JPS62150717A - Forming method of fine pattern - Google Patents

Abstract

PURPOSE:To obtain a forming method of fine pattern of high accuracy, by arranging a fine pattern capable of monitoring dimensional accuracy, on a semiconductor chip. CONSTITUTION:Monitor patterns 41, 42a, 42b and 43 are arranged on a semiconductor chip 3. Longitudinal dimensions of the monitor patterns 42a and 42b, and a gap dimension (b) between the two monitor patterns 42a and 42b are measured at the same time. Based on these dimensional differences, the dimensional differences in X-direction and Y-direction which generate at the time of electron beam exposure can be monitored. The dimensional accuracy of a scanning-connection part can be monitored by measuring the monitor pattern 41. The monitor pattern 43 is arranged at the scanning-connection part to show being the scanning-connection part. The dimensional accuracy in X-direction and Y-direction can be monitored by a dimensional difference between the width of the monitor pattern 42a, (a), and that of the monitor pattern 41, (a').

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming fine patterns on wafers and photomasks used in semiconductor integrated circuits.

[Conventional technology]

In recent years, semiconductor integrated circuits have become increasingly highly integrated and highly accurate. The photolithography process is an essential process in the production of semiconductor integrated circuits, and increasingly high precision is required.

Factors to improve the accuracy of the photolithography process include:
Examples include dimensional accuracy, defects, registration accuracy, etc., but electron beam exposure has made it possible to perform highly accurate patterning, and dimensional accuracy, registration accuracy, etc. have been improved.

However, as patterns become finer and more highly integrated, dimensional accuracy is increasingly required.

FIG. 4 is an enlarged view showing a photomask manufacturing method using a conventional electron beam exposure method. (1) is a photomask,
(2) is the arrangement, (3) is the semiconductor chip, and (4) is the monitor pattern.

Next, the process will be explained. In the photomask (11), the arrangement (2) is created by repeatedly drawing the semiconductor chip (3).
3) Semiconductor chips (
From the bottom of 3), the light is divided and exposed for each scan.

After the exposure is completed, a pattern including the monitor pattern (4) is formed through curing, development, rinsing, baking, and etching steps.

In the conventional fine pattern forming method, a monitor pattern (41) is placed on the semiconductor chip (3) as a pattern for monitoring the dimensional accuracy and its dimensional accuracy is measured.Therefore, a method for checking the dimensional accuracy of the photomask full However, it was only possible to measure the monitor pattern (4) and evaluate the in-plane variations of the photomask (1).

[Problem that the invention seeks to solve]

Since the conventional fine pattern forming method is configured as described above, it is only possible to monitor the dimensional accuracy due to the process, and it is not possible to monitor the dimensional accuracy of the electron beam itself.
There has been a problem in that it is impossible to accurately monitor the dimensional accuracy of the semiconductor chip itself.

This invention was made in order to solve the above-mentioned problems, and aims to obtain a method of forming fine patterns with higher precision by arranging a pattern whose dimensional accuracy can be monitored on a substrate created by electron beam exposure. purpose.

[Means for solving problems]

The fine pattern forming method according to the present invention makes it possible to measure the dimensional accuracy caused by electron beam exposure of a semiconductor chip by arranging a fine pattern that can monitor dimensional accuracy on a semiconductor chip or outside an effective area in a substrate. This is what I did.

[Effect]

The monitor pattern according to the present invention makes it possible to monitor the dimensional accuracy of the scanning joint part that is unique to electron beam exposure, and also monitor the dimensional difference between the X direction and the Y direction from the dimensional difference between the white pattern and the black pattern. make it possible to

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is the photomask, (2) is the arrangement, (
3) are semiconductor chips, (41), (42a), (42
b) and (43) are monitor patterns.

Next, the process will be explained. Semiconductor chips (3) are repeatedly arranged in a rectangular pattern η as shown in arrangement (2) on a photomask fil. Semiconductor chip (3) inside photomask (1)
) are sequentially processed into semiconductor chips (3) using an electron beam exposure device.
The semiconductor chip (3) below the dotted line is exposed in one scan. A monitor pattern (41) having a width of, for example, 3 μm is arranged in the horizontal direction at the scanning junction. Next, moving to the next scan, parts of the monitor pattern (41) are sequentially exposed.

A monitor pattern (42a) with a width of, for example, 3 μm is arranged vertically below the monitor pattern (41), and another identical monitor pattern (42b) is arranged vertically at a distance of, for example, 3 μm from this monitor pattern (42a). do.

After electron beam exposure, development and etching are performed to form these monitor patterns (41), (42a) and (42).
b) Measure. As in the past, by measuring the width a of the monitor pattern (42a), the absolute accuracy of the pattern dimensions can be confirmed, and by measuring the inside of the photomask (11), the accuracy of variations within this plane can be checked. .Vertical dimensions of monitor patterns (42a) and (42b) and two monitor patterns (42a) and (42b)
Measure the size of the gap between the two at the same time. From these dimensional differences, the dimensional difference between the X direction and the Y direction that occurs during electron beam exposure can be monitored.

