CN109642309B

CN109642309B - High-precision shadow mask deposition system and method

Info

Publication number: CN109642309B
Application number: CN201780042868.XA
Authority: CN
Inventors: M·阿南丹; A·高希; F·瓦然; E·多诺霍; I·哈尤林; T·阿里; K·泰斯
Original assignee: Emagin Corp
Current assignee: Emagin Corp
Priority date: 2017-05-17
Filing date: 2017-07-24
Publication date: 2021-08-17
Anticipated expiration: 2037-07-24
Also published as: JP2019517623A; CN109642309A; TW201900901A; KR102378672B1; JP7134095B2; KR20200008936A; TWI737795B

Abstract

A direct deposition system for forming a high resolution pattern of material on a substrate is disclosed. Vaporized atoms from an evaporation source are passed through a pattern of through holes of a shadow mask to deposit on the substrate in a desired pattern. The shadow mask is held in a mask chuck that enables the shadow mask and the substrate to be separated by a distance that can be less than 10 microns. Before reaching the shadow mask, the vaporized atoms pass through a collimator that operates as a spatial filter that blocks any atoms that do not travel in a direction nearly perpendicular to the substrate surface. Vaporized atoms passing through the shadow mask exhibit little or no lateral spreading after passing through the via, and the material is deposited on the substrate in a pattern with very high fidelity to the via pattern of the shadow mask.

Description

High-precision shadow mask deposition system and method

Statement of related cases

Priority is claimed for U.S. provisional patent application serial No. 62/340,793 (attorney docket No. 6494-208PR1), filed on 24/5/2016, which is hereby incorporated by reference in its entirety. Priority is also claimed for U.S. non-provisional patent application No. 15/597,635 (attorney docket No. 6494-208US1) applied on day 17, 5/2017 and No. 15/602,939 (attorney docket No. 6494-209US1) applied on day 23, 5/2017, both of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates generally to thin film deposition, and more particularly, to evaporation-based thin film deposition.

Background

Shadow mask based deposition is a process of depositing a layer of material onto the surface of a substrate such that a desired pattern of the layer is defined during the deposition process itself. This deposition technique is sometimes referred to as "direct patterning".

In a typical shadow mask deposition process, the desired material is vaporized at a source at a distance from the substrate, with the shadow mask positioned between the source and the substrate. As the vaporized atoms of the material travel toward the substrate, they pass through a set of through holes in a shadow mask positioned directly in front of the substrate surface. The vias (i.e., pores) arrange the material in a desired pattern on the substrate. Thus, the shadow mask blocks all vaporized atoms except those passing through the through-holes, which are deposited on the substrate surface in a desired pattern. Deposition based on shadow masks is similar to the screen technology used to form patterns (e.g., jersey numbers, etc.) on articles of clothing or stencils used to develop artwork.

Shadow mask based deposition has been used in the Integrated Circuit (IC) industry for many years to deposit patterns of material on substrates, due in part to the fact that it avoids the need to pattern a layer of material after it is deposited. Thus, its use does not require exposing the deposited material to harmful chemicals (e.g., acidic etchants, caustic lithographic development chemicals, etc.) to pattern it. In addition, shadow mask based deposition requires less handling and processing of the substrate, thereby reducing the risk of substrate damage and increasing manufacturing yield. Furthermore, many materials, such as organic materials, cannot be subjected to lithographic chemistries without damaging them, which necessitates the deposition of such materials through shadow masks.

Unfortunately, the feature resolution that can be obtained by conventional shadow mask deposition is reduced by the fact that the deposited material tends to spread laterally after passing through the shadow mask, known as "feathering". Feathering increases with the magnitude of the spacing between the substrate and the shadow mask. To mitigate feathering, this spacing is kept as small as possible without compromising the integrity of the chuck holding the substrate and shadow mask. Furthermore, any non-uniformity in this spacing across the deposition area will result in variations in the amount of feathering. Such non-uniformity can be caused by, for example, non-parallelism between the substrate and the shadow mask, bowing or sagging of one or both of the substrate and the shadow mask, and the like.

Unfortunately, it can be difficult to position the shadow mask and substrate close enough to avoid causing substantial feathering. Furthermore, the shadow mask must be supported only at its periphery to avoid blocking vaporized atoms through the via pattern. Thus, the center of the shadow mask may sag due to gravity, which further exacerbates the feathering problem.

Thus, in practice, the critical features formed by prior art shadow mask-based deposition techniques are typically separated by relatively large open space regions to accommodate feathering, which limits the achievable device density. For example, each pixel of an Active Matrix Organic Light Emitting Diode (AMOLED) display typically includes several regions of organic light emitting material that each emit a different color of light. Due to feathering issues, prior art AMOLED displays have typically been limited to about 600 pixels per inch (600ppi) or less, which is insufficient for many applications such as near-eye augmented reality and virtual reality applications. In addition, the need for large gaps within and between pixels results in a reduction in pixel fill factor, which reduces display brightness. Therefore, the current density through the organic layers must be increased to provide the desired brightness, which negatively impacts display lifetime.

An alternative approach is to use a shadow mask with apertures as large as the active area of the display itself to deposit the emissive monochromatic white light organic layer across the entire display and then pattern or deposit the red, green and blue filters on top of the OLED. These color filters absorb all of the emitted white light except for the red, green, or blue portions of the spectrum (depending on the color filter) to allow a full color image to be produced. However, these color filters absorb up to 80% of the emitted light, which significantly reduces the display brightness, again requiring operation at higher than desired drive currents.

In the prior art, the need for a process to achieve high resolution direct patterning has not yet been met.

Disclosure of Invention

The present invention enables high resolution direct deposition of a patterned material layer on a substrate without increasing cost and overcoming the disadvantages of the prior art. Embodiments of the present invention filter the propagation angle of vaporized atoms to a narrow range around the direction normal to the surface of the substrate. Thus, feathering of the deposited material outside the lateral dimensions of the features of the shadow mask is mitigated. Embodiments of the present invention are particularly suitable for depositing sensitive materials such as organic light emitting materials. Embodiments are also well suited to depositing other thin and thick film layers in packaging applications, integrated circuit processing applications, and the like.

The present invention further enables high precision alignment of shadow masks and substrates that may be in contact with or spaced apart by only a few microns. The present invention also mitigates gravity-induced sagging of a shadow mask supported only at its periphery. Embodiments of the present invention are particularly well suited for applications requiring high density material patterns on a substrate, such as Dense Pixel Displays (DPD), high definition displays, and the like.

An illustrative embodiment of the present invention is a direct patterning deposition system in which material is vaporized at a source such that it is deposited on a surface of a substrate after passing through a pattern of apertures of a shadow mask. The vaporized atoms pass through a collimator that blocks all vaporized atoms except those having a propagation angle close to a direction perpendicular to the surface of the substrate before they reach the shadow mask. Thus, the lateral deviation between the aperture and its corresponding deposited material region is reduced compared to the prior art.

