A method of etching exposed silicon-nitrogen-and-carbon-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-nitrogen-and-carbon-containing material. The plasma effluents react with the patterned heterogeneous structures to selectively remove silicon-nitrogen-and-carbon-containing material from the exposed silicon-nitrogen-and-carbon-containing material regions while very slowly removing selected other exposed materials. The silicon-nitrogen-and-carbon-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element controls the number of ionically-charged species that reach the substrate. The methods may be used to selectively remove silicon-nitrogen-and-carbon-containing material at a faster rate than exposed silicon oxide or exposed silicon nitride.

BACKGROUND OF THE INVENTION

Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. Producing patterned material on a substrate requires controlled methods for removal of exposed material. Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers, thinning layers or thinning lateral dimensions of features already present on the surface. Often it is desirable to have an etch process which etches one material faster than another helping e.g. a pattern transfer process proceed. Such an etch process is said to be selective to the first material. As a result of the diversity of materials, circuits and processes, etch processes have been developed with a selectivity towards a variety of materials. However, there are few options for selectively etching silicon carbon nitride.

Dry etch processes are often desirable for selectively removing material from semiconductor substrates. The desirability stems from the ability to gently remove material from miniature structures with minimal physical disturbance. Dry etch processes also allow the etch rate to be abruptly stopped by removing the gas phase reagents. Some dry-etch processes involve the exposure of a substrate to remote plasma by-products formed from one or more precursors. For example, remote plasma excitation of ammonia and nitrogen trifluoride enables silicon oxide to be selectively removed from a patterned substrate when the plasma effluents are flowed into the substrate processing region. Some selective remote plasma etch processes produce solid by-products which grow on the surface of the substrate as substrate material is removed. The solid by-products are subsequently removed via sublimation when the temperature of the substrate is raised. As a consequence of the production of solid by-products, Siconi™ etch process can deform delicate remaining structures formed in or nearby exposed regions of etched material.

A gas phase method of removing silicon-carbon-nitride selectively ideally without forming solid by-products.

BRIEF SUMMARY OF THE INVENTION

A method of etching exposed silicon-nitrogen-and-carbon-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-nitrogen-and-carbon-containing material. The plasma effluents react with the patterned heterogeneous structures to selectively remove silicon-nitrogen-and-carbon-containing material from the exposed silicon-nitrogen-and-carbon-containing material regions while very slowly removing selected other exposed materials. The silicon-nitrogen-and-carbon-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element controls the number of ionically-charged species that reach the substrate. The methods may be used to selectively remove silicon-nitrogen-and-carbon-containing material at a faster rate than exposed silicon oxide or exposed silicon nitride.

Embodiments of the invention include methods of etching patterned substrates in a substrate processing region of a substrate processing chamber. The patterned substrate has an exposed silicon-nitrogen-and-carbon-containing region. The method includes flowing each of a fluorine-containing precursor and an oxygen-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a plasma in the plasma region to produce plasma effluents. The methods further include etching the exposed silicon-nitrogen-and-carbon-containing region by flowing the plasma effluents into the substrate processing region through through-holes in a showerhead.

Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosed embodiments. The features and advantages of the disclosed embodiments may be realized and attained by means of the instrumentalities, combinations, and methods described in the specification.

DETAILED DESCRIPTION OF THE INVENTION

A method of etching exposed silicon-nitrogen-and-carbon-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-nitrogen-and-carbon-containing material. The plasma effluents react with the patterned heterogeneous structures to selectively remove silicon-nitrogen-and-carbon-containing material from the exposed silicon-nitrogen-and-carbon-containing material regions while very slowly removing selected other exposed materials. The silicon-nitrogen-and-carbon-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element controls the number of ionically-charged species that reach the substrate. The methods may be used to selectively remove silicon-nitrogen-and-carbon-containing material at a faster rate than exposed silicon oxide or exposed silicon nitride.

The ion suppression element functions to reduce or eliminate ionically charged species traveling from the plasma generation region to the substrate. Uncharged neutral and radical species may pass through the openings in the ion suppressor to react at the substrate. It should be noted that complete elimination of ionically charged species in the reaction region surrounding the substrate is not always the desired goal. In many instances, ionic species are required to reach the substrate in order to perform the etch and/or deposition process. In these instances, the ion suppressor helps control the concentration of ionic species in the reaction region at a level that assists the process.

In accordance with some embodiments of the invention, an ion suppressor as described in the exemplary equipment section may be used to provide radical and/or neutral species for selectively etching substrates. In one embodiment, for example, an ion suppressor is used to provide fluorine and oxygen containing plasma effluents to selectively etch silicon-nitrogen-and-carbon-containing material. Using the plasma effluents, an etch rate selectivity of silicon-nitrogen-and-carbon-containing material to silicon oxide of as high as about 4000:1 or more can be obtained. The ion suppressor may be used to provide a reactive gas having a higher concentration of radicals than ions. Because most of the charged particles of a plasma are filtered or removed by the ion suppressor, the substrate is typically not biased during the etch process. Such a process using radicals and other neutral species can reduce plasma damage compared to conventional plasma etch processes that include sputtering and bombardment. Embodiments of the present invention are also advantageous over conventional wet etch processes where surface tension of liquids can cause bending and peeling of small features.

In order to better understand and appreciate the invention, reference is now made toFIG. 1which is a flow chart of a silicon carbide selective etch process according to disclosed embodiments. Silicon carbon nitride is an example of a silicon-nitrogen-and-carbon-containing material. Prior to the first operation, a structure is formed in a patterned substrate. The structure possesses separate exposed regions of silicon carbon nitride and silicon oxide. The substrate is then delivered into a processing region (operation110).

A flow of nitrogen trifluoride is introduced into a plasma region separate from the processing region (operation120). Other sources of fluorine may be used to augment or replace the nitrogen trifluoride. In general, a fluorine-containing precursor may be flowed into the plasma region and the fluorine-containing precursor comprises at least one precursor selected from the group consisting of atomic fluorine, diatomic fluorine, bromine trifluoride, chlorine trifluoride, nitrogen trifluoride, hydrogen fluoride, sulfur hexafluoride and xenon difluoride. Even carbon containing precursors, such as carbon tetrafluoride, trifluoromethane, difluoromethane, fluoromethane and the like, can be added to the group already listed. The use of carbon-containing precursor generally requires an increased flow of the oxygen-containing precursors described herein. The separate plasma region may be referred to as a remote plasma region herein and may be within a distinct module from the processing chamber or a compartment within the processing chamber. Oxygen (O2) is also flowed into the plasma region (operation125) where it is simultaneously excited in a plasma along with the nitrogen trifluoride. Generally speaking, an oxygen-containing precursor may be flowed into the plasma region and the oxygen-containing precursor may comprise at least one precursor selected from O2, O3, N2O, NO, NO2, or the like.

Embodiments of the invention maintain a high atomic flow ratio of oxygen (O) to fluorine (F) in order achieve an etch rate of silicon-nitrogen-and-carbon-containing films which lends itself to use in manufacturing. Essentially the presence of oxygen helps to scavenge carbon from the silicon-nitrogen-and-carbon-containing film. In one embodiment, a gas flow ratio (O2:NF3) of between 1:1 and 4:1, or more generally an atomic flow ratio of between 2:3 and 8:3 (O:F), was found to achieve manufacturable etch rates of 50-100 Å/minute or more. The present invention may also utilize O:F ratios at or above or about 0.5:1, above or about 1:1 or above or about 2:1 in different embodiments. The O:F atomic Sow ratios may be below or about 10:1, below or about 6:1, below or about 5:1 or below or about 4:1 in embodiments of the invention. Upper limits on the atomic flow ratio may be combined with lower limits to create other embodiments. The higher ranges are typically used for fluorine-containing precursors which contain carbon. The more general atomic flow ratio, O:F, is calculated from the gas flow rate of each precursor gas and the total number of each atom per molecule. In the embodiment wherein one precursor is O2and another is NF3, each molecule of oxygen includes two oxygen atoms whereas each molecule of nitrogen trifluoride includes three fluorine atoms. Using mass flow controllers to maintain a gas flow ratio above, e.g. 1:1, will result in an atomic flow ratio of above 2:3. In another embodiment, the precursor gases include at least one gas which contains both oxygen and fluorine. The atomic flow rate of all contributions are included when calculating the atomic flow ratio.

The plasma effluents formed in the remote plasma region are then flowed into the substrate processing region (operation130). The patterned substrate is selectively etched (operation135) such that the exposed silicon carbon nitride is removed at a rate at least twenty times greater than the exposed silicon oxide. The reactive chemical species are removed from the substrate processing region and then the substrate is removed from the processing region (operation145). The flow of oxygen (O2) into the plasma and resulting flow of oxygen-containing excited species into the substrate processing region enables the fluorine-containing excited species in the plasma effluents to remove the silicon carbon nitride. The flow of oxygen-containing excited species into the substrate processing region has little effect on the exposed regions of silicon oxide so the fluorine-containing excited species are substantially unable to etch the silicon oxide regions. The substrate processing region is plasma-free during the etching operation in order ten ensure high etch selectivity of the silicon-nitrogen-and-carbon-containing layer.

Using the oxygen-containing precursor increases the etch rate of the silicon carbon nitride with minimal impact on an etch rate of the silicon oxide. The fluorine-containing precursor and/or the oxygen-containing precursor may further include one or more relatively inert gases such as He, N2, Ar, or the like. The inert gas can be used to improve plasma stability. Flow rates and ratios of the different gases may be used to control etch rates and etch selectivity. In an embodiment the fluorine-containing gas includes NF3at a flow rate of between about 5 sccm and 300 sccm, O2at a flow rate of between about 5 sccm and 1500 sccm, He at a flow rate of between about 0 sccm and 3000 sccm, and Ar at a flow rate of between about 0 sccm and 3000 sccm. One of ordinary skill in the art would recognize that other gases and/or flows may be used depending on a number of factors including processing chamber configuration, substrate size, geometry and layout of features being etched, and the like. Some hydrogen-containing precursors may also be combined with the other precursors or flowed separately into the plasma region, however, the concentration should be kept low. Hydrogen may interact with the fluorine-containing precursor in the plasma to form precursors which remove silicon oxide by forming solid residue by-products on the oxide surface. This reaction reduces the selectivity of the exposed silicon carbon nitride regions as compared with exposed silicon oxide regions. Though some hydrogen may be useful to introduce in some embodiments, there may also be no or essentially no flow of hydrogen-containing precursors into the plasma region during the etch process in disclosed embodiments. The fluorine-containing precursor and the plasma effluents may be essentially devoid of hydrogen in embodiments of the invention.

The method also includes applying energy to the fluorine-containing precursor and the oxygen-containing precursor while they are in the remote plasma region to generate the plasma effluents. As would be appreciated by one of ordinary skill in the art, the plasma may include a number of charged and neutral species including radicals and ions. The plasma may be generated using known techniques (e.g., RF, capacitively coupled, inductively coupled, and the like). In an embodiment, the energy is applied using a capacitively-coupled plasma unit at a source power of between about 10 watts and 2000 watts and a pressure of between about 0.2 Torr and 30 Torr. The capacitively-coupled plasma unit may be disposed remote from a gas reaction region of the processing chamber. For example, the capacitively-coupled plasma unit and the plasma generation region may be separated from the gas reaction region by an ion suppressor.

Without wishing to bind the coverage of the claims to theoretical mechanisms which may or may not be entirely correct, some discussion of possible mechanisms may prove beneficial. Radical-fluorine precursors and radical-oxygen precursors are concurrently produced by delivering a fluorine-containing precursor and an oxygen-containing precursor into the remote plasma region. Applicants suppose that a concentration of radical-fluorine fragments, fluorine ions and atoms are produced and delivered into the substrate processing region. Applicants further suppose that radical-oxygen species are concurrently delivered to the substrate processing region. The radical-oxygen species may react with carbon in the near surface region to create a silicon-rich region near the exposed surface of the silicon carbon nitride regions. Volatile species which may be created during this reaction may include carbon dioxide (CO2) which can then be pumped away through an exhaust system fluidly coupled to the substrate processing region. The silicon-rich near surface region of the silicon carbon nitride can be etched by the radical-fluorine precursors which are concurrently available within the substrate processing region. The silicon oxide regions are essentially unaffected by the radical-oxygen. Radical-fluorine precursors are highly selective towards silicon and leave silicon oxide essentially unetched. As a consequence, the etching methods outlined herein achieve selectivity toward silicon-nitrogen-and-carbon-containing material. Generally speaking, the selectivity of the etching methods presented herein may possess selectivities (silicon-nitrogen-and-carbon-containing material:silicon oxide) greater than or about 50:1, greater than or about 100:1, greater than or about 150:1 or greater than or about 250:1. The selectivity, the non-local plasma, the controlled ionic concentration and the lack of solid byproducts, each make these etch processes well suited for removing or trimming delicate silicon-nitrogen-and-carbon-containing material structures with little deformation and while removing little or no silicon oxide. These selectivities also apply generally to silicon-nitrogen-and-carbon-containing material which will be described shortly.

In addition to or instead of exposed silicon oxide regions, there may be regions of exposed silicon nitride on the patterned substrate during the etching operation herein. The selectivity of the etching operation (exposed silicon-nitrogen-and-carbon-containing region:exposed silicon nitride region) may be greater than or about 2:1, greater than or about 3:1 or greater than or about 4:1 in embodiments of the invention. Silicon carbide and silicon carbon nitride may etch at more similar rates using the etching processes disclosed herein, whereas silicon nitride and silicon are more slowly etched as quantified above.

