JP2610456B2 - Pattern film correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to irradiating a predetermined portion of a patterned thin film formed on a sample surface while scanning a focused ion beam and scanning a halogen gas or a halogenated xenon gas (hereinafter, referred to as a xenon gas). (Hereinafter simply referred to as a halogen gas) is locally sprayed onto the portion to efficiently and cleanly remove a predetermined portion of the patterned thin film.

[Summary of the Invention]

The present invention is to repeatedly scan and irradiate a focused ion beam onto a predetermined portion of a metal or metal oxide patterned thin film formed on a sample surface and locally blow a halogen gas on the portion to form a patterned thin film. In the method of removing a predetermined portion, the secondary ion intensity of a metal element generated from the pattern film during the removal of the pattern film is measured, and the pattern removal is terminated by a change in the intensity.

[Conventional technology]

Conventionally, a method and an apparatus for partially removing a pattern film formed on the surface of a substrate as a sample and correcting a pattern are disclosed in JP-A-58-196020. It has been known to repeatedly scan a narrowly focused ion beam and remove that portion by sputtering.

Generally, the ion beam used here uses gallium liquid ions, indium liquid ions, or metal ions from a gold-silicon-beryllium eutectic alloy ion source or the like, and the sample is placed on a substrate. A photomask or reticle (hereinafter, simply referred to as a mask) for manufacturing a semiconductor on which a patterned thin film is formed. The modification of the pattern film is terminated when a predetermined portion of the pattern material is removed and the glass substrate is exposed on the surface. At this time, the change in the secondary ionic strength of the metal of the pattern film and the component of the glass substrate are The end (hereinafter, referred to as an end point) was determined by observing the change in the secondary ion intensity of silicon.

[Problems to be solved by the invention]

However, according to the conventional method, as shown in FIG.
In the case of the sample on which the chromium pattern film 52 is formed, the temporal change in the intensity of the secondary ions of chromium and silicon generated by the irradiation of the focused ion beam occurs.
The edge portion 52a of the pattern film 52 and the inner portion 52b of the pattern film 52 are different from each other as shown in FIGS. That is, in the interior 52b, the chromium ion intensity has two peaks at the surface of the chromium pattern film 52 and at the interface between the chromium film and the glass substrate 51, and the silicon ion intensity rises at the second peak of the chromium ion. It rises at the same time as the curve, and has a saturated intensity 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, in the edge portion 52a, the chromium ion intensity has one peak and the width of the peak is wide, and the silicon ion intensity has some intensity from the beginning, and the detection intensity increases at the same time as the chromium ion intensity decreases. Since the initial silicon ion intensity is an 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.

[Means for solving the problem]

In order to solve the above-mentioned drawbacks, the present invention repeatedly irradiates a predetermined portion of a pattern film formed on a sample surface with a focused ion beam while scanning the same, and simultaneously blows a halogen gas locally to the irradiation position, thereby forming a pattern. The correction of the pattern film is terminated based on the change of the secondary ion intensity of the metal element forming the film or the total secondary ion intensity.
The end point can be determined by one type of ion mass analyzer or a simple total ion detector.

[Action]

By repeatedly irradiating a predetermined portion of the pattern film formed on the sample surface with a focused ion beam made of metal ions while scanning, the ion beam irradiated 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. Also, the ionization rate of the element itself,
Since the sputtering rates are different, the endpoint can also be obtained by measuring the total ion intensity (amount).

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the entire pattern film repair apparatus according to the present invention. An ion beam extracted from an extraction electrode (not shown) from the ion source 1 located above the chamber 21 becomes a focused ion beam 4 having a submicron diameter by the ion lens system of the focusing lens 2 and the objective lens 3, and the surface of the sample 5. Illuminate 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. The sample 5 is mounted on an XY stage 8 for holding the sample 5 and moving it on the XY plane. Note that the XY stage 8 can also be configured to be movable in the Z direction.

A halogen gas blowing device 11 for blowing a halogen gas to the irradiation position of the focused ion beam 4 on the sample is provided in the chamber 21. The halogen gas spraying device 11 is provided with a nozzle 13 for spraying a halogen gas from a gas supply source 12 locally on the sample surface, and a valve 14 for turning on and off the halogen gas spray. The attachment device 11 is provided with an air cylinder 15 for moving the nozzle 13 closer to or away from the spray position on the sample 5. Valve 14 and air cylinder 15
Is 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 detected by a secondary ion detector 23 directed to the surface of the sample 5.

Further, the signal from the secondary ion detector 23 is output to the arithmetic circuit 24
And the signal of the scanning circuit 7 is also taken in.
By synchronizing the signal intensity from the secondary ion detector 23 with the signal of the scanning circuit 7, the image shape of the pattern shape is displayed on the image display device 25.

In the irradiation path of the focused ion beam, a focused ion beam 4
A blanking electrode 25 for largely bending the beam is arranged so that the beam does not irradiate the surface of the sample 5, and is electrically driven by a blanking circuit 26. The scanning range setting unit 27 focuses only a predetermined portion of the surface of the sample 5 on the focused ion beam 4.
The scanning range set by the scanning range setting unit 27 is achieved by controlling the blanking circuit 26 and the scanning control circuit 7.

