JP2002184338A - Electron beam device and manufacturing method of device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase of aberration and to increase the throughput of the evaluation of the sample equivalent number of times as the optical system, and further to increase the throughput of the evaluation of the sample same beam number of times as the multi-beams. SOLUTION: The electron beam device comprises an electron optical system that forms an electric field by an electrode 16 arranged between the objective lens 15 and the sample S and irradiates electron beams on the sample and a sample position detecting system that irradiates a measuring light flux on the sample from oblique direction and detects the position of the sample in the height direction by detecting the measuring light flux reflected by the sample. A pair of measuring openings for passing the measuring light flux on the face of the objective lens side at the position deviated from the optical axis of the electron optical system is formed on the electrode 16 nearest the sample, and a concave part enabling to pass the measuring light flux is provided on the sample side of the electrode in symmetry with the axis.

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 for evaluating a pattern or the like formed on the surface of a sample and a device manufacturing method for evaluating a sample during or after a process using the electron beam apparatus. Specifically, the minimum line width is 0.1 μm
An electron beam apparatus capable of performing high-throughput and high-reliability evaluation of defect inspection of device patterns on a substrate, CD measurement, measurement of potential contrast, measurement of high-time-resolved potential, and the like having the following patterns, and the like. The present invention relates to a device manufacturing method for evaluating a sample during or after a process using such an electron beam apparatus.

[0002]

2. Description of the Related Art A method and means for transmitting light from a detector (Z sensor) for detecting a vertical position when a deceleration electric field is applied between an objective lens and a sample are already known. However, according to the conventional means, although it is eight-fold symmetric but not rotationally symmetric, there is a high possibility of occurrence of aberration. Further, in the above-described conventional means, there is a problem that the throughput is small for evaluating the wafer and the like.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and one problem to be solved is to provide an aperture for a measurement light having a smaller aberration by providing an electron beam. An object of the present invention is to provide a device capable of improving resolution. Another problem to be solved by the present invention is to provide a plurality of optical systems capable of improving the resolution of an electron beam by providing an aperture for measurement light with smaller aberration, by providing a plurality of optical systems in parallel for one sample. An object of the present invention is to provide an electron beam apparatus capable of improving the line resolution and the throughput. Another problem to be solved by the present invention is to improve the resolution of an electron beam and the throughput of evaluation by providing an aperture for measurement light with smaller aberration and forming a plurality of beams by an electron optical system. It is to provide an electron beam device. Still another object of the present invention is to provide a device manufacturing method for evaluating a sample during or after a process using the above-described electron beam apparatus.

[0004]

According to the present invention, an electric field is formed by an electrode disposed between an objective lens and a sample.
An electron optical system that irradiates an electron beam toward the sample, and irradiates the sample with a measurement light beam from an oblique direction, detects the measurement light beam reflected from the sample, and determines the position in the height direction of the sample. In an electron beam apparatus having a sample position detection system for detecting, the electrode closest to the sample,
A pair of measurement openings for passing the measurement light beam is formed on the surface on the objective lens side at a position off the optical axis of the electron optical system, and the measurement light beam is formed on the sample side surface of the electrode. It is characterized in that a concave portion that allows passage is provided axially symmetrically.

