Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
  • B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
  • B23K26/0648—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising lenses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
  • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
  • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/50—Working by transmitting the laser beam through or within the workpiece
  • B23K26/57—Working by transmitting the laser beam through or within the workpiece the laser beam entering a face of the workpiece from which it is transmitted through the workpiece material to work on a different workpiece face, e.g. for effecting removal, fusion splicing, modifying or reforming
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B3/00—Simple or compound lenses
  • G02B3/02—Simple or compound lenses with non-spherical faces
  • G02B3/04—Simple or compound lenses with non-spherical faces with continuous faces that are rotationally symmetrical but deviate from a true sphere, e.g. so called "aspheric" lenses
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
  • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2101/00—Articles made by soldering, welding or cutting
  • B23K2101/36—Electric or electronic devices
  • B23K2101/40—Semiconductor devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
  • B23K2103/56—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26 semiconducting
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
  • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
  • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
  • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
  • H01L2221/68381—Details of chemical or physical process used for separating the auxiliary support from a device or wafer

Definitions

• TITLE Laser treatment system and method
• the present description relates generally to the systems and methods for laser treatment of an object comprising a semiconductor substrate.
• One drawback is that silicon does not substantially transmit electromagnetic radiation, the wavelength of which is less than 1100 nm, which prevents the use of infrared lasers which are the most widely used on the market. Further, even using a laser at a wavelength at which the silicon is substantially transparent, it may be difficult to focus the laser beam effectively on the region to be removed, especially due to non-linear interactions between the laser and silicon. Furthermore, it may be difficult to prevent deterioration of regions neighboring the region to be treated.
• an object of one embodiment is to at least partially overcome the drawbacks of the systems and methods for laser treatment of an object comprising a semiconductor substrate described above.
• An object of an embodiment is that the laser beam is focused on the region to be treated through the semiconductor substrate.
• Another object of an embodiment is that the regions of the object neighboring the region to be treated are not damaged by the treatment.
• One embodiment provides a system configured for processing a region of an object adjacent to a substrate, the system comprising:
• a source of an incident laser beam configured to provide a focused laser beam, said configuration being such that the wavelength of the incident laser beam is greater than the sum of 500 nm and the wavelength associated with the band deviation of the material composing the substrate and less than the sum of 2500 nm and the wavelength associated with the band deviation of the material composing the substrate;
• an optical device associating a numerical aperture greater than 0.3 and means for correcting spherical aberrations appearing when passing through the substrate for a given thickness of the substrate and a given distance between the substrate and the optical device
• said treatment being carried out on said region adjacent to the substrate and opposite to the optical device, either through said substrate, and comprising the physical, chemical or physico-chemical modification or the ablation of said region.
• the material making up the substrate is a semiconductor.
• the source is adapted to supply at least one pulse of the incident laser beam, the duration of said at least one pulse being between 0.1 ps and 1000 ps.
• the source is adapted to supply said at least one pulse of the incident laser beam with a peak power of between 300 kW and 100 MW.
• the optical device comprises at least one aspherical lens.
• An embodiment also provides a method of treating a region of an object further comprising a substrate adjacent to the region to be treated comprising the exposure of the region to be treated to the focused laser beam supplied by the system such as defined above through the substrate.
• the substrate is a semiconductor.
• the method comprises supplying at least one pulse of the incident laser beam, the duration of said at least one pulse being between 0.1 ps and 1000 ps.
• the method comprises providing said at least one pulse with a peak power of between 300 kW and 100 MW.
• the substrate comprises a face oriented towards the side of the system, the method comprising the formation of an antireflection layer on said face.
• the substrate is made of silicon, germanium, or a mixture or alloy of at least two of these compounds.
• the object comprises a dielectric layer covering the substrate, the region to be treated being interposed between the substrate and the dielectric layer.
• the object comprises at least one electronic circuit covering the substrate, the region to be treated being interposed between the substrate and the electronic circuit.
• the method comprises destroying the region of interest by the focused laser beam.
• FIG. 1 illustrates an embodiment of a system for processing a laser object
• FIG. 2 represents a converging lens exhibiting spherical aberrations
• Figure 3 is a sectional view, partial and schematic, of an embodiment of the optical device of the processing system shown in Figure 1;
• FIG. 4 represents a curve of the evolution of the irradiance of the laser beam supplied by the processing system shown in FIG. 1 as a function of the distance of the laser beam relative to the focal plane of the optical device of the processing system;
• FIG. 5 represents an evolution curve of the diameter of the laser beam supplied by the processing system shown in FIG. 1 as a function of the distance of the beam laser relative to the focal plane of the optical device of the treatment system.
• Figure 1 is a sectional view, partial and schematic, of an embodiment of a processing system 10 of an object 20.
• the processing system 10 comprises a laser source 12 and an optical focusing device 14 having an optical axis D.
• the source 12 is adapted to provide an incident laser beam 16 to the collimation device 14 which provides a converging laser beam 18 .
• the optical device of focusing 14 may comprise an optical component, two optical components or more than two optical components, an optical component corresponding for example to a lens.
• the incident laser beam 16 is substantially collimated along the optical axis D of the optical device 14.
• the object 20 comprises a substrate 22 made of a semiconductor material.
• the semiconductor material can be silicon, germanium or a mixture of at least two of these compounds.
• the substrate 22 is made of silicon, more preferably of monocrystalline silicon.
• the semiconductor substrate 22 comprises two opposite faces 24, 26, the laser beam 18 penetrating into the substrate 22 through the face 24.
• the faces 24 and 26 are parallel.
• the faces 24 and 26 are flat.
• the thickness of the substrate 22 is between 50 ⁇ m and 3 mm.
• an antireflection layer is provided on the front face 24 of the substrate 22.
• the substrate 22 may be, at least in part, of a non-semiconducting material, for example a electrically insulating material or an electrically conductive material.
• the object 20 comprises a region to be treated 28 at the level of the second face 26 and which is the region to be treated 28 to be treated.
• the substrate 22 is not covered with another element on the side of the face 26 and the region to be treated 28 corresponds to the face 26 of the substrate 22.
• the region to be treated 28 corresponds to a layer covering the face 26.
• the layer to be treated 28 can be made of a material different from the substrate 22.
• the layer to be treated 28 can be of the same material as the substrate 22 and then correspond to a portion of the substrate 22.
• an additional zone 30 covering the layer to be treated 28 on the side of the layer to be treated 28 opposite the substrate 22.
• the element 30 may comprise a layer in a material different from the substrate 22 and from the layer to be treated 28.
• the layer 30 can be of the same material as the substrate 22 or of the same material as the layer to be treated 28.
• the layer 30 is made of a dielectric material, for example silicon oxide or silicon nitride.
• Element 30 may further comprise electronic circuits, for example light-emitting diode circuits or transistor circuits, in particular MOS transistors.
• the treatment corresponds to the ablation of the layer to be treated 28 so as to allow the detachment of the element 30 relative to the substrate 22.
• the treatment corresponds to the texturing of the face 26.
• the treatment corresponds to an input of energy into the region to be treated 28, for example to cause a chemical reaction or a physical phenomenon.
• the wavelength of the laser beam 18 supplied by the processing system 10 is greater than the wavelength corresponding to the band gap (bandgap) of the material making up the substrate 22, preferably at least 500 nm, more preferably at least 700 nm. This advantageously makes it possible to reduce the interactions between the laser beam 18 and the substrate 22 when the substrate 22 passes through the laser beam 18.
• the wavelength of the laser beam 18 supplied by the system treatment 10 is not greater than the wavelength corresponding to the deviation of bands (bandgap) of the material making up the substrate 22, preferably over 2500 nm. This advantageously makes it possible to more easily provide a laser beam forming a laser spot of small dimensions.
