Tungsten feature fill

Abstract

Described herein are methods of filling features with tungsten and related systems and apparatus. The methods include inside-out fill techniques as well as conformal deposition in features. Inside-out fill techniques can include selective deposition on etched tungsten layers in features. Conformal and non-conformal etch techniques can be used according to various implementations. The methods described herein can be used to fill vertical features, such as in tungsten vias, and horizontal features, such as vertical NAND (VNAND) word lines. Examples of applications include logic and memory contact fill, DRAM buried word line fill, vertically integrated memory gate/word line fill, and 3-D integration with through-silicon vias (TSVs).

1 - 20 . (canceled) 
     
     
         21 . A method comprising:
 providing a substrate including a feature having one or more feature openings, feature sidewalls, and a feature interior,   conformally depositing a boron layer in the feature;   converting a portion of the boron layer in the feature to tungsten, leaving a remaining boron layer in the feature;   etching part of the tungsten in the feature without etching the remaining boron layer.   
     
     
         22 . The method of claim  1 , further comprising converting the remaining boron layer to tungsten. 
     
     
         23 . The method of claim  1 , wherein the boron layer is deposited to a thickness of greater than 10 nm. 
     
     
         24 . The method of claim  1 , wherein converting the portion of the boron layer comprises a reacting a tungsten precursor with the portion of the boron layer. 
     
     
         25 . The method of claim  1 , wherein the boron layer is converted to a thickness of 10 nm or less. 
     
     
         26 . The method of claim  1 , where etching part of the tungsten in the feature comprises exposing the feature to a plasma generated from NF 3 . 
     
     
         27 . The method of claim  1 , wherein etching part of the tungsten in the feature comprises exposing the feature to a F-based plasma. 
     
     
         28 . A method comprising:
 providing a substrate including a feature having one or more feature openings, feature sidewalls, and a feature interior,   conformally depositing a boron layer in the feature, the boron layer having a thickness of at least about 1.5 nm;   converting the entire thickness of the boron layer in the feature to tungsten; and   repeating conformal deposition and conversion operations one or more times to partially or wholly fill the feature with tungsten.   
     
     
         29 . The method of  claim 28 , wherein the boron layer has a thickness of no more than 100 nm. 
     
     
         30 . The method of  claim 28 , wherein the boron layer has a thickness of at least 3 nm. 
     
     
         31 . The method of  claim 28 , wherein the boron layer has a thickness of at least 5 nm 
     
     
         32 . The method of  claim 28 , wherein the conversion operation comprises volumetric expansion of material in the feature. 
     
     
         33 . The method of  claim 28 , wherein conformally depositing the boron layer comprises thermal decomposition of a boron-containing compound. 
     
     
         34 . The method of  claim 28 , wherein the conversion occurs at a temperature at least 300° C. and at most 400° C. and a pressure of about 40 Torr and wherein the boron layer is no more than 10 nm thick. 
     
     
         35 . A method comprising:
 providing a substrate including a feature having one or more feature openings, feature sidewalls, and a feature interior,   conformally depositing a fluorine-free tungsten nitride layer in the feature; and   converting the fluorine-free tungsten nitride layer to a fluorine-free tungsten layer.   
     
     
         36 . The method of  claim 35 , wherein converting the fluorine-free tungsten nitride layer to a fluorine-free tungsten layer comprises annealing the fluorine-free tungsten nitride layer at a temperature of at least 600° C. 
     
     
         37 . The method of  claim 35 , wherein conformally depositing a fluorine-free tungsten nitride layer in the feature is performed without closing off the feature to provide a flow path for volatized nitrogen (N 2 ) gas during the conversion. 
     
     
         38 . The method of  claim 35 , further comprising depositing tungsten on the fluorine-free tungsten layer. 
     
     
         39 . The method of  claim 35 , further comprising depositing tungsten nitride on the fluorine-free tungsten layer.