Patent Application
20170069468
The invention relates to a device for processing plasma with low-temperature plasmas that have multiple plasma processing zones in a processing chamber, in which a portion of the exhaust gas that is discharged from the processing chamber is added back to the process gas for the plasma processes.
Plasma processes are used, as examples, in the production of solar cells, microelectronics and the refinement of substrate surfaces (e.g. glass) with regard to the deposition or removal of layers or particles or with regard to the doping of layers, for instance via plasma-immersion ion implantation. To increase the throughput in the plasma processing, batch systems are used in which several substrates are simultaneously treated. In so doing, the substrates with the surface to be processed can be arranged next to or on top of one another. Systems are known from U.S. Pat. No. 4,287,851 B and EP 0 143 479 A1 in which a plasma processing zone, which is operated separately from the other plasma processing zones, is assigned to each substrate.
The process gas that is used during the plasma processing is either introduced in only one place in the processing chamber and is distributed to the individual plasma processing zones from there or is fed into the individual plasma processing zones via separate outlet openings (e.g. nozzles) in each case. In so doing, the process gas advantageously flows through the plasma processing zone.
Different processing results can come about over the multitude of substrates that are simultaneously processed because of differences in the plasma-production conditions, in the boundary conditions for a particular substrate (for instance ambient temperature) and other instances of inhomogeneity in the processing chamber. They can constitute, as examples, different deposition or etching rates or different compositions of the deposited layers or different doping amounts.
Furthermore, in the case of large substrates, an inhomogeneity of the process comes about over the whole lateral extension of the substrate because the process gas changes in terms of its composition over its transport path through the plasma processing zone. The number of reactive components decreases, for example, because of the reactions of components of that type that have taken place over the length of the substrate in the direction of the process gas flow. The layer thickness based on deposition or removal therefore also decreases in this substrate direction.
A pulsing of the plasmas that are produced is a known remedy to the last problem. In so doing, the plasmas are only ignited for a short period of time with a short pulse; the plasmas are shut off for most of the time (approx. 90%) in a cycle. New, unspent process gas can be distributed over the entire substrate during this down time, so equal deposition or etching rates can be achieved at all points of the substrate during the period in which the plasma is ignited. This leads to a substantial increase in the processing time, however, because only 10% of the overall time is effectively used.
The device for plasma processing as per the invention is comprised of a processing chamber with at least two plasma processing zones with process gas flowing through them, a gas inlet that is suitable for feeding the process gas to the at least two plasma processing zones, and a gas outlet that is suitable for discharging exhaust gas from the processing chamber, as well as a circulation unit with a circulation line and a circulation pump, wherein the circulation unit is suitable for feeding at least a portion of the exhaust gas into the gas inlet and wherein the exhaust gas that is fed into the gas inlet is a mixture of gases that are discharged from at least two of the plasma processing zones. Because of the mixture of exhaust gases from at least two of the plasma processing zones and their renewed feeding into the gas inlet, the components of the process gas from the at least two plasma processing zones that have already been converted, but also those that have not yet been converted, are mixed and a homogenization of the process gas is therefore achieved that is fed into the plasma processing zones. This reduces the inhomogeneity of the plasma processing among individual substrates that arises from differences in the plasma process in different plasma processing zones.
The objective of the instant invention is to consequently provide a device for plasma processing of multiple substrates with several plasma processing zones that is suitable for reducing instances of inhomogeneity of plasma processing among individual substrates that rise because of differences of the plasma processing in different plasma processing zones. Furthermore, an objective of the instant invention is to provide a device for plasma processing that also reduces instances of inhomogeneity of plasma processing over a whole substrate.
This problem is solved by the device according to claim 1. Advantageous embodiments are found in the subordinate claims.
The device for plasma processing as per the invention is comprised of a processing chamber with at least two plasma processing zones with process gas flowing through them, a gas inlet that is suitable for feeding the process gas to the at least two plasma processing zones, and a gas outlet that is suitable for discharging exhaust gas from the processing chamber, as well as a circulation unit with a circulation line and a circulation pump, wherein the circulation unit is suitable for feeding at least a portion of the exhaust gas into the gas inlet and wherein the exhaust gas that is fed into the gas inlet is a mixture of gases that are discharged from at least two of the plasma processing zones.
In general, the terms “gas”, “process gas” or “exhaust gas” in this application are understood to mean any kind of gas or gas mixtures that are suitable for plasma processing or that arise during it.
