Method and apparatus for obtaining particle beams the density of which is spatially modulated, application to etching and to ion implantation

Claim 2

Process for obtaining beams of particles of spatially modulated density, characterized in that it consists in: causing the particles of a primary beam (3, 56) of particles to pass to a first energy state E 1' in such a manner as to form a beam of particles situated in the said first energy state E 1' selectively causing the particles situated in the said first energy state E 1 to pass to a second energy state E 2 by a means of a luminous flux (7, 40, 72) which is of spatially modulated intensity and which is directed onto the beam of particles situated in the said first energy state E" and separating the particles situated in the said second energy state E 2 from the particles situated in the said first energy state E, in such a manner as to obtain a beam formed of the particles situated in the said first energy state E, and a beam formed of the particles situated in the said second energy state E 2 , these beams being distinct and of spatially modulated density, in that one of the said first and second energy states E, and E 2 is an energy state of long lifetime, and in that the other energy state is an ionized state, the state of ionization of which differs from that of the energy state of long lifetime.

Claim 3

Process according to claim 1, characterized in that said energy state of long lifetime is a metastable excited state.

Claim 4

Process according to claim 2, characterized in that the particles of the primary beam (3, 56) are electrically neutral and in their fundamental state, and in that these particles are caused to pass to the said metastable excited state, from their fundamental state, by electron bombardment, the said first energy state E, being constituted by the said metastable excited state and the said energy state E 2 then being the said ionized state.

Claim 5

Process according to claim 2, characterized in that the particles of the primary beam (3, 56) are electrically charged, and in that these particles are caused to pass to the said metastable excited state by electron bombardment, after having neutralized the particles of the primary beam (3, 56) by exchange of charges in a gas of particles of the same type, the said first energy state E, being constituted by the said metastable excited state and the said second energy state E2 then being the said ionized state.

Claim 6

Process according to any one of claims 1 to 4, characterized in that the said ionized state is the state of first ionization.

Claim 7

Process according to any one of claims 1 to 5, characterized in that the particles situated in the said ionized state are separated from the particles situated in the said energy state of long lifetime by means of at least one of the fields included in the group comprising the electric fields and the magnetic fields.

Claim 8

Process according to any one of claims 1 to 6, characterized in that the intensity of the luminous flux (7, 40, 72) is spatially modulated by passage of the said luminous flux through a mask (8,41, 73).

Claim 9

Process according to any one of claims 1 to 6, characterized in that the spatial modulation of intensity of the luminous flux is obtained by a method based on the wave nature of the light.

Claim 10

Process according to claim 8, characterized in that the luminous flux of modulated intensity is obtained by directing towards the axis of the beam of particles situated in the said first energy state E, two beams of coherent light which have emerged from the same primary luminous beam, this taking place in a symmetrical manner in relation to the axis of the beam of particles situated in the said first energy state E l , in such a manner as thus to obtain alternately bright and dark zones parallel to the axis of the beam of particles situated in the said first energy state E l .

Claim 11

Process according to any one of claims 1 to 9, characterized in that the said particles are atoms of at least one rare gas.

Claim 12

Device for obtaining beams of particles of spatially modulated density, characterized in that it comprises: means (2, 55) for producing a primary beam (3, 56) of particles, means for causing the particles of this primary beam to pass into a first energy state E, in such a manner as to form a beam (5, 36, 69) of particles situated in the said first energy state E l , means (6 or 38, 39 or 70, 71) for producing a luminous flux (7,40, 72) composed of photons capable of causing the particles situated in the said first energy state E 1 to pass into a second energy state E 2 and for directing this luminous flux (7,40, 72) onto the beam of particles situated in the first energy state E 1 , means (8, 41, 73) for spatial modulation of the intensity of the said luminous flux, the said means being interposed between the means for producing and directing this luminous flux and the beam of particles situated in the first energy state E 1 in such a manner as selectively to cause the particles situated in the first energy state E 1 to pass into the second energy state E 2 and means (9 or 43, 44 or 75) for separation of the particles situated in the second energy state E 2 from the particles situated in the first energy state E 1 , in such a manner as to obtain a beam (21, 45, 79) formed of the particles situated in the first energy state E 1 and a beam (22, 49, 81) formed of the particles situated in the second energy state E 2 , these beams being distinct and of spatially modulated density, one of the first and second energy states E 1 and E 2 being an energy state of long lifetime and the other energy state being an ionized state, the state of ionization of which differs from that of the energy state of long lifetime.

