JPH02112138A - Ion beam alignment method for focusing ion beam device - Google Patents

Abstract

PURPOSE:To enable the rapid practice of the X, Y and theta directional positionings by conducting the X, Y direction positionings of the ion gun top end, then calculating the X, Y directional dislocation degrees caused by the theta directional positioning, and correcting the dislocation. CONSTITUTION:The ratio of the top end position displacement degree of an emitter 7 to the movement degree of theta directional regulating elements 251-253 when an ion gun 1 is moved in the direction theta is observed. From Q-X correlation functions a1-a3, theta-Y correlation functions b1-b3, and the regulation amounts T1- T3 of the theta directional regulating elements 251-253, each displacement degree X, Y in the X, Y directions is calculated according to the schemes I, II. The ion gun 1 is moved in the direction eliminating the dislocation along the X, Y directions in the portions of the determined X, or X directional dislocation X2-X1, and Y, or Y directional dislocation Y2-Y1. At a result, the top end of the emitter 7 is made in the state situated on the optical axis of lens systems 12-17, and the alignment can be rapidly and precisely conducted.

Description

[Detailed description of the invention] The present invention will be described in accordance with the above order jf.

Industrial application field Overview of the invention Background art [Fig. 7] Problems to be solved by the invention [Fig. Effects (A. Industrial Application Field) The present invention relates to an ion beam alignment method for a focused ion beam device, in particular, an ion beam alignment method for a focused ion beam device, in which an ion gun hanging from the ceiling of a vacuum chamber is aligned at least in the The present invention relates to an ion beam alignment method for a focused ion beam device that allows position adjustment in both the θ direction and the θ direction.

(B. Summary of the Invention) The present invention provides an ion beam alignment method for the above-mentioned focused ion beam device, in which alignment in the X, Y, and O directions can be performed more quickly. Adjustment of the ion gun in the θ direction for the focused ion beam device"X for i
Find the ratio of displacement in the direction and Y direction, and first set the tip of the ion gun or the optical axis Jl of the lens system of the focused ion beam device.
No alignment in the X and Y directions so that the beam is located at Multiply the adjustment amount by the above ratio to find the amount of deviation of the ion gun tip in the X and Y directions due to alignment in the 0 direction, and move the ion gun in the X and Y directions by the amount of deviation to correct the deviation by 1- It is something that

(C Background Art) [Figure 7] Ic, exposure essential for LSI manufacturing, addition by ion etching of semiconductor substrates, '4' conductor clothing for repair, growth of conductive films, and insulating films. Focused ion beam devices are increasingly being used. Technology development to improve the performance of focused ion beam devices is also active.
One of the results has been published, for example, in Japanese Patent Application Laid-Open No. 63-43249.

FIG. 7 is a cross-sectional view of an example of a focused ion beam device, in which 1 is an ion gun installed on the ceiling of a vacuum chamber 2. Reference numeral 3 denotes a refrigerator, 4 an insulating sapphire bonded to the lower end of the refrigerator 3, 5 a waste introduction space formed in the insulating sapphire 4, and a vibrator that does not appear in the drawing in the gas introduction space 5. Helium He gas, which is an ion source, is supplied from the outside of the C vacuum chamber 2 to the waste introduction space 5 through the pipe. Reference numeral 6 denotes a nozzle for jetting helium gas downward, and is formed in the opening of the waste introduction space 5 which has an opening 1 at the center of the lower end line of the insulating film fire 4. Reference numeral 7 denotes a needle-shaped emitter inserted into the nozzle 6, and the pointed tip of the emitter 7 slightly protrudes from the tip of the nozzle 6. 8 is a ratation shield that surrounds the refrigerator 3, the insulating sapphire 4, the nozzle 6, and the emitter 7 to block heat radiated from the outside; 9;
By applying a voltage between the electrode 9 and the emitter 7, the emitter 7 is
An ion beam is extracted from the tip of the ion beam.

The following is a description of the structure of the ion gun 1. Incidentally, the ion beam monitor disposed below the ion gun 1 can detect lO even from the ion beam path if necessary.

