System and method for sub micron additive manufacturing

Patent metadata

Field	Value
Publication number	US-11312067-B2
Application number	US-201715857917-A
Country	US
Kind code	B2
Filing date	Dec 29, 2017
Priority date	Oct 31, 2017
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

An apparatus is disclosed for performing an additive manufacturing operation to form a structure by processing a photopolymer resist material. The apparatus may incorporate a laser for generating a laser beam, and a tunable mask for receiving the laser beam which has an optically dispersive element. The mask splits the laser beam into a plurality of emergent beams each having a subplurality of beamlets of varying or identical intensity, with each beamlet emerging from a unique subsection of illuminated regions of the mask. A collimator collimates at least one of the emergent beams to form a collimated beam. One or more focusing elements focuses the collimated beam into a focused beam which is projected as a focused image plane on or within the resist material. The focused beam simultaneously illuminates a layer of the resist material to process an entire layer in a parallel fashion.

First claim

What is claimed is:

1. An apparatus for performing an additive manufacturing operation to form a structure by processing a photopolymer resist material, the apparatus comprising:
a laser source for generating a laser beam;
a tunable mask for receiving the laser beam wherein the tunable mask comprises an optically dispersive element and is configured to generate a plurality of differing images;
a control system configured to control the tunable mask to generate the plurality of differing images in sequential fashion;
the tunable mask further being configured to split the laser beam into a plurality of emergent beams, wherein each said emergent beam emerging from the tunable mask comprises a subplurality of beamlets of varying or identical intensity, for each one of the differing images, and wherein each said beamlet from each said differing image emerges from a unique subsection of illuminated regions of the tunable mask during projection of each said differing image;
a collimator for collecting and collimating at least one of the emergent beams, from each said differing image, from the tunable mask to form a collimated beam;
a power monitoring unit to collect and measure the power of at least one of said plurality of emergent beams from each said image that are not being projected into a focused image plane and not delivered to the collimator;
one or more focusing elements to focus the collimated beam into a focused beam which is projected as the focused image plane on or within the photopolymer resist material, wherein the tunable mask, the collimator, and the focusing elements are so oriented and positioned as to create the same optical path length between the tunable mask and the focused image plane for all optical frequencies of the laser beam; and
wherein the focused beam simultaneously illuminates a layer of the photopolymer resist material, the focused beam using the differing images to generate a cumulative non-linear exposure dose within the focused image plane to selectively polymerize portions of the photopolymer resist material within the focused image plane.

2. The apparatus of claim 1 , wherein an incident aperture of the collimator is large enough to collect all wavelengths contained within a single one of the emergent beams emerging from the tunable mask but sufficiently small to block all wavelengths of all other ones of the emergent beams.

3. The apparatus of claim 1 , wherein the collimator comprises a convex lens or a concave mirror.

4. The apparatus of claim 1 , further comprising a motion stage to support and move the resist material relative to the focused image plane.

5. The apparatus of claim 4 , further comprising a motion stage to support the one or more focusing elements and to axially move the focused image plane toward or away from the resist material.

6. The apparatus of claim 1 , wherein at least one of the one or more focusing elements comprises a focus-tunable optics comprising an electrically tunable lens (ETL).

7. The apparatus of claim 1 , further comprising a power monitoring system to monitor the power of at least one of the emergent beams emerging from the tunable mask that are not focused on the resist material.

8. The apparatus of claim 7 , further comprising a power control unit including at least one of:
a rotating half-wave plate followed by a polarizing beam splitter to control the power of the beam received by the tunable mask; or
a rotating neutral density filter wheel to control the power of the beam received by the tunable mask.

9. The apparatus of claim 1 , wherein the tunable mask comprises a digital micromirror device (DMD).

10. The apparatus of claim 1 , further comprising an imaging system using an incoherent optical source to monitor the focused beam illuminating the photopolymer resist material.

11. The apparatus of claim 1 , wherein the tunable mask comprises a spatial light modulator (SLM).

12. An apparatus for performing an additive manufacturing operation to form a structure by processing a photopolymer resist material, the apparatus comprising: a laser source for generating a pulsed laser beam having a non-uniform Gaussian profile; a beam homogenizer configured to receive the pulsed laser beam and to convert the non-uniform Gaussian profile to a uniform flat-top profile; a tunable mask for receiving the pulsed laser beam, wherein the tunable mask includes a digital micromirror device (DMD) including a plurality of independently controllable pixels that may be turned on or off; a control system for configured to control the tunable mask to generate a plurality of differing images in sequential fashion; the tunable mask further being configured to split the pulsed laser beam into a plurality of emergent beams, for each one of said plurality of differing images, wherein each said emergent beam emerging from the tunable mask comprises a subplurality of beamlets of varying or identical intensity, for each one of said plurality of differing images, and wherein each said beamlet emerges from a unique pixel; a collimator for collecting and collimating all wavelengths of only a select one of the plurality of emergent beams, from each one of said differing images, from the tunable mask, and the collimator being configured to block all wavelengths of all other ones of the emergent beam, to produce a collimated beam; one or more focusing elements to focus the collimated beam into a focused beam which is projected as a focused image plane on or within the photopolymer resist material, wherein the tunable mask, the collimator, and the focusing elements are so oriented and positioned as to create the same optical path length between the tunable mask and the focused image plane for all optical wavelengths of the pulsed laser beam, and for each one of the differing plurality of images; a power monitoring unit configured to collect and measure the power of at least one of said plurality of emergent beams that are not being projected into the focused image plane and not delivered to the collimator; a motion stage to support and move the photopolymer resist material relative to the focused image plane; and wherein the focused beam simultaneously illuminates a layer of the photopolymer resist material using the plurality of differing images, and in connection with movement of the photopolymer resist material by movement of the motion stage, generates a cumulative non-linear exposure dose within the focused image plane to selectively polymerize portions of the photopolymer resist material within the focused image plane.

13. The apparatus of claim 12 , wherein the tunable mask is oriented at such an angle to the pulsed laser beam being received as to generate a blazed grating condition for the center wavelength of the pulsed laser beam being received.

14. The apparatus of claim 12 , further comprising a power monitoring unit to collect and measure the power of at least one of said plurality of emergent beams that are not used to generate the focused image plane.

15. The apparatus of claim 14 further comprising a power control unit including one of:
a rotating half-wave plate followed by a polarizing beam splitter; or
a rotating neutral density filter wheel to control the power of the pulsed laser beam received by the tunable mask.

16. The apparatus of claim 12 , further comprising a control unit to tune the DMD upon receiving a trigger signal from an internal or external clock.

17. The apparatus of claim 12 , wherein one of the focusing elements comprises an electrically tunable lens (ETL) to optically translate an axial position of a focal

Assignees

• L Livermore Nat Security Llc

Inventors

• Saha Sourabh Kumar
• Panas Robert Matthew
• Chen Shih-Chi

Classifications

• G02B27/285

  comprising arrays of elements, e.g. microprisms · CPC title

• G02B26/0833

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title

• G03F7/70258

  Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• G03F7/70291

  Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices · CPC title