Method and apparatus for cleaning a reaction chamber

Abstract

The present disclosure relates to methods and apparatus for cleaning a reaction chamber. A method for cleaning a reaction chamber (110) of a substrate processing apparatus (100) and a substrate processing apparatus (100) wherein a cleaning gas is provided from a cleaning gas source (190), a first cleaning gas stream is supplied into the reaction chamber (110) through a first inlet (120) and a second cleaning gas stream is supplied into the reaction chamber (110) through a second inlet (180) for etching the reaction chamber, wherein the first cleaning gas stream and the second cleaning gas stream enter the reaction chamber (110) from different directions, and wherein the cleaning gas is activated prior to the etching.

Description

Technical Field

[0001] The present disclosure generally relates to cleaning of substrate processing equipment. The present disclosure particularly (but not limited to) relates to cleaning of reaction chambers. Background Art

[0002] This section provides useful background information, but does not constitute an admission that any of the techniques described herein represent prior art.

[0003] In various substrate processing devices, various chemicals are supplied into the reaction chamber. During use, the chemicals may accumulate on the reaction chamber walls, and the accumulated chemicals may contaminate the chemical reaction or processing on the substrate. The residues and contaminants of the previously introduced chemicals should be removed from the reaction chamber as effectively as possible to maintain the reaction quality. Summary of the invention

[0004] It is an object of certain embodiments of the present invention to provide a method and apparatus for improving the cleaning of a reaction chamber.

[0005] The attached claims define the scope of protection. Any examples and technical descriptions of devices, products and / or methods in the specification and / or drawings that are not covered by the claims are not presented as embodiments of the present invention, but are presented as background technology or examples to help understand the present invention.

[0006] According to a first exemplary aspect, there is provided a method for cleaning a reaction chamber of a substrate processing apparatus, comprising:

[0007] providing a clean gas from a clean gas source;

[0008] Supplying a first cleaning gas flow into the reaction chamber through a first inlet and supplying a second cleaning gas flow into the reaction chamber through a second inlet for etching the reaction chamber, wherein the first cleaning gas flow and the second cleaning gas flow enter the reaction chamber from different directions; and

[0009] The cleaning gas is activated prior to the etching.

[0010] Thus, in some embodiments, the first cleaning gas flow enters the reaction chamber from one direction (or position), and the second cleaning gas flow enters the reaction chamber from another direction (or position). In some embodiments, the first cleaning gas flow enters the reaction chamber from the top (or top section) of the reaction chamber, and the second cleaning gas flow enters the reaction chamber from the bottom (or bottom section) of the reaction chamber or from the substrate support.

[0011] In some embodiments, the activating comprises decomposing the cleaning gas with a plasma. In some embodiments, the activating comprises forming a plasma from the cleaning gas.

[0012] In certain embodiments, the activating includes at least one of decomposing the cleaning gas with the plasma and forming the plasma from the cleaning gas.

[0013] In some embodiments, the method includes simultaneously supplying the cleaning gas into the reaction chamber through the first inlet and the second inlet. Advantageously, injecting the cleaning gas through two opposing inlets can improve the distribution of the cleaning gas in the reaction chamber.

[0014] In certain embodiments, the method includes sequentially supplying a cleaning gas into the reaction chamber through the first inlet and the second inlet. Advantageously, cleaning can be focused sequentially on different components of the reaction chamber.

[0015] In some embodiments, the cleaning gas is a fluorine-based gas. In some embodiments, the cleaning gas is NF3. In some embodiments, the fluorine-based cleaning gas is selected from the group consisting of NF3, SF6, CF4, CHxFy and F2. In some embodiments, the fluorine-based cleaning gas is selected from but not limited to the group consisting of NF3, SF6, CF4, CHxFy and F2. Advantageously, when activated with plasma, the fluorine-based gas decomposes into atomic fluorine gas and other reactive byproducts, which are willing to react with almost all materials. Therefore, effective reaction chamber cleaning can be achieved.

[0016] In certain embodiments, the cleaning gas of the first cleaning gas flow is different than the cleaning gas of the second cleaning gas flow. Advantageously, different combinations of cleaning gases may be used.

[0017] In some embodiments, the second inlet is a substrate backside protection channel. In some embodiments, the second clean gas flow enters the reaction chamber from below through the substrate support. In some embodiments, the second clean gas flow enters the reaction chamber from below through the interior of the substrate support. Therefore, in some embodiments, the supply of the second clean gas flow through the second inlet includes supplying the second clean gas flow through the substrate support (or through the interior of the substrate support). Advantageously, the existing structure of the substrate processing device can be used to deliver the clean gas to the reaction chamber, and the need for structural modification can be alleviated.

[0018] In some embodiments, the first inlet and the second inlet are opposite to each other. In some embodiments, the first cleaning gas flow enters the reaction chamber through the top of the reaction chamber via the first inlet, and the second cleaning gas flow enters through the bottom of the reaction chamber via the second inlet opposite to the first inlet. Advantageously, the reverse flow of the cleaning gas improves the gas distribution in the reaction chamber. Therefore, less cleaning gas may be required.

[0019] In some embodiments, at least one of the two inlets is also used to supply reactive chemicals during substrate processing. Advantageously, the same structure of the substrate processing apparatus can be used for substrate processing and cleaning processing.

[0020] In some embodiments, the method includes repeating the method a predetermined number of times. Advantageously, by repeating the method, the cleaning efficacy can be improved. In some embodiments, changing the cleaning parameters of each repeated cycle can also improve the cleaning efficacy.

[0021] In some embodiments, the method includes:

[0022] The cleaning gas is activated with plasma formed in a separate plasma forming unit (remote or separate from the reaction chamber).

[0023] In some embodiments, the method includes:

[0024] The cleaning gas is activated with plasma formed in a plasma forming unit integrated into the reaction chamber.

[0025] In some embodiments, the method includes:

[0026] The cleaning gas of the first cleaning gas flow and the cleaning gas of the second cleaning gas flow are activated with plasma formed in a single plasma forming unit.

[0027] In some embodiments, the method includes:

[0028] The plasma for activating the cleaning gas and the plasma for substrate processing are formed in the same (preferably integrated) plasma forming unit.

[0029] In certain embodiments, the duration of the first cleaning gas flow and the second cleaning gas flow are independently controlled. Advantageously, the combined cleaning gas flow can be directed more accurately to certain components of the reaction chamber, such as the top component or components that are difficult to clean with conventional solutions. The different durations can allow the direction of the cleaning gas flow to be changed during the cleaning process and the focus area of ​​cleaning inside the reaction chamber to be changed.

