JPH0449670B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a marker for beam diameter measurement in a charged beam device or the like.

[Prior art and its problems] Charged beam devices require highly accurate beam diameter measurement in order to evaluate beam decomposition as a basic performance.

For example, recent charged beam devices for microfabrication technology are required to measure beam diameters of 0.1 μm or less with high precision for microfabrication in the submicron region.

An example of a conventional marker for beam diameter measurement is shown in FIG. The marker 1 is selectively formed on the substrate 2 using a material such as gold, which has a larger backscattering coefficient for a charged beam than the material of the substrate 2, such as silicon.
As a forming procedure (not shown), first, selectively removed portions of the resist are formed by a known resist pattern forming method using a light exposure method. Next, gold was deposited on the resist pattern including the removed portion, and a marker 1 was formed by a known lift-off method. The method for measuring the beam diameter will be described below. First, a reflected beam signal or a secondary electron signal (hereinafter referred to as a signal) from the marker obtained when a charged beam (hereinafter referred to as a beam) is scanned over a substrate on which a marker is formed is captured by a signal detector (second
figure). The distance obtained by measuring the scanning time width of 10% to 90% of this signal and multiplying it by the scanning speed is generally defined as the beam diameter (half width of the beam).

The signal obtained using conventional markers is shown in FIG. In the conventional case, excessive absorption of the reflected beam (including both the reflected component of the charged beam and the secondary electrons) on the side surface of the marker edge (as indicated by the dotted line 3 in Figure 3)
2) and extra reflection (solid line 42 in FIG. 4) caused waveform distortion as shown in the dotted circle in FIG. For this reason, the position of the white circle should be 10.
The measurement positions of %-90% are shifted to the positions of the black circles, and the distance d', which is larger than the accurate beam diameter d, is measured as the beam diameter. Measurement errors due to this waveform distortion have a non-negligible effect as the beam diameter becomes smaller, making it extremely difficult to measure beam diameters of 0.1 μm or less.

[Object of the Invention] An object of the present invention is to reduce beam diameter measurement errors in a charged beam device or the like and to accurately measure the beam diameter.

[Summary of the Invention] The main purpose of the present invention is to provide a marker that eliminates excess absorption and reflection of the reflected beam by the side surface of the edge marker by embedding the marker in the substrate, and that accurately measures the beam diameter with a distortion-free waveform. do.

[Effects of the Invention] According to the present invention, it is possible to detect a signal waveform without distortion even with a minute beam of about 0.1 μm when measuring the beam diameter of a charged beam device, etc., and it is possible to reduce measurement errors due to waveform distortion. .

[Embodiments of the Invention] An example of the beam diameter measuring marker of the present invention is shown in FIG. The marker 1 is made of the material of the substrate 2, such as a material that has a larger backscattering coefficient of a charged beam than silicon.
For example, it is formed by embedding it on the substrate 2 using gold. As for the formation procedure (not shown), first, a resist is used as a mask using a known resist pattern forming method using light exposure, and a groove is formed by etching the substrate using a known RIE technique (reactive ion etching). After gold plating to a thickness necessary to flatten the groove, the resist was peeled off to form a marker 1 buried in the substrate. The beam measurement method can be the same as the conventional method. When the beam is scanned over the substrate, a signal detector captures the reflected beam signal or secondary electron signal (hereinafter referred to as signal) from the marker obtained (Figure 6).10% of this signal.
The beam diameter can be determined by measuring the 90% scanning time width and multiplying it by the scanning speed. The signals obtained using the marker of the invention are shown in FIG. In the case of the present invention, a distortion-free signal waveform could be detected by eliminating excess absorption and reflection of the reflected beam on the side surface of the marker edge.

In the above embodiment, a gold plating method was used to form the marker, but the marker may be embedded using a lift-off method. The material for embedding is gold, which has a high backscattering coefficient.
Molybdenum, tungsten, chromium, titanium or compounds containing these elements, single alloys or laminates, other embedded materials include beryllium, boron, chromium, titanium or compounds containing these elements that have a small backscattering coefficient, An alloy alone or a laminate can also be used.

FIG. 7 shows another embodiment of the present invention, 5
is a material with a small backscattering coefficient. FIG. 8 shows the detected waveform 4 in that case. FIG. 9 shows still another embodiment of the present invention, in which 6 indicates a laminate.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional schematic diagram showing the schematic configuration of a beam diameter measurement board in a conventional charged beam device;
The figure is a waveform diagram showing the measurement error detected by the conventional method.
FIG. 3 is an explanatory diagram showing an example of extra absorption of a reflected beam, FIG. 4 is an explanatory diagram showing an example of extra reflection of a reflected beam, and FIGS. A schematic cross-sectional view showing a schematic configuration of a beam diameter measuring substrate in an example, and FIGS. 6 and 8 are characteristic diagrams showing waveforms detected by the method of the present invention. 1...Gold marker, 2...Silicon substrate, 3...
... Distorted waveform, 4 ... Normal waveform, 5 ... Material with small backscattering coefficient, 6 ... Laminate, 31 ... Charged beam, 32 ... Extra absorption of beam, 41 ...
Charged beam, 42... extra reflection of the beam.

Claims (1)

[Scope of Claims] 1. At least one layer of at least one material having a backscattering coefficient of a charged beam different from that of the substrate material is laminated in an opening selectively provided on a marker forming substrate. A beam diameter measurement marker characterized by being embedded and flattened. 2. The marker for beam diameter measurement according to claim 1, characterized in that a material having a larger backscattering coefficient than the substrate material is used as the embedding material. 3 Claim 1, characterized in that gold, molybdenum, tungsten, chromium, tantalum, titanium, or a compound or alloy containing these elements, alone or in a laminate, is used as the embedding material.
Beam diameter measurement marker described in Section 2 or Section 2. 4. The marker for beam diameter measurement according to claim 1, characterized in that a material having a smaller backscattering coefficient than the substrate material is used as the embedding material. 5 As embedding materials, beryllium, boron,
The beam diameter measuring marker according to claim 1 or 4, characterized in that carbon or a compound or alloy containing these elements is used alone or in a laminate.