JP2005019207A - Method for manufacturing charged particle beam apparatus and micro device, and micro device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle beam apparatus which compensates for irradiation nonuniformity of a charged particle beam for irradiation. <P>SOLUTION: Generated electrons 8 from a sample 6 are passed through an objective lens 7, an electromagnetic prism 3 as an optical path switching means, and an image-forming electron-optical system 9 projected on an MCP detector 10 and photoelectrically converted. The light generated by photoelectrical conversion is passed through a photo mapping optical system 12, and an image is projected on a time delay integrating type imaging device camera 13. For observing the sample image, the sample is made to move synchronized to the scanning direction of the imaging device camera 13, thereby accumulating on each corresponding imaging device of the imaging device camera 13 the light intensity produced by secondary electrons, back scattering electrons and reflected electrons 8 from a point of the sample. Hence, even if there is an irradiation distribution, the values integrated by the imaging device camera 13 are equivalent to that in the case of any point of the sample being irradiated with the same light amount. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charged particle beam apparatus for observing and inspecting a sample surface by irradiating a charged particle beam such as an electron beam or an ion beam onto a sample surface, a method of manufacturing a microdevice using the charged particle beam device, and the charged particle beam. The present invention relates to a micro device observed by the apparatus.
[0002]
[Prior art]
The irradiation charged particle beam emitted from the irradiation source is made incident on the optical path switching means through the irradiation optical system, and the irradiation charged particle beam passed through the optical path switching means is made incident on the sample surface through the objective optical system. The observation charged particle beam emitted from the sample surface is incident on the optical path switching means via the objective optical system, and the observation charged particle beam is guided in a direction different from the direction reaching the irradiation source by the optical path switching means, The charged particle beam device that makes the charged particle beam for observation after passing through the optical path switching unit enter the detection unit using the time delay integration type imaging device via the imaging optical system is currently in the development stage. It will be used for inspection of device patterns and other micro devices having fine structures.
[0003]
In such a charged particle beam device, a two-dimensional photoelectric conversion device or the like is disposed on the imaging surface, the formed charged particle beam is temporarily converted into light, and time delay such as TDI-CCD via a relay optical system. An image of the imaging surface is formed on an integral type imaging device. Then, the sample is moved in accordance with the scanning of the time delay integration type image pickup device, and the charged particle beam emitted from the same sample surface and converted into light is integrated to be taken out as a large charge. Enables observation of the sample.
[0004]
As described above, when a time delay integration type imaging device such as a TDI-CCD is used, the result of image formation at various positions of the observation charged particle beam optical system and the optical system in the scanning direction is integrated. Therefore, in this direction, even if there are aberrations in the observation charged particle beam optical system, uneven illuminance, etc., it is possible to obtain an observation result in which they are smoothed.
[0005]
On the other hand, in such a charged particle beam apparatus, the illumination optical system simply needs to uniformly illuminate the sample surface, whereas the observation charged particle beam optical system needs to accurately form an image of the sample surface. Therefore, the conditions such as aberrations are severe. Therefore, in parts commonly used for the illumination optical system and the observation charged particle beam optical system, the conditions required for the illumination optical system and the observation charged particle beam optical system When the required conditions contradict each other, it is general to satisfy the conditions required for the observation charged particle beam optical system at the expense of the conditions of the illumination optical system.
[0006]
Under such conditions, in the charged particle beam apparatus, the optical axis of the charged particle beam optical system for observation is a straight line, the light source of the illumination optical system is provided in the lateral direction, and the light path switching means such as E × B is used for irradiation. It is configured to illuminate the sample surface in a state where the charged particle beam optical path is bent and coincides with the optical axis of the observation charged particle beam optical system. Generally, an optical path switching means using an electric field and a magnetic field, such as E × B, is used. In this case, the charged particle beam has a traveling direction in a plane parallel to the electric field and perpendicular to the magnetic field. When the observation charged particle beam optical system to be changed is considered alone, variations in aberrations and the like appear greatly in a direction parallel to the magnetic field. Therefore, in the conventional charged particle beam apparatus, the scanning direction of the time delay integration type imaging device (and hence the moving direction of the sample) is made to coincide with the direction of the magnetic field of the optical path switching means, thereby causing unevenness between the locations in the magnetic field direction. A method of averaging aberrations and the like having been used has been adopted.
