The present application is a national phase entry of PCT/EP2010/070450, filed on Jul. 30, 2019, which claims the benefit of priority of French Patent Application No. 1857072, filed Jul. 30, 2018, the entire contents of which are hereby incorporated by reference in their entirety for all purposes.
The invention relates to a thin layer vapor deposition head, and more particularly to a deposition head suitable for implementing the SALD—spatial atomic layer deposition—technique. The invention relates also to a thin layer deposition system comprising such a head.
Atomic layer deposition (ALD) is a chemical vapor deposition (CVD) technique developed in the 1960-70s which offers the unique possibility of depositing thin layers of high quality at low temperature, with precise thickness control, an exceptional uniformity and an excellent coverage even in the presence of steps having a significant aspect ratio. That is due to the spontaneously self-limiting nature of the growth by ALD, which is performed directly and selectively on the surface of the sample upon the sequential exposure of different precursors conveyed by inert gas flows (typically N2 or Ar). Thus, whereas in the traditional chemical vapor deposition techniques the precursors are injected at the same time and react on the substrate by thermal or plasma activation, in the case of ALD the precursors are injected by consecutive pulses, separated in time, thus allowing the surface selective and spontaneously resolvent nature of the technique.
Since the 1990s, ALD has become the technique of choice in the semiconductor industries and the industries producing large screens. The later advent of nanosciences and nanotechnologies has broadened the use of ALD to research laboratories.
Despite its unique advantages, ALD does have two major drawbacks which have limited its industrial application: the slowness of the deposition and the need to operate in a vacuum. Consequently, ALD is, these days, used solely in the industries in which no other technique is available.
Spatial ALD (SALD) provides a solution to the problem of the slowness of “conventional” ALD. This technique, initially proposed by T. S. Suntola et al. in the patent U.S. Pat. No. 4,389,973, consists in separating the precursors in space rather than in time. Thus, in SALD, the precursors are delivered constantly in correspondence with different portions of the surface of the substrate, separated by a zone of inert gas, while the sample is displaced from the location of one precursor to the other by passing through the zone of inert gas. That makes it possible to increase the rate of deposition by up to two orders of magnitude. Moreover, it has been demonstrated that, by arranging the SALD deposition head in immediate proximity (100 μm or less) from the deposition surface and by equipping it with gas suction apertures, it is possible to operate at ambient pressure, and therefore outside of a vacuum chamber. This is then called ambient pressure SALD (AP-SALD). See for example US 2009/0217878 and US 2009/081886.
The flows of the gases are represented by arrows. It can be seen that the inert gas forms “barriers” which separate the gas flows containing the precursors from one another and from the ambient air. A substrate SUB, borne by a support or plate PS, is arranged facing and at a short distance from (<100 μm, for example 50 μm) the slits, the plate being driven by an oscillatory movement parallel to the face of the head which bears the slits. The successive reaction of the molecules of the two precursors with one another and with the surface of the substrate leads to the formation of a thin deposited layer CD. In the case where the precursors are H2O and Al(CH3)3, the layer CD is of Al2O3.
Variants are possible, for example the number of precursors can be greater than two.
A more detailed presentation of the AP-SALD technique and of its applications can be found in the article by David Muñoz-Rojas and Judith MacManus Driscoll entitled “Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics”, Material Horizons 2014, vol. 1, No. 3, p. 314-320.
The AP-SALD technique constitutes a significant enhancement over conventional ALD. It nevertheless remains relatively complex and costly. In some cases, closed reaction chambers, similar to those used in conventional ALD and CVD, are used. In other cases, like that described by the abovementioned document US 2009/0217878, the deposition is performed in the open air. In this latter case, the deposition head is a metallic structure of small dimensions (for example of the order of 40 cm3) but having a complex structure, comprising at least four independent gas distribution networks (two for the gas flows conveying the precursors, one for the separating inert gas, one for the discharging of the gases), and external couplings to gas intake or suction ducts. This head is composed of several parts, which must be manufactured, polished, assembled and welded with great precision.
The head of
The reference P1 denotes the inert gas charged with the first precursor (“O” in
Now, the pipes which bring the gases charged with precursor molecules must be saturated with precursors before the start of the actual deposition operations, then be purged before changing precursors to deposit new materials, which takes a lot of time and leads to a wastage of large quantities of precursors and a risk of cross-contamination. Furthermore, it is difficult to displace the head fixed to the pipes; it is therefore generally preferable to keep it fixed and displace the deposition substrate. That limits the choice of substrates that can be used; it is for example difficult, even impossible, to perform an atomic layer deposition on a portion of an object of large dimensions.
