The present invention relates to an apparatus for subjecting a surface of a substrate to alternate surface reactions of at least two precursors according to the principles of atomic layer deposition, and more particularly to an apparatus as defined in the preamble of the independent claim 1.
The present invention further relates to a method for circulating precursor in an apparatus for subjecting a surface of a substrate to alternate surface reactions of at least two precursors according to the principles of atomic layer deposition, and more particularly to a method as defined in the preamble of the independent claim 8.
In prior art spatial ALD-apparatuses and methods for coating a surface of a substrate with an ALD method in which the precursor supplied from the precursor nozzle to the surface of the substrate has to have a sufficient level of precursor partial pressure in order to provide a high quality coating on the surface of the substrate. Determining this sufficient level of partial pressure of precursors before or during the coating process is very difficult. This causes a problem: In order to make sure that a sufficient level of precursor partial pressure is provided to the ALD coating process, the amount of precursor supplied through the precursor nozzle has to be more than the surface of the substrate can adsorb. This naturally leads to precursor losses, filter blockages and ultimately breakdowns of vacuum pumps as excess precursors are purged out of the process and then form so-called residual growth into the parts downstream of the coating section of the ALD tool. Residual growth into the vacuum pumps is especially harmful as it can break down the valuable pump.
An object of the present invention is to provide an apparatus and a method for circulating at least one precursor in the apparatus such that at least part of the precursor supplied through a nozzle head is circulated back to the precursor supply to the nozzle head.
The objects of the invention are achieved by an apparatus and a method which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on the idea of circulating at least part of the precursor supplied from the nozzle head toward the surface of the substrate back to a precursor nozzle through a discharge nozzle. The invention relates to an apparatus for subjecting a surface of a substrate to alternate surface reactions of at least two precursors according to principles of atomic layer deposition.
The apparatus according to the invention comprises a nozzle head having an output face via which the at least one precursor is supplied towards the surface of the substrate. The nozzle head comprises at least one precursor nozzle provided on the output face of the nozzle head and comprising a supply channel for supplying precursor towards the surface of the substrate via the output face; and at least one discharge nozzle provided on the output face of the nozzle head and comprising a discharge channel for discharging precursor from the output face. The apparatus further comprises a supply line for supplying precursor from a precursor source to the at least one precursor nozzle. The supply line is connected to the precursor nozzle and being in a fluid communication with the supply channel of the precursor nozzle; and a discharge line for discharging precursor and generating a discharge flow from the output face. The discharge line is connected to the discharge nozzle and being in a fluid communication with the discharge channel of the discharge nozzle.
The supply channel is provided in the precursor nozzle preferably such that it comprises an opening in the output face of the nozzle head. The supply line and the supply channel are in fluid communication and in some embodiments of the invention the supply line may even be provided as the supply channel meaning that the supply line and the supply channel are the same. In some embodiments of the invention the supply line is provided at least partly outside of the nozzle head and extending between a precursor source and the nozzle head or between the precursor source and the precursor nozzle or between the precursor source and the supply channel in the precursor nozzle.
The discharge channel in the discharge nozzle is preferably provided in the nozzle head such that the discharge channel comprises an opening in the output face of the nozzle head. The discharge line and the discharge channel are in fluid communication and in some embodiments of the invention the discharge line and the discharge channel may even be provided as one discharge channel meaning that the discharge line and the discharge channel are the same. In some embodiments of the invention the discharge line is provided at least partly outside the nozzle head and extending between the discharge nozzle in the nozzle head and the supply line or between the discharge channel in the discharge nozzle and the supply line. In other words, the discharge line is connected to the supply line for circulating precursor in the nozzle head by returning at least part of the discharge flow from the output face of the nozzle head via the discharge channel of the discharge nozzle to the supply channel of the precursor nozzle as a circulation flow. The discharge flow is a flow that is generated from an excess precursor that is left over when the surface of the substrate is applied with the precursor supplied from the precursor nozzle and which is discharged from the output face of the nozzle head to the discharge channel in the discharge nozzle and the circulation flow is the part of the discharge flow that is returned from the discharge line to the supply line to be supplied through the supply channel of the precursor nozzle again.
