阅读说明：本技术 半导体结构的形成方法 (Method for forming semiconductor structure ) 是由 张海洋 涂武涛 陈建 于 2020-05-22 设计创作，主要内容包括：本发明实施例提供一种半导体结构的形成方法,所述形成方法包括：提供衬底；在所述衬底上形成栅功能结构,所述栅功能结构包括：一层栅功能层或多层栅功能层；形成所述栅功能层的步骤包括：在衬底上形成功能材料层；对所述功能材料层表面进行解复合处理,减少所述栅功能材料层表面的陷阱缺陷俘获的带电离子；所述解复合处理之后,对所述栅功能材料层表面进行钝化处理,减少所述栅功能材料层表面的陷阱缺陷；在所述栅功能结构上形成栅极。所述解复合处理和钝化处理能够减少所形成半导体结构的低频噪声。(The embodiment of the invention provides a forming method of a semiconductor structure, which comprises the following steps: providing a substrate; forming a gate functional structure on the substrate, the gate functional structure comprising: a gate function layer or a plurality of gate function layers; the step of forming the gate function layer includes: forming a functional material layer on a substrate; performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the gate functional material layer; after the de-compounding treatment, passivating the surface of the gate functional material layer to reduce the trap defects on the surface of the gate functional material layer; and forming a grid electrode on the grid function structure. The de-compounding and passivating processes can reduce low frequency noise of the formed semiconductor structure.)

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

providing a substrate;

forming a gate functional structure on the substrate, the gate functional structure comprising: a gate function layer or a plurality of gate function layers;

the step of forming the gate function layer includes: forming a functional material layer on a substrate; performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the gate functional material layer; after the de-compounding treatment, passivating the surface of the gate functional material layer to reduce the trap defects on the surface of the gate functional material layer;

and forming a grid electrode on the grid function structure.

2. The method of forming a semiconductor structure of claim 1, wherein the step of passivating comprises: and introducing passivation gas to the surface of the gate functional material layer.

3. The method of forming a semiconductor structure of claim 2, wherein the passivation gas comprises: CF (compact flash)₄、(NH₄)₂S, HCl and SF₆One or more of (a).

4. The method of forming a semiconductor structure of claim 1, wherein the step of de-compounding comprises: and introducing plasma gas to the surface of the gate functional material layer, wherein the plasma gas generates deep ultraviolet photons.

5. The method of forming a semiconductor structure of claim 4, wherein the plasma gas comprises: one or more of helium, neon and argon plasma.

6. The method of forming a semiconductor structure of claim 1, further comprising: and after the gate functional structure is formed and before the gate electrode is formed, annealing treatment is carried out on the gate functional structure.

7. The method of forming a semiconductor structure of claim 1, wherein forming the gate functional layer further comprises: and after the passivation treatment, annealing the gate function material layer.

8. The method of claim 1, wherein the reactive gas forming the gate functional material layer comprises a nitrogen-containing precursor, and wherein forming the gate functional material layer comprises: and controlling the technological parameters for forming the gate functional material layer, and reducing dissociation of nitrogen atoms and the atoms of the gate functional material layer.

9. The method of claim 8, wherein controlling process parameters for forming the gate functional material layer comprises: and enabling the process temperature for forming the gate functional material layer to be less than or equal to 650 ℃.

10. The method of claim 1, wherein the gate functional structure comprises a gate functional layer, and the gate functional layer is a gate dielectric layer or a work function layer.

11. The method of forming a semiconductor structure of claim 1, wherein the gate functional structure comprises a multi-layer gate functional layer comprising: the device comprises a gate dielectric layer positioned on a substrate and a work function layer positioned on the gate dielectric layer.

12. The method of forming a semiconductor structure of claim 11, wherein forming the gate functional structure comprises:

forming a gate dielectric material layer on the substrate; sequentially carrying out first de-compositing treatment and first passivating treatment on the gate dielectric material layer to form a gate dielectric layer;

and forming a work function material layer on the gate dielectric layer, and sequentially performing second de-compounding treatment and second passivation treatment on the work function material layer to form a work function layer.

13. The method of claim 10 or 11, wherein the material of the work function layer comprises lanthanum oxide.

14. The method for forming a semiconductor structure according to claim 10 or 11, wherein the material of the gate dielectric layer is a high-k dielectric material.

15. The method for forming a semiconductor structure according to claim 10 or 11, wherein a material of the gate dielectric layer comprises hafnium oxide or erbium oxide.

16. The method of forming a semiconductor structure of claim 10, wherein the gate dielectric layer is a gate oxide layer.

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a forming method of a semiconductor structure.

Background

With the increase of the integration level of semiconductor devices, the critical dimensions of transistors are continuously shrinking. However, with the rapid decrease of the transistor size, the thickness of the gate dielectric layer and the operating voltage cannot be changed correspondingly, so that the difficulty of suppressing the short channel effect is increased, and the channel leakage current of the transistor is increased.

In order to accommodate the shrinking transistor size, high-k metal gate transistors have been developed. The high-k gate function layer can keep the gate capacitance unchanged, and simultaneously increase the physical thickness of the gate dielectric layer, thereby achieving the dual purposes of reducing the gate leakage current and improving the reliability of the device.

However, the existing transistor has serious low-frequency noise, which affects the electrical performance of the transistor.

Disclosure of Invention

The invention solves the problem of providing a method for forming a semiconductor structure, which can reduce low-frequency noise of the formed semiconductor structure.

The technical scheme of the invention provides a method for forming a semiconductor structure, which comprises the following steps: providing a substrate; forming a gate functional structure on the substrate, the gate functional structure comprising: a gate function layer or a plurality of gate function layers; the step of forming the gate function layer includes: forming a functional material layer on a substrate; performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the gate functional material layer; after the de-compounding treatment, passivating the surface of the gate functional material layer to reduce the trap defects on the surface of the gate functional material layer; and forming a grid electrode on the grid function structure.

Optionally, the step of passivating comprises: and introducing passivation gas to the surface of the gate functional material layer.

Optionally, the passivation gas comprises: CF (compact flash)₄、(NH₄)₂S, HCl and SF₆One or more of (a).

Optionally, the step of de-compounding processing includes: and introducing plasma gas to the surface of the gate functional material layer, wherein the plasma gas generates deep ultraviolet photons.

Optionally, the plasma gas comprises: one or more of helium, neon and argon plasma.

Optionally, the method for forming the semiconductor structure further includes: and after the gate functional structure is formed and before the gate electrode is formed, annealing treatment is carried out on the gate functional structure.

Optionally, the step of forming the gate function layer further includes: and after the passivation treatment, annealing the gate function material layer.

Optionally, the reaction gas for forming the gate functional material layer includes a nitrogen-containing precursor, and the step of forming the gate functional material layer includes: and controlling the technological parameters for forming the gate functional material layer, and reducing dissociation of nitrogen atoms and the atoms of the gate functional material layer.

Optionally, the controlling the process parameters for forming the gate functional material layer includes: and enabling the process temperature for forming the gate functional material layer to be less than or equal to 650 ℃.

Optionally, the gate functional structure includes a gate functional layer, and the gate functional layer is a gate dielectric layer or a work function layer.

Optionally, the gate functional structure includes a plurality of gate functional layers, and the plurality of gate functional layers include: the device comprises a gate dielectric layer positioned on a substrate and a work function layer positioned on the gate dielectric layer.

Optionally, the step of forming the gate function layer includes: forming a gate dielectric material layer on the substrate; sequentially carrying out first de-compositing treatment and first passivating treatment on the gate dielectric material layer to form a gate dielectric layer; and forming a work function material layer on the gate dielectric layer, and sequentially performing second de-compounding treatment and second passivation treatment on the work function material layer to form a work function layer.

Optionally, the material of the work function layer comprises lanthanum oxide.

Optionally, the gate dielectric layer is made of a high-k dielectric material.

Optionally, the material of the gate dielectric layer includes hafnium oxide or erbium oxide.

Optionally, the gate dielectric layer is a gate oxide layer.

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

according to the forming method of the semiconductor structure provided by the technical scheme, the recombination of the trap defects and the charged ions on the surface of the gate functional material layer can be eliminated by performing the recombination elimination treatment on the surface of the gate functional material layer, so that the charged ions trapped by the trap defects on the surface of the gate functional material layer are reduced; after the de-compounding treatment, the surface of the gate functional material layer is passivated, so that trap defects on the surface of the gate functional material layer can be combined with atoms of a passivation gas, the trap defects on the surface of the gate functional layer are reduced, the compounding and dissociation of charged ions and the trap defects can be reduced, and further the low-frequency noise can be reduced.

In the alternative, a multi-layer gate function layer is formed by performing de-compounding treatment and passivation treatment on the gate dielectric material layer and the work function material layer, so that low-frequency noise generated by the formed gate dielectric layer and the work function layer can be reduced, and the performance of the formed semiconductor structure can be further improved.

In an alternative, the step of forming the gate function layer includes: the process parameters for forming the gate function material layer are controlled, dissociation of nitrogen atoms and the atoms of the gate function material layer is reduced, and the stability of the nitrogen atoms is improved, so that trap defects generated by dissociation of the nitrogen atoms can be reduced, and further low-frequency noise can be further reduced.

Drawings

Fig. 1 to 9 are schematic structural diagrams corresponding to steps in a method for forming a semiconductor structure according to an embodiment of the present invention;

fig. 10 to 14 are schematic structural diagrams corresponding to steps in another embodiment of a method for forming a semiconductor structure according to the present invention.

Detailed Description

There are a number of problems with semiconductor formation methods, such as: the low frequency noise of the formed semiconductor structure is severe.

Researches show that trap defects such as holes or dangling bonds exist on the surface of a gate dielectric layer of a transistor (particularly the high-k dielectric layer of an oxygen-containing high-k metal gate transistor), so that charged ions (mainly oxygen ions) are easy to compound and decompose with the trap defects on the surface of the gate dielectric layer, the charged ions and the trap defects on the surface of the gate dielectric layer are repeatedly compounded and decomposed to generate low-frequency electric signals, and the performance of the transistor can be seriously influenced by the low-frequency noise signals.

A method of reducing low frequency noise comprising: after the gate dielectric layer is formed, surface passivation is carried out on the gate dielectric layer, and dangling bonds or holes are combined with passivation atoms, so that trap defects on the surface of the gate dielectric layer are reduced, and the interface state of the gate dielectric layer is further reduced.

However, since the surface of the gate dielectric layer is already complexed with a large number of charged ions before the surface passivation process, passivation atoms can only be bound to a portion of the trap defects. After the surface passivation treatment, the surface state of the gate dielectric layer is still high, so that low-frequency noise still exists in the formed transistor.

The technical scheme of the invention provides a method for forming a semiconductor structure, which comprises the following steps: providing a substrate; forming a gate functional structure on the substrate, the gate functional structure comprising: a gate function layer or a plurality of gate function layers; the step of forming the gate function layer includes: forming a functional material layer on a substrate; performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the gate functional material layer; after the de-compounding treatment, passivating the surface of the gate functional material layer to reduce the trap defects on the surface of the gate functional material layer; and forming a grid electrode on the grid function structure.

According to the technical scheme, the recombination of the trap defects and the charged ions on the surface of the gate functional material layer can be eliminated by performing recombination elimination treatment on the surface of the gate functional material layer, so that the charged ions trapped by the trap defects on the surface of the gate functional material layer are reduced; after the de-compounding treatment, the surface of the gate functional material layer is passivated, so that trap defects on the surface of the gate functional material layer can be combined with atoms of a passivation gas, the trap defects on the surface of the gate functional layer are reduced, the compounding and dissociation of charged ions and the trap defects can be reduced, and further the low-frequency noise can be reduced.

Fig. 1 to 9 are schematic structural diagrams corresponding to steps in an embodiment of a method for forming a semiconductor structure of the present invention.

Referring to fig. 1, a substrate 100 is provided.

In this embodiment, the substrate 100 includes: the device comprises a substrate and a fin part positioned on the substrate. In other embodiments, the substrate does not include the fin.

The substrate is a semiconductor substrate such as a silicon substrate, a germanium substrate, a silicon-on-insulator or a germanium-on-insulator.

In this embodiment, the fin portion is made of silicon. In other embodiments, the fin may be germanium or silicon germanium.

The forming method further includes: an isolation structure 110 is formed on the substrate 100, and the isolation structure 110 covers the sidewall of the fin portion.

The isolation structure 110 is made of silicon oxide or silicon oxynitride.

With continued reference to fig. 1, a dummy gate structure (not shown) is formed on the substrate 100; forming source-drain doping layers 130 in the substrate 100 on two sides of the pseudo gate structure; and forming an etching stop layer 120 covering the source-drain doping layer 130 and the pseudo gate structure.

The step of forming the dummy gate structure includes: forming a dummy gate layer on the substrate 100; and patterning the pseudo gate layer to form a pseudo gate structure.

The dummy gate structure crosses the fin and covers part of the side wall and part of the top surface of the fin. The material of the pseudo gate layer is polysilicon, polycrystalline germanium or polycrystalline silicon germanium.

Before forming the source-drain doping layer 130, the method further includes: and forming a side wall (not shown in the figure) on the side wall of the pseudo gate structure.

The source-drain doping layer 130 is made of silicon germanium or carbon silicon.

In this embodiment, the step of forming the source-drain doping layer 130 includes: forming grooves in the substrate 100 on the two sides of the pseudo gate structure and the side walls; and forming an epitaxial layer in the groove, and carrying out in-situ doping on the epitaxial layer in the process of forming the epitaxial layer to form the source-drain doping layer 130.

The etch stop layer 120 is used to reduce the loss of the source-drain doping layer 130 when forming the contact hole. The material of the etch stop layer 120 is silicon oxide, silicon nitride or silicon oxynitride.

Continuing to refer to fig. 1, forming a dielectric layer 121 on the substrate 100, where the dielectric layer 121 covers the sidewall of the sidewall and exposes the top surface of the pseudo gate structure; after the dielectric layer 121 is formed, the dummy gate structure is removed, and an opening 131 is formed in the dielectric layer 121.

The dielectric layer 121 is used to isolate a subsequently formed gate from an external circuit.

The step of forming the dielectric layer 121 includes: forming an initial dielectric layer (not shown) covering the sidewalls and the top of the dummy gate structure; and carrying out planarization treatment on the initial dielectric layer, and removing the initial dielectric layer higher than the top of the pseudo gate structure.

In this embodiment, the planarization process is further used to remove the etch stop layer 120 on the top of the dummy gate structure.

The material of the dielectric layer 121 is different from the material of the etch stop layer 120.

Specifically, the dielectric layer 121 is made of silicon oxide, silicon nitride, or silicon oxynitride.

Subsequently forming a gate functional structure on the substrate 100, the gate functional structure including: a gate function layer or a plurality of gate function layers; the step of forming each gate function layer includes: forming a functional material layer on a substrate; and performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the functional material layer.

In this embodiment, the gate functional structure includes a plurality of gate functional layers, and the plurality of gate functional layers are stacked. The step of forming the gate functional structure comprises: and sequentially forming a plurality of gate function layers on the substrate.

Specifically, in this embodiment, the multi-layer gate functional layer includes: a gate dielectric layer located on the substrate; and a work function layer located on the gate dielectric layer.

The step of forming each gate function layer includes: forming a functional material layer on a substrate; performing de-compounding treatment on the surface of the functional material layer to reduce charged ions trapped by trap defects on the surface of the functional material layer; and after the de-compounding treatment, passivating the surface of the functional material layer to reduce the trap defects on the surface of the functional material layer.

Specifically, when the gate function layer is a gate dielectric layer, the functional material layer forming the gate dielectric layer is a gate dielectric material layer; performing de-compounding treatment on the surface of the functional material layer comprises performing first de-compounding treatment on the gate dielectric material layer; the passivation treatment of the surface of the functional material layer comprises the following steps: and carrying out first passivation treatment on the gate dielectric material layer.

Referring to fig. 2 to 4, schematic structural diagrams of various steps of forming a gate dielectric layer are shown.

In this embodiment, the gate functional layer is an oxide, and includes a metal oxide, a non-metal oxide, or an oxynitride. In other embodiments, the gate functional layer may be a nitride.

Referring to fig. 2, a gate dielectric material layer 140 is formed on the substrate 100.

Specifically, in this embodiment, the gate dielectric material layer 140 is formed at the bottom of the opening 131. The gate dielectric material layer 140 is also located on the sidewall of the opening 131 and on the top of the dielectric layer 121.

The gate dielectric material layer 140 is used to achieve electrical isolation between the subsequent gate and the substrate 100.

In this embodiment, the gate function layer is a gate dielectric material layer 140. Specifically, the gate function layer is made of a high-k dielectric material, and the k value is greater than 3.9, for example: the gate dielectric material layer is made of hafnium oxide. In other embodiments, the material of the gate dielectric material layer may be erbium oxide.

In this embodiment, the process of forming the gate dielectric material layer 140 includes: chemical vapor deposition, atomic layer deposition, or physical vapor deposition processes.

The reaction gases for forming the gate dielectric material layer 140 include a nitrogen-containing gas (e.g., ammonia), oxygen, and a hafnium-containing precursor.

In this embodiment, the gate dielectric material layer 140 is made of oxide.

Because the gate dielectric material layer 140 is made of an oxide, the gas for forming the gate dielectric material layer 140 includes oxygen-containing gas, and a large number of oxygen ions are easily generated in the process of forming the gate dielectric material layer 140, and the oxygen ions are relatively active and are easily compounded and de-compounded with traps on the surface of the gate dielectric material layer 140, so that low-frequency noise is generated. Therefore, the first de-compounding process and the first passivation process are performed on the gate dielectric material layer 140, so that the low-frequency noise of the formed semiconductor structure can be effectively reduced.

In this embodiment, in the process of forming the gate dielectric material layer 140, the process parameters for forming the gate dielectric material layer 140 are controlled to reduce dissociation between nitrogen atoms and atoms of the gate dielectric material layer 140.

The process parameters for forming the gate dielectric material layer 140 are controlled, dissociation of nitrogen atoms from the gate dielectric material layer 140 atoms is reduced, and the stability of the nitrogen atoms is improved, so that trap defects generated by dissociation of the nitrogen atoms can be reduced, and further low-frequency noise can be further reduced.

Specifically, the method for controlling the process parameters for forming the gate dielectric material layer 140 includes: the process temperature for forming the gate dielectric material layer 140 is less than or equal to 650 ℃.

It should be noted that, if the process temperature for forming the gate dielectric material layer 140 is too high, it is not beneficial to improve the stability of nitrogen atoms in the gate dielectric material layer 140; if the temperature of the process for forming the gate dielectric material layer 140 is too low, the forming speed of the gate dielectric material layer 140 is easily reduced. Specifically, the process temperature for forming the gate dielectric material layer 140 is 550 ℃ to 650 ℃.

In other embodiments, the process temperature for forming the gate dielectric material layer may be greater than 650 ℃. Specifically, the temperature for forming the gate dielectric material layer may be 650 ℃ to 800 ℃.

The dielectric property of the gate dielectric material layer 140 is easily affected by too large or too small a thickness of the gate dielectric material layer 140, and if the thickness of the gate dielectric material layer 140 is too small, the interface state of the gate dielectric material layer 140 is easily caused to be high, so that more trap defects are caused on the surface of the gate dielectric material layer 140, and further, the low-frequency noise of the formed semiconductor structure is serious. Specifically, in this embodiment, the thickness of the gate dielectric material layer 140 is 1.9nm to 2.2 nm.

Before forming the gate dielectric material layer 140 on the substrate 100, forming an interfacial layer (not shown) on the substrate 100 is further included.

The gate dielectric material layer 140 is located on the interfacial layer. The interfacial layer is used for improving an interface state between the gate dielectric material layer 140 and the substrate 100, and reducing trap defects in the gate dielectric material layer 140.

The interface layer is made of silicon oxide or silicon oxynitride.

Referring to fig. 3, a first de-compounding process is performed on the surface of the gate dielectric material layer 140 to reduce charged ions trapped by trap defects of the gate dielectric material layer 140.

The first de-compounding process can remove the combination of the trap defects and the charged ions on the surface of the gate dielectric material layer 140, and reduce the charged ions (for example, oxygen ions) trapped by the trap defects on the surface of the gate dielectric material layer 140. In the subsequent process of performing the first passivation treatment on the surface of the gate dielectric material layer 140, the trap defects on the surface of the gate dielectric material layer 140 can be combined with atoms of the passivation gas, so that the trap defects on the surface of the gate dielectric material layer 140 can be reduced, the recombination and dissociation of charged ions and the trap defects can be further reduced, and further, the low-frequency noise can be reduced.

In this embodiment, the first de-compounding process includes a plasma treatment.

The first de-compounding process includes: and introducing plasma gas to the surface of the gate dielectric material layer 140, wherein the plasma gas is used for generating deep ultraviolet photons.

As an example, the first de-compounding process may be performed by a jet type atmospheric pressure plasma processing system. Specifically, the jet-type atmospheric pressure plasma processing system is composed of a plasma generator, a gas pipeline and a plasma gun, wherein the plasma generator generates high-voltage high-frequency energy to generate low-temperature plasma in glow discharge activated and controlled in a nozzle steel pipe, the low-temperature plasma sprays the plasma to the surface of the gate dielectric material layer 140 by means of compressed air, and when the plasma contacts the surface of the gate dielectric material layer 140, a chemical action and a physical action are generated.

The plasma gas includes: one or more of helium, neon, and argon plasma gases. Specifically, the plasma gas may be helium.

Referring to fig. 4, after the first de-compositing process, a first passivation process is performed on the surface of the gate dielectric material layer 140 to reduce trap defects on the surface of the gate dielectric material layer 140, so as to form a gate dielectric layer 141. After the first de-compounding treatment, the surface of the gate dielectric material layer 140 is passivated, so that trap defects on the surface of the gate dielectric material layer 140 can be bonded with atoms of passivation gas, the trap defects on the surface of the gate dielectric material layer 140 can be reduced, recombination and dissociation of charged ions and the trap defects can be reduced, and low-frequency noise can be reduced.

Specifically, the step of the first passivation process includes: and introducing passivation gas to the surface of the gate dielectric material layer 140.

The passivation gas can be combined with the trap (for example, dangling bond) on the surface of the gate dielectric material layer 140 to form a covalent bond with stable chemical properties, so that the passivation gas is not easily recombined with the trap defect, the trap defect on the surface of the gate dielectric material layer 140 can be reduced, the recombination and dissociation of the trap defect and charged ions (for example, oxygen ions) are prevented, and the formation of low-frequency noise is avoided.

The passivation gas comprises CF₄、(NH4)₂S, HCl and SF₆One or more of (a).

In this embodiment, the gate functional structure includes a plurality of gate functional layers, and the gate functional structure further includes: and the work function layer is positioned on the gate dielectric layer 141.

Therefore, after the gate dielectric layer 141 is formed, a work function material layer is formed on the gate dielectric layer 141, and the work function material layer is sequentially subjected to a second de-compounding process and a second passivation process to form a work function layer.

Referring to fig. 5 to 7, schematic structural diagrams of respective steps of forming the work function layer are shown.

Referring to fig. 5, a work function material layer 150 is formed on the gate dielectric layer 141.

The work function material layer 150 is used to adjust a work function between a subsequently formed gate and the substrate 100.

In this embodiment, the work function material layer 150 is made of lanthanum oxide. In other embodiments, the material of the work function material layer is TiAlC, TaAlN, TiAlN, TaCN, or AlN.

The process of forming the work-function material layer 150 includes: a chemical vapor deposition process, a physical vapor deposition process, or an atomic layer deposition process.

The reaction gas for forming the work function material layer 150 on the gate dielectric layer 141 includes a nitrogen-containing precursor, and the step of forming the work function material layer 150 includes: the process parameters for forming the work function material layer 150 are controlled to reduce dissociation of nitrogen atoms from the work function material layer 150 atoms.

The process parameters for forming the work function material layer 150 are controlled, dissociation of nitrogen atoms from the work function material layer 150 atoms is reduced, and the stability of the nitrogen atoms is improved, so that trap defects caused by dissociation of the nitrogen atoms can be reduced, and further low-frequency noise can be reduced.

Specifically, the work function material layer 150 is an oxide, such as lanthanum oxide, and the reaction gas for forming the work function material layer 150 includes a nitrogen-containing precursor and a lanthanum-containing precursor.

Since the material of the work function material layer 150 is an oxide, the gas for forming the work function material layer 150 includes an oxygen-containing gas, and a large amount of oxygen ions are easily generated in the process of forming the work function material layer 150, and the oxygen ions have active properties and are easily combined and de-combined with surface traps of the work function material layer 150, thereby generating low-frequency noise. Therefore, the second de-composition process and the second passivation process are performed on the work function material layer 150, so that the low frequency noise of the formed semiconductor structure can be effectively reduced.

The method of controlling the process parameters for forming the work function material layer 150 includes: the process temperature for forming the work function material layer 150 is less than or equal to 650 ℃.

Specifically, if the process temperature for forming the work function material layer 150 is too high, it is not favorable for improving the stability of nitrogen atoms in the work function material layer 150; if the process temperature for forming the work function material layer 150 is too low, the formation speed is easily reduced. Specifically, the process temperature for forming the work function material layer 150 is 550 ℃ to 650 ℃.

In other embodiments, the process temperature for forming the work function material layer may be greater than 650 ℃. Specifically, the temperature for forming the work function material layer may be 650 to 800 ℃.

Referring to fig. 6, a second de-composition process is performed on the surface of the work function material layer 150 to reduce charged ions trapped by trap defects on the surface of the work function material layer 150.

The second de-compounding process can remove the combination of the trap defects and the charged ions on the surface of the work function material layer 150, and reduce the charged ions trapped by the trap defects on the surface of the work function material layer 150. Subsequently, the second passivation treatment is performed on the surface of the work function material layer 150, so that the trap defects on the surface of the work function material layer 150 can be combined with atoms of the passivation gas, the trap defects on the surface of the work function material layer 150 can be reduced, the recombination and dissociation of charged ions and the trap defects can be reduced, and the low-frequency noise can be correspondingly reduced.

The second de-compounding process includes: and introducing plasma gas to the surface of the work function material layer 150, wherein the plasma gas generates deep ultraviolet photons.

Specifically, the second de-compounding process may be performed by a jet-type atmospheric pressure plasma processing system. The jet-type normal-pressure plasma processing system consists of a plasma generator, a gas pipeline and a plasma gun, wherein the plasma generator generates high-pressure high-frequency energy to generate low-temperature plasma in glow discharge activated and controlled in a nozzle steel pipe, the low-temperature plasma sprays the plasma to the surface of the work function material layer 150 by means of compressed air, and when the plasma is in contact with the surface of the work function material layer 150, a chemical action and a physical action are generated. In this embodiment, the plasma gas generates deep ultraviolet photons, which can pass through the surface of the work function material layer 150 to separate charged ions (e.g., oxygen ions) from the work function material layer 150.

The plasma gas includes: one or more combinations of helium, neon and argon.

Referring to fig. 7, after the second de-compounding process, a second passivation process is performed on the surface of the work function material layer 150 to reduce trap defects on the surface of the work function material layer 150, so as to form a work function layer 151.

After the second de-compounding process, the surface of the work function material layer 150 is passivated for a second time, so that the trap defects on the surface of the work function material layer 150 can be combined with atoms of the passivation gas, the trap defects on the surface of the work function material layer 150 can be reduced, the recombination and dissociation of charged ions and the trap defects can be reduced, and the low-frequency noise can be reduced correspondingly.

The step of the second passivation process includes: and introducing passivation gas to the surface of the work function material layer 150.

The passivation gas can be combined with a trap (e.g., a dangling bond) on the surface of the work function material layer 150 to form a covalent bond with stable chemical properties, so that the passivation gas is not easily recombined with a trap defect, the trap defect on the surface of the work function material layer 150 can be reduced, and the trap defect and charged ions (e.g., oxygen ions) are prevented from being combined and dissociated, so that low-frequency noise is avoided.

In this embodiment, the passivation gas bagComprises a CF₄、(NH₄)₂S, HCl and SF₆One or more combinations thereof.

In this embodiment, the work function layer 151 is made of an oxide, for example, the work function layer 151 is made of lanthanum oxide. In other embodiments, the material of the work function layer is TiAlC, TaAlN, TiAlN, TaCN, or AlN.

In this embodiment, after forming the gate functional structure, the forming method further includes: and annealing the gate functional structure.

In this embodiment, the gate functional structure includes: correspondingly, the annealing process includes: and performing first annealing treatment on the gate dielectric layer 141 and the work function layer 151.

In this embodiment, the atmosphere of the first annealing treatment is one or a combination of ammonia decomposition atmosphere and ammonia combustion atmosphere.

The ammonia decomposition atmosphere is formed by decomposing liquid ammonia under the action of a catalyst after the liquid ammonia is gasified under reduced pressure, and the composition of the ammonia decomposition atmosphere is 75% of H₂And 25% N₂Due to N₂Is a neutral gas, so its properties are substantially the same as those of hydrogen.

The ammonia combustion atmosphere is 75% H of the ammonia separated₂Burning to 96% N₂And 4% of H₂The dew point reaches-60 percent. The method can reduce H₂Thereby enabling to improve safety of annealing.

In other embodiments, the annealing may also be performed under a nitrogen atmosphere or a hydrogen atmosphere.

In this embodiment, the annealing temperature of the first annealing treatment is 500 ℃ to 1000 ℃.

In this embodiment, after the work function layer 151 is formed, the gate dielectric layer 141 and the work function layer 151 are subjected to a first annealing process, so that the process flow can be simplified.

In other embodiments, after the first passivation process and before the work function layer is formed, the forming method further includes: for the gate dielectric layerAnd carrying out second annealing treatment. And the atmosphere of the second annealing treatment is ammonia decomposition atmosphere or ammonia decomposition atmosphere. The ammonia decomposition atmosphere is formed by decomposing liquid ammonia under the action of a catalyst after the liquid ammonia is gasified under reduced pressure, and the composition of the ammonia decomposition atmosphere is 75% of H₂And 25% N₂Due to N₂Is a neutral gas, so its properties are substantially the same as those of hydrogen. The ammonia combustion atmosphere is 75% H of the ammonia separated₂Burning to 96% N₂And 4% of H₂The dew point reaches-60 percent. The method can reduce H₂Thereby enabling to improve safety of annealing. The annealing temperature of the second annealing treatment is 500 ℃ to 1000 ℃. In this way, in the forming process of each gate functional layer, annealing treatment is carried out once after passivation treatment, so that the quality of each gate functional layer can be optimized.

In this embodiment, after forming the work function layer 151, the method further includes: a capping layer (not shown) is formed on the work function layer 151.

The capping layer is used to protect the gate dielectric layer 141 and the work function layer 151 and prevent the gate dielectric layer 141 and the work function layer 151 from being damaged by a subsequent process.

The covering layer is made of titanium nitride, tantalum nitride, titanium oxynitride or tantalum oxynitride.

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

The process gas for forming the capping layer includes: a nitrogen-containing precursor, an oxygen-containing precursor, and a titanium/tantalum-containing precursor.

Referring to fig. 8 and 9, there is shown a schematic structural view of a step of forming a gate electrode on the gate functional structure.

Referring to fig. 8, after the gate functional structure is formed, a gate material layer 160 is formed in the opening 131 and on the dielectric layer 121.

In this embodiment, after the capping layer is formed, the gate material layer 160 is formed. The gate material layer 160 is on the cap layer.

In this embodiment, the gate material layer 160 is made of metal. Specifically, the material of the gate material layer 160 is tungsten.

Referring to fig. 9, the gate material layer 160 on the dielectric layer 121 is removed to form a gate 161.

In this embodiment, the process of removing the gate material layer 160 on the dielectric layer 121 includes a chemical mechanical polishing process.

In this embodiment, in the process of removing the gate material layer 160 on the dielectric layer 121, the work function layer 151 and the gate dielectric layer 141 on the dielectric layer 121 are also removed.

It should be noted that, the embodiments shown in fig. 1 to fig. 9 are used for forming a high-k metal gate (HKMG) transistor, and since there are many traps on the surfaces of the gate dielectric material layer 140 and the work function material layer 150 of the high-k metal gate transistor, and the low-frequency noise is serious, the technical solution of the present invention can effectively reduce the low-frequency noise of the high-k metal gate transistor.

It should be further noted that in the embodiments shown in fig. 1 to 9, the low-frequency noise of the formed semiconductor structure is reduced by performing the first de-compounding process and the first passivation process on the gate dielectric material layer 140, and performing the second de-compounding process and the second passivation process on the work function material layer 150. In other embodiments, the step of forming only the gate dielectric layer may include a de-recombination process and a passivation process, or the step of forming only the work function layer may include a de-recombination process and a passivation process.

It should be further noted that, in the embodiments shown in fig. 1 to 9, the method for forming the semiconductor structure further includes: an interfacial layer and a capping layer are formed. In order to save the process flow, the steps of forming the interface layer and the covering layer do not comprise de-compounding treatment and passivation treatment.

In other embodiments, the interfacial layer and the capping layer may also be a gate functional layer. One or both of the steps of forming the interface layer and the capping layer may include a de-compounding process and a passivation process to reduce low frequency noise problems. The process details of the de-compounding process and the passivation process are the same as those of the first (second) de-compounding process and the first (second) passivation process, and are not described herein again.

Fig. 10 to 14 are schematic structural diagrams of steps in yet another embodiment of a method for forming a semiconductor structure according to the present invention. In this embodiment, the forming method is used for forming a silicon oxide-polysilicon gate transistor.

The same points of this embodiment as those in the embodiments shown in fig. 1 to 9 are not described herein again, and the different points include:

referring to fig. 10, a substrate 200 is provided.

In this embodiment, the substrate 200 is a planar substrate.

With continued reference to fig. 10, a layer of functional material 210 is formed on the substrate 200.

In this embodiment, the functional material layer 210 is used to form a gate dielectric layer. Specifically, in this embodiment, the gate dielectric layer is a gate oxide layer. Thus, the material of the functional material layer 210 is a gate oxide material layer. The functional material layer 210 is made of silicon oxide or silicon oxynitride.

The process gas for forming the functional material layer 210 includes: oxygen gas, ammonia gas, and a silicon source gas. The silicon source gas includes: SiH₄Or SiCl₄。

Since oxygen is contained in the gas forming the functional material layer 210, a large amount of oxygen ions are easily generated during the formation of the functional material layer 210, and the oxygen ions are easily recombined and dissociated with the functional material layer 210, thereby generating low frequency noise. The subsequent de-compounding and passivation of the functional material layer 210 can effectively reduce low frequency noise of the formed semiconductor structure.

Referring to fig. 11, the functional material layer 210 is subjected to a de-compounding process to reduce charged ions trapped by trap defects on the surface of the functional material layer 210.

The plasma gas for de-compounding treatment comprises: one or more combinations of helium, neon and argon.

Referring to fig. 12, after the de-recombination process, a passivation process is performed on the surface of the functional material layer 210 to reduce trap defects on the surface of the functional material layer 210, so as to form a gate function layer 211.

Correspondingly, the gate function layer 211 is a gate dielectric layer. Specifically, the gate dielectric layer is a gate oxide layer.

In this embodiment, after the passivation process, the method for forming a semiconductor structure further includes: and annealing the gate function layer 211.

After the passivation process, a gate electrode is subsequently formed on the gate functional layer 211.

Specifically, the step of forming the gate electrode includes:

as shown in fig. 13, a gate material layer 220 is formed on the gate function layer 211.

And, referring to fig. 14, the gate material layer 220 is patterned to form a gate 221.

In this embodiment, after patterning the gate material layer 220, the forming method further includes: the gate function layer 211 is patterned.

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.