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
  • H01L21/70—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
• • 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
  • H01L21/20—Deposition of semiconductor materials on a substrate, e.g. epitaxial growth solid phase epitaxy
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D86/00—Integrated devices formed in or on insulating or conducting substrates, e.g. formed in silicon-on-insulator [SOI] substrates or on stainless steel or glass substrates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S438/00—Semiconductor device manufacturing: process
  • Y10S438/91—Controlling charging state at semiconductor-insulator interface

Definitions

• ____Jilis jnyentlon relates to integrated circuit (IC) structures and processes that include a strained silicon or silicon germanium (Si/SiGe) layer. More particularly, this invention relates to formation of a structure having a strained Si/SiGe layer on an insulator layer which is useful for fabricating high speed devices such as complementary metal-oxide-semiconductor (CMOS) transistors and other metal-oxide-semiconductor field effect transistor (MOSFET) applications.
• CMOS complementary metal-oxide-semiconductor
• MOSFET metal-oxide-semiconductor field effect transistor
• Electron and hole mobility in strained silicon or silicon germanium layers has been shown to be significantly higher than that in bulk silicon.
• measured values of electron mobility in strained Si at room temperature are about 3000 cm 2 /Vs as opposed to 400 cm 2 /Vs in bulk silicon.
• hole mobility in strained SiGe with high Ge concentration (60% ⁇ 80%) reaches up to 800 cm 2 /Vs, which is about 5 times the hole mobility in bulk silicon of 150 cm 2 /Vs.
• MOSFETs with strained-Si channels have been experimentally demonstrated to have enhanced device performance compared to devices fabricated in conventional (unstrained) silicon substrates.
• Strained-Si layers are the result of biaxial tensile stress induced in silicon grown on a substrate formed of a material whose lattice constant is greater than that of silicon.
• the lattice constant of germanium is about 4.2 percent greater than that of silicon, and the lattice constant of a silicon-germanium alloy is nearly linear with respect to its germanium concentration.
• the lattice constant of a SiGe alloy containing fifty atomic percent germanium is about 1.02 times ⁇ greater4harHhe lattice onstant of silicon.
• SOI Silicon-On-lnsulator
• Available technology to achieve SOI wafers includes Separation by Implanted Oxygen (SIMOX), bonding and etchback Silicon-On-lnsulator (BESOI), separation by implanted hydrogen also known as the Smart-Cut® process which is described in U.S. Patent No. 5,374,564, or the combination of theJastiwo processes for making ultra-thin SOI, described in U.S. Patent No. 5,882,987.
• SIMOX Separation by Implanted Oxygen
• BESOI etchback Silicon-On-lnsulator
• Smart-Cut® process which is described in U.S. Patent No. 5,374,564, or the combination of theJastiwo processes for making ultra-thin SOI, described in U.S. Patent No. 5,882,987.
• Si in an SOI wafer is substituted by strained Si or SiGe (Si/SiGe) layers for high speed applications
• two methods are generally used to produce strained Si/SiGe-on-insulator structures.
• thermal mixing is used to produce a relaxed SiGe-on-insulator structure (SGOI), followed by epitaxial growth of strained Si on SGOI.
• SGOI relaxed SiGe-on-insulator structure
• FIGs 1(a)-(c) A SiGe layer 13 is deposited on an SOI substrate comprising silicon substrate 10, insulator or oxide layer 11 and silicon layer 12, as shown in Figure 1(a).
• Thermal mixing is then performed, to produce the structure shown in Figure 1 (b) which comprises substrate 10, insulator layer 11 , and SiGe layer 14.
• germanium is rejected from the oxide during high -temperature-oxidation; -and the final SiGe concentration and relaxation in layer 14 is a function of the initial SiGe concentration in layer 13, its thickness, and the final thickness of SiGe layer 14.
• oxide is stripped from the top surface of the structure.
• strained Si layer 15 is grown on SiGe layer 14, as shown in Figure 1(c).
• thermal mixing is a promising method to make strained Si/SiGe-on-insulator, it has draw backs.
• a SiGe-on-insulator structure is first formed, then strained Si is grown on the SiGe. Strained Si deposition on SiGe may leave a non-ideal interface with O and C residue, which may affect device performance or yield.
• SiGe after thermal mixing is usually not fully relaxed.
• high concentration SiGe is needed as the template for strained Si growth. The high concentration SiGe will lead to integration complexity and potentially yield degradation.
• a first wafer bonding method involves bonding relaxed SiGe onto an insulator followed by strained Si/SiGe growth.
• This first wafer bonding method is described in U.S. Patent No. 6,524,935, and is illustrated in Figures 2(a)-2(d).
• the method begins with growing an epitaxial relaxed SiGe layer 21 on a first silicon substrate 20, as shown in Figure 2(a).
• hydrogen is implanted into the SiGe layer 21 to form a hydrogen-rich defective layer (not shown).
• the surface of the SiGe layer 21 is smoothed by chemical-mechanical polishing (CMP).
• the surface of the first substrate is bonded to the surface of a second substrate comprising bulk silicon 22 and an insulator layer 23, as shown in Figure 2(b).
• the smoothed surface of the SiGe layer 21 is bonded to the insulator layer 23, which is typically SiO 2 .
• Bonding the two substrates together is accomplished by placing the surface of the first substrate against the surface of the second substrate resulting in a weak chemical bond which holds the two substrates together. A ⁇ thermaitreatment ⁇ s usually performed to the bonded wafer pair to strengthen the chemical bonds at the joined interface.
• the two substrates are separated at the hydrogen-rich defective layer, resulting in the structure shown in Figure 2(c) which comprises second substrate 22, insulator layer 23 and a portion of SiGe layer 21.
• the top surface of SiGe layer 21 in this separated structure may be smoothed by CMP.
• strained Si layer 24 is epitaxially grown on SiGe layer 21.
• This wafer bonding method suffers from process complications.
• the as-bonded SiGe on insulator is usually too thick, and therefore thinning of SiGe is required before strained Si deposition, which is a non-trivial process.
• strained Si deposition on SiGe may leave a non-ideal interface with O and C residue, which may affect device performance or yield.
• a second wafer bonding method involves directly bonding strained Si/SiGe onto an insulator.
• This second wafer bonding method is described in U.S. Patent No. 6,603,156, and is illustrated in Figures 3(a)-3(e).
• the method begins with growing a relaxed SiGe layer 31 on a first silicon substrate 30, as shown in Figure 3(a).
• a strained-Si layer 32 is next formed on strain-inducing SiGe layer 31 , as shown in Figure 3(b).
• the first substrate is bonded to a second substrate comprising bulk silicon 33 and an insulator layer 34, as shown in Figure 3(c).
• the two structures are bonded such that the insulating layer 34 is between strained-Si layer 32 and second substrate 33, and the strained-Si layer 32 directly contacts the insulating layer 34, as shown in Figure 3(d).
• the initial strain-inducing layer 31 is then removed to expose the surface of the strained-Si layer 32 and yield a strained-Si-on-insulator (SSOI) structure.
• Strain-inducing layer 31 may be removed by CMP, wafer cleaving (smart cut), or chemical etching.
• a chemical etching process such as HHA (hydrogen peroxide, hydrofluoric acid, and acetic acid) selective to Si is preferred so that the SiGe layer 31 is fully removed stopping on the strained-Si layer 32.
• This second wafer bonding method eliminates the steps of thinning of SiGe and the interface left by strained-Si growth on SiGe, as needed by the first wafer bonding method.
• U.S. Patent No. 6,603,156 also teaches that a structure without SiGe between the strained-Si and the insulator is advantageous, as SiGe usually complicates CMOS processes.
• the thickness of Si is limited due to the critical thickness of the strained layer. For example, strained-Si with 1% of strain is limited to a thickness of about 100 A, beyond which defects may form in the strained-Si during high temperature process steps. The critical thickness of Si with higher strain is even less.
• the invention is directed to a method of forming a strained Sii- y Ge y layer above an insulator layer.
