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
  • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
  • B23K26/1462—Nozzles; Features related to nozzles
  • B23K26/1464—Supply to, or discharge from, nozzles of media, e.g. gas, powder, wire
  • B23K26/1476—Features inside the nozzle for feeding the fluid stream through the nozzle
• • 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
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
• • 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
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/26—Bombardment with radiation
  • H01L21/263—Bombardment with radiation with high-energy radiation
  • H01L21/268—Bombardment with radiation with high-energy radiation using electromagnetic radiation, e.g. laser radiation
• • 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
  • H01L21/677—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 conveying, e.g. between different workstations
  • H01L21/67739—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 conveying, e.g. between different workstations into and out of processing chamber
• • 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
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
  • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual 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
  • B23K2101/00—Articles made by soldering, welding or cutting
  • B23K2101/36—Electric or electronic devices
  • B23K2101/40—Semiconductor devices

Definitions

• the present invention relates, in general, to a workpiece processing technique using a laser beam and, more particularly, to a workpiece processing apparatus and a processing method using a laser beam, which prevents a melt ejected from a workpiece from bonding with oxygen, thereby improving processing efficiency.
• a laser beam is focused onto the surface of a wafer to induce heating and a chemical reaction and to remove the portion of the wafer on which the laser beam is focused. That is to say, as the laser beam is applied to the wafer in a focused state, the portion of the wafer on which the laser beam is focused increases in temperature, and depending upon the focusability of the laser beam, melting and vaporization of the wafer material occur. As the wafer material is vaporized, the pressure increases, and the portion of the wafer onto which the laser beam is focused is removed in an explosive manner.
• FIG. 1 is a view explaining a conventional workpiece processing method using a laser beam and illustrating an example of processing a silicon wafer.
• ablation means a phenomenon which includes a phase change developed due to interaction of the laser beam 20 with the workpiece 10, evaporation of material, ejection of particles, interaction of the laser beam 20 with the vapor, generation of plasma, and so on.
• a melt ejection rate per unit laser beam area, j m can be expressed as in the following Equation 1, using a thermal diffusivity K, a boiling point Ti v , a melting point T sl , a melt molar mass M, a melt density of dense phase pa, a radius of laser beam w, and a difference ⁇ p between an ambient pressure and a melt pressure.
• silicon dioxide (SiO 2 ) is generated due to the reaction between a melt, produced from the silicon wafer, and oxygen. Thermal properties of silicon and silicon dioxide are given in Table 1.
• thermal diffusivity and the ratio of boiling point to melting point of silicon are greater than those of silicon dioxide, silicon in a melted state can be ejected out of a processing area more rapidly than silicon dioxide in a melted state.
• thermal expansion coefficient of silicon is four times larger than that of silicon dioxide. The difference in thermal expansion coefficients between these two materials can cause a crack in silicon wafer after processing.
• the melt of the workpiece is oxidized due to contact between the workpiece and oxygen, thereby increasing the viscosity of the melt and decreasing the melt ejection rate. Also, due to the difference in thermal expansion coefficients between the workpiece and the melt, a crack is likely to develop, deteriorating the reliability of processing.
• a die strength test is performed to determine to what level the die can withstand an external force such as a bending force, etc.
• the workpiece such as a silicon wafer
• the die is likely to be easily broken when performing a bending test.
• the melt oxidized during processing adheres to a processing area of the workpiece and thus causes a non-uniform thickness
• a concentrated stress is generated at an undulating portion of the workpiece, and thereby, the die is likely to be easily broken.
• an object of the present invention is to provide an oxygen blocking device which prevents a melt of a workpiece from bonding with oxygen in a processing area when processing the workpiece using a laser beam.
• Another object of the present invention is to provide laser processing apparatus and method, which employs an oxygen blocking device while processing a workpiece using a laser beam, thereby increasing the ejection rate of a melt, improving processing efficiency, and increasing the strength of a die.
