JPS60226121A - Electron beam drawing apparatus - Google Patents

Abstract

PURPOSE:To remarkably reduce over-hanging and easily realize high speed, highly accurate electron beam drawing apparatus by providing extruded over-hang preventing wall formed with a material having small rear scattering coefficient at the external circumference of semiconductor detection holder faced toward a sample. CONSTITUTION:An electron beam 1' entering the point Q on a sample 4 coated with resist generates reflected electron. A holder 11 is formed with a non-magnetic and conductive material such as carbon, Be, Al having small rear scattering coefficient and secondary electron emission coefficiency and moreover a circular or polygonal flat preventing wall A is formed at the lower end part facing to a sample 4 of holder 11. The preventing wall A has adequate thickness and is provided with electron beam passing hole c and four exposition holes 4 of detector 7. Moreover, the lowest end part thereof is formed in such nearer area as is not in contact with the sample 4 and a substance loaded on the movable stage. When the holder 11 thus formed is used, the reflected electron generated in the vicinity of the entering point Q of the electron beam 1' does not almost generate electrons when it collides with the part except for the semiconductor detector 7 (in total of four detectors).

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electron beam lithography device that controls an electron beam to form a fine pattern such as an LSI on a sample surface, and particularly relates to an electron beam lithography device that controls an electron beam to form a fine pattern such as an LSI on a sample surface. A surface-opening device suitable for forming highly accurate drawn figures by preventing fogging [Background of the Invention] The conventional problems will be explained with reference to FIGS. 1 and 2. First, in FIG. 1(a), an electron beam 1 is emitted from an electron gun and reduced to a predetermined size by an irradiation lens, a focusing lens, etc. (not shown), and an electron beam resist is formed by an objective lens 2. The focus is adjusted on the coated sample 4, and deflection scanning is performed by the deflector 3 so as to draw a fine figure at a desired position. Further, the semiconductor detector 5 is used for backscattered electron beam observation on the sample 4 and position detection work using marks.

What has conventionally been a problem here is the behavior of the reflected electrons R shown in FIG. 1(b). In the same figure, actual sample 4
In addition to the flat part, there is an undulating part 6 on the top corresponding to the LSI wiring, so the scattering angle θ of the reflected electrons R with respect to the incident electron beam 1' is generally larger in the vicinity of the etch of the undulating part 6 than in the flat part. big.

FIG. 2 explains the behavior of the reflected electrons in more detail. FIG. 2(a) shows a holder 9 for the semiconductor detector 7.
(Due to axial symmetry, only one side is shown). In the figure, C is a hole through which the electron 4@i' passes, and 7a to 7c are exposed holes of the detector 7 used for detecting the position of a mark. On the other hand, FIG. 9B shows a cross-sectional structure of the holder 9 taken along the line xx' in the plan view. In FIG. 2(b), the electron beam 1' incident on point P on sample 4 coated with electron beam resist is
Reflected electrons such as secondary electrons and backscattered electrons as described above are generated (to make the diagram complicated, only the left half of the scattering state is shown). Here, a semiconductor detector 7 and a holder 9 , which are usually installed facing the sample 4 , are used. The lower surface 10 of the lens is made of Si.
Materials with relatively large scattering coefficients are often used, such as copper or bronze.

However, when the scattered electrons generated at point P collide with the above-mentioned parts, they are scattered again toward the sample 4 side coated with resist, causing unintended overexposure, or so-called fogging. The scattered electrons R1 in the figure are repeated multiple times as shown, and promote fogging in a wide range of side directions. Further, in addition to the Si sample coated with resist, fogging becomes even more severe on standard marks made of Au used for correcting deflection distortion of electron beams, for example. Therefore, the amount of scattered electrons R1 is larger when irradiated on the standard mark than on the St wafer. In the authors' experiments, the range of such fogging was determined by the range of P in Fig. 2(b).
The radius around the point reached several tens of milliseconds. The negative effects caused by this fogging are typified by a decrease in the accuracy of drawn figures and a severe film thinning phenomenon in high-sensitivity resists.

In order to prevent fogging, the authors have conventionally used the method shown in Figure 2 (
Although we tried changing only the holder 9 in b) to a material with a low electron scattering coefficient, it was still not a perfect countermeasure against scattered electrons in the side direction. On the other hand, a method (Japanese Patent Application Laid-Open No. 48-90680) has been devised in which a material with a low scattering coefficient is coated on the entire inner wall of a large-area sample chamber (not shown) facing the sample 4, but it is difficult to process.

There were some difficulties in terms of economy.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to significantly reduce fog and facilitate the realization of a high-speed, high-precision electron beam lithography system.

[Summary of the invention]

The present invention provides a fog prevention wall protruding from the outer periphery of the semiconductor detector holder facing the sample side (so-called skirt shape), and the new holder is made of a material with a small backscattering coefficient.

[Embodiments of the invention]

FIG. 3 is a schematic diagram showing an embodiment of the present invention, and the illustration method is similar to that of FIG. 2(b).

In FIG. 3, the drawing electron beam 1' incident on point Q on the sample 4 coated with resist generates reflected electrons similar to those described above. However, the holder 11 in this embodiment is made of a material such as carbon, Be, or AM that is non-magnetic, has good conductivity, and has a small backscattering coefficient and secondary electron emission efficiency. A prevention wall having a circular or polygonal planar shape as indicated by A in the figure is formed at the lower end. (That is, the holder 11 has a skirt shape). The prevention wall A has an appropriate thickness, and is provided with a hole C through which the electron beam 1' passes and four exposure holes for the detector 7. Further, the lowermost end is formed so close as not to come into contact with the sample 4 or the object mounted on the moving stage.

When using the holder 11 processed in this way, the electron beam 1'
The reflected electrons generated near the incident point Q are detected by the semiconductor detector 7.
When it collides with sites other than (4 in total), almost no electrons are scattered. In particular, since the above-mentioned prevention wall A of the holder 11 effectively blocks multiple scattering in the lateral direction near the incident point Q, fogging on the resist applied to the sample 4 can be drastically reduced. Therefore, the spread of scattered electrons R2 according to the present invention can be suppressed to a very small amount compared to Rt of the conventional example shown in FIG. 2(b).

[Effects of the Invention] According to the present invention, fogging is significantly reduced, and as a result, (1) the precision of drawn figures is improved, and submicron figures can be drawn even more easily. 2. 3. High-sensitivity resist can be used, which helps speed up the writing device. There is no need to coat a substance with a small backscattering coefficient on the large-area inner wall of the sample chamber facing the sample surface, and it is possible to obtain great effects such as 2, which are highly technically and economically effective.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an electron beam lithography system and a diagram showing the scattering state of electrons, Fig. 2 is a detailed sectional view of the vicinity of the electron beam enclosure, and Fig. 3 is a line lithography system according to an embodiment of the present invention. FIG. 1.1'...Electron beam, 4...Sample, 5,7...Semiconductor detector, 9.11...Semiconductor detector holder, 10
... Lens bottom surface, 7a to 7c... Exposure hole for semiconductor detector, P, Q... Electron beam incidence part, R, Ri, R2.
...Scattered electrons, A...Anti-scattering wall. Agent Patent Attorney Akira Takahashi ■ 1 Figure ((L) (b) 3 East 2 Figure (υ (I)) Figure 3

Claims (1)

[Claims] 1. In an electron beam lithography device that focuses and deflects an electron beam onto a sample to form a desired pattern, a skirt-like structure is provided in a region facing the sample surface near the electron beam enclosure. A scattering prevention wall is provided, and the prevention wall is non-magnetic. An electron beam lithography device characterized in that it is made of a material with good conductivity and a small backscattering coefficient. 2. The electron beam lithography apparatus according to item 1, wherein the prevention wall is integrated with the scattered electron detector holder.