JP3145491B2 - Electron beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus, and more particularly, to arranging a large number of microemitters (also referred to as minute field emission cathodes) in a plane and irradiating radiated electrons from each microemitter to, for example, a semiconductor. A micro-emitter with a small field emission cathode array that irradiates the light-emitting surface of a flat panel display, for example, an electron beam device provided with a plane electron source (hereinafter referred to as a multi-electron beam source) called a Spindt-type cold cathode The present invention relates to an array rescue technique including:

[0002]

2. Description of the Related Art Recently, electron beam apparatuses such as an electron beam drawing apparatus and an electron beam inspection apparatus using a sharp electron beam have been used for producing and inspecting a fine circuit pattern of an VLSI. For example, an electron beam lithography apparatus generates a deflection voltage based on arbitrary exposure data and applies the deflection voltage to a deflector, thereby deflecting and scanning the electron beam freely, as if by a single brush. An arbitrary pattern is formed on the surface of the sample (chip) by drawing.

In such an existing apparatus, a large amount of time is required for drawing because one electron beam is used, and when a large area is to be drawn, the drawing process is performed while sequentially moving the scanning area. It is necessary to perform a so-called step-and-repeat such as repeating the above, which is not satisfactory in terms of throughput. As a device for compensating for such a drawback, an electron beam device (hereinafter referred to as a conventional device) provided with a multi-electron beam generating source in which a large number of fine electrodes are arranged in a matrix has attracted attention.

FIG. 9 is a sectional view of a main part of the multi-electron beam generating source. A large number of electron emitters 2 are formed on the substrate 1 by pairing a fine electrode 2a having a sharp tip and a gate 2b arranged so as to surround the tip of the fine electrode 2a. A large number of electron beams 3 extracted from the electron emitter 2 pass through the focusing electrode, the deflection electrode 4 and the like, and are simultaneously irradiated on the surface of the sample 5.

[0005] A detector 6 for detecting reflected electrons or secondary electrons from the sample 5 (hereinafter, represented by reflected electrons) is attached near the exit of each electron beam 3. The state of the irradiation area for each electron beam 3 can be observed on the basis of the signal from 6. In this apparatus, since a large area can be processed at a time by simultaneously irradiating a large number of electron beams 3, the throughput can be remarkably improved.

[0006]

However, in such a conventional multi-electron beam generation source, as shown in FIG. 10, a large number (for example, N
The electron beam 3 (shown by black circles) from the (× M) electron emitters 2 is used to form an irradiation region having an area corresponding to N × M on the surface of the sample 5. If even one unit 2 becomes defective, there is a problem that a defective portion occurs in the irradiation area.

Further, a large number of electron emitters 2 and a portion for converging or deflecting the electron beam 3 from the emitter 2 (a portion including the converging electrode and the deflecting electrode 4; generally a lens barrel) are integrated. Therefore, if even one electron emitter section 2 malfunctions, the entire multi-electron beam generation source must be replaced in its entirety, resulting in a problem of high maintenance cost. [Purpose] A first object of the present invention is to make it possible to relieve defects by optimizing the number of electron emitters, thereby avoiding the occurrence of defects in an irradiation area due to a malfunction of the electron emitters.

A second object of the present invention is to reduce the maintenance cost by coping with the failure of the electron emitter section with the minimum necessary parts replacement.

[0009]

According to the present invention, in order to achieve the first object, a multi-electron beam is formed by arranging a large number of electron emitters 10 in a matrix as shown in FIG. An irradiation area 12 of a sample, which constitutes a source 11 and is arranged to face the multi-electron beam source 11
And in an electron beam apparatus for irradiating by sharing each of the electron beam from the electron emitter 10, the irradiation
The emission region 12 has an area of N × M electron emitters 10.
When the size is appropriate, the multi-electron beam source
11 is composed of n × m electron emitter sections 10, wherein n and m are values corresponding to at least twice each of N and M.

In order to achieve the second object,
A large number of electron emitters are arranged in a matrix
A multi-electron beam generation source.
The irradiation area of the sample placed opposite to the source is
Irradiation by sharing with each electron beam from the mitter
An electron beam apparatus, wherein the multi-electron beam generation source comprises: a first structural part including at least an electron emitter;
The electron beam from the electron emitter is converged and deflected into two parts and a second structural part including N × M lens barrels, and the relative positional relationship between the first and second structural parts is changed. It is characterized by being configured to be possible.

[0011]

When any one of the n × m electron emitters is malfunctioning, the multi-electron beam source 11 (or sample) depends on the position of the malfunctioning electron emitter.
Is moved in the x and y directions, the processing of the region 12 by the normal N × M electron emitters becomes possible.

Further, since the number of the lens barrels included in the second structural portion is N × M, which is the same as the irradiation area, no waste occurs in the lens barrels. Moreover, when the N × M irradiation area cannot be secured due to the failure of the electron emitter section included in the first structure, only the first structure needs to be replaced, and the maintenance cost can be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 2 to 6 show an embodiment of the electron beam apparatus according to claims 1 and 2 of the present invention. In addition,
In the following description, n, m, N and M are integers,
n is at least twice as large as N (that is, n ≧ 2N), m
Is a number corresponding to at least twice as large as M (that is, m ≧ 2M).

In FIG. 2, an electron beam device 20 includes a multi-electron beam generating source 21 having a large number (N × M) of electron emitters (see reference numeral 2 in FIG. 9) arranged in a matrix. A power supply unit 22 including a plurality of (N × M) power supply circuits for generating various voltages (emitter electrode voltage, gate voltage, focusing voltage, deflection voltage, etc.) necessary for the electron emitter unit, A signal processing unit 23 including a plurality of (N × M) signal processing circuits for processing detection signals from the provided detector (see reference numeral 6 in FIG. 9);
The multiplexer 24 includes a multi-electron beam source 2 according to a predetermined address signal.
N × M pairs of the n × m power supply / signal lines La from 1 are selected, and the selected power supply / signal lines La ′ are
N × M sets of power lines Lb (for example, one set for emitter electrode voltage, gate voltage, focusing voltage and deflection voltage) from the power supply unit 22 and N × M sets of signal lines L from the signal processing unit 23
c (for example, one set for signal transmission and control).

Here, assuming that coordinates (x, y) are given to each of the n × m electron emitter sections, the power supply / signal line La is connected from La _{(1, 1)} to La _{(n, m)} . n × m pairs, of which N × M pairs of La
To Lb and Lc. Each set of La includes one set of Lb and Lc. The hatched area 21a described in the frame of the multi-electron beam source 21 is as follows.
The figure shows N × M electron emitter sections (hereinafter referred to as “electron emitter groups”) selected by the multiplexer 24, and the area of this area 21a is substantially equal to the area of the electron beam irradiation area on the sample surface (not shown).

FIG. 3 is a conceptual diagram of an irradiation area and a multi-electron beam generation source. By the selection operation of the multiplexer 24, the position of the electron emitter group can be shifted, and can correspond to the irradiation area. Now, as shown in FIG.
When one of the electron emitters (indicated by a white circle) malfunctions, a multiplexer 24 outputs a preferred selection address signal corresponding to the coordinate position of the malfunctioning electron emitter.
, It is possible to arbitrarily shift the position of the electron emitter group composed of the N × M electron emitter portions (that is, the electron beam irradiation region on the sample surface).

The area (corresponding to n × m) of the electron emitter section constituting the multi-electron beam generation source is defined as “n ≧ 2N”.
From the relationship of “m ≧ 2M”, the area is set to at least four times or more the area of the electron beam irradiation region (corresponding to N × M). By doing so, the electron emitter group can be moved to an appropriate position without being limited to the position of the malfunctioning electron emitter portion, and the occurrence of defects in the irradiation area can be avoided reliably.

