Patent ID: 12217955

DETAILED DESCRIPTION

The present disclosure will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some or all of these specific details. In other instances, well-known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present disclosure.

Low-temperature ALD (atomic layer deposition) of silicon oxide (SiO2) over patterned organic materials, photoresist or spin on carbon (SOC), is used to provide sidewall protection for etching features. Oxygen (O2) plasma is one method used for oxidation of silicon (Si) containing precursors. ALD provides uniform deposition. Such a uniform deposition is not always the most suitable for forming high aspect ratio features.

To facilitate understanding,FIG.1is a high level flow chart of an embodiment. A stack with a mask with mask features is placed on a substrate support in a plasma chamber (step104).FIG.2Ais a cross-sectional view of a stack200with a substrate205. The substrate205is disposed below an intermediate layer208. The intermediate layer208is disposed below a mask212. In this example, the mask212is a patterned organic mask, such as a photoresist mask, with mask features. One or more layers may be disposed between the intermediate layer208and the mask212. The intermediate layer208has been partially etched. One or more layers may be disposed between the intermediate layer208and the substrate205. The cyclical process described below or another process may be used to partially etch features216. The cyclical process described below is shown with partially etched features in order to more clearly illustrate the targeted deposition process. The figures are not drawn to scale in order to better illustrate various features. For example, in some embodiments height to width aspect ratios of features216may be at least 100 to 1. However, the features216are drawn much wider in order to better illustrate subsequently deposited layers.

A targeted deposition is provided (step108) to deposit a targeted deposition comprising at least one cycle of providing a precursor (step112) and a targeted curing of the precursor (step116). The precursor is provided to the features216(step112). In this embodiment, a liquid silicon containing precursor is vaporized and delivered in vapor form into a plasma chamber, to dose the features216to saturation, forming a layer of precursor over the features216. Once the features216are dosed with the precursor, the delivery of the precursor vapor is stopped. The precursor is then subjected to a targeted cure (step116). In an embodiment, the targeted cure (step116) is accomplished by subjecting the stack200to a targeted flash process. The targeted flash process provides a curing gas of 1000 standard cubic centimeters per minute (sccm) to 2000 sccm oxygen (O2) and provides a modification gas of 10 sccm to 25 sccm of octafluorocyclobutane (C4F8). In this example, the curing gas and modification gas are formed into a plasma by providing a radio frequency (RF) power of 2500 watts 13.56 megahertz (MHz). A pressure of 20 millitorrs (mTorr) to 100 mTorr is provided. The targeted flash is provided from between about 0.5 seconds and about 4 seconds. The targeted flash forms a silicon oxide monolayer on first portions of the features216. On second portions of the features, the formation of the targeted deposition is reduced or eliminated. Once the targeted flash operation is completed, the plasma chamber is purged. The cycle may then be repeated. In this embodiment, the providing the precursor (step112) and the targeted curing (step116) are sequential and do not overlap. In this example, a purge may be used to prevent the overlapping of the providing the precursor (step112) and the targeted curing (step116).

In an embodiment of the providing the precursor, any suitable liquid precursor capable of forming a conformal atomic layer can be used. By way of non-limiting example, the liquid precursor can have a composition of the general type C(x)H(y)N(z)O(a)Si(b). In some embodiments, the liquid precursor is a silicon containing polymer with a silicon functional group that may have one of the following compositions: 1-triaminosilylhexane (C6H19N3Si), bis(t-butylamino)silane (C8H22N2Si), 3-aminopropyltriethoxysilane (C9H23NO3Si), and tri-t-butoxysilanol (C12H28O4Si). In this example, the providing of the precursor is plasmaless. The precursor has a silicon function group. The silicon functional group forms a monolayer on the features216since the precursor does not attach to another precursor.

FIG.2Bis a cross-sectional view of the stack200after a plurality of cycles of the targeted deposition (step108). A targeted deposition is formed over sidewalls of the features216. In this example, the targeted deposition has thinner upper regions220, thicker middle regions224, and thinner bottom regions228. In an example, the targeted deposition has an upper region220with a thickness of about 1 to 2 nm, a middle region224with a thickness of about 2-4 nanometer (nm), and a bottom region228with a thickness of about 1 nm. In this example, the first portions are the middle region224and the second portions are the upper regions220and bottom regions228. The thickness of the targeted deposition is not drawn to scale, in order to better illustrate the targeted deposition.

The intermediate layer208is then etched with respect to the mask212(step120). In this example, the intermediate layer208is polysilicon.FIG.2Cis a cross-sectional view of the stack200after the intermediate layer208is selectively etched with respect to the mask212. In this example, the features216have been etched deeper and the targeted deposition has been etched away.

In this example, the targeted deposition (step108) and the intermediate layer etch (step120) are repeated (step124) at least one more cycle. The targeted deposition (step108) deposits another targeted deposition.FIG.2Dis a cross-sectional view of the stack200after a plurality of cycles of the targeted deposition (step108) deposits another targeted deposition with another thinner upper region232, another thicker middle region236, and another thinner bottom region240.

The process is continued and the cycles are repeated until the features216are completed.FIG.2Eis a cross-sectional view of the stack200after the etching of the features216is completed. Additional processes may be provided. For example, the mask212may be removed. Then, the stack200is removed from the plasma chamber (step128).

The targeted deposition provides a nonconformal deposition, where thicknesses at various locations of the etch feature may be selectively tailored. Various embodiments provide different controls for determining where the thicker regions and thinner regions of the targeted deposition are located. Process parameters may be used as controls, such as gas flow rates, pressure, side tuning gases, process times, temperature, and electrical bias. Various embodiments allow for the etching of high aspect ratio features. In the specification and claims, high aspect ratio features are defined as having a height to width aspect ratio of at least 100 to 1. More specifically, the high aspect ratio features have an aspect ratio of at least 200 to 1. Various embodiments may provide high aspect ratio features that are channels or holes. In some embodiments, the thickest part of the targeted deposition would be deposited over the weakest areas of features, such as joint areas for a punch process. Various embodiments may be used for punch processes, shallow trench isolation, and carbon mask opening. In other embodiments, the targeted deposition may be used in the formation of lower aspect ratio features.

By combining a dry etch chemistry with an ALD chemistry in a single step, the targeted deposition is provided. In various embodiments, the modification gas comprises a halogen containing gas. More specifically, the modification gas comprises fluorocarbons. In various embodiments, the modification gas comprises one or more of C4F8, hexafluorobutadiene (C4F6), chlorine (Cl2), hydrogen bromide (HBr), carbon tetrafluoride (CF4), fluoromethane (CH3F), or sulfur hexafluoride (SF6). In other embodiments, a metal oxide may be used for the targeted deposition. In such embodiments, a metal containing precursor forms a metal containing layer, such as a metal containing precursor monolayer. A curing gas and a modification gas are provided and formed into a plasma to provide a targeted metal oxide deposition. In other embodiments, silicon nitride or a metal nitride may be used for the targeted deposition. In other embodiments, silicon oxynitride or metal oxynitride may be used for the targeted deposition. For forming the nitride or oxynitride the precursor layer is nitrogenated. Therefore, in various embodiments, the curing of the precursor layer at least one of oxidizes or nitrogenates portions of the precursor layer.

Without being bound by theory, it is believed that by adding an etchant during the targeted curing and by using tuning parameters, the modification gas may be used to selectively etch targeted areas of the layer of precursor to reduce the deposition at the targeted areas.

In various embodiments, the targeted curing of the monolayer may be done by applying RF power to the plasma chamber along with a curing gas and modification gas to perform a plasma flash process (or oxygen (O2) plasma cure), the plasma flash process being performed for a period of time that is between about 0.2 second and about 4 seconds, and the RF power is applied at a power level that is between about 200 watts and about 3,000 watts. The O2plasma cure converts the Si-containing precursor into SiO2.

In other embodiments, the targeted deposition may deposit thicker deposition on the sidewalls at the bottom of the features216. In other embodiments, the targeted deposition has minimal deposition on horizontal surfaces. Various embodiments may provide a targeted deposition that does not deposit on the bottoms of the features216. Various embodiments may provide targeted depositions that do not deposit at the tops of the features216.

The above embodiments are performed in-situ in the same chamber, without moving the chuck or removing the stack from the chuck. Such embodiments provide faster and less expensive throughput. In addition, thinner layers may be applied for each cycle, since the in-situ process allows for a greater number of cycles. A greater number of cycles allows for improved feature shape.

FIG.3schematically illustrates an example of a plasma processing system300. The plasma processing system300may be used to perform the process of an embodiment. The system includes a plasma chamber332that includes a chamber body314, a chuck316, and a dielectric window306. The plasma chamber332includes a processing region with the dielectric window306disposed over the processing region. The chuck316can be an electrostatic chuck for supporting a substrate205and is disposed in the chamber below the processing region. A transformer coupled plasma (TCP) coil334is disposed over the dielectric window306and is connected to match circuitry302. The TCP coil334is an electrode to provide power through the dielectric window306. The match circuitry302is connected to a plasma RF generator321.

The system includes a bias RF generator320. The RF generator320may be defined as one or more generators. If multiple generators are provided, different frequencies can be used to achieve various tuning characteristics. A bias match318is coupled between the bias RF generators320and a conductive plate of the assembly that defines the chuck316. The chuck316also includes electrostatic electrodes to enable the chucking and dechucking of the wafer. Broadly, a filter and a direct current (DC) clamp power supply can be provided. Other control systems for lifting the wafer off of the chuck316can also be provided.

A first gas injector304provides two different channels to inject two separate streams of process gases or liquid precursor (in vapor form) into the plasma chamber332from the top of the plasma chamber332. It should be appreciated that multiple gas supplies may be provided for supplying different gases to the plasma chamber332for various types of operations, such as process operations on wafers, waferless auto-cleaning (WAC) operations, and other operations. A second gas injector310provides another gas stream that enters the plasma chamber332through the side instead of from the top.

Delivery systems328includes, in one embodiment, an etch gas delivery system327and a liquid delivery system329. Manifolds322are used for selecting, switching, and/or mixing outputs from the respective delivery systems. As will be described in more detail below, the etch gas delivery system is configured to output etchant gases that are optimized to etch one or more layers of materials of a substrate. The manifolds322are further optimized, in response to control from the controller308, to perform targeted deposition. A vacuum pump330is connected to the plasma chamber332to enable vacuum pressure control and removal of gaseous byproducts from the plasma chamber332during operational plasma processing. A valve326is disposed between exhaust324and the vacuum pump330to control the amount of vacuum suction being applied to the plasma chamber332.

A fluid source350may be used to deliver various fluids to the delivery system328. A fluid may be a gas or a liquid. In this embodiment, the fluid source350comprises a precursor fluid source354, a curing fluid source358, a modification fluid source362, and an etch fluid source366. In various embodiments, the fluid source350may be a single unit or more than one individual unit. For example, the precursor fluid source354may provide a liquid vapor and therefore be separate from the curing fluid source358, the modification fluid source362, and the etch fluid source366that provide gases.

FIG.4is a high level block diagram showing a computer system400, which is suitable for implementing the controller308used in an embodiment. The computer system may have many physical forms ranging from an integrated circuit, a printed circuit board, and a small handheld device up to a huge supercomputer. The computer system400includes one or more processors402, and further can include an electronic display device404(for displaying graphics, text, and other data), a main memory406(e.g., random access memory (RAM)), storage device408(e.g., hard disk drive), removable storage device410(e.g., optical disk drive), user interface devices412(e.g., keyboards, touch screens, keypads, mice or other pointing devices, etc.), and a communication interface414(e.g., wireless network interface). The communication interface414allows software and data to be transferred between the computer system400and external devices via a link. The system may also include a communications infrastructure416(e.g., a communications bus, cross-over bar, or network) to which the aforementioned devices/modules are connected.

Information transferred via communications interface414may be in the form of signals such as electronic, electromagnetic, optical, or other signals capable of being received by communications interface414, via a communication link that carries signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, a radio frequency link, and/or other communication channels. With such a communications interface, it is contemplated that the one or more processors402might receive information from a network, or might output information to the network in the course of performing the above-described method steps. Furthermore, method embodiments may execute solely upon the processors or may execute over a network such as the Internet in conjunction with remote processors that shares a portion of the processing.

The term “non-transient computer readable medium” is used generally to refer to media such as main memory, secondary memory, removable storage, and storage devices, such as hard disks, flash memory, disk drive memory, CD-ROM and other forms of persistent memory and shall not be construed to cover transitory subject matter, such as carrier waves or signals. Examples of computer readable code include machine code, such as produced by a compiler, and files containing higher level code that are executed by a computer using an interpreter. Computer readable media may also be computer readable code transmitted by a computer data signal embodied in a carrier wave and representing a sequence of instructions that are executable by a processor.

While this disclosure has been described in terms of several preferred embodiments, there are alterations, permutations, and various substitute equivalents, which fall within the scope of this disclosure. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present disclosure. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and various substitute equivalents as fall within the true spirit and scope of the present disclosure.