JP2003208868A - Electron beam device and semiconductor device manufacturing method therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the measurement and evaluation of a sample surface at high throughput and prevent upsizing, complexity, and a cost increase of a device. <P>SOLUTION: This electron beam device for evaluating a sample 18 comprises a plurality of electron optical system, and the respective electron optical systems comprise objective lenses constituted of electrostatic lenses. To middle electrodes 28 and lower electrodes 16 of the objective lenses, voltage is applied from common control powers 28, 29, and to upper electrodes 14, voltage is applied from independently controlled power sources 27 provided on each of the electron optical systems. Thus, focusing can be independently controlled at the respective electron optical systems. The voltage of the power source 29 is set so as to be lower than that of a power supply 30 for the sample 18, thereby the energy filter effect of a secondary electron can be given and a potential contrast of a pattern on the sample can be evaluated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electron beam apparatus for performing, with high precision and reliability, shape observation and defect inspection of a wafer or mask having a high-density pattern having a minimum line width of 0.1 μm or less, and The present invention relates to a device manufacturing method for inspecting a pattern of a semiconductor device during and after a process using the electron beam apparatus.

[0002]

2. Description of the Related Art A sample made up of a semiconductor wafer or a mask for producing the wafer is irradiated with a primary electron beam, and an electric signal obtained from secondary electrons emitted from the surface of the sample is processed. An electron beam apparatus capable of obtaining a pattern on a sample is known. In such an electron beam apparatus, a method of irradiating a plurality of primary electron beams onto a sample by using one optical system (multi-beam method) has already been proposed in order to improve the throughput, and a plurality of optical systems are used. It has also been proposed to irradiate a sample with a plurality of primary electron beams by using systems in parallel.

[0003]

In the above-mentioned conventional multi-beam type electron beam apparatus, an energy filter effect is provided by applying a voltage lower than the sample surface to the sample-side electrode of the objective lens. Then, the image formation relationship of the secondary electron image is broken, and it is difficult to detect the multi-beam secondary electron beam without crosstalk. Therefore, highly accurate image information cannot be obtained. On the other hand, in an electron beam apparatus using a plurality of optical systems, the problem of crosstalk can be solved, but since a plurality of optical systems are used, the apparatus becomes larger as the number of optical systems increases. And the control system becomes complicated and expensive. Therefore, in consideration of these problems, it is unavoidable to provide a relatively small number of optical systems, and as a result, the throughput cannot be significantly improved.

The present invention is to solve the above-mentioned problems in the electron beam apparatus of the conventional example, and its purpose is to enable measurement and evaluation of the sample surface with high throughput, and further to An object of the present invention is to provide an electron beam apparatus capable of preventing an increase in size, complexity, and price increase. Another object of the present invention is to provide a semiconductor device manufacturing method including a step of evaluating a semiconductor wafer during or after the process using such an electron beam apparatus.

[0005]

To achieve the above object, a plurality of electron optical systems having at least one stage of electrostatic lens according to the present invention are provided, and a plurality of electron optical systems on a sample are provided by these electron optical systems. The electron beam apparatus for simultaneously evaluating the points is characterized by including one common control power supply for commonly controlling the electrostatic lenses of each of the plurality of electron optical systems.

In the electron beam apparatus according to the present invention described above, each electrostatic lens is composed of first to third electrodes, and the second electrode is the first and third electrodes arranged vertically.
Is located in the center of the electrode and is applied with a voltage from a common control power source, and the first or third electrode is applied with a voltage from an independent control power source which is independently controllable and is provided for each electron optical system. It is preferable that it is configured as follows. In addition, at least one stage of electrostatic lens is configured as an objective lens, a voltage from an independent control power source is applied to the first electrode, and a common control power source is used to form a third electrode which is an electrode on the side facing the sample.
It is preferable that a voltage lower than the voltage applied to the sample is applied to the electrode of (1) to give an energy filter effect of secondary electrons so that the potential contrast of the pattern on the sample can be evaluated.

According to another aspect of the present invention, an electron beam apparatus having a plurality of electron optical systems including an electron gun having an anode, a heat emitting cathode, and a Wehnelt for simultaneously evaluating a plurality of points on a sample is provided. Apply the same voltage to all of the heat emitting cathodes of
One common control power source that controls the cathodes in common, and an independent control provided for each electron optical system that independently adjusts each of the Wehnelts by individually adjusting the voltage to the Wehnelts of the electron guns. It is characterized by having a control power supply. The present invention further provides a semiconductor device manufacturing method including the step of inspecting a semiconductor device during or after the process using the electron beam apparatus according to the present invention.