• the wavelength of the laser beam 18 is chosen equal to about 2 ⁇ m.
• a source 20 providing a laser beam is for example sold by the company Novae under the name BrevityHP.
• the wavelength of the laser beam 18 is chosen equal to approximately 2 pm or 2.35 pm.
• the laser beam 18 is polarized. According to one embodiment, the laser beam 18 is polarized according to a rectilinear polarization. This advantageously makes it possible to improve the interactions of the laser beam 28 with the region to be treated 28. According to another embodiment, the laser beam 18 is polarized according to a circular polarization. This advantageously makes it possible to promote the propagation of the laser beam 18 in the substrate 22.
• the laser beam 18 is emitted by the processing system 10 in the form of a pulse, two pulses or more than two pulses, each pulse having a duration between 0.1 ps and 1000 ps.
• the peak laser beam power for each pulse is between 300 kW and 100 MW.
• the fact of using pulses longer than pulses of durations strictly less than 100 femtoseconds makes it possible to reduce the peak power of the laser beam 18 and therefore to reduce the non-linear interactions of the laser beam 18 with the substrate 22.
• the fact of using pulses shorter than nanosecond pulses makes it possible to avoid an undesirable heating outside the region to be treated 28 which could lead to deterioration of the layers adjacent to the region to be treated 28.
• the digital image aperture of the optical device 14 is greater than 0.2, preferably greater than 0.6, more preferably greater than 0.7.
• the digital image aperture is equal to the product nosin (io) where no is the refractive index at the wavelength of the medium traversed by the laser beam at the output of the optical device 14, for example air and io is the angle between the optical axis D of the optical device 14 and the ray of the laser beam 18 which leaves the optical device 14 furthest from the optical axis D.
• the optical device 14 compensates for the optical aberrations due to the crossing of the substrate 22 by the laser beam 18.
• the optical device 14 compensates for the spherical aberrations due to the crossing of the substrate 22 by the laser beam 18.
• the optical aberrations, apart from defocusing, due to the crossing of the substrate 22 by the laser beam 18 correspond only to the aberrations spherical.
• the optical aberrations, apart from defocusing, due to the crossing of the substrate 22 by the laser beam 18 correspond to spherical aberrations and to other aberrations, including coma or astigmatism.
• Figure 2 illustrates the principle of spherical aberrations and is a sectional view, partial and schematic, of a lens 50 receiving a light beam 52 whose rays are parallel to the optical axis D 'of the lens 50 and providing a converging light beam 54.
• the incident light rays 52 do not converge at the same focal point.
• the focal points are close and can be considered as forming a single focal point F1.
• the optical device 14 is determined to be aspherical in the presence of the substrate 22, for a given thickness of the substrate 22 and for a given distance between the substrate 22 and the optical device 14.
• the optical device 14 comprises several optical components, for example several lenses
• the curvature of each input face and of each output face of each optical component is determined so that all the light rays of the beam 18 supplied focus substantially at a single focal point F in the region of interest. These curvatures can be determined by numerical simulation.
• FIG. 3 represents an embodiment of the optical device 14 in which the optical device 14 comprises an aspherical lens 60 receiving an incident beam 62, the rays of which are parallel to the optical axis of the lens 60, and providing a converging light beam 64.
• the lens 60 includes an entrance face 66 and an exit face 68.
• the exit face 68 is planar and the entrance face 66 is curved. The curvature of the entry face 66 is determined so that all the light rays of the incident light beam 62 converge at the same focal point F.
• the determination of the curvature of the entry face 66 is carried out taking into account that the converging beam 64 successively passes through a zone 70 of air, in which a more or less significant vacuum can be created or in which a controlled gas atmosphere, for example a nitrogen atmosphere, can be provided, and the substrate 22.
• a zone 70 of air in which a more or less significant vacuum can be created or in which a controlled gas atmosphere, for example a nitrogen atmosphere, can be provided, and the substrate 22.
