# US 5,345,145 A · Method and apparatus for generating highly dense uniform plasma in a high frequency electric field > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,345,145 A - Document ID: US5345145A - Status: Granted - Kind: A - Application number: 08/039,911 - Filed: 1993-03-30 - Granted: 1994-09-06 - Earliest claimed: 1992-03-31 - Assignees: Matsushita Electric Industrial Co., Ltd. - Inventors: Kenji Harafuji; Mitsuhiro Ohkuni; Tokuhiko Tamaki; Masafumi Kubota; Noboru Nomura - Web page: https://patentgrep.com/patent/US5345145A ## CPC - H01J 37/32623: {Mechanical discharge control means} - H01J 37/32165: {Plural frequencies} - H01J 37/3266: {Magnetic control means} - H05H 1/46: using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS ## Abstract A plasma generating method comprises: a first step of disposing a plurality of lateral electrodes at lateral sides of a plasma generating part in a vacuum chamber; a second step of respectively applying, to the lateral electrodes, high frequency electric powers of which frequencies are the same as one another and of which phases are different from one another, thereby to excite, in the plasma generating part, a high frequency rotating electric field to cause electrons under translational motions in the plasma generating part to present oscillating or rotating motions; and a third step of applying, to the plasma generating part, a magnetic field substantially at a right angle to the working plane of the high frequency rotating electric field, thereby to convert the translational movement of the electrons in the plasma generating part into revolving motions under oscillating or rotating motions by which the electrons revolve in the plasma generating part. The high frequency rotating electric field and the magnetic field cause the electrons in the plasma generating part to be confined therein. ## Claims ### Claim 1 A plasma generating method comprising: a first step of disposing three of more lateral electrodes at lateral sides of a plasma generating part in a vacuum chamber; a second step of respectively applying, to said lateral electrodes, high frequency electric powers of which frequencies are the same as one another and of which phases are different from one another, thereby to excite, in said plasma generating part, a high frequency rotating electric field to cause electrons under translational motions in said plasma generating part to present rotating motions with translational movement component; and a third step of applying, to said plasma generating part, a magnetic field substantially at a right angle to the working plane of said high frequency rotating electric field, thereby to convert said translational movement of said electrons under rotating motions in said plasma generating part into revolving movement by which said electrons revolve in said plasma generating part; said electrons in said plasma generating part being confined therein. ### Claim 2 (depends on 1) A plasma generating method according to claim 1, wherein the third step comprises a step of applying, to said plasma generating part, a magnetic field substantially at a right angle to the working plane of said high frequency rotating electric field, thereby to convert said translational movement of said electrons under rotating motions in said plasma generating part into revolving movement by which said electrons revolve in said plasma generating part in a direction identical with or reverse to the direction of said rotational motions. ### Claim 3 (depends on 1) A plasma generating method according to claim 1, wherein the magnetic field at the third step is steady with the passage of time. ### Claim 4 (depends on 1) A plasma generating method according to claim 1, wherein the magnetic field at the third step is unsteady with the passage of time. ### Claim 5 (depends on 1) A plasma generating method according to claim 1, wherein the high frequency electric powers at the second step are greater than 1 MHz, and the absolute value of the intensity of the magnetic field at the third step is greater than 2 G. ### Claim 6 (depends on 1) A plasma generating method according to claim 1, wherein the following relationship is established among the frequency f (MHz) of the high frequency electric powers at the second step, the intensity E (V/cm) of the rotational electric field excited by said high frequency electric powers and the absolute value B (G) of the intensity of the magnetic field at the third step: 1<E/B f<50 ### Claim 7 (depends on 1) A plasma generating method according to claim 1, wherein the intensity of the magnetic field at the third step is greater at the periphery of the plasma generating part than at the center thereof. ### Claim 8 (depends on 1) A plasma generating method according to claim 1, wherein the wall of the vacuum chamber is made of a nonmagnetic material. ### Claim 9 (depends on 1) A plasma generating method according to claim 1, wherein the wall of the vacuum chamber is magnetically shielded. ### Claim 10 A plasma generating apparatus comprising: three or more lateral electrodes disposed at lateral sides of a plasma generating part in a vacuum chamber; high frequency electric power applying means for applying, to said lateral electrodes, respective high frequency electric powers of which frequencies are the same as one another and of which phases are different from one another, thereby to excite, in said plasma generating part, a high frequency rotating electric field to cause electrons under translational motions in said plasma generating part to present rotating motions; and magnetic field applying means for applying a magnetic field substantially at a right angle to the working plane of said high frequency rotating electric field, thereby to convert said translational movement of said electrons under rotating motions in said plasma generating part into revolving movement by which said electrons revolve in said plasma generating part such that said electrons in said plasma generating part are confined therein. ### Claim 11 (depends on 10) A plasma generating apparatus according to claim 10, further comprising: a sample stage disposed at a lower part of the plasma generating part inside of the vacuum chamber; and an opposite electrode disposed at an upper part of said plasma generating part inside of said vacuum chamber. ### Claim 12 (depends on 11) A plasma generating apparatus according to claim 11, wherein a bias voltage is applied to the sample stage for irradiating a plasma to a sample to be placed on said sample stage. ### Claim 13 (depends on 11) A plasma generating apparatus according to claim 11, further comprising temperature control means for controlling the temperature of the sample stage such that a plasma is irradiated to a sample to be placed on said sample stage. ### Claim 14 (depends on 10) A plasma generating apparatus according to claim 10, wherein the magnetic field applying means has a pair of upper and lower coils so disposed as to be vertically opposite to each other, and power supplies for respectively applying electric currents to said pair of coils. ### Claim 15 (depends on 14) A plasma generating apparatus according to claim 14, wherein the power supplies have means for applying, to the pair of coils, electric currents which are steady with the passage of time. ### Claim 16 (depends on 14) A plasma generating apparatus according to claim 14, wherein the power supplies have means for applying, to the pair of coils, electric currents which are unsteady with the passage of time. ### Claim 17 (depends on 10) A plasma generating apparatus according to claim 10, wherein the three or more lateral electrodes and the magnetic field applying means are disposed outside of the vacuum chamber. ### Claim 18 (depends on 10) A plasma generating apparatus according to claim 10, wherein members made of quartz or ceramics are disposed between the plasma generating part and each of the lateral electrodes, and between said plasma generating part and the magnetic field applying means. ### Claim 19 (depends on 10) A plasma generating apparatus according to claim 10, wherein the high frequency electric power applying means has phase locking means arranged such that the differences in phase among the high frequency electric powers respectively applied to the lateral electrodes are the same as each other. ### Claim 20 (depends on 10) A plasma generating apparatus according to claim 10, wherein the high frequency electric power applying means has means for respectively applying, to the lateral electrodes, three or more high frequency electric powers which are supplied from the same power supply and of which phases are different from one another. ### Claim 21 (depends on 10) A plasma generating apparatus according to claim 10, wherein the wall of the vacuum chamber is made of a nonmagnetic material. ### Claim 22 (depends on 10) A plasma generating apparatus according to claim 10, wherein the wall of the vacuum chamber is magnetically shielded.