Inkjet printing and selective curing of color conversion materials

Abstract

Embodiments of the present disclosure generally relate to methods of depositing color conversion material into sub-pixel wells on a substrate. Depositing a first color conversion material into a first sub-pixel well formed over a substrate, each sub-pixel well defined by adjacent sub-pixel isolation structures, aligning an opening of a mask with the first sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask, projecting light through the opening of the mask to cure the first color conversion material within the second sub-pixel well, conducting a removal of uncured first color conversion material that removes uncured first color conversion material from one or more of the adjacent sub-pixel isolation structures. The substrate with sub-pixel wells is then bonded to a backplane.

Description

INKJET PRINTING AND SELECTIVE CURING OF COLOR CONVERSION MATERIALSBACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to display devices. More specifically, embodiments described herein relate to methods and apparatus for fabricating light-emitting diode (LED) pixels.Description of the Related Art

[0002] A light emitting diode (LED) panel uses an array of LEDs, with individual LEDs providing the individually controllable pixel elements. Such an LED panel can be used for a computer, touch panel device, personal digital assistant (PDA), cell phone, television monitor, and the like. An LED panel that uses micron-scale LEDs based on lll-V semiconductor technology (also called micro-LEDs) would have a variety of advantages as compared to organic light emitting diodes (OLEDs), e.g., higher energy efficiency, brightness, and lifetime, as well as fewer material layers in the display stack, which can simplify manufacturing. However, there are challenges to fabricating micro-LED panels.

[0003] Current techniques for depositing color conversion materials, such as quantum dots, into micro-LED wells generally result in low pixel density (e.g., <300 PPI) display devices having reduced image quality. Although recent techniques have enabled color conversion material to be implemented in micro-LED devices having higher pixel densities, such techniques generally result in high levels of material waste (>70%) and, as a result, increased production costs.

[0004] Therefore, there is a need for an improved method of depositing color conversion materials into micro-LED panels.SUMMARY

[0005] In one embodiment, a method is provided. The method includes depositing a first color conversion material into a sub-pixel well formed over a substrate, the substrate having at least first sub-pixel well, a second sub-pixel well and a third sub-pixel, aligning an opening of a mask with the first sub-pixel well such that a top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask, projecting a light source through the opening of the mask to cure the first color conversion material within the first sub-pixel well, conducting a removal of uncured first color conversion material that removes uncured first color conversion material from one or more of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well while sparing first color conversion material from the first sub-pixel well.

[0006] In another embodiment, a method is proved. The method includes depositing a first color conversion material into the first sub-pixel well formed over a substrate, the substrate having at least a first sub-pixel well, a second sub-pixel well, and a third sub-pixel well, each sub-pixel well defined by adjacent sub-pixel isolation structures, aligning the opening of the mask with the first sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask, projecting light through the opening of the mask to cure the first color conversion material within the second sub-pixel well, removing any uncured second color conversion material from the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well, wherein the removing comprises a wash process followed by a dry process. The method further includes repeating each step in at least the second sub-pixel well, and the third sub-pixel well.

[0007] In another embodiment, a method is proved. The method includes depositing a first color conversion material into the first sub-pixel well formed over a substrate, the substrate having at least a first sub-pixel well, a second sub-pixel well, and a third sub-pixel well, each sub-pixel well defined by adjacent sub-pixel isolation structures, aligning the opening of the mask with the first sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask, projecting light through the opening of the mask to cure the first color conversion material within the second sub-pixel well, and bonding the substrate with abackplane having a plurality of LEDs, wherein each well is aligned with a respective LED.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1A and 1 B are cross-sectional views of a pixel according to embodiments.

[0010] Figure 2 is a flow diagram of a method of fabricating sub-pixels included in a pixel according to embodiments.

[0011] Figures 3A-3F are schematic, cross-sectional views of a substrate during the fabrication of sub-pixels included in a pixel according to embodiments.DETAILED DESCRIPTION

[0012] Embodiments of the present disclosure generally relate to techniques for filling micro-LEDs with one or more color conversion materials, such as quantum dots. In a micro-LED display device, light emitted by individual micro-LEDs is converted to different colors via one or more color conversion materials. Color conversion materials are often deposited by dispersing liquids into wells over a substrate. Each well is made up of isolation structures and a substrate. The substrate may be a backplane. To prevent mixing of the color conversion materials, each color is printed separately.