Next, a lens system for focusing, planking, and deflecting the ion beam emitted from the ion gun 1 will be described.

11 is a condenser lens that focuses the ion beam, 12 is an alignment electrode, 13 is a blanking electrode, 14 is an aperture, 15 is an alignment electrode, 16
1 is an objective lens, 17 is a deflection lens, and a lens system is constituted by members such as kneads. 18 is Aeon Bee 1
There is a semiconductor urchin, etc. that is irradiated.

19 moves the ion gun in each direction to ion gun 1.
7 nubilator for aligning the emitter 7 of the lens system with respect to the lens system. 20 is the ion gun 1 in the X direction (
The X-direction adjustment f moves in the left-right force direction in Fig. 7).
By turning the stiffness, the horizontal table 21 can be moved in the X direction. The horizontal table 21 is configured to slide in the X direction so as to keep its surface 22 constantly wet, and in the Y direction (in the direction JE with respect to the plane of the paper in FIG. 7) when drying.

Reference numeral 23 denotes a Y-direction adjuster for moving the -r ion gun in the Y-direction, and by turning this, the horizontal table 21 can be moved in the Y-direction. Reference numeral 24 denotes a Z-direction adjuster for moving the ion gun 1 in the Z direction (vertical direction), and by turning this, the ion gun 1 can be moved up and down.

25,. 252 is a θ direction adjuster for moving the ion gun 1 in the θ direction, and in addition to this, there is another θ direction adjuster 251.252 that does not appear in the drawing. There is. The O direction adjuster 2
5. ．． 25°, 253 is attached to the ion gun hanging plate 26 located on the IX′ side of the distribution horizontal plate 21,
By turning each of them, the distance between the ion gun hanging plate 26 and the horizontal plate 21 can be changed, thereby changing the direction of the ion gun hanging plate 26 with respect to the horizontal plate 21, which in turn changes the distance between the ion gun hanging plate 26 and the horizontal plate 21. The direction of the ion gun 1 suspended via the suspension part 27 can be rotated around the center point O.

28 may be a window provided on the side wall of the vacuum chamber 2.

This focused ion beam device evacuates the inside of the vacuum chamber 2 and ionizes, for example, helium gas ejected from the nozzle 6 with a high voltage applied between the emitter 7 and the extraction electrode 9, so that the electric field strength of the emitter 7 becomes the strongest. It is possible to emit an ion beam in one direction from the tip.

However, in order to perform exposure, etching, thin film growth, etc. using a focused ion beam device, it is necessary to align the ion beam with the optical axis of the lens system. It is necessary to place the point where the ion beam is generated, that is, the sharp tip of the needle-like emitter 7, on the optical axis of the lens, and secondly, it is necessary to make the direction of the ion beam the same as the optical axis of the lens. And emitter 7
To position the tip at the optical axis of the lens system of the focused ion beam device, remove the ion gun 1 together with the manipulator 19 from the vacuum chamber 2, set it in a positioning jig, and place it on the manipulator 19. ion gun 1 with
, align in the Y direction, then remove the ion gun 1 together with the manipulator 19 from the alignment jig and move it to the vacuum chamber 2.
σ is already set at the top of the application.
It can be easily done using the F1 method.

The orientation of the ion gun 1 in the θ direction is such that the inside of the vacuum chamber 2 is set to a predetermined degree of vacuum, the ion beam is emitted from the tip of the emitter 7, and the ion beam is projected onto the ion beam monitor 10 through the viewing window 28. Observe the projection state and adjust the θ direction adjuster 25. ．． 25□, 253
(The θ direction adjustment f253 does not appear in the drawing.) Adjustment can be made by appropriately turning the θ direction adjustment f253.

(D Problem to be solved by the invention) [Figure 8] However, after aligning the ion gun 1 in the X and Y directions so that the tip of the emitter 7 is located on the optical axis of the lens, the ion gun 1 is When aligned in this direction, although the direction of the ion beam becomes parallel to the optical axis of the lens system, the tip position of the emitter 7 is shifted in the X and Y directions. This is because the rotation in the θ direction is not centered at the tip of the emitter 7, but is centered at position 0, which is further on the 4- side. FIG. 8 is a diagram for explaining this point, and according to this lλ1, the point is iiF t, <
explain.

