JPS6310891B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a pattern having a line width in the submicron range.

2. Description of the Related Art In recent years, in order to improve the degree of integration and high speed of semiconductor devices, pattern forming technology with line widths in the submicron region has been required.

Electron beam exposure is usually used to form patterns with line widths in the submicron range. However, in electron beam exposure, the optimum exposure amount differs depending on the pattern line width, so when forming element patterns with various line widths, parts of a certain line width can be formed as designed, but parts of other line widths cannot be formed. There is a problem in that the exposure amount deviates from the optimum exposure amount and cannot be formed as designed. Further, even if the designed line width is the same, there is a problem in that the finished pattern line width varies depending on the degree of pattern density.

An object of the present invention is to provide a pattern forming method with high line width accuracy.

By the way, the present inventors have separately proposed the following pattern forming method for the same purpose.

FIG. 1 is a plan view of a desired pattern, where 1 is a substrate and 2 is a concave portion.The method is shown in a sectional view explaining the process in FIG. 2, and consists of the following steps.

(1) Apply an electron beam resist 3 to the substrate 1, and simply repeat the line and resist pattern using the electron beam 4.
Expose the first pattern of spaces.

(2) Develop the electron beam resist 3 to form the first pattern 10.

(3) A resist 11 is applied thereon, and exposure 13 is performed so as to include the lines 12 included in the desired second pattern. The minimum space width of this second pattern is larger than the space width of the first pattern 10.

(4) Develop the resist 11 to form spaces 14.

(5) Delete the line included in space 14.

(6) The resist 11 is further exposed and developed to form a third pattern including spaces 15. The minimum space width of this third pattern is also larger than the space width of the original first pattern 10.

(7) By etching the substrate 1 using the electron beam resist 3 and the resist 11 as masks, the recess 1 is etched.
6, 17, etc. are formed, and the electron beam resist 3 and resist 11 are peeled off.

The pattern thus obtained consists of the spaces 14 of the first pattern after removing the lines of the electron beam resist 3 in the spaces 14 of the second pattern of the resist 11, and the spaces 1 of the third pattern.
It is divided into regions by logical AND with 5.

The groove width obtained is the same for both the recesses 16 in the dense portion and the recesses 17 in the isolated portion.

However, in such a method, when forming the second pattern including the space 14, alignment with the first pattern of the resist 3 is performed,
Also, when forming the third pattern including the space 15, alignment with the first pattern of the resist 3 is performed. In the end, since the alignment process is performed twice, the quality of the finally obtained pattern is reduced accordingly.

The present invention provides a pattern forming method that not only has good line width accuracy but also has a high yield by requiring only one alignment step.

That is, according to the present invention, the steps include forming a first pattern of simply repeated lines and spaces, applying a resist on the first pattern, and applying a resist to the resist so that the minimum space width is equal to that of the first pattern. a step of exposing two types of patterns, a second and a third pattern larger than the space width of the pattern, under different exposure conditions; a step of developing the resist so that the second pattern appears first; a step of removing the lines of the first pattern appearing in the spaces of the pattern, a step of developing the resist so that the third pattern appears, and a step of developing the lines of the first pattern appearing in the spaces of the third pattern. There is obtained a pattern forming method comprising the step of processing a workpiece so that the spaces of the first pattern become recesses or protrusions of a desired pattern.

The pattern forming method of the present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a cross-sectional view illustrating the process of the pattern forming method of the present invention.

(1) Apply an electron beam resist 3 to the substrate 1, and simply repeat the line and resist pattern using the electron beam 4.
Expose the first pattern of spaces.

(2) Develop the electron beam resist 3 to form the first pattern 10.

(3) A resist 11 is applied thereon, and exposure 31 with a relatively large amount of exposure and exposure 32 with a relatively small amount of exposure are performed at the same level. Here, exposure 3
1, a second pattern is exposed, and exposure 32, a third pattern.

(4) Develop the resist 11 to first form a second pattern including the spaces 14.

(5) Delete the line included in space 14.

(6) Develop resist 11 further to create space 15
form a third pattern containing.

(7) By etching the substrate 1 using the electron beam resist 3 and the resist 11 as masks, the recess 1 is etched.
6, 17, etc. are formed, and the electron beam resist 3 and resist 11 are peeled off.

The pattern thus obtained consists of the spaces 14 of the first pattern after removing the lines of the electron beam resist 3 in the spaces 14 of the second pattern of the resist 11, and the third pattern formed by exposure 32. The area is formed by logical product of the pattern with space 15.

The groove width obtained is the same for both the recesses 16 in the dense portion and the recesses 17 in the isolated portion.

In this step (3), the exposures 31 and 32 having different amounts of exposure can be provided by providing a semi-transparent part in a mask for X-ray exposure or optical exposure. Further, exposure may be performed by partially changing the exposure amount by electron beam exposure.

Further, in order to form the third pattern including the spaces 15 in step (6), it is possible to simply add development, but it is also possible to change the developer, the composition of the developer, the developing temperature, or the atmosphere during development. .

Note that although a positive type resist 11 is used in this embodiment, it is of course possible to use a negative type resist 11. In that case, the exposure conditions in step (3) will be completely reversed, and the part where the space of the second pattern should be formed will not be exposed at all, and the space part of the second pattern of the space part of the third pattern will be exposed. The removed portions may be exposed to weak light, and the portions where the resist 11 should remain may be exposed to strong light.

As described above, according to the present invention, the line width accuracy is high and a simple repeating line and space pattern and a complex pattern only need to be aligned once, making it possible to form patterns with a high yield. Become.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a desired pattern, and FIG. 2 is a cross-sectional view explaining the process of a conventional method for forming the pattern shown in FIG.
A diagram showing a state in which a simple line and space first pattern is repeatedly exposed, 2 a diagram showing a developed state, 3 a diagram showing a state in which another resist is applied and exposed, 4 is a diagram showing the state after development to form the second pattern, 5 is a diagram showing the state with lines in the spaces of the second pattern removed, and 6 is a diagram showing the state after further exposure and development to form the third pattern. The figure 7 shows the formed state, and the figure 7 shows the state after etching and the resist has been peeled off. FIG. 3 is a cross-sectional view explaining the process of the pattern forming method of the present invention, and 1 is a diagram showing a state in which a resist is applied to a substrate and a first pattern of simple lines and spaces is repeatedly exposed. 2 shows the developed state, 3 shows the state where another resist is applied and the second pattern and third pattern are exposed to different amounts of light, and 4 shows the developed state and the second pattern 5 is a diagram showing a state in which lines in the spaces of the second pattern have been removed. 6 is a diagram showing a state in which the resist is further developed and a third pattern is formed. 7 is a diagram showing a state in which a third pattern is formed. FIG. 3 is a diagram showing a state after etching and peeling off the resist. In the figure, 1 is a substrate, 2 is a groove of a desired pattern, 3, 11 is a resist, 4, 31, 32
is the exposure, 10 is the first pattern, 12 is the line of a simple line-and-space pattern included in the second pattern, 14 is the space of the second pattern, 15 is the space of the third pattern , 16, 17 represent the obtained grooves.

Claims (1)

[Claims] 1. A step of forming a first pattern of simply repeated lines and spaces, applying a resist on the first pattern, and forming a resist with a minimum space width larger than the space width of the first pattern. A step of exposing two types of patterns, a second and a third, under different exposure conditions, a step of developing the resist so that the second pattern appears, and a step of developing the resist in the space of the second pattern. removing the lines of the first pattern that have appeared, then developing the resist so that the third pattern appears, and the first pattern appearing in the spaces of the third pattern. A pattern forming method comprising the step of processing a workpiece so that the spaces in the pattern become concave or convex portions of a desired pattern.