[0030] In some embodiments, the flow rates of the first cleaning gas stream and the second cleaning gas stream are independently controlled. Advantageously, the combined cleaning gas stream can be more accurately directed to certain components of the reaction chamber, such as the top component or components that typically experience contamination that is more difficult to clean.

[0031] In some embodiments, the method includes:

[0032] By controlling the duration and / or flow rate of the first cleaning gas flow and the second cleaning gas flow, the cleaning gas flows are targeted to the interior of the reaction chamber. Advantageously, the highest cleaning gas dose can be targeted to the most heavily contaminated components in the reaction chamber.

[0033] In certain embodiments, the duration of the first cleaning gas flow is equal to the duration of the second cleaning gas flow. Advantageously, the cleaning gas may be effectively delivered from two opposite directions to improve gas distribution inside the reaction chamber.

[0034] In certain embodiments, the flow rate of the first cleaning gas flow is equal to the flow rate of the second cleaning gas flow. Advantageously, the cleaning gases can be effectively delivered from two opposite directions to improve gas distribution inside the reaction chamber.

[0035] According to a second exemplary aspect, there is provided a substrate processing apparatus, comprising:

[0036] Reaction chamber;

[0037] a first inlet for supplying a cleaning gas as a first cleaning gas flow from a cleaning gas source into the reaction chamber;

[0038] a second inlet for supplying a cleaning gas as a second cleaning gas flow from a cleaning gas source into the reaction chamber from a direction different from the supply direction of the first cleaning gas flow; and

[0039] A plasma forming unit is configured to activate a cleaning gas for etching the reaction chamber.

[0040] In certain embodiments, the plasma forming unit is configured to activate the cleaning gas by at least one of decomposing the cleaning gas with the plasma and forming the plasma from the cleaning gas.

[0041] In some embodiments, the plasma forming unit is an integrated plasma forming unit integrated into the reaction chamber (for forming plasma to activate the cleaning gas inside the reaction chamber). Advantageously, the same integrated plasma forming unit used for plasma formation during substrate processing can also be used to form plasma to activate the cleaning gas during cleaning processing.

[0042] In some embodiments, the substrate processing apparatus includes a remote plasma forming unit for forming a plasma to activate the cleaning gas before supplying the cleaning gas to the reaction chamber. In some embodiments, the cleaning gas flow from the first inlet and the second inlet already contains the plasma activated cleaning gas when entering the reaction chamber. Therefore, etching is effectively targeted to the flow direction.

[0043] In some embodiments, the first inlet line and the second inlet line are opposite to each other. In some embodiments, the apparatus is configured to route the first clean gas flow through the top of the reaction chamber (or through the top member), and to route the second clean gas flow through the substrate support. In some embodiments, the first clean gas flow causes a flow from top to bottom within the reaction chamber, and the second clean gas flow is a flow from bottom to top. Thus, in some embodiments, the apparatus is configured to diffuse the first clean gas flow laterally with the second clean gas flow in the reaction chamber.

[0044] In certain embodiments, the substrate processing apparatus is configured to simultaneously supply a first cleaning gas flow and a second cleaning gas flow into the reaction chamber.

[0045] In certain embodiments, the substrate processing apparatus is configured to sequentially supply a first cleaning gas flow and a second cleaning gas flow into the reaction chamber.

[0046] In some embodiments, the cleaning gas is a fluorine-based gas. In some embodiments, the cleaning gas is NF3. In some embodiments, the fluorine-based cleaning gas is selected from the group consisting of NF3, SF6, CF4, CHxFy, and F2. In some embodiments, the fluorine-based cleaning gas is selected from the group including but not limited to NF3, SF6, CF4, CHxFy, and F2.

[0047] In certain embodiments, the cleaning gas of the first clean gas flow (from the first inlet line) is different than the cleaning gas of the second clean gas flow (from the second inlet line).

[0048] In some embodiments, the second inlet is a substrate backside protection channel.

[0049] Different non-binding example aspects and embodiments have been described above. The foregoing embodiments are only used to explain selected aspects or steps that can be used in different implementations. Some embodiments may be presented with reference to only certain example aspects. It should be understood that the corresponding embodiments may also be applied to other example aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Some example embodiments will be described with reference to the accompanying drawings, in which:

[0051] Figure 1 shows a cross-sectional view of a substrate processing apparatus according to an example embodiment;

[0052] Figure 2 shows another cross-sectional view of a substrate processing apparatus according to an example embodiment; and

[0053] Figure 3 A flow chart according to an example embodiment is shown. DETAILED DESCRIPTION

[0054] In the following description, the same reference numerals denote the same elements or steps.

[0055] In the following description, atomic layer deposition (ALD) technology is used as an example. However, the present invention is not limited to ALD technology, but can be used in a variety of substrate processing devices, for example, in a chemical vapor deposition (CVD) reactor, or in an etching reactor, such as an atomic layer etching (ALE) reactor.

[0056] The basic principles of the ALD growth mechanism are known to the skilled person. ALD is a special chemical deposition method based on the sequential introduction of at least two reactive precursor species, usually to at least one substrate. However, it should be understood that when using, for example, photon enhanced ALD or plasma assisted ALD (e.g., PEALD), one of these reactive precursors can be energetically replaced, resulting in a single precursor ALD process. Thin films grown by ALD are dense, pinhole-free, and have uniform thickness.

[0057] As for the substrate processing step, at least one substrate is typically exposed to temporarily separated precursor pulses in a reaction vessel to deposit material on the substrate surface by a continuous self-saturating (or self-limiting) surface reaction. In the context of this application, the term ALD includes all applicable ALD-based techniques and any equivalent or closely related techniques, such as MLD (molecular layer deposition).

[0058] During substrate processing, an accumulation of undesirable reactive chemicals may occur inside the reaction chamber. In order to maintain the quality of the chemical processing, the reaction chamber should be effectively cleaned. The reaction chamber can be cleaned by etching.

[0059] For example, nitrogen trifluoride NF3 is a chamber cleaning gas widely used in substrate processing equipment. When activated with a plasma generated by a plasma forming (or activation) unit, the NF3 molecule decomposes into atomic fluorine gas and other reactive byproducts, which are willing to react with almost all materials. The plasma of the activated NF3 gas can be, for example, an argon or nitrogen plasma, which then decomposes the NF3 molecule. Additionally or alternatively, the activation of NF3 can include using NF3 as a plasma precursor and generating plasma from NF3. That is, the activated cleaning gas includes at least one of decomposing the cleaning gas with plasma and forming a plasma from the cleaning gas. NF3 plasma can be used to decompose the NF3 cleaning gas, or to etch a reaction chamber. Other fluorine compounds other than NF3 can also be used. In general, the fluorine compounds of many materials are volatile, and therefore gaseous fluorine chemicals can be used as a cleaning agent for etching solid materials from the surface of the chamber.

[0060] In some embodiments, the cleaning gas is a fluorine-based gas. In some embodiments, the cleaning gas is NF3. In some embodiments, the fluorine-based cleaning gas is selected from the group consisting of NF3, SF6, CF4, CHxFy, and F2. In some embodiments, the fluorine-based cleaning gas is selected from the group including but not limited to NF3, SF6, CF4, CHxFy, and F2.

[0061] However, a major challenge is the diffusion of the active fluorine species or cleaning gas plasma within the reaction chamber. If the active fluorine compound or plasma does not reach all parts of the reaction chamber, the etching rate can be very different at different locations on the reaction chamber surface. If the dose of the active fluorine species and the cleaning gas plasma at the reaction chamber surface varies greatly, it can cause the chamber cleaning step to require a large amount of etching time. Therefore, the reaction chamber surface location that experiences the lowest dose (determined by partial pressure × time) of the active cleaning gas species during the etching step determines the shortest time required for chamber cleaning. It is desirable to use a minimum amount of fluorine-based cleaning gas in the etching step. The present disclosure, among other things, addresses the above-mentioned problems.

[0062] Figure 1 1 shows an apparatus according to some embodiments. Apparatus 100 is a substrate processing apparatus, such as an ALD, ALE or CVD reactor. Apparatus 100 includes a reaction chamber 110 and a first inlet 120. Reaction chemicals and a first cleaning gas flow can be supplied to reaction chamber 110 through first inlet 120. Figure 1 In some embodiments, the first inlet 120 comprises a plurality of inlet holes in a ceiling of the reaction chamber 110. In some embodiments, the reactant gas and the precursor are supplied to the reaction chamber 110 through the plurality of inlet holes of the first inlet 120, as shown by the plurality of arrows depicting the flow of reactants to the reaction chamber 110, to improve the distribution of the gas supplied to the reaction chamber 110. In some embodiments, the first inlet 120 comprises a showerhead.

[0063] In some embodiments, the apparatus includes an outer chamber 115. The outer chamber 115 at least partially surrounds the reaction chamber 110. An intermediate volume 135 is formed between the outer wall of the reaction chamber 110 and the interior of the wall of the outer chamber 115. In some embodiments, during cleaning, the pressure in the intermediate volume 135 is maintained higher than the pressure in the reaction chamber 110, for example, to prevent leakage from the reaction chamber 110. For example, during the cleaning process, the pressure in the intermediate volume 135 can be 4 hPa, and the pressure in the reaction chamber is less than 2 hPa.

[0064] A plurality of plasma antennas 125 are located downstream of the inlet hole of the first inlet 120. In some embodiments, the plasma antenna is used to form plasma from a plasma precursor, which is supplied through the first inlet 120. In some embodiments, the plasma antenna is used to form plasma from a plasma precursor for activating a NF3 cleaning gas flow for cleaning steps and substrate processing. NF3 is used as an exemplary cleaning gas herein, but other fluorine-based cleaning gases are also possible. The plasma can be, for example, an argon plasma or a nitrogen plasma. In some embodiments, the plasma antenna is used to form plasma from a NF3 cleaning gas. Therefore, activating the cleaning gas includes decomposing the cleaning gas with a plasma and forming at least one of a plasma from the cleaning gas.

[0065] Plasma antenna 125 can emit electromagnetic radiation and / or form electric field and / or magnetic field around it. Plasma is formed around and on the surface of plasma antenna 125, but can also diffuse into reaction chamber. Therefore, NF3 plasma can be used for NF3 cleaning gas activation and / or chamber etching. A first cleaning gas flow of NF3 is provided from cleaning gas source 190. Plasma precursor flow is provided from plasma precursor source 195. In certain embodiments, plasma precursor flow is used for both chamber cleaning and substrate processing operation. In certain embodiments, the first cleaning gas flow and plasma precursor flow enter reaction chamber 110 through first inlet 120. Cleaning gas (second cleaning gas flow) can also enter reaction chamber 110 via substrate back side protection channel 180.

[0066] In some embodiments, the reaction chamber 110 is a cylinder with a rounded bottom. Generally, the horizontal cross-section of the reaction chamber is circular. The reaction chamber 110 is a vertical flow reaction chamber, which means that the gas flow in the reaction chamber 110 generally occurs from top to bottom. The gas is exhausted through the outlet 160 connected to the vacuum pump 170.

[0067] First inlet 120 is coupled to (or forms part of) a top member 130 of reaction chamber 110. In some embodiments, top member 130 is configured to operate as a lid, or top member 130 includes a lid that can be opened for loading a substrate 140 (such as a wafer) or a plurality of substrates 140 onto substrate support 150, or for removing a substrate(s) from reaction chamber 110. In some embodiments, top member 130 is removable, while in other embodiments, reaction chamber bowl 210, i.e., a lower member of reaction chamber 110, can be lowered to load or remove a substrate. In some alternative embodiments, a door is formed on one side of reaction chamber 110 to load or remove substrate(s) 140.

[0068] The substrate support 150 is centrally located in a horizontal direction or in all horizontal directions. In some embodiments, the substrate support 150 is attached to a wall of the reaction chamber 110. In some embodiments, the substrate support 150 stands on support legs 230 inside the reaction chamber 110. In alternative embodiments, the substrate support 150 is suspended from the lid 130.

[0069] In some embodiments, a second inlet 180 for the cleaning gas to enter the reaction chamber 110 is arranged in a connection to the substrate support 150 from below. The second inlet 180 supplies a second cleaning gas flow to the reaction chamber 110. In some embodiments, the second inlet 180 enters the reaction chamber 110 from a different direction than the first inlet 120. That is, the first cleaning gas flow from the first inlet 120 and the second cleaning gas flow from the second inlet 180 are at least partially directed to different directions. In some embodiments, the first inlet 120 and the second inlet 180 are opposite to each other. In some embodiments, the first cleaning gas flow and the second cleaning gas flow from the first inlet 120 and the second inlet 180, respectively, are at least partially directed to opposite directions. In some embodiments, the first inlet 120 and the second inlet 180 are positioned so that the first cleaning gas flow and the second cleaning gas flow are at least partially directed to each other.

