporated herein.

Reference is made to the figures (also pictures) for concrete examples of the invention, however, these examples are not to be read so that they contain compelling elements that are in the extent primate claims to include or appear necessary there. This in turn does not mean that the examples would not include disclosures suitable for supplementing the claims.

Although not in every place and every sentence, the term "particular" or "for example" is to be read, the inclined expert reader may understand the following examples of the claimed invention as examples with exemplary elements, values and functions.

Unwritten elements are not to be understood as disclaiming their presence. If only one example of an element, value or function is disclosed, it may nevertheless be modified in a readily apparent manner by one of ordinary skill in the art.

On the figures (also pictures) is referenced for examples of the invention, they represent the following ...

Figure 1 Example of a winding contact of a resistor 1 in a heating zone.

FIG. 2 A schematic circuit diagram of the heating (in the plant 100)

with several heating zones 1 ', 2', ..., 5 '.

Figure 2a circuit diagram of the heater on the high-voltage side

(HV input) of the high-voltage transformer HT 110.

FIG. 3 shows an example of a voltage converter 21 from the group 20 of voltage transformers.

FIG. 4 shows an example of a current sensor 31 from the group 30 of FIG

Current converters.

Figure 5 eight-slot acquisition with modules ml to m7 for seven

Appendices 100.

Figures 6 Electrical circuit diagram of the plant in the example, on 4

Pages divided into Figures 6-1, 6-2 to 6-4.

Figure 6a block diagram of the resistance measurement and system monitoring.

FIGS. 6b, flowchart of a program-technical solution of the

Resistance measurement and equipment monitoring, split on two sheets 6b-l and 6b-2.

Figure 7 Measurement of voltage and current by means of oscilloscope.

FIGS. 8 software tabs as a screen image,

Home 211 for a USER interface, split on two sheets 8-1 and 8-2.

FIG. 9 software register as screen display,

Plant pages 212, 212a ... as USER interface (s).

Figures 10 software tabs as a screen display, history data evaluation 213, divided into two sheets 10-1 and 10-2.

Figures 11 software tabs as screen display, history

Read data drift 236, split on two sheets 11-1 and 11-2. FIG. 12 Software registers as screen display, UI evaluation 214.

Figures 13 early detection of a first winding contact event 310, divided into two sheets 13-1 and 13-2.

FIG. 14 shows the premature detection of a second winding contact event 310 ', divided into two sheets 14-1 and 14-2.

An enlarged illustration of a winding, that is to say a resistor 1 as a heating coil in a wound, planar form, is illustrated in FIG. Here, a winding contact Fi is to be shown, which has arisen in the region of a resulting winding damage F (in a circle) by touching two adjacent Heizdrahtabschnitten (in black and dark).

Before such damage occurs, the invention described herein, and in particular the embodiments described herein, should be able to foresee such damage as resulting damage.

The center of the helix is not shown, it is above to assume about twice the height of the picture. The section is shown at a lower (right) edge region and it is explained on the basis of the resistance 1 in the heating zone 1 'such a coil. The heating wire is consistently a piece, which winds winding or helically around a center outward.

Radially directed webs, visible in FIG. 1, stabilize the position of this dark-colored heating wire. Between two respective radially adjacent

Sections of the heating wire (dark in the picture) is an insulating material (in the picture bright). In the edge area, individual numbered sections of this heating wire can be seen. Sections 1.4, 1.3, 1.2 and 1.1 are adjacent sections of the

Heating wire, so the winding total. The outermost wire or line section 1.1 performs under all webs 1.10 to 1.14. It begins in the picture on the left, under bridge 1.10 leads to the right, and gets to the bridge 1.11, 1.12, then to the

next bars 1.13 and 1.14.

The webs have approximately the same circumferential distance angles, but are in their

Longitudinal extent (in the radial direction) not equally long, but

alternately shorter and longer, as shown in the picture.

At the inner edge of section 1.3, the insulating zone is 1.6. The webs are based on the insulation zones between the heating wire sections (shown brighter). Even further inside is the next isolation zone 1.5, at the section 1.4 of the heating wire adjoining inside. In the right following section between the radial webs 1.12 and 1.13, the previously described line sections 1.4, 1.3, 1.2 and 1.1 continue the heating wire.

It can be seen in this gutter area that the insulation 1.6 significantly widened (Section 1.6 '), so the sections 1.3 and 1.4 of the heating coil continue to move away from each other, then in the following gutter section, which is marked with OCF, in terms of Section 1.4 to move clearly outward, so far that in the circled fault area F a contact Fi of the two

Line sections 1.3 and 1.4 takes place in the gutter section OCF.

