US 4,642,227 A · Reactor for producing large particles of materials from gases

Abstract

A method and apparatus is disclosed for producing large particles of material from gas, or gases, containing the material (e.g., silicon from silane) in a free-space reactor comprised of a tube (20) and controlled furnace (25). A hot gas is introduced in the center of the reactant gas through a nozzle (23) to heat a quantity of the reactant gas, or gases, to produce a controlled concentration of seed particles (24) which are entrained in the flow of reactant gas, or gases. The temperature profile (FIG. 4) of the furnace is controlled for such a slow, controlled rate of reaction that virtually all of the material released condenses on seed particles and new particles are not nucleated in the furnace. A separate reactor comprised of a tube (33) and furnace (30) may be used to form a seed aerosol which, after passing through a cooling section (34) is introduced in the main reactor tube (34) which includes a mixer (36) to mix the seed aerosol in a controlled concentration with the reactant gas or gases.

Claims13

Dependent claims

A method for producing particles of material from a gas, or gases, using a free-space flow reactor, said reactor having a mixing zone in series with a primary reaction zone, comprising the steps of

introducing into said mixing zone said gas, or mixture of said gases, for flow through said reactor,
mixing a concentration of seed particles of said material with said gas, or gases, in said mixing zone, said concentration being limited such that the quantity of said gas or gases is sufficient to grow each of the particles in the reactor to the desired size larger than one micron within the reactor by vapor deposition alone, and
reacting said gas or gases in said primary reaction zone at a rate which is limited such that the products of gas phase reactions deposit on the seed particles entrained in the flow through said reactor, the rate of deposition being sufficient for the limited reacting rate to prevent homogenous nucleation of new particles, the ultimate particles size being less than 100 microns and the reaction time in said primary reaction zone being of the order of 0.2-10 seconds.

A method for growing silicon particles from a gas or gases containing silicon using a free-space pyrolytic reactor through which said gas or gases flow, said reactor having a mixing zone and a primary reaction zone, comprising the steps of

introducing a flow of said gas or gases through said reactor,
mixing a predetermined concentration of seed particles of silicon with said gas or gases in said mixing zone, said concentration being limited such that the quantity of said gas or gases is sufficient to grow each of the particles in the reactor to the desired size larger than one micron within the reactor by vapor deposition alone, and
growing said particles in said primary reaction zone to an ultimate size less than 100 microns during a residence time on the order of 0.2-10 seconds by vapor deposition of silicon on said seed particles by control of the temperature of said gas or gases flowing therethrough by temperature control beginning at a temperature at which the rate of reaction to generate considerable vapors is sufficiently slow to prevent significant reaction within the residence time available at the gas inlet end of said reactor, and then changing the temperature along the length of the reactor to accelerate the reactions leading to vapor deposition on the seed particles as they flow through the reactor, whereby reaction is limited at all points along the reactor such that vapor deposition on the seed particles occurs preferentially to the formation of new particles by homogenous nucleation.

Dependencies are inferred from the claim text.

Reactor for producing large particles of materials from gases

Life of this patent

Reactor for producing large particles of materials from gases

Life of this patent

Abstract

Claims13