阅读说明：本技术 半导体器件的形成方法 (Method for forming semiconductor device ) 是由 张海洋 韩秋华 郑二虎 涂武涛 于 2020-05-07 设计创作，主要内容包括：本发明提供一种半导体结构的形成方法,所述方法包括：提供基底；在所述基底上形成伪栅极结构和覆盖伪栅极结构侧壁的底部介质层；刻蚀去除所述伪栅极结构,在所述底部介质层中形成栅开口；在所述栅开口的内壁形成高k栅介质层；形成所述高k栅介质层之后,对所述高k栅介质层执行远端等离子体处理工艺；对所述高k栅介质层执行远端等离子体工艺之后,在所述栅开口内形成金属栅极。上述的方案,可以提高所形成的半导体结构的性能。(The invention provides a method for forming a semiconductor structure, which comprises the following steps: providing a substrate; forming a pseudo gate structure and a bottom dielectric layer covering the side wall of the pseudo gate structure on the substrate; etching to remove the pseudo gate structure and forming a gate opening in the bottom dielectric layer; forming a high-k gate dielectric layer on the inner wall of the gate opening; after the high-k gate dielectric layer is formed, performing a remote plasma processing process on the high-k gate dielectric layer; and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate in the gate opening. The scheme can improve the performance of the formed semiconductor structure.)

1. A method of forming a semiconductor device, comprising:

providing a substrate;

forming a pseudo gate structure and a bottom dielectric layer covering the side wall of the pseudo gate structure on the substrate;

etching to remove the pseudo gate structure so as to form a gate opening in the bottom dielectric layer;

forming a high-k gate dielectric layer on the inner wall of the gate opening;

performing a remote plasma treatment process on the high-k gate dielectric layer;

and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate in the gate opening.

2. The method of claim 1, wherein the gas used in the remote plasma treatment process comprises NF₃And H₂。

3. The method of claim 1, further comprising, before or after performing the remote plasma treatment process on the high-k gate dielectric layer:

and performing a pulsed plasma treatment process on the high-k gate dielectric layer.

4. The method of claim 3, wherein the gas used in the pulsed plasma process comprises SF₆。

5. The method for forming the semiconductor device according to claim 1, wherein the high-k gate dielectric layer comprises a first sub-gate dielectric layer and a second sub-gate dielectric layer located above the first sub-gate dielectric layer;

the step of forming the high-k gate dielectric layer comprises the following steps: forming the first sub-gate dielectric layer on the side wall and the bottom of the gate opening; and forming the second sub-gate dielectric layer on the first sub-gate dielectric layer.

6. The method for forming the semiconductor device according to claim 5, wherein the first sub-gate dielectric layer and the second sub-gate dielectric layer are made of HfO₂The thicknesses of the first sub-gate dielectric layer and the second sub-gate dielectric layer are respectively 1 nm-2 nm.

7. The method of claim 1, wherein after forming the dummy gate structure, further comprising: forming a side wall on the side wall of the pseudo gate structure; and after the bottom dielectric layer is formed, the bottom dielectric layer covers the side wall of the side wall.

8. The method of claim 1, further comprising, prior to forming the high-k gate dielectric layer: forming an interface layer in the gate opening; and the high-k gate dielectric layer is positioned on the interface layer.

9. The method of claim 1, further comprising, before forming a metal gate in the gate opening;

forming a barrier layer on the high-k gate dielectric layer; and forming the metal gate in the gate opening after forming the barrier layer.

10. The method according to claim 9, wherein a process of forming the barrier is a physical vapor deposition process.

11. The method according to claim 9, wherein a material of the barrier layer comprises TiN.

12. The method of claim 1, wherein the process of forming the metal gate is a physical vapor deposition process.

13. The method according to claim 1, wherein a material of the metal gate includes W or Al.

14. The method of claim 1, wherein the base comprises a substrate and a fin on the substrate; the dummy gate structure crosses the fin portion;

and after the pseudo gate structure is removed, the high-k gate dielectric layer crosses the fin part.

