JPS6020437A - negative ion source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion source for ion etching used in electronic device manufacturing processes.

Currently, the etching process in the electronic device manufacturing process is shifting from wet etching to dry etching. Examples include etching. Further, the gas used for these dry etchings is a gas containing halogens such as fluorine and chlorine. Safe (generally used) LX containing halogen
, for example if CF4 p CFzClp C1Fm +
CC15+ SFs and the like contain carbon atoms, sulfur atoms, etc.9, and there is a possibility that the sample may be contaminated by smearing. Therefore, an etching method can be considered in which these gases are introduced into an ion source and negative ions obtained by discharge are used, that is, negative ions in which carbon and sulfur are less likely to exist. However, since there is no large-area negative ion source suitable for the purpose of ion etching, etching using negative ions has been carried out using the method shown in FIG.

FIG. 1 is a block diagram showing an etching method using negative ions using a conventional ion source. That is, ion source 1
A reactive gas is introduced into 1, and sample 15 of the positive ions 12, negative ions 13, and neutral particles 14 obtained is biased higher than the ion energy of positive ions 12 by bias power supply 16. This is a method of preventing the incidence of positive ions 12 and irradiating the sample 15 with negative ions. but,
With this method, there is no problem while the ion current is low, but if the ion current is increased, a discharge occurs between the sample 5 and the ion source 11, and stable etching becomes impossible.
However, there has been a strong desire to develop a negative ion source that can stably emit negative ions.

An object of the present invention is to provide a negative ion source for ion etching that enables ion etching by stably emitting negative ions.

That is, the present invention provides an ion generator having a gas inlet, an anode, a magnetic field generator, and an electron supply source, in which at least two extraction electrodes are installed between the ion generator and the sample. The negative ion source is characterized in that it includes a bias power source that biases the first electrode on the sample side negatively and the second electrode on the sample side positively.

FIG. 2 shows a configuration diagram of a first embodiment of the present invention.

In the figure, a rod-shaped cathode 22 is placed in the center of a cylindrical anode 21, and a first electrode 23, a second electrode 24, and a third electrode 2 are placed below the rod-shaped cathode 22 insulated from the anode 21.
Place 5. Molybdenum or carbon is used for this electrode. The anode 21 is also provided with an inlet 126 for introducing a reactive gas, and a solenoid coil 27 is further installed around the outer periphery of the anode 21 . 28 is a bias power source that biases the first electrode 23 negatively, and 29 is a bias power source that biases the second electrode 24 positively. The third electrode 25 is grounded.

In the case of the sample 15 company example, it is installed below the third electrode 25, but no bias is applied to this sample 15.

In the embodiment, a positive potential is applied to the 7 node 21, a reactive gas is introduced from the gas inlet 26, and the solenoid coil n
When energized, a discharge occurs. At this time, the energy of the positive ions is approximately 50 to 8 eV higher than the anode potential. Next, the first electrode 23 is negatively biased, and the second electrode 24
Add a positive bias to . The third electrode 25 is used at ground level. In FIG. 3, molybdenum electrodes are used, the bias voltage is set to about 200 to -300 V for the first electrode 23 and about 41.2 to 1.6 KV for the second electrode 24, and the electrode spacing is 2 m each. The relationship between the voltage of the second electrode 24 and the ion current is shown when the voltage of the electrode is used as a parameter. In addition, CF4 is used as the reactive gas, the pressure of the empty channel is 5XIQ""' (Torr), and the discharge voltage, that is, the potential of the anode electrode 21 is 600 (V).
It is.

In Figure @3, at any voltage of the first electrode 23, unless the voltage of the second electrode 24 is increased to 650 to 680 [V] or more, the ion current has a negative value, that is, negative ions are not emitted. Also, the value of this second electrode 24 is set to 6
The ion energy of the emitted pressure ions when discharged at 00V was 650 to 680 [V].
When the potential of 4 exceeds the energy of positive ions, the negative ion current increases rapidly, and the 4 becomes constant due to the effect of space charge. Further, from the same figure, it can be seen that by increasing the potential of the first electrode 23 to a negative value, the current of negative ions increases.

Therefore, it is clear that by using this negative ion source, negative ions with a large area suitable for ion etching can be stably obtained.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention. In this embodiment, a rod-shaped cathode 42 is installed in the center of a cylindrical anode 41, and an anode 41 and a A first electrode 43 and a second electrode 44 which are completely insulated are arranged. A solenoid coil 46 is provided around the outer periphery of the anode 41, and gas is introduced through a gas inlet 45. 47 is a bias power source that biases the first electrode 43 negatively, and 44 is a bias power source that biases the second electrode 44 positively. This example is based on the third example in the first example.
By removing the electrodes, it is possible to spread the beam even further. Although molybdenum was used as the electrode, carbon may also be used, and the electrode spacing is 2 mm. However, the radiation'rcL%
Since the third electrode is grounded in the first embodiment, there is no change in the properties in the second embodiment, and negative ions can be stably obtained.

In the above embodiments, an ion generator is illustrated which has a rod-shaped cathode in the center, a cylindrical cathode on the concentric circle thereof, a solenoid coil, and a gas inlet at the anode.
Not limited to this, in short, as long as the ion generator has a gas inlet, an anode, a magnetic field generator, and an electron supply source,
This can be utilized in the negative ion source of the present invention.

As described above, by using the negative ions v9 of the present invention, even if the ion current is increased, no single strain is released between the fitting and the ion source, and therefore stable negative ions are
and CF, using S10. When St is etched, the etching selectivity is about 1.

In addition, since it contains almost no negative ion carbon, almost no impurity deposition layer is formed on the Si surface after etching.

As described above, excellent effects can be obtained by using the negative ion source of the present invention in the manufacturing process of electronic devices and the like.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional ion source, Fig. 2 is a block diagram showing a first embodiment of the present invention, and Fig. 3 is a measurement of electrode voltage and ion current of a negative ion source according to the first embodiment. The fourth figure is a diagram showing a graph of values, and the fourth figure is a configuration diagram showing the second embodiment of the present invention. 15...°sample, 21, 41...anode, 22,
42...Cathode, 23, 43...First electrode, 2
4, 44...second electrode, 25...third electrode, 26
, 45... Gas inlet, 27, 46... Solenoid coil, 28.47... Negative bias power supply, 29.
48...Positive bias power supply patent applicant NEC Corporation

Claims (1)

[Claims] (1) In an ion generator that has a gas inlet, an anode, a magnetic field generator, and an electron supply source, at least two extraction electrodes are installed between the ion generator and the sample, and an electrode on the ion generator side is installed. A negative ion source comprising a bias power supply that biases one electrode negatively and a second electrode on the sample side positively.