In Fig. 8, the broken line indicates the state where the tip of the emitter 7 is located on the optical axis of the lens system, and the X and Y coordinates P1 of the tip of the emitter 7 in that state are expressed as (Xi, Yl). . The solid line indicates the direction of the ion beam or the lens light 1kl+ and V
The state after adjusting the position in the Oh direction so that it becomes a row is shown, and the X and Y coordinates P2 of the position of the tip of the emitter 7 in this state are expressed as (X2Y2). When adjusting the θ direction with the tip of the emitter 7 positioned on the optical axis of the lens system, the ion gun l rotates around the rotation center 0, so the position of the tip of the emitter 7 in the X and Y directions is It deviates from the obvious. By the way, the deviation P2-Pi is (X2-Xi,
Y2-Yl).

Therefore, in order to eliminate this deviation, it was necessary to move the ion gun 1 again in the XY B directions so that it was positioned at the tip of the emitter 7 or at the optical axis of the lens.
Then, the positioning is performed by turning the X-direction adjuster 20 and the X-direction adjuster 23 of the manipulator 19 while measuring the ion beam current that has passed through the lens optical system and reached the workpiece 18, and adjusting the ion beam current. I was doing it by guessing that the value would be the maximum value.

However, the size of 1.1-Zu: P1-P2 is very large, and even if we say that we are aligning in the X direction and X direction so that the ion beam current is maximized, the range of movement for alignment is only 5 mm. Heiriki 8 is very wide. On the other hand, the axis and 0.1
If it deviates by more than 1 mm, the workpiece 18 will not reach the target. Therefore, the method of moving in the X and X directions randomly and observing the ion beam current at that time requires a very long time to achieve accurate positioning.

This problem cannot be ignored in order to improve the operating rate of ion beam devices.

The present invention has been made to solve these problems, and an object of the present invention is to enable more rapid alignment of an ion gun in the X, X, and θ directions.

(Means for Solving Problem E) The ion beam alignment method for the focused ion beam device of the present invention is to Find the ratio of the displacement meter in the direction and the X direction, and first align the position in the Align the ion beam generated from the on-gun in the O direction so that it lines up with the optical axis of the lens, and then multiply the adjustment amount for this alignment by the above ratio to obtain θ.
X of the ion gun tip by direction alignment, 1- in the X direction
The amount of deviation is determined, and the ion gun is moved in the X and X directions by the amount of deviation to make each correction.

(F. Effect) According to the ion beam alignment method of the focused ion beam device of the present invention, after aligning the position of the tip of the ion gun that emits the ion beam in the X and X directions, the ion gun is aligned in the θ direction, and then The amount of deviation in the It can be done accurately.

(G. Embodiment) [FIGS. 1 to 6] Hereinafter, the ion beam alignment method of the focused ion beam apparatus of the present invention will be described in detail according to the illustrated embodiment.

Figures 1 to 6 show one embodiment of the ion beam alignment method of the focused ion beam device of the present invention in order of T.
The present position adjustment method will be explained with reference to the drawings.

(1) First, regarding the focused ion beam device, the O direction adjustment f'25+ when the ion gun 1 is moved in the θ direction
, 252.253, the position of the tip of the emitter 7 in X, the ratio of the amount of displacement in the X direction, that is, θ・X
The correlation coefficient and the e-Y correlation coefficient are determined by actual measurement. still,
Strictly speaking, e-X correlation coefficient and θ/Y correlation coefficient are not appropriate, but θ direction adjustment Y-adjustment/X correlation coefficient, θ direction adjuster adjustment amount/Y correlation number are appropriate. Although it can be said that there are some, for convenience we will refer to them as the θ・X correlation coefficient and the θ・Y correlation coefficient.9 Figure 1 is a schematic diagram of the ion gun hanging plate 26 viewed diagonally from the 1st side to explain the correlation coefficient. FIG. The actual shape of the ion gun L is suspended from the lower surface of the ion gun suspension plate 26 via the suspension part 26, and elements unnecessary for the explanation of the above correlation coefficient are omitted. Shown.

