TWI626517B - Shadow mask -substrate alignment method - Google Patents

Abstract

In a shadow mask-substrate alignment method, a light source, a beam splitter, a first substrate including a first grating, a second substrate including a second grating, and a photoreceptor are positioned opposite each other to define a An optical path that includes light that is output by the light source and that is first reflected by the beam splitter. The first reflected light passes through the first or second grid and is secondarily reflected by the second or first grid at least rearward portions through the first or second grid. The second reflected light passes at least partially through the beam splitter for receipt by the light receptor. The orientation of the first substrate, the second substrate, or both is adjusted to position the first grid, the second grid, or both until the light receiver receives a predetermined amount.

Description

Shadow mask-substrate alignment method Cross-references to related applications

This application is a continuation-in-part application of U.S. Patent Application Serial No. 13/695,488, filed on Jan. 31, 2012, which is hereby incorporated by reference. In the US national phase, the department claimed to apply for the US Provisional Application No. 61/351,470 on June 4, 2010. The disclosures of the above documents are hereby incorporated by reference in its entirety.

Field of invention

The present invention relates to accurately aligning a shadow mask with a substrate, which is related to the vapor deposition system deposition material on the substrate.

Prior art

The accurate alignment of the vapor deposition system with the shadow mask and substrate is critical for accurate deposition of one or more materials on the substrate. Unfortunately, most vapor deposition systems include closed vacuum deposition vessels in which one or more vapor deposition events occur and it is difficult to manually and accurately align the shadow mask to the substrate. In addition, current automated and semi-automated systems for aligning shadow masks to substrates do not have the necessary alignment accuracy to provide the desired accuracy when vapor deposited material onto the substrate, particularly with multiple different shadows. The mask subjects the substrate to multiple vapor deposition events.

Therefore, an alignment method and system for aligning a shadow mask-substrate are provided It is desirable to have one or more materials vapor-deposited onto the substrate in a highly accurate and repeatable manner via one or more shadow masks.

Disclosed herein is a shadow mask-substrate alignment method comprising the steps of: (a) causing a collimated light source, a beam splitter, a substrate comprising a first grating, including a shadow mask of a second grid, and a light receiver positioned opposite each other to define an optical path including collimated light output by the collimated light source and at least partially reflected by the beam splitter, the at least being The partially reflected collimated light passes through one of the first or second grids and is reflected at least by the other of the first or second grids through the first or the first The one of the two grids and the at least partially reflected light reflected back through the one of the first or second grids at least partially through the beam splitter for being illuminated by the light receptor Receiving; and (b) adjusting an orientation of the substrate, the shadow mask, or both to position the first grid, the second grid, or both the first and second grids until The light receiver receives a predetermined amount.

Each grid may include a plurality of spaced apart bars. A gap separates each pair of spaced apart bars. Each bar can have the same width as each gap.

Each grid may include a plurality of spaced apart bars and a gap separating each pair of spaced apart bars. Step (b) may include adjusting the orientation of the substrate, the shadow mask, or both such that the long axes of the bars of the first grid are parallel to the bars of the second grid The long axis and the bars of the first grid and the second grid are each overlapped with the gaps of the second grid and the first grid.

The bars of the first and second grids may each overlap 50% of the gaps of the second and first grids.

The collimated light source can include an LED and a collimating lens operable to collimate light output by the LED.

The light receiver can include a PIN diode and a focusing lens operable to focus light received from the beam splitter on the PIN diode.

A longitudinal axis of each bar may extend radially by ±15 degrees from a central axis of the corresponding substrate or shadow mask.

Also disclosed herein is a shadow mask-substrate alignment method comprising the steps of: (a) providing a first substrate having a plurality of first gratings arranged in a pattern, wherein each first grating comprises a plurality of spaced apart bars and a gap between each pair of spaced apart bars; (b) providing a second substrate having a plurality of sets arranged in a pattern identical to the plurality of first gratings An open reflective surface, wherein each set of spaced apart reflective surfaces comprises a pair of spaced apart reflective surfaces; (c) defining a plurality of optical paths, wherein each optical path comprises a light source and a light receptor at opposite ends of the optical path, and a beam splitter between the light source and the light receptor; (d) a first grid disposed roughly aligned with a set of spaced reflective surfaces in each of the light paths; and (e) each strip Light rays on the light path are reflected by the light and reflected by the beam splitter, at least one of the spaced apart reflective surfaces in the optical path, and through at least one gap of the first grating in the optical path Finely positioning the first substrate when received by the light receiver of the optical path The second substrate or both.

Each set of spaced apart reflective surfaces may be comprised of a second grid comprising a plurality of spaced apart bars and a gap between each pair of spaced apart bars. Each of the bars of the second grid may define one of the reflective surfaces. Each gap of the second grid may define a structure in the second substrate that has a reflectance less than each of the reflective surfaces.

Each of the light receptors can output a level and one of the light receptors received A signal related to the amount of light. Step (e) may include finely locating the first substrate, the second substrate, or both until a quasi-combination of the signals output by the photoreceptors is equal to a predetermined value or falls within a predetermined range of values. The predetermined value can be zero.

The first substrate and the second substrate may each have a rectangular shape or a square shape. The first substrate can have a first grid adjacent each corner. The second substrate can have a set of spaced apart reflective surfaces adjacent each corner.

Also disclosed herein is a shadow mask-substrate alignment method comprising the steps of: (a) providing a substrate having a plurality of first gratings in a pattern; (b) providing a shadow mask having a plurality of second grids arranged in a pattern identical to the plurality of first grids, wherein each grid comprises a plurality of spaced apart bars and a gap between each pair of spaced apart bars; (c) Defining a plurality of optical paths, wherein each of the optical paths includes a light source, a light receiver, and a beam splitter; (d) placing a first grid roughly aligned with a second grid in each of the light paths; and e) when the light output by the light source of the optical path on the optical path is reflected by the beam splitter of the optical path, the first time passing through one of the first or second grating is in the optical path At least one gap is reflected by the other of the first or second grids in at least one of the optical paths, and the second time passes back to the one of the first or second grids The at least one gap in the optical path is then finely positioned after passing through the beam splitter of the optical path for reception by the optical receiver of the optical path The substrate, the shadow mask, or both, until a predetermined amount of light is received by the light receptor of the optical path.

Each bar can have the same width as each gap.

Step (e) may include finely positioning the substrate, the shadow mask, or both until the bars of the first and second grids are respectively associated with the second and the first grid The gaps of the grid partially overlap.

The bars of the first and second grids may each overlap 50% of the gaps of the second and first grids.

Each optical receiver can output a signal level related to the amount of light received by the optical receiver. Step (e) may comprise the steps of: finely locating the substrate, the shadow mask or both until a quasi-combination of the signals output by the plurality of optical receivers is equal to a predetermined value or falls on a predetermined Within the range of values. The predetermined value can be zero.

The substrate and the shadow mask may each have a rectangular or square shape and a grid adjacent to each corner of the rectangle or square. The longitudinal axis of each bar may extend radially ±15 degrees from the central axis of the corresponding substrate or shadow mask.

