JPS6232612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure method in which an electron beam is aligned with an existing pattern for exposure when manufacturing a pattern for an integrated circuit or the like.

Conventionally, a method has been used to expose patterns such as integrated circuits using electron beams, but in this case, when the pattern is repeatedly exposed on the same substrate, the interaction between the electron beam and the pattern may occur. It is necessary that alignment be performed accurately.

For this purpose, concavities and convexities of, for example, SiO ₂ have been traditionally attached to the substrate as position reference marks (hereinafter simply referred to as marks), and the area including this mark is scanned with an electron beam, and the electron beam and the substrate are separated. Detection of the positional relationship between

In order to more fully understand the present invention, the prior art will be explained in more detail with reference to FIG. Board 1
Mark 2 is formed on top of the mark 2 in advance. This mark may be an oxide film or a metal pattern. For position detection, use mark 2 as shown in Figure 1.
While scanning with the electron beam 3, signals of reflected electrons or secondary electrons are measured.

This signal is named a position detection signal. The position detection signal has a waveform such as 4 in FIG. This is processed by the circuit shown in the block diagram at the bottom of FIG.
That is, the pulse circuit 6 smoothes the noise of the signal detected by the detector 5, differentiates it, generates a pulse at the time when it exceeds a threshold value, and sends it to a computer or microprocessor 7. A computer or microprocessor 7 detects the position of the mark 2 based on the time at which the pulse is sent. However, such conventional mark position detection methods cannot detect the position with high precision when the height or depth of the mark is not large, or when the atomic numbers of the substrate and mark materials are not far apart. However, it has the disadvantage that exposure cannot be performed with high precision alignment.

An object of the electron beam exposure method according to the present invention is to solve these conventional drawbacks and to enable exposure with highly accurate positioning.

That is, according to the present invention, the mark is irradiated with an ion beam, the mark position is detected, and the irradiation position of the object to be processed with the electron beam is determined based on the detection signal, and the electron beam exposure is performed. .

EMBODIMENT OF THE INVENTION Hereinafter, the electron beam exposure method based on this invention will be explained in detail based on the Example.

FIG. 3 is an explanatory diagram showing an embodiment of the present invention.
A mark 2 is formed in advance on a substrate 1, and an electronic resist is applied thereon (not shown in the figure). Before exposing the electron resist with the electron beam 3, the mark 2 is first scanned with the ion beam 31 to detect the relative positional relationship between the ion beam and the mark 2. The positional relationship between this ion beam and mark 2, and the ion beam 31 and electron beam 3 determined in advance.
Since the positional relationship between the mark 2 and the electron beam 3 can be determined from the positional relationship between the mark 2 and the electron beam 3, it is possible to expose a pattern with the electron beam 3 at a desired position from the mark 2.

The method of the present invention differs from the conventional electron beam mark 2.
It can be performed with higher accuracy than detecting the position of. This is because the ion beam penetrates into the sample less than the electron beam, and only the collision phenomenon on the surface contributes as a mark position detection signal, so there is no need to increase the thickness of mark 2. This is because a signal with a higher S/N ratio can be obtained by scanning the mark with an ion beam.

FIG. 4 is a diagram for explaining a method for determining the relative positions of the ion beam and the electron beam. A mark 42 is formed on the edge of the sample or on the sample holder 41. This is scanned by the ion beam 31 to find the relative position between the mark and the ion beam, and then the mark 42 is scanned by the electron beam 3 to find the relative position between the electron beam and the mark. The relative positions of the ion beam and the electron beam are determined from these two relative positions. Since the mark 42 is formed on the edge of the sample or its holder, it is possible to form a thick mark that cannot be formed on a normal chip, and the mark has a high S/N ratio even for electron beams. Is possible.

As described in detail above, according to the electron beam exposure method according to the present invention, exposure can be performed with highly accurate alignment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining a conventional mark detection method, and FIG. 2 is a block diagram of a mark detection signal and a processing circuit. FIG. 3 is a sectional view for explaining the electron beam exposure method of the present invention, and FIG. 4 is a sectional view for explaining one method for determining the relative position of the ion beam and the electron beam. In addition, in the figure, 1, 41 are the substrates, 2, 42
3 represents a mark, 3 represents an electron beam, 4 represents a waveform of a position detection signal, 5 represents a detector, 6 represents a pulse circuit, 7 represents a computer, and 31 represents an ion beam.

Claims (1)

[Claims] 1. When exposing an object having a position reference mark to an electron beam, the position reference mark is irradiated with an ion beam to detect the position of the position reference mark before the electron beam exposure, and the position of the position reference mark is detected based on the detection signal. An electron beam exposure method characterized by determining the irradiation position of the beam onto an object to be processed.