[0013] When color conversion materials, such as quantum dots, are inkjet printed into the wells, a higher degree of deposition accuracy can be achieved. However, inkjet printing has the drawback of having limited resolution, with a maximum pixel density of about 300 pixels per inch (PPI). Additionally, with respectto inkjet printing, the scrap rate is highly dependent on the print accuracy. Since the accuracy of inkjet printing is below 100%, the scrap rate generally increases as the screen resolution increases.

[0014] Another method of depositing conversion material on a substrate includes spin coating the color conversion material followed by photolithography. Notably, however, the spin coating process may result in over 70% of the color conversion material being wasted, due to the removal of excess color conversion material via development during the photolithography process. Accordingly, the techniques for filling micro-LEDs described herein reduce the amount of wasted material, decreasing costs and resulting in higher pixel density display devices.

[0015] Figure 1 A cross-sectional view of a pixel 100. Figure 1 B cross-sectional view of a pixel 400 having mask based cured color conversion material 114 on a substrate 401 bonded to a backplane 102.

[0016] The pixel 100 includes at least three micro-LEDs 104 disposed on a backplane 102. The pixel 100 includes at least three micro-LEDs 104 disposed on a backplane 102.

[0017] The micro-LEDs 104 are integrated with backplane circuitry so that each micro-LED 104 can be individually addressed. For example, the circuity of the backplane can include a TFT active matrix array with a thin-film transistor and a storage capacitor (not illustrated) for each micro-LED 104, column address and row address lines, column and row drivers, to drive the micro-LEDs 104. Alternatively, the micro-LEDs 104 can be driven by a passive matrix in the backplane circuitry. The backplane 102 can be fabricated using conventional complementary metal- oxide silicon (CMOS) process. The micro-LEDS 104 are connected to the backplane 102 via backplane electrodes 106 and micro-LED electrodes 108. At the interface of the electrodes 106, 108, is an alloy 107 of the two electrode materials. Each micro-LED 104 configured to emit UV light in a first wavelength range. The UV light may be white light. The micro-LEDs 104 may be LEDs.

[0018] Sub-pixel isolation structures 110 are disposed over, and in some embodiments on the backplane 102. The adjacent sub-pixel isolation structures 110 define the respective well 206 of at least three sub-pixels 112. A micro-LEDs104 is disposed in each well 113 between the adjacent sub-pixel isolation structures 110. Each well 113 has a width from about 0.5 um to about 40 um, such as about 2 um to about 30 um. The sub-pixel isolation structures 110 have a width from about 0.1 um to about 15 um such as 1 um to 10 um. The sub-pixel isolation structures 110 may include organic material, such as epoxy-based photoresist or a negative tone photoresist. The photoresist material is a negative photoresist. The exposed surfaces of the sub-pixel isolation structures 110 may have a reflection material disposed thereon. The reflection material on the exposed surfaces provide for reflection of the emitted light to contain the converted light to the respective subpixel in order to prevent color cross-talk. The reflection material includes, but is not limited to, gold platinum, titanium, aluminum, silver, combinations thereof, or the like.

[0019] The sub-pixels 112 include a red sub-pixel 112a with a red color conversion material 114a disposed in the well 113 of the red sub-pixel 112a, a green sub-pixel 112b with a green color conversion material 114b disposed in the well 113 of the green sub-pixel 112b, and a blue sub-pixel 112c with a blue color conversion material 114c disposed in the well 113 of the blue sub-pixel 112c. When a microLED 104a of the red sub-pixel 112a is turned on the red color conversion material 114a will convert the light emitted from micro-LED 104a into red light. When a micro-LED 104b of the green sub-pixel 112b is turned on the green color conversion material 114b will convert the light emitted from micro-LED 104b into green light. When a micro-LED 104c of the blue sub-pixel 112c is turned on the blue color conversion material 114c will convert the light emitted from micro-LED 104c into blue light. In one embodiment, the pixel 100 includes a fourth sub-pixel 112d. As shown in Figure 1 , the fourth sub-pixel 112d does not include a color conversion material, i.e., color-conversion-layer-free. In some embodiments, the fourth subpixel 112d may be later filled with a color conversion material 114 (e.g., a red, green, blue, violet, etc. color conversion material). In another embodiment, the fourth subpixel 112d includes a sacrificial material (not shown). In other embodiments, the at least three sub-pixels 112 include the same color conversion material. The fourth sub-pixel 112d may be later filled with a color conversion material 114.