In one aspect of the electron beam apparatus according to the present invention, in the electron beam apparatus, a surface of the electrode on the objective lens side is equal to a distance between the optical axis and the measurement aperture from the optical axis. An even number of openings of the same size may be provided at the distance while maintaining symmetry. In another embodiment, a plurality of the electron optical systems may be provided in parallel, and each of the electron optical systems may include an electrostatic axis symmetric lens in which electrodes are formed by forming a film on an integral ceramic. In another aspect of the electron beam apparatus of the present invention, the electron optical system includes a primary optical system that forms a plurality of beams, focuses the plurality of beams on a sample, and scans the sample, and has at least one lens. A secondary optical system that guides secondary electrons emitted from the sample and separated from the primary optical system by the E × B separator through the objective lens, wherein the secondary optical system is a secondary electron image. May be enlarged so as to be incident on a plurality of detectors. Another invention of the present application is a device manufacturing method for evaluating a sample during or after a process using the evaluation apparatus.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electron beam apparatus according to the present invention will be described below with reference to the drawings. FIGS. 1 and 2 schematically show an electron beam apparatus 1 according to this embodiment. The electron beam apparatus 1 includes an electron optical system 10 that irradiates an electron beam toward a sample S, and a measurement light beam that is obliquely irradiated on the sample and reflected from the sample to detect the measurement light flux in the height direction of the sample. A sample position detection system 30 for detecting the position. The electron optical system (optical system) 10 includes an electron gun 12 having a cathode 121 for emitting an electron beam, two condenser lenses 13 and 14, an electrostatic axially symmetric lens type objective lens 15, and an electric field control Electrodes 16 are arranged along the optical axis of the electron gun with the electron gun 12 at the top and the electrode 16 at the bottom, as shown in FIG.

The objective lens 15 which is an electrostatic axisymmetric lens
Has a ceramic body 151. The main body 151 is formed in an annular planar shape so as to define a circular hole 152 at the center, and three plate-like portions 15 whose inner peripheral sides are separated in the vertical direction (along the optical axis) in FIG.
It is divided into 3 to 155. Metal coating films 156 to 158 are provided on the outer periphery of the ceramic body 151, particularly around the plate-like portions 153 to 155. These coating films 156 to 15
8 function as electrodes, and the coating film 156
And 158, a voltage close to the ground side is applied, and a positive or negative high voltage having a large absolute value is applied to the middle coating film 157 by an electrode fitting 159 provided on the main body 151, and thereby the action of the lens is reduced. It is supposed to do. Since such a lens is formed by simultaneously shaving the ceramics and performing the processing at the same time, the processing accuracy is high and the outer diameter of the lens can be reduced. In one example, the outer diameter is 20 m in diameter.
m, and in this case, if the 140 mm square of a wafer having an outer diameter (diameter) of 200 mm is set as the evaluation area, seven electron optical systems 10 can be arranged inside 140 mm.
Therefore, in this way, the evaluation can be performed with seven times the throughput.

The electric field controlling electrode 16 is formed in a disc shape having an opening through which an electron beam passes at the center. The electrode 16 is provided with a measurement light beam LB on a surface on the sample side, that is, a lower surface 161.
Extends obliquely from the lower surface 161 to the surface on the objective lens side, that is, the upper surface 162 along the optical axis O′-O ′ (in this embodiment, inclined at an angle θ with respect to the upper surface of the sample), and the thickness of the electrode Is formed in the middle of the recess 163. The concave portion 163 is provided with the optical axis OO of the electron optical system.
Along the entire circumference along a circle centered at. The width of the concave portion 163 (the thickness measured at right angles to the optical axis O′-O ′) may be the same over the entire length, or may spread as the light beam moves away from the sample as shown in FIG. Therefore, the width may be changed accordingly (the lower surface side is narrow and the inner side is wide). The depth of the recess is preferably as deep as possible within the range of the strength of the electrode. Electrode 16
The upper surface 162 is formed with a light beam passage opening, that is, two diametrical positions on the extension of the concave portion, that is, two positions symmetrical with respect to the optical axis OO, and a light beam passage opening 164. Since the optical axis O'-O 'is oblique with respect to the upper surface 162, the opening has an elliptical shape having a major axis in the radial direction as shown in FIG. The electrode 16 is further provided with a plurality of dummy holes 165 having the same shape and size as the opening 164 on the same circumference (6 in this embodiment).
) Are formed at equal intervals. This dummy hole 165 is provided to improve the symmetry of the electrode 16. Since the inclination angle θ of the optical axis O′-O ′ is usually as small as 7 to 12 degrees, if a hole is made obliquely, the opening on the sample side, that is, the lower surface 161 side becomes closer to the optical axis, and the objective lens side, that is, the upper surface side Is located away from the optical axis. Therefore, a concave portion is provided on the surface on the sample side so as to extend annularly over the entire circumference of the axis symmetry, and a portion through which the light flux does not pass is also provided with a concave portion for the axial symmetry. The portion 166 of the electrode 16 near the optical axis OO
When it is desired to reduce the thickness, the inner peripheral side near the optical axis may be made thinner, and the portion where the concave portion 163 is formed may be made thicker. The sample position detection system 30 includes a light emitting device 31, a light receiving device 32, and a detecting circuit 3 connected to the light emitting device and the light receiving device.
3 is provided.

