JPH01280759A - Method for removing pattern film - Google Patents

Abstract

PURPOSE:To completely remove a pattern film by providing a process in which adjacent spots are successively scanned and another process in which an etching gas is blown on spots which are not adjacent to each other by scanning the spots by switching the scanning method of a converged ion beam. CONSTITUTION:The pattern removing process of this invention is divided into the 1st and 2nd processes by switching the scanning method of the converged ion beam 4 and most of a pattern film 24 is removed by ordinarily scanning adjacent spots in the 1st process. In the 2nd process, the spots of the film 24 which are not adjacent to each other and to which an etching gas 16 adheres are scanned in the order from a section a1 to another section a3. While the spots a1-a3 are scanned, sufficient quantities of the etching gas 16 are blown on sections b1-b3 of the film 24 and the sections are successively scanned. Therefore, the 2nd process which is slow in etching speed is only performed on the remaining section left un-removed in the 1st process and the chemical reaction effect of the gas 16 can be utilized sufficiently. Thus the pattern layer is completely removed without leaving an ion-implanted layer with a less quantity of gas in short processing time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microfabrication method using a focused ion beam, and is used to remove pattern films when repairing black defects in masks and reticles sometimes used in semiconductor integrated circuit manufacturing processes. The present invention relates to a method for removing a patterned film without leaving an ion-implanted layer in the patterned film removal area during processing.

[Summary of the invention]

If the pattern film removal process was performed only by physical spattering using a focused ion beam, the light transmittance of the part where the pattern film was removed would decrease due to damage to the substrate due to ion implantation. Even when pattern film removal processing was performed using a focused ion beam in an etching gas atmosphere, the effect was small, and a reduction in light transmittance due to damage to the substrate during black defect correction was a problem.

A drawback of the conventional method is the scanning saw method of the beam.

In digital scanning, which is generally a scanning method for imaging patterned films, a beam is scanned for each adjacent Subono I, making it possible to obtain image information for each spot, but this scanning method can also be used when removing patterned films. Because of this, the irradiation intensity distribution of the focused ion beam is
Even in an etching gas atmosphere, the focused ion beam is irradiated again immediately after the etching gas causes a chemical reaction in the overlapped area, so the chemical etching effect cannot be fully exploited. Ta.

The present invention separates the pattern film removal process into a first process and a second process by switching the beam scanning method. By switching the scanning method and scanning non-adjacent spots one after another, or by scanning one after another while providing a blanking time of δ while moving to the adjacent spot of L4 company. , a necessary and sufficient amount of etching gas is always attached to the spot irradiated with the focused ion beam = 3- to maximize the effect of the chemical reaction caused by the etching gas, and to
The process uses the conventional scanning method to remove most of the pattern film, and the second process, which has a slow etching speed, only removes the remaining part, so the time required for the entire process is longer than the second process. The pattern film removal method of the present invention can be much shorter than the two-step process, and the amount of etching gas introduced into the equipment can be kept to a minimum. The light transmittance of the removed portion is increased to almost 100%.

[Conventional technology]

FIG. 2 shows the overall configuration of a patterned film removal apparatus related to a conventional patterned film removal method, in which 1 is an ion source such as a liquid metal ion source, 2 is a focusing lens, 3 is an objective lens, and 4 is a focusing lens. ion beam, 5 is a sample consisting of a photomask or reticle, 6 is an XY stage, 7 is a secondary ion (or secondary electron), 8 is a secondary ion detector (or 2
9 is a calculation unit, 10 is a CRT, 11 is a scanning control unit, 12 is a scanning electrode, 13 is a blanking control unit, 14 is a blanking electrode, 15 is an external input such as a mouse or keyboard ( equipment, 16 is an etching gas;
17 is a gas gun nozzle, 18 is a valve for turning on and off the etching gas, and 19 is a gas supply source.

With this configuration, the ion beam generated from ions #, 1 is focused by an electrostatic lens system consisting of a focusing lens 2 and an objective lens 3 to become a focused ion beam with a submicron diameter and irradiated onto the sample 5. The XY stage moves on the XY horizontal plane to bring any point on the surface of the sample 5 directly under the focused ion beam. The scanning of the focused ion beam 4 is performed by the scanning controller 1.
Scan electrode 1 with stepwise voltage in the X and Y directions orthogonal to electrode 1.
2, and the surface of the sample 5 is digitally scanned in a spono I-like manner. To turn on and off the focused ion beam at the sample 5-, the blanking control unit 13 applies a voltage to the blanking electrode 14 to polarize the focused ion beam, and for example, the focused ion beam is blocked by the outer cylinder part of the gas gun nozzle 17. To do this.

Secondary ions 7 generated from the surface of the sample 5 by scanning of the focused ion beam are detected by a secondary ion detector 8, and a pattern image corresponding to the intensity of the secondary ions is displayed on the CRTIO by a calculation unit 9.

The pattern film removal process is performed by setting the repeated scanning range of the focused ion beam 4 using the external input device 15 while observing the pattern images of the CRT1 and OJ2, and then controlling the scanning control unit 11 and the blanging control unit 13 via the calculation unit 9. , the focused ion beam 4 starts to repeatedly scan, and is performed by physical sputtering. Alternatively, at the same time as the repeated scanning of the focused ion beam 4 is started, the valve 18 is opened by the calculation section 9, and the pattern film removal process is performed while the etching gas from the gas supply source 19 is blown.

FIG. 3 is a diagram showing the scanning order of the focused ion heater J,4. For simplicity, the scanning range boundary 20 is shown as a rectangle. The 21 square area is Suboso I, and the spot number 1. 2. 3. One frame is scanned in the order of -i, i4-1, -.

FIG. 4 shows a scanning electrode 1 for standardizing the scanning order.
The voltage waveforms 22 and 23 in the x and X directions of 2 are shown.

The numbers marked with a (J) in the figure correspond to the spot numbers in FIG. 3, and in the X direction there is a step-like voltage waveform for each spot, and in the X-direction there is a step-like voltage waveform for each column. Therefore, the transition time from one spot to the next is instantaneous, each spot is irradiated for a certain period of time, and a continuous digital scan is performed as a whole.Such a scanning method is used for imaging. This is because the arithmetic unit 9 digitally processes the display of one detected image of the secondary ions 7.

FIG. 5 is a diagram showing the focused ion beam irradiation intensity distribution. The intensity distribution 24 at one spot generally has a Gaussian distribution. Figure (A) shows the intensity distribution in large-field imaging, and each point of the spot 21 is scanned as a series of points that do not overlap with each other.
The shape and position of the pattern to be removed can be quickly confirmed.

Figure (B) shows the intensity distribution in small-field imaging, where the intervals between the spots 21 are smaller than the full width of the focused ion beam, and the spots 21 overlap each other, making the overall intensity distribution continuous. Therefore, it is possible to obtain an image with high accuracy, and even during pattern film removal processing, by performing the scanning method for imaging of a small field of view described above, it is possible to perform edge processing with high accuracy.

[Problem to be solved by the invention] In the conventional pattern film removal method, the effect of spraying etching gas is not sufficient (the light transmittance of the pattern film removed area is about 75% when no etching gas is used). When blowing etching gas kJ, it is slightly better at about 85%, but it is still at a practical level for exposure using photomasks and reticles used in the manufacturing process of semiconductor integrated circuits such as IC and LSI. had not been reached.

FIG. 6 is a diagram schematically showing the drawbacks of the conventional pattern film removal method. (A) to (E) in the figure show how the focused ion heal I is sequentially scanned on suboso I 1 to 5 in the focused ion beam scanning range of FIG. 3. (A) is a diagram in which a focused ion beam is irradiated onto a spot 1 of a pattern film on which a tinging gas 16 is deposited. In (B), only the irradiated part of Subono l-1 is etched cleanly, but there is an overlap 25 in the irradiation distribution of spot 2, and this part is etched with etching gas 1.
Since the ion implantation layer 26 is irradiated with the focused ion beam earlier than the time when the ion implantation layer 6 is deposited, an ion implantation layer 26 is formed, and a layer 26 is formed as shown in (C). Similarly, in (D) and (E), an ion-implanted layer to which the etching gas adheres remains in the overlapped portion 25 of the focused ion beam irradiation distribution.

Even if the etching gas was introduced in this way, the effect was small and the light transmittance did not improve.

[Means to solve the problem]

The present invention was made to eliminate the above problems, and includes an ion source, an electrostatic lens for focusing the ion beam generated from the ion source, a scanning electrode for scanning the focused ion beam, and a sample. A pattern consisting of a gas gun for spraying etching gas onto the sample, a detector for secondary charged particles emitted from the sample, and an image display device that displays a pattern of the sample according to the output of the detector. In the film removal apparatus, the entire process of pattern film removal is divided into two steps by switching the scanning method of the focused ion beam, and in the first step, the focused ion beam is scanned sequentially to adjacent spots. In the second step, the focused ion beam is scanned one after another on non-adjacent spots, or the focused ion beam is scanned one after another with a certain blanking time between spots, and etching is performed. The method is characterized in that the gas blowing is performed either during the pattern film removal process or from the beginning.

[Effect]

The above method works by switching the scanning method of the focused ion beam in the pattern film removal process.
The first step is to remove most of the pattern film in the same way as in the past, and the second step is to scan spots that are not adjacent to each other one after another, or to remove adjacent spots. By scanning one after another while providing a certain blanking interval between spots,
By ensuring that a necessary and sufficient amount of etching gas is always attached to the substrate irradiated with the focused ion beam, the remaining portion of the pattern film is removed while maximizing the effect of the chemical reaction caused by the etching gas. In order to remove the parts, the first step prioritizes the effect of increasing the etching speed over the effect of the chemical reaction, and the second step maximizes the effect of the chemical reaction, although the etching speed is slower than the first step. As a result, the light transmittance can reach almost 100% with minimal processing time and without leaving any ion-implanted layers. Furthermore, by spraying the etching gas in the middle of the pattern film removal process, the amount of etching gas introduced into the equipment can be kept to a minimum. By spraying the etching gas from the beginning, the effect of delay in the etching gas control system can be eliminated.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. The overall configuration of the pattern film removal device is the same as the conventional one, and the second
As shown in the figure.

In the figure, 1 is an ion source such as a liquid metal ion source, 2 is a focusing lens, 3 is an objective lens, 4 is a focused ion beam, 5 is a sample consisting of a photomask or reticle, and 6 is an XY
stage, 7 is a secondary ion (or secondary electron), 8 is a secondary ion detector (or secondary electron detector), 9 is a calculation unit, 1
0 is a CRT, 11 is a scan control unit, 12 is a scan electrode,]3
14 is a blanking control unit, 14 is a blanking electrode,
15 is an external input device such as a mouse or keyboard;
16 is an etching gas, 17 is a gas gun nozzle, 18 is a valve for turning on and off the etching gas, and 19 is a gas supply source.

With this configuration, the ion beam generated from the ion source 1 is
The ion beam is focused by an electrostatic lens system consisting of a focusing lens 2 and an objective lens 3 to become a focused ion beam with a submicron diameter and is irradiated onto the sample 5. The XY stage moves in the XY horizontal plane to bring any point on the surface directly under the focused ion beam. Scanning of the focused ion beam 4 is performed by applying stepped voltages to the scanning electrode 12 in orthogonal x and y directions from the scanning control unit 11, and digitally scanning the surface of the sample 5 in a spot manner. The focused ion beam J on the sample 5 is turned on and off by applying a voltage to the blanking electrode 14 from the blanking control unit 13 to polarize the focused ion beam, and blocking it, for example, at the outer cylinder part of the gas gun nozzle 17. To do this.

Secondary ions 7 generated from the surface of the sample 5 by the scanning of the focused ion beam are detected by a secondary ion detector 8, and a pattern image corresponding to the intensity of the secondary ions is displayed on the CRTl, 0 by the calculation unit 9. .

Setting of the scanning range is performed using the external input device 15 while observing the pattern image on the CRTIO, and instructions are given to the scanning control section 11 and the blanking control section 13 via the calculation section 9. In addition, the scanning control section 11 and the blanking control section 13
The scanning method can be switched according to instructions from the calculation section 9.

Similarly, opening and closing of the valve 18 of the gas gun is controlled by instructions from the calculation unit 9, and when the valve 18 is opened, the gas supply 111
From t19, etching gas is blown onto the surface of the sample 5 through the valve 18 and the nostle 17.

