JPH05339761A - Ecr plasma etching method - Google Patents

Abstract

PURPOSE:To enable etching with high anisotropy and low damage by executing the etching while applying specific pulse magnetic fields in the direction parallel with the progressing direction of microwaves and perpendicular to the progressing direction of the microwaves with respect to an ion source to stabilize plasma MHD. CONSTITUTION:The ECR plasma etching is executed by utilizing an electron cyclotron resonance (ECR) phenomenon. The etching is executed by applying >=0.08T pulse magnetic fields applied in parallel with the progressing direction of the microwaves. The etching is executed by applying >=0.08T pulse magnetic fields in the progressing direction of the microwaves with respect to the ion source to stabilize the plasma MHD. Pulse currents of 0.01 to 500ms pulse width are energized to a coil to apply the pulse magnetic fields in the direction perpendicular to the progressing direction of the microwaves. As a result, the efficiency of confining plasma is improved and the ion temp. is lowered. The anisotropic etching by the parallel pulse magnetic fields is thus executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic ECR plasma etching processing method.

[0002]

2. Description of the Related Art In the conventional ECR plasma etching method, an electron makes a circular motion around a line of magnetic force in a constant magnetic field (0.0875T) using a permanent magnet, and its angular frequency ω _C
And the angular frequency ω of the microwave coincide with each other to generate an ECR phenomenon, which is applied to etching processing.

[0003]

In the conventional ECR plasma etching process, since the ECR phenomenon is utilized in a constant magnetic field, the ion temperature in the plasma is high and the ion energy is low, so that there is anisotropy. No ECR plasma etching profile was obtained.

Reducing the ion temperature that induces a reaction in ECR plasma etching is important in terms of reducing damage due to ion bombardment. If the ion temperature is lowered, the directionality of ions can be improved. The ion temperature is considered to be approximately equal to the neutral molecule temperature. Causing a large shift in the motion of electrons and ions with different masses,
Therefore, in the magnetized plasma, it is always in the state of charge separation, and the electric field caused by the charge separation does not promptly neutralize the electric field in the state where electrons and ions are combined,
When charge separation progresses due to interaction with a magnetic field,
The plasma becomes unstable and is the main cause of heating the ions.

The present invention remedies this deficiency, stabilizes the plasma, and enables anisotropic etching processes.

[0006]

According to the present invention, in an ECR plasma etching method utilizing an electron cyclotron resonance (ECR) phenomenon, a pulse magnetic field of 0.08 T or more is applied in parallel with the traveling direction of microwaves, 0.08 in the direction perpendicular to the direction of microwave transmission to the source
This is an ECR plasma etching method in which a pulse magnetic field of T or more is applied to stabilize and process the plasma MHD. The present invention also provides, in the ECR plasma etching method, a pulse magnetic field of 0.08 T or more in parallel with the direction of propagation of microwaves, and a pulse width of 0.01 in the direction perpendicular to the direction of microwave propagation with respect to the ion source. ~ 500m
a pulse current of s is applied to the coil to give a pulse magnetic field,
This is an ECR plasma etching method for stabilizing and processing plasma MHD. That is, by applying a pulse magnetic field of 0.08 T or more parallel to the traveling direction of the microwave, a magnetic field exceeding 0.0875 T, which is a conventional constant magnetic field on average, is generated at the moment of the pulse on-time, so that electrons, ions The turning curvature and speed of the sample become small, the direction becomes straight, the effect of anisotropic treatment becomes large, and the sample does not wrap around to the back surface, and accurate processing can be performed. Moreover, the ion temperature could be lowered by applying a pulse magnetic field of 0.08 T or more to the ion source in the direction perpendicular to the traveling direction of the microwave. As a result, accurate etching processing can be performed at high speed. Further, by enlarging the pulse width of the parallel pulse magnetic field, the number of ions wrapping around increases and the side surface etching can be performed efficiently.

[0007]

Embodiments will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 is a material to be processed, 2
Is a coil for generating a pulse magnetic field parallel to the traveling direction of the microwave, 3 is a coil for generating a pulse magnetic field perpendicular to the traveling direction of the microwave in the ion source, 4 is a yoke,
Reference numeral 5 is an ion source, and 6 is a traveling direction of a microwave of 2.45 GHz. Reference numeral 7 is a reaction gas inlet, and 8 is an exhaust system. DC200-1000V as ion extraction power source
give.

Next, a specific processing example will be described. For example, when polycrystalline Si is used as a material to be processed, CF ₄ + O ₂ is flown as an etching gas to generate high-ionization plasma in an atmosphere of 0.05 Torr, so that the average magnetic field is 0.0875 T in the traveling direction of microwaves. A pulsed magnetic field was applied. Further, as a confining magnetic field for lowering the ion concentration, an average magnetic field of 0.0875 or more and 0.1 is applied to the coil 3.
A magnetic field of 2T was applied. As a result, 0.86 μm / min
It was possible to carry out high speed etching. Conventional method 4
The etching rate more than doubled was obtained, and it was 0.1 ° with respect to the conventional wrap angle of 15 °, and extremely excellent anisotropy was obtained. The pulse width conditions at this time and the results are shown in Tables 1 to 4. Further, as a work material, Si ₃ N ₄ , SiO ₂ , Al ₂ O
_{When 3} was also processed, it was found that the pulsed magnetic field could lower the ion temperature and anisotropic etching. These are also shown in Table 1. In addition,
As shown in FIG. 3, the wrap-around angle indicates a dent angle θ due to etching on the side surface of the sample.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

According to the present invention, the plasma confinement becomes efficient by variously changing τ _ON of the pulse magnetic field,
In addition, the ion temperature is lowered, and anisotropic etching can be performed by the parallel pulse magnetic field. Also with respect to the processing accuracy of VLSI, highly anisotropic and low damage etching processing can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus for carrying out the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is an explanatory diagram of a turning angle θ.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Kazuo Oba 4-chome 2-3, Matsuba-cho, Higashimurayama, Saitama (72) Inventor Yoshinori Shima 768, Ozenji, Aso-ku, Kawasaki-shi, Kanagawa 15 (72) Inventor Oba Chapter 3-205, 1-9 Hamasaki, Asagiri, Saitama Prefecture

Claims (2)

[Claims] 1. In an ECR plasma etching method using an electron cyclotron resonance (ECR) phenomenon, a pulse magnetic field of 0.08 T or more is applied in parallel with the traveling direction of microwaves, and the microwaves propagate toward an ion source. An ECR plasma etching method, characterized in that a plasma magnetic field (HD) is stabilized by applying a pulse magnetic field of 0.08 T or more in a direction perpendicular to the direction. 2. In the ECR plasma etching processing method, a pulse magnetic field of 0.08 T or more is applied in parallel with the traveling direction of microwaves, and the pulse width is 0.01 in the direction perpendicular to the traveling direction of microwaves with respect to the ion source. ~ 500 ms
The ECR plasma etching method, wherein the pulse current is applied to the coil to give a pulse magnetic field to stabilize the plasma MHD for processing.