JP3130310B2 - Pattern correction method and photomask manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern correction technique and a photomask manufacturing technique, and is particularly effective when applied to defect correction of a photomask used in a manufacturing process of a semiconductor integrated circuit device. Technology.

[Conventional technology]

Pattern defects of a photomask (reticle) used in the manufacturing process of a semiconductor integrated circuit device are roughly classified into black point defects (chrome remaining such as pin dots and projections) and white point defects (lack of patterns such as pin holes). . To correct black spot defects, FIB (Focused Ion Beam;
A method of irradiating a focused ion beam) to sputter-etch a defect is generally used. To correct a white spot defect, a thin film is deposited on the defect using a laser CVD method or an ion beam CVD method. The method is commonly used. The technology for repairing photomask defects is described in
It is described in -62733.

By the way, the method of correcting the black spot defect using the FIB is as follows.
Since high-energy ions are implanted into the photomask, there is a disadvantage in that after defect correction, the ion source metal remains in the glass substrate at the repaired portion and reduces the light transmittance of the photomask. Therefore, conventionally, after defect correction, the surface of the photomask is plasma-etched using an etching apparatus to remove the residual ion source metal in the glass substrate, thereby recovering the light transmittance.

[Problems to be solved by the invention]

However, in the above-described conventional technique of removing the ion source metal implanted in the glass substrate by plasma etching at the time of defect repair, the photomask is transported to the etching apparatus after the defect repair, and plasma etching is performed. Is reduced. Further, there is a problem that the step on the surface of the glass substrate formed by sputter etching using FIB is not sufficiently removed by plasma etching.

An object of the present invention is to provide a technique for improving the throughput of pattern defect correction.

Another object of the present invention is to provide a technique for improving the accuracy of pattern defect correction.

The above and other objects and novel features of the present invention are as follows.
It will be apparent from the description of this specification and the accompanying drawings.

[Means for solving the problem]

The outline of a typical invention among the inventions disclosed in the present application will be briefly described as follows.

One invention of the present application is to correct a pattern by irradiating a focused ion beam to a surface of a sample on which a predetermined pattern is formed, reduce the acceleration voltage of the focused ion beam immediately before etching an undersubstrate, and apply the focused ion beam to the surface of the sample. This is a pattern correction method in which a reaction gas is supplied, and the base substrate surface at the correction portion is etched using the reaction gas activated by the irradiation of the focused ion beam.

[Action]

According to the above-described means, the ion source metal can be removed without roughening the surface of the undersubstrate by chemically etching the undersubstrate surface at the repaired portion using the reaction gas activated by the focused ion beam of low acceleration voltage. Can be removed.

Further, by removing the ion source implanted metal continuously without moving the sample after the pattern correction, it is possible to perform an integrated process of the pattern correction and the removal of the ion source metal.

 Hereinafter, the present invention will be described with reference to examples.

〔Example〕

FIG. 1 is a diagram showing a main part of a focused ion beam device according to the present embodiment.

The focused ion beam device 1 includes a vacuum chamber 2 and a preliminary exhaust chamber 3. Vacuum pumps 4a and 4b for exhausting the inside of the chamber are connected to the vacuum chamber 2 and the preliminary exhaust chamber 3, respectively. The lower part of the vacuum chamber 2 is movable in a horizontal plane.
An XY table 5 is provided. A stage 7 on which a photomask (sample) 6 is placed is placed on the XY table 5.

As shown in FIGS. 2 and 3, the photomask 6 is made of a transparent quartz glass substrate having a refractive index of about 1.47, and has a main surface with a thickness of about 500 to 1500 ° and a line width.
A fine pattern 8 of about 0.5 to 0.8 μm is provided. The pattern 8 constituting the integrated circuit pattern transferred onto the semiconductor wafer is formed by processing a metal film such as Cr (chromium) deposited on the main surface of the glass substrate by an electron beam drawing method. The pattern 8 becomes a light-shielding area during exposure, and the other areas become light-transmitting areas. Here, it is assumed that the photomask 6 has a pin dot-shaped black spot defect 9 in a part of the light transmission region.

In the vicinity of the upper surface of the XY table 5 on which the photomask 6 is mounted, a reaction gas supply nozzle 10 for supplying a reaction gas to the surface of the photomask 6 and secondary ions generated from the surface of the photomask 6 are captured. A secondary ion detector 11 for detecting the end point of the etching is arranged.
The other end of the reaction gas supply nozzle 10 is connected to a gas cylinder 12 outside the focused ion beam device 1. Above the gas cylinder 12 is fluorocarbon-based gas such as CF ₄ or CHF ₃ is filled.

Above the vacuum chamber 2, a cylindrical ion beam column 13 is provided.
Is provided. At the top of the ion beam column 13, an ion gun 14 as an ion beam source is arranged. The ion gun 14 emits metal ions such as Ga (gallium). Below the ion gun 14, an extraction electrode 15 for applying a predetermined acceleration voltage to the metal ions is arranged. The above extraction electrode 15, a high acceleration power supply 16 and has a low acceleration power supply 17 is connected, by switching the acceleration voltage conversion switch 18, the ion beam I _B passing through the extraction electrode 15 a high acceleration voltage ( Either 25 keV) or a low accelerating voltage (eg 15 keV) is applied.

Below the extraction electrode 15, a beam aperture 19 is arranged. Below the beam aperture 19,
Beam deflection coils to control the beam diameter of the ion beam I _B
20 are located. The beam deflection coil 20 is connected to a pair of beam stop control circuits 21 and 22. By switching a beam diameter conversion switch 23, an ion beam irradiated on the surface of the photomask 6 on the XY table 5 is irradiated.
Beam diameter of I _B is enlarged or reduced. The switching timing of the beam diameter conversion switch 23, the switching timing of the acceleration voltage conversion switch 18, the switching timing of the secondary ion detector 12,
The control unit 24 centrally manages the end point detection signal output by the controller 24 and the control of the flow rate of the reaction gas supplied from the gas cylinder 12.

Next, a method of repairing a photomask defect using the focused ion beam device 1 will be described with reference to FIGS. 1, 4, and 5. FIG.

First, the lid 25 of the preliminary exhaust chamber 3 of the focused ion beam device 1
Is opened and the photomask 6 for defect correction is placed on the stage 7 on the stage 26, and then the lid 25 is closed. Next, valve 27
a, open the 27b, the vacuum pump 4a, the vacuum chamber 2 and the preliminary exhaust chamber 3 is predetermined degree of vacuum using 4b (e.g. 1 to 2 × 10 ¹⁷ Tor
Exhaust until r). Subsequently, the stage 7 on which the photomask 6 is placed is transferred to the vacuum chamber 2 through the gate valve 28 and placed on the XY table 5.

Then, the ion beam I _B accelerated by a high acceleration voltage of 25 keV, and squeeze the beam diameter 0.2μm or less is irradiated to the black spot defect 9 photomask 6 removes the black spot defect 9 by sputter etching. At this time, as shown in FIG.
Since the ion source metal (Ga) is implanted to a depth of about a degree, the light transmittance of the glass substrate at the above-mentioned corrected portion is:
It is reduced to about 85 to 96% as compared with other light transmitting regions.

Next, the control unit 24 that has detected the removal of the black spot defect 9 by the endpoint detection signal of the secondary ion detector 12 is switched acceleration voltage conversion switch 18 and the beam diameter conversion switch 23, the acceleration voltage of the ion beam I _B 15ke
V and the beam diameter increases. Subsequently, the valve 27c of the gas cylinder 12 is opened by a signal from the control unit 24, and the reaction gas is supplied to the surface of the photomask 6 through the reaction gas supply nozzle 10. The reaction gas consists of a fluorocarbon-based gas such as CF ₄ or CHF _3, the flow rate, for example, a vacuum degree in the vacuum chamber 2 is 2 to 3 ×
It is about 10 ^-6 Torr.

The reaction gas supplied to the surface of the photomask 6 is:
Activated by the energy of the ion beam I _B, a glass substrate thereby correcting portions are chemically selective etching, ion source metal (Ga) are removed (Fifth
Figure). At this time, the ion beam I to _B low acceleration voltage (15Ke
Since V) is applied and the surface of the glass substrate is not physically etched, the surface of the glass substrate is not roughened. Also, to expand the beam diameter, to increase the contact area between the reaction gas and the ion beam I _B at correcting portions near by the reaction gas activated, thereby improving the selectivity of the etching, the surface of the glass substrate Is prevented.

According to the photomask defect repair method of the present embodiment having the above configuration, the following operation and effect can be obtained.

(1). Lowering the accelerating voltage of the ion beam I _B to prevent physical etching of a glass substrate by the ion beam I _B,
By chemically etching the glass substrate corrected portion with activated reactive gas by irradiation of the ion beam I _B, it can be removed ions source metal (Ga) without roughening the surface of the glass substrate it can. This makes it possible to reliably recover the light transmittance lowered by the pattern correction, thereby improving the accuracy of pattern defect correction.

