JP3258213B2 - How to fix the pattern film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for correcting a pattern defect on a sample surface, and more particularly to a method for correcting a pattern film using a focused ion beam.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a method of selectively depositing a thin film by irradiating an ion beam as a method of correcting a pattern defect in a mask (or a reticle) used in a manufacturing process of a semiconductor integrated circuit. in this way,
After scanning the ion beam on the sample surface and imaging the pattern including the pattern missing part to be corrected, the ion beam is scanned while supplying the compound vapor to the area containing the pattern missing part to be corrected confirmed by the imaging process. Irradiation deposits a compound film and corrects the pattern.

By the way, as the wavelength of a stepper light source is shortened and the phase shift mask is introduced with the aim of improving the resolution in optical lithography, the ion beam is scanned on the sample surface and corrected by the above-described method. Ions remaining in the sample substrate when a pattern including a pattern lacking part to be imaged is becoming a problem. This is because ions remain in the substrate to cause a decrease in light transmittance.

For example, for DUV light, 10 ¹⁶ ions / cm
^At an ion dose of ^2, a drop in transmittance of about 10% occurs.
When such a decrease occurs, the pattern transferred from the mask causes a dimensional change, and even after the correction of the pattern film is completed, the imaging region becomes a new defect. Therefore, there is a need for a means capable of imaging a pattern film including a minute portion to be corrected at a lower dose. However, when imaging at a low dose, there is a problem that the resolution generally decreases, and a solution to the problem is desired.

According to the experiments of the present inventors, while supplying a compound vapor to a region imaged at a low dose, an ion beam is scanned and irradiated on a region including a pattern missing portion to be corrected, which is confirmed by imaging. When a compound film is to be deposited, the cross-sectional side wall angle of the deposited film is slower than that of a film deposited after imaging at a conventional high dose, and the edge tends to blur. found. The lack of sharpness in the edge profile is equivalent to a decrease in correction accuracy.Therefore, even when correcting a pattern film in an area imaged at a low dose, the conventional deposition shape can be secured and corrected. A method is desired.

[0006]

As described above, a mask is modified by a method of irradiating a predetermined position of a sample with an ion beam in an atmosphere where a compound vapor is present, depositing a compound film at the irradiated position and modifying a pattern. In such a case, it is desirable to keep the dose of ions irradiated to the mask at the time of imaging low. However, the profile of a film deposited on a low-dose substrate is not preferable, and the correction accuracy has been reduced in spite of a short wavelength mask that requires higher correction accuracy. In addition, the above problem is not limited to the correction of the pattern missing part, but can be similarly applied to the correction of the pattern surplus part.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to secure the transmittance of a substrate required for low-dose imaging while maintaining the profile of a compound film at a portion to be corrected. Another object of the present invention is to provide a method of correcting a pattern film in which a removal profile of a surplus portion is sharpened and the correction accuracy can be secured.

[0008]

[Means for Solving the Problems]

(Summary) In order to solve the above problems, the present invention employs the following configuration.

That is, according to the present invention (claim 1), in a method of correcting a pattern defect on a sample surface on which a thin film of a predetermined pattern is formed, a focused ion beam is scanned and corrected on the sample surface. A first step of imaging a pattern including a minute part to be corrected, a second step of implanting a focused ion beam into the minute part to be corrected identified in the first step, and ions formed by the second step A third step of performing fine processing by spraying a compound vapor onto a region including at least the implantation region.

Here, preferred embodiments of the present invention include the following. (1) The minute portion to be corrected is a pattern missing portion, and a compound film is deposited on the pattern missing portion in the third step. (2) The minute part to be corrected is a pattern surplus part, and the pattern surplus part is removed in the third step. (3) The ion beam scanning for imaging is performed at a low dose, and the ion beam implantation for fine processing is performed at a high dose. (4) In the third step, a compound vapor is sprayed on at least an ion implantation region and an ion beam is irradiated. (Operation) According to the present invention, in the first step of scanning a focused ion beam on a sample surface to image a pattern film including a minute portion to be corrected, ions implanted into the sample are suppressed to a low dose. A second step of implanting a focused ion beam into the minute part to be corrected confirmed in the first step is provided. In this manner, the compound shape is supplied to the minute portion to be corrected in the subsequent third step (by irradiating a focused ion beam at the same time as necessary) to perform the fine processing, thereby sharpening the processing shape of the minute portion to be corrected. Can be

More specifically, in the case where a pattern is missing, an edge profile of the compound film is sharpened in a step of scanning and irradiating an ion beam on a pattern missing portion to be corrected while supplying compound vapor to deposit a compound film. It is possible to prevent the correction accuracy from lowering. In addition, in the case of pattern surplus, in the step of scanning and irradiating an ion beam on the pattern surplus part to be corrected while supplying compound vapor, the removal profile of the pattern surplus part is sharpened, and the correction accuracy is reduced. Can be prevented.