[0007]
[Patent Document 1] JP 2000-340162 A
[Problems to be solved by the invention]
According to the above configuration, correction of unevenness in the direction parallel to the E × B electric field and perpendicular to the magnetic field, that is, in the plane in which the illumination charged particle beam is bent, may be performed by a time delay integration type imaging device. I could not. In this plane, since the optical path of the charged particle beam for illumination is bent, the generation of uneven illuminance is inevitable, but this is unavoidable.
[0009]
The present invention has been made in view of such circumstances, and in consideration of recent advances in observational charged particle beam optical systems, a charged particle beam device capable of compensating for illuminance unevenness of a charged particle beam for illumination, and It is an object of the present invention to provide a method of manufacturing a microdevice using the same, and further to provide a microdevice observed by this charged particle beam apparatus.
[0010]
[Means for Solving the Problems]
The first means for solving the above-mentioned problem is that the charged particle beam for irradiation emitted from the irradiation source is made incident on the optical path switching means via the irradiation optical system, and the irradiation charge passed through this optical path switching means. A particle beam is incident on the sample surface via the objective optical system, and the observation charged particle beam emitted from the sample surface is incident on the optical path switching means via the objective optical system. The charged particle beam for observation is guided in a direction different from the direction reaching the irradiation source, and the charged particle beam for observation after passing through the optical path switching unit is converted into a time delay integration type via an imaging optical system. A charged particle beam apparatus that is incident on a detection unit using an imaging device, the direction being parallel to a plane including a trajectory of the irradiation charged particle beam whose traveling direction is bent by the optical path switching unit, and the time delay integration Type image sensor The direction in which the integrated Te is performed matches charged particle beam apparatus according to claim. (Claim 1).
[0011]
As described above, in the observation charged particle beam optical system, the occurrence of aberration or the like has been a problem. For example, as described in Japanese Patent Application Laid-Open No. 2000-340162 (Patent Document 1), optical path switching is performed. By means of adjusting the observation charged particle beam optical system so that the power center of the means is conjugate with the observation surface, it becomes possible to reduce the influence of aberration on the observation charged particle beam optical system. If such a charged particle beam optical system for observation with small aberration is used, the charged particle beam for irradiation whose traveling direction is bent without worrying about the influence on the charged particle beam optical system for observation with severe aberration correction conditions. It is possible to determine the relationship between the direction of the surface including the locus and the direction of integration in the time delay integration type image sensor.
[0012]
Therefore, in this means, the direction of the surface including the locus of the charged particle beam for irradiation coincides with the direction in which the images are integrated in the time delay integration type imaging device (that is, the direction in which the sample is moved). As a result, even if there is uneven illuminance of the charged particle beam for irradiation, the value that is integrated and output by the time delay integration type image sensor is the average charged particle while the sample is moving in the observation field. It becomes the value of the amount of line reflection or the amount of secondary electrons generated. Therefore, illumination unevenness is canceled and a favorable imaging result can be obtained.
[0013]
The second means for solving the problem is the first means, wherein the optical path switching means is an electromagnetic prism, and the power center of the sample surface and the electromagnetic prism is in a charged particle beam optical system. The present invention is characterized by being in a conjugate positional relationship (claim 2).
[0014]
As described in Japanese Patent Laid-Open No. 2000-340162 (Patent Document 1), if the charged particle beam optical system for observation is adjusted so that the power center of the electromagnetic prism as the optical path switching means is conjugate with the observation surface, It is possible to reduce the influence of aberration on the observation charged particle beam optical system, and the configuration as in the first means without worrying about the influence on the observation charged particle beam optical system having severe aberration correction conditions. To cancel the illumination unevenness and obtain a good imaging result.
[0015]
A third means for solving the problem includes a step of observing the surface of the microdevice using a charged particle beam apparatus which is the first means or the second means. It is a manufacturing method (Claim 3).
[0016]
In this means, since the micro device can be inspected in a state where the illuminance unevenness of the charged particle beam apparatus is reduced, the inspection accuracy by surface observation can be increased. Note that a micro device refers to an object having a fine structure including a semiconductor device and a micro machining device, and this is common throughout the present specification.
[0017]
A third means for solving the above problem is a micro device (surface 4) in which surface observation is performed using a charged particle beam apparatus which is the first means or the second means.
