The present invention is directed, in general, to a protective layer and, more specifically, to an interconnect structure including a silicon oxycarbonitride layer, a method of manufacture therefore, and an integrated circuit including the same.
The push to decrease the size of submicron multilevel metallized interconnections, such as lines, via, and trenches, and the desire to produce faster semiconductor devices, has resulted in a shift toward the use of copper for making electrical interconnections in ultra-large scale integration circuits. Copper interconnects, however, because of their oxidizing nature, often require a hermetic layer be formed thereover after each metallization level. The hermetic layer serves as a barrier for moisture or oxygen diffusion into the underlying copper layer during damascene processing.
There is currently a tradeoff in the industry that the hermetic layer be thick enough to provide the requisite amount of hermetic protection for the copper interconnects, but thin enough such that the effective dielectric constant (k-effective) of the hermetic layer remains small, and thus does not increase the capacitance and therefore RC delay. In the current technology nodes, such as the 90 nm nodes and 65 nm nodes, a single hermetic layer thickness is capable of accomplishing both the requisite amount of hermetic protection and the requisite k-effective. For example, for these nodes a 60 nm thick SiCN hermetic layer can still be used to provide both the requisite amount of hermetic protection and the required k-effective.
Unfortunately, as the next generation technology nodes are introduced, such as the 45 nm node, it does not appear that a single hermetic layer thickness will accomplish both the requisite amount of hermetic protection and the decreasing k-effective requirement. When this occurs, the industry will be forced to decide whether to accept limited hermeticity protection in lieu of decreased k-effective values, or vice versa. Neither scenario is appealing to the industry.
Accordingly, what is needed in the art is a new hermetic layer or process for manufacture therefore, that would accommodate both the requisite amount of hermetic protection and the decreasing k-effective requirement for future nodes.
To address the above-discussed deficiencies of the prior art, the present invention provides an interconnect structure, a method of manufacture therefore, and an integrated circuit including the same. In one embodiment of the present invention, the interconnect structure includes a conductive feature located in or over a dielectric layer, and a silicon oxycarbonitride layer located over the conductive feature. The method for manufacturing the integrated circuit, in another embodiment, includes providing and forming the aforementioned features.
As indicated above, another embodiment of the present invention is an integrated circuit. The integrated circuit may include: (1) transistor devices located over a substrate, (2) a dielectric layer located over the transistor devices, (3) a conductive feature located in or over the dielectric layer, and (4) a silicon oxycarbonitride layer located over the conductive feature.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.
The invention is best understood from the following detailed description when read with the accompanying FIGURES. It is emphasized that in accordance with the standard practice in the semiconductor industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The present invention is based, at least in part, on the recognition that the inclusion of nitrogen into certain conventional layers will allow for a novel hermetic layer that is capable of balancing the tradeoff between effective dielectric constant (k-effective) and hermeticity, which are both traditionally inversely related to the thickness of the hermetic layer. The present invention specifically recognizes that nitrogen might be added to a silicon oxycarbide layer, in various amounts, to result in a silicon oxycarbonitride layer that provides similar, if not improved, heremeticity with a much thinner layer. Accordingly, the silicon oxycarbonitride layer would have the desired k-effective because of its reduced thickness, but would also have the requisite hermeticity required to protect the interconnect structure from external environments.
A hermetic layer, as used herein, is any layer that may impede the diffusion of moisture or oxygen within a stack of layers. For instance, in a semiconductor device, the hermetic layer may be placed in such a position as to impede the diffusion of moisture or oxygen from an interlevel dielectric layer to an underlying copper layer, thereby inhibiting copper oxidation. The hermeticity of a given hermetic layer is a measurement of the ability of the hermetic layer to impede the diffusion of moisture or oxygen over time. One method for measuring a hermetic layer's hermeticity is to place the hermetic layer over a tensile dielectric material (e.g., TEOS or OSG) and measure the tensile dielectric material's stress as a function of time. As moisture or oxygen diffuses into the hermetic layer the diffusion will show up as stress change in the dielectric layer. This is one appropriate measurement technique of a material's hermeticity. Other known measurement techniques may also be used to measure a given hermetic layer's hermeticity.