As a result, it is possible to correct the pattern film with sharpness of the profile of the deposited film or the removal profile of the pattern surplus portion at the portion to be corrected, without reducing the transmittance of the substrate due to imaging. Become.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. However, needless to say, the present invention is not limited to the following embodiments.

FIG. 1 is a schematic configuration diagram showing a mask pattern correcting apparatus used in one embodiment of the present invention. In the figure, 1 is a gallium ion source, 2 is a magnifying lens, 3 is a deflector, 4 is an objective lens, 5 is an ion beam column including 1-4, 6
Is a charge nutrizer, 7 is a secondary particle detector, 8
Is a mask (sample), 9 is a sample stage, 10 is a chamber containing 6-9, 11 is an exhaust port for exhausting the inside of the ion beam column 5 or the chamber 10, 12 is a gas cylinder, 13 is a pressure gauge, 14 Is a pressure regulating valve, 15 is a gas outlet, and 16 is a gas outlet drive mechanism.

The ion beam column 5 is provided in the upper part of the chamber 10, and the ions emitted from the ion source 1 are focused on the surface of the mask 8 by the electronic optical components 2 to 4.

The mask pattern correcting apparatus having such a structure blows gas from the gas cylinder 12 onto the mask 8 and irradiates the part with an ion beam to remove a part of the mask sample by gas assisted etching or deposition. Or to partially modify the mask sample by depositing a film.

Next, a method of correcting a mask pattern (a method of correcting a missing portion) using the apparatus having the above configuration will be described with reference to FIGS.

For example, it is assumed that correction is performed on a halftone type phase shift mask of a model having a phase shift section 22 and a light transmission section 23 as schematically shown in a cross section in FIG. . As shown in FIG. 2A, the entire surface of the mask is irradiated with an ion beam 25 by scanning with an ion beam 25 as schematically shown by an arrow A. At this time, secondary particles 26 generated from the mask surface are detected. , It is detected whether or not the phase shift unit exists at the designed position. This is performed by utilizing the fact that the secondary particles 26 generated by the irradiation of the ion beam 25 differ depending on the irradiated material.

In the example of FIG. 2A, the portion indicated by reference numeral 24 is a missing portion, and this is detected. In addition,
Means for imaging a pattern film including a minute portion to be corrected at a low dose may be as follows.

The surface of the mask is two-dimensionally irradiated with a particle beam for imaging at a low dose, and the planar intensity distribution of secondary particles emitted from the mask surface by the irradiation of the particle beam is detected. A new planar intensity distribution is created by performing a smoothing process on the planar intensity distribution of the secondary particles. Then, a predetermined threshold value is set for the created new plane intensity distribution and binarized or multi-valued to recognize a defective portion. As a result, noise can be effectively removed, and defects can be accurately recognized.

Further, if a region including a desired processing region is set using the newly created planar intensity distribution of secondary particles and the beam irradiation region is determined, the desired region can be set more accurately. And can be processed. In particular, by performing a smoothing process as an image processing process, noise on a signal can be removed even when the contrast between the substrate and a film formed on the substrate is low, so that a difference in material can be reliably determined. Become.

Next, an ion beam 25 is implanted into a region including the missing portion 24 to be corrected, which has been confirmed in the above-described steps. As shown in FIG. 2A, a region to be irradiated with the ion beam with respect to the image shown on the CRT screen is
For example, the frame 27 is designated by a setting method using a cursor. Then, only the inside of the frame 27 is scanned and irradiated with the ion beam 25 to form a region 28 in which a desired dose is implanted in the frame 27, and the ion implantation amount is made higher than the surrounding imaging region (FIG. 3). (A)). Finally, the compound film 30 is deposited on the missing portion 24 while supplying the compound vapor 29 (FIG. 3B).

Here, the region where the compound film 30 is deposited is within the frame 27 designated by the setting method using the cursor, that is, the region 28 where the ion implantation amount is increased. However, when the edge of the phase shift portion exists at the edge of the phase shift portion as in the above-described missing portion 24, the position at which the edge of the compound film is required to be sharp is the 27a portion. 27b, c and d have no significant meaning. Depending on the situation, other than 27a may be appropriately determined.

After the region for depositing the compound film has been finally determined, the compound vapor 29 is blown out from the gas cylinder 12 onto the mask 8, and the portion is irradiated with the ion beam 25. The compound film 30 is deposited in the missing portion specified by the above to correct the pattern of the mask.

When the correction is performed in this manner, the edge profile of the compound film at the portion 27a where the correction accuracy is a problem becomes extremely sharp (the inclination angle is close to 90 °, and the edge is straight without unevenness).

FIG. 4 shows a dimensional SEM photograph of a compound film deposited on a mask substrate having a different ion dose amount implanted from directly above. FIG. 4A shows a low dose substrate (5 × 10 ¹⁴ ions / cm ² ), and FIG. 4B shows a high dose substrate (2 × 10 ¹⁵ ions / cm ² ).