The temperature of the substrate may be between about −30° C. and about 150° C. in general. The etch rate has been found to be higher for the lower temperatures within this range. In embodiments, the temperature of the substrate during the etches described herein may be about 0° C. or more, about 5° C. or more or about 10° C. or more. The substrate temperatures may be less than or about 50° C., less than or about 30° C., less than or about 20° C., less than or about 15° C. or less than or about 10° C. in different embodiments. The data further show an increase in etch rate as a function of process pressure. The pressure within the substrate processing region is below or about 50 Torr, below or about 30 Torr, below or about 20 Torr, below or about 10 Torr or below or about 5 Torr. The pressure may be above or about 0.1 Torr, above or about 0.2 Torr, above or about 0.5 Torr or above or about 1 Torr in embodiments of the invention. Any of the upper limits on temperature or pressure may be combined with lower limits to form additional embodiments. Generally speaking, the processes described herein may be used to etch films which contain silicon and carbon (and not just silicon carbide). The remote plasma etch processes may remove silicon-nitrogen-and-carbon-containing material which includes an atomic concentration of about 30% or more silicon. The atomic concentration of carbon in the silicon-nitrogen-and-carbon-containing material may be greater than or about 10%, greater than or about 15% or greater than or about 20% in embodiments of the invention. Analogously, the atomic concentration of nitrogen in the silicon-nitrogen-and-carbon-containing material may be greater than or about 10%, greater than or about 15% or greater than or about 20% in embodiments of the invention. The silicon-nitrogen-and-carbon-containing material may also consist only of silicon, nitrogen and carbon, outside of impurities and dopants. Of course, the silicon-nitrogen-and-carbon-containing material may be silicon carbon nitride in embodiments of the invention.

Additional process parameters are disclosed in the course of describing an exemplary processing chamber and system.

Exemplary Processing System

Processing chambers that may implement embodiments of the present invention may be included within processing platforms such as the CENTURA® and PRODUCER® systems, available from Applied Materials, Inc. of Santa Clara, Calif. Examples of substrate processing chambers that can be used with exemplary methods of the invention may include those shown and described in co-assigned U.S. Provisional Patent App. No. 60/803,499 to Lubomirsky et al, filed May 30, 2006, and titled “PROCESS CHAMBER FOR DIELECTRIC GAPFILL,” the entire contents of which is herein incorporated by reference for all purposes. Additional exemplary systems may include those shown and described in U.S. Pat. Nos. 6,387,207 and 6,830,624, which are also incorporated herein by reference for all purposes.

FIG. 2Ais a substrate processing chamber1001according to disclosed embodiments. A remote plasma system1010may process the fluorine-containing precursor which then travels through a gas inlet assembly1011. Two distinct gas supply channels are visible within the gas inlet assembly1011. A first channel1012carries a gas that passes through the remote plasma system1010(RPS), while a second channel1013bypasses the remote plasma system1010. Either channel may be used for the fluorine-containing precursor, in embodiments. On the other hand, the first channel1012may be used for the process gas and the second channel1013may be used for a treatment gas. The lid (or conductive top portion)1021and a perforated partition1053are shown with an insulating ring1024in between, which allows an AC potential to be applied to the lid1021relative to perforated partition1053. The AC potential strikes a plasma in chamber plasma region1020. The process gas may travel through first channel1012into chamber plasma region1020and may be excited by a plasma in chamber plasma region1020alone or in combination with remote plasma system1010. If the process gas (the fluorine-containing precursor) flows through second channel1013, then only the chamber plasma region1020is used for excitation. The combination of chamber plasma region1020and/or remote plasma system1010may be referred to as a remote plasma system herein. The perforated partition (also referred to as a showerhead)1053separates chamber plasma region1020from a substrate processing region1070beneath showerhead1053. Showerhead1053allows a plasma present in chamber plasma region1020to avoid directly exciting gases in substrate processing region1070, while still allowing excited species to travel from chamber plasma region1020into substrate processing region1070.

Showerhead1053is positioned between chamber plasma region1020and substrate processing region1070and allows plasma effluents (excited derivatives of precursors or other gases) created within remote plasma system1010and/or chamber plasma region1020to pass through a plurality of through-holes1056that traverse the thickness of the plate. The showerhead1053also has one or more hollow volumes1051which can be filled with a precursor in the form of a vapor or gas and pass through small holes1055into substrate processing region1070but not directly into chamber plasma region1020. Hollow volumes1051may be used for precursors which do not require excitement by a plasma to achieve a specific process. Showerhead1053is thicker than the length of the smallest diameter1050of the through-holes1056in this disclosed embodiment. In order to maintain a significant concentration of excited species penetrating from chamber plasma region1020to substrate processing region1070, the length226of the smallest diameter1050of the through-holes may be restricted by forming larger diameter portions of through-holes1056part way through the showerhead1053. The length of the smallest diameter1050of the through-holes1056may be the same order of magnitude as the smallest diameter of the through-holes1056or less in disclosed embodiments.

Showerhead1053may be configured to serve the purpose of an ion suppressor as shown inFIG. 2A. Alternatively, a separate processing chamber element may be included (not shown) which suppresses the ion concentration traveling into substrate processing region1070. Lid1021and showerhead1053may function as a first electrode and second electrode, respectively, so that lid1021and showerhead1053may receive different electric voltages. In these configurations, electrical power (e.g., RF power) may be applied to lid1021, showerhead1053, or both. For example, electrical power may be applied to lid1021while showerhead1053(serving as ion suppressor) is grounded. The substrate processing system may include a RF generator that provides electrical power to the lid and/or showerhead1053. The voltage applied to lid1021may facilitate a uniform distribution of plasma (i.e., reduce localized plasma) within chamber plasma region1020. To enable the formation of a plasma in chamber plasma region1020, insulating ring1024may electrically insulate lid1021from showerhead1053. Insulating ring1024may be made from a ceramic and may have a high breakdown voltage to avoid sparking. Portions of substrate processing chamber1001near the capacitively-coupled plasma components just described may further include a cooling unit (not shown) that includes one or more cooling fluid channels to cool surfaces exposed to the plasma with a circulating coolant (e.g., water).

