System and Method for Forming a Thin-Film Phosphor Layer for Phosphor-Converted Light Emitting Devices

Abstract

A thin-film phosphor layer can be formed by an improved deposition method involving: (1) forming a phosphor powder layer that is substantially uniformly deposited on a substrate surface; and (2) forming a polymer binder layer to fill gaps among loosely packed phosphor particles, thereby forming a substantially continuous layer of thin film.

1 . A method of forming a thin-film phosphor layer for use in a light emitting device, the method comprising:
 transporting, using a carrier gas, a phosphor powder from a source of the phosphor powder to a deposition chamber; and   depositing the phosphor powder adjacent to a substrate within the deposition chamber so as to substantially uniformly distribute the phosphor powder adjacent to a surface of the substrate.   
   
   
       2 . The method of  claim 1 , further comprising inducing electrostatic charges in the phosphor powder. 
   
   
       3 . The method of  claim 2 , wherein the substrate is electrically nonconductive, and further comprising:
 inducing opposite electrostatic charges adjacent to the surface of the substrate; and   subsequent to depositing the phosphor powder, discharging the phosphor powder using an ionizing gas.   
   
   
       4 . The method of  claim 2 , wherein the substrate is electrically conductive, and further comprising:
 electrically connecting the substrate to a ground potential; and   subsequent to depositing the phosphor powder, discharging the phosphor powder using an ionizing gas.   
   
   
       5 . The method of  claim 1 , wherein depositing the phosphor powder includes dispensing the phosphor powder through a showerhead mechanism. 
   
   
       6 . The method of  claim 1 , wherein depositing the phosphor powder includes rotating the substrate using a rotating substrate holder. 
   
   
       7 . The method of  claim 1 , wherein a thickness of the deposited phosphor powder is in the range of 10 nm to 60 μm. 
   
   
       8 . The method of  claim 1 , further comprising depositing a polymer adjacent to the deposited phosphor powder so as to form a thin-film phosphor layer adjacent to the surface of the substrate. 
   
   
       9 . The method of  claim 8 , wherein a thickness of the thin-film phosphor layer is in the range of 10 nm to 100 μm. 
   
   
       10 . The method of  claim 8 , wherein the polymer includes a polyxylylene-based polymer, and depositing the polymer is carried out using chemical vapor deposition. 
   
   
       11 . A method of forming a thin-film phosphor layer for use in a light emitting device, the method comprising:
 forming a first phosphor powder layer adjacent to a substrate, the first phosphor powder layer including first phosphor particles that are distributed adjacent to a surface of the substrate; and   forming, via vapor deposition, a first polymer layer adjacent to the first phosphor powder layer, the first polymer layer serving as a binder for the first phosphor particles.   
   
   
       12 . The method of  claim 11 , further comprising forming, via vapor deposition, a second polymer layer adjacent to the first polymer layer. 
   
   
       13 . The method of  claim 12 , wherein a refractive index of the first polymer layer is greater than a refractive index of the second polymer layer. 
   
   
       14 . The method of  claim 12 , wherein at least one of the first polymer layer and the second polymer layer includes a polymer including a repeating unit of the formula: —CZZ′—Ar—CZ″Z′″—, wherein Ar is selected from (1) an un-substituted phenylene group, (2) a chlorine-substituted phenylene group of the formula: C 6 H 4-x Cl x , with x being an integer in the range of 1 to 4, and (3) a fluorine-substituted phenylene group of the formula: C 6 H 4-   x′ F x′ , with x′ being an integer in the range of 1 to 4, and Z, Z′, Z″, and Z′″ are independently selected from H, F, alkyl groups, and aryl groups. 
   
   
       15 . The method of  claim 11 , further comprising:
 forming a second phosphor powder layer adjacent to the first polymer layer, the second phosphor powder layer including second phosphor particles that are distributed adjacent to a surface of the first polymer layer; and   forming, via vapor deposition, a second polymer layer adjacent to the second phosphor powder layer, the second polymer layer serving as a hinder for the second phosphor particles,   wherein the first phosphor particles and the second phosphor particles are configured to emit light of different colors.   
   
   
       16 . The method of  claim 15 , further comprising:
 forming a third phosphor powder layer adjacent to the second polymer layer, the third phosphor powder layer including third phosphor particles that are distributed adjacent to a surface of the second polymer layer; and   forming, via vapor deposition, a third polymer layer adjacent to the third phosphor powder layer, the third polymer layer serving as a binder for the third phosphor particles,   wherein the first phosphor particles, the second phosphor particles, and the third phosphor particles are configured to emit light of different colors.   
   