Next, a method for removing a patterned film, which is an embodiment of the present invention, will be described in detail. Sample 5 is placed in a chamber (not shown) whose interior is maintained under vacuum by a vacuum pump (not shown).
Insert. Then, by inputting the position data of the removal part to the calculation unit 9 through the external input device 15, the XY stage 6 is driven according to the instructions from the calculation unit 9, and the part to be removed on the sample 5 is brought directly under the focused ion beam, and removed. In order to confirm the location of the spot, the focused ion beam is scanned once or twice over a wide area on the sample 5, and a large field of view is imaged.
Move the XY stage 6 so that it is in the center of the image of O,
The field of view is made smaller and the area to be removed is displayed in a larger size on the CRTIO. The scanning range of the focused ion beam is CRTI
While observing the pattern image on the external input device 15
The voltage waveform explained in FIG. 4 is applied to the scanning electrode 12 from the scanning control section through the calculation section 9, and the focused ion beam is repeatedly scanned or removed at the removal point according to the scanning order shown in FIG. This is carried out only in a certain scanning range, and the first step of pattern film removal of the present invention begins.

The end point of the first step is determined, for example, by a change in pattern type during the removal process. The fumetomask and resicle of sample 5 generally have a black J pattern film formed on a glass base substrate, and the secondary ions generated by focused ion beam irradiation are mainly C ions from the pattern film, and S ions are from the glass-based cutting board.

The intensity change of these two types of ions during the removal process is shown in FIG. Time t-Q and 1=1. There is a knee peak in the C ion intensity 27, but this is because Cr is less likely to be ionized by the oxide layer near the surface of the patterned film and the interface with the underlying substrate. The end of the first step is 1-1 of C ion strength 27. The second peak at or S ionic strength 28 of 1=1. The secondary ion detector 8 and the calculation unit 9
determined by detection. Alternatively, for a sample with a fixed pattern film thickness, the number of repeated scans until the value of Ll or the second peak of the C ion intensity 27 is reached is manually entered in the calculation section 9 in advance. By the method, most of the patterned film is
Although it can be removed during the process, the removal method up to this point is exactly the same as the conventional method, and the ion-implanted layer remains.

Simultaneously with the end of the first step, the second step starts, and the calculation unit 9
The scanning control unit or blanking control unit is instructed to switch the scanning method.

Further, here, it is assumed that the blowing of the enching gas is also instructed by the calculation unit 9 at the same time as the start of the second step.

Next, a skip-and-bus scan method, which is an embodiment of the focused ion beam scanning method in the second step, will be described with reference to FIG. In Figure (A), the ion beam scanning range 20
is equivalent to that shown in Figure 3, and a, , a2, a
l+ a i+1+'-"'a k+ b I+ b
2. '−'−'.

b 4. b ++1. ""'b k, CI+ 02.
Cr-C; ++1"-"c k+ dl+d2. dl
, d, , l, and dK respectively indicate the order of the spot/node for irradiating the focused ion beam. This scanning method is
The inside of the scanning range boundary 20 is divided into two blocks containing a certain number of Subonos 1-21, and a spot number is first given to each spot within the block (in Figure (A),
a, b, c, d), and give block numbers to the blocks (a, b in figure (A)).
, c, and d), the spots with the same spot number in the block are scanned in the order of prosochronization, and when one frame is completed, the spot number with the next spot number in the first block is scanned. This is a method of scanning the entire area in the order of proso- quenance, and will be referred to as the skip scan method. The voltage waveforms in the X and Y directions of the scanning electrode 12 for performing the skip scan shown in FIG. 8(A) are shown at 22.2 in FIG.
Shown in 3. The numbers in the figure correspond to the spot numbers in FIG. 8(A), and in the X direction there is a step-like voltage waveform for each block, and in the Y direction there is a step-like voltage waveform for each row of blocks. It is a voltage waveform, and each has components at different levels. Moreover, FIG. 10 shows the focused ion beam irradiation intensity distribution by the skip scan shown in FIG. 8(A).

