JPS5819042B2 - Position detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position detection method for detecting the electron beam or substrate position by scanning the boundary of the cleavage cross section with an electron beam using an element whose surface is a cleavage cross section of a thin substrate film. .

Generally, in electron beam exposure equipment, the scanning position of the electron beam,
Since the scanning area, scanning direction, etc. change due to the drift of the electron beam, and the position of the substrate also differs for each exposure, it is often necessary to correct this.

For this purpose, a mark indicating the reference position is set on the substrate to be scanned or a substrate at a certain position relative to this, and this mark is scanned with the electron beam, and the reflected electrons etc. generated at that time are detected and converted into the electron beam. I am trying to find the positional relationship with the board.

Conventionally, a commonly used positioning mark is one in which a metal film, such as an Au film, is deposited on a dielectric or semiconductor substrate, such as a Si substrate, by vapor deposition, sputtering, or the like, as shown in FIG.

To detect the position of this mark, the electron beam 4 is scanned across the edge.

At this time, since the amount of electrons reflected or absorbed by the substrate 1 and the metal differs depending on the electron beam, for example, when the electron detector 3 receives reflected electrons (including secondary electrons) and measures the current value, Near the boundary between the substrate 1 and the metal film 2, current characteristics as shown in FIG. 2 are exhibited with respect to the scanning distance of the electron beam.

In this case, the center of the effective distance A between the slopes when the beam passes through the boundary indicates the boundary between the substrate and the mark.

By finding the center position of this signal, the position of the mark can be detected.

However, although this method is simple, if the edge of the metal film 2 is sloping, the effective inclination of the slope portion will change midway, making accurate position detection impossible.

This is because the electron reflection direction differs between the flat part and the inclined part of the mark, and the electron detection efficiency changes.

- The purpose of the present invention is to eliminate such drawbacks, and in order to achieve this purpose, the position detection method of the present invention
A second material layer having a different amount of electrons reflected or absorbed by the electron beam with respect to the first substrate is formed on the material substrate, this is divided to create one cleavage cross section, and the cleavage cross section is The device is characterized in that a surface element is provided at a predetermined position on the substrate, an electron beam is scanned across the boundary of the cleaved cross section, and the position of the electron beam or the substrate is detected by signal processing.

The present invention will be described in detail below with reference to examples.

First, the principle of the present invention will be explained.

Recently, the present applicant has proposed a method for measuring the diameter of an electron beam with high accuracy in a separate application.

FIG. 3 is an explanatory diagram of the configuration of this proposed example.

In the figure, an Au film 2 is deposited on a Si substrate 1, and the Si substrate is split along the crystal cleavage plane.
Boundary 13 between Si substrate portion 11 and Au film portion 12 in cleaved cross section
The vicinity of 6 is the scanning area for measuring the electron beam diameter. When the electron beam 4 is scanned across this boundary 13 and the reflected electrons 4' are detected by the electron detector 3, the result is shown in Fig. 2. However, in this case, since the boundary 13 appears on the cleaved cross section of the Si substrate 11, it becomes a surface with uniform characteristics in terms of crystal structure, and A
Since the u-film surface 12 follows, the boundary 13 is sharply formed, and there is no room for uncertain or unstable parts to occur as in the conventional method.

Therefore, a highly accurate beam diameter can be obtained from the effective slope interval of the current characteristics.

Furthermore, the center indicates the 5i-Au boundary of the cleaved cross section with high precision.

The present invention performs position detection using an element having such characteristics.

FIG. 4 is an explanatory diagram showing the configuration of an embodiment of the present invention.

That is, four elements having the cleaved cross section obtained as shown in FIG. 3 on the surface are made, and each pair of these elements is arranged perpendicularly on another substrate as shown at 211 to 214.

By arranging it in this manner, it can be used as a mark indicating a reference position when correcting the scanning position, scanning area, scanning direction, etc. of the electron beam in an electron beam exposure apparatus, for example.

That is, the elements 21□, 214 are used as reference positions in the X-axis direction.
is used, and elements 210 and 2 are used as reference positions in the X-axis direction.
13 is used.

For example, with an electron beam in the X scanning direction of 20x, the element 21□,
By scanning across the boundaries of the cleavage section 214, the electronic detector output shown in FIG. 5 is obtained.

This corresponds to FIG.

The electron beam moves from another substrate to the level of the Si substrate, then follows a slope as it passes through the boundary and reaches the level of the Au film.

The center of this effective slope accurately indicates the 5i-Au boundary of the cleaved cross section.

In the figure, the slope is almost vertical, but regardless of the slope, the 5i-Au boundary position is determined at the center and can be used as a reference mark.

The same applies to the elements 210 and 213 in the X-axis direction.

Therefore, on the basis of this signal, it is possible to use it as is or to form a pulse indicating an accurate boundary position and use it for the above correction.

A comparator may be used to find the center of this slope.

That is, the power corresponding to the center of the slope is inputted as the reference human power of the comparator, the output from the electronic detector is inputted to the comparison input, and a signal is output when the inputs match.

As described above, according to the present invention, a highly accurate reference position mark can be set using the boundary of the cleaved cross section of the substrate thin film.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of the conventional example, FIG. 3 is an explanatory diagram showing the configuration of the proposed example, and FIG. 4 is an explanatory diagram showing the configuration of the present invention,
FIG. 5 is an explanatory diagram of the operation of the embodiment shown in FIG.
is a substrate, 2 is a metal film, 3 is an electron detector, 4 is an electron beam, 11 is a cleaved cross section of the substrate, 12 is a cross section of the metal film, 13 is a boundary, 20x is the electron beam scanning direction, 21□ to 214 are cleaved cross sections The element is shown.

Claims (1)

[Claims] 1 A second material substrate having a different amount of electrons reflected or absorbed by the electron beam with respect to the first substrate.
forming a material layer, splitting it to create a cleaved cross section, and providing an element having the cleaved cross section as a surface at a predetermined position on the substrate;
A position detection method comprising scanning an electron beam across the boundary of the cleaved cross section and detecting the position of the electron beam or the substrate through signal processing.