Stereolithographic patterning with interlayer surface modifications

• US 6,730,256 B1
• Filed: 08/06/2001
• Issued: 05/04/2004
• Est. Priority Date: 08/04/2000
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Kunz, Roderick R., Bloomstein, Theodore M., Palmacci, Stephen T.
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US09/923,164
• Time in Patent Office: 1,002 Days
• Field of Search: 264/401, 430/324, 430/329
• US Class Current: 264/401
• CPC Class Codes: B29C 2035/0838 using laser
• CPC Class Codes: B29C 2791/005 Using a particular environment, e.g. sterile fluids other than air
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B29C 71/0009 using liquids, e.g. solvents, swelling agents spectacle cases, e.g. for cleaning contact lenses A45C11/04; disinfecting or sterilising contact lenses A61L12/00, using liquid substances A61L2/20; cleaning involving the use of liquid in general B08B3/00; for hydrating contact lenses B29D11/00067
• CPC Class Codes: B29K 2105/0073 Solution
• CPC Class Codes: B29K 2995/0073 smooth
• CPC Class Codes: B29K 2995/0092 hydrophilic
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: G03F 7/70416 2.5D lithography

Abstract

Methods for the preparation of multilayered resists include exposure of the a first layer to radiation followed by exposure to an oxidizing agent. The oxidizing agent alters the surface characteristics of the first resist layer such that it is rendered more hydrophilic than the original resist layer. A second layer of resist is then applied to the oxidized surface of the first resist layer and exposed to radiation. This process can be repeated for thousands of coating layers, thereby permitting stereolithographic patterning of parts and construction of micromachines. A final treatment with a dissolution solution will dissolve unwanted resist material. Dependent upon the type of resist material used in the multilayered resist, the dissolution solution can remove the radiation exposed areas, e.g., a positive resist, or remove unexposed areas, e.g., a negative resist.

Claims

1. A method for patterning a multilayer resist comprising:

depositing a first layer of photoresist material from a first solution onto a substrate;

exposing a portion of the first layer to radiant energy;

treating the first layer to create a treated surface;

depositing a second layer of photoresist material from a second solution, the second layer located atop the treated surface, the treated surface capable of inhibiting penetration of a solvent component of the second solution into the first layer; and

exposing a portion of the second layer to radiant energy.

2. The method of claim 1, wherein the method further comprises:

developing the layers in a single, final step to remove the exposed portions of each layer when the photoresist material comprises a positive resist.

3. The method according to claim 1, wherein the steps are repeated until a multilayer resist having greater than two layers has been completed.

4. The method of claim 1, wherein the method further comprises:

developing the layers in a single, final step to remove unexposed portions of each layer when the photoresist material comprises a negative resist.

5. The method of claim 1, wherein the method further comprises:

heating the multilayer resist following exposing at least one portion.

6. The method of claim 1, wherein the photoresist material comprises a resin selected from the group consisting of phenol-formaldehydes, polyhydroxystyrenes and cyclicpolyvinyls.

7. The method of claim 6, wherein the resin is a phenol-formaldehyde polymer.

8. The method of claim 1, wherein the radiant energy is laser radiation ranging in wavelength from about 4 nanometers to 520 nanometers.

9. The method according to claim 1, wherein treating comprises oxidation.

10. The method according to claim 9, wherein oxidation is accomplished using an agent selected from the group consisting of ozone, peroxide, oxygen plasma and combinations thereof.

11. The method according to claim 10, wherein the agent is ozone.

12. The method of claim 1, wherein the treated surface has carbonyl or hydroxyl functionality.

13. The method of claim 1, wherein treating increases the hydrophilicity of the treated surface.

14. The method of claim 1, wherein treating increases the hydrophobicity of the treated surface.

15. The method according to claim 1, wherein the solution comprises a solvent that is a mixture of liquids.

16. A method of making a multilayer stereolithographic preform comprising:

depositing a base layer of photoresist from a base solution onto a substrate

surface treating the base layer to inhibit penetration of solvent into the base layer; and

depositing an overlayer of photoresist from a second solution, the second solution comprising solvent, the overlayer located atop the base layer to create a multilayer preform;

such that subsequently developing the preform to create a multilayer stereographic pattern may be performed in a single, final step.

17. The method according to claim 16, wherein surface treating and depositing are repeated a number of times, each additional overlayer deposited atop a surface treated overlayer.

18. The method according to claim 16, wherein surface treating comprises oxidation.

19. The method according to claim 18, wherein oxidation is accomplished using an agent selected from the group consisting of ozone, peroxide, and oxygen plasma.

20. The method according to claim 19, wherein the agent is ozone.