JPS6214089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring two exposed areas that are exposed next to each other.

For example, when attempting to expose a chip 1 as shown in FIG. 1 using an electron beam exposure device, one
When the chip is large, the chip pattern is divided into field units such as fields F1, F2, F3, F4, etc., and each time one field is exposed, the stage is moved and the next field is exposed. .

In this case, since the connection accuracy between adjacent fields is an important factor in pattern creation, measurement of this connection accuracy has conventionally been carried out.

Now, connection accuracy includes connection accuracy in a direction parallel to the boundary between adjacent fields and connection accuracy in a direction perpendicular to the boundary.

In the conventional connection accuracy measuring method, as shown in FIG. 2a, the connection accuracy in the direction parallel to the boundary 2 between fields is measured as follows. In other words, for example, 1 is placed at the right end of field FL on the left side of boundary 2.
Main scale graduation lines 3 having a line width of μm are drawn at a pitch of 5 μm. At this time, the center line C is drawn longer than the other lines so that it can be easily identified. Next, move the stage and place the left end of the right field FR, for example 4.9μ.
A vernier scale scale line 4 is drawn with a pitch of m so that its center line CS is at the same position as the center line C of the main scale scale line 3. After the drawing is completed, the drawn pattern is observed using a means for observing an enlarged image, such as an optical microscope. If the connection accuracy in the direction parallel to boundary 2 is extremely high, the center lines C and CS will match, but if the connection is misaligned, the main scale scale line and vernier scale line will be separated from the center line depending on the amount of misalignment. The two lines match, and the accuracy of the connection can be determined by the position of the matching lines. For example, if the second lines in the Y direction from the center line match, it can be determined that the field on the right side is deviated from the field on the left side by 0.2 μm in the Y direction.

In addition, the accuracy in the direction perpendicular to the boundaries of adjacent fields is determined by exposing lines 5 and 6 of the same thickness at a predetermined interval across the boundary 2, as shown in Figure 2b, and after exposure, the two The distance T between the lines 5 and 6 is measured by, for example, an enlarged image observing means equipped with a length measuring device, and the connection accuracy is determined from the difference between the measured distance and the planned distance.

Therefore, in conventional measurement methods, it is easy to measure the connection accuracy in the direction parallel to the boundary by reading the scale lines, but it is extremely troublesome to measure the connection accuracy in the direction perpendicular to the boundary. .

The present invention has been made to solve these conventional drawbacks, and one embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 3 shows the main scale scale line and vernier scale scale line exposed according to the present invention. In Figure 3, 2 indicates the adjacent field whose connection accuracy is to be measured.
It is the boundary between FL and FR.

The measurer places boundary 2 at the right end of the left field FL.
The main scale graduation line 7 is exposed at an angle of 45° to the main scale scale line 7, and the main scale scale line 7 is further exposed at a right angle to the main scale scale line 7 (therefore, at an angle of 135° to the boundary 2). Expose 8.

Next, move the stage and move to the field on the right.
At the left end of the FR, a vernier scale scale line 9 that is paired with the main scale scale line 7 is exposed so that its center line CS is in line with the center line C of the main scale scale line 7, and the main scale scale line 9 is The vernier scale graduation line 10 that is paired with the line 8 is exposed so that its central line CS is aligned with the central line C of the main scale graduation line 8. Incidentally, the exposure is performed so that the directions of these vernier scale lines 9 and 10 coincide with the directions of the main scale scale lines forming a pair.

Now, these scale lines have an angle of 45° (or 135°) with respect to boundary 2. Therefore, if the right field FR deviates from the left field FL by b in the direction perpendicular to boundary 2, then
As is clear from Fig. 4, the vernier scale line p is as if it were observed when the field FR was shifted parallel to (upwards) boundary 2 by b compared to the position p' when there was no shift at all. The vernier scale line q appears to be in the position q′ when there is no deviation at all, as if the field FR is parallel to the boundary 2 (downwards).
The position appears to be the one observed when shifted by b.

Therefore, if field FR deviates from field FL by a in the direction parallel to boundary 2 and by b in the perpendicular direction, the reading value M of the deviation amount by scale lines 7 and 9 is a+b, while the scale line The reading value N of the amount of deviation based on 8 and 10 is a-b.

Therefore, after the exposure is completed, the amount of deviation M by the scale lines 7 and 9 is read, and the reading value N of the amount of deviation by the graduation lines 8 and 10 is read, and from the above-mentioned relationship, the amount of deviation a in the direction parallel to the boundary 2 is conversely read. can be found from a=M+N/2, and the amount of deviation b in the direction perpendicular to the boundary 2 can be found from b=M-N/2.

As described above, according to the present invention, it is possible to easily measure the inter-field connection accuracy in the direction parallel to and perpendicular to the field boundaries by simply reading the scale lines and performing simple calculations.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining that a chip is exposed as a set of multiple fields, Fig. 2 is a diagram for explaining a conventional method, and Fig. 3 is a diagram for showing an embodiment of the present invention. FIG. 4 is a diagram for explaining the effect that a deviation in the direction perpendicular to the boundary between adjacent fields has on the scale line. 2: Boundary, 7: Main scale scale line, 8: Main scale scale line,
9: Vernier scale line, 10: Vernier scale line.

Claims (1)

[Claims] 1 Along the boundary between two exposure areas that are exposed next to each other, expose the main scale scale line on one exposure area side and expose the vernier scale line on the other exposure area side, and In the method of measuring the connection accuracy of the two exposure areas by observing an enlarged image of the scale lines, two pairs of the main scale scale line and the vernier scale scale line are exposed, and the scale of the first pair of the scale lines is exposed. Exposure is performed so that the direction of the lines is perpendicular to the direction of the second pair of graduation lines and 45° to the boundary, and the first and second pairs of graduation lines are observed to determine the A method for measuring connection accuracy in electron beam exposure, characterized in that connection accuracy is measured in a direction parallel to a boundary and in a direction perpendicular to a boundary.