Formation of deep trench airgaps and related applications
AssigneeInteruniversitair Microelektronica Centrum vzw (IMEC)
InventorEddy Kunnen
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Abstract
A method for forming deep trench or via airgaps in a semiconductor substrate is disclosed comprising the steps of patterning a hole in the substrate, partly fill said hole with a sacrificial material (e.g. poly-Si), depositing spacers on the sidewalls of the unfilled part of the hole (e.g. TEOS) to narrow the opening, removing through said narrowed opening the remaining part of the sacrificial material (e.g. by isotropic etching) and finally sealing the opening of the airgap by depositing a conformal layer (TEOS) above the spacers. The method of forming an airgap is demonstrated successfully for use as deep trench isolation structures in BiCMOS devices.
Claims27
A method for forming a bipolar complementary metal oxide semiconductor device, the method comprising the steps of:
- patterning a trench having sidewalls in the substrate;
- depositing an oxide separating layer atop the sidewalls and bottom of the trench;
- depositing an extra oxide liner atop the oxide separating layer;
- forming a partially filled-in portion of the trench, wherein the partially filled-in portion comprises a sacrificial material, whereby a portion of the sidewalls is exposed and a portion of the sidewalls is covered by the sacrificial material;
- depositing spacers on the exposed portion of the sidewalls atop the extra oxide liner, whereby the spacers extend towards the filling material, whereby an opening to the trench is narrowed;
- removing the sacrificial material though the narrowed opening;
- sealing the opening by depositing a layer above the spacers, whereby an airgap is formed;
- and thereafter
- forming a first field area and a second field area inside the substrate a bipolar transistor in the substrate, wherein the airgap is situated between the first field area and the second field area and comprises part of an active area field isolation module in a bipolar complementary metal oxide semiconductor device thus obtained.
A method for forming a bipolar complementary metal oxide semiconductor device, the method comprising the steps of:
- patterning a trench having sidewalls in the substrate;
- depositing an oxide separating layer atop the sidewalls and bottom of the trench;
- depositing a nitride liner atop the oxide separating layer;
- forming a partially filled-in portion of the trench, wherein the partially filled-in portion comprises a sacrificial material, whereby a portion of the sidewalls is exposed and a portion of the sidewalls is covered by the sacrificial material;
- depositing spacers on the exposed portion of the sidewalls atop the extra oxide liner, whereby the spacers extend towards the filling material, whereby an opening to the trench is narrowed;
- removing the sacrificial material through the narrowed opening;
- sealing the opening by depositing a layer above the spacers, whereby an airgap is formed;
- and thereafter
- forming a first field area and a second field area inside the substrate a bipolar transistor in the substrate, wherein the airgap is situated between the first field area and the second field area and comprises part of an active area field isolation module in a bipolar complementary metal oxide semiconductor device thus obtained.
Dependencies are inferred from the claim text.