JPH0358415A - Reactive ion etching device - Google Patents

Abstract

PURPOSE:To prevent the electrostatic breakdown of the gate SiO2 of a MOS capacitor by a method wherein, when an etching treatment is conducted using magnetron discharge produced through application of magnetic field, intensity of magnetic field at the point immediately above the semiconductor substrate, placed on a substrate-installing electrode, is set st 160 Gauss or below, and the pressure is set at 10 pa or below during etching operation. CONSTITUTION:In a reactive ion etching device provided with an electrode, on which a semiconductor substrate 3 is placed, and an electrode 1 provided opposing to the installation electrode 2, magnetic field is formed through a magnetic field coil 5 at the outside of an etching chamber 6. In this case, when etching is conducted using magnetron discharge produced through application of magnetic field onto the interior or the exterior of a reaction chamber, intensity of the magnetic field at a point directly above the semiconductor substrate 1 placed on the installing electrode 2, is set at 160 Gauss or less, and the pressure during etching operation is set at 10 pa or less. As a result, electrostatic breakdown of the gate SiO2 of an MOS device due to charge-up of the particles can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reactive ion etching apparatus. [Prior art] Reactive ion etching equipment using this type of magnetron discharge has already been developed, but in order to reduce the self-bias voltage or increase the etching rate, the strength of the magnetic field directly above the etching substrate has been reduced. is 200 Gau
It has become more than ss. Furthermore, the pressure used during etching varies widely from several pa to several tens of pa. [Problems to be Solved by the Invention] The conventional equipment described above is designed with only an increase in etching rate and a decrease in ion energy in mind, and does not take into account the effect on devices due to the charge-up of charged particles. There are drawbacks. An object of the present invention is to provide a reactive ion etching apparatus that solves the above problems. Differences between the invention and the prior art] In contrast to the above-described conventional reactive ion etching apparatus that applies a magnetic field, the present invention uses a magnetic field strength of 160 Gauss directly above the substrate to be etched, and a pressure of 10 pa or less during etching. The difference is that it is [Means for Solving the Problems] In order to achieve the above object, a reactive ion etching apparatus according to the present invention includes an installation electrode for installing a semiconductor substrate;
In a reactive ion etching apparatus having a counter electrode provided opposite to the installation electrode, when performing etching using magnetron discharge by applying a magnetic field inside or outside the reaction chamber, the installation electrode is The magnetic field strength directly above the installed semiconductor substrate is set to 160 Gauss or less, and the pressure during etching is set to lopa or less. [Example] Next, the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In the figure, 1 is a counter electrode, 2 is a substrate installation electrode on which a semiconductor substrate 3 is placed, and the electrodes 1 and 2 are provided vertically to face each other. 4 is a high frequency power source. 5 is a magnetic field coil, and the magnetic field applied by the magnetic field coil 5 is formed outside the etching chamber 6. Even if this magnetic field is applied around the installed electrode 2 in the chamber 6, the effect is the same. In the reactive ion etching apparatus according to the present invention, the magnetic field strength is set to 160 Gauss or less in order to suppress the influence of charged particle charge-up on the device.
The etching pressure is set to 10 pa or less. Increasing the magnetic field strength or increasing the pressure increases the density of the plasma, increasing the etching rate, but at the same time increases the charge-up of charged particles on the device. Therefore, the present invention indicates a range of magnetic field strength and etching pressure in which the influence of charge-up of charged particles does not occur in a reactive ion etching apparatus that applies a magnetic field. Figures 2 and 3 show CMO using the above etching apparatus.
O to S inverter circuit, (27sec+a) 10S
F, (3 sec) shows the increase in leakage current after plasma irradiation. FIG. 2 shows the dependence on the applied magnetic field strength. The pressure is fixed at 10pa and the power is fixed at 150w. As shown in this figure, it can be seen that as the magnetic field strength increases, the leakage current within the device increases. Furthermore, as shown in FIG. 4, it can be seen that when the gate Sin and breakdown voltage of the MOS capacitor exceeds 160 Gauss, it deteriorates significantly. For this reason, the applied magnetic field strength must be 160 Gauss or less. FIG. 3 shows the etching pressure dependence when the applied magnetic field was fixed at 160 Gauss. Power is 15OW
It is. As the pressure is increased as shown in this figure,
The leakage current increases, and as shown in Figure 5,
When it becomes more than Opa, the gate Si of the MOS capacitor
n, it can be seen that the withstand voltage deteriorates. From this, it can be said that the etching pressure must be 10 pa or less. [Effect of the Invention J As explained above, the present invention provides a reactive ion etching apparatus that applies a magnetic field, by setting the magnetic field strength directly above the etching substrate to 160 Gauss or less and the pressure to 10 pa or less, thereby reducing the charge-up of charged particles. M.O.
This has the effect of preventing electrostatic damage to the gate S i O of the S device.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is a diagram showing the magnetic field strength dependence of the charge-up effect of charged particles on the device, FIG. 3 is a diagram showing the pressure dependence, and FIG. Figure 4 shows the gate SiO. Figure 5 shows the dependence of the breakdown voltage deterioration on the magnetic field strength.
, is a diagram showing the pressure dependence of pressure deterioration of . l...Counter electrode 2...Substrate installed electrode 3.
...Semiconductor substrate 4...High frequency power supply 5...Magnetic field coil

Claims (1)

[Claims] (1) In a reactive ion etching apparatus that has an installation electrode for installing a semiconductor substrate and a counter electrode provided opposite to the installation electrode, a magnetic field is applied inside or outside the reaction chamber to generate magnetron discharge. A reactive ion etching apparatus characterized in that, when performing etching using the above-described method, the magnetic field strength directly above the semiconductor substrate placed on the installation electrode is set to 160 Gauss or less, and the pressure during etching is set to 10 pa or less.