KR20130091735A - Organic vapor jet printing - Google Patents

Abstract

The present invention provides a method of depositing an organic material. The present invention provides a chamber in which a substrate is disposed. A first gas from nozzles 422 and 462 directed to the substrate; And depositing the organic material on the substrate by injecting a vapor of the organic material carried by the first gas. During the deposition of the organic material, a second gas is provided in the chamber. The flow rate of the second gas is at least 5% of the sum of the flow rates of all the gases flowing into the vacuum chamber. The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas. A second gas is provided in the chamber through holes 424 and 464 away from the nozzle.

Description

Organic vapor jet printing {ORGANIC VAPOR JET PRINTING}

The claimed invention includes the Regents of the University of Michigan, Princeton University, The University of Southern California, and Universal on a joint university corporation research agreement. In connection with, and / or on behalf of, one or more of the parties of the Universal Display Corporation. This Agreement shall enter into force on and before the date of the claimed invention, and the claimed invention is made as a result of the activities performed within the scope of this contract.

Field of technology

The present invention relates to organic vapor jet printing (OVJP).

Optoelectronic devices using organic materials are becoming increasingly useful for a variety of reasons. Many of the materials used to fabricate such devices are relatively inexpensive, so organic optoelectronic devices have a cost advantage over inorganic devices. In addition, the inherent properties of the organic materials, such as their flexibility, may allow the organic materials to be well suited for certain applications, such as manufacturing on flexible substrates. Examples of organic optoelectronic devices include organic light emitting devices (OLEDs), organic phototransistors, organic photovoltaic cells and organic photodetectors. In the case of OLEDs, organic materials may have a performance advantage over conventional materials. For example, the wavelength at which the organic emitting layer emits light can generally be easily adjusted by appropriate dopants.

OLEDs use organic thin films that emit light when voltage is applied to the device. OLEDs are becoming a growing technology for use in applications such as flat panel displays, lighting and backlighting. Some OLED materials and configurations are described in US Pat. Nos. 5,844,363, 6,303,238 and 5,707,745, which are incorporated by reference in their entirety.

One way to deposit OLEDs and other organic devices is ORGANIC VAPOR JET Printing (OVJP). The general principles of OVJP are U.S. Patent 7,404,862 (registered July 29, 2008), U.S. Patent 7,744,957 (registered June 29, 2010), U.S. Patent 7,431,968 (registered October 7, 2008), US Patent No. 7,722,927, registered May 25, 2010, and US Patent Application No. 12 / 034,683, filed February 21, 2008, all of which are incorporated by reference.

As used herein, the term "organic" includes polymeric materials as well as small molecule organic materials that can be used to make organic optoelectronic devices. "Small molecule" means any organic material that is not a polymer, and "small molecules" can actually be very large. Small molecules may contain repeat units in some circumstances. For example, using a long chain alkyl group as a substituent does not remove a molecule from the "small molecule" class. Small molecules may also be introduced into the polymer, for example as pendant groups on the polymer backbone or as part of the backbone. Small molecules can also serve as the core moiety of a dendrimer, which consists of a series of chemical shells built on the core moiety. The core moiety of the dendrimer may be a fluorescent or phosphorescent small molecule emitter. Dendrimers can be "small molecules," and all dendrimers currently used in the field of OLEDs are known to be small molecules.

As used herein, "top" means farthest from the substrate, and "bottom" means closest to the substrate. When the first layer is described as "disposed over" the second layer, the first layer is disposed farther from the substrate. Unless the first layer is described as "in contact with" the second layer, there may be another layer between the first layer and the second layer. For example, the cathode may be described as "disposed over" the anode, even though various organic layers are present therebetween.

More details about the OLED and the definitions described above can be found in US Pat. No. 7,279,704, which is incorporated by reference in its entirety.

The present invention provides a method of depositing an organic material. The present invention provides a chamber in which a substrate is disposed. A first gas from a nozzle directed to the substrate; And depositing the organic material on the substrate by injecting a vapor of the organic material carried by the first gas. During the deposition of the organic material, a second gas is provided in the chamber. The flow rate of the second gas is at least 5% of the sum of the flow rates of all the gases flowing into the vacuum chamber. The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas. A second gas is provided in the chamber through a hole remote from the nozzle.

