JPS61296720A - Manufacture of charged-beam forming mask - Google Patents

Abstract

PURPOSE:To manufacture a mask in a short time by a method wherein the mask is composed of a thin mask layer and the thick mask layer and a high accuracy can be obtained by the thin mask layer and mechanical and thermal stability can be obtained by the thick mask layer. CONSTITUTION:The thickness of a thin layer 1 which intercepts a beam is sufficient if it is much thicker than that of the range (the maximum transmitting distance) of the beam for exposure and if the layer 1 is thinner, holes can be drilled more accurately at the parts such as curved parts of the pattern corners. For instance, when an electron beam of 50keV is used, if platinum is employed as the material, thickness of 1mum is thick enough. A layer 2 supports the layer 1 mechanically and transmits the heat generated in the layer 1 to the atmosphere efficiently. The requirements for the material of the layer 2 is such that a thermal expansion coefficient is close to that of the layer 1, thermal conductivity is high and an etchant which can etch the layer 2 by utilizing the layer 1 as a mask is available. From the requirements, Cu is selected as the material of the layer 2 and the thickness is about 20-200mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a mask for shaping a charged beam, particularly a pattern 1 of a complex shape such as a memory cell pattern.

[Technical background of the invention and its problems]

When the pattern size is in the submicron or macroscopic range of 0.5 μm or less, optical exposure cannot be used, so the pattern must be formed by direct exposure using a charged beam such as an electron beam or ion beam. In this case, the throughput is extremely low, so when drawing a pattern with many repetitions, such as a memory cell, the shape and dimensions of the memory cell can be shaped into a double beam, and exposure can be performed using that beam to significantly (=improve) the throughput.

However, there has been no conventional method for manufacturing such a complex and highly accurate 1:beam shaping mask in a short period of time and at low cost. Furthermore, such a mask is mechanically weak and suffers from thermal deformation or melting when exposed to a charged beam.

An electron beam diaphragm has been considered that has a silicon thin film with different impurity contents on the surface of a silicon substrate, shapes the beam with this thin film, and provides a hole that reaches this thin film from the back of the substrate, but there is a better manufacturing method. In this case, it is necessary to align the mask from the back side, a special exposure device is required, and the number of steps increases, so it is inexpensive (2-4 cells). If you want to create a mask for a memory cell and use that mask to draw repetitive parts at high speed (secondly, if the lot is different or the layer is different, you need to replace the beam shaping mask each time, so you need to easily make it. It had to be both affordable and affordable.

[Purpose of the invention]

The object of the present invention is to provide a mask structure for beam shaping that does not have the above-mentioned drawbacks and a method for manufacturing the mask in a short time and at low cost.

[Summary of the invention]

The gist of the present invention is to provide a structure in which high precision is achieved with a thin mask layer, and mechanical and thermal stability is achieved with a thick mask layer.

[Effects of the Invention] With such a structure and manufacturing method, it has become possible to mask a memory cell pattern, and the throughput of a charged beam exposure apparatus has been improved by 5 to 10 times. Masks can be produced in a short time (secondary, the turnaround time for exposure is shortened).

[Embodiments of the invention]

FIG. 1 shows the structure of a mask according to an embodiment of the present invention. The same figure (a) is a plan view, and the same figure (b) is AA' of (a).
FIG. 1 is actually a thin layer that cuts the double beam quickly, and the thickness of this layer should be sufficiently thicker than the range (maximum transmission distance) of the beam used for exposure. Here, when using an electron beam of 5 QKe V, a thickness of IIfn is sufficient if platinum is used. 2 mechanically supports layer 1 and efficiently transfers the heat generated in 1 to the outside. This is a layer for

Cu was selected as a material that has a small difference in thermal expansion coefficient from layer 1, has good thermal conductivity, and has an etchant that etches layer 2 using layer 1 as a mask.

The thickness was about 20-2007a.

In the figure, 3 indicates a hole formed in a thin layer, and 4 indicates a hole formed in a thick layer.

[Other embodiments of the invention]

The structure shown in Fig. 1 can be easily handled by fixing a larger workpiece (2). When using an ion beam, it is preferable that layer 1 be made of a material that is difficult to adhere to the ions used. As the bonding method of 1, it is also possible to bond them together and vapor-deposit 1 on this surface.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an embodiment of a method for manufacturing a beam shaping mask according to the present invention. 1... Thin layer 2... Thick layer 3... Hole 4 formed in the thin layer... Hole in the thick layer formed by isotropic etching using 3 as a mask (7317) "Patent Attorney Rules" Kensuke Chika (1 other person)
Figure 1

Claims (2)

[Claims] (1) Formed of at least two layers of different materials with different thicknesses,
In a charged beam forming mask, a hole of the desired shape and size to form a beam is formed in the thin layer material, and a hole larger than the hole and completely encompassing the hole is formed in the thick layer material. A method for producing a charged beam forming mask, which comprises forming a layer by etching, and using the hole as a mask, forming a thicker layer by etching. (2) A method for manufacturing a charged beam shaping mask according to claim 1, which comprises shaping a beam having a complicated shape such as a memory cell.