Next, the process of correcting the pattern film will be described. A sample 5 having a chromium film pattern formed on a glass substrate whose pattern film is to be corrected is inserted into a chamber 21 whose inside is maintained in a vacuum by a vacuum pump 20. The XY stage 8 is driven such that the position of the sample 5 whose correction position is known in advance is approximately at the center of the scanning range of the focused ion beam 4. An address is set at the position of the correction portion, and this address is input to an XY storage driving device (not shown) for driving the XY storage 8, whereby the correction portion of the sample 5 is automatically adjusted to the position of the focused ion beam 4. The XY stage 8 is driven to be substantially at the center of the scanning range.

Here, the focused ion beam 4 is scanned over the surface of the sample 5, and the secondary ions 22 generated thereby are detected by mass separation with a secondary ion detector, and the pattern shape of the pattern film formed on the surface of the sample 5 is detected. Is displayed on the image display device 25. When the position of the correction portion is at the end or off the display of the image display device 25, the XY storage 8 is driven again so that the position of the correction portion is substantially at the center of the scanning range of the focused ion beam 4. I do. The scanning of the focused ion beam 4 on the surface of the sample 5 is stopped once to several times in order to display the pattern shape of the pattern film formed on the surface of the sample 5 on the image display device 25. The information is stored in a storage device (not shown) of the display device, and can be always or whenever necessary.

When the pattern shape of the correction portion is displayed substantially at the center of the display of the image display device 25, the correction range of the pattern is input to the scanning range setting unit 27, and the scanning range setting unit 27
A signal is output to a blanking electrode 25 following the scanning electrode 26 and a scanning electrode 6 following the scanning circuit 7, and the focused ion beam 4 is supplied to the sample 5.
Only the correction range of the surface pattern 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 supplies the halogen gas 50 locally to the corrected portion of the pattern of the sample 5. Is blown away. The halogen gas 50 is a gas such as chlorine gas, iodine gas, or xenon fluoride depending on the material of the pattern film and the material of the substrate of the sample.

Since the secondary ions generated by the irradiation of the focused ion beam 4 are uniquely determined by the element content of the irradiated part, the secondary ion intensity of chromium, which is an element constituting the pattern film, is measured. It can be determined whether the film has been removed. As shown in FIG. 5 showing the change of the secondary ion intensity of chromium, the edge 52 of the pattern film 52
The change in the secondary ion intensity of chromium from a has the same tendency as that from the inside 52b, and there is almost no change between the pattern films 52. This is because the secondary ion yield increased due to the presence of the halogen gas. For example, the chromium ion intensity (amount) due to the presence of chlorine gas, regardless of whether the sample surface is chromium or chromium oxide, is the chromium ion intensity (amount) from the chromium oxide surface when no chlorine gas is present.
About twice as large as At the interface between the pattern film 52 and the substrate 51, the secondary ion intensity of chromium rapidly decreases. In other words, when the secondary ions of chromium are no longer detected, the correction of the pattern film is terminated, so that the chromium film is not clean.
In addition, the pattern film 52 is hardly roughened on the surface of the substrate glass.
Can be removed.

In another embodiment, the total secondary ion intensity on the pattern film and the total secondary ion intensity on the glass substrate are obtained in advance, and the secondary ion intensity detected during correction of the pattern film is determined on the glass substrate. The endpoint is determined when the total secondary ionic strength reaches.

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. .

〔The invention's effect〕

A focused ion beam is repeatedly irradiated to a predetermined portion of the pattern film, and an etching gas is locally blown to the portion. The pattern film is etched away, and the chemically removed pattern film material is vaporized. Removed material is removed without reattaching. 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 correcting apparatus, FIG. 2 is a plan view showing a surface pattern of a sample, FIG. 3 is a view showing a change in pattern material detection intensity inside the pattern, and FIG. FIG. 5 is a diagram showing a change in pattern material detection intensity at a portion, and FIG. 5 is a diagram showing a change in pattern material detection intensity when a halogen gas is blown. DESCRIPTION OF SYMBOLS 1 ... Ion source, 2 ... Focusing lens 3 ... Objective lens 4, ... Focused ion beam 5 ... Sample, 11 ... Halogen gas spray device 13 ... Nozzle

Claims (7)

(57) [Claims] 1. A method for irradiating a focused ion beam on a desired area of a pattern film formed on the surface of a substrate in a vacuum vessel while repeatedly scanning the same, and locally applying a halogen gas or a xenon halide gas to the desired area. In a pattern film correcting method for correcting a pattern film by spraying to remove the pattern film in the desired range, the pattern film is formed based on a change in secondary ion intensity of a component constituting the pattern film generated from the desired range. A method for correcting a pattern film, which comprises ending the removal. 2. The method according to claim 1, wherein the pattern film is a chromium film, and the pattern film removal is terminated based on a change in the secondary ion intensity of chromium. 3. The method according to claim 1, wherein the pattern film is chromium oxide, and the pattern film removal is terminated based on a change in secondary ion intensity of chromium. 4. The method according to claim 1, wherein the pattern comprises two layers of a chromium film and a chromium oxide film, and the pattern film removal is terminated based on a change in the secondary ion intensity of chromium. 5. The substrate according to claim 1, wherein said substrate is an integrated circuit substrate.
The pattern film correction method according to the above. 6. The method according to claim 1, wherein said halogen gas is chlorine gas. 7. The method according to claim 1, wherein the xenon halide gas is a xenon fluoride gas.