Preferably, the flow rate of the second gas is at least 30% of the sum of the flow rates of all gases flowing into the vacuum chamber. More preferably, the flow rate of the second gas is at least 60% of the sum of the flow rates of all the gases flowing into the vacuum chamber.

Preferably, during the deposition of the organic material, the total pressure in the vacuum chamber is between 1 mTorr and 1 Torr.

The first gas is preferably N ₂ . The second gas is preferably selected from the group consisting of Ar, Kr, Freon, Xe, CO ₂ and WF ₆ .

The second gas may be a single material. The second gas may be a mixture of different gases, each having a molecular weight of at least 20% greater than the molecular weight of the first gas.

The second gas preferably has a molecular weight that is at least 100% greater than the molecular weight of the first gas. The second gas may each be a mixture of materials having a molecular weight that is at least 100% greater than the molecular weight of the first gas.

The chamber may be a vacuum chamber.

The present invention provides a method of depositing an organic material. The present invention provides a chamber in which a substrate is disposed. A first gas from a nozzle directed to the substrate; And depositing the organic material on the substrate by injecting a vapor of the organic material carried by the first gas. During the deposition of the organic material, a second gas is provided in the chamber. The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas. A second gas is provided in the chamber through a hole remote from the nozzle. The nozzle has a hole with a minimum dimension. The organic material is deposited onto the substrate as a patterned feature having a shape defined by the shape of the hole. The partial pressure of the second gas in the chamber during the deposition of the organic material doubles the amount of organic material deposited at a distance of one minimum dimension from the edge of the patterned feature, compared to the same deposition but performed without the second gas. Enough to make

Figure 1 shows an organic light emitting device.
2 shows an inverted organic light emitting device that does not have a separate electron transport layer.
3 is a cross-sectional view of four different nozzle geometries taken in a direction perpendicular to the gas flow.
4 shows two chambers in which material is deposited, one chamber having light ambient gas and the other chamber having heavy ambient gas.
5 shows a plot of the emission rate versus distance from the deposition edge providing a measure of how much overspray occurs during deposition.

In general, an OLED comprises one or more organic layers disposed between and electrically connected to the anode and the cathode. When a current is applied, the anode injects holes in the organic layer and the cathode injects electrons. The injected holes and electrons move to oppositely charged electrodes. When electrons and holes are localized in the same molecule, "excitons", which are localized electron-hole pairs with an excited energy state, are formed. Light is emitted when the excitons relax through the photoelectron emission mechanism. In some cases, excitons can be localized to excimers or exciplexes. Non-radiative mechanisms such as thermal relaxation may also occur, but are generally considered undesirable.

Figure 1 shows an organic light emitting device 100. This figure does not necessarily have to be drawn to scale. The device 100 includes a substrate 110, an anode 115, a hole injection layer 120, a hole transport layer 125, an electron blocking layer 130, a light emitting layer 135, a hole blocking layer 140, an electron It may include a transport layer 145, an electron injection layer 150, a protective layer 155, and a cathode 160. Cathode 160 is a compound cathode having a first conductive layer 162 and a second conductive layer 164. The device 100 can be fabricated by depositing the layers described in order. The properties and functions of these various layers, and example materials, are described in more detail in US Pat. No. 7,279,704, column 6-10, which is incorporated by reference.

More examples of each of these layers are available. For example, flexible and transparent substrate-anode combinations are disclosed in US Pat. No. 5,844,363, which is incorporated by reference in its entirety. An example of a p-doped hole transport layer is m-MT data doped with F ₄ -TCNQ at a molar ratio of 50: 1 as disclosed in US Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of release and host materials are disclosed in US Pat. No. 6,303,238 (Thompson et al), incorporated by reference in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li in a molar ratio of 1: 1 as disclosed in US Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. U.S. Patents 5,703,436 and 5,707,745, incorporated by reference in their entirety, disclose examples of cathodes, including compound cathodes having a thin metal layer, such as Mg: Ag, with underlying transparent, electrically conductive, sputter deposited ITO layers. do. The theory and use of barrier layers is described in more detail in US Pat. No. 6,097,147 and US Patent Application Publication No. 2003/0230980, which is incorporated by reference in its entirety. Examples of injection layers are provided in US Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety. A description of the protective layer can be found in US Patent Application Publication No. 2004/0174116, which is incorporated by reference in its entirety.