FIG. 5 is a diagram showing the relationship between the position of the electron emitter group selected by the multiplexer 24 and the irradiation area. The hatched portion is the position of the electron emitter group. The position of the electron emitter group can be appropriately shifted while avoiding the malfunctioning electron emitter section. Note that the illustrated irradiation area (the area indicated by the broken line) has a larger area than the emitter group, but may have the same area. Incidentally, when the irradiation area is large, the electron beam irradiation is repeated while the position of the multi-electron beam is moved stepwise from the initial position (the position shown).

In the case where the irradiation area is divided into a plurality of columns and step-and-repeat is repeated for each column,
As shown in FIG. 6, the number of the electron emitter sections 31 constituting the multi-electron beam generation source 30 may be A × M ′, and the rows of the electron emitter sections including the malfunctioning electron emitter sections may be replaced. Here, when the size of the irradiation area is N × M, A is a number of 2 to 2 or more, and M ′ is the same number as M or an integer multiple of M.

FIGS. 7 and 8 show the third and fourth aspects of the present invention.
FIG. 9 is a view showing an embodiment of the electron beam apparatus according to the present invention. In the following description, portions common to the embodiment of the electron beam apparatus according to the first and second aspects will be denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 7 is a structural diagram of a main part of the multi-electron beam source, and a schematic block diagram of a drive system, a detection system, and a control system thereof.

Reference numeral 40 denotes a substrate on which a matrix-shaped X electrode (not shown) is formed on the lower surface. Reference numeral 41 denotes a metal such as silicon or Ta arranged on the X electrode at a fine pitch.
A large number of fine electrodes (hereinafter referred to as electron emitters; representatively, one) made of valence lanthanum, etc., 42 is a spacer, 43 is an electron beam 44 having a beam current of a magnitude corresponding to a given electrode voltage Is a gate as an extraction electrode (Y electrode) that draws out from the electron emitter section 41. These elements constitute a first structural portion 45 as one body, and are detachably attached to, for example, a socket (not shown). The first structural section 45 is given a large degree of freedom by the first drive mechanism 46, and for example, a total of two horizontal orthogonal axes (X axis, Y axis) and one axis (Z axis) around the origin. A total of six axes of freedom are given, including three axes, and preferably three axes of rotation about these three orthogonal axes.

Reference numeral 47 denotes a focusing electrode which generates an electric field corresponding to the electrode voltage to converge the electron beam 44, 48 denotes a deflecting electrode which generates an electric field corresponding to the electrode voltage and applies a deflection angle to the electron beam 44, and 49 denotes a sample. This is a detector that captures reflected electrons 51 (or secondary electrons) emitted from the surface of 50 and converts them into an electric signal 52. In addition, other electrodes (the anode 53, the first
The ground electrode 54 and the second ground electrode 55 are used to assist the function of the gate 43 or to form an electric field distribution that converges electrons with the focusing electrode 47.
The same potential (eg, ground potential) is applied to these other electrodes. The above focusing electrode 47 and deflection electrode 4
8, the detector 49 and the other electrodes form a so-called lens-barrel portion using a predetermined material 56 having non-dielectric and insulating properties as a holder, and constitute a second structural portion 57 as a whole. The second structure portion 57 is attached to a chassis or a structure of an electron beam device (not shown),
In order to give degrees of freedom about axes (X axis, Y axis), they are mounted via a second drive mechanism 58.

Reference numeral 59 denotes a signal processing circuit for processing an electric signal from the detector 49 to generate observation data 60 representing the state of the sample surface, and 61 drives an XY stage (not shown) on which the sample 50 is mounted. The third driving mechanism 62 generates various voltages to be applied to the first and second structural parts 45 and 57, and the first to third driving mechanisms 46, 58 and 61.
Control data 63 to 65 for the observation data 60
Is a controller generated based on

Here, the number of the electron emitter portions 41 of the first structure portion 45 is n × m, which is larger than N × M corresponding to the size of the irradiation area, and N × M are selected. (See FIG. 3). Here, n is an integer corresponding to at least twice N or more (ie, n ≧ 2N), and m is an integer corresponding to at least twice M or more (ie, m ≧ 2M).

