Selective metal etching in metal/polymer structures
First Claim
1. A method for removing a metal layer from a structure, in the presence of a polymer layer, without substantial removal of said polymer layer, by the step ofirradiating said metal layer with pulsed ultraviolet radiation of a wavelength in the range 100-400 nm and an energy fluence per pulse sufficiently high that said metal is rapidly removed in one or two pulses while only a thin surface region less than a few microns of said polymer is etched by said ultraviolet radiation pulses said energy fluence per pulse being greater than 3-5 J/cm2.
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Accused Products
Abstract
A differential material removal process wherein a selected material can be rapidly removed without adverse impact to surrounding layers of different materials. Ultraviolet radiation is used to selectively remove metal without adversely harming adjacent polymer layers, in a metal-polymer multilayer structure. The wavelength (100-400 nm) of the ultraviolet radiation and the energy fluence per pulse are selected so that the removal rate of metal due to thermal processes is significantly greater than the removal rate of the polymer by ablative photodecomposition. This can occur at an energy fluence per pulse level greater than that at which the etch rate of the polymer begins to level off. For example, copper of a thickness less than 5 microns is rapidly etched in one or two pulses while adjacent polyimide layers are substantially unetched by the application of ultraviolet pulses of wave-lengths 248-351 nm, at energy fluences per pulse in excess of approximately 3 or 4 J/cm2.
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Citations
21 Claims
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1. A method for removing a metal layer from a structure, in the presence of a polymer layer, without substantial removal of said polymer layer, by the step of
irradiating said metal layer with pulsed ultraviolet radiation of a wavelength in the range 100-400 nm and an energy fluence per pulse sufficiently high that said metal is rapidly removed in one or two pulses while only a thin surface region less than a few microns of said polymer is etched by said ultraviolet radiation pulses said energy fluence per pulse being greater than 3-5 J/cm2.
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8. A method for selectively removing a metal layer in a structure comprised of a plurality of metal and polymer layers, comprising the steps of:
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positioning said structure in the path of ultraviolet laser pulses, said structure including at least one layer of a metal and one layer of a polymer, irradiating said structure with ultraviolet laser pulses to remove said metal layer without substantial etching of said polymer layer, said ultraviolet laser pulses having a wavelength and energy fluence per pulse such that the rate of removal of said metal layer by said laser pulses is at least twice as rapid as the rate of removal of the polymer layer by said laser pulses, for each said laser pulse. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for selectively etching a metal layer in the presence of a polymer layer, where said metal layer has a thickness of several microns and said polymer layer also has a thickness of several microns, said polymer being comprised of a material which exhibits an etch depth/pulse versus energy fluence/pulse curve which begins to level off with increasing energy fluence beyond a fluence F=F0, when said polymer is ablatively photodecomposed by ultraviolet laser pulses having a wavelength in the range 100-400 nm,
said removal process including the step of applying a single pulse of said ultraviolet radiation, said pulse having an energy fluence sufficiently high to completely remove said metal layer, said fluence being greater than F0.
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18. A method for removing a copper layer located adjacent to a polyimide layer without substantial removal of said polyimide layer, said method including the steps of applying a number of pulses ≦
- 5 of ultraviolet radiation to said copper layer, said radiation having a wavelength in the range 100-400 nm and an energy fluence/pulse greater than about 3-5J/cm2.
- View Dependent Claims (19, 20, 21)
Specification