2‧‧‧Shadow mask deposition system

4, 4a ~ 4x‧ ‧ deposition vacuum container

6‧‧‧Substrate

8‧‧‧Distribution reel

10‧‧‧Retracting reel

12, 12a, 12b‧‧‧ deposition source

14, 14a, 14b‧‧‧ substrate holder

15, 15a, 15b, 15'‧‧‧ Shadow Mask Alignment System

16, 16a, 16b‧‧‧ shadow mask

20‧‧‧Mobile platform

20A‧‧‧Y-θ platform/mobile platform

20B‧‧‧X-Z platform/mobile platform

22‧‧‧ Controller

24, 24A~24D‧‧‧ light source

26, 26A~26D‧‧‧ light receiver

28, 28A~28D, 30, 30A~30D‧‧‧ Grille

32, 34‧‧‧ central part

36, 36A~36D, 36', 36A'~36D’‧‧‧ light path

38‧‧‧LED

40‧‧‧ Collimating optics/lens

42, 46‧‧‧ rods

44, 48‧ ‧ gap

50‧‧‧Focus optics/lens

52, 52A~52D‧‧‧PIN diode

54‧‧‧ Analog to Digital (A/D) Converter

60, 60A~60D‧‧ ‧ beam splitter

110‧‧‧Photoresist Deposition Station

112‧‧‧ baking station

114‧‧‧ Grinding station

Θ1, θ2‧‧‧ nominal azimuth

X, Y, Z, θ‧‧‧ directions

1A schematically illustrates a shadow mask deposition system for forming a pixel structure of a high resolution OLED active matrix backplane; FIG. 1B is an enlarged view illustrating a single deposition vacuum vessel of the shadow mask deposition system of FIG. 1A; FIG. A first embodiment of the shadow mask alignment system is schematically illustrated; the plan views of Figures 3A and 3B each illustrate an exemplary substrate and a shadow mask, both of which include a plurality of alignment grids to facilitate shadow masking of the substrate. Azimuth and positioning, and vice versa; Figure 4 is a view taken along line IV-IV in Figure 2; Figure 5 is a view taken along line VV in Figure 2; Figure 6 is a schematic view of the shadow mask A second embodiment of the alignment system; Figure 7 is a view taken along line VI-VI in Figure 6; and Figure 8 is a view taken along line VII-VII in Figure 6.

Referring to FIGS. 1A and 1B, a shadow mask deposition system 2 for forming an electronic device such as, but not limited to, a high-resolution active matrix organic light-emitting diode (OLED) display includes a plurality of deposition vacuum containers 4 arranged in series. (For example, vacuum containers 4a to 4x are deposited). The arrangement and number of deposition vacuum vessels 4 depends on the number of necessary deposition events for any given product to be formed therefrom.

In an exemplary non-limiting use of the shadow mask deposition system 2, the continuous flexible substrate 6 is by means of a reel-to-reel mechanism comprising a dispensing reel 8 and a take-up reel 10. (reel-to-reel mechanism) to translate through the deposition vacuum vessel 4 arranged in series. Alternatively, substrate 6 can be a separate (or continuous) substrate that is translated through a series arrangement of vacuum vessels 4 using any of the conventional components of the art. Hereinafter, in order to describe the present invention, it is assumed that the substrate 6 is a separate substrate.

For any plurality of deposition vacuum vessels 4, each deposition vacuum vessel includes a deposition source 12, a substrate holder 14, a shadow mask alignment system 15, and a shadow mask 16. For example, the deposition vacuum vessel 4a includes a deposition source 12a, a substrate holder 14a, a mask alignment system 15a, and a shadow mask 16a; the deposition vacuum vessel 4b includes a deposition source 12b, a substrate holder 14b, a mask alignment system 15b, and a shadow Mask 16b; and so on.

Each deposition source 12 is filled with a desired material that will be deposited on the substrate 6 by one or more openings corresponding to the shadow mask 16 during deposition, corresponding to the shadow mask 16 in the corresponding deposition vacuum vessel 4 and the substrate 6. Some remain in close contact. The shadow mask 16 can be disclosed as a type in U.S. Patent No. 7,638,417 to Brody. Conventional single layer shadow masks or composite (multilayer) shadow masks are incorporated herein by reference.

Each shadow mask 16 of the shadow mask deposition system 2 includes one or more openings. The openings (or numbers) in each of the shadow masks 16 correspond to materials that will be deposited on the substrate 6 by corresponding deposition sources 12 in the corresponding deposition vacuum vessel 4 as the substrate 6 is translated through the shadow mask deposition system 2. The desired graphic.

Each of the shadow masks 16 may be composed of, for example, nickel, chrome, steel, copper, Kovar or Invar, and preferably between 20 and 200 microns thick, and between 20 and 50. Better between microns. For example, Kovar and Invar may be obtained from ESPICorp, Inc., Azul, Oregon, USA. In the United States, Kovar Alloy® is registered under No. 337,962 and is currently owned by CRS Holdings of Wilmington, Delaware, and the registered trademark of Invar® is No. 63,970, currently by Imphy SA of France. have.

Those skilled in the art will appreciate that the shadow mask deposition system 2 can include additional platforms (not shown), such as an annealing platform, a test platform, one or more cleaning platforms, a cutting and mounting platform, and the like. Moreover, for a particular application, one of ordinary skill in the art can modify the number, purpose, and arrangement of deposition vacuum vessels 4 as needed to deposit one or more materials in the desired order. An exemplary shadow mask deposition system and method of use thereof are disclosed in U.S. Patent No. 6,943,066, the disclosure of which is incorporated herein by reference.

The deposition vacuum vessel 4 can be used to deposit several materials on the substrate 6 to form one or more electronic components of the electronic device on the substrate 6. Each of the electronic components may be, for example, a thin film transistor (TFT), a memory element, a capacitor, or the like. A combination of one or more electronic components can be deposited to form higher level electronic components, such as but not Limited to, sub-pixels or pixels of an electronic device. The multilayer circuit can be separately formed by continuously depositing material on the substrate 6 via the deposition vacuum vessel 4 in a continuous deposition event as described in U.S. Patent No. 6,943,066, the disclosure of which is incorporated herein by reference.

Each deposition vacuum vessel 4 is connected to a vacuum source (not shown) that is operable to establish a suitable vacuum therein to enable the material disposed in the corresponding deposition source 12 to be in a manner known in the art (eg, , sputtering or vapor deposition) is deposited on the substrate 6 through one or more openings corresponding to the shadow mask 16.

Regardless of the form of the substrate 6, for example, a continuous sheet or a separate substrate, each deposition vacuum container 4 can include a holder or guide that avoids sagging of the substrate 6 as it is translated through it.

During operation of the shadow mask deposition system 2, as the substrate 6 travels through the deposition of the vacuum vessel 4, the material disposed at each deposition source 12 is deposited by one or more openings of the corresponding shadow mask 16 under appropriate vacuum. Corresponding to the substrate 6 in the deposition vacuum vessel 4, a plurality of continuous patterns are formed on the substrate 6. More specifically, the substrate 6 is positioned in each deposition vacuum vessel 4 for a predetermined time interval. During this predetermined time interval, material is deposited on the substrate 6 by the corresponding deposition source 12. After this predetermined time interval, the substrate 6 is advanced to the next series of vacuum vessels for additional processing (if applicable). Moving on until the substrate 6 passes through all of the deposition vacuum vessel 4 and the substrate 6 leaves the last deposition vacuum vessel 4 in the sequence.

Referring to FIG. 2 and with continued reference to FIGS. 1A and 1B, the mask alignment system 15 includes one or more moving platforms 20 for controlling the orientation and position of the substrate 6, the shadow mask 16, or both for alignment as will be described later. Substrate 6 and shadow mask 16. A desirable non-limiting embodiment of the mask alignment system 15 includes a base coupled to the Y-theta platform 20A. The board 6 is coupled to a shadow mask 16 of the X-Z stage 20B. Utilizing one or more platforms 20 such that the substrate 6, shadow mask 16 or both are in the X, Y, Z and / or θ directions (in the present embodiment, the θ direction is the rotation of the substrate 6 in the XY plane) The translation, orientation and positioning are known to the art and will not be further described herein for the sake of brevity.

The Y-theta platform 20A and the XZ platform 20B are operated under the control of the controller 22, and the controller 22 can be implemented with any suitable and/or desirable combination of hardware and/or software to enable control of the mobile platform 20A in a manner that will be described later. And 20B.

The mask alignment system 15 further includes one or more light sources 24 and one or more light receivers 26. Each light source 24 is positioned to be aligned with a light receiver 26 to define a pair of light sources 24-to-light receiver 26. Each pair of light sources 24-optical receiver 26 defines an optical path 36 therebetween.

When the mask is used to align the system, the substrate 6 and the shadow mask 16 are positioned in the optical path 36 of each pair of light sources 24-photoreceiver 26. In a preferred embodiment, the mask alignment system 15 includes four light sources 24 and four light receivers 26, for a total of four pairs of light sources 24-light receivers 26 defining four optical paths 36. However, this should not be construed as limiting the invention.

Referring to FIGS. 3A-3B and continuing to refer to FIGS. 1A-1B and 2, the substrate 6 includes one or more grids 28, and the shadow mask 16 includes one or more grids 30. In a non-limiting embodiment, the substrate 6 includes four grids 28A-28D and the shadow mask 16 includes four grids 30A-30D. In the particular embodiment illustrated in FIG. 3A, the substrate 6 has a rectangular or square shape and each of the grids 28A-28D is positioned adjacent one of the four corners of the substrate 6. Likewise, the shadow mask 16 has a rectangular or square shape and each of the grids 30A-30D is positioned in four corners of the shadow mask 16 One of them is adjacent. The central portion of the substrate 6 (indicated by reference numeral 32) is where deposition events will occur on the substrate 6. The central portion of the shadow mask 16 (indicated by reference numeral 34) is where the shadow mask 16 contains a pattern of one or more openings through which material from the deposition source 12 is deposited on the region 32. The graphic is the same as the one formed by one or more of the openings in the shadow mask 16 region 34.

In the particular embodiment of the substrate 6 illustrated in FIG. 3A, the grid 28B is a mirror image of the grid 28A centered on the Y-axis of FIG. 3A; and the grids 28C, 28D are each illustrated by the grids 28B, 28A. The x-axis of 3A is a mirror image of the centerline. However, this should not be construed as limiting the invention.

Similarly, in a particular embodiment of the shadow mask 16 illustrated in FIG. 3B, the grid 30B is a mirror image of the grid 30A centered on the Y-axis of FIG. 3B; and the grids 30C, 30D are grids 30B, Each of 30A is mirrored with the X-axis of Fig. 3B as a center line. However, this should not be construed as limiting the invention.

A shadow mask 16 that aligns the substrate 6 of one or more of the grids 28 with one or more grids 30 using the mask alignment system 15 is now described.

Initially, as shown in FIG. 2, the substrate 6 is moved in and is spaced (or substantially) from the shadow mask 16 in the optical path 36 between the light source (or plurality) 24 and the light receiver (or plurality) 26. alignment. When the substrate 6 and the shadow mask 16 are roughly aligned in the optical path 36 shown in FIG. 2, each of the grids 28 of the substrate 6 and each of the grids 30 of the shadow mask 16 are positioned at a pair of light sources 24 - light receivers 26 of a light path 36. For example, the mask alignment system 15 includes four pairs of light source-light receivers 24A-26A, 24B-26B, 24C-26C, and 24D-26D each defining four optical paths 36A-36D, and the substrate 6 includes a grid 28A-28D. And when the shadow mask 16 includes the grids 30A-30D: the grids 28A and 30A are positioned in the light path 36A from the light source 24A to the light receiver 26A; the grids 28B and 30B Positioned in the optical path 36B from the light source 24B to the light receiver 26B; the grids 28C and 30C are positioned in the optical path 36C from the light source 24C to the light receiver 26C; and the grids 28D and 30D are positioned from the light source 24D to the light receiving In the optical path 36D of the device 26D.

4 is a plan view showing the substrate 6 and the shadow mask 16 roughly aligned between the light sources 24A-24D, the light receivers 26A-26D (shown in phantom), and each for each pair of light source-light receivers. The position of the light path 36A-36D. It should be understood that, in FIG. 4, the grids 28A and 30A are located in the optical path 36A; the grids 28B and 30B are located in the optical path 36B; the grids 28C and 30C are located in the optical path 36C; and the grids 28D and 30D are located in the optical path 36D.

Referring to FIG. 5, a fine alignment of one of the grids 28 of the substrate 6 with one of the grids 30 of the shadow mask 16 (i.e., a pair of grids 28-30) along an optical path 36 is described. However, it should be understood that the fine alignment of the grid pairs 28-30 along the optical path 36 of FIG. 5 can also be applied to the alignment of the pairs of grids 28-30 located in each of the optical paths 36.

At the appropriate time, each light source 24 is activated to output light along its optical path 36. In a non-limiting embodiment, each light source includes an LED 38 that outputs light to a collimating optic/lens 40 that collimates light output by LED 38 and along optical path 36. The collimated light is output.

Each of the grids 28 of the substrate 6 includes a plurality of spaced apart bars 42, preferably spaced apart parallel bars. Each pair of spaced apart bars 42 has a gap 44. Preferably, each gap 44 has the same width. Likewise, each grid 30 includes a plurality of spaced apart bars 46, preferably spaced apart parallel bars. Each pair of spaced apart bars 46 has a gap 48. Preferably, each gap 48 has the same width. Preferably, each gap 44 and each gap 48 have the same width. However, the same gap width of both the grid 28, the grid 30, the grids 28 and 30 should not be construed as limiting the invention.

With continued reference to FIG. 5 and with reference to FIGS. 3A and 3B, it is not necessary to orient or position each gap of each bar or substrate 6 and shadow mask 16 to have the same angle for each of the X axes. For example, the longitudinal axis of each bar 42 and each gap 44 of the substrate 6 are preferably nominally oriented or positioned to have a 45 degree θ1 for the X axis of FIG. 3A. However, with respect to the X-axis, the azimuth angle θ1 of each of the bars 42 and the longitudinal azimuth 44 of each of the gaps 44 may differ by ±15 degrees from the nominal azimuth angle θ1 of 45 degrees. Additionally, each bar 42 can be oriented or positioned with a different angle θ1 from each gap 44. However, the bars 42 of each of the grids of the substrate 6 are preferably parallel to the gaps 44.

Likewise, the longitudinal axis of each bar 46 and each gap 48 of the shadow mask 16 are preferably nominally oriented or positioned at an angle θ2 of 45 degrees with respect to the X-axis of Figure 3B. However, with respect to the X-axis, the azimuth angle θ2 of the longitudinal axis of each bar 46 and each gap 48 may differ by ±15 degrees from the nominal azimuth angle θ2 of 45 degrees. Additionally, each bar 46 can be oriented or positioned at a different angle θ2 from each gap 48. However, the bars 46 of each of the grids of the shadow mask 16 are preferably parallel to the gap 48.

More generally, the longitudinal axes of each of the bars 42, 46, preferably each of the longitudinal axes of the gaps 44, 48 extend radially outwardly of the substrate 6, the center of the shadow mask 16, by ±15 degrees. For each grid, the bars of the grid are preferably parallel to the gap. However, depending on the circumstances, it is also contemplated that the bars and gaps of the grid may extend radially from the center of the substrate 6 or shadow mask 16 in a radial pattern. Thus, for example and without limitation, the longitudinal axis of each of the bars 42, 46 and the longitudinal axis of each of the gaps 44, 48 may be when the angles θ1 - θ2 are oriented or positioned at an angle of 30 degrees for the corresponding X axis. It differs from 30 degrees by ±15 degrees.

It will be appreciated that the angular displacement between the bars 42 and 46 of any pair of grids 28-30 and the gaps 48, 44 may differ by as much as 30 degrees, for example, when the bar 42 has 60 for the X axis of the substrate 6. At a degree angle, the gap 48 is for its shadow mask 16 The X-axis has a 30 degree angle, and the substrate 6 is parallel to the X-axis of the shadow mask 16; 60 degrees minus 30 degrees is equal to 30 degrees.

The collimated light output by the light source 24 passes through the gaps 44, 48 of the roughly aligned grids 28, 30, and is received by the light receiver 26. The light receiver 26 includes a focusing optics/lens 50 that focuses on the collimated light that passes through the roughly aligned gaps 44, 48 of the grids 28, 30 to be illuminated by the light detecting member in the form of a PIN diode 52. receive. In the mask alignment system 15, the output of each PIN diode 52 of each of the light receivers 26 is provided to an analog to digital (A/D) converter 54 of the controller 22 for each PIN diode. The analog output of body 52 is converted to a corresponding digital signal for processing by the processing component of controller 22. The output of each PIN diode 52 corresponds to the amount of light received by the PIN diode 52. The greater the amount of light received by the PIN diode 52, the greater its output voltage; the greater the amount of light received by the PIN diode 52 Small, its output voltage is smaller.

At the appropriate time, controller 22 begins to finely position substrate 6, shadow mask 16 or both via Y-theta platform 20A and/or XZ platform 20B to align substrate 6 with shadow mask 16 thereby positioning Each pair of grids 28-30 is in the optical path 36. At least some of the bars 42 overlap with some of the gaps 48 in the grid 30 (in the direction transverse to the optical path 36, preferably perpendicularly) to the desired The extent, and the grid 30, at least some of the bars 46 overlap with some of the gaps 44 in the grid 28 (preferably perpendicular to the direction of the optical path 36), to the desired extent. As shown in FIG. 5, preferably each gap 48 of the shadow mask 16 partially overlaps the bar 42 of the substrate 6, and each gap 44 of the substrate 6 partially overlaps the bar 46 of the shadow mask 16. More desirably, the bars 42 and 46 overlap 50% of the width of the gaps 48, 44, respectively. In other words, the gaps 48, 44 have a 50% width that overlaps the bars 42, 46.

For each pair of grids 28-30 located in one of the optical paths 36, the controller 22 takes the digitized output of the PIN diode 52 on the optical path 36 (this digital output is obtained via the A/D 54). And the digitized output corresponds to a collimated light passing through the gaps 48, 44) for comparison with a predetermined value or a predetermined range of values to detect when the bars 42, 46 overlap the gaps 48, 44 to a desired extent. Upon detecting that the digitized output of the PIN diode 52 is not within a predetermined or predetermined range of values, the controller 22 causes the one or more mobile platforms 20A and 20B to adjust the substrate 6, shadow mask 16 or both as needed. The X, Y, and/or θ positions until the controller 22 detects via the digitized output of the PIN diode 52 that the bars 42, 46 are each overlapped with the gaps 48, 44 of the grid pair 28-30. Quantity. Since the number of bars 42, 46 overlapping each of the grid pairs 28-30 gaps 48, 44 affects the amount of collimated light reaching the PIN diode 52, by comparing the digitized output of the PIN diode 52 to a predetermined value Or a predetermined range of values, the controller 22 can determine when the appropriate amount of overlap of the gap between the bar and the pair of grilles 28-30 at the optical path 36 is achieved. In a similar manner, controller 22 can determine when the appropriate amount of overlap of the bar with each of the other pairs of grids 28-30 at each of the other optical paths 36 is achieved.

In a non-limiting embodiment, controller 22 preferably combines the outputs of all of PIN diodes 52 in optical receivers 26A-26D to determine when substrate 6 and shadow mask 16 have reached an appropriate X, Y, and θ pair. quasi. More specifically, assume that controller 22 adjusts the orientation/position of substrate 6, shadow mask 16, or both. After a certain period of time, the controller 22 stops adjusting the orientation/position of the substrate 6, the shadow mask 16, or both, and causes the A/D 54 to sample and digitize the PIN diodes in the optical receivers 26A-26D. The output of 52A-52D (shown in Figure 4). The controller 22 combines the digitized output of the PIN diodes 52A-52D with the variables f1-f4, and the X, Y and rotation or angle of the substrate 6, shadow mask 16, or both in the memory of the controller 22. ) displacement is used below Combine the variables: ‧ (Equation 1) X displacement = f1 - f2 - f3 + f4‧ (Equation 2) Y displacement = f1 + f2 - f3 - f4; and ‧ (Equation 3) θ displacement = f1 - f2 +f3-f4.

