ELECTRICAL GATE-TO-SOURCE/DRAIN CONNECTION
20170062438 ยท 2017-03-02
Inventors
Cpc classification
H10D64/259
ELECTRICITY
H10D64/021
ELECTRICITY
International classification
H01L29/08
ELECTRICITY
H01L29/417
ELECTRICITY
H01L27/12
ELECTRICITY
H01L29/06
ELECTRICITY
H01L29/49
ELECTRICITY
H01L29/66
ELECTRICITY
Abstract
A method of manufacturing a semiconductor device is provided including forming a gate electrode layer over a semiconductor substrate, forming a sidewall spacer at a sidewall of the gate electrode layer, forming a raised source/drain region over the semiconductor substrate and adjacent to the sidewall spacer, removing a portion of the sidewall spacer, thereby exposing a portion of the sidewall of the gate electrode layer, and forming an electrically conductive layer electrically connecting the exposed portion of the sidewall of the gate electrode layer and the source/drain region.
Claims
1. A method of manufacturing a semiconductor device, comprising: forming a gate electrode layer over a semiconductor substrate; forming a sidewall spacer at a sidewall of said gate electrode layer; forming a raised source/drain region over said semiconductor substrate and adjacent to said sidewall spacer; removing a portion of said sidewall spacer, thereby exposing a portion of said sidewall of said gate electrode layer; and forming an electrically conductive layer electrically connecting said exposed portion of said sidewall of said gate electrode layer and said source/drain region.
2. The method of claim 1, further comprising forming a patterned mask layer over said gate electrode layer and said raised source/drain regions, said patterned mask layer exposing said portion of said sidewall spacer.
3. The method of claim 1, wherein forming said electrically conductive layer comprises performing silicidation of said gate electrode layer and said raised source/drain region.
4. The method of claim 1, wherein forming said electrically conductive layer comprises performing silicidation of said gate electrode layer and said raised source/drain region and further comprising forming a metal layer over said gate electrode layer including said exposed portion of said sidewall of said gate electrode layer, said raised source/drain regions and a remaining portion of said sidewall spacer and performing an anneal treatment of said metal layer in order to form a metal silicide layer.
5. The method of claim 1, wherein said electrically conductive layer is partly formed in said gate electrode layer and said source/drain region.
6. The method of claim 1, further comprising providing said semiconductor substrate by forming a buried oxide layer on a semiconductor bulk substrate and forming a semiconductor layer on said buried oxide layer.
7. The method of claim 1, further comprising forming an additional sidewall spacer at another sidewall of said gate electrode, forming another source/drain region and removing a portion of said other sidewall spacer, thereby exposing a portion of said other sidewall of said gate electrode layer and wherein said electrically conductive layer is formed to electrically contact said other source/drain region and said exposed portion of said other sidewall of said gate electrode layer.
8. A semiconductor device, comprising: a semiconductor substrate; a gate electrode layer formed over said semiconductor substrate; a sidewall spacer formed at a sidewall of said gate electrode layer covering only a first portion and exposing a second portion of said sidewall; a raised source/drain region adjacent to said sidewall spacer and formed over said semiconductor substrate; and an electrically conductive layer continuously formed partly on said exposed second portion of said sidewall of said gate electrode and said raised source/drain region.
9. The semiconductor device of claim 8, wherein said electrically conductive layer comprises a metal silicide.
10. The semiconductor device of claim 8, wherein said semiconductor substrate is an FDSOI substrate.
11. The semiconductor device of claim 8, further comprising: another sidewall spacer formed at another sidewall of said gate electrode layer covering only a third portion and exposing a fourth portion of said other sidewall; another raised source/drain region adjacent to said other sidewall spacer and formed over said semiconductor substrate; and wherein said electrically conductive layer is continuously formed partly on said exposed fourth portion of said other sidewall of said gate electrode and said other raised source/drain region.
12. An SRAM cell comprising a semiconductor device according to claim 8.
13. A method of manufacturing a semiconductor device, comprising: forming a gate electrode layer over a semiconductor substrate; forming a sidewall spacer at a sidewall of said gate electrode layer such that it covers a first portion of said sidewall and exposes a second portion of said sidewall; forming a raised source/drain region over said semiconductor substrate and adjacent to said sidewall spacer; and performing a silicidation process to obtain a silicided portion of said gate electrode layer, a silicided portion of said source/drain region and a silicided layer connecting said silicided portion of said gate electrode layer and said silicided portion of said source/drain region.
14. The method of claim 13, wherein performing said silicidation process comprises forming a metal layer over said gate electrode layer including said exposed second portion of said gate electrode layer and said source/drain region and performing an anneal treatment of said metal layer.
15. The method of claim 13, wherein forming said gate electrode layer comprises forming a metal gate and a polysilicon layer above said metal gate.
16. The method of claim 13, further comprising forming a high-k gate dielectric between said gate electrode layer and said semiconductor substrate.
