DE102018216969A1 - Plasma treatment device and method for outputting pulses of electrical power to at least one process chamber - Google Patents

Abstract

A plasma treatment device and a method for outputting pulses of electrical power to at least one process chamber are described. The plasma treatment device has a plasma generator for outputting pulses of electrical power to at least one process chamber, the plasma generator is configured to generate and output the pulses over a process time in accordance with a predetermined pulse sequence. The plasma generator has an Are unit which is suitable for recognizing a rollover or an upcoming rollover, also called an arc event, and in response to this, aborting, changing and / or interrupting a pulse which is or is to be output to the process chamber to drop out what is called an Are intervention. Furthermore, at least one control unit is provided which is configured to carry out a method, which comprises: determining or receiving a process time and pulse sequence for the process chamber in / on a control unit, controlling a plasma generator in order to output the pulse sequence over the determined process time recognizing an arc event that indicates a rollover or an upcoming rollover, in response to the detection of an arc event, performing an intervention of canceling, changing and / or dropping a pulse that is output to the process chamber or outputted, obtaining data about Are interventions and determining on the basis of the data a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the Arc interventions, and actuating the plasma generator in order to follow the specific process time over the daue r to output the corresponding pulse sequence according to the determined process time extension

Description

The present invention relates to a plasma treatment device and a method for outputting pulses of electrical power to at least one process chamber for the plasma-assisted treatment of substrates.

A wide variety of fields of application are known in the art, in which electrical power is usually provided at a frequency of at least 40 kHz in order to excite a plasma from a gas and to maintain it for certain processes. An example of this is plasma-assisted gas phase deposition in semiconductor technology or the photovoltaic industry.

Here, for example, wafers are loaded into so-called wafer boats, some of which consist of electrically conductive plates and placed in corresponding process chambers. Electrical power at a frequency of at least 40 kHz is then applied to the wafer boats in order to generate a plasma from a suitable process gas between the plates and between wafers received on the plates. An example of such a plasma treatment device is shown in US Pat DE 10 2015 004 419 A1 shown to the applicant.

Such plasma treatment devices generally consist of a single process chamber to which a single plasma generator is assigned. With the adjacent arrangement of several process chambers, the sharing of gas cabinets and other peripheral devices was sometimes considered, but so far each process chamber had a single plasma generator. Such a plasma generator generally has a controllable power supply unit with an output which is suitable for outputting a direct current with a predetermined voltage and / or strength at its output, a converter which is suitable for converting an alternating current with a predetermined frequency from a direct current at the input Form at least 40KHz as an output signal and apply the output signal to the connected process chamber

During the processes, the electrical power is usually made available periodically as a pulse by the respective plasma generator, a duty cycle (quotient of pulse duration and period duration) of less than 0.1 being generally set here over long time periods. Such a pulsed operation of a plasma in the process chamber has proven to be particularly advantageous. Typically, 90% of the available continuous power of a plasma generator therefore remains unused over long stretches of the processes. There are also processes with much smaller duty cycles, but also processes or process sections with higher duty cycles. The power supply unit and the converter are usually controlled via a controller which, depending on a process recipe (the required power), determines a corresponding pulse sequence for the process chamber over a process duration and generates corresponding control signals. The process duration and the pulse sequence are usually defined in advance and are no longer changed.

Plasma generators usually also have an arc suppression unit (also known as an arc suppression unit), which is suitable for obtaining current process data about processes in the process chamber and current data from the power supply unit and / or the switch, and evaluating them in real time in order to determine a rollover or an upcoming rollover also known as Arc). Arcs can lead to locally burned, melted, or unevenly coated wafers. Furthermore, the wafer carrier can also be damaged, which can lead to production downtime or high service costs. Therefore, arcs should be avoided if possible.

The arc suppression unit can be connected to the power supply unit and / or the switch, for example, in order to control them in response to the detection of a rollover or an upcoming rollover, in order to avoid or quickly suppress rollovers in the process chamber. This happens, for example, by the fact that electrical power pulses are not built up at all or a corresponding pulse is diverted to an absorber, for example. This can also be done while a pulse has already been partially directed into the process chamber.

Plasma generator manufacturers usually specify suitable settings for arc suppression management (also called are management), which can also be changed by the system operator if necessary. In addition, modern treatment plants can use arc suppression values to decide on a process termination if, for example, too many arc events have occurred within a period of time, or if power, current and / or voltage are out of tolerance.

Plasma generator manufacturers in particular offer arc management or arc suppression software solutions that intervene in the process by reducing current / voltage and forcing process breaks. A reduction of current / voltage and process breaks, however, if they are planned in advance, can increase the process times accordingly and thus affect the throughput of a process plant. If, however, in this way in the ongoing process intervention, this leads to a low average power over the process time. This can result in the deposited layer thicknesses being less than desired, since, for example in PECVD processes, the deposition thickness is proportional to the power input. Lower layer thicknesses can lead to problems in later machining processes or even to a complete failure of the deposited layer.

Plant operators also define process termination criteria such as voltage, current, power or number of arcs. This allows you to cancel the process before the workpiece carrier is damaged. To do this, the plant operator must select the termination criteria so that the Arc Management System has little chance of reacting. A process termination followed by a search for the cause of the arc is time-consuming, reduces the system throughput and leads to material loss.