In the embodiment shown, showerhead1053may distribute (via through-holes1056) process gases which contain oxygen, fluorine and/or nitrogen and/or plasma effluents of such process gases upon excitation by a plasma in chamber plasma region1020. In embodiments, the process gas introduced into the remote plasma system1010and/or chamber plasma region1020may contain fluorine (e.g. F2, NF3or XeF2). The process gas may also include a carrier gas such as helium, argon, nitrogen (N2), etc. Plasma effluents may include ionized or neutral derivatives of the process gas and may also be referred to herein as a radical-fluorine precursor referring to the atomic constituent of the process gas introduced.

Through-holes1056are configured to suppress the migration of ionically-charged species out of the chamber plasma region1020while allowing uncharged neutral or radical species to pass through showerhead1053into substrate processing region1070. These uncharged species may include highly reactive species that are transported with less reactive carrier gas by through-holes1056. As noted above, the migration of ionic species by through-holes1056may be reduced, and in some instances completely suppressed. Controlling the amount of ionic species passing through showerhead1053provides increased control over the gas mixture brought into contact with the underlying wafer substrate, which in turn increases control of the deposition and/or etch characteristics of the gas mixture. For example, adjustments in the ion concentration of the gas mixture can significantly alter its etch selectivity (e.g., SiCx:SiOxetch ratios).

In embodiments, the number of through-holes1056may be between about 60 and about 2000. Through-holes1056may have a variety of shapes but are most easily made round, The smallest diameter1050of through-holes1056may be between about 0.5 mm and about 20 mm or between about 1 mm and about 6 mm in disclosed embodiments. There is also latitude in choosing the cross-sectional shape of through-holes, which may be made conical, cylindrical or combinations of the two shapes. The number of small holes1055used to introduce unexcited precursors into substrate processing region1070may be between about 100 and about 5000 or between about 500 and about 2000 in different embodiments. The diameter of the small holes1055may be between about 0.1 mm and about 2 mm.

Through-holes1056may be configured to control the passage of the plasma-activated gas (i.e., the ionic, radical, and/or neutral species) through showerhead1053. For example, the aspect ratio of the holes (i.e., the hole diameter to length) and/or the geometry of the holes may be controlled so that the flow of ionically-charged species in the activated gas passing through showerhead1053is reduced. Through-holes1056in showerhead1053may include a tapered portion that faces chamber plasma region1020, and a cylindrical portion that faces substrate processing region1070. The cylindrical portion may be proportioned and dimensioned to control the flow of ionic species passing into substrate processing region1070. An adjustable electrical bias may also be applied to showerhead1053as an additional means to control the flow of ionic species through showerhead1053.

Alternatively, through-holes1056may have a smaller inner diameter (ID) toward the top surface of showerhead1053and a larger ID toward the bottom surface. In addition, the bottom edge of through-holes1056may be chamfered to help evenly distribute the plasma effluents in substrate processing region1070as the plasma effluents exit the showerhead and thereby promote even distribution of the plasma effluents and precursor gases. The smaller ID may be placed at a variety of locations along through-holes1056and still allow showerhead1053to reduce the ion density within substrate processing region1070. The reduction in ion density results from an increase in the number of collisions with walls prior to entry into substrate processing region1070. Each collision increases the probability that an ion is neutralized by the acquisition or loss of an electron from the wall. Generally speaking, the smaller ID of through-holes1056may be between about 0.2 mm and about 20 mm. In other embodiments, the smaller ID may be between about 1 mm and 6 mm or between about 0.2 mm and about 5 mm. Further, aspect ratios of the through-holes1056(i.e., the smaller Id to hole length) may be approximately 1 to 20. The smaller ID of the through-holes may be the minimum ID found along the length of the through-holes. The cross sectional shape of through-holes1056may be generally cylindrical, conical, or any combination thereof.

FIG. 2Bis a bottom view of a showerhead1053for use with a processing chamber according to disclosed embodiments. Showerhead1053corresponds with the showerhead shown inFIG. 2A. Through-holes1056are depicted with a larger inner-diameter (ID) on the bottom of showerhead1053and a smaller ID at the top. Small holes1055are distributed substantially evenly over the surface of the showerhead, even amongst the through-holes1056which helps to provide more even mixing than other embodiments described herein.

