JP3117783B2 - Driving device for deflector in electron microscope etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving a deflector in an electron microscope, an electron beam lithography apparatus, etc., and more particularly to a deflection device capable of switching between a shift operation and a tilt operation using a two-stage deflector. The present invention relates to a device for driving a vessel.

[0002]

2. Description of the Related Art It is well known that a shift operation and a tilt operation are switched by using a deflector in an electron microscope or the like. The shift operation is to move an electron beam irradiation point on the sample surface to move, for example, an analysis point. Further, the tilt operation is to change the irradiation direction while fixing the electron beam irradiation point on the sample surface. When the shift operation and the tilt operation are performed by disposing a deflector at a stage before the objective lens, it is necessary to make the electron beam pass near a point conjugate with the front focal point of the objective lens for the shift operation. In addition, for the tilt operation, the electron beam must pass through a point where the optical axis intersects with a plane conjugate with the sample plane. Hereinafter, these points will be referred to as cross points, and the beam path emerging from this cross point will be referred to as a ray path.

Conventionally, when the electron beam is deflected by a two-stage deflector, when the beam is deflected by an angle θ ₁ by the first deflector, the beam deviates from the ray path by that amount. Swing back by angle θ ₂ so as to pass through the ray path. Simultaneously performing this operation is called interlocking. In interlocking, the excitation current applied to the main deflector is attenuated by an appropriate amount and applied to the subordinate deflector, so that the main deflector is deflected. It is common for the angle to be greater than the deflection angle of the corresponding deflector. Conventionally, the first deflector is mainly used,
Switching from the shift operation to the tilt operation or from the tilt operation to the shift operation while satisfying the relationship of θ ₁ > θ ₂ with the second deflector as a slave, The switching operation between the shift operation and the tilt operation is performed while satisfying the relationship of θ ₁ <θ ₂ with the deflector as a slave.

This will be described with reference to FIGS. 2 and 3. FIG. 2 shows a ray path of an electron beam in a shift operation, and FIG. 3 shows a ray path of an electron beam in a tilt operation. (A) of each drawing is a case where the deflection angle θ ₂ by the second deflector is larger than the deflection angle θ ₁ by the first deflector, and (b) of each drawing is a case where the deflection angle θ ₁ by the first deflector is. This is the case where the deflection angle by the second deflector is larger than θ ₂ . In each figure, an electron beam emitted from an electron gun (not shown) is converged by a condenser lens CL, deflected via a first deflection coil D1 and a second deflection coil D2, and travels as if coming out of a cross point P. The sample S is irradiated onto the sample S by the mini lens CM and the objective lens OL. Conventionally, as described above, between FIG. 2 (a) and FIG.
Alternatively, the shift operation and the tilt operation could be switched between FIG. 2 (b) and FIG. 3 (b), but between FIG. 2 (a) and FIG. 3 (b) or FIG. 2 (b). Switching between the shift operation and the tilt operation between FIG. 3A and FIG.

[0005]

As described above, when an electron beam is deflected by a two-stage deflector, conventionally, an interlocking shift operation in which a first deflector is mainly used and a second deflector is used. Or, from the tilt operation, the first
In some cases, it is difficult to switch to a tilt operation or a shift operation in an interlocking relationship with a deflector as a slave.
Therefore, depending on the excitation state of the condenser mini-lens and the like, there are positions and angles where shifting or tilting is not possible.

The present invention has been made in view of such circumstances, and a purpose thereof is to provide a shift operation in a deflector such as an electron microscope which switches between a shift operation and a tilt operation by using a two-stage deflector. It is an object of the present invention to provide a driving device for a deflector in which the main deflector can be switched at the same time when the tilt operation and the tilt operation are switched.

[0007]

A deflector driving apparatus in an electron microscope or the like according to the present invention for achieving the above object has a two-stage deflector for performing a shift operation and a tilt operation, and selectively performs both operations. In an apparatus for driving a deflector in an electron microscope or the like, the excitation current flowing through the first deflector is attenuated in accordance with a parameter set by the first interlocking data setting means to reduce the excitation current to the excitation current of the second deflector. A first switch for adding and supplying, and an excitation current flowing through the second deflector, which is attenuated according to a parameter set by the second interlocking data setting means, and added to and supplied to the excitation current of the first deflector. A second switch unit; and a control unit for selectively operating one of the first switch unit and the second switch unit. The interlocking relationship between the first deflector and the second deflector can be reversed. It is characterized in that the configuration was.