In the above-mentioned electron beam apparatus, the beam current of the electron beam emitted from the cathode 121 of the electron gun 12 is determined by the condenser lenses 13 and 14, and the objective lens 1
5 to form an image on the upper surface of the sample S. Secondary electrons emitted from the sample S by the irradiation of the electron beam are:
It is also sent to a detector (not shown) via a secondary optical system (not shown), and secondary electrons are detected by the detector to perform evaluation. On the other hand, in order to measure the position of the sample in the optical axis direction, a light beam LB for measurement is emitted from the light emitter 31 of the sample position detection system 30, and the light beam is transmitted to one opening 164 (left side in FIG. 1).
The sample S is irradiated through the inside and the left side of the concave portion 163. The light beam LB reflected on the upper surface of the sample S passes through the inside of the right side of the concave portion 163 on the opposite side in the diameter direction (the right side in FIGS. 1 and 2) and the inside of the opening 164 to the light receiver 32 side and is received by the light receiver. 33.
In the present invention, the electrode for electric field control is provided with an annular concave hole for light flux passage at a position near the optical axis OO to improve the axial symmetry, so that the opening and the dummy hole are located far from the optical axis. Although it is not axially symmetric, aberration does not increase near the optical axis because of good symmetry.

FIG. 3 schematically shows another embodiment of the electron beam apparatus according to the present invention. This electron beam device 1a has a primary electron optical system (hereinafter simply referred to as a primary optical system) 11a.
An electron optical system 10a including a secondary electron optical system (hereinafter simply referred to as a secondary optical system) 21a, a sample position detecting system 30a,
It has a secondary electron beam detection system 40a and a stage 50a for holding the wafer S, which are arranged in a positional relationship as shown in FIG. The primary optical system 11a
An electron gun 12a for emitting an electron beam, ie, an electron beam;
A condenser lens 13a for focusing an electron beam, a multi-aperture plate 17a having a plurality of (seven in this embodiment) openings formed on the same circumference, an intermediate lens 14a, and a scanning electrostatic element for scanning the electron beam. A deflector 18a, an ExB separator, that is, an ExB electrostatic deflector 19a,
It has an electrostatic deflector 20a for B, an objective lens 15a, and an electrode 16a for controlling electric field, which are emitted from the electron gun in order with the electron gun 12a at the top as shown in FIG. The primary optical system is arranged so that the optical axis is perpendicular to the surface (sample surface) of the sample S. Electron gun 12a
Is the cathode 121 inside the Wehnelt electrode 122a.
a is provided.

The secondary optical system 21a has a magnifying lens 22a and a multi-aperture plate 23a for detection. Detection system 40
a includes a detector 41a arranged for each opening 231a of the second multi-aperture plate 23a, and a processing circuit (not shown) connected to each detector. The primary optical system 11
a, the structure and function of each component of the secondary optical system 21a and the detection system 40a are the same as those of the related art, and therefore detailed description thereof will be omitted. Opening 1 of opening plate 17a
The opening 71a of the inspection multi-aperture plate 23a is formed to correspond to the opening 231a, and the opening 171a is smaller than the opening 231a shown by the broken line as shown by the solid line in FIG. 3B.

Next, the operation of the evaluation device according to the above embodiment will be described. The electron beam emitted from the electron gun 12a is focused by the condenser lens 13a and irradiates the multi-aperture plate 17a. The electron beam is formed on a plurality of (eg, 9 in this embodiment) formed on the same circumference of the multi-aperture plate.
Through the small aperture 171a toward the intermediate lens, and is multi-beamed by the aperture. The multi-beam is reduced by the objective lens 15a,
The multi-beam is two-dimensionally scanned by a and 20a and is irradiated onto the surface of the sample S. Secondary electrons emitted from the sample are accelerated by an electric field created by the objective lens 15a and the electrode 16a, pass through the objective lens, and are subjected to the E × B separator 19a,
20a, is deflected by the secondary optical system,
Thereby, an enlarged image of the secondary electrons is formed in each opening 231a of the multi-aperture plate 23a for detection. The enlarged image of the secondary electrons is detected by the detector 41a.

In order to measure the position of the sample S in the axial direction, that is, the position in the Z direction, the light emitting device 31a of the sample position detecting system 30a is used.
, A detection light beam LB is applied obliquely to the surface of the sample, and the light beam reflected on the upper surface of the sample is received by the light receiver 32a, detected by the detection circuit 33a, and the position is measured. The light beam passes through the concave portion and the opening formed in the electrode 16a as in the above-described embodiment. Since their structures are the same as those of the above-described embodiment,
Detailed description is omitted.

Next, an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described with reference to FIGS. FIG.
3 is a flowchart showing one embodiment of a method for manufacturing a semiconductor device according to the present invention. The manufacturing process of this embodiment includes the following main processes. (1) Wafer manufacturing process for manufacturing a wafer (or wafer preparing process for preparing a wafer) (2) Mask manufacturing process for manufacturing a mask used for exposure (or mask preparing process for preparing a mask) (3) Necessary for wafer (4) Chip assembling step of cutting out chips formed on a wafer one by one and making them operable (5) Chip inspection step of inspecting the resulting chips The main process further comprises several sub-processes.

Among these main steps, the wafer processing step (3) has a decisive effect on the performance of the semiconductor device. In this step, designed circuit patterns are sequentially stacked on a wafer, and a number of chips that operate as memories and MPUs are formed. This wafer processing step includes the following steps. (A) A thin film forming step (CVD) for forming a dielectric thin film serving as an insulating layer, a wiring portion, or a metal thin film forming an electrode portion.
(B) Oxidation step of oxidizing this thin film layer or wafer substrate (C) Lithography for forming a resist pattern using a mask (reticle) to selectively process the thin film layer or wafer substrate Step (D) An etching step of processing a thin film layer or a substrate according to a resist pattern (for example, using a dry etching technique) (E) Ion / impurity implantation / diffusion step (F) Resist stripping step (G) Step of inspecting the processed wafer It should be noted that the wafer processing step is repeated by the required number of layers to manufacture a semiconductor device that operates as designed.

FIG. 5 is a flowchart showing a lithography step which is the core of the wafer processing step shown in FIG. This lithography step includes the following steps. (A) a resist coating step of coating a resist on a wafer on which a circuit pattern has been formed in the preceding step (b) a step of exposing the resist (c) a developing step of developing the exposed resist to obtain a resist pattern ( d) Annealing step for stabilizing the developed resist pattern The above-described semiconductor device manufacturing step, wafer processing step, and lithography step are well known and need not be further described. When the defect inspection method and the defect inspection apparatus according to the present invention are used in the inspection step (G), even a semiconductor device having a fine pattern can be used.
Since the inspection can be performed with a high throughput, all the inspections can be performed, thereby improving the product yield and preventing the shipment of defective products.

[0017]

According to the present invention, the following effects can be obtained. (A) A hole through which the light beam for position measurement in the optical axis direction, that is, the Z direction passes, is provided in the electric field control electrode, and since the hole is axially symmetric near the optical axis, the aberration is prevented from increasing. it can. (B) The throughput of sample evaluation can be improved to the number of optical systems. (C) The throughput of the sample evaluation can be improved to the number of beams of the multi-beam.