Turning initially to
Positioned over the substrate 110 and/or the first conductive feature 120, in the embodiment of
Positioned over the dielectric barrier layer 130 may be a dielectric layer 140. The dielectric layer 140, in one exemplary embodiment, comprises a low dielectric constant (k) layer having an opening formed therein. While not limited to such, the dielectric layer 140 might comprise an organo-silicate glass (OSG) dielectric layer having a thickness ranging from about 50 nm to about 500 nm.
Located over the dielectric layer 140, and in this embodiment within the opening in the dielectric layer 140, is a second conductive feature 150. The second conductive feature 150 illustrated in
Uniquely positioned over the second conductive feature 150 is a silicon oxycarbonitride layer 160. The silicon oxycarbonitride layer 160, by its very nature, must contain more than trace amounts of oxygen or nitrogen therein. As the silicon oxycarbonitride layer 160 contains more than trace amount of oxygen and nitrogen, the oxygen and nitrogen must be intentionally added to the silicon oxycarbonitride layer 160. As an example, in one embodiment of the present invention, the silicon oxycarbonitride layer 160 includes at least about 2 atomic weight percent oxygen. In the same or another embodiment of the present invention, the silicon oxycarbonitride layer 160 contains at least about 2 atomic weight percent nitrogen. In yet another embodiment of the present invention, the silicon oxycarbonitride layer 160 contains from about 15 atomic weight percent to about 30 atomic weight percent oxygen and/or from about 8 atomic weight percent to about 30 atomic weight percent nitrogen. In addition to the oxygen and nitrogen amounts just given, another embodiment of the present invention has the silicon oxycarbonitride layer 160 including from about 30 atomic weight percent to about 50 atomic weight percent silicon and/or from about 15 atomic weight percent to about 45 atomic weight percent carbon. While various ranges for the amounts of silicon, oxygen, carbon and nitrogen have been given above, it should be clear to the skilled artisan that other conceivable amounts outside of these ranges may exist; thus, the present invention should not be limited to such ranges.
The embodiment discussed in the paragraph above leads one to believe that the concentration profile of the nitrogen in the silicon oxycarbonitride layer 160 is flat. While this does represent one embodiment of the present invention, another embodiment exists wherein the nitrogen in the silicon oxycarbonitride layer 160 has a graded profile. Without limitation, this embodiment might include a nitrogen graded profile having a greater amount of nitrogen at a surface of the silicon oxycarbonitride layer 160 proximate the second conductive feature 150 than a surface of the silicon oxycarbonitride layer 160 distal the second conductive feature 150.
The inclusion of the nitrogen into the silicon oxycarbonitride layer 160 allows the thickness of the silicon oxycarbonitride layer 160 to be less than the thickness of traditional hermetic layers, while maintaining the same hermeticity properties. For instance, in one embodiment the thickness of the silicon oxycarbonitride layer 160 ranges from about 3 nm to about 100 nm, while continuing to provide the requisite hermeticity properties. In another exemplary embodiment of the present invention, however, the thickness of the silicon oxycarbonitride layer 160 ranges from about 5 nm to about 50 nm, while continuing to provide the requisite hermeticity properties.
The silicon oxycarbonitride layer 160, in accordance with the principles of the present invention, may have a plurality of different functions. For example, in one embodiment the silicon oxycarbonitride layer 160 functions as a hermetic layer. In another embodiment, however, the silicon oxycarbonitride layer 160 functions as an etch stop. In yet another embodiment, the silicon oxycarbonitride layer 160 functions as both a hermetic layer and an etch stop.
Optionally located between the silicon oxycarbonitride layer 160 and the second conductive feature 150 may be an intermediate layer 170. The intermediate layer 170, when used, may be designed to prevent the oxygen containing silicon oxycarbonitride layer 160 from contacting the second conductive feature 150. This is particularly advantageous when the second conductive feature 150 contains copper, which will readily oxidize in the presence of oxygen.
The intermediate layer 170 may comprise many different materials. For instance, the intermediate layer 170 may comprise a silicon nitride layer, a silicon carbide layer, a silicon carbonitride layer, etc. It should further be noted that the intermediate layer 170 need not be a thick layer, but could also be an atomic layer or thin film. Accordingly, the intermediate layer 170 could be formed by chemically treating the second conductive feature 150 prior to forming the silicon oxycarbonitride layer 160.
