Embodiments of the present disclosure generally relate to methods for selective dielectric deposition using self-assembled monolayers.
Selective atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes can advantageously reduce the number of steps and cost involved in conventional lithography while keeping up with the pace of device dimension shrinkage. Selective silicon based dielectric deposition in a metal dielectric pattern is of high potential value in back-end of line (BEOL) applications. Some alternative selective silicon based dielectric deposition techniques that have emerged are template-controlled growth, holographic based lithography, and the like. However, none of these alternative techniques provide a complete solution due to limitations like throughput, scale, defect issues, etc.
Accordingly, the inventors have developed improved methods and apparatus for selective dielectric deposition using self-assembled monolayer as sacrificial and nucleation inhibition layer.
Methods for selective deposition using self-assembled monolayer (SAM) are provided herein. In some embodiments, a method of selectively depositing a low-k dielectric layer atop a substrate having an exposed silicon surface and an exposed silicon-containing surface, includes: (a) growing an organosilane based self-assembled monolayer atop the exposed silicon-containing surface, wherein the organosilane based self-assembled monolayer is thermally stable at a first temperature of greater than about 300 degrees Celsius; and (b) selectively depositing a low-k dielectric layer atop the exposed silicon surface of the substrate, wherein the organosilane based self-assembled monolayer inhibits deposition of the low-k dielectric layer atop the silicon-containing surface.
In some embodiments, a method of selectively depositing a layer atop a substrate having an exposed metal surface and an exposed silicon-containing surface, includes: (a) growing a first self-assembled monolayer atop the exposed metal surface; (b) growing a second self-assembled monolayer atop the exposed silicon-containing surface, wherein the second self-assembled monolayer is organosilane based; (c) heating the substrate to a temperature of about 200 to about 300 degrees Celsius to remove the first self-assembled monolayer from atop the exposed metal surface; (d) selectively depositing a layer atop the exposed metal surface, wherein the layer is a low-k dielectric layer or a metal layer; and (e) heating the substrate to a temperature of about 500 to about 1000 degrees Celsius to remove the second self-assembled monolayer from atop the exposed silicon-containing surface.
Other and further embodiments of the present disclosure are described below.
Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. The appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of the scope, for the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Methods for selective dielectric deposition using self-assembled monolayer (SAM) are provided herein. In some embodiments, the inventive methods described herein advantageously provide an innovative method of selective dielectric deposition or selective metal deposition using self-assembled monolayers. Self-assembled monolayers (SAM) can selectively grow on patterned substrate and enable selective deposition by inhibiting nucleation selectively.
The method 200 is performed on a substrate 300, as depicted in
The method 200 begins at 202 and as depicted in
Growing the organosilane based self-assembled monolayer 306 comprises exposing the substrate 300 to a solution comprising a liquid organosilane. Suitable organosilanes have long alkyl chains to form a compact, defect free, thermally stable, and chemically inert barrier which can be removed cleanly at a later stage. Suitable organosilanes have C-8 to C-30 chains, including all the corresponding homologues with C-8 to upward of C-30 chains. Exemplary suitable organosilanes include, but are not limited to, octadecyltrichlorosilane (ODTS), trimethoxy(octadecyl)silane (ODTMS), chloro(dimethyl)octadecylsilane (CDODS), or trichloro(1H, 1H, 2H, 2H-perfluorooctyl)silane (PFTS). One of the criteria listed above of choosing the organosilane molecule is the thermal stability of the self-assembled monolayer. Selecting a self-assembled monolayer that is thermally stable at the deposition temperature of the subsequently deposited dielectric layer avoids decomposition of the self-assembled monolayer 306 at the deposition temperature of the subsequently deposited dielectric layer. For example, the thermal stability of ODTS on silicon dioxide (SiO2) is at least up to 500 degree Celsius. Accordingly, an ODTS self-assembled monolayer will not decompose during the deposition of dielectric material such as silicon dioxide (SiO2) or silicon nitride (SiN) via an ALD process. Thus, the thermal stability of ODTS-SiO2 SAM expands the temperature compatibility limit.
The solution further comprises a solvent, such as toluene, hexane, cyclohexane, or diethylether. In some embodiments, the solution comprises the solvent having about 1 millimol to about 10 millimol of organosilane. The substrate 300 is dipped in the solution for about 2 to about 3 hours to form the self-assembled monolayer 306 atop the exposed silicon-containing surface 304. The organosilane molecules have a chemical affinity (i.e. are reactive and selective) to the oxide in a silicon oxide (SiO2) surface, or the nitride in a silicon nitride (SiN) surface or the oxide and nitride in a silicon oxynitride (SiON) surface. Thus, the self-assembled monolayer 306 will only form on the exposed silicon-containing surface 304 but not on the exposed silicon surface 302. The substrate 300 is rinsed with a solvent, for example a solvent listed above, after depositing the self-assembled monolayer 306 to remove any unabsorbed organosilane molecules.
In some embodiments, the exposed silicon surface 302 may have a native oxide layer formed atop the exposed silicon surface 302. In some embodiments, the native oxide layer is removed prior to depositing the self-assembled monolayer 306. In embodiments where a native oxide layer is to be removed from the substrate, a SICONI™ Pre-clean process may be performed in a suitable chamber, such as a process chamber that utilizes SICONI™ technology available from Applied Materials, Inc., of Santa Clara, Calif. In such embodiments, the substrate 300 may be exposed to a fluorine containing precursor and a hydrogen containing precursor in a two part dry chemical clean process. In some embodiments, the fluorine containing precursor may comprise nitrogen trifluoride (NF3), hydrogen fluoride (HF), diatomic fluorine (F2), monatomic fluorine (F) and fluorine-substituted hydrocarbons, combinations thereof, or the like. In some embodiments, the hydrogen containing precursors may comprise atomic hydrogen (H), diatomic hydrogen (H2), ammonia (NH3), hydrocarbons, incompletely halogen-substituted hydrocarbons, combinations thereof, or the like. In some embodiments, the first part in the two part process may comprise using a remote plasma source to generate an etchant species (e.g., ammonium fluoride (NHF4)) from the fluorine containing precursor (e.g., nitrogen trifluoride (NF3)) and the hydrogen containing precursor (e.g., ammonia (NH3)). By using a remote plasma source, damage to the substrate may be minimized. The etchant species are then introduced into the pre-clean chamber and condensed into a solid by-product on the substrate surface through a reaction with native oxide layer. An in-situ anneal may then be performed to decompose the by-product. The by-product then sublimates and may be removed from the substrate surface via a flow of gas and pumped out of the pre-clean chamber.
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The method 400 is performed on a substrate 500, as depicted in
The method begins at 402 and as depicted in
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The process chamber 102 has an inner volume 105 that may include a processing volume 104. The processing volume 104 may be defined, for example, between a substrate support 108 disposed within the process chamber 102 for supporting a substrate 110 thereupon during processing and one or more gas inlets, such as a showerhead 114 and/or nozzles provided at predetermined locations. In some embodiments, the substrate support 108 may include a mechanism that retains or supports the substrate 110 on the surface of the substrate support 108, such as an electrostatic chuck, a vacuum chuck, a substrate retaining clamp, or the like (not shown). In some embodiments, the substrate support 108 may include mechanisms for controlling the substrate temperature (such as heating and/or cooling devices, not shown) and/or for controlling the species flux and/or ion energy proximate the substrate surface.
For example, in some embodiments, the substrate support 108 may include an RF bias electrode 140. The RF bias electrode 140 may be coupled to one or more bias power sources (one bias power source 138 shown) through one or more respective matching networks (matching network 136 shown). The one or more bias power sources may be capable of producing up to 1200 W or RF energy at a frequency of about 2 MHz to about 60 MHz, such as at about 2 MHz, or about 13.56 MHz, or about 60 Mhz. In some embodiments, two bias power sources may be provided for coupling RF power through respective matching networks to the RF bias electrode 140 at respective frequencies of about 2 MHz and about 13.56 MHz. The at least one bias power source may provide either continuous or pulsed power. In some embodiments, the bias power source alternatively may be a DC or pulsed DC source.
The substrate 110 may enter the process chamber 102 via an opening 112 in a wall of the process chamber 102. The opening 112 may be selectively sealed via a slit valve 118, or other mechanism for selectively providing access to the interior of the chamber through the opening 112. The substrate support 108 may be coupled to a lift mechanism 134 that may control the position of the substrate support 108 between a lower position (as shown) suitable for transferring substrates into and out of the chamber via the opening 112 and a selectable upper position suitable for processing. The process position may be selected to maximize process uniformity for a particular process. When in at least one of the elevated processing positions, the substrate support 108 may be disposed above the opening 112 to provide a symmetrical processing region.
The one or more gas inlets (e.g., the showerhead 114) may be coupled to a gas supply 116 for providing one or more process gases through a mass flow controller 117 into the processing volume 104 of the process chamber 102. In addition, one or more valves 119 may be provided to control the flow of the one or more process gases. The mass flow controller 117 and one or more valves 119 may be used individually, or in conjunction to provide the process gases at predetermined flow rates at a constant flow rate, or pulsed (as described above).
Although a showerhead 114 is shown in
The apparatus 100 may utilize capacitively coupled RF energy for plasma processing. For example, the process chamber 102 may have a ceiling 142 made from dielectric materials and a showerhead 114 that is at least partially conductive to provide an RF electrode (or a separate RF electrode may be provided). The showerhead 114 (or other RF electrode) may be coupled to one or more RF power sources (one RF power source 148 shown) through one or more respective matching networks (matching network 146 shown). The one or more plasma sources may be capable of producing up to about 3,000 W, or in some embodiments, up to about 5,000 W, of RF energy at a frequency of about 2 MHz and/or about 13.56 MHz or a high frequency, such as 27 MHz and/or 60 MHz. The exhaust system 120 generally includes a pumping plenum 124 and one or more conduits that couple the pumping plenum 124 to the inner volume 105 (and generally, the processing volume 104) of the process chamber 102.
A vacuum pump 128 may be coupled to the pumping plenum 124 via a pumping port 126 for pumping out the exhaust gases from the process chamber via one or more exhaust ports (two exhaust ports 122 shown). The vacuum pump 128 may be fluidly coupled to an exhaust outlet 132 for routing the exhaust to appropriate exhaust handling equipment. A valve 130 (such as a gate valve, or the like) may be disposed in the pumping plenum 124 to facilitate control of the flow rate of the exhaust gases in combination with the operation of the vacuum pump 128. Although a z-motion gate valve is shown, any suitable, process compatible valve for controlling the flow of the exhaust may be utilized.
To facilitate control of the process chamber 102 as described above, the controller 150 may be any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory, or computer-readable medium, 156 of the CPU 152 may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits 154 are coupled to the CPU 152 for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like.
The inventive methods disclosed herein may generally be stored in the memory 156 as a software routine 158 that, when executed by the CPU 152, causes the process chamber 102 to perform processes of the present disclosure. The software routine 158 may also be stored and/or executed by a second CPU (not shown) that is remotely located from the hardware being controlled by the CPU 152. Some or all of the method of the present disclosure may also be performed in hardware. As such, the disclosure may be implemented in software and executed using a computer system, in hardware as, e.g., an application specific integrated circuit or other type of hardware implementation, or as a combination of software and hardware. The software routine 158 may be executed after the substrate 110 is positioned on the substrate support 108. The software routine 158, when executed by the CPU 152, transforms the general purpose computer into a specific purpose computer (controller) 150 that controls the chamber operation such that the methods disclosed herein are performed.
The disclosure may be practiced using other semiconductor substrate processing systems wherein the processing parameters may be adjusted to achieve acceptable characteristics by those skilled in the art by utilizing the teachings disclosed herein without departing from the spirit of the disclosure.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.
Number | Date | Country | Kind |
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553/DEL/2015 | Feb 2015 | IN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/US2016/019597 | 2/25/2016 | WO | 00 |