Etch process for dielectric materials comprising oxidized organo silane materials

• US 6,762,127 B2
• Filed: 08/23/2001
• Issued: 07/13/2004
• Est. Priority Date: 08/23/2001
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Chen, Hui, Tang, Sum-Yee Betty, Hsieh, Chang-Lin, Hung, Hoiman, Gregoratto, Ivano, Boiteux, Yves Pierre
• Primary Examiner(s): HITESHEW, FELISA CARLA
• Application Number:
  US09/938,432
• Publication Number:
  US 20030073321A1
• Time in Patent Office: 1,055 Days
• Field of Search: 438/702, 438/723, 438/743, 438/710, 216/67
• US Class Current: 438/702
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics
• CPC Class Codes: H01L 21/76807 for dual damascene structures
• CPC Class Codes: H01L 21/76808 involving intermediate temporary filling with material
• CPC Class Codes: H01L 2221/1036 Dual damascene with different via-level and trench-level dielectrics

Abstract

The present invention provides a novel etching technique for etching a layer of C-doped silicon oxide, such as a partially oxidized organo silane material. This technique, employing CH₂F₂/Ar chemistry at low bias and low to intermediate pressure, provides high etch selectivity to silicon oxide and improved selectivity to organic photoresist. Structures including a layer of partially oxidized organo silane material (1004) deposited on a layer of silicon oxide (1002) were etched according to the novel technique, forming relatively narrow trenches (1010, 1012, 1014, 1016, 1030, 1032, 1034 and 1036) and wider trenches (1020, 1022, 1040 and 1042). The technique is also suitable for forming dual damascene structures (1152, 1154 and 1156). In additional embodiments, manufacturing systems (1410) are provided for fabricating IC structures of the present invention. These systems include a controller (1400) that is adapted for interacting with a plurality of fabricating stations (1420, 1422, 1424, 1426 and 1428).

Claims

1. A method of plasma etching C-doped silicon oxide, the method comprising:

etching the C-doped silicon oxide inside an etch reactor employing plasma conditions including (1) flowing CH₂F₂ gas and inert gas into the reactor and (2) a reactor bias energy no greater than about 400 W.

3. The method of claim 1 further comprising plasma conditions wherein the second flow rate ranges from about 5 times to about 20 times higher than the first flow rate.

4. The method of claim 1 wherein:

a) the first flow rate ranges from about 20 sccm to about 40 sccm; and

b) the second flow rate ranges from about 200 sccm to about 400 sccm.

5. The method of claim 1 wherein the plasma conditions additionally comprise a plasma ionization density ranging from about 10¹⁰/cm³ to about 10¹¹/cm³.

6. The method of claim 1, wherein the etch reactor comprises an inductively coupled plasma reactor employing a separately controlled plasma source power and plasma bias power.

7. The method of claim 1 wherein the etch reactor is selected from the group consisting of reactors adapted for forming a plasma density ranging from about 10¹⁰/cm³ to about 10¹¹/cm³, RIE reactors and MERIE reactors.

8. The method of claim 1 wherein the C-doped silicon oxides comprises an oxidized organo silane layer including an oxidized organo silane compound that is formed by reacting an organo silane compound with an oxidizing compound.

9. The method of claim 8 wherein the oxidized organo silane layer comprises a carbon content of at least 1% by atomic weight.

10. The method of claim 9 wherein the organo silane compound is selected from the group consisting of methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane;

imethylsilanediol, diphenylsilane, diphenylsilanediol, methylphenylsilane, bis(methylsilano)methane, 1,2-bis(methylsilano)ethane, 1,3,5-trisilano-2,4,6-trimethylene, dimethyldimethoxysilane, diethyldiethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane, and fluorinated derivatives thereof.

11. The method of claim 10 wherein the organo silane compound is reacted with N₂O gas at plasma conditions sufficient to form the layer and wherein the plasma conditions additionally comprise:

a) a high frequency RF power density ranging from about 0.16 W/cm² to about 0.48 W/cm²; and

b) a sufficient amount of organo silane compound with respect to the N²O gas to provide a layer of material with a carbon content of at least 1% by atomic weight.

12. The method of claim 10 wherein the organo silane is reacted with O₂ gas at plasma conditions sufficient to form the layer and wherein the plasma conditions comprise:

a) a high frequency RF power density greater than about 0.03 W/cm²; and

b) a sufficient amount of organo silane compound with respect to the O₂ gas to provide a layer of material with a carbon content of at least 1% by atomic weight.

13. The method of claim 8 wherein the oxidizing compound selected from the group consisting of N₂O, O₂ and H₂O₂.

14. The method of claim 1 wherein the etch pattern is provided in an organic photoresist and wherein the method of etching comprises an etch selectivity of about 5 to the organic photoresist.

2. A method of plasma etching an etch pattern through a layer of C-doped silicon oxide, the method comprising:

a) depositing a photoresist layer on the C-doped silicon oxide layer;

b) forming an etch mask having the etch pattern in the photoresist layer;

c) etching the pattern through the C-doped silicon oxide layer inside an etch reactor, wherein etching the pattern comprises employing plasma conditions including (1) CH₂F₂ gas flowing into the reactor at a first predetermined flow rate, (2) inert gas flowing into the reactor at a second predetermined flow rate and (3) a reactor bias energy no greater than about 400 W.