Reference numeral 21 denotes a horizontal plate disposed below the ion gun hanging plate 26, and its V plane 22 is always kept parallel. And -
(The on-can suspension plate 26 is held on the horizontal plate 21 via legs 29□ to 293, and the legs 29. to 29. are connected to the θ direction adjusters 25+, 252., which are not shown in FIG.
By turning 253, the bottom of the ion gun hanging plate 21 [
It is possible to continuously change the length protruding from nl, so that the θ force surface adjuster 25. ．． 252
．． 253, the horizontal plate 21 of the ion gun hanging plate 26
This allows the ion gun 1 to be moved without moving in the θ direction. By the way, the θ direction adjuster 25. The amount of movement is ΔT3, θ direction 2
Let ΔT2 be the time when 52 is moved, and ΔT be the time when the θ direction 253 is moved, then the amount of displacement ΔX, ΔY in the X direction of the tip of the emitter 7 caused by moving the θ directions 251 to 253 can be calculated using the following formulas. It is expressed as

ΔX=a, ΔT1+a2ΔT2+a, ΔT, lΔY=
b, ΔT, +b2 ΔT2 +b, ΔT3
Note that a is the θ direction adjuster 25. θ・X correlation coefficient indicating the amount of displacement in the X direction of the tip of the emitter 7 per amount of position adjustment;
a2 is the θ/X correlation coefficient for the θ direction adjuster 25□;
a, l are θ direction adjustment 7-25.

θ・X correlation coefficient, bl is θ direction adjustment Y=25
The displacement amount in the Y direction of the tip of the emitter 7 per unit adjustment amount of □ is not shown. The θ-Y correlation coefficient, a2 is the θ-Y correlation coefficient for the θ-direction adjuster 25 □, and a3 is the O-direction adjustment r253. is the θ-Y correlation coefficient for If the displacement in the θ direction is large, it can be said that the displacement in the X and Y directions of the emitter 7 is directly proportional to the displacement in the θ direction, or ±1.5 mrad (= ±1 Since it changes only in a very narrow range such as ``'''), a proportional relationship exists, and the existence of correlation coefficients a1 to aJ, b1 to b1.

Therefore, in the present invention, each correlation coefficient is first determined for the focused ion beam device. This correlation coefficient is determined by the O direction adjusters 25125, . When turning each of 253 a certain amount, the amount of wrinkles that can be removed in the X direction, Y
It can be determined by actually measuring whether the emitter 7 has changed direction or moved the tip of the emitter 7. Note that if this correlation coefficient is calculated by 1-11, it is not necessary to calculate the correlation coefficient again every time the emitter 7 is converted.

(2) Next, place the ion gun 1 in the X and Y directions so that the tip of the emitter 7 that generates the ion beam of the ion gun 1 is located on the rinsing optical axis of the focused ion beam device. Alternatively, the positioning is performed using a positioning jig 30 as shown in FIG. This positioning jig 30 is a cylindrical body having the same diameter as a part of the vacuum chamber 2 and open on the north side, and has a peephole 31 formed in the center of the bottom of the chamber. Then, the ion gun 1 and manipulator 19 are removed together from the vacuum M1 and set in the alignment jig 30. Then, while looking down from below through the peep hole 31, use the manipulator 19 to move the ion gun 1 in the X direction and the Y direction.
direction so that the tip of the emitter 7 is positioned on the central axis of the alignment jig 30. This correspondence can be confirmed visually. After that, the in-gun 1 and the manipulator 19 are integrated into the positioning jig 3.
0 and set it on the top of the vacuum chamber 2.

1-, the tip of the emitter 7 is located on the optical axis of the lens system of the focused ion beam device. This is because the positioning jig 30 is the jig 30 of the ion gun 1 when the ion gun 1 is integrated with the manipulator 19.
The positional relationship with respect to the central axis of 1. is the same as the positional relationship with respect to the optical axis of the lens system of the ion gun 1 when the ion beam is set in the focused ion beam device. This is because it can serve as a dummy for positioning the r-on-can 1.

