NOVELTY - A fluid delivery system (10) comprises an active fluid source (12); a diluent fluid source (14); a fluid flow metering device (24) to dispense active or diluent fluid; a mixer (28) to mix the two fluids to form a diluted active fluid mixture; a monitor (42) to sense concentration of active fluid and/or diluent fluid in the mixture, and to responsively adjust the metering device to achieve a predetermined concentration of active fluid in the mixture; and a pressure controller (38) to control flow of fluid so as to maintain a predetermined pressure of the mixture dispensed from system.    USE - For delivering a dilute fluid to a semiconductor manufacturing tool (such as ion implantation tools, chemical vapor deposition tools, epitaxial doping tools, and etching tools) for manufacturing a semiconductor product and other microelectronic product (claimed).    ADVANTAGE - The system provides efficient and economic delivery of dilute gases at predetermined concentration to process equipment. The dilute fluid supply system can be operated and arranged to supply several active species, e.g. a blend of complex dopants. The system provides enhanced safety when the active fluid source is a sub-atmospheric gas source. Thus, the system, by virtue of its use of a real-time fluid monitor, provides a continuous measure of the fluid mixture to ensure a constant diluted active fluid concentration in the delivered dilute fluid mixture, and at the same time provides the delivered dilute fluid mixture at a set point pressure determined by the pressure controller that accommodates downstream flow control by the end user, without loss of accuracy of the in-line analyzer or deviation from the desired concentration level of the active fluid component in the diluted fluid mixture. The system provides a conveniently transported and installed point-of-use gas delivery unit, which can be readily connected to source gas vessels or other gas supply sources and to the downstream flow controller and gas-utilizing process facility, to provide the desired amount of diluted gas mixture containing a precisely controlled concentration of active component. By utilizing an electronic pressure controller or other pressure controller instead of the mass flow controller employed in prior fluid delivery systems to control the flow of diluent gas, a constant pressure can be maintained in the gas blender, regardless of what overall flow rate is selected by the end user for delivery to the downstream gas-utilizing installation. The maintaining of the gas blender at a constant pressure allows the analyzer to determine concentration of the diluted active gas component in an accurate manner at all times.    DETAILED DESCRIPTION - A fluid delivery system (10) comprises an active fluid source (12) of active fluid; a diluent fluid source (14) of diluent fluid; a fluid flow metering device (24) adapted to dispense one of the active and diluent fluids; a mixer (28) arranged to mix the active and diluent fluids to form a diluted active fluid mixture; a monitor (42) arranged to sense concentration of the active fluid and/or the diluent fluid in the diluted active fluid mixture, and to responsively adjust the fluid flow metering device to achieve a predetermined concentration of active fluid in the diluted active fluid mixture; and a pressure controller (38) arranged to control flow of the other of the active and diluent fluids so as to maintain a predetermined pressure of the diluted active fluid mixture dispensed from the system. The system is coupled with a fluid-utilizing unit, for flow of dispensed diluted active fluid mixture to the unit. The system further comprises a mass flow controller arranged to provide a predetermined flow of dispensed diluted active fluid mixture to the fluid-utilizing unit such as semiconductor process tool. INDEPENDENT CLAIMS are included for the following:    (1) a fluid blender apparatus comprising a fluid blender box including fluid flow metering device, pressure controller, mixer and monitor, and the flow circuitry is arranged for connection to active fluid and diluent fluid sources located exterior of the fluid blender box;    (2) a method of blending fluids to form a multicomponent fluid;    (3) a microelectronic product manufacturing facility such as semiconductor manufacturing facility;    (4) a method of manufacturing a microelectronic product such as semiconductor product;    (5) a fluid delivery apparatus; and    (6) a method for delivery of dilute fluid.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a gas delivery system.    system (10)    active fluid source (12)    diluent fluid source (14)    fluid flow metering device (24)    mixer (28)    pressure controller (38)    monitor. (42)