2 shows an inverted OLED 200. The device includes a substrate 210, a cathode 215, a light emitting layer 220, a hole transport layer 225, and an anode 230. Device 200 can be fabricated by sequentially depositing the described layers. Since the most common OLED configuration has a cathode disposed above the anode, and the device 200 has a cathode 215 disposed below the anode 230, the device 200 may be referred to as an "inverted" OLED. Materials similar to those described with respect to device 100 may be used in the corresponding layer of device 200. 2 provides an example of how some layers may be omitted from the structure of device 100.

The simple layered structures illustrated in FIGS. 1 and 2 are provided by way of non-limiting example, and it should be understood that embodiments of the present invention can be used in connection with a wide variety of other structures. The specific materials and structures described are exemplary in nature and other materials and structures may be used. Functional OLEDs may be achieved by combining the various layers described in different ways, or may omit layers entirely based on design, performance, and cost factors. Other layers not specifically described may also be included. Materials other than those specifically described may be used. Although many of the examples provided herein describe various layers as comprising a single material, it should be understood that combinations of materials, such as mixtures of hosts and dopants, or more generally any mixture, may be used. Also, the layers can have various sublayers. The names given to the various layers herein are not intended to be strictly limiting. For example, in device 200, hole transport layer 225 transports holes to light emitting layer 220 to inject holes, which may be described as a hole transport layer or a hole injection layer. In one embodiment, an OLED can be described as having an "organic layer" disposed between the cathode and the anode. This organic layer may comprise a single layer or may further comprise a plurality of layers of different organic materials, for example as described in connection with FIGS. 1 and 2.

Structures and materials not specifically described, such as OLEDs made of polymeric materials (PLEDs) as disclosed in US Pat. No. 5,247,190 (Friend et al., Incorporated by reference in its entirety), can also be used. As a further example, OLEDs with a single organic layer can be used. OLEDs can be stacked, for example, as described in US Pat. No. 5,707,745 to Forrest et al., Incorporated by reference in its entirety. The OLED structure may deviate from the simple layered structure illustrated in FIGS. 1 and 2. For example, the substrate may be an angled reflective surface to improve out-coupling, such as described in US Pat. No. 6,091,195 (Forrest et al., Incorporated herein by reference in its entirety). Such mesa structures and / or pit structures as described in US Pat. No. 5,834,893 (Bulovic et al., Incorporated by reference in its entirety).

Unless stated otherwise, any of the layers of the various embodiments may be deposited by any suitable method. For organic layers, preferred methods are thermal vapor deposition (thermal evaporation), ink jets, such as those described in US Pat. Nos. 6,013,982 and 6,087,196, incorporated by reference in their entirety, OVPD (ogranic vapor phase deposition) For example, as described in US Pat. No. 6,337,102 (Forrest et al., Which is incorporated by reference in its entirety) and by deposition by organic vapor jet printing, such as US Pat. Incorporated in the literature). Other suitable deposition methods include spin coating and other solution based processes. It is preferable to carry out this solution based process in nitrogen or an inert atmosphere. For other layers, the preferred method involves thermal evaporation. Preferred patterning methods include deposition through a mask, cold welding, such as those described in US Pat. Nos. 6,294,398 and 6,468,819 (incorporated by reference in their entirety), and in conjunction with some of the deposition methods, such as ink jet and OVJD. Pattern formation. Other methods can also be used. The material to be deposited can be modified to make it compatible with a particular deposition method. For example, substituents such as alkyl and aryl groups that are branched or unbranched, preferably containing three or more carbons, can be used in small molecules to improve the ability to withstand soul processing. Substituents having 20 or more carbons can be used, and 3 to 20 carbons is a preferred range. Materials having an asymmetric structure may have better solution processability than having a symmetric structure because the asymmetric material may have a lower tendency to recrystallize. Dendrimer substituents can be used to improve the performance of small molecules that can withstand solution processing.

Devices manufactured according to embodiments of the present invention may be used for flat panel displays, computer monitors, televisions, billboards, lights for internal or external lighting and / or signaling, heads-up displays, fully transparent displays, flexible displays, laser printers. It can be used in a wide variety of consumer products, including telephones, cell phones, personal digital assistants, laptop computers, digital cameras, camcorders, viewfinders, microdisplays, vehicles, large area walls, theater or playground screens, or signage. have. Various control mechanisms can be used to control devices made in accordance with the present invention, including passive and active matrices. Many devices are intended for use at temperatures that may be comfortable to humans, such as 18 ° C. to 30 ° C., more preferably at room temperature (20-25 ° C.).

The materials and structures described herein may have use in devices other than OLEDs. For example, other optoelectronic devices such as organic solar cells and organic photo detectors may utilize the materials and structures. More generally, organic devices, such as organic transistors, can utilize the materials and structures.

Organic vapor jet printing (OVJP) is a preferred method for depositing organic materials in many situations. OVJP is a deposition of organic molecules of a shape or pattern defined by nozzles in which jets are formed that do not use masks, photoresists, or similar patterning techniques, based on blocking or hiding of portions of the substrate where deposition is undesirable. Can be allowed.

Generally, the nozzle or nozzles of the OVJP system are in fluid communication with a source of organic molecules and a source of carrier gas.

As used herein, a "nozzle" is a mechanism that directs, directs, or otherwise controls the flow of material after leaving the mechanism.

Some, but not all, OVJP systems involve deposition in a chamber. Many OVJP systems also include a substrate holder adapted to support the substrate under the nozzle and move relative to the nozzle. The nozzle, substrate holder, or both can be moved. When using a chamber, the nozzle and substrate holder may be in the chamber. The use of the chamber allows for better control of ambient conditions such as background pressure, gas composition, and temperature. As used herein, “under” a nozzle means that the nozzle is positioned in the direction that the nozzle points, ie, on the substrate. The nozzles can be oriented in any number of directions on the substrate.

OVJP is demonstrated in practice by using a single carrier gas (usually nitrogen) to transport organic vapor from a nozzle deposited over a substrate very close to the nozzle, creating a thin film having a lateral dimension determined by the size of the nozzle. It is often simply stated that the width of the deposited thin film is the same as the size of the nozzle, but in a more complex analysis it is recognized that, in the absence of a physical mask on the substrate, less than 100% of organic molecules injected from the nozzle are deposited under the nozzle itself. . The material that deposits outside of the nozzle area is called "hyperspray". Given the sensitivity of the organic device to contamination (especially the sensitivity of the organic light emitting device to the presence of lower exciton energy luminescent molecules), a small amount (less than 0.1%) of overspray will be a problem. Therefore, it is desirable to minimize overspray.

It is already known that the addition of a coaxial stream of organic glass gas (known “monitoring flow”) of nozzle attention can reduce overspray, see US Pat. No. 7,744,957. However, coaxial placement adds complexity to the OVJP nozzle. Disclosed herein is a simpler method of reducing overspray achieved by simply introducing into a deposition chamber by a "blanket" gas having a significantly greater atomic mass than the carrier gas.

Figure 3 shows a cross section of four different nozzle geometries taken from holes in a direction perpendicular to the gas flow. Arrows in each hole indicate the "minimum dimension" of the hole. Mathematically, at the minimum dimension, the arrow length is constant at the local maximum (for the rectangle, oval and triangle) or constant (for the rectangle) with respect to translation of the entire arrow in the direction perpendicular to the arrow, The "smallest" dimension is at or near the smallest local maximum (if it occurs). 3 shows cross sections of holes 310, 320, 330 and 340 having circular, elliptical, rectangular and triangular cross sections, respectively. Rectangular holes are the most preferred shape for the deposition line and are also relatively easy to obtain in nozzles etched in silicon. However, other shapes can be used.

The present invention provides a method of depositing an organic material. The present invention provides a chamber in which a substrate is disposed. A first gas from a nozzle directed to the substrate; And depositing the organic material on the substrate by injecting a vapor of the organic material carried by the first gas. During the deposition of the organic material, a second gas is provided in the chamber. The flow rate of the second gas is at least 5% of the sum of the flow rates of all the gases flowing into the vacuum chamber. The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas. A second gas is provided in the chamber through a hole remote from the nozzle.