(3) Next, the inside of the vacuum chamber 2 is evacuated, and helium scum is supplied and ejected from the nozzle 6 to connect the emitter 7 and the extraction electrode 9.
A laser beam is generated from the tip of the emitter 7 without generating an electric field with an intensity of, for example, about 3 V/in on the surface of the emitter 7 by applying an extraction voltage (several to several V in V) between the emitter 7 and the emitter 7. This laser him is placed on the laser beam monitor 10 set as shown in FIGS. 3(A) and 3(B). One shot was fired. 32 is a laser beam. The laser beam 32 irradiated onto the laser beam monitor 10 is observed from outside the vacuum chamber 2 through the viewing window 28 to determine whether the direction of the laser beam 32 is tilted with respect to the optical axis of the lens system. This determination is made using the beam axis set on the surface of the monitor 10.
・This can be done by looking at the positional relationship of 34. That is the optical axis): l Ep 3
This is because the lens 3 is located at a distance of J3 on the optical axis of the lens system.

FIG. 3(A) shows a case where the direction of the laser beam 32 coincides with the optical axis of the lens system. If the direction of the laser beam 32 coincides with the optical axis of the lens system, it can be said that adjustment in the θ direction is not necessary. However, such cases where adjustment in the θ direction is not necessary are extremely rare, and usually the direction of the laser beam 32 is not parallel to the optical axis of the lens system, as shown in FIG. Therefore, the beam spot 34 is located off-center from the optical axis mark 33. In such a case, θ of ion gun 1
This means that some direction adjustment is required. Furthermore, the third [
In the main 1, Pl is the position of the tip of the emitter 7 (the end T in the O direction after the alignment of the ion gun 1 in the X and Y directions is completed).
Of course, this position exists in the light 11qlIL of the lens system.

(4) Next, the θ direction adjuster 25. ．． 25. ．． 251. By appropriately turning the ion gun 1, the ion gun 1 is moved in the θ direction so that the laser beam 34 substantially overlaps the optical axis 1 mark 33 as shown in the fourth mark 1. Then, the direction of the laser beam 32 becomes approximately parallel to the light 1 of the lens system. In Fig. 4, P2 is the emitter 7 after alignment in the θ direction.
This is the position of the tip (position in the X direction and Y direction).

(5) By the way, as described above, the alignment in the θbj direction is '11' and the position of the tip of the emitter 7 that generates the laser beam in the X and Y directions is displaced from Pl to P2. Therefore, the amount of displacement P2-PL (X2-X
I, Y2-Yl) It is necessary to move the ion gun 1 in the X and Y directions so that the tip of the emitter 7 is located on the optical axis of the lens system. Conventionally, this was done by moving it in the X and Y directions randomly, which took time and made it difficult to achieve accurate alignment. However, in the present invention, the above θ・X correlation coefficients a, , a2, a3 and θ−
Y correlation coefficient b+, b2t b3, and each θ direction adjuster 25+, 252.2!53 during θ direction alignment
Adjustment amount ΔT 1. Displacement amount P2- from ΔT2 and ΔT3
Displacement amount ΔX of PI outside the X direction and displacement amount ΔY outside the Y direction
It is calculated by using the - notation. The above formula is repeated here as follows.

ΔX=a, ΔT, +a, ΔT, +a, ΔT3ΔY=b,
ΔT, b2ΔT2+b3ΔT1 and the obtained ΔX
(i.e., X2-Xi) and ΔY (i.e., Y2-Yl), the ion gun 1 is moved along the X direction and the Y direction in a direction to eliminate the deviation. Then, as shown in FIG. 5, the tip of the emitter 7 is positioned on the optical axis of the lens system. By calculating the amount of deviation and moving the ion gun 1 by the amount of deviation, alignment can be performed quickly and accurately.

