This application claims priority from Korean Patent Application No. 10-2014-0109095 filed on Aug. 21, 2014 in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which in its entirety are herein incorporated by reference.
1. Field of the Inventive Concepts
The present inventive concepts relates to a method for fabricating a semiconductor device improving the process speed.
2. Description of the Related Art
In order to improve performance of a metal oxide semiconductor (MOS) transistor, conductivity of a channel region of the MOS transistor may be increased. For example, the charge carrier mobility may be increased by altering a lattice structure of the channel region, thereby increasing the conductivity of the channel region of the MOS transistor.
The lattice structure of the channel region may be altered by generating a stressor near the channel region. Accordingly, the charge carrier mobility may be increased. In detail, in order to generate the stressor, a stress memorization technique (SMT) may be employed. According to the SMT, an amorphized region is formed to be adjacent to the channel region of the MOS transistor, followed by annealing in a state in which a stress inducing layer is positioned on the MOS transistor, thereby recrystallizing the amorphized region. Since the amorphized region is recrystallized while being affected by the stress applied from the stress inducing layer, transformed crystals may be generated. Even if the stress inducing layer positioned on the MOS transistor is removed, the transformed crystals maintain their transformed states, so that the stress is memorized in the transformed crystals. As the result, the transformed crystals act as stressors, thereby affecting the lattice structure of the channel region and ultimately increasing the charge carrier mobility.
Meanwhile, when the SMT is applied to a fin type field effect transistor (FinFET) or a nanowire transistor, the process speed is considerably reduced, which is because a fin or a nanowire undergoes very slow recrystallization due to surface proximity.
The present inventive concepts provides a method for fabricating a semiconductor device improving the process speed.
According to an aspect of the present inventive concepts, there is provided a method for fabricating a semiconductor device, the method including forming a fin on a substrate, forming a gate electrode on the fin, first ion-implanting a first impurity to amorphize a region including portions of the fin positioned at opposite sides of the gate electrode, forming a stress inducing layer on the substrate and the fin, and annealing the substrate to recrystallize the amorphized region, wherein after the forming of the fin and before the annealing, the method further comprises second ion-implanting a second impurity different from the first impurity into the fin.
According to another aspect of the present inventive concepts, there is provided a method for fabricating a semiconductor device, the method including forming a fin on a substrate, first ion-implanting first electrically active impurities (EAIs) into the fin, forming a gate electrode on the fin, performing a pre-amorphization implantation (PAI) process to amorphize a region including portions of the fin positioned at opposite sides of the gate electrode, forming a stress inducing layer on the substrate and the fin, and annealing the substrate to recrystallize the amorphized region.
According to still another aspect of the present inventive concepts, there is provided a method for fabricating a semiconductor device, the method comprising forming a gate electrode on a substrate, performing a pre-amorphization implantation (PAI) process to amorphize portions of source/drain regions positioned at opposite sides of the gate electrode, forming a stress inducing layer on the substrate, and annealing the substrate to recrystallize the amorphized region, wherein before the annealing, ion-implanting boron (B) into at least portions of the source/drain regions.
The above and other features and advantages of the present inventive concepts will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings in which:
Advantages and features of the present inventive concepts and methods of accomplishing the same may be understood more readily by reference to the following detailed description of example embodiments and the accompanying drawings. The present inventive concepts may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the inventive concepts to those skilled in the art, and the present inventive concepts will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive concepts. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on”, “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present inventive concepts.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the 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. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Embodiments are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, these embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present inventive concepts.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present inventive concepts belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Hereinafter, a method for fabricating a semiconductor device according to a first embodiment of the present inventive concepts will be described with reference to
The method for fabricating the semiconductor device according to the first embodiment of the present inventive concepts may be a method for fabricating an NMOS transistor. Therefore, while a process for the method for fabricating the semiconductor device according to the first embodiment of the present inventive concepts is performed, a region other than an NMOS region (e.g., a PMOS region) may be covered by a mask.
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In detail, a mask pattern 103 is formed on the substrate 100, followed by etching, thereby forming the fin F1. The fin F1 may extend in a second direction Y1. A trench 121 is formed in proximity of the fin F1. The mask pattern 103 may be made of a material including at least one of silicon oxide, silicon nitride, and silicon oxynitride.
The substrate 100 may be bulk silicon or a silicon-on-insulator (SOI). Alternatively, the substrate 100 may be a silicon substrate, or a substrate made of other materials selected from the group consisting of, for example, germanium, silicon germanium, indium antimonide, lead telluride compound, indium arsenide, indium phosphide, gallium arsenide, and gallium antimonide, but aspects of the present inventive concepts are not limited thereto.
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Next, a top portion of the isolation layer 110 is recessed to expose a top portion of the fin F1. The recessing may include a selective etching process. The mask pattern 103 may be removed before the forming of the isolation layer 110 or after the recessing.
Alternatively, a portion of the fin F1 upwardly protruding from the isolation layer 110 may be formed by an epitaxial process. In detail, after the forming of the isolation layer 110, a portion of the fin F1 may be formed by an epitaxial process using a top surface of the fin F1 exposed by the isolation layer 110 as a seed, without being recessed.
Next, a first impurity, for example, electrically active impurities (EAIs) may be first ion-implanted into the fin F1 (310).
Here, the first impurity may include B, As, P, Sb, Si, Ge or combinations thereof. As will later be described, the first impurity may enhance the recrystallization speed in annealing (see
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The gate electrode 143 may be a dummy gate electrode and the gate insulation layer 141 may be a dummy gate insulation layer. That is to say, the gate electrode 143 and the gate insulation layer 141 may be removed in a subsequent process (see
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For example, the spacers 151 may be formed by forming an insulation layer on the resultant product having the gate electrode 143 and then performing an etch-back process. The spacers 151 may expose a top surface of the mask pattern 104 and the top surface of the fin F1. The spacers 151 may include silicon nitride or silicon oxynitride.
Next, a pre-amorphization implantation (PAI) process is performed to form an amorphized region 321. That is to say, portions of the fin F1 positioned at opposite sides of the gate electrode 143 may be amorphized. In detail, a second impurity is second ion-implanted using the gate electrode 143 and the spacers 151 as masks, thereby forming the amorphized region 321. At least a portion of the amorphized region 321 may be a potential region of a source/drain.
Here, the second impurity may be different from the first impurity. The second impurity may be Ge or Si. However, after the second impurity is second ion-implanted, lateral diffusion may occur. Therefore, the amorphized region 321 may extend to a portion of a channel region.
When the PAI process is performed with high ion-implantation energy of 35 KeV or greater, considerable portions of the channel region may be amorphized due to lateral diffusion. Therefore, in order to reduce or minimize the amorphization of the channel region due to the lateral diffusion during the PAI process, Ge or Si may be ion-implanted with ion-implantation energy in the range of, for example, 10 to 35 KeV.
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The buffer layer 330 and the stress inducing layer 340 may be deposited by, for example, atomic layer deposition (ALD) or chemical vapor deposition (CVD), but not limited thereto.
The buffer layer 330 may be conformally formed on the substrate 100, the fin F1 and the spacers 151. The buffer layer 330 may include silicon oxide considerably different from silicon nitride included in the stress inducing layer 340 in view of etching selectivity, but not limited thereto. Since the buffer layer 330 includes silicon oxide, it may be used as an etch stop layer when the stress inducing layer 340 is removed.
In addition, since the buffer layer 330 is formed to cover the substrate 100, and may mitigate or prevent the gate electrode 143 and the spacers 151 from being damaged when the stress inducing layer 340 is removed.
As described above, the semiconductor device according to the first embodiment of the present inventive concepts may be an NMOS transistor. Therefore, the stress inducing layer 340 may include a material capable of applying tensile stress to a channel region. The stress inducing layer 340 may include, for example, silicon nitride, but not limited thereto.
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In detail, the process shown in
Since the method for fabricating the semiconductor device according to the first embodiment of the present inventive concepts employs a stress memorization technique (SMT), the amorphized region 321 may be transformed by the stress inducing layer 340 to then be recrystallized. Therefore, even if the stress inducing layer 340 is removed in a subsequent process, the transformed state of the recrystallized region 361 may be maintained. Accordingly, the recrystallized region 361 may continuously apply tensile stress to the channel region, altering the lattice structure of the channel region, thereby increasing mobility of charge carriers and ultimately improving performance of the semiconductor device.
Since the SPE process is performed under the tensile stress induced by the stress inducing layer 340, crystals tend to grow at different rates according to the crystallographic directions. For example, during the recrystallization of the amorphized region 321, the crystal growth rate may be greater in a <100> crystallographic direction than in a <110> crystallographic direction.
In the method for fabricating the semiconductor device according to the first embodiment of the present inventive concepts, the crystal growth rate is increased by first ion-implanted electrically active impurities (EAIs). In detail, in a case where the first ion-implanted EAIs include boron (B), the crystal growth rate in the <100> crystallographic direction is increased approximately 20.8 times and the crystal growth rate in the <110> crystallographic direction is increased approximately 13.3 times, compared to a case where the first ion-implanting is not performed. In a case where the first ion-implanted EAIs include phosphorus (P), the crystal growth rate in the <100> crystallographic direction is increased approximately 8.0 times and the crystal growth rate in the <110> crystallographic direction is increased approximately 7.2 times, compared to a case where the first ion-implanting is not performed.
