JPH035080Y2 - - Google Patents

Description

[Detailed explanation of the idea] Recently, exposure equipment that uses electron beams or ion beams has been attracting attention as a means of manufacturing LSI devices and VLSI devices. In such an exposure apparatus, a photosensitive resist is coated on an exposure material and exposed with an electron beam or an ion beam, and the minimum line width is about 0.2 μm due to electrons scattered from the material. Recently, multilayer film coating has enabled exposure of around 100 Å, and the demand for finely focused electron beam exposure equipment is increasing. Now, in order to analyze the exposure width obtained with this multilayer film technology, it is necessary to know the diameter of the beam spot. Generally, the knife edge method is used to measure the beam diameter, but there is a limit to the beam diameter that can be measured depending on the knife edge used.In particular, when the measurement beam diameter becomes small, the fidelity of the measurement decreases due to the influence of scattered electrons. Therefore, for example, an aperture P is placed between a shielding member S such as a knife edge body used in the knife edge method and the detection element D to prevent such scattered electrons from entering the detection element D. (Figure 1). However, although some of the scattered electrons B can be prevented from entering the detection element D, there are still some scattered electrons.
B ₁ enters the detection element.

In view of these points, in the present invention, as shown in FIG. 1, if the aperture P is brought into close contact with the detection element D (see P'), the scattering that passes from the shielding member S through the aperture of the aperture and enters the detection element. This method was developed with the focus on the fact that the number of electrons is significantly reduced.The charged beam emitted from the charged beam generating means is focused on a plane on which a beam shielding member is arranged and scanned on the plane, and by this scanning, the charged beam is In an apparatus for measuring properties of a charged beam based on a charged beam detected by a charged beam detection means disposed on a beam path, a scattered beam having a hole in a charged beam incident surface of the charged beam detection means is provided. A novel method in which the width of the hole is approximately αL, where the aperture angle of the charged beam is α, and the distance between the edge of the beam shielding member and the scattered beam shield is L, by closely contacting the shielding member. The present invention provides a charged beam measuring device with a high level of accuracy.

FIG. 2 is a schematic diagram of a charged beam measuring device showing an embodiment of the present invention. In the figure, reference numeral 1 denotes an electron gun, and an electron beam emitted from the electron gun is focused by focusing lenses 2 and 3, and focused by an objective lens 4 onto a horizontal plane on which a knife edge body 5 is disposed. Although the knife edge bodies are not shown, they are actually arranged in two directions, X and Y, respectively. Note that 6 is an aperture of the objective lens 4. The electrons focused on the horizontal plane are scanned by a deflector 7 on the horizontal plane. The deflector 7 operates in accordance with a deflection signal from a deflection power source 10 which receives instructions from a digital computer (hereinafter referred to as CPU) 9 via a DA converter 8. Although the deflector is not shown, it actually consists of a deflector for scanning in the X direction and for scanning in the Y direction. Below the knife edge body 5 is a PN, for example, which amplifies the incoming electron beam as a beam current.
A semiconductor detection element 11 such as a junction is arranged. On the electron beam incident surface of the semiconductor detection element, a thin metal plate 13 (for example, 20 μm thick) for shielding scattered electrons has a small hole 12 in the center.
m, 20 μm diameter molybdenum aperture) are in close contact. Note that instead of closely adhering the metal plate, a metal layer may be attached to the beam incidence surface of the semiconductor detection element by vapor deposition or the like. Of course, in this case as well, the portion of the hole 12 for beam incidence must not be vapor-deposited. The size of the beam entrance hole is determined as follows. That is, as shown in FIG. 3, when an electron beam with an opening angle α scans on a horizontal plane including the edge of the knife edge body 5, the detection element detects the beam that has gone straight without being blocked by the knife edge body 5 during the scanning process. 11 is determined to be approximately equal to the minimum size necessary for detection. Therefore, the length that the beam scans on the horizontal plane including the edge of the knife edge body 5 is D, the distance between the edge portion and the metal plate 13 is L, and the diameter of the beam incidence hole in the metal plate for shielding scattered electrons is Letting be A, it can be expressed as A=D+αL. Incidentally, the scanning length D is extremely small, and is significantly smaller than the size αL of the hole on the metal plate 13 necessary for injecting the electron beam having the aperture angle α. Therefore, the diameter A of the beam incidence hole of the scattered electron shielding metal plate can be considered to be approximately αL.
Furthermore, the thinner the metal plate or metal layer 13 that is closely attached to the beam incidence surface of the semiconductor detection element 11, the smaller the hole 1.
The influence of scattered electrons generated at the edge part 2 can be reduced, but if it is made too thin, the scattered electrons will pass through, so it must be created with a thickness that does not allow the scattered electrons to pass through. The thickness is determined by the acceleration voltage of the beam. Note that since the PN junction of the semiconductor detection element 11 is located at a certain depth (e.g. 0.2 μm to 3 μm) from the beam incidence surface, detection is possible even if a metal plate or metal layer is brought into close contact with the surface of the detection element. There is no effect on the characteristics of the element.

