Methods to improve the performance stability of metal gate devices

Abstract

This application provides a method for improving the performance stability of a metal gate device, comprising: step one, providing a substrate, forming an interlayer dielectric layer on the substrate, and forming trenches in the interlayer dielectric layer; step two, forming a first work function metal layer in the trenches; step three, forming a second work function metal layer in the trenches located in the NMOS region of the substrate; step four, forming a titanium nitride barrier layer covering the second work function metal layer; step five, hydrogen treating the titanium nitride barrier layer to reduce the chlorine content of the titanium nitride barrier layer; and step six, forming a metal gate in the trenches. According to this application, the chlorine content of titanium nitride in the metal gate device can be significantly reduced, thereby significantly improving the performance stability of the metal gate device.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and specifically to a method for improving the performance stability of metal gate devices. Background Technology

[0002] The barrier layer material in the gate structure of metal gate devices is typically titanium nitride (TiN). Since atomic layer deposition of TiN involves the reaction of titanium tetrachloride (TiCl4) with NH3, the resulting metal film contains chlorine (Cl). The presence of Cl has a significant negative impact on the stability of metal gate devices. After subsequent high-temperature processes, such as… Figure 1 As shown, Cl in TiN will volatilize to the bottom of the contact hole (CT) and react with Ti to form a void. This defect will seriously affect the conductivity of the contact hole.

[0003] In addition, such as Figure 1 As shown, Cl element will block the diffusion of Al in TiAl layer. For NMOS, Al diffusion is an important factor in regulating threshold voltage (Vt). Excessive Cl content will seriously affect the device performance of NMOS. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a method for improving the performance stability of metal gate devices, in order to solve the problem that the poor performance stability of metal gate devices is caused by excessive Cl content in the TiN layer in the prior art.

[0005] To achieve the above and other related objectives, this application provides a method for improving the performance stability of metal gate devices, comprising: Step 1: Provide a substrate, and form an interlayer dielectric layer on the substrate, with trenches formed in the interlayer dielectric layer; Step two: Form the first work function metal layer within the trench; Step 3: Form a second work function metal layer in the trench located in the NMOS region of the substrate; Step four: Form a titanium nitride barrier layer covering the second work function metal layer; Step 5: Perform hydrogen treatment on the titanium nitride barrier layer to reduce its chlorine content. Step six: Form a metal gate within the trench.

[0006] Preferably, the hydrogen treatment is an immersion treatment performed in a high-temperature environment with hydrogen gas, with a temperature range of 350°C to 450°C.

[0007] Preferably, the hydrogen treatment is performed by removing chlorine contained in the titanium nitride barrier layer through hydrogen plasma.

[0008] Preferably, before forming the first work function metal layer, the method further includes the step of sequentially forming a high dielectric constant dielectric layer and a capping layer on the sidewalls and bottom of the trench.

[0009] Preferably, the material of the coating layer includes titanium nitride.

[0010] Preferably, a deposition process is used to form the first work function metal layer.

[0011] Preferably, the material of the first work function metal layer includes titanium nitride.

[0012] Preferably, in step three, a second work function metal layer is first formed in the trench by a deposition process, and then the second work function metal layer located in the trench of the substrate PMOS region is removed by an etching process.

[0013] Preferably, the deposition process for forming the second work function metal layer is physical magnetron sputtering.

[0014] Preferably, the material of the second work function metal layer includes titanium aluminum.

[0015] As described above, the method for improving the performance stability of metal gate devices provided in this application has the following beneficial effects: it can significantly reduce the Cl content of titanium nitride in metal gate devices, thereby significantly improving the performance stability of metal gate devices. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 The diagram shows a cross-sectional structure of a device where Cl in the TiN layer causes contact hole voids and affects the diffusion of Al in the TiAl layer. Figure 2 The flowchart shown is a method for improving the performance stability of metal gate devices provided in an embodiment of this application. Figure 3 The image shows a comparison of how this application significantly reduces the Cl content in the TiN layer compared to existing technologies. Detailed Implementation

[0018] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this invention.

[0019] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0023] Please see Figure 2 The flowchart illustrates a method for improving the performance stability of metal gate devices provided in an embodiment of this application.

[0024] like Figure 2 As shown, the method for improving the performance stability of metal gate devices includes the following steps: Step 1: Provide a substrate, and form an interlayer dielectric layer on the substrate, with trenches formed in the interlayer dielectric layer; Step two: Form the first work function metal layer within the trench; Step 3: Form a second work function metal layer in the trench located in the NMOS region of the substrate; Step four: Form a titanium nitride barrier layer covering the second work function metal layer; Step 5: Perform hydrogen treatment on the titanium nitride barrier layer to reduce its chlorine content. Step six: Form a metal gate within the trench.

[0025] In step one, a substrate is provided. Optionally, the substrate may be a silicon substrate, a germanium substrate, or a silicon-on-insulator substrate, etc.; or the substrate material may also include other materials, such as gallium arsenide or other III-V compounds. Those skilled in the art can select the substrate material according to the type of device structure formed on the substrate, therefore the type of substrate should not limit the scope of protection of this invention.

[0026] Optionally, the material of the interlayer dielectric layer may include, but is not limited to: silicon nitride (Si3N4), silicon oxide (SiO2), fluorinated SiO2 (FSG), hydrogenated carbon silicon oxide (SiCOH), porous SiCOH, borosilicate glass (BPSG), silsesquioxane, carbon (C) doped oxides (i.e., organosilicones) including silicon (Si), carbon (C), oxygen (O) and / or hydrogen (H) atoms, thermosetting polyarylene ethers, or other materials with low dielectric constants (<3.9).

