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  Gas delivery device for improved deposition of dielectric materialUSPTO Application #: 20060065368Title: Gas delivery device for improved deposition of dielectric material Abstract: A gas delivery device useful in material deposition processes executed during semiconductor device fabrication in a reaction chamber, including the gas delivery device of the present invention and a method for carrying out a material deposition process, including introducing process gas into a reaction chamber using the gas delivery device of the present invention. In each embodiment, the gas delivery device of the present invention includes a plurality of active diffusers and a plurality of gas delivery nozzles, which extend into the reaction chamber. Before entering the reaction chamber through one of the plurality of gas delivery nozzles, process gas must first pass through one of the plurality active diffusers. Each of the active diffusers is centrally controllable such that the rate at which process gas flows through each active diffuser is exactly controlled at all times throughout a given deposition process. (end of abstract) Agent: Trask Britt - Salt Lake City, UT, US Inventor: Gurtej S. Sandhu USPTO Applicaton #: 20060065368 - Class: 156345330 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20060065368. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of application Ser. No. 11/004,702, filed Dec. 3, 2004, pending, which is a divisional of application Ser. No. 09/649,897, filed Aug. 28, 2000, now U.S. Pat. No. 6,896,737, issued May 24, 2005. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to reaction chambers used for the deposition of material layers during fabrication of semiconductor devices. Specifically, the present invention relates to an improved gas delivery device for improved control of chemical vapor delivery within a semiconductor device fabrication chamber. [0004] 2. State of the Art [0005] As is well known, processes for semiconductor device fabrication generally involve the deposition and processing of one or more material layers on a semiconductor substrate. Often, these different material layers are formed using well-known chemical vapor deposition (CVD) processes, such as thermally enhanced (TE) CVD, plasma enhanced (PE) CVD or high density plasma (HDP) CVD. Such techniques require placing a semiconductor substrate within a sealed reaction chamber and introducing one or more chemical vapors into the sealed reaction chamber under conditions known to result in the deposition of a desired material. However, in order to ensure the deposition of high-quality material layers using known deposition techniques, the quantity and quality of the gaseous chemicals entering the sealed reaction chamber must be carefully controlled throughout the deposition process. Failure to control the amount of chemical vapor entering a reaction chamber, the distribution of chemical vapor within the reaction chamber, or the rate at which a given amount of chemical vapor enters the reaction chamber can each result in low-quality material layers that substantially compromise the quality of the subsequently completed semiconductor device. [0006] For example, HDP CVD processes are often used to fill various features, such as isolation gaps or trenches, included in an intermediate semiconductor device structure with a dielectric material, such as silicon dioxide (SiO.sub.2). HDP CVD processes are currently favored for filling isolation gaps or trenches because the simultaneous dielectric deposition and sputter etch produced by such processes allows small, high aspect ratio features to be reliably filled with dielectric material. However, imprecise control of the reactant gases used for HDP deposition will either result in damage to underlying device features or deposition of a low-quality dielectric layer, either of which significantly reduces the performance and reliability of subsequently completed semiconductor devices. [0007] Presently used HDP CVD processes often utilize a gas mixture containing oxygen (O.sub.2), silane (SiH.sub.4), and inert gases, such as argon (Ar), in combination with plasma generation and application of an RF bias to the target substrate, to achieve simultaneous dielectric deposition and sputter etching. The interaction of SiH.sub.4 and O.sub.2 molecules in the HDP environment results in the deposition of silicon dioxide (SiO.sub.2) over the semiconductor substrate. However, as SiO.sub.2 is deposited over the semiconductor substrate, molecules of the inert gas included in the gas mixture are ionized by the plasma produced within the chamber. Due to the RF bias applied to the semiconductor substrate, the ionized molecules accelerate toward and impinge upon the surface of the substrate. As a result, SiO.sub.2 is simultaneously deposited on the wafer surface and sputter etched by accelerated ionized particles. In most HDP CVD processes, the ratio of deposition rate to etch rate ranges from about 2% to about 20%. It is the simultaneous deposition and sputter etch created by HDP CVD processes that allow higher aspect ratio features to be filled with the desired dielectric material. [0008] In order to better describe the simultaneous deposition and sputter etch of a typical HDP CVD process, drawing FIG. 1 through FIG. 4 schematically illustrate various stages of such a process. Illustrated in drawing FIG. 1 is an intermediate semiconductor device 5 including a semiconductor substrate 10 with an isolation gap 12 disposed between two circuit elements 14. As can be seen in drawing FIG. 1, due to the interaction of SiH.sub.4 with O.sub.2 during a typical HDP CVD process, a layer of SiO.sub.2 16 begins to form over the two circuit elements 14 and within the isolation gap 12. As the SiO.sub.2 16 is deposited, however, charged ions (not shown in drawing FIG. 1) impinge on and sputter etch the newly deposited layer of SiO.sub.2 16. Because the sputter etch rate created by the impinging ions is approximately three to four times higher at 45E than it is at 90E, facets 20 form at the corners of the two circuit elements 14 during the deposition process. Illustrated in drawing FIGS. 2 through 4 is the continuing growth of the layer of SiO.sub.2 16 and filling of the isolation gap 12 as would be expected from an HDP process having an optimized deposition-to-etch ratio. [0009] However, as is well known, the deposition-to-etch ratio can be controlled by varying the rate of flow of SiH.sub.4 or other process gases into the reaction chamber. For example, if the flow rate of SiH.sub.4 is increased, the deposition rate of the HDP CVD process will increase. As shown in drawing FIG. 5, if the deposition-to-etch ratio is increased above the optimum, the facets 20 begin moving away from the corners of the two circuit elements 14, and cusps 22 begin to form on sidewalls 24 of the isolation gap 12. Cusp formation is believed to result from redeposition of etched SiO.sub.2 on opposing surfaces through line-of-sight redeposition. Significantly, the rate of redeposition increases as the distance (represented by the letter "D") between opposing facets 20 decreases. As the facets 20 move away from the corners of the two circuit elements 14, the line-of-sight paths are shortened and sidewall redeposition is increased. Eventually, the cusps 22 meet, preventing further deposition below the cusps 22 and creating a void 25 in the dielectric material layer SiO.sub.2 16 deposited within the isolation gap 12, as can be seen in drawing FIG. 6. [0010] Additionally, if the rate at which inert gas (e.g., Ar) is introduced into an HDP CVD chamber is increased or flow of SiH.sub.4 is decreased, the sputter etch rate of the HDP CVD process will increase, thereby decreasing the deposition-to-etch ratio. As shown in drawing FIG. 7, decreasing the deposition-to-etch ratio can result in the etching or "clipping" of material from the corners 23 of the two circuit elements 14. Clipping progressively damages the circuit elements as the HDP CVD process progresses and will potentially compromise the performance of the two circuit elements 14 or render the two circuit elements 14 completely inoperable. [0011] As is easily appreciated from the foregoing, the flow rate of reactant gases used to effect HDP CVD processes, particularly those gases that affect the deposition-to-etch ratio, must be precisely controlled. This is especially true as the device features to be filled by HDP CVD processes shrink well below 0.5 .PHI.m. However, known gas delivery systems used in conjunction with HDP CVD reactors do not provide the range of control necessary to consistently deposit high quality dielectric material within the ever-shrinking, high-aspect-ratio device features included in state of the art semiconductor devices. [0012] A typical gas distribution device 28 used for gas delivery within an HDP CVD reaction chamber is illustrated in drawing FIG. 8. Such a gas distribution device 28 includes a single mass flow control valve ("MFC") 30, a gas inlet 32, a manifold ring 34, and a plurality of nozzles 36a-36h. Often during an initial period of a "gas-on" phase of an HDP CVD process, a build up of process gas pressure occurs within the gas delivery system, and where a gas distribution device 28 such as the device illustrated in drawing FIG. 8 is used, the initial build up of process gas pressure results in a high initial flow of reactant gas through the nozzles located closest to the gas inlet 32. However, while this high flow is occurring at the nozzles 36a, 36h closest to the gas inlet 32, very little, if any, reactant gas flows through those nozzles 36d, 36e located farthest away from the gas inlet 32 for approximately one to two seconds. Thus, deposition of SiO.sub.2 on the target substrate begins in the area of the substrate underlying those nozzles 36a, 36h closest to the gas inlet 32 before any deposition has taken place in the area of the target substrate underlying those nozzles 36d, 36e located farthest from the gas inlet 32. Moreover, the initial build up of process gas pressure causes process gas to flow through those nozzles 36a, 36h closest to the gas inlet 32 at an undesirably high rate, and the deposition-to-etch ratio of the HDP CVD process moves away from the desired optimum, until the pressure of the process gas within