阅读说明：本技术 具有低闪烁噪声的半导体装置和其形成方法 (Semiconductor device with low flicker noise and method of forming the same ) 是由 郑新立 郭良泰 张聿骐 于 2019-07-26 设计创作，主要内容包括：本发明实施例涉及具有低闪烁噪声的半导体装置和其形成方法。在一些实施例中,提供一种半导体装置。所述半导体装置包含布置于半导体衬底中的源极区和漏极区,其中所述源极区与所述漏极区横向间隔。栅极堆叠布置于所述半导体衬底上和所述源极区与所述漏极区之间。盖层布置于所述栅极堆叠上,其中所述盖层的底面接触所述栅极堆叠的顶面。侧壁间隔件沿所述栅极堆叠和所述盖层的侧布置。抗蚀剂保护氧化物RPO层安置于所述盖层上,其中所述RPO层沿所述侧壁间隔件的侧延伸到所述半导体衬底。接触蚀刻停止层布置于所述RPO层、所述源极区和所述漏极区上。(Embodiments relate to a semiconductor device having low flicker noise and a method of forming the same. In some embodiments, a semiconductor device is provided. The semiconductor device includes a source region and a drain region arranged in a semiconductor substrate, wherein the source region is laterally spaced from the drain region. A gate stack is arranged on the semiconductor substrate and between the source and drain regions. A cap layer is disposed on the gate stack, wherein a bottom surface of the cap layer contacts a top surface of the gate stack. Sidewall spacers are disposed along sides of the gate stack and the cap layer. A Resist Protective Oxide (RPO) layer is disposed on the cap layer, wherein the RPO layer extends to the semiconductor substrate along sides of the sidewall spacers. A contact etch stop layer is disposed on the RPO layer, the source region, and the drain region.)

1. A semiconductor device, comprising:

a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region;

a gate stack disposed on the semiconductor substrate and arranged between the source region and the drain region;

a cap layer disposed on the gate stack, wherein a bottom surface of the cap layer contacts a top surface of the gate stack;

a plurality of sidewall spacers disposed along sides of the gate stack and the cap layer;

a Resist Protective Oxide (RPO) layer disposed on the cap layer, wherein the RPO layer extends to the semiconductor substrate along a side of the sidewall spacer; and

a contact etch stop layer CESL disposed on the RPO layer, the source region, and the drain region.

2. The semiconductor device of claim 1, further comprising:

a first isolation region disposed in the semiconductor substrate and arranged on an opposite side of the source region as the gate stack;

a second isolation region disposed in the semiconductor substrate and arranged on an opposite side of the drain region as the gate stack; and is

Wherein the RPO layers extend in opposite lateral directions on opposite sides of the gate stack to at least partially cover the first isolation region and at least partially cover the second isolation region.

3. The semiconductor device of claim 2, wherein the RPO layer partially covers greater than or equal to approximately 0.2 microns of the source region and partially covers greater than or equal to approximately 0.2 microns of the drain region.

4. The semiconductor device of claim 1, wherein a top surface of the cap layer contacts a bottom surface of the RPO layer and a sidewall of the cap layer contacts the sidewall spacer.

5. The semiconductor device of claim 4, wherein the RPO layer has a horizontally extending segment extending over a portion of the source region and a vertically extending segment projecting outwardly from an upper surface of the horizontally extending segment and extending vertically along one of the sidewall spacers.

6. The semiconductor device of claim 5, wherein the CESL has a first upper surface above a second upper surface, and wherein the first upper surface and the second upper surface are arranged between a top surface of the gate stack and a top surface of the semiconductor substrate.

7. The semiconductor device of claim 6, wherein the CESL has a third upper surface arranged on a top surface of the gate stack, and wherein the third upper surface is a first distance from an upper surface of the gate stack and the second upper surface is a second distance from the upper surface of the semiconductor substrate substantially equal to the first distance.

8. A method for forming a semiconductor device, comprising:

forming a gate stack on a semiconductor substrate;

forming a capping layer on the gate stack;

injecting a noise reducing material into the gate stack;

forming a source region and a drain region in the semiconductor substrate, wherein the source region and the drain region are laterally spaced apart from the gate stack; and

performing a first annealing procedure on the semiconductor substrate, wherein the cap layer is configured to prevent outgassing of the noise-reducing material during the first annealing procedure.

9. A semiconductor device, comprising:

a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region;

a conductive gate electrode spaced from the semiconductor substrate by a gate dielectric layer, wherein the conductive gate electrode and the gate dielectric layer are arranged between the source region and the drain region;

a cap layer disposed on the conductive gate electrode, wherein the cap layer extends along opposing sides of the conductive gate electrode and opposing sides of the gate dielectric layer to contact a top surface of the semiconductor substrate; and

a Contact Etch Stop Layer (CESL) disposed on the cap layer, wherein the CESL extends beyond sidewalls of the cap layer and contacts the top surface of the semiconductor substrate.

10. The semiconductor device of claim 9, further comprising:

a first isolation region disposed in the semiconductor substrate and arranged on an opposite side of the source region as the conductive gate electrode, wherein the cap layer has a first horizontally extending segment extending over the source region along the top surface of the semiconductor substrate and at least partially over the first isolation region; and

a second isolation region disposed in the semiconductor substrate and arranged on an opposite side of the drain region as the conductive gate electrode, wherein the cap layer has a second horizontally extending segment extending over the drain region along the top surface of the semiconductor substrate and at least partially over the second isolation region.

Technical Field

Embodiments relate to a semiconductor device having low flicker noise and a method of forming the same.