The gas inlet is realized, for instance, by at least one opening connected to a gas line in the wall of the processing chamber, by at least one gas line (pipe) projecting into the processing chamber or by an intake chamber that is connected to at least one gas line and that has one or more openings from which the process gas flows into the processing chamber. In the same way, the gas outlet is realized, for instance, by at least one opening connected to an exhaust gas line in the wall of the processing chamber, by at least one exhaust gas line (pipe) projecting into the processing chamber or by an outlet chamber that is connected to at least one exhaust gas line and that has one or more openings through which the process gas flows out of processing chamber.
As already described above, different plasma processing zones can have different rates of conversion of the components of the process gas, for instance into radicals, ions or reaction products. Because of the mixture of exhaust gases from at least two of the plasma processing zones and their renewed feeding into the gas inlet, the components of the process gas from the at least two plasma processing zones that have already been converted, but also those that have not yet been converted, are mixed and a homogenization of the process gas is therefore achieved that is fed into the at least two plasma processing zones. This reduces the inhomogeneity of the plasma processing among individual substrates that arises from differences in the plasma process in different plasma processing zones. In other words: The deposition rate or etching rate or other processing rates of the substrates are homogenized, i.e. balanced out, by the thorough mixing of the process gases over all of the substrates.
Furthermore, the process gas is made better use of for the respective plasma process because, on the one hand, components of the process gas that have not yet been used for the layer deposition or removal are fed into the plasma process once again and, on the other hand, the process gas will thereby already contain reactive components or activated components that require less activation for the desired reaction than a process gas that has not yet been activated up to that point via a plasma. Both a reduction in the gas consumption, meaning the consumption of fresh process gas, and an increase in the deposition or etching rate for the plasma process can be achieved because of that.
The circulation unit preferably comprises a control valve, wherein the control valve and the circulation pump are designed in such a way that the ratio of the gas flow of the exhaust gas fed into the gas inlet via the circulation line to the gas flow of a gas differing from the exhaust gas that is fed into the gas inlet is in a range smaller than 100. A typical and preferred value for the ratio is between 8 and 12, with a special preference for 10. This means that a gas flow greater by multiples than the gas flow freshly fed into the plasma processing is removed from the exhaust gas by the circulation unit and fed back into the gas inlet and therefore the plasma processing. The flow rate of the process gas through the plasma processing zones is significantly increased because of that, and the retention time of the process gas in the respective plasma processing zone is significantly reduced, for instance by approximately 10-fold. The degree of plasma-chemical degradation of the process gas while passing through the respective plasma processing zone also drops with that; a more homogeneous composition of the components of the process gas in the plasma processing zone is achieved over the length of the substrate in the direction of flow of the gas because of that and, in the end, a more homogeneous thickness of the deposited or removed layer is achieved over the whole extension of the substrate. In other words: The processing of each substrate is homogenized over its whole extension in the direction of the gas flow. Moreover, the above-mentioned effect of a renewed feed-in of gas components that have already been activated is reinforced, which leads to a further increase in the deposition or etching rate.
Outstanding homogenization of the layer thicknesses and/or other layer properties, for instance optical or electrical properties such as transparency, refraction index, electrical conductivity etc., is achieved over the whole extension of a substrate in the direction of the gas flow and over a multitude of substrates because of the effects of the gas feedback that were described; the deviations of layer thickness or of the other layer properties are in a range of a few percentage points, for instance less than or equal to ±4%.
In one embodiment of the device as per the invention, the circulation line is connected to a gas supply line that is suitable for feeding a gas differing from the exhaust gas into the gas inlet. This gas is a fresh gas or gas mixture that can contain one, several or all of the components of the process gas and serves to start the plasma process and to replace the components of the process gas that are consumed by the plasma processing. The freshly fed-in gas and the exhaust gas that is fed back into the plasma process via the circulation line are therefore already mixed in the gas supply line that is connected to the gas inlet, and only one gas supply line is required to feed both the freshly fed-in gas and the recirculated exhaust gas into the processing chamber.
In a preferred embodiment, the gas inlet is connected to two gas supply lines; a first gas supply line is directly connected to the circulation line, and a second gas supply line is connected to a device for providing a gas differing from the exhaust gas. The second gas supply line is therefore suitable for feeding a fresh gas or a fresh gas mixture to the process gas, so components of the process gas that are consumed by the plasma processing can be replaced.
The gas inlet is preferably designed in the form of a gas inlet mixing chamber that has at least two discharge systems each with one or more openings. Each discharge system is assigned to one of the at least two plasma processing zones here, so the process gas flows out of the openings of the respective discharge system to the assigned plasma processing zone. The multiple openings of a discharge system preferably have an arrangement and size to the effect that the process gas is fed into the plasma processing zone evenly or in a manner adapted to the plasma conditions of the plasma processing zone. As an example, the openings can be arranged at a smaller distance to one another in the edge area of the plasma processing zone or can have different key values than the openings in a central area of the plasma activation zone. Furthermore, the individual discharge systems, meaning discharge systems differing from one another assigned to different plasma processing zones, can have different arrangements and/or key values of the openings. The openings of the discharge systems preferably have the same key value. In addition to the defined supply of the process gas to the individual plasma processing zones, the inlet chamber is also suitable for ensuring a mixture of the exhaust gas fed in via the circulation line and the fed-in gas differing from the exhaust gas. This is especially advantageous if the exhaust gas fed in via the circulation line and the fed-in gas differing from the exhaust gas are fed into the gas inlet via two gas supply lines that are separated from one another. The gas inlet mixing chamber can be arranged outside on the wall of the processing chamber or inside of the processing chamber, in contact with the wall or spaced apart from it.
If the gas inlet is connected to two gas supply lines, the first serving to feed in the exhaust gas and a second one serving to provide a gas differing from the exhaust gas, as described above, the gas inlet mixing chamber will have at least two sub-chambers in an especially preferred embodiment; each sub-chamber will have a separate discharge system from which the process gas flows to at least one plasma processing zone and which is assigned in each case to at least one of the plasma processing zones. Every sub-chamber is assigned to at least one dispensing unit here that is suitable for separately adjusting the quantity of fed-in exhaust gas or the quantity of the fed-in gas differing from the exhaust gas for the respective sub-chamber.
The gas outlet is preferably realized by a gas outlet mixing chamber that has at least two intake systems, each with one or several openings through which the exhaust gas from the plasma processing zones flows into the gas outlet mixing chamber; each intake system is assigned to one of the at least two plasma processing zones. The multiple openings of an intake system preferably have an arrangement and size to the effect that the process gas is discharged from the assigned the plasma processing zone evenly or in a manner adapted to the plasma conditions of the plasma processing zone. What has already been stated with regard to the discharge systems and their openings applies here. The openings of the at least two intake systems preferably have the same key value. The gas outlet mixing chamber can be arranged outside on the wall of the processing chamber or inside of the processing chamber, in contact with the wall or spaced apart from it.
In a preferred embodiment, the gas outlet is connected to a device for discharging gas through an exhaust gas line and the circulation line is connected to the exhaust gas line. Only one exhaust gas line connected to the gas outlet is therefore necessary. The device for gas discharge, for instance a vacuum pump, serves here, on the one hand, to set a defined pressure in the processing chamber and to also discharge the exhaust gas from the gas outlet, and therefore serves to regulate the supply of the process gas to the process chamber.
In another preferred embodiment, the gas outlet is connected to a device for gas discharge through an exhaust gas line and, separately from that, connected to the circulation line. This means that the gas outlet is connected to two gas discharge lines, the first of which is the exhaust gas line and the second of which is the circulation line. This makes it possible to adapt both the exhaust gas line and circulation line and also the device for gas discharge and the circulation pump to the parameters and purity requirements to be set. As an example, the circulation pump is not supposed to bring about any impurities of the recirculated exhaust gas; greater demands can be placed on the circulation pump than on the vacuum pump connected to the exhaust gas line because of that.
The circulation unit preferably contains a dust-collection device that is preferably arranged in front of the circulation pump in the circulation line.
As a further preference, the circulation unit contains a device for removing specific components of the exhaust gas, especially gaseous components. That can be reaction products that are no longer used in the plasma process, for instance.
