Method of forming resist pattern, and exposure device

• US 20030117608A1
• Filed: 12/12/2002
• Published: 06/26/2003
• Est. Priority Date: 03/27/2000
• Status: Active Grant

• Current Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Original Assignee: Takamitsu Furukawa
• Inventors: Furukawa, Takamitsu
• Granted Patent: US 6,956,641 B2
• Time in Patent Office: Days
• US Class Current: 355/69
• CPC Class Codes: G03F 7/2024 of the already developed image
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking

Abstract

A method of forming a resist pattern and an exposure device using the method are provided in which a relatively large pattern, whose dimension is greater than a resolution limit of a KrF exposure technique, and an extremely fine pattern, whose dimension is less than or equal to the resolution limit of the KrF exposure technique, can be formed well and simultaneously. Two patterns are exposed simultaneously by deep UV light of a wavelength of 248 nm on a resist film 10 formed of TDUR-P015 and formed on a surface of an SiO₂ film 12. The two patterns are: a circular pattern of a dimension which is made larger, in accordance with a shrinkage rate, than a finally required pattern dimension, which circular pattern is formed at regions to be shrunk; and a circular pattern of a dimension which is finally required, which circular pattern is formed at regions not to be shrunk. A UV light exposure amount, which is of an amount such that heat resistance of the TDUR-P015 forming the resist film 10 improves and the resist pattern does not shrink, is applied only onto the regions not to be shrunk of the resist pattern obtained by development. Then, high temperature bake processing at 135° C. for 60 seconds is carried out.

Claims

1. A method of forming a resist pattern comprising the steps of:

subjecting a resist, which is applied on a surface of an object to be processed, to pattern exposure in which a first exposure amount for forming a pattern is applied to the resist;

forming a resist pattern by developing the resist;

subjecting the resist pattern to a second exposure in which a second exposure amount, which adjusts a shrinkage rate of the resist pattern, is applied to the resist pattern; and

subjecting the resist to a bake process at a temperature at which the resist flows.

2. The method of forming a resist pattern of claim 1, wherein the second exposure amount is an exposure amount which is at least equal to a saturation exposure amount of the resist.

3. The method of forming a resist pattern of claim 1, wherein the resist pattern includes regions to be shrunk at a predetermined shrinkage rate and regions not to be shrunk, and the step of subjecting the resist pattern to a second exposure includes the sub-step of exposing regions to be shrunk at the second exposure amount, which corresponds to the predetermined shrinkage rate, and exposing regions not to be shrunk at a third exposure amount which provides the resist pattern with resistance to shrinkage during the step of subjecting the resist to a bake process.

4. The method of forming a resist pattern of claim 1, further comprising the step of:

adjusting the second exposure amount for each of predetermined regions of the object to be processed in accordance with shrinkage rate differentials due to a distribution of temperatures arising during the step of subjecting the resist to a bake process.

5. The method of forming a resist pattern of claim 1, further comprising the step of:

correcting the second exposure amount for each of predetermined regions of the object to be processed for eliminating a distribution of errors in shrinkage rates of a pattern to finally be formed on the object.

6. The method of forming a resist pattern of claim 4, wherein the step of adjusting the second exposure amount is carried out at the time of second exposure by adding a correction amount to a pre-correction second exposure amount.

7. The method of forming a resist pattern of claim 4, wherein the step of adjusting the second exposure amount is carried out by performing an additional exposure at an exposure amount corresponding to a correction amount, after the second exposure has been carried out at a pre-correction second exposure amount.

8. The method of forming a resist pattern of claim 5, wherein the step of adjusting the second exposure amount is carried out at the time of second exposure by adding a correction amount to a pre-correction second exposure amount.

9. The method of forming a resist pattern of claim 5, wherein the step of adjusting the second exposure amount is carried out by performing an additional exposure at an exposure amount corresponding to a correction amount, after the second exposure has been carried out at a pre-correction second exposure amount.

10. The method of forming a resist pattern of claim 1, wherein the resist is a resist for use with UV light, and exposures are performed using UV light.

11. The method of forming a resist pattern of claim 1, further comprising the step of:

adjusting the shrinkage rate of the resist pattern by adjusting bake temperature while subjecting the resist to the bake process.

12. A device for exposure of an object surface having a predetermined shrinkage rate during bake processing of the object following exposure, the device comprising:

(a) an optical system having a light source which when operated irradiates light of a substantially uniform intensity towards a target location, which location is for placement of the object surface thereat for exposure;

(b) a filter provided between the target location and the light source, the filter having an adjustable transmission rate, which passes light irradiated from the light source therethrough for each of predetermined regions of the object surface in an exposure amount corresponding to a predetermined shrinkage rate for the object surface when bake processed following exposure.

13. The device of claim 12, wherein the transmission rate of the filter is corrected for each predetermined region of the object surface for reducing a distribution of errors in the shrinkage rate, which distribution corresponds to a temperature distribution arising in the object during the bake process.

14. The exposure device of claim 12, wherein the transmission rate of the filter is corrected for each predetermined region of the object to be processed for reducing a distribution of errors in the shrinkage rate for forming a final pattern on the object surface.

15. A method of forming a resist pattern, comprising the steps of:

(a) applying a resist to an object surface;

(b) subjecting the resist to pattern exposure by irradiating the resist with light directed through a first reticle;

(c) developing the resist;

(d) adjusting a shrinkage rate of the resist pattern by irradiating the resist with light directed through a second reticle; and

(e) baking the resist.

16. The method of claim 15, wherein the step of adjusting a shrinkage rate includes irradiating areas of the resist with light of at least 2.7 mJ/cm².

17. The method of claim 15, wherein the step of adjusting a shrinkage rate includes irradiating areas of the resist with light of at least 3.3 mJ/cm².

18. The method of claim 15, wherein the step of adjusting a shrinkage rate includes providing the second reticle for passing light therethrough for exposing areas of the resist which are not to be shrunk.

19. The method of claim 15, further comprising the step of irradiating the resist with light in an amount from 2.7 to 3.3 mJ/cm².

20. The method of claim 19, wherein the step of irradiating the resist with light in the amount from 2.7 to 3.3 mJ/cm² includes irradiating areas of the resist in accordance with temperature differentials that arise in the resist during the step of baking.