Preferably, the flow rate of the second gas is at least 30% of the sum of the flow rates of all gases flowing into the vacuum chamber. More preferably, the flow rate of the second gas is at least 60% of the sum of the flow rates of all the gases flowing into the vacuum chamber.

(See FIG. 5 and related discussion) The presence of a second gas, which may be referred to as a "blanket" gas, has been demonstrated to reduce overspray compared to the method where only carrier gas is present instead of heavier blanket gas. One feature of the second gas is that it is introduced into the chamber through a hole remote from the nozzle. By "distant" from the nozzle it is meant that the hole into which the blanket gas is introduced is at least two "minimum dimensions" of the nozzle hole from the nozzle hole. In most embodiments, the hole into which the blanket gas is introduced will be farther away. The blanket gas is, in most common embodiments thereof, different from the "monitoring flow" introduced into the chamber through an annular ring around the nozzle into which the carrier gas is introduced, ie the specific location at which the monitoring flow is introduced is injected from the nozzle. This is important for the fluid dynamics of the gases being In its purest sense, the specific location at which the "blanket gas" is introduced is not critical, since the presence of the blanket gas in the ambient gas of the chamber affects the fluid dynamics of the gas injected from the nozzle, which results in a narrower jet spread. Because it is generated. As a result, the use of heavy blanket gas may be easier to implement than the use of supervised flow.

"Heavy" as used herein means that the blanket (or second) gas has a molecular weight that is at least 20% greater than the molecular weight of the carrier (or first) gas. Molecular weights greater than 20% are expected to have the effect as demonstrated in connection with FIG. 5 and related experiments, since Ar has a molecular weight of 18 compared to the molecular weight of 14 of N ₂ . From the point of view of narrowing the jet spread, the heavier the blanket gas compared to the carrier gas, the better. The molecular weight is preferred for the blanket gas that is at least 100% larger than the molecular weight of the carrier gas.

It is preferred that the blanket gas is inert in terms of device performance. The blanket gas should not react with the material in the device being manufactured. Suitable inert and heavy suitable gases include Ar, Kr, Freon, Xe, CO ₂ and WF ₆ . Since N ₂ is inert and light, it is preferable to use N ₂ as the first gas. He can also be used as a carrier gas, opening up new possibilities for "heavy" blanket gases. For example, N ₂ is heavier than He, and when He is a carrier gas, N ₂ can be used as the blanket gas.

The blanket gas may be a single gas that meets the weight criteria, or it may be a mixture of gases that each meet the weight criteria, and is 20% or 100% greater than the molecular weight of the carrier gas. This is desirable for the simplicity of using a single gas, and since the blanket gas consists of molecules that are heavier than the carrier gas, the blanket gas has its desired effect, which effect must occur whether all of the blanket gas molecules are the same or not the same.

This is expected in most embodiments where the carrier gas is a single gas, preferably N ₂ . However, embodiments of the present invention may be practiced with a carrier gas having multiple gas components. In this situation, the "molecular weight" of the carrier gas should be thought of as the molar average molecular weight.

Preferably, during the deposition of the organic material, the total pressure in the vacuum chamber is between 1 mTorr and 1 Torr. This is generally the preferred range of pressure for OVJP. OVJP, including OVJP by the use of blanket gases, can also be run at higher and lower pressures. However, lower pressures than the lower limit of this range are less desirable because, by their nature, OVJP introduces gas into the chamber during deposition, so lower vacuum levels are most expensive compared to similar vacuum levels in other processes such as thermal evaporation. This can require vacuum equipment. Higher pressures are readily available, but the carrier gas must generally be removed so that deposition can take place over time in a controlled equilibrium in the chamber, and it is reasonably easy to obtain a 1 Torr pressure.

The chamber is preferably a vacuum chamber. However, there are embodiments of OVJP that can be carried out at atmospheric or higher pressures, and the use of blanket gas would be applicable to this embodiment.

