JPS6227728B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam position detection method used for positioning an electron beam and a pattern when fabricating patterns such as integrated circuits using electron beams.

BACKGROUND ART Conventionally, a method has been used in which a pattern of an integrated circuit or the like is exposed using an electron beam. In this case, when exposure of a pattern is repeatedly performed on the same substrate, it is necessary that the mutual positioning of the electron beam and the pattern is performed accurately.

To this end, conventionally, unevenness is attached to the substrate as a position reference mark (hereinafter simply referred to as mark), and the area including this mark is scanned with an electron beam to detect the positional relationship between the electron beam and the substrate. things are being done.

In order to more fully understand the present invention, the prior art will be explained in more detail with reference to FIG. Marks 2 are formed on a substrate 1 in advance. This mark may be an oxide film or a metal pattern.
Also, although the figure shows a convex shape, it may of course be concave. An electronic resist 3 is deposited on the mark 2 on a flat surface. To detect the position, while scanning the mark 2 with the electron beam 4 as shown in the figure,
Measure the next electron signal. This is called a position detection signal. The position detection signal has a waveform such as 5 in FIG.

Position detection is performed by the circuit shown at the bottom of FIG. That is, the position detection signal detected by the detector 6 is smoothed and differentiated by the pulse circuit 7, and a pulse is generated at the time when the threshold value is exceeded, and the pulse is sent to the computer or microprocessor 8.
The computer or microprocessor 8 detects the mark position based on the time at which the pulse is sent.

However, noise is generally superimposed on the position detection signal, and since the position detection signal is small, the signal-to-noise ratio (S/N ratio) is quite low, and the position detection error is large.

In order to solve this problem, it is necessary to repeatedly scan marks provided on a substrate and average data regarding a large number of positions obtained from detection signals to improve position detection accuracy. For this reason, the conventional method requires a lot of time for position detection, and also has the drawback that the mark may deteriorate due to electron beam irradiation because the mark is irradiated with the electron beam for a long time. .

An object of the electron beam position detection method according to the present invention is to solve the drawbacks of the above-mentioned conventional methods and to perform high-speed and highly accurate electron beam positioning.

That is, according to the present invention, high-speed and highly accurate electron beam position detection can be performed by removing the resist deposited on the mark by irradiating the mark with an ion beam, and then irradiating the mark with the electron beam to position the mark. Ru.

Although the type of ion beam is not particularly limited, an oxygen ion beam is most preferable for removing organic compound resist. This is because the oxygen ion beam has a particularly high etching rate for organic compounds.

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

FIG. 3 is a process sectional view showing an example.

(1) Element pattern 52 and mark 5 on substrate 51
form 3.

(2) An electronic resist 54 is attached thereon, and then an oxygen ion beam A is irradiated so that at least a portion of the mark 53 is included.

(3) The electron resist 54 in the area irradiated with the oxygen ion beam A is removed, and an opening 55 in the area including at least a portion of the mark 53 is formed.

(4) By scanning a portion of the opening 55 with the electron beam 56 and detecting the relative position of the mark 53 and the electron beam, a pattern of the electronic resist 54 is formed in a desired positional relationship with the element pattern 52.

Although positioning is required during ion beam irradiation in the above process, this accuracy does not pose a problem since it is only necessary to align the marks 53 to include them.

As in this process, by removing the resist above the mark using an ion beam and then irradiating the mark with an electron beam to detect the position, the electron beam is applied to the mark without removing the resist above the mark. It enables much faster and more accurate positioning than detecting the position by irradiation.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the vicinity of a mark to explain the conventional method, Fig. 2 is a block diagram of a mark detection signal and a processing circuit, and Fig. 3 is a process cross-sectional view of an embodiment of the present invention. 2 shows a state in which an element pattern and a mark are present, 2 shows a state in which an electron resist is applied and an oxygen ion beam is irradiated near the mark, 3 shows a state in which an opening is formed near the mark, and 4 shows a state in which the mark is scanned with an electron beam. state. In addition, in the figure, 1, 51 are the substrates, 2, 53
are marks, 3 and 54 are electronic resists, 4 and 56 are electron beams, 5 is a position detection signal, 6 is a detector, 7 is a pulse circuit, 8 is a computer or microprocessor, 52 is an element pattern, and 55 is an electronic resist represents the opening of

Claims (1)

[Claims] 1. In the step of detecting a position reference mark provided on a workpiece using an electron beam in an electron beam exposure method, after removing the resist on the position reference mark by irradiating the position reference mark with an ion beam, the position reference mark is exposed to an electron beam. An electron beam position detection method characterized by positioning by irradiating a beam.