DEPOSITING TUNGSTEN INTO HIGH ASPECT RATIO FEATURES

• US 20110159690A1
• Filed: 01/28/2011
• Published: 06/30/2011
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Chandrashekar, Anand, Fellis, Aaron R., Danek, Michal, Chang, Sean, Humayun, Raashina
• Granted Patent: US 8,124,531 B2
• Time in Patent Office: Days
• US Class Current: 438/675
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/486 Via connections through the substrate with or without pins
• CPC Class Codes: H01L 21/76865 Selective removal of parts of the layer H01L21/76844 takes precedence
• CPC Class Codes: H01L 21/76876 for deposition from the gas phase, e.g. CVD
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material

Abstract

Methods and apparatuses for filling high aspect ratio features with tungsten-containing materials in a substantially void-free manner are provided. In certain embodiments, the method involves depositing an initial layer of a tungsten-containing material followed by selectively removing a portion of the initial layer to form a remaining layer, which is differentially passivated along the depth of the high-aspect ration feature. In certain embodiments, the remaining layer is more passivated near the feature opening than inside the feature. The method may proceed with depositing an additional layer of the same or other material over the remaining layer. The deposition rate during this later deposition operation is slower near the feature opening than inside the features due to the differential passivation of the remaining layer. This deposition variation, in turn, may aid in preventing premature closing of the feature and facilitate filling of the feature in a substantially void free manner.

Claims

1. A method of filling a high aspect ratio feature provided on a partially manufactured semiconductor substrate, the method comprising:

introducing a tungsten-containing precursor and a reducing agent into a processing chamber;

depositing a layer of a tungsten-containing material on the partially manufactured semiconductor substrate via a chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent, such that the layer partially fills the high aspect ratio feature;

introducing an activated etching material into the processing chamber;

removing a portion of the layer using the activated etching material to form a remaining layer;

reintroducing the tungsten-containing precursor and the reducing agent into the processing chamber; and

selectively depositing an additional layer of the tungsten-containing material on the partially manufactured semiconductor substrate via a chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent such that the additional layer is thicker inside the feature than near the feature opening.

2. The method of the claim 1, wherein the processing chamber is maintained at a pressure of less than 5 Torr the removing operation.

3. The method of the claim 1, wherein the processing chamber is maintained at a pressure of less than 2 Torr during the removing operation.

4. The method of claim 1, wherein the remaining layer is selectively passivated such that the passivation of the remaining layer is greater near the feature opening than inside the feature.

5. The method of claim 1, wherein the remaining layer is thinner near the feature opening than inside the feature.

6. The method of claim 1, wherein the remaining layer has a thickness of less than 10% of the feature opening.

7. The method of claim 1, wherein more tungsten-containing material is removed near the feature opening than inside the feature during the removing operation.

8. The method of claim 7, wherein, during the removing operation, a reduction in a thickness of the layer near the opening of the high aspect ratio feature is at least about 25% greater than inside the feature.

9. The method of claim 1, wherein selectively depositing the additional layer comprises filling in a substantially void-free manner at least a lower half of the high aspect ratio feature.

10. The method of claim 1, wherein the high aspect ratio feature has an aspect ratio of at least about 2.

11. The method of claim 1, wherein the removing operation is performed in a mass transport regime.

12. The method of claim 1, wherein the depositing, removing, and selective depositing operations are performed in different processing chambers maintained at different environmental conditions.

13. The method of claim 1, wherein the substrate has a second feature that is closed during the deposition operation and remains closed after the removal operation.

14. The method of claim 1, wherein the high aspect ratio feature is closed during the deposition operation and opens during the removal operation.

15. The method of claim 1 further comprising:

applying photoresist to the partially manufactured semiconductor substrate;

exposing the photoresist to light; and

patterning the photoresist to create a pattern and transferring the pattern to the partially manufactured semiconductor substrate.

16. A method of filling a high aspect ratio feature provided on a partially manufactured semiconductor substrate, the method comprising:

introducing a tungsten-containing precursor and a reducing agent into a processing chamber;

depositing a layer of a tungsten-containing material on the partially manufactured semiconductor substrate via a chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent, such that the layer partially fills the high aspect ratio feature;

introducing an activated etching material into the processing chamber; and

selectively removing a portion of the layer to form a remaining layer of the tungsten-containing material, the remaining layer having a varying level of passivation along a depth of the high aspect ratio feature and being more passivated near a feature opening than inside the feature.

17. The method of claim 16, wherein the level of passivation of the remaining layer at a particular depth is correlated to the amount of the tungsten-containing material removed from the layer of the tungsten-containing material at that depth.

18. A method of processing a partially manufactured semiconductor substrate, the method comprising:

providing the partially manufactured semiconductor substrate into a processing chamber, the partially manufactured semiconductor substrate comprising a high aspect ratio feature having a size of less than about 50 nanometers and an aspect ratio of at least about 4 and a protective layer deposited at least within the high aspect ratio feature;

introducing a tungsten-containing precursor and a reducing agent into the processing chamber;

depositing a layer of a tungsten-containing material on the partially manufactured semiconductor substrate via a chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent, wherein the layer has a thickness of less than about half the size of the high aspect ratio feature;

introducing an activated etching material into the processing chamber; and

removing a portion of the layer using the activated etching material at a pressure of less than 5 Torr for a period of time;

introducing the tungsten-containing precursor and the reducing agent into the processing chamber; and

selectively depositing an additional layer of the tungsten-containing material on the partially manufactured semiconductor substrate via the chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent such that an interior deposition rate inside the feature is at least twice higher than an exterior deposition rate near the feature opening, wherein the selective deposition is configured to fill at least a bottom half of the feature.

19. The method of claim 18 wherein the period of time is determined by the thickness of the layer.

20. The method of claim 18, wherein the size of the high aspect ratio feature is about 30 nanometers and a depth of the high aspect ratio feature is about 250 nanometers and wherein the period in the removing operation is between about 1 second and 10 seconds.

21. The method of the claim 18, wherein the exterior deposition rate is less than about 100 Angstroms per minute for at least first 30 seconds of the selective deposition.

22. A semiconductor processing apparatus for filling a high aspect ratio feature provided on a partially manufactured semiconductor substrate, the apparatus comprising:

a first processing chamber having one or more deposition stations for positioning the substrate, said first processing chamber configured to deposit a layer of a tungsten-containing material or an additional layer of the tungsten-containing material on the partially manufactured semiconductor substrate via a chemical vapor deposition reaction, said one or more deposition stations comprising a deposition heating element for controlling a temperature of the substrate during deposition;

a second processing chamber having one or more etching stations for positioning the substrate, said second processing chamber configured to selectively remove a portion of the layer, said one or more etching stations comprising an etching heating element for controlling the temperature of the substrate during etching; and

a controller comprising program instructions for;

introducing a tungsten-containing precursor and a reducing agent into the first processing chamber;

after introducing the tungsten-containing precursor and the reducing agent into the first processing chamber, introducing an activated etching material into the second processing chamber at a pressure of less than 5 Torr for a period of between about 1 second and 10 seconds; and

after introducing an activated etching material into the second processing chamber, introducing the tungsten-containing precursor and the reducing agent into the first processing chamber or another processing chamber.

23. The apparatus of claim 22, further comprising a wafer stepper.

24. A non-transitory computer machine-readable medium comprising program instructions for control of a semiconductor processing apparatus for filling a high aspect ratio feature provided on a partially manufactured semiconductor substrate, the program instructions comprising,

code for introducing the tungsten-containing precursor and the reducing agent into the first processing chamber;

code for introducing an activated etching material into the second processing chamber at a pressure of less than 5 Torr for a period of between about 1 second and 10 seconds; and

code for introducing the tungsten-containing precursor and the reducing agent into the first processing chamber or another processing chamber.