   
       17 . A system to form a thin-film phosphor layer on a substrate, the system comprising:
 a deposition subsystem defining an enclosure to accommodate the substrate;   a phosphor powder delivery subsystem configured to deliver, using a carrier gas, a phosphor powder from a source of the phosphor powder to the deposition subsystem;   a polymer precursor delivery subsystem configured to deliver polymer precursors in a vapor phase to the deposition subsystem; and   a control subsystem connected to the deposition subsystem, the phosphor powder delivery subsystem, and the polymer precursor delivery subsystem, wherein the control subsystem is configured to control the phosphor powder delivery subsystem to deliver the phosphor powder to the deposition subsystem for a first time interval to form a phosphor powder layer adjacent to the substrate, and the control subsystem is configured to control the polymer precursor delivery subsystem to deliver the polymer precursors to the deposition subsystem for a second time interval to form a polymer layer adjacent to the phosphor powder layer.   
   
   
       18 . The system of  claim 17 , wherein the deposition subsystem includes a vacuum chamber defining the enclosure, a substrate holder configured to support the substrate within the vacuum chamber, and a showerhead mechanism configured to deposit the phosphor powder over the substrate. 
   
   
       19 . The system of  claim 18 , wherein the substrate holder is configured to rotate the substrate. 
   
   
       20 . The system of  claim 18 , wherein the deposition subsystem further includes an ionizer configured to induce electrostatic charges in the phosphor powder. 
   
   
       21 . The system of  claim 17 , wherein the phosphor powder delivery subsystem includes an ionizer configured to induce electrostatic charges in the phosphor powder. 
   
   
       22 . The system of  claim 17 , wherein the polymer precursor delivery subsystem includes a gas reactor configured to generate reactive intermediates in a vapor phase from the polymer precursors. 
   
   
       23 . The system of  claim 22 , wherein the gas reactor is configured to generate free radicals from the polymer precursors, and the polymer precursors have the formula: (CZZ′Y) m —Ar—(CZ″Z′″Y′) n , wherein Ar is selected from (1) an un-substituted phenylene group, (2) a chlorine-substituted phenylene group of the formula: C 6 H 4-x Cl x , with x being an integer in the range of 1 to 4, and (3) a fluorine-substituted phenylene group of the formula: C 6 H 4-   x′ F x′ , with x′ being an integer in the range of 1 to 4, Z, Z′, Z″, and Z′″ are independently selected from H, F, alkyl groups, and aryl groups, Y and Y′ being removable to generate the free radicals, m and n are each equal to zero or a positive integer, and a sum of m and n is less than or equal to a total number of sp 2 -hybridized carbons on Ar available for substitution. 
   
   
       24 . The system of  claim 22 , wherein the gas reactor is configured to generate free radicals from the polymer precursors, and the polymer precursors include dimers having the formula: {(CZZ′)—Ar—(CZ″Z′″)} 2 , wherein Ar is selected from (1) an un-substituted phenylene group, (2) a chlorine-substituted phenylene group of the formula: C 6 H 4-x Cl x , with x being an integer in the range of 1 to 4, and (3) a fluorine-substituted phenylene group of the formula: C 6 H 4-   x′ F x′ , with x′ being an integer in the range of 1 to 4, and Z, Z′, Z″, and Z′ are independently selected from H, F, alkyl groups, and aryl groups. 
   
   
       25 . A thin-film phosphor layer, comprising:
 at least one phosphor layer; and   at least one parylene-based polymer layer disposed adjacent to the at least one phosphor layer, the at least one parylene-based polymer layer serving as a binder for the at least one phosphor layer.   
   
   
       26 . The thin-film phosphor layer of  claim 25 , wherein the at one parylene-based polymer layer includes a polymer including a repeating unit of the formula: —CZZ′—Ar—CZ″Z′″—, wherein Ar is selected from (1) an un-substituted phenylene group, (2) a chlorine-substituted phenylene group of the formula: C 6 H 4-x Cl x , with x being an integer in the range of 1 to 4, and (3) a fluorine-substituted phenylene group of the formula: C 6 H 4-   x′ F x′ , with x′ being an integer in the range of 1 to 4, and Z, Z′, Z″, and Z′″ are independently selected from H, F, alkyl groups, and aryl groups.