JPH09134000A - Pattern film correcting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to efficiently and cleaning remove the prescribed part of the patterned thin films formed on a sample surface by irradiating the prescribed part of the patterned thin films with a convergent ion beam while scanning this part and locally blowing gaseous halogen to these parts. SOLUTION: A device 11 for blowing the gaseous halogen for spraying the gaseous halogen to the position on the sample 5 to be irradiated with the convergent ion beam 4 is installed in a chamber 21. This device 11 for blowing the gaseous halogen is provided with a nozzle 13 for blowing the gaseous halogen from a gas supplying source 13 to the local point of the sample surface and a valve 14 for turning the blowing of the gaseous halogen on and off. The secondary ions 22 generated from the sample 5 surface by the convergent ion beam 4 with which the surface of the sample 5 is irradiated under scanning are detected by a secondary ion detector 23 directed to the sample 5 surface. The correction of the pattern films is ended by the change in the total secondary ion intensity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a predetermined portion of a patterned thin film formed on the surface of a sample while scanning with a focused ion beam, and a halogen gas or a halogenated xenon gas (hereinafter simply referred to as a halogen gas). The present invention relates to a method for efficiently and cleanly removing a predetermined part of a patterned thin film by locally spraying the part on the part. Then, the present invention provides that a predetermined portion of the patterned thin film of metal or metal oxide formed on the sample surface is repeatedly scan-irradiated with a focused ion beam and a halogen gas is locally blown to the portion to form a patterned film. In the method of removing a predetermined portion of a thin film, the secondary ion intensity of the metal element generated from the pattern film during the removal of the pattern film is measured,
This is a method of ending the pattern removal according to the intensity change.

[0002]

2. Description of the Related Art Conventionally, a method and apparatus for partially removing a pattern film formed on the surface of a substrate, which is a sample, to correct the pattern is disclosed in JP-A-58-196020. It has been known that a focused ion beam that is narrowed down is repeatedly scanned on a desired portion and that portion is removed by sputtering. Generally, the ion beam used here uses metal ions such as gallium liquid ion, indium liquid ion or gold-silicon eutectic alloy ion source or gold-silicon-beryllium eutectic alloy ion source, and the sample is patterned on the substrate. It is a photomask or a reticle (hereinafter simply referred to as a mask) for semiconductor production in which a thin film is formed.

The modification of the pattern film ends when the pattern material in a predetermined portion is removed and the glass, which is the substrate, appears on the surface. At this time, the change in the secondary ionic strength of the metal of the pattern film and the substrate. The end (hereinafter referred to as the end point) was determined by observing the change in the secondary ionic strength of silicon, which is a glass component.

[0004]

However, in the case of a sample according to the conventional method in which the chromium pattern film 52 is formed on the glass substrate 51 as shown in FIG. 2, it is possible to remove the chromium and silicon generated by the focused ion beam irradiation. The temporal change in the intensity of the secondary ions differs from the edge portion 52a of the pattern film 52 and the inside 52b of the pattern film 52 as shown in FIGS. 3 and 4. That is, in the inside 52b, the chrome ionic strength is determined by the chromium pattern film 52 surface portion, the chrome film and the glass substrate 5.
Peaks appear at two places on the interface of No. 1, and the silicon ion intensity rises at the same time as the rising curve of the second peak of chromium ions, and becomes the intensity saturated at the second peak of chromium ions. Such a change of chromium ions causes the ionization rate to increase due to the oxygen effect because chromium is oxidized on the surface and at the interface.

However, at the edge portion 52a, the peak of the chromium ion intensity is wide at one position, and the width of the silicon ion intensity has a certain degree from the beginning, and the detected intensity increases at the same time as the decrease of the chromium ion intensity. . Since the initial silicon ion intensity is at the edge, it is generated from the glass substrate 51 at the edge. As described above, two types of ions, silicon ions and chromium ions, must be detected, and the time when the chromium ion intensity decreases and the silicon ion intensity increases must be set as the end point. That is, two types of ions had to be detected.

[0006]

In order to solve the above problems, the present invention repeatedly irradiates a predetermined portion of a pattern film formed on a sample surface with a focused ion beam while scanning it, and at the same time, irradiates the irradiation position with a halogen. The gas is locally blown to finish the pattern film modification based on the change in the secondary ion intensity of the metal element forming the pattern film or the total secondary ion intensity. One type of ion mass analyzer or simple It becomes possible to judge the end point with a total ion detector.

