Ti/Tinx underlayer which enables a highly <111>...

Details Ti/Tinx underlayer which enables a highly <111>... Ti/Tinx underlayer which enables a highly <111>...

2000-10-24

2002-07-16

Nguyen, Ha Tran (Department: 2812)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S628000, C438S648000, C438S653000, C438S654000, C438S685000, C438S688000

Reexamination Certificate

active

06420260

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a particular (Ti or TiN
x
)/TiN/TiN
x
barrier/wetting layer structure which enables the warm aluminum filling of high aspect ratio vias while providing an aluminum fill exhibiting a high degree of <111> crystal orientation aluminum.
2. Brief Description of the Background Art
Titanium nitride layers have been used in semiconductor device structures as barrier layers for preventing the interdiffusion of adjacent layers of materials such as aluminum and silicon, for example. However, the crystal orientation of aluminum deposited over the surface of the titanium nitride barrier layer is typically polycrystalline, and polycrystalline aluminum has poor electromigration resistance.
In the formation of integrated circuit interconnect structures, such as a Ti/TiN/TiN
x
stack, electromigration of aluminum atoms within the aluminum layer becomes a problem if the aluminum layer is not formed with a high degree of <111> crystal orientation. Electromigration of the aluminum atoms can result in open circuits within the integrated circuit structure, and therefore, such electromigration must be inhibited or eliminated. Electromigration of aluminum atoms can occur within filled vias as well, impairing the conductivity of the contacts.
U.S. Pat. No. 4,944,961 to Lu et al., issued Jul. 31, 1990, describes a process for partially ionized beam deposition of metals or metal alloys on substrates, such as semiconductor wafers. Metal vaporized from a crucible is partially ionized at the crucible exit, and the ionized vapor is drawn to the substrate by an imposed bias. Control of substrate temperature is said to allow non-conformal coverage of stepped surfaces such as trenches or vias. When higher temperatures are used, stepped surfaces are planarized. The examples given are for aluminum deposition, where the non-conformal deposition is carried out with substrate temperatures ranging between about 150° C. and about 200° C., and the planarized deposition is carried out with substrate temperatures ranging between about 250° C. and about 350° C.
S. M. Rossnagel and J. Hopwood describe a technique of combining conventional magnetron sputtering with a high density, inductively coupled RF plasma in the region between the sputtering cathode and the substrate in their 1993 article titled “Metal ion deposition from ionized magnetron sputtering discharge”, published in the J. Vac. Sci. Technol. B. Vol. 12, No. 1, January/February 1994. One of the examples given is for titanium nitride film deposition using reactive sputtering, where a titanium cathode is used in combination with a plasma formed from a combination of argon and nitrogen gases.
U.S. Pat. No. 5,262,361 to Cho et al., issued Nov. 16, 1993 describes a method for forming single crystal aluminum films on the surface of a substrate such as silicon (111). The object is to increase the amount of the aluminum (111) crystal orientation, to improve the electromigration resistance of the aluminum. Electrically neutral aluminum is deposited by a vacuum evaporation technique upon a silicon wafer surface at a temperature ranging between about 300° C. and about 400° C.
U.S. Pat. No. 5,543,357 to Yamada et al., issued Aug. 6, 1996, describes a process for manufacturing a semiconductor device wherein a titanium film is used as an under film for an aluminum alloy film to prevent the device characteristics of the aluminum alloy film from deteriorating. The thickness of the titanium film is set to 10% or less of the aluminum alloy film containing no silicon, the titanium film is set to 5% or less of the aluminum alloy film. The aluminum film is formed at a substrate temperature of 200° C. or less by a sputtering process, and when the aluminum film or an aluminum alloy film is to fill a via hole, the substrate is heated to fluidize the aluminum. The pressure during the aluminum film formation and during the fluidization is lower than 10
−7
Torr. A titanium nitride barrier layer may be applied on an interlayered insulating film (or over a titanium layer which has been applied to the insulating film), followed by formation of a titanium film over the titanium nitride film, and finally by formation of the aluminum film over the titanium film. After formation of the titanium nitride barrier layer, the barrier layer is heated to a temperature of about 600° C. to 700° in a nitrogen atmosphere using a halogen lamp so that any titanium which is not nitrided will become nitrated. The titanium nitride barrier layer is said to be a poor barrier layer if un-nitrided titanium is present within the layer.
U.S. Pat. No. 5,571,752 to Chen et al., issued Nov. 5, 1996, discloses a method for patterning a submicron semiconductor layer of an integrated circuit. In one embodiment, titanium or titanium nitride having a thickness of between approximately 300 and 2000 Å is formed by sputter deposition to reach the bottom of a contact opening. The barrier layer may be annealed to form a silicide in the bottom of the opening. A conformal conductive layer of a refractory metal or refractory metal silicide is formed over the titanium or titanium nitride using chemical vapor deposition (CVD). Finally, a second conductive layer, typically aluminum is applied over the surface of the conformal conductive layer. The aluminum is sputtered on, preferably at a temperature ranging between approximately 100° C. and 400° C. This method is said to make possible the filling of contact openings having smaller device geometry design requirements by avoiding the formation of fairly large grain sizes in the aluminum film.
U.S. patent application Ser. No. 08/511,825 of Xu et al., filed Aug. 7, 1995, assigned to the Assignee of the present invention, and hereby incorporated by reference in its entirety, describes a method of forming a titanium nitride-comprising barrier layer which acts as a carrier layer. The carrier layer enables the filling of apertures such as vias, holes or trenches of high aspect ratio and the planarization of a conductive film deposited over the carrier layer at reduced temperatures compared to prior art methods.
U.S. patent application Ser. No. 08/753,251 of Ngan et al., filed Nov. 21, 1996, describes a method for producing a titanium nitride-comprising barrier layer on the surface of a contact via. For certain contact geometries, when the reactor pressure is reduced during formation of the titanium nitride-comprising barrier layer, the thickness of the barrier layer on the sidewalls of the via increases. This enables an aluminum fill to travel along the sidewalls of the via more easily, resulting in a better fill of the via. In particular, the titanium nitride comprising barrier layer needs to be of a minimum thickness and to have a minimum titanium content so that the barrier layer can react slightly with the Aluminum, to draw the aluminum along the sidewalls of the via.
U.S. patent application Ser. No. 08/825,216 of Ngan et al., filed Mar. 27, 1997, discloses various process techniques which can be used to control the crystal orientation of a titanium nitride barrier layer as it is deposited. Further, by increasing the {200} crystal orientation of the titanium nitride barrier layer, the resistivity of this layer is decreased.
A “traditionally sputtered” titanium nitride-comprising film or layer is deposited on a substrate by contacting a titanium target with a plasma created from an inert gas such as argon in combination with nitrogen gas. A portion of the titanium sputtered from the target reacts with nitrogen gas which has been activated by the plasma to produce titanium nitride, and the gas phase mixture contacts the substrate to form a layer on the substrate. Although such a traditionally sputtered titanium nitride-comprising layer can act as a wetting layer for hot aluminum fill of contact vias, good fill of the via generally is not achieved at substrate surface temperature of less than about 500° C.
To provide for aluminum fill at a lower temperature, Xu et al

Affiliated with

Also associated with

Rating

Ti/Tinx underlayer which enables a highly &lt;111&gt;... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Ti/Tinx underlayer which enables a highly &lt;111&gt;..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ti/Tinx underlayer which enables a highly &lt;111&gt;... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2897175