JPS6351641A - Fine pattern formation of single crystal or polycrystalline si film - Google Patents

Abstract

PURPOSE:To enable a fine pattern of single crystal or polycrystalline Si with high precision to be formed easily in simplified processes by a method wherein an etching mask comprising an oxide Si film is directly formed on the surface of single crystal or polycrystalline Si film by means of irradiating said surface with oxygen ion beams. CONSTITUTION:A polycrystalline Si film 23 is formed on an oxide Si film 22 on an Si substrate 21. A natural oxide film layer 24 is produced on the surface of polycrystalline Si film 23. Thus, the natural oxide film 24 is removed by fluoric acid. Next, the non-etched region of polycrystalline film 23 is irradiated with oxygen ion beams 25 to implant the surface with oxygen ion. Thus, another Si film 26 is formed on the surface of non-etched region of polycrystalline film 23. Next, the polycrystalline Si film 23 is laser-etched using the oxide Si film 26 as a mask. Thus, the polycrystalline Si film 23 is left only below the oxide Si film 26 so that a fine pattern of polycrystalline Si film 23 may be formed. Later, the oxide Si film 26 is removed. Likewise, a fine pattern of single crystal Si film can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming single crystal or polycrystalline SiM into minute turns by laser assisted etching.

(Prior Art) Polycrystalline Si has conventionally been widely used as a f-to electrode material in large-scale semiconductor integrated circuits (hereinafter abbreviated as VLSI). Furthermore, as a method for etching polycrystalline Si, a laser-assisted etching method that causes less damage to polycrystalline Si has recently been adopted.

FIG. 2 is a schematic diagram showing an example of the configuration of a conventional laser-assisted etching device that implements the laser-assisted etching device. ) Conference on Solid State Devices and 6 Materials, Code (Exten
Abstracts of the 16th
(1984International) Conf.
erence on3o1id 5tate Devi
ces and Materials, Kobe
).

1984, PP, 441-446 K.

Referring to Figure 2, l is in the reaction chamber, C7, gas (10
~100 torr) is introduced. In addition, the reaction chamber 1
The object to be etched 3, for example, polycrystalline Sl, is placed on the holder 2 inside
and single crystal Si are retained. Also, as an excimer laser, XeC1! (308 nm), and its excimer laser beam 4 is introduced into the reaction chamber 1 through the quartz window 5 and irradiated onto the object 3 to be etched. Then, Cl and other gases are photodissociated on the surface of the object 3 to be etched, and the object 3 to be etched is excited by the light.
, the etching reaction proceeds.

FIG. 3 is a process sectional view showing a conventional method of forming a fine pattern of a polycrystalline Si film using the above-mentioned laser assisted etching method in VLSI. In this conventional method, a polycrystalline 81 film 13 is formed on an oxidized Si film 12 on the surface of a Si substrate 11, and then a resist soturn 14 is formed on the polycrystalline Sl film 13 in a desired shape using ordinary photolithography. (Fig. 3(a)). Thereafter, using this resist pattern 14 as a mask, the polycrystalline Si film 13 is laser-assisted etched using the laser-assisted etching apparatus shown in FIG. A crystalline Si film 13 is obtained.

In FIG. 3(a), reference numeral 15 indicates excimer laser light irradiated onto the polycrystalline Sl film 13 during laser-assisted etching.

(Problems to be Solved by the Invention) However, in the conventional fine pattern forming method as described above, the resist pattern 14 is used as an etching mask, so that the resist coating and exposure are difficult.

Not only does this require complicated processes such as processing, baking, and resist removal, but the processing accuracy of the polycrystalline Si film 13 also depends on the resolution of the retasteless nine-turn 14, so there is a limit in terms of microfabrication.

The present invention eliminates the above-mentioned problems in process and processing accuracy, and produces ready-to-crystalline or polycrystalline Si using a laser-assisted etching method with a simple process and excellent processing fFfi.
An object of the present invention is to provide a method for forming fine setanes in a single crystal or polycrystalline Si film, which can form fine notterns in the film.

