Printing Semiconductor Elements by Shear-Assisted Elastomeric Stamp Transfer

• US 20100123268A1
• Filed: 11/19/2009
• Published: 05/20/2010
• Est. Priority Date: 11/19/2008
• Status: Active Grant

• Current Assignee: X Display Company Technology Limited (Sensinnovat BVBA)
• Original Assignee: Semprius, Inc.
• Inventors: MENARD, Etienne
• Granted Patent: US 8,506,867 B2
• Time in Patent Office: Days
• US Class Current: 264/293
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68354 used to support diced chips prior to mounting
• CPC Class Codes: H01L 2224/75303 of the pressing surface
• CPC Class Codes: H01L 2224/75305 comprising protrusions
• CPC Class Codes: H01L 2224/75315 Elastomer inlay
• CPC Class Codes: H01L 2224/7598 specially adapted for batch processes
• CPC Class Codes: H01L 2224/83192 wherein the layer connectors are disposed only on another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/838 Bonding techniques
• CPC Class Codes: H01L 24/75 Apparatus for connecting with bump connectors or layer connectors
• CPC Class Codes: H01L 24/83 using a layer connector
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01011 Sodium [Na]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/01015 Phosphorus [P]
• CPC Class Codes: H01L 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01031 : Gallium [Ga]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/10336 : Aluminium gallium arsenide [AlGaAs]
• CPC Class Codes: H01L 2924/10349 : Aluminium gallium indium phosphide [AlGaInP]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15788 : Glasses, e.g. amorphous oxides, nitrides or fluorides

Abstract

Provided are methods and devices for transfer printing of semiconductor elements to a receiving surface. In an aspect, the printing is by conformal contact between an elastomeric stamp inked with the semiconductor elements and a receiving surface, and during stamp removal, a shear offset is applied between the stamp and the receiving surface. The shear-offset printing process achieves high printing transfer yields with good placement accuracy. Process parameter selection during transfer printing, including time varying stamp-backing pressure application and vertical displacement, yields substantially constant delamination rates with attendant transfer printing improvement.

Claims

1. A method of printing a transferable semiconductor element, said method comprising:

a. providing an elastomeric stamp having a transfer surface with said semiconductor element supported thereon, wherein said transfer surface comprises a three-dimensional pattern of relief features that at least partially contacts said semiconductor element;

b. providing a substrate having a receiving surface;

c. establishing conformal contact between said elastomeric stamp and said receiving surface, thereby contacting at least a portion of said semiconductor element with said receiving surface;

d. offsetting said elastomeric stamp a horizontal distance relative to said receiving surface, thereby generating a mechanical deformation in at least a portion of said pattern of relief features without separating said semiconductor element from said transfer surface or said receiving surface; and

e. separating said stamp from said receiving surface, thereby printing said semiconductor element to said receiving surface.

2. The method of claim 1, wherein said conformal contact step is established by applying air pressure to a top surface of said elastomeric stamp.

3. The method of claim 1, wherein said offsetting step comprises applying an in plane displacement to said elastomeric stamp.

4. The method of claim 3, wherein said in plane displacement comprises a horizontal displacement of said top surface relative to said receiving surface that is greater than 5 μ

m and less than 100 μ

m.

5. The method of claim 2, wherein said separating step comprises decreasing said air pressure applied to said stamp top surface.

6. The method of claim 1, wherein said elastomeric stamp further comprises:

a. an elastomeric layer having a top surface that is opposite said transfer surface; and

b. a rigid backing layer having a bottom surface, wherein said bottom surface is positioned adjacent to said elastomeric layer top surface.

7. The method of claim 6, wherein said elastomeric stamp further comprises a reinforcement layer operably connected to said rigid backing layer, said reinforcement layer having an opening that vertically coincides with at least a portion of said relief features on said transfer surface.

8. The method of claim 1, further comprising mounting said elastomeric stamp to a dry transfer printing tool, wherein said offsetting step comprises applying an in plane displacement to said dry transfer printing tool, thereby generating a mechanical deformation of at least a portion of said relief features.

9. The method of claim 8, further comprising applying a pressure to a top surface of said mounted stamp, thereby establishing conformal contact between said stamp and said receiving surface.

10. The method of claim 8, wherein said stamp is separated from said receiving surface by moving said transfer printing tool mounted to said elastomeric stamp in a vertical direction relative to said receiving surface.

11. The method of claim 10, wherein said pressure varies during said vertical direction movement that separates said stamp from said receiving surface.

12. The method of claim 11, wherein said pressure decreases from a maximum value to a minimum value, wherein said maximum value is between 4 kPa and 10 kPa and said minimum value is between 0 kPa and 2 kPa.

13. The method of claim 12, wherein said pressure decrease rate and said vertical direction movement rate are selected to provide a delamination rate of said relief features from said receiving surface that is substantially constant.

14. The method of claim 1, wherein said relief features comprise a plurality of posts.

15. The method of claim 14 wherein said plurality of posts has a contacting area fraction on said transfer surface selected from a range that is greater than 1% and less than 25%.

