Method for reducing N-type FinFET source and drain resistance

A method of manufacturing a semiconductor device includes providing a substrate structure, the substrate structure having a semiconductor substrate including a first semiconductor fin, a first gate structure, and a first mask layer on a first semiconductor region. The method includes forming a second mask layer on the substrate structure, etching first mask layer and second mask layer to expose a portion of a first semiconductor fin not covered by the first gate structure, performing a first ion implantation on an exposed portion of the first semiconductor fin to introduce impurities into a portion of the first semiconductor fin located below the first gate structure, etching the first semiconductor fin to remove a portion of an exposed portion of the first semiconductor fin, and epitaxially growing a first semiconductor material on the remaining portions of the first semiconductor fin to form a first source region and a first drain region.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 201610379189.9, filed on Jun. 1, 2016, the content of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to the field of semiconductor technology. Embodiments of the invention relate to integrated circuit package structures and manufacturing methods.

In FinFET (Fin Field Effect Transistor) devices, the parasitic resistance has a great influence on the resistance of the source region and the drain region. The parasitic resistance can be caused by a variety of reasons. For example, an important contribution to the parasitic resistance comes from the contact resistance between a metal silicide and the source and drain regions. And the contact between metal silicides with the source and drain regions tends to pinch the Fermi level near the middle of the band gap, which leads to a large Schottky barrier height that increases the contact resistance between the metal silicide and the source region and the drain region.

High resistance in the source and drain regions can have adverse effects in device performance, particularly in FinFET devices. Due to the smaller size, the high resistance of the source and drain regions will reduce the performance of FinFET devices more severely.

Therefore, there is an urgent need for improved techniques for reducing the resistance of the source region and the drain region.

BRIEF SUMMARY OF THE INVENTION

According to some embodiments of the invention, a method of manufacturing a semiconductor device includes providing a substrate structure, the substrate structure including a semiconductor substrate including a first semiconductor region, a first semiconductor fin on the first semiconductor region, a first gate structure on a portion of the surface of the first semiconductor fin, and a first mask layer on the first semiconductor fin and the first gate structure. The method includes forming a second mask layer on the substrate structure, etching the first mask layer and the second mask layer to expose a portion of a first semiconductor fin that is not covered by the first gate structure, performing a first ion implantation on an exposed portion of the first semiconductor fin to introduce impurities into a portion of the first semiconductor fin located below the first gate structure, etching the first semiconductor fin to remove at least a portion of an exposed portion of the first semiconductor fin, and epitaxially growing a first semiconductor material on the remaining portions of the first semiconductor fin to form a first source region and a first drain region.

In an embodiment, the method also includes performing a second ion implantation to the first source region and the first drain region.

In an embodiment, the implantation energy of the first ion implant is greater than the implantation energy of the second ion implantation.

In an embodiment, the method also includes forming a spacer on the first gate structure by etching the first mask layer and the second mask layer.

In an embodiment, said first gate electrode structure includes a first gate dielectric layer on a portion of a surface of the first semiconductor fin, a first gate on said first gate dielectric layer, and a first hard mask layer on the first gate.

In an embodiment, the substrate structure further comprises a bias spacer layer between the first semiconductor fin and the first mask layer, and between the first gate structure and the first mask layer.

In an embodiment, the first semiconductor material is different from the second semiconductor fin material.

In an embodiment, the semiconductor substrate further includes a second semiconductor region adjacent to said first semiconductor region, and the substrate structure includes a second semiconductor fin on said second semiconductor region, a second gate structure on a portion of the surface of the second semiconductor fin, and a second source region and a second drain region on both sides of the second gate structure. The second gate structure includes a second gate dielectric layer on a portion of a surface of the second semiconductor fin, a second gate on the second gate dielectric layer, a second hard mask layer on the second gate, and a bias spacer layer on the sidewalls of the second gate dielectric layer, the second gate, and the second hard mask layer.

In an embodiment, the step of providing a substrate structure includes providing an initial substrate structure, which includes:a semiconductor substrate including a first semiconductor region and a second semiconductor region,a first semiconductor fin on said first semiconductor region,a second semiconductor fin on said second semiconductor region, andan isolation region between the semiconductor fins;
forming a gate dielectric material layer on the initial substrate structure;
forming a gate material layer on the gate dielectric material layer;
forming a patterned hard mask layer on the gate material layer;
patterning a gate material layer and a gate dielectric material layer with a patterned hard mask layer to form a first structure and a second structure, the first structure including a first gate dielectric layer, a first gate electrode, and a first hard mask layer on the first semiconductor fin, the second structure including a second gate dielectric layer, a second gate electrode, and a second hard mask layer on the first semiconductor fin;
depositing an offset spacer layer on the substrate structure after the patterning step;
depositing a first barrier layer to cover the second semiconductor region above the offset spacer layer, and performing a first LDD implantation to the part of not covered by the first barrier layer;
removing a second barrier layer and depositing a first mask layer on the offset spacer layer;etching the masking layer and the offset spacer layer on the second semiconductor region to retain portions of the offset spacer layer and the first masking layer on the sidewalls of the second structure;etching the exposed portion of the second semiconductor fin to remove at least a portion of the exposed portion of the second semiconductor fin; andepitaxially growing a second semiconductor material on the remaining portion of the second semiconductor fin to form the second source region and the second drain region.

In an embodiment, the step of providing an initial substrate structure includes: providing an initial semiconductor substrate comprising a first semiconductor region and a second semiconductor region, etching the initial semiconductor substrate to form a first semiconductor fin on the first semiconductor region and a second semiconductor fin on the second semiconductor region, depositing a spacer material so as to cover a space between each of the semiconductor fins and each of the semiconductor fins; and etching the isolation material to expose a portion of each of the semiconductor fins to form an isolation region between the semiconductor fins.

Some embodiments of the invention can reduce n-type FinFET source and drain resistance. For example, after n-type source/drain formation, the first phosphorus implant is to reduce extension resistance, and is implanted post LDD spike anneal and SiGe epitaxial growth process in the PMOS region, in order to reduce diffusion during thermal processes, which will lead to a worse short channel effect. The source/drain recessed regions are implemented to provide a larger volume for epitaxy growth, which will bring more stress into the channel, and improve device performance. The silicon epitaxial growth in the n-type source and drain includes heavy in-situ implantation with a phosphorus dose as high as 1×1021/cm3. Next, a phosphorus implant is carried out to reduce the Schottky barrier height, which will reduce the contact resistance.

The following description, together with the accompanying drawings, will provide further understanding of the nature and advantages of the claimed invention.

DETAILED DESCRIPTION OF THE INVENTION

The drawings of various exemplary embodiments of the present invention will be described in detail. It should be noted that, unless otherwise specified, the relative arrangement set forth in these embodiments, components and steps, the numerical expressions, and values do not limit the scope of the present invention. At the same time, it should be appreciated that, for ease of description, the dimensions of the various parts are not illustrated in the drawings according to the actual proportional relationship.

The following description of exemplary embodiments is merely illustrative of the present invention and in no way intends to impose any restrictions on its use or application. Techniques, methods, and equipment known to someone of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the techniques, methods and equipment should be considered as part of the specification.

In all the examples shown and discussed, any specific value is to be construed as merely illustrative, and not as a limitation. Accordingly, another exemplary embodiment may have different values. It should be also noted that like reference numerals and letters refer to similar items in the following figures, and thus once an item is defined in one figure, it need not be further discussed in subsequent figures.

FIG. 1is a simplified flowchart of a method of manufacturing a semiconductor device according to an embodiment of the present invention. As shown inFIG. 1, the method can be briefly summarized below.Step101—Providing a substrate structure. In some embodiments, the substrate structure includes a semiconductor substrate having a first semiconductor region, a first semiconductor fin on the first semiconductor region, a first gate structure on a portion of the surface of the first semiconductor fin, and a first mask layer on the first semiconductor fin and the first gate structure;Step103—Forming a second mask layer on the substrate structure;Step105—Etching the first mask layer and the second mask layer to expose a portion of a first semiconductor fin that is not covered by the first gate structure;Step107—Performing a first ion implantation on an exposed portion of the first semiconductor fin to introduce impurities into a portion of the first semiconductor fin located below the first gate structure;Step109—Etching the first semiconductor fin to remove at least a portion of an exposed portion of the first semiconductor fin; andStep111—Epitaxially growing a first semiconductor material on the remaining portions of the first semiconductor fin to form a first source region and a first drain region.

The method is described further below with reference toFIGS. 2A-8B.FIGS. 2A-8Aare cross-sectional views of the device structure perpendicular to the channel, andFIGS. 2B-8Bare cross-sectional views of the device structure along the channel direction.

FIGS. 2A and 2Billustrate a substrate structure that includes a semiconductor substrate201having a first semiconductor region211, e.g., an NMOS region, and a first semiconductor fin202in the first semiconductor region, a first gate structure203on a portion of the surface of the first semiconductor fin, and a first mask layer204on the first semiconductor fin and the first gate structure. First mask layer204can include a silicon nitride layer or a silicon oxide layer. In an exemplary embodiment, the first gate structure203may include a first gate dielectric layer213on a surface on a portion of the first semiconductor fin202, e.g., a silicon oxide; a first gate electrode223on the gate dielectric layer213, e.g., a polysilicon gate electrode; and a first hard mask layer233on the first gate electrode223, e.g., silicon nitride.

Alternatively, the substrate structure may further include a spacer layer243between the first semiconductor fin202and the first mask layer204, and between the first gate203and the first mask layer204.

Further, the first gate structure203is not limited to the exemplary structures shown above. In other embodiments, the first gate structure203in the above structure can omit some layers, e.g., the first hard mask layer233, or may additionally comprise other layers, for example, may include a buffer layer (not shown) between a first gate electrode223and the first hard mask layer233.

InFIGS. 2A and 2B, a dashed box in the substrate structure illustrates an optional second semiconductor region221, for example, a PMOS region adjacent to the first semiconductor region211. In this embodiment, the substrate structure may further include: a second semiconductor fin205in the second semiconductor region221, a second gate electrode206, and a second source region207and a second drain region208. Here, as shown inFIG. 2A, the fins can be isolated by an isolation region209(such as shallow trench isolation region). In one embodiment, a second gate structure206may include a second gate dielectric layer216, a second gate electrode226, a second hard mask layer236, and offset spacers246on sidewalls of the second gate dielectric layer216, a second gate electrode226, and the second hard mask layer236. Further, the second gate structure206may also include a spacer layer256on the offset spacer246.

At step103in the method ofFIG. 1, a second mask layer301, e.g., a silicon nitride layer, is formed on the substrate structure301, as shown inFIGS. 3A and 3B.

Next, at step105, as shown inFIGS. 4A and 4B, the second mask layer301and the first mask layer204are etched to expose the part of the first semiconductor fin202not covered with the first gate structure203, and to expose an upper surface of the first gate structure203. In an embodiment, after the second mask layer301and the first mask layer204are etched, the remaining portions of the first mask layer204and second mask layer301can act as a spacer on the sidewalls of the first gate structure203.

Next, at step107, as shown inFIGS. 5A and 5B, first ion implantation is performed on the exposed part of the first semiconductor fin202, and impurities are introduced in a portion of the semiconductor fin202under the first gate structure203. After the first ion implantation, an annealing process may be performed to activate the implanted impurities. Preferably, the first implantation angle of ion implantation may be 0-30 degrees, more preferably 5-25 degrees, even more preferably, 10-15 degrees. Here, the injection angle is the angle between the ion implantation direction and the normal direction of the substrate. In some embodiments, preferably, the first ion implantation is a tilted ion implantation, i.e., the implantation direction is at an angle to the normal direction of the substrate. Thus, recesses can be made with reference toFIGS. 6A and 6B, and desired impurities can be introduced to at least part of the side of the recess, thereby further reducing the resistance of the structure to be formed.

In an embodiment, the substrate structure may further include lightly doped drain (LDD) under the first gate structure203(not shown). In this case, when performing a first ion implantation, impurities can be introduced into the LDD regions, thereby reducing the resistance of LDD regions. In some embodiments, the first ion implantation includes implanting phosphorus ions at an energy of 2-5 KeV with an implantation dose of 1×1014/cm2to 3×1015/cm2. The second ion implantation includes performing phosphorus ions implantation at an energy of 100 eV-2 KeV with an implantation dose of 1×1014/cm2to 3×1015/cm2.

Next, at step109, as shown inFIGS. 6A and 6B, the first semiconductor fin202is etched to remove at least a portion of the exposed portion of the first semiconductor fin202, thereby forming a first recess601and a second recess602. Preferably, the height of the exposed portion of the first portion of the semiconductor that is removed fin is less than 10 nm.

Next, at step111, as shown inFIGS. 7A and 7B, a first semiconductor material is epitaxially grown on the remaining portions of first semiconductor fin202(i.e., a first recess and a second recess) to form a first source region701and a first drain region702. In some embodiments, the first semiconductor material may be different from the first semiconductor fin material, e.g., a first semiconductor material can be SiC, and the first semiconductor fin material can be Si. In other embodiments, the first semiconductor material and the first semiconductor fin material may be the same. For example, both can be Si. Preferably, in-situ doping may be performed during the epitaxial growth of the first semiconductor material. For example, in-situ doping can be performed with phosphorus, and the phosphorus doping concentration is preferably 1×1019/cm3to 3×1021/cm3, more preferably 1×1021/cm3. By in-situ doping, more impurities can be introduced into the epitaxially grown first semiconductor material, thereby reducing the resistance of the source and drain regions.

As described above, a method of fabricating a semiconductor device according to some embodiments of the present disclosure is described.

Preferably, in order to further reduce the resistance of the source and drain regions, in an embodiment, after forming the first source region701and the first drain region702, the above method may further include a second ion implantation to the first source region701and the first drain region702as shown inFIGS. 8A and 8B. By the second ion implantation, it is possible to reduce the height of the Schottky contact barrier between the source region and the drain region after the subsequent formation of the metal silicide, thereby lowering the contact resistance between the metal silicide and the source region and the drain region. In one embodiment, the implantation energy of the first ion implant is greater than the implantation energy of the second ion implant. Preferably, the second ion implantation conditions may include: phosphorus ions, implantation energy of 100 eV-2 KeV with an implantation dose of 1×1014/cm2to 3×1015/cm2.

In this embodiment, the doping concentration of the source region and the drain region can be increased by two ion implantations in order to reduce the resistance of the source region and the drain region. The embodiment can also reduce the contact resistance between the subsequently formed metal silicides and the source region and the drain region.

Preferably, after the second ion implantation, the first source region701and first drain region702can also receive spike anneal and laser anneal. In one embodiment, in the spike annealing, the annealing temperature can range from 850° C. to 1050° C.; and the annealing temperature for the laser annealing can range from 1000° C. to 1200° C.

Thereafter, other steps of a standard integrated circuit manufacturing process can be performed, such as depositing an interlevel dielectric layer, performing chemical mechanical polishing, etc. These steps are not the focus of the present disclosure and will not be described in detail herein.

In the above process, the substrate structure as shown inFIGS. 2A and 2Bmay be formed in different ways. An exemplary implementation of forming the substrate structure will be given below.

First, as shown inFIGS. 9A and 9B, the initial substrate structure has a semiconductor substrate201including a first semiconductor region211and a second semiconductor region221, a first semiconductor fin202on the first semiconductor region211, a second semiconductor fin205on the second semiconductor region, and an isolation region209between each of the semiconductor fins. In an exemplary implementation, the step of providing an initial substrate structure may include providing an initial semiconductor substrate including a first semiconductor region and a second semiconductor region, such as a silicon substrate; etching the initial semiconductor substrate to form a first semiconductor fin on the first semiconductor region and a second semiconductor fin on the second semiconductor region; depositing an insulating material in a space between each of the semiconductor fins; and etching the insulating material to expose a portion of each of the semiconductor fins so as to form an isolation region between the semiconductor fins.

Then, as shown inFIGS. 10A and 10B, a gate dielectric material layer1001is formed on the initial substrate structure. A gate material layer1002is formed on the gate dielectric layer material1001. A patterned hard mask layer1003is formed on the gate material layer1002.

Next, as shown inFIGS. 11A and 11B, the patterned hard mask layer1003may be used as a mask to pattern gate material layer1002on the gate electrode and the gate dielectric material layer1001to form the first and second gate structures. Here, the first gate structure includes a first hard mask layer233, a first gate electrode223, and a first gate dielectric layer213. The second gate structure includes a second hard mask layer236, a second gate electrode226, and a second gate dielectric layer216. The first gate dielectric layer213and the second gate dielectric layer216are formed by gate dielectric material layer1001, The first gate electrode223and the second gate electrode226are formed by gate material layer1002. After the patterning step, the hard mask layer on the first gate electrode223is referred to as the first hard mask layer233, and the hard mask layer on the second gate electrode226is referred to as the second hard mask layer236.

Next, as shown inFIGS. 12A and 12B, an offset spacer layer1201, e.g., a silicon oxide layer, is deposited on the initial substrate after the patterning step.

Then, as shown inFIG. 13, a first barrier layer1301(e.g. photoresist) is deposited to cover the offset spacer layer1201in the second semiconductor region. An LDD implant is performed in the region not covered by the first barrier layer1301. Preferably, the first LDD implantation conditions may include: implanting ions of arsenic ion with an injection energy of 1-3 KeV, at an implantation dose of 1×1014/cm2to 1×1015/cm2.

Next, as shown inFIG. 14, a second barrier layer1401(e.g., photoresist) is deposited so as to cover the offset of the spacer layer1201over the first semiconductor region. Then, a second LDD implantation is performed in the region not covered by the second barrier layer1401. The second LDD implantation can include implantation of BF2+.

Next, as shown inFIGS. 15A and 15B, a mask layer1501is deposited on the offset spacer layer1201.

Thereafter, as shown inFIGS. 16A and 16B, mask layer1501and offset spacer1201on the second semiconductor region221are etched. Portions of mask layer1501and offset spacer1201on the sidewalls will remain as spacer layers, because of anisotropic etching. These spacer layers form offset spacer layer246and spacer layer256. Similarly, offset spacer layer246and spacer layer256are formed in the first semiconductor region211.

Next, inFIGS. 16A and 16B, an etching process is performed to remove at least a portion of the exposed portion of the second semiconductor fin structure, thereby forming a third recess and a fourth recess1601and1602.

Then, a second semiconductor material (e.g., the SiGe) is epitaxially grown on the remaining portions of the second semiconductor fin (i.e., the third recess1601and the fourth recessed1602) to form a second source region207and a second drain region208. After the epitaxial growth process, the substrate structure inFIGS. 2A and 2Bis formed.

Thus, a semiconductor manufacturing method and device structure have been described in detail. While the present invention is described herein with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Rather, the purpose of the illustrative embodiments is to make the spirit of the present invention be better understood by those skilled in the art. In order not to obscure the scope of the invention, many details of well-known processes and manufacturing techniques are omitted. Various modifications of the illustrative embodiments as well as other embodiments will be apparent to those of skill in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications. Furthermore, some of the features of the preferred embodiments of the present invention could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the invention, and not in limitation thereof.