Method and apparatus for microwave plasma anisotropic dry etching
First Claim
1. A microwave plasma etching apparatus comprising:
- a vacuum vessel, filled with a gas having a predetermined pressure, includinga plasma generating chamber,a reaction chamber,a connecting chamber for connecting said plasma generating chamber and said reaction chamber, the connecting chamber having an axis, andmeans, positioned in the reaction chamber, for holding a workpiece at a position in line with the axis of the connecting chamber and electrically isolating the workpiece;
means for applying microwave power of a predetermined frequency to the plama generating chamber for generating therein a plasma, the plasma including ions, electrons and free radicals; and
means for generating a magnetic field having a cyclotron resonance point in the plasma generating chamber for causing a cyclotron resonance of electrons in the plasma corresonding to the predetermined frequency of the microwave power, and having a peak point between said cyclotron resonance point and said workpiece at which said magnetic field intensity has a maximum value and functions as a magnetic mirror for reflecting the electrons in the plasma while allowing the free radicals and ions to pass the magnetic mirror along the axis of the connecting chamber to impinge on the workpiece, thereby to perform substantially anisotropic plasma etching of the workpiece.
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Abstract
A microwave plasma etching method and apparatus for performing substantially anisotropic etching to form micropatterns on IC substrates. A microwave power source creates a plasma from a gas with a relatively low pressure such as 10-3 to 10-4 Torr, so that the mean free path of the gas molecules exceeds the dimensions of the etching apparatus. A magnetic field is generated in a plasma generating chamber, a reaction chamber where in the substrate is mounted and a connecting chamber. The plasma discharge is enhanced by a cyclotron resonance magnetic field intensity corresponding to the frequency of the microwave power applied to the plasma chamber. The magnetic field creates a magnetic mirror which prevents the electrons in the plasma from entering into the reaction chamber so as to eliminate the generation of free radicals in which the reaction chamber which adversely affect the anisotropic etching ability.
107 Citations
24 Claims
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1. A microwave plasma etching apparatus comprising:
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a vacuum vessel, filled with a gas having a predetermined pressure, including a plasma generating chamber, a reaction chamber, a connecting chamber for connecting said plasma generating chamber and said reaction chamber, the connecting chamber having an axis, and means, positioned in the reaction chamber, for holding a workpiece at a position in line with the axis of the connecting chamber and electrically isolating the workpiece; means for applying microwave power of a predetermined frequency to the plama generating chamber for generating therein a plasma, the plasma including ions, electrons and free radicals; and means for generating a magnetic field having a cyclotron resonance point in the plasma generating chamber for causing a cyclotron resonance of electrons in the plasma corresonding to the predetermined frequency of the microwave power, and having a peak point between said cyclotron resonance point and said workpiece at which said magnetic field intensity has a maximum value and functions as a magnetic mirror for reflecting the electrons in the plasma while allowing the free radicals and ions to pass the magnetic mirror along the axis of the connecting chamber to impinge on the workpiece, thereby to perform substantially anisotropic plasma etching of the workpiece. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A microwave plasma etching apparatus, comprising:
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a plasma generating chamber filled to a predetermined pressure with an ionizable gas; means for applying microwave power to the plasma generating chamber to create a plasma in the ionizable gas, the plasma including ions, free radicals and electrons; a reaction chamber; connecting chamber means having an axis and connecting the plasma generating chamber and the reaction chamber for collimating ions and free radicals passing from the plasma generating chamber to the reaction chamber; means, positioned in the reaction chamber, for holding a workpiece at a predetermined position in line with the axis of the connecting chamber and electrically isolating the workpiece; and means for generating a magnetic field having a peak magnetic field intensity point at which the magnetic field functions as a magnetic mirror for containing electrons in the plasma in the plasma generating chamber, and having a cyclotron resonance point in the plasma generating chamber for imparting a cyclotron motion to the electrons in the plasma generating chamber. - View Dependent Claims (15, 16, 17)
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18. A method of anisotorpic plasma etching in a microwave plasma etching apparatus incuding a vacuum vessel having a plasma generating chamber, a reaction chamber, and a connecting chamber connecting the plasma generating chamber and the connecting chamber, the connecting chamber having an axis, comprising the steps of:
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(a) evacuating the vacuum vessel and back-filling the vacuum vessel with an ionizable gas; (b) applying microwave energy to the plasma generating chamber to generate a plasma; and (c) generating a magnetic field having a cyclotron resonance point in the plasma generating chamber for causing a cyclotron resonance of electrons in the plasma corresonding to the predetermined frequency of the microwave power, and having a peak point in the connecting chamber at which said magnetic field intensity has a maximum value and functions as a magnetic mirror for reflecting the electrons in the plasma while allowing the free radicals and ions to pass the magnetic mirror along the axis of the connecting chamber to impinge on the workpiece, thereby to perform substantially anisotropic plasma etching of the workpiece. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification