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  Methods of forming materials comprising tungsten and nitrogen, and methods of forming capacitorsUSPTO Application #: 20060234465Title: Methods of forming materials comprising tungsten and nitrogen, and methods of forming capacitors Abstract: In one aspect, the invention includes a method of forming a material comprising tungsten and nitrogen, comprising: a) providing a substrate; b) depositing a layer comprising tungsten and nitrogen over the substrate; and c) in a separate step from the depositing, exposing the layer comprising tungsten and nitrogen to a nitrogen-containing plasma. In another aspect, the invention includes a method of forming a capacitor, comprising: a) forming a first electrical node; b) forming a dielectric layer over the first electrical node; c) forming a second electrical node; and d) providing a layer comprising tungsten and nitrogen between the dielectric layer and one of the electrical nodes, the providing comprising; i) depositing a layer comprising tungsten and nitrogen; and ii) in a separate step from the depositing, exposing the layer comprising tungsten and nitrogen to a nitrogen-containing plasma. (end of abstract)
Agent: Wells St. John P.s. - Spokane, WA, US Inventors: Vishnu K. Agarwal, Gurtej S. Sandhu USPTO Applicaton #: 20060234465 - Class: 438396000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Making Passive Device (e.g., Resistor, Capacitor, Etc.), Stacked Capacitor The Patent Description & Claims data below is from USPTO Patent Application 20060234465. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The invention pertains to methods of forming materials comprising tungsten and nitrogen, and in an exemplary application pertains to methods of forming capacitors. BACKGROUND OF THE INVENTION [0002] Tungsten nitride has properties which render it particularly suitable so for utilization in integrated circuitry. For instance, tungsten nitride is found to exhibit better or equivalent electrical properties when compared to such commonly utilized compositions as, for example, TiN. Further, tungsten nitride retains its good electrical properties after being subjected to relatively high temperature processing, such as a polysilicon anneal or borophosphosilicate glass (BPSG) reflow. [0003] Tungsten nitride materials can be formed by, for example, chemical vapor deposition processes, such as, for example, plasma enhanced chemical vapor deposition (PECVD). The tungsten nitride materials formed by such methods can have good step coverage over an underlying substrate and be continuous, particularly if formed at lower working ends of temperature and plasma power ranges. However, utilization of such tungsten nitride materials has been limited due to difficulties in working with the materials. Specifically, tungsten nitride can peel, and/or bubble, and/or crack when exposed to high temperature processing (such as, for example, the greater than 800.degree. C. processing associated with anneal steps). The peeling, cracking and bubbling lead to a non-continuous film. It would be desirable to develop methods of forming materials comprising tungsten nitride which overcome problems associated with tungsten nitride exposure to high temperature processing conditions. SUMMARY OF THE INVENTION [0004] In one aspect, the invention includes a method of forming a material comprising tungsten and nitrogen. A layer comprising tungsten and nitrogen is deposited over a substrate. Subsequently, and in a separate step from the depositing, the layer comprising tungsten and nitrogen is exposed to a nitrogen-containing plasma. [0005] In another aspect, the invention includes a method of forming a capacitor. A first electrical node is formed and a dielectric layer is formed over the first electrical node. A second electrical node is formed and separated from the first electrical node by the dielectric layer. A layer comprising tungsten and nitrogen is provided between the dielectric layer and one of the electrical nodes. The providing the layer comprising tungsten and nitrogen includes: a) depositing a layer comprising tungsten and nitrogen; and b) in a separate step from the depositing, exposing the layer comprising tungsten and nitrogen to a nitrogen-containing plasma. BRIEF DESCRIPTION OF THE DRAWINGS [0006] Preferred embodiments of the invention are described below with reference to the following accompanying drawings. [0007] FIG. 1 is a fragmentary, diagrammatic, cross-sectional view of a semiconductor wafer fragment at a preliminary step of a method of the present invention. [0008] FIG. 2 is a view of the FIG. 1 wafer fragment shown at a processing step subsequent to that of FIG. 1. [0009] FIG. 3 is a view of the FIG. 1 wafer fragment shown at a processing step subsequent to that of FIG. 2. [0010] FIG. 4 is a view of the FIG. 1 wafer fragment shown at a processing step subsequent to that of FIG. 4. [0011] FIG. 5 is a fragmentary, diagrammatic, cross-sectional view of a semiconductor wafer fragment at a preliminary step of a second embodiment method of the present invention. [0012] FIG. 6 is a view of the FIG. 5 wafer fragment shown at a processing step subsequent to that of FIG. 5. [0013] FIG. 7 is a view of the FIG. 5 wafer fragment shown at a processing step subsequent to that of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0014] This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws "to promote the progress of science and useful arts" (Article 1, Section 8). [0015] The invention encompasses methods of forming materials comprising tungsten and nitrogen. An exemplary method of the present invention is described with reference to a semiconductor wafer fragment 10 in FIGS. 1 and 2. Referring to FIG. 1, wafer fragment 10 comprises a substrate 12 and a layer 14 formed over substrate 12. Substrate 12 includes a step 16. Substrate 12 can comprise, for example, a conductive material, or an insulative material. Exemplary conductive materials include, for example, conductively doped polysilicon and metals, such as, for example, copper. Conductive materials of substrate 12 can be incorporated into, for example, interconnect lines. Exemplary insulative materials include, for example, silicon dioxide, tantalum pentoxide (Ta,.sub.2O.sub.5) and barium strontium titanate (BST). The insulative material can have a dielectric constant or "K" value which is greater than or equal to about 10. For instance, Ta.sub.2O.sub.5 comprises a "K" value of from about 10to about 25, and BST comprises a "K" value of from about 80to about 1,000 or greater. [0016] Layer 14 comprises tungsten and nitrogen, and can, for example, consist essentially of tungsten nitride. Such tungsten nitride can have the chemical formula WN.sub.x, wherein "x" is from 0.05 to 0.5. In one aspect, layer 14 is a tungsten nitride layer. Tungsten nitride layer 14 can be formed by, for example, chemical vapor deposition utilizing WF.sub.6 and N.sub.2 and H.sub.2 as precursors, with either He or Ar as a carrier gas. The deposition can be plasma enhanced, with a plasma power of from a about 50 watts to about 700 watts. A temperature of a substrate upon which deposition occurs can be from about 170.degree. C. to about 550.degree. C., and a pressure within the deposition chamber can be from about 500 mTorr to about 8 Torr. The described conditions are for deposition of tungsten nitride over a single semiconductor material wafer. [0017] Tungsten nitride layer 14 is preferably formed to a thickness of from about 30 .ANG. to about 2000 .ANG., and more preferably from about 50 .ANG. to about 500 .ANG.. An exemplary thickness of layer 14 is from about 150 .ANG. to about 500 .ANG.. The shown layer 14 has a number of defects. Specifically, voids (or cracks) 20 occur throughout layer 14. An additional defect is a bubble 22 formed within layer 14 at an interface of layer 14 and substrate 12. The above-described defects can occur either during deposition of layer 14, or during high temperature processing subsequent to the deposition. [0018] Referring to FIG. 2, layer 14 is exposed to a nitrogen-containing plasma in accordance with a method of the present invention. Such exposure removes at least some of defects 20 and 22. After the exposure, layer 14 forms a stable film over substrate 12, with the term "stable" indicating that layer 14 is resistant to formation of cracks, voids or bubbles during subsequent processing. [0019] The plasma to which layer 14 is exposed preferably comprises a nitrogen-containing compound that does not contain oxygen. Suitable compounds are, for example, N.sub.2 and NH.sub.3. Continue reading... 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