US20210273089A1 - Semiconductor device and fabrication method thereof - Google Patents

Semiconductor device and fabrication method thereof Download PDF

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Publication number
US20210273089A1
US20210273089A1 US17/321,517 US202117321517A US2021273089A1 US 20210273089 A1 US20210273089 A1 US 20210273089A1 US 202117321517 A US202117321517 A US 202117321517A US 2021273089 A1 US2021273089 A1 US 2021273089A1
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Prior art keywords
trench
stress
semiconductor device
fins
isolation
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US17/321,517
Inventor
Shih-Wei Su
Hao-Hsuan Chang
Chih-Wei Chang
Chi-Hsuan Cheng
Ting-An Chien
Bin-Siang Tsai
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United Microelectronics Corp
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United Microelectronics Corp
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Abandoned legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/785—Field effect transistors with field effect produced by an insulated gate having a channel with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
    • 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
    • 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
    • H01L21/76224—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using trench refilling with dielectric materials
    • H01L21/76229—Concurrent filling of a plurality of trenches having a different trench shape or dimension, e.g. rectangular and V-shaped trenches, wide and narrow trenches, shallow and deep trenches
    • 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
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76841—Barrier, adhesion or liner layers
    • H01L21/7685—Barrier, adhesion or liner layers the layer covering a conductive structure
    • H01L21/76852—Barrier, adhesion or liner layers the layer covering a conductive structure the layer also covering the sidewalls of the conductive structure
    • 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
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
    • H01L21/76877—Filling of holes, grooves or trenches, e.g. vias, with conductive material
    • 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
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
    • H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
    • H01L21/8232—Field-effect technology
    • H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
    • H01L21/823431—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type with a particular manufacturing method of transistors with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
    • 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
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
    • H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
    • H01L21/8232—Field-effect technology
    • H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
    • H01L21/823481—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type isolation region manufacturing related aspects, e.g. to avoid interaction of isolation region with adjacent structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007—Multistep manufacturing processes
    • H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
    • H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
    • H01L29/66409—Unipolar field-effect transistors
    • H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
    • H01L29/66787—Unipolar field-effect transistors with an insulated gate, i.e. MISFET with a gate at the side of the channel
    • H01L29/66795—Unipolar field-effect transistors with an insulated gate, i.e. MISFET with a gate at the side of the channel with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
    • 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
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H01L21/82—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components
    • H01L21/822—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices to produce devices, e.g. integrated circuits, each consisting of a plurality of components the substrate being a semiconductor, using silicon technology
    • H01L21/8232—Field-effect technology
    • H01L21/8234—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type
    • H01L21/823412—MIS technology, i.e. integration processes of field effect transistors of the conductor-insulator-semiconductor type with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials

Definitions

  • the present invention relates to the field of semiconductor process technology, and more particularly to a method for forming semiconductor fin structures with improved fin height profile control.
  • nonplanar FETs such as the fin field effect transistor (finFET) have three-dimensional structure, not only capable of increasing the contact to the gate but also improving the controlling of the channel region, such that the nonplanar FETs have replaced the planar FETs and become the mainstream of the development.
  • the current method of forming the finFETs is forming a fin structure on a substrate primary, and then forming a gate on the fin structure.
  • the fin structure generally includes the stripe-shaped fin formed by etching the substrate.
  • the width of each fin, as well as the pitch between fins have to be shrunk accordingly.
  • the fabricating process of the finFETs also faces more challenges and limitations.
  • the semiconductor device and method of forming the same does still not fully meet the demand of the product, and requires further improvement.
  • the invention provides an improved semiconductor device and a manufacturing method thereof, which can improve fin height profile control and device performance.
  • One aspect of the invention provides a method for forming a semiconductor device.
  • a substrate having at least two fins thereon and an isolation trench between the at least two fins is provided.
  • a liner layer is then deposited on the substrate.
  • the liner layer conformally covers the two fins and interior surface of the isolation trench.
  • a stress-buffer film is then deposited on the liner layer.
  • the stress-buffer film completely fills a lower portion that is located at least below half of a trench depth of the isolation trench.
  • a trench-fill oxide layer is then deposited to completely fill an upper portion of the isolation trench.
  • the liner layer is a silicon oxide layer deposited by performing an atomic layer deposition (ALD) process.
  • ALD atomic layer deposition
  • the stress-buffer film comprises amorphous silicon.
  • the stress-buffer film has a thickness that is greater than or equal to about 40 angstroms at a fin pitch of about 48 nm.
  • the stress-buffer film has a thickness ranging between about 40 angstroms and about 80 angstroms at a fin pitch of about 48 nm.
  • the trench-fill oxide layer is a silicon oxide layer deposited by performing a flowable chemical vapor deposition (FCVD) process.
  • FCVD flowable chemical vapor deposition
  • the method further comprises: subjecting the trench-fill oxide layer to an anneal process.
  • the stress-buffer film is converted to silicon suboxide film of formula SiOy, wherein y ⁇ 2.
  • the method further comprises: polishing the trench-fill oxide layer, the stress-buffer film, and the liner layer until a top surface of the at least two fins is exposed; and recess etching the trench-fill oxide layer, the stress-buffer film, and the liner layer, thereby exposing an upper portion of the each of the at least two fins.
  • a semiconductor device including a substrate having at least two fins thereon and an isolation trench between the at least two fins; and an isolation structure in the isolation trench.
  • the isolation structure consists of a liner layer covering a lower sidewall of each of the at least two fins and a bottom surface of the isolation trench, and a stress-buffer film on the liner layer.
  • the stress-buffer film is a silicon suboxide film of formula SiOy, wherein y ⁇ 2.
  • FIGS. 1-4 are schematic diagrams illustrating a method of forming a semiconductor device according to one embodiment of the present invention.
  • FIGS. 1-4 are schematic diagrams illustrating a method of forming a semiconductor device according to one embodiment of the present invention.
  • a substrate 100 having multiple fins 300 thereon is provided.
  • the multiple fins 300 are separated from one another by isolation trenches 120 having a trench depth d.
  • the substrate 100 may include a semiconductor substrate such as a silicon containing substrate or a silicon-on-insulator (SOI) substrate.
  • SOI silicon-on-insulator
  • the substrate 100 may include a dense region 101 and an isolated region 102 .
  • the fins 300 may be disposed in the dense region 101 and the isolated region 102 of the substrate 100 but in different pitches, as shown in FIG. 1 .
  • the pitch of the fins 300 in the dense region 101 is smaller than the pitch of the fins 300 in the isolated region 102 .
  • the fins 300 in the dense region 101 may have a fin pitch P of about 48 nm, which is the combination of the fin critical dimension (FCD) and the trench width W.
  • FCD fin critical dimension
  • the fin critical dimension (FCD) may be 13 nm and the trench width W may be 35 nm, but is not limited thereto.
  • the fins 300 may be formed through a self-aligned double patterning (SADP) process, such as sidewall image transfer (SIT) process.
  • SADP self-aligned double patterning
  • SIT sidewall image transfer
  • the formation of the fins 300 includes forming a plurality of mandrels (not shown in the drawings) on the substrate 100 by using a photolithography and an etching process, performing a depositing and an etching processes sequentially to form a plurality of spacers (not shown in the drawings) at sidewalls of the mandrels, using the spacers as a mask to form a patterned hard mask underneath, and then, forming a plurality of isolation trenches 120 in the substrate 100 to define the fins 300 .
  • SADP self-aligned double patterning
  • SIT sidewall image transfer
  • the formation of the fins 300 may also be accomplished by first forming a patterned hard mask (not shown in the drawings) on the substrate 100 , and then performing an epitaxial process on the exposed substrate 100 through the patterned hard mask to form a semiconductor layer (not shown in the drawings) such as silicon or silicon germanium layer to configure as corresponding fin shaped structures.
  • a fin cut process (not shown in the drawings) may be performed to remove unwanted portions of the fins.
  • the isolation trenches 120 between the fins 300 are filled with an isolation layer 310 .
  • the isolation layer 310 includes a liner layer 311 , a stress-buffer layer 312 on the liner layer 311 , and a trench-fill oxide layer 313 on the stress-buffer film 312 .
  • the liner layer 311 is formed right after the fins 300 are formed, by depositing an oxide layer on the substrate 100 in a blanket manner through an atomic layer deposition (ALD) process.
  • the liner layer 311 conformally covers the fins 300 and interior surface of the isolation trenches 120 .
  • the liner layer 311 may be a silicon oxide layer and may have a thickness of about 50 ⁇ 70 angstroms, but is not limited thereto.
  • the stress-buffer film 312 is deposited directly on the liner layer 311 . Therefore, the stress-buffer film 312 is in direct contact with the liner layer 311 .
  • the stress-buffer film 312 completely fills a lower portion 120 b that is located at least below half of a trench depth d of the isolation trenches 120 .
  • the stress-buffer film 312 may be an amorphous silicon layer and may have a thickness of about 40 ⁇ 80 angstroms, but is not limited thereto.
  • the stress-buffer film 312 may have a thickness that is greater than or equal to about 40 angstroms at a fin pitch P of about 48 nm.
  • the stress-buffer film 312 may have a thickness ranging between about 40 angstroms and about 80 angstroms at a fin pitch P of about 48 nm.
  • the trench-fill oxide layer 313 is deposited directly on the stress-buffer film 312 . Therefore, the trench-fill oxide layer 313 is in direct contact with the stress-buffer film 312 .
  • the trench-fill oxide layer 313 completely fills an upper portion 120 a of each of the isolation trenches 120 .
  • the trench-fill oxide layer 313 is a silicon oxide layer deposited by performing a flowable chemical vapor deposition (FCVD) process.
  • an annealing process 400 is performed to anneal the trench-fill oxide layer 313 .
  • the annealing process 400 may be performed at a temperature of about 1000° C., but is not limited thereto.
  • the stress-buffer film 312 may be converted to silicon suboxide film of formula SiOy, wherein y ⁇ 2.
  • the trench-fill oxide layer may be a silicon oxide film of formula SiOx, wherein x ⁇ y.
  • a planarization process may be performed to polish the trench-fill oxide layer 313 , the stress-buffer film 312 , and the liner layer 311 until the top surfaces of the fins 300 are exposed. Subsequently, the remaining trench-fill oxide layer 313 , the stress-buffer film 312 , and the liner layer 311 are recess etched, thereby exposing the upper portion of the each of the fins 300 .
  • the above-mentioned fin-recess process is known in the art.
  • the trench-fill oxide layer 313 , the stress-buffer film 312 , and the liner layer 311 may be etched by using SiCoNi dry etching process.
  • the SiCoNi dry etching process primarily includes the step of reacting the fluorine-containing gas with the silicon oxide to synthesize diammonium fluosilicate ((NH 4 ) 2 SiF 6 ). In this way, the silicon oxide can be selectively removed.
  • the aforesaid fluorine-containing gas may comprise hydrogen fluoride (HF) or nitrogen trifluoride (NF 3 ).
  • a wicking structure 320 with a height h may be defined between a peak adjacent to the sidewall surface of the fin 300 and a lowest point of the top surface 312 a of the stress-buffer film 312 in the dense region 101 .
  • the wicking structure 320 is formed between the fins 300 with a small pitch and covers the sidewalls of the fins 300 as shown in FIG. 4 .
  • the wicking structure 320 on the fins 300 affects the effective height of the fins 300 and adversely affects the performance of the semiconductor device. Therefore, it is desired to reduce the height h of the wicking structure 320 as much as possible.
  • the present disclosure addresses this issue by providing a stress-buffer film 312 in the isolation layer 310 .
  • the stress-buffer film 312 and the liner layer 311 constitute the isolation structure in each of the isolation trenches 120 in the dense region 101
  • the stress-buffer film 312 and the liner layer 311 constitute the isolation structure in each of the isolation trenches 120 .
  • the height h of the wicking structure 320 may be reduced to about 1.74 nm in a case that the stress-buffer film 312 has a thickness of about 40 angstroms at a fin pitch P of about 48 nm.
  • a semiconductor device 1 comprises a substrate 100 having at least two fins 300 thereon and an isolation trench 120 between the at least two fins 300 .
  • An isolation structure 310 is disposed in the isolation trench 120 .
  • the isolation structure 310 consists of a liner layer 311 covering a lower sidewall of each of the at least two fins 300 and a bottom surface of the isolation trench 120 , and a stress-buffer film 312 on the liner layer 311 .
  • the stress-buffer film 312 is a silicon suboxide film of formula SiOy, wherein y ⁇ 2.
  • the height h of the wicking structure can be reduced by introducing the stress-buffer film 312 on the liner layer 311 in the isolation trenches 120 .

Abstract

A semiconductor device includes a substrate having at least two fins thereon and an isolation trench between the at least two fins; and an isolation structure in the isolation trench. The isolation structure consists of a liner layer covering a lower sidewall of each of the at least two fins and a bottom surface of the isolation trench, and a stress-buffer film on the liner layer. The stress-buffer film is a silicon suboxide film of formula SiOy, wherein y<2.