• an oxygen blocking device comprising a laser beam incidence section having a cylindrical configuration, for allowing a laser beam to be introduced therein; a first gas inlet section having a cylindrical configuration which extends from the laser beam incidence section, for jetting gas onto a surface of a workpiece while processing the workpiece using the laser beam, in order to prevent a melt of the workpiece from bonding with oxygen; a second gas inlet section formed around the first gas inlet section to define a space independent of the first gas inlet section and having a cylindrical configuration which is larger than the first gas inlet section, for jetting gas onto the surface of the workpiece while processing the workpiece, in order to prevent the melt of the workpiece from bonding with oxygen; a gas and laser beam radiation section for radiating the laser beam introduced into the laser beam incidence section and gas introduced into the first and second gas inlet sections; and a fastening section formed between the laser beam incidence section and the first gas inlet section and coupled to an external member.
• a laser processing apparatus comprising conveying means for loading in a chamber a workpiece to be processed and fixedly maintaining the workpiece on a base member; a control section for storing control parameters required for processing the workpiece; a driver operated under the control of the control section; an oxygen blocking device positioned by the driver to be separated from the workpiece by a predetermined distance, for jetting gas onto the workpiece; gas supply means connected to the oxygen blocking device through nozzles, for supplying gas into the oxygen blocking device; a laser generating section for radiating the laser beam under the control of the control section; and a mirror for reflecting the laser beam radiated from the laser generating section and directing the laser beam onto the workpiece through the oxygen blocking device.
• a laser processing method using an oxygen blocking device which is connected to a gas supply section through nozzles to supply gas to a processing area of a workpiece while processing the workpiece, the method comprising the steps of; determining control parameters in consideration of a processing purpose; loading and fixedly maintaining the workpiece in a chamber; moving and positioning the oxygen blocking device on the processing area of the workpiece; supplying gas from the gas supply section through the oxygen blocking device onto the processing area of the workpiece; and radiating the laser beam through the oxygen blocking device onto the processing area of the workpiece.
• FIG. 1 is a view explaining a conventional workpiece processing method using a laser beam
• FIG. 2 is a cross-sectional view of an oxygen blocking device in accordance with an embodiment of the present invention
• FIG. 3 is a top perspective view of the oxygen blocking device according to the present invention.
• FIG. 4 is a bottom perspective view of the oxygen blocking device according to the present invention.
• FIG. 5 is a view illustrating a configuration of a laser beam radiation section in the oxygen blocking device according to the present invention
• FIG. 6 is a view explaining a relationship between gas injection speed and distance from a workpiece in the oxygen blocking device according to the present invention
• FIG. 7 is a view explaining a workpiece processing principle using the oxygen blocking device according to the present invention.
• FIG. 8 is a block diagram illustrating a construction of a workpiece processing apparatus using the oxygen blocking device according to the present invention.
• FIG. 9 is a flow chart explaining a workpiece processing method using the oxygen blocking device according to the present invention.
• FIG. 10 is a graph explaining a relationship between processing speed and processing depth depending upon whether or not the oxygen blocking device is used;
• FIGs. HA and HB are photographs for illustrating a difference in processing depth of a silicon wafer depending upon whether or not the oxygen blocking device is used.
• FIG. 2 is a cross-sectional view of an oxygen blocking device in accordance with an embodiment of the present invention.
• an oxygen blocking device 100 in accordance with an embodiment of the present invention comprises a laser beam incidence section 110 having a cylindrical configuration, for allowing a laser beam to be introduced therein; a first gas inlet section 130 having a cylindrical configuration which extends from the laser beam incidence section 110, for jetting inert gas onto a surface of a workpiece while processing the workpiece using the laser beam, in order to prevent a melt of the workpiece from bonding with oxygen; a second gas inlet section 140 formed around the first gas inlet section 130 to define a space independent of the first gas inlet section 130 and having a cylindrical configuration which is larger than the first gas inlet section 130, for jetting inert gas onto the surface of the workpiece while processing the workpiece, in order to prevent the melt of the workpiece from bonding with oxygen; a gas and laser beam radiation section 150 for radiating the laser beam introduced into the laser beam incidence section 110 and discharging the inert gas introduced into the first and second gas inlet sections 130 and 140; and a fastening section 120 formed
• the laser beam incidence section 110 has a laser beam incidence hole 112 through which the laser beam is radiated onto the surface of the workpiece.
• a condensing lens for maintaining the focus of the laser beam in the laser processing apparatus is fitted in the laser beam incidence hole 112.
• the first and second gas inlet sections 130 and 140 are respectively defined with first and second gas inlets 132 and 142 to which inert gas from a gas supply section is supplied.
• the gas and laser beam radiation section 150 has a laser beam outlet 152 for radiating the laser beam introduced into the laser beam incidence section 110 and discharging the inert gas introduced into the first gas inlet section 130, first gas outlets 154a and 154b and second gas outlets 156a and 156b for discharging the inert gas introduced into the second gas inlet section 140, respectively.
• the inert gas may comprise helium, argon, or a combination thereof.
• FIG. 3 is a top perspective view of the oxygen blocking device according to the present invention, viewed from the laser beam incidence hole 112.
• the laser beam incidence section 110, the fastening section 120, the first and second gas inlet sections 130 and 140, and the gas and laser beam radiation section 150 are formed to have cylindrical configurations.
• the fastening section 120 is defined with a plurality of locking holes 120a, 120b, 120c and 12Od so that the oxygen blocking device 100 can be coupled to another device (such as a driver, etc.).
• FIG. 4 is a bottom perspective view of the oxygen blocking device according to the present invention, viewed from the gas and laser beam radiation section 150.
• FIG. 5 is a view illustrating a configuration of the laser beam radiation section in the oxygen blocking device according to the present invention.
• the laser beam outlet 152 is defined in the shape of a slit so that laser beam and inert gas from the first gas inlet section 130 can be radiated through the laser beam outlet 152. Inert gas introduced into the second gas inlet section
• first and second gas outlets 154 and 156 are designed to define a dome-shaped contour which serves as a damper for preventing a melt produced from the workpiece while processing the workpiece, from splashing and adhering to the oxygen blocking device 100.
• the reason why the first and second gas inlet sections 130 and 140 are formed independently of each other is that the outlets through which the gas introduced into the first and second gas inlet sections 130 and 140 is discharged have different sizes, hi other words, if a single gas inlet section is used, gas is discharged through a hole having low resistance, that is, the laser beam outlet 152. Therefore, in order to ensure that gas is uniformly jetted while proper internal pressures are maintained in respective spaces, the gas inlet sections 130 and 140 are constituted independently of each other.
• first gas discharged through the laser beam outlet 152 and second gas discharged through the first and second gas outlets 154 and 156 should be controlled to create streamlined laminar flow. To this end, it is necessary to appropriately adjust the gas injection speed and control the distance between the lower surface of the oxygen blocking device 100 and the workpiece to several millimeters.
• FIG. 6 is a view explaining a relationship between gas injection speed and distance from the workpiece in the oxygen blocking device according to the present invention.
• gas flow between the workpiece 10 and oxygen blocking device 100 is simplified as flow between two flat plates.
• a Reynolds number (Re) expressed below by Equation 2 will be considered.
• the Reynolds number is a non-dimensional number which serves as an index for obtaining a ratio between an inertia force and a viscous force of fluid flow passing through an object or a path.
• p the density of flowing gas
• ⁇ the coefficient of dynamic viscosity of the fluid.
• the average flow velocity V when h is set to 1.5 mm, it is to be appreciated from Equation 2 that, in order to ensure creation of laminar flow, the average flow velocity V must be no greater than 5.76 m/s, preferably 3-5 m/s, when the gas comprises argon, and no greater than 54.5 m/s, preferably 43-53 m/s, when the gas comprises helium.
• FIG. 7 is a view explaining a workpiece processing principle using the oxygen blocking device according to the present invention.
• inert gas is introduced into the first and second gas inlet sections 130 and 140, and the laser beam is radiated through the laser beam incidence hole 112 to process the workpiece 10.
• inert gas from the first gas inlet section 130 is jetted as designated by the reference numeral 30
• inert gas from the second gas inlet section 140 is jetted through the first and second gas outlets 154 and 156 as designated by the reference numeral 40.
• FIG. 8 is a block diagram illustrating a construction of a workpiece processing apparatus using the oxygen blocking device according to the present invention.
