Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • 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
• • 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
  • B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
  • B24B37/044—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor characterised by the composition of the lapping agent
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P90/00—Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
  • H10P90/12—Preparing bulk and homogeneous wafers
  • H10P90/129—Preparing bulk and homogeneous wafers by polishing
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices
  • H10P52/40—Chemomechanical polishing [CMP]
  • H10P52/402—Chemomechanical polishing [CMP] of semiconductor materials

Definitions

• the present invention relates to polishing compositions.
• This application claims priority based on Japanese Patent Application No. 2021-016868 filed on February 4, 2021, the entire contents of which are incorporated herein by reference.
• a polishing composition is used to polish the surfaces of materials such as metals, semi-metals, non-metals, and their oxides.
• a surface composed of a compound semiconductor material such as silicon carbide, boron carbide, tungsten carbide, silicon nitride, titanium nitride, or gallium nitride is polished by supplying diamond abrasive grains between the surface and the polishing platen. (wrapping).
• diamond abrasive grains is likely to cause defects and distortion due to the occurrence and remaining of scratches and dents. Therefore, after lapping with diamond abrasive grains or instead of lapping, polishing with a polishing pad and a polishing composition has been studied.
• Documents disclosing this type of conventional technology include Patent Documents 1 and 2.
• Patent Documents 1 and 2 a polishing composition containing water and an oxidizing agent and containing no abrasive grains (Patent Document 1) or containing abrasive grains (Patent Document 2) is added with an alkali metal salt and a polishing accelerator as polishing accelerators. It has been proposed to improve the polishing rate by including/or an alkaline earth metal salt.
• the polishing removal rate can also be improved by setting polishing conditions such as increasing the load applied to the polishing surface during polishing to increase the processing pressure and speeding up the rotation of the surface plate of the polishing apparatus.
• polishing conditions such as increasing the load applied to the polishing surface during polishing to increase the processing pressure and speeding up the rotation of the surface plate of the polishing apparatus.
• the temperature rise of the polishing pad tends to increase during polishing using the polishing composition. If the temperature rise of the polishing pad can be suppressed, more severe processing conditions can be adopted, which is beneficial for further improving the polishing removal rate.
• An object of the present invention is to provide a polishing composition capable of suppressing a temperature rise of a polishing pad during polishing. Another related object is to provide a method of polishing an object to be polished using such a polishing composition.
• the polishing composition provided herein comprises water, an oxidizing agent A selected from compounds other than peroxides, a first metal salt selected from alkaline earth metal salts, and A second metal salt selected from salts with cations and anions of metals belonging to Groups 3-16.
• an oxidizing agent A selected from compounds other than peroxides
• a first metal salt selected from alkaline earth metal salts
• a second metal salt selected from salts with cations and anions of metals belonging to Groups 3-16.
• the oxidizing agent A is permanganate.
• the first metal salt is preferably nitrate.
• the combination of the alkaline earth metal nitrate as the first metal salt and the second metal salt can preferably exhibit the effect of suppressing the rise in pad temperature while improving the removal rate by polishing.
• the second metal salt is preferably an aluminum salt.
• the effect of suppressing the rise of the pad temperature while improving the removal rate by polishing can be preferably exhibited.
• the first metal salt and the second metal salt have the same anion species.
• the combination of the first metal salt and the second metal salt selected to have the same anion species tends to exhibit a better effect of suppressing the rise in the pad temperature.
• the ratio of the concentration C2 [mM] of the second metal salt to the concentration C1 [mM] of the first metal salt in the polishing composition is, for example, 0.1 ⁇ 10.
• the effect of using the first metal salt and the second metal salt in combination can be favorably exhibited.
• the polishing composition further contains abrasive grains.
• the use of abrasive grains can improve the polishing removal rate.
• the pad temperature tends to be higher than when using a polishing composition that does not contain abrasive grains, so the technology disclosed herein is applied. It is more effective to suppress the increase in pad temperature.
• the polishing composition disclosed herein is used, for example, for polishing materials with a Vickers hardness of 1500 Hv or more. In the polishing of such high-hardness materials, the effects of the technique disclosed herein can be favorably exhibited.
• the material with a Vickers hardness of 1500 Hv or higher is a non-oxide (ie, a compound that is not an oxide). In the polishing of a non-oxide material to be polished, the polishing removal rate improving effect of the polishing composition disclosed herein tends to be favorably exhibited.
• the polishing composition disclosed here is used, for example, for polishing silicon carbide.
• the effect of the technique disclosed herein can be preferably exhibited.
• a method for polishing an object to be polished includes the step of polishing an object to be polished using any one of the polishing compositions disclosed herein. According to such a polishing method, it is possible to increase the removal rate by polishing while suppressing the increase in pad temperature even when polishing an object made of a high-hardness material. As a result, the productivity of the target object (polished object, for example, a compound semiconductor substrate such as a silicon carbide substrate) obtained through polishing by the above polishing method can be enhanced.
• the polishing composition disclosed herein comprises an oxidizing agent A selected from compounds other than peroxides.
• the oxidizing agent A can exhibit the effect of improving the polishing removal rate in polishing a material to be polished (for example, a non-oxide material with high hardness such as silicon carbide).
• compounds that can be selected as the oxidizing agent A include permanganic acid, its salts sodium permanganate, potassium permanganate, and other permanganates; periodic acid, its salt sodium periodate; Periodic acids such as potassium periodate; iodic acids such as iodic acid and its salts such as ammonium iodate; bromates such as bromic acid and its salts potassium bromate; ferric acid and its salts potassium ferrate ferric acids such as; vanadic acids such as sodium acid and potassium vanadate; ruthenic acids such as perruthenic acid or salts thereof; molybdic acids such as molybdic acid and its salts ammonium molybdate and disodium molybdate; rhenic acids; tungstic acids such as tungstic acid and its salts disodium tungstate; chloric acids and perchlorates such as chloric acid and its salts, perchloric acid and its salt potassium perchlorate; .
• the oxidizing agent A one type of such compounds can be used alone or two or more types can be used in combination.
• the oxidizing agent A is preferably an inorganic compound from the viewpoint of performance stability of the polishing composition (for example, prevention of deterioration due to long-term storage).
• the polishing composition contains, as the oxidizing agent A, a composite metal oxide that is a salt of a cation selected from alkali metal ions and an anion selected from transition metal oxoacid ions.
• the composite metal oxide is effective in reducing the hardness of high-hardness materials such as silicon carbide and making the materials brittle.
• the polishing composition containing the above composite metal oxide as the oxidizing agent A the effect of improving the polishing removal rate and suppressing the pad temperature rise by using the first metal salt and the second metal salt in combination can be favorably exhibited.
• the above composite metal oxides may be used singly or in combination of two or more.
• transition metal oxoacid ions in the composite transition metal oxides include permanganate ions, ferrate ions, chromate ions, dichromate ions, vanadate ions, ruthenate ions, molybdate ions, and rhenate ions. ions, tungstate ions, and the like.
• the oxoacid of the 4th period transition metal element of the periodic table is more preferable.
• the fourth period transition metal elements in the periodic table include Fe, Mn, Cr, V, and Ti. Among them, Fe, Mn and Cr are more preferred, and Mn is even more preferred.
• the alkali metal ion in the composite transition metal oxide is preferably Na + or K + . Potassium permanganate may preferably be employed as oxidant A in some embodiments.
• the compound used as the oxidizing agent A is a salt (for example, permanganate)
• the compound may exist in the form of ions in the polishing composition.
• the polishing composition disclosed herein may or may not further contain an oxidizing agent other than the oxidizing agent A.
• the technology disclosed herein can be preferably practiced in a mode that does not substantially contain an oxidizing agent other than oxidizing agent A (for example, hydrogen peroxide).
• the concentration (content) of the oxidizing agent A in the polishing composition is not particularly limited, and can be appropriately set according to the purpose and mode of use of the polishing composition.
• the concentration of the oxidizing agent A is about 5 mM or more (that is, 0.005 mol/L or more).
• the concentration of the oxidizing agent A is preferably 10 mM or higher, more preferably 30 mM or higher, and may be 50 mM or higher, 70 mM or higher, or 90 mM or higher.
• the concentration of oxidizing agent A may be 120 mM or higher, 140 mM or higher, or 160 mM or higher.
• the concentration of the oxidizing agent A in the polishing composition is suitably about 2500 mM or less, preferably 2000 mM or less, more preferably 1700 mM or less, and 1500 mM or less. 1000 mM or less, 750 mM or less, 500 mM or less, 400 mM or less, or 300 mM or less. Reducing the concentration of the oxide A can be advantageous from the viewpoint of suppressing an increase in pad temperature. From this point of view, in some embodiments, the concentration of oxidant A may be 250 mM or less, 200 mM or less, 150 mM or less, or 120 mM or less.
• the polishing composition disclosed herein contains, in addition to oxidizing agent A, a first metal salt selected from alkaline earth metal salts.
• a first metal salt selected from alkaline earth metal salts.
• the first metal salt preferably contains one or more of Mg, Ca, Sr, and Ba as elements belonging to alkaline earth metals. Among them, one of Ca and Sr is preferable, and Ca is more preferable.
• the type of salt in the first metal salt is not particularly limited, and may be an inorganic acid salt or an organic acid salt.
• inorganic acid salts include hydrohalic acids such as hydrochloric acid, hydrobromic acid and hydrofluoric acid, and salts of nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid and phosphoric acid.
• organic acid salts include carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycic acid, butyric acid, citric acid, tartaric acid, trifluoroacetic acid; methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, toluene organic sulfonic acids such as sulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid and toluenephosphonic acid; organic phosphoric acids such as ethylphosphoric acid; and salts thereof.
• carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycic acid, butyric acid, citric acid, tartaric acid, trifluoroacetic acid
• salts of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid are preferable, and salts of hydrochloric acid and nitric acid are more preferable.
• the technology disclosed herein can be preferably practiced, for example, in a mode using an alkaline earth metal nitrate or chloride as the first metal salt.
• alkaline earth metal salts that may be alternatives for the first metal salt include chlorides such as magnesium chloride, calcium chloride, strontium chloride, barium chloride; magnesium bromide, calcium bromide, strontium bromide, barium bromide; Fluorides such as magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride; Nitrates such as magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate; Magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate carbonates such as magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate; magnesium acetate, calcium acetate, strontium acetate, barium acetate, magnesium benzoate, calcium benzoate, barium benzoate, magnesium citrate, citric carboxylates such as calcium phosphate, strontium citrate and barium citrate;
• the first metal salt is preferably a water-soluble salt.
• the first metal salt is preferably a compound different from the oxidizing agent A and is not oxidized by the oxidizing agent A.
• the oxidizing agent A and the first metal salt By appropriately selecting the oxidizing agent A and the first metal salt from this point of view, deactivation of the oxidizing agent A due to oxidation of the first metal salt by the oxidizing agent A can be prevented, and the polishing composition can be improved over time. It is possible to suppress performance deterioration (for example, decrease in polishing removal rate, etc.).
• a preferred combination of the oxidizing agent A and the first metal salt is a combination of an alkali metal permanganate and calcium nitrate.
• the concentration (content) of the first metal salt in the polishing composition is not particularly limited, and is appropriately set according to the purpose and mode of use of the polishing composition so as to achieve the desired effects. obtain.
• the concentration of the first metal salt may be, for example, approximately 1000 mM or less, 500 mM or less, or 300 mM or less. From the viewpoint of making it easier to effectively achieve both an improvement in polishing removal rate and a suppression of pad temperature rise when used in combination with the second metal salt, in some embodiments, the concentration of the first metal salt is 200 mM or less.
• the concentration is preferably 100 mM or less, more preferably 50 mM or less, may be 30 mM or less, may be 20 mM or less, or may be 10 mM or less.
• the lower limit of the concentration of the first metal salt may be, for example, 0.1 mM or more, preferably 0.5 mM or more, and preferably 1 mM or more, from the viewpoint of appropriately exhibiting the effects of using the first metal salt. More preferably, it may be 2.5 mM or more, or 5 mM or more.
• the technique disclosed herein can be preferably practiced, for example, in a mode in which the concentration of the first metal salt in the polishing composition is 0.5 mM to 100 mM or in a mode in which it is 1 mM to 50 mM.
• the concentration of the first metal salt in the polishing composition (a plurality of If the first metal salt of is included, their total concentration) C1 [mM] and the concentration of oxidant A (if multiple oxidants A are included, their total concentration) Cx [mM]
• the ratio (C1/Cx) is suitably about 0.0002 or more, preferably 0.001 or more, more preferably 0.005 or more, and may be 0.01 or more, or even 0.02 or more. good.
• C1/Cx can be, for example, 0.03 or greater, 0.05 or greater, or 0.07 or greater.
• C1/Cx is not particularly limited, it is suitable to be approximately 200 or less, and may be 100 or less, 75 or less, or 50 or less. In some preferred embodiments, C1/Cx may be 20 or less, 10 or less, 5 or less, 1 or less, 0.5 or less, 0.3 or less, or 0.1 or less. It's okay.
• concentration ratio (C1/Cx) between the first metal salt and the oxidizing agent A the use of a combination of the first metal salt and the second metal salt, which will be described later, preferably improves the polishing removal rate and suppresses the rise in the pad temperature.
• the polishing composition disclosed herein further contains a second metal salt in addition to the oxidizing agent A and the first metal salt.
• the second metal salt is selected from salts of cations and anions of metals belonging to groups 3 to 16 of the periodic table, and can be used singly or in combination of two or more.
• the cation of the second metal salt may be a transition metal, ie, a cation of a metal belonging to Groups 3 to 12 of the periodic table, or a poor metal, ie, a cation of a metal belonging to Groups 13 to 16 of the periodic table.
• the transition metal those belonging to groups 4 to 10 of the periodic table are preferable, those belonging to periods 4 to 6 of the periodic table are suitable, those belonging to periods 4 to 5 are preferable, and those belonging to periods 4 to 5 are preferable.
• Those belonging to 4 cycles are more preferable.
• the poor metal preferably belongs to groups 13 to 15 of the periodic table, more preferably belongs to groups 13 to 14, and preferably belongs to periods 3 to 5 of the periodic table. Those belonging to ⁇ 4 periods are more preferred, and poor metals belonging to the third period, ie aluminum, are particularly preferred.
• the second metal salt is preferably a salt of a cation and an anion of a metal having a pKa of about 10 or less for the hydrated metal ion.
• a second metal salt which is a salt of a cation and an anion, tends to have high stability against oxidation, and therefore tends to suppress deterioration in the performance of the polishing composition over time.
• a salt of a metal cation whose pKa of a hydrated metal ion is, for example, 8.0 or less, or 7.0 or less, or 6.0 or less, and an anion is preferably employed. obtain.
• metal cations having a hydrated metal ion pKa of 6.0 or less include Al 3+ (pKa of hydrated metal ion is 5.0), Cr 3+ (pKa of hydrated metal ion is 4.0), Fe 3+ (pKa is 2.2 ), but are not limited to these.
• the type of salt in the second metal salt is not particularly limited, and may be an inorganic acid salt or an organic acid salt.
• inorganic acid salts include hydrohalic acids such as hydrochloric acid, hydrobromic acid and hydrofluoric acid, and salts of nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid and phosphoric acid.
• organic acid salts include carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycic acid, butyric acid, citric acid, tartaric acid, trifluoroacetic acid; methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, toluene organic sulfonic acids such as sulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid and toluenephosphonic acid; organic phosphoric acids such as ethylphosphoric acid; and salts thereof.
• carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycic acid, butyric acid, citric acid, tartaric acid, trifluoroacetic acid
• salts of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid are preferable, and salts of hydrochloric acid, nitric acid and sulfuric acid are more preferable.
• the technique disclosed herein uses, for example, a salt of any one of Al 3+ , Cr 3+ , and Fe 3+ cations and nitrate ion (NO 3 ⁇ ) or chloride ion (Cl ⁇ ) as the second metal salt. It can be preferably implemented in the mode of use.
• the second metal salt is preferably a water-soluble salt.
• a water-soluble second metal salt By using a water-soluble second metal salt, a good surface with few defects such as scratches can be efficiently formed.
• the second metal salt is preferably a compound different from the oxidizing agent A and not oxidized by the oxidizing agent A.
• the oxidizing agent A and the second metal salt By appropriately selecting the oxidizing agent A and the second metal salt from this point of view, the deactivation of the oxidizing agent A due to the oxidation of the second metal salt by the oxidizing agent A can be prevented, and the polishing composition can be improved over time. It is possible to suppress performance deterioration (for example, decrease in polishing removal rate, etc.).
• Preferred combinations of the oxidizing agent A and the second metal salt include a combination of alkali metal permanganate and aluminum nitrate, and a combination of alkali metal permanganate and aluminum chloride.
• the first metal salt and the second metal salt are identical in their anionic species.
• the increase in pad temperature can be suppressed more effectively.
• the anionic species common to the first and second metal salts can be, for example, nitric acid, hydrochloric acid, phosphoric acid, and the like. From the viewpoint of obtaining a higher effect, a polishing composition in which both the first metal salt and the second metal salt are nitrates is particularly preferred.
• the concentration (content) of the second metal salt in the polishing composition is not particularly limited. obtain.
• the concentration of the second metal salt may be, for example, approximately 1000 mM or less, 500 mM or less, or 300 mM or less. From the viewpoint of making it easier to effectively achieve both an improvement in polishing removal rate and a suppression of pad temperature rise when used in combination with the first metal salt, in some embodiments, the concentration of the second metal salt is 250 mM or less.
• the concentration is preferably 200 mM or less, more preferably 100 mM or less, and may be 50 mM or less, 30 mM or less, 20 mM or less, or 10 mM or less.
• the lower limit of the concentration of the second metal salt may be, for example, 0.1 mM or more, and from the viewpoint of appropriately exhibiting the effect of using the second metal salt, it is advantageous to set it to 1 mM or more, and it is preferably 5 mM or more. It is preferably 7 mM or more (for example, 8 mM or more), and more preferably.
• the technique disclosed herein can also be preferably practiced, for example, in a mode in which the concentration of the second metal salt in the polishing composition is 10 mM or higher, 20 mM or higher, or 30 mM or higher.
• C1/C2 can range from 0.001 to 1000. From the viewpoint of making it easier to both improve the polishing removal rate and suppress the rise in the pad temperature, in some embodiments, C1/C2 is suitably about 0.005 or more, and 0.01 or more. (eg, 0.025 or more). Also, C1/C2 is suitably about 100 or less, preferably 50 or less, and more preferably 25 or less (for example, 10 or less).
• the concentration of the second metal salt (the total concentration when multiple second metal salts are included) C2 [mM] and the concentration of the oxidant A (the total when the multiple oxidants A are included) Concentration) Cx [mM] ratio (C2/Cx) is suitably about 0.0002 or more, preferably 0.001 or more, more preferably 0.005 or more, and 0.01 or more , or 0.02 or more.
• C2/Cx may be, for example, 0.03 or more, preferably 0.04 or more, 0.05 or more, or 0. 0.07 or more.
• the upper limit of C2/Cx is not particularly limited, it is suitable to be approximately 200 or less, and may be 100 or less, 75 or less, or 50 or less. In some preferred embodiments, C2/Cx may be 20 or less, 10 or less, 5 or less, 1 or less, 0.6 or less, 0.3 or less, 0.2 or less. It's okay.
• the use of the combination of the first metal salt and the second metal salt preferably improves the polishing removal rate and suppresses the rise in the pad temperature.
• the polishing composition contains abrasive grains.
• the abrasive grains in addition to the mainly chemical polishing action by the oxidizing agent A, the first metal salt and the second metal salt, the abrasive grains mainly exhibit mechanical polishing action. Thereby, a higher polishing removal rate can be achieved.
• the pad temperature tends to increase by including abrasive grains in the polishing composition, it is more effective to apply the technology disclosed herein to suppress the increase in pad temperature.
• the abrasive grains can be inorganic particles, organic particles, and organic-inorganic composite particles.
• oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, iron oxide particles; silicon nitride particles, nitride nitride particles such as boron particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate;
• Abrasive grains may be used singly or in combination of two or more.
• oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, zirconium oxide particles, manganese dioxide particles, and iron oxide particles are preferable because they can form a good surface.
• silica particles, alumina particles, zirconium oxide particles, chromium oxide particles, and iron oxide particles are more preferable, and silica particles and alumina particles are particularly preferable.
• silica particles or alumina particles as abrasive grains, the effect of suppressing the increase in pad temperature by applying the technology disclosed herein can be suitably exhibited.
• the phrase “substantially composed of X” or “substantially composed of X” with respect to the composition of abrasive grains means that the proportion of X in the abrasive grains (purity of X) is It means that it is 90% or more as a standard.
• the proportion of X in the abrasive grains is preferably 95% or more, more preferably 97% or more, even more preferably 98% or more, for example 99% or more.
• the average primary particle size of abrasive grains is not particularly limited. From the viewpoint of facilitating a desired removal rate by polishing while suppressing an increase in pad temperature, the average primary particle diameter of the abrasive grains may be, for example, 5 nm or more, suitably 10 nm or more, and preferably 20 nm or more. Yes, and may be 30 nm or more. From the viewpoint of improving the removal rate by polishing, in some embodiments, the average primary particle size of the abrasive grains may be 50 nm or more, 80 nm or more, 150 nm or more, 250 nm or more, or 350 nm or more.
• the average primary particle size of the abrasive grains can be, for example, 5 ⁇ m or less, preferably 3 ⁇ m or less, more preferably 1 ⁇ m or less, and may be 750 nm or less. , 500 nm or less. From the viewpoint of surface quality after polishing, in some embodiments, the average primary particle size of the abrasive grains may be 350 nm or less, 180 nm or less, 85 nm or less, or 50 nm or less.
• the specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex under the trade name “Flow Sorb II 2300”.
• the average secondary particle size of the abrasive grains may be, for example, 10 nm or more, preferably 50 nm or more, more preferably 100 nm or more, and may be 250 nm or more, and may be 400 nm or more, from the viewpoint of easily increasing the polishing removal rate. .
• the upper limit of the average secondary particle size of the abrasive grains is suitably about 10 ⁇ m or less from the viewpoint of sufficiently securing the number of particles per unit weight.
• the average secondary particle size is preferably 5 ⁇ m or less, more preferably 3 ⁇ m or less, for example, 1 ⁇ m or less.
• the average secondary particle size of the abrasive grains may be 600 nm or less, 300 nm or less, 170 nm or less, or 100 nm or less.
• the average secondary particle diameter of the abrasive grains for particles less than 500 nm, for example, volume average particle diameter (volume-based arithmetic mean diameter ; Mv).
• Particles of 500 nm or more can be measured as a volume average particle diameter by a pore electrical resistance method or the like using a model "Multisizer 3" manufactured by BECKMAN COULTER.
• alumina particles alumina abrasive grains
• they can be appropriately selected from among various known alumina particles and used.
• known alumina particles include alpha-alumina and intermediate alumina.
• intermediate alumina is a general term for alumina particles other than ⁇ -alumina, and specific examples include ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, and the like. be done.
• Alumina called fumed alumina typically fine alumina particles produced when an alumina salt is sintered at a high temperature
• fumed alumina typically fine alumina particles produced when an alumina salt is sintered at a high temperature
• alumina called colloidal alumina or alumina sol is also included in the above known alumina particles. From the viewpoint of workability, it preferably contains ⁇ -alumina.
• Alumina abrasive grains in the technology disclosed herein may contain one of such alumina particles alone or in combination of two or more.
• the proportion of alumina particles in the total abrasive grains is preferably 70% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more, and may be substantially 100% by weight.
• the particle size of the alumina abrasive grains is not particularly limited, and can be selected so that the desired polishing effect is exhibited.
• the average primary particle size of the alumina abrasive grains is preferably 50 nm or more, more preferably 80 nm or more, and may be 150 nm or more, 250 nm or more, or 300 nm or more.
• the upper limit of the average primary particle size of the alumina abrasive grains is not particularly limited, but from the viewpoint of suppressing the pad temperature rise, it is suitable to be approximately 5 ⁇ m or less, and from the viewpoint of surface quality after polishing, etc., it is 3 ⁇ m or less. is preferably 1 ⁇ m or less, and may be 750 nm or less, 500 nm or less, 400 nm or less, or 350 nm or less.
• the polishing composition disclosed herein contains abrasive grains made of a material other than the above alumina (hereinafter also referred to as non-alumina abrasive grains) within a range that does not impair the effects of the present invention. may further contain.
• non-alumina abrasive grains include oxide particles such as silica particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, iron oxide particles.
• oxide particles such as silica particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, iron oxide particles.
• Nitride particles such as silicon nitride particles and boron nitride particles; Carbide particles such as silicon carbide particles and boron carbide particles; Diamond particles; Granules are mentioned.
• the content of the non-alumina abrasive grains is, for example, 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight, of the total weight of the abrasive grains contained in the polishing composition. % or less.
• the polishing composition contains silica particles (silica abrasive grains) as abrasive grains.
• Silica abrasive grains can be appropriately selected from various known silica particles and used. Examples of such known silica particles include colloidal silica and dry process silica. Among them, colloidal silica is preferably used. Silica abrasive grains containing colloidal silica can suitably achieve good surface accuracy.
• the shape (outer shape) of silica abrasive grains may be spherical or non-spherical.
• specific examples of non-spherical silica abrasive grains include a peanut shape (that is, a peanut shell shape), a cocoon shape, a confetti shape, a rugby ball shape, and the like.
• the silica abrasive grains may be in the form of primary particles or in the form of secondary particles in which a plurality of primary particles are associated. Further, silica abrasive grains in the form of primary particles and silica abrasive grains in the form of secondary particles may be mixed. In a preferred embodiment, at least part of the silica abrasive grains are contained in the polishing composition in the form of secondary particles.
• the silica abrasive grains those having an average primary particle diameter of more than 5 nm can be preferably employed.
• the average primary particle size of the silica abrasive grains is preferably 15 nm or more, more preferably 20 nm or more, still more preferably 25 nm or more, and particularly preferably 30 nm or more.
• the upper limit of the average primary particle size of the silica abrasive grains is not particularly limited, it is suitable to be approximately 120 nm or less, preferably 100 nm or less, and more preferably 85 nm or less.
• silica abrasive grains with a BET diameter of 12 nm or more and 80 nm or less are preferable, and silica abrasive grains with a BET diameter of 15 nm or more and 75 nm or less are preferable from the viewpoint of achieving both polishing efficiency and surface quality at a higher level.
• the average secondary particle size of the silica abrasive grains is not particularly limited, it is preferably 20 nm or more, more preferably 50 nm or more, and still more preferably 70 nm or more from the viewpoint of polishing efficiency. From the viewpoint of obtaining a higher quality surface, the average secondary particle size of the silica abrasive grains is suitably 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less, still more preferably 130 nm or less, and particularly preferably 500 nm or less. is 110 nm or less (eg, 100 nm or less).
• the true specific gravity (true density) of silica particles is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more.
• the increase in the true specific gravity of silica particles tends to increase the physical polishing ability.
• the upper limit of the true specific gravity of silica particles is not particularly limited, it is typically 2.3 or less, for example, 2.2 or less, 2.0 or less, or 1.9 or less.
• a value measured by a liquid replacement method using ethanol as a replacement liquid can be employed.
• the shape (outer shape) of the silica particles is preferably spherical.
• the average value of the major axis/minor axis ratio of the particles is in principle 1.00 or more, and from the viewpoint of improving the removal rate by polishing, for example, it is 1.05 or more. There may be, and 1.10 or more may be sufficient.
• the average aspect ratio of the particles is suitably 3.0 or less, and may be 2.0 or less. From the viewpoint of improving the smoothness of the polished surface and reducing scratches, the average aspect ratio of the particles is preferably 1.50 or less, may be 1.30 or less, or may be 1.20 or less.
• the shape (outer shape) and average aspect ratio of the particles can be grasped, for example, by electron microscope observation.
• a scanning electron microscope (SEM) is used to extract the shapes of a predetermined number (eg, 200) of particles.
• the value obtained by dividing the length of the long side (the value of the major axis) by the length of the short side (the value of the minor axis) is the ratio of the major axis to the minor axis (aspect ratio).
• the average aspect ratio can be obtained by arithmetically averaging the aspect ratios of the predetermined number of particles.
• the polishing composition may further contain abrasive grains made of a material other than silica (hereinafter also referred to as non-silica abrasive grains).
• abrasive grains made of a material other than silica (hereinafter also referred to as non-silica abrasive grains).
• particles constituting such non-silica abrasive grains include alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, iron oxide particles, etc.
• oxide particles such as silicon nitride particles and boron nitride particles
• carbide particles such as silicon carbide particles and boron carbide particles
• diamond particles carbonates such as calcium carbonate and barium carbonate; and particles composed of
• the content of the non-silica abrasive grains is, for example, 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight, based on the total weight of the abrasive grains contained in the polishing composition. % or less.
• the content of abrasive grains (e.g., silica abrasive grains, alumina abrasive grains, etc.) in the polishing composition disclosed herein is suitably less than 5% by weight from the viewpoint of suppressing pad temperature rise, Advantageously less than 3 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, even less than 0.3 wt%, less than 0.2 wt% It's okay.
• the abrasive content in the polishing composition may be 0.1 wt% or less or less than 0.1 wt%, and may be 0.05 wt% or less or less than 0.05 wt%, It may be 0.04 wt% or less or less than 0.04 wt%, or 0.03 wt% or less or less than 0.03 wt%.
• the lower limit of the abrasive grain content is not particularly limited, and may be, for example, 0.000001% by weight or more (that is, 0.01 ppm or more).
• the content of abrasive grains in the polishing composition may be 0.00001% by weight or more, 0.0001% by weight or more, or 0.001% by weight. % or more, 0.002% by weight or more, or 0.005% by weight or more.
• the polishing composition disclosed herein contains multiple types of abrasive grains
• the content of abrasive grains in the polishing composition refers to the total content of the multiple types of abrasive grains.
• the polishing composition disclosed herein preferably does not substantially contain diamond particles as particles.
• the high hardness of diamond particles can be a limiting factor in improving smoothness.
• diamond particles are generally expensive, they are not an advantageous material in terms of cost effectiveness, and from a practical standpoint, less dependence on expensive materials such as diamond particles may be used.
• the particles substantially do not contain diamond particles means that the ratio of diamond particles to the total particles is 1% by weight or less, more preferably 0.5% by weight or less, and typically 0.1% by weight or less. and includes the case where the proportion of diamond particles is 0% by weight. In such a mode, the application effects of the present invention can be favorably exhibited.
• the relationship between the concentration of the oxidizing agent A and the content of the abrasive grains is not particularly limited, and is appropriately adjusted so as to achieve the desired effect according to the purpose and mode of use. can be set.
• the ratio of the concentration Cx [mM] of the oxidizing agent A to the content W1 [% by weight] of the abrasive grains, that is, Cx/W1 can be, for example, 5 or more, suitably 50 or more, and 100 or more. and preferably 200 or more. The larger the Cx/W1, the greater the contribution of chemical polishing to the contribution of mechanical polishing.
• Cx/W1 may be 300 or more, 500 or more, 700 or more, 1000 or more, 1500 or more, 3000 or more, 5500 or more, 7500 or more It's okay.
• the upper limit of Cx/W1 is not particularly limited, but from the viewpoint of the storage stability of the polishing composition, for example, it can be about 100,000 or less, 75,000 or less, 50,000 or less, 20,000 or less, or 10,000. It may be less than or equal to 9000 or less.
• Cx/W1 may be 7000 or less, 5000 or less, or 3000 or less.
• Cx is the numerical value when the concentration of the oxidizing agent A in the polishing composition is expressed in units of "mM”
• W1 is the abrasive in the polishing composition. It represents the numerical part when the grain content is expressed in the unit of "% by weight”
• both Cx and W1 are dimensionless numbers.
• the relationship between the concentration of the first metal salt and the content of the abrasive grains is not particularly limited, and is appropriately determined according to the purpose and mode of use so as to achieve the desired effect.
• the ratio of the concentration C1 [mM] of the first metal salt to the content W1 [% by weight] of the abrasive grains, that is, C1/W1 can be, for example, 5 or more, preferably 10 or more, and 30 or more. More preferably, it may be 50 or more, or 80 or more. As C1/W1 increases, the contribution of chemical polishing tends to increase relative to the contribution of mechanical polishing.
• C1/W1 may be 100 or greater, 150 or greater, 200 or greater, 300 or greater, or 500 or greater.
• the upper limit of C1/W1 is not particularly limited, it can be, for example, about 5000 or less, may be 2500 or less, or may be 1000 or less from the viewpoint of the storage stability of the polishing composition.
• C1/W1 may be 900 or less, 700 or less, or 500 or less.
• C1 is the numerical value when the concentration of the first metal salt in the polishing composition is expressed in units of "mM”
• W1 is the concentration in the polishing composition. It represents the numerical part when the content of abrasive grains is expressed in the unit of "% by weight”
• both C1 and W1 are dimensionless numbers.
• the relationship between the concentration of the second metal salt and the content of the abrasive grains is not particularly limited, and is appropriately determined according to the purpose and mode of use so as to achieve the desired effect.
• the ratio of the concentration C2 [mM] of the second metal salt to the content W1 [% by weight] of the abrasive grains, that is, C2/W1 can be, for example, 5 or more, preferably 10 or more, and 30 or more. More preferably, it may be 50 or more, or 80 or more.
• C2/W1 becomes larger, the effect of suppressing the pad temperature rise by using the combination of the first metal salt and the second metal salt can be preferably exhibited.
• C2/W1 may be 150 or greater, 300 or greater, 500 or greater, or 800 or greater.
• the upper limit of C2/W1 is not particularly limited, but from the viewpoint of the storage stability of the polishing composition, it can be, for example, about 10000 or less, 5000 or less, or 2500 or less. In some embodiments, C2/W1 may be 1000 or less, 800 or less, or 600 or less.
• C2/W1 is the numerical value when the concentration of the second metal salt in the polishing composition is expressed in units of "mM”
• W1 is the concentration of the second metal salt in the polishing composition. It represents the numerical portion when the content of abrasive grains is expressed in the unit of "% by weight”
• both C2 and W1 are dimensionless numbers.
• the polishing composition disclosed here can also be preferably implemented in a mode that does not contain abrasive grains.
• the effect of improving the polishing removal rate and suppressing the pad temperature rise by using the first metal salt and the second metal salt in combination is exhibited more effectively.
• the polishing composition disclosed herein contains water.
• water ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like can be preferably used.
• the polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary.
• an organic solvent lower alcohol, lower ketone, etc.
• 90% by volume or more of the solvent contained in the polishing composition is water, preferably 95% by volume or more is water, and more preferably 99 to 100% by volume is water. preferable.
• the polishing composition may contain an acid, if necessary, for the purpose of adjusting pH and improving the polishing removal rate.
• Both inorganic acids and organic acids can be used as acids.
• inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, and the like.
• Examples of organic acids include aliphatic carboxylic acids such as formic acid, acetic acid and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, and succinic acid. acids, organic sulfonic acids, organic phosphonic acids, and the like.
• polishing compositions disclosed herein may be a composition substantially free of acid.
• the polishing composition may optionally contain a basic compound for purposes such as pH adjustment and polishing removal rate improvement.
• the basic compound refers to a compound that has the function of increasing the pH of the polishing composition when added to the composition.
• Examples of basic compounds include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; salts; ammonia; quaternary ammonium compounds, such as quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; An organic acid salt etc. are mentioned.
• a basic compound can be used individually by 1 type or in combination of 2 or more types. When a basic compound is used, the amount used is not particularly limited, and can be set according to the purpose of use (for example, pH adjustment). Alternatively, some embodiments of the polishing composition disclosed herein may be a composition substantially free of basic compounds.
• the polishing composition disclosed herein contains a chelating agent, a thickener, a dispersant, a surface protective agent, a wetting agent, a surfactant, an anticorrosive agent, an antiseptic agent, an antiseptic agent, as long as the effects of the present invention are not impaired.
• Known additives that can be used in polishing compositions for example, polishing compositions used for polishing high-hardness materials such as silicon carbide), such as mold agents, may be further contained as necessary.
• the content of the additive may be appropriately set according to the purpose of addition, and detailed description is omitted because it does not characterize the present invention.
• the pH of the polishing composition is suitably about 1-12. When the pH is within the above range, a practical polishing removal rate is likely to be achieved.
• the pH may be 12.0 or less, 11.0 or less, 10.0 or less, 9.0 or less, less than 9.0, or 8.0 or less.
• it may be less than 8.0, it may be 7.0 or less, it may be less than 7.0, or it may be 6.0 or less.
• the pH of the polishing composition is preferably 6. .0, may be 5.0 or less, may be less than 5.0, may be 4.0 or less, or may be less than 4.0.
• the pH may be, for example, 1.0 or higher, 1.5 or higher, 2.0 or higher, or 2.5 or higher.
• each component contained in the polishing composition may be mixed using a well-known mixing device such as a blade stirrer, an ultrasonic disperser, or a homomixer.
• the manner in which these components are mixed is not particularly limited. For example, all the components may be mixed at once, or they may be mixed in an appropriately set order.
• the polishing composition disclosed herein may be a one-component type or a multi-component type including a two-component type.
• part A containing some of the components of the polishing composition (for example, components other than water) and part B containing the remaining components may be mixed and used for polishing an object to be polished.
• part A containing some of the components of the polishing composition for example, components other than water
• part B containing the remaining components may be mixed and used for polishing an object to be polished.
• may be configured to These are, for example, stored separately before use, and can be mixed at the time of use to prepare a one-component polishing composition.
• the object to be polished with the polishing composition disclosed herein is not particularly limited.
• the polishing composition disclosed herein can be applied to polishing a substrate having a surface composed of a compound semiconductor material, that is, a compound semiconductor substrate.
• the constituent material of the compound semiconductor substrate is not particularly limited, and examples thereof include II-VI group compound semiconductors such as cadmium telluride, zinc selenide, cadmium sulfide, mercury cadmium telluride, and cadmium zinc telluride; gallium nitride and gallium arsenide.
• the object to be polished may be made of a plurality of these materials.
• the polishing compositions disclosed herein can be applied to polish substrates having surfaces composed of non-oxide (ie, non-oxide) chemical semiconductor materials. In the polishing of a substrate having a surface composed of a non-oxide chemical semiconductor material, the polishing promoting effect of the oxidizing agent contained in the polishing composition disclosed herein tends to be favorably exhibited.
• the polishing composition disclosed herein can be preferably used for polishing the surface of an object having a Vickers hardness of 500 Hv or more, for example.
• the Vickers hardness is preferably 700 Hv or higher, for example, 1000 Hv or higher, or 1500 Hv or higher.
• the Vickers hardness of the material to be polished may be 1800 Hv or higher, 2000 Hv or higher, or 2200 Hv or higher.
• the upper limit of the Vickers hardness of the surface of the object to be polished is not particularly limited. In this specification, Vickers hardness can be measured based on JIS R 1610:2003.
• the international standard corresponding to the above JIS standard is ISO 14705:2000.
• Materials having a Vickers hardness of 1500 Hv or more include silicon carbide, silicon nitride, titanium nitride, and gallium nitride.
• An object to be polished in the technology disclosed herein may have a single crystal surface of the mechanically and chemically stable material described above.
• the surface of the object to be polished is preferably made of either silicon carbide or gallium nitride, and more preferably made of silicon carbide.
• Silicon carbide is expected to be a compound semiconductor substrate material that has low power loss and is excellent in heat resistance, etc., and the improvement in productivity by improving the removal rate by polishing has a particularly large practical advantage.
• the technology disclosed herein can be particularly preferably applied to polishing the surface of silicon carbide single crystals.
• the polishing composition disclosed herein can be used for polishing an object to be polished, for example, in a mode including the following operations. That is, a polishing liquid (slurry) containing any one of the polishing compositions disclosed herein is prepared. Preparing the polishing liquid may include performing operations such as concentration adjustment (for example, dilution) and pH adjustment on the polishing composition to prepare the polishing liquid. Alternatively, the above polishing composition may be used as it is as a polishing liquid. In the case of a multi-component polishing composition, preparing the polishing liquid includes mixing the agents, diluting one or more agents before the mixing, and diluting the mixture, and the like.
• the polishing liquid is supplied to the object to be polished, and the object is polished by a normal method performed by those skilled in the art.
• a method in which an object to be polished is set in a general polishing apparatus, and the polishing liquid is supplied to the surface of the object to be polished through the polishing pad of the polishing apparatus.
• the polishing pad is pressed against the surface to be polished of the object to be polished, and the two are relatively moved (for example, rotationally moved). Polishing of the object to be polished is completed through such a polishing process.
• the content and content ratio described above for each component that can be contained in the polishing composition in the technique disclosed herein is typically the same when actually supplied to the object to be polished (i.e., It means the content and the ratio of the content in the polishing composition (at the point of use), and can therefore be read as the content and the ratio of the content in the polishing liquid.
• a polishing method for polishing an object to be polished typically, a material to be polished
• the polishing method is characterized by including the step of polishing an object to be polished using the polishing composition disclosed herein.
• a polishing method according to a preferred embodiment includes a step of performing preliminary polishing (preliminary polishing step) and a step of performing finish polishing (finish polishing step).
• the pre-polishing step is a polishing step placed immediately before the final polishing step.
• the preliminary polishing process may be a one-stage polishing process, or may be a multi-stage polishing process of two or more stages.
• the finish polishing step referred to here is a step of performing finish polishing on an object to be polished that has been preliminarily polished, and is the final polishing step performed using a polishing slurry containing abrasive grains ( That is, it refers to the polishing step that is arranged on the most downstream side.
• the polishing composition disclosed herein may be used in the preliminary polishing step, may be used in the finish polishing step, or may be used in the preliminary polishing step. It may be used both in the process and in the final polishing process.
• Preliminary polishing and finish polishing can be applied to both single-side polishing and double-side polishing.
• a single-sided polishing apparatus an object to be polished is attached to a ceramic plate with wax, or the object to be polished is held using a holder called a carrier, and a polishing pad is pressed against one side of the object to be polished while supplying a polishing composition.
• One side of the object to be polished is polished by relatively moving both of them. The movement is, for example, rotational movement.
• a holder called a carrier is used to hold an object to be polished, and while a polishing composition is supplied from above, a polishing pad is pressed against the opposite surface of the object to be polished, and they are rotated in relative directions. Thus, both surfaces of the object to be polished are polished simultaneously.
• polishing conditions are not limited to specific conditions because they are appropriately set based on the type of material to be polished, the target surface properties (specifically, smoothness), polishing removal rate, and the like.
• the polishing composition disclosed herein can be used in a wide range of pressure, for example, 10 kPa or more and 150 kPa or less.
• the processing pressure may be, for example, 20 kPa or more, 30 kPa or more, or 40 kPa or more, or 100 kPa or less, or 80 kPa. or 60 kPa or less.
• the polishing composition disclosed herein can be preferably used for polishing under processing conditions of, for example, 30 kPa or higher or higher, and can increase the productivity of the target object (polished object) obtained through such polishing.
• the processing pressure here is synonymous with polishing pressure.
• the polishing pad used in each polishing step disclosed here is not particularly limited.
• any of non-woven fabric type, suede type, and rigid polyurethane foam type may be used.
• non-woven type polishing pads may be preferably employed.
• the effect of suppressing the temperature rise of the pad which is the effect of the technology disclosed herein, is preferably exhibited.
• the polishing pad used in the technology disclosed herein is a polishing pad that does not contain abrasive grains.
• a polishing object polished by the method disclosed herein is typically washed after polishing. This washing can be performed using a suitable washing liquid.
• the washing liquid to be used is not particularly limited, and a known and commonly used washing liquid can be appropriately selected and used.
• the polishing method disclosed herein may include any other steps in addition to the preliminary polishing step and the final polishing step.
• Such steps include a mechanical polishing step and a lapping step performed prior to the pre-polishing step.
• the mechanical polishing step the object to be polished is polished using a liquid in which diamond abrasive grains are dispersed in a solvent.
• the dispersion does not contain an oxidizing agent.
• the lapping step is a step of polishing by pressing the surface of a polishing platen, for example, a cast iron platen against the object to be polished. Therefore, no polishing pad is used in the lapping process.
• the lapping process is typically performed by supplying abrasive grains between the polishing platen and the object to be polished.
• the abrasive grains are typically diamond abrasive grains.
• the polishing method disclosed herein may include additional steps before the preliminary polishing step or between the preliminary polishing step and the final polishing step. Additional steps are, for example, cleaning steps and polishing steps.
• the technology disclosed herein may include a method for producing a polished object including a polishing step by any of the polishing methods described above, and provision of a polished object produced by the method.
• the above method for producing a polished product is, for example, a method for producing a silicon carbide substrate. That is, according to the technology disclosed herein, the production of a polished object including polishing an object having a surface made of a high-hardness material by applying any of the polishing methods disclosed herein. A method and an abrasive article made by the method are provided. According to the manufacturing method described above, a substrate manufactured through polishing, such as a silicon carbide substrate, can be efficiently provided.
• Example A1 Alumina abrasive grains, potassium permanganate as an oxidizing agent A, calcium nitrate as a first metal salt, aluminum nitrate as a second metal salt, and deionized water are mixed to reduce the alumina abrasive grains to zero.
• Alumina abrasive grains, potassium permanganate as an oxidizing agent A, calcium nitrate, and deionized water were mixed to obtain 0.1% alumina abrasive grains, 181 mM potassium permanganate (in terms of Mn), and nitric acid.
• a polishing composition containing calcium (calculated as Ca) at a concentration of 9.52 mM was prepared.
• Comparative Example A2 Alumina abrasive grains, potassium permanganate as an oxidizing agent A, aluminum nitrate, and deionized water were mixed to obtain 0.1% alumina abrasive grains, 181 mM potassium permanganate (in terms of Mn), and nitric acid.
• Example A1 Comparative Examples A1 and A2
• ⁇ -alumina abrasive grains having an average primary particle diameter of 310 nm were used as the alumina abrasive grains.
• the pH of the polishing composition according to each example was adjusted to 2.5 using nitric acid.
• a SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive grains.
• the pre-polished SiC wafer was used as an object to be polished, and the polishing composition according to each example was used as it was as a polishing liquid to polish the object to be polished under the following polishing conditions.
• Polishing device Fujikoshi Machine Industry Co., model "RDP-500” Polishing pad: "SUBA800XY” manufactured by Nitta Haas (non-woven fabric type) Processing pressure: 44.1 kPa Surface plate rotation speed: 120 rotations/minute Head rotation speed: 120 rotations/minute Supply rate of polishing liquid: 20 mL/minute How to use polishing liquid: Throw away Polishing time: 15 minutes
• Object to be polished 4-inch SiC wafer (conduction type : n-type, crystal-type 4H-SiC, off-angle of main surface (0001) with respect to C-axis: 4°), 1 sheet/batch Temperature of polishing liquid: 23°C
• the obtained polishing removal rate was converted into a relative value when Comparative Example A1 was taken as 100%. Based on the relative values, the polishing removal rate was evaluated according to the following 5 levels, and shown in Table 1.
• a rating of A means that the polishing removal rate is improved by more than 1.15 times to 1.5 times that of Comparative Example A1.
• AA greater than 150% and 200% or less
• Pad temperature The temperature of the polishing pad was measured during polishing under the above polishing conditions.
• a template using a backing material made of suede material was used as the wafer holding portion, and the wafer was attached so that the protrusion height of the wafer was 100 ⁇ m or more.
• the wafer was kept moist against the suede material.
• the pad temperature the value output from the pad temperature measuring device (infrared thermal radiation thermometer) attached to the polishing apparatus was used as it was. The measurement was performed from 10 minutes to 15 minutes after the start of polishing, and the average temperature during that period was taken as the pad temperature during polishing with the polishing composition according to each example.
• ⁇ T [° C.] (pad temperature of Comparative Example A1) ⁇ (pad temperature of each example);
• the effect of suppressing pad rise was evaluated according to the following five levels, and the results are shown in Table 1.
• a ⁇ T of 0° C. or less (evaluation D) means that the pad temperature is the same as or higher than that of Comparative Example A1.
• AA: ⁇ T is 2.5°C or more
• A: ⁇ T is 2.0°C or more and less than 2.5°C
• B: ⁇ T is 1.2°C or more and less than 2.0°C C: ⁇ T is more than 0°C and less than 1.2°C
• ⁇ T is 0°C or less
• Comparative Example A0 a polishing composition having a composition from Comparative Example A1 excluding calcium nitrate was prepared, and the polishing removal rate and pad temperature were measured and evaluated in the same manner. was about 1.2 times that of Comparative Example A0, and the pad temperature of Comparative Example A1 was 1.1° C. higher than that of Comparative Example A0. That is, according to Comparative Example A1, the polishing removal rate was improved compared to Comparative Example A0, but the pad temperature also increased.
• Example A1 containing a combination of calcium nitrate as the first metal salt and aluminum nitrate as the second metal salt exhibited a higher The pad temperature could be significantly reduced while further improving the polishing removal rate.
• Example B1 Potassium permanganate as the oxidizing agent A, calcium nitrate as the first metal salt, aluminum nitrate as the second metal salt, and deionized water were mixed to obtain 105 mM potassium permanganate (in terms of Mn). , calcium nitrate (calculated as Ca) and aluminum nitrate (calculated as Al) at concentrations of 7.6 mM and 38 mM, respectively, and containing no abrasive grains.
• Example B1 The pH of the polishing compositions of Example B1 and Comparative Example B1 was 3.4-3.5.
• a SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive grains.
• the pre-polished SiC wafer was used as an object to be polished, and the polishing composition according to each example was used as it was as a polishing liquid to polish the object to be polished under the following polishing conditions.
• Polishing device Fujikoshi Machine Industry Co., model "RDP-500” Polishing pad: "SUBA800XY” manufactured by Nitta Haas (non-woven fabric type) Processing pressure: 29.4 kPa Surface plate rotation speed: 100 rotations/minute Head rotation speed: 100 rotations/minute Supply rate of polishing liquid: 20 mL/minute How to use polishing liquid: Throw away Polishing time: 1 hour
• Object to be polished 2-inch SiC wafer (conduction type : n-type, crystal-type 4H-SiC, off-angle of main surface (0001) with respect to C-axis: 4°), 1 sheet/batch Temperature of polishing liquid: 23°C
• the obtained polishing removal rate was converted into a relative value when Comparative Example B1 was taken as 100%. Based on the relative values, the polishing removal rate was evaluated according to the following five levels, and shown in Table 2.
• a rating of AA means that the polishing removal rate is more than 1.5 times to 2 times higher than that of Comparative Example B1. AA: greater than 150% and 200% or less A: greater than 115% and 150% or less B: 85% or more and 115% or less C: 50% or more and less than 85% D: less than 50%
• the temperature of the polishing pad during polishing under the above polishing conditions was measured using a pad temperature measuring device (infrared thermal radiation thermometer) attached to the polishing apparatus.
• the wafer protrusion height was set to 200 ⁇ m or more, and the average temperature from 5 minutes to 55 minutes after the start of polishing was taken as the pad temperature during polishing with the polishing composition according to each example.
• the same procedures as in Experimental Example 1 were carried out.
• ⁇ T [° C.] (pad temperature of Comparative Example B1) ⁇ (pad temperature of each example);
• the effect of suppressing pad rise was evaluated according to the following five levels, and the results are shown in Table 2.
• a ⁇ T of 0° C. or less (evaluation D) means that the pad temperature is the same as or higher than that of Comparative Example B1.
• AA: ⁇ T is 2.5°C or more
• A: ⁇ T is 2.0°C or more and less than 2.5°C
• B: ⁇ T is 1.2°C or more and less than 2.0°C C:
• ⁇ T is more than 0°C and less than 1.2°C
• ⁇ T is 0°C or less
• Comparative Example B0 a polishing composition having a composition from Comparative Example B1 excluding calcium nitrate was prepared, and the polishing removal rate and pad temperature were measured and evaluated in the same manner. was about three times that of Comparative Example B0, and the pad temperature of Comparative Example B1 was 1° C. higher than that of Comparative Example B0. That is, according to Comparative Example B1, the polishing removal rate was improved compared to Comparative Example B0, but the pad temperature also increased.
• Example B1 As shown in Table 2, according to the polishing composition of Example B1 containing a combination of calcium nitrate as the first metal salt and aluminum nitrate as the second metal salt, compared to the polishing composition of Comparative Example B1, The pad temperature could be significantly reduced while further improving the polishing removal rate. Further, as Example B2, a polishing composition having a composition in which aluminum nitrate in the polishing composition of Example B1 was replaced with aluminum chloride having the same concentration (in terms of Al) was prepared, and measurement and evaluation were performed in the same manner. Similar to Example B1, the effect of lowering the pad temperature was observed as compared with Comparative Example B1, and a polishing removal rate equivalent to that of Example B1 was obtained. In comparison between Example B1 and Example B2, Example B1, in which the anion species of the first metal salt and the second metal salt are the same, showed a larger drop in pad temperature.
• Example C1 Silica abrasive grains, potassium permanganate as oxidizing agent A, calcium nitrate as the first metal salt, aluminum nitrate as the second metal salt, and deionized water are mixed to reduce the silica abrasive grains to zero.
• Comparative Example C1 Silica abrasive grains, potassium permanganate as oxidizing agent A, calcium nitrate, and deionized water were mixed to obtain 0.1% silica abrasive grains and 189.8 mM potassium permanganate (in terms of Mn). , and a polishing composition containing calcium nitrate (calculated as Ca) at a concentration of 10 mM.
• silica abrasive grains Silica abrasive grains, potassium permanganate as oxidizing agent A, aluminum nitrate, and deionized water were mixed to obtain 0.1% silica abrasive grains and 189.8 mM potassium permanganate (in terms of Mn). and aluminum nitrate (in terms of Al) at a concentration of 30 mM.
• colloidal silica having an average primary particle diameter of 35 nm was used as the silica abrasive grains.
• the pH of the polishing composition according to each example was adjusted to 3.0 using nitric acid.
• a SiC wafer was pre-polished using a pre-polishing composition containing alumina abrasive grains.
• the pre-polished SiC wafer was used as an object to be polished, and the polishing composition according to each example was used as it was as a polishing liquid to polish the object to be polished under the following polishing conditions.
• Polishing device Fujikoshi Machine Industry Co., model "RDP-500” Polishing pad: "SUBA800XY” manufactured by Nitta Haas (non-woven fabric type) Processing pressure: 44.1 kPa Surface plate rotation speed: 120 rotations/minute Head rotation speed: 120 rotations/minute Supply rate of polishing liquid: 20 mL/minute How to use polishing liquid: Throw away Polishing time: 15 minutes
• Object to be polished 4-inch SiC wafer (conduction type : n-type, crystal-type 4H-SiC, off-angle of main surface (0001) with respect to C-axis: 4°), 1 sheet/batch Temperature of polishing liquid: 23°C
• the obtained polishing removal rate was converted into a relative value when Comparative Example C1 was taken as 100%. Based on the relative values, the polishing removal rate was evaluated according to the following 5 levels, and shown in Table 3.
• a rating of AA means that the polishing removal rate is improved by more than 1.5 times relative to Comparative Example C1. AA: greater than 150% A: greater than 115% and 150% or less B: 85% or more and 115% or less C: 50% or more and less than 85% D: less than 50%
• Pad temperature The temperature of the polishing pad during polishing under the above polishing conditions was measured using a pad temperature measuring device (infrared thermal radiation thermometer) attached to the polishing apparatus. In the measurement, the wafer protrusion height was set to 200 ⁇ m or more, and the average temperature from 5 minutes to 55 minutes after the start of polishing was taken as the pad temperature during polishing with the polishing composition according to each example. Other than that, it was carried out in the same manner as in Experimental Example 1.
• ⁇ T [° C.] (pad temperature of Comparative Example C1) ⁇ (pad temperature of each example);
• the effect of suppressing pad rise was evaluated according to the following five levels, and the results are shown in Table 3.
• a ⁇ T of 0° C. or less (evaluation D) means that the pad temperature is the same as or higher than that of Comparative Example C1.
• AA: ⁇ T is 2.5°C or more
• A: ⁇ T is 2.0°C or more and less than 2.5°C
• B: ⁇ T is 1.2°C or more and less than 2.0°C C:
• ⁇ T is more than 0°C and less than 1.2°C
• ⁇ T is 0°C or less
• Comparative Example C0 a polishing composition having a composition from Comparative Example C1 excluding calcium nitrate was prepared, and the polishing removal rate and pad temperature were measured and evaluated in the same manner. was about 1.2 times that of Comparative Example C0, and the pad temperature of Comparative Example C1 was 1°C higher than that of Comparative Example C0. That is, according to Comparative Example C1, the polishing removal rate was improved compared to Comparative Example C0, but the pad temperature also increased.
• Example C2 As shown in Table 3, the polishing composition of Example C1 containing a combination of calcium nitrate as the first metal salt and aluminum nitrate as the second metal salt exhibited a higher The pad temperature could be greatly reduced while further improving the polishing removal rate. Further, as Example C2, a polishing composition having a composition in which aluminum nitrate in the polishing composition of Example C1 was replaced with aluminum chloride having the same concentration (in terms of Al) was prepared, and measurement and evaluation were performed in the same manner. Similar to Example C1, the effect of lowering the pad temperature was observed as compared with Comparative Example C1, and a polishing removal rate equivalent to that of Example C1 was obtained. In comparison between Example C1 and Example C2, Example C1, in which the anion species of the first metal salt and the second metal salt are the same, showed a greater decrease in pad temperature.

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• 2022
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