(2). By the above (1), it is possible to prevent a pattern defect at the time of transfer (causing a disconnection or a short circuit of a wiring) due to a decrease in light transmittance, so that the production yield of the semiconductor integrated circuit device is improved.

(3). Since the correction of the black spot defect 9 and the subsequent removal of the ion source metal (Ga) can be performed consistently in the vacuum chamber 2, the throughput of the pattern correction process is improved.

As described above, the invention made by the inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments, and it can be said that various modifications can be made without departing from the gist of the invention. Not even.

In the above embodiment, a fluorocarbon-based gas was used as the reaction gas, but any gas can be used as long as the gas imparts glass etching ability by irradiation with an ion beam.

In the above-described embodiment, the case where the present invention is applied to the correction of a black spot defect has been described. However, when the white spot defect is corrected using, for example, a laser CVD method, the present invention is also applied to a case where an extra thin film deposited on a glass substrate is removed. be able to.

In the above description, the case where the invention made by the present inventor is mainly applied to defect correction of a photomask, which is the background of the application, has been described. However, the present invention is not limited to this. The present invention can also be applied to pattern defect correction of a wiring board, a liquid crystal panel, and the like.

〔The invention's effect〕

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

(1). According to the pattern correction method of the present invention, the light transmittance of the sample, which has been reduced by the pattern correction, can be reliably recovered, so that the reliability of the pattern correction is improved.

(2). According to the pattern correction method of the present invention, since the pattern correction and the removal of the ion source metal can be performed consistently, the throughput of the pattern correction is improved.

[Brief description of the drawings]

FIG. 1 is a view showing a main part of a focused ion beam apparatus according to one embodiment of the present invention, FIG. 2 is a sectional view of a main part of a photomask, FIG. 4 and 5 are cross-sectional views of a main part of a photomask showing a photomask defect repair method. 1 Focused ion beam device, 2 Vacuum chamber, 3 Preliminary exhaust chamber, 4a, 4b Vacuum pump, 5 XY table,
6 photomask (sample), 7 mounting table, 8 pattern, 9 black spot defect, 10 reactive gas supply nozzle,
11 ... Secondary ion detector, 12 ... Gas cylinder, 13 ...
... Ion beam column, 14 ... Ion gun, 15 ... Extraction electrode, 16 ... High acceleration power supply, 17 ... Low acceleration power supply, 18 ... Acceleration voltage conversion switch, 19 ... Beam aperture, 20 ...
Beam deflecting coils, 21, 22 ... Beam stop control circuit, 23
…… Beam diameter conversion switch, 24 …… Control part, 25
... lid, 26 ... stage, 27a, 27b, 27c ... valve, 28
... Gate valve.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23F 4/00 G03F 1/08 H01L 21/027 H01L 21/3065

Claims (7)

(57) [Claims] 1. A pattern correction method for irradiating a focused ion beam onto a surface of a sample on which a predetermined pattern is formed to sputter-etch a pattern correction portion. Supplying a reaction gas to the surface of the substrate, and etching the sample surface at the correction point using the reaction gas activated by the irradiation of the focused ion beam. 2. The pattern correction method according to claim 1, wherein after the pattern correction, the beam diameter of the focused ion beam is enlarged. 3. The pattern correction method according to claim 1, wherein a fluorocarbon-based gas is used as the reaction gas. 4. A step of forming an integrated circuit pattern on a glass substrate, and irradiating a focused ion beam accelerated at a first acceleration voltage to a black spot defect generated on the glass substrate to remove the black spot defect. Setting the accelerating voltage of the focused ion beam to a second accelerating voltage lower than the first accelerating voltage, supplying a reactive gas onto the glass substrate, and activating by the focused ion beam. Removing the surface of the glass substrate in the region where the black spot defect has occurred by using the converted reaction gas. 5. The method according to claim 4, wherein the black spot defect is made of chromium. 6. The method according to claim 4, wherein the reaction gas is a fluorocarbon-based gas. 7. A step of preparing a glass substrate on which an integrated circuit pattern is formed, and irradiating a pattern ion generated on the glass substrate with a focused ion beam accelerated at a first acceleration voltage to remove the pattern defect. Removing the focused ion beam, setting the accelerating voltage of the focused ion beam to a second accelerating voltage lower than the first accelerating voltage, supplying a reactive gas onto the glass substrate, Chemically etching the surface of the glass substrate in a region where the pattern defect has occurred with the reaction gas activated by the above method.