[0018]
In this means, since the surface observation is performed in a state where the illuminance unevenness is reduced, it is possible to obtain a micro device having no defect.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of an electron beam apparatus as an example of an embodiment of the present invention. The irradiation beam 4 emitted from the cathode 1 passes through the Wehnelt electrode 14, the anode 15, and the illumination electron optical system 2 and enters the electromagnetic prism (E × B) 3. After the optical path of the irradiation beam 4 is changed by the electromagnetic prism 3 which is an optical path switching unit, the irradiation beam 4 passes through the objective lens 7 and irradiates the surface of the sample 6. When the irradiation beam 4 enters the sample 6, secondary electrons, backscattered electrons, and reflected electrons 8 are generated from the sample 6 according to the surface shape, material distribution, potential change, and the like.
[0020]
The generated electrons 8 are projected onto a MCP (Micro Channel Plate) detector 10 through an objective lens 7, an electromagnetic prism 3 as an optical path switching means, and an imaging electron optical system 9, and are photoelectrically converted. The light generated by the photoelectric conversion passes through the optical mapping optical system 12 and an image is projected onto a time delay integration type imaging device (TDI-CCD) camera 13. Here, the objective lens 7 is designed so that an intermediate image by secondary electrons, backscattered electrons and reflected electrons 8 is imaged with good resolution near the center of the electromagnetic prism 3 which is an optical path switching means. That is, the center position of the electromagnetic prism 3 and the surface position of the sample 6 are conjugate. Further, the electromagnetic prism 3 and the imaging electron optical system 9 are precisely designed so that an image formed by secondary electrons, backscattered electrons, and reflected electrons 8 is formed with high resolution.
[0021]
Since the center position of the electromagnetic prism 3 and the surface position of the sample 6 are conjugate, as described in Patent Document 1, the objective lens 7, the electromagnetic prism 3 that is an optical path switching means, and the imaging electron optical system 9 As a result, the aberration of the observation charged particle beam optical system centering on can be reduced.
[0022]
Here, FIG. 2 shows a state where the optical path of the irradiation beam 4 is bent by the electromagnetic prism 3 which is an optical path switching means. When the surface of the sample 6 is illuminated by passing through the objective lens 7, distortion occurs in the direction in which the optical path is bent as shown in FIG. 2A, and as a result, as shown in FIG. The illuminance unevenness in the left-right direction in FIG. On the other hand, since the irradiation beam 4 is not bent in the direction perpendicular to the paper surface of FIG. 2, relatively uniform illuminance can be obtained.
[0023]
However, in the present embodiment, the scanning direction of the time delay integration type imaging device camera 13 is set to the horizontal direction (electric field direction) in FIG. , Taken in the direction perpendicular to the paper surface in FIG. 2 (magnetic field direction).
[0024]
Therefore, when observing the image of the sample, the sample is moved in the left-right direction in FIG. 2 in accordance with the scanning direction of the time delay integration type image pickup device camera 13, thereby secondary electrons from the same point, The intensity of light generated by the backscattered electrons and the reflected electrons 8 is moved while being accumulated in each image sensor of the time delay integration type image sensor camera 13.
[0025]
Therefore, before a certain point of the sample enters the imaging field of view and exits, the left and right points in FIG. 2 are irradiated, and the received light amount integrated by the time delay integration type imaging device camera 13 The value has a relationship with the value obtained by integrating the illuminance distribution shown in FIG. Therefore, since the sample is imaged while moving, the value obtained by integrating the illuminance distribution shown in FIG. 2B is the same at any point of the sample. Therefore, the illuminance distribution as shown in FIG. Despite this, the value integrated by the time delay integration type imaging device camera 13 is equivalent to that illuminated at the same amount of light at any point of the sample.
[0026]
Therefore, according to the present embodiment, even when there is uneven illuminance of the sample in the actual electron beam for irradiation, the same effect as that in which uniform illumination is performed can be obtained. Therefore, observing a sample, for example, a semiconductor device, which is a micro device, using such an electron beam apparatus is substantially the same as that observed using an electron beam apparatus having no unevenness in illuminance, and increases the observation accuracy. Can do.
[0027]
Hereinafter, an example of an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described. FIG. 3 is a flowchart showing an example of the semiconductor device manufacturing method of the present invention. The manufacturing process of this example includes the following main processes.
