Patent Application
20150011059
The present disclosure, relates, most generally to semiconductor devices and methods for forming semiconductor devices. More particularly, the present disclosure relates to methods and structures for metal gate semiconductor devices with high-k dielectric materials.
In today's rapidly advancing semiconductor manufacturing industry, it is of paramount importance to manufacture the most highly multi-functional and integrated semiconductor devices in the most efficient manner possible. An economy in the number of manufacturing operations used to form a device having a certain level of complexity and integration, is essential for minimizing manufacturing costs and maximizing productivity and throughput.
As device complexities and performance levels increase, high-k dielectric materials are increasingly being used as gate dielectrics for MOSFET (metal oxide semiconductor field effect transistor) devices. When a CMOS (complementary metal oxide semiconductor) device is formed using high-k dielectrics as the gate dielectric materials, different suitable metals must be used as the gate electrode for the PMOS and NMOS transistors. The use of different materials conventionally requires separate deposition and patterning operations. If a single patterning, i.e., etching operation is attempted to be used to etch two dissimilar materials in the same etching operation, at least one of the materials will likely be over- or under-etched and device functionality will suffer or the device will completely fail.
It would therefore be desirable to provide a single layer of material which can be patterned in one etching operation but which can also function as both the N-type metal and P-type metal utilized in conjunction high-k gate dielectric materials and NMOS and PMOS devices, respectively. Such aspect would enable the use of an economical number of processing operations to efficiently produce a CMOS device with N-metal and P-metal devices on the same substrate.
To address these and other needs and in view of its purposes, the present disclosure provides a method for forming PMOS and NMOS semiconductor devices using corresponding P-metal and N-metal materials formed from the same original layer of material and patterned simultaneously. P-metal and N-metal materials refer respectively to materials suitable for use in N-type and P-type semiconductor devices.
According to one aspect, provided is a method for forming a metal gate semiconductor device. The method includes forming an N-metal layer suitable for use as a gate electrode for N-metal semiconductor devices, over a surface of the substrate and converting portions of the N-metal layer to P-metal portions suitable for use as gate electrodes in P-metal semiconductor devices. The method further provides for forming N-metal semiconductor devices using unconverted sections of the N-metal layer and P-metal semiconductor devices using sections of the P-metal portions.
According to another aspect, provided is a CMOS device disposed over a substrate and including at least one NMOS semiconductor device comprising a portion of a layer of TaC and at least one PMOS semiconductor device comprising a further portion of the layer of TaC. The further portion includes at least one of O, C, N and Si as an impurity added therein.
According to yet another aspect, provided is a CMOS device disposed over a substrate and comprising at least one NMOS transistor having a gate formed of a portion of a layer of binary material having a work function of about 4.5 eV or less and at least one PMOS transistor having a gate formed of a further portion of the layer of binary material and having a work function of about 4.7 eV or greater. The further portion includes at least one of O, C, N and Si as an impurity added therein.
The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Like numerals denote like features throughout the specification and drawing.
The present disclosure provides for forming P-metal sections from an original N-metal layer and for forming both P-type semiconductor devices and N-type semiconductor devices from the original N-metal layer, the P-type semiconductor devices formed of material sections that are converted from N-metal materials to P-metal materials.
Layer 10 is formed over high-k dielectric layer 8 and includes upper surface 12. Layer 10 is advantageously an N-metal material suitable for use as a gate electrode in N-type semiconductor devices such as NMOS transistors i.e., layer 10 has a work function of about 4.3 or 4.4 electron volts, eV. Layer 10 may be formed of ruthenium, TaC, TaN, or various other suitable binary N-metal materials. Typical thicknesses for layer 10 may be about 1.0 to 2.0 nm, but other suitable thicknesses may be used in other exemplary embodiments. Each of the aspects and features shown in
Now turning to
Materials such as oxygen, O, nitrogen, N, carbon, C, and/or silicon, Si, may be implanted or otherwise introduced into the exposed sections of layer 10, i.e., the portions of layer 10 within P-metal sections 22. In one exemplary embodiment, ion implantation may be used. In another exemplary embodiment, gas cluster ion beam (GCIB) implantation techniques may be used and in yet another exemplary embodiment, diffusion may be used to drive the desired additives/impurities into the exposed portions of layer 10, with pattern sections 16 preventing the additive/impurity from being introduced into layer 10 within N-metal sections 18. The addition of additives changes the work function of layer 10 from about 4.3 or 4.4 electron volts or less as deposited, to about 4.7 or 4.8 electron volts or greater after conversion. Other work functions may be used in other exemplary embodiments but an aspect of the disclosure is that original layer 18 is now a layer that has portions with different (relatively high/relatively low) work functions, with the converted P-metal sections having an increased work function.
A conventional patterning and etching operation may be used to form discrete sections 46 and 48 shown in
The preceding merely illustrates the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes and to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.
This description of the exemplary embodiments is intended to be read in connection with the figures of the accompanying drawing, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the device be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.
Although the disclosure has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the disclosure, which may be made by those skilled in the art without departing from the scope and range of equivalents of the disclosure.
This application is a divisional of U.S. patent application Ser. No. 11/751,403, filed on May 21, 2007, the contents of which are hereby incorporated by reference as if set forth in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11751403 | May 2007 | US |
| Child | 14497920 | US |
