ALD apparatus, method and valve

Abstract

An apparatus, a method and a valve with a reactive chemical inlet, a reaction chamber outlet, and a closure having an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet to the reaction chamber outlet, the valve further including an additional cleaning chemical inlet at a downstream side of the closure to purge the closure.

Claims

1. An apparatus, comprising: a reaction chamber; a pulsing valve directly attached to the reaction chamber, the pulsing valve comprising: a reactive chemical inlet; a reaction chamber outlet; and a closure having an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet to the reaction chamber outlet, the apparatus further comprising: an additional cleaning chemical inlet at the reaction chamber side of the closure to purge the closure, wherein the closure provides a valve output surface facing the reaction chamber outlet in the open configuration, wherein the valve output surface is purged in both the open configuration and in the closed configuration of the closure, and wherein in the closed configuration, the reactive chemical remains on a side of the closure other than a side of the closure providing the valve output surface.

2. The apparatus of claim 1, wherein the additional cleaning chemical inlet is configured to purge the valve output surface.

3. The apparatus of claim 1, wherein the additional cleaning chemical inlet points directly or at least obliquely to the closure and/or valve output surface.

4. The apparatus of claim 1, wherein the reaction chamber outlet provides a reaction chamber outlet channel towards the reaction chamber.

5. The apparatus of claim 4, comprising the additional cleaning chemical inlet in a reaction chamber outlet channel wall.

6. The apparatus of claim 4, comprising a pipe extending towards the closure and/or valve outlet surface within the reaction chamber outlet channel, the pipe providing the additional cleaning chemical inlet.

7. The apparatus of claim 1, wherein the apparatus is configured to provide continuous purge of the closure and/or valve output surface.

8. The apparatus of claim 1, wherein the apparatus is configured to provide purge along the closure and/or valve output surface.

9. The apparatus of claim 1, comprising a heated outer chamber around the reaction chamber.

10. The apparatus of claim 9, comprising the pulsing valve in a heated intermediate space within the outer chamber but on the outside of the reaction chamber.

11. The apparatus of claim 1, providing a route by-passing the closure from the reactive chemical inlet to the waste line outlet that route being open in the closed configuration of the closure.

12. The apparatus of claim 1, wherein the apparatus is configured to maintain a higher pressure in a chemical waste line beginning at the waste line outlet compared to a pressure in the reaction chamber.

13. The apparatus of claim 1, wherein the pulsing valve is embedded into or attached to a structure selected from a group comprising: a structure leading to a reaction chamber, a reaction chamber structure, a reaction chamber wall, and a reaction chamber lid.

14. The apparatus of claim 1, wherein the apparatus is an ALD reactor.

15. The apparatus of claim 1, wherein the pulsing valve comprises a chemical waste line outlet.

16. The apparatus of claim 15, wherein the closure is configured to prevent reactive chemical from flowing into the chemical waste line outlet when in the open configuration.

17. A method, comprising: supplying reactive chemical through a pulsing valve comprising a reactive chemical inlet, a reaction chamber outlet, and a closure having an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet to the reaction chamber outlet, wherein the pulsing valve is directly attached to a reaction chamber; controlling the closing of the route by pulsing the closure; and supplying cleaning chemical through an additional cleaning chemical inlet at the reaction chamber side of the closure and purging the closure by the cleaning chemical, purging a valve output surface provided by the closure that is facing the reaction chamber outlet in the open configuration; and purging the valve output surface in both the open configuration and in the closed configuration of the closure, wherein in the closed configuration, the reactive chemical remains on a side of the closure other than a side of the closure providing the valve output surface.

18. The method of claim 17, comprising: purging the valve output surface provided by the closure by cleaning chemical released from the additional cleaning chemical inlet that is additional to the reaction chamber outlet.

19. The method of claim 17, wherein the additional cleaning chemical inlet points directly or at least obliquely to the closure and/or valve output surface.

20. The method of claim 17, comprising providing the additional cleaning chemical inlet in a reaction chamber outlet channel wall.