An exemplary patterned substrate may be supported by a pedestal (not shown) within substrate processing region1070when fluorine-containing plasma effluents and oxygen-containing plasma effluents arrive through through-holes1056in showerhead1053. Though substrate processing region1070may be equipped to support a plasma for other processes such as curing, no plasma is present during the etching of patterned substrate, in embodiments of the invention.

A plasma may be ignited either in chamber plasma region1020above showerhead1053or substrate processing region1070below showerhead1053. A plasma is present in chamber plasma region1020to produce the radical-fluorine precursors from an inflow of the fluorine-containing precursor. An AC voltage typically in the radio frequency (RF) range is applied between the conductive top portion (lid1021) of the processing chamber and showerhead1053to ignite a plasma in chamber plasma region1020during deposition. An RF power supply generates a high RF frequency of 13.56 MHz but may also generate other frequencies alone or in combination with the 13.56 MHz frequency.

The top plasma may be left at low or no power when the bottom plasma in the substrate processing region1070is turned on to either cure a film or clean the interior surfaces bordering substrate processing region1070. A plasma in substrate processing region1070is ignited by applying an AC voltage between showerhead1053and the pedestal or bottom of the chamber. A cleaning gas may be introduced into substrate processing region1070while the plasma is present.

The pedestal may have a heat exchange channel through which a heat exchange fluid flows to control the temperature of the substrate. This configuration allows the substrate temperature to be cooled or heated to maintain relatively low temperatures (from room temperature through about 120° C.). The heat exchange fluid may comprise ethylene glycol and water. The wafer support platter of the pedestal (preferably aluminum, ceramic, or a combination thereof) may also be resistively heated in order to achieve relatively high temperatures (from about 120° C. through about 1100° C.) using an embedded single-loop embedded heater element configured to make two full turns in the form of parallel concentric circles. An outer portion of the heater element may run adjacent to a perimeter of the support platter, while an inner portion runs on the path of a concentric circle having a smaller radius. The wiring to the heater element passes through the stem of the pedestal.

The substrate processing system is controlled by a system controller. In an exemplary embodiment, the system controller includes a hard disk drive, a floppy disk drive and a processor. The processor contains a single-board computer (SBC), analog and digital input/output boards, interface boards and stepper motor controller boards. Various parts of CVD system conform to the Versa Modular European (VME) standard which defines board, card cage, and connector dimensions and types. The VME standard also defines the bus structure as having a 16-bit data bus and a 24-bit address bus.

The system controller controls all of the activities of the etching chamber. The system controller executes system control software, which is a computer program stored in a computer-readable medium. Preferably, the medium is a hard disk drive, but the medium may also be other kinds of memory. The computer program includes sets of instructions that dictate the timing, mixture of gases, chamber pressure, chamber temperature, RF power levels, susceptor position, and other parameters of a particular process. Other computer programs stored on other memory devices including, for example, a floppy disk or other another appropriate drive, may also be used to instruct the system controller.

A process for depositing a film stack on a substrate or a process for cleaning a chamber can be implemented using a computer program product that is executed by the system controller. The computer program code can be written in any conventional computer readable programming language; for example, 68000 assembly language, C, C++, Pascal, Fortran or others. Suitable program code is entered into a single file, or multiple files, using a conventional text editor, and stored or embodied in a computer usable medium, such as a memory system of the computer. If the entered code text is in a high level language, the code is complied, and the resultant compiler code is then linked with an object code of precompiled Microsoft Windows® library routines. To execute the linked, compiled object code the system user invokes the object code, causing the computer system to load the code in memory. The CPU then reads and executes the code to perform the tasks identified in the program.

The interface between a user and the controller may include a flat-panel touch-sensitive monitor. In the preferred embodiment two monitors are used, one mounted in the clean room wall for the operators and the other behind the wall for the service technicians. The two monitors may simultaneously display the same information, in which case only one accepts input at a time. To select a particular screen or function, the operator touches a designated area of the touch-sensitive monitor. The touched area changes its highlighted color, or a new menu or screen is displayed, confirming communication between the operator and the touch-sensitive monitor. Other devices, such as a keyboard, mouse, or other pointing or communication device, may be used instead of or in addition to the touch-sensitive monitor to allow the user to communicate with the system controller.

The chamber plasma region or a region in a remote plasma system may be referred to as a remote plasma region. In embodiments, the radical precursors (e.g. a radical-fluorine precursor and radical-oxygen precursor) are formed in the remote plasma region and travel into the substrate processing region where the combination preferentially etches silicon-nitrogen-and-carbon-containing material. Plasma power may essentially be applied only to the remote plasma region, in embodiments, to ensure that the radical-fluorine precursor and the radical-oxygen precursor are not further excited in the substrate processing region.

In embodiments employing a chamber plasma region, the excited plasma effluents are generated in a section of the substrate processing region partitioned from a deposition region. The deposition region, also known herein as the substrate processing region, is where the plasma effluents mix and react to etch the patterned substrate (e.g., a semiconductor wafer). The excited plasma effluents may also be accompanied by inert gases (in the exemplary case, argon). The substrate processing region may be described herein as “plasma-free” during the etch of the patterned substrate. “Plasma-free” does not necessarily mean the region is devoid of plasma. A relatively low concentration of ionized species and free electrons created within the plasma region do travel through pores (apertures) in the partition (showerhead/ion suppressor) due to the shapes and sizes of through-holes1056. In some embodiments, there is no concentration of ionized species and free electrons within the substrate processing region outside of unavoidable sources of unintentional radiation which are omnipresent. The borders of the plasma in the chamber plasma region are hard to define and may encroach upon the substrate processing region through the apertures in the showerhead. In the case of an inductively-coupled plasma, a small amount of ionization may be effected within the substrate processing region directly. Furthermore, a low intensity plasma may be created in the substrate processing region without eliminating desirable features of the forming film. All causes for a plasma having much lower intensity ion density than the chamber plasma region (or a remote plasma region, for that matter) during the creation of the excited plasma effluents do not deviate from the scope of “plasma-free” as used herein.

Nitrogen trifluoride (or another fluorine-containing precursor) may be flowed into chamber plasma region1020at rates between about 25 sccm and about 200 sccm, between about 50 sccm and about 150 sccm or between about 75 sccm and about 125 sccm in different embodiments. Oxygen (O2) may be flowed into chamber plasma region1020at rates between about 25 sccm and about 200 sccm, between about 50 sccm and about 150 sccm or between, about 75 sccm and about 125 sccm in different embodiments.

Combined flow rates of fluorine-containing precursor and oxygen-containing precursor into the chamber may account for 0.05% to about 20% by volume of the overall gas mixture; the remainder being carrier gases. The fluorine-containing precursor and the oxygen-containing precursor are flowed into the remote plasma region but the plasma effluents have the same volumetric flow ratio, in embodiments. In the case of the fluorine-containing precursor, a purge or carrier gas may be first initiated into the remote plasma region before those of the fluorine-containing gas to stabilize the pressure within the remote plasma region.

Plasma power can be a variety of frequencies or a combination of multiple frequencies. In the exemplary processing system the plasma is provided by RF power delivered between lid1021and showerhead1053. The RF power may be between, about 10 watts and about 2000 watts, between about 20 watts and about 1500 watts or between about 50 watts and about 500 watts in different embodiments. The RF frequency applied in the exemplary processing system may be low RF frequencies less than about 200 kHz, high RF frequencies between about 10 MHz and about 15 MHz or microwave frequencies greater than or about 1 GHz in different embodiments.

Substrate processing region1070can be maintained at a variety of pressures during the flow of carrier gases and plasma effluents into substrate processing region1070. The pressure within the substrate processing region is below or about 50 Torr, below or about 30 Torr, below or about 20 Torr, below or about 10 Torr or below or about 5 Torr. The pressure may be above or about 0.1 Torr, above or about 0.2 Torr, above or about 0.5 Torr or above or about 1 Torr in embodiments of the invention. Lower limits on the pressure may be combined with upper limits on the pressure to arrive at further embodiments of the invention.

In one or more embodiments, the substrate processing chamber1001can be integrated into a variety of multi-processing platforms, including the Producer™ GT, Centura™ AP and Endura™ platforms available from Applied Materials, Inc. located in Santa Clara. Calif. Such a processing platform is capable of performing several processing operations without breaking vacuum. Processing chambers that may implement embodiments of the present invention may include dielectric etch chambers or a variety of chemical vapor deposition chambers, among other types of chambers.

Embodiments of the deposition systems may be incorporated into larger fabrication systems for producing integrated circuit chips.FIG. 3shows one such system1101of deposition, etching, baking and curing chambers according to disclosed embodiments. In the figure, a pair of FOUPs (front opening unified pods)1102supply substrate substrates (e.g., 300 mm diameter wafers) that are received by robotic arms1104and placed into a low pressure holding areas1106before being placed into one of the wafer processing chambers1108a-f. A second robotic arm1110may be used to transport the substrate wafers from the low pressure holding areas1106to the wafer processing chambers1108a-fand back. Each wafer processing chamber1108a-f, can be outfitted to perform a number of substrate processing operations including the dry etch processes described herein in addition to cyclical layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etch, pre-clean degas, orientation and other substrate processes.

The wafer processing chambers1108a-fmay include one or more system components for depositing, annealing, curing and/or etching a flowable dielectric film on the substrate wafer. In one configuration, two pairs of the processing chamber (e.g.,1108c-dand1108e-f) may be used to deposit dielectric material on the substrate, and the third pair of processing chambers (e.g.,1108a-b) may be used to etch the deposited dielectric. In another configuration, all three pairs of chambers (e.g.,1108a-f) may be configured to etch a dielectric film on the substrate. Any one or more of the processes described may be carried out on chamber(s) separated from the fabrication system shown in different embodiments.

