JPH0618184B2 - Ion beam etching method - Google Patents

Description

The present invention relates to a sputtering effect of ions by irradiating an ion beam through a resist mask on a thin film formed on a substrate made of a material such as ceramics by a vacuum deposition method or a sputtering method. The present invention relates to an ion beam etching method for removing an exposed portion of a thin film.

Configuration of Conventional Example and Problems Thereof In recent years, the demand for devices using thin films has been increasing year by year mainly in the semiconductor field. On the other hand, in the manufacturing method, there are various steps such as adhesion and removal of a thin film, and an appropriate processing method and apparatus are used according to the application. An ion beam etching method has been studied as one of the thin film removing methods.

Hereinafter, a conventional ion beam etching method will be described with reference to the drawings.

FIG. 1 shows a conventional ion beam device.
In FIG. 1, reference numeral 1 is a vacuum chamber capable of maintaining a vacuum state. Reference numeral 2 is a pipe made of stainless steel for introducing gas particles from the outside of the vacuum chamber 1 into the inside of the vacuum chamber 1. Reference numeral 3 is an ion generation chamber for converting gas particles introduced through the pipe 2 into ion particles by gas discharge. Reference numeral 4 is a workpiece on which a pattern is formed by a resist mask, 4a is a substrate made of alumina, and 4b is a film formed by a vacuum deposition method or the like with a thickness of about 10
A thin film of 00Å, and 4c is a resist mask having a film thickness of about 1.7 μm. Reference numeral 5 denotes an ion extracting electrode for extracting the ion particles from the ion generating chamber 3 to irradiate the surface of the workpiece 4 with the ion particles produced in the ion generating chamber 3 as an ion beam. 6 suppresses the workpiece 4 from rising in temperature due to ion beam irradiation,
Cooled to prevent deterioration of the resist mask 4c,
It is also a rotatable sample table. An ion beam 7 is extracted from the ion generation chamber 3.

The operation of the ion beam device configured as described above will be described below.

First, the degree of vacuum in the vacuum chamber 1 is set to 2 × 1 using a vacuum pump.
After vacuum evacuation to 0 ^-5 Torr or less, an argon (hereinafter abbreviated as Ar) gas is introduced into the ion generating chamber 3 at a constant flow rate of 6.0 to 7.0 SCCM through the pipe 2, and the vacuum degree in the vacuum chamber 1 is set. Is maintained at about 1.8 × 10 ⁻⁴ Torr. The ion extraction electrode 5 and a predetermined electrode in the ion generation chamber 3 are energized to cause a gas discharge of Ar in the ion generation chamber 3. That is, the Ar particles introduced into the ion generation chamber 3 by the pipe 2 are converted into Ar ion particles by excitation. At the same time, the Ar ion particles generated in the ion generation chamber 3 are accelerated through the ion extraction electrode 5 and are irradiated onto the workpiece 4 as the ion beam 7. The Ar ion particles that have collided with the surface of the workpiece 4 remove the atoms of the workpiece 4. That is, when the accelerated Ar ion particles collide with the workpiece 4, the momentum of the Ar ion particles moves to the atoms of the workpiece 4, and the atoms are changed by the Ar ion particles.
Be kicked out. Therefore, the ion beam etching with Ar ion particles utilizes the above-mentioned sputtering effect, and when the energy of Ar ion particles is larger than the binding energy (about 25 eV) of the constituent atoms of the workpiece 4. proceed. In this case, the resist mask 4c also
Although it is removed by the ion beam 7 together with the thin film 4b to be etched, the exposed portion of the thin film 4b can be removed earlier than the resist mask 4c because the thin film of the resist mask 4c is larger than the thin film 4b. It is possible. Further, the processing speed (etching speed) R (θ) of the workpiece 4 by the irradiation of the ion beam 7 is generally expressed by the following equation.