The plant operator would therefore like to avoid any process interruptions, no damage to the wafer and / or workpiece carrier caused by Arcs, and also no layers that were deposited too thinly.

The present invention is therefore based on the object of making the provision of electrical power more efficient in order to avoid or reduce at least one of the problems mentioned above as far as possible. According to the invention, this object is achieved by a plasma treatment device according to claim 1 and a method for outputting pulses of electrical power to at least one process chamber according to claim 9. Further refinements of the invention result, inter alia, from the subclaims.

The plasma treatment device has a plasma generator that is configured to output pulses of electrical power to at least one process chamber, the plasma generator is configured to generate and output the pulses over a process time according to a predetermined pulse sequence, and the plasma generator is an Are unit which is suitable for recognizing a rollover or an upcoming rollover, also called an arc event, and in response responding to a pulse which is or is to be output to the process chamber, cancels, changes and / or cancels out what are -Intervention is called. In particular, the plasma treatment device also has at least one control unit that is configured to receive and evaluate process data about processes in the at least one process chamber and, based on the process data, at least one process time and a pulse sequence to be made available by the plasma generator over the process time to determine, or to receive a specific process time and pulse sequence, the pulse sequence configured to bring a predetermined power into the process chamber via the process time, to control the plasma generator, to output the pulse sequence over the process time. The at least one control unit is also configured to receive data about Are interventions and to use the data to determine a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the Arc interventions. Such a plasma treatment device offers the possibility of compensating for power losses that occur due to arc events at least in steep increments, which improves the homogeneity of processes and enables more aggressive arc management.

The plasma treatment device preferably has a unit that is configured to determine the number of interventions and transmit it to the at least one control unit. The simply ascertainable number of interventions alone can provide a basis for determining an approximate loss of performance for determining a process time extension with a corresponding pulse sequence. In particular, the unit can be configured to recognize at least two different types of Are interventions, to determine the number of each type of Are intervention and to transmit the number to the at least one control unit. By differentiating the Arc interventions, a better assessment of the loss of performance can be made. The unit can be part of the arc unit that performs the Are operations. In one embodiment, the arc unit is configured to recognize at least two different types of arc events and to select different predetermined arc interventions corresponding to the arc event.

In particular, the arc unit can be configured to recognize at least two of the following arc events: an Imax event which indicates an overcurrent, ie a current above a threshold, and thus the occurrence of an arc; a U * I event which, before reaching an overcurrent, indicates an excessive current increase at a given voltage (Uxl) in such a way that an overcurrent would be expected if further power was supplied; a micro-arc, which is indicated by a current peak at a given voltage. These events have different influences on the process, whereby an Imax event has the greatest influence and should be avoided if possible, since it can lead to damage to the sebum rate or to a substrate carrier. Appropriate interventions in micro-arc events and U * I events, which are often harbingers of an immanent Imax event, can prevent these if necessary. The arc unit can be configured in particular when the Imax event is detected to abort the current pulse completely and then slowly increase the power, so that the following pulse may not be fully output; to interrupt the current pulse when a U * I event is detected and, if possible, to restart within the planned pulse time with an increasing power ramp; and to interrupt the current pulse when a micro-arc is detected and continue to output it after a short waiting time.

In a further embodiment, the control unit is configured to control the plasma generator when a certain number of arc events are reached within the process time or a process section, to reduce the power output per pulse of the remaining pulse train, and to reduce the power correspondingly when determining the process time extension with a corresponding pulse train to consider. By reducing the power of the remaining pulses, the probability of arcs during the running process can be reduced, but a corresponding power loss can be at least partially compensated for in order to obtain a desired process result.

When determining the process time extension with a corresponding pulse sequence, the average power of the pulses can be chosen to be lower than the average power of the pulses during the previous process time in order to reduce the probability of arcs during the process time extension.

The method for outputting pulses of electrical power to at least one process chamber has the following: determining or receiving a process time and pulse train for the process chamber in / on a control unit, controlling a plasma generator in order to output the pulse train over the specific process time, recognizing an arc Receive events indicating a rollover or an upcoming rollover in response to the detection of an arc event, performing an Are intervention that includes canceling, changing, and / or dropping a pulse that is being delivered to the process chamber or is to be delivered of data via arc interventions and determine on the basis of the data a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the arc interventions, and actuation of the plasma generator to follow the determined process time over the duration of the determined process time output the corresponding pulse train. The advantages already mentioned above can be achieved by the method.

The data on Are interventions preferably have the number of Are interventions, which is easy to determine. It is preferably possible to carry out different types of Arc interventions and the data on Are interventions then have at least the types of Arc interventions and the respective number of Are interventions.