• the method comprises the steps of: forming a relaxed Sii- x Ge x layer on a first crystalline semiconductor substrate; forming a strained Sii- y Ge y layer on said relaxed Si 1-x Ge x layer; forming a Sii -2 Ge z layer on said strained silicon layer; forming a hydrogen-rich defective layer in said relaxed Si 1-x Ge x layer; providing a second crystalline semiconductor substrate having an insulator layer thereover; bonding a top surface of said Sii -z Ge z layer on said first substrate to said insulator layer on said second substrate; separating said relaxed Si 1-x Ge x layer at said hydrogen-rich defective layer to form a structure comprising said second substrate with said insulator layer, said Sii- 2 Ge z layer on said insulator layer, said strained Sii -y Ge y layer on said Sii -z Ge z layer, and
• Figures 1(a)-1(c) illustrate a prior art method for forming a strained Si/SiGe-on-insulator structure using thermal mixing
• Figures 2(a)-2(d) illustrate a prior art method for forming a strained Si/SiGe-on-insulator structure using a first wafer bonding method which involves bonding relaxed SiGe onto an insulator and then growing strained Si/SiGe;
• Figures 3(a)-3(e) illustrate a prior art method for forming a strained Si/SiGe-on-insulator structure using a second wafer bonding method which involves directly bonding strained Si/SiGe onto an insulator;
• Figures 4(a)-4(f) illustrate a preferred embodiment of the method of the present invention for forming a strained Si/SiGe-on-insulator structure.
• FIGs 4(a)-4(f) A preferred embodiment of the method of the present invention is illustrated in Figures 4(a)-4(f).
• the method begins with formation of a relaxed Sii- x Ge x layer 41 on a first crystalline semiconductor substrate 40, as shown in Figure 4(a).
• First substrate 40 may be any single crystal material suitable for forming epitaxial layers thereon. Examples of such suitable single crystal materials include Si, SiGe, SiGeC and SiC, with Si being preferred.
• layer 41 should be substantially relaxed or completely relaxed.
• the relaxation may be due to a modified Frank-Read mechanism as described in U.S. Patent No. 5,659,187, the disclosure of which is incorporated herein by reference.
• Layer 41 may be formed by growing a relatively thick graded SiGe layer followed by a constant concentration SiGe layer having a total thickness of greater than 1 ⁇ m, where the SiGe is fully or partially relaxed, followed by CMP smoothing.
• layer 41 may be formed by growing a medium thickness SiGe layer having a thickness of about 500 to 3000 A, followed by He implant and anneal, and CMP smoothing if necessary.
• the concentration x of Ge in layer 41 may range from about 0.05 up to about 1.0, and is preferably in the range of about 0.15 to about 0.40.
• a strained Sii -y Ge y layer 42 is grown epitaxially on the top surface of layer 41 , and then a Sii- z Ge 2 layer 43 is grown on top of strained layer 42, as shown in Figure 4(b).
• the concentration y of Ge in layer 42 may range from zero up to 0.05.
• the concentration y in layer 42 should be less than the concentration x in layer 41 , such that layer 41 has a greater lattice constant than layer 42, thereby forming a strained layer 42 which is under biaxial tension.
• concentration y in layer 42 is zero, such that layer 42 is a strained-Si layer.
• Layer 42 preferably has a thickness of about 50 A to about 300 A. The thickness of layer 42 is related to the strain in the film. For higher strain, the thickness of layer 42 should be smaller to avoid defect formation in the film.
• Si 1-2 Ge 2 layer 43 may be strained or unstrained, depending on the concentration z of Ge and the process needs. Specifically, the concentration z may range from about 0.05 to about 1.0, more preferably about 0.10 to about 0.30, and may be less than or greater than the concentration y of Ge in layer 42.
• The. thickness of, Sh -2 Ge 2 layer 43 may be selected so that the total thickness of layers 42 and 43 is as required by the specific CMOS technology needs. In a preferred embodiment, layer 43 may have a thickness of about 50 A to about 600 A, more preferably about 100 A to about 300 A.
• Sh -2 Ge 2 layer 43 may be epitaxially grown following growth of the strained Sii-yGe y layer 42, preferably without taking the wafer out from the epitaxy chamber, so that the interface between Sii. z Ge z layer 43 and strained Sh-yG ⁇ y layer 42 is clean.
• a hydrogen implantation step is performed to form a hydrogen-rich defective layer 44, as shown in Figure 4(c).
• layer 41 is subjected to ion bombardment or the implantation of hydrogen ions, which may be implanted at an energy of about 10 KeV to about 200 KeV at a dose of about 5x10 16 to about 1x10 17 ions/cm 2 .
• the hydrogen implantation results in the formation of a hydrogen-rich layer 44 comprising hydrogen-containing SiGe point defects and planar micro cracks residing in principle crystallographic planes of SiGe.
• the energy of the hydrogen ions is selected to place the peak dose in layer 41 below the top surface of layer 41 , preferably at a depth of about 100 nm to 1000 nm.
• the hydrogen-rich defective layer 44 will form at the peak dose location of hydrogen.
• the first structure comprising layers 40, 41 , 42 and 43 is bonded to a second structure comprising layers 45 and 46, as shown in Figure 4(d).
• second structure comprises substrate 46 and insulating layer 45.
• Suitable materials for substrate 46 include single-crystal silicon, polysilicon, SiGe 1 GaAs and other Ml-V semiconductors, with single-crystal silicon being particularly preferred.
• the insulating layer 45 may be formed of any suitable material, including silicon oxide (SiO 2 ), silicon nitride (SiN) and aluminum oxide (AI 2 O 3 ), although other electrically insulating materials could be used, including silicon oxynitride, hafnium oxide (HfO 2 ), zirconium oxide (ZrO 2 ) and doped aluminum oxide. SiO 2 is particularly preferred for insulating layer 45. While the individual thicknesses of insulating layer 45 and substrate 46 are not generally critical to the invention, thicknesses of up to about 1 ⁇ m are suitable for the insulating layer 45.
• the first structure may be bonded to the second structure using any suitable wafer bonding technique.
• the top surface of layer 43 Prior to wafer bonding, the top surface of layer 43 is preferably polished by a Chemical Mechanical Polishing (CMP) process to provide a smooth top surface. This polishing may be performed before or after formation of hydrogen-rich defective layer 44.
• This top surface of layer 43 shown in Figure 4(c) then may be turned upside down and brought into contact with the top surface of layer 45.
• the bonding between the surfaces of layers 43 and 45 may be strengthened by annealing at a temperature of about 50 °C to about 500 "C, for a time period of about 2 hours to about 50 houfSi- »»
• Layer 41 is then separated at the hydrogen-rich defective layer 44 by any suitable technique, without disturbing the mechanical bond between layers 43 and 45.
• layer 41 may be separated into two portions by annealing, preferably at a temperature of about 200 °C to about 600 °C.
• the remaining structure comprises substrate 46, insulating layer 45, Sh -2 Ge 2 layer 43, strained Sii-yGe y layer 42, and a portion of relaxed Si 1-x Ge x layer 41 , a shown in Figure 4(e).
• the remaining portion of layer 41 is removed by any suitable method, preferably by selective etch such as using HHA stopping on strained ⁇ ayerA2.
• The,resulting structure, shown in Figure 4(f) comprises substrate 46, insulating layer 45, Sh -2 Ge 2 buffer layer 43, and strained Si 1-y Ge y layer 42.
• the interface between strained Sii- y Ge y layer 42 and Sh -2 Ge 2 buffer layer 43 is clean, as the two films were grown in the same epitaxy step.
• This invention is useful in the manufacture of integrated circuit (IC) structures that include a strained silicon or silicon germanium (Si/SiGe) layer.

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• 2004
  • 2004-06-29 US US10/710,255 patent/US6893936B1/en not_active Expired - Fee Related
• 2005
  • 2005-02-16 JP JP2007519189A patent/JP2008505482A/ja active Pending
  • 2005-02-16 CN CNA2005800153595A patent/CN1954421A/zh active Pending
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