JPS62265725A - Working apparatus for semiconductor substrate by using focused ion beam - Google Patents

Abstract

PURPOSE:To accelerate a working speed, such as etching in a working apparatus by disposing the radical discharge port of a radical generation tube inserted into a sample treating chamber near the surface of a sample. CONSTITUTION:A radical generation tube 11 composed of a discharge tube or the like is inserted into a sample treating chamber 5, and a radical discharge port 11a at the end of the tube 11 is disposed near the surface of a sample 10. Cl2 molecules are introduced into the tube 11 to generate radical C by discharge in the tube, the generated radical Cl is discharged from the port 11a to be absorbed to the surface of the sample 10. An ion beam drawn from a liquid metal ion source 2 is focused by a focusing lens system 3, further focused ion beam is introduced through a pore 12 formed at a partition wall 6 into the chamber 5 to be emitted to a predetermined position of the sample 10. Thus, the surface of the sample 10 is efficiently worked or etched by the synergistic action of the radical Cl and the emitted ion beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an apparatus for processing a conductive substrate using a focused ion beam.

(Prior art) A focused ion beam device using a liquid total bending ion source is capable of making the irradiation diameter very small. As shown in FIG. 6, the processing apparatus includes a focused ion beam generating section C which has a liquid metal ion source a such as Ga and a focusing lens system inside, and a focused ion beam generating section C which is adjacent to the focused ion beam generating section C and has inside it a liquid metal ion source a such as Ga and a focusing lens system. It consists of a sample processing chamber e having an inner sample chamber d, in which a sample If such as a semiconductor substrate is placed, while the ion beam extracted from the ion source a is focused by a focusing lens system. This focused ion beam is irradiated onto a single point on the sample f through a small hole g formed in the partition wall between the focused ion beam generating section C and the sample processing chamber e, and a small hole formed in the upper wall of the inner sample chamber d. ,
It performs processing such as etching and deposition of semiconductor substrates.

In this case, even if only ion irradiation is used, processing by physical sputtering is possible, or the etching rate is low.

In order to speed up this process, conventionally, reactive gases such as CI2, Si (:I4) containing a! Some processing processes such as etching have been performed on sample f in an atmosphere.

, '1: In this case, the gas pressure in the inner sample chamber d is
- Measurement is carried out through pipe j, and the reactive gas introduced into the inner sample chamber d flows into the sample processing chamber e through a small hole provided in the inner sample chamber d, and then through the exhaust path k. is exhausted to the outside.

(Problem to be solved by the invention) As mentioned above, irradiating the sample with an ion beam in a reactive gas atmosphere to perform processing such as etching the sample is because the surface of the sample f is exposed to chlorine gas, etc. This method attempts to increase the speed of processing such as etching by adsorbing a reactive gas and irradiating the surface of the sample with the reactive gas adsorbed with an ion beam.

However, in this case, it is not possible to increase the speed of processing such as etching much.

As a result of the inventor's research into the cause of this problem, the adsorption coefficient of conventionally used reactive gases such as 01□ to the surface of the sample f is small, and molecular gases such as CI□ do not contribute much to etching, and only CI2 molecules are used. It was found that CI radicals and CI' ions, which were dissociated or ionized by collision with the sample substrate, were mainly adsorbed onto the surface of the sample substrate and contributed to etching (see FIG. 5).

(Means for Solving the Problems) The first invention of the present application has been completed based on the above knowledge, and consists of a focused ion beam generating section in which an ion source and a focusing lens system are arranged, It consists of a sample processing chamber located adjacent to a focused ion beam generating section, and a semiconductor board sample placed within the sample processing chamber is irradiated with the focused ion beam generated by the focused ion beam generating section. A semiconductor substrate processing device using a focused ion beam, characterized in that a radical generation tube is inserted into the sample processing chamber, and a radical discharge port of the radical generation tube is arranged close to the sample surface. This is a semiconductor substrate processing device that uses a focused ion beam.