System controller1157is used to control motors, valves, flow controllers, power supplies and other functions required to carry out process recipes described herein. A gas handling system1155may also be controlled by system controller1157to introduce gases to one or all of the wafer processing chambers1108a-f. System controller1157may rely on feedback from optical sensors to determine and adjust the position of movable mechanical assemblies in gas handling system1155and/or in wafer processing chambers1108a-f. Mechanical assemblies may include the robot, throttle valves and susceptors which are moved by motors under the control of system controller1157.

In an exemplary embodiment, system controller1157includes a hard disk drive (memory), USB ports, a floppy disk drive and a processor. System controller1157includes analog and digital input/output boards, interface boards and stepper motor controller boards. Various parts of multi-chamber processing system1101which contains substrate processing chamber1001are controlled by system controller1157. The system controller executes system control software in the form of a computer program stored on computer-readable medium such as a hard disk, a floppy disk or a flash memory thumb drive. Other types of memory can also be used. The computer program includes sets of instructions that dictate the timing, mixture of gases, chamber pressure, chamber temperature, RF power levels, susceptor position, and other parameters of a particular process.

A process for etching, depositing or otherwise processing a film on a substrate or a process for cleaning chamber can be implemented using a computer program product that is executed by the controller. The computer program code can be written in any conventional computer readable programming language: for example, 68000 assembly language, C, C++, Pascal, Fortran or others. Suitable program code is entered into a single file, or multiple files, using a conventional text editor, and stored or embodied in a computer usable medium, such as a memory system of the computer. If the entered code text is in a high level language, the code is compiled, and the resultant compiler code is then linked with an object code of precompiled Microsoft Windows® library routines. To execute the linked, compiled object code the system user invokes the object code, causing the computer system to load the code in memory. The CPU then reads and executes the code to perform the tasks identified in the program.

The interface between a user and the controller may be via a touch-sensitive monitor and may also include a mouse and keyboard. In one embodiment two monitors are used, one mounted in the clean room wall for the operators and the other behind the wall for the service technicians. The two monitors may simultaneously display the same information, in which case only one is configured to accept input at a time. To select a particular screen or function, the operator touches a designated area on the display screen with a finger or the mouse. The touched area changes its highlighted color, or a new menu or screen is displayed, confirming the operator's selection.

As used herein “substrate” may be a support substrate with or without layers formed thereon. The patterned substrate may be an insulator or a semiconductor of a variety of doping concentrations and profiles and may, for example, be a semiconductor substrate of the type used in the manufacture of integrated circuits. Exposed “silicon oxide” of the patterned substrate is predominantly SiO2but may include concentrations of other elemental constituents such as nitrogen, hydrogen, carbon and the like. In some embodiments, silicon oxide films etched using the methods disclosed herein consist essentially of silicon and oxygen. The term “precursor” is used to refer to any process gas which takes part in a reaction to either remove material from or deposit material onto a surface. “Plasma effluents” describe gas exiting from the chamber plasma region and entering the substrate processing region. Plasma effluents are in an “excited state” wherein at least some of the gas molecules are in vibrationally-excited, dissociated and/or ionized states. A “radical precursor” is used to describe plasma effluents (a gas in an excited state which is exiting a plasma) which participate in a reaction to either remove material from or deposit material on a surface. A “radical-oxygen precursor” is a radical precursor which contains oxygen but may contain other elemental constituents. A “radical-fluorine precursor” is a radical precursor which contains fluorine but may contain other elemental constituents. “Radical-oxygen precursor” and “radical-fluorine precursor” are equivalent to “oxygen-containing plasma effluents” and “fluorine-containing plasma effluents,” respectively. The phrase “inert gas” refers to any gas which does not form chemical bonds when etching or being incorporated into a film. Exemplary inert gases include noble gases but may include other gases so long as no chemical bonds are formed when (typically) trace amounts are trapped in a film.

The terms “gap” and “trench” are used throughout with no implication that the etched geometry has a large horizontal aspect ratio. Viewed from above the surface, trenches may appear circular, oval, polygonal, rectangular, or a variety of other shapes. A trench may be in the shape of a moat around an island of material. The term “via” is used to refer to a low aspect ratio trench (as viewed from above) which may or may not be filled with metal to form a vertical electrical connection. As used herein, a conformal etch process refers to a generally uniform removal of material on a surface in the same shape as the surface, i.e., the surface of the etched layer and the pre-etch surface are generally parallel. A person having ordinary skill in the art will recognize that the etched interface likely cannot be 100% conformal and thus the term “generally” allows for acceptable tolerances.

As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a process” includes a plurality of such processes and reference to “the dielectric material” includes reference to one or more dielectric materials and equivalents thereof known to those skilled in the art, and so forth.