This local case of touch, which causes a circumferential coil (approximately 360 °) to be short-circuited, will result in a fault. This fault situation can have the effect that the entire heating coil 1 fails if at one point Fi an excessive heating occurs, which can lead to a line break.

This can be seen in the dashed area F '(on the left edge). It is a

(Coming) further error case, the wire sections 1.1. and 1.2.

Embodiments of the hardware will be described below.

A schematic diagram of the structure is illustrated with FIG.

A voltage at each of the resistors 1 to 5 is measured by means of an optically isolated voltage converter 20 (from FIG. 3) directly at each heating zone 1 'to 5'. A current detection 30 of each zone 1 'to 5' is realized via in each case a contactless Hall current sensor (from FIG. 4) between phase A to E and SCR unit 40 (thyristor block or heater control). FIG. 2 shows a group 20, 30 of transducers, wherein two of the transducers 21, 31 are assigned to a zone 1 '. In each case a current detection 31 and a voltage converter 21 (collectively also called "converter") form the measured values of the resistance 1 of a heating zone 1 '. The same for the zone 2 '(converter 22, 32) and others.

The contactless measurements do not affect the heating zones in the event of a sensor failure. Both sensor types (current sensors 30,

Voltage sensors 20) use a ± 15V DC voltage as a potential-separated supply voltage.

For evaluation of the signals of current and voltage, an 8-slot housing is used for modules ml to m7, wherein in each module an analogue detection area 30a for current and a voltage analogue detection area 20a is provided. The eight-slot package is an exemplary NI-cDAQ 9188 from National Instruments. It accommodates the 7 analog input modules (16 analog inputs per module) and one solid state relay module 60 with eight SSR relays 61 to 68 (see Figure 5).

With this hardware, seven heaters per five zones of different systems can be monitored simultaneously (ie seven heating systems 100 from Figure 2, each with at least five zones).

Through the relays 60, a connection to a respective thermal plant 100 can be made to generate an alarm 90.

The electrical wiring of the hardware becomes visible in accordance with FIG. 6 (example of a (total) system 100, of which seven may be present in the expansion stage proposed here). The unit 100 is distributed on four sheets, which are to be put together as shown in the upper right for Figure 6 on sheet 6-1. Depending on the system state, there are four figures or a figure. Each system has an electrical control box in which the voltage transformers 20 and power supply 80 are implemented at ± 15V (DCV).

To avoid interference, suppression capacitors can be integrated with the current sensors 30, since these are mounted directly in the vicinity of power transformers in the system. In addition, shielded multi-core cables can be used.

Non-flammable lines can be used to pick up the voltages.

The previously summarized overall system 100 should be in the individual

Components are explained in more detail, wherein reference numerals are used.

Previously, the current sensors 30 were summarily mentioned, which in Figure 2 before the

Thyristorblock 40 can be seen. In the example for the five zones 1 ', 2', 3 ', 4' and 5 'of the thermal plant 100, this involves five bidirectional thyristors, which can also be connected as a triac. In general, they had previously been referred to as heater control. Their control corresponds to the usual procedure and will not be explained in detail here. The effect of their control already.

The five zones 1 'to 5' can be seen in the thermal system 100 of Figure 2, they are there marked with five resistors 1 to 5, of which each resistor is located in a zone. The resistors are called as the zones, ie resistor 1 in zone 1 ', resistor 2 in zone 2', resistor 3 in zone 3 ', resistor 4 in zone 4' and resistor 5 in zone 5 '. After these resistors are all connected in series in the example, it is also possible to use an upper resistor (top) and a lower resistance (bottom). In the heater 100 they are arranged accordingly. With regard to Figure 1, each resistor, for example, resistor 1, as a helix (heating coil) is formed.

The voltages at the resistors, ie each voltage at each resistor, is determined via the voltage sensors 20 mentioned. Here, a voltage sensor 21 is provided in the heating zone 1 'at the resistor 1. All other voltage sensors 22, 23, 24 and 25 correspond to the heating zones 2 ', 3', 4 'and 5', and the associated

Resistors 2, 3, 4 and 5.

Each thyristor in the thyristor block 40, or a respective counter-parallel pair of thyristors, for example, 41, controls a resistor, in the example the

Resistor 1 (the heating coil 1) in the heating zone 1 '. Here, a current IA is drawn in, from the (later) to be explained potential-free secondary load voltage A via the current measurement 31, the bidirectionally connected thyristors 41, the associated line to BN then in the heating zone 1 'through the resistor 1 and at the end over the connection line AN flows. This current is an alternating current and it comes from a voltage which will be explained below with reference to FIG. 2a.

This voltage A has a phase and a neutral conductor AN, which are here named "Top". They come from a winding on a common transformer core, of which windings there are five in the example. These windings and their outputs from each phase and neutral, each potential-free, are named A, B, C, D and E. They are connected to the associated phase inputs A, B, C, D and E of the thyristor block 40

connected (in each case the phase) and the respective neutral conductor AN, BN, CN USW. to the respective neutral conductor AN, BN, CN, USW. in FIG. 2

The heating transformer 110 (HT 110) has a primary high input voltage, which may be between 300V and 600V, preferably at 380V nominal AC voltage. The associated input circuit of three phases U, V and W is connected to three windings Wl, W2 and W3 in a delta connection, which are wound on a common core. This transformer core has five potential-free secondary windings on the secondary side which match the number of heating zones in the thermal system 100.

Each secondary winding supplies a heating zone and, after the heating zones are connected in series with their resistors, can also be connected to each winding via the

Thyristor block 40 and the bidirectional thyristors present therein an individual heating of the respective zone. The switches shown in FIG. 2a turn on the heating zones and their supply voltage, they are here summarily called "Sch", and can be found in the figure quartet in the lower left corner of FIGS. The voltages shown there correspond to the voltages A to E (from top to bottom). On the right, the thyristors of the thyristor block 40 can be seen.

The current levels of the supply of the heating transformer 110 are adapted to the current compatibility of the resistors 1 to 5. They are between 30A and 55A. Also the

Voltages of the secondary windings of the heating transformer 110 are matched and are between 75V to 165V. The resistances in the heating zones have values between 1.8Ω to 4.5Ω in the middle temperature range and between 0.25Ω and 0.9Ω in the high temperature range.

The currents can be up to 150A. The resistors can have resistance values below 1Ω.

It should be clarified again for coordination of the following explanation that the heating zone 1 'the resistance 1 (as physical or representational

Resistance). It is designed as a helix, as can be seen in FIG. Its operational value (here called resistance value) is Ri.

The heating zone 1 'is in this example, the upper heating zone "Top" and has the

Voltage measurement on the physical resistance 1 with the sensor 21. In the example shown flows in this resistor 1 with the resistance Ri of the current IA. The resistance value, which is determined via the voltage measurement 21 and the current measurement 31, is calculated Ri, wherein a plurality of resistance values are "measured" and calculated in a continuous measurement, since the ohmic value of the resistor 1 changes and consequently several measured resistance values are expressed as i R i (i), R i (i + 1), where i = 1 to n. n is a multiple of the sampling time (more precisely ... the sampling interval).

The same applies to the heating zone 2 'with the physical resistance 2 and its ohmic resistance R ₂ , continuously over time as R ₂ (i), where i = 1 to n. Similarly, the explanation is on the other three resistors 3, 4 and 5 from Figure 2 to transfer, each with the matching indices 3, 4 and 5 respectively.

Physically, the voltage transformers 20 are shown in Figure 3, as Aufsteckgehäuse (for a Aufschnapp-rail not shown). They have input connections and

Output connections that are potential-free. For the current sensors 30, FIG. 4 shows an example of a current sensor 31, which measures the current without potential, which current is supplied from the thyristor block 40 to the bipolar thyristor 41, for example.

Several current sensors are used, in the example it is five, corresponding to the five zones for a thermal plant 100. If several plants are used, then there are correspondingly more current sensors. In the example further ahead, there are seven plants 100.

After the number of current sensors 30 and the voltage sensors 20 can become very extensive, input modules are provided for evaluating the measured current and voltage signals, in the example those of FIG. 5 as 8-slot housing 30a (for current) and 20a (for voltage) , shown in Figure 6. Here are the seven plants mentioned in the example in each case five heating zones.

After 16 analog inputs per module are available, more heating zones per module can be included than have been interconnected in the example. Here five inputs are used for current signals and five inputs for voltage signals, in the example of FIG

functional areas 30a (for current) and 20a (for voltage). So can one

thermal plant 100 are assigned to a module.

From Figure 6a is a schematic block diagram (as a circuit) can be seen, as it can be realized for a zone and a resistor disposed therein.

If multiple zones are monitored, this scheme can also be transferred to multiple zones, or multidimensionally considered each

Function block 50, 52, ... is present as often as there are resistances in a thermal system to measure, either in a thermal plant 100 or across plants, when multiple systems, such as seven systems, each with five heating zones are monitored ,

Here, for zone 1 'in the thermal plant 100, the monitoring will be explained with reference to FIG. 6a.