17. The method of claim 13, further comprising forming an additional sidewall space at another sidewall of said gate electrode, forming another source/drain region and removing a portion of said other sidewall spacer, thereby exposing a portion of said other sidewall of said gate electrode layer and wherein said silicided layer is formed to electrically contact said other source/drain region and said exposed portion of said other sidewall of said gate electrode layer.
18. The method of claim 13, wherein said semiconductor substrate is an FDSOI substrate and further comprising forming a high-k gate dielectric between said gate electrode layer and a semiconductor layer of said FDSOI substrate that is formed on a buried oxide layer of said FDSOI substrate.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The disclosure may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
[0016]
[0017]
[0018]
[0019] While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION
[0020] Various illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
[0021] The following embodiments are described in sufficient detail to enable those skilled in the art to make use of the disclosure. It is to be understood that other embodiments would be evident, based on the present disclosure, and that system, structure, process or mechanical changes may be made without departing from the scope of the present disclosure. In the following description, numeral-specific details are given to provide a thorough understanding of the disclosure. However, it would be apparent that the embodiments of the disclosure may be practiced without the specific details. In order to avoid obscuring the present disclosure, some well-known circuits, system configurations, structure configurations and process steps are not disclosed in detail.
[0022] The present disclosure will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details which are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary or customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition shall be expressively set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
[0023] As will be readily apparent to those skilled in the art upon a complete reading of the present application, the present methods are applicable to a variety of technologies, e.g., NMOS, PMOS, CMOS, etc., and is readily applicable to a variety of devices, including, but not limited to, logic devices, SRAM devices, etc. Generally, manufacturing techniques and semiconductor devices in which N-channel transistors and/or P-channel transistors may be formed are described herein. The manufacturing techniques may be integrated in CMOS manufacturing processes. The techniques and technologies described herein can be utilized to fabricate MOS integrated circuit devices, including NMOS integrated circuit devices, PMOS integrated circuit devices, and CMOS integrated circuit devices. In particular, the process steps described herein are utilized in conjunction with any semiconductor device fabrication process that forms gate structures for integrated circuits, including both planar and non-planar integrated circuits. Although the term MOS properly refers to a device having a metal gate electrode and an oxide gate insulator, that term is used throughout to refer to any semiconductor device that includes a conductive gate electrode (whether metal or other conductive material) that is positioned over a gate insulator (whether oxide or other insulator) which, in turn, is positioned over a semiconductor substrate.
[0024] In principle, there are two well-known processing methods for forming a planar or 3D transistor with a high-k/metal gate (HK/MG) structure: (1) the so-called gate last or replacement gate technique; and (2) the so-called gate first technique. In general, using the gate first technique involves forming a stack of layers of material across the substrate, wherein the stack of materials includes a high-k gate insulation layer (i.e., a layer with a dielectric constant k higher than the one of SiO.sub.2), one or more metal layers, a layer of polysilicon and a protective cap layer, for example, silicon nitride. Thereafter, one or more etching processes are performed to pattern the stack of materials to thereby define the basic gate structures for the transistor devices. In the replacement gate technique, a so-called dummy or sacrificial gate structure is initially formed and remains in place as many process operations are performed to form the device, e.g., the formation of doped source/drain regions, performing an anneal process to repair damage to the substrate caused by the ion implantation processes and to activate the implanted dopant materials. At some stage of the process flow, the sacrificial gate structure is removed to define a gate cavity where the final HK/MG gate structure for the device is formed. The herein disclosed techniques can be applied to the gate first approach.
[0025] The present disclosure provides a method of manufacturing a semiconductor device including electrical connecting gates and source/drain regions of FETs. The FETs may be comprised in an SRAM device. An example of this method according to the present disclosure is illustrated in
[0026] A semiconductor layer 14 is formed on the buried oxide layer 13. The semiconductor layer 14 provides the channel region of the transistor device and may be comprised of any appropriate semiconductor material, such as silicon, silicon/germanium, silicon/carbon, other II-VI or III-V semiconductor compounds and the like. The semiconductor layer 14 may have a thickness suitable for forming a fully depleted field effect transistor, for example, a thickness in a range from about 5-8 nm. A gate electrode layer 15 is formed over the semiconductor layer 14. The gate electrode layer 15 may be formed on or over a gate dielectric layer (not shown in
[0027] Sidewall spacers 16, for example, comprising silicon dioxide and/or silicon nitride, are formed at sidewalls of the gate electrode layer 15. The sidewall spacers 16 may include a plurality of spacer layers. Adjacent to the sidewall spacers 16, raised source/drain regions 17 are formed. Formation of the raised source/drain regions 17 may include epitaxially growing a semiconductor material over the semiconductor layer 14 and appropriate doping of the same after or during the epitaxial growth.
[0028] An exemplary process sequence of forming the semiconductor device 10 described so far is illustrated in
[0029] On the side of the P-channel transistor 104, semiconductor layer 108 may have a selective silicon/germanium channel. The channel may have a thickness of less than 20 nm and more than 1 nm or a thickness of less than 10 nm and more than 5 nm. The selective silicon/germanium channel may be provided to adjust the threshold voltage of the P-channel transistor 104 in order to match the threshold voltage of the P-channel transistor 104 with the threshold voltage of the N-channel transistor 102.
[0030] A first insulating layer 112 and a second insulating layer 114 may be formed over he gate electrode structure and the substrate. The first and second insulating layers 112, 114 may be formed by, for instance, epitaxially growing or depositing respective layers. The first and/or the second insulating layers 112, 114 may be substantially uniformly formed over the semiconductor layer 108 and/or at least one gate electrode structure. The first insulating layer 112 may be comprised of silicon nitride (SiN). The first insulating layer 112 may have a thickness of substantially less than 10 nm or may have a thickness of substantially less than 5 nm or may have a thickness of substantially less than 1 nm or may substantially be a monolayer having a thickness of less than 1 nm. The second insulating layer 114 may comprise silicon dioxide (SiO.sub.2) and may have a thickness which is substantially greater than the thickness of the first insulating layer 112. The second insulating layer 114 may have a thickness which is substantially greater than 1 nm or which is substantially greater than 5 nm or which is substantially greater than 10 nm.
[0031] As indicated by the arrows, etching 140 may be performed in order to form sidewall spacers, thereby resulting in the semiconductor device 200 shown in
[0032] As depicted in
[0033]
[0034] Furthermore,
[0035] The N-channel transistor 302 may be exposed to a subsequent halo implantation step 344 by which halo regions 322 may be formed in the semiconductor layer 108 at the side of the N-channel transistor 302, as illustrated in
[0036] It is expressly noted that, in the context of FDSOI applications, source/drain extension regions and halo regions may not be provided in the above-described examples.
[0037] Although not shown in
[0038]
[0039] The semiconductor layer 420 may be formed over at least a portion of the exposed surface of the semiconductor layer 108 substrate at both sides of the gate electrode, The semiconductor layer has a beveled layer portion 422 which is beveled (from top to bottom) towards the gate electrode structure of the N-channel transistor 402 and the P-channel transistor 404 with regard to the surface of the semiconductor layer 108. Whereas the beveled layer portion 422 of the semiconductor layer 420 reduces possible parasitic capacitances which may arise due to portions of raised source/drain regions which are disposed adjacent gate electrode structures, it may alternatively be preferred to form a non-beveled semiconductor layer 420. For forming the beveled layer portion 422, an epitaxy technique may be performed which makes use of the effect that the speed of epitaxial growth depends on the orientation of the crystal surface on which material is to be grown. After a complete reading of the present application, a person skilled in the art will appreciate that growth of silicon on a (111) surface may be substantially suppressed. However, this does not pose any limitation on the present disclosure, and other techniques may be considered for forming beveled layer portions 422. The semiconductor layer 420 can be properly doped during the epitaxial growth or afterwards in order to form raised source/drain regions. The height of the semiconductor layer 420 and thereby the raised source/drain regions can properly be selected. For example, the height might be chosen similar to the one of the gate electrode layers 120 (compare the heights of the gate electrode layer 15 and the source/drain regions 17 of
[0040] The semiconductor device 100 shown in
[0041] As illustrated in
[0042] A silicide layer 20, for example, comprised of NiSi, may be formed in the raised source/drain regions 17 as well the gate electrode layer 15 after removal of the patterned mask layer 18, as illustrated in
[0043] The silicidation process is known to improve electrical contact resistance of the raised source/drain regions 17 and the gate electrode layer 15, However, as disclosed herein, the formation of the silicide layer 20 additionally results in contacting the gate electrode layer 15 and the source/drain region 17 as illustrated by the oval contour shown in
[0044] As a result, a method of manufacturing a semiconductor device is provided including electrically connecting a gate and a source/drain region of a FET without the need for the formation of a Carec. Printing of regular contacts only is needed rather than Carec printing. In particular, the overall contacting process may be performed by using one single contacting mask only. Contrary, in the art, at least two contacting masks, namely, one for regular contacts and one for Carecs, were needed. In the context of continuous RX manufacturing processes, no upsizing of the RX is needed that conventionally was necessary in order to provide for landing pads of the Carecs. The disclosed techniques can be used in the formation of logic parts of semiconductor devices and SRAMS, for example.
[0045] The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Note that the use of terms, such as first, second, third or fourth to describe various processes or structures in this specification and in the attached claims is only used as a shorthand reference to such steps/structures and does not necessarily imply that such steps/structures are performed/formed in that ordered sequence. Of course, depending upon the exact claim language, an ordered sequence of such processes may or may not be required. Accordingly, the protection sought herein is as set forth in the claims below.