R (θ) = A × I × S (θ) cos θ / n Å / min where n is the atomic density of the workpiece 4 (atoms / c
m ³ ), I is the ion beam current density (mA / cm ² ), θ
Is the angle of incidence of the ion beam on the workpiece 4, S (θ) is the sputtering rate, and A is a constant. That is, the processing speed of the workpiece has a relationship proportional to the ion beam current density. Accordingly, the ion beam current density of the ion beam 7 with which the workpiece 4 is irradiated is on the surface of the workpiece 4,
If the distribution of strength is strong, the processing speed of the workpiece 4 has a distribution. In general, many workpieces 4 require processing uniformity. For example, during overetching,
Various problems associated with processing uniformity, such as those that adversely affect the base of the processing tank, and that the product line quality of the processing object 4 deteriorates due to the reduction of the processing line width fidelity of the processing object 4 due to the receding of the resist. There is. Therefore, although it depends on the size of the workpiece 4, by rotating the sample table 6, the product of the ion beam current density and the irradiation time at each position on the surface of the workpiece 4 is within a fixed processing time. Attempts have been made to make it almost constant. However, when the beam incident angle of the ion beam 7 with respect to the workpiece 4 is changed and the processed cross section of the workpiece 4 is inclined, the cross section becomes tapered in the conventional method. As described above, the conventional ion beam apparatus has a processing defect due to the rotation of the sample table 6.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to obtain the product of the ion beam current density and the ion beam irradiation time at each position on the surface of the workpiece without rotating the workpiece. However, the present invention provides an ion beam etching method that can make the workpiece substantially constant and improve the processing uniformity of the workpiece.

Configuration of the invention The present invention is a vacuum chamber capable of maintaining a vacuum state, an ion generation chamber provided in the vacuum chamber for converting gas particles introduced from outside the vacuum chamber into ion particles, and the ions Irradiates the workpiece with the ion beam, which has an ion extraction chamber and an ion extraction electrode provided between the workpiece so that the particles can be used as the ion beam to irradiate the workpiece placed in the vacuum chamber. In the ion beam etching method in which the etching is performed by arranging a shield plate on the ion beam incident path to the workpiece for a certain time during the etching of the workpiece, only a part of the workpiece is provided. This is an ion beam etching method in which the shielding plate is removed and the work piece is etched after the ion beam irradiation of the work piece is cut off. The value of the product of the on-beam current density and the ion beam irradiation time can be made almost constant within the processing time, and the processing uniformity with the workpiece can be improved.

Description of Embodiments An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an ion beam device according to the first embodiment of the present invention. In FIG. 2, 11 is a vacuum chamber, 12 is a material for introducing Ar gas from the outside of the vacuum chamber 11 into the vacuum chamber 11, and the diameter is 6
mm pipe, 13 is Ar introduced by pipe 12
An ion generation chamber for converting gas particles into Ar ion particles by gas discharge, 14 is a work piece, 14a is a substrate made of alumina and has a shape of 60 × 60 × 1, and 14b is formed by a vacuum deposition method. A thin film having a thickness of about 1000Å, 14c a resist mask having a thickness of about 1.7 μm, 15 an ion extraction electrode made of molybdenum for extracting Ar ion particles from the ion generation chamber 13 to the workpiece 14 side, 16 Is a cooled sample stage for suppressing the temperature rise of the workpiece, 1
Reference numeral 7 is an ion beam extracted from the ion generation chamber 13,
8 can be located on the incident path of the ion beam 17 to the work piece 14, and the irradiation of the ion beam 17 to a part of the work piece can be blocked for at least a certain time during the processing of the work piece 14. The material is molybdenum, and is a disc-shaped grounding shield plate having a diameter of φ44 × 1.2.

The operation of the ion beam device configured as described above will be described below.