In a preferred embodiment, the gas inlet and the gas outlet are identical and the device for plasma processing has a changeover unit that is suitable, in a first switching state, to supply the gas inlet with exhaust gas fed in through the circulation line and the fed-in gas differing from the exhaust gas, and to discharge the exhaust gas from the gas outlet, and, in a second switching state, to supply the gas outlet with exhaust gas fed in through the circulation line and the fed-in gas differing from the exhaust gas, and to discharge the exhaust gas from the gas inlet. The device for plasma processing is therefore suitable for bringing about a change in the gas circulation direction of the gas flow in the processing chamber and the plasma processing zones. The thickness of the layer that has been deposited or removed can therefore be homogenized, i.e. balanced, in an even better way over the whole extension of the substrate. The changeover unit is preferably comprised of two valve groups, each with two valves; the valves of the first valve group are switched in an opposite way with respect to the valves of the second valve group in each case. One valve of each valve group is located in the exhaust gas branch of the device, and the other respective valve of each valve group is located in the supply branch of the device. The changeover unit is preferably suitable for changing the switching state and therefore the direction of gas circulation between 5 and 25 times per plasma processing event. A plasma processing event is, for instance, the coating of a substrate with a specified layer thickness or the removal of a specified thickness of a layer from a substrate.
The device for plasma processing preferably has, moreover, a device for moving an arrangement of substrates that are processed in the plasma processing zones along a first direction in the processing chamber. The processing chamber is comprised of several gas inlets and several gas outlets here; the gas inlets and the gas outlets are arranged in an alternating fashion along the first direction on one side of the processing chamber. As an example, the gas inlets and gas outlets are arranged on the upper wall of the processing chamber; the substrates are laterally arranged next to one another and move along beneath the plasma processing zones that are arranged along the first direction between the respective gas inlets and gas outlets. In so doing, the process gas flows to the substrate arrangement, but not through the substrate arrangement. This corresponds to a so-called in-line plant with flat, individual substrates laterally arranged next to one another in which the process gas flows in a direction along the direction of movement of the substrates. The exhaust gas from at least two gas outlets is mixed by the circulation unit and fed back into the gas inlets.
In another preferred embodiment, the gas inlet and the gas outlet are arranged on opposite sides of the processing chamber. The plasma processing zones can be arranged laterally next to one another or preferably vertically stacked on top of one another between the gas inlet and the gas outlet here.
The device for plasma processing preferably has, moreover, a device for moving an arrangement of substrates that are processed in the plasma processing zones along a first direction in the processing chamber. The processing chamber is comprised of several gas inlets and several gas inlets that are assigned to them here; the gas inlets and the gas outlets are arranged along the first direction in such a way that a specific gas inlet is arranged on one side of the processing chamber that extends along the first direction and a gas outlet that is assigned to this specific gas inlet is arranged on the opposite side of the processing chamber. In so doing, the substrates in the substrate arrangement are arranged laterally next to one another or preferably vertically stacked on top of one another between a specific gas inlet and a gas outlet arranged to be opposite it so that the process gas flows through the substrate arrangement and the plasma processing zones assigned to the respective gas inlet and gas outlet. This corresponds to an in-line plant in which substrate stacks can also be processed where the process gas flows in a direction that is vertical with respect to the direction of movement of the substrates. In the process, the substrates can be moved during the plasma processing or can be processed in a quasi-stationary manner. In the second case, the substrates are moved from a position between a first pair made up of a gas inlet and an assigned gas outlet to a different position between a second pair made up of a gas inlet and an assigned gas outlet in the processing chamber, but they remain without movement at the respective position during the plasma processing.
The gas outlet preferably discharges the exhaust gas in the process from at least two plasma processing zones that are supplied with process gas by the assigned gas inlet, mixes this and feeds it back to at least the assigned gas inlet.
In a preferred embodiment, the device for plasma processing is comprised of the same number of circulation units as there are pairs of gas inlets and gas outlets assigned to them; a circulation unit is assigned to every specific pair made up of a gas inlet and an assigned gas outlet. The exhaust gases from a specific gas outlet are therefore exclusively fed into the assigned gas inlet by the assigned circulation unit.
Alternatively, the exhaust gases of several gas outlets are mixed with one another and fed back into at least one, preferably several, gas inlets. In an especially preferred embodiment, the exhaust gases from all of the gas outlets are mixed and fed into all of the gas inlets. Only one circulation unit is required for this design form.
In an especially preferred embodiment of the device for plasma processing, the gas inlets and the accompanying gas outlets of two pairs of gas inlets and gas inlets assigned to them that are arranged in back of one another in the first direction are arranged in such a way that the gas inlet of the one pair is located on the same side of the processing chamber as the gas outlet of the other pair. At least two gas inlets and two gas outlets are thereby arranged in an alternating fashion on the same side of the processing chamber along the first direction. Instances of inhomogeneity over the extension of the substrates in the direction of flow of the process gas are balanced out with this arrangement, because the direction of flow of the process gas alternatives between the two pairs of gas inlets and assigned gas outlets.
