JPH01140159A - Ion beam working device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion beam processing device, and is particularly suitable for ion beam processing of X-ray masks, masks with insulating films, elements, etc. such as LSIs, etc. It is related to a device.

[Conventional technology]

Conventionally, when sputtering a mask or LSI using a focused ion beam to correct pattern defects, the following problems occur.As shown in Figure 2 (1), the mask, LSI, etc. There is an insulating film 15 on the upper surface of a pattern 16 to be processed on the object 8, and when processing the pattern 16 with the ion beam 3, first N! The edge wedge 15 is processed and then the pattern 16 is processed. However, loquat 1ijllll
(When processing the insulating film 15, the ion beam 31
Since it is more positively charged, the spot of ion beam 3 is P! There is a problem that the irradiation position of the ion beam 3 is shifted due to the repulsion of the positive charge 18 on the surface of the rim 15.

On the other hand, as shown in Figure 2(b), the electronic Java 17
A method using this method is described in Patent No. 5111-5433. This heats the filament 24 of the electronic Java 17, applies a voltage to the extraction electrode 25 to extract electrons, and irradiates the surface of the insulating film 15 with the electron flow 19 as shown in FIG. is applied to neutralize the positive charges on the surface of the insulating film 15.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, it is necessary to narrow down the electrons from electronic Java to a predetermined location and irradiate only the optimum amount of electrons required for neutralization. However, this adjustment is difficult, as the periphery of the ion beam 5 or the periphery of the insulating film 15 becomes negatively charged due to the electrons, which disturbs the trajectory of the ion beam 3.
On the other hand, the amount of electrons is small and the positive charges on the surface of the ion beam 3 and the insulating film 15 cannot be completely neutralized, making it impossible to prevent the spot position of the ion beam 3 from moving. When it comes to Tanashi, there are 5 problems, my friend.

An object of the present invention is to prevent the surface of an insulating film of a workpiece from being charged without disturbing the trajectory of the ion beam or changing the beam shape, and to prevent the irradiation position of the ion beam from shifting. The goal is to process In one degree well.

[Means for solving the problem] [The above purpose is to sputter processing a workpiece with a focused ion beam.
This is achieved by using the following configuration of a deflector controller that controls the deflection voltage of a deflector that scans the ion beam within the processing area. Deflector controller X
The deflection voltage is a normal sawtooth wave generator, and the Y deflection voltage is a voltage waveform generator that performs interlaced scanning with a width corresponding to the ion beam diameter, or a voltage waveform generator that performs scanning at certain intervals in the Y direction. There is a voltage waveform generator that returns the voltage, or there are multiple blocks in the Y direction and each block is scanned once.
This is achieved by providing a voltage waveform generator that scans each block circle in an arbitrary direction.

[Effect]

To sputter a workpiece with a focused ion beam,
This is done by scanning the spot of the ion beam within the processing area using the deflection voltage of a deflector, and using the energy of the incident ions to knock out atoms of the workpiece and remove them. At this time, the deflection voltage of the deflector that scans the processing area is normally generated by a sawtooth wave electric/pressure generator in the X direction as shown in Figure 3 (α) or (b), and in the Y direction as shown in Figure 3 (a). ), the stepped voltage waveform generator using DA conversion was applied by a sawtooth voltage waveform generator as shown in FIG. 3(b), and processing was performed by sequential scanning. In this case, if the number N of scanning lines in the processing area of the ion beam is 200 to 500, for example, 5 μm above the processing area, the distance Δ1 between each scanning line is 0.025 μm to α01 μm. However, the spot diameter d of the ion beam is 0.1 μwt = 0.5 μm (ΔJ(d), as shown in Figure 3 (C), @), the ion beam of the previous scan f# is There are cases where the spot irradiation location and the spot irradiation location of the current ion beam differ by more than 90 cm. By the way, Tomomasa's '1 charge charged by the ion beam at each stroke f, line is am
It leaks with a time constant determined by the electricity y'it and resistance of the workpiece. If the scanning time of one scanning line of the ion beam is large, the workpiece will not be charged, but if it is not, a positive charge will accumulate as the workpiece reverses its scanning direction. go.