[Brief description of the drawings]

FIG. 1 is a schematic view of one embodiment of an electron beam device according to the present invention.

FIG. 2 is a plan view showing a half and a half of a hole and a dummy hole formed in the electric field control electrode of FIG. 1;

FIG. 3A is a schematic diagram of another embodiment of the electron beam apparatus according to the present invention, and FIG. 3B is a diagram showing a comparison between the apertures of a multi-aperture plate and a multi-aperture plate for detection.

FIG. 4 is a flowchart showing one embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 5 is a flowchart showing a lithography step which is the core of the wafer processing step shown in FIG. 4;

[Explanation of symbols]

1, 1a Electron beam device 10, 10a Electron optical system 11a Primary optical system 12, 12a Electron gun 13, 13a
Condenser lens 14, 14a Intermediate lens 15, 15a
Objective lens 16, 16a Electrode 17a Multi-aperture plate 18a Deflector 19a, 20a
Ex × B separator 21a Secondary optical system 22a Magnifying lens 23a Multi aperture plate for detection 30, 30a Sample position detection system 31, 31a
Light emitter 32, 32a Light receiver 33, 33a
Detection circuit 40a Secondary electron beam detection system 41a Detector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G21K 5/04 G21K 5/04 F 5C033 H01J 37/28 B H01J 37/28 H01L 21/66 J H01L 21 / 66 G01R 31/28 L (72) Inventor: Mamoru Nakasuji, 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Meister Co., Ltd. (72) Inventor Shinji Noji 11-1, Haneda Asahi-cho, Ota-ku, Tokyo EBARA CORPORATION (72) Inventor Toru Satake 11-1 Haneda Asahimachi, Ota-ku, Tokyo F-term in EBARA CORPORATION (reference) 2F067 AA26 AA54 BB01 BB04 CC17 EE04 HH06 JJ05 KK04 LL02 QQ02 2G001 AA03 AA07 BA07 BA14 CA03 CA07 DA02 DA06 EA04 GA01 GA06 GA08 GA09 JA02 JA04 KA03 LA11 MA05 RA04 RA08 SA01 SA04 2G132 AA00 AD15 AE04 AF13 4M106 AA01 BA02 CA39 DB05 DB30 5C001 AA01 CC04 CC 08 5C033 JJ01 UU02 UU10

Claims (5)

[Claims] 1. An electron optical system for forming an electric field by an electrode disposed between an objective lens and a sample and irradiating an electron beam toward the sample, and irradiating the sample with a measurement light beam from an oblique direction. And an electron beam device comprising a sample position detection system for detecting the position of the sample in the height direction by detecting the measurement light beam reflected from the sample, wherein the electrode closest to the sample includes: A pair of measurement openings for passing the measurement light beam is formed on the surface on the objective lens side at a position off the optical axis of the electron optical system, and the measurement light beam is formed on the sample side surface of the electrode. An electron beam device, wherein a concave portion that allows passage is provided axially symmetrically. 2. The electron beam apparatus according to claim 1, wherein
On the surface on the objective lens side of the electrode, at a position at a distance equal to the distance between the optical axis and the measurement opening from the optical axis,
An electron beam apparatus, wherein an even number of openings having the same dimensions are provided while maintaining symmetry. 3. The electron beam apparatus according to claim 1, wherein
An electron beam apparatus, wherein a plurality of the electron optical systems are provided in parallel, and each electron optical system has an electrostatic axis symmetric lens in which electrodes are formed by forming a film on an integral ceramic. 4. The electron beam apparatus according to claim 1, wherein
The electron optical system is a primary optical system that forms a plurality of beams and focuses and scans the plurality of beams on a sample.
A secondary optical system having at least one stage of lenses and guiding secondary electrons emitted from the sample and separated from the primary optical system by the E × B separator through the objective lens; An electron beam apparatus characterized in that an optical system enlarges a secondary electron image and makes it incident on a plurality of detectors. 5. A device manufacturing method, comprising: evaluating a wafer in the course of a process using the apparatus according to claim 1.