Silicon nitride passivation layer for covering high aspect ratio features

• US 8,563,095 B2
• Filed: 03/15/2010
• Issued: 10/22/2013
• Est. Priority Date: 03/15/2010
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Rajagopalan, Nagarajan, Han, Xinhai, Yamase, Ryan, Park, Ji Ae, Patel, Shamik, Nowak, Thomas, Naik, Mehul, Park, Heung Lak, Ding, Ran, Kim, Bok Hoen, Cui, Zhengjiang David
• Primary Examiner(s): CHEN, BRET P
• Application Number:
  US12/724,396
• Publication Number:
  US 20110223765A1
• Time in Patent Office: 1,317 Days
• Field of Search: 427/535, 427/579, 427/96.8, 427/98.8, 427/99.2, 427/255.393, 427/255.394
• US Class Current: 427/579
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/45523 Pulsed gas flow or change of composition over time
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/56 Encapsulations, e.g. encapsulation layers, coatings
• CPC Class Codes: H01L 21/76832 Multiple layers
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence
• CPC Class Codes: H01L 2224/1181 Cleaning, e.g. oxide removal step, desmearing
• CPC Class Codes: H01L 2224/1182 Applying permanent coating, e.g. in-situ coating
• CPC Class Codes: H01L 2224/11827 Chemical vapour deposition [CVD], e.g. laser CVD
• CPC Class Codes: H01L 2224/11831 involving a chemical process, e.g. etching the bump connector
• CPC Class Codes: H01L 2224/119 Methods of manufacturing bump connectors involving a specific sequence of method steps
• CPC Class Codes: H01L 2224/11901 with repetition of the same manufacturing step
• CPC Class Codes: H01L 2224/13025 the bump connector being disposed on a via connection of the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/13147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13562 : On the entire exposed surface of the core
• CPC Class Codes: H01L 2224/1358 : being stacked
• CPC Class Codes: H01L 2224/13583 : Three-layer coating
• CPC Class Codes: H01L 2224/13687 : Ceramics, e.g. crystalline carbides, nitrides or oxides glass ceramics H01L2224/13688
• CPC Class Codes: H01L 2224/742 : Apparatus for manufacturing bump connectors
• CPC Class Codes: H01L 23/291 : Oxides or nitrides or carbides, e.g. ceramics, glass
• CPC Class Codes: H01L 23/3171 : the coating being directly applied to the semiconductor body, e.g. passivation layer H01L23/3178 takes precedence
• CPC Class Codes: H01L 24/11 : Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 : of an individual bump connector
• CPC Class Codes: H01L 24/742 : Apparatus for manufacturing bump connectors
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0001 : Technical content checked by a classifier
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/05042 : Si3N4
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/351 : Thermal stress

Abstract

A method of forming a passivation layer comprising silicon nitride on features of a substrate is described. In a first stage of the deposition method, a dielectric deposition gas, comprising a silicon-containing gas and a nitrogen-containing gas, is introduced into the process zone and energized to deposit a silicon nitride layer. In a second stage, a treatment gas, having a different composition than that of the dielectric deposition gas, is introduced into the process zone and energized to treat the silicon nitride layer. The first and second stages can be performed a plurality of times.

Claims

1. A method of forming a passivation layer on features of a substrate, the passivation layer comprising a silicon nitride layer, and the method comprising:

(a) providing a substrate having a plurality of high aspect ratio features in a process zone, the high aspect ratio features comprising (i) interconnects or connector bumps, and (ii) a metal-containing material;

(b) in an initial soaking stage, providing a soaking gas into the process zone to deposit a thin silicon nitride layer on the substrate, the soaking gas comprising silane, ammonia and nitrogen;

(c) in a first stage, (i) forming in the process zone, a deposition gas comprising a silicon-containing gas and a nitrogen-containing gas by introducing a flow of the silicon-containing gas into the process zone and introducing a flow of the nitrogen-containing gas into the process zone, and (ii) energizing the deposition gas to deposit a silicon nitride layer on the features;

(d) in a second stage, forming in the process zone, a treatment gas by stopping the flow of the silicon-containing gas while continuing the flow of the nitrogen-containing gas, and energizing the treatment gas to treat the silicon nitride layer; and

(e) performing the first and second stages a plurality of times.

