Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/01—Manufacture or treatment
  • H10D30/021—Manufacture or treatment of FETs having insulated gates [IGFET]
  • H10D30/024—Manufacture or treatment of FETs having insulated gates [IGFET] of fin field-effect transistors [FinFET]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/62—Fin field-effect transistors [FinFET]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/01—Manufacture or treatment
  • H10D64/017—Manufacture or treatment using dummy gates in processes wherein at least parts of the final gates are self-aligned to the dummy gates, i.e. replacement gate processes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/20—Electrodes characterised by their shapes, relative sizes or dispositions 
  • H10D64/27—Electrodes not carrying the current to be rectified, amplified, oscillated or switched, e.g. gates
  • H10D64/311—Gate electrodes for field-effect devices
  • H10D64/411—Gate electrodes for field-effect devices for FETs
  • H10D64/511—Gate electrodes for field-effect devices for FETs for IGFETs
  • H10D64/517—Gate electrodes for field-effect devices for FETs for IGFETs characterised by the conducting layers

Definitions

• This invention relates generally to semiconductor processing, and more specifically, to forming a semiconductor device having a fin.
• double gated transistors are desirable because they allow for tighter electrostatic control over the channel so that, for example, smaller dimensions can be achieved.
• Double gated transistor that is currently known is a Fin Field Effect
• FinFETs form gate electrodes over one or more fins, where the regions of the fins that are adjacent the gate electrodes form the channel regions of the devices.
• mechanical stability is reduced. For example, wrapping thin and tall gate electrodes around high aspect fins may result in mechanically unstable gate electrodes. This problem is exacerbated as technology improves and gate lengths continue to scale.
• FIGs. 1-8 illustrates cross sectional views at various points in processing a FinFET device in accordance with an embodiment of the present invention.
• FIG. 9 illustrates a top down view of a FinFET in accordance with an embodiment of the present invention.
• FIG. 10 illustrates a cross sectional view taken through the FinFET of FIG. 9.
• FIGs. 11-16 illustrate cross sectional views at various points in processing a FinFET device in accordance with an alternate embodiment of the present invention.
• a FinFET is formed in which spacers are used to increase mechanical stability while allowing for smaller gate dimensions.
• spacers are formed prior to the formation of the gate electrode which may allow for improved mechanical stability and which may also be used to achieve smaller, sublithographic, dimensions.
• a method for forming a semiconductor device includes providing a semiconductor layer, forming a passivation layer over the semiconductor layer, wherein the passivation layer has an opening having sidewalls, forming a fin over the semiconductor layer, wherein after forming the passivation layer the fin is within the opening, and forming a portion of a gate within the opening.
• the fin is formed before forming the passivation layer.
• the method includes forming spacers along the sidewalls of the opening.
• the method includes forming a dummy gate over the fin, and removing the dummy gate before forming the spacers, where forming the gate is performed after removing the dummy gate.
• forming the gate further includes forming a gate electrode and a gate contact area and forming dummy gate further includes forming a dummy structure for the gate electrode.
• forming the spacers includes depositing a dielectric layer within the opening and over the fin, and anisotropically etching the dielectric layer to remove all portions of the dielectric layer except some portions that are adjacent the passivation layer to form the spacers, wherein the spacers have a first height and the opening of the passivation layer as a second height, wherein the first height is less than the second height.
• the method further includes providing a buried oxide layer over the semiconductor layer, forming a capping layer over the fin, and forming a gate dielectric layer within the opening and over the fin, where forming the fin further includes forming the fin over the buried oxide layer, and forming the gate further includes forming the gate over the gate dielectric layer.
• forming a portion of the gate within the opening further includes forming the portion of the gate so that the portion of the gate has a top portion and a bottom portion, where the top portion is substantially contiguous with a top of the passivation layer and has a first dimension, the bottom portion is adjacent the spacers and has a second dimension between the spacers, the second dimension is parallel to the first dimension, and the first dimension is greater than the second dimension.
• forming the passivation layer further includes depositing a passivation layer, forming a masking layer over the passivation layer, wherein the masking layer has a pattern, and etching the passivation layer using the masking layer to form the opening in the passivation layer.
