US2005003669A1PendingUtilityA1
HF vapor phase cleaning and oxide etching
Assignee: MASSACHUSETTS INST TECHNOLOGYPriority: Feb 5, 1999Filed: May 21, 2004Published: Jan 6, 2005
Est. expiryFeb 5, 2019(expired)· nominal 20-yr term from priority
H10P 50/283H10P 70/125
42
PatentIndex Score
0
Cited by
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0
Claims
Abstract
HF vapor processes are provided for etching oxide on a semiconductor substrate, cleaning a substrate, or cleaning a metal structure on a substrate. In the processes, a semiconductor substrate to be cleaned or having oxide to be etched is exposed to anhydrous hydrofluoric acid vapor and water vapor at a substrate temperature greater than about 40° C. Control of substrate temperature, hydrofluoric acid vapor pressure and water vapor pressure inhibits formation of liquid on the substrate and forms on the substrate a sub-monolayer of etch reactant and product molecules by adsorption of etch reactant and product molecules at less than about 95% of oxide adsorption sites.
Claims
exact text as granted — not AI-modified1 . A method for etching oxide on a semiconductor substrate, comprising exposing the oxide to anhydrous hydrofluoric acid vapor and water vapor at a substrate temperature greater than about 40° C., control of substrate temperature, hydrofluoric acid vapor pressure and water vapor pressure inhibiting formation of liquid on the substrate and forming on the substrate a sub-monolayer of etch reactant and product molecules by adsorption of etch reactant and product molecules at less than about 95% of oxide adsorption sites.
2 . The method of claim 1 wherein the semiconductor substrate comprises a silicon wafer and the oxide comprises silicon dioxide.
3 . The method of claim 1 wherein the substrate temperature, hydrofluoric acid vapor pressure, and water vapor pressure are controlled to etch the oxide at an etch rate of no more than about 100 Å/minute.
4 . The method of claim 3 wherein the substrate temperature, hydrofluoric acid vapor pressure, and water vapor pressure are controlled to etch the oxide at an etch rate of no more than about 50 Å/minute.
5 . The method of claim 1 wherein the substrate temperature, hydrofluoric acid vapor pressure, and water vapor pressure are controlled to etch the oxide at an etch rate, E.R., that is specified as:
E
.
R
.
=
(
1.059
×
10
12
ⅇ
-
15500
/
RT
×
1.79
×
10
-
9
ⅇ
13000
/
RT
P
HF
×
9.107
×
10
-
8
ⅇ
10500
/
RT
P
H
2
O
)
(
1
+
1.79
×
10
-
9
ⅇ
13000
/
RT
P
HF
+
9.107
×
10
-
8
ⅇ
10500
/
RT
P
H
2
O
)
2
where E.R. and pre-exponential factors are expressed in Å/min; where P H20 is partial pressure of water vapor and P HF is partial pressure of HF vapor, both in Torr; where R is ideal gas constant, where T is temperature, and where all activation energies are expressed as Kcal/mol.
6 . The method of claim 1 further comprising producing a positive electrical charge on the oxide prior to exposure of the oxide to the hydrofluoric acid vapor and water vapor.
7 . The method of claim 1 wherein the substrate exposure temperature is controlled to be greater than about 100° C.
8 . The method of claim 1 wherein the substrate exposure temperature is controlled by thermal conduction between the substrate and a substrate holder on which the substrate is supported.
9 . The method of claim 1 wherein the anhydrous hydrofluoric acid vapor and the water vapor are maintained at a temperature between about 30° C. and about 100° C. as they are delivered for exposure of the substrate.
10 . The method of claim 1 wherein the substrate is exposed to the anhydrous hydrofluoric acid vapor and the water vapor in a process chamber maintained at a temperature of at least about 60° C.
11 . The method of claim 1 wherein the substrate is first exposed only to the water vapor and then subsequently exposed to both the water vapor and the anhydrous hydrofluoric acid vapor at a specified start time for the oxide etching.
12 . The method of claim 1 wherein the water vapor is provided at a flow rate of between about 5 sccm and about 100 sccm.
13 . The method of claim 1 wherein the anhydrous hydrofluoric acid vapor is provided at a flow rate of between about 10 sccm and about 200 sccm.
14 . The method of claim 1 wherein the anhydrous hydrofluoric acid vapor is provided at a partial pressure of between about 2.5 Torr and about 100 Torr.
15 . The method of claim 1 wherein the water vapor is provided at a partial pressure of between about 1 Torr and about 50 Torr.
16 . A method for cleaning a semiconductor substrate, comprising exposing the substrate to anhydrous hydrofluoric acid vapor and water vapor at a substrate temperature greater than about 40° C., control of substrate temperature, hydrofluoric acid vapor pressure and water vapor pressure inhibiting formation of liquid on the substrate and forming on the substrate a sub-monolayer of cleaning reactant and product molecules by adsorption of cleaning reactant and product molecules at less than about 95% of substrate adsorption sites.
17 . The method of claim 16 wherein the substrate exposure temperature is controlled to be greater than about 100° C.
18 . The method of claim 16 wherein the substrate exposure temperature is controlled by thermal conduction between the substrate and a substrate holder on which the substrate is supported.
19 . The method of claim 16 wherein the anhydrous hydrofluoric acid vapor and the water vapor are maintained at a temperature of between about 30° C. and about 100° C. as they are delivered for exposure of the substrate.
20 . The method of claim 16 wherein the substrate is exposed to the anhydrous hydrofluoric acid vapor and the water vapor in a process chamber maintained at a temperature of at least about 60° C.
21 . The method of claim 16 wherein the water vapor is provided at a flow rate of between about 5 sccm and about 100 sccm.
22 . The method of claim 16 wherein the anhydrous hydrofluoric acid vapor is provided at a flow rate of between about 5 sccm and about 200 sccm.
23 . The method of claim 16 wherein the anhydrous hydrofluoric acid vapor is provided at a partial pressure of between about 2.5 Torr and about 100 Torr.
24 . The method of claim 16 wherein the water vapor is provided at a partial pressure of between about 1 Torr and about 50 Torr.
25 . The method of claim 16 wherein cleaning of a semiconductor substrate comprises cleaning of a metal contact region of the semiconductor substrate; and wherein exposure of the substrate to anhydrous hydrofluoric acid vapor and water vapor comprises exposure of the metal contact region to anhydrous hydrofluoric acid vapor and water vapor.
26 . A method for cleaning a metal structure on a semiconductor substrate, comprising exposing the metal structure to anhydrous hydrofluoric acid vapor and water vapor at a substrate temperature greater than about 40° C., control of substrate temperature, hydrofluoric acid vapor pressure, and water vapor pressure inhibiting formation of liquid on the substrate and forming on the substrate a sub-monolayer of cleaning reactant and product molecules by adsorption of cleaning reactant and product molecules at less than about 95% of substrate adsorption sites.
27 . The method of claim 26 wherein the substrate exposure temperature is controlled to be greater than about 100° C.
28 . The method of claim 26 wherein the substrate exposure temperature is controlled by thermal conduction between the substrate and a substrate holder on which the substrate is supported.
29 . The method of claim 26 wherein the anhydrous hydrofluoric acid vapor and the water vapor are maintained at a temperature of between about 30° C. and about 100° C. as they are delivered for exposure of the substrate.
30 . The method of claim 26 wherein the substrate is exposed to the anhydrous hydrofluoric acid vapor and the water vapor in a process chamber maintained at a temperature of at least about 60° C.
31 . The method of claim 26 wherein the water vapor is provided at a flow rate of between about 5 sccm and about 100 sccm.
32 . The method of claim 26 wherein the anhydrous hydrofluoric acid vapor is provided at a flow rate of between about 10 sccm and about 200 sccm.
33 . The method of claim 26 wherein the anhydrous hydrofluoric acid vapor is provided at a partial pressure of between about 2.5 Torr and about 100 Torr.
34 . The method of claim 26 wherein the water vapor is provided at a partial pressure of between about 1 Torr and about 50 Torr.
35 . The method of claim 26 wherein the metal structure comprises an aluminum structure.
36 . The method of claim 26 wherein cleaning of the metal structure comprises removing etch residue from the metal structure.Join the waitlist — get patent alerts
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