Classifications

• • 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
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
• • 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
  • H01L21/02002—Preparing wafers
  • H01L21/02005—Preparing bulk and homogeneous wafers
  • H01L21/02008—Multistep processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
• • 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
  • H01L21/02002—Preparing wafers
  • H01L21/02005—Preparing bulk and homogeneous wafers
  • H01L21/02008—Multistep processes
  • H01L21/0201—Specific process step
  • H01L21/02024—Mirror polishing

Definitions

• the invention relates to a method for producing a semiconductor wafer.
• semiconductor wafers are in a plurality of successive process steps
• the production of a semiconductor single crystal is usually carried out by pulling a single crystal from a melt (CZ or "Czochralski” method) or by recrystallization of a rod made of polycrystalline semiconductor material (FZ or "floating zone” method).
• the mechanical processing serves to remove seeding, remove the surface layers that are damaged by the rougher sawing processes or are contaminated by the saw wire, and above all, the global leveling of the semiconductor wafers.
• surface loops single-sided, double-sided
• lapping known, as well as mechanical
• the semiconductor wafer is held on the back on a base ("chuck") and on the front by a cup grinding disk with rotation of the base and
• the grinding wheel is positioned so that the center of rotation of the semiconductor wafer passes into a working region or the edge region of the grinding wheel formed by teeth. This can, the entire surface of the
• the semiconductor wafers are moved under a certain pressure while supplying a slurry containing abrasive materials between an upper and a lower working disk, which are usually made of steel and are usually provided with channels for better distribution of the lapping agent, whereby semiconductor material is removed.
• DE 103 44 602 A1 and DE 10 2006 032 455 A1 disclose methods for simultaneous simultaneous grinding of both sides of a plurality of semiconductor wafers with a movement sequence similar to that of lapping, but characterized in that abrasive is used which is fixed in working layers ("films").
• Working disks are glued, for example, described in US 6,007,407 A and US 6,599,177 B2. During processing, the semiconductor wafers are in thin guide cages, so-called.
• Carrier discs inserted, the corresponding openings for
• the LauferScheiben have an external toothing, which engages in a rolling device of the inner and outer ring gear and are moved by means of this, in the formed between the upper and lower working disk, working gap.
• the edge of the semiconductor wafer including any mechanical markings such as a
• Orientation notch ("notch") is usually also processed (edge rounding, "edge-notch-grinding”). To do this
• edge rounding methods are necessary because the edge is particularly susceptible to breakage in the unprocessed state and the semiconductor wafer can already be damaged by slight pressure and / or temperature stresses in the edge region.
• the ground and treated with an etching medium edge of the disc is usually polished.
• the edge of a centrally rotating semiconductor wafer is pressed with a certain force (contact pressure) against a centrally rotating polishing drum.
• Aluminum alloy is composed and with a polishing cloth
• the semiconductor wafer is usually fixed on a flat disk holder, a so-called chuck.
• the edge of the semiconductor wafer protrudes beyond the chuck so that it is freely accessible to the polishing drum.
• the group of chemical processing steps includes
• the group of chemo-mechanical processing steps includes polishing steps with which the surface is smoothed by partial chemical reaction and partial mechanical removal of material (abrasion) and residual damage to the surface is removed. While the single-sided polishing processes generally lead to poorer plane parallelism, double-sided polishing processes produce semiconductor wafers with improved flatness.
• semiconductor wafers through removal polishing.
• semiconductor wafers "single-side polishing", SSP) are held back on a carrier plate with putty, by vacuum or by adhesion
• Double-side polishing semiconductor wafers are loosely inserted into a thin toothed disc and polished simultaneously "free floating" between an upper and a lower, with a polishing cloth occupied polishing plate front and back.
• the front sides of the semiconductor wafers are often polished without haze, for example with a soft polishing cloth with the aid of an alkaline polishing sol.
• this step is often called CMP polishing ("chemo-mechanical polishing").
• FAP Fixed Abrasive Polishing
• a polishing step using such a FAP polishing cloth is hereinafter referred to as FAP step for short / 55491 A1 describes a two-stage polishing process, with a first FAP polishing step and a subsequent second CMP polishing step In CMP, the polishing cloth does not contain a bonded abrasive Abrasive is here as in a DSP step in the form of a suspension between the silicon wafer and the Such a two-stage polishing method is used in particular to eliminate scratches that the FAP step has left on the polished surface of the substrate.