The second invention of the present application further improves the first invention of the present application, in which a radical generating tube is inserted into the sample processing chamber,
Its configuration uses the focused ion beam of the first invention described above.
A protective cylinder communicating with the focused ion beam generating section is provided in the processing bag for the conductor substrate, protruding into the sample processing chamber, and the ion beam emitted from the focused ion beam generating section passes through the protective cylinder. It is designed to irradiate a semiconductor substrate sample.

(Function) That is, in the first invention of the present application, a radical generating tube is inserted into the sample 1 processing chamber, and the radical discharge port of the radical generating tube is arranged close to the sample surface. Therefore, radical gases such as C1 radicals generated by discharge etc. have a large adsorption coefficient to the surface of the semiconductor substrate sample f, and are constantly adsorbed to the surface of the sample f even when the sample is not irradiated with the scanning ion beam.

In this way, since the ion beam is irradiated with the CI radicals adsorbed onto the surface of the sample f, the etching rate increases significantly (see FIG. 4).

In addition, in the first invention of the present application, in addition to inserting a radical generating tube into the sample processing chamber to feed radical gas into the chamber, an etching tube is inserted into the chamber and an etching gas such as chlorine gas is fed therefrom. Processing such as etching of the semiconductor substrate may be promoted using both a radical gas and a molecular etching gas such as chlorine gas.

On the other hand, in the first invention of the present application, since the radical generating tube is inserted into the sample processing chamber, the distance # (working distance: WD) from when the ion beam enters the sample processing chamber until it is irradiated onto the sample surface is become longer.

Normally, when the ion energy number lO is greater than ev, the working distance is 3 to 4c+a, or this application: JIJ1
In the case of the invention, it can be as much as 100 to 150 mm.

The ion beam is scattered more, and the focusing ability of the ion beam is impaired.

In this case, is it possible to shorten the working distance by bending the radical generating tube inside the sample processing chamber?
When the radical generating tube is bent, the radicals generated within the tube are adsorbed by the tube wall, resulting in a decrease in energy and the generated radicals returning to their molecular state.

The second invention of the present application improves the above-mentioned drawbacks of the first invention of the present application, and is provided with a protective tube that projects into the sample processing chamber and communicates with the focused ion beam generator, and the focused ion beam is emitted from the focused ion beam generator. Most of the ion beam to be etched passes through the protective cylinder and is irradiated onto the semiconductor substrate sample, so it is possible to avoid collision of the ion beam with etching gas such as radical gas that exists in the sample processing chamber, thereby preventing the ion beam from reaching the sample surface. The focusing ability of the irradiated ion beam is not impaired.

(Example) Examples of this invention will be shown below.

Furthermore, two intake pipes 4a and 4b are provided above and below on the sides of the focused ion beam generating section 1, and the inside of the focused ion beam generating section 1 is kept in a high vacuum state.

Reference numeral 5 denotes a sample processing chamber adjacent to the focused ion beam generation section l via a partition wall 6. The sample processing chamber 5 has an intake pipe 7 at the bottom, makes the inside of the chamber evacuated, and processes the sample using a transfer means 8. A sample IO such as a semiconductor substrate placed on a sample stage 9 is placed at a predetermined position within the chamber 5.

On the other hand, a radical generating tube 11 constituted by a discharge tube or the like is inserted into the sample processing chamber 5, and a radical discharge port 11a at the tip of the radical generating tube 11 is positioned close to the surface of the sample IO.

In the above configuration, a C1 molecule is inserted into the radical generating tube ll, and a radical CI is
The generated radicals CI are released from the release port 11a and adsorbed onto the surface of the sample IO.

On the other hand, the ion beam extracted by the liquid metal ion source 2 is focused by a focusing lens system 3, and furthermore, radical C
Due to the synergistic effect of 1 and the irradiated ion beam, the processing of the etching cap can be carried out efficiently.