The silicon oxycarbonitride layer 160 provides a number of benefits not available when using conventional hermetic layers. For instance, the silicon oxycarbonitride layer 160 allows a thinner hermetic layer to be used, thereby decreasing the k-effective of the dielectric stack, while improving the hermeticity. Additionally, hermeticity tests show minimal water diffusion over time compared to current dielectric layers used for advanced technology node interconnects. Furthermore, it is believed that the silicon oxycarbonitride layer 160 may be added to the traditional process flows, and in one embodiment into the hermetic layer deposition tool, with minimal impact.
Turning now to
As previously mentioned, located over or in the substrate is a conductive feature 220. The conductive feature 220 may also comprise a number of different features while remaining within the scope of the present invention. In one aspect of the invention, the conductive feature 220 is a conductive trace, runner or trench traversing along at least a portion of an interlevel dielectric layer. In another aspect, however, the conductive feature 220 is a transistor device level feature, such as a gate electrode or source/drain contact region. Other conductive features 220 may also exist.
The conductive feature 220 illustrated in
Optionally located over the substrate 210 and the conductive feature 220 may be a dielectric barrier layer 230. The dielectric barrier layer 230, in accordance with the principles of the present invention, may comprise silicon nitride, silicon carbide, silicon carbonitride or other similar materials, for example. Various different compositions and configurations for the dielectric barrier layer 230 may, nonetheless, exist.
Positioned over the substrate 210 and the conductive feature 220 in the embodiment of
Positioned over the dielectric layer 240 is a photoresist layer 250. The photoresist layer 250 illustrated in
Turning now to
Turning now to
The metal barrier/adhesion layer 410 may comprise similar types of materials as the barrier/adhesion layer 223, such as titanium, titanium nitride, a Ti/TiN stack, tantalum, tantalum nitride, or other barrier-like materials or mixtures of these materials that adhere well to copper, aluminum and/or the dielectric layer 240. Similarly, the blanket layer of conductive material 420 may comprise similar types of materials as the conductive plug 228. Therefore, in the embodiment of
Turning now to
Turning now to
The intermediate layer 610 may be formed using various different processes and to various different thicknesses. For instance, in one embodiment the intermediate layer is formed using a plasma enhanced chemical vapor deposition (PECVD) process to a thickness ranging from about 5 nm to about 50 nm. In an alternative embodiment, however, the intermediate layer 610 is formed using a chemical pretreatment applied to the conductive plug 520. In this embodiment, the intermediate layer 610 may only be atoms thick, and thus not be referred to as a layer at all. In conclusion, the intermediate layer 610 may be formed from any process, comprise any material, be any thickness, etc., as long as it accomplishes its purposes set-forth herein.
Turning now to
The silicon oxycarbonitride layer 710 may be formed using various different techniques. Nevertheless, in one embodiment of the invention the silicon oxycarbonitride layer 710 is formed using a PECVD technique. For example, the silicon oxycarbonitride layer 710 could be formed using gasses such as ammonia, helium, trimethyl silane, carbon dioxide and hydrogen. When forming the silicon oxycarbonitride layer 710 using these gasses, the ammonia flow rate might range from about 100 sccm to about 2000 sccm, the helium flow rate might range from about 100 sccm to about 2000 sccm, the trimethyl silane flow rate might range from about 40 sccm to about 500 sccm, the carbon dioxide flow rate might range from about 100 sccm to about 2000 sccm, and the hydrogen flow rate might range from about 100 sccm to about 2000 sccm. Other flow rates could nevertheless also be used. The PECVD technique might also use a deposition power ranging from about 100 Watts to about 500 Watts, and a temperature ranging from about 300° C. to about 400° C., among others.
The silicon oxycarbonitride layer 710 layer illustrated in
After completing the silicon oxycarbonitride layer 710 layer the manufacturing of the interconnect structure 200 might continue in a conventional manner. For example, the manufacturing might continue in a manner sufficient to provide a device similar to the completed interconnect structure 100 illustrated in
Referring now to
Although the present invention has been described in detail, those skilled in the art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.