[0020] In some embodiments, the color conversion material 114 may include quantum dots (QDs). The quantum dots may be sized to produce wavelengths corresponding to different colors. In one embodiment, the red color conversion material 114a may include quantum dots approximately 6 nm in size. The green color conversion material 114b may include quantum dots approximately 4 nm in size. The blue color conversion material 114c may include quantum dots approximately 2 nm in size. In other embodiments, the color conversion material 114 may include nanostructures, photoluminescent materials, or organic substances.

[0021] An encapsulation layer 122 is disposed over, and in some embodiments directly on, a top surface of the sub-pixel isolation structures 110 and the sub-pixels 112. The encapsulation layer 122 prevents reactions between the color conversion material 114 and other materials in an ambient environment. The encapsulation layer 122 has a thickness from 10 nm or less and is one of a metal layer, a metal oxide layer, or a silicon containing layer. The encapsulation layer includes, but is not limited to, aluminum oxide, titanium oxide, silicon nitride, tantalum (Ta) hafnium (Hf), tantalum oxide, hafnium oxide, titanium (Ti), aluminum (Al), chromium (Cr), copper (Cu), tungsten (W), zirconium (Zr), or a combination thereof. The encapsulation layer 122 may be deposited using a physical vapor deposition (PVD) process, chemical vapor deposition (CVD), or atomic layer deposition (ALD). The PVD process may include pulsed laser deposition (PLD), thermal evaporation, or electron beam evaporation PVD (EBPVD).

[0022] In some embodiments, the pixel 100 includes micro-lenses 128 disposed on the encapsulation layer 122 and over each of the wells 206 of the sub-pixels 112. In some embodiments, a passivation layer 126 is disposed on the micro-lenses 128. In other embodiments, the micro-lenses 128 may be made of a resist material such as photoresist material that blocks UV light.

[0023] The sub-pixel 112 has a length and a width. The length is about 35 urn or less. The width is about 35um or less. The length and the width of each subpixel result the pixel 100 having a PPI of 320 or less. The surface area results in a display (such as a smartphone, wearable electronics, laptop, and ARA / R display) of pixels 100 having greater than 300 pixel per inch (PPI). To fabricate a display having aPPI greater than 300 it may be necessary to remove uncured color conversion material 114 from adjacent sub-pixels 112 and from sub-pixel isolation structures 110. For example, residual, uncured color conversion material 114 may occur as overflow 212 in adjacent wells or buildup 214 on the sub-pixel isolation structures 110. Overflow 212 or buildup 214 decreases print accuracy which can limit PPI capabilities, increase cost, and increase time needed to create the display having a PPI greater than 300. The method 200 of forming the pixel 100 described herein provides for inkjet printing and photolithography processes that to pattern the color conversion material 114 and utilize wash and dry processes to remove uncured color conversion material 114 from adjacent sub-pixels 112 and from sub-pixel isolation structures 110.

[0024] Figure 1 B is a cross-sectional view of a pixel 400 having mask based cured color conversion material on a substrate 401 bonded to a backplane 102. The pixel 400 includes at least three micro-LEDs 104 disposed on a backplane 102 with a backplane surface 102a. The backplane surface 102a includes pairs of backplane electrodes 106 disposed thereon. Micro-LEDs 104 include pairs of micro-LED electrodes 108 coupled to the pairs of backplane electrodes 106 disposed on the backplane 102. The micro-LEDs 104 may be PSS micro-LEDs or planar micro- LEDs. The PSS micro-LEDs and planar micro-LEDs are interchangeable. An ultraviolet (UV) blocking material 405 is disposed on the backplane 102, between the pairs of backplane electrodes 106, between the pairs of micro-LED electrodes 108, and between the micro-LEDs 104. The UV blocking material 405 surrounds the micro-LEDs 104, the micro-LED electrodes 108, and the backplane electrodes 106. The UV blocking material 405 provides support for the backplane 102 and the connection between the micro-LEDs 104 and backplane 102. The optical density of the UV blocking material 405 provides for color isolation between each of the micro-LEDs 104 because the UV blocking material 405 blocks UV light. The UV blocking material 405 includes thermal curable glue, UV curable glue, black matrix epoxy, metal particles, UV absorbing materials, or combinations thereof.

[0025] Pixel 400 further includes a substrate 401 . Substrate 401 includes wells 206 defined by sub-pixel isolation structures 110. Cured color conversion material 114 is disposed in the wells 206, which are disposed on the substrate 401. Thesubstrate 401 is coupled to the backplane 102 seen in Figure 1 B. To form the arrangement seen in Pixel 400, the substrate 401 aligns with the backplane 102 where the color conversion material 114 in their respective wells 206 aligns with the micro-LEDs 104. In some embodiments, a transparent UV material (not pictured) is disposed over the micro-LEDS. The transparent UV material includes an adhesive material. The adhesive material includes, but is not limited to, an epoxy, an acrylic material, and combinations thereof. The acrylic material may be UV transparent material.

[0026] Figure 2 is a flow diagram of a method 200 of fabricating sub-pixels included in a pixel 100 according to embodiments. Figures 3A-3F are schematic, cross-sectional views of the substrate 401 of Figure 1 during the method 200 according to embodiments.

[0027] In some embodiments, method 200 may be performed in an inert atmosphere. In some embodiments, method 200 is operable in an environment containing argon (Ar), nitrogen (N2), or a combination of Ar and N2.

[0028] Figure 3A is a schematic, cross-sectional view of a substrate 401 prior to operation 210. As shown in Figure 3A, the substrate 401 includes sub-pixel isolation structures 110, which form wells 206. In Figure 3A, color conversion material 114 has not yet been deposited into the wells 206.

[0029] At operation 210, color conversion material 114 is deposited into a well 206. For example, as shown in Figure 3B, red color conversion material 114a is deposited into well 206b. It is contemplated that any color conversion material 114 may be deposited in the first instance of operation 210. However, in some embodiments, red color conversion material 114a may be deposited first, green color conversion material 114b second, and blue color conversion material 114c third to account for the relative stabilities of the associated compounds. However, it is contemplated that, in subsequent instances of operation 210, any color may be printed. In one or more embodiments, the color conversion material 114 is deposited via inkjet printing. In some embodiments, color conversion material 114, for example red color conversion material 114a may be ink jet printed into multiple wells 206 concurrently. The total amount of desired red color conversion material114a is printed into the desired amount of wells 206 before continuing to the next operation 220. In other embodiments, color conversion material 114, for example red color conversion material 114a, may be ink jet printed into the same well 206 multiple times in order to achieve a high print yield. A high print yield is about 300 PPI to about 5000 PPI.

[0030] During operation 210, some overspill or misjetting may occur, resulting in overflow 212 into wells 206a and 206c and buildup 214 on the sub-pixel isolation structures 110. In some embodiments, more or less overflow 212 and buildup 214 may occur. In some embodiments, the overflow 212 may also be misjetted into adjacent wells 206. The overflow 212 may occur in an empty well, for example well 206a or 206b shown in Figure 3B. In other examples, not shown, the overflow 212 may occur on a well 206 where color conversion material 114 has been previously deposited and cured in a previous operation cycle. In some embodiments, there may be little to no overflow 212 or buildup 214. Overflow 212 or buildup 214 may occur while disposing any color conversion material 114 (e.g., a red, green, blue, violet, etc. color conversion material).

[0031] At operation 220, a mask 320 is aligned with the substrate 401. The mask 320 includes one or more openings 322 having widths 324. In Figure 3C, the opening 322 is positioned above well 206b. The mask 320 is positioned a height 326 above the sub-pixel isolation structures 110. The pixel well 206b has a width 310, and the sub-pixel isolation structures 110 have a height 312. In an embodiment, the mask 320 has a width less than the width of the well 206 on substrate 401 . This creates an angle 9 for a portion 330 of light 328 to pass through the mask 320 and cure only the color conversion material 114 in the desired well 206.

[0032] In some embodiments, the opening 322 may be circular or rectangular. In some embodiments, the opening 322 may be any regular or irregular shape. In some embodiments, the shape of the opening 322 may depend on the shape of the well 206, the size of the well 206, or any other factor.

[0033] At operation 230, light 328 is directed at the mask 320. In some embodiments, the light 328 may be ultraviolet (UV) light. As shown, a portion 330of the light 328 passes through the mask 320 opening 322, and the rest of the light 328 is blocked by the mask 320. The portion 330 of the light 328 cures the red color conversion material 114a. Since the rest of the light 328 is blocked by the mask 320, the overflow 212 and buildup 214 are not cured. In some embodiments, operation 230 may be performed for a set period of time or until the color conversion material 114 is cured.

[0034] Figure 3D is an enlarged view of section A1 of Figure 3C. In some embodiments, the height 326 of the mask 320 may be adjusted to make the angle 9 closer to 90° to reduce splash 332 onto the sub-pixel isolation structures 110. Splash 332 may cause all or a portion of the overflow 212 and buildup 214 to be cured, which would cause defects in the display. The height 326 may range from 0 to 500 pm, such as 2 to 50 pm, such as 5 to 10 pm. In some embodiments, the height 326 may be greater than zero to avoid damage to the pixel 100 in the event that the pixel 100 or the mask 320 is tilted, in the event that there is variability in the sub-pixel isolation structure 110 heights 312, or in the event that the substrate 401 is not 100% planar.

