JPH0544172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an electron beam exposure method, and more particularly to a method for detecting exposure deviation due to resist charge up.

(2) Background of the Technology Electron beam exposure methods are used, for example, in the field of semiconductor device manufacturing to form fine patterns on masks, reticles, or wafers.

In the electron beam exposure method, a resist is applied onto a base material such as a mask on which a pattern is to be formed, and an electron beam is scanned over the resist to expose the pattern. There is a problem in that the trajectory of the electron beam is bent and the exposure is generally deviated from the target position by several μm to 10 μm.

One way to prevent such exposure deviations due to charge up of the resist (hereinafter abbreviated as "charge up exposure deviation" or simply "exposure deviation") is to prevent the resist charge up itself. No preventive measures have been established at present.

Another measure to prevent charge-up exposure deviation is
The method is to detect the amount of exposure deviation, correct the exposure data in advance based on it, and perform exposure. However, conventionally, there has been no method for easily and accurately detecting charge-up exposure deviation.

(3) Object of the Invention In view of the above circumstances, an object of the present invention is to provide an electron beam exposure method that allows charge-up exposure deviation to be detected easily and accurately.

(4) Structure of the Invention The electron beam exposure method according to the present invention includes placing portions of marks for detecting charge-up exposure deviation in advance at a plurality of positions within the exposure surface of a substrate on which a pattern is to be formed, before exposing the substrate pattern. After exposure, the base material pattern is exposed, and other parts of the mark are sequentially overlapped and exposed at the position. By inspecting the exposed marks in this manner, it is possible to easily and accurately detect charge-up exposure deviations.

(5) Embodiments of the invention Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.

FIG. 1 shows exposure of a mask by the electron beam exposure method of the present invention. A mask 1 (approximately 100 mm square) is set on a stage (not shown) of an electron beam exposure apparatus, and after positioning using positioning marks on the mask or the stage, exposure is performed. Now, if we are to sequentially expose from position 1a to 1e along the arrow line, the first position 1a
In this case, the charge up amount is small and the exposure deviation is small, but as the position moves from position 1b, 1c, 1d, and 1e, the charge up amount increases and the exposure deviation becomes large. Therefore, the present invention provides such a plurality of positions 1
Exposure deviation detection marks are exposed to light in a to 1e to enable detection of exposure deviation.

An example of the mark for detecting exposure deviation is shown in FIG. This mark 10 consists of two marks 10a, 1
Contains 0b. The mark 10a is a reference mark for exposing the positioning accuracy of the electron beam exposure apparatus, as will be described later, and the mark 10b is a mark for detecting charge-up exposure deviation. The mark 10a consists of a central square pattern 11 and a surrounding cross pattern 12, and the mark 10b similarly consists of a square pattern 13 and a cross pattern 14. The size of the mark 10 is on the order of 10 μm to 2 mm, and can be appropriately selected within this range.

Next, a method of exposing the exposure deviation detection mark 10 to the positions 1a to 1e of the mask 1 will be explained with reference to FIG. Roughly speaking, the mark 10 is exposed in the following steps in conjunction with the exposure of the mask pattern.

(b) First, before exposing the mask pattern,
As shown in FIG. 3A, only the square patterns 11 and 13 are sequentially exposed at each position 1a to 1e.

(b) Next, as shown in FIG. 3B, the cross pattern 12 of the mark 10a is sequentially exposed at each position 1a to 1e.

(C) Next, while exposing the mask pattern, the cross pattern 14 of the mark 10b is sequentially exposed at each position 1a to 1e as shown in FIG. 3C.

Charge-up exposure deviations can be detected by inspecting the marks shown in FIG. 3C exposed as described above, and the inspection method will now be described.

(a) First, regarding the reference mark 10a, there is almost no charge up in the resist at the stage of exposing the pattern 12 (FIG. 3B), and the charge up exposure deviation can be completely ignored. Therefore, if the positioning accuracy of the electron beam exposure device is ideal, pattern 12 is equal to pattern 1.
There should be no positional deviation with respect to 1. In other words, by inspecting the positional deviation of the pattern 12, the positioning error of the electron beam exposure apparatus can be detected. If a positioning error is detected, it is used for correction when detecting an exposure shift using the mark 10b, as will be described later.

