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
  • H01L21/26—Bombardment with radiation
  • H01L21/263—Bombardment with radiation with high-energy radiation
  • H01L21/265—Bombardment with radiation with high-energy radiation producing ion implantation
  • H01L21/26506—Bombardment with radiation with high-energy radiation producing ion implantation in group IV semiconductors
  • H01L21/26533—Bombardment with radiation with high-energy radiation producing ion implantation in group IV semiconductors of electrically inactive species in silicon to make buried insulating layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
  • H01L21/76—Making of isolation regions between components
  • H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
  • H01L21/7624—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology
  • H01L21/76251—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques
  • H01L21/76254—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond

Definitions

• the present invention relates to a method for manufacturing an SOI wafer having an SOI (Silicon insul nator) structure in which a silicon layer is formed on an insulator, and an S ⁇ I wafer manufactured by the method.
• SOI Silicon insul nator
• SOI wafers which have an SOI structure in which a silicon layer (SOI layer) is formed on an insulator, excel in high-speed, low power consumption, high withstand voltage, environmental resistance, etc. of devices.
• SOI layer silicon layer
• Typical manufacturing methods for this SOI wafer include the SIMOX method, in which oxygen ions are implanted into a silicon wafer at a high concentration and then heat treated at a high temperature to form an oxide film inside the wafer.
• the bonding method is a bonding method for forming a SOI layer; an oxide film is formed on at least one of the wafer and the base wafer serving as a supporting substrate, and the bond wafer and the base wafer are bonded via the oxide film. Later, by reducing the thickness of the bond wafer, a method of manufacturing an SOI wafer in which an SOI layer is formed on a buried oxide film that is an insulator. .
• the manufacturing method of the SOI wafer using this bonding method is also called a grinding and polishing method, a PAC, a plasma-assisted chemical etching method, and an ion implantation delamination method (smart cut (registered trademark) method).
• Patent No. 30482801-), ELT RAN method, etc. are known (Silicon Science, edited by UCS Semiconductor Technology Research Group, Realize Inc., p.44-3 — 49) 6).
• the ion implantation separation method will be described with reference to FIG. First, Prepare two silicon wafers, silicon wafer 11 and bondue wafer 12 (step (a ')). Next, after an oxide film 13 is formed on at least one of these wafers (in this case, a pond wafer) (step (b ′)), hydrogen ions or rare gas ions are implanted into the bond wafer 12. An ion-implanted layer 14 is formed inside the bond wafer 12 (step (c ′)). Then, after bonding the surface of the bonded wafer 12 with the implanted ion to the base wafer 11 via the oxide film 13 (step (d ')), the ion-implanted layer 14 is subjected to a peeling heat treatment.
• the thin film is formed by peeling the bonder 12 to form the S ⁇ I layer 15 (step (e ′)), and then the bonding between the wafers is further strengthened.
• the SOI wafer 16 can be manufactured by applying a bonding heat treatment or a mirror polishing called a touch polish with an extremely small polishing allowance (process ( ⁇ ′)).
• the polishing allowance is not uniform.
• an SII layer is formed by an ion implantation delamination method, a bonding heat treatment is performed, and a mirror polishing is performed.
• a technique for performing high-temperature heat treatment in a hydrogen or Ar atmosphere to reduce the surface roughness and crystal defects of the SII layer of the SIII wafer without polishing is disclosed. .
• SOI wafers with thin buried oxide films have improved the crystallinity of SOI layers. It has been demanded.
• An oxide film to be formed on at least one of the bond wafer and the base wafer is formed so as to have the same thickness as a desired buried oxide film, and then the wafers are bonded together to manufacture an SOI wafer. I have.