[0035] In some embodiments, the width 324 of the opening 322 is adjusted based on the height 326 of the mask 320 and the width 310 of the well 206b to reduce the splash 332 onto the sub-pixel isolation structures 110. In some embodiments, the width 324 of the opening 322 is the same as the width 310 of the well 206b. In some embodiments, the width 324 of the opening 322 is smaller than the width 310 of the well 106b. In some embodiments, the width 324 of the opening 322 may range from 0.5 times to 2 times the size of the width 310 of the well 206b. In some embodiments in which the width 324 of the opening 322 is larger than the width 310 of the well 106b, the mask 320 may include a lens to focus the light 328.

[0036] In some embodiments, the opening 322 in the mask 320 may include a metalens to achieve a focusing or defocusing effect. In some embodiments, the metalens may be a Fresnel lens.

[0037] After the completion of operation 230, the mask may be removed.

[0038] At operation 240, removal of the uncured color conversion material 114 is conducted. For example, during operation 240, the overflow 212 and buildup 214may be removed, since the overflow 212 and buildup 214 were not cured during operation 230. The overflow 212 may be removed when the overflow 212 occurs occur in an adjacent empty well 206. At operation 240, the uncured color conversion material 114 that remains uncured can be removed from an adjacent well 206 that contains color conversion material 114 that has been cured in a previous operation. Color conversion material 114 in a sub-pixel well that has been previously cured remains in the sub-pixel well. Figure 3E shows the pixel 100 after the completion of operation 240.

[0039] In some embodiments, operation 240 is performed via a wash and dry process. In some embodiments, the wash and dry process utilizes a monomer solvent for the wash step and isopropyl alcohol (IPA) for the dry step. In some embodiments, the monomer solvent may include diethylacrylamide (DEAA) or 1 ,6- hexanediol diacrylate (HDDA).

[0040] At operation 250, method 200 is repeated until the color conversion material 114 is deposited for all of the red, green, blue, etc. sub-pixels. After the color conversion material is deposited for all of the sub-pixels, the pixel 100 may undergo further processing. As seen in Figure 3F, color conversion material 114 has been disposed in the wells 206 and cured.

[0041] At an optional operation 260, as shown in Figure 1 B, to form a pixel 400, the substrate 401 is disposed above the backplane 102. The substrate 401 is positioned such that the sub-pixel isolation structures 110 and micro-LEDs 104 are aligned. The substrate 401 includes the wells 206 and the cured color conversion material 114 disposed therein. As shown in Figure 1 B, after the sub-pixel isolation structures 110 and the micro-LEDs 104 are aligned, a transparent UV material (not pictured) is disposed on top of the backplane 102. The transparent UV material is used to bond the backplane 102 and the substrate 401 .

[0042] Accordingly, the embodiments described herein overcome the low print accuracy of quantum dot ink jet printing, allowing for 300 to 5,000 PPI (or higher) displays to be fabricated. Additionally, this disclosure decreases color conversion material waste by up to 70% compared to spin coating processes.

[0043] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:1 . A method, comprising: depositing a first color conversion material into a first sub-pixel well formed over a substrate, the substrate having at least the first sub-pixel well, a second subpixel well, and a third sub-pixel well, each sub-pixel well defined by adjacent subpixel isolation structures; aligning an opening of a mask with the first sub-pixel well such that a top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the first color conversion material within the first sub-pixel well; and conducting a removal of uncured first color conversion material that removes uncured first color conversion material from one or more of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well while sparing first color conversion material from the first sub-pixel well.

2. The method of claim 1 , further comprising: depositing a second color conversion material into the second sub-pixel well; aligning the opening of the mask with the second sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the second sub-pixel well, the first sub-pixel well, and the third sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the second color conversion material within the second sub-pixel well; and conducting a removal of uncured first color conversion material that removes uncured second color conversion material from one or more of the adjacent subpixel isolation structures of the second sub-pixel well, the first sub-pixel well, and the third sub-pixel well while sparing second color conversion material from the second sub-pixel well.