The device for plasma processing as per the invention will be explained below with the aid of several examples without limiting the device to these examples. In particular, it is possible to combine aspects with one another that are described with reference to different examples as long as this is not expressly ruled out.
With regard to
A first embodiment of the device (1) for plasma processing as per the invention is shown in
The processing chamber (10) has several plasma processing zones (11a to 11c), as well as a gas inlet (13) that is realized in the form of a gas inlet mixing chamber and a gas outlet (14) that is realized in the form of a gas outlet mixing chamber. The processing chamber (10) has three plasma processing zones (11a to 11c) in the embodiment shown in
The gas inlet (13) is arranged on a first side of the processing chamber (10), whereas the gas outlet (14) is arranged on a second side of the processing chamber; the second side of the processing chamber is opposite the first side. Both the intake chamber of the gas inlet (13) and the outlet chamber of the gas outlet (14) are arranged inside of the processing chamber (10), meaning on the inside of the wall of the processing chamber (10). The substrates (12a to 12c) are arranged between the first and second sides of the processing chamber (10) so that a process gas flowing between the gas inlet and the gas outlet will flow through the substrate arrangement, meaning the entirety of the substrates. The gas inlet (13) has several discharge openings (131a to 131c) from which the process gas flows to the plasma processing zones (11a to 11c), whereas the gas outlet (14) has several intake openings (141a to 141c) through which the exhaust gas that is being discharged from the plasma processing zones (11a to 11c) flows into the gas outlet. Three discharge openings (131a to 131c) and three intake openings (141a to 141c) exist in the embodiment shown in
In other embodiments, the number of discharge openings and the number of intake openings can also differ from three, differ from one another and even be different for different plasma processing zones. Furthermore, the number of discharge openings for various discharge systems, the number of intake openings for various intake systems, as well as the vertical position of the discharge openings in a specific discharge system and the vertical position of the intake openings in a specific intake system, meaning their position with reference to the y axis, can be different.
The gas inlet mixing chamber has a sufficiently large cross-section in the x-y plane and therefore a sufficiently small key flow value in the interior, so the process gas can be fed into the multiple plasma processing zones from the discharge openings (131a to 131c) in an equally distributed way. The discharge openings (131a to 131c) advantageously have small cross-sections and dimensions such that the effect of gas interblocking arises in them.
The gas inlet (13) is connected to the gas supply line (21) via which the process gas is fed into the gas inlet (13). The process gas is comprised here of a mixture of fresh gas that is provided by the gas provision unit (22) and of exhaust gas that is fed back into the gas inlet (13) from the gas outlet (14) via the circulation unit (30). The fresh gas and the exhaust gas are already mixed in the gas supply line (21) in the process and, moreover, in the gas inlet mixing chamber of the gas inlet (13). The quantity of fresh gas is regulated via a dispensing unit, for instance a mass flow controller, in the gas provision unit (22).
The gas outlet (14) is connected to an exhaust gas line (23) to which a pump (24) is connected. The pump (24) serves, on the one hand, to suction off the exhaust gas arising during the plasma processing and, on the other hand, to set a defined pressure in the processing chamber (10) together with the control valves (25a, 25b) arranged in the exhaust gas line (23). In the process, the exhaust gases from different plasma processing zones (11a to 11c) are mixed in the gas outlet mixing chamber of the gas outlet (14) and in the exhaust gas line (23).
The circulation unit (30) is comprised of a circulation line (31) and a circulation pump (32). The circulation line (31) is connected to the exhaust gas line (23) and the gas supply line (21) in the first embodiment of the device for plasma processing as per the invention, so the gas inlet (13) is only connected to the gas supply line (21) and the gas outlet (14) is only connected to the exhaust gas line (23). A portion of the exhaust gas is fed back into the process gas with the aid of the circulation unit (30); the proportion of exhaust gas that is fed back in again with respect to the overall exhaust gas is set with the control valves (25a, 25b). The proportion of exhaust gas that is fed back in again is therefore also regulated with respect to the overall process gas, which is equal to or greater than the flow of fresh gas. As an example, a gas flow that is 10 times larger than the gas flow of the fresh gas is removed from the exhaust gas and fed into the gas inlet again. A Roots pump that generates sufficient overpressure for the gas circulation with a compression ratio of about 10 is suitable as a circulation pump (32). Since Roots pumps with suction power in the range of 250 to 25,000 m3/h are available, very large processing chambers can also be provided with adequate gas circulation. Roots pumps are advantageously used in a design with semiconductor-level purity, so only very small leakage rates additionally arise in the circulation unit (30) and contamination of the process gas with gearbox oil from the Roots-pump shaft bearings, for instance, is prevented. The diameter (d1) of the circulation line (31) in front of the circulation pump (32) in the direction of the pumped gas can be greater than the diameter (d2) of the circulation line (31) after the circulation pump (32) in the direction of the pumped gas here.