Therefore, in the present invention, as shown in FIGS. 41(α) and (b), the
The directional deflection range pressure is determined by using a stepped interlaced scanning voltage generator using DA conversion or a sawtooth interlaced scanning voltage generator. Scanning is performed by changing the deflection voltage of the deflector to avoid overlapping. In other words, as shown in Fig. 4 @), in the stepwise interlaced scanning voltage generator, the magnitude of the X-direction deflection region pressure is determined by the voltage corresponding to the ion beam diameter d with the period Tx of the X-direction deflection and direction voltage. , increases stepwise by the same amount, and in the next cycle of the X-direction deflection area pressure, the spot diameter d is shifted by an interval Δy of, for example, 10%, so that it becomes the same as the previous cycle. A magnetic pressure waveform having four shapes d is generated. Alternatively, as shown in No. 41!4 (b), a sawtooth wave interlaced scanning voltage generator generates a sawtooth wave direct pressure waveform whose synchronization TY is Ty=T×N+T, x△νA. do.

In this way, as shown in Fig. 4(c) and (I4), the ion beam scans the machining area in the Y direction at intervals of ΔJ, = d, scans the entire machining area once, and scans the entire machining area in one frame. Then, the first scanning line of the second frame is Δy from the first scanning line of the first frame, and the rest is Δj.
Scanning is performed at an interval of =d, and the parts where the scanning lines of the first frame are skipped are processed. As before, the scanning line of the first scan of the third frame is separated by an interval Δν from the scan fm of the first scan of the second frame. and,
Every time the number of frames F=d/Δy is scanned, the same scanning line as the previous scanning line is scanned.

In this case, the number of irradiation locations of the ion beam spot increases in each frame, compared to each scanning line in the conventional method.
Since the time interval between irradiation of the ion beam spot on the same part of the workpiece and its re-irradiation becomes longer, the insulating film of the workpiece becomes electrically charged and the amount of leakage of Tomomasa increases. . Seventh, since the insulating film is less likely to be charged, the irradiation position of the ion beam spot is no longer misaligned.

Next, a deflection voltage generator that increases the amount of interlace in interlace scanning will be described. As mentioned above, the scanning line interval of the ion beam is set to Δ1. -D and as a friend, the insulating film is charged during the previous scan and the specific pressure charge leaks due to the deviation of the trajectory of the ion beam spot due to noise or the spread of positive charges on the workpiece9. A case may occur where a new charge is generated without charging. At this time, a deflection voltage generator that increases the scanning line width of the interlaced scan by two or three times the spot diameter d may be considered, but a deflection voltage generator that increases the amount of interlacing is used as described below. In this case, as shown in FIG. 5(b), the processing area is divided into a plurality of blocks, and as shown in FIG. A five-way interlaced scan voltage generator is used, and the increments corresponding to the blocks are made into a stepped voltage waveform. And X
The direction deflection voltage is shifted every cycle by an amount corresponding to the amount of shift Δ of the scanning line in each block. As a result, the first frame of the ion beam scans the beginning of each block, and the second frame scans the second scanning line of each block.

In this case, the amount of interlace in interlace scanning described above is greatly increased, but the X-direction deflection voltage is converted to a voltage as shown in Fig. 6(a) using a constant voltage waveform generator using DA conversion. When a waveform is applied to the X-direction deflection electrode, it becomes possible to change the scanning order of blocks in one frame, as shown in FIG. 6(b)j. In this case, by changing the scanning line deviation Δy within each block, it is possible to variously change the scanning order in each block.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The ion beam processing apparatus shown in FIG. 1 turns on and off a high-intensity liquid gold maple ion source 1, an extraction electrode 2 that extracts ions from the ion source, a lens electrode 4 that focuses the extracted ion beam 5 feet, and an ion beam 3. Blanking electrode 5, blanking aperture 6, and X-biased electrode/pole 2 of the teflector 7 that scans the ion beam 3 over the workpiece 8
6, Y deflection electrode 27, secondary electrons 11 emitted from the workpiece 8
a secondary electron detector 10 that captures and outputs an electric signal;
Stage 9 and Karasashi where the workpiece is installed are as follows:
It is housed in a vacuum chamber that is evacuated to a true nitrogen temperature of 1 f' Torr or higher using a vacuum pump.

Also, as a control device, an amplifier 1 that amplifies the signal of secondary electrons.
2. The CkLT display 25 displays the amplified signal as a scanning ion 11N, scans the ion beam by changing the X deflection voltage of the teflector 7, and scans the ion beam by changing the It consists of a deflector controller 13 that changes the deflection voltage of the CRT display, and a blanker 14 that applies voltage to the blanking electrode L pole 5, deflects the beam, and blocks it with the blanking aperture 6.

The deflector controller 13 also includes an X deflection controller 28 that performs normal scanning in the X direction, a 5Y deflection controller 29 that performs normal sequential scanning in the Amplifier 31, 52.53 that changes the scanning range
It consists of.

Next, its operation will be explained. The workpiece 8 is covered with an a-retaining film 21 made of PIQ using an X-shaped mask as shown in Fig. 7.
It has a four-layer structure including an Au pattern 22 that absorbs X#, a buffer material 21' made of PIQ, and a support film 25 made of BN. The protective film 21 is an insulating film, and what is processed is the Au pattern 22. The protective film 21 is on the top surface, and the Au pattern 22 is processed after the protective film 21 is processed.

By applying a high voltage of several kilovolts between the ion source 1 and the extraction electrode 2, the ion beam 6 is focused to 0.1 to 0.3 μm on the workpiece 8 by the extraction lens electrode 4. The scanning of the ion beam 5 by the deflector 7 differs between observation for positioning the processing area of the workpiece 8 and during processing in which only the processing area is scanned. During observation, the Y deflection electrode 26 and the Y deflection electrode 27 of the deflector 7 are connected to the X deflection controller 28 and the X deflection controller 29 of the deflector controller 13, respectively, and the Xvi
A regular sequential scanning voltage waveform shown in FIG. 3(a) or (b) is applied to the j1@ electrode 26 and the Y deflection electrode 27. At this time, the valley voltage value is the amplifier 31, 5
2, the scanning range is made larger than that during machining, and the scanning range extends to the periphery of the machining location. Then, the luminance obtained by the secondary electronic detector 10 is changed to 7' (by the luminance signal C), and the luminance on the T display is changed, and the X deflection controller 28 and
A scanned ion image can be obtained by deflecting the ion beam on a CRT display using a deflection controller 29 in synchronization with the ion beam.

Next, in order to perform processing, the processing location is limited from the scanned ion image, the processing location is moved to the center of the original axis by the stage 9, and the values of the amplifiers 31 and 32 are made small so that the ion beam 3 scans only the processing location. As a result, the number of days the ion beam scans the processing area per unit time is large.
Sputter processing using an ion beam becomes possible. At this time, if the temporary workpiece 8 is as shown in FIG. 7, the ion beam 3 will protect the workpiece 8 111i! Since 21 is an insulating film, it is charged with a positive charge. Charged *X charge 18
The positive charges leak to the periphery and the stage 9 via the U pattern 22 over time, but if the scanning time of the ion beam is short, positive charges accumulate in the protective film 21.

Therefore, in order to lengthen the leakage time, Y(
The Ji electrode 27 is connected to the deflector controller 13OY and the deflection jump controller 30. In this case, Y
The deflection jump controller 30 generates a step-like voltage waveform with an increment ΔJ and a shift amount Δ2 (where ΔJ− is the scanning line interval, Δ2 scanning line shift amount) as shown in FIG. 4 (α). The stepped interlaced scan voltage generator has a period T-T! as shown in Figure 4).・N+T, ・Δl/ΔL
(Tx: X deflection voltage period, N: number of scanning lines per frame).