[0008]

FIG. 1 is an explanatory view for explaining the configuration of an electron beam apparatus according to an embodiment of the present invention, which electron beam apparatus comprises a plurality of electron optical systems arranged in parallel. This is the method used. In the drawing, three sets of electron optical systems are shown as sectional views, but it is needless to say that two sets or four sets or more can be provided. Each electron gun is composed of a L _a B ₆ cathode 1, a Wehnelt 2 and an anode 3 which constitute _a heat emitting cathode. A Wehnelt independent control power source 20 for supplying a voltage to the Wehnelt 2 is provided for each electron optical system, that is, for each electron gun, and these power sources 20 can individually adjust the output voltage. Further, the same voltage is commonly applied to the cathodes 1 of all the electron guns from one cathode common control power source 19 whose output voltage is adjustable, and although not shown, the anodes 3 of all the electron guns are grounded. Has been done.

The primary electron beam emitted from each electron gun passes through the openings of the anode 3 and the aperture plate 4, and the reference numeral 3
Follow the trajectory indicated by 1 and crossover at position 5. The crossover position 5 can be positioned at an appropriate position along the optical axis direction by individually adjusting the independent control power source 20. N at crossover position 5
A circular opening that determines A is arranged. The aperture of the aperture plate 4 has a square shape, whereby the trajectory 3 of the primary electron beam is
1 is an electrostatic capacitor including three cylindrical electrodes 6, 7, 8 (upper electrode 6, central electrode 7, lower electrode 8) that are shaped so that their cross section is square and have an opening in the center. It is reduced by a condenser lens that is a lens. Further, the primary electron beam is an objective consisting of an electrostatic lens including three cylindrical electrodes 14, 15, 16 (upper electrode 14, central electrode 15, lower electrode 16) having an opening in the central portion. The sample 18 is irradiated with light through the lens to form a reduced image.

The central electrodes 7 of the condenser lenses are all electrically connected so as to have the same potential, and a voltage is applied from one common control power supply 22 capable of adjusting the output voltage with high accuracy. The lower electrode 8 of each condenser lens is grounded, while the upper electrode 6 is an independent control power supply 21 provided corresponding to each optical system and capable of individually adjusting the output voltage.
Voltage is applied from. By independently adjusting the output of each power supply 21, each optical system can form a crossover image at an accurate position. This makes it possible to form the crossover images of all the optical systems at the predetermined set positions.

Similarly to the case of the condenser lens, the central electrode 15 of the objective lens is connected to have the same electric potential, and a voltage is applied from one common control power source 28 which can be adjusted with high accuracy. The accuracy R of this power supply 28 is
Using an electron gun with a L _a B ₆ cathode, if voltage to be supplied to the central electrode 15 was set to 20kV, R«ΔE / (2
Should be set to 0 × 10 ³ ), and if ΔE≈3 V, R << 1.5 × 10 ⁻⁴ . Therefore, the common control power supply 28 needs an adjustment accuracy of about 1 × 10 ⁻⁴ .

The upper electrode 14 of the objective lens is
A voltage is applied from an independent control power supply 27 that is provided for each electron optical system and can be adjusted individually, and by individually adjusting the voltage, the focusing condition set for each electron optical system can be satisfied. Controlled to form a crossover image at position 17. The deflectors 9 and 11 for scanning the primary electron beam in each electron optical system are scanned by the scanning signals from the deflection power sources 24 and 25. The curvature needs to be corrected. This field curvature is corrected by adjusting the voltage applied from the independent control power supply 27 to the upper electrode 14 to adjust the focus state of the objective lens. In order to adjust the in-focus state, the power supply 27 needs to have a relatively high response speed, but if it can be corrected at ± 100 V or less, exceptionally high-precision stability is not required.

The central electrodes 15 of all the objective lenses are electrically connected to each other so as to have the same potential, and are held at the voltage level from one common control power supply 28 whose output voltage is adjustable. Similarly, the lower electrodes 16 of all objective lenses
Are electrically connected to each other so as to have the same potential, and are held at the voltage level from one common control power supply 29 whose output voltage is adjustable. From the sample 18 depending on whether the output voltage of the power source 29 is higher or lower than the voltage applied to the sample 10 from the power source 30 (that is, whether the potential of the lower electrode 16 is higher or lower than the potential of the sample 18). 2 released
A part of the secondary electrons can be returned to the sample 18 side or passed through the objective lens.

