Method for fabricating grating pattern

• US 6,361,927 B1
• Filed: 12/14/1999
• Issued: 03/26/2002
• Est. Priority Date: 12/15/1998
• Status: Expired due to Term

• Current Assignee: Havit Company Limited
• Original Assignee: Havit Company Limited
• Inventors: Park, Byung Sun
• Primary Examiner(s): ANGEBRANNDT, MARTIN J
• Application Number:
  US09/461,175
• Time in Patent Office: 833 Days
• Field of Search: 430/320, 430/321, 430/330, 65/172
• US Class Current: 430/321
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams

Abstract

There is a provided a method for fabricating a grating pattern, including the steps of: coating an SOG solution on a glass substrate by spin coating method; heat-treating the SOG thin film coated on the glass substrate, to form a silicon oxide layer; coating a photoresist on the silicon oxide layer and exposing the photoresist layer by masking process; developing the exposed photoresist layer and wet-etching the silicon oxide layer; and developing the photoresist layer used as a mask. According to the present invention, the grating pattern can be fabricated without etching the glass substrate, and high-quality products at a low cost is accomplished since the present invention does not require the expensive sputtering apparatus. Furthermore, the step-shape oxide layer pattern can be obtained through one-time wet etching since the multilevel oxide layer is easily formed.

Claims

1. A method of fabricating a grating pattern, comprising the steps of:

coating a first SOG solution on a glass substrate by a spin coating method to form a first SOG thin film coated on the glass substrate;

heat-treating said first SOG thin film coated on said glass substrate at a first temperature of between 80 and 170°

C. to form a first silicon oxide layer on said glass substrate;

coating a second SOG solution on the first silicon oxide layer by a spin coating method to form a second SOG thin film on the glass substrate;

heat-treating said second SOG thin film at a second temperature to form a second silicon oxide layer, said second temperature being lower than said first temperature and above 80°

C.;

coating a third SOG solution on the second silicon oxide layer by a spin coating method to form a third SOG thin film on the glass substrate;

heat-treating said third SOG thin film at a third temperature to form a third silicon oxide layer, said third temperature being lower than said second temperature and above 70°

C., thus forming a glass substrate with three silicon oxide layers thereon which have different etch rates;

coating a photoresist layer over said first, second and third silicon oxide layers and exposing said photoresist layer by a masking process;

developing said exposed photoresist layer and wet-etching said first, second and third silicon oxide layers once; and

removing said photoresist layer to provide a glass substrate having a three-level stepped grating pattern thereon.

2. The method as claimed in claim 1, wherein said first, second and third silicon oxide layers have a wet etch selectivity to said glass substrate of above 100:

1.

3. The method as claimed in claim 1, wherein the heat treatments are conducted in a gas atmosphere, and refractive index of said silicon oxide layer varies according to the gas atmosphere.

4. The method as claimed in claim 1, wherein said glass substrate with three-level stepped grating pattern thereon is further heat-treated at a temperature of 400-500°

C.