15. The method of claim 14, wherein the fin material comprises Si or SiGe.

Technical Field

The present invention relates to the field of semiconductor integrated circuits, and more particularly, to a method for forming a semiconductor device.

Background

With the development of semiconductor technology, the conventional planar MOS transistor has a weak ability to control channel current, resulting in a serious leakage current. Fin field effect transistors (Fin FETs) are an emerging multi-gate device that replaces planar MOS transistors for greatly improved circuitry and reduced leakage current.

With the reduction of the channel length, SiO is used for inhibiting the short channel effect and improving the device performance₂The thickness of the gate dielectric layer (referred to as the gate dielectric equivalent oxide thickness, EOT) needs to be reduced accordingly. With the development of integrated circuit technology, SiO₂The thickness (EOT) of the gate dielectric is also decreasing. For EOT<1nm of SiO₂The gate dielectric layer, due to the significant direct tunneling effect, cannot meet the technical requirements for unacceptably high leakage current and high power consumption. Subsequently, the high-k gate dielectric layer is adopted to replace the traditional SiO₂The gate dielectric material can significantly reduce the gate leakage current.

However, the performance of the semiconductor structure formed by the prior art is poor.

Disclosure of Invention

The invention provides a method for forming a semiconductor device, which is used for improving the performance of a formed semiconductor structure.

In order to solve the above problems, the present invention provides a method of forming a semiconductor device, the method comprising:

providing a substrate;

forming a dummy gate structure on the substrate;

forming a bottom dielectric layer covering the substrate, wherein the top surface of the bottom dielectric layer is flush with the top surface of the dummy gate structure;

etching to remove the pseudo gate structure and forming a gate opening in the bottom dielectric layer;

forming a high-k gate dielectric layer on the inner wall of the gate opening;

performing a remote plasma treatment process on the high-k gate dielectric layer;

and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate in the gate opening.

Optionally, the gas used for the remote plasma treatment process comprises NF₃And H₂。

Optionally, before or after performing a remote plasma processing process on the high-k gate dielectric layer, the method further includes:

and performing a pulsed plasma treatment process on the high-k gate dielectric layer.

Optionally, the gas used for the pulsed plasma processing process comprises SF₆。

Optionally, the high-k gate dielectric layer includes a first sub-gate dielectric layer and a second sub-gate dielectric layer located above the first sub-gate dielectric layer;

the step of forming the high-k gate dielectric layer comprises the following steps: forming the first sub-gate dielectric layer in the gate opening; and forming the second sub-gate dielectric layer on the first sub-gate dielectric layer.

Optionally, the first sub-gate dielectric layer and the second sub-gate dielectric layer are both made of HfO₂The thicknesses of the first sub-gate dielectric layer and the second sub-gate dielectric layer are respectively 1 nm-2 nm.

Optionally, after forming the dummy gate structure, the method further includes: forming a side wall on the side wall of the pseudo gate structure; and after the bottom dielectric layer is formed, the bottom dielectric layer covers the side wall of the side wall.

Optionally, before forming the high-k gate dielectric layer, the method further includes: forming an interface layer in the gate opening; and the high-k gate dielectric layer is positioned on the interface layer.

Optionally, before forming the metal gate in the gate opening, further comprising;

forming the barrier layer on the high-k gate dielectric layer; and forming the metal gate in the gate opening after forming the barrier layer.

Optionally, the process of forming the barrier is a physical vapor deposition process.

Optionally, the material of the barrier layer comprises TiN.

Optionally, the process of forming the metal gate is a physical vapor deposition process.

Optionally, the material of the metal gate comprises W or Al.

Optionally, the base includes a substrate and a fin portion on the substrate; the dummy gate structure crosses the fin portion;

and after the pseudo gate structure is removed, the high-k gate dielectric layer crosses the fin part.

Optionally, the material of the fin comprises Si or SiGe.