21. The method of claim 17, comprising supplying the cleaning chemical from a pipe extending towards the closure and/or valve outlet surface within the reaction chamber outlet channel, the pipe providing the additional cleaning chemical inlet.

22. The method of claim 17, comprising: purging the closure and/or valve output surface continuously.

23. The method of claim 17, comprising: purging along the closure and along the reaction chamber outlet channel wall.

24. The method of claim 17, comprising: heating an outer chamber around the reaction chamber.

25. The method of claim 17, comprising: providing a route by-passing the closure from the reactive chemical inlet to a waste line outlet that route being open in the closed configuration of the closure.

26. The method of claim 25, comprising: maintaining a higher pressure in a chemical waste line compared to a pressure in the reaction chamber, which chemical waste line begins at the waste line outlet.

27. The method of claim 25, comprising: completely preventing or at least partly preventing reactive chemical from flowing into the chemical waste line outlet when the closure is in the open configuration.

28. The method of claim 17, comprising: performing ALD deposition within the reaction chamber.

29. The method of claim 17, wherein said supplying of cleaning chemical comprises releasing cleaning chemical onto pulsing valve output surface which cleaning chemical reacts with reactive chemicals on the surface without producing solid particles.

30. A pulsing valve directly attached to a reaction chamber, the pulsing valve, comprising: a reactive chemical inlet; a reaction chamber outlet; and a closure having an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet to the reaction chamber outlet, the valve further comprising: an additional cleaning chemical inlet at a downstream side of the closure to purge the closure, wherein the closure provides a valve output surface facing the reaction chamber outlet in the open configuration, wherein the valve output surface is purged in both the open configuration and in the closed configuration of the closure, and wherein in the closed configuration, the reactive chemical remains on a side of the closure other than a side of the closure providing the valve output surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The aspects of the disclosed embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a pulsing valve with its closure in a closed configuration in accordance with certain example embodiments of the present disclosure;

(3) FIG. 2 shows the pulsing valve of FIG. 1 with its closure in an open configuration;

(4) FIG. 3 shows a pulsing valve with its closure in a closed configuration in accordance with certain other example embodiments of the present disclosure;

(5) FIG. 4 shows the pulsing valve of FIG. 3 with its closure in an open configuration;

(6) FIG. 5 shows a pulsing valve attached to a reaction chamber structure in accordance with certain example embodiments of the present disclosure;

(7) FIG. 6 shows a substrate processing apparatus in accordance with certain example embodiments of the present disclosure;

(8) FIG. 7 shows a method according to certain example embodiments of the present disclosure; and

(9) FIG. 8 shows yet another example embodiment of the present disclosure.

DETAILED DESCRIPTION

(10) In the following description, Atomic Layer Deposition (ALD) technology is used as an example. However, the aspects of the disclosed embodiments are not limited to ALD technology, but it can be exploited in a wide variety of substrate processing apparatuses, for example, in Chemical Vapor Deposition (CVD) reactors.

(11) The basics of an ALD growth mechanism are known to a skilled person. ALD is a special chemical deposition method based on the sequential introduction of at least two reactive precursor species to at least one substrate. It is to be understood, however, that one of these reactive precursors can be substituted by energy when using, for example, photon-enhanced ALD or plasma-assisted ALD, for example PEALD, leading to single precursor ALD processes. For example, deposition of a pure element, such as metal, requires only one precursor. Binary compounds, such as oxides can be created with one precursor chemical when the precursor chemical contains both of the elements of the binary material to be deposited. Thin films grown by ALD are dense, pinhole free and have uniform thickness.

(12) The at least one substrate is typically exposed to temporally separated precursor pulses in a reaction vessel to deposit material on the substrate surfaces by sequential self-saturating surface reactions. In the context of this application, the term ALD comprises all applicable ALD based techniques and any equivalent or closely related technologies, such as, for example the following ALD sub-types: MLD (Molecular Layer Deposition) plasma-assisted ALD, for example PEALD (Plasma Enhanced Atomic Layer Deposition) and photon-enhanced Atomic Layer Deposition (known also as flash enhanced ALD).

(13) A basic ALD deposition cycle consists of four sequential steps: pulse A, purge A, pulse B and purge B. Pulse A consists of a first precursor vapor and pulse B of another precursor vapor. Inactive gas and a vacuum pump are typically used for purging gaseous reaction by-products and the residual reactant molecules from the reaction space during purge A and purge B. A deposition sequence comprises at least one deposition cycle. Deposition cycles are repeated until the deposition sequence has produced a thin film or coating of desired thickness. Deposition cycles can also be either simpler or more complex. For example, the cycles can include three or more reactant vapor pulses separated by purging steps, or certain purge steps can be omitted. All these deposition cycles form a timed deposition sequence that is controlled by a logic unit or a microprocessor.

(14) A reaction space is a defined volume within a reaction chamber. The desired chemical reactions occur in the reaction space. Basic ALD inlet tools through which chemicals are flown into the reaction space are generally knows as shower heads. The inlet of precursor chemical can be from the top, or cross flow, where the chemical is inlet from at least one side.

(15) FIG. 1 shows a pulsing valve with its closure in a closed configuration in accordance with certain example embodiments of the present disclosure. The pulsing valve 100 comprises a valve body 110 having an inlet 101 for reactive chemical, such as a precursor chemical, and an outlet 104 towards a reaction chamber (not shown in FIG. 1). A closure 111 comprised by the pulsing valve has an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet 101 to the reaction chamber outlet 104. FIG. 1 shows the closure 111 in its closed configuration.

(16) A surface of the closure 111 pointing towards the reaction chamber is defined as a valve output surface 112. The pulsing valve 100 further comprises an additional cleaning chemical inlet 103 at the reaction chamber side of the closure 111 to purge the closure 111, especially the valve output surface 112, to prevent or minimize material growth thereon thus providing a cleaning effect. The same effect is achieved on side walls of the outlet (or outlet channel, or opening) 104 when the cleaning chemical exits along the side walls towards the reaction chamber. In certain example embodiments, the cleaning chemical inlet 103 is implemented through the side wall of the outlet 104. A cleaning chemical inlet pipe or channel travelling within the valve body passes through the side wall and points towards the closure 111 and/or valve output surface 112.

(17) The cleaning chemical can be the same gas that is used as the purging gas in the reaction chamber during process stage. Cleaning chemical is led to inlet 103 via a route that is separate from the routes the other chemicals use. In certain example embodiments, the cleaning chemical route has pulsing control, mass flow control, and/or valve control to change and/or limit the flow of cleaning chemical with respect to pulses in process stage.

(18) The pulsing valve 100 further comprises an optional chemical waste line outlet 102. A route by-passing the closure 111 is formed from the reactive chemical inlet 101 to the waste line outlet 102.

(19) The pulsing valve 100 may be attached to and/or sealed with a reaction chamber structure of a substrate processing apparatus at its attaching surface 115.

(20) FIG. 2 shows the pulsing valve 100 with its closure 111 in an open configuration. The reactive chemical flows from the reactive chemical inlet 101 to the reaction chamber outlet 104.

(21) FIG. 3 shows a pulsing valve with its closure in a closed configuration in accordance with certain other example embodiments of the present disclosure. The pulsing valve 300 comprises a valve body 110 having an inlet 101 for reactive chemical, such as a precursor chemical, and an outlet 104 towards a reaction chamber (not shown in FIG. 3). A closure 111 comprised by the pulsing valve has an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet 101 to the reaction chamber outlet 104. FIG. 3 shows the closure 111 in its closed configuration.

(22) A surface of the closure 111 pointing towards the reaction chamber is, again, defined as a valve output surface 112. The pulsing valve 300 further comprises an additional cleaning chemical inlet 303 at the reaction chamber side of the closure 111 to purge the closure 111, especially the valve output surface 112, to prevent or minimize material growth thereon thus providing a cleaning effect. The same effect is achieved on side walls of the outlet (or outlet channel, or opening) 104 when the cleaning chemical exits along the side walls towards the reaction chamber. In certain example embodiments, the cleaning chemical inlet 103 is implemented as a separate pipeline extending within the outlet 104 towards the closure 111 and/or valve output surface 112.