(1) Wafer manufacturing process for manufacturing a wafer (or wafer preparation process for preparing a wafer)
(2) Mask manufacturing process for manufacturing a mask used for exposure (or mask preparation process for preparing a mask)
(3) Wafer processing process for performing necessary processing on the wafer (4) Chip assembly process for cutting out chips formed on the wafer one by one and making them operable (5) Chip inspection process for inspecting the completed chips Each process further includes several sub-processes.
[0028]
Among these main processes, the main process that has a decisive influence on the performance of semiconductor devices is the wafer processing process. In this step, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing step includes the following steps.
(1) A thin film forming process for forming a dielectric thin film to be an insulating layer, a wiring portion, or a metal thin film for forming an electrode portion (using CVD, sputtering, etc.)
(2) Oxidation process for oxidizing the thin film layer and the wafer substrate (3) Lithography process for forming a resist pattern using a mask (reticle) to selectively process the thin film layer and the wafer substrate (4) Resist Etching process that processes thin film layers and substrates according to patterns (eg, using dry etching technology)
(5) Ion / impurity implantation / diffusion process (6) Resist stripping process (7) Inspection process for inspecting further processed wafers The wafer processing process is repeated as many times as necessary to produce semiconductor devices that operate as designed. To do.
[0029]
FIG. 4 is a flowchart showing a lithography process that forms the core of the wafer processing process of FIG. This lithography process includes the following steps.
(1) Resist coating process for coating a resist on a wafer on which a circuit pattern has been formed in the preceding process (2) Exposure process for exposing the resist (3) Development process for developing the exposed resist to obtain a resist pattern {Circle around (4)} The semiconductor device manufacturing process, wafer processing process, and lithography process beyond the annealing process for stabilizing the developed resist pattern are well known and need no further explanation.
[0030]
In the present embodiment, in the step (7), since the inspection is performed using the electron beam apparatus as described above, a precise inspection can be performed, and the yield of the semiconductor device is improved. In addition, shipment of defective products can be prevented.
[0031]
【The invention's effect】
As described above, according to the present invention, the charged particle beam apparatus capable of compensating for the illuminance unevenness of the charged particle beam for illumination, the method of manufacturing the microdevice using the charged particle beam apparatus, and the charged particle beam apparatus It is possible to provide a microdevice that has been observed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of an electron beam apparatus as an example of an embodiment of the present invention.
FIG. 2 is a diagram showing a state in which the optical path of an irradiation beam is bent by an electromagnetic prism which is an optical path switching unit.
FIG. 3 is a flowchart showing an example of a semiconductor device manufacturing method of the present invention.
FIG. 4 is a flowchart showing a lithography process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Illumination electron optical system, 3 ... Electromagnetic prism, 4 ... Irradiation beam, 5 ... Stage, 6 ... Sample, 7 ... Objective lens, 8 ... Secondary electron, backscattered electron and reflected electron, 9 ... Imaging electron optical system, 10 ... MCP detector, 12 ... Photomapping optical system, 13 ... Imaging device camera, 14 ... Wehnelt electrode, 15 ... Anode

Claims (4)

The irradiation charged particle beam emitted from the irradiation source is made incident on the optical path switching means via the irradiation optical system, and the irradiation charged particle beam passing through the optical path switching means is incident on the sample surface via the objective optical system. The charged particle beam for observation emitted from the sample surface is incident on the optical path switching means via the objective optical system, and is moved in a direction different from the direction reaching the irradiation source by the optical path switching means. Charged particles for guiding the observation charged particle beam and causing the observation charged particle beam after passing through the optical path switching unit to enter a detection unit using a time delay integration type imaging device via an imaging optical system A line device that has a direction parallel to a plane including the locus of the charged particle beam for irradiation whose traveling direction is bent by the optical path switching unit and a direction in which integration is performed in the time delay integration type imaging device. Doing The charged particle beam apparatus according to claim and. The charged particle beam apparatus according to claim 1, wherein the optical path switching unit is an electromagnetic prism, and the power center of the sample surface and the electromagnetic prism is in a conjugate positional relationship in the charged particle beam optical system. Characterized charged particle beam device. A method for manufacturing a microdevice, comprising the step of observing the surface of the microdevice using the charged particle beam apparatus according to claim 1. A microdevice whose surface has been observed using the charged particle beam apparatus according to claim 1.

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