This invention generally pertains to systems and manifolds for delivering chemicals from bulk delivery canisters to manufacturing process tools such as chemical vapor deposition (CVD) devices, and more particularly for process tools utilized in the fabrication of integrated circuits.
The production of electronic devices such as integrated circuits is well known. In certain steps in such production, chemical may be fed to certain process tools which use the chemical. For instance, a CVD reactor is commonly employed to generate a layer of a given material, such as a dielectric or conductive layer. Historically, the process chemicals were fed to the CVD reactor via bulk delivery cabinets. The chemicals used in the fabrication of integrated circuits must have a ultrahigh purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been a directly proportional increase in the need for maintaining the purity of source chemicals. This is because contaminants are more likely to deleteriously affect the electrical properties of integrated circuits as line spacing and interlayer dielectric thickness decrease. The increasing chemical purity demands also impact the chemical delivery systems.
Thus, there exists a need for improved chemical delivery systems such that impurities are not introduced into the process tools during chemical canister replacement or refilling procedures, and other maintenance procedures. The impurities of concern may include particles, moisture, trace metals, etc. In order to meet these more demanding requirements, improved manifold systems are required.
Further as chemical purity demands have increased, the variety of chemicals utilized in integrated circuit manufacturing have increased. Moreover, some of the chemicals being contemplated for integrated circuit manufacturing exhibit more demanding physical properties and/or are more toxic than previous chemicals utilized, thus placing additional demands upon the chemical delivery system. For example, very low vapor pressure chemicals having a vapor pressure of less than 100 mT and even less than 10 mT are contemplated for use in integrated circuit manufacturing. One such chemical, TaEth (tantalum pentaethoxide) has a vapor pressure of less than 1 mT and is contemplated for use in the CVD formation of dielectric layers. Another such chemical, TDEAT (tetrakis(diethylamido)titanium) has a vapor pressure of approximately 7 mT and is contemplated for use in the CVD formation of titanium nitride layers. Yet another low vapor pressure chemical is TEASate (triethyl arsenate). Additional low vapor pressure chemicals may be those utilized to deposit conductor layers formed of copper or TaN. Because the vapor pressures of such chemicals are so low, traditional methods of purging the manifold system of a chemical delivery system are inadequate. While existing manifolds adequately allow traditional compounds to be removed from the lines and manifold through repeated vacuum/gas purge cycles, such vacuum/gas purge cycles may not adequately remove very low vapor pressure materials. Thus, a need exists for an improved method and apparatus for purging a manifold system such that very low vapor pressure chemicals may be adequately purged from the various components of the chemical delivery system. Further, materials such as TaEth may require heating of the chemical cabinet. It is thus desirable to have a chemical delivery system which efficiently incorporates a heating system into the gas cabinet.
Other chemicals also place increased demands upon the purging techniques utilized. For example, chemicals which include solid compounds in solution with a liquid may also be used as reactants in the manufacture of integrated circuits. The solid compounds are typically stored in chemical canisters as dispersions in an organic liquid. For example, solid reactants such as barium/strontium/titanate (BST) cocktails (solutions) utilized for forming dielectric layers may be dispersed in a liquid such as tetrahydrofuran (THF) or triglyme. A wide variety of other solid materials may also be used in conjunction with other organic liquids, such as for example as described in U.S. Pat. No. 5,820,664 the disclosure of which is incorporated herein by reference.
When such solid compositions are sold and used in canisters, the canisters are often adapted such that they may be connected to a manifold for distribution of the chemical, such as described in U.S. Pat. Nos. 5,465,766; 5,562,132; and 5,607,002. However, when the canister is changed, existing manifolds do not adequately accommodate the ability to clean out the manifold and lines prior to change out. Thus, if a vacuum/gas purge cycle is used with a solid/liquid composition, the liquid will be evaporated away to leave solid compounds in the lines. This is unacceptable, especially if the canister is being changed out to another compound since the line is contaminated. Particle contamination and chemical concentration variation may cause severe process problems at the process tool. A solution to this problem would be highly desirable.