The layer thickness ds decreases in the x direction in the conventional process, because the process gas undergoes plasma-chemical degradation in the plasma processing zone with the low flow velocity and the deposition rate drops with an increasing share of breakdown products. Furthermore, other layer parameters, for instance optical or electrical properties such as transparency, refraction index, electrical conductivity etc. can also change.
When the device as per the invention is used, the process gas is moved through the plasma processing zone with a greater, for instance ten-fold, flow velocity caused by the gas circulation in the circulation unit (30). The plasma-chemical degradation of the process gas in the plasma processing zone is dropped so low with this increased gas flow throughput Q2 that the deposition rate remains virtually unchanged. The layer thickness ds and the other layer parameters will therefore be homogenized, i.e. uniformly produced, over the whole extension of the substrate in the x direction.
An explanation is provided with the aid of
Differentially small gas volumes (2), (3) and (4) are considered on their flow path in two different instances of gas circulation for this in
In a first circulation cycle, the differential gas volumes (2), (3) and (4) all have a first gas composition (a) at first that is the same for all of the differential gas volumes (2), (3), and (4). While the individual differential gas volumes (2), (3) and (4) each cross through the corresponding plasma processing zone (11a to 11c), the overall composition for each differential gas volume changes in a special way depending on the characteristics of the plasma processing zone and the plasmas located in it. The plasma-chemical gas conversion can be somewhat different in the individual plasma zones, e.g. because of slightly different instances of plasma power coupling, which leads to a situation in which the differential gas volumes (2′), (3′) and (4′) can differ with regard to their gas composition after leaving the plasma zones.
As a result of that, the first differential gas volume (2′) has a first, slightly changed gas composition (a1), whereas the second differential gas volume (3′) has a second, slightly changed gas composition (a2) and the third differential gas volume (4′) has a third, slightly changed gas composition (a3) that can all differ from one another.
The differential gas volumes (2′), (3′) and (4′) are now mixed on their path through the circulation unit (30) so that there is a fourth differential gas volume (5) that has a fourth, homogenized gas composition (b) in the circulation line (31) in front of the connection to the gas supply line (21). The fourth differential gas volume (5) is mixed with fresh gas, if necessary, so a fifth differential gas volume (6) with a fifth gas composition (c) that can differ from the first gas composition (a) exists in the gas supply line (21).
This fifth differential gas volume (5) is now fed into the gas inlet (13) and, in a second cycle, fed into the corresponding plasma processing zones (11a to 11c) again as new differential gas volumes (2), (3) and (4) via the discharge openings (131a to 131c); the gas composition of the differential gas volumes (2), (3) and (4) among one another is equal once again.
A gas molecule that has gone through the first plasma processing zone (11a) in the first cycle can therefore go through the second plasma processing zone (11b), for instance, in the second cycle or through the third plasma processing zone (11c), which precisely brings about the intended gas-mixing effect. The processing rates and the layer properties that are obtained are therefore balanced out over all of the substrates whose process gases are mixed in the circulation unit (30).
The effects of gas recirculation through the gas circulation unit (30) that have been explained with regard to
In other embodiments, moreover, it is possible to provide further gas supply lines that feed further fresh gas into the gas inlet (13) in addition to the second gas supply line (21b). This is, in particular, advantageous when the freshly fed-in gases under normal pressure lead to problems with regard to safety when they are mixed.