The intensity distribution 24 in one spot l□ generally has a Gaussian distribution, and as shown in FIG. a3. '
−”a+, so the overlap of the intensity distribution is the same as the 5th spot of the conventional method.
It is much smaller than the case shown in Figure (B). and,
A focused ion beam follows this same line, b
2. b3. Since scanning is performed while skipping one spot at a time, as shown in (b), the overall intensity distribution is the same as that shown in Figure 5 (B), which shows the conventional method, making it possible to perform highly accurate machining. .

Note that the block size in the skip scan method (
Although the embodiment has been described in which the number of spots in a block is 2×2, the size may be 3×3, for example. In this case, the block division of the scanning range is shown in Figure 8 (B).
become that way. If the overlap of the irradiation intensity distribution of the focused ion beam in the case of 2×2 Zeiss as shown in FIG. 10 (8) is a problem, the block size should be changed to 3 as shown in FIG. 8 (B).
It would be better to make it ×3 or even larger.

Next, FIG. 1 schematically shows how the Bakun film is removed in the second step.

(A) to (E) show the focused ion beam 4 by Suginobu scan with block size 3 x 3 according to Fig.
is pattern II where etching gas 16 is attached! 1
In Figure 1, the focused ion beam 4 is irradiated onto the spot in the order of al+a2+''3, and the ion-implanted layer is etched using the effect of the chemical reaction of the etching gas. Figure 1 (B
) is neatly machined as shown in 7. The focused ion beam 4 then a4. a =,,””'
The spots are irradiated in the order of a and q, and during that time the spots shown in Figure 1 (C
), the etching gas 16 is deposited, and as shown in FIG. 1(D) again, the focused ion beam 4 is
l, b2. The spots are irradiated in the order of b3 to perform a clean etching, and the focused ion beam 4 is applied to the spots 1-b.
,, b, , -b A sufficient amount of etching gas 16 is deposited on I' while the focused ion beam 4 goes around C, C2, C3 as shown in FIG. 1(E). The spot is irradiated with the light, and the same process is repeated. In this way, the spot I, which is irradiated with the focused ion beam 4,
In this case, a sufficient amount of etching gas is always supplied to bring out the effect of the chemical reaction. However, in the skip scan method, the time required for irradiation of the focused ion beam to shift from one spot to an adjacent spot may be short. In such a case, blanking can actively provide time for the etching gas to adhere. For example, blanking is performed when a focused ion beam moves from a block to an adjacent block (block blanking), or from the last block of one frame to the first block.
20= Perform blanking (frame blanking) etc. while the ion beam is coming to the spot I where there is a focused ion beam.
It is also possible to increase the time (spora 1 - blanking time) for moving to an adjacent spot from . In addition to these block blanking times and frame blanking times,
Dual ring time (the time the focused ion beam stays on one spot), block size, and starting point of the second process.

If parameters such as the end point are set in such a way as to maximize the effect of the chemical reaction caused by the etching gas, and to minimize the time required for pattern film removal processing and the amount of etching gas introduced into the equipment, pattern film removal will be possible. It is effective in improving the light transmittance of the device, improving throughput, and protecting the ion source, secondary ion detector, vacuum pump, etc. inside the device. Note that the etching gas is C1,2, SiCE1.
It is a halogen gas such as BC123 or XeF2.

In addition, in a device using Ga as a liquid metal ion source,
As a result of residual gas analysis performed using a quadrupole mass filter during the pattern film removal process, GaCI2. This is because Ga in the ion-implanted layer and Ci, a component of the etching gas, react under irradiation with a focused ion beam due to the effect of a chemical reaction caused by the etching gas, resulting in GaCi.
It is presumed that the amount of water became 3 and gasified.

In addition, Auger electron spectroscopy (A
Analysis by ES) shows that the Ga content is about a few percent compared to the conventional method, and the patterned film is removed without leaving almost any ion-implanted layer.

Next, the effect of the embodiment of the present invention will be explained using the graph shown in No. 110.

Graph (A) shows the light transmittance after processing of the pattern film removed part,
Graph (B) shows the etching depth, where curve 30 is the conventional method without using etching gas, curve 31 is the conventional method with etching gas, and curve 32 is the case of the embodiment of the present invention. For comparison, time 1=1. Up to this point, the conventional method without etching gas is followed under the same conditions, and from time t to t2, the etching gas is blown or the scanning method is switched.