[0008]

In the present invention, the first switch which attenuates the exciting current flowing through the first deflector according to the parameter set by the first interlocking data setting means and adds it to the exciting current of the second deflector and supplies the first switch. Means, and second switch means for attenuating the exciting current flowing through the second deflector in accordance with the parameter set by the second interlocking data setting means and adding it to the exciting current of the first deflector for supply. First switch means,
Since the control means for selectively operating either one of the second switch means is provided, the interlocking relation between the first deflector and the second deflector can be easily reversed, and the switching is performed by switching between the shift operation and the tilt operation. By performing the operations at the same time, the degree of freedom of shifting and tilting increases, and the positions and angles at which shifting and tilting can be performed increase. In addition, how to take the link,
For example, setting and changing can be easily performed by setting the exciting current data and the interlocking data by the CPU.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A deflector driving apparatus according to the present invention will be described below with reference to an embodiment shown in FIG. When a deflection coil is used as an electron beam deflector, the first
The following two methods are conceivable for swinging back the deviation from the ray path by the deflector by the second deflector.

(1) The winding direction of the second deflection coil is reversed with respect to the first deflection coil. (2) The direction of the current flowing through the second deflection coil is reversed with respect to the first deflection coil.

In the circuit of FIG. 1, the circuit is configured by the method (1).

The deflector driven by the deflector driving device shown in FIG. 1 comprises two-stage deflection coils D1 and D2 as shown in FIGS. 2 and 3, each of which is an x-direction deflection coil D1 _x , D2 _x, consisting of y deflection coils D1 _y, D2 _y. Output currents V _1x , V _1y , V _2x from the adders 5, 6, 7, 8 are respectively applied to the coils D1 _x , D1 _y , D2 _x , D2 _y .
V _2y is flowed. By the way, from the CPU 10, the memory 1
The deflection coil main excitation data N _{1 to} N ₄ , the interlocking data α _{1 to} α ₄ and the switch control data stored in
D / A converters are sent to terminals A to D, respectively. Here, N ₁ : main excitation data to the x-direction deflection coil D1 _{x of} the first deflection coil N ₂ : main excitation data to the y-direction deflection coil D1 _{y of} the first deflection coil N ₃ : x of the second deflection coil Main excitation data for the directional deflection coil D2 _x N ₄ : Main excitation data for the y-direction deflection coil D2 _{y of} the second deflection coil α ₁ : Interlocking data of the deflection coil D2 _x with respect to the deflection coil D1 _x α ₂ : deflection coil D1 deflection for _y coils D2 _y of the linked data alpha _3: Integration deflection coils D1 _x for deflection coil D2 _x data alpha _4: a linked data of deflection coils D1 _y against deflection coils D2 _y.

The data N ₁ converted into an analog signal by the D / A converter is input to one terminal of an adder 5, and the data N ₁ converted into an analog signal by the D / A converter in the multiplier ₁ is added to the data N _1. The result is multiplied, arithmetically amplified, and -α ₁ N ₁ is input to the ON terminal of the switch S1. Similarly, one terminal of the adder 6 has N ₂ , the ON terminal of the switch S2 has −α ₂ N ₂ , and the one terminal of the adder 7 has N 2.
₃ is connected to the ON terminal of the switch S3, -α ₃ N ₃ , and one terminal of the adder 8 is connected to N _4.
-Α ₄ N ₄ is input to the N terminal. Outputs from the switches S1 to S4 are input to the other terminals of the adders 5 to 8, respectively.

Therefore, when the control data applied to the switches S1 to S4 are all zero, the switch S
Since 1 to S4 are OFF and zero is input to the other terminals of the adders 5 to 8, the outputs V _1x , V _1y , V _2x and V _2y of the adders 5 to 8 are N ₁ , N ₂ , N ₃ ,
N _4, and the respective coils of the deflection coil D1, D2 of the two-stage _{D1 x, D1 y, D2 x} , D2 y mainly exciting data N _1, N _2, N _3, N ₄ by separately and independently to the excitation drive Will be done.

On the other hand, the switches S1 and S2 are turned on.
When the switches S3 and S4 are OFF (A, B... 1,
C, D... 0), that is, when the first deflection coil D1 is driven independently and the second deflection coil D2 is driven in conjunction, V _1x = N ₁ , V _1y = N ₂ , V _2x = N ₃ -2α ₁ N ₁ , V
_2y = N ₄ -2α ₂ N ₂ where, for simplicity, N = N ₁ = N ₂ = N ₃ = N ₄ ,
If α = α ₁ = α ₂ (0 ≦ α ≦ 1), then | V _2x / V _1x | = | (1-2α) N / N | ≦ 1 | V _2y / V _1y | = | (1- 2α) N / N | ≦ 1, and both coils D2 _x and D2 _{y of} the second deflection coil D2
Is applied to both coils D of the first deflection coil D1.
1 _x, becomes smaller than the current flowing in D1 _y, the deflection angle theta ₁ of the first deflection coil D1 is greater than the deflection angle theta ₂ of the second deflection coil D2. Therefore, the interlocking relationship in which the first deflection coil D1 is mainly used and the second deflection coil D2 is used is satisfied.

Next, when the switches S1 and S2 are turned off and the switches S3 and S4 are turned on (A, B... 0, C, D
.. 1), that is, when the second deflection coil D2 is driven independently and the first deflection coil D1 is driven in conjunction with it, V _1x = N ₁ -2α ₃ , V _1y = N ₂ -2α ₄ , V _2x =
N ₃ , V _2y = N ₄ Here, for simplicity, similarly, N = N ₁ = N ₂ = N ₃ =
Assuming that N ₄ and α = α ₁ = α ₂ (0 ≦ α ≦ 1), | V _2x / V _1x | = | N / {(1-2α) N} | ≧ 1 | V _2y / V _1y | = | N / {(1-2α) N} | ≧ 1, and both coils D of the first deflection coil D1 are
Current flowing in 1 _x, D1 _y is smaller than the current flowing in both coils D2 _x, D2 _y of the second deflection coil D2,
Deflection angle theta ₁ of the first deflection coil D1 is smaller than the deflection angle theta ₂ of the second deflection coil D2. Therefore, the interlocking relationship in which the second deflection coil D2 is mainly used and the first deflection coil D1 is used is satisfied.

In summary, by changing the control data input to the terminals A to D of the switches S1 to S4, the interlocking relationship between the first deflection coil D1 and the second deflection coil D2 is changed as shown in the following table. Can easily be reversed, and this interlocking relationship can be eliminated.

[0018] Therefore, in an electron microscope or the like using the two-stage deflectors D1 and D2, the shift operation shown in FIG. 2A and the tilt operation shown in FIG. 3B, and the shift operation shown in FIG.
(A) It is possible to easily switch between the tilt operations, thereby increasing the degree of freedom of the shift and the tilt, and increasing the position and angle at which the shift and the tilt can be performed.

In the embodiment shown in FIG. 1, the CPU 1
From 0, the deflection coil main excitation data N _{1 to} N ₄ and the interlocking data α _{1 to} α ₄ are input using the D / A converter. However, the present invention is not limited to this, and the voltage can be set arbitrarily. If any (for example, a potentiometer), any of them may be used.

Although the driving device of the deflector in the electron microscope and the like according to the present invention has been described based on the embodiments, the present invention is not limited to these embodiments, and various modifications are possible.

[0021]

As is apparent from the above description, according to the deflector driving apparatus in the electron microscope and the like of the present invention, the exciting current flowing through the first deflector is changed to the parameter set by the first interlocking data setting means. A first switch means for attenuating the exciting current to be added to the exciting current of the second deflector and supplying the exciting current to the second deflector; A second switch for supplying the excitation current to the first deflector in addition to the excitation current, and a controller for selectively operating either the first switch or the second switch.
The interlocking relationship between the deflector and the second deflector can be easily reversed, and the switching is performed at the same time when the shift operation and the tilt operation are switched, so that the degree of freedom of the shift and the tilt is increased, and the position and angle at which the shift and the tilt can be performed are increased. To increase.
In addition, how to set the linkage can be easily set and changed by setting the excitation current data and the linkage data by the CPU, for example.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an embodiment of a driving device for a deflector according to the present invention.

FIG. 2 is a diagram showing ray paths of an electron beam during a shift operation.

FIG. 3 is a diagram showing ray paths of an electron beam during a tilt operation.

[Explanation of symbols]

CL: condenser lens D1: first deflection coil D2: second deflection coil P: cross point CM: condenser mini lens OL: objective lens S: sample D1 _x : x-direction deflection coil of first deflection coil D1 _y : first deflection coil in the y-direction deflection coils D2 _x ... second deflection coils in the x-direction deflection coil D2 _y ... second deflection coil y deflection coils 1-4 ... multiplier 5-8 ... adder 10 ... CPU 11 ... memory ~ ... D / A converters S1 to S4 ... switches A to D ... terminals

Claims (1)

(57) [Claims] 1. A deflector driving device for an electron microscope or the like which includes a two-stage deflector for performing a shift operation and a tilt operation, and which can selectively switch both operations, an excitation flowing to the first deflector. A first switch for attenuating the current in accordance with the parameter set by the first interlocking data setting means and adding the current to the exciting current of the second deflector; A second switch for attenuating according to the parameter set by the data setting unit and supplying the attenuated current to the first deflector, and selecting one of the first switch and the second switch. A driving device for a deflector in an electron microscope or the like, characterized by comprising control means for operating the first deflector and the interlocking relationship between the first deflector and the second deflector.