[0070] In some embodiments, the cleaning gas arriving at the second inlet 180 passes through the support leg(s) 230 of the substrate support 150 and the substrate support 150 into the reaction chamber 110. Like the first inlet 120, the second inlet 180 is connected to a cleaning gas source 190. In some embodiments, the first cleaning gas flow and the second cleaning gas flow are provided from the same cleaning gas source 190.

[0071] In some embodiments, the apparatus 100 includes more than one cleaning gas source 190. In some embodiments, the first inlet 120 and the second inlet 180 are connected to separate cleaning gas sources 190. In some embodiments, the cleaning gas of the first cleaning gas flow is different from the cleaning gas of the second cleaning gas flow.

[0072] exist Figure 1 In an embodiment of the present invention, the second inlet 180 is a substrate backside protection channel (or forms a part thereof). The backside protection channel 180 is a gas channel located in the substrate support (or substrate holder assembly) 150. During substrate processing, the backside protection channel 180 supplies an inert gas from below the substrate 140 to prevent reactions from occurring on the back side of the substrate 140. That is, in addition to its normal substrate processing function, the backside protection channel can be used as the second inlet 180. When chamber cleaning is performed, the substrate 140 is not in the reaction chamber 110, so that the substrate 140 does not block the flow of the second cleaning gas into the reaction chamber 110.

[0073] In accordance with Figure 1 In some embodiments, during chamber cleaning, the first inlet 120 and the second inlet 180 supply cleaning gas to the reaction chamber 110 as a first cleaning gas flow and a second cleaning gas flow, respectively. For example, during a pre-deposition or post-deposition step during processing of the substrate (one or more) 140, the chamber cleaning can be performed. The second inlet 180 is located opposite the first inlet 120 and is arranged to provide a second cleaning gas flow to enter the reaction chamber 100 from below and through the substrate support 150. The opposite first inlet 120 and the second inlet 180 provide the opposite first cleaning gas flow and the second cleaning gas flow, respectively. The opposite first cleaning gas flow and the second cleaning gas flow are at least partially directed in opposite directions. In some embodiments, the first cleaning gas flow and the second cleaning gas flow are at least partially directed to each other. In some embodiments, NF3 is injected into the reaction chamber 110 from both the top and the bottom. That is, the NF3 cleaning gas is routed from the cleaning gas source 190 through both the first inlet 120 and the second inlet 180, and is injected into the reaction chamber 110 from the two opposite inlets 120, 180.

[0074] In some embodiments, the cleaning gas is injected simultaneously from two inlets entering the reaction chamber from different directions. Therefore, the first inlet and the second inlet flow at least partially point to different directions. In some embodiments, the two inlets include the first inlet 120 and / or the substrate backside protection channel 180. In some embodiments, the first inlet 120 and the second inlet 180 are opposite to each other. The first inlet 120 and the second inlet supply the first cleaning gas flow and the second cleaning gas flow to the reaction chamber 110 from different directions, respectively.

[0075] In some embodiments, the cleaning gas is supplied sequentially by alternating between the two inlets 120, 180. In some embodiments, the cleaning gas is first injected from the second inlet 180 (e.g., bottom), and then injected from the first inlet 120 (e.g., top). In some embodiments, the cleaning gas is first injected from the first inlet 120 (e.g., top), and then injected from the second inlet 180 (e.g., bottom). In some embodiments, at least one of the first inlet 120 and the second inlet 180 is located at the side of the reaction chamber 100.

[0076] In some embodiments, the sequential injection cycle is repeated. In some embodiments, the sequential cleaning gas injection cycle is repeated 1, 2, or 3 times. In some embodiments, the same cleaning gas is provided through both the first inlet 120 and the second inlet 180. In some embodiments, different cleaning gases are provided through the first inlet 120 and the second inlet 180.

[0077] Figure 1The arrows in show the flow and diffusion of the cleaning gas. In some embodiments, the NF3 gas from the cleaning gas source 190 is decomposed into atomic fluorine gas and other reaction byproducts by activation with a plasma generated in a separate remote plasma forming unit (not shown). For example, argon plasma or nitrogen plasma can be used to decompose, i.e., activate the cleaning gas. Additionally or alternatively, the activated cleaning gas includes forming a plasma from the cleaning gas. The cleaning gas plasma can activate other cleaning gas molecules by decomposing them, and / or is also used for cleaning the chamber by etching. That is, in some embodiments, the activated cleaning gas flow includes atomic fluorine gas and other reaction byproducts produced by the decomposition of the cleaning gas by plasma treatment. Additionally or alternatively, the activated cleaning gas flow includes a plasma formed by the cleaning gas.

[0078] Then, the first activated clean gas flow is routed to the reaction chamber 110 via the first inlet 120, and the second activated clean gas flow is routed to the reaction chamber 110 via the second inlet 180. In certain embodiments, when using Figure 1 In the plasma enhanced reactor of the embodiment of the present invention, a plasma forming (or activation) unit, such as a plasma antenna 125, is integrated, which activates a plasma precursor during substrate processing, for generating a plasma to activate NF3, or other suitable cleaning gas, for the etching step. That is, the first NF3 cleaning gas flow supplied through the first inlet 120 and the second cleaning gas flow supplied through the second inlet 180 can be activated by the plasma formed by the integrated plasma antenna 125 inside the reaction chamber 110. In this way, in some embodiments, the cleaning gas flows provided by the first inlet 120 and the second inlet 180 are not activated when they first enter the reaction chamber 100, but are activated only after they have reached the area of ​​the plasma antenna 125 inside the reaction chamber 110. However, any way of performing NF3 activation before or after entering the reaction chamber 110 is feasible, because the distribution of the cleaning gas activated by the plasma inside the reaction chamber 110 can be improved anyway due to the two opposite flows. In some embodiments, the plasma for activation is formed by the NF3 cleaning gas. In some embodiments, the first inlet 120 and the second inlet 180 have separate plasma forming units. In some embodiments, the cleaning gas routed through the first inlet 120 is activated by the integrated plasma antenna 125 of the substrate processing apparatus 100, and the cleaning gas routed through the second inlet 180 is activated (forming plasma from the cleaning gas) by a separate (remote) plasma forming (or activation) unit. In some embodiments, only the cleaning gas of the first cleaning gas flow or the cleaning gas of the second cleaning gas flow is plasma activated before entering the reaction chamber 110.

[0079] The simultaneous flow of NF3 from the first inlet 120 and the second inlet 180 improves the distribution of activated NF3 toward the sidewall of the reaction chamber 110. In particular, according to Figure 1 In the embodiment of FIG. 1 , due to the flow of NF 3 from two opposing inlets 120, 180, the gas flow to the top member and top corners of the reaction chamber 110 is improved (at Figure 1 180). In contrast, if only the first inlet 120 is used, the distribution of NF3 to the top member will be significantly weaker, resulting in poorer cleaning of the reaction chamber 110 wall, longer etching time, and greater consumption of cleaning gas. Therefore, by also supplying NF3 through the second inlet 180, the etching gas distribution, etching rate, and cleaning efficacy inside the reaction chamber can be improved. In addition, since the area inside the reaction chamber 110 with a low NF3 dosage can be reduced, the amount of NF3 gas required for etching can be reduced.

[0080] Figure 2 Another cross-sectional view of a substrate processing apparatus according to example embodiments is shown. Figure 2 The reaction chamber 110 of the substrate processing apparatus 100 includes a top member 130 and a lower member, namely a reaction chamber bowl 210. During operation, the top member 130 and the reaction chamber bowl 210 are releasably sealed together by a coupling device 220. To load or remove substrate sample(s) 140, the reaction chamber 210 (along with the substrate support 150) can be lowered to open the reaction chamber 110, while the top member 130 remains stationary.

[0081] lie in Figure 2 The first inlet 120 of the top member 130 of the substrate processing apparatus 100 includes a reactant channel 250 connected to a plurality of reactant inlets 260, a plasma precursor channel 270 connected to a plurality of plasma inlets 280, and a plurality of plasma antennas 125, i.e., an integrated plasma formation (or activation) unit. It should be noted that Figure 2 Only two plasma antennas are shown, but other numbers of plasma antennas are possible. In some embodiments, the plasma antenna 125 used during substrate processing is also used to generate plasma to activate the cleaning gas or form plasma from the cleaning gas for cleaning processing. In some embodiments, the plasma formed from the cleaning gas is used to activate other cleaning gas molecules by decomposition or directly etch the reaction chamber.

[0082] During normal operation, non-plasma reactants (non-plasma precursors) are provided into the reaction chamber 110 via the reactant passage 250 and the reactant inlet 260. Figure 2, the flow of the non-plasma precursor inside the reactant channel 250 toward the reactant inlet 260 is depicted by dashed arrows. The reactant inlet 260 is a channel in the reaction chamber 110 extending from the first inlet ceiling to downstream of the plasma antenna 125. Thus, the non-plasma precursor can be delivered directly to the reaction chamber 110, and undesired contact with the plasma antenna 125 can be minimized.

[0083] For plasma enhanced processing, a plasma precursor is provided via a plasma precursor channel 270 and a plurality of plasma inlets 280 . Figure 2 The first inlet 120 includes a precursor channel 270 and a plurality of plasma inlets 280. A cleaning gas for chamber cleaning is also provided through the plasma precursor channel 270 and the plurality of plasma inlets 280. In some embodiments, the cleaning gas is used as a plasma precursor. The flow of the plasma precursor and / or the cleaning gas in the first inlet 120 and the second inlet 180 is Figure 2 The plasma precursor supplied through the plasma precursor passage 270 and the plasma inlet 280 may come from the plasma precursor source 195 (for normal substrate processing with plasma or for generating plasma for cleaning gas activation), and the cleaning gas may come from the cleaning gas source 190 (for decomposing or forming plasma for chamber cleaning and etching).

[0084] In some embodiments, the plurality of plasma inlets 280 are short channels protruding from the top plate of the first inlet 120, which provide plasma precursors and / or cleaning gases upstream of the plasma antenna 125. In some embodiments, the plasma inlet 280 is presented as a plurality of holes in the top plate of the first inlet 120, which distributes the plasma precursor to the reaction chamber 110 upstream of the plasma antenna 125. That is, the plasma precursor and / or the cleaning gas must pass through the plasma antenna 125 on the way into the reaction chamber 110. Therefore, in some embodiments, the plasma antenna 125 is used to form a plasma from the plasma precursor and / or the cleaning gas to activate the cleaning gas for chamber etching. Additionally or alternatively, the cleaning gas activation includes forming a plasma from the cleaning gas through the plasma antenna 125. In some embodiments, the cleaning gas plasma is used to directly etch the reaction chamber 110 or activate the cleaning gas.

[0085] In an alternative embodiment, a separate (remote) plasma forming unit forms a plasma from the plasma precursor stream(s) to activate, i.e., decompose the first cleaning gas stream and the second cleaning gas stream into reactive species with the plasma before the streams enter the reaction chamber 110. In some embodiments, the remote plasma forming unit also forms a plasma from the cleaning gas, so that the cleaning gas is present as a plasma when entering the reaction chamber 110. In some embodiments, during chamber cleaning, the plasma generated by the plasma antenna 125 also activates the cleaning gas, which is provided via the substrate backside protection channel (second inlet) 180 passing through the substrate support 150. It should be noted that during cleaning, the substrate 140 is not present in the reaction chamber 110 to avoid blocking the second inlet 180 and damaging the substrate 140.

[0086] In some embodiments, the core of the substrate support 150 is hollow. In some embodiments, the second cleaning gas flow is supplied to the reaction chamber through the hollow substrate support 150. That is, the second cleaning gas flow can flow from the cleaning gas source 190 and pass through the substrate support 150 to effectively diffuse upward into the reaction chamber 110. In some embodiments, the second cleaning gas flow enters the reaction chamber 110 through a plurality of substrate support inlet holes 240 located on the substrate support 150 (but in other embodiments, there are fewer holes, and in some embodiments, only a single hole).

[0087] The cleaning gas of the second cleaning gas flow may be activated before or after entering the reaction chamber 110. In some embodiments, the substrate support 150 is supported on the reaction chamber bowl 210 by support legs 230. For example, there may be one, two, three, or four support legs 230. The back protection channel enters the hollow substrate support 150 through one of the support legs 230. In some embodiments, the back protection channel operates as a second inlet 180. In some embodiments, the second cleaning gas flow directly enters the substrate support 150 without passing through the support legs 230 (e.g., through a separate tube extending to the inlet hole (one or more) 240, and the core of the substrate support may be hollow or non-hollow). In some embodiments, the second cleaning gas flow is provided to the hollow substrate support 150, and the second inlet line 180 does not pass through the reaction chamber 110. For example, the second inlet 180 may be directed to a channel inside the support legs 230 or a separate structure so that the second inlet line 180 is not exposed to the reaction chamber 110.

[0088] The substrate support inlet hole(s) 240 direct the cleaning gas upward toward the top of the reaction chamber 110 and the plasma antenna 125, that is, opposite to the first cleaning gas flow provided through the plasma inlet 280 of the first inlet 120. In certain embodiments, the activation (to form a plasma) of the cleaning gas provided via the backside protection channel is performed by the plasma antenna 125. In alternative embodiments, a separate remote plasma formation unit is used to activate the second cleaning gas flow before the second cleaning gas flow enters the reaction chamber 110 through the substrate support 150 and the substrate support inlet hole(s) 240.

[0089] Figure 3 A flow chart according to an example embodiment is shown. Figure 3 The process is illustrated to include various possible steps, including some optional steps, and may also include further steps and / or steps that may be performed multiple times. The process may be performed, for example, Figure 1 or Figure 2 The process is implemented in a substrate processing device 100. The process includes the following steps:

[0090] 310: Provide a clean gas from a clean gas source. The clean gas may be provided from Figure 1 or Figure 2 A cleaning gas source 190 is provided. In some embodiments, the cleaning gas is a fluorine-based gas. In some embodiments, the cleaning gas is NF3. In some embodiments, the fluorine-based cleaning gas is selected from the group consisting of NF3, SF6, CF4, CHxFy and F2. In some embodiments, the fluorine-based cleaning gas is selected from the group including but not limited to NF3, SF6, CF4, ChxFy and F2. In some embodiments, the cleaning gas source 190 includes more than one cleaning gas source. In some embodiments, two different cleaning gases are provided to the first inlet and the second inlet, respectively. In some embodiments, only one type of cleaning gas (e.g., NF3) is provided.

[0091] 320: Cleaning gas is supplied to the reaction chamber 110 from different directions through two inlets 120, 180 for etching the reaction chamber. In some embodiments, the cleaning gas enters the reaction chamber in an unactivated state. In some embodiments, the cleaning gas enters the reaction chamber in an activated, i.e., decomposed state after being treated with plasma. In some embodiments, the cleaning gas enters the reaction chamber 110 as plasma. In some embodiments, the first inlet 120 providing the first cleaning gas flow is a showerhead. In some embodiments, the second inlet 180 providing the second cleaning gas flow is a substrate backside protection channel. In some embodiments, the first inlet 120 and the second inlet 180 are opposite to each other. In some embodiments, the first cleaning gas flow from the first inlet 120 and the second cleaning gas flow from the second inlet 180 are at least partially directed to each other. In some embodiments, the first cleaning gas flow enters the reaction chamber 110 through the top of the reaction chamber 110 via the first inlet 120, and the second cleaning gas flow enters through the bottom of the reaction chamber 110 via the second inlet 180 opposite to the first inlet 120. In some embodiments, the second cleaning gas flow enters from below through substrate support 150. In some embodiments, the first cleaning gas flow is directed downwardly while the second cleaning gas flow is directed upwardly toward the first cleaning gas flow. In some embodiments, at least one of the first cleaning gas flow and the second cleaning gas flow enters reaction chamber 110 from the side.

[0092] 330: Activating the cleaning gas with plasma before etching. In some embodiments, the cleaning gas is plasma activated after having been supplied through two opposing inlets 120, 180. In some embodiments, the cleaning gas is plasma activated before being supplied through the first inlet 120 and the second inlet 180, that is, the cleaning gas enters the reaction chamber 110 in an activated state. In some embodiments, the fluorine-based cleaning gas is activated with plasma generated by a plasma forming unit. In some embodiments, the plasma is an argon plasma or a nitrogen plasma. In some embodiments, the plasma is a plasma from a fluorine-based cleaning gas. In some embodiments, at least one of the first cleaning gas flow and the second cleaning gas flow is activated with plasma before entering the reaction chamber 110.

[0093] The cleaning gas can form a plasma to activate the cleaning gas. In some embodiments, the cleaning gas plasma is used for chamber etching. When activated with plasma, the NF3 molecules decompose into atomic fluorine gas and other reactive byproducts, which can react with almost all materials. Therefore, the NF3 molecules can be used to etch solid materials from the surface of the reaction chamber 110. In some embodiments, the plasma forming unit is a separate plasma unit. In some embodiments, the plasma forming unit is an integrated plasma forming unit of the plasma enhanced substrate processing device 100, such as a plurality of plasma antennas 125. That is, the plasma forming unit used to generate the plasma for cleaning gas activation can be the same plasma forming unit also used for substrate processing.

[0094] 340: The process optionally includes independently controlling the duration and / or flow rate of the first cleaning gas flow and the second cleaning gas flow through the inlets 120, 180. In some embodiments, the cleaning gas is injected simultaneously through two opposing inlets, namely the first inlet 120 and the second inlet 180. In some embodiments, the cleaning gas enters the reaction chamber 110 simultaneously through the first inlet 120 and the second inlet 180. In some embodiments, the duration of the cleaning gas flow through the two inlets is 5 minutes, 10 minutes, 15 minutes, 20 minutes or 30 minutes. In some embodiments, the cleaning gas is injected into the reaction chamber for a total of at least 5 minutes. In some embodiments, the flow duration is determined by a user. In some embodiments, the flow duration is automatically determined and adjusted by a computing device. In some embodiments, the cleaning gas is pulsed to the reaction chamber 110 through the first inlet and the second inlet. In some embodiments, the cleaning gas pulse time is 15 to 300 seconds, followed by an inert gas (such as N2) purge, wherein the purge duration is 10 to 200 seconds. In some embodiments, the total cleaning gas pulse time is 10 minutes, 20 minutes or 30 minutes, or 5 to 30 minutes. In some embodiments, the duration of the cleaning gas pulse (one or more) is longer than the duration of the purge (one or more). In some embodiments, N2 is used as a carrier gas for the cleaning gas.

[0095] In some embodiments, the reaction chamber 110 during cleaning has an elevated temperature. In some embodiments, the reaction chamber temperature during cleaning is 50 to 200° C., such as 125° C. In some embodiments, the reaction chamber temperature during cleaning is at least 125° C. In some embodiments, the reaction chamber 110 and the substrate support 150 during cleaning have the same temperature.

[0096] In some embodiments, the flow rate of the first cleaning gas flow is equal to the flow rate of the second cleaning gas flow. In some embodiments, the flow rate is 50sccm, 100sccm, 150sccm, 200sccm or 300sccm. In some embodiments, the flow rate is 20 to 500sccm. In some embodiments, the flow rate is greater than 500sccm. In some embodiments, the flow rates from the two opposite inlets 120, 180 are not equal. In some embodiments, the cleaning gas flow through the first inlet 120 (top) has a higher flow rate than the second cleaning gas flow through the second inlet 180 (bottom). In some embodiments, the flow rate of the first inlet 120 (top) is lower than the flow rate of the bottom inlet 180 (bottom). In some embodiments, the ratio of the flow rate from the first inlet 120 to the flow rate from the second inlet 180 is from 6:1 to 1:6. In some embodiments, the maximum ratio of the flow rate from the first inlet 120 to the flow rate from the second inlet 180 is 10:1. In some embodiments, the minimum ratio of the flow rate from the first inlet 120 to the flow rate from the second inlet is 1:10. In some embodiments, the relative flow rates of the two opposing inlets 120, 180 vary during the cleaning process, while the total flow rate remains constant. In some embodiments, the flow rates are automatically controlled by a computing device, such as a general purpose personal computer.

[0097] In some embodiments, the duration and / or flow rate of the first cleaning gas flow and the second cleaning gas flow through the two opposing inlets 120, 180 are individually controlled to target the total cleaning gas flow to the interior of the reaction chamber 110. In some embodiments, the duration and / or flow rate are controlled to direct most of the cleaning gas to the area in the reaction chamber 110 that is most in need of cleaning. For example, when it has been observed that the top part of the reaction chamber suffers from chemical accumulation, a higher flow rate from the bottom inlet can be used to focus most of the cleaning gas flow to the top of the reaction chamber 110. In some embodiments, the flow rate is manually determined by a user. In some embodiments, the flow rate is automatically determined by a computing device.

[0098] In some embodiments, the cleaning gas is sequentially injected into the reaction chamber by alternating the cleaning gas flow through two opposing inlets 120, 180 for etching the reaction chamber with an activated cleaning gas. In some embodiments, the cleaning gas is sequentially injected into the reaction chamber 110 by alternating the cleaning gas flow between the two opposing inlets 120, 180. For example, the cleaning gas may first flow out of only the first inlet 120, while the second inlet 180 is closed; thereafter, the first inlet 120 is closed and the cleaning gas flow is allowed to pass through the second inlet 180. In some embodiments, the cleaning gas is first injected from the first inlet 120 (top) and then injected from the second inlet 180 (bottom). In some embodiments, the cleaning gas is first injected from the second inlet 180 (bottom) and then injected from the first inlet 120 (top).

[0099] In some embodiments, the duration of the first clean gas flow (first injection) from the first inlet 120 is equal to the duration of the second clean gas flow (second injection) from the second inlet 180. In some embodiments, the duration of each sequential injection is 30 seconds, 60 seconds, 120 seconds, or 180 seconds. In some embodiments, the duration of the sequential injections is not equal. For example, in some embodiments, the duration of the first injection is 60 seconds, 120 seconds, 180 seconds, 240 seconds, or 300 seconds, respectively, and the duration of the second injection is 30 seconds, 60 seconds, 120 seconds, or 180 seconds. For example, in some embodiments, the duration of the first injection is 30 seconds, 60 seconds, 120 seconds, or 180 seconds, respectively, and the duration of the second injection is 60 seconds, 120 seconds, 180 seconds, 240 seconds, or 300 seconds. For clarity, it should be noted that the first injection is the first clean gas injection that occurs, and the second injection is the injection performed after the first injection. That is, the first injection does not necessarily occur from the first inlet 120 , and the second injection does not necessarily occur from the second inlet 180 .

[0100] In some embodiments, the flow rates of the sequential injections are equal. In some embodiments, the flow rates of the first injection and the second injection are 20 to 500 sccm. In some embodiments, the flow rates of the sequential injections are unequal. In some embodiments, the ratio of the first injection rate to the second injection rate is 20 to 500 sccm.

[0101] Advantageously, separately controlling the flow rate and duration of the first and second injections allows the cleaning gas to be targeted to the interior of the reaction chamber according to the accumulation of chemical substances. For example, if most of the accumulated chemical contaminants are located in the top part of the reaction chamber, the flow rate and duration of the cleaning gas flow from the back protection channel 180 can be increased, and the gas flow from the showerhead 120 can be kept short and weak. Therefore, the cleaning gas flow can be specifically targeted to the top part of the reaction chamber 110, while less intense cleaning is required in the bottom part. Vice versa, if it is observed that the top part of the reaction chamber 110 is clean, a higher flow rate and longer duration of the gas flow from the showerhead 120 may be preferred to direct most of the cleaning gas downward to the bottom of the reaction chamber 110. In general, due to the two cleaning gas flows from two opposing inlets 120, 180, the distribution of the activated cleaning gas within the reaction chamber 110 is improved.

[0102] 350: The process optionally includes removing the cleaning gas from the reaction chamber through the outlet 160. In certain embodiments, the vacuum pump 170 is used to remove the cleaning gas and cleaning residues from the reaction chamber 110.

[0103] 360: The process optionally includes repeating the cleaning process a predetermined number of times. In some embodiments, steps 310 to 350 are repeated a predetermined number of times. In some embodiments, the flow rate and duration from the first inlet and / or from the second inlet are different for each cleaning process repetition cycle. Advantageously, each cleaning cycle can target a large portion of the activated cleaning gas flow to a certain component of the reaction chamber 110. In some embodiments, in repeated cleaning cycles, simultaneous and sequential activated cleaning gas injections are alternated. In some embodiments, the cleaning process of simultaneously injecting cleaning gas from two opposing inlets 120, 180 is repeated 1, 2, 3, or 4 times. In some embodiments, the cleaning process of sequentially injecting cleaning gas from two opposing inlets 120, 180 is repeated 1, 2, 3, or 4 times. In some embodiments, the number of cleaning process cycles is based on the observed conditions of the reaction chamber. In some embodiments, the cleaning process alternates between simultaneous cleaning gas injection and sequential cleaning gas injection.

[0104] Without limiting the scope and interpretation of the patent claims, some technical effects of one or more example embodiments disclosed herein are listed below. A technical effect is improved cleaning gas distribution inside a reaction chamber. Another technical effect is improved cleaning efficiency of a reaction chamber. Another technical effect is improved processing quality due to less contamination. Another technical effect is reduced consumption of cleaning gas during chamber cleaning. Another technical effect is reduced etching time due to more efficient cleaning gas distribution. Another technical effect is improved control and targeting of cleaning gas flow within a reaction chamber.

[0105] Various embodiments have been presented.It should be understood that in this document, the words "include," "comprises," and "comprising" are each used as open-ended expressions, with no exclusivity intended.

[0106] The foregoing description has provided, by way of non-limiting examples of specific embodiments and embodiments, a complete and informative description of the best mode presently contemplated by the inventor for carrying out the invention. However, it will be apparent to those skilled in the art that the invention is not limited to the details of the embodiments given above, but may be implemented in other embodiments using equivalent means or in different combinations of embodiments without departing from the features of the invention.

[0107] In addition, some features of the exemplary embodiments disclosed above can be used advantageously without correspondingly using other features. Therefore, the above description should be considered as merely an illustration of the principles of the present invention, rather than a limitation of the present invention. Therefore, the scope of the present invention is only limited by the attached patent claims.

Claims

1. A method for cleaning a reaction chamber (110) of a substrate processing apparatus (100), comprising: providing (210) a clean gas from a clean gas source (190); Supplying (230) a first cleaning gas flow into the reaction chamber (110) through a first inlet (120), and supplying a second cleaning gas flow into the reaction chamber through a second inlet (180), for etching the reaction chamber (110), wherein the first cleaning gas flow and the second cleaning gas flow enter the reaction chamber (110) from different directions; and The cleaning gas is activated prior to the etching. 2 . The method of claim 1 , wherein the activating comprises at least one of decomposing the cleaning gas with a plasma and forming a plasma from the cleaning gas.

3. The method according to claim 1 or 2, comprising: The cleaning gas is simultaneously supplied into the reaction chamber (110) through the first inlet (120) and the second inlet (180).

4. The method according to claim 1 or 2, comprising: The cleaning gas is sequentially supplied into the reaction chamber (110) through the first inlet (120) and the second inlet (180).

5. The method according to any one of the preceding claims, wherein the cleaning gas is a fluorine-based gas.

6. The method of any one of the preceding claims, wherein the cleaning gas of the first cleaning gas flow is different from the cleaning gas of the second cleaning gas flow.

7. The method according to any one of the preceding claims, wherein the first inlet (120) and the second inlet (180) are opposite to each other.

8. The method according to any of the preceding claims, wherein the second inlet (180) is a substrate backside protection channel.

9. A method according to any one of the preceding claims, wherein the first cleaning gas flow enters the reaction chamber (110) through the top of the reaction chamber (110) via the first inlet (120), and the second cleaning gas flow enters through the bottom of the reaction chamber (110) via the second inlet (180) opposite to the first inlet (120).

10. The method according to any of the preceding claims, wherein at least one of the two inlets is also used for supplying reactive chemicals during substrate processing.

11. A method according to any one of the preceding claims, comprising: The method is repeated (360) a predetermined number of times.

12. A method according to any one of the preceding claims, comprising: The cleaning gas is activated with plasma formed in a separate plasma forming unit.

13. The method according to any one of claims 1 to 11, comprising: The cleaning gas is activated by plasma formed in a plasma forming unit integrated into the reaction chamber (110).

14. A method according to any one of the preceding claims, comprising: The cleaning gas of the first cleaning gas flow and the cleaning gas of the second cleaning gas flow are activated with plasma formed in a single plasma forming unit.

15. A method according to any one of the preceding claims, comprising: The plasma for activating the cleaning gas and the plasma for substrate processing are formed in the same plasma forming unit.

16. A method according to any one of the preceding claims, comprising: The cleaning gas flows are targeted to the interior of the reaction chamber (110) by controlling the duration and / or flow rate of the first cleaning gas flow and the second cleaning gas flow.

17. A substrate processing device (100), comprising: A reaction chamber (110); a first inlet (120) for supplying a cleaning gas as a first cleaning gas flow from a cleaning gas source (190) into the reaction chamber (110); a second inlet (180) for supplying a cleaning gas as a second cleaning gas flow from the cleaning gas source (190) into the reaction chamber (110) from a direction different from the supply direction of the first cleaning gas flow; as well as A plasma forming unit is configured to activate the cleaning gas for etching the reaction chamber (110).

18. The substrate processing apparatus (100) according to claim 17, wherein the plasma forming unit is configured to activate the cleaning gas by at least one of decomposing the cleaning gas with plasma and forming plasma from the cleaning gas.

19. The substrate processing apparatus (100) according to claim 17 or 18, wherein the plasma forming unit is an integrated plasma forming unit integrated into the reaction chamber (110).

20. The substrate processing apparatus (100) according to claim 17 or 18, comprising a remote plasma forming unit for forming plasma to activate a cleaning gas before supplying the cleaning gas into the reaction chamber (110).

21. The substrate processing apparatus (100) according to any one of claims 17 to 20, wherein the first inlet line (120) and the second inlet line (180) are opposite to each other.

22. The substrate processing apparatus (100) according to any one of claims 17 to 21, configured to supply the first cleaning gas flow and the second cleaning gas flow into the reaction chamber (110) simultaneously.

23. The substrate processing apparatus (100) according to any one of claims 17 to 21, configured to sequentially supply the first cleaning gas flow and the second cleaning gas flow into the reaction chamber (110).

24. The substrate processing apparatus (100) according to any one of claims 17 to 23, wherein the cleaning gas is a fluorine-based gas.

25. The substrate processing apparatus (100) according to any one of claims 17 to 24, wherein the cleaning gas of the first cleaning gas flow is different from the cleaning gas of the second cleaning gas flow.

26. The substrate processing apparatus (100) according to any one of claims 17 to 25, wherein the second entrance (180) is a substrate back side protection channel.

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