Activation-free electroless solution for deposition of cobalt and method for deposition of cobalt capping/passivation layer on copper
First Claim
1. An electroless deposition solution for deposition of cobalt onto a substrate, comprising:
- at least one cobalt ion source; and
at least two reducing agents for reducing ions of said at least one cobalt ion source, wherein the at least two reducing agents comprise;
a first reducing agent for initiating deposition of a first layer of cobalt on said substrate; and
a second distinct reducing agent for continuing the deposition of cobalt above said substrate, wherein the second reducing agent is substantially absent of alkali metals.
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Accused Products
Abstract
The present invention relates to compositions and a method for electroless formation of alkaline-metal-free coatings on the basis of cobalt and composition of cobalt with tungsten and phosphorus, which have high resistance to oxidation and stability of electrical characteristics, when the Co—Cu system layer is used in IC chips. The composition of the electroless solution contains more than one reducing agents, one of which can catalyze the initial electroless deposition layer of cobalt on copper (called initiator), while the other maintains deposition of cobalt on the aforementioned initial layer as the process is continued. Small amount (100-5000 ppm) of elements from the initiator also builds into the electroless film, which is expected to further improve the barrier properties of the resultant film compared to the deposition bath without initiator. Such coating may find application in semiconductor manufacturing where properties of deposited films and controllability of the composition and physical and chemical characteristics of the deposited films may be critically important.
65 Citations
34 Claims
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1. An electroless deposition solution for deposition of cobalt onto a substrate, comprising:
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at least one cobalt ion source; and
at least two reducing agents for reducing ions of said at least one cobalt ion source, wherein the at least two reducing agents comprise;
a first reducing agent for initiating deposition of a first layer of cobalt on said substrate; and
a second distinct reducing agent for continuing the deposition of cobalt above said substrate, wherein the second reducing agent is substantially absent of alkali metals. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14)
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7. A single-stage method for electroless deposition of a cobalt layer on a copper surface, comprising:
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preparing an electroless deposition solution by mixing at least one cobalt ion source with a first reducing comprising boron and a second reducing agent substantially free of alkali metals and distinct from the first reducing agent; and
exposing the copper surface to the electroless deposition solution to form the cobalt layer. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An electroless deposition solution, comprising:
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cobalt ions;
at least two reducing agents configured to reduce the cobalt ions to a cobalt film, wherein the at least two reducing agents comprise;
a first reducing agent comprising an aminoborane; and
a second distinct reducing agent comprising phosphorous and substantially absent of an alkali metal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification