Topography transfer method with aspect ratio scaling

• US 20060166508A1
• Filed: 01/27/2006
• Published: 07/27/2006
• Est. Priority Date: 01/27/2005
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Contour Semiconductor, Inc.
• Inventors: Shepard, Daniel Robert
• Granted Patent: US 7,682,981 B2
• Time in Patent Office: Days
• US Class Current: 438/736
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G03F 7/0002 Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• CPC Class Codes: H01L 21/3085 characterised by their behaviour during the process, e.g. soluble masks, redeposited masks
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/76804 by forming tapered via holes
• CPC Class Codes: H01L 21/76817 using printing or stamping techniques

Abstract

The present invention is a method of applying a topographical surface to a part such as a substrate without the need for low temperature softening of that part while retaining high aspect ratios and densely packed features in that topography. A substrate, selected for its ability to be processed at a given desired temperature, has a layer of material applied to its surface. This layer is selected, among other reasons, for its ability to be molded. Typically, it is expected that the substrate will be able to withstand the higher temperatures of semiconductor post-processing whereas the applied layer will be moldable at low temperatures. This combination enables low cost embossing of a topography into this surface layer. The present invention comprises means to transfer this topography from the low temperature material into the higher temperature substrate. In addition, the present invention comprises a means to scale the aspect ratio of the features of that topography when it is transferred into the substrate material. Since the sidewall angle must be opened enough to permit demolding of the master form from the substrate after molding, some very vertical sidewall angles may not be possible during a molding-demolding operation. The present invention is a means to achieve steeper sidewall angles on features in a substrate where those features are applied by way of a molding process.

Claims

1. A method for transferring a topography into a substrate from a layer of material on the surface comprising the steps of:

a. applying said layer of material to the surface of said substrate,

b. applying a topography to the layer of material, and

c. etching to transfer the topography into the substrate.

2. The method of claim 1 whereby the etch rate of said layer of material and said substrate are different and the ratio of the difference in etch rates will generally control the scaling of the aspect ratio of the topography etched into said substrate.

3. The method of claim 1 further comprising a layer or layers of material having a slower rate of etching such that the depth of one or more of the features of the topography is generally determined.

4. A method for transferring a topography from a layer into a substrate comprising the steps of:

a. applying a layer of material to the surface of a substrate,

b. patterning a topography into the layer of material,

c. etching to transfer the topography into the substrate, and

d. scaling the aspect ratio of the topography as a function of the difference in the etch rates of the layer of material and the substrate.

5. The method of claim 4 whereby the topography is patterned using gray-scale lithography.

6. The method of claim 4 whereby the topography is applied using molding.

7. The method of claim 6 whereby the molded topography is applied by imprinting.