In addition, time 1. ．． 12 is the same as that in FIG.

From graph (A), the light transmittance is approximately 75% in the conventional method without etching gas and approximately 85% in the presence of etching gas, and as in the embodiment of the present invention with etching gas and skip scanning. 100% if you go
reach. From graph (B), the etching speed is faster when etching gas is used than when there is no etching gas in the conventional method, but in the example of the present invention, the etching speed is higher than the speed increase effect due to etching gas. The delay effect of the , skip, and bus scan methods compared to the conventional scanning method is large, and as a result, the speed is slower than the conventional method. However, when the processing end point at time t2 is determined based on changes in the intensity of secondary ions, this can be determined with high accuracy and is effective in preventing over-etching. actually,
Time required for second step 12-1. Since G is sufficiently smaller than the time t1 required for the first step, even if the etching rate is reduced somewhat in the second step, it will hardly affect the throughput. However, in the pattern film removal process -2
3= If everything is done only in the second step, due to the effect of deceleration,
This is undesirable because the processing time increases and the amount of etching gas introduced into the apparatus also increases. This is the reason why the pattern film removal process is separated into two processes in the present invention. That is, in the first step, priority is given to the through-etching over the effect of chemical reaction, and in the second step, the etching gas is blown for a short period of time to minimize the amount of etching gas introduced into the device. However, by maximizing the effect of the chemical reaction, it is possible to achieve a light transmittance of 100% without leaving any ion-implanted layer, with a minimum overall processing time and a minimum amount of etching gas.

Next, another embodiment of the focused ion beam scanning method in the second step will be explained based on FIG. Blanking is performed when the beam moves to an adjacent spot, allowing time for the necessary and sufficient amount of etching gas to adhere to the adjacent spot, thereby bringing out the effect of the chemical reaction. With only slight improvements in the method, the problems of the prior art can be overcome.

In still another embodiment of the present invention, the etching gas is
It is characterized by spraying from the beginning. This method is suitable for small area removal parts and Bakun II! It is effective for removing parts with a thin J thickness, and in processes that can be completed in a short time, by blowing the etching gas from the beginning of the first step, the ability to detect the peak of secondary ion intensity by the secondary ion detector is improved. There is no need to consider delays in the system from the start to the valve operation of the gas gun. Also, if the etching gas introduced into the equipment is non-corrosive,
Alternatively, a large amount of etching gas may be introduced using equipment equipped with anti-corrosion measures. Due to the effect of increasing the speed when the etching gas is sprayed using the same scanning method, the time required for the force-cutting process can be shortened.

Another detailed explanation of the present invention will be given below. In this example, in the focused ion beam scanning method of the second step,
For example, in the skip scan method, the blanking time is changed depending on the area of the removed part, such as block blanking time or frame blanking time, and in the method that adds blanking to the conventional scanning method, the blanking time is changed depending on the area of the removed part.
As the area of the removed portion becomes smaller, the time required for the focused ion beam to irradiate an adjacent spot becomes shorter, which may result in the focused ion beam being irradiated without sufficient etching gas adhering. In this embodiment, the above problem is solved by changing the various blanking times depending on the area.

Finally, one more embodiment of the present invention is shown in FIGS. 12 and 13.
This will be explained based on the diagram. FIG. 12 shows the intensity distribution 34 when the focused ion beam is defocused by changing the voltage of the focusing lens 2 or objective lens 3.
This becomes a Gaussian distribution with a gentle shape compared to the normal intensity distribution 33. FIG. 13 schematically shows how the second step of the pattern film removal step was performed using such a defocused beam. (8) to (E) show how the defocused beam 35 is sequentially scanned over the sponoles 1-1 to 1-5 in the focused ion beam scanning range of FIG. 3. (8) is a diagram in which the defocused beam is irradiated onto the sponole 1-1 of the pattern film 24 to which the etching gas 16 is attached.

Since the irradiation intensity is reduced due to the defocusing effect, unreacted etching gas 36 remains after one irradiation.
As shown in (B), when adjacent spots 2 are irradiated with the defocused beam, unreacted etching gas 37 remains after two irradiations due to the overlap 25 in the irradiation distribution, and these remaining etching gases 37 remain. Since the gas is located at the overlap 25 of the irradiation distribution, no ion-implanted layer is formed (C) and (D
) and (E), pattern film removal progresses. Generally, machining using a differential socus beam results in poor accuracy, but in the embodiment of the present invention, since the differential socus beam is used only in the second step, accuracy is not a problem.