On the basis of the voltage measurement 21 and on the basis of the current measurement 31, a temporally respectively assigned measured value is detected which is present at the instant i (i is a

continuous variable of the digital acquisition and can also be called "time stamp"). AC voltage is preferably RMS values, not instantaneous values. Both measured signals, the voltage and the current at the instant i, are supplied to the arithmetic unit 50 in order to calculate therefrom a resistance value Ri (i) belonging to a time value as time stamp i. This measurement and this calculation takes place permanently during the operation of the system 100 and the resistance values Ri (i) continuously determined during this process are stored in the intermediate memory 52. This buffer 52 outputs the current value and a previous value, in particular the immediately preceding value, and thus supplies a comparator or a difference former 54.

The two resistance values Ri (i) and Ri (i-l) are subtracted or compared in their value and the comparison result, in particular the difference ARi (i), of these two values is output. In general, it is the resistance value differences ARj (i), at j = 1 to m, where in the example m = 5 stands for five heating zones.

The output of the difference ARj (i) is provided to a threshold switch 56 which responds when a predetermined difference value AR is exceeded (also referred to as upper and lower limit windows) and the threshold switch 56 provides a signal to one of the SSR relays 60 from which triggers an alarm signal 90. The multiple SSR relays 60 can be seen in FIG. 6, one of them, the SSR 61 is here at

Heating coil 1 of the thermal system 100 active.

The injected deviation AR defines the responsiveness and indicates whether an error case F caused by contact of two adjacent heater wire sections in the area Fi is in progress or already in progress. The alarm 90 on this detected error case is thus generated, well before a failure of a whole heating coil or heating coil 1, which was used here as an example in Figure 6a and in Figure 1.

With the measurement and calculation of a continuous resistance value, the contact within a winding (better: helix) can be detected early, before a final winding break or finally to a winding

Winding break is coming.

Assigned measures are possible, for. B. the system is not turned on before a repair is done. The system can also be stopped before a failure and the entire heater from all existing, in particular five zones are renewed. Another possibility is to disable the starting of the thermal system, if in standby mode, the monitoring took place and the next actual error case (the oncoming winding break) is detected (as the alarm generating "error" of the monitoring).

Software realization (program realization) is explained below. A measurement data acquisition and monitoring can also be done by program technology, which illustrate Figure 6b. The programmed technical flow chart is 190. It works with real measured values from an operating procedure (like a process computer to be assigned to a technical area that does not process abstract data, and therefore is not a "data processing system as such").

The acquisition of the current and voltage signals (ie the measured values) is realized simultaneously with 5,000 values / sec per analog input across all plants 100,

programmed function 110. A measuring interval is 4 sec, which corresponds to a total of 20,000 values per analog input. The complete measurement data packet can be sent over a network, e.g. are transmitted via Ethernet (not shown) to a controller programmed with (technical) software, which implements the function of the FIG. 6a shown as a circuit or is recorded in the software flowchart 190.

Filter and evaluation ...

The temperature control of each individual heating zone takes over the

Thyristor control 40 of each system 100. This switches depending on

Power setting (0% to 100%) several voltage periods for a certain number of milliseconds by (example see Figure 7).

To achieve a clean RMS formation 130 (Root Mean Square, RMS, RMS) for both current and voltage, the zero crossings are replaced by one

Filter filtered out (see Figure 12 with the steps 241a in the

Zero crossings of U and I) and only the negative half-waves are used for the evaluation, function 125. This is because the heating zones are in the positive

Half-wave depending on the performance can influence each other and so one

could lead to unclear signal.

In function 122, it may be checked whether there are a minimum number of periods, e.g. five periods. If not, then this data is ignored, branch 122a. This is particularly useful because when cooling the heater, the power can be less than 3% and thus could have a not sufficient number of raw data (first threshold) for optimal RMS formation.

After the RMS formation 130, the resistance value of each heating element is determined according to Ohm's law with the function 140 and stored with a time stamp in a suitable file, in particular a text file.

Subsequently, the power curve is controlled with the function 142 from the determined resistance value with the square values of voltage and current, to additionally rule out that the signal is disturbed. If the difference in the comparison 144 is greater than a default (a second threshold), the measured data (the measurement interval) of the affected heater zone is also ignored, branch 144a, function 145.

Alarm generation ...

After the process data (no "data as such") has been determined, these are evaluated by an alarm routine. In this case, the current resistance value is compared with the last value in the function 150. In the case of a deviation outside a range (for example ± 2.5% as a window AR in percent), as the third threshold value, after the query 151 via the alarm generation 90a branch 151a, an SSR relay of the associated system with the function 161 occurs.

Other alarm generations are possible, as well as equipotential, not necessarily only via a potential-free SSR relay.

In addition, the raw data are stored in order to be able to carry out an analysis of the signal profiles afterwards. It can also be evaluated whether the thyristor pair for the positive or negative half-wave is defective. This is determined in the process and displayed in text form.

So far not mentioned in the flow chart was the function 120, with which a scaling (or a normalization) of the measured raw data takes place. This allows the

subsequent calculation with reasonably large values work, if necessary even without having to consider the different current levels of different zones. By normalizing, currents between 30A and 60A can be tailored to be the same for the following calculation and error detection

Have maximum values or the same RMS values. Error detection with function 150 requires a deviation in percent.

Thus, the resistance difference ARabsoiut can be applied to the previous or current measurement value Rj (i) or j (il) is related to be expressed as a percentage as AR _re iativ, thus for the i-th measurement of zone j gives {Rj (i) - Rj (i-1)} / Rj (i). The result AR _re iativ in function 150th

In the case of a deviation outside the threshold values of, for example, ± 2.5% as window ARreiative, the path 151a is taken in the process, otherwise branch 151b, which leads back to the function 110, as well as the branching return paths 122a and 145a as consequences of unachieved thresholds. The various inserted thresholds should be selected again. They serve to verify a result that is not as simple as

Alarm error case 151, 151a and the alarm generation 161 is assumed, but can go through several plausibility checks, whether it is really a real error (in the sense of an expected real error), not just an unfortunate reading or a disturbance.

(a) The number of periods in query 122 ensures that sufficient

Measurement results are available. After the thyristor control 40 operates on a pulse packet control assumed here in the example, ie it always transmits an entire sine wave and blocks one or more sine waves, at low powers, e.g. less than 3%, many solid waves are blanked out by 360 ° and only one or a few full waves are switched through

for example, a full-wave through and five full waves. For example, at higher currents, eight fullwaves are turned on and two fullwaves are matched. The latter case would support query 122 and say that there are sufficient measurements for RMS calculation. This is a first control step here also abstractly called "first threshold".

(b) A second threshold is in the control of active power over current and voltage. If the resistance has been calculated in function 140, it can also be used to calculate the active power delivered to the system or to the zone, both by voltage and by current. Both calculated process values of the active power are available and help to detect faults. This should be referred to as the second threshold, which is not a true threshold, but only a threshold or switching threshold to prevent any further transmission of disturbances or false alarms.

(c) A third threshold is in the query 151. Here, the difference to be detected between the measured and the previously measured resistance value (or a previously measured resistance value) becomes a minimum

Deviation that is to be met to trigger an error via the alarm routine 151, 151 a and 161 as a real alarm 90

One, two or all of the three thresholds help ensure safety and security

Reliability of error detection to improve and failed alarms

largely to avoid almost completely. It may be remembered that switching off the system involves the risk of losing the wafers contained therein. Precisely for this reason, an early detection is possible be achieved, but at the same time a reliable detection. It is known from control engineering that a system, the more sensitive it reacts, the more susceptible it is in operation. Fulfilling these two criteria together realizes the multiple provision of so-called thresholds above, which must be overcome if an alarm 161 actually has to be triggered.

Suitable values for the minimum number of periods are the number of at least five consecutive voltage periods. A suitable number for the control of the active power (calculated over the current) and for the comparison of the active power

(calculated from the voltage), each with the previously calculated resistance, is in a range of less than 5%, preferably less than 2%. A suitable value for the window or control window, which must leave the resistance difference for the case of error, is ± 2.5%. It should be noted that the threshold (ie the window) must not be too large, so as not to miss any error case or hide such, but on the other hand not too small to choose is too often to accept a fault, of which only a few actual error cases are, as shown in Figure 1 in the area F (or take place in the area F ').

Functional software interface (GUI, control panel)

The graphical user interface (GUI) may be composed of multiple tabs 210. On the start page 211 (see also Figure 8) the following properties can be set ...

For configuration 221 of the measuring system ...

• Sample rate, field 221a

• Number of values, field 22 lb

• Time interval, field 221c, for displaying and saving the graph (in hours, are set 24h)

• Alarm limits, field 222, plus / minus in percent, as the third mentioned

Threshold, in the form of eight windows

• Activate / deactivate data acquisition, field 223, per system 10

• Functionally remove individual heating zones (heating zones) from the alarm evaluation, field 224.

The on the start page with the tab 211 defined information 200 a

Overall plant with in the example eight thermal plants PHOT-0400 to PHOT-1400 is to be pointed out more concretely from the abstract circumscription above here. The measuring system is configured at 221 (in the lower rider). The limits (the third threshold) are configured or determined in sub-tab 222 by +/- limits so that the limits of ± 2.5% set here for PHOT-0400, for example, indicate a range within which no warning or no Alarm is output.

Without a separate tab, directly on the user interface, field 223 with graphically activatable keys or areas is turned on, in which the eight systems mentioned are activated for data acquisition. In the lower part of the graph, the evaluation is in sub-tab 224, where each plant from PHOT-0400 to PHOT-1400 is mapped in area 224a with all its zones, here five zones each (Bottom, CTR1, CTR2, CTR3 and Top).

This graphical tab, accessed via tab 211, thus has the characteristics of the configuration of the measuring system, the configuration of the limits, the alarm evaluation and additionally a field which activates the data acquisition at each of the several thermal systems.

In a special way, all useful data for the configuration of the system are kept and optically visualized. Important criteria are the attitude of the

Window sizes for the resistance differences in the individual systems, within which no warning is given. It is also possible to remove entire zones or even entire systems from the warning by activating or deactivating them in the field with the tab 224. Such an evaluation manages a large number of

Process data to be viewed, recognizable by the sampling rate 221a, the number of

Samples 221b and the predetermined time interval for which the measured values are to be stored as graphs. Nevertheless, a functionally easy-to-grasp overview is achieved, which allows a user to monitor, preselect, and activate as well as disable the facility (s) and their failures.

The following tabs 212, 212a, 212b, ... (see FIG. 9) are assigned to the systems PHOT-0400, PHOT-0500, etc. On these the currently determined data are displayed and the resistance values are displayed graphically. In the text field Alarm message 91 the alarm case 90 is written out.

In the register History 213 (see Figure 10), the resistance values of the individual systems from the past can be read.

The change in resistance (see also FIG. 11) can also be viewed over time since the mean value is formed and stored for each time interval. Under a UI evaluation (see Figure 12), the raw data of voltage and current can be viewed in case of error.

The functional recognition in the following tabs 212, 212a, 212b, etc. will be illustrated here with reference to FIG. Each attachment is shown here in more detail and has a chart 232 showing the course of resistance over time. Only the tab 212 will be explained here, in the same way the tabs 212a, 212b are formed and functionally realized. The user leaves the home page of the

Reiter 211, by clicking the tab 212, the system PHOT-400 is visualized.

Three larger fields are shown, the actual process data (measured data and calculated values) in field 230, alarm messages 90 in field 91 (currently no alarms are displayed, the system is running error-free), and a visual supportive chart of at least four resistance curves 232 over time, with two resistors superimposed over time, between 4.25 ohms and 4.5 ohms.

In the actual measurement window 230, all the physical variables present there for this plant PHOT-400 are visible for the five zones provided there (bottom, CTR1, CTR2, CTR3, and top), the calculated resistance, the detected voltage, the measured current, the calculated one active power. A visual display, e.g. An LED symbol can symbolize whether an alarm is active and the alarms that have already occurred can also be displayed in a smaller window for each of the five zones.

The individualization of each thermal system on the picture allows the user to be very concrete in every detail of the process

to comprehend, as well as very abstractly superior measurements and others

Survey results of the process (s), visually evaluate displayed results, and do so very quickly. If you take the example of

Reiter's 212, multiplied by the other seven facilities shown here

PHOT-0500 to PHOT-1400, it is easy to see which data sets are to be processed in such a way that they can be easily captured and evaluated by the user. Independent of this, of course, is the automatic evaluation of one

Alarm event, but depends on the settings of the parameters on the start page 211 of the GUI.

The configurations are concentrated on the homepage 211. The plant results on the tabs 212, 212a, ... with associated alarm message 90 for each Plant and within the plant for all existing zones, in the example five zones per plant 10 in the entire plant 100.

Optionally, an error message from the thyristor unit 40 (as an example of circuit breakers) may be included among the alarms, not just the detection of a resistive coil that is going to be damaged.

The tabs 213 (FIGS. 10 and 11) as well as the UI evaluation 214 (in FIG. 12) are used for checking and retrospectively considering an error development. Often it is useful to reproduce and look at the exact course of the error later, it is often helpful to analyze why an error was detected or how it was detected and last but not least it makes sense to analyze an accidentally reported alarm also why this was recognized, although he should not have been recognized. All these tasks are served by the records of the past (History, tab 213) and the recordings of the measurements of the drift of the resistance, how it behaves in the long term. For this purpose, the mean value per day is entered, for example, according to FIG. 11, wherein the illustrated scaling of the x-axis between two vertical sections respectively in FIGS. 9, 10 and 11 becomes larger and larger. If in FIG. 9 a scaling of the x-axis is also subdivided into 2min (for a respective system in tabs 212, 212a, 212b), then the history display in tab 213 is already increased to 2h per scale unit and the drift over an even longer one Time scales with 2 months.