By repeatedly irradiating a predetermined portion of the pattern film formed on the sample surface with a focused ion beam of metal ions while scanning, the ion beam irradiation portion of the pattern film is removed by sputter etching. Further, secondary particles generated from the sample by ion beam irradiation are ionized by simultaneously spraying a halogen gas having a high electronegativity locally onto the irradiation position, thereby increasing ion intensity. In other words, the ionic strength hardly changes due to the state of the metal element such as chromium (state of oxidation or the like), and changes almost linearly according to the amount of the metal element. That is, it is possible to determine whether the pattern film has been removed by measuring the intensity of only the secondary ions of the elements constituting the pattern film. Further, since the ionization rate and the sputter rate are different depending on the element itself, the endpoint can be obtained by measuring the total ion intensity (quantity).

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the entire pattern film repairing apparatus according to the present invention. The ion beam extracted from the ion source 1 above the chamber 21 from the extraction electrode (not shown) becomes a focused ion beam 4 of submicron diameter by the ion lens system of the focusing lens 2 and the objective lens 3, and the surface of the sample 5. Irradiate the top. In addition, a scanning electrode 6 is provided on the ion beam irradiation path to irradiate the focused ion beam 4 while scanning the surface of the sample while scanning.
The scanning electrode 6 is controlled by a scanning control circuit 7 for controlling the scanning of the focused ion beam. Sample 5 is sample 5
Is mounted on an XY stage 8 for holding and moving on the XY plane. The XY stage 8 can also be configured to be movable in the Z direction.

A chamber 21 is provided with a halogen gas blowing device 11 for blowing a halogen gas to the irradiation position of the focused ion beam 4 on the sample. The halogen gas blowing device 11 has a nozzle 13 for blowing the halogen gas from the gas supply source 12 locally on the sample surface,
A valve 14 for turning the halogen gas spray on and off is provided, and a halogen gas spray device 11 is also provided.
Is provided with an air cylinder 15 for moving the nozzle 13 closer to or farther from the spraying position on the sample 5. The valve 14 and the air cylinder 15 are controlled by the halogen gas control circuit 16.

Secondary ions 22 generated from the surface of the sample 5 by the focused ion beam 4 irradiating the surface of the sample 5 while scanning are directed to the surface of the sample 5 by the secondary ion detector 2
3 is detected. Further, the signal from the secondary ion detector 23 is introduced into the arithmetic circuit 24 and the scanning circuit 7
Of the secondary ion detector 23 and the signal intensity from the secondary ion detector 23 is synchronized with the signal of the scanning circuit 7, so that the pattern shape is displayed as an image on the image display device 25.

On the irradiation path of the focused ion beam, there is arranged a blanking electrode 30 for largely bending the beam so that the focused ion beam 4 does not irradiate the surface of the sample 5.
It is electrically driven by the blanking circuit 26. The scanning range setting unit 27 sets a focused ion beam scanning range in order to irradiate only a predetermined portion of the surface of the sample 5 with the focused ion beam 4. The scanning range set by the scanning range setting unit 27 is a blanking circuit. 26, by controlling the scan control circuit 7.

Next, the process of modifying the pattern film will be described.
A sample 5 having a chromium film pattern formed on a glass substrate for correcting the pattern film is inserted into a chamber 21 whose interior is maintained at a vacuum by a vacuum pump 20.
The XY stage 8 is driven so that the portion to be corrected of the sample 5 whose position to be corrected is known is located substantially in the center of the scanning range of the focused ion beam 4. By setting an address at the position of the correction point and inputting this address to an XY stage driving device (not shown) that drives the XY stage 8, the point where the sample 5 is corrected is automatically focused ion beam 4.
The XY stage 8 is driven so as to come to approximately the center of the scanning range.

Here, the focused ion beam 4 is scanned on the surface of the sample 5, and the secondary ions 22 generated thereby are mass-separated and detected by the secondary ion detector, and the pattern film formed on the surface of the sample 5 is detected. The pattern shape of the image display device 2
5 is displayed. When the position of the corrected portion is at the edge of the display of the image display device 25 or is off, the XY stage 8 is driven again so that the position of the corrected portion comes to approximately the center of the scanning range of the focused ion beam 4. To do. Sample 5
The scanning of the focused ion beam 4 on the surface of the sample 5 for displaying the pattern shape of the pattern film formed on the surface on the image display device 25 is stopped once to several times, and the pattern display is stored in the display device. It is stored in a device (not shown) so that it can be constantly or at any time.