16. The method of claim 15, wherein said relief features further comprise:

a. a plurality of stabilization features interspersed between said posts, wherein said stabilization features have a contacting area that is less than the contacting area of said posts.

17. The method of claim 1, wherein said semiconductor printing provides a transfer printing yield and said yield is:

a. greater than or equal to 99.5% for a receiving surface that is coated with a thin layer of adhesive;

or

b. greater than or equal to 99.5% for stamp delamination rates that are greater than or equal to 1 mm/s.

18. The method of claim 1 further comprising:

a. optically aligning said stamp with said receiving surface;

b. positioning said semiconductor elements to within less than or equal to 100 μ

m vertical separation distance from said receiving surface; and

c. applying a pressure to a top surface of said stamp, thereby establishing conformal contact between said stamp and said receiving surface.

19. The method of claim 18, wherein said pressure is applied by application of a uniform air pressure to said stamp top surface.

20. The method of claim 1, wherein said pattern of relief features support a plurality of semiconductor elements.

21. The method of claim 1, wherein said receiving surface is a low-tack surface.

22. The method of claim 1, wherein said separating step comprises displacing said stamp relative to said receiving surface by applying a vertical offset to said stamp or to said receiving surface.

23. The method of claim 1, wherein said offsetting step is provided by:

a. applying an in-plane displacement to said stamp;

or

b. applying an in-plane displacement to said receiving surface.

24. The method of claim 1 further comprising:

a. applying an air pressure to at least partially establish said conformal contact; and

b. vertically separating said stamp from said receiving surface;

wherein said air pressure varies over a first time interval and said vertical separation is maintained constant over said first time interval; and

said air pressure is maintained constant over a second time interval that does not overlap said first time interval, and said vertical separation increases during said second time interval, thereby maintaining a delamination rate that deviates less than or equal to 5% from an average delamination rate over said first and second time intervals.

25. A device for dry transfer printing of semiconductors to a receiving substrate, said device comprising:

a reinforced composite stamp comprising;

a deformable layer having an internal surface and an external surface positioned opposite said internal surface, said external surface of said deformable layer having a plurality of relief features;

a rigid support layer connected to said internal surface of said deformable layer, wherein said rigid support layer has a bottom surface and a top surface positioned opposite said bottom surface, wherein said bottom surface is positioned proximate to said internal surface of said deformable layer; and

a reinforcement layer operably connected to said rigid support layer, said reinforcement layer having an opening that vertically coincides with at least a portion of said relief features of said external surface of said deformable layer;

a mounting flange having a top surface;

a vertical section that operably connects said mounting flange to said deformable layer external surface;

a transfer printing tool head comprising a receiving surface that is connected to said mounting flange top surface; and

an actuator operably connected to said mounting flange or said transfer printing tool head for generating a horizontal displacement between said deformable layer internal surface and said receiving surface.

26. The device of claim 25, wherein said actuator comprises:

a stepper motor, a micropositioner, a pressure generator, or piezoelectric actuator.

27. The device of claim 25, wherein said plurality of relief features comprises a plurality of posts distributed on said external surface.

28. The device of claim 27, further comprising a plurality of stabilization features distributed on said external surface, wherein the height of said stabilization features is less than the height of said posts.

29. The device of claim 28, wherein said stabilization features comprise a first population and a second population, wherein said each population has a geometric footprint and said first population geometric footprint is larger than said second population geometric footprint.

30. The device of claim 25, further comprising:

a. a variable pressure regulator operably connected to said rigid support layer of said composite stamp for controllably applying a positive pressure to a top surface of said rigid support layer.

31. The device of claim 30, wherein said pressure to a top surface is substantially uniform over said top surface of said rigid support layer.

32. The device of claim 31, wherein said pressure varies with time.

33. A method of printing a transferable semiconductor element, said method comprising:

a. providing a reinforced composite elastomeric stamp, said stamp having

i. an elastomeric layer having a top surface and a bottom surface;

ii. a transfer surface on said elastomeric layer bottom surface, wherein said semiconductor element is supported by said transfer surface and said transfer surface comprises a three-dimensional pattern of relief features that at least partially contacts said semiconductor element;

iii. a rigid backing layer having a bottom surface positioned adjacent to said elastomeric layer top surface;

iv. a reinforcement layer operably connected to said rigid backing layer, said reinforcement layer having an opening that vertically coincides with at least a portion of said relief features;

b. providing a substrate having a receiving surface;

c. positioning said transfer surface to within about 200 μ

m or less of said receiving surface;

d. aligning said stamp to said receiving surface;

e. establishing conformal contact between said elastomeric stamp and said receiving surface, thereby contacting at least a portion of said semiconductor element with said receiving surface by applying a uniform air pressure to said rigid backing layer;

f. offsetting said elastomeric stamp a horizontal distance relative to said receiving surface, thereby generating an in-plane shear force in said stamp;

g. decreasing said air pressure applied to said rigid backing layer; and

h. separating said stamp from said receiving surface by moving said stamp in a vertical direction relative to said substrate, thereby printing said semiconductor element to said receiving surface.