The measurement data is being condensed more and more, so that they also allow long-term statements and assessments, as well as short-term determination in the minute grid.

The paged-out data can be read in via field 235 (a text file is provided to make this data available). Also, drift data can be read in via field 236, as illustrated in FIG. 11, in each case system-related, function field 237. Reading the drift data over a longer period of more than one day (the history data of FIG 24 hours from day) can be reached over the two-month grid of FIG. 11 and the chart drift data 234 '.

All fields described here are touch-sensitive or click-sensitive to trigger an associated action.

The monitoring and control also serves a record of the voltage curve over the activatable field 240 comparable to the resistance value. The voltage curve 241 appearing on the x-axis is based on the number of pulses

Scaled data samples. It is noticeable that the zero crossings are hidden, which was previously explained with reference to FIG. 6b with the function 121. One of these places is picked out with 241a. It will be appreciated that with four or five periods necessary to calculate a value of an RMS value of the voltage and a corresponding value for the current, substantially more data samples for the voltage and current for the UI evaluation will be stored, permanently stored, than that for the history 213 of the resistance value of all plants is the case.

FIGS. 13 and 14 show, as mentioned above, that premature detection of a winding contact was possible, designated as the first event in FIGS. 13 and 14 as the second event.

The proof is here guided on the basis of the history and the associated tab 213, with which it is subsequently possible to retrospectively and retrospectively analyze, with the aid of the previously described functional sequence from FIG. 10, what has happened. A time grid of 2 h is assumed and depicted, as is also shown in FIG. 10, wherein the plant PHOT-0900 is displayed via the functional selection field 237 for the alarm case of FIG.

For the second event in FIG. 14, the PHOT-1000 system is functional

Selection box 237 is selected and in both representations a scaling of 2h per scale grid is used.

In a detail enlargement, in FIG. 13, the time range 300 is increased out than 300 'in order to illustrate the beginning of the error case (a resistance change of 7% occurs) at the time 310. The breaking of the resistance is shown at 320 after 5h as a real error case. The alarm generation when observed

However, the (actual) error case is earlier in time and is already classified by the system as an error case, before the real error causes the thermal system to fail (and makes the batch of the load unusable).

In a comparable detail magnification in FIG. 14, the temporal

Area 300 out increased as 300 "to the beginning of the second event

(Error 2) (also here a resistance change of 7% occurred at time 310 '). Breakage of the resistance is shown at 320 'after 3.5h as a second real fault case. The alarm generation was already done 3,5 hours ago. Proof of early detection ...

Since the installation of the heater monitoring at the applicant's internal systems, two events of the early detection of a winding contact (first event and second event) have been detected (shown in FIGS. 13 and 14).

In both cases there was a resistance change of about 7% and about 3.5h or 5h later there was a winding break (a break of the heating coil in the thermal plant).

The production lots were saved by the alarm message (s) at the plants.

Claims

Claims .

A method for or monitoring a thermal device (100) for receiving and tempering wafer lots or batches of wafers, wherein a permanently applied measurement of a resistance value

(Ri) of a resistor (1) in at least one heating zone (16) of

a plurality of heating zones (, 2 ', 3', 4 ', 5') of the thermal

Device (100) takes place;

each currently measured value (Ri (i)) of the resistor (1) in

the associated heating zone () with a previously measured

Value (Ri (i-l)) of the same resistor (1) is compared;

already at a deviation detected by the comparison (310,

ARi) of the two resistance values (Ri (i); Ri (i-l)) from the same

Heating zone () A warning or alarm (90) for the

Thermal device (100) is generated, the time before one

Failure of a whole heating zone () of the thermal device

(100) is located.

2. The method of claim 1, wherein the permanent applied measurement of

Resistance is obtained from a plurality of measurements of voltage (21) and current (31) at the resistor (1) and respective calculation of the value (Ri) of the resistor (1).

3. The method of claim 2, wherein the permanent applied measurement of

Resistance value (Ri) a time course of the value (Ri (i)) of

Resistance (1) yields, in particular, the time course over the i-th sample results.

The method of at least claim 1 wherein the generated warning or alarm (90) for the thermal device results in replacement of the resistor (1) in the heater zone (12).

The method of at least claim 1, wherein the continuous applied measurement of the resistance value (Ri) or resistance (1) also extends to a time range prior to the actual operation of the thermal device (100).