In an embodiment of the invention the nozzle head comprises at least two precursor nozzles provided on the output face of the nozzle head such that at least one first precursor nozzle is arranged to supply a first precursor and at least one second precursor nozzle is arranged to supply a second precursor. The apparatus then comprises a first supply line for supplying the first precursor from a first precursor source to the at least one first precursor nozzle and a second supply line for supplying the second precursor from a second precursor source to the at least one second precursor nozzle. The first supply line is connected to the first precursor nozzle and being in a fluid communication with the supply channel of the first precursor nozzle and the second supply line is connected to the second precursor nozzle and being in a fluid communication with the supply channel of the second precursor nozzle. The apparatus further comprises a first discharge line for discharging the first precursor and generating a discharge flow from the output face and a second discharge line for discharging the second precursor and generating a discharge flow from the output face. The first discharge line is connected to the first discharge nozzle and being in a fluid communication with the discharge channel of the first discharge nozzle and the second discharge line is connected to the second discharge nozzle and being in a fluid communication with the discharge channel of the second discharge nozzle. The first discharge line is connected to the first supply line for circulating the first precursor in the nozzle head by returning at least part of the discharge flow of the first precursor from the output face of the nozzle head via the discharge channel of the first discharge nozzle to the first supply channel of the first precursor nozzle as a circulation flow, and the second discharge line is connected to the second supply line for circulating the second precursor in the nozzle head by returning at least part of the discharge flow of the second precursor from the output face of the nozzle head via the discharge channel of the second discharge nozzle to the supply channel of the second precursor nozzle as a circulation flow. In other words, this embodiment of the invention comprises at least two precursor circulations in the apparatus such that the first precursor is circulated in a first precursor loop and the second precursor is circulated in a second precursor loop. Said first precursor loop comprises the first supply line, the supply channel of the first precursor nozzle, the discharge channel of the first discharge nozzle and the first discharge line and said second precursor loop comprises the second supply line, the supply channel of the second precursor nozzle, the discharge channel of the second discharge nozzle and the second discharge line.
In another embodiment of the invention the nozzle head comprises at least two discharge nozzles and at least one precursor nozzle such that one precursor nozzle is provided between two discharge nozzles. The apparatus then comprises at least two discharge lines for discharging precursor and generating a discharge flow from the output face. The at least two discharge lines being connected to the discharge nozzles provided on opposite sides of the precursor nozzle and being in a fluid communication with the discharge channels of the discharge nozzles. The discharge lines are connected to the supply line for circulating precursor in the nozzle head by returning at least part of the discharge flow from the output face of the nozzle head via the discharge channels of the discharge nozzles to the supply channel of the precursor nozzle as circulation flows. In other words, the apparatus comprises at least two loops for circulating at least part of the discharge flow from the output face of the nozzle head through at least two discharge lines to the same supply line as two separate circulation flows.
In an embodiment of the invention the discharge line comprises at least one of the following: a pump for circulating a discharge flow and/or a circulation flow; a first filter for filtering the discharge flow or the circulation flow; a first mass flow controller for regulating the circulation flow to the supply line or for regulating the ratio of the circulation flow divided from the discharge flow to the supply line; or a coupling with an exhaust ventilation for connecting the discharge line to the exhaust ventilation.
In another embodiment of the invention the discharge line comprises a first mass flow controller and a filter provided upstream side of the mass flow controller. In another embodiment of the invention the discharge line comprises a first mass flow controller and a pump provided upstream side of the mass flow controller. In another embodiment of the invention the discharge line comprises a first mass flow controller, a pump and a first filter such that said pump is provided upstream side of the mass flow controller and said first filter is provided upstream side of the pump. In another embodiment of the invention the discharge line comprises a first mass flow controller, a pump, a first filter and a second filter such that said second filter is provided upstream side of the mass flow controller, said pump is provided upstream side of the second filter and said first filter is provided upstream side of the pump.
In an embodiment of the invention the supply line comprises a second mass flow controller for regulating precursor flow from the precursor source. The second mass flow controller is provided in the supply line between the precursor source and the connection of the discharge line to the supply line.
