JPH0770299B2 - Ion beam processing apparatus and surface processing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention scans an ion micro-beam obtained by focusing ions extracted from an ion source to scan a sample to be processed such as wiring on a semiconductor substrate. The present invention relates to an ion beam processing apparatus and a surface processing method for cutting and connecting wiring by directly irradiating the processing section, and particularly for improving the accuracy of confirming the end of work in this type of processing work. Is.

[Background of the Invention]

Recently, microfabrication using high current density ion microbeam has been attempted. This microbeam processing technology is an essential technology for manufacturing future VLSI devices.

FIG. 1 is a basic configuration diagram of an apparatus for explaining a conventional ion microbeam processing apparatus. Ions extracted from the ion source 1 are focused by the electrostatic lens 2 to form an ion microbeam 3 (hereinafter abbreviated as beam 3) and irradiate the processed sample 4. Reference numeral 5 denotes a deflector for scanning the beam 3 on the processed sample 4, which is connected to the scanning power source 6. The secondary electron e is emitted from the processed sample 4 by the irradiation of the beam 3 and detected by the secondary electron detector 7. In addition,
10 indicated by a broken line is a vacuum container. Secondary electron image observation section 8
In the CRT (cathode ray tube) inside, the beam scanning (x axis and y axis) synchronized with the scanning power source 6 is performed, and the signal corresponding to the secondary electron intensity from the secondary electron detector 7 is subjected to the brightness modulation (z
Axis), the secondary electron image on the beam scanning surface of the processed sample 4 is observed, and this is used to process the processed sample 4
The processing area of is set. When the processing operation is completed, the sample atoms in the processing area are removed, and a dent is formed there, and the underlying sample appears on the surface, so the secondary electron intensity in that area is different from that before the processing operation. Come on. By monitoring this change, the end of machining work was confirmed.

However, in the above-described conventional processing apparatus, since the change in secondary electron intensity is used to monitor the end of processing, for example, in the case of cutting a wiring pattern, the processing end instruction for the change in secondary electron intensity does not necessarily indicate the wiring. There is a problem that the electric cutting of the pattern does not always coincide with the processing end instruction. The main causes are non-uniformity depending on the processing location and redeposition of sample atoms once removed by beam irradiation.

[Object of the Invention]

An object of the present invention is to provide an ion beam processing apparatus and a surface processing method capable of eliminating the above-mentioned inconveniences in the prior art and accurately monitoring the end of the processing work.

[Outline of Invention]

A first aspect of the present invention for achieving the above object is to provide a sample having wiring, a means for setting the wiring to a first potential, a means for irradiating the sample with an ion beam, and a portion near the wiring. And to detect the processing state of the wiring by detecting the intensity of secondary electrons generated from the sample surface and passing through the metal mesh, and the metal mesh set to the second potential. An ion beam processing apparatus characterized by having a secondary electron detector of
A second gist is to irradiate a sample having wirings with an ion beam, and to detect secondary electrons having an energy of a predetermined value or more among secondary electrons generated from the sample by the irradiation of the ion beam with a secondary electron detector. The surface processing method is characterized in that the processing state of the wiring is detected by detecting with. INDUSTRIAL APPLICABILITY The present invention can be applied not only to a work such as cutting a wiring pattern, but also to a work such as connecting a wiring pattern.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. The ion source 1 is a liquid metal ion source with high brightness, and the ions extracted from the ion source 1 are focused by an electrostatic lens 2 and a beam 3 thereof is applied to a processed sample 4. In the microbeam processing device, a blanking electrode for controlling the on / off of the beam is provided in the middle of the ion optical system, but it is omitted in FIG.

First, the case of cutting the wiring pattern will be described. FIG. 3 (a) shows an example in which the wiring pattern on the processed sample 4 is cut at a part of the position PP 'to electrically cut the pattern into A and B.

