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  • H10D30/00—Field-effect transistors [FET]
  • H10D30/01—Manufacture or treatment
  • H10D30/021—Manufacture or treatment of FETs having insulated gates [IGFET]
  • H10D30/0223—Manufacture or treatment of FETs having insulated gates [IGFET] having source and drain regions or source and drain extensions self-aligned to sides of the gate
  • H10D30/0227—Manufacture or treatment of FETs having insulated gates [IGFET] having source and drain regions or source and drain extensions self-aligned to sides of the gate having both lightly-doped source and drain extensions and source and drain regions self-aligned to the sides of the gate, e.g. lightly-doped drain [LDD] MOSFET or double-diffused drain [DDD] MOSFET
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  • H10D30/01—Manufacture or treatment
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  • H10D30/027—Manufacture or treatment of FETs having insulated gates [IGFET] of lateral single-gate IGFETs
  • H10D30/0278—Manufacture or treatment of FETs having insulated gates [IGFET] of lateral single-gate IGFETs forming single crystalline channels on wafers after forming insulating device isolations
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  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/601—Insulated-gate field-effect transistors [IGFET] having lightly-doped drain or source extensions, e.g. LDD IGFETs or DDD IGFETs 
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  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/751—Insulated-gate field-effect transistors [IGFET] having composition variations in the channel regions
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  • H10D64/68—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator
  • H10D64/681—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator having a compositional variation, e.g. multilayered
  • H10D64/685—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator having a compositional variation, e.g. multilayered being perpendicular to the channel plane
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  • H10D64/66—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes
  • H10D64/68—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator
  • H10D64/691—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes characterised by the insulator, e.g. by the gate insulator comprising metallic compounds, e.g. metal oxides or metal silicates 
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  • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
  • H10D84/01—Manufacture or treatment
  • H10D84/0123—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs
  • H10D84/0126—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs
  • H10D84/0165—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs the components including complementary IGFETs, e.g. CMOS devices
  • H10D84/0167—Manufacturing their channels
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  • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
  • H10D84/01—Manufacture or treatment
  • H10D84/0123—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs
  • H10D84/0126—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs
  • H10D84/0165—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs the components including complementary IGFETs, e.g. CMOS devices
  • H10D84/017—Manufacturing their source or drain regions, e.g. silicided source or drain regions
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  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
  • H10D84/01—Manufacture or treatment
  • H10D84/0123—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs
  • H10D84/0126—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs
  • H10D84/0165—Integrating together multiple components covered by H10D12/00 or H10D30/00, e.g. integrating multiple IGBTs the components including insulated gates, e.g. IGFETs the components including complementary IGFETs, e.g. CMOS devices
  • H10D84/0181—Manufacturing their gate insulating layers
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  • H10D84/01—Manufacture or treatment
  • H10D84/02—Manufacture or treatment characterised by using material-based technologies
  • H10D84/03—Manufacture or treatment characterised by using material-based technologies using Group IV technology, e.g. silicon technology or silicon-carbide [SiC] technology
  • H10D84/038—Manufacture or treatment characterised by using material-based technologies using Group IV technology, e.g. silicon technology or silicon-carbide [SiC] technology using silicon technology, e.g. SiGe
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  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/60—Electrodes characterised by their materials
  • H10D64/66—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes
  • H10D64/665—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes the conductor comprising a layer of elemental metal contacting the insulator, e.g. tungsten or molybdenum
  • H10D64/666—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes the conductor comprising a layer of elemental metal contacting the insulator, e.g. tungsten or molybdenum the conductor further comprising additional layers
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  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/60—Electrodes characterised by their materials
  • H10D64/66—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes
  • H10D64/667—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes the conductor comprising a layer of alloy material, compound material or organic material contacting the insulator, e.g. TiN workfunction layers

Definitions

• the present invention is directed in general to the field of semiconductor devices. In one aspect, the present invention relates to the fabrication of metal gate electrodes used in semiconductor devices. Description of the Related Art
• CMOS technology is increasingly replacing silicon dioxide gate dielectrics and polysilicon gate conductors with high dielectric constant (high-k) dielectrics in combination with metal gate electrodes formed from a gate stack of polysilicon and one or more metal layers.
