Claims
- 1. A method of exposing light comprising the steps of:
- forming a mask pattern made of a mask film pattern formed on a light-transmissible substrate, the mask pattern being a semi-transparent film which causes a length of an optical path for a light beam passing therethrough to be different from a length of an optical path for a light beam passing through the substrate by a predetermined amount, the step of forming a mask pattern comprising the steps of:
- determining ranges of refractive index n and extinction coefficient k of the semi-transparent film within which an amplitude transmissivity ratio T and a phase difference .phi. between the semi-transparent film and air that has the same thickness of the semi-transparent film fall within ranges necessary to obtain desired resolution and depth of focus,
- obtaining relationship in the form of a curved line between the refractive index n and the extinction coefficient k by changing conditions for formation of the mask pattern,
- selecting values of the refractive index and the extinction coefficient k from the ranges thus determined, and determining the conditions for formation of the mask pattern such that the refractive index n and the extinction coefficient k become the selected values, and
- forming a mask film pattern based on the conditions for formation of the mask pattern; and
- irradiating an exposure beam onto a resist through a reticle using the mask pattern.
- 2. A method of exposing light as set forth in claim 1, wherein the step of forming the mask film pattern comprises the step of forming a silicon nitride or silicon oxide film having desired values of amplitude transmissivity ratio and phase difference by mixing a predetermined quantity of nitrogen or oxygen gas in a sputtering atmosphere using silicon as a target and controlling a nitrogen or oxygen composition ratio based on the conditions for formation of the mask pattern.
- 3. A method of exposing light as set forth in claim 2, wherein said phase difference is substantially .pi..
- 4. A method of exposing light as set forth in claim 1, wherein said exposure beam is a g ray and the step of forming the mask film pattern comprises the step of forming a mask pattern made of amorphous silicon based on the conditions for formation of the mask pattern, thereby forming a mask pattern having desired values of amplitude transmissivity ratio and phase difference.
- 5. A method of exposing light as set forth in claim 4, wherein, said phase difference is substantially .pi..
- 6. A method of exposing light as set forth in claim 4, wherein the step of forming the mask film pattern comprises the step of forming a silicon nitride or silicon oxide film having desired values of amplitude transmissivity ratio and phase difference by mixing a predetermined quantity of nitrogen or oxygen gas in a sputtering atmosphere using silicon as a target and controlling a nitrogen or oxygen composition ratio based on the conditions for formation of the mask pattern.
- 7. A method of exposing light as set forth in claim 1, wherein said exposure beam is an i ray.
- 8. A method of exposing light as set forth in claim 1, wherein said exposure beam is an g ray.
- 9. A method of exposing light as set forth in claim 1, wherein the step of forming the mask film pattern comprises the step of depositing a silicon dioxide film while adjusting the quantity of oxygen in a raw material gas by using a CVD technique based on the conditions for formation of the mask pattern so as to control an oxygen composition ratio in the silicon dioxide film, thereby forming a mask pattern having desired values of amplitude transmissivity ratio and phase difference.
- 10. A method of exposing light as set forth in claim 1, wherein the step of forming the mask film pattern comprises the step of depositing a silicon nitride film while adjusting the quantity of ammonium in a raw material gas by a CVD technique based on the conditions for formation of the mask pattern so as to control a nitrogen composition ratio, thereby forming a mask pattern having desired values of the amplitude transmissivity ratio and the phase difference.
Priority Claims (4)
Number |
Date |
Country |
Kind |
331308 |
Nov 1990 |
JPX |
|
163131 |
Jul 1991 |
JPX |
|
294540 |
Nov 1991 |
JPX |
|
297461 |
Nov 1991 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 08/192,091, filed Feb. 4, 1994 now abandoned which is a continuation-in-part of application Ser. No. 07/798,721, filed Nov. 29, 1991 now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5214489 |
Mizutani et al. |
May 1993 |
|
5328807 |
Tanaka et al. |
Jul 1994 |
|
5424153 |
Asai |
Jun 1995 |
|
Foreign Referenced Citations (2)
Number |
Date |
Country |
4-136854 |
May 1992 |
JPX |
5-127361 |
May 1993 |
JPX |
Divisions (1)
|
Number |
Date |
Country |
Parent |
192091 |
Feb 1994 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
798721 |
Nov 1991 |
|