When the pattern on the sample 18 is formed by a groove, or a plurality of different materials (eg, SiO ₂
When it is desired to obtain an image that clearly shows the difference in the shape and material of the pattern, such as in the case where the voltage is higher than the potential of the sample 18, the power source 29 applies a lower voltage to the lower electrode 16. Apply. On the other hand, when it is desired to obtain a potential contrast image on the sample 18, a voltage lower than the output voltage of the power source 30 is applied from the power source 29 to the lower electrode 16. For example, when 0 V is applied to the sample 18 from the power source 30 and the sample 1
When two regions of + 2V region and -2V region exist on 8 and a voltage of -10V is applied from the power supply 29 to the lower electrode 16 of the objective lens, the secondary electrons from the -2V region are objective. After passing through the lens, the secondary electrons from the area of +2 V are driven back to the sample 18 side by the objective lens. As a result, the -2V area in the obtained image becomes brighter and +2
The V area becomes dark. The other areas have intermediate brightness. Therefore, the potential contrast can be obtained.

The secondary electrons that have passed through the objective lens are deflected by an E × B deflector (Wien filter) including an electrostatic deflector 11, an electromagnetic deflection coil 12, and a deflection core 13 for each electron optical system. It is detected by the secondary electron detector 10 and is image processed by the SEM imaging circuit 23. In the present embodiment, the electron gun uses a heat emitting cathode. Then, the shot noise is reduced by using this electron gun under the space charge limiting condition such that the shot noise is reduced, whereby an image with a good S / N ratio can be scanned with a small beam current or at a high speed. Can be obtained at speed.

Next, the semiconductor device manufacturing method of the present invention will be described. The semiconductor device manufacturing method of the present invention is
The above-described electron beam apparatus is used in a semiconductor device manufacturing method described below with reference to FIGS. 2 and 3. As shown in FIG. 2, the semiconductor device manufacturing method is roughly divided into a wafer manufacturing step S1 for manufacturing a wafer, a wafer processing step for performing necessary processing on the wafer.
Processing step S2, mask manufacturing step S3 for manufacturing a mask necessary for exposure, chip assembling step S4 for cutting out chips formed on a wafer one by one to make them operable, and chip inspection for inspecting completed chips Process S
It is composed of 5. Each of these steps includes several substeps.

Among the above-mentioned steps, the step which has a decisive influence on the manufacture of the semiconductor device is the wafer processing step S2. In this process, the designed circuit pattern is formed on the wafer and the memory or MPU is formed.
Many chips that operate as are formed. As described above, it is important to evaluate the processing state of the wafer processed in the wafer processing step S2 that affects the manufacturing of the semiconductor device, and the step S2 includes the following sub-steps.

1. 1. A thin film forming step (using CVD or sputtering) for forming a dielectric thin film that becomes an insulating layer, a wiring part, or a metal thin film that forms an electrode part. 2. Oxidation step of oxidizing the thin film layer and the wafer substrate 3. Lithography process for forming a resist pattern by using a mask (rectile) for selectively processing a thin film layer, a wafer substrate, etc. 4. Etching process for processing a thin film layer or substrate according to a resist pattern (for example, using a dry etching technique) 5. Ion / impurity injection diffusion step 6. Resist stripping step 7. A wafer inspection process for inspecting processed wafers. The sub-process of the wafer processing process S2 is
By repeating the process for the required number of layers, a wafer before being separated into chips is formed in the chip assembling step S4.

FIG. 3 is a flowchart showing a lithography process which is a sub-process of the wafer processing process of FIG. As shown in FIG. 3, the lithography process includes a resist coating process S21, an exposure process S22, a developing process S23, and an annealing process S24. In the resist coating step S21, a resist is coated on the wafer on which the circuit pattern is formed by using CVD or sputtering, and in the exposure step S22, the coated resist is exposed. Then, in the developing step S23, the exposed resist is developed to obtain a resist pattern, and in the annealing step S24, the developed resist pattern is annealed to be stabilized. These steps S21-
S24 is repeatedly executed for the required number of layers.