In one embodiment, recognizing arc events comprises recognizing at least two different types of arc events, performing the arc intervention selecting a predetermined arc intervention from a plurality of predetermined are interventions corresponding to the arc event and performing the selected arc intervention. In this way, specific events can be addressed more specifically. In particular, the detection of arc events has the detection of at least two of the following arc events: an Imax event that has an overcurrent, i.e. a current above a threshold value, and thus indicating the occurrence of an arc, a U * I event which, before reaching an overcurrent, indicates an excessive current rise at a given voltage such that an overcurrent would be expected if further power was supplied, and / or a micro-arc, which is indicated by a current peak at a given voltage. Accordingly, performing the arc intervention can have the following effects: when a Imax event is detected, the current pulse is aborted completely and the output is then slowly increased, so that the subsequent pulse may not be fully output when a U * I event is detected Interrupt pulse and restart as far as possible within the planned pulse time with increasing power ramp, and / or interrupt the current pulse when a micro-arc is detected and continue to output normally after a short waiting time. The advantages of the different Are interventions have already been explained above.

In one embodiment, when a certain number of arc events are reached within the process time and / or a process section, the plasma generator is controlled to reduce the power output per pulse of the remaining pulse sequence, with a corresponding power reduction being taken into account when determining the process time extension with a corresponding pulse sequence. The power reduction for the remaining pulses is at least 10%, preferably at least 20%.

When determining the process time extension with the appropriate pulse sequence, the average power per pulse can be chosen lower than that average power per pulse during the process time to reduce the probability of arcs in the process time extension. In particular, the average power per pulse during the process time extension can be selected to be at least 10%, preferably at least 20% lower than the average power per pulse during the process time.

• 1 eine schematische Darstellung einer beispielhaften Ausführungsform einer Plasma-Behandlungsvorrichtung;
• 2 eine schematische Darstellungen einer Soll-Pulsfolge, wie sie über einen Zeitraum von einem Plasmagenerator abgegeben werden soll;
• 3 eine schematische Darstellungen einer beispielhaften Pulsfolge entsprechend 1, wie sie tatsächlich vom Plasmagenerator abgegeben wurde;
• 4 eine schematische Darstellungen eines Einzelpulses, bei dem ein erster Fehler detektiert wurde und eine dem Fehler entsprechende Korrektur vorgenommen wurde;
• 5 eine schematische Darstellungen eines Einzelpulses, bei dem ein zweiter Fehler detektiert wurde und eine dem Fehler entsprechende Korrektur vorgenommen wurde;
• 6 eine schematische Darstellungen von drei Pulsen der Soll-Pulsfolge, bei denen ein dritter Fehler detektiert wurde und eine dem Fehler entsprechende Korrektur vorgenommen wurde;
• 7 eine schematische Darstellungen einer beispielhaften Pulsfolge, wie sie von einem Plasmagenerator über einen vorbestimmten Zeitraum abgegeben wurde, mit einem Beispiel einer Verlängerung des Abgabezeitraums;
• 8 eine schematische Darstellungen einer beispielhaften Pulsfolge, wie sie von einem Plasmagenerator über einen vorbestimmten Zeitraum abgegeben wurde, mit einem alternativen Beispiel einer Verlängerung des Abgabezeitraums;
• 9 eine schematische Darstellungen einer beispielhaften Pulsfolge, wie sie von einem Plasmagenerator über einen vorbestimmten Zeitraum abgegeben wurde, mit einem weiteren Beispiel einer Verlängerung des Abgabezeitraums.

The invention will be explained in more detail with reference to the drawings; in the drawings shows:

• 1 a schematic representation of an exemplary embodiment of a plasma treatment device;
• 2nd a schematic representations of a target pulse sequence as it is to be delivered over a period of time by a plasma generator;
• 3rd a schematic representations of an exemplary pulse sequence accordingly 1 how it was actually delivered by the plasma generator;
• 4th a schematic representations of a single pulse, in which a first error was detected and a correction corresponding to the error was carried out;
• 5 a schematic representations of a single pulse, in which a second error was detected and a correction corresponding to the error was carried out;
• 6 a schematic representation of three pulses of the target pulse sequence, in which a third error was detected and a correction corresponding to the error was carried out;
• 7 a schematic representations of an exemplary pulse sequence, as it was delivered by a plasma generator over a predetermined period, with an example of an extension of the delivery period;
• 8th a schematic representations of an exemplary pulse sequence, as it was delivered by a plasma generator over a predetermined period, with an alternative example of an extension of the delivery period;
• 9 a schematic representations of an exemplary pulse sequence, as it was delivered by a plasma generator over a predetermined period, with a further example of an extension of the delivery period.

1 shows a schematic representation of an exemplary embodiment of a plasma treatment device 1 with two process units 3a , 3b and a plasma generator 5 . Although in the embodiment two process units 3a , 3b with a plasma generator 5 the person skilled in the art will recognize that only a single process unit can also be provided and the plasma generator can be simplified accordingly.

The process units 3a and 3b can each have the same structure and each have a process chamber for receiving one or more substrates, in particular semiconductor wafers or PV substrates. The process chambers can be sealed and the process units 3a and 3b have different means, not shown, for setting a desired gas atmosphere within the respective process chambers, such as pumps and a gas cabinet. While each process chamber is usually assigned its own pump, a gas cabinet can supply several process chambers if necessary. Means for generating a plasma are also provided in the process chambers, some of which can be formed by a wafer boat which, for example, is introduced into the process chamber together with the substrates and is electrically contacted there, as described, for example, in the above DE 10 2015 004 419 A1 is described, which is so far the subject of the present disclosure.