Correspondingly, an embodiment of the present invention further provides a semiconductor structure, where the semiconductor structure includes:

a substrate;

a bottom dielectric layer on the substrate; the bottom dielectric layer is provided with a corresponding gate opening;

a high-k gate dielectric layer located within the gate opening;

and the metal gate is positioned on the high-k gate dielectric layer.

Optionally, the semiconductor structure further comprises: and the side wall is positioned on the side wall of the gate opening.

Optionally, the semiconductor structure further comprises: and the interface layer is positioned in the gate opening and positioned below the high-k gate dielectric layer.

Optionally, the semiconductor structure further comprises: and the barrier layer is positioned between the high-k gate dielectric layer and the metal gate.

Optionally, the base of the semiconductor structure includes a substrate and a fin portion on the substrate; the high-k gate dielectric layer crosses the fin portion.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the scheme, the substrate is provided; forming a dummy gate structure on the substrate; forming a bottom dielectric layer covering the substrate; etching to remove the pseudo gate structure and forming a gate opening in the bottom dielectric layer; forming a high-k gate dielectric layer in the gate opening; after the high-k gate dielectric layer is formed, performing a remote plasma processing process on the high-k gate dielectric layer; and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate in the gate opening. After the high-k gate dielectric layer is formed, a remote plasma processing technology is performed on the high-k gate dielectric layer to perform surface passivation processing on the high-k gate dielectric layer, so that oxygen vacancies and interface traps existing on the surface of the high-k gate dielectric layer can be removed, the defect charge density is reduced, the low-frequency noise can be obviously reduced, and the performance of the formed semiconductor structure is improved.

Drawings

Fig. 1 is a flow chart illustrating a method for forming a semiconductor structure according to an embodiment of the invention.

Fig. 2 to 13 are schematic intermediate structures formed by the steps of the method for forming a semiconductor structure according to the embodiment of the present invention.

Detailed Description

With the development of integrated circuit technology, SiO₂The thickness of the gate dielectric layer is also continuously reduced. For SiO with the thickness of equivalent oxide layer (EOT) of gate dielectric layer less than 1nm₂The gate dielectric layer, due to the significant direct tunneling effect, cannot meet the technical requirements for unacceptably high leakage current and high power consumption. Subsequently, the high-k gate dielectric layer is adopted to replace the traditional SiO₂Gate dielectric material to significantly reduce gate leakage current.

However, the surface of the high-k gate dielectric layer formed by the existing method for forming the high-k gate dielectric layer has oxygen vacancies and interface traps, and the defect charge density is high, so that the formed semiconductor structure has serious low-frequency noise.

The method for forming the semiconductor device in the embodiment of the invention comprises the following steps: providing a substrate; forming a pseudo gate structure and a bottom dielectric layer covering the side wall of the pseudo gate structure on the substrate; etching to remove the pseudo gate structure so as to form a gate opening in the bottom dielectric layer; forming a high-k gate dielectric layer on the inner wall of the gate opening; after the high-k gate dielectric layer is formed, performing a remote plasma processing process on the high-k gate dielectric layer; and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate structure in the gate opening.

According to the method for forming the semiconductor device, after the high-k gate dielectric layer is formed, a remote plasma processing technology is performed on the high-k gate dielectric layer to perform surface passivation on the high-k gate dielectric layer, so that oxygen vacancies and interface traps existing on the surface of the high-k gate dielectric layer can be removed, the defect charge density can be reduced, the low-frequency noise can be obviously reduced, and the performance of the formed semiconductor structure can be improved.

Fig. 1 shows a flow chart of a method of forming a semiconductor structure in an embodiment of the invention. Referring to fig. 1, the method for forming the semiconductor structure may include:

step S11: providing a substrate;

step S12: forming a pseudo gate structure and a bottom dielectric layer covering the side wall of the pseudo gate structure on the substrate;

step S13: etching to remove the pseudo gate structure and forming a gate opening in the bottom dielectric layer;

step S15: forming a high-k gate dielectric layer on the inner wall of the gate opening;

step S16: performing a remote plasma treatment process on the high-k gate dielectric layer;

step S17: and after the high-k gate dielectric layer is subjected to a remote plasma process, forming a metal gate in the gate opening.