FIG. 2 shows an embodiment of the second invention of the present application,
In contrast to the embodiment shown in FIG. 1, in addition to the radical generating tube [l], an etching gas introduction tube 12 is inserted into the sample processing chamber 5, and its discharge port +2a is placed close to the surface of the sample 10. Furthermore, a protective tube 13 is provided at the lower center of the partition wall 6 and communicates with the focused ion beam generating section 1 so as to protrude into the sample processing chamber 5.
An ion beam exit pinhole 13a is formed at a position close to the surface, for example, at a position of 5 to 110l1lI, and the rest of the structure is the same as that of the embodiment shown in FIG.

Note that the inside of the protection tube 13 is maintained in the same vacuum system as the ion beam generating section 1 by communicating with the ion beam generating section 1 .

In the above configuration, the surface of the sample 10 is sprayed with radicals C1 from the radical generating tube 11, and irradiated onto the surface of the sample 10 from the etch output pinhole 13a, as explained in the embodiment shown in Fig. fJS1. be.

Therefore, in this embodiment, the ion beam passes through the protection tube 13 kept in vacuum, and can be irradiated onto the surface of the sample 10 without passing through the sample processing chamber 5.

■! However, in this embodiment, unlike the embodiment shown in FIG.
Since the traveling distance of the ion beam to be irradiated onto the surface of the ion beam is not long and is extremely short, as seen in the embodiment shown in FIG. There is no loss of sex.

Furthermore, in this embodiment, in addition to the radicals C1, an etching gas such as chlorine gas is sprayed onto the surface of the sample 10, so that the etching rate can be further increased than in the embodiment shown in FIG.

The protection tube 13 may be of a conical shape in the embodiment shown in Figure M2, or may be limited to this.

(Effects of the Invention) In summary, according to the first invention of the present application, a semiconductor substrate can be etched by replacing the conventional molecular gas as an etching gas.

Furthermore, in the second invention of the present application, the drawbacks associated with adopting the configuration of the first invention can be overcome, and processing such as surface etching of a semiconductor substrate can be performed without impairing the focusing property of the ion beam.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the first invention of the present application, and FIG.
The figure is a schematic diagram showing an embodiment of the second invention of the present application, and FIG.
a) and (b) are cross-sectional side views showing other examples of the protective tube used in the second invention of the present application, FIG. 4 is an explanatory diagram of the etching mechanism of the first invention of the present application, and FIG. FIG. 6, which is an explanatory diagram of the etching mechanism, is a schematic diagram of etching gas on the surface of a semiconductor substrate using a focused ion beam according to a conventional method. In the figure, ■ is a focused ion beam generator, 2 is an ion source, and 3 is a focused ion beam generator.
1 is a focusing lens system, 5 is a sample processing chamber, 10 is a semiconductor substrate sample, 11 is a radical generating tube, and 13 is a protective tube.

Claims (2)

[Claims] (1) Consisting of a focused ion beam generation section in which an ion source and a focusing lens system are arranged, and a sample processing chamber arranged adjacent to the focused ion beam generation section, the ion beam generated in the focused ion beam generation section In a semiconductor substrate processing apparatus using a focused ion beam that irradiates a semiconductor substrate sample placed in the sample processing chamber with a focused ion beam, a radical generation tube is inserted into the sample processing chamber, and the radical generation tube is A semiconductor substrate processing apparatus using a focused ion beam, characterized in that a radical emitting port is arranged close to the sample surface. (2) Consisting of a focused ion beam generating section in which an ion source and a focusing lens system are arranged, and a sample processing chamber arranged adjacent to the focused ion beam generating section, the ion beam generated in the focused ion beam generating section is In a semiconductor substrate processing apparatus using a focused ion beam that irradiates a semiconductor substrate sample placed in the sample processing chamber with a focused ion beam, a radical generation tube is inserted into the sample processing chamber, and the radical generation tube is A radical discharge port is disposed close to the surface of the sample, and a protective tube communicating with the focused ion beam generating section is provided protruding into the sample processing chamber, so that almost no ion beam is emitted from the focused ion beam generating section. A semiconductor substrate processing apparatus using a focused ion beam, characterized in that the semiconductor substrate sample is irradiated through the protective cylinder.