First, the degree of vacuum in the vacuum chamber 11 is set to 2 × with a vacuum pump.
After vacuum evacuation to 10 ^-5 Torr or less, pipe 12 for Ar
The gas is introduced into the ion generating chamber 13 at a constant flow rate of 6.0 to 7.0 SCCM. At this time, the degree of vacuum in the vacuum chamber 11 is 1.
It becomes 8 × 10 ^-4 Torr. Next, the ion extracting electrode 15 and a predetermined electrode of the ion generating chamber 13 are energized to generate an accelerated ion beam 17 of Ar ion particles. About 4
After the shielding plate 18 blocks the ion beam 17 incident on the central portion of the workpiece 14 for 50 seconds, the shielding plate 18 is removed from the incident path of the ion beam 17 to the workpiece 14. That is, the ion beam 17 on the workpiece 14 is irradiated to the peripheral portion on the workpiece 14 for about 450 seconds, and then to the entire surface of the workpiece 14. About 150 seconds after removing the shield plate 18, the thin film 14b not covered with the resist mask 14c was almost simultaneously etched over the entire area of the workpiece 14 to expose the base substrate. Here, in order to compare with the conventional one, the following experiment was carried out by using the same workpiece 14 as described above under the same generation condition of the ion beam 17. However, the sample table 16 was not rotated. That is, the shield plate 16 is removed from the initial state from the incident path of the ion beam 17 to the work piece 14 and the work piece 14 is removed for about 300 seconds.
The ion beam 17 is irradiated on the top. Then, the vacuum chamber 11
After removing the work piece 14 from the work piece and removing the resist mask 14c with a chemical, the etching depth of the thin film 14b at 9 positions is measured by using a highly accurate minute step measuring device, and the processing speed at the 9 position is determined. The calculated processing uniformity was evaluated from the average value and the processing speed at 9 positions, and it was about ± 70%. Next, according to the present invention, the shield plate 18 is used for about 230 seconds.
Then, after the ion beam 17 incident on the central portion of the workpiece 14 is blocked, the shield plate 18 is removed from that position in the same manner as described above, and then the ion beam 17 is exposed to the workpiece 14 for about 75 seconds. Then, the processing uniformity was determined in the same manner as above, and it was about ± 16%. That is,
Compared with the conventional method, it means that the variation of the product value of the ion beam current density and the ion beam irradiation time at each position on the surface of the workpiece 14 is reduced, and the processing uniformity is improved. I think.

EFFECTS OF THE INVENTION As described above, according to the present invention, between the ion extraction electrode and the workpiece, the ion beam incidence path section to the workpiece is processed at least for a certain period of time during the processing of the workpiece by ion beam irradiation. The value of the product of the ion beam current density and the ion beam irradiation time at each position on the surface of the workpiece by providing at least one shield plate capable of blocking the ion beam irradiation to a part of the workpiece. Can be made substantially constant within the processing time, and the processing uniformity of the workpiece can be improved, which is extremely advantageous in practical use.

In this embodiment, the effective portion of the ion beam to the workpiece is blocked by the shield plate at the beginning of the processing, but it may be blocked at the end of the processing. Further, the ion beam of the effective portion of the ion beam by the shield plate may be interrupted periodically or intermittently. In the present embodiment, the shield plate is composed of one plate and has a disk shape. However, it may have a non-linear shape, two or more pieces may be used, and the shield plate shape may be continuous, intermittent, or cyclic. You may change it.

In short, it is sufficient that the product of the ion beam current density and the ion beam irradiation time can be made almost constant within the required processing time at each position on the surface of the workpiece.

Although argon gas is used in this embodiment, xenon gas, helium gas, or a mixed gas thereof may be used.

In this embodiment, the shield plate is made of molybdenum, but may be made of carbon.

[Brief description of drawings]

FIG. 1 is a sectional view showing a conventional ion beam apparatus, and FIG. 2 is a sectional view showing an ion beam apparatus according to an embodiment of the present invention. 11 ... Vacuum tank, 13 ... Ion generation chamber, 14 ... Workpiece, 15 ... Ion extraction electrode, 18 ... Shield plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Saeki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-55-62735 (JP, A) JP-A-57-177975 (JP, A)

Claims (1)

[Claims] 1. A vacuum chamber capable of maintaining a vacuum state, an ion generating chamber provided in the vacuum chamber for converting gas particles introduced from outside the vacuum chamber into ion particles, and the ion particles. As an ion beam, it has an ion extraction electrode provided between the ion generation chamber and the workpiece to irradiate the workpiece placed in the vacuum chamber, and irradiates the workpiece with the ion beam. In an ion beam etching method for performing etching, by arranging a shield plate on an ion beam incident path to the workpiece for a certain time during etching of the workpiece, ions to only a part of the workpiece are provided. An ion beam etching method in which the shield plate is removed and the workpiece is etched after the beam irradiation is blocked.