The dimension SEM is an apparatus for controlling dimensions such as a pattern width. In dimension SEM, edges are recognized by utilizing the fact that secondary electrons generated when a low-acceleration electron beam is irradiated onto a sample are generated in large quantities from places where the shape changes sharply, and the distance between edges is accurately determined. To be measured.
The uneven waveform in the center of each photograph in FIG. 4 is a secondary electron signal obtained when scanning across the compound film on the mask substrate, and two short straight lines (edge bars) near the secondary electron signal are determined from the waveform. FIG.

Comparing the secondary electron signals, (b) has a sharper peak, and it is expected that the deposited compound film has a steep edge. This can be easily inferred from the edge contrast of the compound film in the photograph. That is,
In (b), two clear and thin white lines can be observed, while in (a), two lines that appear to be significantly blurred are observed.
The book is finally observable.

When comparing the edge positions determined by the apparatus, (a) and (b) show that the compound films having the same width are deposited in both cases, but in (b) there is an edge bar immediately beside the thin white line. On the other hand, in (a), it is presumed that there is an edge bar in a considerably wide place and the edge is considerably blurred. Although it is not a quantitative evaluation from these facts, it can be determined that a deposited film having a better edge profile can be formed on a high dose substrate than on a low dose substrate.

As described above, the imaging of the pattern lacking portion is performed at a low dose, and ions are implanted only where the compound film is to be deposited to form a high dose region, so that the transmittance of the mask substrate due to the imaging is inadvertently reduced. Without this, it is possible to sharpen the profile of the deposited film with respect to the portion to be repaired, and to repair the pattern film while ensuring repair accuracy.

The present invention is not limited to the above embodiment. In the embodiment, the case where the compound film is deposited on the pattern missing portion has been described. However, it has been confirmed that, even when the excess portion is removed by scanning and irradiating a beam while spraying a compound vapor on the excess portion of the pattern, it is preferable to implant ions in a region to be removed in advance to obtain a processed shape.

In short, the present invention provides a first step of imaging a pattern film including a minute part to be corrected by scanning an ion beam on a sample surface, and a minute part or a minute part to be corrected identified in the first step. Most preferably, it comprises a second step of implanting an ion beam only in a region including a minute portion, and a third step of finely processing a region partially or wholly including the ion implanted region formed in the second step. It is important. If this point is held down, the present invention can be applied according to various specifications.

The present invention can be applied not only to repair of a mask but also to defect repair of various patterns of a semiconductor device. In addition, various modifications can be made without departing from the scope of the present invention.

[0034]

As described above in detail, according to the present invention, a focused ion beam is scanned on a sample surface to image a pattern including a minute portion to be corrected, and the minute portion to be corrected confirmed by this is imaged. A focused ion beam is implanted into the region, and compound vapor is sprayed onto a region including at least the ion implanted region to perform fine processing. It is possible to realize a method of correcting a pattern film in which a profile or a removal profile of a surplus portion is sharpened and correction accuracy can be secured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a mask pattern correcting apparatus used in an embodiment of the present invention.

FIG. 2 is a diagram showing details of a mask repair method according to the embodiment of the present invention.

FIG. 3 is a diagram showing details of a mask correcting method according to an embodiment of the present invention.

FIG. 4 is a dimensional SEM photograph showing the shape of a compound film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Gallium ion source 2 ... Expansion lens 3 ... Deflector 4 ... Objective lens 5 ... Ion beam column 6 ... Charge nutrizer 7 ... Secondary particle detector 8 ... Mask (sample) 9 ... Sample stage 10 ... Chamber 11 ... Exhaust Mouth 12 ... Gas cylinder 13 ... Pressure gauge 14 ... Pressure regulating valve 15 ... Gas blowing port 16 ... Gas blowing drive mechanism 22 ... Phase shift section 23 ... Light transmitting section 24 ... Pattern missing section 25 ... Ion beam 26 ... Secondary particles 27 ... Frame 28 ... Ion implantation region 29 ... Compound vapor 30 ... Compound film

Continuation of the front page (56) References JP-A-1-130158 (JP, A) JP-A-3-231749 (JP, A) JP-A-5-241328 (JP, A) JP-A-59-129423 (JP) JP-A-64-64545 (JP, A) JP-A-5-341500 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1/08 H01L 21/205

Claims (3)

(57) [Claims] 1. A method of repairing a pattern film on a sample surface on which a thin film of a predetermined pattern is formed, wherein a focused ion beam is scanned on the sample surface to image a pattern including a minute portion to be repaired. A first step of implanting, a second step of implanting a focused ion beam into the minute portion to be corrected identified in the first step, and a compound vapor in an area including at least the ion implantation area formed by the second step. And a third step of performing fine processing by spraying. 2. The method according to claim 1, wherein the scanning of the ion beam for the imaging is performed at a low dose, and the ion beam implantation for the fine processing is performed at a high dose. . 3. The method according to claim 1, wherein in the third step, a compound vapor is blown onto an area including at least the ion implantation area and an ion beam is irradiated.