(Effects of the Invention) According to the present invention, the four 27
= I-In the process of removing a pattern film on a mask or reticle, it is possible to perform the removal process without leaving any ion implantation layer in the part where the pattern film is removed, which is effective in improving light transmittance.

Further, according to the present invention, it is possible to maximize the effect of the chemical reaction caused by the etching gas while using the minimum amount of etching gas in the minimum processing time. It can also be applied to microfabrication of ICs and LSIs using focused ion beams, and can also be applied to deposition using focused ion beams using carbon-based gases or tungsten-based gases to maximize the effects of chemical reactions. It can be applied for exactly the same reason.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the second step of pattern film removal according to an embodiment of the present invention, Fig. 2 is a basic configuration diagram of a pattern film removal apparatus, and Fig. 3 is a conventional focused ion beam scanning order. FIG. 4 is a diagram showing voltage waveforms applied in the X2Y directions of the scanning electrodes in order to standardize the scanning order in FIG. 3, and FIG. 5 (8). (B) is a focused ion beam irradiation intensity distribution diagram of the cross sections P and P' in FIG. 3 for large-field and small-field imaging, respectively, and FIG. 6 is a diagram schematically showing the pattern film removal process by the conventional method. FIG. 7 is a diagram showing the change in secondary ion intensity during the pattern film removal process, and FIGS. 8 (A) and (B) are respectively the skip scan method of the embodiment of the present invention in which the block size is 2 x 2.3 x 3. Figure 9 shows the scanning electrode X
, a diagram showing the voltage waveform applied in the Y direction, FIG.
FIG. 8(A) is a focused ion beam irradiation intensity distribution diagram of cross sections P and P' in the scanning order of FIG. Figure 12 shows the change in etching depth over time. Figure 12 is an intensity distribution diagram of the focused ion beam and defocused beam.
Figure 3 shows the second pattern film removal process according to another embodiment of the present invention.
This is a diagram schematically showing the steps 1...Ion source 4...Focused ion beam 16...Etching gas 21...Spot 24...Pattern film 26...Ion implantation layer 29...Block or more Applicant Seiko Electronic Industries Co., Ltd. Agent Patent Attorney Keiyuki Hayashi = 7″V Ku m 〇−−− Ichino' -ノ (%) Hideme■ lower Gugentan Vcho ×
Σ CL CL<
COO ＼ノ -ノ
\No01” Procedural amendment (voluntary)

Claims (5)

[Claims] (1) an ion source, an electrostatic lens for focusing the ion beam generated by the ion source, a scanning electrode for scanning the focused ion beam, and a gas gun for spraying etching gas onto the sample; In a pattern film removal apparatus comprising a detector for secondary charged particles emitted from a sample and an image display device that displays a pattern on the sample according to the output of the detector, the entire process of pattern film removal is performed using the focused ions. By switching the beam scanning method, the beam is separated into two processes. In the first process, the focused ion beam is scanned to adjacent spots one after another, and in the second process, the focused ion beam is scanned to non-adjacent spots one after another. A pattern film removal method characterized by scanning a focused ion beam and further spraying an etching gas from the middle of the pattern film removal process. (2) In the common part (in parentheses in (1)), in the second step, the focused ion beam is scanned one after another while providing a certain blanking time between moving to adjacent spots, and the pattern film is further removed. A pattern film removal method characterized by spraying etching gas from midway through the process. (3) In the common part, the second step is pattern film removal characterized by scanning a focused ion beam on non-adjacent spots one after another, and further spraying etching gas from the beginning of the pattern film removal process. Method. (4) In the common part, in the second step, the focused ion beam is scanned one after another while providing a certain blanking time between adjacent spots, and furthermore, the etching gas is blown from the beginning of the pattern film removal step. A method for removing a patterned film, which is characterized by applying a coating. (5) The patterned film removing method according to claim 1 or 3, wherein the distance between the non-adjacent spots is greater than or equal to the diameter of the focused ion beam.