The collimator includes a plurality of channels having high aspect ratios, wherein longitudinal axes of the channels are substantially aligned with a vertical direction. Therefore, vaporized atoms that do not travel in a direction close to vertical are blocked by the inner side walls of the channel.

In some embodiments, the source is sized and arranged to provide a conical vapor plume (vapor plume) of vaporized atoms such that the entire substrate surface receives vaporized material simultaneously. In several of these embodiments, the source is moved along a path such that the uniformity of the thickness of the deposited material over a two-dimensional area of the substrate surface is improved.

In some embodiments, the source is a linear source emitting a fan-shaped steam plume, wherein the linear source moves in a direction that is not aligned with its longitudinal axis. In some of these embodiments, the source is moved in a direction substantially orthogonal to both the longitudinal axis and the vertical direction of the source. In several of these embodiments, the source is moved along a non-linear path.

In some embodiments, the source includes a plurality of individual nozzles, each of which emits a conical vapor plume such that the nozzles collectively provide a substantially uniform flow of vaporized atoms over the area of the substrate surface.

In some embodiments, the source is a two-dimensional planar source arranged parallel to and facing the substrate such that organic material vaporizes uniformly across a planar surface of the source when heated. In some embodiments, relative motion between the source and the shadow mask is provided to improve thickness uniformity of deposited material over a two-dimensional area of the substrate surface.

Another illustrative embodiment of the present invention is a direct patterning deposition system, comprising: a first chuck having a first mounting surface for holding a substrate; and a second chuck having a second mounting surface for holding a shadow mask including a via hole pattern. The second chuck includes a support surrounding a central opening exposing the via pattern in the shadow mask. Thus, during deposition, vaporized atoms of material may pass through the second chuck and the vias to be deposited in a desired pattern on a deposition area of the front surface of the substrate.

The first chuck generates a first electrostatic force that is selectively applied to a back surface of the substrate. The first chuck is also sized and arranged so that it does not protrude beyond the substrate front surface. In a similar manner, the second chuck generates a second electrostatic force that is selectively applied to a rear surface of the shadow mask. The second chuck is also sized and arranged so that it does not protrude beyond the shadow mask front surface. When the shadow mask and the substrate are aligned for deposition, no portion of the first chuck and the second chuck encroaches into the three-dimensional space between the substrate and the shadow mask. Thus, the substrate and the shadow mask can be positioned very close to or even in contact during deposition, thereby mitigating feathering.

In some embodiments, at least one of the first suction force and the second suction force is a non-electrostatic force such as a vacuum-generating force, a magnetic force, or the like.

In some embodiments, the second mounting surface is sized and arranged to create a tensile stress in a front surface of the shadow mask that mitigates gravity-induced sag of a central region of the shadow mask. In some such embodiments, the shelf of the second chuck is shaped such that its mounting surface slopes away from a top edge of an inner periphery of the shelf. Thus, when the shadow mask is mounted in the second chuck, the shadow mask becomes slightly bowed, which causes tensile stress in the front surface of the shadow mask. In some of these embodiments, the mounting surface curves downward from the top edge of the inner perimeter of the bracket.

An embodiment of the invention is a system for depositing a first material on a plurality of deposition sites in a deposition area of a substrate arranged in a first arrangement, wherein the substrate comprises a first major surface and a second major surface comprising the deposition area, the system comprising: a source for providing a first plurality of vaporized atoms of the first material, each of the first plurality of vaporized atoms propagating along a propagation direction characterized by a propagation angle relative to a first direction perpendicular to a first plane defined by the substrate, wherein a range of propagation angles for the first plurality of vaporized atoms spans a first angular range; a shadow mask comprising a plurality of vias arranged in the first arrangement, wherein the shadow mask includes a third major surface and a fourth major surface comprising the vias; a first chuck for holding the substrate, the first chuck being sized and arranged to selectively impart a first suction force to the first major surface; a second chuck for holding the shadow mask, the second chuck comprising a support surrounding a first opening enabling the material to pass through the second chuck to the through-hole, the second chuck being sized and arranged to selectively impart a second suction force to the third major surface; a collimator comprising a plurality of channels, the collimator being interposed between the source and the shadow mask, wherein each of the plurality of channels is sized and arranged to pass only vaporized atoms having a propagation angle within a second angular range that is less than the first angular range; and a positioning system for controlling the relative positions of the first chuck and the second chuck to align the shadow mask and the substrate.

Another embodiment of the invention is a system for depositing a first material on a plurality of deposition sites in a deposition area of a substrate, the plurality of deposition sites arranged in a first arrangement, wherein the substrate includes a first major surface and a second major surface having a first lateral extent, the system comprising: a source operable to provide a plurality of vaporized atoms, each of the plurality of vaporized atoms traveling along a propagation direction defining a propagation angle, wherein the plurality of propagation angles span a first angular range; a shadow mask comprising a plurality of vias arranged in the first arrangement, wherein the shadow mask includes a third major surface and a fourth major surface comprising the vias, wherein the shadow mask and the plurality of deposition sites together define an acceptable angular range that is less than the first angular range; a first chuck for holding the substrate; a second chuck for holding the shadow mask, the second chuck comprising a support surrounding a first opening enabling the material to pass through the second chuck to the via; wherein when the shadow mask and the substrate are aligned, the shadow mask and the substrate together define a second region that (1) has a second lateral extent equal to or greater than the first lateral extent, (2) has a thickness equal to a spacing between the substrate and the shadow mask, and (3) does not include the first chuck and the second chuck; wherein the first chuck and the second chuck are sized and arranged to enable the thickness to be less than 10 microns; and a collimator positioned between the source and the shadow mask, the collimator comprising a plurality of channels, each of the plurality of channels having a height-to-width aspect ratio defining a range of filter angles less than or equal to the range of acceptable angles.

Yet another embodiment of the present invention is a method for depositing a first material on a plurality of deposition sites arranged in a first arrangement on a substrate, wherein the substrate includes a first major surface and a second major surface having a first lateral extent, the second major surface including a first region, wherein the method comprises: receiving a first plurality of vaporized atoms at a collimator positioned between a source and a shadow mask having a plurality of through holes arranged in the first arrangement, wherein the shadow mask includes a third major surface and a fourth major surface including the through holes, wherein the first plurality of vaporized atoms is characterized by a first range of propagation angles; holding the substrate in a first chuck that selectively imparts a first suction force to the first major surface; holding the shadow mask in a second chuck that selectively imparts a second suction force to the third major surface, wherein the second chuck enables particles comprising the material to pass through the second chuck to the through holes; selectively passing a second plurality of vaporized atoms through the collimator to the shadow mask, wherein the second plurality of vaporized atoms is characterized by a second range of propagation angles that is narrower than the first range of propagation angles; and positioning the substrate and the shadow mask such that the second major surface and the fourth major surface are separated by a distance of less than or equal to 10 microns; and enabling at least some of the second plurality of vaporized atoms to be deposited on the substrate through the second chuck and the plurality of vias.