the gas distribution device 28 stabilizes. [0013] Where a gas delivery ring such as the one illustrated in drawing FIG. 8 is used to deliver SiH.sub.4 during an HDP CVD process, the quality of the resulting dielectric material may, therefore, be severely compromised. During the initial period of an SiH.sub.4 gas-on phase, the high flow of SiH.sub.4 through the nozzles 36a, 36h located closest to the gas inlet 32 of the gas distribution device 28 will cause the deposition-to-etch ratio to increase away from the desired optimum. Even though this inconsistency may last as little as one second, the deposition-to-etch ratio is effected long enough to affect deposition of at least the initial nuclear layer of the deposited dielectric material in such a way as to cause voids or other material inconsistencies within the deposited dielectric layer as the deposition process continues. Thus, the inconsistent gas flow provided by known gas delivery rings often renders entire wafers or portions of wafers unusable. [0014] As can be easily appreciated, there is a need in the art for a gas delivery apparatus that allows reliable, precise control of gas flow at all times during a material deposition process. Such a device would not only be desirable because it would eliminate the problems caused by the inconsistent delivery of process gases associated with known devices, but such a device will likely prove necessary as the dimensions of state of the art semiconductor devices continue shrink. BRIEF SUMMARY OF THE INVENTION [0015] The gas delivery device of the present invention addresses the foregoing needs by enabling precise control of process gas flow into a reaction chamber. In each embodiment, the gas delivery device of the present invention includes a plurality of active diffusers and a plurality of gas delivery nozzles which extend into the reaction chamber. Before entering the reaction chamber through one of the plurality of gas delivery nozzles, process gas must first pass through one of the plurality of active diffusers. Each of the active diffusers is centrally controllable such that the rate at which process gas flows through each active diffuser is exactly controlled at all times throughout a given deposition process. As a result, the gas delivery device of the present invention not only eliminates any undesirable increase in the rate of process gas flow during the initial period of a "gas on" phase of a material deposition process, but enables exact control of the deposition-to-etch ratio of any HDP CVD process. Further, each of the plurality of active diffusers included in the gas delivery device of the present invention is specifically positioned to minimize any inconsistencies in the time needed for the process gas to flow from the plurality of active diffusers and through each nozzle of the plurality of gas delivery nozzles. Thus, the gas delivery device of the present invention prevents the formation of material voids associated with the inconsistent flow rates of process gas during material deposition processes, such as an HDP CVD process, while reducing or eliminating any problems associated with non-uniform distribution of process gas within a reaction chamber. [0016] The present invention also includes a reaction chamber for use in material deposition processes. The reaction chamber includes a sealable chamber and a gas delivery device. The reaction chamber may further include various other known features necessary for carrying out a desired material deposition process. Significantly, because the reaction chamber incorporates the gas delivery device, the reaction chamber enables precise control of process gas dosing within the reaction chamber throughout any given material deposition process. [0017] Furthermore, the present invention includes a method of carrying out a material deposition process. The method of the present invention includes providing a reaction chamber, providing a gas delivery device according to any one of the embodiments of the gas delivery device of the present invention, disposing a semiconductor substrate within the reaction chamber, and introducing a desired process gas into the reaction chamber using the gas delivery device of the present invention. [0018] Various other aspects and advantages of the present invention will become apparent to those of skill in the art through consideration of the ensuing description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0019] The figures presented in conjunction with this description are not actual views of any particular portion of a device or component, but are merely representations employed to more clearly and fully depict the present invention. [0020] FIG. 1 through FIG. 4 illustrate deposition of a dielectric material over an intermediate semiconductor device during a desirable HDP CVD process; Continue reading... Full patent description for Gas delivery device for improved deposition of dielectric material Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Gas delivery device for improved deposition of dielectric material patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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