US5965463A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silane etching process
Assignee: Applied Materials Inc
•
Filing: 1997-07-03
•
Granted: 1999-10-12
•
Expires: 2017-07-03
Abstract
Abstract A low-temperature process for selectively etching oxide with high selectivity over silicon in a high-density plasma reactor. The principal etching gas is a hydrogen-free fluorocarbon, such as C2F6 or C4F8, to which is added a silane or similar silicon-bearing gas, e.g., the monosilane SiH4. The fluorocarbon and silane are added in a ratio within the range of 2 to 5, preferably 2.5 to 3. The process provides high polysilicon selectivity, high photoresist facet selectivity, and steep profile angles. Selectivity is enhanced by operating at high flow rates. Silicon tetrafluoride may be added to enhance the oxide etching rate. The process may operate at temperatures of chamber parts below 180 DEG C. and even down to 120 DEG C. The process enables the fabrication of a bi-level contact structure with a wide process window.
Inventors
- 👤 Chunshi Cui
- 👤 Robert W. Wu
- 👤 Gerald Zheyao Yin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:28
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32431; H01J37/32798; H01J37/32853; H01J37/32871; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
99 words
A process for etching a substrate, comprising: placing said substrate within a plasma reactor chamber including a silicon-based scavenging surface exposed to a plasma within said chamber; admitting into said chamber a processing gas comprising a first gas comprising a silane and a second gas comprising fluorine and carbon in a ratio of flow rates between said hydrogen-free fluorocarbon and said silane lying with a range of between 2 and 5: and exciting said processing gas into said plasma to thereby etch said substrate whereby an oxide of said substrate is etched preferentially to an underlying material comprising silicon.
Claim 2
Dependent Claim
99 words
A process for etching a substrate, comprising: placing said substrate within a plasma reactor chamber including a silicon-based scavenging surface exposed to a plasma within said chamber; admitting into said chamber a processing gas comprising a first gas comprising a silane and a second gas comprising fluorine and carbon in a ratio of flow rates between said hydrogen-free fluorocarbon and said silane lying with a range of between 2 and 5: and exciting said processing gas into said plasma to thereby etch said substrate whereby an oxide of said substrate is etched preferentially to an underlying material comprising silicon.
Claim 3
Dependent Claim
11 words
The process of claim 1, wherein said first gas comprises monosilane.
Claim 4
Dependent Claim
14 words
The process of claim 1, wherein said processing gas additionally comprises SiF 4 .
Claim 5
Dependent Claim
13 words
The process of claim 1, wherein said second gas comprises a hydrogen-free fluorocarbon.
Claim 6
Dependent Claim
14 words
The process of claim 1, wherein said fluorocarbon comprises C 2 F 6 .
Claim 7
Dependent Claim
14 words
The process of claim 1, wherein said fluorocarbon comprises C 4 F 8 .
Claim 8
Dependent Claim
13 words
The process of claim 1, wherein said range extends between 2.5 and 4.
Claim 9
Dependent Claim
13 words
The process of claim 7, wherein said range extends between 2.5 and 3.
Claim 10
Dependent Claim
23 words
The process of claim 8, wherein said flow rate of said fluorocarbon is greater than 55 sccm normalized to a 20 liter chamber.
Claim 11
Dependent Claim
30 words
The process of claim 1, wherein said admitting steps flows said fluorocarbon into said chamber at a flow rate of greater than 55 sccm normalized to a 20 liter chamber.
Claim 12
Dependent Claim
25 words
The process of claim 1, further comprising controlling a temperature of said silicon-based scavenging surface to an operating temperature of no more than 200° C.
Claim 13
Dependent Claim
14 words
The process of claim 11, wherein said operating temperature is less than 150° C.
Claim 14
Dependent Claim
72 words
A process for etching a substrate, comprising: placing s aid substrate within a plasma reactor chamber; admitting into said chamber a processing gas comprising a hydrogen-free fluorocarbon gas and a silane gas in a ratio of flow rates between said fluorocarbon gas and said silane gas lying within a range of between 2 and 5; and exciting said processing gas within said plasma reactor chamber into a plasma to etch said substrate.
Claim 15
Dependent Claim
72 words
A process for etching a substrate, comprising: placing s aid substrate within a plasma reactor chamber; admitting into said chamber a processing gas comprising a hydrogen-free fluorocarbon gas and a silane gas in a ratio of flow rates between said fluorocarbon gas and said silane gas lying within a range of between 2 and 5; and exciting said processing gas within said plasma reactor chamber into a plasma to etch said substrate.
