Patent Application
20190157213
The present disclosure relates to semiconductor structures and, more particularly, to a semiconductor structure with a substantially straight contact profile and methods of manufacture.
Semiconductor devices include many different wiring layers. These wiring layers are formed in interlevel dielectric material and may include wiring structures, interconnect contacts, passive devices and active devices. The interconnect contacts are provided in different wiring layers of the die to connect to the different structures, e.g., different wiring structures, etc.
In manufacturing the semiconductor devices, an adhesion layer is typically formed at a bottom surface of the interlevel dielectric material, e.g., bulk SiCOH materials, above a wiring structure. The adhesion layer, though, has a different etch rate than the interlevel dielectric material, resulting in a tapered via profile. In other words, as the etch rate is different for the interlevel dielectric material and the adhesion layer, these materials will etch at a different rate resulting in a tapered profile within the adhesion layer. The tapered via profile, in turn, leads to interconnect contacts with tapered profiles. This tapered profile of the interconnect contacts leads to electrical performance issues including void formation in the metal material, e.g., copper, as well as and time-dependent gate oxide breakdown (TDDB).
The etching of these different materials is also known to be difficult to control as it is not possible to measure the thickness of the adhesion layer, in line. And, different thicknesses of the adhesion layer will generate different tapered via profiles.
In an aspect of the disclosure, a structure comprises: a block material comprising an upper oxidized layer at an interface with an insulating material; and an interconnect contact structure with a substantially straight profile through the oxidized layer of the block material.
In an aspect of the disclosure, a structure comprises: a wiring layer formed in an insulator material; a block material comprising an upper surface composed of oxidized material; an interlevel dielectric material directly on the upper surface; and a contact extending to the wiring layer, through the block material, oxidized material and the interlevel dielectric material, the contact having a substantially straight profile within the oxidized material.
In an aspect of the disclosure, a method comprises: forming a blocking material over a wiring structure; oxidizing the blocking material to form an upper oxidized layer; forming an interlevel dielectric material over the oxidized layer; etching a via into the interlevel dielectric material, the oxidized layer and the blocking material to expose the wiring structure, the via having a substantially straight via profile through the oxidized layer; and forming a contact within the via, the contact having a substantially straight profile through the oxidized layer.
The present disclosure is described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present disclosure.
The present disclosure relates to semiconductor structures and, more particularly, to a semiconductor structure with a substantially straight contact profile and methods of manufacture. More specifically, the present disclosure provides a substantially straight or vertical interconnect contact profile within an oxidized film in a blocking layer, below an interlevel dielectric material. Advantageously, by using the oxidized film, the present disclosure provides a more controllable via etching process, resulting in improved electrical parametric values of the interconnect contact, e.g., reduction in voids and time-dependent gate oxide breakdown (TDDB).
In embodiments, an oxygen treatment is provided to an upper surface of a BLoK layer, e.g., low-k dielectric insulator material. This oxygen treatment will improve taper control, e.g., etching, at the interface between an interlevel dielectric material and the BLoK layer. That is, by providing the oxygen treatment an oxidized layer of the BLoK layer will have a similar etch rate as the interlevel dielectric layer. The resulting via profile will, in turn, have a straight or substantially straight profile at the interface between the two materials, e.g., substantially 90 degrees as measured relative to the horizontal dielectric surface, as the oxidized layer and the interlevel dielectric layer will have a similar etch rate. In addition, by implementing the processes described herein, it is possible to eliminate the adhesion layer formed at the bottom of the interlevel dielectric layer that typically causes a tapered via profile during the etching process.
The structure of the present disclosure can be manufactured in a number of ways using a number of different tools. In general, though, the methodologies and tools are used to form structures with dimensions in the micrometer and nanometer scale. The methodologies, i.e., technologies, employed to manufacture the structure of the present disclosure have been adopted from integrated circuit (IC) technology. For example, the structure can be built on wafers and are realized in films of material patterned by photolithographic processes on the top of a wafer. In particular, the fabrication of the structure uses three basic building blocks: (i) deposition of thin films of material on a substrate, (ii) applying a patterned mask on top of the films by photolithographic imaging, and (iii) etching the films selectively to the mask.
For example, to form the wiring structure 12, a resist formed over the insulator material 14 is exposed to energy (light) to form a pattern (opening). An etching process with a selective chemistry, e.g., reactive ion etching (RIE), will be used to form one or more trenches in the insulator material 14 through the openings of the resist. The resist can then be removed by a conventional oxygen ashing process or other known stripants. Following the resist removal, the conductive material can be deposited by any conventional deposition processes, e.g., electroplating processes. Any residual material on the surface of the insulator material 14 can be removed by conventional chemical mechanical polishing (CMP) processes.
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In embodiments, the block material 16 undergoes an oxygen treatment to form an oxidized layer 18. In embodiments, the oxidized layer 18 can be at an upper surface of the block material and, more specifically, can extend about 5 nm to about 25 nm, depending on the technology node; although other thicknesses are also provided herein. In more specific examples, the oxidized layer 18 can be about 20% to about 30% of the thickness of the block material 16. In one specific embodiment, the oxidized layer 18 can be about 5 nm for a 35 nm thick block material 16.
The oxygen treatment can be provided in an oxygen atmosphere. The oxygen atmosphere can be, e.g., O2, NO2 or CO2, in a carrier gas in a CVD chamber. For example, the oxygen treatment can be provided after the start of the deposition process using the same CVD chamber as the deposition process. For example, the oxidation treatment can be provided after the start of or at the end of the deposition process of the block material 16. In this way, the oxidation can be provided in situ. Alternatively, the oxygen treatment can be provided prior to the deposition interlevel dielectric material, e.g., oxygen pre-treatment before SiCOH deposition, in either an external tool or within the deposition chamber. As an example, the oxygen treatment can be provided using a remote plasma tool, after the deposition process. In embodiments, the oxygen treatment should not affect the underlying metal features, e.g., wiring structure 12.
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The method(s) as described above is used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.
The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