When the controller 22 determines that the X, Y, and θ displacements determined by Equations 1-3 above are each equal to 0, the controller 22 recognizes that this corresponds to the alignment of the substrate 6 and the shadow mask 16. On the other hand, if any of the X displacement, the Y displacement, or the θ displacement is not equal to 0, the controller 22 recognizes that this corresponds to the substrate 6 and the shadow mask 16 having no alignment, and the controller 22 causes one or More mobile platforms 20A-20B adjust the X, Y and/or θ position (or several) of the substrate 6, the shadow mask 16 or both, and the X displacement and the Y displacement determined by the above equations 1-3 depending on actual needs. Or the θ shifts are each equal to zero.

The controller 22 preferably repeats the steps of: adjusting the orientation/position of the substrate 6, the shadow mask 16, or both; stopping the orientation/position of the adjustment substrate 6, the shadow mask 16, or both; sampling and digitizing the PIN diode The outputs of the bodies 52A-52D; and, determining whether the X, Y, and θ displacements determined by Equations 1-3 above are each equal to 0 until the X, Y, and θ displacements determined by Equations 1-3 above are each substantially equal to 0, These steps have occurred a predetermined number of repetitions, or a predetermined time has elapsed.

After determining that the X, Y, and θ displacements are each equal to 0, the controller 22 causes the moving platform 20 moving in the Z direction to cause the substrate 6 and the shadow mask 16 to become in close contact from the spaced relationship of FIG. 5, which is in a spaced relationship. The purpose is to align the substrate 6 with the shadow mask 16.

However, it should not be considered that using Equations 1-3 to determine that the X, Y, and θ displacements are each equal to 0 in the above manner is intended to limit the invention, since it is assumed that each displacement can be The displacement is unique or within a suitable range of values that are common to the displacements. For example and without limitation, the controller 22 can be programmed to have an X displacement that is within a range of ±1 acceptable, a Y displacement that falls within a range of ±1.5, and fall within a range of ±0.5. The θ displacement is acceptable. Alternatively, controller 22 can be programmed to use the same range of values for each displacement. For example, controller 22 can be programmed such that it accepts that each of the X, Y, and θ displacements falls within the range of ±1.

It can be seen that with the output of the PIN diodes 52A-52D of the light receivers 26A-26D, the controller 22 can cause the substrate 6 and shadow mask 16 to be in a desired alignment with a high degree of accuracy. To this end, the controller 22 can progressively change the orientation/position of the substrate 6, shadow mask 16, or both until the grid 28 of the substrate 6 is aligned with the grid 30 of the shadow mask 16 to the desired extent. In the case where the controller 22 determines that the substrate 6 and the shadow mask 16 need further alignment, the controller 22 can make an sensible decision on the substrate by the X, Y, and θ displacement values determined by Equations 1-3 above. 6. The shadow mask 16 or both are moved or rotated in that direction in the X, Y, and θ directions to improve alignment of the substrate 6 with the shadow mask 16. Therefore, the controller 22 can orient/position the substrate 6, the shadow mask 16 or both in the first position, and then take the output of the PIN diodes 52A-52D of the light receivers 26A-26D to determine the substrate 6 and the shadow mask. 16 is properly aligned. If so, the controller 22 causes the substrate 6 to enter in close contact with the shadow mask 16 in the Z direction to prepare for deposition events that occur in the deposition vacuum vessel 4. However, if it is determined that the substrate 6 and the shadow mask 16 are not properly aligned, the controller 22 may progressively change the direction/position of the substrate 6, the shadow mask 16, or both to other locations, where the controller 22 samples the light reception. The outputs of the PIN diodes 52A-52D of the devices 26A-26D. Continue sampling the output of the PIN diodes 52A-52D of the optical receivers 26A-26D and progressively changing the direction/position of the substrate 6, shadow mask 16 or both until the controller 22, with the program of the controller 22, it is determined that the substrate 6 is aligned with the shadow mask 16 to a desired extent.

It can also be seen that the controller 22 causes the orientation of the substrate 6, shadow mask 16 or both to be adjusted to position the grid 28 of the substrate 6 and the grid 30 of the shadow mask 16, or both, until each light path 36 has A predetermined amount of collimated light passes through the grid that falls on the optical path 36 for acceptance by the corresponding light receiver 26. In other words, the controller 22 finely positions the substrate 6, the shadow mask 16, or both until a predetermined number of rays of light on each of the optical paths 36 pass through the grid of the path and are received by the light receiver on the optical path.

Referring to Figure 6, all aspects of the shadow mask alignment system 15' are similar to the mask alignment system 15 illustrated in Figure 2, except for the following: each pair of light sources 24-photoreceptors 26 is located on the same side of substrate 6 and shadow mask 16; and each pair of light source 24-photoreceptor 26 and beam splitter 60 together define an optical path 36'. More specifically, each of the grids 28 of the substrate 6 and each of the grids 30 of the shadow mask 16 are located in an optical path 36' of the light source 24-photoreceptor 26 of Fig. 6. Each of the optical paths 36' extends from the light source 24 for reflection by one of the beam splitters 60, one of the beam splitters 60 passing through the shadow mask 30 of the substrate 6 and the substrate 6. The grid 30 aligned with the grid 28 reflects the light from the source 24 toward the grid 28. Some of the light striking the grid 28 of the substrate 6 is reflected back by the grid 28 through the grid 30 in the shadow mask 16 that is aligned with the grid 28 toward the beam splitter 60. The beam splitter 60 causes some of the light rays reflected from the grid 28 of the substrate 6 after passing through the grid 30 aligned with the grid 28 in the shadow mask 16 to reach the light receptor 26 at the end of the light path 36'. .

The above description assumes that both the light source 24-photoreceptor 26 pair and the beam splitter 60 are located on the opposite side of the shadow mask 16 from the substrate 6. However, this is an idea, Light source 24-photoreceptor 26 pair and beam splitter 60 may be located on the other side of substrate 6, and then light from source 24 that is reflected by beam splitter 60 is first worn before being partially reflected by grid 30 of shadow mask 16. The passages through the grid 28 of the substrate 6 and the partially reflected light passing back through the grid 28 to the beam splitter 60 are such that some of the reflected light passing through the grid 30 is transmitted to the light receptor 26. Accordingly, in the foregoing description and illustration of FIG. 6, the light source 24-photoreceptor pair 26 and the beam splitter 60 located on the opposite side of the shadow mask 16 from the substrate 6 should not be considered as being invented by the present invention. It is considered to be limiting of the invention.

A shadow mask 16 that aligns the substrate 6 of one or more of the grids 28 with one or more of the grids 30 with the mask alignment system 15' will now be described.