One way of quantifying the amount of blanket gas in the chamber is by flow rate. In equilibrium, the relative flow rates of the various gases introduced into the chamber are expected to correspond to the partial pressures of the gas at a location remote from any opening into which the gas is introduced, ie the "ambient" gas in the chamber. However, the flow rate is much easier to control and measure than partial pressure.

Another way of quantifying the amount of blanket gas in the chamber is by measuring the effect of hyperspray. One goal of embodiments of the present invention with respect to OLEDs is to reduce the amount of impurity molecules in adjacent devices having different structures and usually emitting different colors of light. If the impurity molecule is emissive in a device believed to be an impurity, it is reasonably easy to quantify the amount of impurity present by measuring the emission of the device. The experiment of FIG. 5 shows that the normal amount of blanket gas is free of blanket gas, but the same overall pressure can reasonably reduce the amount of impurities compared to the same (and resulting from the presence of carrier gas). In general, the nozzles used in OVJP have a "minimum dimension" described in connection with FIG. One way to quantify whether the blanket gas has a sufficient partial pressure to have the desired effect is to compare the OVJP performed by the use of the blanket gas against the OVJP running only at the same overall pressure at which the carrier gas is present. Is to carry out an experiment. This can be done as described with respect to FIG. 5. The effect of overspray can be measured at a distance of one minimum dimension from the edge of the patterned feature. During partial deposition of the organic material, the partial pressure of the second gas in the chamber reduces the amount of organic material deposited at a distance of one minimum dimension from the edge of the patterned feature, by a factor of two, compared to the same deposition except that performed without the second gas. Is sufficient, the blanket gas can be said to have a significant effect. As illustrated with respect to FIG. 5, this effect is reasonably easy to achieve with moderate amounts of blanket gas.

Preferably OVJP is carried out in a relatively poor vacuum, typically at 1 mTorr to 1 Torr, although embodiments from higher vacuum levels to atmospheric or higher pressures are possible. Thus, there may be an acceptable partial pressure of residual gas in the vacuum chamber seen by the organic molecules after the organic molecules have been carried through the nozzle by the carrier gas. Within this limit, some combination of pressure and carrier gas flow rate produces a minimum amount of overspray.

Embodiments of the invention include further reducing overspray by intentionally introducing a partial pressure of gas heavier than the carrier gas into the deposition chamber. This heavier gas may be referred to as a "blanket" gas. The heavier gas limits the expansion of the carrier gas and the organic vapors exiting the nozzle better than the carrier gas. In certain exemplary embodiments, the carrier gas is nitrogen and the chamber is filled with a partial pressure of argon. The overspray when the chamber contains argon is somewhat less than the overspray when the chamber contains only nitrogen introduced by the carrier gas.

There may be an optimal total pressure for the Ar blanket which may differ from the optimal pressure using only N ₂ , and it may be desirable to determine this optimal total pressure. The optimum total pressure can easily be determined by performing a series of depositions at different total pressures and measuring the results. This is done routinely for regular OVJP without blanket gas, and should be equally routine for OVJP by blanket gas.

If reducing overspray is the only consideration, it is preferable to use the heaviest possible blanket gas. However, other factors must be considered in selecting the blanket gas, for example cost, toxicity and environmental effects must also be considered. The blanket gas should also be inert, ie it should not deleteriously interact with any part of the organic device. In terms of gases preferred for use as blanket gases due to their high molecular weight, preferred choices include Kr, complex gas molecules such as CF ₄ , C ₂ F ₆ and higher order Freons, Xe, CO ₂ and WF ₆ . It is expected that the overspray when heavy blanket gas is present is reduced compared to the same overall pressure when only carrier gas is present. However, it is expected that each blanket / carrier gas combination may have a different partial pressure where overspray is minimized, which can be determined by a relatively simple experiment.

One consideration of using exotic gases for blanket OVJP deposition is potentially expensive. Fresh blanket gas is preferably continuously introduced to offset the carrier gas coming from the nozzle, otherwise the deposition chamber is eventually filled with the carrier gas. This means that over time, a significant volume of blanket gas can be used and cost and / or disposal must be considered.