• the metal gate layers not only obviate gate-depletion and boron-penetration effects, but also provide a significantly lower sheet resistance.
• high-k dielectrics in conjunction with metal gate electrodes advantageously exhibit improved transistor performance
• the use of new metal layer technologies can create new technical challenges. For example, when the threshold voltage for metal gate PMOS devices is adjusted by including a silicon germanium layer in the PMOS channel region, the existing dual gate oxide (DGO) fabrication processes may not be compatible if they use thermal oxidation or high temperature thermal oxidation process to form the thick gate oxide over the silicon germanium layer.
• DGO dual gate oxide
• TDDB Time-Dependent Dielectric Breakdown
• Figure 1 is a partial cross-sectional view of a semiconductor wafer structure including a semiconductor layer
• Figure 2 illustrates processing subsequent to Figure 1 where a masking layer is formed over NMOS areas of the semiconductor wafer structure and an epitaxial SiGe layer is selectively formed over PMOS areas of the semiconductor wafer structure;
• Figure 3 illustrates processing subsequent to Figure 2 after the masking layer is removed and a first high-k gate dielectric layer is disposed over the semiconductor wafer structure;
• Figure 4 illustrates processing subsequent to Figure 3 after a patterned etch mask is formed on the first high-k gate dielectric layer in the DGO device areas;
• Figure 5 illustrates processing subsequent to Figure 4 after exposed portions of the first high-k gate dielectric layer are removed from the core device areas;
• Figure 6 illustrates processing subsequent to Figure 5 after the patterned etch mask is stripped or removed;
• Figure 7 illustrates processing subsequent to Figure 6 after a second high-k gate dielectric layer is disposed over the semiconductor wafer structure
• Figure 8 illustrates processing subsequent to Figure 7 after a first metal-based gate layer is deposited over the semiconductor wafer structure
• Figure 9 illustrates processing subsequent to Figure 8 after a silicon-containing gate layer is disposed over the first metal-based layer; and [015] Figure 10 illustrates processing subsequent to Figure 9 after the single metal gate stack is selectively etched to form gate electrodes and the NMOS and PMOS core and DGO devices are at least partially completed.
• a method and apparatus are described for integrating dual gate oxide (DGO) transistor devices and core transistor devices on a single substrate where each transistor includes a metal gate and one or more high-k gate dielectric layers.
• a thicker gate dielectric is formed to include a first, relatively lower high-k layer and a second, relatively higher high-k metal oxide layer in a region of the device for higher voltage requirements (e.g., an I/O region), and a thinner second gate dielectric is formed with the second, relatively higher high-k metal oxide layer in a region of the device for lower voltage requirements (e.g., a core device region).
• the substrate may be formed to include a channel layer in one or both of the PMOS and NMOS devices areas, where the channel layer is formed from a semiconductor material having a different electrical property than the underlying semiconductor substrate (e.g., a SiC channel layer in the NMOS device area or a SiGe channel layer in the PMOS device area).
• the threshold voltage of PMOS metal-gate devices can be adjusted independently of NMOS devices.
• the DGO transistor devices may be fabricated to include a first, relatively lower high-k layer (e.g., Hafnium silicate or HfSiO x Ny) and a second, relatively higher high-k metal oxide layer (e.g., Hafnium oxide), while the core transistor devices may be fabricated using the second, relatively higher high-k metal oxide layer as the core gate dielectric layer.
• a single metal layer and polysilicon layer are sequentially formed or deposited over the DGO and core device areas, and then selectively etched to form PMOS and NMOS gate electrodes having tuned the threshold voltages and improved gate oxide integrity.
• the structure 1 includes a semiconductor layer 16 formed on or as part of a semiconductor substrate 15 that has a first crystallographic orientation. Also illustrated is a plurality of shallow trench isolations 17 that divide the layer 16 into separate regions, such as an NMOS dual gate oxide (N-DGO) region 110, an NMOS core (N- Core) region 111, a PMOS dual gate oxide (P-DGO) region 112, and a PMOS core (P-Core) region 113.
• N-DGO NMOS dual gate oxide
• N- Core NMOS core
• P-Core PMOS core
• the N-DGO region 110 and N-Core region 111 may be implanted with boron to form P-well regions, and the P-DGO region 112 and PMOS core region 113 may be implanted with arsenic or phosphorus to form N-well regions (not shown).
• NMOS devices may be formed in N-DGO region 110 and N- Core region 111.
• PMOS devices may be formed in P-DGO region 112 and P-Core region 113.
• the devices formed in the dual gate oxide regions (110 and 112) will be formed with thicker gate oxide and the devices formed in the core regions (111 and 113) will be formed with thinner gate oxide.
• the semiconductor layer 15, 16 may be implemented as a bulk silicon substrate, single crystalline silicon (doped or undoped), semiconductor on insulator (SOI) substrate, or any semiconductor material including, for example, Si, SiC, SiGe, SiGeC, Ge, GaAs, InAs, InP, as well as other III/V or II/VI compound semiconductors or any combination thereof, and may optionally be formed as the bulk handling wafer.
• the semiconductor layer 15, 16 has a channel crystallographic orientation of ⁇ 100>. The present disclosure will also work for devices with other crystal orientation such as ⁇ 110>, ⁇ 111> which may be desirable for enhancing carrier mobility.
• the layer 16 may consist of multiple stacks of materials.
• the starting substrate for the invention can be of semiconductor-on-insulator (SOI) type having a buried insulator layer under a top layer of semiconductor, or a dual substrate orientation substrate, such as partial bulk and partial SOI with orientation different for bulk and SOI.
• SOI semiconductor-on-insulator
• the isolation regions or structures 17 are formed to electrically isolate the
• Isolation structures 17 define lateral boundaries of an active region or transistor region 110-113 in active layer 16, and may be formed using any desired technique, such as selectively etching an opening in the second semiconductor layer 16 using a patterned mask or photoresist layer (not shown), depositing a dielectric layer (e.g., oxide) to fill the opening, and then polishing the deposited dielectric layer until planarized with the remaining second semiconductor layer 16. Any remaining unetched portions of the patterned mask or photoresist layer(s) are stripped. As will be appreciated, the isolation regions or structures 17 may be formed in other ways in other embodiments.
• Figure 2 illustrates processing of a semiconductor wafer structure 2 subsequent to Figure 1 where a patterned masking layer 20 is selectively formed over NMOS areas 110, 111 of the semiconductor wafer structure and an epitaxial SiGe layer 21 is selectively formed over PMOS areas 112, 113 of the semiconductor wafer structure.
• a patterned masking layer 20 is selectively formed over NMOS areas 110, 111 of the semiconductor wafer structure and an epitaxial SiGe layer 21 is selectively formed over PMOS areas 112, 113 of the semiconductor wafer structure.
• one or more masking layers 20 e.g., an oxide layer and/or nitride layer
• conventional patterning and etching techniques may be used to form an opening in the mask layer(s) 20 that exposes at least the PMOS device area 112, 113.
• the selectively formed masking layer 20 is used to define and differentiate active regions for NMOS and PMOS devices subsequently formed on the wafer structure 16. After forming the patterned masking layer
• a thin, compressively stressed semiconductor layer 21 is selectively formed over the PMOS area(s) 112, 113 of the semiconductor wafer structure that will be used to form the PMOS devices.
• the semiconductor layer 21 is shown in the figures as being formed on top of the semiconductor layer 16, it will be appreciated that the semiconductor layer 21 may be embedded in the semiconductor layer 16.
• the thin, compressively stressed semiconductor layer 21 is formed with a semiconductor material having larger atom-to-atom spacing than the underlying second semiconductor layer 16, such as SiGe, SiGeC, or combinations and composition by weight thereof, which is capable of being formed utilizing a selective epitaxial growth method or other deposition methods accompanied by subsequent re-crystallization.