Initially, the substrate 6 is moved into a roughly (or substantially) aligned relationship with the shadow mask 16. When the substrate 6 is roughly aligned with the shadow mask 16, each of the grids 28 of the substrate 6 and each of the grids 30 of the shadow mask 16 are positioned in the optical path 36' of the pair of light sources 24-photoreceptors 26. For example, if the mask alignment system 15' includes four pairs of light source-light receptors 24A-26A, 24B-26B that each define four optical paths 36A', 36B', 36C', and 36D' (also shown in FIG. 7), 24C-26C and 24D-26D (schematically shown in Figure 7), and substrate 6 includes grids 28A, 28B, 28C, and 28D, and shadow mask 16 includes grids 30A, 30B, 30C, and 30D: grid 28A and The 30A position is in the optical path 36A' extending from the light source 24A via the beam splitter 60A to the light receptor 26A; the grids 28B and 30B are located in the optical path 36B' extending from the light source 24B via the beam splitter 60B to the light receptor 26B; The grids 26C and 30C are located in the optical path 36C' extending from the light source 24C via the beam splitter 60C to the light receptor 26C; and the grids 28D and 30D are located from the light source 24D via the beam splitter 60D to the light receptor 26D. Light path 36D'.

The top view of Figure 7 illustrates a substrate 6 that is roughly aligned with the shadow mask 16, wherein the light sources 24A through 24D, the light receptors 26A through 26D (shown in dashed lines), Beams 60A through 60D (shown in phantom), and optical paths 36A'-36D' for respective pairs of light source-light receivers. In FIG. 7, it should be understood that the grids 28A and 30A are located in the optical path 36A'; the grids 28B and 30B are located in the optical path 36B'; the grids 26C and 30C are located in the optical path 36C'; and the grids 28D and 30D Located in the optical path 36D'.

Referring to Figure 8, a fine alignment of one of the grids 28 of the substrate 6 with one of the grids 30 of the shadow mask 16 (i.e., a pair of grids 28-30) along an optical path 36' is now described. However, it should be understood that the fine alignment of the grid pairs 28-30 along the optical path 36' of Figure 8 can also be applied to the alignment of the other pairs of grids 28-30 located in each of the other optical paths 36.

Starting with a shadow mask 16 in spaced relationship with the substrate 6, each light source 24 is activated to output light along its optical path 36' at the appropriate time. In a non-limiting embodiment, each light source includes an LED 38 that outputs light to a collimating optic/lens 40 that collimates light output by LED 38 and outputs the collimated light At least the collimated light portion output by the collimating optics/lens 40 is reflected to the beam splitter 60 of a grid pair 28-30.

As noted above, each of the grids 30 of the shadow mask 16 includes a plurality of spaced apart bars 46, preferably spaced apart parallel bars. Each pair of spaced apart bars 46 has a gap 48. Preferably, each gap 48 has the same width. Likewise, each of the grids 28 of the substrate 6 includes a plurality of spaced apart bars 42, preferably spaced apart parallel bars. Each pair of spaced apart bars 42 has a gap 44. Preferably, each gap 44 has the same width. Again, it is preferred that the width of each gap 44 and each gap 48 be the same. However, the same gaps 44, 48 of the grid 28, grid 30 or grids 28 and 30 should not be considered as limiting the invention.

The collimated light from the beam splitter 60 through the gaps 48 of the grid 30 and the gaps 44 of the grid 28 does not contribute to the light reflected by the spaced bars 42 of the grid 28. Do not The collimated light reflected by the spaced bars 42 of the grid 28 returns to the gap 48 that passes through the grid 30 and propagates toward the beam splitter 60. At beam splitter 60, at least a portion of the reflected light passes through beam splitter 60 for receipt by photoreceptor 26.

The focusing optics/lens 50 of the light receiver 26 concentrates the portion of the reflected light that passes through the beam splitter 60 toward the light detecting member in the form of a PIN diode 52. The output of each PIN diode 52 of each of the light receptors 26 of the mask alignment system 15' is provided to an analog to digital (A/D) converter 54 of the controller 22 (shown in Figure 6), which will The analog output of each PIN diode 52 is converted to a corresponding digital signal for processing by the processing component of controller 22. The output of each PIN diode 52 corresponds to the amount of light received by the PIN diode 52.

At the appropriate time, controller 22 initiates fine positioning of substrate 6, shadow mask 16 or both via Y-theta platform 20A and/or XZ platform 20B to align substrate 6 with shadow mask 16 such that Each of the optical paths 36', some of the bars 42 of the grid 28 overlap with some of the gaps 48 of the grid 30 (in the lateral direction, preferably perpendicular to the optical path 36'), and conversely, the bars 46 of the grid 30 At least some of the overlap with the gap 44 of the grid 28 is (in the lateral direction, preferably perpendicular to the optical path 36'). Preferably, each gap 48 of the shadow mask 16 partially overlaps the bar 42 of the substrate 6, and each gap 44 of the substrate 6 partially overlaps the bar 46 of the shadow mask 16, as shown in FIG. The bars 42 and 46 partially overlap the widths of the gaps 48 and 44 by a desired percentage, such as 50%. In other words, the gaps 48 and 44 each have a width of 50% overlapping the bars 42 and 46.

For each pair of grids 28-30 associated with one of the optical paths 36', the controller 22 detects when the bar 42 overlaps the gap 48 to a desired extent by comparing the PIN diode 52 to the optical path 36'. Digital output on a predetermined value or a predetermined value The range, wherein the digital output is obtained via A/D 54 and the digital output corresponds to light reflected from the bar 42 through the gap 48.

When detecting that the digital output of the PIN diode 52 is not equal to or within a predetermined value range, the controller 22 causes the one or more moving platforms 20A and/or 20B to adjust the substrate 6, the shadow mask 16, or both as needed. The X, Y, and/or θ positions until the controller 22 detects the gap 48 of the bar 42 and the pair of grilles 28-30 via the digital output of the PIN diode 52. Since the amount of overlap of the bar 42 and the gap 48 of the grid pair 28-30 affects the amount of collimated light reaching the PIN diode 52, by comparing the digital output of the PIN diode 52 with a predetermined value or a predetermined range of values, control The device 22 can determine when the bar 42 and the gap 48 of the pair of grilles 28-30 associated with the optical path 36' have achieved an appropriate amount of overlap. In a similar manner, controller 22 can determine when the bar 42 and the gaps 48 of the other pairs of grids 28-30 associated with the other respective optical paths 36' have achieved an appropriate amount of overlap.

In a non-limiting embodiment, controller 22 preferably combines the outputs of all of PIN diodes 52 of light receptors 26A through 26D to determine when substrate 6 and shadow mask 16 have achieved the appropriate X, Y, and θ pairs. quasi. More specifically, it is assumed that the controller adjusts the orientation/position of the substrate 6, the shadow mask 16, or both. After a certain period of time, the controller stops adjusting the orientation/position of the substrate 6, the shadow mask 16 or both, and adjusts the PIN diodes 52A to 52D of the A/D 54 sampling and digitizing light receivers 26A to 26D ( The output shown in Figure 7). The controller 22 causes the digital outputs of the PIN diodes 52A to 52D to be associated with the variables f1-f4 in the memory of the controller 22 and the X, Y and rotation or angle (θ) of the combined substrate 6, shadow mask 16, or both. The variation of the displacement is as follows: ‧ (Equation 1) X displacement = f1-f2-f3 + f4 ‧ (Equation 2) Y displacement = f1 + f2 - f3 - f4; and ‧ (Equation 3) θ displacement = f1 - f2 + f3 - f4. Equations 1 through 3 above are copies of Equations 1 through 3 mentioned above when describing the mask alignment system 15 of the first embodiment.