Embodiments of the invention can be practiced over a wide variety of dimensions. The use of heavy ambient gas can be advantageously used in any dimension desired for the OVJP system.

A simple single nozzle implementation of an embodiment of the present invention is shown in FIG. 4 shows systems 410 and 450. System 410 includes a chamber 420 having an OVJP nozzle 422, an aperture 424 for introduction of blanket gas, and an aperture 426 for removal of gas from chamber 420. A vacuum system can be attached to the hole 426. Nozzle 422 is abstractly illustrated as introducing a jet of gas 430 from which gas flows out of the chamber from a source. It is to be understood that any of a variety of known systems, including nozzles, in OVJP may be used. System 410 shows a wider jet spread when light ambient gas is present.

System 450 includes a chamber 460 having an OVJP nozzle 462, a hole 464 for introduction of blanket gas, and a hole 466 for removal of gas from chamber 460. A vacuum system can be attached to the aperture 466. Nozzle 462 is abstractly illustrated as introducing a jet of gas 470 from which gas flows out of the chamber from a source. It is to be understood that any of a variety of known systems, including nozzles, in OVJP may be used. System 450 shows a narrower jet spread when heavy ambient gas is present.

One-dimensional arrays of nozzles (ie, lines of nozzles) are preferred embodiments for nozzle blocks. Such an array allows for high throughput patterning by moving the nozzle relative to the substrate or vice versa by moving the nozzle perpendicular to the line of the nozzle. Other arrangements of multiple nozzles, such as two dimensional arrays, may also be used. Various nozzle shapes can be used. For example, the nozzle can be extended, for example rectangular, with the long axis preferably in the translation direction of the array relative to the substrate.

Embodiments of the invention can generally be practiced in combination with other techniques for OVJP or enhanced OVJP. For example, embodiments of the invention can be practiced in combination with off-gas located in a nozzle block that produces a local vacuum as disclosed in US patent application Ser. No. 11 / 643,795 (incorporated by reference).

5 shows a plot of emission rate versus distance from the deposition edge, which provides a measure of how much overspray occurs during deposition. Different deposition conditions show the effect of heavy blanket gas on deposition through OVJP, specifically reduction of overspray through the use of heavy blanket gas. NPD / TPBi two-layer devices are grown via vacuum thermal deposition (VTE) over a 6 "glass substrate patterned with a 1 mm wide ITO anode with 0.5 mm separation between lines. The device is characterized by charge injection and transport characteristics. In the absence of contamination, the resulting device shows a blue EL from the NPD.The OVJP along one of the ITO lines between the blanket VTE depositions of NPD and TPBi. Deposit a thin line of red dopant, the deposited line showing red electroluminescence due to effective exciton transport to the red dye Any hyperspray of the red dye behind the deposited ITO strip is also deposited at that location Shows a slight level of red emission depending on the amount of red dye, with peaks in the electroluminescence spectrum due to red dye and default NPD emission The highly separable and ratio of red and blue peaks quantitatively limits the amount of red dye present and corrects it using controlled VTE deposition of the test structure Effective confinement and down energy of excitons in organic heterogeneous interfaces Because of the high efficiency of the transport, the structure is very sensitive to the presence of hyperspray used to detect less than 0.25 kPa of material, or about 1/10 of a monolayer.

Experimental setup is somewhat limited. Schematically, the OVJP portion of device fabrication is performed in a chamber as shown in FIG. The chamber is a vacuum chamber, but the vacuum does not have a variable valve, ie the vacuum is turned on or off without setting in between. Considering when the vacuum is on, the total pressure in the chamber is determined by the flow rates of the carrier gas and the blanket gas. The chamber has a single pressure measuring device capable of measuring the total pressure in the chamber.