The process units 3a , 3b stand above power lines 7a respectively. 7b and data connections 8a respectively. 8b with the plasma generator 5 in connection. Via the power lines 7a , 7b delivers the plasma generator 5 electrical power with a frequency greater than 40 kHz to the respective process units 3a and 3b . Via the data connections 8a respectively. 8b can transfer data between the process units 3a , 3b and the plasma generator 5 be replaced. The data connections 8a respectively. 8b can be wired or wireless. In particular, the process units 3a , 3b the plasma generator 5 deliver different process data about processes in the respective process chambers. In particular, actual data relating to the actually incoming electrical power, the presence of a plasma, etc. can be transmitted, but also corresponding target data, as is also the case with known plasma treatment devices with a single process unit and a single plasma generator.

The plasma generator 5 has an adjustable power supply 10th , a switching unit 12th as well as a control unit 14 . The power supply unit has an input, not shown, and an output, which is via a power line 15 with an input of the switching unit 12th connected is. The power supply 10th is suitable in response to a control signal from the control unit 14 output a direct current of a predetermined voltage and / or strength at its output, as is known in the art.

The switching unit 12th has the already mentioned input with the power line 15 is connected to receive DC power from the power supply 10th , as well as two separate outputs, one output with the power line 7a and the other output with the power lines 7b connected is. The switching unit 12th has a converter circuit which can form an alternating current with a predetermined frequency of at least 40KHz as an output signal from a direct current at the input. The converter circuit can have, for example, a bipolar transistor, which consists of the power supply 10th provided direct current forms a quasi sinusoidal signal (step-shaped signal). The switching unit also has 12th a switching part which outputs the output signal thus shaped in response to a control signal from the control unit 14 creates one or the other output, and thus to the process unit 3a or the process unit 3b . The output signals (pulses) must be coordinated in such a way that the respective requirements of the process chamber are met. A corresponding pulse coordination is, for example, in the not previously published DE 10 2018 204 585 the same applicant, which is made the subject of the present application by reference. With only one process unit, corresponding coordination is not necessary and the switch can be omitted, for example, or used to interrupt and / or redirect the output signal to an absorber.

The control unit 14 again has two separate controls for the display 16a , 16b , as well as an arc suppression unit 18th , also known as an arc unit. The controllers 16a , 16b stand over the data connections 8a respectively. 8b with the process units 3a respectively. 3b in connection. The controllers 16a , 16b are each formed in a known manner on the basis of actual data and target data about the respective processes in the process units 3a , 3b Performance requirements for the process units 3a , 3b to determine. The controllers create these 16a , 16b (or a downstream unit) then control data for the power supply 10th and the switching unit 12th . Although the regulator 16a , 16b Shown as separate units, they can also be designed as a single unit, which essentially processes data of the process units in parallel 3a and 3b enables. In particular, the controller 16a , 16b be designed as separate software routines which can be executed essentially in parallel and are executed on a processor.

The performance requirements of the individual process units are generally specified for a particular process and consist of a specific pulse sequence that is to be output over a specific process time. The performance requirements can be made available from a memory of a corresponding system controller (not shown) from a memory, but they can also be determined by the system controller if necessary, with an operator, for example in the case of a PECVD, specifying a layer thickness to be achieved on substrates in the process chamber and the System control determines the corresponding parameters, including the performance requirements in the form of a specific pulse sequence that is to be output over a process time. The pulse sequence generally consists of a sequence of pulses of the same duration, the same distance between the pulses and the same power, even if this is not necessary and can vary. The total output over the process time essentially determines the process result achieved. With a PECVD, the deposited layer thickness is proportional to the output power. Corresponding pulse sequences can, depending on the layer type and layer thickness, consist of a few hundred or fewer, up to several thousand or even tens of thousands of pulses. The number is of course determined by the power and the pulse length. In order to obtain short process times, there is a tendency to provide as much power as possible per pulse, but this increases the risk of arcs or arcs.

In the embodiment shown, corresponding outputs are the controllers with corresponding inputs of the Are unit 18th connected. The arc unit 18th can therefore by the controllers 16a , 16b receive the performance requirements of the individual process units, or directly the control data for the power supply unit created from them 10th and the switching unit 12th . In addition, the Are unit 18th but also unprocessed data directly from the respective process units 3a , 3b receive. Such data are, in particular, those which make it possible to evaluate in real time whether it is in one of the process units 3a and 3b a rollover has occurred or is imminent, which is referred to below as an arc event. The data required for this are known to the person skilled in the art and also the corresponding detection algorithms, which are therefore not initially explained in more detail. In the event of the detection of an arc event, ie a rollover or the danger of such an event, the arc unit can 18th the control signals to the power supply 10th and the switching unit 12th adapt and intervene in the provision of the service to the respective process unit by aborting, changing and / or missing a pulse. Such an intervention is also known as an Are intervention.

The arc unit 18th In this embodiment, it can also be designed such that it receives control data for the power supply unit when it receives performance request data from the individual process units 10th and the switching unit 12th created. This is of course not necessary if the control data already contains this data 16a , 16b to be created. In addition, the arc unit 18th trained so that they can create their own or that of the regulators 16a , 16b created control data for the power supply 10th and the switching unit 12th coordinates. The control data for the power supply 10th and the switching unit 12th are to be coordinated so that the respective process units 3a , 3b performance is provided according to your performance requirements. In addition, the control data for the power supply 10th and the switching unit 12th but also to coordinate in time, since power can only be made available at one of the outputs of the switching unit at any time. As already explained above, the performance is passed to the respective process units 3a , 3b provided as a pulse with a predetermined pulse duration. The respective pulses are therefore via the control data for the power supply 10th and the switching unit 12th Coordinate so that the pulses do not overlap, but the process chambers can still be operated at the same time. Such a pulse coordination is of course not necessary for a single process unit.

The arc unit 18th can, if necessary, differentiate between different types of arc events and perform different are interventions accordingly. Furthermore, the Are unit is able to count the number of Are interventions as a whole, but also according to the respective type. As one skilled in the art will recognize, any intervention in a requested pulse causes a difference between the requested power and the actually output power.

However, since performance is essential to the process result, the control unit is 14 (or the system controller) configures to receive data about the Are interventions and to use the data to determine a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the Arc interventions. After the normal process time, a corresponding additional process time with a corresponding pulse sequence can then be added. Of course, the rest of the process components, such as gas supply, pump, heating, etc., are informed about a corresponding process time extension and controlled accordingly for a longer time.

This is explained below using the 2nd to 9 explained in more detail. It shows 2nd an exemplary pulse train from a plasma generator 5 to be output to a process chamber while 3rd shows an example of the pulse sequence actually output. Here are in 3rd the actually desired pulses are shown in dashed lines.

The desired or requested pulse sequence according to 2nd consists of a certain number of pulses that are to be output over a certain process time in order to bring a desired electrical power into a process. A real process usually has several hundred to several thousand or even tens of thousands of pulses. To simplify matters, only 12 pulses are shown in the illustration, which should be output over a process time. Each pulse is an alternating current pulse with a frequency of at least 40 kHz and a predetermined power (P) that is to be output over the pulse duration. Then there is a pulse pause followed by another pulse. In the illustration, all pulses are the same, ie they each have the same pulse duration and the same amplitude (power). The pulse pauses are also shown with the same length. In the illustration, the pulse pauses are approximately twice as long as a respective pulse (ratio 2: 1). In real processes, however, the ratio is often much larger, such as 9: 1, which would result in a duty cycle of 0.1. In addition, the pulse duration, the pulse pauses and / or the amplitude of the pulses can vary over the process time, although the same pulses with the same pulse pauses are usually requested over a main section.

3rd now shows the pulse sequence actually correspondingly output by a plasma generator, the actually desired pulses being shown in dashed lines. As can be seen, most of the pulses have been completely output, while some pulses have only been partially output and one pulse has not. For the pulses that were only partially output, the average power of the pulse over the pulse duration is displayed.

The incomplete pulse output is based on Arc interventions by the Arc unit 18th . In particular, it is considered within the scope of the application that the arc unit 18th is able to recognize at least two, preferably three or more different arc events and to carry out correspondingly different are interventions. Examples of this are a micro arc event, a U * I arc event and an imax arc event, which are also based on the 4th to 6 with their corresponding interventions are explained in more detail. It shows 3rd a micro-arc event with corresponding are intervention, 4th a U * I arc event with the corresponding Are intervention and 6 an Imax arc event with corresponding arc intervention. An Imax arc event occurs when an overcurrent occurs, ie a current above a threshold value, which indicates the occurrence of an arc. A micro-arc event is indicated by a current (power) peak at a given voltage, a U * I event by an excessive current (power) increase given voltage, the current being below the overcurrent, but an overcurrent would be expected if further power was supplied.

Micro-Arc events usually occur at the beginning of a pulse and are characterized by a small peak in performance. However, they can also occur at any time during the pulse. 4th shows schematically a single pulse with a micro-arc event with appropriate intervention. As can be seen, there is a peak in performance at the beginning of the pulse, whereby transients in the range from micro to nanoseconds can be taken into account here, for example. Although the power drops back to its normal level, the power output is interrupted for a short time shortly after the peak occurs and then continues to be output normally. The delay after the peak is due to the response time of the system. The interruption is only of a short predetermined duration and is achieved, for example, by redirecting the power to an absorber. In the representation, the interruption is approximately 1/10 of the pulse duration, so that approximately 10% of the power of the pulse is lost as a result of the interruption. Of course, the actual lack of power depends on the duration of the interruption and the length of the pulse. Although not shown, another micro-arc event or another event can occur in the same pulse, which would lead to a further Are intervention within the same pulse. Although micro-arc events do not significantly affect the process, an appropriate intervention can be advantageous here, since they often occur before another arc event and thus announce this. The intervention can possibly avoid a following, possibly more serious arc event. There is no need to react to every micro-arc event in the above manner. Rather, the amplitude and / or length of the event can be taken into account when deciding whether an intervention takes place or not.