Further, it is desirable to improve the clean out and purge processes because the chemicals utilized may be highly toxic, noxious, etc. Thus, it is desirable to reduce the residual levels of low vapor pressure chemicals (such as discussed herein) within the manifold and lines of the chemical delivery system.
Moreover, at least some of the chemicals contemplated for use in deposition systems have ambient temperature requirements which may require elevated temperatures to prevent solidification. Thus, a chemical delivery system which addresses the above described problems while efficiently and economically providing a controlled temperature environment is desirable.
The present invention provides a solution to one or more of the disadvantages and needs addressed above. More particularly, a chemical delivery system which utilizes multiple techniques to achieve a suitable chemical purge of the chemical delivery system is provided. A purge sequence serves to purge the manifold and canister connection lines of the chemical delivery system prior to removal of an empty chemical supply canister or after a new canister is installed. More particularly, a purge technique which may utilize at least one of a variety of combinations of a medium level vacuum source, a hard vacuum source, and/or a liquid flush system is disclosed. By utilizing a plurality of purge techniques, chemicals such as TaEth, TDEAT, BST, etc. which pose purging difficulties, may be efficiently purged from the chemical delivery system. The chemical delivery system may also be provided with an efficient and conveniently located heater system for heating the chemical delivery system cabinet. Advantageously, the manifold of this invention enables improved purge efficiency for low vapor pressure materials and toxic chemicals.
In one respect, the present invention may include a method of purging a low vapor pressure chemical from a chemical delivery system having a plurality of valves and lines. The method may include utilizing a first purging technique to remove chemical, gas, or contaminants from within at least some of the valves and lines; utilizing a second purging technique to remove chemical, gas, or contaminants from within at least some of the valves and lines; and utilizing a third purging technique to remove chemical, gas, or contaminants from within at least some of the valves and lines. In this method, each of the first, second and third purging techniques may be different. The first purging technique may be a first vacuum step, the second purging technique may be a flowing purge step utilizing an inert gas, and the third purging technique may be a liquid flush step. Alternatively, the third purging technique may be a second vacuum step, the first and second vacuum steps utilizing different types of vacuum sources.
Another method according to the present invention is a method of operating a chemical delivery system for delivery of chemicals to a semiconductor process tool. The method may include providing at least one liquid chemical from the chemical delivery system to the semiconductor process tool; purging at least a portion of the chemical delivery system of gas, the liquid chemical or contaminants, the purging including the use of at least three different purging techniques; and changing at least one canister of the chemical delivery system, the canister containing the at least one liquid chemical.
In yet another embodiment of the present invention, a method of purging a low vapor pressure liquid chemical from a chemical delivery system is provided. The method may include providing the low vapor pressure liquid chemical to at least one line or valve of the chemical delivery system; and purging the at least one line or valve of the low vapor pressure liquid chemical , the purging including the use of at least three different purging techniques. The low vapor pressure liquid chemical may be TaEth, TDEAT or BST or other low vapor pressure chemicals.
In another embodiment, a method of forming a dielectric layer upon a semiconductor substrate is provided. The method includes providing the semiconductor substrate, the substrate having one or more layers; providing a deposition process tool; and coupling a chemical delivery system to the deposition process tool to provide a low vapor pressure liquid chemical to the deposition process tool. The method further includes periodically purging at least a portion of the chemical delivery system of the low vapor pressure liquid chemical, the purging including the use of at least three different purging techniques; and depositing the dielectric layer upon the semiconductor substrate by utilizing the low vapor pressure liquid chemical within the deposition process tool. The low vapor pressure liquid chemical may be TaEth or BST.
In still another embodiment, a method of forming a layer containing titanium upon a semiconductor substrate is provided. The method may include providing the semiconductor substrate, the substrate having one or more layers; providing a deposition process tool; and coupling a chemical delivery system to the deposition process tool to provide a low vapor pressure liquid chemical to the deposition process tool. The method may also include periodically purging at least a portion of the chemical delivery system of the low vapor pressure liquid chemical, the purging including the use of at least three different purging techniques; and depositing the layer containing titanium upon the semiconductor substrate by utilizing the low vapor pressure liquid chemical within the deposition process tool. The low vapor pressure liquid chemical may be TDEAT. The layer may comprise titanium nitride.
In one embodiment, the present invention may be a chemical delivery system. The chemical delivery system may include at least one canister inlet and at least one canister outlet line; a plurality of manifold valves and lines; a first purge source inlet coupling a first purge source to the plurality of manifold valves and lines; a second purge source inlet coupling a second purge source to the plurality of manifold valves and lines; and a third purge source inlet coupling a third purge source to the plurality of manifold valves and lines, the first, second and third purge sources each being different types of purge sources. The first purge source may be a first vacuum source, the second purge source may be a gas source and the third purge source may be a liquid source. Alternatively, the third purge source may be a second vacuum source, the first and second vacuum sources being different types of vacuum sources.
In another embodiment, a chemical delivery system for delivery of low vapor pressure liquid chemicals to a semiconductor process tool is provided. The system may include at least one chemical output line, the chemical output line coupled to the manifold of the chemical delivery system and operable to provide the low vapor pressure liquid chemical to the semiconductor process tool; at least three purge source inlet lines, the purge source inlet lines coupling at least three different purge sources to the manifold; and one or more refillable canisters coupled to the manifold. The one or more refillable canisters may comprise at least a first canister and a second canister. Further the low vapor pressure liquid chemical may be provided to the semiconductor process tool from the second canister, the chemical delivery system being capable of refilling the second canister from the first canister. The system may alternatively be capable of providing liquid chemical from both the first canister and the second canister to the semiconductor process tool.
Another embodiment of the invention disclosed herein may include a cabinet for housing a chemical delivery system. The cabinet may include a plurality of cabinet walls forming an interior cabinet space, at least one of the cabinet walls being a door; at least one heater element disposed in or adjacent to the door; and an air flow passage in close proximity to the at least one heater element. The cabinet may further include at least one heat exchange element within the air flow passage, the heat exchange element being thermally coupled to the heater. The heat exchange element may be a plurality of fins. The air flow passage may be formed along a back side of a wall of the door and the heater element may be formed along a front side of the wall of the door. The door of the cabinet may have a cavity and an interface structure within the cavity, the interface structure forming at least a portion of the wall of the door. The heater may be recessed within the door.
Another embodiment of disclosed invention may include a temperature controlled cabinet for housing a liquid chemical delivery system. The cabinet may include at least one door; at least one heater element disposed in or on the door; an air vent within the door; and an air flow passage in close proximity to the at least one heater element, the air flow passage thermally communicating with the at least one heater element, the air vent providing an air inlet for the air flow passage.
In still another embodiment, a temperature controlled cabinet for housing a liquid chemical delivery system is provided. The cabinet may include a plurality of cabinet walls; and at least one heater element disposed in or on at least a first cabinet wall, the heater element being located on exterior side of the first cabinet wall and thermal energy from the heater being coupled to the interior of the cabinet through the first cabinet wall. The first cabinet wall may be at least a portion of a cabinet door. The cabinet may further comprising an air passage adjacent an interior side of the first cabinet wall.
Yet another embodiment of the present invention is a method of controlling the temperature of a cabinet housing a chemical delivery system. The method may include providing a plurality of cabinet walls forming an interior cabinet space; locating at least one heater element within or in close proximity to at least a first cabinet wall; and thermally transferring energy from the heater to the interior cabinet space utilizing the first cabinet wall as a heat transfer mechanism.
In yet another embodiment, a method of controlling the temperature of a cabinet housing a liquid chemical delivery system is provided. The method may include providing a plurality of cabinet walls forming an interior cabinet space; locating at least one heater element on an exterior side of at least a portion of a first cabinet wall; thermally transferring energy from the heater to an interior side of the first cabinet wall, utilizing the first cabinet wall as a heat transfer mechanism; and heating the interior cabinet space by flowing air across the interior side of the first cabinet and circulating side air within the interior cabinet space.