• German patent application DE 102 007 035 266 A1 describes a method for polishing a substrate made of silicon material comprising two polishing steps of the FAP type, which characterized in that in a polishing step a
• Solid is brought between the substrate and the polishing cloth, while in the second polishing step in place of the polishing agent suspension occurs a polishing agent solution which is free of solids.
• semiconductor wafers are made with an epitaxial
• epitaxially coated or epitaxially coated semiconductor wafers have certain advantages over semiconductor wafers made of homogeneous material, for example the prevention of a
• Crystal-originated particles and the absence of a significant oxygen content, whereby a short circuit risk can be excluded by oxygen precipitates in device-relevant areas.
• wet etching can be replaced by a plasma etching.
• DSP polished semiconductor wafers obtainable by this process have unsatisfactory edge geometry due to the use of wet chemical treatments as well as plasma assisted chemical etching (PACE). At best, semiconductor wafers are acceptable
• the nanotopology is adversely affected by etching.
• an increased material removal is necessary with DSP, which in turn negatively affects the geometry in the edge region
• the object of the invention is achieved by a method for producing a semiconductor wafer, comprising in the
• a semiconductor wafer is separated from a single crystal of semiconductor material grown by means of CZ or FZ.
• the separation of the semiconductor wafer is preferably carried out with a wire saw.
• the separation of the semiconductor wafer by means of wire saw is carried out as e.g. from US 4655191, EP 522 542 Al, DE 39 42 671 Al or EP 433 956 Al known.
• the grown single crystal of semiconductor material is preferably a single crystal of silicon.
• the Semiconductor wafer is preferably a monocrystalline silicon wafer.
• Step (a) Two-sided material removing machining of the semiconductor wafer separated from a single crystal
• step (a) of the method according to the invention both sides of the semiconductor wafer are processed to erode material.
• DDG simultaneous double-side loops
• PPG Planetary Päd Grinding
• JP2000-280155A and JP2002-307303A described have two opposing grinding wheels whose axes of rotation are arranged collinear. During the grinding process, one between the grinding wheels
• the holding and rotating device can, for example
• notch finger To the entire To machine the surface of the workpiece, the workpiece is guided relative to the grinding wheels so that the abrasive
• Abrasive segments of the grinding wheels describe a circular path which runs continuously over the workpiece center.
• the workpiece is usually not firmly fixed, but is by two to both sides of the workpiece
• Each hydropad includes several
• Hydrostatic bearing between which grooves for discharging the medium used for the hydrostatic bearing (hereinafter referred to as "hydro-bearing medium”) and the grinding coolant are arranged.
• one or more measuring sensors are integrated, which during the grinding process, a measurement of the distance between the surface of the hydropads and the
• Back pressure nozzles are usually mounted close to the edge of the hydropads adjacent to the grinding wheels.
• PPG is a process for simultaneous double-sided grinding of a plurality of semiconductor wafers, each wafers being freely movable in a recess of one of a plurality of wafers rotated by a winder, and thereby on a cycloid
• the PPG to be processed is the PPG to be processed
• abrasive hard material with a Mohs hardness> 6 is preferred.
• Suitable abrasives are preferably diamond, silicon carbide (SiC),
• Ceria (CeO 2 ), corundum (alumina, Al 2 O 3 ), zirconia (ZrO 2 ), boron nitride (BN, cubic boron nitride, CBN), further
• Silicon dioxide SiO 2
• boron carbide B 1 C
• barium carbonate BaCO 3
• calcium carbonate CaCO 3
• magnesium carbonate MgCO 3
• diamond silicon carbide
• Al 2 O 3 alumina
• the mean grain size of the abrasive should be less than 9 microns.
• the preferred size of the abrasive grains bonded in the working layers is in the case of diamond as
• the diamonds are preferably singly or as conglomerates ("clusters") in the bonding matrix of
• the preferred grain diameters are the primary particle size of the cluster constituents.
• Working layers with a ceramic bond are preferably used; a synthetic resin bond is particularly preferred; in the Case of working layers with conglomerates also a hybrid bonded system (ceramic bond within the
• the hardness of the working layer is preferably at least 80 Shore A.