Description

    CROSS REFERENCE TO RELATED APPLICATIONS
  • This is a division of U.S. application Ser. No. 16/451,018 filed Jun. 25, 2019, which is included in its entirety herein by reference.
    • BACKGROUND OF THE INVENTION Field of the Invention
  • The present invention relates to the field of semiconductor process technology, and more particularly to a method for forming semiconductor fin structures with improved fin height profile control.
    • Description of the Prior Art
  • With increasing miniaturization of semiconductor devices, it is crucial to maintain the efficiency of miniaturized semiconductor devices in the industry. However, as the size of the field effect transistors (FETs) is continuously shrunk, the development of the planar FETs faces more limitations in the fabricating process thereof. On the other hand, nonplanar FETs, such as the fin field effect transistor (finFET) have three-dimensional structure, not only capable of increasing the contact to the gate but also improving the controlling of the channel region, such that the nonplanar FETs have replaced the planar FETs and become the mainstream of the development.
  • The current method of forming the finFETs is forming a fin structure on a substrate primary, and then forming a gate on the fin structure. The fin structure generally includes the stripe-shaped fin formed by etching the substrate. However, under the requirements of continuous miniaturization, the width of each fin, as well as the pitch between fins have to be shrunk accordingly. Thus, the fabricating process of the finFETs also faces more challenges and limitations. Hence, the semiconductor device and method of forming the same does still not fully meet the demand of the product, and requires further improvement.
    • SUMMARY OF THE INVENTION
  • The invention provides an improved semiconductor device and a manufacturing method thereof, which can improve fin height profile control and device performance.
  • One aspect of the invention provides a method for forming a semiconductor device is disclosed. A substrate having at least two fins thereon and an isolation trench between the at least two fins is provided. A liner layer is then deposited on the substrate. The liner layer conformally covers the two fins and interior surface of the isolation trench. A stress-buffer film is then deposited on the liner layer. The stress-buffer film completely fills a lower portion that is located at least below half of a trench depth of the isolation trench. A trench-fill oxide layer is then deposited to completely fill an upper portion of the isolation trench.
  • According to some embodiment, the liner layer is a silicon oxide layer deposited by performing an atomic layer deposition (ALD) process.
  • According to some embodiment, the stress-buffer film comprises amorphous silicon.
  • According to some embodiment, the stress-buffer film has a thickness that is greater than or equal to about 40 angstroms at a fin pitch of about 48 nm.
  • According to some embodiment, the stress-buffer film has a thickness ranging between about 40 angstroms and about 80 angstroms at a fin pitch of about 48 nm.
  • According to some embodiment, the trench-fill oxide layer is a silicon oxide layer deposited by performing a flowable chemical vapor deposition (FCVD) process.
  • According to some embodiment, the method further comprises: subjecting the trench-fill oxide layer to an anneal process.
  • According to some embodiment, during the anneal process, the stress-buffer film is converted to silicon suboxide film of formula SiOy, wherein y<2.
  • According to some embodiment, the method further comprises: polishing the trench-fill oxide layer, the stress-buffer film, and the liner layer until a top surface of the at least two fins is exposed; and recess etching the trench-fill oxide layer, the stress-buffer film, and the liner layer, thereby exposing an upper portion of the each of the at least two fins.
  • Another aspect of the invention provides a semiconductor device including a substrate having at least two fins thereon and an isolation trench between the at least two fins; and an isolation structure in the isolation trench. The isolation structure consists of a liner layer covering a lower sidewall of each of the at least two fins and a bottom surface of the isolation trench, and a stress-buffer film on the liner layer. The stress-buffer film is a silicon suboxide film of formula SiOy, wherein y<2.
  • These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIGS. 1-4 are schematic diagrams illustrating a method of forming a semiconductor device according to one embodiment of the present invention.
    •  DETAILED DESCRIPTION
  • In the following detailed description of the disclosure, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention.
  • Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be considered as limiting, but the embodiments included herein are defined by the scope of the accompanying claims.