(23) The pulsing valve 300 further comprises an optional chemical waste line outlet 102. A route by-passing the closure 111 is formed from the reactive chemical inlet 101 to the waste line outlet 102.

(24) The pulsing valve 300 may be attached to a reaction chamber structure of a substrate processing apparatus at its attaching surface 115. As to the operation of the pulsing valve 300 a reference is made to the preceding description in connection with pulsing valve 100.

(25) FIG. 4 shows the pulsing valve 300 with its closure 111 in an open configuration. The reactive chemical flows from the reactive chemical inlet 101 to the reaction chamber outlet 104.

(26) FIG. 5 shows a pulsing valve attached to a reaction chamber structure in accordance with certain example embodiments of the present disclosure. The pulsing valve 100 (300) may form part of the surface of the reaction chamber. In certain example embodiments, the reaction chamber structure 520 comprises a recess into which the pulsing valve 100 (300, similarly) is embedded. The pulsing valve 100 (300) may be tightened against the structure 520 at the attaching surface 115. In certain example embodiments, the pulsing valve is attached to a reaction chamber wall. In certain example embodiments, the pulsing valve is attached to a reaction chamber side wall. FIG. 5 specifically shows an embodiment in which the pulsing valve is embedded into reaction chamber upper wall, or lid.

(27) In certain example embodiments, the pulsing valve forms an integral part of the reaction chamber. In other example embodiments, the pulsing valve is attached to a pipe or other structure leading to a reaction chamber.

(28) FIG. 5 further shows by arrows certain routing alternatives to implement a route of the cleaning chemical inlet pipe (or channel). The pipe can for part of the valve structure and/or the reaction chamber lid and/or wall structure, or it can be a separate pipe attached to or through the reaction chamber lid/wall. The route can extend in parallel of the reaction chamber lid or wall structure on the outside of the structure, and/or it can penetrate through the structure into the reaction chamber side of the structure, and/or it can extend within the lid or wall structure and/or within the valve body. The other pipings, such as the reactive chemical in-feed piping, can be implemented similarly.

(29) FIG. 6 shows a substrate processing apparatus in accordance with certain example embodiments of the present disclosure. The substrate processing apparatus 500 comprises a reaction chamber 530 configured to house a substrate 600 within a reaction space 521 defined by the reaction chamber 530. In certain example embodiments, the apparatus comprises an outer chamber 540 surrounding the reaction chamber 530 thereby closing an intermediate space 522 in between the reaction chamber 530 and the outer chamber 540. In certain example embodiments, the intermediate space 522 is heated by a heater 545 positioned in the space 522.

(30) A reactive chemical in-feed line 501 (which may contain a plurality of pipes) extends from a reactive chemical source (not shown) via the intermediate space (if any) to the reactive chemical inlet (see FIGS. 1-4, inlet 101) of the pulsing valve 100. A chemical waste line 502 extends from the chemical waste line outlet (see FIGS. 1-4, outlet 102) of the pulsing valve 100 via the intermediate space (if any) to exhaust. The waste line 502 in certain example embodiments joins to an exhaust line 555 that extends from the reaction chamber 530 to a vacuum pump (not shown).

(31) The pulsing valve 100 has similar structure and operation as described in connection of FIGS. 1 and 2. Accordingly, the pulsing valve 100 comprises a valve body having an inlet for reactive chemical, and an outlet towards the reaction chamber 530. A closure comprised by the pulsing valve has an open and closed configuration to open and close, respectively, a route from the reactive chemical inlet to the reaction chamber outlet. The pulsing valve 100 further comprises the additional cleaning chemical inlet at the reaction chamber side of the closure to purge the closure. The pulsing valve 100 further comprises the optional chemical waste line outlet. A route by-passing the closure is formed from the in-feed line 501 via the reactive chemical inlet to the waste line 502 via the waste line outlet.