Drawings

Fig. 1 depicts a schematic diagram of a cross-section of the main features of a direct patterning deposition system according to the prior art.

Fig. 2 depicts a schematic diagram of a cross-section of the main features of a high precision direct patterning deposition system, according to an illustrative embodiment of the invention.

Fig. 3 depicts operations of a method for depositing a layer of directly patterned material on a substrate, according to an illustrative embodiment.

Fig. 4A-B depict schematic diagrams of a top view and a cross-sectional view, respectively, of a mask chuck in accordance with an illustrative embodiment.

Fig. 5 depicts a cross-sectional view of the shadow mask 106 mounted in the mask chuck 206.

Fig. 6A depicts a schematic diagram of a cross-sectional view of a portion of a mask chuck 206 according to a first alternative embodiment of the present invention.

Fig. 6B depicts a schematic diagram of a cross-sectional view of a portion of mask chuck 206, according to a second alternative embodiment of the present invention.

Fig. 7A-B depict schematic diagrams of a top view and a cross-sectional view, respectively, of a mask chuck according to a third alternative embodiment of the present invention.

Fig. 8A depicts a schematic diagram of a cross-sectional view of a mask chuck in accordance with an illustrative embodiment.

Fig. 8B depicts a schematic diagram of a cross-sectional view of the substrate chuck 204 when holding the substrate 102.

Fig. 9 depicts a schematic diagram of a cross-sectional view of a portion of system 100 in which substrate 102 and shadow mask 106 are aligned for deposition of material 116.

Fig. 10 depicts a schematic diagram of an enlarged view of the pixel area of the substrate 102 and its corresponding aperture 120 of the shadow mask 106.

FIG. 11A depicts a schematic diagram of a cross-sectional view of a collimator in accordance with an illustrative embodiment.

Fig. 11B-C depict schematic diagrams of top and cross-sectional views, respectively, of a region of the collimator 208.

Detailed Description

Fig. 1 depicts a schematic diagram of a cross-section of the main features of a direct patterning deposition system according to the prior art. System 100 is a conventional evaporation system that deposits a desired pattern of material on a substrate by evaporating the material through a shadow mask positioned in front of the substrate. System 100 includes a source 104 and a shadow mask 106 arranged within a low pressure vacuum chamber (not shown).

The substrate 102 is a glass substrate suitable for forming an Active Matrix Organic Light Emitting Diode (AMOLED) display. The substrate 102 includes a surface 114 that defines a plane 108 and a vertical axis 110. Vertical axis 110 is orthogonal to plane 108. Surface 114 includes a plurality of deposition sites G for receiving green-emitting material, a plurality of deposition sites B for receiving blue-emitting material, and a plurality of deposition sites R for receiving red-emitting material. The deposition sites are arranged in a plurality of pixel regions 112 such that each pixel region contains one deposition site for a light emitting material of a respective color.

The source 104 is a crucible for vaporizing the material 116, the material 116 being an organic material that emits light at a desired wavelength. In the depicted example, the material 116 is an organic light emitting material that emits red light. In the depicted example, the source 104 is a single chamber crucible centered with respect to the substrate 102; however, in some embodiments, the source 104 includes a plurality of chambers arranged in a one-dimensional and/or two-dimensional arrangement. As the material 116 melts or sublimates within the low pressure atmosphere of the vacuum chamber 110, vaporized atoms 122 of the material 116 are ejected from the source and propagate in a generally ballistic manner toward the substrate 102. The vaporized atoms emitted by the source 104 collectively define a vapor plume 124.

Shadow mask 106 is a sheet of structural material containing apertures 120. The shadow mask is substantially planar and defines a plane 118. A shadow mask is positioned between the source 104 and the substrate 102 such that it blocks all vaporized atoms from passing except those passing through its apertures. The shadow mask is spaced from the substrate by a spacing s (typically tens or hundreds of microns), the

planes

108 and 118 are substantially parallel, and the apertures 120 are aligned with the deposition sites R.

Ideally, when the red-emitting material 116 is deposited, the vaporized atoms are only incident on the deposition site R. Unfortunately, the steam plume 124 contains vaporized atoms traveling in many different propagation directions 126, many of which are not aligned with the direction of the vertical axis 110. Thus, most of the vaporized atoms passing through the aperture 120 travel in a direction of propagation with a substantial lateral component. The point of incidence of each vaporized atom on surface 114 is geometrically dependent on its angle of propagation and the spatial relationship between the substrate and shadow mask, specifically the spacing s and alignment of apertures 120 with deposition sites R. For purposes of this specification, including the appended claims, the term "propagation angle" is defined as the angle formed by the direction of propagation of vaporized atoms relative to a direction perpendicular to the plane 108 of the substrate 102 (i.e., the vertical direction 128, which is aligned with the vertical axis 110). For example, vaporized atoms 122 travel along a propagation direction 126, the propagation direction 126 forming a propagation angle θ p with respect to a vertical direction 128.

The propagation angle of the vaporized atoms of the vapor plume 124 spans a relatively large angular range of- θ m to + θ m, which leads to a significant disadvantage of prior art direct deposition systems. In particular, it results in the deposition of material 118 on surface 114 outside the perimeter of aperture 120, which is commonly referred to as "feathering". In addition, the amount of feathering at the aperture increases with the distance of the aperture from the center of the substrate 102.

Vaporized atoms 122 that reach shadow mask 106 have a propagation angle within a relatively small angular range for apertures located near the center of the vapor plume 124. In other words, it travels in a direction that is only slightly offset from the vertical axis 110. As a result, vaporized atoms passing through these apertures exhibit only minimal lateral drift (i.e., feathering) after passing through the shadow mask. Thus, in this region, the lateral extent of the deposition material 116 is generally nearly aligned with the edges of the aperture 120 (i.e., it is deposited primarily on the target deposition site R).

However, for apertures further away from the center of the vapor plume 124, vaporized atoms reaching the shadow mask 106 span a relatively large angular range and include propagation angles closer to | θ m |. Therefore, in these regions, the lateral distance traveled by the vaporized atoms after passing through the shadow mask is large, resulting in feathering of the deposited material well beyond the lateral extent of the apertures. This results in a lateral offset δ f between the edge of the aperture opening and the periphery of the area in which the material 116 is deposited. Thus, the deposition material extends beyond the area of the target deposition site. In some cases, this feathering can result in the deposition of material on adjacent deposition sites (i.e., deposition sites B and/or G) desired for different light emitting materials, thereby resulting in color mixing.