• the semiconductor layer 21 may be formed by epitaxially growing a SiGe layer that is thinner than a critical relaxation thickness to form a compressive SiGe layer
• This epitaxial growth may be achieved by a process of chemical vapor deposition (CVD) at a chamber temperature between 400 and 900 0 C in the presence of dichlorosilane, germane (GeH 4 ), HCl, and hydrogen gas. So long as the thickness of the SiGe layer 21 is less than the critical relaxation thickness, the SiGe layer 21 is compressively stressed. As will be appreciated, the critical relaxation thickness for a SiGe layer will depend on the amount of germanium contained in the layer 21 and the layer thickness.
• CVD chemical vapor deposition
• an epitaxially grown SiGe layer 21 that has 10% to 50% germanium (e.g., 20% to 35% germanium) and that is grown to a predetermined thickness in a range of at least 30 Angstroms to 150 Angstroms (e.g., approximately 100 Angstroms) will have a biaxial compressive strain because of the lattice mismatch between layers 22 and 16. Compressive stress and lower band gap of SiGe allows for threshold voltage lowering and mobility enhancement for PMOS devices in regions 112 and 113.
• SiGe can be doped with Boron for further reduction of PMOS threshold voltage.
• a channel layer 21 of silicon germanium may be formed, it will be appreciated that other semiconductor materials having different electrical properties from semiconductor substrate 16 may be used.
• silicon carbide may be used, or any semiconductor material may be used that changes a band gap of a channel region for NMOS devices.
• any semiconductor material that changes a band gap of a channel region of a thick gate device relative to a channel region of a thin gate device may be used.
• a semiconductor cap layer may be formed over the epitaxial semiconductor layer 21 by epitaxially growing or depositing a layer of silicon to a predetermined thickness of approximately 15 Angstroms over the underlying SiGe layer 22, though other thicknesses and materials may be used.
• Figure 3 illustrates processing of a semiconductor wafer structure 3 subsequent to Figure 2 after the mask layer 20 is removed, and a first high-k gate dielectric layer 22 is disposed over the semiconductor wafer structure.
• the first high-k gate dielectric layer 22 is formed by depositing a high-k gate dielectric material with a relatively low dielectric constant value on top of the DGO device areas and the core device areas 110-113 using chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination(s) of the above.
• CVD chemical vapor deposition
• PECVD plasma-enhanced chemical vapor deposition
• PVD physical vapor deposition
• ALD atomic layer deposition
• the first high-k gate dielectric layer 22 may be formed by a low temperature CVD or ALD process to a predetermined final thickness in the range of 1-100 Angstroms (e.g., 10-50 Angstroms, or more particularly, 20-30 Angstroms), though other thicknesses may be used.
• a suitable high- k gate dielectric material for the gate dielectric layer 22 is an insulator material having a dielectric constant value k of 7.0 or greater that is lower than the dielectric constant value of the second high-k gate dielectric layer 24 (described below).
• a suitable temperature for the deposition process is in the range of approximately 200 degrees Celsius to approximately 400 degrees Celsius, and is controlled to reduce or eliminate the diffusion of germanium.
• a suitable high-k gate dielectric material for use as the first high-k gate dielectric layer 22 is a hafnium-based dielectric which does not adversely interact with the underlying silicon germanium layer 21, such as hafnium silicate (e.g., Hf x Sii_ x O y ) or hafnium oxy-nitride (e.g., Hf x Sii_ x O y N z ), though other silicates of zirconium, aluminum, lanthanum, strontium, tantalum, titanium and combinations thereof may also be used, including but not limited to HfSiO x , ZrSiO x , LaSiO x , YSiO x , ScSiO x , CeSiO x , and HfLaSiO x .
• hafnium silicate e.g., Hf x Sii_ x O y
• hafnium oxy-nitride e
• FIG. 4 illustrates processing of a semiconductor wafer structure 4 subsequent to Figure 3 after a patterned etch mask 23 is formed on the first high-k gate dielectric layer 22 in the DGO device areas 110, 112.
• the patterned etch mask 23 may be formed by applying a layer of photoresist that is patterned directly on the first high-k gate dielectric layer 22 to mask the DGO device areas 110, 112, or a multi-layer masking technique may be used to form a etch mask pattern 23 over the first high-k gate dielectric layer 22 in the DGO device areas 110, 112.
• Figure 5 illustrates processing of a semiconductor wafer structure 5 subsequent to Figure 4 after exposed portions of the first high-k gate dielectric layer 22 are removed from the core device areas 111, 113.
• the exposed portions of the first high-k gate dielectric layer 22 are selectively etched and removed from the core device areas 111, 113, thereby leaving portions of the first high-k gate dielectric layer 22 in the DGO device areas 110, 112.
• the pattern transfer and etching of the mask layer 23 may use one or more etching steps to remove the unprotected portions of the layer 22, including a dry etching process such as reactive-ion etching, ion beam etching, plasma etching or laser etching, a wet etching process wherein a chemical etchant is employed or any combination thereof.
• a dry etching process such as reactive-ion etching, ion beam etching, plasma etching or laser etching, a wet etching process wherein a chemical etchant is employed or any combination thereof.
• the exposed portion of first high-k gate dielectric layer 22 may be anisotropically etched using a reactive ion etch process, leaving the lower gate oxide region 22 in N-DGO region 110 and in the P-DGO region 112.
• the exposed portions of the first high-k gate dielectric layer 22 may be removed from N-Core region 111 and P-Core region 113 using a hydrofluor
• the patterned photoresist layer 23 is removed. This is shown in Figure 6 which illustrates processing of a semiconductor wafer structure 6 subsequent to Figure 5 after the patterned etch mask 23 is stripped or removed, such as by using, for example, a piranha clean or solvent clean process.
• Figure 7 illustrates processing of a semiconductor wafer structure 7 subsequent to Figure 6 after a second high-k gate dielectric layer 24 is disposed over the semiconductor wafer structure.
• a pre-cleaning process e.g., an RCA standard clean 1 or 2 solution without HF
• a pre-cleaning process may be applied to clear the top surfaces of the relevant regions.
• the second high-k gate dielectric layer 24 is formed by depositing a high-k gate dielectric material with a relatively high dielectric constant value on top of the DGO device areas and the core device areas 110- 113 so that the dielectric layer 24 directly overlies the lower gate oxide region 22 in the N- DGO region 110, a portion of the semiconductor layer 16 in N-Core region 111, the lower gate oxide region 22 in the P-DGO region 112, and the SiGe layer 21 in the P-Core region 113.
• the second high-k gate dielectric layer 24 is deposited using CVD, PECVD, PVD, ALD, or any combination(s) of the above to a predetermined final thickness in the range of 1-100 Angstroms (e.g., 10-50 Angstroms, or more particularly, 15- 20 Angstroms), though other thicknesses may be used.
• a suitable high-k gate dielectric material for the gate dielectric layer 24 is an insulator material having a dielectric constant value k greater than 7.0 that is higher than the dielectric constant value of the first high-k gate dielectric layer 22.
• a metal oxide compound may be used that does not include silicon (e.g., Hf ⁇ 2), though other oxides, silicates or aluminates of zirconium, aluminum, lanthanum, strontium, tantalum, titanium and combinations thereof may also be used, including but not limited to Ta 2 O 5 , ZrO 2 , TiO 2 , Al 2 O 3 , Y 2 O 3 , La 2 O 3 , HfSiN y O x , ZrSiN y O x , ZrHfOx, LaSiO x , YSiO x , ScSiO x , CeSiO x , HfLaSiO x , HfAlO x , ZrAlO x , and LaAlO x .
• multi-metallic oxides for example barium strontium titanate, BST
• BST barium strontium titanate
• a first metal-based gate layer 25 is deposited on the second high-k gate dielectric layer 24.