• the focal point F is fixed on the surface 26 of the substrate 22 which corresponds to the region to be treated 28.
• the focal point F can be fixed in the middle of the layer to be treated. process 28 when it is present Consequently, the curvature of the input face 66 making it possible to eliminate the spherical aberration is determined for a given thickness of the substrate 22 and a given relative position between the substrate 22 and the optical device 14.
• the distance between the face 68 of the optical device 15 and the face 24 of the substrate 22 is between 0.5 mm and 20 cm
• the use of a large numerical aperture of the optical device 14 makes it possible to ensure that the energy density of the laser beam is high only at the level of the focal point.
• the portion of the substrate 22 crossed by the laser beam 18 and in which the energy density of the laser beam is high is therefore reduced.
• This also advantageously makes it possible to limit the nonlinear interactions of the laser beam 18 with the substrate 22 outside the region to be treated 28. Indeed, the nonlinear interactions of the laser beam 18 with the substrate 22 are of all the more important as the local energy density of the laser beam 18 is high.
• the use of an aspherical optical device 14 makes it possible to obtain a suitable focusing of the laser beam 18 despite the large numerical aperture of the optical device 14.
• the laser beam 18 can cause the formation of a plasma in the region to be treated 28.
• the formation of a plasma causes a significant increase in the local absorption of the laser beam in the region of interest. .
• FIG. 4 represents an evolution curve of the illumination I of the laser beam, expressed in arbitrary units (au) and measured in a plane parallel to the focal plane, as a function of the distance d of the measurement plane with respect to to the focal plane
• FIG. 5 represents an evolution curve of the diameter 0 of the laser beam, measured in a plane parallel to the focal plane, as a function of the distance d of the measurement plane with respect to the focal plane.
• the curves shown in Figures 5 and 6 were obtained by simulation using an aspherical optical device 14 having a numerical aperture equal to 0.72.
• object 20 included a silicon substrate 22, which corresponds to the negative d distances in Figures 4 and 5, and a layer 30 of silicon dioxide, which corresponds to the positive d distances in Figures 4 and 5. 5.
• the focal plane therefore corresponds to a distance d equal to zero.
• the diameter of the laser beam 18 in the focal plane is less than 2 ⁇ m, in Due to diffraction, and when moving 5 mpi away from the focal plane in the silicon oxide layer 30, the diameter of the laser beam is 6.5 ⁇ m. This means that a good focusing of the laser beam 18 is obtained in the focal plane and a strong divergence of the laser beam 18 is obtained downstream of the focal plane.
• the illumination decreases by a factor of about 15 when moving 5 ⁇ m away from the focal plane in the silicon oxide layer 30.
• the diameter of the laser spot is about 1.7 ⁇ m and
• the diameter of the laser beam is about 6.5 ⁇ m. This further means that the fluence of the light beam at 5 ⁇ m past the focal plane in silicon dioxide is substantially equal to 7% of the fluence of the laser beam in the focal plane.
• the region to be treated 28 corresponds to a layer interposed between the substrate 22 and the dielectric layer 30 of negligible thickness which has a transmission of the order of 40% in linear mode. The transmission can be much lower in the case where the laser beam causes the local formation of a plasma in the region to be treated 18. Further, considering the fact that
• the fluence of the light beam at 5 ⁇ m after the focal plane in the silicon dioxide is substantially equal to 2.4% of the fluence of the laser beam 18 in the focal plane. This means that any components formed on / in layer 30 may not be impacted by the treatment carried out by the treatment system 40.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
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• Condensed Matter Physics & Semiconductors (AREA)
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• 2019
  • 2019-07-31 FR FR1908743A patent/FR3099636B1/fr active Active
• 2020
  • 2020-07-21 EP EP20740344.5A patent/EP4003635A1/de active Pending
  • 2020-07-21 KR KR1020227005484A patent/KR20220038408A/ko active Search and Examination
  • 2020-07-21 US US17/630,876 patent/US20220266384A1/en active Pending
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