JPS59103333A - Electron beam exposing method - Google Patents

Abstract

PURPOSE:To eliminate relative deviation of mask from the stage by providing an alignment mark which is usually provided to the stage to the mask itself and obtaining the mark position data through detection of electrons reflected from said alignment mark when delineating mask with electron beam. CONSTITUTION:A substrate 3 is formed by vacuum-depositing a chromium film 2 on a low expansion glass 1 and a positive resist film 4 is applied on the film 2. The substrate 3 is loaded to a cassette and is fixed on the stage in the chamber. The inside of chamber is highly vacuumed and a cross pattern 6 for positioning is formed at the edge of film 4 by the scanning with electron beam 5. Thereafter, the pattern 6 is developed and is removed and a molybdenum film 7 is deposited on the entire part by the electron beam vacuum deposition method. The resist film 4 is lifted off together with the film 7 deposited thereon and thereby positioning mark 8 is cross pattern formed by protruded film 7 can be obtained. As a result, quality of mask can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Field of Application in Mining Field of the Invention The present invention relates to electron beam N optical properties which are frequently used for pattern formation of various semiconductor devices such as integrated circuits.

B. Prior Art In the electron beam light method, in order to form a pattern on a mask, the surface of the mask is covered with a resist, and an electron beam is scanned to expose the casing area.

The exposure is carried out in accordance with the support from a computer that has been given data in advance.

Conventionally, the position of the pattern data is determined by scanning a grid provided on the stage with an electron beam, and using the position of the grid as a reference point, the position of the stage is corrected by rescanning during writing. Ta. In this case, since the mask is attached to a cassette fixed on the stage, there is a possibility that the cassette and mask may be misaligned when the stage is scanned.

Misalignment caused by expansion and contraction of the cassette due to the temperature difference between the room temperature and the inside of the drawing chamber had a direct impact on pattern accuracy. Furthermore, in order to avoid the influence of expansion and contraction of the cassette due to the temperature difference, waiting one hour until the warm equilibrium state is reached has been a cause of deterioration of the drawing ability of the electron beam exposure apparatus.

Purpose of the Invention The present invention has been made in view of these problems, and it corrects the relative deviation of the two masks from the stage, and at the same time eliminates the influence of the relaxation time of the cassette, thereby improving the electron beam The purpose is to improve the capabilities of exposure equipment and ultimately improve the quality of masks.

D) Structure of the invention The present invention applies to mask writing using an electron beam.

The unique feature is that the alignment mark, which was conventionally provided on the stage, is provided on the mask body, and this mark is scanned and irradiated with an electron beam, and the position information of the mark is obtained by detecting the reflected electrons from the mark. have

Example 4 Chromium [121
A positive resist FBM-120 is applied to the substrate (3) on which
Apply (4) (Figure 1). Next, after mounting it on a cassette, it was fixed on a stage in a chamber with a vacuum degree of 7xiQ Torr, and an electron beam (5) was scanned with an acceleration voltage of 10KV, 4QMHz, a beam diameter of 0.5JJII+, and an exposure of t5X10-7C/-2. An alignment cross pattern (6) as shown in FIGS. 10 and 11 is drawn on the edge of the substrate +31 (second factor). After developing this pattern (6), a molybdenum film (7) is deposited on the entire surface of the first plate (31) by electron beam evaporation (Fig. 6).Finally, the resist (4) is removed. ) The molybdenum film (7) deposited on the top is lifted off, leaving the molybdenum film following the cross pattern where the resist f4+ was developed and removed, and forming the alignment mark (8) in the cross pattern in a convex step state. obtained (Figure 4).

The actual pattern is drawn using the alignment mark (8) obtained in this way, and the fifth part shows the mask position correction system at the time of drawing. The mark (8) is scanned with an electron beam from an electron gun Q (If), and the reflected electrons at that time are detected by a reflected electron detection system (111) such as a solar cell, and the coordinates of the center position of the mark (81) are measured. Then, in the subsequent drawing process, coordinates are measured by scanning the alignment mark (8) every 1, for example, every 3 minutes.
The calculation circuit (12
1 is detected and added to the input of double deflection amplifier U. This double deflection amplifier 03 is an amplifier with a double deflection coil (141 km) installed in the scanning system of the electron beam.
By adding an error signal to 31, beam scanning can be made to follow the positional deviation of the mask.

In the conventional alignment method, the deviation of the pattern in the mask from the design value is measured by a light wave interferometric coordinate measuring device.
The average value was 0.3 μm, and the variation was 0.04 μm. There are many causes for this, including factors in the development and etching processes, but the error component in the beam scanning stage of writing has a direct impact on subsequent processes, and removing this component will improve the quality of the mask. It has the meaning of being heavily armored.

As for the effect of the alignment mark of the stepped cross pattern on the mask in this embodiment, according to the light wave interference type coordinate measuring instrument, the positional deviation was improved by about one fraction compared to the conventional method.

F) Example-2 In the previous Example-1, the alignment mark was curved on the curtain plate (31), but in this example, the alignment mark was placed on the low expansion glass. Make a recess at the time of engraving.

That is, a mask (201) from which the cross pattern (6) shown in FIG.
R-800 (4 inch square low expansion material coated with 21+)
The cross pattern 2■ is printed, and as a result of the phenomenon, a cross pattern (6) is drawn on the resist (i7e
N). What to do with this cross pattern (6+) Regis 1-(2
Using 11 as a mask, a glass hanging plate (22) was etched with buffered hydrofluoric acid to form alignment marks (241) with a depth of 5 μm.
(8th layer) Finally, the resist (211) is peeled off and washed, dried, and then a chromium film 4 is evaporated to a thickness of 500.7 mm to form an electron beam with a cross pattern mark (26) recessed. A mask bottom plate for beam exposure is obtained (FIG. 9).From this point on, a pattern is drawn by scanning the alignment mark (g) with an electron beam in the same manner as in Example-1.

According to the measurement method described above, the positional deviation in this example had an average value of 0.08 μm and a variation of 0.01 μm.

As described in detail, according to the electron beam exposure method of the present invention, it is possible to avoid misalignment of the stage and cassette, which has a great effect on improving pattern accuracy.

[Brief explanation of the drawing]

1 to 4 show the manufacturing process of a mask used in the exposure method of the present invention; TFIh plane view 2; FIG. 5 is a block diagram showing a mask position correction system; Cross-sectional diagram 2 10 showing the manufacturing process of another example mask used for
Figure 11 is a front view of the mask substrate and an enlarged front view of the main parts thereof, 1ll (221 is a glass curtain plate,
+21 (251 is the chromium film, (4) (2) J is the resist 6 (6) is the cross pattern, +81 (261 is the alignment mark), respectively. Negative: Sf/ j7 and 1

Claims (1)

[Claims] 1) In the electron beam exposure method in which a reference point for electron beam scanning is determined by detecting the reflected beam obtained by reflecting an electron beam irradiated in a scanning manner at an alignment mark, the above alignment mark is used. An electron beam exposure method characterized by providing a convex or concave step on the mask body.