U * I-Arc events can occur at any point in time of a pulse and are characterized by an excessive increase in the current (the power at constant voltage), the current being below the threshold value for an overcurrent. The increase, however, indicates that an overcurrent would likely occur if the power was added. 5 shows schematically a single pulse with a U * I arc event with appropriate intervention. When a corresponding increase in the power is detected (corresponding to a current increase with a constant voltage), the arc unit interrupts the power output within the pulse and starts the power output again after a predetermined interruption period, but the power is increased like a ramp. The duration of the interruption is significantly longer than with the micro-arc intervention and is four times as long, for example. The possibility of renewed power output naturally depends on the time of the interruption, the interruption duration and the remaining pulse length. Here the missing power depends primarily on the duration of the interruption, the ramp and the length of the pulse. In addition, the time of the interruption might also have to be taken into account, but this would be too complex. Rather, the missing power of the pulse can be averaged and in the embodiment shown it is assumed that it is 50%. Here, too, the intervention criteria for an intervention can be freely determined, the increase rate and / or an increase duration usually being taken into account.

Imax Arc events can record a pulse at any point in time and are characterized by an overcurrent (excessive power with constant voltage), the current being above a threshold value that indicates the occurrence of a flashover or arc. 6 shows schematically three successive pulses of a conventional pulse sequence with an Imax Arc event in the first pulse and a corresponding intervention. When a corresponding Imax event is recognized, the arc unit interrupts the power output within the pulse and starts power output again after a predetermined interruption period, the power being increased in a ramp-like manner, however. The duration of the interruption is significantly longer than with the other interventions and is usually longer than a pulse period consisting of pulse duration and pulse duration. In the representation, the interruption duration is approximately twice a pulse duration. Thus, the first pulse in the three-way sequence is only partially output, the second pulse in the three-way sequence shown is in any case completely absent and the third pulse in the three-way sequence is also only partially output. The missing power of the first and third pulse depends, among other things, on the time of the interruption in the first pulse. However, the total missing power over the three-way sequence essentially depends on the interruption duration, the pulse period and the ramp, which are essentially known to the system. Thus, the power not brought in by the Imax intervention can be averaged and in the illustrated embodiment it is assumed that it is 200%, that is to say that the power of two full pulses is not introduced in an Imax intervention.

The above-mentioned values are, of course, only to be taken as examples and depend essentially on the set intervention parameters, such as interruption pause and, if necessary, ramps, and parameters of the pulse sequence, such as pulse length and pulse period. In any case, the specialist recognize from the above explanation that different arc events can result in different are interventions. These different interventions can in turn have different effects on the performance brought in. By determining the number of interventions (per type) and knowing the approximate effect on the power input (faulty performance), a corresponding control unit can determine a process time extension with a corresponding pulse sequence that can be appended to the normal process time to at least partially correct the faulty performance to compensate. This allows process results to be homogenized across multiple processes. The provision of a process time extension can also depend on whether a significant number of Arc interventions have taken place. In other words, if arc events occur below a threshold, the process can also be ended normally.

Of course, the control unit can also carry out a corresponding analysis of arc events and attacks for the attached process time and determine a further process time extension. It is also possible to output pulses with a lower output during the process time extension than during the normal process time. In this way, the probability of further arc events can be reduced even if the attached process time is thereby extended.

The 7 and 8th show the above variants, the figures each showing an output pulse sequence (requested pulses are shown in dashed lines) within a process time (normal process end is shown by a dashed line), to which a further pulse sequence (pulses with hatching) are attached within a process time extension. As can be seen, some pulses are not complete due to an intervention by the arc unit, and a pulse is not output at all). It is assumed that the operations were carried out as described above or in a similar manner. The respective interventions are as Arc-Type1 (corresponds to Micro-Arc-Event with corresponding intervention), Arc-Type2 (corresponds to U * I-Arc-Event with corresponding intervention) and Arc-Type3 (corresponds to Imax-Arc-Event with corresponding intervention ), and indicated with every pulse. Based on the above values, the control unit can use the number of interventions per type ((6 * Arc-Type1, 4 * Arc-Type2 and 1 * Arc-Type3) to determine that the output of approximately 4.6 pulses was under-output .

In the 7 the process controller has therefore determined the process time by an extension of the process time with a pulse sequence of 4 identical pulses corresponding to the pulses of the normal process time and added it directly to the normal process time. While 4.6 of this was rounded down to the last whole number, you can of course also round up normally or always round up to the next higher whole number. It is also possible, for example, to output the last pulse with a power of 60% of the power of the other pulses. It is not necessary to precisely assign the faulty performance to the attached one with additional performance and, as described above, it is not possible due to the lack of knowledge of the precisely occurring incorrect performance. Although the exact faulty performance could possibly be determined more precisely by a correspondingly higher effort, this is generally not necessary, since the primary aim is to at least partially compensate for faulty performance in order to be able to better comply with predetermined and, if appropriate, tighter tolerances than previously stated. Even the distinction between arc types is not absolutely necessary, provided that the controller can estimate an approximate loss of performance from a total number of arc events, for example if an approximate frequency of occurrence of the individual types is known, or for certain arc events, such as for example, a micro-arc is not intervened at all. This results in a wide variety of options for estimating the faulty performance and determining a corresponding process time extension with a pulse sequence.

In the 8th the process control has determined the process time by a process time extension with a pulse sequence of 9 identical pulses, each with half the power of the pulses of the normal process time, and added it directly to the normal process time. The choice of pulses with lower power per pulse (with the same pulse duration) has the advantage that the probability is reduced that arcs occur during the process time extension. The resulting increase in process time is usually not essential.

In the previous embodiments, the control unit took note of the arc events and determined only one process time extension. In one embodiment, however, it is also possible for the control unit to intervene in the normal pulse sequence via arc interventions. For example, it is known and possible for a control unit to abort a process completely if too many arc events occur, although no distinction has been made here between arc types in the past. As a result, the batch of substrates in the process was generally completely discarded or the substrates were processed (the partially applied layer was removed, for example by etching), inspected and again exposed to a coating).

According to the present embodiment, on the other hand, instead of aborting a process, it is considered to change the pulse sequence when a certain number of arc events occur in such a way that the power per pulse is reduced in order to increase the probability of arc events for the remaining pulse sequence to decrease. The decision as to whether a reduction in performance is to be made from the total number of arc events in the previous process or the number of arc events per arc type can be used. In addition, a frequent occurrence of arc events can lead to a corresponding decision within a shorter period of the process sequence. Especially if there are several arc events of the arc type in quick succession 3rd this can quickly lead to a corresponding decision to reduce the power of the pulses of the pulse train in order to protect the substrates and / or the substrate carriers. The pulse sequence is then continued with lower power per pulse until the end of the process time. On the basis of the number of arc events and the number of pulses with reduced power (and knowledge of the reduced power), a process time extension with a corresponding pulse sequence can then be determined and appended to the normal process time.

A corresponding example is in 9 shows that an output pulse sequence (requested pulses are shown in dashed lines) again shows within a process time (normal process end is shown by a dashed line), to which a further pulse sequence (pulses with hatching) are attached within a process time extension. In the pulse sequence, arcs of types 2 and 3 occur in quick succession (four events within a pulse sequence of 10), whereupon the control for subsequent pulses reduces the power by half, which means that no further arc events occur, however a significantly lower output than planned is also brought in during the process time. Based on the number of arc events and the number of pulses with reduced power (and knowledge of the reduced power), the controller determines a corresponding process time extension with a pulse sequence with pulses that each output 50% less power compared to a normal pulse .

The specified values with regard to the number of arc events that lead to an intervention beyond an Are intervention can of course only be seen as an example. This also applies to the 50% power reduction. Rather, it is of course possible to first reduce the performance by a lower value (for example 10%), in order to then see whether the reduction in performance is sufficient to reduce the arc events sufficiently. If this is not the case, another (or more) reduction (s) can occur within the process sequence. Due to the fact that the control unit is able to at least partially compensate for a resulting malfunction through a process time extension with a pulse sequence, substrate batches can possibly be processed successfully despite major problems in the process.

If an excessive number of arcs occurs, instead of a power reduction for subsequent pulses, the are interventions could also be adapted, for example by extending the respective interruption times and / or making the ramps flatter during the U * I arc intervention or the Imax intervention . While these have so far been designed so that the intervention generates as little error as possible, it can now be designed so that it reduces the probability of subsequent arcs. The resulting faulty performance can be estimated and at least partially compensated for by the process time extension with a corresponding pulse sequence.

The possibility of extending the process time with a pulse sequence can increase the homogeneity of the process results and offers improved possibilities for intervention in the process. In particular, arc interventions can primarily be designed in such a way that the risk of subsequent arcs is reduced (longer breaks, flatter ramps), since greater power loss can be compensated for. In addition, for example, the criteria for when an intervention takes place can also be adapted so that intervention can be made sooner or more often in order to avoid the Imax Arc events as far as possible. This applies in particular to U * I events but also to micro-arc events.

The different approaches above can be combined with each other in such a way that they are compatible with one another, depending on the process requirements. As stated, the power not fed in due to arcing can be fed in at the end of the normal pulse sequence. As a result, the process duration is no longer stored as a fixed value, but is essentially controlled by the power fed in. This enables a significantly better integration of the plasma generator with the coating system and modified recipes.

New recipes would no longer need to define process duration and performance, but could count the amount of energy with a target performance. The target output could be defined with further tolerances than is customary with the current recipes. The process controller could simply stop using an if query or while loop as soon as the desired amount of energy was reported. This further change could be as Alternatively, consider the process at the end of the deposition to query the number of arcs and then calculate the additional time. It would be advantageous to calculate the correct active power (amount of energy delivered in the workpiece carrier). Modern plasma generators can determine the active power with the fed-in, the dissipated power and the phase shift of the current. Inaccuracies should be kept as small as possible here, since the performance correction can otherwise lead to a greater deviation than if it is not made.

The invention has been described above on the basis of preferred embodiments of the invention, without being limited to the specific embodiments. In particular, the plasma generator can also be used only for one plasma unit. This can involve a wide variety of plasma units in which the process result depends largely on the power input. The number of plasma units to be supplied by a plasma generator can also differ from the number shown (here two).

