Method for laser interference lithography using diffraction grating

• US 8,399,184 B2
• Filed: 10/08/2008
• Issued: 03/19/2013
• Est. Priority Date: 10/17/2007
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Kim, Tae-Su, Kim, Jae-Jin, Shin, Hyun-Woo
• Primary Examiner(s): RAYMOND, BRITTANY L
• Application Number:
  US12/738,598
• Publication Number:
  US 20100279233A1
• Time in Patent Office: 1,623 Days
• Field of Search: 430/322, 430/5
• US Class Current: 430/322
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• CPC Class Codes: G03F 7/70408 Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect

Abstract

A method for laser interference lithography using a diffraction grating includes (a) forming a photoresist layer on a work substrate to which a repeated fine pattern is to be formed; (b) forming a refractive index matching material layer on the photoresist layer; (c) forming on the refractive index matching material layer a diffraction grating layer having a period of diffraction grating within the range from λ/n_g to λ/n₀ (λ is a wavelength of laser beam, n_g is a refractive index of the diffraction grating, and n₀ is a refractive index in the air or in vacuum); and (d) exposing the photoresist layer by means of mutual interference of positive and negative diffracted lights with the same absolute value by inputting a laser beam perpendicularly to the diffraction grating layer. This method allows to realize an interference pattern with higher resolution and to use a laser source with lower coherence.

Claims

1. A method for laser interference lithography using a diffraction grating, comprising:

(a) forming a photoresist layer on a work substrate to which a repeated fine pattern is to be formed;

(b) forming a refractive index matching material layer on the photoresist layer;

(c) forming on the refractive index matching material layer a diffraction grating layer having a period of diffraction grating within the range from λ

/ng to λ

/n0 (λ

is a wavelength of laser beam, ng is a refractive index of the diffraction grating, and n0 is a refractive index in the air or in vacuum); and

(d) exposing the photoresist layer by means of mutual interference of positive and negative diffracted lights with the same absolute value by inputting a laser beam perpendicularly to the diffraction grating layer.

2. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein, in the step (d), the photoresist layer is exposed by means of mutual interference of +1st diffracted light and −

1st diffracted light.

3. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein, in the step (b), the refractive index matching material layer is an index matching liquid layer.

4. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein the refractive index matching material layer has a refractive index allowing anti-reflection of diffracted light at a border between the diffraction grating layer and the photoresist layer.

5. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein the refractive index matching material layer has a refractive index identical to that of the diffraction grating layer or the photoresist layer.

6. The method for laser interference lithography using a diffraction grating according to claim 1, further comprising:

forming a BARC (Bottom Anti Reflection Coater) between the work substrate and the photoresist layer.

7. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein the diffraction grating layer is a Bragg grating layer.

8. The method for laser interference lithography using a diffraction grating according to claim 1, wherein the diffraction grating layer includes:

a glass substrate;

a BARC formed on the glass substrate; and

a repeated grating pattern formed on the BARC.

9. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein the photoresist layer is a photoresist layer of i-line series or DUV (Deep Ultra Violet) series.

10. The method for laser interference lithography using a diffraction grating according to claim 1,

wherein the diffraction grating layer has a grating pattern whose sectional shape is rectangular, trapezoidal or triangular.