On the Mechanism of the Step Coverage of Blanket Tungsten Chemical Vapor Deposition

The influence of adding dichlorosilane (SiH 2 Cl 2 ) to the silane (SiH 4 )-based reduction reaction of tungsten hexafluoride (WF 6 ) has been investigated to enhance the properties of this chemical vapor deposition process, especially the control of the growth rate. The growth rate of tungsten by the reduction reaction based on SiH 4 and SiH 2 Cl 2 has been measured. It is shown that the kinetics of the silane-dichlorosilane process can be characterized by a surface reaction limitation. The sole effect of the SiH 2 Cl 2 in the process is blocking of surface sites by preferential absorption, thereby reducing the growth rate of the tungsten film.

Section: Methodsmentioning

confidence: 99%

“…The temperature dependence of b is given by Eq. 4 [4] where Q ads is the adsorption enthalpy of the species. The area available for the deposition of tungsten is reduced by a factor (1-⌰).…”

Section: Effect Of Dichlorosilane On the Sih 4 W-cvd Process-by Addingmentioning

confidence: 99%

Influence of SiH2 CI 2 on the Kinetics of the Chemical Vapor Deposition of Tungsten by SiH4 Reduction of WF 6

Jongste

Oosterlaken

Janssen

et al. 1999

“…The deposition temperature of the ALD-WN x film was fixed at 300°C. The traditional W-plug deposition process is composed of two steps; 25 W nucleation and W-plug fill. Prior to W nucleation, TiN is typically deposited as a nucleation/barrier layer.…”

Section: D438mentioning

confidence: 99%

Characteristics of ALD Tungsten Nitride Using B2H6, WF6, and NH3 and Application to Contact Barrier Layer for DRAM

Kim

Kim²,

Lee³

et al. 2007

Tungsten nitride ͑WN x ͒ thin films were grown by atomic layer deposition ͑ALD͒ within the temperature range of 200-350°C from diborane ͑B 2 H 6 ͒, tungsten hexafluoride ͑WF 6 ͒, and ammonia ͑NH 3 ͒ for application to a contact barrier layer in dynamic random access memory ͑DRAM͒. Herein, B 2 H 6 was used as an additional reducing agent to produce a low-resistivity ALD-WN x film, and its resistivity was in the range of 300-410 ⍀ cm, depending on the deposition conditions for the ϳ10 nm thick film. An increase in the growth rate was observed with increasing deposition temperature, but an almost constant growth rate of ϳ0.28 nm/cycle was obtained in the temperature range from 275 to 300°C. The properties of the as-deposited film, including the resistivity, W/N ratio, density, B and F impurity content, and phase, were affected by the deposition temperature and B 2 H 6 flow rate during the process. As the deposition temperature and B 2 H 6 flow rate increased, the W/N ratio and film density increased and the impurity content decreased, leading to a reduction in the resistivity of the film. An increased W/N ratio was found to be favorable to the formation of a face-centered-cubic ␤-W 2 N phase. Excellent step coverage was obtained even on a 0.14 m diameter contact hole with an aspect ratio of 16:1. The ALD-WN x film in this study was thermally stable to annealing at 800°C for 30 min, but after annealing at 900°C, it converted to body-centered-cubic ␣-W with the accompanying release of N. The ALD-WN x film was evaluated as a barrier layer for W-plug deposition for 70 nm design-rule DRAM. The results showed that the integration scheme with ALD-WN x showed lower contact resistance than metallorganic chemical vapor deposition TiN or TiCl 4 -based chemical vapor deposited TiN.

“…7 Since the CVD reaction runs in a depletion mode that enhances deposition at the via mouth, unwanted void formation is likely. 4 Another possible cause of creep-up is the in situ plasma etching, which is used to remove the metal oxide from the aluminum surface prior to W deposition. During the plasma etching, the sputtered aluminum oxide and aluminum can be redeposited on the sidewall of the via and on the surface of the dielectric layer, resulting in creep-up and selectivity loss during subsequent selective CVD-W.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Preclean of Aluminized Silicon Substrate for Chemical Vapor Deposition of Submicron Tungsten Plugs

Yeh

Tsai

Chen

et al. 1995

Preclean of aluminum trench and via patterned substrates is vital for successful selective chemical vapor deposition of tungsten (CVD‐W). A convenient preclean method uses in situ BCl3 plasma etching to remove the native metal oxide prior to conducting the CVD‐W. During the plasma etching, however, the outsputtered aluminum oxide and aluminum can be redeposited on the sidewall of the trench and via hole and on the surface of the dielectric layer, where W nucleation is induced, resulting in creep‐up and selectivity loss during tungsten deposition. By using a solution of hydroxylamine sulfate to pretreat the aluminum trench and via hole patterned substrates, we successfully avoid the creep‐up and selectivity loss of W deposition.