(Means for Solving the Problems) In the present invention, an oxygen ion beam is irradiated to the non-etched region of a single crystal or polycrystalline Si film to form a Si oxide film on the surface of the Frfl region. Using the Si oxide film as a mask, a single crystal or polycrystalline Si film is subjected to laser assisted etching to form a fine nosetan.

(Operation) When a single crystal or polycrystalline Si film is irradiated with an oxygen ion beam and ν ions are implanted, the implanted oxygen ions react with the single crystal or polycrystalline Si and change into oxidized SiK.

That is, oxidized si#A is formed.

When this Si oxide film is on the surface, when a single crystal or polycrystalline Si film is subjected to laser assisted etching, the etching reaction does not proceed at all in that part, and the Si oxide film acts as an etching mask. According to the method of the present invention, an etching mask is formed directly on the surface of a single-crystalline or polycrystalline Si film by irradiation with an oxygen ion beam, and using the etching mask as a mask, the single-crystalline or polycrystalline silicon is etched finely by laser-assisted etching.・Able to form patterns.

(Example) A one-person embodiment of the present invention will be described below with reference to FIG.

FIG. 1(a) shows a state in which a polycrystalline Si film 23 is formed on an oxidized Si film 22 on the surface of a Si substrate 21, and 24 indicates a natural oxide film 1- present on the surface of the polycrystalline Si film 23. It is. If this natural oxide film layer 24 exists, the etching reaction will not proceed at all even if laser assisted etching is performed.

Therefore, first, as shown in FIG. 1(b), the natural oxide film layer 24 is removed using hydrofluoric acid.

Next, as shown in FIG. 1(c), the oxygen ion beam 2
5' A non-etched region of the t-polycrystalline Si film 23 is also irradiated, and oxygen ions are implanted into the surface of the region. Then, the implanted oxygen ions react with polycrystalline Si to form oxidized 5t (S).
As a result, as shown in FIG. 1(c), an oxidized Si film 26 is formed on the surface of the non-etched region of the polycrystalline Si film 23.

Next, using the oxidized Sl film 26 as a mask, polycrystalline S is etched using the laser assisted etching apparatus shown in FIG.
The i-film 23 is laser assisted etched. The state at this time is shown as 7' in FIG. 1(d), and 27 in the figure is an air laser beam irradiated onto the polycrystalline Si film 23.

When this laser-assisted etching is performed, the polycrystalline Si pattern 23 remains only under the Si oxide film 26, as shown in FIG. 1(c). As a result, a fine pattern of the polycrystalline Si film 23 is formed. After that, the Si oxide film 26 is removed.

Note that although the above embodiment is a case of forming fine flat turns of a polycrystalline Si film, it is also possible to form fine flat turns of a single crystal Si film in the same manner.

(Effects of the Invention) As described above in detail, according to the fine pattern forming method of the present invention, an etching mask made of a Si oxide film is directly applied to the surface of a single crystal or polycrystalline Si film by irradiation with an oxygen ion beam. Since the etching mask is formed in this manner, the process can be simplified compared to the case where an etching mask made of a resist pattern is used. In addition, since a fine, highly accurate Si oxide film can be formed by narrowing the oxygen ion beam to a small extent using a TA lens, a highly accurate fine pattern of single crystal or polycrystalline Si can be easily formed.

[Brief explanation of the drawing]

Figure 1 shows the single crystal or fcld polyFA & Si of this invention.
FIG. 2 is a schematic diagram showing an example of the configuration of a laser-assisted etching device. FIG.
FIG. 3 is a process cross-sectional view showing a turn forming method. 21...81 substrate, 23...polycrystalline Si film, 25...
...Oxygen ion beam, 26...Si oxide film, 27.
...eximale light. Fig. 2

Claims (1)

[Scope of Claims] (a) A step of forming a single-crystalline or polycrystalline Si film on a substrate; (b) A step of irradiating an oxygen ion beam to a non-etched region of the single-crystalline or polycrystalline Si film to a step of forming an oxidized Si film on the surface of the region, and (c) a step of laser-assisted etching the single crystal or polycrystalline Si film using the oxidized Si film as a mask to form a fine pattern of the single crystal or polycrystalline Si film. A method for forming a fine pattern on a single crystal or polycrystalline Si film, comprising: