US 11,756,783 B1
Method for creating cavities in silicon carbide and other semiconductor substrates
Eric Prophet, Malibu, CA (US); Joel Wong, Agoura Hills, CA (US); and Florian G. Herrault, Agoura Hills, CA (US)
Assigned to HRL LABORATORIES, LLC, Malibu, CA (US)
Filed by HRL Laboratories, LLC, Malibu, CA (US)
Filed on Jun. 11, 2021, as Appl. No. 17/345,932.
Claims priority of provisional application 63/067,511, filed on Aug. 19, 2020.
Int. Cl. H01L 21/02 (2006.01); H01L 21/268 (2006.01); B23K 26/40 (2014.01); B23K 101/40 (2006.01)
CPC H01L 21/02035 (2013.01) [B23K 26/40 (2013.01); H01L 21/02013 (2013.01); H01L 21/02016 (2013.01); H01L 21/268 (2013.01); B23K 2101/40 (2018.08)] 24 Claims
OG exemplary drawing
 
1. A method for creating at least one cavity in a semiconductor substrate, wherein the at least one cavity has a cross section of a desired shape and extends through the semiconductor substrate, wherein the semiconductor substrate comprises at least a top side, an opposed backside and a substrate thickness as measured from the top side to the backside, and wherein the semiconductor substrate comprises a semiconductor material that makes it susceptible to formation of surface or subsurface cracks when the at least one cavity is created solely by mechanical milling, the method comprising the steps of:
(a) partially ablating the semiconductor substrate from the top side with a laser to form a trench in the semiconductor substrate surrounding a cross section of the semiconductor material having the desired shape, wherein the trench extends to a laser ablation depth that covers a major portion of the substrate thickness and leaves only a minor portion of the substrate thickness remaining unablated below the semiconductor material surrounded by the trench formed by the partial ablating;
(b) machining the backside of the semiconductor substrate partially ablated in step (a) to reduce the semiconductor substrate to a final thickness that is equal to or less than the laser ablation depth whereby to form a plug of the semiconductor material unattached to a remainder of the semiconductor substrate; and
(c) removing the plug of semiconductor material from the semiconductor substrate to form the at least one cavity with cross section of desired shape extending through the semiconductor substrate.