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102015004419 A1 [0003, 0025]
• DE 102018204585 [0028]

Claims (17)

Plasma treatment device comprising: a plasma generator configured to output pulses of electrical power to at least one process chamber, the plasma generator configured to generate and output the pulses over a process time according to a predetermined pulse sequence, and wherein the plasma generator has an arc unit that is suitable for a rollover or to recognize an upcoming rollover, also called an arc event, and in response to this, abort, change and / or to cancel a pulse which is or is to be output to the process chamber, which is referred to as an are intervention; and at least one control unit configured to To receive and evaluate process data about processes in the at least one process chamber and to use the process data to determine at least one process time and a pulse sequence to be made available by the plasma generator over the process time, or to receive a specific process time and pulse sequence, the pulse sequence being configured A predetermined power is to be introduced into the process chamber via the process time; to control the plasma generator, to output the pulse sequence over the process time, - Obtain data on Are interventions and use the data to determine a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the Arc interventions. Plasma treatment device after Claim 1 that has a unit that is configured to determine the number of interventions and to transmit the number to the at least one control unit. Plasma treatment device after Claim 1 comprising a unit configured to recognize at least two different types of Are interventions, to determine the number of each type of Are intervention and to transmit the number to the at least one control unit. Plasma treatment device after Claim 2 or 3rd , where the unit is part of the arc unit. Plasma treatment device according to one of the preceding claims, wherein the arc unit is configured to detect at least two different types of arc events and to select different predetermined arc interventions corresponding to the arc event. Plasma treatment device after Claim 5 , wherein the arc unit is configured to recognize at least two of the following arc events: an Imax event which indicates an overcurrent, ie a current above a threshold, and thus the occurrence of an arc; a U * I event which, before an overcurrent is reached, indicates an excessive current rise at a given voltage (Uxl) in such a way that an overcurrent would be expected if further power were supplied; - a micro-arc, which is indicated by a current peak at a given voltage; and wherein the arc unit is further configured - when an Imax event is detected, abort the current pulse completely and then slowly increase the power, so that the subsequent pulse may also not be fully output; - to interrupt the current pulse when a U * I event is recognized and, if possible, to restart within the planned pulse time with an increasing power ramp; and - when a micro-arc is detected, interrupt the current pulse and continue to output it after a short waiting time. Plasma treatment device according to one of the preceding claims, wherein the control unit is configured to control the plasma generator when a certain number of arc events are reached within the process time, to reduce the power output per pulse of the remaining pulse train and to reduce power accordingly when determining the process time extension appropriate pulse train to be considered. Plasma treatment device according to one of the preceding claims, wherein the control unit is configured, when determining the process time extension with a corresponding pulse sequence, to select the average power of the pulses lower than the average power of the pulses during the process time. Method for outputting pulses of electrical power to at least one process chamber, which comprises: - determining or receiving a process time and pulse sequence for the process chamber in / on a control unit; - Controlling a plasma generator in order to output the pulse sequence over the certain process time, - Detecting an arc event that indicates a rollover or an upcoming rollover, - In response to the detection of an arc event, performing an are intervention that cancels, change and / or failure to have a pulse that is output to the process chamber or is to be output, Obtaining data about Are interventions and determining on the basis of the data a process time extension with a corresponding pulse sequence in order to at least partially compensate for a power reduction caused by the Are interventions; and - controlling the plasma generator in order to output the corresponding pulse sequence after the specific process time over the duration of the specific process time extension. Procedure according to Claim 9 , with the data on Are interventions being the number of Are interventions. Procedure according to Claim 9 or 10th , wherein different types of arc interventions are carried out, and wherein the data on are interventions include at least the types of arc interventions and the respective number of arc interventions. Procedure according to one of the Claims 9 to 11 wherein recognizing arc events includes recognizing at least two different types of arc events, and performing the arc intervention, selecting a predetermined arc intervention from a plurality of predetermined are interventions corresponding to the arc event, and performing of the selected arc intervention. Procedure according to Claim 12 , wherein the detection of arc events comprises the detection of at least two of the following arc events: an Imax event which indicates an overcurrent, ie a current above a threshold, and thus the occurrence of an arc; a U * I event which, before an overcurrent is reached, indicates an excessive current rise at a given voltage (Uxl) in such a way that an overcurrent would be expected if further power were supplied; and / or - a micro-arc, which is indicated by a current peak at a given voltage; and wherein performing the arc intervention has the following: - upon detection of an Imax event, aborting the current pulse completely and then slowly increasing the power, so that the subsequent pulse may not be fully output; - to interrupt the current pulse when a U * I event is recognized and, if possible, to restart within the planned pulse time with an increasing power ramp; and / or - to interrupt the current pulse when a micro-arc is detected and continue to output it after a short waiting time. Procedure according to one of the Claims 9 to 13 , wherein when a certain number of arc events are reached within the process time, the plasma generator is controlled to reduce the power output per pulse of the remaining pulse train, and a corresponding power reduction is taken into account when determining the process time extension with a corresponding pulse train. Procedure according to Claim 14 , the power reduction for the remaining pulses being at least 10%, preferably at least 20%. Procedure according to one of the Claims 9 to 15 , whereby when determining the process time extension with a corresponding pulse sequence, the average power per pulse is chosen to be lower than the average power per pulse during the process time. Procedure according to Claim 16 , wherein the average power per pulse during the process time extension is chosen to be at least 10%, preferably at least 20% lower than the average power per pulse during the process time.

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