• an SOI layer having a buried oxide film As shown in Fig. 3, when the wafer is manufactured and subjected to a delamination heat treatment after bonding the wafers, a silicon oxide layer 32 and an SOI layer 33 laminated on the base wafer 31 are formed. In many cases, pre-stars 34 and voids 35 were generated in the I-Ehwa and unbonded portions were formed. Then, as the thickness of the embedded oxide film of the S • I wafer becomes thinner, such prestar voids are more likely to be generated, and it is difficult to obtain a good product and the yield is deteriorated.
• the thickness of the buried oxide film formed on the S ⁇ I ⁇ wafer will further decrease from lOOnm to 50 nm or the like. Therefore, it is desired to produce SOI wafers at a high yield without generating prestars and voids even if the thickness of the buried oxide film is reduced.
• crystallinity of the SOI layer formed on the SOI wafer by the above-mentioned bonding method is better than that of the SIMOX method, crystal defects called HF defects and Secco defects that appear by etching are completely eliminated. This is not the case, and further improvement in crystallinity is desired. Disclosure of the invention
• an object of the present invention is to prevent the occurrence of prestar and void even when the thickness of the buried oxide film is reduced, and to make the crystallinity of the SOI layer extremely high.
• a method of manufacturing an SOI wafer having a SOI layer formed on a buried oxide film by laminating the bond wafer after bonding the bond wafer and the base wafer via an oxide film, wherein the bond wafer and the base wafer are bonded together.
• the total thickness of the oxide film formed on at least one of the surfaces is at least one of the buried oxide films of the SOI wafer to be manufactured.
• the bond wafer and the base wafer are bonded through the formed oxide film, and then the bond wafer is thinned to form a so-layer, and thereafter, Obtained lamination
• a method for manufacturing an S ⁇ I wafer is provided, wherein the wafer is subjected to a heat treatment to reduce the thickness of the buried oxide film.
• the wafers are bonded to each other, and then the bond wafer is thinned to form an SOI layer.
• the thickness of the buried oxide film is adjusted to a desired thickness by performing a heat treatment on the wafer to reduce the thickness of the buried oxide film.
• I ⁇ A wafer can be manufactured with high yield.
• the portion where the film thickness is reduced is reduced to a silicon layer having good crystallinity, and further, the silicon layer having good crystallinity during the heat treatment. Since the SII layer grows as a solid layer by using as a seed, an SOI layer with extremely good crystallinity can be obtained.
• the thickness of the SOI layer formed by thinning the bond wafer is 500 nm or less.
• the thickness of the SOI layer is greater than 500 nm, the reduction in the thickness of the buried oxide film is small even if a subsequent heat treatment is performed to reduce the thickness of the buried oxide film. It is necessary to perform heat treatment for a long time in order to obtain an oxide film.However, by reducing the thickness of the SOI layer to 50 O nm or less by thinning the bond wafer, heat treatment for reducing the thickness of the oxide film can be performed. This can be performed efficiently, and the buried oxide film can be reduced to a desired thickness in a short time.
• the heat treatment for reducing the thickness of the buried oxide film is preferably performed at a temperature of 100 ° C. or more in an atmosphere of hydrogen gas, argon gas, or a mixed gas thereof.
• the thickness of the oxide film can be effectively reduced, and a buried oxide film having a desired thin thickness can be reliably obtained.
• the heat treatment for reducing the thickness of the buried oxide film is performed so that the thickness of the buried oxide film can be reduced to 10 Onm or less.
• hydrogen ions or rare gas ions are implanted into the surface layer of the bond wafer to form an ion-implanted layer, and the ion-implanted surface of the bond wafer is cleaned.
• the bond wafer is peeled off by the formed ion-implanted layer to be thinned.
• the present invention is very effective when thinning the bond wafer by the ion implantation delamination method, and by performing the thinning by the ion implantation delamination method, the uniformity of the film thickness of the SOI layer is also high. You can get SOI ⁇ eha.
• a sacrificial oxidation process is further performed after the heat treatment for reducing the thickness of the buried oxide film.
• a thermal oxide film is further formed on the SOI layer, and the oxide film is removed.
• the damaged layer formed on the surface of the wafer can be removed, and the thickness of the SII layer can be adjusted while further improving the crystal quality of the SOI layer.
• an SOI wafer manufactured by the method for manufacturing an SOI wafer according to the present invention.
• the SOI wafer manufactured by the method of manufacturing an SOI wafer according to the present invention has no prestar and void even when the buried oxide film is thin, and the crystallinity of the SOI layer is extremely good. It can be.
• FIG. 2 is a flow chart showing a method of manufacturing an S 0 I wafer by a conventional ion implantation separation method.
• FIG. 3 is a schematic explanatory diagram schematically illustrating a void and a prestar generated in the SOI wafer. ⁇
• Figure 4 shows the relationship between the heat treatment time of the heat treatment to reduce the thickness of the buried oxide film and the amount of reduction in the thickness of the buried oxide film, and the thickness of the SOI layer formed on the bonded wafer and the reduction in the thickness of the buried oxide film. It is the graph which showed the relationship of quantity.
• the present inventors have conducted intensive studies and studies on a method for manufacturing an SOI wafer having a thin buried oxide film and a good crystallinity of an SOI layer without generating a prestar void.
• the bonding method when fabricating an SOI wafer by the bonding method, the total thickness of the oxide film formed on the surface of at least one of the two wafers is reduced by the buried oxide film of the manufactured SOI wafer.
• the wafers are bonded together, then thinned to form an SOI layer, and then the resulting bonded wafer is subjected to a heat treatment.
• the thickness of the buried oxide film The inventors have found that the thickness can be reduced to a desired thickness of 100 nm or less without generating any voids, and that the crystallinity of the SOI layer also becomes extremely good, thereby completing the invention.
• FIG. 1 is a flowchart showing an example of a method for manufacturing an SOI wafer by the ion implantation separation method according to the present invention.
• step (a) two silicon mirror surfaces are prepared.
• one wafer is a base wafer 1 serving as a support substrate meeting the device specifications, and the other wafer is a bond wafer 2 serving as an SOI layer.
• step (b) a thermal oxidation treatment is performed on at least one of the wafers, here the bond wafer 2, to form an oxide film 3 on the surface thereof.
• the thickness of the oxide film formed on the surface of the bond wafer is, for example, lOO nm so as to be larger than the thickness of the buried oxide film that the SOI wafer should have when the SOI wafer is finally manufactured.
• An oxide film is formed so as to have the above thickness.
• the wafer for forming the oxide film is not limited to the bond wafer, and may be formed on the base wafer or on both the base wafer and the bond wafer.
• the total thickness of the oxide film formed on the surfaces of both the wafers will eventually be the desired thickness of the embedded oxide film of the SOI wafer.
• the oxide film is formed so as to be thicker than the thickness.
• step (c) hydrogen ions in the surface layer of Bondueha 2 to form an oxide film 3 on the surface (H + ions, H first ion, H 2 + ions, etc.) by injecting an average of I O emissions
• An ion implantation layer 4 is formed parallel to the surface of the wafer at the penetration depth.
• the ions implanted into the bond wafer 2 may be rare gas ions or a mixture of hydrogen and rare gas ions.
• step (d) the surface of the bond wafer 2 on which the hydrogen ions have been implanted is overlapped and adhered to the base wafer 1 via the oxide film 3.
• the wafers can be bonded together without using an adhesive or the like.
• step ( e ) the bond wafer is thinned to form the SII layer 5.
• Bonding wafer 2 is formed into a thin film by, for example, applying a delamination heat treatment at a temperature of about 500 ° C. or more in an inert gas atmosphere and using the ion-implanted layer 4 formed on the bonding wafer 2 by the above-described hydrogen ion implantation as a boundary surface. It can be easily performed by peeling off. At this time, in the present invention, since the buried oxide film is formed thick in advance, the generation of voids and prestars due to degassing is suppressed.
• the peeling heat treatment can be omitted by performing plasma treatment on the wafer surface before bonding and activating the wafer before bonding.
• the SOI layer can be formed with a high precision so as to have a desired thickness by performing touch-borishing after peeling off the bond wafer with the ion-implanted layer.
• the thickness of the buried oxide film of the S SI ⁇ wafer finally obtained is determined by the product standard, but in the present invention, it can be made less than 10011 m, and furthermore, less than 50 nm. is there.
• the heat treatment conditions for the heat treatment for reducing the thickness of the oxide film can be determined as needed, and are not particularly limited. For example, hydrogen gas, argon gas, or a mixture gas of 100
• the heating is performed at a temperature of 0 ° C. or higher, preferably 110 ° C. or higher, and more preferably 115 ° C. or higher.
• the thickness of the oxide film under such heat treatment conditions By performing a heat treatment to reduce the thickness, the thickness of the buried oxide film can be effectively reduced, and a buried oxide film having a thickness of less than 100 ⁇ m, such as 100 to 80 nm, can be easily obtained.
• the bonding force between wafers can be increased to produce a firmly bonded SOI wafer.
• a heat treatment was performed to reduce the thickness of the buried oxide film with a heat treatment time of 1 hour or 0.4 hours at C, and then the amount of reduction in the thickness of the buried oxide film under each heat treatment condition was measured.
• the thickness reduction of the buried oxide film was measured by measuring the thickness of the buried oxide film of the bonded wafer before and after the heat treatment using a multilayer spectroscopic ellipsometer (manufactured by SOP RA). .
• the thickness of the buried oxide film is reduced by heat treatment by reducing the thickness of the SOI layer formed on the buried oxide film from 846 nm to 2977 ⁇ .
• the amount can be increased.
• the thickness of the S SI layer formed on the buried oxide film is larger than 500 nm, even if the heat treatment for reducing the thickness of the oxide film is performed, the amount of decrease in the thickness of the buried oxide film is reduced.
• the small size requires a long heat treatment to obtain a buried oxide film having a desired thickness. Therefore, it is preferable that the thickness of the SOI layer formed by thinning the bond wafer be 500 nm or less, thereby reducing the thickness of the buried oxide film.
• the heat treatment can be performed efficiently, and the buried oxide film can be reduced to a desired thickness in a short time.
• a so-called sacrificial oxidation is performed in which a thermal oxide film is formed on the SOI layer after the heat treatment for reducing the thickness of the buried oxide film, and the oxide film is removed.
• a treatment is performed.
• a heat treatment in an oxidizing atmosphere is performed to form an oxide film on the surface of the SII layer, and then the oxide film formed on the surface of the SOI layer is removed.
• the oxide film may be removed by, for example, etching with an aqueous solution containing HF. If etching is carried out with an aqueous solution containing HF, only the oxide film is removed by etching, and a SOI wafer with no contaminants such as damaging heavy metals removed by sacrificial oxidation can be obtained.
• the damage layer generated on the surface of the SOI wafer by ion implantation can be reliably removed, and the crystal quality of the SOI layer can be further improved. Since the thickness of the SOI layer can be adjusted while increasing the thickness, it is possible to manufacture a higher quality S ⁇ I ⁇ wafer.
• an SOI wafer By manufacturing an SOI wafer by the above-described method, it is possible to manufacture a SOI wafer with a reduced yield of a buried oxide film to a desired thickness by suppressing the generation of a prestar board and at a high yield. . Also, since the thickness of the buried oxide film is reduced by a heat treatment for reducing the thickness of the oxide film, the reduced thickness portion is reduced to a silicon layer having good crystallinity, and the crystallinity thereof is improved. Since the SOI layer is grown as a solid layer using the silicon layer as a seed, an SOI layer with extremely good crystallinity can be obtained.
• the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
• one silicon wafer to be a bond wafer is subjected to thermal oxidation to form an oxide film with a thickness of 100 nm on the surface of the wafer, and then hydrogen is injected into the silicon wafer at an implantation energy of 53 keV. Ions were implanted (dose amount: 5.5 ⁇ 10 16 / cm 2 ) to form an ion-implanted layer. Then, after bonding the bond wafer and the base wafer via the oxide film, the wafer is subjected to a peeling heat treatment at 500 ° C. for 30 minutes in a nitrogen gas atmosphere to be peeled at the ion-implanted layer, thereby removing the SOI layer. A wafer was prepared. The obtained bonded wafer was subjected to touch polishing with a polishing allowance of 60 nm to form an SOI layer having a thickness of 320 ⁇ .
• a mirror-polished silicon wafer having a diameter of 200 mm was prepared, and an SOI wafer having a buried oxide film having a thickness of 30 nm as a product standard was manufactured by an ion implantation separation method.
• a bond oxide was thermally oxidized to form an oxide film with a thickness of 80 nm on the surface of the wafer, and then hydrogen ions were implanted into the silicon wafer at an implantation energy of 50 keV ( Dose amount: 5.5 ⁇ 10 16 / cm 2 ), and an ion-implanted layer was formed. Then, after bonding the bond wafer and the base wafer having an oxide film with a thickness of 20 nm on the surface via the oxide film, a peeling heat treatment of 30 minutes at 50.0 ° C. in a nitrogen gas atmosphere is performed. As a result, the wafer was peeled off at the ion-implanted layer to produce a wafer having an SOI layer. The obtained bonded wafer was subjected to touch polishing with a polishing allowance of 60 nm to form an SII layer having a thickness of 320 nm.
• the bonded wafer was subjected to a heat treatment to reduce the thickness of the oxide film at 1200 ° C for 14 hours in an argon gas atmosphere to reduce the thickness of the buried oxide film by 70 ⁇ ⁇ .
• a heat treatment to reduce the thickness of the oxide film at 1200 ° C for 14 hours in an argon gas atmosphere to reduce the thickness of the buried oxide film by 70 ⁇ ⁇ .
• an SOI wafer having a buried oxide film having a thickness of 30 nm was manufactured.
• Two mirror-polished silicon wafers each having a diameter of 20 O mm were prepared, and the thickness was 80 nm (comparative example 1) as a product standard by the ion implantation peeling method.
• An SOI wafer having a buried oxide film having a thickness of O nm (Comparative Example 2) was manufactured. First, a thermal oxidation was performed on each of the bonders to form an oxide film with a thickness of 80 nm (Comparative Example 1) and a thickness of 30 nm (Comparative Example 2) on the surface of each wafer.
• Hydrogen ions were implanted into the silicon wafer of Comparative Example 1 with an implantation energy of 50 keV and the silicon wafer of Comparative Example 2 with an implantation energy of 44 keV (dose amount: 5 5 ⁇ 10 16 Z cm 2 ) to form an ion injection layer. Then, after bonding the bond wafer and the base wafer having no oxide film on the surface via the oxide film, ion-implantation is performed by performing a stripping heat treatment at 500 ° C. for 30 minutes in a nitrogen gas atmosphere. By peeling off the layer, a wafer having an SOI layer was produced. Each of the obtained bonded substrates was subjected to touch polishing with a polishing allowance of 60 nm to form an SOI layer having a thickness of 320 nm.
• a bonding heat treatment for further increasing the bonding strength between the bond wafer and the base wafer may be performed, thereby obtaining an SOI wafer in which the wafers are more firmly bonded to each other. it can .
• the bond wafer is thinned by the ion implantation delamination method.
• the present invention is not limited to this.
• the grinding and polishing method or the PACE method is used. Can be similarly applied.

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• 2003
  • 2003-01-10 JP JP2003004833A patent/JP4407127B2/ja not_active Expired - Fee Related
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