15. A method of anisotropically plasma etching an etch pattern through a layer of C-doped silicon oxide of a first structure that is fabricated by depositing the C-doped silicon oxide layer on a layer of silicon oxide, the method comprising:

a) depositing a photoresist layer on the C-doped silicon oxide layer of the first structure;

b) forming an etch mask having the etch pattern in the photoresist layer;

c) positioning the first structure having the etch mask inside an etch reactor;

d) exposing the C-doped silicon oxide layer to a plasma including ;

(1) CH₂F₂ gas flowing into the reactor at a first predetermined flow rate, (2) inert gas flowing into the reactor at a second predetermined flow rate and (3) a reactor bias energy no greater than about 400 W; and

e) continuing exposing to the plasma until the pattern has been etched through the C-doped silicon oxide layer wherein a second structure is formed having a cavity in the C-doped silicon oxide layer such that the cavity exposes the silicon oxide layer as defined by the etch pattern.

16. The method of claim 15 wherein the method of etching comprises an etch selectivity to silicon oxide ranging from about 8 to about 10.

17. The method of claim 15 comprising an etch front having an etch front flatness no greater than about 0.1.

18. The method of claim 15 wherein the C-doped silicon oxide layer comprises a layer thickness of at least about 300 nm.

19. The method of claim 18 wherein a substantially flat etch front is formed on the silicon oxide layer.

20. The method of claim 15 wherein the C-doped silicon oxide layer comprises an oxidized organo silane compound that is formed by oxidizing an organo silane compound selected from the group consisting of methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane;

dimethylsilanediol, diphenylsilane, diphenylsilanediol, methyiphenylsilane, bis(methylsilano)methane, 1,2-bis(methylsilano)ethane, 1,3,5-trisilano-2,4,6-trimethylene, dimethyldimethoxysilane, diethyldiethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, hexamethyldisiloxane, octamethylcyclotetrasiloxane, and fluorinated derivatives thereof, such that the oxidized compound comprises a carbon content of at least 1% by atomic weight.

21. The method of claim 15 wherein the silicon oxide layer is selected from the group consisting of SiO₂, related non-stoichiometric materials SiOx and related dielectric silica glasses exhibiting similar chemistry as SiO₂.

22. The method of claim 15 wherein the reactor is selected from the group consisting of reactors adapted for forming a plasma density ranging from about 10¹⁰/cm³ to about 10¹¹/cm³, RIE reactors and MERIE reactors.

23. A method of plasma etching a trench and a via in a first structure having a substrate upon which are sequentially formed a silicon oxide layer and a C-doped silicon oxide layer, the method comprising:

a) depositing a first photoresist layer on the C-doped silicon oxide layer;

b) forming a first etch mask having an via pattern in the first photoresist layer;

c) anisotropically etching the via pattern through the C-doped silicon oxide layer and the silicon oxide layer, forming a cavity that exposes the substrate;

d) removing the first photoresist, wherein a second structure is formed;

e) forming a second photoresist layer on the second structure, wherein the second photoresist layer includes a second etch mask having a trench pattern that overlays the cavity;

f) anisotropically etching the trench pattern through the C-doped silicon oxide layer forming a trench exposing the underlying via and the underlying silicon oxide layer, wherein etching the trench pattern comprises etching with a plasma including;

(1) CH₂F₂ gas flowing at a first predetermined flow rate, (2) inert gas flowing at a second predetermined flow rate and (3) plasma conditions comprising (i) a bias energy no greater than about 400 W; and

g) removing the second photoresist, wherein a third structure is formed that is adapted for forming a dual damascene structure therein.

24. The method of claim 23 wherein the C-doped silicon oxide comprises a layer thickness of at least about 300 nm, thereby forming a fourth structure.

25. The method of claim 23 comprising a trench etch front having an etch front flatness no greater than about 0.1.

26. A method of forming a structure on a substrate, the method comprising:

a) depositing a silicon nitride layer on the substrate;

b) depositing a first adhesive layer on the silicon nitride layer;

c) depositing a silicon oxide layer on the first adhesive layer;

d) depositing a second adhesive layer on the silicon oxide layer;

e) depositing a layer of C-doped silicon oxide on the second adhesive layer;

f) depositing a first photoresist layer on the C-doped silicon oxide layer;

g) developing a via etch pattern in the photoresist layer;

h) anisotropically etching the via etch pattern such that a hole is formed that exposes the silicon nitride layer;

i) removing the first photoresist;

j) depositing a second photoresist layer on the material layer;

k) developing a trench pattern in the second photoresist layer such that the trench pattern overlays the hole;

l) anisotropically etching the trench pattern through the C-doped silicon oxide layer and the second adhesive layer, comprising employing a plasma including (1) a gas mixture comprising CH₂F₂ and inert gas and (2) plasma conditions including

(i) a bias energy range of about 250 to about 500 W and (ii) a pressure range of about 10 mT to about 90 mT, wherein a trench is formed overlaying a via and the silicon oxide layer.

27. The method of claim 26 wherein etching the trench pattern additionally comprises forming a trench having a substantially flat etch front.

28. A structure formed according to the method of claim 26.