At this time, the processing area is 5 μm, and the ion beam diameter is d=α
1μm, and the amount of deviation of the scanning line is Δy=001μm,
ΔJ-=d, the number of scanning lines N in the Y direction in one frame is 5.
In this case, the first scanning line in each frame is shifted by Δy=α01μ from the first scanning line in the previous frame. As a result, the ion beam scans one location every 10 frames. In this case, as shown in FIG. 8(C), after the spot of ion beam 3 is irradiated (t=t4), 90% of the same area is irradiated (t; t5) at the 50th scan. be. on the other hand,
In the case of sequential scanning, as shown in FIG. 8 (4), the time Δt for scanning the same location is one scan? #1 hour (to~1+
), the leakage time of the positive charge Qo by the ion beam 3 is 50 times that of the sequential scanning method.
A22 is charged and the specific charge (. leaks.

By the way, in the case of sequential scanning, it is conceivable to slow down the scanning speed in order to lengthen the leakage time, but as shown in Fig. 8(b)
As shown in the figure, the positive charge accumulated when the scanning time is multiplied by α is also α times that of case (1) before the scanning speed is multiplied by α, and the antistatic effect is weak.

In this example, F=ΔJ−/Δn (in this case, F
=10) When frame scanning is performed, the processing area is the same as in normal sequential scanning, and uneven processing due to interlaced scanning does not occur, and the entire processing area is uniformly processed.

In addition, the spatter award is mostly when processing along the slope that has already been processed, but in the first frame processing, all flat surfaces are processed, so the amount of spatter is small. However, from the second frame Processing is performed along the slope as in the normal case, and it is thought that the amount of spatter as a whole does not change from the normal case.

Next, a second embodiment of the present invention will be described. In this embodiment, the Y-biased toe-over controller 30 of the first embodiment is replaced with a block movement controller. The block movement controller generates a stepped interlaced scanning voltage by DA conversion, which has an increment corresponding to a block as shown in FIG. Consists of a generator.

For example, if the interval between each block is about 10th of the ion beam diameter d (1 μm), the processing area of the workpiece 8 is 5 μm.
In this case, L=5 blocks are formed on the processing area. However, if the amount of deviation is Δyt-rt/2, it is 0.05 μm. At this time, in the first frame, the beginning of each block 1 to 5 is scanned, and in the second frame, it is scanned with a deviation of Δy = α05 μm from the scanning line of the first frame, and at this point, the irradiation point of the ion beam spot is Wealth will occur.

By the way, if there is a deviation in the trajectory of the ion beam 3 or if the positive charges on the IE membrane 21 of the workpiece 8 spread, etc., the ion beam 3 is scanned sequentially to blocks other than the corresponding block, so that the ion beam 3 is within each block. In particular, the time interval between the overlaps of the ion beams 3 within a block can be made L times longer than in sequential scanning, making it possible to prevent positive charges from being charged by the ion beams.

For such a second embodiment, as shown in FIG. 6(b), a deflection controller that changes the scanning f and order of each block, and the scanning line interval and direction within each block is used. −
It is also possible to change it to la.

〔Effect of the invention〕

According to the present invention, in order to prevent the insulating film from being positively charged by the ion beam by changing the scanning interval and scanning order of the ion beam and prolonging the time for charging and leakage of the ion beam, This method has the advantage that it is possible to prevent the workpiece from being charged without disturbing the trajectory or changing the beam shape, and it is possible to eliminate deviations in the ion beam irradiation location.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a conventional antistatic method, FIGS. 3 to 6 are explanatory diagrams of interlaced scanning of the present invention, and FIG. FIG. 8 is an explanatory diagram of the first embodiment of the invention, and FIG. 9 is an explanatory diagram of the second embodiment of the invention.

Claims (1)

[Claims] 1. In an ion beam processing apparatus consisting of an ion source, an ion beam optical system that extracts and focuses an ion beam from the ion source, a deflector that scans the ion beam on a workpiece, and a deflector controller that controls the deflection voltage of the deflector, a deflector is used. The X deflection voltage of the controller is a normal sawtooth wave generator, and the Y deflection voltage is a voltage that makes the processing area multiple blocks, scans each block once, and scans each block circle in any direction. An ion beam processing device characterized by comprising a waveform generator.