• the working layer is constructed in multiple layers, wherein the top and bottom have different hardness, so that point elasticity and long-term compliance of the working layer can be adjusted independently of the process requirements.
• the abrasive materials incorporated in the working layer are preferably exposed by removing the uppermost layer in order to make them usable for the grinding process.
• This initial sharpening is carried out, for example, with the aid of grindstones or knives, which are preferably specially modified
• Rotor discs are mounted and are guided by means of the rolling device on the two working wheels.
• the dressing is done with grindstones containing abrasive grain having a similar grain size to the abrasive in the working layers
• “Sharpening stones” can for example be inserted annularly and in an externally toothed driving ring, so that they by means of the rolling devices of the grinding machine on
• the sharpening stones preferably coat the entire surface of the working layers during the dressing, and even more preferably even run
• the abrasive grain is preferably bonded in the sharpening stone in such a way that the wear of the sharpening stones still permits an economical sharpening operation, but always during the sharpening process at least one layer of loose sharpening grain grain in the sharpening stone Work zone is located between sharpening stone and working surface, so that the sharpening mainly by free
• Sharpening stone with too coarse grain therefore imposes a structure on the working layer, which is characterized by the grain of the sharpening stone and not by the properties of the working layer. This is unfavorable for the desired uniform possible self-sharpening of the working layer in the following
• Sharpening is predominantly less directed by free sharpening grain as a result of the rolling motion of the sharpening grain during the sharpening movement
• Working layer used abrasive grains. Particularly preferred is the sharpening grains of corundum (Al 2 O 3 ).
• sanding fabric residues are preferably removed and constantly exposed new, easy-to-cut abrasive materials. This is a continuous operation until complete wear of the
• multi-grain grinding with a geometrically indeterminate cutting edge Relative movement of working layer and semiconductor wafers Successful material removal is technically referred to as "multi-grain grinding with a geometrically indeterminate cutting edge”.
• surface engagement is meant that the portion of the surface of the working layer which actually averages during grinding in contact with the
• Cup grinding loop process such as DDG or SSG.
• the carriers are preferably made of a completely metal-free material, such as a ceramic
• Such a coating is preferably made of thermoplastic or thermosetting plastics, ceramics or organic-inorganic hybrid polymers, diamond
• Semiconductor wafers preferably lined with a ceramic material. As a result, there is no direct contact between the semiconductor wafer and the metal of the rotor disc.
• a rotor disk preferably has three to eight recesses for semiconductor wafers. During one The grinding process is preferably five to nine
• the main load step is the
• Processing phase with the highest pressure or the proportionately longest duration or both In the case of a working layer with abrasive grains of diamond having an average size of 3 to 15 ⁇ m, a removal rate between 2.5 and 25 ⁇ m / min is particularly preferred.
• the temperature prevailing in the working gap formed between the working layers is kept constant.
• the carrier discs may have openings through which cooling lubricant can be exchanged between lower and upper working disk, so that upper and lower working layers always have the same temperature. This counteracts an undesired deformation of the working gap formed between the working layers by deformation of the working layers or working disks due to thermal expansion under alternating load.
• the cooling of those involved in the working layers may be kept constant.
• the cooling lubricant used preferably consists of a water-based mixture with viscosity-modifying
• Additives such as glycols, short or longer chain polyethylene glycols, alcohols, sols or gels, and the like
• coolants or lubricants.
• a particularly preferred coolant but is also pure water without any addition.
• Working disk supplied amounts of cooling lubricant are preferably in the range between 0.2 and 50 l / min and more preferably between 0.5 and 20 l / min.
• the preferred initial thickness before processing with step a) of the method according to the invention is 500 to 1000 ⁇ m.
• an initial thickness of 775 to 950 ⁇ m is particularly preferred.
• Step a) of the process according to the invention is preferably 500 to 950 ⁇ m and more preferably 775 to 870 ⁇ m.
• the total removal, d. H. the sum of the individual abrasions from both sides of the semiconductor wafer is preferably 7.5 to 120 ⁇ m and more preferably 15 to 90 ⁇ m.
• the shape of the working gap formed between the working layers is determined during grinding and the shape of the working surface of at least one working disk mechanically or thermally changed depending on the measured geometry of the working gap so that the working gap has a predetermined shape.
