Patent Application
20220389580
Embodiments of the disclosure generally relate to methods for depositing gapfill materials by atomic layer deposition (ALD). In particular, embodiments of disclosure relate to gapfill methods which deposit material within features to enable fill of reentrant features without seams or voids.
Atomic layer deposition (ALD) produces conformal films. Accordingly, any use of ALD to fill substrate features with a re-entrant profile (i.e., an internal width greater than the opening width) will lead to void formation when the feature opening closes.
Various techniques have been proposed to limit film growth near feature openings in an effort to prevent premature closure and void formation. One such technique utilizes a carbon-based surface poisoning agent to slow film deposition on target surfaces. But these poisoning agents often deposit into the formed films and can cause increased impurities and adversely affect various film properties.
Accordingly, there is a need for non-conformal gapfill methods which enable fill of complex features without voids and without the use of poisoning agents.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.
Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways.
As used in this specification and the appended claims, the term “substrate” refers to a surface, or portion of a surface, upon which a process acts. It will also be understood by those skilled in the art that reference to a substrate can also refer to only a portion of the substrate, unless the context clearly indicates otherwise. Additionally, reference to depositing on a substrate can mean both a bare substrate and a substrate with one or more films or features deposited or formed thereon
A “substrate” as used herein, refers to any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. For example, a substrate surface on which processing can be performed include materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon doped silicon oxides, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor wafers. Substrates may be exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in the present disclosure, any of the film processing steps disclosed may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term “substrate surface” is intended to include such underlayer as the context indicates. Thus for example, where a film/layer or partial film/layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface.
According to one or more embodiments, the term “on”, with respect to a film or a layer of a film, includes the film or layer being directly on a surface, for example, a substrate surface, as well as there being one or more underlayers between the film or layer and the surface, for example the substrate surface. Thus, in one or more embodiments, the phrase “on the substrate surface” is intended to include one or more underlayers. In other embodiments, the phrase “directly on” refers to a layer or a film that is in contact with a surface, for example, a substrate surface, with no intervening layers. Thus, the phrase “a layer directly on the substrate surface” refers to a layer in direct contact with the substrate surface with no layers in between.
One or more embodiments of the disclosure are directed to ALD methods for non-conformal fill of substrate features. Some embodiments utilize a plasma treatment to de-activate portions of the substrate for subsequent ALD deposition cycles. Some embodiments of the disclosure provide methods of depositing a metal nitride film (e.g., titanium nitride (TiN) or silicon nitride (SiN)) in high aspect ratio (AR) structures with small dimensions. Some embodiments provide methods for filling reentrant features without any substantial void. Some embodiments provide methods which produce films of similar quality to traditional ALD methods.
Referring to
In some embodiments, the feature 110 is a reentrant feature. A reentrant feature is defined by having a portion of the feature which is wider than a portion closer to the substrate surface 102. As shown in
In some embodiments, the at least one feature has an aspect ratio (D/W) of greater than or equal to 3:1, 5:1, 10:1, 15:1, or 20:1.
In some embodiments, the first film forms a gapfill material within the at least one feature that is without any substantial void. In this regard a “substantial” void is greater than or equal to 1 nm in width. It is noted that in some embodiments, a seam (<1 nm in width) may still be present.
Referring to
In some embodiments, the first reactant comprises silicon. In some embodiments, the first reactant comprises or consists essentially of dichlorosilane or diiodosilane. In some embodiments, the first reactant comprises titanium. In some embodiments, the first reactant comprises or consists essentially of titanium tetrachloride (TiCl4).
As used in this regard, a reactant which “consists essentially of” a stated compound comprises at least 95%, at least 98%, at least 99% or at least 99.5% of the stated compound on a molar basis, excluding any inert, diluent, or carrier materials (e.g., gasses, solvents).
The method continues at 206 by exposing the substrate surface to a first plasma to react with the first reactive species to form a first film on the substrate surface and within the at least one feature. Operations 204 and 206 may be understood to be similar to a typical plasma ALD process to produce a single monolayer of the first film.
The first plasma is formed from a first plasma gas. In some embodiments, the first plasma gas comprises ammonia.
The method continues at 208 by exposing the substrate surface to a second plasma to deactivate portions of the first film near the top of and outside of the at least one feature.
The second plasma is formed from a second plasma gas. In some embodiments, the second plasma gas comprises one or more of nitrogen gas (N2) or argon. In some embodiments, the second plasma gas comprises 1-25% N2 in argon, 5-25% N2 in argon or 5-10% N2 in argon.
In some embodiments, the first plasma and the second plasma are generated in the same processing region. In some embodiments, the first plasma and the second plasma are generated without an intervening pause. In some embodiments, the first plasma gas is flowed with the second plasma gas to produce the first plasma and then the first plasma gas is ceased to provide the second plasma. In some embodiments, the first plasma and the second plasma share one or more attributes. For example, in some embodiments, the first plasma and the second plasma have a power in a range of 50 W to 5000 W or in a range of 500 W to 2500 W.
The method continues at 212 by determining if a desired or predetermined thickness of the first film has been formed. If it has, the method 200 continues to 214 for optional post processing. If not, the method 200 returns to 204 for repetition of operations 204, 206 and 208.
The method 200 may be performed at any suitable temperature and/or pressure. In some embodiments, the method is performed at a chamber pressure in a range of 0.5 Torr to 20 Torr, in a range of 0.5 Torr to 5 Torr or in a range of 0.5 Torr to 2 Torr.
The resulting deposition on the deactivated portions during the repeated cycle provides a lower growth rate and less film deposition than on the unaffected portions. Accordingly, in some embodiments, after repeated cycles, the thickness of the first film is greater at the bottom of than at the top of the at least one feature.
Referring to
Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.
Although the disclosure herein has been described with reference to particular embodiments, those skilled in the art will understand that the embodiments described are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, the present disclosure can include modifications and variations that are within the scope of the appended claims and their equivalents.
This application claims priority to U.S. Provisional Application No. 63/229,501, filed Aug. 4, 2021, and U.S. Provisional Application No. 63/208,499, filed Jun. 8, 2021, the entire disclosures of which are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63208499 | Jun 2021 | US | |
| 63229501 | Aug 2021 | US |
