EP0837497A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method for etching transistor gates using a hardmask
Assignee: Applied Materials Inc
•
Filing: 1997-09-25
•
Granted: —
•
Expires: 2017-09-25
Abstract
Abstract An etchant composition of nitrogen trifluoride and chlorine, preferably also including a passivation material such as hydrogen bromide, etches tungsten silicide-polysilicon gate layers with high selectivity to a thin underlying silicon oxide gate oxide layer to form straight wall, perpendicular profiles with low microloading and excellent profile control.
Inventors
- 👤 Ajay Kumar
- 👤 Jeffrey Chinn
- 👤 Shashank C. Deshmukh
- 👤 Weinan Jiang
- 👤 Rolf Adolf Guenter
- 👤 Bruce Minaee
- 👤 Mark Wiltse
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 09:10
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
45 words
An etch composition for etching transistor gates
on a silicon oxide layer comprising a layer of
tungsten silicide over a layer of polysilicon adjacent
to said silicon oxide layer, using a silicon oxide
hardmask, the etch composition comprising a mixture of
nitrogen trifluoride and chlorine.
Claim 2
Dependent Claim
21 words
An etch composition according to claim 1
additionally including one or more of hydrogen
bromide, nitrogen, oxygen and a carrier gas.
Claim 3
Dependent Claim
29 words
An etch composition according to claim 1 or claim
2 comprising from 75 to 85% by volume of chlorine and
from 15 to 25% by volume of nitrogen trifluoride.
Claim 4
Dependent Claim
36 words
An etch composition according to claim 1 or claim
2 comprising from 75% to 80% by volume of chlorine, 10
to 15% by volume of nitrogen trifluoride and 5 to 10%
by volume of hydrogen bromide.
Claim 5
Independent Claim
48 words
A method of etching transistor gates comprising
sequential layers of gate oxide, polysilicon and
tungsten silicide on a substrate and using a patterned
silicon oxide layer as a hardmask, the method
comprising etching the tungsten silicide and
polysilicon layers with an etchant composition
including nitrogen trifluoride and chlorine.
Claim 6
Dependent Claim
29 words
A method according to claim 5, wherein the
etchant composition comprises from 75% to 85% by
volume of chlorine and from 15 to 25% by volume of
nitrogen trifluoride.
Claim 7
Dependent Claim
17 words
A method according to claim 5 or claim 6, wherein
said etchant composition further includes hydrogen
bromide.
Claim 8
Dependent Claim
36 words
A method according to claim 7, wherein the
etchant composition comprises from 75% to 80 by volume
of chlorine, 10 to 15% by volume of nitrogen
trifluoride and 5 to 10% by volume of hydrogen
bromide.
Claim 9
Dependent Claim
42 words
A method according to any one of claim 6 to 8,
wherein said tungsten silicide layer is about 1500
angstroms thick, said polysilicon layer is about 1000
angstroms thick and said gate oxide layer is from
about 90 to 100 angstroms thick.
Claim 10
Independent Claim
23 words
A method according to any one of claims 6 to 9,
wherein the temperature of etching is chosen to obtain
the desired profile.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.