2. A method according to claim 1 wherein the silicon-containing gas comprises silane and the nitrogen-containing gas comprises ammonia and nitrogen.

3. A method according to claim 2 comprising providing a ratio of SiH₄:

NH₃;

N₂ of from about 1;

1;

8 to about 2;

1;

20.

4. A method according to claim 1 wherein (c) comprises setting process conditions to deposit a silicon nitride layer having a refractive index n that is less than 1.88, as measured using ellipsometry at a wavelength of 633 nm.

5. A method according to claim 1 wherein (c) comprises setting process conditions to deposit a silicon nitride layer having a wet etch rate ratio WERR of etching the passivation layer of silicon nitride relative to etching a thermal oxide layer that is less than 5.2.

6. A method according to claim 1 comprising maintaining the substrate at a temperature of from about 180°

C. to about 550°

C.

7. A method according to claim 1 wherein the high aspect ratio features further comprise any one of:

(i) silicon vias;

or

(ii) oxide structures.

8. A method according to claim 1 comprising an initial cleaning stage comprising (i) providing a cleaning gas comprising a hydrogen-containing gas into the process zone, and (ii) energizing the cleaning gas to form an energized cleaning gas.

9. A method according to claim 8 wherein the hydrogen-containing gas comprises (i) H₂, (ii) N₂ and NH₂, (iii) H₂O, or (iv) SiH₄.

10. A method according to claim 8 wherein the cleaning gas is provided in a volumetric flow rate of from about 100 sccm to about 18 liters/minute.

11. A method according to claim 8 wherein the cleaning gas comprises:

(1) H₂ in a volumetric flow rate of from about 500 to about 3000 sccm;

(2) NH₃ in a volumetric flow rate of from about 50 to about 300 sccm and N₂ in a volumetric flow rate of from about 1000 L/min to 30,000 L/min;

or

(3) H₂ in a volumetric flow rate of from about 500 to about 3000 sccm and NH₃ in a volumetric flow rate of from about 50 to about 300 sccm.

12. A method according to claim 8 wherein the cleaning gas is energized by coupling RF energy to process electrodes which are about the process zone at a power of from about 50 to about 700 Watts.

13. A method according to claim 1 wherein the soaking stage comprises at least one of:

(1) maintaining the substrate at a temperature of from about 100 to about 240°

C.;

(2) maintaining the soaking gas at a pressure of from about 1 to about 5 Torr;

or

(3) performing the soaking stage for from about 5 to about 30 seconds.

14. A method according to claim 1 wherein the soaking gas comprises silane in a volumetric flow rate of from about 200 to about 800 sccm, ammonia in a flow rate of from about 200 to about 800 sccm, and nitrogen in a flow rate of from about 4000 to about 12,000 sccm.

15. A method according to claim 1 comprising depositing a conformal liner on the features by:

(1) introducing into the process zone, a liner gas comprising (i) SiH₄, NH₃ and N₂;

(ii) trisilyamine, NH₃, and N₂;

(iii) SiH₄ or N₂;

or (iv) trisilyamine and a nitrogen-containing gas; and

(2) energizing the liner gas to form a plasma to deposit a conformal liner on the features of the substrate, the conformal liner having a thickness greater than approximately 100 Å and

a tensile stress of at least about 100 MPa.

16. A method according to claim 15 comprising depositing a conformal liner comprising a silicon nitride layer having a stress gradient through the thickness of the layer.

17. A method according to claim 15 comprising depositing a conformal liner by controlling the flow rate of SiH₄ from a high flow rate to a low flow rate during the deposition process, and changing the rate of applying RF power applied to a pair of process electrodes about the process zone.

18. A method according to claim 15 comprising depositing a liner comprising a plurality of discrete silicon nitride layers having different stress levels.

19. A method according to claim 15 comprising depositing a silicon nitride layer by sequentially depositing a silicon nitride layer and partially etching away the deposited silicon nitride layer.

20. A method according to claim 19 comprising etching away the deposited layer to change the reentrant profile at a bottom corner of the features.

21. A method according to claim 1 wherein the process zone comprises a pair of process electrodes, and wherein (c) comprises applying a first power level to the process electrodes, and thereafter, applying a second power level to the process electrodes, the second power level being higher than the first power level.

22. A method according to claim 21 wherein the second power level is at least about 100 Watts higher than the first power level.

23. A method of forming a passivation layer on features of a substrate, the passivation layer comprising a silicon nitride layer, and the method comprising:

(a) providing a substrate having a plurality of high aspect ratio features in a process zone, the high aspect ratio features comprising (i) interconnects or connector bumps, and (ii) a metal-containing material;

(b) in an initial soaking stage, providing a soaking gas into the process zone to deposit a thin silicon nitride layer on the substrate, the soaking gas comprising silane, ammonia and nitrogen;

(c) in a first stage, introducing into the process zone, a deposition gas comprising a silicon-containing gas and a nitrogen-containing gas and energizing the deposition gas to deposit the silicon nitride layer on the features of the substrate;

(d) in a second stage, introducing an etching gas into the process zone and energizing the etching gas to partially etch the deposited layer; and

(e) performing the first and second stages a plurality of times.

24. A method according to claim 23 wherein the etching gas comprises fluorine.

25. A method according to claim 24 wherein (d) comprises etching the silicon nitride layer to modify a reentrant profile of the silicon nitride layer at a bottom of corner of the features.

26. A method according to claim 23 wherein the process zone comprises a pair of process electrodes, and wherein (c) comprises applying a first power level to the process electrodes, and thereafter, applying a second power level to the process electrodes, the second power level being higher than the first power level.

27. A method according to claim 26 wherein the second power level is at least about 100 Watts higher than the first power level.

28. A method of forming a passivation layer on features of a substrate, the passivation layer comprising a silicon nitride layer and having a stress gradient through a thickness of the passivation layer, and the method comprising:

(a) providing a substrate having a plurality of high aspect ratio features in a process zone, the high aspect ratio features comprising (i) interconnects or connector bumps, and (ii) a metal-containing material;

(b) in an initial soaking stage, providing a soaking gas into the process zone to deposit a thin silicon nitride layer on the substrate, the soaking gas comprising silane, ammonia and nitrogen;

(c) introducing into the process zone, a first deposition gas comprising a silicon-containing gas and a nitrogen-containing gas, the first deposition gas having a first ratio of silicon-containing component to nitrogen-containing component;

(d) energizing the first deposition gas to deposit a first silicon nitride layer on the features of the substrate, which comprises a first ratio of silicon to nitrogen through the thickness of the layer;

(e) introducing into the process zone, a second deposition gas comprising a silicon-containing gas and a nitrogen-containing gas, the second deposition gas having a second ratio of silicon-containing component to nitrogen-containing component which is less than the first ratio; and

(f) energizing the second deposition gas to deposit a second silicon nitride layer on the features of the substrate, which comprises a second ratio of silicon to nitrogen through the thickness of the layer.

29. A method according to claim 28 wherein the first ratio is less than about 100:

1 and the second ratio is at least about 1;

1.

30. A method of forming a passivation layer on features of a substrate, the passivation layer comprising a silicon nitride layer and a stress gradient through a thickness of the layer, and the method comprising:

(a) providing a substrate having a plurality of features in a process zone;

(b) introducing into the process zone, a first deposition gas comprising a silicon-containing gas and a nitrogen-containing gas;

(c) energizing the first deposition gas by applying a first power level to a pair of process electrodes to deposit the silicon nitride layer on the features of the substrate;

(d) introducing into the process zone, a second deposition gas comprising a silicon-containing gas and a nitrogen-containing gas; and

(e) energizing the second deposition gas by applying a second power level to the pair of process electrodes, the second power level being higher than the first power level, to deposit the silicon nitride layer on the features of the substrate.

31. A method according to claim 30 wherein the second power level is at least about 100 Watts higher than the first power level.

32. A method according to claim 30 wherein the first power level is at least about 100 Watts and the second power level is at least about 500 Watts.

33. A method according to claim 30 wherein the silicon-containing gas comprises silane and the nitrogen-containing gas comprises ammonia and nitrogen.

34. A method according to claim 30 further comprising forming in the process zone, a treatment gas by stopping the flow of the silicon-containing gas while continuing the flow of the nitrogen-containing gas, and energizing the treatment gas to treat the silicon nitride layer.

35. A method according to claim 30 further comprising an initial soaking stage in which the substrate is maintained at a temperature while a soaking gas comprising silane is introduced into the process zone.