• the metal-based layer 25 is deposited on the second high-k gate dielectric layer 24 using any desired deposition or sputtering process, such as CVD, PECVD, PVD, ALD, molecular beam deposition (MBD) or any combination(s) thereof.
• a suitable material for use as the metal-based layer 25 is an element or alloy (e.g., TaC or W) which may be deposited over the NMOS and PMOS regions 110-113 to a predetermined thickness of 20-150 Angstroms (e.g., 50-100 Angstroms), though other metallic layer materials with different thicknesses may be used.
• an element or alloy e.g., TaC or W
• the metal-based layer 25 may include an element selected from the group consisting of Ti, Ta, La, Ir, Mo, Ru, W, Os, Nb, Ti, V, Ni, W, and Re to form a metal or metal-based layer that may contain carbon and/or nitrogen (such as TiN, TaC, HfC, TaSi, ZrC, Hf, etc.) or even a conductive metal oxide (such as IrO 2 ).
• Figure 9 illustrates processing of a semiconductor wafer structure 9 subsequent to Figure 8 after a silicon-containing gate layer 26 is disposed over the metal- based layer 25 to form a metal gate stack.
• the silicon-containing layer 26 is an amorphous or polysilicon cap layer or an amorphous/poly silicon germanium cap layer that is formed using CVD, PECVD, PVD, ALD, MBD, or any combination(s) thereof to a predetermined thickness in the range of 200-1000 Angstroms (e.g., 500-600 Angstroms), though other materials and thicknesses may be used. Silicon-containing layer 26 may also be a doped or undoped amorphous silicon or silicon germanium layer. An anti- reflective coating (ARC) (not shown) may subsequently be formed over silicon-containing gate layer 26 to a thickness in the range of approximately 10 to 200 Angstroms, though other thicknesses may be used.
• ARC anti- reflective coating
• ARC layer is formed by depositing a silicon-rich silicon nitride layer, an organic ARC, a silicon-oxy nitride, or any ARC material which serves an ARC function for the particular lithography process.
• ARC layer may be applied directly to the silicon-containing layer 26 or as part of a multilayer mask on the silicon-containing layer 26.
• the amorphous silicon-containing layer 26 covers the NMOS and PMOS device area 110-113.
• Figure 10 illustrates processing of a semiconductor wafer structure 10 subsequent to Figure 9 after PMOS and NMOS devices 50-53 are formed.
• the metal gate stack is selectively etched to form NMOS and PMOS gate electrodes in the core and DGO device regions 110-113 using any desired pattern and etching processes, including application and patterning of photoresist directly on the ARC layer, though multilayer masking techniques may also be used.
• N-DGO device 50 may be formed in N-DGO region 110
• N-Core device 51 may be formed in N-Core region 111
• P- DGO device 52 may be formed in P-DGO region 112
• P-Core device 53 may be formed in P-Core region 113.
• N-DGO device 50 may include a gate structure including a lower gate oxide region 58 (formed from the first relatively lower high-k layer 22), an upper gate oxide region 60 (formed from the second relatively higher high-k layer 24), a metal gate electrode region 62, and a polysilicon gate electrode region 64.
• N-DGO device 50 may further include spacers 66 formed adjacent to the gate structure.
• N-DGO device 50 may further include source/drain regions 68 and 70 that are implanted at least in part around the gate structure and/or spacers 66.
• N-Core device 51 may include a gate structure including a gate oxide region 72 (formed from the second relatively higher high-k layer 24), a metal gate electrode region 74, and a polysilicon gate electrode region 76.
• N-Core device 52 may further include spacers 78 formed adjacent to the gate structure, and source/drain regions 80 and 82 that are implanted at least in part around the gate structure and/or spacers 78.
• P-DGO device 52 may include silicon germanium region 30.
• P-DGO device 52 may further include a gate structure including a lower gate oxide region 84 (formed from the first relatively lower high-k layer 22), an upper gate oxide region 86 (formed from the second relatively higher high-k layer 24), a metal gate electrode region 88, and a polysilicon gate electrode region 90.
• P-DGO device 52 may further include spacers 92 formed adjacent to the gate structure and source/drain regions 94 and 96 that are implanted at least in part around the gate structure and/or spacers 92.
• P-Core device 53 may include silicon germanium region 32.
• P-Core device 53 may further include a gate structure including a gate oxide region 98 (formed from the second relatively higher high-k layer 24), a metal gate electrode region 100, and a polysilicon gate electrode region 102.
• P-Core device 53 may further include spacers 104 formed adjacent to the gate structure and source/drain regions 106 and 108 that are implanted at least in part around the gate structure and/or spacers 104.
• the inclusion of the lower gate oxide regions 58, 84 in the DGO NMOS and PMOS devices 50, 52 improves the interface quality with the upper gate oxide regions 60, 84 because of the material similarity between the first high-k gate dielectric layer 22 (e.g., HfSiO x ) and the second high-k gate dielectric layer 24 (e.g., HfO 2 ).
• the lower gate oxide regions 58, 84 from a first high-k gate dielectric layer 22 having a relatively lower k (e.g., HfSiO x ), the physical thickness increase required to meet desired electrical oxide thickness (Tox) is minimized, thus ensuring better film quality.
• the formation of the lower gate oxide regions 58, 84 with a relatively low temperature deposition of the first high-k gate dielectric layer 22 reduces the germanium diffusion from the silicon germanium channel layer which leads to high interface state density and TDDB problems, as compared to forming a gate dielectric layer with a high temperature thermal oxide process.
• the formation of the gate oxide regions 72, 98 with the second relatively higher high-k layer 24 provides improved core device performance for the N-Core devices 51 and P-Core devices 53. [031] As will be appreciated, additional or different processing steps may be used to complete the fabrication of the depicted device structures 50-53 into functioning devices.
• additional backend processing steps may be performed, such as forming contact plugs and multiple levels of interconnect(s) that are used to connect the device components in a desired manner to achieve the desired functionality.
• the wafer fabrication process is completed, the wafer can be singulated or diced into separate integrated circuits dies for subsequent electrical connection, such as by leadframe attachment, wirebonding and encapsulation.
• the specific sequence of steps used to complete the fabrication of the device components may vary, depending on the process and/or design requirements.
• a wafer that includes a first semiconductor layer as a semiconductor-on-insulator (SOI) substrate structure or bulk substrate structure with PMOS and NMOS device areas which include a DGO NMOS device area, an NMOS core device area, a DGO PMOS device area and a PMOS core device area.
• a compressive silicon germanium layer is formed, such as by epitaxially growing silicon germanium to a predetermined thickness.
• a deposited first high-k dielectric layer is selectively formed from a first dielectric material (e.g., a silicate or metal oxy-nitride material, such as Hf x Sii_ x O y or Hf x Sii_ x O y N z ) which has a first dielectric constant value greater than 7.0.
• a first dielectric material e.g., a silicate or metal oxy-nitride material, such as Hf x Sii_ x O y or Hf x Sii_ x O y N z
• the selective formation of the first high-k dielectric layer may include blanket depositing the first high-k dielectric layer over the NMOS device area and the PMOS device area (including the compressive silicon germanium layer in the PMOS device area), followed by forming a patterned etch mask to cover the compressive silicon germanium layer and then selectively etching the first high-k dielectric layer to expose the NMOS device area while leaving the first high-k dielectric layer over the compressive silicon germanium layer.
• a low temperature deposition process is used to deposit the silicate or metal oxy-nitride material where the temperature is selected to reduce or eliminate germanium diffusion from the compressive silicon germanium layer.
• a second high-k dielectric layer is deposited over the PMOS and NMOS device areas, where the second high-k dielectric layer is formed from a second dielectric material which has a dielectric constant value that is higher than the first dielectric constant value.
• the second high-k dielectric layer may be a layer OfHfO 2 that is deposited over the first high-k dielectric layer in the PMOS device area and over the first semiconductor layer in the NMOS device area.
• the process further includes depositing one or more gate electrode layers over the second high-k dielectric layer.
• a method of forming devices In another form, there is provided a method of forming devices.