• a laser processing apparatus 200 using the oxygen blocking device comprises conveying means 210 for conveying the workpiece 10 such as a wafer into a chamber 280, a fixing section 220 for sucking and fixing the workpiece 10, a control section 230 for controlling the operation of the entire laser processing apparatus 200, an input section 232 for inputting control parameters and control instructions, a display section 234 for displaying information such as the operational status, etc., a storage section 236 for storing data, the oxygen blocking device 100 installed so as to be separated from the workpiece by a predetermined distance, a driver 240 for fixing and driving the oxygen blocking device 100, inert gas supply means 250 for supplying gas to the oxygen blocking device 100 through the first and second nozzles 252 and 254, laser generating means 260 for generating the laser beam of a predetermined diameter, and reflection means 270 for changing the direction of the laser beam radiated from the laser generating means 260 and focusing the laser beam onto a processing position on the workpiece 10 such as a
• FIG. 9 is a flow chart explaining a workpiece processing method using the oxygen blocking device according to the present invention.
• control parameters are determined depending upon the workpiece to be processed (Sl 10). This determination step is implemented in a manner such that one of menus, which are preset in consideration of the kind of workpiece to be processed, a processing type (such as cutting, grooving, etc.), and so forth, and stored in the storage section 236, are called up.
• the control parameters include an output magnitude and a frequency of laser beam, a processing position, a processing length, a processing depth, a flow rate, a flow velocity and a pressure of inert gas, etc.
• the control parameters are determined, the workpiece 10 is loaded into the chamber 280 using the conveying means 210 and fixed on the fixing section 220 (S 120).
• the driver 240 moves the oxygen blocking device 100 under the control of the control section 230 and positions the oxygen blocking device 100 above the processing area of the workpiece 10 (S130).
• the inert gas supply means 250 supplies inert gas into the first and second gas inlet sections 130 and 140 of the oxygen blocking device 100 through the first and second nozzles 252 and 254 to allow the inert gas to be jetted through the laser beam outlet 152 and the first and second gas outlets 154 and 156 (S 140).
• inert gas may comprise helium, argon or a combination thereof.
• the control section 230 controls the laser generating means 260 to generate a laser (S 150).
• the laser beam generated by the laser generating means 260 is radiated through the reflection means 270 and by way of the oxygen blocking device 100 onto the workpiece 10 to effect processing of the workpiece 10 (S 160).
• the workpiece is unloaded from the chamber to undergo subsequent processes.
• FIG. 10 is a graph explaining the relationship between processing speed and processing depth depending upon whether or not the oxygen blocking device is used.
• changes of processing depth with respect to processing speeds are illustrated when a silicon wafer having a thickness of 720 ⁇ m is processed using the oxygen blocking device using argon and when the silicon wafer is processed without using the oxygen blocking device.
• FIGs. HA and HB are photographs for illustrating the difference in processing depth of a silicon wafer depending upon whether or not the oxygen blocking device is used. These sectional photographs show the processing of a silicon wafer at a processing speed 10im/s under the same conditions as in FIG. 10.
• FIG. 1 IA is a sectional photograph showing the case in which the silicon wafer is processed without employing the oxygen blocking device and illustrates a state in which the silicon wafer is processed to a depth of 141 ⁇ m.
• FIG. HB is a sectional photograph showing the case in which the silicon wafer is processed employing the oxygen blocking device and illustrates a state in which the silicon wafer is processed to a depth of 220 ⁇ m.
• the present invention provides advantages in that, in order to prevent a melt produced in a workpiece processing area from bonding with oxygen while processing a workpiece using a laser beam and to thereby suppress the viscosity of the melt from increasing, oxygen is blocked using an inert gas when radiating a laser beam onto the workpiece processing area, whereby the ejection speed and the ejection rate of the melt can be increased.
• processing efficiency including a processing speed, processing quality, and so forth, can be improved. Further, since it is possible to prevent a substance
• the strength of a die can be increased.

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• 2005
  • 2005-02-23 KR KR1020050015082A patent/KR100601905B1/ko active IP Right Grant
  • 2005-05-26 WO PCT/KR2005/001550 patent/WO2006090949A1/en active Application Filing

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