In the method of manufacturing a semiconductor device of the present invention, the electron beam apparatus described with reference to FIG. 1 is used to perform not only a process in the middle of processing (wafer inspection process) but also a chip inspection process for inspecting a completed chip. By using in S5, even a semiconductor device having a fine pattern can obtain an image in which distortion, blurring, etc. are reduced, so that a defect in a wafer can be reliably detected.

[0021]

Since the present invention is configured as described above, the following operational effects can be obtained. 1. Since multiple electron optical systems are arranged in parallel,
Compared with the case of the multi-beam method in which a plurality of primary electron beams are formed by using one electron gun, the crosstalk is small and the throughput can be improved. 2. Since the cathode of the electron gun, the central electrode of the condenser lens, and the central and lower electrodes of the objective lens, which need to be adjusted with high precision, are adjusted and controlled by a power source common to a plurality of electron optical systems, The configuration of the electric control system can be simplified. 3. The Wehnelt potential of the electron gun can be controlled by an individual power source provided for each electron optical system, so even if there are individual differences in the electron gun, the crossover position created by the electron gun can be
The position can be adjusted as designed. 4. Since the focusing is controlled by the electrode (that is, the electrode 14) of the condenser lens or the objective lens that is originally grounded, the correction for each electron optical system can be performed by an independent power source. 5. Since the number of lenses of the electron optical system is two, that is, the condenser lens and the objective lens, the number of lenses is small, so that the structure and the control system can be made simple. This gives, for example, 1
Ten or more optical systems can be arranged on a 2-inch wafer, and throughput can be improved by about 10 times. 6. By operating the electron gun under the space charge limiting condition where shot noise is reduced, a high quality image can be obtained even with a small beam current or high speed scanning.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an electron beam apparatus according to the present invention.

FIG. 2 is a flowchart showing an example of a semiconductor device manufacturing method.

FIG. 3 is a flowchart showing a lithographic process forming the core of the wafer processing process shown in FIG.

[Explanation of symbols]

1 ... Cathode 2 ... Wehnelt 3 ... Anode
4 ... Aperture plates 5, 17 ... Crossover positions 6-8 ... Condenser lens 9 ... Deflector 10 ... Secondary electron detector 11-13 ... ExB deflector 14-16 ... Objective lens 18 ... Samples 19, 22 28, 29 ... Common control power source 20, 2
1, 27 ... Independent control power supply 23 ... Image processing device 24, 25, 30 ... Power supply

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Noji             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION (72) Inventor Toru Satake             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION F-term (reference) 4M106 AA01 AA09 CA39 CA41 DB05                       DB30                 5C033 UU02 UU04

Claims (5)

[Claims] 1. An electron beam apparatus having a plurality of electron optical systems having at least one stage of electrostatic lens, wherein the electron optical systems simultaneously evaluate a plurality of points on a sample. An electron beam apparatus comprising one common control power supply for commonly controlling an electro-lens. 2. The electron beam apparatus according to claim 1, wherein each electrostatic lens includes first to third electrodes, and the second electrode has first and third electrodes arranged vertically. Is located at the center of the electrode of the common control power supply, and the voltage is applied to the first or third electrode from the independent control power supply which is independently controllable and is provided for each electron optical system. An electron beam apparatus having the above-mentioned configuration. 3. The electron beam apparatus according to claim 2, wherein the electrostatic lens of at least one stage is an objective lens, a voltage from an independent control power source is applied to the first electrode, and the objective lens is controlled by a common control power source. By applying a voltage lower than the voltage applied to the sample to the third electrode, which is the electrode on the side of the lens facing the sample, the energy filter effect of secondary electrons is provided, and the potential of the pattern on the sample is increased. An electron beam device characterized in that contrast can be evaluated. 4. A plurality of electron optical systems including an electron gun having an anode, a heat emitting cathode, and a Wehnelt are provided,
In an electron beam apparatus for simultaneously evaluating a plurality of points on a sample, one common control power source for controlling the cathodes in common by applying the same voltage to all heat emitting cathodes of a plurality of electron guns in an adjustable manner, An electron beam apparatus, comprising: an independent control power supply provided for each electron optical system, which independently controls each of the Wehnelts by individually and individually applying a voltage to the Wehnelts of the electron gun. 5. A method of manufacturing a semiconductor device, which includes the step of inspecting a semiconductor device during or after the process using the electron beam apparatus according to any one of claims 1 to 4. .