The invention aims to resolve, wholly or partly, the abovementioned problems and to render the AP-SALD technique more flexible, faster and less costly to implement.
In accordance with one aspect of the invention, that is obtained by the use of a deposition head produced in a single piece by additive manufacturing (“3D printing”). That allows for a reduction of costs, together with a wider choice of the materials that can be used (depending on the precursors to be delivered, a deposition head can be produced in metal, but also in ceramic, even in plastic material), a greater freedom in the forms that can be produced and a greater miniaturization. It thus becomes possible to manufacture “on demand” a deposition head optimized for a particular process and for the production of a particular layer or multilayer structure.
Documents US 2017/204989 and US 2017/372923 disclose gas distribution networks produced by additive manufacturing.
In accordance with another aspect of the invention, the bubblers can be brought close to the deposition head and mounted with it on a movable carriage. Thus, it is no longer the substrate which is displaced under a fixed deposition head, but the carriage bearing the deposition head and the bubblers—preferably miniaturized (less than 10 ml, for example 1 or 2 ml)—which is displaced over the substrate, which can thus be an object of large dimensions or, more generally, non-removable. The shortening of the gas intake ducts reduces the wastage of precursors and reduces the duration of the saturation and purging phase. Furthermore, the entire assembly can be heated to a uniform temperature, which is useful in the case of relatively non-volatile precursors. These miniaturized bubblers, for example produced by additive manufacturing, can be provided already pre-filled with the precursors, and thus form a “consumable” similar to an ink cartridge of a printer.
According to another embodiment, the bubblers can be produced in a single piece with the deposition head by additive manufacturing. The assembly formed by the deposition head and the bubblers, which can moreover be supplied already pre-filled with the precursors and form a “consumable”, allows, in certain cases, the purging phase to be dispensed with, and therefore the production of complex structures requiring several depositions of thin layers of different compositions to be simplified.
One subject of the invention is therefore a chemical vapor deposition head comprising a solid body comprising:
wherein each orifice linked to the first opening is separated from the or each closest orifice linked to the second opening by at least one orifice linked to the third opening and by two orifices linked to the fourth opening, arranged on either side of the orifice linked to the third opening;
characterized in that the solid body is produced in a single piece by additive manufacturing, the network of distribution ducts being formed by cavities formed in said piece.
According to particular embodiments of such a deposition head:
At least one said reservoir can be a bubbler whose hollow volume is intended to contain a precursor in the liquid state, the input duct and the output duct being arranged so that the gas flow injected into the input duct bubbles through the liquid before arriving at the output duct.
The hollow volume of said or each bubbler can contain a structure configured to lengthen the path traveled by the bubbles of gas between the input duct and the output duct.
Another subject of the invention is a vapor deposition system comprising such a head and a carriage bearing said head and allowing it to be displaced above a substrate.
Another subject of the invention is a vapor deposition system comprising such a head, a carriage bearing said head and allowing it to be displaced over a substrate and at least one first reservoir and one second reservoir, linked respectively to the first opening and to the second opening by respective output ducts, each said reservoir comprising a hollow volume capable of containing a precursor in the liquid or solid state and an input duct arranged so that a gas flow injected into the input duct enters into contact with the precursor before arriving at the respective output duct, the first reservoir and the second reservoir being also borne by said carriage. The reservoirs can be produced by additive manufacturing, mounted removably and interchangeably and each filled with one said precursor in the liquid or solid state. Alternatively, the reservoirs can be produced in a single piece with the solid body by additive manufacturing.
Yet another subject of the invention is a method for depositing at least one thin layer, or a thin-layered device, on a substrate comprising:
Said deposition process is advantageously performed spatially selectively on the substrate.
Other features, details and advantages of the invention will emerge on reading the description given with reference to the attached drawings given by way of example and which represent, respectively:
Contrary to the deposition head of
The head of
Several additive manufacturing techniques can be suitable for producing a deposition head according to the invention, dependent on the material used. Nonlimiting examples that can be cited include stereolithography and fused filament fabrication for the polymer materials, selective laser fusion for the metallic materials, selective laser sintering for the metals and ceramics, but also certain polymer materials, electron beam fusion for certain metals such as titanium.
