JPH03127818A - Manufacture of reticle - Google Patents

Abstract

PURPOSE:To eliminate the influence of instability of a pattern by performing electron beam exposure by using a first variable slit and a second fixed slit, and eliminating other resist except this pattern by photolithography. CONSTITUTION:When a light shielding film pattern 12 is formed on a substrate 11 for a reticle on which substrate a light shielding film 12a and resist 13 thereon are spread, electron beam exposure is performed by using a first variable slit 21 and a second fixed slit 22, so as to left only the resist of the pattern 12. The resist except the pattern 12 is eliminated by photolithography. Thereby the influence of instability of a pattern can be eliminated, and a reticle having a high precision pattern can be manufactured with high throughput.

Description

[Detailed Description of the Invention] [Summary] Regarding a reticle manufacturing method, that is, a method for manufacturing a reticle that is an original plate for device pattern creation, the present invention relates to a method for manufacturing a reticle, which is an original plate for creating a device pattern, which reduces the influence of pattern instability that has conventionally been observed in forming a reticle pattern by electron beam exposure. In order to create a light shielding film pattern on a reticle substrate with a light shielding film and a resist coated thereon by electron beam exposure, the present invention aims to provide an EB exposure method that is variable so that only the resist of the pattern remains. The present invention includes a method for manufacturing a reticle, which includes a step of performing electron beam exposure using a first slit and a fixed second slit, and removing resist other than the pattern by photolithography.

[Industrial application field]

The present invention relates to a method for manufacturing a reticle, that is, a method for manufacturing a reticle and a mask, which are original plates for device pattern creation.

As device patterns become smaller and more precise, it is becoming necessary to increase the dimensional accuracy of reticle patterns. Therefore, when creating a reticle pattern using an electron beam (EB) n light, when creating a pattern using a variable rectangular beam, the size of the variable rectangular beam is affected by the influence of heat, and ■ the design dimensions of the EB exposure machine. Due to the problem of linearity between values and actual dimensions, the actual dimension values of patterns with the same dimensions differ even in apparent patterns due to differences in rectangular division. Therefore, it is necessary to make the dimensions of the same pattern by rectangular division uniform.

[Conventional technology]

There are two methods for EB exposure: a method in which the EB exposure is performed with the shape of the electron beam unchanged, and a method in which the shape of the electron beam is made variable. In the former case, since the beam shape is fixed, there are problems such as throughput during EB exposure. In the latter case, the electron beam shape is variable, so the throughput is fast, but due to the effects of heat during EB exposure, the effects of secondary electron scattering, and the actual size of the variable rectangle and dimensional linearity due to design irregularities, it is difficult to use a reticle. The dimensional accuracy is poor. There is a method of solving the above problem by adding a shift using software, but this is not a complete solution due to problems such as the complexity of the pattern and the stability of the EB exposure machine.

The method of forming a rectangular pattern by EB exposure while keeping the electron beam shape unchanged will be explained with reference to FIG.
) Silicon substrates 43 and 44 having rectangular first slits 41 and rectangular second slits 42 formed therein are prepared.

Using these silicon substrates 43 and 44, a rectangular pattern is irradiated onto a sample (not shown) by EB exposure. For this, a circular beam 45 is passed through the first slit 41 to the fourth
The beam obtained by cutting as shown in the enlarged view of Figure (b) (shown with diagonal lines in the figure) is shown in Figure (b).
As shown in the enlarged view of FIG. 1C, it is placed on the second slit 42, thereby obtaining a rectangular EB shot 46 shown by crossed diagonal lines in FIG.

The size of the shot is not determined by moving the slit itself, but by moving the first slit 4 shown in Figure 4(b).
It is determined by electrically waving the beam cut by 1 onto the second slit 42. Thus, from an image perspective, the first slit is variable and the second slit is fixed, and one shot is determined by how much the first slit beam is swung over the second slit.

[Problem to be solved by the invention]

Referring to FIG. 3, when attempting to form the light-shielding film pattern shown in FIG. 3(a) by EB exposure, the pattern shown in FIG.
Using a silicon substrate called the variable first slit 21 and a silicon substrate called the fixed second slit 22 shown in b), the variable first slit 21 is moved in the X direction and the Y direction. A light-shielding film pattern shown in FIG. 3(a) consisting of a rectangle is formed. Here, in the same figure (a)
In the pattern, the distance indicated by A becomes 11Im, and the distance indicated by B
It is assumed that the distance indicated by is set to 2 μm.

Referring to the same figure (b), the lines 23 and 24 formed by the fixed second slit 22 are fixed and stable. However, the lines 25 and 26, which are variable in the directions of the white arrows and created by the first variable slit 21, are unstable due to the influence of the exposure machine that irradiates EB through the first variable slit 21, so the dimensional linearity is poor. Fixed second slit 2
Linearities 25 and 26 are unstable compared to the linearity of the pattern created by 2. As a result, the same figure (
When the light shielding film pattern shown in C) is made with the first and second slits, the design values are A=A', B=B'
, C=C', but A and A'
, B and B' are on the fixed side or on the variable side in FIG. 3(b), the 0 width and the C' width may differ.

In addition, as shown in (d) and (e) of the same figure, when a figure with the same dimensions is formed by 4-divided irradiation (shot) and 16-divided shot, when the same acceleration voltage and current density are used, Due to the influence of heat, the actual size of the 4-part shot shown in (d) is larger than that of the 16-part shot shown in (e) of the same figure.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an EB exposure method that reduces the influence of pattern instability that has conventionally been observed in the formation of reticle patterns by electron beam exposure.

[Means for solving the problem] The above problem is to create a light-shielding film pattern by electron beam exposure on a reticle substrate having a light-shielding film and a resist coated thereon, so as to leave only the resist of the pattern. The problem is solved by a method for manufacturing a reticle, which includes a step of performing electron beam exposure using a fixed second slit and a variable first slit, and removing resist other than the pattern by photolithography.

[Effect]

That is, in the present invention, only the outline of the pattern that requires high dimensional accuracy within the reticle is formed by an EB shot of 1.5-angle or less, and the light shielding film in other parts where the light shielding film is not required is removed by a photolithography process. be.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

Figure 1 shows an embodiment of the present invention, which is a plan view of the figure (a) and O))
An example of forming the light shielding film pattern shown in the cross-sectional view will be described. In the figure, 11 is a reticle substrate (for example, a quartz substrate), and 12 is a light-shielding film pattern made of, for example, chrome.

In the first step, a chromium film 12a, for example, is formed as a light-shielding film on the quartz substrate 11, and a resist, for example, a positive resist 13, is applied onto the chromium film 12a. Next, a rectangular first shot 14a with one side of 1.5 μm or less is formed.
As shown in FIG. 3C, correction values are added in software in consideration of the influence of heat and the influence of secondary electron scattering, and the shots 14b subsequent to the second shot are then irradiated one after another. The inner edges of these shots 14a and 14b are made to correspond to the outer edges of the light-shielding film pattern 12 to be formed as shown in FIG. Shown with .

Next, when the positive resist 13 is developed, the exposed resist 13a is removed as shown in the plan view of FIG. Regislot 3b remains. Conversely, in the case of a punching pattern using a negative resist, the negative resist corresponding to the exposed positive resist 13a remains, and the negative resist corresponding to the unexposed positive resist 13b is removed.

Next, as shown in the cross-sectional view of FIG. 3(g), a positive resist 15 is applied to the entire surface.

Next, as shown in the cross-sectional view of the same figure (h), a resist (3b) that is larger than the unexposed resist (3b (this corresponds to the dimension of the light-shielding film pattern 12 shown in the same figure (a) and (b)). Using a mask 17 having a light-shielding film 16, light 18 is irradiated by photolithography.

Next, the positive resist 15 is developed, the exposed chromium film 12a is etched, and the remaining positive resist 5 is peeled off. Thus, a light-shielding film pattern 12 having the same dimensions as those shown in FIGS. 4A and 3B is obtained.

Returning now to FIG. 1(C), lines 14c and 14d of the first shot 14a are replaced by lines 23.24 shown in FIG. 3(b).
Similarly, if we use fixed slit lines, only the other two lines are unstable and there is a problem with linearity, but the linearity is corrected by software as described above, so the other two lines are unstable and have a problem with linearity. Line instability is minimized so that shots 14b following the second shot have stable contours.

FIG. 2 is a diagram showing the effect of the present invention, which was created based on the results of experiments according to the inventor. This experiment was carried out to form a light-shielding film pattern 19 and 20 shown in the plan view of FIG.

The light shielding film patterns 19 are a8, C1, a2, C2,...
A pattern with a width of , a light-shielding film pattern 20,
The pattern has widths of dl, b2, d2, . . .

In the same figure (B), the dose was 10μC/cr by the conventional method.
It shows a shift from the average value of 3.35 when EB is irradiated at M0, and the parts indicated by als 111... on the horizontal axis indicate measurement points, with a shift value of 10 upwards and a shift value of - downwards. Take.

The same figure (C) shows that according to the present invention, the dose amount is 10 μC/c [
It is a diagram similar to the same figure (B) showing the amount of shift from the average value of 4.66 when EB is irradiated at. In the conventional example shown in FIG. 3(B), it was confirmed that the pattern size variation was 0.07-M, but in the case of the present invention, it was reduced to 0.031M.

〔Effect of the invention〕

As described above, according to the present invention, in addition to significantly reducing variations in pattern accuracy, the light-shielding film other than the required light-shielding film pattern can be removed at one time using photolithography technology, which has excellent throughput. This has the effect of increasing throughput and producing reticles with

[Brief explanation of the drawing]

FIG. 1 is a diagram of an embodiment of the present invention, including (a), (C), (
e), (i) are plan views, (b), (d), (f),
(g), peaks), and (j) are cross-sectional views. Figure 2 is a diagram showing the effect of the present invention, (^) is a plan view of a light-shielding film pattern, and (B) is a diagram of pattern dimensions according to the conventional method. A line diagram showing variations; (C) is a diagram showing variations in pattern dimensions according to the present invention; FIGS. 3(a) to (e) are plan views explaining pattern formation by EB rectangular division shots; (a), (b), and (C) are plan views showing a method of forming a rectangular pattern using two silicon substrates. In the figure, 11 is a quartz substrate, 12 is a light shielding film pattern, 12a is a chrome film, 13 is a positive resist, 13a is an exposed resist, 2 13b is an unexposed resist, 14a is a first shot, 14b is a second shot 15 is a positive resist, 16 is a light-shielding film, 17 is a mask, 18 is a light, 19 and 20 are light-shielding film patterns, 21 is a variable first
22 is a fixed second slit; 14c, 14d, 23, 24, 25, and 26 each indicate a rectangular pattern line.

Claims (1)

[Claims] In creating a light-shielding film pattern (12) by electron beam exposure on a reticle substrate (11) having a light-shielding film (12a) and a resist (13) coated thereon, the pattern (12a) is ) is exposed using an electron beam using a variable first slit (21) and a fixed second slit (22), and the resist other than the pattern (12) is removed by photolithography. A method for manufacturing a reticle characterized by the following.