  • FIGS. 1-4 are schematic diagrams illustrating a method of forming a semiconductor device according to one embodiment of the present invention. As shown in FIG. 1, a substrate 100 having multiple fins 300 thereon is provided. The multiple fins 300 are separated from one another by isolation trenches 120 having a trench depth d. For example, the substrate 100 may include a semiconductor substrate such as a silicon containing substrate or a silicon-on-insulator (SOI) substrate. The substrate 100 may include a dense region 101 and an isolated region 102. The fins 300 may be disposed in the dense region 101 and the isolated region 102 of the substrate 100 but in different pitches, as shown in FIG. 1. The pitch of the fins 300 in the dense region 101 is smaller than the pitch of the fins 300 in the isolated region 102. According to one embodiment, the fins 300 in the dense region 101 may have a fin pitch P of about 48 nm, which is the combination of the fin critical dimension (FCD) and the trench width W. For example, the fin critical dimension (FCD) may be 13 nm and the trench width W may be 35 nm, but is not limited thereto.
  • According to one embodiment, the fins 300 may be formed through a self-aligned double patterning (SADP) process, such as sidewall image transfer (SIT) process. For example, the formation of the fins 300 includes forming a plurality of mandrels (not shown in the drawings) on the substrate 100 by using a photolithography and an etching process, performing a depositing and an etching processes sequentially to form a plurality of spacers (not shown in the drawings) at sidewalls of the mandrels, using the spacers as a mask to form a patterned hard mask underneath, and then, forming a plurality of isolation trenches 120 in the substrate 100 to define the fins 300. However, in another embodiment, the formation of the fins 300 may also be accomplished by first forming a patterned hard mask (not shown in the drawings) on the substrate 100, and then performing an epitaxial process on the exposed substrate 100 through the patterned hard mask to form a semiconductor layer (not shown in the drawings) such as silicon or silicon germanium layer to configure as corresponding fin shaped structures. A fin cut process (not shown in the drawings) may be performed to remove unwanted portions of the fins.
  • As shown in FIG. 2, the isolation trenches 120 between the fins 300 are filled with an isolation layer 310. According to one embodiment, the isolation layer 310 includes a liner layer 311, a stress-buffer layer 312 on the liner layer 311, and a trench-fill oxide layer 313 on the stress-buffer film 312. According to one embodiment, the liner layer 311 is formed right after the fins 300 are formed, by depositing an oxide layer on the substrate 100 in a blanket manner through an atomic layer deposition (ALD) process. The liner layer 311 conformally covers the fins 300 and interior surface of the isolation trenches 120. For example, the liner layer 311 may be a silicon oxide layer and may have a thickness of about 50˜70 angstroms, but is not limited thereto.
  • The stress-buffer film 312 is deposited directly on the liner layer 311. Therefore, the stress-buffer film 312 is in direct contact with the liner layer 311. The stress-buffer film 312 completely fills a lower portion 120 b that is located at least below half of a trench depth d of the isolation trenches 120. For example, the stress-buffer film 312 may be an amorphous silicon layer and may have a thickness of about 40˜80 angstroms, but is not limited thereto. For example, the stress-buffer film 312 may have a thickness that is greater than or equal to about 40 angstroms at a fin pitch P of about 48 nm. For example, the stress-buffer film 312 may have a thickness ranging between about 40 angstroms and about 80 angstroms at a fin pitch P of about 48 nm.
  • The trench-fill oxide layer 313 is deposited directly on the stress-buffer film 312. Therefore, the trench-fill oxide layer 313 is in direct contact with the stress-buffer film 312. The trench-fill oxide layer 313 completely fills an upper portion 120 a of each of the isolation trenches 120. According to one embodiment, the trench-fill oxide layer 313 is a silicon oxide layer deposited by performing a flowable chemical vapor deposition (FCVD) process.
  • Subsequently, as shown in FIG. 3, an annealing process 400 is performed to anneal the trench-fill oxide layer 313. For example, the annealing process 400 may be performed at a temperature of about 1000° C., but is not limited thereto. According to one embodiment, the stress-buffer film 312 may be converted to silicon suboxide film of formula SiOy, wherein y<2. According to one embodiment, the trench-fill oxide layer may be a silicon oxide film of formula SiOx, wherein x<y.