(32) Although there is only one pulsing valve shown in FIG. 6 it is clear that there may be a plurality of pulsing valves with similar structural and operational features, and/or one or more other pulsing valves with different known structures. Instead of the pulsing valve 100, the pulsing valve(s) 300 described in connection with FIGS. 3 and 4 may be used. The pulsing valve(s) may be positioned at the side wall of the reaction chamber 530, as illustrated by reference numeral 100′, or they may be positioned at the lid structure or upper wall 520, or both at the side wall and at the lid structure/upper wall 520. In certain example embodiments, at least one pulsing valve can be positioned inside of the reaction chamber 530. In certain example embodiments, all of the one or more pulsing valves are positioned at the side wall and the reaction chamber is open from the top to receive energy needed in surface reactions at the substrate surface from the top, wherein the energy may be in the form of plasma or photons, for example.

(33) In certain example embodiments, the reaction chamber 530 comprises a hatch 531 at its side wall for loading and unloading substrates. The structure 520 may be a fixed chamber upper wall or a removable lid. In certain example embodiments, the structure 520 is a removable lid. The substrate or substrates 600 are loaded from the top side of the reaction chamber by lifting the lid 520. A preferred position of the pulsing valve(s) is then at the side wall. In the event the removable lid has pulsing valve(s) at the lid, the pipings 501 and 502 can be designed to connect and disconnect if needed, for example at line 560 in FIG. 6. In certain example embodiments, the reaction chamber 520 is lowered, for example, by a bellows structure 570 to form a substrate loading route in between the chamber 530 and lid 520. A similar arrangement has been described in a co-pending international application PCT/FI2017/050071 filed by the same application. This enables loading from the side of the reaction chamber.

(34) FIG. 7 shows a method according to certain example embodiments of the present disclosure. In step 701, reactive chemical is supplied to a reaction chamber via a pulsing valve for deposition. The supply of reactive chemical to the reaction chamber is interrupted in step 702. The valve output surface is purged by cleaning chemical, and the purging by cleaning chemical is continued in step 703.

(35) In certain example embodiments, a reactive chemical pulse into the reaction chamber is followed by a cleaning chemical period. The cleaning chemical may be gas or fluid. In certain example embodiments, the cleaning chemical flows continuously. In certain example embodiments, the flow rate of cleaning chemical is reduced at least during a part of a precursor chemical pulse. In certain example embodiments, the cleaning chemical flows at an elevated rate during a period in which precursor vapor is not released into the reaction chamber via the pulsing valve in question.

(36) The cleaning chemical can refer here to a gas or fluid, which can push fluid atoms or molecules away from a space, and/or which can remove them from surfaces. The cleaning chemical can be neutral, such as argon gas Ar, or nitrogen gas N2, or reactive, such as heated gas, or ionized or radical gas. It can be any such gas which does not react with the reactive chemical, or it can be any such gas which reacts with the chemical to be cleaned in a way that it does not produce solid species (or in some cases neither liquid species, which would react with the substrate). In certain example embodiments, the cleaning gas can be helium gas He. Some or all of the gases can be considered as carrier gases.

(37) In certain or all foregoing embodiments, the following applies:

(38) chemical flowing into the inlet 101 may consist of pure precursor (or reactive) chemical, or a mixture of precursor chemical and carrier gas;

(39) the flow and mixing of reactive gas to carrier gas can be controller with mass flow controller or valves synchronized with the whole process, or with any synchronization down to duration of a step of the deposition cycle, such as presented, for example, in U.S. Pat. No. 8,211,235 assigned to the same assignee;

(40) the pulsing valve 100 or 300 may contain a flow restrictor, such as a capillary, in the optional waste line 502 within the valve area;

(41) the valve 100 or 300 may be a 3-way valve or a 4-way valve in which a fluid flow hits the closure 111;

(42) the fluid flow may be released from the additional cleaning chemical inlet positioned at a side of the valve (as in FIGS. 1 and 2), and/or the additional cleaning chemical inlet may be provided by a cleaning chemical inlet pipe coming from the outside of valve body (as in FIGS. 3 and 4);

(43) the cleaning chemical inlet pipe may be heated, which heat may me higher than the reaction chamber heat;

(44) the cleaning chemical inlet pipe may be provided with pre-heated gas;