The use of additive manufacturing techniques simplifies the production and the use of deposition heads specifically optimized for a deposition process, which is in turn specifically designed for the deposition of a layer or a particular multilayer structure. That is illustrated by
According to a preferred variant of the deposition head of
It will be noted that, in the system of slits of
It will also be noted that the system of slits F of
Until now, only cases in which the slits are continuous, rectilinear and parallel to one another (except for two slits FI “closing the ends” of the head, which are at right angles to the others). That is not however essential: the slits need not be strictly parallel and/or rectilinear. They can moreover be discontinuous, for example composed of several small orifices aligned and close together. Generally, a slit is understood to mean an orifice, or a set of orifices linked to one another, having a width very much greater (at least by a factor of 10) than its width. In some cases, the gases can be brought and/or discharged through orifices, at least some of which may not be considered as slits in the proper sense.
For example,
The additive manufacturing can also be used to manufacture the bubblers, which can moreover be incorporated in the deposition head. In this respect,
The bubbler BI1 also comprises a structure SAT, for example in helical form, suitable for lengthening the path of the bubbles inside the liquid so as to facilitate/ensure the saturation of the gas with molecules of the precursor. The helical form is not essential, the structure SAT could for example be in chicane form, or a porous or cross-linked structure (which makes smaller bubbles). The elements BI2 and BI3 need not be bubblers in the strict sense, but more simply reservoirs including a gas injection pipe and a discharge pipe (not represented), which are not necessarily arranged so as to allow a bubbling; the precursor can moreover be solid, for example in powder form, providing that it is sufficiently volatile. The bubblers, or some of them, can also include heating elements, for example electrical resistors or coils for a heated liquid, which can, if necessary, be produced in incorporated fashion by additive manufacturing.
According to another embodiment, the reservoirs and bubblers can be produced by additive manufacturing, but not be incorporated in the head. In this case, the head preferably comprises an accommodating seat allowing for a rapid mounting of the reservoirs, for example by pressure, which are thus interchangeable. These reservoirs can moreover be pre-filled with precursor, in the manner of printer ink cartridges.
Whether they are incorporated or not, the reservoirs/bubblers produced by additive manufacturing typically have a content smaller than 10 ml, for example between 1 and 2 ml. There are on the market electric valves that are small enough to be compatible with such reservoirs.
The miniaturization made possible by the use of additive manufacturing techniques thus allows the reservoirs to be close to the print head. Because of the small volumes involved, that is not dangerous even in the presence of flammable precursors. As has been explained above, that makes it possible to reduce the wastage of precursors, to substantially reduce the duration of the purging phases and to reduce the risks of contamination. That also makes it possible to more radically modify the structure and the operation of an AP-SALD deposition system by mounting the assembly formed by the deposition head TD and the reservoirs/bubblers B1, B2 (incorporated or not) on a carriage CM that can be displaced over a substrate which is kept stationary—contrary to the mode of operation of the conventional system described above with reference to
The embodiment of
The invention is particularly suited to the selective deposition of SALD type. As indicated previously, a deposition head as represented in
The invention has been described with reference to its application to the AP-SALD technique, but it can also be suitable for implementing other methods of CVD type.
Number | Date | Country | Kind |
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1857072 | Jul 2018 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/070450 | 7/30/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2020/025593 | 2/6/2020 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4389973 | Suntola et al. | Jun 1983 | A |
5545436 | Saito | Aug 1996 | A |
20030113451 | Mayer | Jun 2003 | A1 |
20050066893 | Soininen | Mar 2005 | A1 |
20090081886 | Levy et al. | Mar 2009 | A1 |
20090217878 | Levy et al. | Sep 2009 | A1 |
20100041213 | Lee | Feb 2010 | A1 |
20100186800 | Baker | Jul 2010 | A1 |
20170204989 | Burkhart et al. | Jul 2017 | A1 |
20170252756 | Iizuka | Sep 2017 | A1 |
20170372923 | Terada et al. | Dec 2017 | A1 |
Number | Date | Country |
---|---|---|
101578391 | Nov 2009 | CN |
101809193 | Aug 2010 | CN |
7-12475 | Feb 1995 | JP |
2002-367911 | Dec 2002 | JP |
2011-66166 | Mar 2011 | JP |
Entry |
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International Searching Authority, International Search Report (ISR) and Written Opinion received for International Application No. PCT/EP2019/070450, dated Oct. 10, 2019, 14 pages, European Patent Office, Netherlands, ISR Only. |
Muñoz-Rojas, David, et al., “Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics”, Material Horizons 2014, vol. 1, No. 3, pp. 314-320, Royal Society of Chemistry, UK. |
Chinese Office Action issued in Chinese Patent Application No. 201980050597.1 mailed Sep. 15, 2022, with English translation. |
Number | Date | Country | |
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20210140047 A1 | May 2021 | US |