It should be noted that any additional misalignment between the shadow mask and the substrate exacerbates feathering, such as parallelism out of planes 108 and 118 (i.e., relative spacing and/or deflection between the mask and the substrate), unevenness of the shadow mask and/or the substrate, and translational and/or rotational misalignment between the shadow mask and the substrate. Furthermore, in many prior art deposition systems (e.g., systems for depositing more than one material, etc.), the source 104 is positioned off-center relative to the substrate, which leads to even greater feathering problems.

Those skilled in the art will recognize that contacting shadow mask 106 with substrate 102 during deposition will reduce or even eliminate the problem of feathering altogether. Unfortunately, this is undesirable or impossible in most cases for a variety of reasons. First, prior art substrate and shadow mask chucks typically include features that protrude beyond the substrate and shadow mask, respectively. These features thus become blocking elements that limit the degree of tight positioning of the substrate and shadow mask. Second, contact with the shadow mask can cause damage to existing structural mechanisms on the surface of the substrate. Third, shadow mask damage can result from contact with the substrate. Fourth, once contact with the substrate is removed, residues can remain on the shadow mask surface. Then, frequent cleaning of the shadow mask is required, which increases process time and overall cost, while also potentially causing damage to the mask during the cleaning operation. Thus, prior art shadow mask deposition has been generally limited to non-contact configurations in which feathering has a significant negative impact. Fifth, conventional shadow masks are typically made of metal and are therefore necessarily quite thick. The thick shadow mask, when in contact with the substrate, causes shadow in the area of each aperture, which results in thinning of the edges of the deposited features. For thicker shadow masks, such as those typically used in the prior art, more material is lost due to the walls of the apertures and the edges of the subpixels become thinner.

However, the present invention achieves direct deposition while overcoming some of the disadvantages of the prior art. The first aspect of the present invention is: feathering can be significantly reduced by allowing only vaporized atoms propagating in a direction nearly perpendicular to the surface of the substrate to reach the shadow mask, thereby enabling the pattern of deposited material to have higher resolution and fidelity relative to the aperture pattern of the shadow mask.

Another aspect of the invention is: non-metallic materials such as silicon nitride are used for the shadow mask to enable it to be very thin (< 1 micron), thereby resulting in significantly reduced shadow compared to prior art shadow masks.

Yet another aspect of the invention is: gravity-induced sagging of a shadow mask can be reduced or eliminated by using a shadow mask chuck sized and arranged to counteract the effects of gravity on the shadow mask.

Another aspect of the invention is: the substrate and shadow mask chuck do not have structures protruding beyond the top surface of the substrate and shadow mask to enable a very small spacing or even contact between the substrate and shadow mask, thereby mitigating feathering. The substrate/shadow mask contact may also increase its stability during deposition, improve material utilization by reducing waste, enable faster deposition and higher throughput, and enable lower temperature deposition.

Fig. 2 depicts a schematic diagram of a cross-section of the main features of a high precision direct patterning deposition system, according to an illustrative embodiment of the invention. System 200 includes vacuum chamber 202, substrate chuck 204, source 104, shadow mask 106, mask chuck 206, collimator 208, and positioning system 212. The system 200 is operable to evaporate a desired pattern of material onto a substrate surface without the need for subsequent subtractive patterning operations such as photolithography and etching.

The system 200 is described herein with respect to depositing a pattern of light emitting material on a glass substrate as part of fabricating an AMOLED display. However, it should be apparent to those skilled in the art, after reading this specification, that the present invention can be directed to forming directly patterned layers of virtually any thin and thick film material (organic or inorganic) on any of a variety of substrates, such as semiconductor substrates (e.g., silicon carbide, germanium, and the like), ceramic substrates, metal substrates, plastic substrates, and the like. Moreover, although the illustrative embodiment is a thermal evaporation system, one of ordinary skill in the art will recognize, upon reading this specification, that the invention may be directed to virtually any material deposition process, such as e-beam evaporation, sputtering, and the like. Furthermore, although the depicted example is a deposition system suitable for single substrate planar processing, the present invention is also suitable for other manufacturing methods, such as cluster tool processing, track processing, roll-to-roll processing, and the like. Accordingly, the present invention is suitable for use in a variety of applications including, but not limited to, packaging applications, IC manufacturing, MEMS manufacturing, nanotechnology device manufacturing, Ball Grid Array (BGA) manufacturing, and the like.

In the depicted example, shadow mask 106 is a high precision shadow mask comprising handle substrate 224 and film 226 suspended over a central opening formed in the handle substrate. Film 226 includes via pattern 228. Shadow mask 106 includes two major surfaces: a front surface 230 and a rear surface 232. The front surface 230 is the top surface of the membrane 226 (i.e., the surface of the membrane remote from the handle substrate 224), which defines the plane 118. The back surface 232 is the surface of the handle substrate 224 (i.e., the surface of the substrate away from the film 226). It should be noted that although shadow mask 106 is a film-based high-precision shadow mask, virtually any type of shadow mask can be held using a mask chuck according to the present invention. Preferably, film 226 comprises silicon nitride; however, other materials may be used without departing from the scope of the invention. Preferably, the film 226 has a thickness of less than or equal to one micron; however, other thicknesses of film may be used without departing from the scope of the invention.

As discussed above, by employing a shadow mask film having a thickness of one micron or less, the shadow effect during direct deposition can be reduced as compared to prior art shadow masks.

The vacuum chamber 202 is a conventional pressure vessel for containing the low pressure environment required to vaporize the material 116. In the depicted example, vacuum chamber 110 is a stand-alone unit; however, it may also be part of a cluster deposition system or a track deposition system in which a plurality of evaporation chambers are arranged in a linear chain without departing from the scope of the invention. In some embodiments, vacuum chamber 110 includes several evaporation source/shadow mask combinations capable of forming different patterns of different materials on substrate 102, such as, for example, a plurality of light emitting sub-pixels emitting light of different colors, such as red, green, and blue.

Controller 240 is a conventional instrument controller that provides, among other things, control signals 236 and 238 to substrate chuck 204 and mask chuck 206, respectively.

Fig. 3 depicts operations of a method for depositing a layer of directly patterned material on a substrate, according to an illustrative embodiment. The method 300 is described herein with continued reference to fig. 2 and with reference to fig. 4A-B, 5, 6A-B, 7A-B, 8A-B, 9, 10, and 11A-C. The method 300 begins at operation 301, where the collimator 208 is installed in the collimator chuck 210.