(b) Next, regarding the exposure deviation detection mark 10b, since the charge increase gradually increases during the exposure stage of the pattern 14 (FIG. 3C), the pattern 14 is placed at the normal position (indicated by the dotted line) as shown in the figure.
exposed to light. That is, pattern 1
Charge-up exposure deviation can be detected by inspecting the positional deviation of 4. However, as described above, if a positioning error is detected using the reference pattern 10, the pattern 1
Since the positional deviation of pattern 4 includes the positional deviation due to this positioning error, it is necessary to correct the positional deviation of pattern 14 by the positional deviation of pattern 12 in order to obtain accurate charge-up exposure deviation.

Incidentally, if a mark 20 consisting of a vernier pattern as shown in FIG. 4 is used as the exposure deviation detection mark instead of the mark 10 shown in FIG. 2, the exposure deviation can be measured accurately. mark 20
Similarly, it has a reference mark 20a and an exposure deviation detection mark 20b. The exposure procedure for the mark 20 is to first expose the mark 20 before exposing the mask pattern.
The patterns 21 and 23 on the left side of marks 20a and 20b are sequentially exposed at positions 1a to 1e, and then the pattern 22 on the right side of mark 20a is sequentially exposed at positions 1a to 1e. Thereafter, while performing mask pattern exposure, the pattern 24 on the right side of the mark 20b is exposed at positions 1a to 1e. A positioning error is detected by the positional deviation between the patterns 21 and 22, and an exposure deviation is detected by the positional deviation between the patterns 23 and 24.

The exposure method for the mask 1 described above can be applied to a reticle in almost the same way. However, in the case of a reticle, the exposure deviation detection mark should be exposed only at peripheral positions such as positions 1a, 1b, 1d, and 1e, avoiding central positions such as position 1c shown in FIG.

Next, FIG. 5 shows an example of direct exposure of a wafer by the method of the present invention. In this case as well, the exposure deviation detection marks 10 or 20 are exposed at positions 2a to 2e on the wafer 2 in the same manner as in the case of the mask described above. The difference between direct wafer exposure and that using a mask or reticle is that the offset amount is corrected for each chip. However, exposure deviations on the order of microns may occur even within the chip.
For example, as shown in Figure 6, chip 3 (approximately 6 mm square)
consists of nine fields 4 (each approximately 2 mm square), the chip pattern exposure is performed at position 3a.
When starting from position 3a, the exposure deviation is small at position 3a, but normally the exposure deviation increases as the distance from position 3a increases. Therefore, an exposure deviation detection pattern 10 or 20 is exposed at peripheral positions 3a to 3h of each field to detect charge-up exposure deviation. However, since the field 4a at the center is an effective field of the chip, it is generally not possible to expose the exposure deviation detection mark.
In this case, it may be determined by calculation from the exposure deviation amounts of the surrounding positions 3a to 3h.

(6) Effects of the Invention As described above, according to the method of the present invention, charge-up exposure deviation can be detected by detecting the exposure deviation detection mark, and the exposure accuracy of the mask or wafer can be known, so it is possible to determine whether the product is good or defective. It becomes possible to judge whether the product is good or not.

Furthermore, if exposure is performed by correcting the exposure data based on the exposure deviation information obtained in this way, and the exposure deviation is detected by exposing the exposure deviation detection mark at the same time, even higher accuracy can be achieved. Exposure is achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a mask exposure method using the electron beam exposure method of the present invention, FIG. 2 is a diagram showing an example of a pattern of marks for detecting charge-up exposure deviation,
3 is a diagram showing the exposure process of the mark shown in FIG. 2, FIG. 4 is a diagram showing another pattern example of the mark for detecting charge-up exposure deviation, and FIG. FIG. 6 is a diagram showing the exposure method, and is a diagram showing a wafer chip. 1...mask, 2...wafer, 3...chip,
4...Field, 1a to 1e, 2a to 2e, 3
a to 3h... position, 10, 20... mark for charge up light deviation detection, 10a, 20a... reference mark, 10b, 20b... mark for exposure deviation detection, 11, 12, 13, 14, 21, 22, 2
3, 24...pattern.

Claims (1)

[Claims] 1. In an electron beam exposure method in which a resist is applied onto a substrate on which a pattern is to be formed and the resist is scanned with an electron beam to expose the pattern, a resist charge drop is applied to a plurality of positions within the exposure surface of the substrate. A part of the mark for detecting exposure deviation of the pattern is exposed in advance before exposing the base material pattern, and then, while exposing the base material pattern, other parts of the mark are sequentially overlapped and exposed at each of the positions. An electron beam exposure method characterized by: