Patent Application
20190189447
The present disclosure incorporates by reference for all purposes the US patent application entitled “INTEGRATED ATOMIC LAYER PASSIVATION IN TCP ETCH CHAMBER AND IN-SITU ETCH-ALP METHOD” by Zhou et al. filed on Aug. 4, 2017, U.S. application Ser. No. 15/669,871.
The present disclosure relates to the formation of semiconductor devices. More specifically, the disclosure relates to the formation of semiconductor devices requiring etching features.
During semiconductor wafer processing, an intermediate layer below a patterned organic mask may be etched. Double or multiple patterning may be used to multiply the number of patterns in an area of the mask to increase the density of the pattern.
To achieve the foregoing and in accordance with the purpose of the present disclosure, a method for in-situ patterning a stack having a patterned mask with mask features including sidewalls and tops is provided. A plurality of patterning cycles is provided in a plasma chamber wherein each patterning cycle comprises: at least one (1) cycle of depositing an atomic layer deposition (ALD) over the mask features to create an ALD layer, wherein the ALD layer includes sidewalls over the sidewalls of the mask features and top portions over the tops of the mask features, and selectively etching the top portions of the ALD layer with respect to the sidewalls of the ALD layer.
These and other features will be described in more detail below in the detailed description and in conjunction with the following figures.
The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:
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.
To facilitate understanding,
The system includes a bias RF generator 320, which can be defined from one or more generators. If multiple generators are provided, different frequencies can be used to achieve various tuning characteristics. A bias match 318 is coupled between the RF generators 320 and a conductive plate of the assembly that defines the chuck 316. The chuck 316 also includes electrostatic electrodes to enable the chucking and dechucking of the wafer. Broadly, a filter and a DC clamp power supply can be provided. Other control systems for lifting the wafer off of the chuck 316 can also be provided.
A first gas injector 304 provides two different channels to inject two separate streams of process gases or liquid precursor (in vapor form) to the chamber from the top of the chamber. It should be appreciated that multiple gas supplies may be provided for supplying different gases to the chamber for various types of operations, such as process operations on wafers, waferless auto-cleaning (WAC) operations, and other operations. A second gas injector 310 provides another gas stream that enters the chamber through the side instead of from the top.
Delivery systems 328 includes, in one embodiment, an etch gas delivery system 327 and a liquid delivery system 329. Manifolds 322 are 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 manifolds 322 are further optimized, in response to control from the controller 308, to perform atomic layer deposition (ALD). A vacuum pump 330 is connected to the plasma chamber 332 to enable vacuum pressure control and removal of gaseous byproducts from the chamber during operational plasma processing. A valve 326 is disposed between exhaust 324 and the vacuum pump 330 to control the amount of vacuum suction being applied to the chamber.
Information transferred via communications interface 414 may be in the form of signals such as electronic, electromagnetic, optical, or other signals capable of being received by communications interface 414, 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 processors 402 might 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 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 code transmitted by a computer data signal embodied in a carrier wave and representing a sequence of instructions that are executable by a processor.
In an example of an implementation of the embodiment, a stack is placed on a substrate support in a plasma chamber (step 104).
A plurality of patterning cycles is provided (step 108). Each patterning cycle comprises at least one cycle of conducting an ALD over the mask features to create an ALD layer (step 112) and a selective etching of the tops of the ALD layer (step 116).
In an embodiment of the ALD cycle, 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 has one of the following compositions: C6H19N3Si, C8H22N2Si, C9H23NO3Si, and C12H28O4Si. In this example, the providing of the precursor is plasmaless. The precursor has a silicon function group, which forms a monolayer on the structures, since the precursor does not attach to another precursor.
Once a number of ALD cycles are processed, a selective etch is provided that selectively etches the top portions 232 of the ALD layer 220 with respect to sidewalls 224 of the ALD layer 220 (step 116). Since in this embodiment, the top portions 232 of the ALD layer 220 are horizontal and the sidewalls 224 are vertical, the selective etch selectively etches horizontal layers at the top with respect to vertical layers. An example of an etch for providing a selective etch would be a fluorine based highly ion assisted etch.
The patterning cycles (step 108) is repeated a plurality of times repeating the ALD cycles (step 112) and the selective etch (step 116) a plurality of times.
The patterned mask 212 is selectively etched with respect to the ALD layer 220 (step 120). An example for selectively etching the patterned mask 212 with respect to the sidewalls of the ALD layer 220 uses oxygen based low ion plasma for etching.
An etch process is provided to etch the intermediate layer 208 with respect to the sidewalls 224 of the ALD layer 220.
This embodiment is able to provide etched features with double the density of the features compared to the original photoresist mask. The use of ALD and selective etching forms square features with vertical sidewalls, which reduce defects.
In different embodiments, after the patterned mask is selectively etched, patterning cycles may be used to form sidewalls on the remaining sidewalls out of a different material than the remaining sidewalls. In various embodiments, the patterned mask is a carbon containing mask, such as photoresist. In the above example, the precursor was a silicon containing polymer to bind to the patterned mask, to form the self limiting silicon containing monolayer. In this example, the silicon containing polymer is a polymer with a silicon functional group. In various embodiments, the precursor may be a liquid, a vapor of a liquid, or a gas. Such precursors are generally described as being in fluid form. The curing of the precursor forms the silicon containing monolayer into a silicon oxide monolayer. Subsequent layers would use the precursor to form a self limiting silicon containing monolayer over the silicon oxide containing sidewall, which is cured to add an additional monolayer of silicon oxide. In this example, the precursor is able to form a monolayer on different types of material, such as a silicon containing material or an organic material. In an embodiment, a silicon nitride ALD layer is formed over the silicon oxide deposition. Such a process may be used to double the pattern again, when the silicon oxide is selectively etched with respect to the silicon nitride. Because various embodiments provide vertical sidewalls with square tops, the feature detail is improved.
In various embodiments, a plurality of ALD cycles are performed before each selective etch. In more preferred embodiments, at least five (5) ALD cycles are performed before each selective etch. In more preferred embodiments, between five (5) and twenty (20) ALD cycles are performed before each selective etch. In various embodiments, at least five (5) patterning cycles are completed, so that at least five (5) selective etches are provided. In other embodiments, at least twenty (20) patterning cycles are completed. In other embodiments, at least one hundred (100) patterning cycles are completed. In some embodiments, between one (1) and thirty (30) patterning cycles are completed.
In various embodiments, the curing of the monolayer may be done by applying radio frequency (RF) power to the plasma chamber along with an oxygen gas to perform a plasma flash process (or O2 plasma cure), the plasma flash process being processed 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 O2 plasma cure converts the Si containing precursor into SiO2.
In various embodiments, different recipes may be used to selectively etch the top portions of the ALD layer with respect to sidewalls of the ALD layer. Spacer etch recipes may be used to accomplish this in different embodiments.
The above embodiments are performed in situ in a single 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, since the in situ process allows for a greater number of cycles, which allows for the improved feature shapes.
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.
