JPH01107257A - Correcting device for mask pattern - Google Patents

Abstract

PURPOSE:To reduce the quantity of ion beam irradiation required to correct a mask defect by arranging a mask substrate slantingly to the incidence direction of an ion beam. CONSTITUTION:The mask substrate 7 is arranged rotatably, so the incidence direction of the ion beam 6 to the mask substrate 7 is changeable. For the purpose, the incidence angle of the ion beam 6 is changed to increase the etching speed of a thin film constituting a mask pattern without increasing the quantity of ion irradiation. Consequently, the mask pattern can be corrected with the small quantity of ion irradiation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mask pattern correction apparatus, and more particularly to a mask pattern correction apparatus using a focused ion beam.

[Prior Art] In recent years, with the progress in the integration of semiconductor devices, it has become necessary to manufacture mask patterns with a line width of several microns. At the same time, there is a need for a mask pattern repair apparatus that can completely and accurately repair defects that occur during the production of such fine patterns.

2. Description of the Related Art In the manufacturing process of semiconductor integrated circuits, when a pattern is transferred to a semiconductor wafer, a mask is required to selectively block the light used for the transfer. This mask is usually produced through the following steps.

First, chromium (
After forming a thin film of Cr) or molybdenum silicide (MoSi), an electron beam resist is applied over the entire surface.

Thereafter, a resist pattern is produced by drawing and developing a pattern on this electron beam resist coating film using an electron beam exposure device. A mask is fabricated by etching a thin film of chromium or molybdenum silicide using this resist pattern as a mask.

However, in this mask manufacturing process, two types of defects, ``white defects'' and ``black defects'', as described below, occur due to factors such as adhesion of dust.

Figures 3A, 3B, 4A, and 4B show examples of various defects. In the figure, the shaded areas are areas to which chromium or molybdenum is attached. iBA diagram,
Defect 8.9 shown in FIG. 3B is a type of defect in which a thin film of chromium or molybdenum silicide that should block light is missing, and is called a "white defect." Figure 4A, Figure 4B
Defects 10 and 11 shown in the figure are a type of defect in which excess chromium or molybdenum silicide is attached to a portion that should transmit light, and is called a "black defect."

Also, these defects are isolated from the pattern.

Defects are classified into defects that involve the edges of the pattern and defects that involve the edges of the pattern. That is, defect 8 in FIG. 3A is a pattern isolated white defect, defect 9 in FIG. 3B is a pattern edge white defect, and defect 4 is a pattern edge white defect.
Defect 10 in Figure A is a pattern isolated black defect, and defect 11 in Figure 4B is a pattern edge black defect.

Among the above-mentioned defects, a conventional method for repairing "black defects" is to irradiate the black defects with an argon (A) laser beam, and the heat of the laser beam causes the black defects.
A method is used to remove excess chromium and molybdenum silicide by melting and evaporating them. However, according to this method, it is difficult to focus the laser narrowly and scan accurately.
Although it is possible to correct a pattern isolated black defect 10 as shown in FIG. 4A, it is difficult to accurately correct a pattern edge black defect 11 as shown in FIG. 4B.

In recent years, ions such as gallium (Ga) have been
A focused ion beam device has been developed that can focus an ion beam to about m and scan it. This focused ion beam can have a smaller beam diameter than a laser beam, and also has superior controllability of the irradiation beam position.

By irradiating this focused ion beam to the defect,
Attempts have been made to remove the chromium and molybdenum silicide constituting the black defects by etching them by sputtering.

A conventional mask pattern correction apparatus using a focused ion beam as described above is constructed as shown in FIG.

This device includes an ion gun 1 that generates ions, a blanking device 2 that controls irradiation/non-irradiation of ions emitted from the ion gun 1, and a focusing lens 3 that focuses the ions. The focused ion beam is deflected by a beam deflector 4. This beam deflector 4
is controlled by pattern generator 5. The focused ion beam 6 is deflected by a beam deflector 4 to scan over a mask substrate 7 to be modified.

Using the apparatus configured in this way, the focused ion beam 6 is irradiated perpendicularly to the surface of the mask substrate 7. The black defect portion irradiated with the focused ion beam 6 is repaired by sputtering and removing the chromium and molybdenum silicide constituting the defect. Therefore, according to this apparatus, the focused ion beam can be narrowed and the controllability is excellent, so that it is also possible to correct pattern edge black defects 11 as shown in FIG. 4B.

[Problems to be Solved by the Invention] However, when fine mask patterns are corrected using a focused ion beam using the above-mentioned apparatus, it is difficult to completely remove chromium and molybdenum silicide that constitute black defects. requires a large amount of gallium ions to be irradiated onto the mask substrate. As a result, a portion of it will be implanted into the quartz glass substrate that is the mask substrate.

The implanted gallium ions lowered the transmittance of the quartz glass and caused defects called gallium stains.

