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copper may contact and poison the very devices that they supply with energy and information; with barrier layers too thick, these wrapped stacks of two barrier metal films and an inner copper conductor can have a greater total resistance than the traditional aluminum interconnections would have, eliminating any benefit derived from the new metallization technology.
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diffusion barrier simultaneously, the bonding between layers needs to come from a chemical reaction of limited range at both boundaries. Materials providing good adhesion are not necessarily good diffusion barriers and vice versa. Consequently, there are cases where two or more separate layers must be used to provide a proper interface between substrates.
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in order to maintain a good electronic contact, while maintaining a low enough copper diffusivity to sufficiently chemically isolate these copper conductor films from underlying device silicon. The thickness of the barrier films is also quite important; with too thin a barrier layer, the inner
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between plate and substrate in order to work. The role of a diffusion barrier is to prevent or to retard the inter-diffusion of the two superposed metals. Therefore, to be effective, a good diffusion barrier requires inertness with respect to adjacent materials. To obtain good adhesion and a
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involves three diffusion barrier layers—copper, nickel, then chromium—to provide long term durability where there will be many large temperature changes. If chromium is plated directly onto the steel, then their different
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has excellent adhesion to many materials because of its reactivity. Its affinity for oxygen forms a thin stable oxide coat on the outer surface, creating a
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from soft metal interconnects, while maintaining an electrical connection between them. For instance, a layer of barrier metal must surround every
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which prevents further oxidation of the chromium, and of the underlying metal (if any), even in corrosive environments. Chromium plating on steel
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usually placed between two other metals. It is done to act as a barrier to protect either one of the metals from corrupting the other.
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are a few of the metal combinations used to form diffusion barriers for specific applications. Conductive
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metal combinations have been evaluated for their adhesion and diffusion barrier properties.
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its virtue relies in its inertness, and ease of application; its problem is its cost.
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also easily reacts with oxygen but its oxides have poor adhesion properties. As for
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While the choice of diffusion barrier depends on the final function, anticipated
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layer to its substrate requires a physical interlocking, inter-
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Some materials that have been used as barrier metals include
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will cause the chrome plating to peel off the steel.
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As the name implies, a barrier metal must have high
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200:in modern integrated circuits, to prevent
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204:of copper into surrounding materials.
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247:, but "metals" in this context).
298:Semiconductor device fabrication
243:(the last four being conductive
116:thermal expansion coefficients
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156:can be also used, such as
89:properties of its oxide.
264:Cahn, Robert W. (1996),
85:reactivity and the self-
209:electrical conductivity
192:to chemically isolate
188:is a material used in
61:operating temperature
79:thermal conductivity
46:of the deposit or a
267:Physical metallurgy
198:copper interconnect
190:integrated circuits
180:Integrated circuits
111:for automotive use
277:978-0-444-89875-3
107:passivation layer
29:diffusion barrier
16:(Redirected from
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241:titanium nitride
237:tungsten nitride
229:tantalum nitride
174:titanium nitride
170:tungsten nitride
158:tantalum nitride
48:chemical bonding
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40:plated metal
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87:passivation
292:Categories
251:References
75:electrical
221:ruthenium
202:diffusion
142:zirconium
65:thin film
55:Selection
44:diffusion
245:ceramics
225:tantalum
154:ceramics
150:tungsten
146:vanadium
130:tantalum
126:Nichrome
103:Chromium
71:Aluminum
138:niobium
134:hafnium
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239:, and
217:cobalt
172:, and
148:, and
122:Nickel
93:Copper
83:oxygen
33:metal
272:ISBN
97:gold
77:and
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