The collimator 208 is a mechanically rigid plate comprising a plurality of channels separated by thin walls, as will be described in more detail below with respect to fig. 11A to C. The collimator 208 is sized and arranged to act as a spatial filter that selectively passes vaporized atoms that propagate in a direction nearly perpendicular to the plane 108 (i.e., vaporized atoms with very small propagation angles). Thus, the collimator 208 mitigates feathering across the entire substrate 102.

Collimator chuck 210 is an annular clamping mechanism for holding and positioning the collimator relative to shadow mask 106.

In operation 302, shadow mask 106 is installed in mask chuck 206.

Mask chuck 206 is a jig that holds shadow mask 106 via suction applied only to its rear surface. In the depicted example, mask chuck 206 uses electrostatic forces to hold shadow mask 106. In some embodiments, mask chuck 206 holds the shadow mask via different suction forces, such as vacuum-generated forces, magnetic forces, and the like. In other embodiments, the mask chuck 206 is a mechanical clamp.

Fig. 4A-B depict schematic diagrams of a top view and a cross-sectional view, respectively, of a mask chuck in accordance with an illustrative embodiment. The cross-section depicted in fig. 4B is taken through line a-a shown in fig. 4A. Mask chuck 206 includes a support 402, electrodes 404-1 and 404-2, and a pad 406.

The support 402 is a structurally rigid ring of electrically insulating material. The standoff 402 surrounds an opening 408, the opening 408 being large enough to expose the entire via pattern 228. In some embodiments, the stent 402 has a non-circular shape, such as a square, rectangle, irregular, etc. In some embodiments, the bracket 402 comprises an electrically conductive material coated with an electrical insulator.

Electrodes 404-1 and 404-2 are conductive elements formed on the surface of support 402. Electrodes 404-1 and 404-2 are electrically coupled to controller 240.

Pad 406 is a structurally rigid plate of electrically insulating material disposed over electrodes 404-1 and 404-2. Each of the pads 406 includes a mounting surface 410 against which the shadow mask 106 is held when the shadow mask 106 is mounted in the mask chuck, the mounting surface 410 being abutted by the shadow mask 106.

The shadow mask 106 is held in the mask chuck 206 by applying electrostatic forces between the mounting surface 410 and the back surface 232. The electrostatic force is generated in response to a voltage potential between electrodes 404-1 and 404-2, which is generated by control signal 238. When the back surface 232 is brought into contact with the mounting surface 410, a region of sympathetic charge develops within the handle substrate 224, as shown in the figure. Accordingly, electrostatic force is selectively imparted between the rear surface 232 and the mounting surface 410.

Typically, shadow mask 106 is supported only around the perimeter of shadow mask 106. Therefore, prior art shadow masks tend to sag under the force of gravity. In some embodiments, a mask chuck according to the present disclosure includes one or more features that reduce or eliminate gravity-induced sagging of a shadow mask when the shadow mask is installed. As discussed in detail above, the shadow mask may sag center a few microns due to its own mass and gravity. This gravity causes sagging leading to several significant problems that exacerbate feathering. First, it increases the spacing between the shadow mask and the substrate in the center of the deposition area, which is typically centrally located on the shadow mask. As discussed above, feathering increases with substrate/shadow mask spacing. Second, it results in non-uniform spacing between the substrate and the shadow mask, which results in variations in the degree of feathering that occurs across the substrate surface. Even if the non-uniformity is not unable to compensate for feathering via the innovative mask layout, it can be very difficult.

Yet another aspect of the invention is: the mask chuck may include features that mitigate gravity-induced sag of the shadow mask.

In some embodiments, mask chuck 206 includes a slight curvature (e.g., an upward slope) that biases the shadow mask upward to counteract shadow mask sag due to gravity. In some embodiments, fine support structures may extend across openings in the mask chuck 206 to support the mask and reduce gravitational sag. These features will be described in more detail below with respect to fig. 6A-B and 7A-B.

Fig. 6A-B depict schematic diagrams of cross-sectional views of portions of a mask chuck according to a first alternative embodiment of the present invention. The cross-section depicted in fig. 6A is taken through line a-a shown in fig. 4A. The mask chuck 600 includes a support 402, electrodes 404-1 and 404-2, and a pad 602.

Pad 602 is similar to pad 406 described above; however, each pad 602 has a mounting surface designed to induce or increase tensile strain in the shadow mask when the shadow mask is mounted in the mask chuck. The pad 602 has a mounting surface 604 that tapers linearly downward from an inner edge 606 (i.e., the edge proximate the opening 408) to an outer edge 608. In other words, the mounting surface 604 tapers in the negative z-direction from point 614 to point 616 (i.e., from the intersection with the inner edge 606 at plane 610 to the intersection with the outer edge 608 at plane 612), as shown in the figure. Thus, in embodiments where inner edge 606 is perpendicular to plane 610, inner edge 606 and mounting surface 604 form an interior angle θ such that it is acute.

When shadow mask 106 is held in mask chuck 600, back surface 232 is attracted to mounting surface 604, thereby causing the shadow mask to bend, which increases the laterally directed tension in front surface 230 of the shadow mask. Thus, the membrane is pulled tighter and gravity induced sagging is reduced or eliminated.

Fig. 6B depicts a schematic diagram of a cross-sectional view of a portion of a mask chuck in accordance with a second alternative embodiment of the present invention. The cross-section depicted in fig. 6B is taken through line a-a shown in fig. 4A. The mask chuck 618 includes a support 402, electrodes 404-1 and 404-2, and a pad 720.

Pad 620 is similar to pad 406 described above; however, like pads 602, each pad 620 has a mounting surface designed to induce or increase tensile strain in the shadow mask when the shadow mask is mounted in the mask chuck. The pad 620 has a mounting surface 622 that curves downward (i.e., in the negative z-direction, as shown in the figure) from the inner edge 606 to the outer edge 608. In other words, the mounting surface 622 tapers in the negative z-direction from point 614 to point 616, as shown in the figure.

When shadow mask 106 is held in mask chuck 618, back surface 232 is attracted to mounting surface 622, thereby causing the shadow mask to bend, which increases the laterally directed tension in front surface 230 of the shadow mask. Thus, the membrane is pulled tighter and gravity induced sagging is reduced or eliminated. In some embodiments, the amount of additional tension induced in front surface 230 may be controlled by controlling the magnitude of the voltage difference applied to electrodes 404-1 and 404-2.

It should be clear to those skilled in the art, after reading this specification, that for a deposition system in which the mounting mask is reversed (as compared to its orientation depicted in fig. 1), the direction in which the mounting surfaces 604 and 622 are tilted (or curved) will be reversed. Moreover, in such a configuration, it is typically desirable to have substrate chuck 204 designed to enable substrate 102 to reside within opening 408 such that the substrate/shadow mask spacing is less than or equal to 10 microns.

Fig. 7A-B depict schematic diagrams of a top view and a cross-sectional view, respectively, of a mask chuck according to a third alternative embodiment of the present invention. Mask chuck 700 includes mask chuck 206 and support grid 702.

The support grid 702 includes plates 704 and support ribs 706.

The plate 704 is a rigid plate from which support ribs 706 extend. In some embodiments, the plate 704 and the support ribs 706 are machined from a solid structural material. Suitable materials for use in the plate 704 and support ribs 706 include, but are not limited to, metals, plastics, ceramics, composites, glass, and the like. Plate 704 is designed to be mounted to bracket 402 to position support grid 702 within opening 408 such that it mechanically supports membrane 226 when shadow mask 106 is installed in mask chuck 700.

Support ribs 706 are arranged to support shadow mask 106 in areas located between the vias of via arrangement 228. Typically, the vias of the shadow mask are arranged in clusters corresponding to different die areas on the substrate. Since these die areas are typically separated by "lanes" that are desired to be removed by a dicing saw, the support ribs 706 are preferably arranged to match the arrangement of these lanes. It should be noted, however, that any suitable arrangement of support ribs may be used in the support grid 702.

The support grid 702 is formed such that its top surfaces 708 are coplanar and define a plane 710. The plane 710 is located above the mounting surface 410 a distance equal to the thickness of the bracket 224. Thus, when the bracket 224 is in contact with the mounting surface 410, the support ribs 706 are in contact with the membrane 226.

In some embodiments, shadow mask 106 is held upside down in mask chuck 700 so that film 226 is in contact with mounting surface 410. In such embodiments, the support grid 702 is designed to fit within the opening 408 such that the plane 710 is coplanar with the mounting surface 410. Thus, the membrane 226 is supported by the support grid 702 such that it is completely horizontal throughout the opening 408.

In operation 303, substrate 102 is mounted in substrate chuck 204.

The substrate chuck 204 is a platen for holding the substrate 102 via suction applied only to a rear surface thereof. In the depicted example, substrate chuck 204 generates electrostatic forces to hold the substrate, however, in some embodiments, substrate chuck 204 holds the substrate via different suction forces such as vacuum generated forces, magnetic forces, and the like. For the purposes of this specification (which includes the appended claims), the term "magnetic force" includes any force resulting from the use of permanent magnets and/or electromagnets. Substrate chuck 204 will be described in more detail below with respect to fig. 8A-B.

In some embodiments, substrate chuck 204 is sized and arranged to contact substrate 102 from the front surface only to mitigate interference with depositing material on the other side of the substrate. In some embodiments, substrate chuck 204 holds the substrate from both sides of the substrate via different means, such as vacuum mechanical clamps, and so forth. In some embodiments, substrate chuck 204 includes an in-situ gap sensor that operates in conjunction with positioning system 212 to control the spacing and parallelism between substrate 102 and shadow mask 106.

In the depicted example, the substrate 102 is a glass substrate suitable for use in an Active Matrix Organic Light Emitting Diode (AMOLED) display. The substrate 102 includes two major surfaces on which display elements are defined: a rear surface 115 and a front surface 114. The front surface 114 defines a plane 108.

Fig. 8A depicts a schematic diagram of a cross-sectional view of a substrate chuck, according to an illustrative embodiment. Substrate chuck 204 includes a platen 802 and electrodes 804-1 and 804-2.

The platen 802 is a structurally rigid platform that includes a substrate 806 and a dielectric layer 808. Each of the substrate 806 and the dielectric layer 808 comprise an electrically insulating material such as glass, ceramic, anodized aluminum, composite, bakelite, and the like to electrically isolate the electrodes 804-1 and 804-2 from each other and from the substrate 102 when the substrate is mounted in the substrate chuck.

Electrodes 804-1 and 804-2 are conductive elements formed on the surface of substrate 806 and covered by dielectric layer 808 to embed them within platen 802. Electrodes 804-1 and 804-2 are electrically coupled to controller 240. It should be noted that although electrodes 804-1 and 804-2 are depicted as simple plates, substrate chuck 204 may have electrodes shaped in virtually any manner, such as interdigitated fingers, concentric rings, irregular shapes, and so forth.

Dielectric layer 808 is a structurally rigid glass layer disposed on electrodes 804-1 and 804-2 to create mounting surface 810.

To hold substrate 102 in substrate chuck 204, control signal 236 generates a voltage potential between electrodes 804-1 and 804-2. When the back surface 115 is brought into contact with the mounting surface 810 (i.e., the top surface of the dielectric layer 808), a region of sympathetic charge develops within the substrate 102, as shown in the figure. Accordingly, electrostatic force is selectively imparted to the rear surface 115, thereby attracting the rear surface 115 to the mounting surface 810.

Although the illustrative embodiments include a substrate chuck that holds the substrate 102 via electrostatic forces, it will be clear to those skilled in the art, after reading this specification, how to specify, make, and use alternative embodiments in which the substrate is held in the substrate chuck via suction forces other than electrostatic forces, such as vacuum-generated forces, magnetic forces, and the like.

In operation 304, the relative positions of substrate 102, source 104, shadow mask 106, and collimator 208 are controlled by positioning system 212.

Positioning system 212 aligns substrate 102 and shadow mask 106 by controlling the position of substrate chuck 204. In some embodiments, the positioning system aligns the substrate and the shadow mask by controlling the position of the mask chuck 206. In some embodiments, the positions of the two chucks are controlled to align the substrate and the shadow mask. Operation 304 and positioning system 212 will be described in more detail below with respect to fig. 1, 2,9, 10, and 11A-C.

The positioning system includes three six-axis manipulators and an optical alignment system for controlling the alignment between the substrate 102 and the shadow mask 106. Each of the six-axis manipulators is operably connected with each of substrate chuck 204, mask chuck 206, and collimator chuck 210 to control their position along and rotation about each of the x-axis, y-axis, and z-axis. In some embodiments, the position of at least one of the mask chuck 206 and the collimator chuck 210 is not controlled by a six-axis positioner. In some embodiments, positioning system 212 also includes a rotary stage for controlling the relative rotational alignment of substrate 102 and shadow mask 106.

In operation 304, positioning system 212 positions the substrate and shadow mask such that deposition sites R in deposition area 216 are aligned with apertures 120,

planes

108 and 118 are parallel, and the spacing s between the substrate and shadow mask is as close to zero (i.e., contact) as possible, preferably within a few microns (e.g., 1-5 microns). In some embodiments, s is another suitable spacing. It should be noted that the spacing s is depicted particularly exaggerated for clarity.