The electron beam detected by the detection element 11 is current amplified and sent to the display device 15 via the amplifier 14.
The signals are sent to the CPU via the amplifier 14 and AD converter 16, respectively. The display device 15 includes the deflection power source 10.
A deflection signal is being sent from CPU9.
A command signal is sent via the DA converter 17.

In such a device, when the horizontal plane on which the knife edge body 5 is arranged is scanned with a beam having a rectangular cross section according to a command from the CPU 9, the hole 12 of the metal plate 13 is scanned.
The electron beam that enters the semiconductor detection element 11 through the detector is sent as a beam current signal to the CPU 9 via the amplifier 14 and the AD converter 16, and to the display device 15 via the amplifier 14. Then, the CPU calculates beam dimensions, focusing conditions, etc. from the beam current signal. In this case, the accuracy can be increased by differentiating the beam current signal once or twice in the CPU to calculate the beam dimensions, etc.
See No. 157027 and Japanese Patent Application No. 55-523137. ) In the present invention, a metal plate 1 having a hole is provided on the charged beam incident surface of the charged beam detecting means.
3 are brought into close contact with each other, and the width of the hole is formed to be approximately aL when the opening angle of the charged beam is a and the distance between the edge portion of the knife edge body 6 and the metal plate 13 is L. Most of the electrons scattered when the electrons from the electron gun collide with the knife edge body 5 hit the metal plate 13 that is in close contact with the beam incidence surface of the semiconductor detection element 11, so that the knife edge body 6 that enters the semiconductor detection element 11 The number of scattered electrons from Moreover, since a sufficient amount of electrons can be detected by the detection element to measure the beam diameter even when the number of scattered electrons entering the detection element is small, the beam diameter can be measured with extremely high accuracy.

The present invention can be applied not only to spot beams but also to square beams and rectangular beams. or,
It can be applied not only to electron beam measurements but also to ion beam measurements. Further, another beam detection element may be used instead of the semiconductor detection element, but in consideration of detection accuracy, a detection element having an amplifying effect (a photoelectric conversion element, such as a combination of a scintillator and a photomultitube, etc.) is selected. It is also convenient to create the knife edge body by vapor depositing or sputtering a metal such as gold on a microgrid made of a commercially available polymeric material. In other words, this microgrid has a copper mesh with a diameter of 3 mm (the mesh holes are
200 μm to 300 μm) on which a polymer material with countless holes of about 0.3 μm to 5 μm is placed, and if any of the holes is used, hole 1 of the metal plate on the semiconductor detection element
2 (pore diameter is, for example, 100 μm to 200 μm), which is convenient.

[Brief explanation of the drawing]

Fig. 1 is a diagram to supplement the explanation of conventional problems and points of view of the present invention, Fig. 2 is a schematic diagram of an electron beam measuring device showing an embodiment of the present invention, and Fig. 3
FIG. 3 is a diagram for explaining a hole 12 for beam incidence. 2, 3...Focusing lens, 4...Objective lens, 5
... knife edge body, 7 ... deflector, 9 ... electronic computer (CPU), 11 ... semiconductor detection element, 12
... hole, 13 ... metal plate, 15 ... display device.

Claims (1)

[Scope of utility model registration request] A charged beam emitted from a charged beam generating means is focused on a plane on which a beam shielding member is disposed and scanned on the plane, and as a result of the scanning, a charged beam is detected by a charged beam detecting means disposed on a charged beam path. In an apparatus for measuring the properties of a charged beam based on the charged beam, a scattered beam shielding member having a hole is brought into close contact with the charged beam incident surface of the charged beam detecting means, and the width of the hole is set to the width of the charged beam. A charged beam measuring device characterized in that the charged beam measuring device is formed to have a size approximately αL, where α is an opening angle and L is a distance between the edge portion of the beam shielding member and the scattered beam shielding object.