In other words, due to an abnormality in the electron beam control system or stage,
This is because if there is a dimensional difference between the direction and the Y direction, the dimensional difference between the white pattern, which is an unexposed area, and the black pattern, which is an exposed area, will be promoted and become more noticeable.

Next, by measuring the monitor pattern (41),
The dimensional accuracy of the scanning joint can be monitored. A monitor pattern (43) is placed at the scan junction to indicate that it is a scan junction. Further, the dimensional accuracy in the X direction and the Y direction can also be monitored by the dimensional difference between the width a of the monitor pattern (42a) and the width a' of the monitor pattern (41).

Various factors that affect the dimensional accuracy caused by electron beam exposure include the following. Due to the size of the pattern absolute dimension value, due to the dimensional difference between the X direction and the Y direction, due to the scanning joint, due to variations within the pattern chip, due to the difference between the white pattern and the black pattern, due to the beam diameter Examples of the causes include scan linearity, differences in pattern density, variations in the photomask surface itself, and proximity effects.

When we investigate these factors, we find that, excluding the proximity effect, two factors, the dimensional difference at the scanning junction and the dimensional difference between the X and Y directions, have a large effect on the dimensional accuracy of the semiconductor chip itself. It turned out that there was.

Of course, in-plane variations and absolute accuracy of a photomask are also important as dimensional accuracy, but until now they have been relatively easy to monitor.

From these points of view, the present invention monitors the dimensional accuracy of the scanning joint, which is unique to electron beam exposure, and
By arranging a pattern that monitors the dimensional difference between the white pattern and the black pattern caused by the dimensional difference between the direction and the Y direction, the dimensional accuracy can be grasped reliably and precisely, and it is extremely effective for high-precision formation of fine patterns. Verified.

In the above embodiment, the case of a photomask has been described, but the same effect can be achieved with a semiconductor wafer or the like.

Also, although the monitor pattern was placed inside the semiconductor knob,
As shown in FIG. 2, it may be placed outside the effective area.

Furthermore, although three monitor patterns are arranged, the number of monitor patterns arranged may be changed as necessary.

Furthermore, when monitoring the proximity effect, it is possible to monitor by arranging a finer monitor pattern.

Furthermore, in order to increase the dimensional accuracy, monitor patterns may be arranged according to influencing factors such as beam diameter, scan linearity, difference in pattern density, and variations within the photomask itself.

Furthermore, you can place the monitor pattern anywhere (
, the scan junction may be any location as long as it is a scan junction.

Furthermore, although the vertical direction self-pattern and black pattern are shown, if the width of the exposed part and the width of the unexposed part are designed to be the same dimension, for example, a square pattern (51 ) and other patterns such as a rectangular pattern (52) surrounding this pattern (51) with a constant width and a constant interval.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to monitor the dimensional accuracy of the scanning joint part peculiar to electron beam exposure, and to
The configuration is such that a pattern is placed to monitor the dimensional difference between the white pattern and the black pattern caused by the dimensional difference in the direction, so it is effective in forming fine patterns with high precision, and it is effective in forming fine patterns with high accuracy. This has the effect of providing a fine pattern forming method that can produce high-quality semiconductor chips at a high yield.

[Brief explanation of drawings]

FIG. 1 is an enlarged view showing a fine pattern forming method according to one embodiment of the present invention, FIG. 2 is an enlarged view showing a fine pattern forming method according to another embodiment of the present invention, and FIG. 3 is an exposed area and an unexposed area. FIG. 4 is an enlarged view showing another example of a monitor pattern in which portions have the same size. FIG. 4 is an enlarged view showing a conventional fine pattern forming method. (11 is a photomask, (2) is an arrangement, (3) is a semiconductor chip, (41), (42a), (42b), (43)
, (51) and (52) are monitor patterns. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) In an electron beam exposure method in which a substrate is exposed by continuously scanning an electron beam, a pattern for monitoring the dimensional accuracy of the exposure is drawn and arranged on each chip or outside the effective area within the substrate. A method for forming fine patterns characterized by: (2) The fine pattern according to claim 1, characterized in that the pattern for monitoring the dimensional accuracy is a pattern capable of monitoring the scan connection portion of the electron beam and the dimensional difference between the X direction and the Y direction. Pattern formation method. (3) The method for forming a fine pattern according to claim 2, wherein the pattern for monitoring the dimensional accuracy is a pattern indicating a scanning connection portion of the electron beam. (4) The fine pattern forming method according to claim 2, wherein the pattern for monitoring the dimensional accuracy is a pair of patterns having the same width and interval.