TW459366B - Method to form Copper activated seed layer - Google Patents

Abstract

The present invention provides a method to form Copper activated seed layer, wherein a Tantalum or Titanium metal layer is formed on the substrate as the barrier layer, this barrier layer is put in the nonaqueous polarized organic solvent containing Copper ions to proceed the electrochemical oxidation-reduction contact displacement, the Copper ions will be reduced and deposited on the barrier layer.

Description

4 5 9 36 6 V. Description of the invention (1) ---- [Field of invention] The present invention relates to an agricultural method and method of a copper-activated seed layer, and particularly to a species In the copper process, a method of performing electrochemical redox contact displacement to form a copper-activated seed layer on a barrier layer (barrier Uyer). [Know-how] In terms of integrated circuit technology, in order to improve the component integration and data transmission speed, the process technology has entered the quarter-micron or even the sub-micron. Finer size range. However, as the line width becomes smaller and smaller, 'aluminum wires can no longer meet the speed requirements', so the use of metal copper with high conductivity as the wire to reduce the RC delay is the current trend < = However, copper metal cannot define the pattern by dry etching, because the vaporized copper (CuCl2) produced by the reaction of copper metal and gas plasma gas has a very high boiling point (approximately 15,000 ° C). The production process is carried out by a damascene process. In addition, 'copper metal is usually deposited by electroplating'. Before plating, a conforming (conf orma 1) barrier layer must be formed on the dielectric layer where the trench has been formed. An activated seed layer is deposited on the surface of the barrier layer. However, when the process enters the sub-micron stage, it is necessary to cover the trench of this seed layer with a large aspect ratio, which is quite difficult to fix. . At present, some people have provided information on the use of Cu ionized physical vapor deposition (Cu-IPVD) or Cu chemical vapor deposition (Cu-CVD) in the submicron

459 36 6 V. Description of the invention (2) The activated seed layer is deposited in the trench from (2), but its cost is high and its reliability is not good. In addition, in US Patent No. 5,891,513, it is disclosed that the copper-activated seed layer is made by a copper contact replacement method. However, the contact replacement solution is an aqueous solution, and it has been experimentally proven that the contact replacement cannot be performed. ) Or titanium (T i) in the aqueous solution will quickly form a stable metal oxide of the pentoxide group (γ% A) or titanium dioxide (Ti0 2). This metal oxide is not conductive 'and therefore will block the copper ions. Displacement reaction. In addition, after the copper metal plating is completed, a chemical mechanical polishing process is required to remove the excess copper. However, when the chemical mechanical polishing process is performed to a certain degree, the polishing rate between the copper metal and the barrier layer is different. As a result, the formed copper wire has a phenomenon of dishing, and the problem of dielectric layer loss occurs. These problems will affect the quality of the interconnect. [Objective and Summary of the Invention] In view of this, the present invention provides a method for producing a copper-activated seed layer by using an electrochemical redox contact displacement reaction. In addition, the present invention provides a pentoxide or titanium dioxide that can be avoided between the copper wire and the group or metal layer as a barrier layer, so as to reduce the contact resistance between the copper wire and other components. Furthermore, the present invention provides a manufacturing method which can be applied to a deep sub-micron activated seed layer. '° Therefore' The object of the present invention is to improve the conventional technology. The present invention provides a method for forming a copper-activated seed layer, which includes: placing a barrier layer in a contact replacement solution, and the contact replacement solution Copper

Page 5 4 5 9 3 6 '6 V. Description of the invention (3) The method of ionization, the formation of a groove from the surface of the fluorine, the method of interposing the contactor and the anhydrous or non-electrical recording layer, or by hydrogen fluoride Acidic water alcohol or the above copper should be deposited on top of the layer before, and the composition of the polar organic solvent and anhydrous polar is used to activate the copper seed layer on the surface layer of the barrier layer. Ming also provides a kind of steel interconnecting process, which includes: forming a compliant barrier layer on the formed electrical layer, and then replacing the barrier layer in a solution, which is replaced by copper ions and fluorine. It is composed of organic solvents and copper metal plating process to fill the trench with copper metal to form copper wires. In a preferred embodiment of the present invention, in the above-mentioned process for forming a copper activation seed and copper interconnects, the barrier layer is tantalum, tantalum / nitride / thallium nitride. The copper ion is provided by copper sulfate, and the fluoride ion System or hydrofluoric acid / ammonium fluoride, anhydrous polar organic solvents are anhydrous ketones such as methanol, ethanol, acetone and the like. In addition, in the interconnection process, the barrier layer is placed in contact with the solution to perform the chemical mechanical polishing of the barrier layer to remove the copper metal formed by the dielectric barrier layer in this case. The layer will be selected within the trench. Since the copper-activated seed layer of the present invention is produced by immersion in a contact replacement solution composed of steel ions, gas ions, and anhydrous polar organic solvents, the method is relatively simple and does not require external energy. Furthermore, the method for manufacturing the copper-activated seed layer can be applied to deep sub-micron processes. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is exemplified below, and it is described in detail with the accompanying drawings as follows: ° [Simplified description of drawings]

459 36 6 V. Description of the invention (4) Figures 1A to 1D are diagrams showing a flow chart of copper interconnects using a method for manufacturing a copper-activated seed layer according to a preferred embodiment of the present invention. . [Symbol description] 10 ~ substrate; 16a ~ metal oxide layer; 12 ~ dielectric layer; 18 ~ copper activated seed layer; 14 ~ trench copper; 20 ~ metal layer; 16, 16 '~ barrier layer . [Example] Since the barrier layers commonly used for copper wires include groups, groups / nitride groups, titanium, titanium / titanium nitride, etc., such materials will quickly form stable metal oxides in aqueous solutions, such as pentoxide Giant and titanium dioxide, so the present invention is electrochemical redox contact replacement in a non-aqueous solution, so that tantalum or hafnium atoms are oxidized, and copper ions are reduced and deposited on the barrier layer as a seed layer of electrical chain copper . Figures 1A to 1D are cross-sectional views of a process for applying copper-activated seed layer manufacturing method to copper interconnects according to a preferred embodiment of the present invention. First, please refer to FIG. 1A to provide a substrate 10, such as a semiconductor sand substrate. A semiconductor element (not shown) has been formed thereon, and a dielectric mill 12 'has been formed as an electrical isolation between different layers of wires. The thickness of the dielectric layer 12 is about 0.3 μm to about 1 μm. The material of the dielectric layer 12 is, for example, dioxide; or other materials with a low dielectric constant, such as fluorine-containing dioxide, HSQ (hydrogen si1esquioxane). '' MSQ (methyl

Page 7 4 5 9 366 V. Description of the invention (5) si lesquioxane) ’Trenches 14 have been formed in the dielectric layer 12 for subsequent filling of the wire material as the wire. A uniform and compliant barrier layer 16 is then formed on the surface of the dielectric layer 12. The method for forming the barrier layer 16 is, for example, physical vapor deposition, and the thickness is about 200 angstroms to 500 angstroms. , Whose materials are, for example, buttons (Ta), tantalum / nitride buttons (TaN), titanium (Ti) / titanium nitride (T i N), tungsten nitride (), etc., in order to avoid copper conductors to be formed later The steel atoms diffuse into the dielectric layer 12 and are also used to increase the adhesion between the copper wire and the dielectric layer 12. It is worth noting that a metal oxide layer 16a is easily formed on the surface of the barrier layer 16, such as five Oxidation of two buttons (Ta205) or titanium dioxide (Ti02). • Referring to FIG. 8, the CMP process of the barrier layer 16 and the metal oxide layer 16 a on the surface is performed to remove the barrier layer 16 and the metal oxide layer 16 a outside the trench 14. Since no copper metal is involved in this chemical mechanical polishing process, this chemical mechanical polishing process is easier to perform. Next, referring to FIG. 1C, the barrier layer 6 is placed in a copper contact replacement solution, so that part of the barrier layer 16 is converted into a copper-activated seed layer 8 and the remaining part is the barrier layer 16. Before the contact replacement of steel, the copper contact replacement solution will first dissolve the metal oxide layer 6a on the surface of the barrier layer 16. In addition, since the barrier layer 16 is located in the trench μ, the formed copper-activated seed layer 18 is also located only in the trench 14. The copper contact replacement solution of the present invention is composed of copper ions (Cu2 +), fluoride ions (CF) and anhydrous polar organic solvents. The copper ions are provided by, for example, sulfuric acid steel (CuS04), and the fluoride ions are, for example, by hydrofluoric acid. (HF)

459366

Fluoric acid / Qinghua 4F) provided, anhydrous polar organic solvents: ': Solvents that can dissolve copper ions and fluoride ions, such as anhydrous and anhydrous _, where alcohols such as methanol, such as acetone, etc. e J ^ When the barrier layer 16 and its surface metal oxide layer 16a are placed at this copper connection = replacement, the fluoride ion will react with the metal oxide layer 16a to form a soluble metal fluoride, with the button as the The barrier layer 6 is taken as an example. The metal oxide layer 1ja is tantalum pentoxide, and the hexafluoride ion is formed after the reaction of the two pentoxide button with the fluoride ion (TaF6). After that, the fluoride ion will continue to undergo an oxidation reaction with tantalum. It will also generate soluble hexafluoride button ions and release electrons, while the copper ions in the solution will accept the electrons and reduce to copper atoms and deposit on the barrier layer 16 ' on. The above redox half-reaction and full-reaction formulas are as follows: Oxidation reaction: 2Ta (s) + 12F_— 2TaF6- + 10e-reduction reaction: 5Cu2 + +1 0 e_ — · 5Cu (s) full reaction: 5Cu2 + + 2Ta (s) + 12F- 5Cu (s) + 2TaF6- The above reaction is spontaneous and does not require external energy. In addition, the above reaction rate is directly proportional to the concentration of copper ions and the concentration of fluoride ions. Therefore, using a hydrofluoric acid / ammonium fluoride buffer solution as the source of gas ions will have a better effect, because the fluoride ion The concentration will exist at a fixed concentration, without causing rapid changes in the fluoride ion concentration due to the consumption of fluoride ions. Next, referring to FIG. 1D, a copper metal plating process or an electroless recording process is performed, and a copper metal layer 20 is covered on the copper activated seed layer 18 as a guide.

459366 V. Description of invention (7) Use of line. Since the copper-activated seed layer 18 is located only in the trench 14, the copper metal layer 20 formed by the electroplating method is also located only in the trench η, thereby simplifying the process of manufacturing the copper wire. In addition, you need to planarize the copper metal layer 20 to remove the part that is higher than the plane of the dielectric layer 12, and only need to perform chemical mechanical polishing (CMP buffing) without using copper. Chemical-mechanical grinding of metals reduces process costs. [Features and Effects of the Invention] In summary, the present invention has at least the following advantages: 1. The copper-activated seed layer of the present invention is immersed in contact replacement consisting of copper ions, ions, and anhydrous polar organic solvents The solution is produced by a simple method, which is relatively low in manufacturing cost and does not require external energy. 2 The method for manufacturing a copper-activated seed layer of the present invention, the formed copper-activated seed layer has a fairly good reliability, and can be applied to a 0.18 microfining process. 3. Using the manufacturing method of the copper activated seed layer of the present invention to form a copper wire, it is possible to avoid the existence of a pentoxide or titanium dioxide between the copper wire and the tantalum or titanium metal layer as a barrier layer, so as to reduce the copper wire Instead of its contact resistance. 4. Since the copper wire manufacturing method of the present invention is used, the brocade can be selectively formed in the trench ', which simplifies the steps and the difficulty of the copper wire manufacturing process. 5. In addition, the present invention only indirectly defines the pattern of the copper wire by simple mechanical polishing of the barrier layer, thereby avoiding the selective control of the chemical mechanical polishing between the complex copper-gold barrier layer and the dielectric layer. Question

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Claims (1)

4,5 9 36 6 VI. Application patent scope 1. Kind of method for forming a copper-activated seed layer, including: providing a barrier layer; and placing the barrier layer in a contact displacement solution, the contact device It consists of a copper ion, a fluoride ion and -anhydrous polar organic solvent. 2. The method for forming a copper-activated seed crystal as described in the item of the scope of the patent application ', wherein the barrier layer is selected from the group consisting of tantalum, tantalum / nitride group, hafnium, and titanium oxide. The method of forming a copper-activated seed layer as described in item No. of the patent application scope, wherein the anhydrous polar organic solvent includes anhydrous alcohols. 4. The method for forming a copper-activated seed layer as described in item 1 of the scope of the patent application, wherein the anhydrous polar organic solvent includes anhydrous ketones. 5_ The method for forming a copper-activated seed layer as described in item 1 of the scope of patent application, wherein the copper ion is provided by copper sulfate a 6. The method for forming a copper-activated seed layer as described in item 1 of the scope of patent application A method wherein the fluoride ion is provided by hydrofluoric acid. S 7. The method for forming a copper-activated seed layer as described in item 1 of the patent application scope, wherein the fluoride ion is provided by hydrofluoric acid / ammonium fluoride. 8. A copper interconnect process including: providing a substrate, a dielectric layer having a trench has been formed on the substrate; forming a compliant barrier layer on the dielectric layer; and blocking the barrier The layer is placed in a contact replacement solution to form a copper-activated seed layer on the surface of the barrier layer, wherein the contact replacement solution consists of a copper ion, a fluoride ion, and an anhydrous polar organic solvent; and Page 12 459366 6. Scope of patent application A hafnium copper metal layer is formed on the copper-activated seed layer. According to the copper interconnection process described in item 8 of the scope of the patent application, the S-xuan barrier layer is selected from the group consisting of group, group / gasification group, Qin and Qin / Ihuaqin. 10. The copper interconnection process described in item 8 of the scope of the patent application, wherein placing the barrier layer before the contact replacement solution further includes performing a chemical mechanical polishing to remove the dielectric layer above the dielectric layer. The barrier layer. 11. The copper interconnect process as described in item 8 of the scope of patent application, wherein the anhydrous polar organic solvent includes anhydrous alcohols. 1 2. The copper interconnection process as described in item δ of the patent application scope, wherein the anhydrous polar organic solvent includes anhydrous nets. 13. The copper interconnection process as described in item 8 of the scope of patent application, wherein the copper ion is provided by sulfuric acid steel. 14. The copper interconnection process as described in item 8 of the scope of patent application, wherein the fluoride ion is provided by hydrofluoric acid. # 15. The copper interconnection process as described in item 8 of the scope of patent application, wherein the fluoride ion is provided by hydrofluoric acid / ammonium fluoride. "16. The copper interconnection process as described in item 8 of the scope of patent application, which includes a buffing after the copper plating process is completed. 17 * The copper as described in item 8 of the scope of patent application Interconnection process, which is due to the method of forming the steel metal layer on the steel activation seed layer, including the plating process of the copper metal. · Return lamp 18. The copper interconnection as described in item 8 of the scope of patent application Line process, where Page 13 4p366 Page 14