5 shows the following: N ₂ at 0.1 Torr shows a calibration run to determine the total pressure (0.1 Torr) when the carrier gas flow rate is set to a specific amount, and the only gas allowed in the chamber Is the carrier gas through the nozzle. This figure shows less overspray because the total pressure is lower and is not comparable to other figures for the purpose of measuring the effect of whether the ambient gas is the same as the carrier gas or comprises a heavier blanket gas. The two figures for N ₂ at 0.3 Torr, Ar blanket are the same experiment, where the flow rate of N ₂ carrier gas is the same as for N ₂ at 0.1 Torr, but Ar gas is also through a hole far from the nozzle Is allowed in the chamber. The flow rate of Ar is sufficient to reach a total pressure of 0.3 Torr. The two figures for N ₂ in a 0.3 Torr, N ₂ blanket are the same experiments, in which N ₂ gas instead of Ar gas is allowed into the chamber through a hole away from the nozzle, so that the total pressure is 0.3 Torr or less. Except that is the same experiment performed in the same manner as the Ar blanket experiment. The data shows less overspray using an Ar blanket at 0.3 Torr than using the default N ₂ blanket at the same pressure.

The smallest amount of overspray shown in FIG. 5 is for the calibration run in the absence of blanket gas. Both results with blanket gas showed more overspray than deposition at 0.1 Torr using the default N ₂ blanket. However, due to the limited nature of the experimental apparatus, 0.1 Torr is the minimum achievable pressure with flow through the nozzle, and any blanket gas adds pressure, so that the limited apparatus can be tested by Ar blanket at a total pressure of 0.1 Torr. Can't. A related comparison shows that 0.3 Torr, N ₂ in an Ar blanket (or heavier ambient gas (or more precisely, ambient gas due to heavy gas at least a significant partial pressure) reduces overspray compared to lighter ambient gas at the same pressure). 0.3 Torr, N ₂ in an N ₂ blanket. This is the true case where the presence of heavy gas is achieved through introduction into the chamber through a hole far from the nozzle.

It is understood that the various embodiments described herein are described by way of example only and are not intended to limit the scope of the invention. For example, many of the materials and structures described herein may be replaced with other materials and structures without departing from the scope of the present invention. As will be apparent to those skilled in the art, the claimed invention may therefore comprise modifications from the specific examples and preferred embodiments described herein. It is understood that various theories as to how the invention works are not intended to be limiting.

Claims (12)

Providing a chamber in which the substrate is located;
From the nozzle to the substrate
A first gas; And
Vapor of organic material carried by the first gas
Depositing an organic material on the substrate by spraying:
Providing a second gas, within the chamber, during deposition of the organic material
As a method comprising;
The flow rate of the second gas is at least 5% of the sum of the flow rates of all gases flowing into the vacuum chamber;
The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas;
And the second gas is provided in the chamber through a hole remote from the nozzle. The method of claim 1, wherein the flow rate of the second gas is at least 30% of the sum of the flow rates of all gases flowing into the vacuum chamber. The method of claim 1, wherein the flow rate of the second gas is at least 60% of the sum of the flow rates of all gases flowing into the vacuum chamber. The method of claim 1, wherein during the deposition of the organic material, the total pressure in the vacuum chamber is between 1 mTorr and 1 Torr. The method of claim 1, wherein the first gas is N ₂ . The method of claim 1, wherein the second gas is selected from the group consisting of Ar, Kr, Freon, Xe, C0 ₂ and WF ₆ . The method of claim 1, wherein the second gas is a single material. The method of claim 1 wherein the second gas has a molecular weight that is at least 100% greater than the molecular weight of the first gas. The method of claim 1, wherein the second gas is each a mixture of materials having a molecular weight of at least 20% greater than the molecular weight of the first gas. The method of claim 1, wherein the second gas is a mixture of materials, each having a molecular weight of at least 100% greater than the molecular weight of the first gas. The method of claim 1, wherein the chamber is a vacuum chamber. Providing a chamber in which the substrate is located;
From the nozzle to the substrate
A first gas; And
Vapor of organic material carried by the first gas
Depositing an organic material on the substrate by spraying:
Providing a second gas, within the chamber, during deposition of the organic material
As a method comprising;
The second gas has a molecular weight of at least 20% greater than the molecular weight of the first gas;
The nozzle has a hole with a minimum dimension;
The organic material is deposited on the substrate as a patterned feature having a shape defined by the shape of the hole;
The partial pressure of the second gas in the chamber during the deposition of the organic material doubles the amount of organic material deposited at a distance of one minimum dimension from the edge of the patterned feature, as compared to the same deposition but performed without the second gas. How to be sufficient.

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