In an embodiment of the invention the discharge line is connected to the supply line with a first coupling and to an exhaust ventilation with a second coupling, and the first mass flow controller is provided in the discharge line between the first coupling and the second coupling. In other words, the first mass flow controller is provided in the discharge line to regulate the circulation flow which is the part of the discharge flow that is separated in the second coupling in which part of the discharge flow is directed to the exhaust ventilation and part of the discharge flow is circulated back to the precursor nozzle as a circulation flow.
The invention further relates to a method for circulating precursor in an apparatus for subjecting a surface of a substrate to alternate surface reactions of at least two precursors according to the principles of atomic layer deposition in which the apparatus comprises a nozzle head having an output face and at least one precursor nozzle and at least one discharge nozzle provided on the output face. The method according to the invention comprises the steps of supplying precursor from the precursor nozzle via the output face toward the surface of the substrate as a precursor flow; discharging precursor from the output face through the discharge nozzle as a discharge flow; and returning at least part of the discharge flow from the discharge nozzle to the precursor nozzle as a circulation flow. In other words, the precursor supplied from the precursor nozzle toward the surface of the substrate is the precursor flow for coating the surface of the substrate and an excess precursor that is left over and discharged from the output face to the discharge nozzle is the discharge flow. The part of the discharge flow that is returned back to the precursor nozzle is the circulation flow. The method in other words comprises steps of supplying a precursor flow from a precursor nozzle, discharging a discharge flow via a discharge nozzle and returning a circulation flow from the discharge nozzle back to the precursor nozzle.
The discharge flow comprises the excess precursor gas that is left over when the surface of the substrate is subjected to surface reactions and it may also comprise purge gas which is used as a barrier gas or for flushing. The circulation flow comprises precursor gas which is filtered and/or otherwise purified and/or from which part of is directed to exhaust ventilation.
The apparatus comprises a supply line extending from a precursor source to a precursor channel in the precursor nozzle and a discharge line extending from the discharge nozzle to the supply line and the method further comprises the step of circulating the at least part of the discharge flow through the discharge line to the supply line as the circulation flow.
In an embodiment of the invention the method further comprises the step of dividing the discharge flow to the circulation flow and an exhaust flow. Said circulation flow is returning to the supply line as part of the precursor flow and the exhaust flow is directed to the exhaust ventilation. In other words, the method further comprises the step of leading the circulation flow to the supply line as part of the precursor flow. The method further comprises the step of leading part of the discharge flow as an exhaust flow to the exhaust ventilation.
In an embodiment of the invention the apparatus further comprises a first mass flow controller provided in the discharge line and the method further comprises the step of regulating the circulation flow to the supply line by the first mass flow controller; or regulating the ratio of the circulation flow divided from the discharge flow to the supply line by the first mass flow controller.
In an embodiment of the invention the apparatus further comprises a first filter provided in the discharge line and the method further comprises the step of filtering the circulation flow upstream of the supply line.
In an embodiment of the invention the apparatus further comprises a second mass flow controller provided in the supply line and the method further comprises the step of regulating the precursor flow supplied from the precursor source with the second mass flow controller.
In an embodiment of the invention the nozzle head comprises at least two precursor nozzles and at least two discharge nozzles provided on the output face of the nozzle head and the method comprises the steps of supplying a first precursor from a first precursor nozzle via the output face toward the surface of the substrate as a first precursor flow; supplying a second precursor from a second precursor nozzle via the output face toward the surface of the substrate as a second precursor flow; discharging the first precursor from the output face through a first discharge nozzle as a first discharge flow; discharging the second precursor from the output face through a second discharge nozzle as a second discharge flow; returning at least part of the first discharge flow through the first discharge nozzle to the first precursor nozzle as a first circulation flow; and returning at least part of the second discharge flow through the second discharge nozzle to the second precursor nozzle as a second circulation flow.