6) Next, as shown in FIG. 6, the ion beam monitor 10 is moved from the path of the laser beam so that the laser beam is incident on the lens system. Then, check whether the laser beam has passed through the hole 35 of the electrode 11 to the lower side, and then fine-tune the position in the X and Y directions without measuring the ion beam current. . This means that ΔX, ΔY obtained by the above calculation
There is room for an error of about 70 degrees, so ±0.1
Since there may be errors north of mm, fine adjustments are made. This can be done easily. At this time, if necessary (if the ion beam does not reach between the workpieces 18 because the deviation is larger than 10.1 mm), the electric field is increased to about 5 V/input by increasing the extraction voltage. It is also possible to widen the radiation angle of the beam 32 as shown by the two-dot chain line. This is because if the ion beam 32 is widened in this way, the beam can reach the workpiece 18 and the beam current can be measured, making it easier to make fine adjustments.

After that, the electric field was returned to 3V/person and the final adjustment was made. In this case, it is preferable to adjust the direction of the ion beam using the alignment electrode 11. This completes the series of alignments.

(Effects of the invention H) As described above, the ion beam alignment method of the focused ion beam device of the present invention is capable of adjusting the position of the tip of the ion gun that generates the ion beam with respect to the amount of adjustment in the θ direction of the focused ion beam device. Determine the ratio of displacement in the X and Y directions in advance, and then adjust the position of the ion gun in the X and Y directions so that the tip of the ion gun is located on the optical axis of the lens system of the focused ion beam device. Then,
The position in the θ direction was adjusted so that the ion beam generated from the ion gun was parallel to the optical axis of the lens system of the focused ion beam device, and the θ direction was adjusted so that the ion beam was parallel to the optical axis of the lens system. The current adjustment amount is multiplied by the above ratio to calculate the deviation meter in the X and Y directions in the θ direction, and if the ion gun is not satisfied, the ion gun is returned to the direction opposite to the deviation. It is something to do.

Therefore, according to the -r on-beam alignment method of the focused ion beam device of the present invention, after aligning the ion gun's ion beam emitting tip in the X and Y directions, the ion gun is aligned in the θ direction. By calculating the amount of sh in the X and Y directions caused by alignment, it is possible to correct the deviation more quickly and accurately than in the conventional case where it is done by guessing.

[Brief explanation of drawings]

1 to 6 show one embodiment of the ion beam alignment method of the focused ion beam device of the present invention in the order of steps. FIG. 2 is a perspective view for explaining the ratio of the amount of deflection, that is, the correlation coefficient; FIG. 2 is a sectional view for explaining the initial alignment of the ion pan 1 in the X and Y directions; FIG. 3 (A) , (B) are perspective views showing two examples of the orientation of the ion beam after initial alignment in the X and Y directions, and (A) shows the case where the orientation of the ion beam is correct. B) shows the case where the ion beam is tilted, Figure 4 is a perspective view showing the direction of the ion beam after alignment in the θ direction, and Figure 5 shows the orientation after realignment in the X and Y directions. 6 is a perspective view showing the state of incidence on the lens system, FIG. 7 is a sectional view showing a focused ion beam device for explaining the background art, and FIG. 8 is an explanatory diagram of the problem. It is. Explanation of symbols 1...-Ion gun, 7...Ion beam generation section (emitter), 19...
Manipulator, 32...Ion beam.

Claims (1)

[Claims] (1) An ion beam alignment method for a focused ion beam device in which the position of an ion gun suspended from the ceiling of a vacuum chamber can be adjusted in at least the X, Y, and θ directions using a mammupillator installed above the vacuum chamber. , the ratio of the displacement amount in the X and Y directions of the tip position of the ion gun that generates the ion beam to the adjustment amount in the θ direction of the focused ion beam device is determined in advance, and first, the tip of the ion gun is aligned with the lens of the focused ion beam device. Adjust the position of the ion gun in the X and Y directions so that it is on the optical axis of the system, and then adjust the position in the θ direction so that the ion beam generated from the ion gun is parallel to the optical axis of the lens of the focused ion beam device. Adjust the position,
Calculate the amount of deviation in the X and Y directions due to the adjustment in the θ direction by multiplying the adjustment amount when adjusting the θ direction so that the ion beam is parallel to the lens optical axis by the above ratio, and adjust the ion gun by the amount of deviation above. , an ion beam alignment method for a focused ion beam device characterized by returning the ion beam in the Y direction in the opposite direction to the deviation.