• forming the fin further includes forming the fin with a first height
• forming the passivation layer further includes forming the passivation layer with a second height, where the second height is greater than the first height
• a method of forming a semiconductor device includes forming a semiconductor layer; forming a passivation layer over the semiconductor layer, wherein the passivation layer has an opening and wherein the opening has sidewalls; forming a fin over the semiconductor layer, where after forming the passivation layer the fin is within the opening of the passivation layer; forming a spacer adjacent the sidewalls of the opening of the passivation; and forming a gate, where a portion of the gate is within the opening of the passivation layer.
• fin is formed before forming the passivation layer.
• forming the gate further includes forming a gate electrode and a gate contact area.
• forming the spacer further includes depositing a dielectric layer within the opening of the passivation layer and over the fin, and anisotropically etching the dielectric layer to remove at least portions of the dielectric layer that are over the fin and at least portions of the dielectric layer that are adjacent the fin to form the spacer along the sidewalls of the opening of the passivation layer.
• the method further includes forming a dummy gate over the fin, and removing the dummy gate before forming the spacer, where forming the gate is performed after removing the dummy gate.
• forming the passivation layer further includes depositing a passivation layer, forming a masking layer over the passivation layer, where the masking layer has a pattern, and etching the passivation layer using the masking layer to form the opening of the passivation layer.
• a semiconductor device in another embodiment, includes a semiconductor layer, a passivation layer over the semiconductor layer, where the passivation layer has an opening and the opening has sidewalls, a fin over the semiconductor layer and within the opening of the passivation layer, spacers adjacent the sidewalls of the opening of the passivation layer, and a gate, where a portion of the gate is within the opening of the passivation layer.
• the portion of the gate within the space has top portion and a bottom portion, the top portion is substantially contiguous with a top of the passivation layer and has a first dimension, the bottom portion is adjacent the spacers and a second dimension between the spacers, the second dimension is parallel to the first dimension, and the first dimension is greater than the second dimension.
• the fin has a first height
• the passivation layer has a second height
• the second height is greater than the first height
• the gate includes a metal gate.
• FIG. 8 illustrates a top down view of a FinFET semiconductor device which may be formed in accordance with various embodiments of the present invention.
• Device 10 includes a fin portion 16 having a first source/drain region 44 at one end and a second source/drain region 46 at an opposite end.
• a gate electrode 38 is formed over fin 16.
• Device 10 also includes a gate contact area 40 at one end of gate electrode 38.
• Gate contact area 40 includes gate contacts 42.
• Device 10 also includes a spacer 28 which underlies gate electrode 38 and gate contact area 40. The portion of fin 16 which underlies spacer 28 and gate electrode 38 forms the channel region of device 10. Note that gate electrode 38 and gate contact area 40 may be referred to as a gate of device 10.
• the format of device 10 is exemplary and alternate embodiments may include any number of variations.
• a gate contact area may be located at both ends of gate electrode 38.
• the shapes of source/drain regions 44 and 46 may also differ in different embodiments.
• FIG. 8 illustrates only a single fin 16; however, alternate embodiments may include any number of fins where gate electrode 38 may therefore be formed over the fins.
• any number of gate contacts may be formed.
• device 10 may also include any number of source/drain contacts which would contact source/drain regions 44 and 46.
• FIGs. 1-7 illustrate cross sectional view of various processing steps which may be used to form the device of FIG. 8.
• FIG. 1 illustrates device 10 after formation of fin 16, passivation 20, and a patterned masking layer 22.
• Device 10 includes a layer 12 and an insulating layer 14 overlying layer 12.
• layer 12 includes a semiconductor layer such as, for example, a silicon layer.
• layer 12 can be formed of any material and may be used to provide support for insulating layer 14.
• insulating layer 14 is an oxide. Insulating layer 14 may also be referred to as a buried oxide layer.
• Fin 16 is formed over insulating layer 14 and may include a semiconductor material, such as, for example, silicon or silicon germanium.
• fin 16 also includes a capping layer 18 which may be, for example, a nitride.
• fin 16 is formed using a semiconductor-on-insulator (SOI) wafer.
• SOI semiconductor-on-insulator
• an SOI wafer is provided having a semiconductor layer overlying an insulating layer (such as insulating layer 14) which overlies a layer (such as layer 12).
• the semiconductor layer of the provided SOI can then be patterned to form one or more fins such as fin 16.
• capping layer 18 is present, a layer can be formed over the SOI wafer prior to patterning the fin to result in capping layer 18 and fin 16. (Note that capping layer 18 may also be referred to as a cap.)
• Passivation layer 20 is formed over insulating layer 14 and fin 16.
• passivation layer 20 is deposited using, for example, tetraethylorthosilicate (TEOS).
• TEOS tetraethylorthosilicate
• Patterned masking layer 22 is formed over passivation layer 20, where patterned masking layer defines an opening corresponding to gate electrode 38 and gate contact area 40.
• patterned masking layer includes photoresist.
• FIG. 2 illustrates device 10 after using patterned masking layer 22 to remove (for example, etch) portions of passivation layer 20 over fin 16 to form an opening 24.
• Opening 24 defines the location of at least a portion of the gate of device 10.
• opening 24 may define the location of gate electrode 38 and gate contact area 40.
• opening 24 within passivation layer 20 is a cross-section of a cavity within passivation layer 20.
• fin 16 is within opening 24.
• FIG. 3 illustrates device 10 after formation of a spacer layer 26 over passivation layer 20 and over insulating layer 14 and fin 16 (and capping layer 18, if present) within opening 24.
• Spacer layer 26 may be formed, for example, using a deposition process.
• spacer layer 26 includes an oxide. Note that spacer layer 26 may include any suitable dielectric and may therefore also be referred to as a dielectric layer.
• FIG. 4 illustrates device 10 during an intermediate stage of anisotropically etching spacer layer 26 to form spacers 28 adjacent sidewalls of passivation layer 20 and spacers 30 adjacent sidewalls of fin 16.
• the anisotropic etch is continued, as illustrated in FIG. 5, until spacers 30 are removed.
• a height of spacers 28 is less than the height of passivation layer 20.
• Spacers 28, as will be discussed further below, may be used to increase mechanical stability of device 10 and may also be used to achieve smaller gate lengths. (Note that although, in FIGs.
• spacers 30 and 28 each appear to include separate portions due to the illustrated cross section, they may each be portions of a single spacer, as illustrated with respect to spacer 28 in the top down view of FIG. 8. Therefore, each of spacers 28 and 30 may also be referred to as spacer 28 and spacer 30, respectively.
• FIG. 6 illustrates device 10 after formation of a gate dielectric layer 32 over passivation layer 20, spacer 28, fin 16 (and capping layer 18, if present), and insulating layer 14.
• Gate dielectric layer 32 may include any type of gate dielectric material such as an oxide or metal oxide.
• Gate dielectric layer 32 may include a material having a dielectric constant (K) greater than that of silicon dioxide (which may therefore be referred to as a high K material), such as, for example, hafnium oxide.
• gate dielectric 32 is deposited by chemical vapor deposition (CVD) or atomic layer deposition (ALD), as shown in FIG. 6.
• gate dielectric layer 32 may be grown on sidewalls of fin 16.
• gate dielectric layer 32 may be, e.g., grown silicon dioxide or silicon oxynitride. Also, in this alternate embodiment, gate dielectric layer 32 would only be grown on sidewalls of fin 16.
• gate layer 34 is then formed over gate dielectric layer 32.
• Gate layer 34 may include any type of gate material or materials.
• gate layer 34 may include silicon or may include a metal.
• gate layer 34 may include any number of different layers, where gate layer 34 may represent a gate stack layer.
• FIG. 7 illustrates device 10 after planarizing gate layer 34 to form gate 36.
• Gate 36 includes a gate electrode portion (gate electrode 38) and a gate contact portion (gate contact area 40).
• a top portion of gate 36 is substantially contiguous with a top of passivation layer 20. Therefore, note that FIG. 7 corresponds to a horizontal cross section taken through the top down view of device 10 of FIG. 8, which was described above.
• FIG. 9 illustrates a cross sectional view corresponding to a cross section taken through the middle of source/drain regions 44 and 46 and fin 16.
• the cross section is taken at the same location through the top down view of device 10 of FIG. 8 as the cross section of FIG. 10; however, in FIG. 9, passivation layer 20 is still present. Therefore, gate 36 and spacer 28 is shown overlying fin 16 (and capping layer 18, if present). Note that the portion of fin 16 underlying gate 36 in FIG. 9 includes a channel region of device 10. Also, note that dimension 48, which corresponds to the opening width defined by patterned masking layer 22, is greater than dimension 50 which corresponds to the actual gate length of device 10.
• dimension 48 corresponds to a length of a top portion of gate 36 that is substantially contiguous with a top of passivation layer 20
• dimension 50 corresponds to a length of bottom portion of gate 36 that is adjacent spacers 28. Therefore, note that spacer 28 may be used to achieve gate lengths that are shorter than what may be available through the use of patterned masking layer 22 or other lithographic techniques.