Therefore, this invention was made to solve the above-mentioned problems, and it is possible to perform fine mask pattern correction using a focused ion beam, and also suppress the generation of gallium stain due to ion irradiation. An object of the present invention is to obtain a mask pattern correction device that can correct a mask pattern.

[Means for Solving the Problems] A mask pattern correction apparatus according to the present invention includes the following means.

(a) Means for generating ions.

(b) Means for focusing the ions.

(C) Means for controlling the deflection of the focused ion beam.

(d) Means for rotatably arranging said mask substrate so that the angle of incidence of the ion beam on the surface of the mask substrate having the mask pattern to be modified can be varied.

[Operation] In the mask pattern correction device using a focused ion beam according to the present invention, the mask substrate is rotatably arranged, so that the direction of incidence of the ion beam on the mask substrate can be changed. Therefore, by changing the incident angle of the ion beam, it is possible to increase the etching rate for the thin film forming the mask pattern without increasing the amount of ion irradiation. Therefore, the mask pattern can be corrected with a smaller amount of ion irradiation.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic configuration diagram of a mask pattern correction apparatus according to the present invention.

In the figure, this device includes an ion gun 1 that generates ions.
, a blanking device 2 for controlling irradiation/non-irradiation emitted from the ion gun 1, and a focusing lens 3 for focusing the ions, and the focused ion beam is deflected by a beam deflector 4. It will be done. pattern generator 5
is provided to control the beam deflector 4. The focused ion beam 6 is deflected by a beam deflector 4 to scan over a mask substrate 7 to be modified. The mask substrate 7 is installed by a tilting table 7a so that it can be inclined at a predetermined angle with respect to the direction of incidence of the focused ion beam 6.

Using the above-mentioned device, the mask pattern can be corrected by
As in the conventional example, the chromium and molybdenum silicide constituting the defects are sputter-etched and removed by the focused ion beam 6 incident on the mask substrate 7.

The number of molecules ejected from the target per incident ion is defined as the sputtering rate.

It is recognized that this sputtering rate is dependent on the angle of incidence of incident ions on the target. Figure 5 shows, as an example, when sputtering copper (Cu) with argon (Ar) ions as a target.
The dependence of the sputtering rate on the ion incidence angle (Kame Kanehara, "Sputtering Phenomenon", University of Tokyo Press, p. 26) is shown.

In the figure, the horizontal axis shows the ion incident angle (°), and the vertical axis shows the sputtering ratio (S (θ)/S (
0): θ indicates the ion incidence angle (°). Here, the angle of incidence is defined as the angle between the normal to the target surface and the direction of incidence. According to this figure, the sputtering rate has a maximum value when the ion incidence angle is around 60 to 70 degrees, and has a value that is 2 to 3 times that in the case of normal incidence (the incidence angle is O'').

Such dependence of the sputtering rate on the ion incidence angle is a phenomenon observed not only in argon ions but also in other ion beams.

By utilizing the above phenomenon, when removing chromium or molybdenum silicide constituting black defects on a mask pattern using an apparatus configured according to the present invention, the required amount of incident ion beam can be reduced compared to conventional vertical incidence. can be reduced compared to Preferably, by varying the angle of incidence within the range of 0 to 70 degrees, it is possible to reduce the required amount of incident ion beam by one-half to one-third compared to conventional normal incidence. In this way, it is possible to suppress the occurrence of gallium stain, which has been a problem in conventional mask pattern correction devices using focused ion beams. Note that the ion beam used in the mask pattern correction apparatus of the present invention is not limited to gallium ions.

[Effects of the Invention] As described above, according to the present invention, mask defects can be fixed by connecting to a mask pattern correction device using a focused ion beam and arranging the mask substrate at an angle with respect to the incident direction of the ion beam. Since the amount of ion beam irradiation required for correction can be reduced, the time required for correction can be shortened. In addition, it is possible to suppress the generation of gallium stain, which becomes a defect after irradiation.
This has the effect of making it possible to repair small defects with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a mask pattern correction device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of a conventional mask pattern correction device, and FIGS. 3A, 3B, 4A, and FIG. 4B is a partial plan view showing various defects that occur during mask pattern fabrication, and FIG. 5 is a relationship diagram showing the relationship between the sputtering ratio and the ion incidence angle in sputtering/soching. In the figure, 1 is an ion gun, 2 is a blanking device, and 3
4 is a focusing lens, 4 is a beam deflector, 5 is a pattern generator, 6 is a focused ion beam, 7 is a mask substrate, and 7a is a tilt table. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A mask pattern correction device using a focused ion beam, comprising: means for generating ions; means for focusing the ions; means for controlling deflection of the focused ion beam; A mask pattern correction apparatus comprising: means for rotatably arranging the mask substrate so that the incident angle of the ion beam with respect to a mask substrate surface having a mask pattern can be changed. (2) The mask pattern correction apparatus according to claim 1, wherein the incident angle can be changed within a range of at least 0 to 70 degrees. (3) The mask pattern correction device according to claim 1 or 2, wherein the ions are gallium ions.