JPH0249338A - Diaphragm for charged particle beam - Google Patents

Abstract

PURPOSE:To obtain a diaphragm sized to a micron or less order by forming a desired hole on a substrate using a drilling technique used in the manufacture process of a semiconductor and applying a metallic coat to both surfaces of the substrate. CONSTITUTION:An insulation film comprising an SiO2 films 3 and 5, and an Si3N4 films 2 and 4 is formed on the surface of a silicon substrate to a thickness of a sub-micron order. Then, a resist is coated to one of the surfaces and a desired hole 6 is patterned thereon. The aforesaid surface is etched to obtain such depth as penetrating the film 3, using a dry etching process and the resist is thereby removed. Thereafter, a sufficiently large region 7 near the position of the hole 6 is applied with the etching process from the rear side of the substrate and the films 4 and 5 are thereby removed. Thereafter, silicon is selectively etched only from the rear side with a KOH solution and the substrate is immersed in a hydrofluoric acid solution when the thickness of the remaining silicon film 9 becomes about 10mum. As a result, the diaphragm hole 6 is made through while the film 9 having a thickness of a micron order remains. Thereafter both surfaces of the substrate are coated with a metal 8 such as gold and platinum and the diaphragm of a micron order size can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a charged particle beam applied device, and particularly [Prior Art] Charged particle beam applied devices generally used as described above. With current technology, it is impossible to drill holes smaller than a few μm in materials such as (see Figure 5 of the drawings of this application), which are made by drilling holes in high-melting point metals such as molybdenum and platinum. Have difficulty. The reason behind this lies in the current method of manufacturing iris. That is, the hole is made by directly etching the metal using a mask patterned to a desired size. In this case, in order to accurately drill a hole diameter on the order of μm, it is necessary to use a metal that is equal to or thinner than the hole diameter. However, it is difficult to reduce the thickness of the metal currently used as the aperture to 10 μm or less.

Therefore, at present, there is a demand for limiting the charged particle beam by using holes smaller than a few micrometers, with holes on the order of micrometers or less, and exceeding τ. For this reason, it has become difficult to deal with this problem using conventional technology.

[Problem to be solved by the invention]

An object of the present invention is to provide a diaphragm having holes of several μm or less, particularly on the μm order or less.

[Means for Solving the Problems] In order to solve the above problems, instead of directly drilling holes in metal, which has been conventionally used, a Si substrate drilling technique used in a semiconductor process is used. That is,
Using current semiconductor process technology, it is possible to form slots in a Si substrate with a depth on the μm order and a diameter of up to about 0.1 μm.

The present invention utilizes this technique.

[Effect]

First, a thin film of a different material is formed on a Si substrate, and a desired hole is drilled in this thin film using a drilling technique used in a semiconductor process. Thereafter, by removing the Si substrate near this hole, it can be used as an aperture.

It is extremely easy to form a film on the order of μm or less.
Since patterning up to about 1 .mu.m can be performed without any problem with the current technology, apertures down to the sub-.mu.m order can be easily manufactured.

The present invention has been made based on such an effect.

〔Example〕

An embodiment of the present invention will be described below. FIG. 1 is a sectional view of one embodiment, and FIG. 2 is a view from the back side of FIG. 1 (without metal coating). This aperture was manufactured by the following process. (1) First, insulating films are formed on both sides of a Si substrate 1 having a thickness of 0.5 am to a submicron order. The insulating film is an oxide film with a thickness of 0.12 pm (
SiOz) 3°5 and 0.35 μm thick nitride film (S
Formed with two layers of iaNa)2°4. (2) This one side (
When resist is applied to the front surface) and the batt is removed to the desired size, an insulating film (nitride film 2 and oxide film 3) with holes is formed on the Si substrate. Regarding the insulating film (nitride film 4 and oxide film 5), the insulating film is removed by etching in the vicinity of the position of this 66 in a sufficiently large area 7 in the same manner. (4) The surface of the Si substrate 1 thus patterned is protected with acid-resistant wax or acid-resistant tape. Thereafter, it is immersed in a sodium hydroxide (KOH) solution that can selectively etch only Si, and etching is performed only from the back surface of the Si substrate 1.

When the remaining S1 film 9 on the etched Si substrate 1 reaches about 10 μm, the wax or acid-resistant tape is removed and the substrate is immersed in a fluorine-nitric acid (HF/HN◯8) solution. At this time, the Si substrate 1 is isotropically etched not only from the back surface but also from the aperture hole 6 on the front surface, so that the aperture hole 6 passes through with the residual Si film 9 remaining on the order of microns. When etching is stopped in this state, an insulating film with a submicron thickness and a desired hole size in which the RrHJ is supported by the remaining Si film 9 on the order of microns is formed. As can be seen in Figure 1, the Si substrate remains as it is around the hole, so there is no problem in handling it. (5) After this, metal 8 such as gold or platinum is coated from one both sides. This is to prevent the insulating film from being charged up since it is used as a diaphragm for the charged particle beam. By the above method, 0
．． To form an insulating film consisting of a minimum hole diameter of 0.1 μm, a nitride film with a thickness of 0.12 μm, and an oxide film with a thickness of 0.35 μm, supported by a Si remaining film with a thickness of 4 μm, on a Si substrate with a thickness of 5 cm. was completed.

Of course, this is just an example, and the diameter of the holes, the number of holes, the thickness and quality of the insulating film, etc. are not limited to these. for example,
As for the shape of the hole, it is also possible to use a special pattern such as a rectangular shape used in a shaped beam diaphragm of an electron beam drawing device or a part of an IC pattern instead of a circular shape. There may be a plurality of 2M1 types of these.

Further, instead of 5iaNa/5iOz (7), a negative layer of 5iaN4 or PSG, or a semiconductor such as P-type or N-type Si doped with P or B may be used. That is, any material that can be selectively etched with Si may be used. For example, if B is doped at about 10"/CM8 or more, the etching rate with Si will be about 1/1000, and selective etching with Si will be possible.Also, a film with a sandwich structure of these may be used. For example, SiO2, Si sNa, S i
Assuming a three-layer structure of Oz, the expansion of 5iOz and 5isN
This balances h with shrinkage, reduces stress during etching, and easily prevents damage to the film.

As for etching, it goes without saying that either dry or wet etching can be used. In short, any material that can be selectively etched with Si may be used.

For example, for Si etching, use sodium hydroxide in addition to potassium hydroxide solution.

Any solution such as lithium hydroxide, ammonium hydroxide or fluoronitric acid, hydrofluoric acid or ammonium fluoride may be used for 51 g Na and 5 iOz.

Further, in this embodiment, a Si substrate is described as a representative example, but a compound semiconductor such as GaAs or InP may also be used.

Moreover, the above manufacturing method is also an example, and is not limited to this. For example, when removing a large area of the insulating films 4 and 5 on the back surface, it may be mechanically scraped together with the Si substrate to the vicinity of the insulating film on the front surface, or it may be scraped using ultrasonic waves, and the remaining Si portion may be removed by etching. .

FIG. 3 is a sectional view of another embodiment, in which the same parts as in FIG. 1 are given the same reference numerals. FIG. 4 is a view from the back side of FIG. 3 (before metal coating).

The manufacturing procedure of this aperture is the process (4) of the first embodiment.
The only difference is as follows. That is, the Si substrate 1 is immersed in an etching solution that can selectively etch only Si.
Etching is performed until the remaining Si film 9 shown in the figure disappears. As a result, a submicron-thick nitride film 2 with the desired hole size was obtained.
．． Only the insulating film layer consisting of the oxide film 3 is formed.

In the above embodiments, the part used for the aperture is made of an insulating film and coated with metal to prevent charge-up, but the invention is not limited to this. For example, instead of the insulating film, a metal such as W, Au, or Pt may be coated and manufactured using the same procedure. In this case, a metal coating to prevent charge-up is unnecessary. Generally, when wet etching metals, selectivity with Si is not very good. Therefore, an insulating film such as 5iC)z or 5iaNt is formed between the metal film used as the aperture and the substrate, and this protects the metal film when etching from the back side, and the front side is coated with wax or resist. Cover, protect and etch. After the desired film is formed, the wax or resist is melted to create the desired aperture. Of course, the protective film such as SiO2 or 5isNa may be removed after this. This method can be used not only for the production of metal films but also for the production of films with poor selectivity in general.

Furthermore, in the above embodiments, we have described an aperture with a structure in which the substrate remains, but for example, the desired aperture can also be created by removing the entire substrate, leaving only a thin film, and gluing this onto something like a mesh. .

〔Effect of the invention〕

As described above, according to the present invention, it is possible to form a sufficiently smaller aperture diameter than the aperture diameter made of metal. In other words, the precision of the aperture edge is better than that of the conventional method. That is, even if this aperture pattern is used in a charged particle beam optical system that projects or transfers the aperture pattern, it is possible to provide an extremely accurate aperture. In addition, since these films can be made extremely thin, self-heating occurs when used as a diaphragm for charged particle beams, resulting in the effect of preventing contamination of the diaphragm.

[Brief explanation of the drawing]

FIG. 1 is a basic sectional view of a diaphragm showing one embodiment of the present invention. Figure 2 is a view from the back of Figure 1 (before metal coating). FIG. 3 is a basic sectional view of an aperture showing another embodiment of the present invention. Figure 4 is a view from the back of Figure 3 (before metal coating). FIG. 5 is a basic configuration diagram of the conventional system. 1... Si substrate, 2... Nitride film, 3... Oxide film,
4...Nitride film, 5...Oxide film, 6...Aperture hole,
7... Hole for Si substrate etching, 8... Metal coating film, 9... Si remaining film, 10... Metal plate aperture.

Claims (1)

[Claims] 1. An aperture for a charged particle beam, characterized in that a thin film having a hole smaller than the hole is formed on a substrate having a hole. 2. The charged particle beam aperture according to item 1, wherein the hole in the substrate has a cross-sectional structure of two or more stages. 3. The aperture for charged particle beams according to either of item 1 or item 2, wherein the substrate is a semiconductor such as Si or GaAs. 4. Items 1 to 4, wherein the thin film is an insulating film such as SiO_2, Si_3N_4, PSG, or an insulating film having a structure in which two or more layers of these are stacked, and these are coated with metal. The charged particle beam aperture according to any one of Item 3. 5. Items 1 to 3, wherein the thin film is a semiconductor such as P-type or N-type Si doped with P or B, or has a structure in which the semiconductor is coated with a metal. The charged particle beam aperture according to any one of the above. 6. The charged particle beam aperture according to any one of items 1 to 3, wherein the thin film is made of metal. 7. The charged particle beam aperture according to any one of items 1 to 6, wherein the small hole is arranged in the path of the charged particle beam emitted from the charged particle beam source. 8. A charged particle beam device equipped with the charged particle beam aperture according to any one of items 1 to 7.