• FIG. 10 corresponding to a cross section taken through the top down view of FIG. 8, illustrates device 10 after removal of passivation layer 20.
• spacer 28 remains along sides of gate 36. Therefore, spacer 28 may provide mechanical support to gate 36, thus allowing for a more mechanically stable device as compared to current FinFET devices.
• conventional processing may be used to substantially complete the FinFET device. For example, spacers may be formed along sidewalls of gate 36 and spacer 28 using conventional processing techniques. Also, conventional implants may be used to form source/drain regions 44 and 46.
• FIGs. 11-16 illustrate cross sectional views of device 10 which is formed in accordance with an alternate embodiment of the present invention and also results in device 10 of FIG. 8.
• FIG. 11 illustrates layer 12, insulating layer 14, fin 16, and capping layer 18, all of which were described above in reference to FIG. 1.
• a patterned dummy gate layer 52 is formed over fin 16 and capping layer 18. Since dummy gate layer 52 will be later removed, it may be formed of any suitable easily removable material.
• source/drain implants may be formed after forming dummy gate layer 52. In this manner, dummy gate layer 52 may protect fin 16 during the implants.
• Dummy gate layer 52 may be considered a dummy structure for at least a portion of the subsequently formed gate electrode 38.
• FIG. 12 illustrates device 10 after formation of a passivation layer 54 over dummy gate layer 52.
• Passivation layer 54 is analogous to passivation layer 20 and may be formed using the same processes and materials.
• FIG. 13 illustrates device 10 after planarization of passivation layer 54 to expose a top portion of dummy gate layer 52.
• FIG. 14 illustrates device 10 after removal of dummy gate layer 52. Note that fin 16 and capping layer 18 remain. Therefore, the removal of dummy gate layer 52 results in an opening 51 within passivation layer 54 in which fin 16 is located. That is, note that opening 51 in passivation layer 54 is a cross-section of a cavity within passivation layer 54. Note that opening 51 is similar to opening 24 described above. However, while opening 24 defines the location of gate electrode 38 and gate contact area 44, opening 51 defines the location of a portion of the gate overlying fin 16.
• FIG. 15 illustrates formation of spacers 56 adjacent sidewalls of passivation layer 54.
• Spacers 56 are analogous to spacers 28 discussed above and can be formed using the same methods and materials discussed above with respect to spacers 28.
• an anisotropic etch of a spacer layer can be used to form spacers 56, where spacers 56 may include a dielectric material, such as an oxide.
• passivation layer 54 has a greater height than fin 16, allowing for the formation of spacers 56 on sidewalls of passivation layer 54 without the formation of spacers adjacent sidewalls of fin 16.
• a height of passivation layer 54 is greater than a height of spacers 56. (As discussed above with respect to spacers 30 and 28, note that spacers 56 appear to include separate portions due to the illustrated cross section; however, they may be portions of a single spacer. Therefore, spacers 56 may also be referred to as spacer 56.)
• a gate dielectric layer 58 is formed over passivation layer 54, and over spacers 56, insulating layer 14, and fin 16 within opening 51.
• a gate layer 60 is formed over gate dielectric layer 58.
• Gate dielectric layer 58 and gate layer 60 are analogous to gate dielectric layer 32, and gate layer 34, respectively, discussed above and can be formed using the same methods and materials discussed above with respect to gate dielectric layer 32 and gate layer 34.
• FIG. 16 illustrates device 10 after patterning and etching gate layer 60 to form gate electrode 38 and gate contact area 40.
• resulting gate 60 is not substantially contiguous with a top of passivation layer 54, but instead extends over passivation layer 54 to form the remaining portion of gate electrode 38 and gate contact area 40. Therefore, note that gate 60 would appear as illustrated in FIG. 8. However, note that spacer 56 would only be located under a portion of gate electrode 38 rather than under all of gate electrode 38 and gate contact area 40, as illustrated in FIG. 8 with respect to spacer 28. Also, in the embodiments of FIGs.
• plurality is defined as two or more than two.
• another is defined as at least a second or more.
• Coupled is defined as connected, although not necessarily directly, and not necessarily mechanically.

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• Thin Film Transistor (AREA)
• Insulated Gate Type Field-Effect Transistor (AREA)
• Electrodes Of Semiconductors (AREA)

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• 2006
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