The present invention relates generally to a semiconductor transistor device and a method of fabricating the same. More particularly, the present invention relates to a semiconductor transistor device using a solid state doping (SSD) technique to form a doped layer in the lower half of a fin structure and a method of fabricating the same.
In recent years, as the dimensions of key components continue to shrink, the development of planar field effect transistor elements has been faced with process limitations. In order to overcome process limitations, it has become a mainstream trend to replace planar transistor elements with non-planar field-effect transistor elements, such as fin field effect transistors (Fin FET) elements.
Because the three-dimensional structure of the fin field effect transistor element can increase the contact area between the gate electrode and the fin structure, the control of the gate electrode to the carrier channel region can be further increased, thereby reducing the drain induced barrier lowering (DIBL) effect and suppressing the short-channel effect (SCE).
Moreover, because the fin field effect transistor element has a wider channel width at the same gate electrode length, a double of the drain drive current can be obtained. Even the threshold voltage of the transistor element can be controlled by adjusting the work function of the gate electrode.
The integrated microelectronic device having a FinFET architecture may rely on solid-state diffusion sources where an impurity source film is formed adjacent to a sidewall of a portion of a sub-fin region proximate to substrate. Dopants are driven from the impurity source film(s) into the portions of the sub-fin region proximate to the source films.
However, there is still improvement required in the process design of the fin structure, such as the removal of the unnecessary dummy fins between active areas at post stage. Therefore, how to improve the prior process of fin field effect transistor and develop the process for post stage is an important issue today.
One objective of the present invention is to provide a process for removing dummy fins at post solid-state doping (SSD) stage.
To achieve the objective, the preferred embodiment of the present invention provides a method for fabricating a semiconductor device, which includes the steps of providing a substrate having a first region, a second region and a dummy region, forming a plurality of fins in the first region and the second region and a dummy fin in the dummy region, forming a first solid-state dopant source layer in the first region, forming a first insulating buffer layer on the first solid-state dopant source layer, forming a second solid-state dopant source layer in the second region and the dummy region, forming a second insulating buffer layer on the second solid-state dopant source layer and on the first insulating buffer layer, and performing an etch process to cut the fin in the dummy region.
The present invention also provides a semiconductor device resulted from the method provided above, which includes a substrate having a first region, a second region and a dummy region between the first region and the second region, a plurality of fins in the first region and the second region, at least one dummy fin in the dummy region, a first solid-state dopant source layer in the first region, a first insulating buffer layer on the first solid-state dopant source layer, a second solid-state dopant source layer in the second region and the dummy region, a second insulating buffer layer on the second solid-state dopant source layer, and a dielectric layer on the substrate, wherein a top surface of the dielectric layer, the second insulating buffer layer, the first insulating buffer layer, the first solid-state dopant source layer and the second solid-state dopant source layer is lower than a top surface of the fins, and a top surface of the dummy fin is lower than the top surface of the dielectric layer, the second insulating buffer layer, the first insulating buffer layer, the first solid-state dopant source layer and the second solid-state dopant source layer.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute apart of this specification. The drawings illustrate some of the embodiments and, together with the description, serve to explain their principles. In the drawings:
It should be noted that all the figures are diagrammatic. Relative dimensions and proportions of parts of the drawings have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in modified and different embodiments.
In the following detailed description of the invention, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
Before describing the preferred embodiment, the following description will be given for specific terms used throughout the specification. The term “etch” or “etching” is used herein to generally describe a fabrication process of patterning a material, such that at least a portion of the material remains after the etch is completed. For example, it should be understood that the process of etching silicon involves the steps of patterning a photoresist layer above the silicon, and then removing the areas of silicon no longer protected by the photoresist layer. As such, the areas of silicon protected by the photoresist layer would remain behind after the etch process is complete. However, in another example, etching may also refer to a process that does not use a photoresist layer, but still leaves behind at least a portion of the material after the etch process is complete.
The above description serves to distinguish the term “etching” from “removing.” When etching a material, at least a portion of the material remains behind after the process is completed. In contrast, when removing a material, substantially all of the material is removed in the process. However, in some embodiments, “removing” is considered to be a broad term that may incorporate etching.
The term “substrate,” “semiconductor substrate” or “wafer” as described throughout, is most commonly a silicon substrate or a silicon wafer. However, term “substrate” or “wafer” may also refer to any semiconductor material such as germanium, gallium arsenide, indium phosphide, and the like. In other embodiments, the term “substrate” or “wafer” may be non-conductive, such as a glass or sapphire wafer.