(45) the provided reaction chamber outlet channel (or opening) 104 towards the reaction chamber may be the only inlet to the reaction chamber (i.e., there are no other gas inlets to the reaction chamber)—this outlet channel may provide all chemicals needed in the reactions within the reaction chamber;

(46) the pulsing valve may be oriented such that the closure 111 faces (or sees) the reaction space (or substrate surface);

(47) the opening may expand from the closure surface towards the reaction chamber

(48) the expansion may be in the form of a conical opening;

(49) the pulsing valve may form part of the reaction chamber (or reaction vessel) structure—the reaction chamber structure may be a reaction chamber lid

(50) the pressure in the intermediate space 522 pressure may be 1000-0.1 mBar, preferably 100-1 mBar, more preferably 20-2 mBar.

(51) the reaction chamber pressure may be ambient to 1 μBar, more preferably 10-0.01 mBar, most preferably 1-0.1 mBar.

(52) the reaction chamber pressure can be varied with the aid of modifying the vacuum in foreline (exhaust line) 555 leading out from the chamber 530, or by a total gas flow to the reaction space 521, and possibly intermediate space 522;

(53) the reaction chamber pressure referred here can be synchronized with the whole process, or any synchronization down to duration of a step of the deposition cycle may be applied

(54) FIG. 8 shows yet another example embodiment of the present disclosure. The closure 111 can be configured to close the waste line outlet 102′, or at least partly close the waste line outlet 102′, or decrease the flow to the waste line, while the route from the reactive chemical inlet 101 to the reaction chamber outlet 104 is opened. The waste line outlet 102′ may be positioned at the other side of the closure 111 so that when the closure 111 moves away from the reaction chamber outlet 104 it pushes against the waste line outlet (opening) 102′.

(55) Yet in other embodiments, in a slightly modified valve design, the closure 111 will close the reactive chemical inlet (opening) 101 while it closes the passage to the reaction chamber, e.g., by pushing against the inlet 101. This is in order to evacuate reactive gas from the space above the closure 111 into the waste line. This is especially applicable if the closure 111 is not able to completely block the reactive chemical flow into the reaction chamber past the closure (i.e., when the closure 111 is not completely closing). The pressure in the space above the closure 111 is then lower compared to the pressure inside the reaction chamber and residual reactive chemical flows into the direction of the waste line.

(56) The description concerning any particular preceding embodiment is directly applicable to other disclosed embodiments. This applies both with regard to the structure and operation of the disclosed apparatus.

(57) Without limiting the scope and interpretation of the patent claims, certain technical effects of one or more of the example embodiments disclosed herein are listed in the following. A technical effect is providing a minimum amount of trapped precursor chemical thereby avoiding undesired particle generation, while enabling high pulsing speed, for example, more than one pulse and purge per second. Another technical effect is a mechanically smaller pulsing valve implementation, for example, less than 10 cm.sup.3, such as 4 cm.sup.3. Another technical effect is a cleaning effect by purging reactive material away from surfaces. Undesired gas phase reactions of material adsorbed on solid surfaces of the pulsing valve structure and pulsing valve outlet can be minimized.

(58) It should be noted that some of the functions or method steps discussed in the preceding may be performed in a different order and/or concurrently with each other. Furthermore, one or more of the above-described functions or method steps may be optional or may be combined.

(59) In the foregoing drawings 1-4, and 8 a space inside the valve 100 or 300 where the closure 111 is moved should in each case be consider to be a closed volume.

(60) The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments of the present disclosure a full and informative description of the best mode presently contemplated by the inventors for carrying out the aspects of the disclosed embodiments. It is however clear to a person skilled in the art that the aspects of the disclosed embodiments are not restricted to details of the embodiments presented above, but that it can be implemented in other embodiments using equivalent means without deviating from the characteristics of the present disclosure.

(61) Furthermore, some of the features of the above-disclosed embodiments of the present disclosure may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the present disclosure, and not in limitation thereof. Hence, the scope of the aspects of the disclosed embodiments are only restricted by the appended patent claims.