In a product-by-process claim, the patent applicant recites a series of process steps (i.e., a process for making a particular product) within the claim body, but it is actually the resulting product recited in the preamble that is protected, not the process itself. Thus, if some party created the exact same product using a completely different process, that party would still infringe a product-by-process patent.
The resulting product typically appears first in the claim's preamble, followed by language stating that the product is being prepared by a process. The claim below exemplifies a typical product-by-process claim:
"A wafer for production of an LED prepared by a process comprising the steps of:
(a) providing an n-GaAs single crystalline substrate;
(b) contacting the substrate with a melt comprising GaAs and Si in an amount of from 0.1 to 0.5 wt% at a temperature of from 900 to 950EC;
(c) cooling the melt while maintaining contact with the substrate at a rate of 5E/min to form a Si-doped GaAs epitaxial layer on the substrate comprising a pn junction; and
(d) separating the substrate from the melt."
The resulting product typically appears first in the claim's preamble, followed by language stating that the product is being prepared by a process. The claim below exemplifies a typical product-by-process claim:
"A wafer for production of an LED prepared by a process comprising the steps of:
(a) providing an n-GaAs single crystalline substrate;
(b) contacting the substrate with a melt comprising GaAs and Si in an amount of from 0.1 to 0.5 wt% at a temperature of from 900 to 950EC;
(c) cooling the melt while maintaining contact with the substrate at a rate of 5E/min to form a Si-doped GaAs epitaxial layer on the substrate comprising a pn junction; and
(d) separating the substrate from the melt."