In the apparatus according to the invention, the apparatus comprises a nozzle head having an output face via which the at least one precursor is supplied towards the surface of the substrate, said nozzle head comprising at least one precursor nozzle provided on the output face of the nozzle head and comprising a supply channel for supplying precursor towards the surface of the substrate via the output face, and at least one discharge nozzle provided on the output face of the nozzle head and comprising a discharge channel for discharging precursor from the output face. The apparatus further comprises a supply line for supplying precursor from a precursor source to the at least one precursor nozzle and a discharge line for discharging precursor and generating a discharge flow from the output face. The supply line is connected to the precursor nozzle and is in a fluid communication with the supply channel of the precursor nozzle and the discharge line is connected to the discharge nozzle and is in a fluid communication with the discharge channel of the discharge nozzle. The supply line is extending from the precursor source to the precursor channel in the precursor nozzle and the discharge line is extending from the discharge nozzle to the supply line such that the discharge line is connected to the supply line for circulating precursor in the nozzle head by returning at least part of the discharge flow from the output face of the nozzle head via the discharge channel of the discharge nozzle to the supply channel of the precursor nozzle. In other words, the discharge line and the supply line are connected together for circulating the precursor in the nozzle head. In still other words, the supply line is arranged to extend from the precursor source to the precursor channel in the precursor nozzle in the nozzle head and the discharge line is connected to the supply line between the precursor source and the nozzle head. Therefore the connection between the supply line and the discharge line is in the apparatus between the precursor source and the nozzle head such that the discharge line is not extending to the precursor source nor to the nozzle head but to the supply line extending between the precursor source and the nozzle head.
In the method according to the invention, the method comprises the steps of supplying precursor from a precursor nozzle in a nozzle head via an output face toward a surface of a substrate as a precursor flow, discharging precursor from the output face through a discharge nozzle in the nozzle head as a discharge flow; and returning at least part of the discharge flow from the discharge nozzle to the precursor nozzle as a circulation flow by circulating the at least part of the discharge flow through a discharge line to a supply line as the circulation flow. The step of returning at least part of the discharge flow from the discharge nozzle to the precursor nozzle is provided through a discharge line extending from the discharge nozzle to the supply line which the supply line is extending from a precursor source to a precursor channel in the precursor nozzle in the nozzle head. In other words, the discharge line is connected to the supply line extending between the precursor source and the nozzle head.
The method described above can be utilized with the apparatus as described above.
An advantage of the invention is that precursor supplied from a precursor source to the apparatus is more effectively used because it can be partly reused again. The loss of precursor can be reduced when the excess precursor is returned back to the precursor nozzle by discharging the precursor via the discharge nozzle to the precursor nozzle. The excess precursor is the part of the precursor which is left over when the surface of the substrate is coated with precursor and the amount of precursor supplied from the precursor nozzle toward the surface of the substrate is more than needed for the surface reactions.
The invention is described in detail by means of specific embodiments with reference to the enclosed drawings, in which
The mass flow controllers disclosed in this application are for regulating the precursor supply from the precursor source, the circulation flow returning to the supply line or the ratio of the circulation flow divided from the discharge flow. The mass flow controllers measure and control the precursor flow from the precursor source and the circulation flow in the discharge line 400. The first mass flow controller 460 provided in the discharge line 400 controls the amount of precursor flowing in the loop formed of the supply line 300 and the discharge line 400 connected to the supply line 300. When the amount precursor provided in the loop decreases more precursor is supplied from the precursor source 330 which the supply is regulated by the second mass flow controller 360. The discharge flow generated from the output face 2 of the nozzle head 1 may comprise purge gas meaning that the precursor content in the discharge flow will reduce and therefore part of the discharge flow may be exhausted through exhaust ventilation 480 and the amount exhaust through the exhaust ventilation will be replaced by new precursor from the precursor source regulated by the second mass flow controller 360.
As shown in
The
The circulation flow CF is either a part of the discharge flow DF that is not lead to an exhaust ventilation 480 as an exhaust flow EF, or the discharge flow DF that is filtered with a filter 420 or the part of the discharge flow that is not lead to an exhaust ventilation 480 as an exhaust flow EF and that is filtered with a filter 420. The discharge line 400 may comprise a filter before the coupling to the exhaust ventilation 480 and/or after the coupling to the exhaust ventilation 480 meaning that the method may comprise the steps of filtering the discharge flow DF and/or filtering the circulation flow CF.
In the embodiment of the invention shown in
In another embodiment of the invention shown in
In an embodiment shown in
The invention has been described above with reference to the examples shown in the figures. However, the invention is in no way restricted to the above examples but may vary within the scope of the claims.
Number | Date | Country | Kind |
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20185358 | Apr 2018 | FI | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FI2019/050300 | 4/15/2019 | WO | 00 |