• a first gate dielectric device is formed in a first (DGO) region of a semiconductor substrate, where a compressive silicon germanium layer or silicon carbide layer may be epitaxially grown on a first channel region.
• a first gate dielectric formed is formed by depositing a first high-k dielectric layer (e.g., Hf x Sii_ x O y or Hf x Sii_ x O y N z ) and a second high-k dielectric layer (e.g., HfO 2 ) over the silicon germanium layer in the first channel region of the semiconductor substrate, where the first high-k dielectric layer has a first dielectric constant value that is smaller than a second dielectric constant value for the second high-k dielectric layer.
• a first high-k dielectric layer e.g., Hf x Sii_ x O y or Hf x Sii_ x O y N z
• a second high-k dielectric layer e.g., HfO 2
• the first high-k dielectric layer is deposited as a silicate or metal oxy-nitride material in a deposition process which occurs at a temperature that is selected to reduce or eliminate germanium diffusion from the compressive silicon germanium layer.
• a gate electrode material is deposited over the second high-k dielectric layer.
• the disclosed methodology also forms a second gate dielectric device in a second (core) region of the semiconductor substrate by forming a second gate dielectric that is thinner than the first gate dielectric and that is formed by depositing the second high-k dielectric layer (e.g., HfO 2 ) over a second channel region of the semiconductor substrate.
• a gate electrode material is deposited over the second high-k dielectric layer.
• the disclosed methodology may also form a third gate dielectric device in a third (DGO) region of the semiconductor substrate that includes a third gate dielectric formed by sequentially depositing the first and second high-k dielectric layers over a third channel region of the semiconductor substrate.
• a fourth gate dielectric device may be formed in a fourth (core) region of the semiconductor substrate that includes a fourth gate dielectric that is thinner than the third gate dielectric and that is formed by depositing the second high-k dielectric layer over a fourth channel region of the semiconductor substrate.
• a compressive silicon germanium layer may be epitaxially grown on one or more PMOS channel regions of the semiconductor substrate (e.g., in the first and/or second device areas).
• a first high-k dielectric layer having a first dielectric constant value of 7.0 or greater is formed over the first device area, such as by depositing a layer of Hf x Sii_ x O y or Hf x Sii_ x O y N z on the silicon germanium layer with a deposition process which occurs at a temperature that is selected to reduce or eliminate germanium diffusion from the compressive silicon germanium layer.
• the first high-k dielectric layer may be deposited as a layer of silicate or metal oxy-nitride over the first and second device areas, and then selectively etched from the second device area to expose the semiconductor substrate in the second device area.
• a second high-k dielectric layer e.g., HfO 2
• HfO 2 a second high-k dielectric layer
• One or more gate electrode layers are then over the second high-k dielectric layer and selectively etched to form one or more gate electrode structures over the first and second device areas.
• the first high-k dielectric layer By forming the first high-k dielectric layer over the first device area with a relatively lower dielectric constant value, there is a reduction in the thickness measure for the first high-k dielectric layer in the first device area that is required to meet a predetermined electrical oxide thickness (Tox) requirement as compared to forming the first high-k dielectric layer with a material having a higher dielectric constant value.
• Tox electrical oxide thickness
• the described exemplary embodiments disclosed herein are directed to various semiconductor device structures and methods for making same, the present invention is not necessarily limited to the example embodiments which illustrate inventive aspects of the present invention that are applicable to a wide variety of semiconductor processes and/or devices.
• the process flow is described above with respect to PMOS devices having silicon germanium regions, a similar process flow may be used with NMOS devices having silicon carbon.
• the semiconductor layer 21 could be formed as a silicon carbide layer to change a band gap of an NMOS channel region, in which case the DGO device 52 would be formed as an N-DGO device, and the core device 53 would be formed as an N-Core device.

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• Metal-Oxide And Bipolar Metal-Oxide Semiconductor Integrated Circuits (AREA)
• Insulated Gate Type Field-Effect Transistor (AREA)
• Thin Film Transistor (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)

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• 2009
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