Background

Semiconductor devices are electronic components that utilize the electrical conductivity of semiconductor materials to affect electrons or their associated fields. One type of semiconductor device that is widely used is a Field Effect Transistor (FET). The FET includes a pair of source/drain regions, a selective conductive channel, and a gate electrode. FETs are multifunctional devices that may be used, among other things, for switches, amplifiers, and memories. Examples of FETs include Metal Oxide Semiconductor Field Effect Transistors (MOSFETs).

Disclosure of Invention

An embodiment of the present invention relates to a semiconductor device, including: a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region; a gate stack disposed on the semiconductor substrate and arranged between the source region and the drain region; a cap layer disposed on the gate stack, wherein a bottom surface of the cap layer contacts a top surface of the gate stack; a plurality of sidewall spacers disposed along sides of the gate stack and the cap layer; a Resist Protection Oxide (RPO) layer disposed on the cap layer, wherein the RPO layer extends to the semiconductor substrate along a side of the sidewall spacer; and a Contact Etch Stop Layer (CESL) disposed on the RPO layer, the source region, and the drain region.

An embodiment of the invention relates to a method for forming a semiconductor device, comprising: forming a gate stack on a semiconductor substrate; forming a capping layer on the gate stack; injecting a noise reducing material into the gate stack; forming a source region and a drain region in the semiconductor substrate, wherein the source region and the drain region are laterally spaced apart from the gate stack; and performing a first annealing procedure on the semiconductor substrate, wherein the cap layer is configured to prevent outgassing of the noise-reducing material during the first annealing procedure.

An embodiment of the present invention relates to a semiconductor device, including: a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region; a conductive gate electrode spaced from the semiconductor substrate by a gate dielectric layer, wherein the conductive gate electrode and the gate dielectric layer are arranged between the source region and the drain region; a cap layer disposed on the conductive gate electrode, wherein the cap layer extends along opposing sides of the conductive gate electrode and opposing sides of the gate dielectric layer to contact a top surface of the semiconductor substrate; and a Contact Etch Stop Layer (CESL) disposed on the cap layer, wherein the CESL extends beyond sidewalls of the cap layer and contacts the top surface of the semiconductor substrate.

Drawings

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying drawing figures. It should be noted that the various devices are not drawn to scale in accordance with industry standard practice. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

Fig. 1 shows a cross-sectional view of some embodiments of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) having an anti-outgassing layer.

Fig. 2 shows a cross-sectional view of some more detailed embodiments of a MOSFET having an anti-outgassing layer.

Fig. 3A-3B show various views of some other more detailed embodiments of MOSFETs having an anti-outgassing layer.

Fig. 4A-4B illustrate some other embodiments of the MOSFET of fig. 3A-3B.

Fig. 5-19 show a series of cross-sectional views of some embodiments for forming a MOSFET having an anti-outgassing layer.

Fig. 20 depicts a flow diagram of some embodiments of a method for forming a MOSFET having an anti-outgassing layer.

Detailed Description

The present disclosure will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout, and wherein the depicted structures are not necessarily drawn to scale. It should be understood that [ embodiments ] and corresponding drawings in no way limit the scope of the present disclosure, and that [ embodiments ] and drawings merely provide some examples to illustrate some ways in which the inventive concepts themselves may be embodied.

The present disclosure provides many different embodiments, or examples, for implementing different features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, "forming a first device over or on a second device" may include embodiments in which the first device and the second device are formed in direct contact, and may also include embodiments in which additional devices may be formed between the first device and the second device such that the first device and the second device may not be in direct contact. Additionally, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially relative terms, such as "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or device's relationship to another element(s) or device, as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Some Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) include a semiconductor substrate and Shallow Trench Isolation (STI) structures. The STI structure is disposed in the semiconductor substrate and delimits a device region of the semiconductor substrate. In addition, the MOSFET includes a pair of source/drain regions, a selective conductive channel, a gate dielectric, and a gate electrode. The source/drain regions are disposed in the semiconductor substrate and are laterally spaced in the device region. The selectively conductive channel is disposed in the device region of the semiconductor substrate and extends laterally from one of the source/drain regions to the other of the source/drain regions. The gate dielectric layer and the gate electrode are arranged between the source/drain regions and disposed on the selective conductive channel.

The challenge of the above-described MOSFETs is flicker noise. Flicker noise is a type of electronic noise that has a power spectral density of 1/f or "pink". A source of flicker noise occurs near a central portion of the selective conductive channel and is due to charge carriers being trapped and released by defect states at the interface between the gate dielectric layer and the selective conductive channel. The gate dielectric layer includes traps that can cause carrier generation to occur and can cause unwanted fluctuations in the conductivity of the selective conductive channel due to defect states along the interface of the gate dielectric layer and the selective conductive channel.

Another source of flicker noise occurs near the peripheral portion of the selective conductive channel and is due to charge carriers being trapped and released at STI corners at the interface between the STI structure and the selective conductive channel. The STI corner is a top cross-sectional corner of the semiconductor substrate located on opposite sides of the selective conductive channel and interfacing with the STI structures in the device region of the semiconductor substrate. The STI corners may also contribute to unwanted fluctuations in the conductivity of the selective conductive channel due to defect states along the STI corners.

A method for mitigating flicker noise is to inject a noise reducing material into the semiconductor substrate and/or the gate electrode. For example, a noise reducing material may be implanted into a top surface of the gate electrode and/or a top surface of the semiconductor substrate. A first annealing procedure may be performed on the semiconductor substrate to diffuse the noise-reducing material through the gate electrode to an interface between the gate dielectric layer and the selective conductive channel and along the STI corners. The noise reducing material is configured to reduce flicker noise by bonding to dangling bonds present in a defect state. However, fabrication of the MOSFET uses one or more subsequent anneal procedures (e.g., source/drain region anneals) that may cause the noise-reducing material to outgas through the gate electrode and/or the semiconductor substrate. The effectiveness of the noise reducing material for reducing flicker noise affecting the MOSFET is reduced due to outgassing of the noise reducing material.

Accordingly, the present disclosure is directed to a method of forming a MOSFET having an anti-outgassing layer disposed on a portion of a gate electrode and/or a semiconductor substrate to prevent outgassing of noise reducing material during one or more subsequent anneal processes, such as source/drain region anneals. The outgassing prevention layer functions as a cap layer that prevents the noise reducing material from bleeding through the gate and/or the semiconductor substrate to the ambient environment. Thus, the outgassing prevention layer may prevent an amount of noise reducing material from outgassing from the MOSFET when a subsequent annealing procedure is performed. In some embodiments, the formation of the outgassing-prevention layer may be incorporated into a process step, such as a Resist Protection Oxide (RPO) layer, that has been used to form other devices of the MOSFET, such as silicided source/drain regions. Thus, the outgassing prevention layer may improve device performance of the MOSFET by reducing the amount of flicker noise that affects the MOSFET.

Fig. 1 shows a cross-sectional view of some embodiments of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET)100 having an anti-outgassing layer.

MOSFET100 includes a pair of source/drain regions 104 disposed within a semiconductor substrate 102. Source/drain regions 104 are laterally spaced from one another. In some embodiments, the source/drain regions 104 may comprise a first doping type (e.g., n-type doping).

A gate stack 106 is disposed on the semiconductor substrate 102 and arranged between the source/drain regions 104. The gate stack 106 includes a conductive gate electrode 108 spaced apart from the semiconductor substrate 102 by a gate dielectric layer 110.

The noise reduction material 111 is disposed near the upper surface of the semiconductor substrate 102. In some embodiments, the noise reduction material 111 is disposed near the interface of the gate dielectric layer 110 and the semiconductor substrate 102. In a further embodiment, the noise-reducing material 111 is disposed in the source/drain regions 104 near the upper surface of the semiconductor substrate 102. Although the noise-reducing material 111 is shown within the semiconductor substrate 102, it is understood that the noise-reducing material 111 may also be within the gate stack 106 (e.g., within the conductive gate electrode 108). In further embodiments, the noise-reducing material 111 may include fluorine (F), chlorine (Cl),Hydrogen (H) ₂) Deuterium (1) ²H) Or the like.

A patterned outgassing prevention layer 112 is disposed on the gate stack 106. In some embodiments, the patterned outgassing prevention layer 112 has sidewalls that are substantially aligned with the sidewalls of the gate stacks 106. In a further embodiment, the patterned outgassing prevention layer 112 may extend onto the source/drain regions 104 along the sides of the gate stacks 106. In further embodiments, the patterned outgassing prevention layer 112 may include silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like. In a further embodiment, the patterned outgassing prevention layer 112 may be considered a cap layer.

After the patterned outgassing containment layer 112 is formed over the gate stack 106, formation of the MOSFET100 may be completed using one or more subsequent annealing procedures, such as source/drain region annealing. As a result of having the patterned outgassing-prevention layer 112 formed on the gate stack 106, the patterned outgassing-prevention layer 112 may prevent the noise-reducing material 111 from bleeding through the gate stack 106 during one or more subsequent annealing processes to the ambient environment. Thus, the amount of flicker noise affecting MOSFET100 can be reduced by increasing the amount of noise reducing material 111 present in MOSFET100 after one or more subsequent anneal procedures. Additionally, in some embodiments, the formation of patterned outgassing prevention layer 112 may be incorporated into a process step, such as a Resist Protection Oxide (RPO) layer, that may have been used to form other devices of MOSFET100, such as silicided source/drain regions. Thus, patterning the outgassing prevention layer 112 may improve device performance by reducing the amount of flicker noise affecting the MOSFET100 without increasing the cost of manufacturing the MOSFET 100.

Fig. 2 shows a cross-sectional view of some more detailed embodiments of a MOSFET200 with an anti-outgassing layer.

The MOSFET200 includes a well 202 disposed in the semiconductor substrate 102. The well 202 may have a first doping type (e.g., p-type doping). The semiconductor substrate 102 may comprise any type of semiconductor body (e.g., single crystal silicon/CMOS bulk, silicon germanium (SiGe), silicon-on-insulator (SOI), etc.).

An isolation structure 204 may be disposed within the semiconductor substrate 102 and surround the well 202. The isolation structure 204 may be a Shallow Trench Isolation (STI) region or a Deep Trench Isolation (DTI) region. In a further embodiment, the isolation structure 204 may have a ring-shaped layout bounding the sides of the well 202.

A pair of source/drain regions 104 is disposed within the semiconductor substrate 102. The source/drain regions 104 are laterally spaced from one another by a selective conductive channel 206. A selective conductive via 206 is defined as a portion of well 202 extending laterally from one of source/drain regions 104 to the other of source/drain regions 104 along the top surface of semiconductor substrate 102. In some embodiments, source/drain regions 104 may comprise a second doping type (e.g., n-type doping) different from the first doping type.

A gate stack 106 is disposed on the semiconductor substrate 102 and arranged between the source/drain regions 104. The gate stack 106 includes a conductive gate electrode 108 spaced apart from the semiconductor substrate 102 by a gate dielectric layer 110. In some embodiments, the sidewall spacers 208 are arranged along opposing sides of the gate stack 106 such that the sides of the conductive gate electrode 108 and the sides of the gate dielectric layer 110 contact the sidewall spacers 208.

In some embodiments, the conductive gate electrode 108 comprises polysilicon. In these embodiments, the gate dielectric layer 110 may comprise, for example, an oxide (e.g., SiO) ₂) A dielectric material of nitride (e.g., silicon nitride), or the like. In other embodiments, the conductive gate electrode 108 may comprise a metal such as aluminum, copper, titanium, tantalum, tungsten, molybdenum, cobalt, or the like. In these embodiments, the gate dielectric layer 110 may comprise a high-k dielectric material such as hafnium oxide, hafnium silicon oxide, hafnium tantalum oxide, aluminum oxide, zirconium oxide, or the like. In some embodiments, the sidewall spacers 208 may comprise oxide, nitride, carbide, or the like.

A pair of lightly doped source/drain extension regions 210 is disposed within the semiconductor substrate 102 and extends below the sidewall spacers 208. Lightly doped source/drain extension regions 210 are laterally spaced apart and contact source/drain regions 104, respectively. In some embodiments, the lightly doped source/drain extension regions 210 comprise a second doping type (e.g., n-type doping). In a further embodiment, lightly doped source/drain extension regions 210 have a different doping concentration than source/drain regions 104.

The noise reduction material 111 is disposed near the upper surface of the semiconductor substrate 102. In some embodiments, the noise reduction material 111 is disposed near the interface of the gate dielectric layer 110 and the semiconductor substrate 102. In a further embodiment, the noise-reducing material 111 is disposed in the source/drain regions 104 near the upper surface of the semiconductor substrate 102. In a further embodiment, the noise-reducing material 111 may be disposed in the lightly doped source/drain extension regions 210 near the upper surface of the semiconductor substrate 102 and/or in the isolation structure 204 near the upper surface of the semiconductor substrate 102. The noise reduction material 111 may include fluorine (F), chlorine (Cl), hydrogen (H) ₂) Deuterium (1) ²H) Or the like.

A patterned outgassing prevention layer 112 is disposed on the gate stack 106. In some embodiments, the lowermost surface of patterned outgassing prevention layer 112 contacts the uppermost surface of conductive gate electrode 108. In various embodiments, patterned outgassing prevention layer 112 has sidewalls that are substantially aligned with the sidewalls of gate stack 106. In a further embodiment, the sidewall spacers 208 may contact opposing sides of the patterned outgassing prevention layer 112. In a further embodiment, an uppermost surface of the patterned outgassing prevention layer 112 may be substantially aligned with an uppermost portion of the sidewall spacer 208. The outgassing-preventing layer may include silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like.

A Resist Protective Oxide (RPO) layer 212 may be disposed on the patterned outgassing prevention layer 112 and along the sidewall spacers 208 to the upper surface of the semiconductor substrate 102. In some embodiments, a first bottom surface of RPO layer 212 contacts an upper surface of patterned outgassing prevention layer 112 and a second bottom surface of RPO layer 212 contacts an upper surface of semiconductor substrate 102. In a further embodiment, the RPO layer 212 extends laterally along the upper surface of the semiconductor substrate 102 to cover a portion of the source/drain regions 104. In these embodiments, the RPO layer 212 may extend laterally from the sidewall spacers 208 a distance greater than or equal to about 0.2 micrometers (μm).

In some embodiments, the RPO layer 212 may extend laterally along the upper surface of the semiconductor substrate 102 covering a portion of the isolation structure 204. In these embodiments, the RPO layer 212 mayLaterally extends beyond source/drain regions 104 to cover isolation structures 204 by a distance greater than or equal to about 0.2 μm. In other embodiments, the RPO layer 212 is optional. The RPO layer 212 may comprise silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like.

A Contact Etch Stop (CESL)214 is disposed on the RPO layer 212 and extends laterally over the source/drain regions 104 and the isolation structures 204. In some embodiments, a first bottom side of CESL 214 contacts an upper surface of RPO layer 212 and a second bottom side of CESL 214 contacts an upper surface of semiconductor substrate 102. In a further embodiment, CESL 214 is a conformal layer that completely covers MOSFET 200. In various embodiments, CESL may comprise an oxide (e.g., SiO) ₂) Nitride (e.g., silicon nitride), carbide (e.g., silicon carbide), or the like.

Fig. 3A-3B show various views of some other more detailed embodiments of MOSFETs having an anti-outgassing layer. Fig. 3A is a cross-sectional view of a MOSFET having an anti-outgassing layer. Fig. 3B is a top view of a MOSFET having an anti-outgassing layer.

MOSFET 300 may include a patterned outgassing prevention layer 112 disposed on gate stack 106 and extending along sidewall spacers 208 to the upper surface of semiconductor substrate 102. In some embodiments, the patterned outgassing prevention layer 112 may extend laterally over the source/drain regions 104 and the isolation structures 204. In various embodiments, patterned outgassing prevention layer 112 may be formed via the same procedure that forms RPO layer 212 in other areas of an Integrated Circuit (IC). In a further embodiment, the CESL 214 is disposed on the patterned outgassing prevention layer 112 and extends laterally over the source/drain regions 104 and the isolation structures 204. In a further embodiment, a bottom surface of CESL 214 contacts an upper surface of patterned outgassing prevention layer 112.

As shown in the cross-sectional view of fig. 3A, the CESL 214 may have a first upper surface, a second upper surface, and a third upper surface. The first surface is disposed on the second upper surface, and both the first upper surface and the second upper surface are arranged between the top surface of the gate stack 106 and the top surface of the semiconductor substrate 102. The third upper surface is disposed on both the first upper surface and the second upper surface and is arranged on the top surface of the gate stack 106. In some embodimentsA first upper surface of the CESL 214 is a first distance d from an uppermost surface of the semiconductor substrate 102 ₁. In a further embodiment, the second upper surface of the CESL 214 is less than the first distance d from the uppermost surface of the semiconductor substrate 102 ₁Second distance d ₂. In a further embodiment, the third upper surface of CESL 214 is substantially the same as the second distance d from the top surface of the gate stack 106 ₂Third distance d ₃。

As shown in the top view of fig. 3B, the patterned outgassing-prevention layer 112 may extend laterally along the first axis a fourth distance d beyond the outer sidewall of the sidewall spacer 208 ₄. In some embodiments, the patterned outgassing-prevention layer 112 may extend laterally over the isolation structures 204 a fifth distance d along a second axis perpendicular to the first axis ₅. In a further embodiment, the fourth distance d ₄Greater than or equal to about 0.2 micrometers (μm), and a fifth distance d ₅Greater than or equal to about 0.2 μm. In a further embodiment, the fourth distance d ₄And a fifth distance d ₅Are substantially the same. In other embodiments, the fourth distance d ₄And a fifth distance d ₅Different. Since patterned outgassing containment layer 112 is extended beyond the outer sidewalls of sidewall spacers 208 onto isolation structures 204, patterned outgassing containment layer 112 reduces the amount of noise reducing material 111 that outgases through MOSFET 300. Thus, the performance of MOSFET 300 can be improved by reducing the amount of flicker noise that affects MOSFET 300.

Fig. 4A-4B illustrate some other embodiments of the MOSFET of fig. 3A-3B. Fig. 4A is a cross-sectional view of a MOSFET having an anti-outgassing layer. Fig. 4B is a top view of a MOSFET having an anti-outgassing layer.

As shown in fig. 4A-4B, the patterned outgassing prevention layer 112 extends partially over the isolation structures 204. In some embodiments, the patterned outgassing prevention layer 112 extends in the first lateral direction to overlap the isolation structure 204 by a sixth distance d ₆. In a further embodiment, the sixth distance d ₆Greater than or equal to about 0.2 μm. In a further embodiment, the sixth distance d ₆And a fifth distance d ₅Are substantially the same. In other embodiments, the sixth distance d ₆And a fifth distance d ₅Different.

Fig. 5-19 show a series of cross-sectional views of some embodiments for forming a MOSFET having an anti-outgassing layer. Although fig. 5-19 are described with respect to a method, it should be understood that the structure disclosed in fig. 5-19 is not limited to such a method, but may stand alone as a method-independent structure.

As illustrated by fig. 5, an isolation structure 204 is formed within the semiconductor substrate 102. In some embodiments, the isolation structure 204 may be formed by selectively etching the semiconductor substrate 102 to form a trench in the semiconductor substrate 102 and then filling the trench with a dielectric material. In a further embodiment, the semiconductor substrate 102 is selectively etched by forming a mask layer (not shown) on the semiconductor substrate 102 and subsequently exposing the semiconductor substrate 102 to an etchant configured to selectively remove unmasked portions of the semiconductor substrate 102. In further embodiments, the dielectric material may include an oxide (e.g., silicon oxide), a nitride, a carbide, or the like.

As depicted by fig. 6, a well 202 is formed within the semiconductor substrate 102. The well 202 is a region of the semiconductor substrate 102 having a first doping type, for example p-type doping. In some embodiments, the well 202 has a doping type opposite to that of the adjoining region of the semiconductor substrate 102. In various embodiments, the well 202 may be formed by an ion implantation procedure and a masking layer (not shown) may be utilized to selectively implant ions into the semiconductor substrate 102.

As depicted by fig. 7, a dielectric layer 702 and a conductive layer 704 are formed over the isolation structure 204 and the well 202 such that the dielectric layer 702 separates the conductive layer 704 from the semiconductor substrate 102. In some embodiments, the dielectric layer 702 may be silicon dioxide, a high-k dielectric, or some other dielectric. In further embodiments, the conductive layer 704 may be doped polysilicon, metal, or some other conductor. In other embodiments, the conductive layer 704 may be polysilicon that undergoes a subsequent doping process (e.g., ion implantation).

In some embodiments, the procedure for forming the dielectric layer 702 and the conductive layer 704 includes: a dielectric layer 702 is deposited or grown over the isolation structures 204 and wells 202 of the semiconductor substrate 102, and then a conductive layer 704 is deposited or grown over the dielectric layer 702. In further embodiments, the dielectric layer 702 may be deposited or grown by thermal oxidation, Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD), sputtering, or some other deposition or growth procedure. In further embodiments, the conductive layer 704 may be deposited or grown by CVD, PVD, ALD, sputtering, electrochemical plating, electroless plating, or some other deposition or growth procedure.

As illustrated by fig. 8, an outgassing prevention layer 802 is formed on the conductive layer 704. In some embodiments, the outgassing prevention layer 802 may include silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like. In a further embodiment, the outgassing prevention layer 802 may be deposited or grown over the conductive layer 704 by thermal oxidation, CVD, PVD, ALD, sputtering, or some other deposition or growth procedure.

As illustrated by fig. 9, a noise reducing material 111 is formed on the semiconductor substrate 102. In some embodiments, the noise-reducing material 111 may be formed by selectively implanting a dopant species 902 into the outgassing-prevention layer 802. In various embodiments, the dopant species 902 may include fluorine (F), chlorine (Cl), hydrogen (H) ₂) Deuterium (1) ²H) Or the like. In other embodiments, the noise reduction material 111 may be formed by selectively implanting a dopant species 902 into the conductive layer 704. In these embodiments, the outgassing prevention layer 802 is formed after implanting the dopant species 902 into the conductive layer 704. In further embodiments, the noise-reducing material 111 may be formed prior to forming the dielectric layer 702, the conductive layer 704, and/or the anti-outgassing layer 802. In these embodiments, the noise-reducing material 111 is formed on the upper surface of the semiconductor substrate 102.

As depicted by fig. 10, a first anneal 1002 is performed on the semiconductor substrate 102 after the noise-reducing material 111 is implanted into the outgassing-prevention layer 802. The first anneal 1002 is configured to diffuse the noise-reducing material 111 into the upper region of the semiconductor substrate 102. For example, the noise-reducing material 111 may diffuse to the interface between the dielectric layer 702 and the well 202, the interface between the isolation structure 204 and the dielectric layer 702, and/or a corner of the isolation structure 204 and the well 202 disposed near the upper surface of the semiconductor substrate 102. Although the noise-reducing material 111 is shown within the semiconductor substrate 102, it is understood that the noise-reducing material 111 may also be within the dielectric layer 702 and/or the conductive layer 704. In a further embodiment, some noise-reducing material 111 is disposed in the dielectric layer 702 and some noise-reducing material is disposed in the semiconductor substrate 102. In various embodiments, the first anneal 1002 may be performed at about 750 ℃, and the first anneal 1002 may be performed for about 2 to 4 hours.

As depicted by fig. 11, the conductive layer 704 and the dielectric layer 702 are patterned into the gate stack 106, and the outgassing-prevention layer 802 is patterned into the patterned outgassing-prevention layer 112. The gate stack 106 includes a conductive gate electrode 108 spaced apart from the semiconductor substrate 102 by a gate dielectric layer 110. In some embodiments, the conductive layer 704 and the dielectric layer 702 may be patterned prior to forming the outgassing prevention layer 802 and/or injecting the noise reduction material 111.

In some embodiments, the process for patterning the conductive layer 704, the dielectric layer 702, and the outgassing-prevention layer 802 includes forming a patterned mask layer (not shown) on the outgassing-prevention layer 802. In various embodiments, the patterned mask layer may be formed by a spin-on procedure and patterned using photolithography. In a further embodiment, the program comprises: after the patterned mask layer is in place, etching into the outgassing prevention layer 802, the conductive layer 704, and the dielectric layer 702 is performed, and then the patterned mask layer is stripped. In a further embodiment, the conductive layer 704, the dielectric layer 702, and the outgassing-prevention layer 802 are patterned by a single patterning procedure. In other embodiments, a first patterning procedure is performed to pattern the outgassing prevention layer 802 and a second patterning procedure is performed to pattern the conductive layer 704 and the dielectric layer 702.

As illustrated by fig. 12, a pair of lightly doped source/drain extension regions 210 are formed in the well 202. In some embodiments, the lightly doped source/drain extension regions 210 comprise a second doping type (e.g., n-type doping) different from the first doping type (e.g., p-type doping). In various embodiments, the lightly doped source/drain extension pair 210 may be formed by an ion implantation procedure and a masking layer (not shown) may be utilized to selectively implant ions into the semiconductor substrate 102. In a further embodiment, the noise-reducing material 111 may be implanted into the gate stack 106, the patterned outgassing prevention layer 112, and the semiconductor substrate 102 during the formation of the lightly doped source/drain extension regions 210.

As depicted by fig. 13, sidewall spacers 208 are formed on the semiconductor substrate 102 and along the sides of the gate stack 106 and the patterned outgassing-prevention layer 112. In some embodiments, the sidewall spacers 208 may be formed by depositing a spacer layer on the semiconductor substrate 102, the gate stack 106, and the patterned outgassing prevention layer 112. In further embodiments, the spacer layer may be deposited by PVD, CVD, ALD, sputtering, or some other deposition procedure. Subsequently, in a further embodiment, the spacers are etched to remove the spacers from the horizontal surfaces to leave the spacers along the opposite sides of the gate stack 106 and the patterned outgassing-prevention layer 112 as sidewall spacers 208. In various embodiments, the spacer layer may comprise silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like. In some embodiments, the sidewall spacers 208 may be formed prior to forming the lightly doped source/drain extension regions 210. In these embodiments, the lightly doped source/drain extension regions 210 may be formed using a tilted implantation process.

As depicted by fig. 14, a pair of source/drain regions 104 are formed within a well 202. In some embodiments, the source/drain region pair 104 includes a second doping type (e.g., n-type doping). In a further embodiment, the source/drain regions 104 adjoin lightly doped source/drain extension regions 210, respectively. In a further embodiment, the source/drain regions 104 have a different doping concentration than the lightly doped source/drain extension regions 210. In various embodiments, the source/drain regions 104 may be formed by an ion implantation procedure and a masking layer (not shown) may be utilized to selectively implant ions into the semiconductor substrate 102. In further embodiments, the noise-reducing material 111 may be implanted into the gate stack 106, the patterned outgassing prevention layer 112, and the semiconductor substrate 102 during the formation of the source/drain regions 104.

As illustrated by fig. 15, the resist is protectedAn oxide (RPO) layer 212 is formed on the patterned outgassing prevention layer 112 and the semiconductor substrate 102 and along the sidewall spacers 208. In some embodiments, RPO layer 212 may comprise silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like.

In some embodiments, the procedure for forming the RPO layer 212 may include depositing or growing a conformal RPO layer (not shown) over the gate stack 106, the sidewall spacers 208, and the semiconductor substrate 102. The conformal RPO layer may be deposited or grown by thermal oxidation, CVD, PVD, ALD, sputtering, or some other deposition or growth procedure. In various embodiments, a patterned masking layer is formed on the conformal RPO layer by a spin-on procedure and patterned using photolithography. In a further embodiment, after the patterned mask is in place, an etch into the conformal RPO layer is performed, and the patterned mask layer is subsequently stripped.

In some embodiments, the RPO layer 212 may be formed such that the patterned outgassing-prevention layer 112 (or a portion of the patterned outgassing-prevention layer 112) is not covered by the RPO layer 212. In a further embodiment, the RPO layer 212 may be formed on the conductive gate electrode 108 such that a bottom surface of the RPO layer 212 contacts the conductive gate electrode 108. In such an embodiment, the patterned outgassing prevention layer 112 may not be formed and the RPO layer 212 may prevent the noise-reducing material 111 from outgassing during one or more subsequent annealing processes. In further embodiments, the patterned outgassing prevention layer 112, the RPO layer 212, or a combination of both may prevent outgassing of the noise reducing material 111 such that the concentration of the noise reducing material 111 near the interface between the gate dielectric layer 110 and the semiconductor substrate 102 is greater than or equal to about 1.0 x 10 ²¹cm ^-3. In further embodiments, RPO layer 212 may be used to form other devices of a MOSFET (e.g., silicided source/drain regions), which may improve device performance (e.g., by limiting the amount of process steps used to form the MOSFET) without increasing the cost of manufacturing the MOSFET.

As illustrated by fig. 16, a second annealing process 1602 is performed on the semiconductor substrate 102. In some embodiments, the second annealing procedure 1602 is a drive-in annealing procedure configured to diffuse dopant species (e.g., phosphorous, arsenic, etc.) of the source/drain regions 104 into the semiconductor substrate 102. During the second annealing procedure 1602, the noise-reducing material 111 may outgas by seeping out to the ambient environment through the gate stack 106 and/or the semiconductor substrate 102. However, since the patterned outgassing containment layer 112 is formed over the gate stack (and/or the semiconductor substrate 102), the patterned outgassing containment layer 112 may prevent an amount of the noise reduction material 111 from outgassing from the MOSFET.

As illustrated by fig. 17, in some embodiments, a silicide layer 1702 is formed on the source/drain regions 104. In some embodiments, an additional silicide layer (not shown) is formed on the conductive gate electrode 108. In various embodiments, the silicide layer 1702 may include nickel (e.g., nickel silicide), titanium (e.g., titanium silicide), cobalt (e.g., cobalt silicide), platinum (e.g., platinum silicide), tungsten (e.g., tungsten silicide), or the like.

In some embodiments, the process for forming the silicide layer 1702 includes: a transition metal layer is deposited overlying the RPO layer 212 and the semiconductor substrate 102 and subsequently heated such that it reacts with the exposed silicon to form a silicide layer 1702. In a further embodiment, the procedure includes removing unreacted material of the transition metal layer (and/or the RPO layer 212) by etching. In a further embodiment, the procedure may be a self-aligned procedure.

As depicted by fig. 18, a Contact Etch Stop (CESL)214 is formed on the RPO layer 212 and the semiconductor substrate 102. In some embodiments, CESL 214 may comprise silicon nitride, silicon dioxide (SiO) ₂) Silicon oxynitride (e.g., SiON), or the like. In a further embodiment, CESL 214 may be deposited or grown on RPO layer 212 and semiconductor substrate 102 by thermal oxidation, CVD, PVD, ALD, sputtering, or some other deposition or growth procedure. In a further embodiment, CESL 214 is conformally formed on RPO layer 212 and semiconductor substrate 102.

As illustrated by fig. 19, an inter-layer dielectric (ILD) layer 1902 is formed on the CESL 214. The ILD layer 1902 may be formed with a planar upper surface and may comprise an oxide, a nitride, a low-k dielectric, or some other dielectric. In some embodiments, the ILD layer 1902 may be formed by CVD, PVD, sputtering, or some other deposition or growth procedure. In a further embodiment, a planarization procedure, such as Chemical Mechanical Planarization (CMP), may be performed on the ILD layer 1902 to form a substantially planar upper surface.

Also illustrated in fig. 19, contacts 1904 are formed that extend through the ILD layer 1902 and CESL 214 to the source/drain regions 104 and/or the silicide layer 1702. In some embodiments, a contact 1904 may be formed that extends through the ILD layer 1902 to the conductive gate electrode 108. In a further embodiment, a silicide layer (not shown) may be formed on the conductive gate electrode 108 and the contact 1904 may extend through the ILD layer 1902 to the silicide layer (not shown).

In some embodiments, the procedure for forming the contacts 1904 includes performing an etch into the ILD layer 1902 to form contact openings corresponding to the contacts 1904. In some embodiments, the etching may be performed after a patterned mask layer is formed on the ILD layer 1902. In a further embodiment, the procedure includes filling the contact openings with a conductive material (e.g., tungsten). In a further embodiment, the contact openings may be filled by depositing or growing a conductive layer overlying the ILD layer 1902 (which fills the contact openings) and then performing planarization (e.g., CMP) on the ILD layer 1902.

Although not shown in the figures, additional dielectric layers and conductive devices may be subsequently formed on the ILD layer 1902. For example, one or more additional ILD layers, wires, vias, and/or passivation layers may be formed on the ILD layer 1902.

As depicted in fig. 20, a flow diagram 2000 of some embodiments of a method for forming a MOSFET having an anti-outgassing layer is provided. Although the flow diagram 2000 of fig. 20 is depicted and described herein as a series of acts or events, it will be appreciated that the depicted order of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. Further, not all illustrated acts may be required to implement one or more aspects or embodiments described herein, but rather one or more of the acts depicted herein may be implemented in one or more separate acts and/or phases.

In 2002, an isolation structure is formed within a semiconductor substrate. FIG. 5 illustrates a cross-sectional view of some embodiments corresponding to act 2002.

In 2004, a well is formed within the semiconductor substrate. Fig. 6 illustrates a cross-sectional view of some embodiments corresponding to act 2004.

In 2006, a dielectric layer, a conductive layer, and an outgassing prevention layer are formed on a semiconductor substrate, where the outgassing prevention layer is disposed on the conductive layer and the conductive layer is spaced apart from the semiconductor substrate by the dielectric layer. Fig. 7-8 depict cross-sectional views of some embodiments corresponding to act 2006.

In 2008, a noise reducing material is formed on a semiconductor substrate. Fig. 9 illustrates a cross-sectional view of some embodiments corresponding to act 2008.

In 2010, a first anneal is performed on the semiconductor substrate to diffuse the noise reducing material to an interface between the dielectric layer and the semiconductor substrate. Fig. 10 depicts a cross-sectional view of some embodiments corresponding to act 2010.

In 2012, the conductive layer and the dielectric layer are patterned into a gate stack and the outgassing prevention layer is patterned into a patterned outgassing prevention layer. FIG. 11 shows a cross-sectional view of some embodiments corresponding to act 2012.

In 2014, a pair of lightly doped source/drain extensions are formed in the semiconductor substrate. Figure 12 depicts a cross-sectional view of some embodiments corresponding to act 2014.

At 2016, sidewall spacers are formed along opposing sides of the gate stack and the patterned outgassing prevention layer. Fig. 13 depicts a cross-sectional view of some embodiments corresponding to act 2016.

In 2018, a pair of source/drain regions is formed in a semiconductor substrate. FIG. 14 depicts a cross-sectional view of some embodiments corresponding to act 2018.

In 2020, a Resist Protective Oxide (RPO) layer is formed over the patterned outgassing prevention layer and the semiconductor substrate and along the sidewall spacers. Fig. 15 depicts a cross-sectional view of some embodiments corresponding to act 2020.

In 2022, a second anneal is performed to the semiconductor substrate. Fig. 16 shows a cross-sectional view of some embodiments corresponding to act 2022.

In 2024, a silicide layer is formed on the source/drain regions. Fig. 17 shows a cross-sectional view of some embodiments corresponding to act 2024.

In 2026, a Contact Etch Stop Layer (CESL) is formed on the RPO layer and the semiconductor substrate. Fig. 18 shows a cross-sectional view of some embodiments corresponding to act 2026.

In 2028, an interlayer dielectric (ILD) layer is formed on the CESL. Fig. 19 shows a cross-sectional view of some embodiments corresponding to act 2028.

In 2030, contacts are formed that extend through the ILD layer and CESL to the silicide layer. Fig. 19 depicts a cross-sectional view of some embodiments corresponding to act 2030.

In some embodiments, the present application provides a semiconductor device. The semiconductor device includes a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region. A gate stack is disposed on the semiconductor substrate and arranged between the source region and the drain region. A cap layer is disposed on the gate stack, wherein a bottom surface of the cap layer contacts a top surface of the gate stack. Sidewall spacers are disposed along sides of the gate stack and the cap layer. A Resist Protection Oxide (RPO) layer is disposed on the cap layer, wherein the RPO layer extends to the semiconductor substrate along sides of the sidewall spacers. A Contact Etch Stop Layer (CESL) is disposed on the RPO layer, the source region, and the drain region.

In other embodiments, the present application provides a method for forming a semiconductor device. The method includes forming a gate stack on a semiconductor substrate. A cap layer is formed over the gate stack. Injecting a noise reducing material into the gate stack. Forming a source region and a drain region in the semiconductor substrate, wherein the source region and the drain region are laterally spaced apart from the gate stack. Performing a first annealing procedure on the semiconductor substrate, wherein the cap layer is configured to prevent outgassing of the noise-reducing material during the first annealing procedure.

In other embodiments, the present application provides a semiconductor device. The semiconductor device includes a source region and a drain region disposed in a semiconductor substrate, wherein the source region is laterally spaced from the drain region. A conductive gate electrode is spaced from the semiconductor substrate by a gate dielectric layer, wherein the conductive gate electrode and the gate dielectric layer are arranged between the source region and the drain region. A capping layer is disposed on the conductive gate electrode, wherein the capping layer extends along opposing sides of the conductive gate electrode and opposing sides of the gate dielectric layer to contact a top surface of the semiconductor substrate. A Contact Etch Stop Layer (CESL) is disposed on the cap layer, wherein the CESL extends beyond sidewalls of the cap layer and contacts the top surface of the semiconductor substrate.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Description of the symbols

100 Metal Oxide Semiconductor Field Effect Transistor (MOSFET)

102 semiconductor substrate

104 source/drain region

106 gate stack

108 conductive gate electrode

110 gate dielectric layer

111 noise reducing material

112 patterned outgassing prevention layer

200 MOSFET

202 well

204 isolation structure

206 selective conductive path

208 sidewall spacers

210 lightly doped source/drain extensions

212 Resist Protective Oxide (RPO) layer

214 Contact Etch Stop Layer (CESL)

300 MOSFET

702 dielectric layer

704 conductive layer

802 anti-outgassing layer

902 dopant species

1002 first annealing

1602 second annealing program

1702 silicide layer

1902 an interlayer dielectric (ILD) layer

1904 contact

2000 flow chart

2002 act

2004 act

Action 2006

2008 act

Action 2010

2012 action

2014 act

2016 act

2018 act

2020 movement

2022 act

2024 act

2026 act

2028 act

2030 actions

d ₁First distance

d ₂Second distance

d ₃Third distance

d ₄A fourth distance

d ₅A fifth distance

d ₆A sixth distance