Radiant energy – Irradiation of objects or material – Irradiation of semiconductor devices
Patent
1990-11-26
1994-08-02
Berman, Jack I.
Radiant energy
Irradiation of objects or material
Irradiation of semiconductor devices
H01L 21027
Patent
active
053348451
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to high-throughput charged beam exposure method and charged beam exposure apparatus using a collective exposure beam in charged beam exposure methods.
BACKGROUND ART
A conventional technique will be described with reference to FIG. 4 by taking a case of exposing a pattern 20 shown in FIG. 2 as an example.
In a variable shaping method standing for the conventional technique, the shape of a charged beam is of only rectangle and therefore, as shown in FIG. 4, exposure has to be carried out by making a division in compliance with a pattern form. Accordingly, for a pattern having a number of inclined lines and a pattern having complexity, the number of shots is correspondingly increased and as a result the throughput is decreased. Especially, the number of exposure shots increases drastically for exposure of a highly integrated electronic memory device or the like having a large number of patterns and hence it takes a long time for exposure.
The aforementioned conventional technique fails to fully take into consideration a high speed processing of exposure of the highly integrated electronic memory device and the like having periodical repetition and a large number of patterns. To solve this problem, an exposure method shown in JP-A-59-169131 is available. According to this idea, the charged beam shapes are prepared including, in addition to the rectangle, shapes forming one element portion of pattern such as a pattern 23 and a pattern 24 which are shown in FIG. 3. However, the conventional aperture material is a metallic material having bad workability and practically speaking, the aperture can not be formed with a complicated shape, for example, comparable to a 64-mega bit dynamic random access memory (hereinafter abbreviated as Mb DRAM). Further, in the above example, only portions of a pattern such as a single inclined line or single polygonal line are exposed collectively but the form inclusive of even an array of pattern is not taken into account. Therefore, making a pattern division is still required and a drastic decrease in shot number can not be achieved. In addition, when shot density per unit area is increased concomitantly with high integration, the total shot number is correspondingly increased.
SUMMARY OF THE INVENTION
The above object can be accomplished by collectively handling all patterns within a constant area without making any pattern division and exposing them by one shot. To this end, even pattern forms and an array thereof contained in a constant area are taken into account and they are all built in an aperture.
As a material of the aperture built in with such a complicated pattern as above, a semiconductor single crystal, especially, silicon single crystal may be used.
An object of the invention is to provide an exposure method and an exposure apparatus which can handle even an element having such a large number of patterns as above at a high throughput and can maintain the high throughput regardless of shot density per unit area.
Another object of the invention to provide an exposure method and an exposure apparatus which can ensure high process speeds regardless of whether the pattern is complicated or not.
Another object of the invention is to provide an aperture step which can be used for the exposure method and exposure apparatus and a method for production of the aperture step.
Other objects of the invention will become apparent by reading the specification in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1(a) is a schematic diagram of an exposure apparatus of the invention,
FIG. 1(b) is a plan view showing a typical example of an aperture for 64 Mb DRAM,
FIGS. 2 and 5 are diagrams showing a gate layer pattern of 64 Mb DRAM pattern,
FIG. 3 is a diagram for explaining aperture pattern of the conventional scheme,
FIG. 4 is a diagram for explaining pattern division according to the conventional variable shaping scheme,
FIG. 6 is a diagram showing a contact layer pattern of 64 Mb DRAM pattern,
FIG. 7 is a diagra
REFERENCES:
PCT International Search Report dated Jun. 25, 1990; by Japanese Patent Office (ISA/JP).
Murai Fumio
Nakayama Yoshinori
Okazaki Shinji
Wakabayashi Hiroaki
Berman Jack I.
Hitachi Limited
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