According to the embodiment of the invention, the top of each fin 102 may be optionally provided with a pad oxide layer (not shown), such as a silicon dioxide layer, and a hardmask layer (not shown), such as a silicon nitride hardmask layer. Further, an oxide layer (not shown) may be optionally formed on the fins, such as a silicon oxide layer formed by in-situ steam generation (ISSG), but is not limited thereto.
Next, as shown in
To be detailed, the first solid-state dopant source layer 108 and the first insulating buffer layer 110 may be formed first on the entire substrate 100, an etching mask (not shown), such as a photoresist, is then masked on the first region 100a without masking the second region 100b and the dummy region 100c. An etching process is then performed to remove the first solid-state dopant source layer 108 and the first insulating buffer layer 110 not covered by the etching mask from the second region 100b and the dummy region 100c, so that the first solid-state dopant source layer 108 and the first insulating buffer layer 110 are formed only covering the first region 100a. The etching mask is removed subsequently after the etching process.
Next, as shown in
To be detailed, the second solid-state dopant source layer 112 may be first formed on the entire substrate 100, an etching mask (not shown), such as a photoresist, is then masked on the second region 100b without masking the first region 100a. An etching process is then performed to remove the second solid-state dopant source layer 112 not covered by the etching mask in the first region 100a, to thereby expose the first insulating buffer layer 110 in the first region 100a, so that the second solid-state dopant source layer 112 is formed only in the second region 100b and the dummy region 100c. The etching mask is removed subsequently after the etching process.
As shown in
Next, as shown in
Furthermore, after the above planarization process, a thermal doping process is performed to drive dopants from the first solid-state dopant source layer 108 and the second solid-state dopant source layer 112 into the fins 102 in the first region 100a, the second region 100b and the dummy region 100c, respectively. In this way, the doped portions with different conductive type are formed respectively in the fins 102 in the first region 100a and the second region 100b, respectively. The doped portion may also be formed extending into the substrate 100 with a predetermined thickness in addition to the fins 102.
Subsequently, as shown in
Next, as shown in
After the etching mask 118 is formed, an anisotropic dry etching process is then performed to etch the fin 102 exposed from the opening 118a, so that the fin is cut to a level lower than the top surface of the dielectric layer 116 and forms a dummy fin 119, as shown in
The dummy fin 119 in this embodiment is provided with the second solid-state dopant source layer 112 and the second insulating buffer layer 114 at both sides, However, in other embodiment, the dummy fin 119 may be provided with the second solid-state dopant source layer 112 and the second insulating buffer layer 114 at one side and the first solid-state dopant source layer 108 and the second insulating buffer layer 110 at the other side, depending on the predetermined region of the first solid-state dopant source layer 108 and the second solid-state dopant source layer 112 in the forming process.
In another embodiment of the present invention, as shown in
In still another embodiment of the present invention, the cutting process may also recess the exposed second solid-state dopant source layer 112 and the second insulating buffer layer 114 to a level lower than the top surface of the dielectric layer 116. More specifically, the cutting process has different etching rates for the second solid-state dopant source layer 112 and the second insulating buffer layer 114, so that the top surface of the second solid-state dopant source layer 112 would higher than the top surface of the second insulating buffer layer 114 at both sides of the dummy fin 119 as shown in
In still another embodiment of the present invention, the cutting process may have quite larger etching rates for the second solid-state dopant source layer 112 and the second insulating buffer layer 114 rather than the fins 102, so that the second solid-state dopant source layer 112 and the second insulating buffer layer 114 would be completely removed by the cutting process at both sides of the dummy fin 119 to form two grooves 120 between the dummy fin 119 and the dielectric layer 116 as shown in
In still another embodiment of the present invention, as shown in
Next, as shown in
Finally, according to the embodiment of the invention as shown in
In other embodiment, as shown in
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Number | Date | Country | Kind |
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2017 1 0679485 | Aug 2017 | CN | national |
This application is a divisional application and claims the benefit of U.S. non-provisional application Ser. No. 15/691,717, which was filed on Aug. 30, 2017 and is incorporated herein by reference.
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Number | Date | Country | |
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20190109207 A1 | Apr 2019 | US |
Number | Date | Country | |
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Parent | 15691717 | Aug 2017 | US |
Child | 16212700 | US |