Aspects of the invention are: in some embodiments, both substrate chuck 204 and mask chuck 206 do not include any structural elements that protrude beyond their respective mounting surfaces. Thus, the substrate and shadow mask can be aligned with little or no spacing from each other to mitigate feathering during deposition. Those skilled in the art will recognize that in conventional direct deposition systems, the spacing between the substrate and the shadow mask must be at least a few ten or even hundreds of microns.

When the substrate and shadow mask are aligned, they collectively define an area 902 between them. The region 902 has a lateral extent L1 equal to the lateral extent of the front surface 114. Region 902 also has a thickness equal to spacing s1 between planes 108 and 118 (i.e., the spacing between the substrate and the shadow mask).

Because no portion of substrate chuck 204 extends beyond plane 108 into region 902, there are no obstacles between the substrate and the shadow mask. Thus, the spacing s1 between substrate 102 and shadow mask 106 can be very small (< 10 microns). In fact, the substrate and shadow mask can be brought into contact with each other if desired. The ability to perform direct patterning with a substrate/shadow mask spacing equal to or less than 10 microns makes embodiments of the present invention significantly superior to prior art direct patterning deposition systems because it enables significant reduction or even elimination of feathering. In some embodiments, there is no space or gap between the substrate and the shadow mask to be zero to completely eliminate feathering.

In operation 305, the source 104 generates a steam plume 124. As described above with respect to fig. 1, the propagation angle θ p of the vaporized atoms of the vapor plume 124 spans a relatively large angular range of- θ m to + θ m. In the prior art, this large angular range exacerbates feathering, which varies depending on the range of lateral and rotational alignment between the substrate 102 and the shadow mask 106, the spacing s between the substrate 102 and the shadow mask 106, and the propagation angle θ p of vaporized atoms incident on the shadow mask.

However, in the present invention, the range of propagation angles of vaporized atoms to the substrate surface is reduced by positioning a spatial filter (i.e., collimator 208) in the path of the vaporized atoms from source 104 to shadow mask 106. Thus, the inclusion of collimator 208 in system 200 significantly reduces feathering during direct deposition.

Fig. 10 depicts a schematic diagram of an enlarged view of the pixel area 112 of the substrate 102 and its corresponding aperture 120 of the shadow mask 106. As shown in the figure, for high fidelity between the apertures 120 and the deposition of material on the deposition site R, the propagation angle of the vaporized atoms through the shadow mask 106 must be within an acceptable range of-theta a to + theta a. For purposes of this specification, including the appended claims, the term "acceptable angular range" is defined as the range of propagation angles desired through the shadow mask that span an angular range from-thetaa to + thetaa. Generally, the acceptable angular range is the angular range that enables the material 116 to be deposited only on the deposition site R after passing through the aperture 120. In some embodiments, the acceptable angular range includes a small guard band around the deposition sites to allow feathering of less than half of the spacing between the nearest deposition sites. Any vaporized atoms incident on the shadow mask having a propagation angle outside this range will deposit on the surface 114 beyond the lateral extent of the deposition site R.

In operation 306, the steam plume 124 is filtered by the collimator 208 to produce the steam column 214.

FIG. 11A depicts a schematic diagram of a cross-sectional view of a collimator in accordance with an illustrative embodiment. The collimator 208 includes a body 1102 patterned to form a plurality of channels 1104, each of the plurality of channels 1104 extending through a thickness of the body 1102.

The body 1102 is a glass plate suitable for planar processing. In the depicted example, the body 1102 has a thickness of about 25 millimeters (mm); however, any practical thickness may be used without departing from the scope of the invention. In some embodiments, body 1102 comprises a different structurally rigid material adapted to withstand the temperatures associated with thermal and/or e-beam evaporation without significant deformation. Suitable materials for use in the body 1102 include, but are not limited to, semiconductors (e.g., silicon carbide, etc.), ceramics (e.g., alumina, etc.), composites (e.g., carbon fiber, etc.), fiberglass, printed circuit boards, metals, polymers (e.g., Polyetheretherketone (PEEK), etc.), and the like.

The vias 1104 are through-holes formed in the body 1102 using conventional processing operations, such as metal forming, drilling, electron discharge machining, Deep Reactive Ion Etching (DRIE), and the like. In the depicted example, the channel 1104 has a circular cross-section with a diameter of about 3 mm. Thus, the channel 1104 has a height-to-width aspect ratio of about 8: 1. Preferably, the aspect ratio is at least equal to 3: 1. Additionally, for aspect ratios in excess of 100:1, the flow of vaporized atoms through the collimator begins to decrease to undesirable levels; however, aspect ratios in excess of 100:1 are within the scope of the present invention. In some embodiments, the channels 1104 have a non-circular cross-sectional shape (e.g., square, rectangular, hexagonal, octagonal, irregular, etc.).

The formation of the channels 1104 results in a plurality of walls 1106 residing between the channels. Preferably, to achieve high throughput, the walls 1106 are as thin as possible without sacrificing the structural integrity of the body 1102. In the depicted example, the walls 1106 have an average thickness of about 500 microns; however, any practical thickness for wall 1106 may be used.

Fig. 11B-C depict schematic diagrams of top and cross-sectional views, respectively, of a region of the collimator 208. The channels 1104 are arranged in a honeycomb arrangement, with columns being periodic and adjacent columns being offset from their neighbors by half a period. In some embodiments, the channels are arranged in different arrangements, such as two-dimensional periodic, hexagonal close-packed, random, and the like.

As depicted in fig. 11C, the aspect ratio of the channel 1104 defines a filter angle range. For purposes of this specification, including the appended claims, the term "filter angular range" is defined as the range of propagation angles through the collimator 208 that span an angular range from-thetac to + thetac. Therefore, vaporized atoms with a propagation angle greater than | θ c | will be blocked by the collimator.

Those skilled in the art will recognize that the dimensions provided above for the body 1102, channel 1104, and wall 1106 are merely illustrative, and that other dimensions may be used without departing from the scope of the invention.

In operation 307, the aperture 120 passes the vaporized atoms of the vapor column 214 such that they are deposited on the deposition site R in the deposition region 216.

In optional operation 308, positioning system 212 imparts motion to collimator 208 to improve uniformity of vaporized atom density across the lateral extent of vapor column 214, thereby improving deposition uniformity across deposition sites on substrate 102. In some embodiments, the positioning system 212 is operable to impart an oscillating motion to the collimator 208.

It should be noted that in the illustrative embodiment, the source 104 is generally a point source of the material 116 because the open area of its crucible is significantly smaller than the area of the substrate 102.

In optional operation 309, the positioning system 212 moves the source 104 relative to the substrate in the x-y plane to improve deposition uniformity.

In some embodiments, the source 104 is a linear evaporation source that includes a plurality of nozzles that emit a fan-shaped vapor plume of vaporized atoms. In some embodiments, the positioning system 212 moves the linear source in the x-y plane in a direction that is not aligned with its longitudinal axis to improve uniformity of the deposited material on the substrate 102. In some embodiments, this path is a line that is substantially orthogonal to both the linear arrangement of nozzles and the vertical axis 110. In some embodiments, the linear source is moved along a non-linear path in the x-y plane.

In some embodiments, the source 104 comprises a two-dimensional arrangement of nozzles, each nozzle emitting a conical vapor plume, such that the plurality of nozzles collectively provide a substantially uniform flow of vaporized atoms over the area of the substrate surface. In some embodiments, the positioning system 212 moves a two-dimensional arrangement of nozzles to promote deposition uniformity. In some embodiments, the two-dimensional arrangement of nozzles is rotated in a plane to promote deposition uniformity.

In some embodiments, the source 104 is a two-dimensional planar source that includes a layer of material 116 distributed across its top surface. The source is arranged such that this top surface is parallel to and faces the substrate 102. The material 116 vaporizes uniformly across a plane when heated. Exemplary Planar Evaporation sources suitable for use in embodiments of the present invention are disclosed in "OLED Evaporation Fabrication by Using Novel Planar Evaporation techniques" (int.j.of Photoenergy, vol 2014(18), pages 1 to 8 (2014)) (which is incorporated herein by reference).

In some embodiments, to improve uniformity when the material 116 is deposited over a two-dimensional area of the surface 114, the positioning system 212 imparts relative motion between the source 104 and the combination of the substrate 102 and shadow mask 106 by moving at least one of the substrate/mask combination and the source.

It is understood that the present disclosure teaches only some embodiments according to the invention and that many variations of the invention can be easily envisaged by a person skilled in the art after reading the present disclosure and that the scope of the invention will be determined by the appended claims.

Claims

1. A system for depositing a first material on a plurality of deposition sites in a deposition area of a substrate arranged in a first arrangement, wherein the substrate includes a first major surface and a second major surface comprising the deposition area, the system comprising:

a source for providing a first plurality of vaporized atoms of the first material, each of the first plurality of vaporized atoms propagating along a propagation direction characterized by a propagation angle relative to a first direction perpendicular to a first plane defined by the substrate, wherein a range of propagation angles for the first plurality of vaporized atoms spans a first angular range;

a shadow mask comprising a plurality of vias arranged in the first arrangement, wherein the shadow mask includes a third major surface and a fourth major surface comprising the vias;

a first chuck for holding the substrate, the first chuck being sized and arranged to selectively impart a first suction force to the first major surface;

a second chuck for holding the shadow mask, the second chuck comprising a support, an inside of the support defining a first opening enabling the material to pass through the second chuck to the through-hole, the second chuck being sized and arranged to selectively impart a second suction force to the third major surface and to reduce gravity induced sagging of the shadow mask by inducing a tensile stress in the fourth major surface, and wherein the support has a cross-section defining a mounting surface extending between a first edge proximate the first opening and a second edge distal from the first opening, the mounting surface being in contact with the third major surface when the shadow mask is held in the second chuck, wherein the mounting surface and the first edge meet at a point in a first plane and the mounting surface and the second edge meet at a point in a second plane, and wherein the first plane is closer to the substrate than the second plane when the shadow mask and the substrate are aligned;

a collimator comprising a plurality of channels, the collimator being interposed between the source and the shadow mask, wherein each of the plurality of channels is sized and arranged to pass only vaporized atoms having a propagation angle within a second angular range that is less than the first angular range; and

a positioning system for controlling the relative positions of the first chuck and the second chuck to align the shadow mask and the substrate.

2. The system of claim 1, wherein the first material is an organic material operable to emit light.

3. The system of claim 1, wherein the plurality of deposition sites and the plurality of vias collectively define an acceptable angular range, and wherein the second angular range is less than or equal to the acceptable angular range.

4. The system of claim 1, wherein each of the plurality of channels is characterized by a height-to-width aspect ratio equal to or greater than 3: 1.

5. The system of claim 1, wherein the positioning system is operable to impart relative motion between the substrate and the collimator.

6. The system of claim 1, wherein the first chuck, the second chuck, and the positioning system collectively enable alignment of the substrate and the shadow mask with a spacing between the substrate and the shadow mask that is greater than 0 microns and less than or equal to about 10 microns.

7. The system of claim 1, wherein the mounting surface is non-linear.

8. The system of claim 1, wherein the second chuck further comprises a support grid within the first opening, the support grid sized and arranged to mitigate gravity-induced sagging of the shadow mask.

9. A method for depositing a first material on a plurality of deposition sites arranged in a first arrangement on a substrate, wherein the substrate includes a first major surface and a second major surface having a first lateral extent, the second major surface comprising a first region, wherein the method comprises:

providing a shadow mask comprising a plurality of through holes, the shadow mask having a third major surface and a fourth major surface comprising the plurality of through holes;

holding the substrate in a first chuck that selectively imparts a first suction force to the first major surface;

holding the shadow mask in a second chuck that selectively imparts a second suction force to the third major surface, wherein the second chuck comprises a support, an inner side of the support defining a first opening that enables vaporized atoms of the material to pass through the second chuck to the plurality of through holes, the second chuck being sized and arranged to reduce gravity induced sagging of the shadow mask by inducing tensile stress in the fourth major surface, and wherein the support has a cross-section defining a mounting surface extending between a first edge proximate the first opening and a second edge distal the first opening, the mounting surface contacting the third major surface when the shadow mask is held in the second chuck, wherein the mounting surface and the first edge meet in a first plane and the mounting surface and the second edge meet in a second plane Two planes meeting at a point, and wherein the first plane is closer to the substrate than the second plane when the shadow mask and the substrate are aligned;

positioning the substrate and the shadow mask such that the second major surface and the fourth major surface are separated by a distance greater than 0 microns and less than or equal to 10 microns;

receiving a first plurality of vaporized atoms at a collimator located between a source and the shadow mask, wherein the first plurality of vaporized atoms is characterized by a first range of propagation angles, and wherein the collimator includes a plurality of channels, each channel of the plurality of channels having a high-to-wide aspect ratio that determines a second range of propagation angles that is narrower than the first range of propagation angles;

selectively passing a second plurality of vaporized atoms through the collimator to the shadow mask, wherein the first plurality of vaporized atoms includes the second plurality of vaporized atoms, and wherein the second plurality of vaporized atoms is characterized by the second range of propagation angles; and

at least some of the second plurality of vaporized atoms are enabled to be deposited on the substrate through the second chuck and the plurality of vias.

10. The method of claim 9 wherein the tensile strain in the fourth major surface is induced by affecting a curvature of the shadow mask.

11. The method of claim 9 wherein the gravity induced sag is mitigated by mechanically supporting the shadow mask in an area of the shadow mask that includes the through holes.