When the pattern shape of the corrected portion is displayed in the approximate center of the display of the image display device 25, the scanning range setting unit 27
Then, the scanning range setting unit 27 outputs a signal to the blanking electrode 30 following the blanking circuit 26 and the scanning electrode 6 following the scanning circuit 7, so that the focused ion beam 4 is applied to the pattern on the surface of the sample 5. Only the correction range of is repeatedly scanned. At the same time, the valve 14 is opened by a signal from the halogen gas control circuit 16, the nozzle 13 is brought close to the sample surface by the air cylinder 15, and the halogen gas blowing device 11 locally supplies the halogen gas 50 to the portion where the pattern of the sample 5 is corrected. Be sprayed on. The halogen gas 50 is a gas such as chlorine gas, iodine gas, or halogen fluoride gas, although it depends on the material of the pattern film and the material of the sample substrate.

Since the secondary ions generated by the irradiation of the focused ion beam 4 are uniquely determined by the concentration of the element in the irradiated portion, the secondary ion intensity of chromium, which is an element forming the pattern film, is measured. By
It can be determined whether the film has been removed. As shown in FIG. 5 which shows the change in the secondary ion intensity of chromium, the change in the secondary ion intensity of chromium from the edge portion 52a of the pattern film 52 and the tendency from the inside 52b are almost the same.
During 2, it hardly changes. This is because the presence of halogen gas increased the yield of secondary ions. For example, due to the presence of chlorine gas, the chromium ion strength (quantity) is
Regardless of whether the sample surface is chromium oxide or chromium oxide, it is about twice the chromium ion intensity (amount) from the chromium oxide surface when chlorine gas is not present. Pattern film 52 and substrate 51
The secondary ionic strength of chromium sharply decreases at the interface.
That is, when the secondary ion of chromium is no longer detected, the pattern film 52 is removed without finishing the correction of the pattern film and the surface of the substrate glass is hardly roughened.

As another embodiment, a total of 2 on the pattern film is used.
The intensity of secondary ions (secondary ions of each ion species that are not mass separated) and the total secondary ion intensity on the glass substrate are obtained in advance, and the secondary ion intensity detected during the modification of the pattern film is measured on the glass substrate. It becomes the end point when the total secondary ionic strength of is reached. In the above, the mask which is a chromium pattern film formed on a glass substrate has been described. However, the same can be applied to an integrated circuit which is a metal pattern formed on a silicon substrate, as well as a multi-layer mask of chromium and chromium oxide. .

[0017]

EFFECTS OF THE INVENTION A predetermined portion of a pattern film is repeatedly irradiated with a focused ion beam, and an etching gas is locally blown to the portion. The pattern film is removed by etching, and the chemically removed pattern film material is vaporized. As a result, the removed material is neatly removed without reattaching to the periphery. In addition, since the secondary ion intensity can be efficiently detected, the endpoint can be accurately determined only by measuring the secondary ions of only the elements constituting the pattern film or by measuring the total secondary ion intensity. did it. That is, the configuration of the pattern film repair apparatus has been simplified and the cost has been reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the entire pattern film repairing apparatus.

FIG. 2 is a plan view showing a surface pattern of a sample.

FIG. 3 is a diagram showing changes in pattern material detection intensity inside a pattern.

FIG. 4 is a diagram showing a change in pattern material detection intensity at a pattern edge portion.

FIG. 5 is a diagram showing changes in pattern material detection intensity when a halogen gas is blown.

[Explanation of symbols]

 1 Ion source 2 Focusing lens 3 Objective lens 4 Focusing ion beam 5 Sample 11 Halogen gas 13 Nozzle spraying device

Claims (4)

[Claims] 1. A desired area of a pattern film formed on the surface of a substrate in a vacuum chamber is irradiated with a focused ion beam while repeatedly scanning, and a halogen gas or a halogenated xenon gas is locally applied to the desired area. In a pattern film repair method for repairing a pattern film by removing the pattern film in the desired range by spraying, the pattern film removal is completed based on a change in secondary ion intensity of total ions generated from the desired range. A method for repairing a patterned film, which comprises: 2. The pattern film repairing method according to claim 1, wherein the substrate is an integrated circuit substrate. 3. The pattern film repairing method according to claim 1, wherein the halogen gas is chlorine gas. 4. The pattern film repairing method according to claim 1, wherein the xenon halide gas is xenon fluoride gas.