The first exhaust gas line (23a) corresponds to the circulation line (31) and is directly connected to the circulation pump (32), whereas the second exhaust gas line (23b) is only connected to the pump (24). The gas outlet mixing chamber of the gas outlet (14) therefore has a sufficiently large cross-section in the x-y plane and thereby a sufficiently small key flow value in the interior, so the exhaust gases from the multiple plasma processing zones are thoroughly mixed. The gas flow of the exhaust gas that is fed once again into the gas inlet (13) is adjusted with the control valve (25a) arranged in the circulation line (31), whereas the pressure in the processing chamber (10) is adjusted with the control valve (25b) arranged in the second exhaust gas line (23b).
Features of the first and the second embodiments can also be combined. As an example, the device (1) for plasma processing can also comprise two gas supply lines (21a, 21b) as shown in
Although a dispensing unit (26a to 26f) is shown in every gas supply line in each case in
In another advantageous embodiment, the dust-collection device (33) is arranged behind the circulation pump (32) in the direction of the pumped gas so that a drop in pressure in the dust-collection device (33) will have less of an impact. It is also possible for several dust-collection devices of that type or multi-stage devices to be used.
The device (34) for removing specific gaseous components of the exhaust gas serves to remove components of the exhaust gas that can no longer be used in the plasma processing or that exist in the exhaust gas in quantities that are too high. They could be reaction products, for instance, that no longer contribute to the actual plasma process to be carried out. These components can be removed in whole or in part from the exhaust gas transported in the circulation line (31) by the removal device (34) and carried off by a removal line (35). The device (34) for removing specific gaseous components of the exhaust gas can be arranged in front of or in back of the circulation pump (32) in the direction of the pumped gas in the circulation unit (30).
A fourth embodiment of the device (1) for plasma processing is schematically shown in
Specific examples of the production of plasma and the electrical connection of the substrate holders are explained with reference to
In general, the plasma(s) used for the processing can be low-pressure plasmas for which the required power can be coupled in via electrodes, via an inductive process, via microwaves or via dielectric windows.
Furthermore, a heating element (15) that ensures the substrate temperature and/or gas temperature required for the plasma processing is also shown in
The exhaust gases that leave all of the gas outlets (14a, 14b) located in the processing chamber (10) are advantageously mixed with one another and fed into all of the gas inlets (13a, 13b) located in the processing chamber (10). It is also possible in other embodiments, however, to only mix the exhaust gases from specific gas outlets and to only feed them into specific gas inlets. Process-gas differences between the individual plasma processing zones (11a to 11c), but also within a specific plasma processing zone, are balanced out by the mixture of exhaust gases and their renewed supply to the gas inlets.
But individual pairs made up of one gas inlet and one gas outlet can also be arranged opposite one another in other embodiments. As an example, the gas inlets 13a and 13c can be arranged on a first side of the processing chamber (10) and the accompanying gas outlets 14a and 14c on the opposite, second side of the processing chamber (10), whereas the gas inlet 13b is arranged on the second side of the processing chamber (10) and the accompanying gas outlet 14b is arranged on the first side of the processing chamber (10). A change of the direction of gas flow can therefore be achieved in neighboring plasma processing zones (11a to 11c) without using the changeover unit shown in
In examples other than the ones shown in
1 Device for plasma processing
2-6 Differential gas volume
10 Processing chamber
11
a-11c Plasma processing zone
111 Remote plasma
12
a-12d Substrate
120 Substrate carrier
121 First electrodes
122 Second electrodes
13 Gas inlet
13
a-13c Sub-chamber
131
a-131c Discharge opening
132
a,b Partition wall
14 Gas outlet
141
a-141c Intake opening
15 Heating element
21 Gas supply line
21
a First gas supply line
21
b Second gas supply line
22 Gas provision unit
23 Exhaust gas line
23
a First exhaust gas line
23
b Second exhaust gas line
24 Pump
25
a, 25b Control valve
26
a-26f Dispensing unit
27 First valve group
24
a,b Valves of the first valve group
28 Second valve group
28
a,b Valves of the second valve group
30 Circulation unit
31 Circulation line
32 Circulation pump
33 Dust-collection device
34 Device for removing gas components
35 Removal line
60 Generator
61 Pulse generator
62 Match and filter box
70 Device for the movement of substrates
| Number | Date | Country | Kind |
|---|---|---|---|
| 14158269.2 | Mar 2014 | EP | regional |
This application is the U.S. national stage of International Application No. PCT/EP2015/054334, filed on Mar. 3, 2015. The international application claims the priority of EP 14158269.2 filed on Mar. 7, 2014; all applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/054334 | 3/3/2015 | WO | 00 |