• the semiconductor wafers leave during the
• Overflow is defined as the relative to the working wheels measured in the radial direction length to the one
• Semiconductor disk at a certain time during grinding beyond the inner or outer edge of the working gap is also.
• step (b) the semiconductor wafer is provided with a rounded edge.
• the semiconductor wafer is fixed on a rotating table and delivered with its edge against the also rotating working surface of a machining tool.
• the processing tools used can be used as slices
• Material-removing grain can be firmly anchored in the working surfaces of the processing tools. Usually that shows
• the mean grain size is preferably greater than or equal to 10 ⁇ m.
• Semiconductor wafer to be provided with a rounded edges. Usually, however, after edge rounding, a certain minimum roughness remains on the edge surface.
• step (a) of the method it is preferable to use two edge grinding steps
• Step (c) grinding front and back of the
• step c) of the process both sides of the
• the grinding of front and back is preferably carried out sequentially.
• Semiconductor wafer enters a working area of the grinding wheel, wherein the grinding wheel with a Feed rate is moved in the direction of the semiconductor wafer, whereby the grinding wheel and semiconductor wafer are delivered to each other while semiconductor wafer and
• the grinding wheel and semiconductor wafer be delivered by a distance of 0.03-0.5 ⁇ m during one revolution of the semiconductor wafer. Very particularly preferred is the choice of a delivery during a revolution of
• Wafer of 0.03-0.1 ⁇ m Preferably, a grinding wheel with a grain size greater than or equal to # 2000 is used, most preferably # 2000 - # 8000.
• the grain size is usually indicated in # (mesh size) according to Japanese Industrial Standard JIS R 6001: 1998.
• Finishing wheels have e.g. a grit of # 1000 up to # 4000, e.g. that of Disco Corporation commercially
• # 1200 has an average particle size of 9.5 ⁇ m, # 5000 a mean particle size of 2.5 ⁇ m, and # 8000 a mean particle size of 1.2 ⁇ m.
• the mean particle sizes during fine grinding are thus approximately greater than or equal to 1 ⁇ m and less than or equal to 10 ⁇ m.
• Grinding wheels of a grain size of less than or equal to # 2000 are performed in order to achieve the highest possible removal rates and short process times (rough grinding) and the second, subsequent step with grinding wheels of a grain size greater than # 2000 and less than or equal to # 8000 takes place to be particularly smooth sanded wafers with a minimum damage of approx. 1 ⁇ m (fine sanding).
• the rotational speed of the grinding wheel is preferably 1000-5000 min -1 .
• the rotational speed of the semiconductor wafer is preferably 50-300 min -1 , very particularly preferably 200-300 min -1 .
• the feed speed is preferably 10-20 ⁇ m / min.
• step (d) at least one side of the semiconductor wafer is polished with a polishing cloth containing abrasives.
• step (d) only the front side of the
• step (d) only the back of the
• step (d) both the front and rear sides of the semiconductor wafer are polished.
• polishing step is preferably a
• Polishing agent solution which is free of solids, placed between the side of the semiconductor wafer to be polished and the polishing cloth.
• the polish solution is in the simplest case water, preferably deionized water (DIW) with the purity customary for use in the semiconductor industry.
• DIW deionized water
• the polish solution can also be compounds such as
• the pH of the polishing agent solution is preferably in a range of 10 to 12 and the proportion of said compounds in the
• Polishing agent solution is preferably 0.01 to 10 wt .-%, particularly preferably from 0.01 to 0.2 wt .-%.
• the polish solution may also contain one or more further additives, for example surface-active additives such as wetting agents and surfactants, as protective colloids
• a polishing cloth which contains an abrasive substance bound in the polishing cloth (FAP or FA cloth or FA pad).
• Suitable abrasives include, for example, particles of oxides of the elements cerium, aluminum, silicon, zirconium and Particles of hard materials such as silicon carbide, boron nitride and diamond.
• polishing dishes have a surface topography embossed by replicated microstructures.
• posts are in the form of pillars having a cylindrical or polygonal cross-section, or in the shape of pyramids or truncated pyramids Further descriptions of such polishing cloths are included, for example, in WO 92/13680 A1 and US 2005/227590 A1.
• the grain sizes of the FAP polishing cloths used are preferably greater than or equal to 0.1 p and less than or equal to 1.0 micron.
• Particularly preferred is a particle size of 0.1-0.6 ⁇ m.