A method of forming a semiconductor device in an embodiment of the present invention will be described in further detail below with reference to fig. 2 to 13.

The semiconductor device may be any suitable device known to those skilled in the art, and the technical solution of the present invention is mainly explained and illustrated in the present embodiment by taking a case that the semiconductor device is a fin field effect transistor (FinFET) device as an example.

Referring to fig. 2, a substrate is provided.

In this embodiment, the semiconductor device is a FinFET device. The base includes a substrate 100 and a fin 110 on the substrate 100. In other embodiments, the semiconductor device is a planar MOS transistor and, correspondingly, the base is a planar substrate.

In particular implementations, the substrate 100 provides a process platform for subsequent fin field effect transistor formation. The FinFET may be one of an N-type FinFET or a P-type FinFET.

In this embodiment, the substrate 100 is a silicon germanium substrate. In other implementations, the substrate 100 may be germanium, silicon carbide, gallium arsenide, or indium gallium arsenide, and the substrate 100 may also be a silicon substrate on an insulating substrate or a germanium substrate on an insulator. The material of the substrate 100 may be a material suitable for process requirements or integration.

In this embodiment, the material of the fin 110 is the same as the material of the substrate 100, i.e., silicon germanium. In other embodiments, the material of the fin may also be silicon.

In a specific implementation, the steps of forming the substrate 100 and the fin 110 may include: providing an initial substrate; forming a fin mask layer on the initial substrate; and etching the initial substrate with a part of thickness by using the fin part mask layer as a mask through a dry etching process to form the substrate 100 and the discrete fin parts 110 positioned on the substrate 100.

In this embodiment, after the substrate 100 and the fin 110 are formed, the fin mask layer on the top of the fin 110 is retained. The fin mask layer is made of silicon nitride, and when a planarization process is performed subsequently, the top surface of the fin mask layer is used for defining a stop position of the planarization process and protecting the top of the fin 110. In other embodiments, after the substrate 100 and the fin 110 are formed, the fin mask layer on the top of the fin 110 is not retained, and the fin mask layer on the top of the fin 110 is removed.

Referring to fig. 3, after forming the substrate 100 and the fin 110, an isolation structure 120 is formed on the substrate 100, and a top surface of the isolation structure 120 is lower than a top surface of the fin 110.

The isolation structure 120 is used to isolate adjacent semiconductor devices.

In this embodiment, the isolation structure is made of silicon oxide. In other embodiments, the material of the isolation structure may also be other insulating materials such as silicon nitride or silicon oxynitride.

Referring to fig. 4 and 5, a dummy gate structure 130 is formed on the substrate 100 across the fin 110. Fig. 5 is a schematic sectional view taken along the cutting line a-a of fig. 4.

The dummy gate structure 130 covers a portion of the top surface and a portion of the sidewall surface of the fin 110.

The dummy gate structure 130 is used to occupy a spatial location for a subsequently formed metal gate structure.

In this embodiment, the dummy gate structure includes a dummy gate dielectric layer and a dummy gate electrode layer on the dummy gate dielectric layer. In this embodiment, the dummy gate dielectric layer is made of silicon dioxide, and the dummy gate electrode layer is made of polysilicon.

As shown in fig. 6, fig. 6 is a schematic view based on fig. 5, and after forming the dummy gate structure 130, a sidewall spacer 140 is formed on a sidewall of the dummy gate structure 130.

When a fin mask layer is disposed on the dummy gate structure 130, the sidewall 140 is also formed on the sidewall of the fin mask layer.

In this embodiment, the sidewall spacers 140 are made of silicon nitride. In other embodiments, the material of the sidewall spacers 140 can also be an insulating material such as silicon nitride, silicon oxide, or silicon oxynitride.

The process for forming the side wall comprises a chemical vapor deposition, physical vapor deposition or atomic layer deposition process.

As shown in fig. 7, after the sidewall spacers 140 are formed, source and drain regions 150 are formed in the substrate on both sides of the dummy gate structure 130 and the sidewall spacers 140. In the embodiment of the present invention, the source drain regions 150 are formed in the dummy gate structures 130 and the fin portions 110 on both sides of the sidewall 140.

The method for forming the source and drain regions 150 includes: and etching the dummy gate structure 130 and part of the fin 110 on two sides of the sidewall 140 to form a groove in the fin 110, and selectively epitaxially growing the source drain region 150 in the formed groove.

For a PMOS or P-type fin field effect transistor, the source drain region 150 is made of SiGe doped with conductive ions, and the conductive type of the conductive ions is P-type; for an NMOS or N-type finfet, the source drain region 150 material may comprise SiC doped with conductive ions of N-type conductivity or SiP doped with conductive ions.

As shown in fig. 8, a bottom dielectric layer 160 is formed on the substrate, and a top surface of the bottom dielectric layer 160 is flush with a top surface of the dummy gate structure 130.

In this embodiment, the bottom dielectric layer 160 is made of silicon oxide.

The step of forming the bottom dielectric layer comprises the following steps: forming a bottom dielectric material layer on the substrate covering the sidewalls and the top of the dummy gate structure 130; and etching the bottom dielectric material layer back until the top surface of the pseudo gate structure is exposed to form the bottom dielectric layer.

In this embodiment, when the sidewall of the dummy gate structure 130 is formed with the sidewall spacer 140, the bottom dielectric material layer further covers the top and the sidewall of the sidewall spacer 140, and the bottom dielectric layer further covers the sidewall of the sidewall spacer 140.

In this embodiment, before forming the bottom dielectric layer 160, a step of forming a contact hole etching stop layer (not shown) on the substrate is further included. After forming a contact etch stop layer on the substrate, the bottom dielectric layer 160 is formed on the etch stop layer.

Referring to fig. 9, after forming the bottom dielectric layer 160, the dummy gate structure 130 is removed, and a gate opening 135 is formed in the bottom dielectric layer 160.

In this embodiment, the dummy gate structure 130 is removed by etching using a dry etching process. In other embodiments, the dummy gate structure can be removed by etching using a wet etching process.

Referring to fig. 10, an interfacial layer 170 is formed on the fin surface at the bottom of the gate opening 135; a high-k gate dielectric layer 180 is formed on the sidewall and bottom of the gate opening 135, and the high-k gate dielectric layer 180 is located on the interfacial layer 170.

The interfacial layer 170 is used to improve the interfacial characteristics between the fin and the subsequently formed high-k gate dielectric layer 180.

The interfacial layer 170 is located in the gate opening 135 and covers the top and sidewalls of the fin 110.

In this embodiment, the material of the interfacial layer 170 is silicon dioxide.

The process of forming the interfacial layer includes an oxidation process.

The high-k gate dielectric layer is made of a high-k dielectric material. Wherein the value of the relative dielectric constant k of the high-k dielectric material is more than 3.9. In this embodiment, the material of the high-k gate dielectric layer 180 is hafnium oxide (HfO)₂)。

In this embodiment, the high-k gate dielectric layer 180 includes a first sub-gate dielectric layer and a second sub-gate dielectric layer, the first sub-gate dielectric layer is located on the sidewall and the bottom of the gate opening 130, and the second sub-gate dielectric layer is located on the sidewall and the bottom of the gate opening 130 and on the first sub-gate dielectric layer.

The step of forming the high-k gate dielectric layer comprises the following steps: forming the first sub-gate dielectric layer on the interface layer on the side wall and the bottom of the gate opening 130; and forming a second sub-gate dielectric layer on the first sub-gate dielectric layer.

Referring to fig. 11, after the high-k gate dielectric layer 180 is formed, a remote plasma treatment process is performed on the high-k gate dielectric layer 180.

In this embodiment, when performing a remote plasma processing process on the high-k gate dielectric layer 180, a mask layer 165 covering the bottom dielectric layer 160 and the sidewall layer 140 is first formed, and the remote plasma processing process is performed on the high-k gate dielectric layer 180 in the gate opening 135 by using the mask layer 165 as a mask.