Therefore, the crystal growth rate in the <100> crystallographic direction relative to the crystal growth rate in the <110> crystallographic direction (that is, <100>/<110>) is increased approximately 1.56 times when the first ion-implanted EAIs include boron (B) (=20.8/13.3). In addition, the crystal growth rate in the <100> crystallographic direction relative to the crystal growth rate in the <110> crystallographic direction (that is, <100>/<110>) is increased approximately 1.11 times when the first ion-implanted EAIs include phosphorus (P) (=8.0/7.2). Consequently, the solid-phase epitaxy growth rate of a fin or a nanowire may be improved. Therefore, the process speed of the SMT can be improved.
Meanwhile, as described above, the crystal growth rate in the <100> crystallographic direction may be greater than the crystal growth rate in the <110> crystallographic direction. As a result, a point at which crystal growth pinches off can appear, thus creating a stacking fault (350). Here, since the crystal growth rate in the <100> crystallographic direction and the crystal growth rate in the <110> crystallographic direction are both increased, a problem of creation of stacking faults can be overcome.
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Next, the interlayer insulation layer 155 is planarized until a top surface of the gate electrode 143 is exposed. As a result, the mask pattern 104 may be removed and the top surface of the gate electrode 143 may be exposed.
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The gate insulation layer 145 may include a high-k material having a higher dielectric constant than the silicon oxide layer. For example, the gate insulation layer 145 may include HfO2, ZrO2 or Ta2O5. The gate insulation layer 145 may be substantially conformally formed along sidewalls and a bottom surface of the trench 123.
The metal gate electrode 147 may include metal layers MG1 and MG2. As shown, the metal gate electrode 147 may have two or more metal layers MG1 and MG2 stacked one on another. The first metal layer MG1 may function to adjust a work function, and the second metal layer MG2 may function to fill a space formed by the first metal layer MG1. For example, the first metal layer MG1 may include at least one of TiN, TaN, TiC, and TaC. In addition, the second metal layer MG2 may include W or Al. Alternatively, the metal gate electrode 147 may be made of a non-metal material, such as Si, or SiGe.
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The forming of the recess 125 may be performed using dry etching or a combination of wet etching and dry etching.
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In addition, the forming of the source/drain 161 may be performed using an epitaxial process. When necessary, during the epitaxial process, impurities may be in-situ doped. In addition, when necessary, the recess 125 may be filled with a metal, rather than a semiconductor material.
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That is to say, the ion-implantating of EAIs may be performed after the PAI process. The first ion-implanting of the EAIs has only to be performed before the recrystallizing.
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Here, the third impurity may be B, As, P, Sb, Si, Ge or combinations thereof. The third impurity may be different from the impurity used in the PAI process. The third impurity may improve the recrystallizing speed during the annealing (360) and may suppress creation of stacking faults.
In addition, the PAI process and the EAI ion implanting process may be performed at the same time. Alternatively, the EAI ion implanting process may be performed after the PAI process, and the PAI process may be performed after the EAI ion implanting process.
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Here, the third impurity may be B, As, P, Sb, Si, Ge or combinations thereof. The third impurity may be different from the impurity used in the PAI process. The third impurity may improve the recrystallizing speed during the annealing (360) and may suppress creation of stacking faults.
The PAI process and the EAI ion implanting process may be performed at the same time. Alternatively, the EAI ion implanting process may be performed after the PAI process, and the PAI process may be performed after the EAI ion implanting process.
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The electronic device 1400 may include a controller 1410, an input/output device (I/O) 1420, a memory 1430, and a wireless interface 1440. Here, the memory 1430 may include a semiconductor device according to various embodiments of the present inventive concepts. The controller 1410 may include a microprocessor, a digital signal processor, and a processor capable of performing functions similar to these components. The memory 1430 may be used to store commands processed by the controller 1410 (or user data). The wireless interface 1440 may be used to exchange data through a wireless data network. The wireless interface 1440 may include an antenna or a wired/wireless transceiver. For example, the electronic device 1400 may use a third generation communication system protocol, such as CDMA, GSM, NADC, E-TDMA, WCDMA, CDMA2000, or the like.
While the present inventive concepts has been particularly shown and described with reference to example embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present inventive concepts as defined by the following claims. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than the foregoing description to indicate the scope of the inventive concepts.
Number | Date | Country | Kind |
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10-2014-0109095 | Aug 2014 | KR | national |