[0027] For example, an interlayer dielectric layer is formed using a chemical vapor deposition process.

[0028] For example, the step of forming a trench in the interlayer dielectric layer includes: forming a photoresist layer on the interlayer dielectric layer by a coating process; exposing and developing the photoresist layer by a photolithography process to form a photoresist layer with a dummy gate pattern; using the photoresist layer with the dummy gate pattern as a mask, etching the exposed dummy gate by a plasma etching process to form a trench in the interlayer dielectric layer; and removing the photoresist layer with the dummy gate pattern by an ashing process.

[0029] In step two, before forming the first work function metal layer, a high dielectric constant (high k) dielectric layer and a capping layer are sequentially formed on the sidewalls and bottom of the trench. For example, the high k dielectric layer may be made of hafnium oxide (HfO2), aluminum oxide (Al2O3), hafnium silicate (HfSiOx), zirconium dioxide (ZrO2), or hafnium zirconium oxide (HfZrOx), and the capping layer may be made of titanium nitride (TiN).

[0030] For example, a first work function metal layer is formed using a deposition process. This first work function metal layer serves as the work function metal layer of the PMOS metal gate device, and its material includes titanium nitride.

[0031] This deposition process can be carried out in a high-temperature environment, which can increase the molecular kinetic energy characteristics, enabling the deposition process to achieve higher step coverage and uniformity, thereby improving the electrical properties and yield of the formed first work function metal layer.

[0032] In step three, a second work function metal layer is first formed in the trench through a deposition process, and then the second work function metal layer located in the trench of the substrate PMOS region is removed through an etching process.

[0033] For example, the deposition process is a physical magnetron sputtering process. The second work function metal layer serves as the work function metal layer of the NMOS metal gate device, and its material includes titanium aluminum (TiAl).

[0034] In step four, an atomic layer deposition process is used to form a titanium nitride barrier layer covering the second work function metal layer, and the titanium nitride barrier layer is formed by the reaction of TiCl4 and NH3.

[0035] In step five, the hydrogen treatment can be performed by immersion in a high-temperature environment with hydrogen gas, with a temperature range of 350°C to 450°C. Alternatively, the hydrogen treatment can be performed using hydrogen plasma to remove chlorine from the titanium nitride barrier layer.

[0036] In step six, for example, the step of forming a metal gate includes: depositing a metal gate material layer on a substrate using a physical vapor deposition process, a chemical vapor deposition process, or a metal sputtering deposition process to fill the trench; and etching back the metal gate material layer to remove the metal gate material layer outside the trench region, for example, the back etching is plasma etching.

[0037] For example, the material of the metal gate includes tungsten.

[0038] like Figure 3 As shown, compared with the prior art, after implementing the method for improving the performance stability of metal gate devices provided in this application embodiment, the Cl content of titanium nitride in the metal gate device decreases by 37%, which can significantly improve the performance stability of the metal gate device. Here, titanium nitride can be a titanium nitride barrier layer in an NMOS metal gate device, a work function metal layer in a PMOS metal gate device, or a capping layer in a metal gate device.

[0039] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0040] In summary, the method for improving the performance stability of metal gate devices provided in this application can significantly reduce the Cl content of titanium nitride within the metal gate device, thereby significantly improving the performance stability of the metal gate device. Therefore, this application effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0041] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this application.

Claims

1. A method for improving the performance stability of metal gate devices, characterized in that, The method includes: Step 1: Provide a substrate, and form an interlayer dielectric layer on the substrate, wherein trenches are formed in the interlayer dielectric layer; Step 2: Form a first work function metal layer within the trench; Step 3: Form a second work function metal layer in the trench located in the NMOS region of the substrate; Step four: Form a titanium nitride barrier layer covering the second work function metal layer; Step 5: Perform hydrogen treatment on the titanium nitride barrier layer to reduce the chlorine content of the titanium nitride barrier layer; Step six: Form a metal gate within the trench.

2. The method according to claim 1, characterized in that, The hydrogen treatment is an immersion treatment carried out in a high-temperature environment with hydrogen gas, with a temperature range of 350℃-450℃.

3. The method according to claim 1, characterized in that, The hydrogen treatment involves removing chlorine from the titanium nitride barrier layer using hydrogen plasma.

4. The method according to claim 1, characterized in that, Before forming the first work function metal layer, the method further includes the step of sequentially forming a high dielectric constant dielectric layer and a capping layer on the sidewalls and bottom of the trench.

5. The method according to claim 4, characterized in that, The material of the coating layer includes titanium nitride.

6. The method according to claim 1, characterized in that, The first work function metal layer is formed using a deposition process.

7. The method according to claim 1 or 6, characterized in that, The material of the first work function metal layer includes titanium nitride.

8. The method according to claim 1, characterized in that, In step three, the second work function metal layer is first formed in the trench by a deposition process, and then the second work function metal layer located in the trench of the PMOS region of the substrate is removed by an etching process.

9. The method according to claim 8, characterized in that, The deposition process for forming the second work function metal layer is physical magnetron sputtering.

10. The method according to claim 1 or 8, characterized in that, The materials used to form the second work function metal layer include titanium and aluminum.

Images