  • As shown in FIG. 4, a planarization process (not shown in the drawings) may be performed to polish the trench-fill oxide layer 313, the stress-buffer film 312, and the liner layer 311 until the top surfaces of the fins 300 are exposed. Subsequently, the remaining trench-fill oxide layer 313, the stress-buffer film 312, and the liner layer 311 are recess etched, thereby exposing the upper portion of the each of the fins 300. The above-mentioned fin-recess process is known in the art. For example, the trench-fill oxide layer 313, the stress-buffer film 312, and the liner layer 311 may be etched by using SiCoNi dry etching process. In one embodiment of the present invention, the SiCoNi dry etching process primarily includes the step of reacting the fluorine-containing gas with the silicon oxide to synthesize diammonium fluosilicate ((NH4)2SiF6). In this way, the silicon oxide can be selectively removed. The aforesaid fluorine-containing gas may comprise hydrogen fluoride (HF) or nitrogen trifluoride (NF3).
  • In FIG. 4, a wicking structure 320 with a height h may be defined between a peak adjacent to the sidewall surface of the fin 300 and a lowest point of the top surface 312 a of the stress-buffer film 312 in the dense region 101. The wicking structure 320 is formed between the fins 300 with a small pitch and covers the sidewalls of the fins 300 as shown in FIG. 4. The wicking structure 320 on the fins 300 affects the effective height of the fins 300 and adversely affects the performance of the semiconductor device. Therefore, it is desired to reduce the height h of the wicking structure 320 as much as possible. The present disclosure addresses this issue by providing a stress-buffer film 312 in the isolation layer 310.
  • It is noteworthy that in the dense region 101, only the stress-buffer film 312 and the liner layer 311 are left in the isolation trenches 120. Therefore, the stress-buffer film 312 and the liner layer 311 constitute the isolation structure in each of the isolation trenches 120 in the dense region 101, while in the isolated region 102 the trench-fill oxide layer 313, the stress-buffer film 312 and the liner layer 311 constitute the isolation structure in each of the isolation trenches 120. By providing such configuration, the height h of the wicking structure 320 may be reduced to about 1.74 nm in a case that the stress-buffer film 312 has a thickness of about 40 angstroms at a fin pitch P of about 48 nm.
  • Structurally, as shown in FIG. 4, a semiconductor device 1 comprises a substrate 100 having at least two fins 300 thereon and an isolation trench 120 between the at least two fins 300. An isolation structure 310 is disposed in the isolation trench 120. The isolation structure 310 consists of a liner layer 311 covering a lower sidewall of each of the at least two fins 300 and a bottom surface of the isolation trench 120, and a stress-buffer film 312 on the liner layer 311. The stress-buffer film 312 is a silicon suboxide film of formula SiOy, wherein y<2.
  • It is advantageous to use the present disclosure because the height h of the wicking structure can be reduced by introducing the stress-buffer film 312 on the liner layer 311 in the isolation trenches 120.
  • Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims (10)

What is claimed is:
1. A semiconductor device, comprising:
a substrate having at least two fins thereon and a first isolation trench between the at least two fins, wherein the first isolation trench is disposed within a first region; and
a first isolation structure in the first isolation trench, wherein the first isolation structure consists of a liner layer covering a lower sidewall of each of the at least two fins and a bottom surface of the first isolation trench, and a stress-buffer film on the liner layer, wherein the stress-buffer film is a silicon suboxide film of formula SiOy, wherein y<2.
2. The semiconductor device of claim 1 further comprising:
a second isolation trench in the substrate within a second region; and
a second isolation structure in the second isolation trench, wherein the second isolation structure comprising the liner layer, the stress-buffer film, and a trench-fill oxide layer on the stress-buffer film.
3. The semiconductor device of claim 2, wherein the first region is a dense region and the second region is an isolated region.
4. The semiconductor device of claim 2, wherein a width of the second isolation trench is greater than that of the first isolation trench.
5. The semiconductor device of claim 2, wherein the liner layer is a silicon dioxide layer.
6. The semiconductor device of claim 2, wherein the trench-fill oxide layer may be a silicon oxide film of formula SiOx, wherein x<y.
7. The semiconductor device of claim 1, wherein a lower portion of the first isolation trench does not include the trench-fill oxide layer.
8. The semiconductor device of claim 7, wherein the lower portion is located at least below half of a trench depth of the first isolation trench within the first region.
9. The semiconductor device of claim 1, wherein the stress-buffer film has a thickness that is greater than or equal to about 40 angstroms at a fin pitch of about 48 nm.
10. The semiconductor device of claim 1, wherein the stress-buffer film has a thickness ranging between about 40 angstroms and about 80 angstroms at a fin pitch of about 48 nm.
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