When the controller 22 determines that the X, Y, and θ displacements determined by the above Equations 1 through 3 are each equal to zero, the controller 22 considers this state to correspond to the substrate 6 and the shadow mask 16 to be aligned. On the other hand, if any of the X displacement, the Y displacement, or the θ displacement is not equal to zero, the controller 22 considers this state to correspond to the substrate 6 and the shadow mask 16 that are not to be aligned, and then the controller 22 causes one or more The multiple moving platforms 20A-20B adjust the X, Y, and/or θ positions of the substrate 6, shadow mask 16, or both as needed to cause the X, Y, or θ displacements determined by Equations 1 through 3 above to be equal to zero, respectively.

The controller 22 preferably repeats the steps of: adjusting the orientation/position of the substrate 6, the shadow mask 16, or both; stopping the orientation of the substrate 6, the shadow mask 16, or both; sampling and digitizing the PIN II The outputs of the pole bodies 52A to 52D; and determining whether the X displacement, the Y displacement, or the θ displacement determined by the above Equations 1 to 3 are each equal to zero until the X, Y, and θ displacements determined by the above Equations 1 to 3 are each actually equal to zero; or until The steps have been performed a predetermined number of repetitions; or until a predetermined amount of time has elapsed.

When it is determined that the X, Y, and θ displacements are each equal to zero, the controller 22 causes the motion platform 20B to move in the Z direction to cause the substrate 6 to move into close contact with the shadow mask 16 from the position illustrated in FIG. 8 in a spaced relationship, which The separation relationship is used to align the substrate 6 with the shadow mask 16.

X, Y, and θ displacements are determined in the above manner using Equations 1 through 3 The respective equals to zero should not be considered as limiting the invention, as it is contemplated that the various displacements may be within a suitable numerical range that is unique to the displacement or common to the displacements. For example and without limitation, the controller 22 can be programmed to have an X displacement that is within a range of ±1 acceptable, a Y displacement that falls within a range of ±1.5, and fall within a range of ±0.5. The θ displacement is acceptable. Alternatively, controller 22 can be programmed to use the same range of values for each displacement. For example, controller 22 can be programmed such that it can accept each of the X, Y, and θ displacements that fall within the range of ±1.

It can be seen that with the outputs of the PIN diodes 52A to 52D of the photoreceptors 26A to 26D, the controller 22 can cause the substrate 6 and the shadow mask 16 to be highly accurately aligned. To this end, the controller 22 can progressively change the orientation/position of the substrate 6, shadow mask 16, or both until the grid 28 of the substrate 6 is in a desired degree of alignment with the grid 30 of the shadow mask 16. In the case where the controller 22 determines that the substrate 6 and the shadow mask 16 need further alignment, the controller 22 can make an sensible decision on the substrate by the X, Y, and θ displacement values determined by Equations 1-3 above. 6. The shadow mask 16 or both are moved or rotated in that direction in the X, Y, and θ directions to improve alignment of the substrate 6 with the shadow mask 16. Therefore, the controller 22 can orient/position the substrate 6, the shadow mask 16 or both in the first position, and then take the output of the PIN diodes 52A-52D of the light receivers 26A-26D to determine the substrate 6 and the shadow mask. 16 is properly aligned. If so, the controller 22 causes the substrate 6 to enter in close contact with the shadow mask 16 in the Z direction to prepare for deposition events that occur in the deposition vacuum vessel 4. However, if it is determined that the substrate 6 and the shadow mask 16 are not properly aligned, the controller 22 may progressively change the direction/position of the substrate 6, the shadow mask 16, or both to other locations, where the controller 22 samples the light reception. The outputs of the PIN diodes 52A-52D of the devices 26A-26D. Continue to sample the output of the PIN diodes 52A-52D of the optical receivers 26A-26D and the tired The process of changing the orientation/position of the substrate 6, the shadow mask 16, or both is advanced until the controller 22 determines the degree of alignment of the substrate 6 with the shadow mask 16 by the program of the controller 22.

It can be seen that the controller 22 causes the orientation of the substrate 6, the shadow mask 16 or both to be adjusted to position the grid 28 of the substrate 6 and the grid 30 of the shadow mask 16 or both until each light path 36' has A predetermined amount of reflected light passes through the corresponding beam splitter 60 for reception by the corresponding light receiver 26. In other words, the controller finely positions the substrate 6, the shadow mask 16 or both until the light rays of the bars 42 of the respective grids 28 have a predetermined number of passes through the gaps 48 of the respective grids 30 and the beam splitter 60 to be correspondingly illuminated. Receiver 26 receives.

As shown in Fig. 8, in the mask alignment system 15', the light sources 24A to 24D are each located on the same side of the shadow mask 16 as the light receivers 26A to 26D. Each pair of light sources 24-photoreceptor 26 is optically combined using a beam splitter 60 (shown as a 45 degree facet) as a beam combiner.

Each of the light receptors 26 is positioned such that its optical axis is perpendicular to the shadow mask 16 and the substrate 6 and is located on the opposite side of the shadow mask 16 from the substrate 6. However, this should not be construed as limiting the invention.

In the configuration illustrated in Figure 8, light from the beam splitter 60 passes through the gap 48 of the shadow mask 16, and is at least partially reflected by the bar 42 of the substrate 6, while the remaining light from the beam splitter 60 is worn. Through the gap 44 of the substrate 6. The light reflected by the bar 42 of the substrate 6 passes through the gap 48 of the shadow mask 16 and then at least partially passes through the beam splitter 60 for reception by the light receptor 26.

Light source 24, including collimating optics/lens 40, is positioned transverse to, preferably perpendicular, to photoreceptor 26 comprising focusing optics/lens 50. Minute The beamer 60 is placed at the intersection of the optical axes of the light source 24 and the light receptor 26, and the plane of the beam splitter 60 is oriented to bisect the axis of the light source 24 and the light receptor 26 at right angles. In this manner, the collimated light from source 24 is reflected at 90 degrees, and then the reflected light propagates through the gap 48 of shadow mask 16 for the first time to strike the downward facing surface of bar 42 of substrate 6 grid 28 and at least These downward facing surfaces are partially reflected. The light reflected by the bar 42 of the grid 28 passes through the gap 48 of the shadow mask 16 for a second time and then partially passes through the beam splitter 60 for receipt by the PIN diode 52 of the photoreceptor 26. Therefore, the amount of light received by the PIN diode 52 of the photoreceptor 26 and the gap 48 of the grid 30 of the shadow mask 16 are proportional to the degree of overlap of the bars 42 of the grid 28 of the substrate 6. Therefore, the mask alignment 15' performs alignment sensing in the reflective mode. This is in contrast to the above-described mask alignment system 15 which performs alignment sensing in the shot mode.

Those skilled in the art should understand that some of the amount of light is lost because some of the light is used due to partial reflection and partial transmission of the beam splitter 60. It is not difficult to understand that the use of the collimating optics/lens 40 and the beam splitter 60 as a polarizing beam splitter can illustrate the inefficiency of the beam splitter 60.

In the above-described embodiment of the mask alignment system 15', each pair of light sources 24-photoreceptor 26 and each corresponding beam splitter 60 are located on the opposite side of the shadow mask 16 from the substrate 6. However, this should not be seen as limiting the invention, as it is contemplated that one, or more or all of the pair of light sources 24-photoreceptors 26, and each of the corresponding beam splitters 60, may be located in the substrate 6 and The opposite side of the shadow mask 16 is, that is, on the other side of the substrate 6. In this particular embodiment, light from each beam splitter 60 will first pass through the gap 44 of the substrate 6 to be reflected by the bar 46 of the shadow mask 16, and then the reflected light will again pass through the gap 44 of the substrate 6 for subsequent The beam splitter 60 is passed through to be received by the light receptor 26.

The invention has been described in terms of several exemplary embodiments. Obviously, you can think of modifications and changes after reading the above detailed description. It is intended that the present invention be construed as covering all such modifications and modifications as fall within the scope of the appended claims.

Claims (19)

A shadow mask-substrate alignment method comprising the steps of: (a) causing a collimated light source, a beam splitter, a substrate including a first grating, and a shadow mask including a second grating And a light receiver positioned relative to each other to define an optical path comprising collimated light output by the collimated light source and at least partially reflected by the beam splitter, the at least partially reflected collimated light being threaded through Passing through one of the first or second grids and being at least partially reflected by the other of the first or second grids back through the first or second grid And at least a portion of the reflected light that is reflected back through the one of the first or second gratings passes at least partially through the beam splitter for receipt by the light receptor; and (b Orienting the substrate, the shadow mask or both to adjust the first grid, the second grid, or both the first and second grids until the light receiver receives a a predetermined number, wherein: each grid comprises a plurality of bars in spaced relationship; each pair of spaced bars is separated by a gap And at least one of the first grid and the second grid includes at least one gap extending through the respective substrate and the shadow mask. The method of claim 1, wherein each bar has the same width as each gap. The method of claim 1, wherein: each of the grids includes a plurality of spaced apart bars and separates each pair of spaced apart strips a gap of the rod; and step (b) includes: adjusting an orientation of the substrate, the shadow mask, or both to position the long axes of the bars of the first grid to be parallel or substantially parallel to The long axes of the bars of the second grid, and the bars of the first and second grids are positioned to overlap the gaps of the second and the first grids, respectively . The method of claim 3, wherein the bars of the first and second grids each overlap 50% of the gaps of the second and the first grids. The method of claim 1, wherein the collimated light source comprises: an LED; and a collimating lens operable to collimate light output by the LED. The method of claim 1, wherein the light receptor comprises: a PIN diode; and a focusing lens operable to focus light received from the beam splitter onto the PIN diode. The method of claim 1, wherein a longitudinal axis of each of the bars extends radially at ±15 degrees from a central axis of the corresponding substrate or shadow mask. A shadow mask-substrate alignment method comprising the steps of: (a) providing a first substrate having a plurality of first gratings arranged in a pattern, wherein each of the first gratings comprises a plurality of spaced apart strips a rod, and a gap between each pair of spaced apart bars and through the first substrate; (b) providing a second substrate having the plurality of first gratings a plurality of sets of spaced apart reflective surfaces of the same pattern, wherein each set of spaced apart reflective surfaces includes a pair of spaced apart reflective surfaces; (c) defining a plurality of optical paths, wherein each optical path includes a light source at an opposite end of the optical path a light receptor, and a beam splitter between the light source and the light receiver in the optical path; (d) positioning a first grid in each of the light paths to be roughly thinned with a set of spaced reflective surfaces And (e) when light rays on each of the optical paths are reflected by the light and passed through the beam splitter, reflected by at least one of the spaced apart reflective surfaces in the optical path, and passed through the first The grid is finely positioned with the first substrate, the second substrate, or both when the grid is received by the light receptor of the optical path after at least one gap in the optical path. The method of claim 8 wherein: each set of spaced apart reflective surfaces is comprised of a second grid comprising a plurality of spaced apart bars and one of each pair of spaced apart bars a gap; each of the bars of the second grid defining one of the reflective surfaces; and each gap of the second grid defining a structure in the second substrate having a reflectivity less than each of the reflective surfaces. The method of claim 8, wherein: each of the photoreceivers outputs a signal having a bit associated with the amount of light received by the photoreceiver; and step (e) includes: finely locating the first a substrate, the second substrate or both, until a level of the signals output by the optical receivers The combination is equal to a predetermined value or falls within a predetermined range of values. The method of claim 10, wherein the predetermined value is zero. The method of claim 8, wherein: the first substrate and the second substrate each have a rectangular or square shape; the first substrate has a first grating adjacent to each corner; and the second substrate has an adjacent A set of corners separate the reflective surfaces. A shadow mask-substrate alignment method comprising the steps of: (a) providing a substrate having a plurality of first gratings arranged in a pattern; (b) providing a shadow mask having a plurality of a plurality of second grids of the same pattern as the first grid, wherein each grid includes a plurality of spaced apart bars and a gap between each pair of spaced apart bars, and the first grating and the At least one of the second grids includes at least one gap extending through the respective substrate and the shadow mask; (c) defining a plurality of optical paths, wherein each of the optical paths includes a light source, a light receiver, and a beam splitter (d) positioning a first grid in each of the optical paths to be roughly aligned with a second grid; and (e) illuminating the light source by the light source on each of the optical paths, by the optical path At least one gap reflected by the beam splitter through one of the first or second grids in the optical path, by the other of the first or second grids in the optical path Reflecting at least one of the rods and returning to the one of the first or second gratings in the optical path After a gap is less, and then passes through the beam splitter of the optical path to be received by the light receiver of the optical path, the substrate, the shadow mask or both are finely positioned until a predetermined amount of light is applied to each optical path. The light receiver of the optical path is received. The method of claim 13, wherein each bar has the same width as each gap. The method of claim 13, wherein the step (e) comprises: finely positioning the substrate, the shadow mask, or both until the bars of the first and second grids are respectively associated with the second The gaps of the first grid partially overlap. The method of claim 15, wherein the bars of the first and second grids each overlap 50% of the gaps of the second and first grids. The method of claim 13, wherein: each photoreceiver outputs a signal having a level associated with the amount of light received by the photoreceiver; and step (e) includes: finely locating the substrate The shadow mask or both until a quasi-combination of the signals output by the plurality of photoreceivers is equal to a predetermined value or falls within a predetermined range of values. The method of claim 17, wherein the predetermined value is zero. The method of claim 13, wherein: the substrate and the shadow mask each have a rectangular or square shape, and a grid is adjacent to the rectangle or each corner of the square; and a longitudinal axis of each bar and One of the corresponding substrate or shadow mask The central axis extends radially at ±15 degrees.