Claim 16
Dependent Claim
13 words
The process of claim 13, wherein said range extends between 2.5 and 4.
Claim 17
Dependent Claim
13 words
The process of claim 14, wherein said range extends between 2.5 and 3.
Claim 18
Dependent Claim
24 words
The process of claim 15, wherein said flow rate of said fluorocarbon gas is greater than 55 sccm normalized to a 20 liter chamber.
Claim 19
Dependent Claim
24 words
The process of claim 13, wherein said flow rate of said fluorocarbon gas is greater than 55 sccm normalized to a 20 liter chamber.
Claim 20
Dependent Claim
23 words
The process of claim 13, further comprising maintaining all walls of said chamber at an operating temperature of no more than 200° C.
Claim 21
Dependent Claim
14 words
The process of claim 18, wherein said operating temperature is less than 150° C.
Claim 22
Dependent Claim
22 words
The process of claim 19, wherein said wall comprise at least a portion having a composition selected from silicon and silicon carbide.
Claim 23
Dependent Claim
34 words
The process of claim 13, wherein said substrate comprises a first layer comprising silicon oxide overlying a second layer comprising essentially silicon, wherein said processing gas preferentially etches said silicon oxide over said silicon.
Claim 24
Dependent Claim
53 words
A process of etching an oxide layer, comprising the steps of: positioning a substrate having an silicon oxide layer formed thereon within a plasma reactor chamber; flowing into said chamber an etching gas comprising silane, silicon tetrafluoride, and a fluorocarbon; and exciting said etching gas into a plasma to thereby etch said substrate.
Claim 25
Dependent Claim
53 words
A process of etching an oxide layer, comprising the steps of: positioning a substrate having an silicon oxide layer formed thereon within a plasma reactor chamber; flowing into said chamber an etching gas comprising silane, silicon tetrafluoride, and a fluorocarbon; and exciting said etching gas into a plasma to thereby etch said substrate.
Claim 26
Dependent Claim
12 words
The process of claim 22, wherein said fluorocarbon is a hydrogen-free fluorocarbon.
Claim 27
Dependent Claim
30 words
The process of claim 23, wherein said flowing step flows said silane and said fluorocarbon into said chamber at respective flow rates in a ratio of between 2 and 5.
Claim 28
Dependent Claim
152 words
A process of optimized etching of an oxide layer, comprising the steps of: positioning a series of substrates having an silicon oxide layer formed thereon within a plasma reactor chamber; for each of said substrates flowing into said chamber an etching gas formed at least in part by a respective combination of a first flow rate of silane and a second flow rate of a fluorocarbon, said combinations of first and second flow rates differing between said substrates; exciting said etching gas into a plasma to thereby etch said each substrate; measuring for each of said substrates a respective oxide etching rate and a selectivity of etching silicon oxide over polysilicon; determining a preferred range of ratios of first and second flow rates from said measured oxide etching rates and said measured selectivities; and determining a minimum flow rate of one of said first and second flow rates from said measured selectivities.
Claim 29
Dependent Claim
152 words
A process of optimized etching of an oxide layer, comprising the steps of: positioning a series of substrates having an silicon oxide layer formed thereon within a plasma reactor chamber; for each of said substrates flowing into said chamber an etching gas formed at least in part by a respective combination of a first flow rate of silane and a second flow rate of a fluorocarbon, said combinations of first and second flow rates differing between said substrates; exciting said etching gas into a plasma to thereby etch said each substrate; measuring for each of said substrates a respective oxide etching rate and a selectivity of etching silicon oxide over polysilicon; determining a preferred range of ratios of first and second flow rates from said measured oxide etching rates and said measured selectivities; and determining a minimum flow rate of one of said first and second flow rates from said measured selectivities.
Claim 30
Dependent Claim
58 words
The process of claim 25, further comprising etching a plurality of substrates while flowing into said chamber said etching gas formed according to respective first and second values of said first and second flow rates having ratios within said preferred range and conforming to said minimum flow rate of said one of said first and second flow rates.
References Cited (Backward Citations)
US4213818A
Cited
US5556501A
Cited
US5354421A
Cited
US5266154A
Cited
US5312518A
Cited
EP0552490A1
Cited
EP0552491A1
Cited
US5423945A
Cited
US5477975A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-10-11 | 2003-04-12 | 2003-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-10-11 | 2007-04-12 | 2007-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-10-11 | 2011-04-12 | 2011-10-12 | $7700.00 | Window Closed / Lapsed |