When a failure * occurs in the electron emitter 41 in use, N × M electron emitters 41 other than the failed electron emitter 41 are newly selected to recover the failure. As the number of defective electron emitters 41 increases, it becomes impossible to secure N × M regions only with normal electron emitters 41. * The cause of the failure is mainly due to the destruction of the electron emitter section 41, and other components, such as those caused by the lens barrel, occur very rarely. It is considered that this is because the shape of the electron emitter 41 easily changes greatly due to ion bombardment and the like, and the electric field concentrates on the deformed portion to increase the electric field emission current. On the other hand, since the current density of the electron beam is considerably low in the lens barrel and the like, an obstacle such as causing melting and becoming unusable rarely occurs.

As described above, in this embodiment, the electron emitter section 41 having the highest probability of failure (or having the shortest life) is provided.
Is separated from the first structure 45 including the lens barrel which hardly breaks down, so that N × M areas are secured only by the normal electron emitter 41 as described above. If it becomes impossible, the device can be restored only by replacing the minimum necessary components, that is, the first structural portion 45, and the maintenance cost of the electron beam device can be reduced.

Since the first structural part 45 and the second structural part 57 are separated, accurate alignment between the axis of the electron beam 44 and the center axis of the lens barrel is required. If the positioning accuracy is about 0.1 mm, a ball screw method or a V-groove guide method driven by a stepping motor or a DC motor is sufficient, but in order to satisfy the accuracy of 0.1 μm or less, an STM (scanning tunneling microscope) is required. It is effective to use a piezoelectric driving method that has been proven in the above. For example, as shown in FIG. 8, a first structure 45 is mounted on a stage 63 driven by a ball screw system or a V-groove guide system via a Z-axis piezoelectric actuator 64, and a parallel position is set on the stage 63. The second structural portion 57 is attached via the piezoelectric actuator 65 for use. In addition, 66 is a frame for holding the second structural portion 57. According to this, the positioning up to about 0.1 mm can be performed by moving the stage 63 , and further fine positioning can be performed by the piezoelectric actuators 64 and 65.

It is desirable to evaluate the alignment as follows. That is, at least an arbitrary position on the XY stage on which the sample 50 of FIG. 7 is mounted, specifically, a position other than the mounting surface of the sample 50 and a position where multi-electron beam irradiation is possible. A reference plane having an area of N × M is formed, and the amount of reflected electrons or secondary electrons from this reference plane is detected by N × M detectors 49. If the reference reference surface is formed of the same material (for example, a heavy metal film such as tantalum having a high generation efficiency of reflected electrons and secondary electrons), and the entire surface is uniformly finished, as long as the alignment is accurate, N A uniform observation with an area of × M should be obtained. If a variation is observed, the first structural unit 4 is designed to eliminate the variation.
What is necessary is just to adjust the relative positional relationship between 5 and the 2nd structure part 57.

Although the spot diameter of the electron beam must be a perfect circle, it is conceivable that the electron beam is deformed into an ellipse by separating the first structure 45 and the second structure 57 from each other. The spot diameter of the electron beam is X
At an arbitrary position on the Y stage, a reference pattern made of two kinds of materials having different generation efficiencies of reflected electrons or secondary electrons can be formed, and it can be observed from the output of the detector 49 when the reference pattern is crossed. Therefore, correction from an ellipse to a perfect circle is easily possible.

By the way, according to these two evaluation methods,
Not only the alignment and the adjustment of the spot diameter, but also the loss of the multi-electron beam (that is, the failure of the electron emitter section 41) can be easily detected, so that the automatic determination of the failure state (the automatic replacement of the electron emitter section 41) is also possible. In addition, it is possible to provide an electron beam apparatus that does not bother the operator every time a failure occurs.

[0031]

According to the present invention, since the number of electron emitters is optimized, defect remedy can be achieved, and the occurrence of defects in the irradiation area due to malfunction of the electron emitters can be avoided.
In addition, it is possible to cope with a failure of the electron emitter section by the minimum necessary component replacement, and it is possible to reduce the maintenance cost.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the invention according to claim 1 and claim 2;

FIG. 2 is a configuration diagram of an embodiment according to the first and second aspects of the present invention.

FIG. 3 is a conceptual diagram of an irradiation region and an electron emitter group according to an embodiment of the present invention.

FIG. 4 is a diagram showing a group of electron emitters shifted in position in one embodiment according to the first and second aspects of the present invention;

FIG. 5 is a diagram showing a relationship between a position of an electron emitter group and an irradiation area according to an embodiment of the present invention.

FIG. 6 is a diagram showing a preferred embodiment in the case where step and repeat are performed for each column according to the first and second aspects of the present invention.

FIG. 7 is a structural view of a main part of a multi-electron beam generating source according to the third, fourth and fifth aspects of the present invention, and a schematic block diagram of a drive system, a detection system and a control system thereof.

FIG. 8 is a preferred mounting structure diagram of the first structure portion and the second structure portion according to the third, fourth, and fifth aspects of the invention.

FIG. 9 is a cross-sectional view of a conventional multi-electron beam generation source.

FIG. 10 is a diagram showing a relationship between an electron emitter section and an irradiation area in a conventional example.

[Explanation of symbols]

 10: Electron emitter 11: Multi-electron beam generator 12: Irradiation area 45: First structure 57: Second structure

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H01L 21/30 541W (58) Investigated field (Int.Cl. ⁷ , DB name) H01L 21/027 H01J 37/06

Claims (5)

(57) [Claims] 1. A multi-electron beam source is formed by arranging a large number of electron emitter sections on a matrix, and an irradiation area of a sample placed opposite to the multi-electron beam source is defined by the electron emitter section. In the electron beam apparatus for irradiating the electron beam in a shared manner with each of the electron beams, the irradiation area corresponds to the area of N × M electron emitter sections.
The size of the multi-electron beam generator is n × m electron emitters.
Constructed in parts, the electron beam device n and m, which is a value corresponding to at least each of more than two times of the N and M. 2. The method according to claim 1, wherein the irradiation area is N × M electron emitters.
When the size of the multi-electron beam source is A × M ′,
Constituted by data unit, A is a number of at least 2 or more, and, M 'is an electron beam apparatus according to claim 1, characterized in that the number of an integral multiple of the M and equal to or M. 3. A plurality of electron emitters arranged in a matrix.
Array to form a multi-electron beam source,
Irradiation area of sample placed opposite to beam source
With the respective electron beams from the electron emitter section.
In the electron beam apparatus for sharing and irradiating, the multi-electron beam generating source is composed of a first structure section including at least an electron emitter section, and N × M lens barrels for converging and deflecting an electron beam from the electron emitter section. The electron beam apparatus according to claim 1, wherein the electron beam apparatus is divided into a second structure part including a part and a relative positional relationship between the first and second structure parts is changeable. 4. A reference reference surface having an area approximately equal to the irradiation area according to claim 1 or 2 at an arbitrary position on an XY stage on which a sample is mounted. 4. The electron beam apparatus according to claim 3, wherein a positional relationship between the first structure and the second structure is adjusted based on an output of a detector for detecting a secondary electron. 5. A reference pattern made of two kinds of materials having different generation efficiency of reflected electrons or secondary electrons is provided at an arbitrary position on an XY stage on which a sample is placed, and reflected electrons or secondary electrons from the reference pattern are provided. 4. The convergence amount and the deflection amount in the second structure portion are adjusted based on an output of a detector that detects electrons.
An electron beam apparatus according to claim 1.