US 12,347,670 B2
Etching method
Delia Ristoiu, St. Ismier (FR); Pierre Bar, Grenoble (FR); and Francois Leverd, St. Ismier (FR)
Assigned to STMicroelectronics (Crolles 2) SAS, Crolles (FR)
Filed by STMicroelectronics (Crolles 2) SAS, Crolles (FR)
Filed on Sep. 8, 2022, as Appl. No. 17/940,758.
Application 17/940,758 is a division of application No. 16/709,251, filed on Dec. 10, 2019, granted, now 11,469,095.
Claims priority of application No. 1874151 (FR), filed on Dec. 26, 2018.
Prior Publication US 2023/0005735 A1, Jan. 5, 2023
Int. Cl. H01L 21/02 (2006.01); G02B 6/30 (2006.01); G02B 6/36 (2006.01); H01L 21/311 (2006.01); H01L 21/67 (2006.01)
CPC H01L 21/02019 (2013.01) [G02B 6/30 (2013.01); G02B 6/3644 (2013.01); G02B 6/3692 (2013.01); H01L 21/31116 (2013.01); H01L 21/67253 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An electronic device, comprising:
a stack of alternating layers including a bottom layer made solely of a first insulating material, a first layer made solely of a second insulating material which covers the bottom layer, a second layer made solely of the first insulating material which covers the first layer and a third layer made solely of the second insulating material which covers the second layer, wherein the bottom layer includes a first portion having a first thickness and a second portion outside of the first portion having a second thickness less than the first thickness; and
a cavity that traverses the stack of layers, wherein the cavity comprises:
a first portion of the cavity having a depth extending into said first layer but which does not reach an upper surface of the first portion of the bottom layer; and
a second portion of the cavity that extends completely through the first portion of the bottom layer, wherein the second portion of the cavity is vertically in line with the first portion of the bottom layer.