6. The method according to claim 1, wherein the deviation (ARi) of the two time-spaced resistance values detected by the comparison in the case of an electrical contact (Fi) of juxtaposed points (1.3, 1-4) of the heating coil as resistor (1) before a the current interrupting break (320) of the heating coil as a resistor (1) are.

A method according to at least claim 1, wherein the deviation (ARi) of the two time-spaced resistance values detected by the comparison is less than 10% of the resistance value (Ri) of the healthy, undamaged heating coil (1).

The method according to at least claim 7, wherein the deviation of the two time-spaced resistance values detected by the comparison is less than 7%, in particular less than 5% of the value of the healthy undamaged one

Heating coil (1) amounts.

9. The method according to at least claim 1 or one of claims 2 to 8, wherein a breakage of a heating coil (1) more than one hour after detection of the detected by the comparison deviation (ARi) of the two temporally

spaced and measured resistance values (Ri (i), Ri (i-1)).

10. The method of claim 1 or claim 9, wherein the detected deviation (ARi) well before a failure of the heating zone (16) with associated heating

Resistance as a heating coil (1) is located.

11. The method according to any one of the preceding claims, wherein in the plurality of heating zones or heating zones (, 2 ', 3', 4 ', 5'), the respective resistance is permanently applied measured and compared.

12. The method according to any one of the preceding claims, wherein in a plurality of heating zones or heating zones (, 2 ', 3', 4 ', 5') of several systems (100) of the respective resistance permanently applied measured and compared.

13. The method according to any one of the preceding claims, wherein the permanently applied

Measurement works even when the thermal device (100) or its heating zones (, 2 ', ...) or one of their heating zones cools or in the

Cooling operation is or are.

14. The method according to any one of the preceding claims, wherein a plurality of thresholds are provided (122,142,151), which must be overcome in the course of the measurement in order to automatically conclude from the measurements (151a) to trigger an alarm (90,61,161).

15. The method of claim 14, wherein

(a) a minimum number of periods of resistance (1)

feeding voltage from the associated power control (40), in particular thyristor control, one after the other

must be switched through;

and or

(b) Active power from the calculated resistance (149) as well

are calculated and compared, respectively, from the measured voltage and from the measured current;

and or

(c) the detected and calculated resistance difference (ARi) a

Control window is exposed or suspended, and the

Resistance difference must leave the control window.

16. The method according to claim 15, wherein at least four periods are to be switched through, and / or the calculated active powers may deviate by less than 2% in comparison with each other and / or at least 2.5% of the calculated one

Resistance difference (ARi) must have been detected.

17. The method according to any one of the preceding claims, wherein filtered out for a clean RMS formation for current and voltage at the one or more resistors, the zero crossings and only a half-wave, in particular the negative half-waves are used for the evaluation.

18. Screen for monitoring multiple thermal

Means (100) or for carrying out the method according to any one of the preceding claims, with

(i) a configuration window area (211) for displaying

technical parameters of thermal equipment (100) in the

Form of a first field (321) with segments (221a, 221b) for

Configuration of sample rate and number of samples, a second field (222) for specifying window sizes for calculated resistance values and a third field (224, 224a) for

Activation or deactivation of heating zones (, 2 ', ...) in the

thermal plants (100), as well as a fourth field (223) for

Switching on or off of entire thermal systems;

(ii) a measurement and detection window area (212) for display

of technical measured values of one of the thermal installations (100) in

Form of at least three visibly arranged further fields (230, 232, 91), one for actual or calculated measured values

(23a), in particular the calculated resistance value of each

Heating zone of this thermal plant (100), a field (91) for

Alarm messages (90) and a field representing a time history of calculated resistance values (Ri (i)).

The screen display of claim 18, wherein a plurality of sensing and sensing windows (212a, 212b) are provided and each of a thermal

Attachment (100) is assigned.

20. A thermal device with a monitoring device for carrying out the method according to one of the preceding method claims, for monitoring thermally treated wafer lots or batches of wafers, in particular with a screen display according to claim 18 or 19.

21. A thermal device according to claim 20, wherein a computing means and a comparator (54) is provided, wherein

in the calculation device (140) in each case a currently measured

Value (Ri (i)) of the resistance (1) of the associated heating zone ()

with a previously measured value (Ri (i-1)) of the same resistor

(1) is comparable. A thermal device according to claim 21, wherein a warning or an alarm (90) for the thermal device (100) can already be initiated or generated when the deviation (310, ARi) of the two resistance values from the same heating zone (10) is detected by the comparator is located before a failure of one or the entire heating zone (1) in the thermal device (100).

A thermal device according to claim 22, wherein the comparator (144, 54) is subtractor.