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US 8,540,891 B2Granted
Etching pastes for silicon surfaces and layers
AssigneeMerck Patent GmbH
InventorsArmin Kübelbeck, Sylke Klein, Werner Stockum
Life of this patent
Estimating the term…
Abstract
The invention relates to novel etching media in the form of etching pastes for etching selected areas or the entire area of silicon surfaces and layers, in addition to the use of said media.
Claims16
A process for the selective etching of patterns or lines on silicon surfaces and layers to a depth of 1-3 μm, said process comprising:
- applying a printable thickened, alkaline liquid etching medium (a) over the entire surface area of said surface or layer, or (b) in accordance with an etch structure mask specifically only to the areas of the surface where etching is desired, and
- removing said medium after an exposure time of from 30 s to 5 minutes,
- wherein said etching medium is effective at temperatures from 70 to 150° C. or can be activated by the input of energy, and
- wherein said etching medium comprises
- (a) 30-40% by weight of a potassium hydroxide etching component, based on the total amount of an etching medium,
- (b) from 55-75% by weight, based on the total amount of said etching medium, of a solvent which is a mixture of water and at least one other solvent that is diethylene glycol, dipropylene glycol, polyethylene glycols, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, glycerol, 1,5 pentanediol, 2-ethyl-1-hexanol, acetophenone, methyl-2-hexanone, 2-octanone, 4-hydroxy-4-methyl-2-pentanone, 1-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, or a carboxylic acid ester,
- (c) 1.0-10% by weight of a thickener which is hydroxyalkylguar, xanthan gum, and/or ethyl hydroxypropyl or hydroxyethylcellulose, sodium carboxymethylhydroxyethylcellulose, homopolymers or copolymers based on functionalised vinyl units of acrylic acid, acrylates or alkyl methacrylates (C10-C30), individually or in a mixture, and
- (d) optionally an additive that is a thixotropic agent, a flow-control agent, a deaerator or an adhesion promoter, and
- wherein said etching medium selectively etches patterns or lines on said silicon surface or layer to a depth of 1-3 μm.
6 more elements
A method for the selective etching of patterns or lines on silicon surfaces and layers for isolation of the pn transition in solar cells comprising:
- applying a printable thickened, alkaline liquid etching medium to the surface of said silicon or a layer for isolation of the pn transition in a solar cell,
- wherein said etching medium comprises
- (a) 30-40% by weight of a potassium hydroxide etching component, based on the total amount of an etching medium, and
- (b) from 55-75% by weight, based on the total amount of said etching medium, of a solvent which is a mixture of water and at least one other solvent that is diethylene glycol, dipropylene glycol, polyethylene glycols, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, glycerol, 1,5 pentanediol, 2-ethyl-1-hexanol, acetophenone, methyl- 2-hexanone, 2-octanone, 4-hydroxy-4-methyl-2-pentanone, 1-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, or a carboxylic acid ester,
- and
- (c) 1.0-10% by weight of a thickener which is hydroxyalkylguar, xanthan gum, and/or ethyl hydroxypropyl or hydroxyethylcellulose, sodium carboxymethylhydroxyethylcellulose, homopolymers or copolymers based on functionalised vinyl units of acrylic acid, acrylates or alkyl methacrylates (C10-C30), individually or in a mixture,
- and wherein said etching medium selectively etches patterns or lines on said silicon surface or layer for isolation of the pn transition in of a solar cell to a depth of 1-3 μm.
4 more elements
A process for the selective etching of patterns and lines on silicon surfaces and layers to a depth of 1-3 μm, comprising:
- applying a printable thickened, alkaline liquid etching medium over the entire surface area of said surface or layer or in accordance with an etch structure mask specifically only to the areas of the surface where etching is desired,
- activating said medium by exposing to temperatures of from 70 to 150° C, and
- removing said medium after an exposure time of from 30 s to 5 minutes,
- wherein said etching medium comprises
- (a) 30-40% by weight of a potassium hydroxide etching component, based on the total amount of an etching medium,
- (b) from 55-75% by weight, based on the total amount of said etching medium, of a solvent which is a mixture of water and at least one other solvent that is diethylene glycol, dipropylene glycol, polyethylene glycols, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, glycerol, 1,5 pentanediol, 2-ethyl-1-hexanol, acetophenone, methyl-2-hexanone, 2-octanone, 4-hydroxy-4-methyl-2-pentanone, 1-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, or a carboxylic acid ester, and
- c) from 1.5-6% by weight of a thickener which is hydroxyalkylguar, xanthan gum, and/or ethyl hydroxypropyl or hydroxyethylcellulose, sodium carboxymethylhydroxyethylcellulose, homopolymers or copolymers based on functionalised vinyl units of acrylic acid, acrylates or alkyl methacrylates (C10-C30), individually or in a mixture,
- and wherein said etching medium selectively etches patterns and lines on said silicon surface or layer to a depth of 1-3 μm.
5 more elements
Dependencies are inferred from the claim text.