The pattern is aluminum wiring (conductor) formed on silicon oxide (insulator). The patterns A and B are connected to the terminals 11 and 12 so that the potentials V _A and V _B are given respectively. The terminal 11 is grounded through the control power supply 13 and the ammeter 9. The terminal 12 is grounded through the control resistor 14, the control power supply 13 ', and the ammeter 9'. However, wiring pattern B
The potential of is V _A when it is connected to the wiring pattern A, and V _B is applied after cutting.

Returning to FIG. 2, a hemispherical metal mesh 15 is provided on the processed sample 4, and a variable electric potential V _m is applied to the control power source.
Given by 16. Secondary electrons that exceed this potential V _m
Only the metal mesh 15 can pass through and is detected by the secondary electron detector 7. The output of the secondary electron detector 7 is used for the brightness modulation of the CRT of the secondary electron image observing section 8, and the beam deflection of the CRT is the beam 3
Is performed in synchronization with the scanning of.

FIG. 3 (b) is a secondary electron image from the wiring pattern portion of FIG. 3 (a). Even during the cutting work at the PP 'position by the beam scanning, sometimes the entire surface beam is scanned and the secondary electron image as shown in Fig. 3 (b) is observed to judge whether the cutting work is completed or not. It is a thing. In other words, most of the kinetic energy of secondary electrons emitted from the sample is 10 eV or less, so when V _A −V _m > 10 V, most of the secondary electrons from the wiring pattern A are metallic. Secondary electron image observation is not possible because it cannot pass through the mesh 15. Conversely, control power supply
By controlling either 13 or 16, or both, V _A or V _m is changed to V _A −V _m <10 V, so that the secondary electron image observation of the wiring pattern A can be performed. The wiring patterns A and B are electrically connected in the middle of the cutting work, and both patterns are used in the secondary electron image observation.
The changes to control V _A and V _m are the same.

However, since the electric potential of the wiring pattern B is different from the electric potential V _{A of} A after the end of the cutting work, the change in secondary electron image observation is different. That is, considering the case where the pattern B is not connected to the control power supply 13 ', the pattern A is charged immediately after the disconnection work for charging up.
Can be seen, but pattern B cannot be seen. In this way, the end of cutting work can be detected with high accuracy. further,
By using the control power supply 13 'and changing the potential V _{B of the} pattern B, it can be reconfirmed whether or not the patterns A and B are electrically connected, and the judgment of the cutting work can be made with higher accuracy. Become so.

In FIG. 3 (a), two control power sources 13 and 13 'are provided, but as can be understood from the above description, 13 or 13'.
It is possible to realize the present invention by providing either one of the control power supplies, and at least one of the two control power supplies 13 and 16 in FIG. 2 is an extended power supply whose output voltage is variable. good.

Here are specific numerical examples. A Ga liquid metal ion source was used as the ion source, the ion microbeam was a 16 keVGa ⁺ beam, the beam diameter was 0.5 μm, the current density was 0.3 A / cm ² , and the wiring pattern was an Al pattern on silicon oxide with a width of 2 μm and a thickness. About
0.2 μm. Under the above conditions, it was found that the cutting work was completed in a few tens of seconds.

Next, the case of connection work for connecting the cut portions of the wiring pattern will be described. The sample is the same as in the above example. However, the width of the part where the pattern is cut is about 2
μm. In this embodiment, a 3 keV Ga ⁺ beam is used as a microbeam for connection work, and the beam diameter is about 20.
μm, current density is about 0.01 A / cm ² . A 10 keVGa ⁺ beam with a beam diameter of about 0.5 μm was used for secondary electron image observation. Both beams can be easily selected simply by switching the voltage applied to the ion source. The time required for the connection work was 1 to 2 minutes. In the case of this connection work, immediately after the wiring patterns A and B are electrically connected, both patterns show the same behavior with respect to the change of V _A V _{m in} the secondary electron image.

In addition, although the Ga liquid metal ion source is described as an example of the ion source in the above-mentioned embodiments, it goes without saying that another ion source such as a field ionization type ion source may be used.
Also, when using a liquid metal ion source, the substance to be ionized is not limited to Ga, and various substances can be used according to the application. When an ionized substance such as an alloy is used, a mass spectrometer may be inserted in the ion optical system to select only a desired ion species.

〔The invention's effect〕

As described above, according to the present invention, it is possible to highly accurately confirm the end of processing work in ion beam processing, and as a result, it is possible to perform high-precision processing such as cutting or connecting a wiring pattern on a semiconductor substrate. And higher efficiency are possible.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a conventional device, FIG. 2 is an overall configuration diagram for explaining an embodiment of the present invention, and FIG. 3 is a diagram for explaining the operation and effects of the present invention. Schematic diagram of
(B) is a figure which shows the secondary electron image of the wiring pattern part shown to (a). <Explanation of symbols> 1 ... Ion source, 2 ... Electrostatic lens 3 ... Ion microbeam 4 ... Processed sample, 5 ... Deflector 6 ... Scanning power supply, 7 ... Secondary electron detector 8 ... … Secondary electron image observation unit, 9, 9 ′ …… Ammeter 10 …… Vacuum container, 13, 13 ′, 16 …… Control power supply 15 …… Metal mesh

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaoru Umemura 1-280 Higashi Koigakubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Itsuzo Tamura 1-280 Higashi Koigakubo, Kokubunji, Tokyo Central Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-58-164135 (JP, A) JP-A-49-99077 (JP, A)

Claims (12)

[Claims] 1. A sample having wiring, a means for setting the wiring to a first potential, a means for irradiating the sample with an ion beam, and a means provided near the wiring and having a second potential. A conductive structure that sets an electric field between the wiring and the wiring, and a processing state of the wiring by detecting the intensity of secondary electrons generated from the sample surface and passing through the space of the electric field. And a secondary electron detector for detecting the ion beam. 2. The ion beam processing apparatus according to claim 1, wherein the conductive structure for generating an electric field between the wiring and the wiring is a metal mesh. 3. The ion beam processing apparatus according to claim 1, wherein the ion beam has a function of cutting the wiring. 4. A control power supply capable of arbitrarily setting an output voltage is connected to at least one of the wiring and the conductive structure.
The ion beam processing apparatus according to item 2, item 2 or item 3. 5. The ion beam processing apparatus according to claim 2, wherein the metal mesh has a hemispherical shape. 6. The ion beam according to claim 1, wherein the ion beam is an ion beam obtained by focusing ions extracted from an ion source.
Item, the ion beam processing apparatus according to Item 4 or Item 5. 7. The ion beam processing apparatus according to claim 6, wherein the ion source is a liquid metal ion source. 8. The ion beam processing apparatus according to claim 6, wherein the ion source is a field ionization type ion source. 9. The energy and beam diameter of the ion beam are variable, and the scope of claim 1
The ion beam processing device according to item (2), item (3), item (4), item (5), item (6), item (7) or item (8). 10. The potential difference between the first potential and the second potential is less than 10 V, as claimed in claims 1, 2, 3, 4, and 5. The ion beam processing apparatus according to item 5, item 6, item 7, item 8 or item 9. 11. The wiring according to claim 1, wherein the wiring is a metal wiring made of a metal.
Item, Item 3, Item 4, Item 5, Item 6, Item 7, Item 8
Item, the ion beam processing apparatus according to Item 9 or 10. 12. A sample having a wiring, a means for setting the wiring to a first potential, a means for irradiating the sample with an ion beam, a means provided near the wiring, and having a second potential. An ion beam processing apparatus having a conductive structure that is set to generate an electric field between the wiring and a secondary electron detector that detects secondary electrons generated from the surface of the sample is used, and ions are added to the wiring. Ions characterized by detecting the processing state of the wiring by detecting the intensity of secondary electrons that have passed through the space of the electric field among the secondary electrons generated from the wiring when processing by irradiating a beam Beam surface treatment method.