3. The method of claim 2, further comprising: depositing a third color conversion material into the third sub-pixel well;aligning the opening of the mask with the third sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the second sub-pixel well, the first sub-pixel well, and the second sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the third color conversion material within the second sub-pixel well; and conducting a removal of uncured third color conversion material that removes uncured third color conversion material from one or more from the adjacent sub-pixel isolation structures of the second sub-pixel well, the first subpixel well, and the third sub-pixel well while sparing third color conversion material from the third sub-pixel well.

4. The method of claim 3, further comprising bonding the substrate with a backplane having a plurality of micro-LEDs, wherein each well is aligned with a respective micro-LED.

5. The method of claim 1 , wherein the depositing comprises ink jet printing.

6. The method of claim 1 , wherein the removing comprises a wash process followed by a dry process.

7. The method of claim 6, wherein the drying process comprises applying an isopropyl alcohol to the substrate.

8. The method of claim 6, wherein the wash process comprises applying a monomer solvent to the substrate.

9. The method of claim 8, wherein the monomer solvent comprises one or more of diethylacrylamide (DEAA) or 1 ,6-hexanediol diacrylate (HDDA).

10. The method of claim 1 , wherein a width of the sub-pixel well is greater than the opening.

11. The method of claim 1 , wherein the mask is disposed a height above the sub-pixel well while directing the light at the mask, wherein the height is between 0 pm and 500 pm.

12. The method of claim 11 , wherein the height is between 5 pm and 10 pm.

13. A method of depositing color conversion material comprising: depositing a first color conversion material into a first sub-pixel well formed over a substrate, the substrate having at least the first sub-pixel well, a second subpixel well, and a third sub-pixel well, each sub-pixel well defined by adjacent subpixel isolation structures; aligning an opening of a mask with the first sub-pixel well such that a top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the first color conversion material within the second sub-pixel well; conducting a removal of uncured first color conversion material that removes uncured first color conversion material from one or more of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well while sparing first color conversion material from the first sub-pixel well; depositing a second color conversion material into the second sub-pixel well; aligning the opening of the mask with the second sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the second sub-pixel well, the first sub-pixel well, and the third sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the second color conversion material within the second sub-pixel well; conducting a removal of uncured first color conversion material that removes uncured second color conversion material from one or more of the adjacent subpixel isolation structures of the second sub-pixel well, the first sub-pixel well, and the third sub-pixel well while sparing second color conversion material from the second sub-pixel well; depositing a third color conversion material into the third sub-pixel well;aligning the opening of the mask with the third sub-pixel well such that the top surface of the adjacent sub-pixel isolation structures of the third sub-pixel well, the first sub-pixel well, and the second sub-pixel well are covered by the mask; projecting light through the opening of the mask to cure the third color conversion material within the second sub-pixel well; and conducting a removal of uncured third color conversion material that removes uncured third color conversion material from one or more from the adjacent sub-pixel isolation structures of the second sub-pixel well, the first subpixel well, and the third sub-pixel well while sparing third color conversion material from the third sub-pixel well.

14. The method of claim 13, wherein the first color conversion material comprises red quantum dots, the second color conversion material comprises green quantum dots, and the third color conversion material comprises blue quantum dots.

15. The method of claim 13, wherein the mask is disposed a height above the sub-pixel well, wherein the height is configured such that UV light does not touch a top surface of the sub-pixel isolation structures.

16. The method of claim 13, wherein the mask is disposed a height above the sub-pixel well, wherein the height is between 0 pm and 500 pm.

17. The method of claim 16, wherein the height is between 5 pm and 10 pm.

18. A method of depositing color conversion material comprising: depositing a first color conversion material into a first sub-pixel well formed over a substrate, the substrate having at least the first sub-pixel well, a second subpixel well, and a third sub-pixel well, each sub-pixel well defined by adjacent subpixel isolation structures; aligning an opening of a mask with the first sub-pixel well such that a top surface of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well are covered by the mask;projecting light through the opening of the mask to cure the first color conversion material within the second sub-pixel well; conducting a removal of uncured first color conversion material that removes uncured first color conversion material from one or more of the adjacent sub-pixel isolation structures of the first sub-pixel well, the second sub-pixel well, and the third sub-pixel well while sparing first color conversion material from the first sub-pixel well; and bonding the substrate with a backplane having a plurality of LEDs, wherein each well is aligned with a respective LED.

19. The method of claim 18, wherein the first color conversion material comprises red quantum dots, a second color conversion material comprises green quantum dots, and a third color conversion material comprises blue quantum dots.

20. The method of claim 18, wherein the substrate is bonded to the backplane by UV transparent material.

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