• the FA-polishing is preferably carried out with ablations of greater than or equal to 1 micron per side, in this regard, the range of 1 - 3 microns is particularly preferred and quite
• the discs processed by FA polishing are identical to The discs processed by FA polishing.
• Step (e) - etching or cleaning the semiconductor wafer In step (e) of the method according to the invention, both sides of the semiconductor wafer are treated with a corrosive medium at a material removal of not more than 1 ⁇ m per side of the semiconductor wafer.
• the minimum material removal per side of the semiconductor wafer is preferably 1 monolayer, i. about 0.1 nm.
• Suitable acidic media are aqueous solutions of hydrofluoric acid, nitric acid or acetic acid.
• the semiconductor wafer comprises a gaseous medium containing hydrogen fluoride and at least one surface of the semiconductor wafer
• the gaseous medium thus contains hydrogen fluoride and
• the oxidant must be able to remove the semiconductor material, e.g. Silicon, to oxidize. During the oxidation of a silicon surface arises
• silica for example, a silica, preferably silica.
• reaction products hexafluorosilicic acid (H 2 SiF 6 ), silicon tetrafluoride (SiF 4 ) and water are formed, which are removed by the flow of the gaseous medium.
• the gaseous medium may additionally contain further constituents, for example inert carrier gases such as nitrogen or Argon, for influencing the flow conditions and removal rates.
• At least one oxidizing agent selected from the group of nitrogen dioxide, ozone and chlorine is used.
• Silicon surface to use and thus to prevent condensation of the liberated in the reaction water even at low flow rates and temperatures.
• the constituents can be mixed in the desired ratio.
• the ratio of hydrogen fluoride to oxidant is selected in the range 1: 1 to 4: 1.
• the gaseous medium can be
• Hydrogen fluoride of suitable concentration directs. This can, for example, in a so-called. Wash bottle or a
• gaseous oxidant passes through the aqueous solution, it is enriched with water and hydrogen fluoride to form the required gaseous medium.
• process parameters and constant ratio of hydrogen fluoride to oxidant show an increase in temperature and an increase in the concentrations of one
• the etching in the gas phase serves to reduce the roughness of the semiconductor wafer, whereby the required polishing removal can be reduced, as well as for removing
• the SSEC 3400 ML from Solid State Equipment Corp. is particularly suitable for a wafer with a diameter of 450 mm that is particularly preferred in the context of the method according to the invention. / USA, which is designed for substrates up to a size of 500mm x 500mm.
• Step (g) polishing the edge of the wafer
• step (g) polishing of the edge of the
• edge polishing machines are suitable for carrying out step (g) of the method according to the invention. From US 5,989,105 such a device for edge polishing is known in which the polishing drum from a
• Aluminum alloy is composed and with a polishing cloth
• the semiconductor wafer is usually on a flat
• Disk holder a so-called chuck, fixed.
• the edge of the semiconductor wafer protrudes beyond the chuck so that it is freely accessible to the polishing drum.
• the chuck In edge polishing, the chuck is rotated centrally with the semiconductor wafer held thereon.
• one turn of the chuck takes 20-300, more preferably 50-150 seconds (orbital period).
• a polishing drum coated with the polishing drum, which is preferably at a rotational speed of 300-1500 min "1 , more preferably 500-1000 min " 1 , centrically rotated, and the Chuck are delivered to each other, the polishing drum under a
• Angle of attack is made obliquely against the semiconductor wafer and the semiconductor wafer is fixed on the chuck so that it protrudes slightly beyond this and is thus accessible to the polishing drum.
• the angle of attack is preferably 30-50 °.
• Polishing agent preferably with a polishing agent flow of 0.1-1 liter / min, more preferably 0.15-0.40 liters / min, pressed together, wherein the contact pressure can be adjusted by weights attached to rollers, and preferably 1-5 kg, particularly preferably 2-4 kg.
• the edge polishing of the semiconductor wafer in the method according to the invention is preferably carried out by fixing the
• the FAP cloth used is much harder and far less compressible than the standard polishing cloths and also offers the advantage of removal without alkaline-charged silica sol. B. only by using an alkaline solution - to produce what also Polierstoffverschleppung on the wafer front and thus the additional negative
• a short soft polishing step with gently removing silica sol can follow on the same FAP polishing cloth, to realize a reduction of the edge roughness and -de Stammraten.
• the two polishing steps can then be matched to each other, so that a targeted positive influence on the wafer edge geometry and surface without negative
• the semiconductor wafer is preferably by means of a polishing drum, on the surface of a hard and less compressible polishing cloth is adhered, which includes firmly bonded abrasive, under feeding a
• Glanzox 3900 is the product name for a polishing agent suspension offered as a concentrate by Fujimi Incorporated, Japan.
• the base solution of this concentrate has a pH of 10.5 and contains about 9% by weight colloidal SiO 2 with a
• Polishing agent carryover in the erosive step of the
• Wafer surface can be avoided.
• the polishing agent solution used in the edge polishing is in the simplest case water, preferably deionized water (DIW) with the usual purity for use in the semiconductor industry.
• DIW deionized water
• the polish solution can also be compounds such as
• TMAH tetramethylammonium hydroxide
• the pH of the polishing agent solution is preferably in a range of 10 to 12, and the proportion of said compounds in the polishing agent solution is preferably 0.01 to 10 wt%, particularly preferably 0.01 to 0.2 wt%.
• the polish solution may also contain one or more further additives, for example surface-active additives such as wetting agents and surfactants, as protective colloids
• the preferred second step of edge polishing uses a polishing agent containing abrasive.
• the proportion of the abrasive in the polishing agent suspension is preferably 0.25 to 20 wt .-%, particularly preferably 0.25 to 1 wt .-%.
• the size distribution of the abrasive particles is preferably monomodal.
• the mean particle size is 5 to 300 nm, more preferably 5 to 50 nm.
• the abrasive material consists of a substrate material
• mechanically ablative material preferably one or more of the oxides of the elements aluminum, cerium or silicon.
• a polishing agent suspension containing colloidally disperse silica is particularly preferred.
• no additives such as sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH 4 OH), tetramethylammonium hydroxide (TMAH) added.
• polishing agent suspension can contain one or more further additives, for example surface-active additives such as wetting agents and surfactants, acting as protective colloids
• step (g) of the method according to the invention a polishing cloth is used which contains an abrasive substance bound in the polishing cloth (FAP cloth or FA pad).
• Suitable abrasives include, for example, particles of oxides of the elements cerium, aluminum, silicon, zirconium and
• Particles of hard materials such as silicon carbide, boron nitride and diamond.
• polishing cloths have a surface topography embossed by replicated microstructures.
• posts are in the form of pillars having a cylindrical or polygonal cross section, or the shape of pyramids or truncated pyramids. Further descriptions of such polishing cloths are contained, for example, in WO 92/13680 A1 and US 2005/227590 A1.
• the mean particle size of the FAP polishing cloth is the mean particle size of the FAP polishing cloth.
• polishing cloth having a multilayer structure, comprising a layer
• abrasive a layer of rigid plastic and a resilient, non-woven layer, the layers being bonded together by means of pressure-sensitive adhesive layers.
• the layer of rigid plastic preferably comprises polycarbonate.
• the polishing cloth may contain an additional layer of polyurethane foam.
• the compliant layer is preferably a non-woven layer.
• the compliant layer preferably comprises polyester fibers.
• polyester fibers impregnated with polyurethane impregnated with polyurethane
• the resilient layer preferably corresponds to the bottom layer of the polishing cloth.
• Foam layer for example made of polyurethane, which is attached by means of an adhesive layer on the flexible layer.
• PU foam Above the PU foam is a layer of a harder, rigid material, preferably of a hard plastic, including itself
• polycarbonate is suitable.
• this stiff layer is the layer with the micro-replicas, ie the actual fixed abrasive layer.
• the pliable situation can also be between the
• PSA pressure-sensitive adhesive layers
• the polishing cloth comprises a layer of micro-replicas, a compliant layer and a layer of a rigid plastic such as polycarbonate, wherein the
• compliant layer may be either the middle or the bottom layer of the polishing cloth.
• the grain sizes of the FAP polishing cloths used are the same.