In this embodiment, the processing gas used in the remote plasma processing process is NF₃And H₂The process chamber temperature is 500 to 650 degrees celsius.

In the remote plasma treatment process, the treatment gas is NF₃The F ions in the dielectric layer can be used for passivating the surface of the formed high-k gate dielectric layer so as to eliminate oxygen vacancies (oxygen vacancies) and interface traps (interface traps). In particular, NF₃The F ions in the dielectric layer can be combined with the metal ions in the high-k gate dielectric layer to form a high-stability Hf-F bond, so that the density of interface defect charges can be reduced.

Meanwhile, the remote plasma processing technology is adopted, and the temperature of the processing chamber is controlled to be 500-650 ℃, so that the processing gas NF₃The N ions in (a) may penetrate into the high-k gate dielectric layer 180 but not into the interfacial layer 170 below the high-k gate dielectric layer 180. When N ions only penetrate into the high-k gate dielectric layer 180, the defect charge density (Dit) on the surface of the high-k gate dielectric layer can be significantly reduced, and the mobility of electrons can be improved.

In this embodiment, before the remote plasma treatment process, a step of performing a pulsed plasma treatment process on the high-k gate dielectric layer 180 is further included.

In this embodiment, the processing gas used in the pulsed plasma processing process is SF₆。

In the pulsed plasma treatment process, a treatment gas SF is used₆The oxygen vacancies and defect charges present in the deeper regions can be controlled, i.e. by means of the process gas SF₆The F and S ions eliminate dangling bonds present in the SiGe fin portion to reduce the number of oxygen vacancies and defect charges present in the deeper region.

Referring to fig. 12, after a remote plasma treatment process is performed on the high-k gate dielectric layer 180, a barrier layer 190 is formed on the high-k gate dielectric layer 180.

The barrier layer 190 is used to prevent metal atoms in the subsequently formed metal gate from diffusing into the dielectric layer, thereby avoiding causing short circuit. Meanwhile, the barrier layer can also improve the adhesion between the subsequent metal gate structure and the dielectric layer.

In this embodiment, the material of the barrier layer includes titanium nitride (TiN).

In this embodiment, the barrier layer 190 is formed using a Physical Vapor Deposition (PVD) process. The barrier layer 190 is formed by a Physical Vapor Deposition (PVD) process, which can inhibit and remove the formation of a germanium oxide (GeO) layer with a low dielectric constant, a poor thermal stability and a high defect charge density on the surface of the SiGe fin, thereby avoiding Fermi-level Pinning (Fermi-level Pinning).

Referring to fig. 13, after forming the barrier layer 190, a metal material is filled in the gate opening to form a metal gate 200.

In the embodiment of the present invention, the material of the metal gate 200 is tungsten (W). In other embodiments, the material of the metal gate can also be aluminum (Al) or copper (Cu), etc.

The step of forming the metal gate 200 includes: forming a metal material layer which covers the bottom dielectric layer and the side wall and fills the gate opening; the top surface of the metal material layer is higher than the top surface of the bottom dielectric layer; and etching back the metal material layer until the top surface of the bottom dielectric layer is exposed to form a metal grid electrode filling the grid opening.

In an embodiment of the present invention, a Physical Vapor Deposition (PVD) process is used to form the metallic material layer. Similar to the formation of the barrier layer 190 by a Physical Vapor Deposition (PVD) process, the formation of the metal material layer by the PVD process can further remove germanium oxide (GeO) with a low dielectric constant, a low thermal stability and a high defect charge density_X) Layer, so that Fermi-level Pinning (Fermi-level Pinning) can be eliminated.

By adopting the scheme in the embodiment of the invention, as the remote plasma processing technology is executed on the high-k gate dielectric layer after the high-k gate dielectric layer is formed, the surface passivation treatment can be carried out on the high-k gate dielectric layer, the defect charge density is reduced, the low-frequency noise can be obviously reduced, and the performance of the formed semiconductor structure is improved.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.