Still another embodiment of the present invention is a chemical delivery system manifold useful for delivery of liquid chemicals from a canister. The manifold may include a vacuum supply valve coupled to a vacuum generator; a pressure vent valve coupled to the vacuum generator; and a carrier gas isolation valve coupled to a carrier gas source. The manifold further includes a process line isolation valve coupled to a bypass valve and a canister outlet line, the canister outlet line capable of being coupled to a canister outlet valve; a flush inlet valve coupled between the carrier gas isolation valve and the bypass valve, the flush inlet valve capable of being connected to a liquid flush source; and a canister inlet line capable of being coupled between a canister inlet valve and the bypass valve.
Also disclosed is a chemical delivery system manifold useful for delivery of liquid chemicals from a canister. The system may include a first vacuum supply valve for coupling the manifold to a first vacuum source; a second vacuum supply valve for coupling the manifold to a second vacuum source, the first and second vacuum sources being different types of vacuum sources; and a pressure vent valve coupled to either or both of the first and second vacuum sources. The system may also include a carrier gas isolation valve coupled to a carrier gas source; a process line isolation valve coupled to a bypass valve and a canister outlet line, the canister outlet line capable of being coupled to a canister outlet valve; and a canister inlet line capable of being coupled between a canister inlet valve and the bypass valve. The manifold may also include a flush inlet valve coupled between the carrier gas isolation valve and the bypass valve, the flush inlet valve capable of being connected to a liquid flush source.
In another embodiment a chemical delivery system is disclosed. The chemical delivery system may include (1) a vacuum supply valve; (2) a vacuum generator; (3) a carrier gas isolation valve; (4) a bypass valve; (5) a process line isolation valve; (6) a liquid flush inlet valve; (7) a low pressure vent valve; (8) a canister inlet valve; and (9) a canister outlet valve. The system may be configured such that the vacuum supply valve is connected to the vacuum generator; the carrier gas isolation valve is connected to the liquid flush inlet valve; and the liquid flush inlet valve is connected to the bypass valve. Also, the bypass valve is further connected to the process line isolation valve; the low pressure vent valve is connected to the vacuum generator; the process line isolation valve is also connected to the canister outlet valve; and the canister inlet valve is connected to the canister outlet valve.
Also disclosed is a method of purging a low vapor pressure liquid chemical from a chemical delivery system. The method may include providing a manifold. The manifold may comprise a vacuum supply valve coupled to a vacuum source, a pressure vent valve coupled to the vacuum supply valve, a carrier gas isolation valve coupled to a carrier gas source, a process line isolation valve coupled to a bypass valve and a canister outlet line, the canister outlet line capable of being coupled to a canister outlet valve, a flush inlet valve coupled between the carrier gas isolation valve and the bypass valve, the flush inlet valve capable of being connected to a liquid flush source, and a canister inlet line capable of being coupled between a canister inlet valve and the bypass valve. The method also comprises providing the low vapor pressure liquid chemical to at least one line or valve of the chemical delivery system; and purging the at least one line or valve of the low vapor pressure liquid chemical, the purging including the use of at least three different purging techniques.
In still another embodiment, a method of purging a low vapor pressure liquid chemical from a chemical delivery system is provided. The method may include providing a manifold. The manifold may comprise a vacuum supply valve coupled to a vacuum source, a pressure vent valve coupled to the vacuum supply valve, a carrier gas isolation valve coupled to a carrier gas source, a process line isolation valve coupled to a bypass valve and a canister outlet line, the canister outlet line capable of being coupled to a canister outlet valve, and a canister inlet line capable of being coupled between a canister inlet valve and the bypass valve. The method may further comprise providing the low vapor pressure liquid chemical to at least one line or valve of the chemical delivery system; purging the at least one line or valve of the low vapor pressure liquid chemical, the purging including the use of at least three different purging techniques.