Claim 13

Device for obtaining beams of particles of spatially modulated density, characterized in that it comprises: means (2, 55) for producing a primary beam (3, 56) of particles, means for causing the particles of this primary beam to pass into a first energy state E, in such a manner as to form a beam (5, 36, 69) of particles situated in the said first energy state E l , means (6 or 38, 39 or 70, 71) for producing a luminous flux (7,40, 72) composed of photons capable of causing the particles situated in the said first energy state E 1 to pass into a second energy state E 2 and for directing this luminous flux (7,40, 72) onto the beam of particles situated in the first energy state E 1 , means (8, 41, 73) for spatial modulation of the intensity of the said luminous flux, the said means being interposed between the means for producing and directing this luminous flux and the beam of particles situated in the first energy state E 1 in such a manner as selectively to cause the particles situated in the first energy state E 1 to pass into the second energy state E 2 and means (9 or 43, 44 or 75) for separation of the particles situated in the second energy state E 2 from the particles situated in the first energy state E 1 , in such a manner as to obtain a beam (21, 45, 79) formed of the particles situated in the first energy state E 1 and a beam (22, 49, 81) formed of the particles situated in the second energy state E 2 , these beams being distinct and of spatially modulated density, one of the first and second energy states E 1 and E 2 being an energy state of long lifetime and the other energy state being an ionized state, the state of ionization of which differs from that of the energy state of long lifetime.

Claim 14

Device according to claim 11, comprising: means (2, 55) for producing a primary beam (3, 56) of particles means for causing the particles of this primary beam (3, 56) to pass into an energy state of long lifetime, in such a manner as to form a beam (5, 36, 69) of particles situated in the said energy state of long lifetime, means (6 or 38, 39 or 70, 71) for producing a luminous flux (7,40, 72) composed of photons capable of ionizing the particles situated in the said energy state of long lifetime, and for directing this luminous flux (7, 40, 72) onto the said beam (5, 36, 69) of particles situated in the said energy state of long lifetime, means (8, 41, 73) for spatial modulation of the intensity of the said luminous flux (7, 40, 72), the said means being interposed between the means (6 or 38, 39 or 70, 71) for producing and directing this luminous flux and the beam (5, 36, 69) of particles situated in the said energy state of long lifetime, in such a manner as to cause the particles situated in the said energy state of long lifetime to pass selectively into an ionized state, and means (9 or 43, 44 or 75) for separation of the particles situated in the said ionized state from the particles remaining in the said energy state of long lifetime, in such a manner as to obtain a beam (21, 45, 79) formed of the particles situated in the said ionized state and a beam (22, 46, 81) formed of the particles remaining in the said energy state of long lifetime, these beams being distinct and of spatially modulated density, the ionized state having a state of ionization different from that of the energy state of long lifetime.

Claim 15

Device according to claim 12, characterized in that the said luminous flux (7) is constituted by at least one luminous beam which is directed towards the beam (5) of particles situated in the said energy state of long lifetime, transversely thereto.

Claim 16

Device according to claim 12, characterized in that the luminous flux (40) is a luminous beam, in that the latter and the beam (36) of particles situated in the said energy state of long lifetime are collinear and have opposite directions of propagation, and in that the device further comprises successively means for ionization (48), means for acceleration (49) and means for deviation (50) of the beam (46) of the particles remaining in the said energy state of long lifetime.

Claim 17

Device according to claim 12, characterized in that the luminous flux is a luminous beam, in that the beam (69) of particles situated in the said energy state of long lifetime and the luminous beam (72) are provided to propagate according to the same direction and in opposite senses, in that the beam (69) of particles situated in the said energy state of long lifetime is made convergent according to an angle a, in that the luminous beam (72) is made divergent according to the same angle a and, moreover, provided to be coincident with the beam (69) of particles situated in the said energy state of long lifetime, and in that the means (75) for separation consist in means for deviation of the particles situated in the said ionized state.

Claim 18

Device according to claim 15, characterized in that the means (73) for spatial modulation of the intensity of the luminous beam consist in a mask provided with patterns, the size of which is provided in order that these patterns should give rise to only a slight luminous diffraction.

Claim 19

Application of the process according to any one of claims 1 to 10 to ion implantation and engraving.