Calibration Of Layer Thickness And Ink Volume In Fabrication Of Encapsulation Layer For Light Emitting Device

• US 20170141353A1
• Filed: 01/26/2017
• Published: 05/18/2017
• Est. Priority Date: 12/12/2013
• Status: Active Grant

• Current Assignee: Kateeva, Inc.
• Original Assignee: Kateeva, Inc.
• Inventors: Harjee, Nahid, Vronsky, Eliyahu
• Granted Patent: US 9,755,186 B2
• Time in Patent Office: Days
• CPC Class Codes: B05C 11/10 Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material B05C1/0813, B05C5/0225, B05C17/002 and B05C19/06 take precedence
• CPC Class Codes: B41J 2/01 Ink jet
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements
• CPC Class Codes: B41J 2/2054 by the variation of dot disposition or characteristics, e.g. dot number density, dot shape
• CPC Class Codes: B41J 2/21 for multi-colour printing
• CPC Class Codes: B41J 3/407 for marking on special material
• CPC Class Codes: B41M 3/00 Printing processes to produce particular kinds of printed work, e.g. patterns printing apparatus or machines of special type or for particular purposes B41F17/00; special designs or pictures per se B44F; manufacturing printed circuits using printing techniques H05K3/12 ; manufacturing organic semiconductor devices using printing techniques H10K71/13
• CPC Class Codes: B41M 5/0047 by ink-jet printing
• CPC Class Codes: B41M 7/0081 using electromagnetic radiation or waves, e.g. ultraviolet radiation, electron beams
• CPC Class Codes: B41M 7/009 using thermal means, e.g. infrared radiation, heat
• CPC Class Codes: H01L 21/02288 printing, e.g. ink-jet printing per se B41J
• CPC Class Codes: H01L 21/67126 Apparatus for sealing, encapsulating, glassing, decapsulating or the like processes H01L23/02, H01L23/28
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 31/0203 Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/048 Encapsulation of modules
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H04N 1/405 : Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: H10K 50/84 : Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/844 : Encapsulations
• CPC Class Codes: H10K 50/8445 : multilayered coatings having a repetitive structure, e.g. having multiple organic-inorganic bilayers
• CPC Class Codes: H10K 59/1201 : Manufacture or treatment
• CPC Class Codes: H10K 59/8731 : multilayered coatings having a repetitive structure, e.g. having multiple organic-inorganic bilayers
• CPC Class Codes: H10K 71/00 : Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: H10K 71/135 : using ink-jet printing
• CPC Class Codes: H10K 71/70 : Testing, e.g. accelerated lifetime tests
• CPC Class Codes: Y02E 10/549 : Organic PV cells
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

An ink jet process is used to deposit a material layer to a desired thickness. Layout data is converted to per-cell grayscale values, each representing ink volume to be locally delivered. The grayscale values are used to generate a halftone pattern to deliver variable ink volume (and thickness) to the substrate. The halftoning provides for a relatively continuous layer (e.g., without unintended gaps or holes) while providing for variable volume and, thus, contributes to variable ink/material buildup to achieve desired thickness. The ink is jetted as liquid or aerosol that suspends material used to form the material layer, for example, an organic material used to form an encapsulation layer for a flat panel device. The deposited layer is then cured or otherwise finished to complete the process.

Claims

1. A method of fabricating a thin film encapsulation layer, the method comprising:

for a first substrate,

ejecting droplets of liquid onto the first substrate with an ink jet printer, thereby forming a first liquid coat having a first volume per unit area of the substrate, and

measuring a thickness of at least one of the first liquid coat or a film formed by curing the first liquid coat; and

for a second substrate,

ejecting droplets of the liquid onto the second substrate with the ink jet printer, thereby forming a second liquid coat having a second volume per unit area of the substrate dependent on the first volume per unit area and a relationship of the measured thickness to a target thickness, and

curing the second liquid coat to form the thin-film encapsulation layer,

wherein ejecting droplets onto the second substrate comprises controlling at least one of an area density of the droplets or a size of the droplets relative to at least one of droplet area density or size used to produce the first volume per unit area.

2. The method of claim 1, wherein:

the method further comprises receiving the first substrate into a gas enclosure;

ejecting the droplets onto the first substrate comprises printing the droplets onto the first substrate using the ink jet printer within the gas enclosure;

the method further comprises receiving the second substrate into a gas enclosure; and

ejecting the droplets onto the second substrate comprises printing the droplets onto the second substrate using the ink jet printer within the gas enclosure.

3. The method of claim 2, wherein the gas enclosure encloses at least one of nitrogen gas or a Noble gas, such that the droplets of the liquid deposited onto the first substrate and the droplets of liquid deposited onto the second substrate are each deposited within an atmosphere comprising the at least one, and wherein curing the second liquid coat is performed within a controlled atmosphere, the second substrate not being exposed to an un-controlled atmosphere in between ejecting the droplets to form the second liquid coat and said curing.

4. The method of claim 3, wherein ejecting the droplets onto the second substrate using the inkjet printer is performed for each substrate in a series of substrates, and wherein for each respective substrate in the series:

ejecting the droplets is performed according to a common printhead scan pattern and a common nozzle firing pattern;

the respective substrate comprises an active region, an exposed region and a buffer region between the active region and the exposed region, the active region to receive the thin film encapsulation layer at a uniform thickness corresponding to the desired thickness, the exposed region not to receive the thin film encapsulation layer, the buffer region to provide a transition between the active region and the exposed region; and

the buffer region is to receive the thin film encapsulation layer according to a third volume of the liquid deposited per unit area, relative to the active region.

5. The method of claim 4, wherein:

the third volume per unit area is selected according to a calibration process performed on a test substrate, the calibration process to measure deviation between a lip of a deposited layer and the uniform thickness; and

the third volume per unit area is selected so as to reduce the deviation.

6. The method of claim 5, wherein the test substrate is the first substrate.

7. The method of claim 6, wherein the liquid comprises a monomer and wherein curing the second liquid coat comprises exposing the second liquid coat to ultraviolet radiation to convert the monomer to a polymer.

8. The method of claim 1, embodied as a method of manufacturing an electronic device, the electronic device having light emitting elements, wherein the second substrate is received in a manner having the light emitting elements, and wherein the second liquid coat and the thin film encapsulation layer are to cover the light emitting elements.

9. A method of fabricating thin film encapsulation layers, the method comprising:

in a calibration process,

ejecting droplets of liquid onto a first substrate with an ink jet printer, thereby forming a first liquid coat having a first volume per unit area of the substrate, and

measuring a thickness of at least one of the first liquid coat or a film formed by curing the first liquid coat; and

in a production process, for each respective substrate in a series of second substrates, receiving the respective substrate,

ejecting droplets of the liquid onto the respective substrate with the ink jet printer, thereby forming a second liquid coat having a second volume per unit area of the substrate dependent on the first volume per unit area and a relationship of the measured thickness to a target thickness, and

curing the second liquid coat to form one of the thin film encapsulation layers on the respective substrate,

wherein ejecting droplets onto the second substrate comprises controlling at least one of an area density of the droplets or a size of the droplets relative to at least one of droplet area density or size used to produce the first volume per unit area.

10. The method of claim 9, wherein the liquid comprises a monomer and wherein curing the second liquid coat comprises exposing the second liquid coat to ultraviolet radiation to convert the monomer to a polymer.

11. The method of claim 9, embodied as a method of forming the thin film encapsulation layer in an electronic device having light emitting elements, and wherein:

the method further comprises receiving the first substrate into a gas enclosure, the first substrate having the light emitting elements formed on the first substrate, the first liquid coat to cover the light emitting elements;

ejecting the droplets onto the first substrate with the ink jet printer comprises printing within the gas enclosure;

receiving each respective substrate in the series further comprises receiving the respective substrate into the gas enclosure, the respective substrate also having the light emitting elements formed on the respective substrate, the second liquid coat to cover the light emitting elements; and

ejecting the droplets onto the respective substrate with the ink jet printer also comprises printing within the gas enclosure.

12. The method of claim 11, wherein the gas enclosure encloses at least one of nitrogen gas or a Noble gas, such that the droplets of the liquid are deposited onto the first substrate and each respective substrate within an atmosphere comprising the at least one, and wherein curing the second liquid coat is performed for each respective substrate in the series within a controlled atmosphere, each respective substrate in the series not being exposed to an uncontrolled atmosphere in between ejecting the droplets to form the second liquid coat and said curing on the respective substrate.

13. The method of claim 9, wherein

each respective substrate in the series comprises an active region, an exposed region and a buffer region between the active region and the exposed region, the active region to receive the thin film encapsulation layer at a substantially uniform thickness corresponding to the target thickness, the exposed region not to receive the thin film encapsulation layer, the buffer region to provide providing a transition between the active region and the exposed region;

and

for each respective substrate in the series, the buffer region is to receive the thin film encapsulation layer according to a third volume of the liquid deposited per unit area, relative to the active region.

14. The method of claim 13, wherein:

the third volume per unit area is selected according to a calibration process performed on a test substrate, the calibration process to measure deviation between a lip of a deposited layer and the uniform thickness; and

the third volume per unit area is selected so as to reduce the deviation.

15. The method of claim 14, wherein the test substrate is also one of the respective substrates in the series.

16. A method of fabricating a thin film encapsulation layer of electronic devices, each of the electronic devices having light emitting elements, the method comprising:

in a calibration process,

ejecting droplets of liquid onto a first substrate with an ink jet printer, thereby forming a first liquid coat having a first volume per unit area of the substrate, and

measuring a thickness of at least one of the first liquid coat or a film formed by curing the first liquid coat; and

in a production process, for each respective substrate in a series of second substrates, each of the second substrates having the light emitting elements,

receiving the respective substrate,

ejecting droplets of the liquid onto the respective substrate with the ink jet printer, thereby forming a second liquid coat so as to cover the light emitting elements of the respective substrate, the second liquid coat having a second volume per unit area of the substrate dependent on the first volume per unit area and a relationship of the measured thickness to a target thickness, and

curing the second liquid coat to form one of the thin film encapsulation layers on the respective substrate,

wherein the liquid comprises an organic material, wherein ejecting droplets onto the second substrate comprises controlling at least one of an area density of the droplets or a size of the droplets relative to at least one of droplet area density or size used to produce the first volume per unit area, and wherein curing the second liquid coat comprises polymerizing the organic material.

17. The method of claim 16, wherein:

the method further comprises receiving the first substrate into a gas enclosure;

ejecting the droplets onto the first substrate with the ink jet printer comprises printing within the gas enclosure;

receiving each respective substrate in the series further comprises receiving the respective substrate into the gas enclosure;

ejecting the droplets onto each respective substrate in the series with the ink jet printer also comprises printing within the gas enclosure; and

curing the second liquid coat is performed for each respective substrate in the series within a controlled atmosphere, each respective substrate in the series not being exposed to an uncontrolled atmosphere in between ejecting the droplets to form the second liquid coat and said curing on the respective substrate.

18. The method of claim 17, wherein the gas enclosure encloses at least one of nitrogen gas or a Noble gas, such that the droplets of the liquid are deposited onto the first substrate and each respective substrate within an atmosphere comprising the at least one, and wherein curing the second liquid coat is performed for each respective substrate in the series within a controlled atmosphere, each respective substrate in the series not being exposed to an uncontrolled atmosphere in between ejecting of the droplets to form the second liquid coat and said curing on the respective substrate.

19. The method of claim 18, wherein

each respective substrate in the series comprises an active region, an exposed region and a buffer region between the active region and the exposed region, the active region to receive the thin film encapsulation layer at a substantially uniform thickness corresponding to the target thickness, the exposed region not to receive the thin film encapsulation layer, the buffer region to provide providing a transition between the active region and the exposed region;

and

for each respective substrate in the series, the buffer region is to receive the thin film encapsulation layer according to a third volume of the liquid deposited per unit area, relative to the active region.

20. The method of claim 16, wherein each of the electronic devices comprises a pixelated organic light emitting diode (OLED) display device.