• step (f) polishing of a front side of the semiconductor wafer using a polishing cloth having firmly bonded abrasives and simultaneous polishing of one takes place
• step (g) edge polishing is performed as before
• step (h) polishing of the back side of the semiconductor wafer is carried out with a polishing cloth which includes firmly bonded abrasive and simultaneous polishing of the front side of the semiconductor wafer with a polishing cloth which does not contain firmly bonded abrasive, wherein an abrasive containing polishing agent between polishing cloth and front of
• the invention provides a combined simultaneous double-side polishing process by simultaneously applying a FAP polish and a CMP polish
• Steps (f) and (h) can be carried out on existing equipment for double side polishing of semiconductor wafers, e.g. on a commercial double-side polishing machine of the AC2000 type by Peter Wolters, Rendsburg (Germany).
• This polishing machine is equipped with a pin toothing of the outer and inner ring for driving the carriers.
• the system can be designed for one or more carriers. Because of the higher throughput, a system for a plurality of carriers is preferred, as described for example in DE-100 07 390 Al and in which the carriers move on a planetary orbit around the plant center. to
• Plant include a lower and an upper polishing plate, which are horizontally freely rotatable and covered with polishing cloth. During polishing, the wafers are located in the recesses of the carriers and between the two
• Polishing plates which rotate and apply a certain polishing pressure to them while a polishing agent is continuously supplied. It also the rotor discs in
• Movement offset preferably about rotating pin rings, which engage in teeth on the circumference of the rotor discs.
• a typical carrier disc has recesses for receiving three half-discs. At the circumference of the recesses are deposits that the break-sensitive edges of
• the rotor disk body can be made of metal, ceramic, plastic, fiber-reinforced plastic or metal, for example
• the recesses are preferably suitable for accommodating an odd number of semiconductor wafers with a diameter of .mu.m.sup.2 at least 200 mm, preferably 300 mm, very particularly preferably 450 mm and thicknesses of 500 to 1000 microns designed
• Polishing cloth which contains no firmly bonded abrasive, includes Abrasive. It is about a
• polishing agent suspension The size distribution of the abrasive particles is preferably monomodal.
• the mean particle size is 5 to 300 nm, more preferably 5 to 50 nm.
• the abrasive material consists of a substrate material
• the proportion of the abrasive in the polishing agent suspension is preferably 0.25 to 20 wt .-%, particularly preferably 0.25 to 1 wt .-%.
• colloidally disperse silica as polishing agent suspension.
• aqueous polishing agents Levasil® 200 from Bayer AG and Glanzox 3900® from the company are used. Fujimi.
• the polishing agent contains additives such as
• Na 2 CO 3 sodium carbonate
• K 2 CO 3 sodium hydroxide
• KOH potassium hydroxide
• NH 4 OH ammonium hydroxide
• TMAH tetramethylammonium hydroxide
• polishing agent suspension can contain one or more further additives, for example surface-active additives such as wetting agents and surfactants, acting as protective colloids
• Stabilizers preservatives, biocides, alcohols and complexing agents.
• a polishing cloth is also used which has a polishing cloth
• Suitable abrasives include, for example, particles of oxides of the elements cerium, aluminum, silicon, zirconium and particles of hard materials such as silicon carbide, boron nitride and diamond.
• Particularly suitable polishing cloths have a surface topography embossed by replicated microstructures.
• posts are in the form of pillars having a cylindrical or polygonal cross-section, or the shape of pyramids or truncated pyramids.
• polishing cloths are contained, for example, in WO 92/13680 A1 and US 2005/227590 A1.
• a polishing cloth with cerium oxide abrasives firmly bonded therein such as e.g. in US 6602117 Bl.
• the grain sizes of the FAP polishing cloths used are preferably greater than or equal to 0.1 ⁇ m and less than or equal to 1.0 ⁇ m.
• Particularly preferred is a particle size of 0.1-0.6 ⁇ m.
• a polishing plate is equipped with such a FAP cloth.
• the second polishing plate is loaded with a conventional CMP polishing cloth.
• the CMP polishing cloths used are:
• Polishing cloths with a porous matrix Polishing cloths with a porous matrix.
• the polishing cloth is made of a thermoplastic or thermosetting polymer.
• the material is a variety of materials into consideration, for example, polyurethanes, polycarbonate, polyamide, polyacrylate, polyester, etc.
• the polishing cloth includes solid, microporous polyurethane. The use of polishing cloths is also preferred
• foamed sheets or felt or fiber substrates impregnated with polymers are foamed sheets or felt or fiber substrates impregnated with polymers.
• the polishing cloths can be largely flat or perforated.
• fillers may be incorporated into the polishing cloth.
• polishing cloths are e.g. the SPM 3100 from Rodel Inc. or the DCP series cloths and the IC1000 TM, Polytex TM or SUBA TM cloths from Rohm & Hass.
• polishing according to steps (f) and (h) of the process according to the invention can be carried out on a double-side polishing machine, as is the case, for example, with type AC 2000 from Peter Wolters / Rendsburg Technique obligatory one-sided
• CMP Veiling Polishing
• edge geometry edge roll-off elimination
• simultaneous double side polishing with planetary kinematics and
• Shaped cloth to achieve the necessary polishing removal to dispense with a silica sol-containing component and also allows targeted influence on the edge region of the
• the simultaneous double-sided polish already integrates the CMP polish by using one of the
• Polishing plate is equipped with a CMP polishing cloth on which the CMP step takes place.
• the Doppel capacpolitur invention finds in two
• step (g) Semiconductor wafer according to step (g) is edge polished.
• a two-stage edge polishing is carried out, in which a first edge polish between the two partial steps of the double-sided polish (f) and (h) and the second
• Double-side polishing that is, after step (h) is performed, which allows the edge polish finer tune by this division in two steps and thus to influence the edge geometry of the semiconductor wafer as little as possible.
• Both steps of edge polishing preferably take place by means of polishing cloths with abrasives firmly bonded therein.
• the second edge polishing is preferably carried out with the supply of an abrasive-containing polishing agent suspension, such as the optional soft polishing step described under (g).
• the proportion of abrasives in the polishing agent suspension is preferably 0.25 to 20 wt .-%.
• the abrasives in the polishing agent suspension are:
• the polishing agent suspension is colloidally disperse silica.
• the pH of the polishing agent suspension is 9 to 11.5.
• the pH of the polishing agent suspension is adjusted by addition of additives selected from the group consisting of sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH 4 OH ), Tetramethylammonium hydroxide (TMAH) or any mixtures of these compounds.
• additives selected from the group consisting of sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH 4 OH ), Tetramethylammonium hydroxide (TMAH) or any mixtures of these compounds.
• additives selected from the group consisting of sodium carbonate (Na 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH 4 OH ), Tetramethylammonium hydroxide (TMAH) or any
• the semiconductor wafer points to the flat surfaces of their
• Back preferably has an average surface roughness R a in a wide range of 0.3 to 4.5 nm, based on spatial wavelengths of less than or equal to 250 microns.
• FAP wipes are used with grain sizes of 0.5-1.0 microns. If low back roughness is desired, it is preferred to use FAP wipes with grain sizes of 0.1-0.25 ⁇ m.
• the polishing agent solution in the first step of polishing the back of the silicon wafer of the method according to the invention is in the simplest case water, preferably deionized water (DIW) with that for use in the DIW.
• DIW deionized water
• the polish solution can also be compounds such as
• TMAH Tetramethylammonium hydroxide
• potassium carbonate is the polish of the back of the polish
• Semiconductor wafer is a polishing agent containing abrasive used.
• the abrasive material consists of a substrate material
• mechanically ablative material preferably one or more of the oxides of the elements aluminum, cerium or silicon.
• polishing agent suspension containing colloidally disperse silica.
• Semiconductor wafer is also a polishing agent containing abrasives as used in the second step. Polishing pressure is reduced from 8-15 psi to 0.5-5 psi versus the first and second steps.
• polishing machines e.g. the polishing machine "nHance 6EG” from Strasbaugh Inc.
• the polishing machine from Strasbaugh Inc. has a polishing pad with a polishing cloth and a polishing head that processes a semiconductor wafer fully automatically.
• the polishing head is gimballed and includes a fixed base plate coated with a backing ubend and a movable guide ring. Drilled holes in the base plate allow air cushions to be constructed in two concentric pressure zones, one inner and one outer, on which the The movable guide ring may be pressurized by means of a pneumatic bellows so as to bias and hold the polishing cloth in contact with the semiconductor wafer.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Mechanical Engineering (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)

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• 2009
  • 2009-08-26 DE DE102009038941A patent/DE102009038941B4/de not_active Expired - Fee Related
• 2010
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  • 2010-08-11 WO PCT/EP2010/004916 patent/WO2011023297A1/de active Application Filing
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