TW451445B - Manufacturing method of copper wire - Google Patents

Abstract

The present invention provides a manufacturing method for copper wire, comprising: after forming a conformal barrier layer on the dielectric with trench formed, covering a layer of silicon material; then, stripping part of the silicon layer so that the silicon layer is filled into the trench only; then, conducting contact displacement reaction to convert the silicon layer into copper wire.

Description

4 5 1 44 5 V. Description of the Invention (i)-[Field of the Invention] The present invention relates to a method for manufacturing a copper wire, and more particularly to a method of using copper atoms to dissolve copper. Selectively form a local copper metal as steel [Known Technology] ^ In terms of integrated circuit technology, in order to improve the component integration and data transmission speed, the process technology has been entered by sub-micron (sub_micr〇n) A range of quarter-micron or even finer sizes. However, as the line width becomes smaller and smaller, the aluminum wire can no longer meet the speed requirement. Therefore, the use of metal steel with high conductivity as the wire to reduce the RC delay is a current trend. But 'copper metal cannot define the pattern by dry etching, because copper chloride (CuCl2) generated by the reaction of copper metal and gas plasma gas is extremely high (about 1500 ° C), so the production of steel wires requires Performed in a damascene process. In addition, copper metal is usually deposited by electroplating. Before electroplating, a conformal barrier layer must be formed on the trenched dielectric layer, and then the barrier in the trench must be formed. A seed layer is deposited on the surface of the layer. However, in the deep sub-micron process, it is quite difficult to uniformly cover the trenches with a large aspect ratio of the activated seed layer. 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. Make

^^ 5 1 V. Cheming said 44 5 q π Explanation (2) ύ _ _ The copper wires formed by the seven dielectric layers have dishing and there are problems of donation, which will affect the interconnection Quality light crystal layer of the wire, < Avoid copper [Objective and summary of Ming] In view of this, the present invention provides a method for forming copper wires without the need to deposit copper activation and steel plating process. In addition, the present invention provides A method for forming a steel wire. Problems such as wire dishing and abrasion of a dielectric layer occur. Furthermore, the present invention provides a method for forming a copper wire which does not require a chemical mechanical polishing process of copper metal. Therefore, the purpose of the present invention is to improve the conventional technology. The present invention provides a method for manufacturing a copper wire, which includes: forming a compliant JI barrier layer on a dielectric layer having a trench formed on a substrate. 'After that, cover the barrier layer with a layer> 5th layer, and then peel off part of the dream layer, so that the dream layer fills only the trench.' Then, a contact replacement reaction is performed to turn the hair layer into a copper wire. According to a preferred embodiment of the present invention, the barrier layer is tantalum, chain / tantalum nitride, titanium, or titanium / titanium nitride, the silicon layer is amorphous silicon or polycrystalline silicon, and the contact displacement reaction is based on copper ion. Contact with fluoride ions is carried out in an aqueous solution 'where the copper ions are provided by copper sulfate, and the fluorine free hands are provided by hydrofluoric acid or hydrofluoric acid / ammonium fluoride. In addition, in the above-mentioned manufacturing method of the copper wire, 'before the completion of the replacement reaction' further includes stripping the barrier layer on the dielectric layer ', and the method of removal is chemical mechanical polishing; after the replacement reaction is performed, It also includes a tempering step to increase the density of the steel atoms in the copper wire, thereby reducing the resistance of the copper wire. Since the invention replaces the copper atoms with the

3 1 44 5 V. Description of the invention (3) The wire can be selectively formed in the trench, which simplifies the difficulty of the copper wire process. In addition, the present invention only indirectly defines the pattern of the steel wire by simple silicon chemical mechanical polishing and barrier chemical mechanical polishing, thereby avoiding the complicated mechanical mechanical polishing between the copper metal, the barrier layer and the dielectric layer. The problem of selective control 'is used to overcome the problems of the dishing of copper wires and the wear of dielectric layers caused by the conventional chemical mechanical polishing of copper metal. In order to make the above-mentioned objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is given below in conjunction with the accompanying drawings and described in detail as follows: [Schematic diagram 1A Application fragmentation [Symbol said Substrate dielectric trench [The embodiment also forms steel guides due to the oxidation, to select the 1A application silicon flow profile section description] Figures to Figure 1C atomic contact set] -10; layer ~ 1 2; -14; ] The silicon atom reacts with the source of copper, depending on the area of the line, selectively in the local map to Figure 1C, the atom and copper ion diagram. It is a cross-sectional view of a process for changing steel to a steel interconnecting line according to one of the preferred embodiments of the present invention. Barrier layer, 16a; Silicon layer ~ 18, 18a; Steel wire ~ 2 0; Ions will spontaneously occur under appropriate environment. The present invention is to place silicon atomic layer on it to be replaced by redox contact. The lead region of the reaction forms a copper wire. This is a schematic diagram of the contact displacement reaction of a substrate according to one of the preferred embodiments of the present invention.

Page 6 451445 V. Description of the invention (4) First, please refer to FIG. 1A to provide a substrate 10, such as a semiconductor stone substrate, on which a semiconductor element (not shown) has been formed, and a dielectric layer has been formed. 12. For electrical isolation between different layers of wires, its thickness is about 0.3 micrometers to 1 micrometer. The material of this dielectric layer 12 is, for example, two gasification; g or other materials with low dielectric Substances with an electrical constant, such as fluorine-containing dioxide seconds, HSQ (hydrogen siesesoxoxane) 'MSQ (methyl siquisquioxane), trenches 14 have been formed in this dielectric layer 12 for subsequent filling of the wire material as the wire use. Then, a uniform and compliant barrier layer 16 is formed on the surface of the dielectric layer 12. The formation method is, for example, physical vapor deposition, and the thickness is about 200 angstroms to 500 angstroms. The material is, for example, group (Ta), group / nitride (TaN), titanium (Ti) / titanium nitride (T i N), tungsten nitride (WN), etc., in order to avoid the subsequent formation of copper wires. Copper atoms diffuse into the dielectric layer 12 and also serve to increase the adhesion between the steel wires and the dielectric layer 12. Thereafter, a silicon layer 18 is deposited on the barrier layer 16 and the trench 14 is filled. The deposition methods are, for example, plasma-assisted chemical vapor deposition, plasma-added chemical vapor deposition (PECVD), and low-pressure chemical vapor deposition (LPCVD). ), High Vacuum Chemical Vapor Deposition (UHVCVD). The material of this silicon layer 18 is, for example, an amorphous silicon layer or a polycrystalline silicon layer. 'Amorphous silicon layer is preferred because the process temperature required to deposit the amorphous silicon layer is relatively high. Low, will not damage the electrical properties of other formed components. It is worth noting that the process technology for depositing the silicon layer 18 is quite good for the trench filling capacity of the trench 14 with a high aspect ratio. Next, referring to FIG. 1B, a chemical mechanical polishing process is performed to remove the silicon layer is above the surface of the dielectric layer 12 into a silicon layer i8a, so that the silicon layer 18a

Page 7 45 1 44 5

Only filled in the trench 14. In addition, the chemical mechanical polishing process of the barrier layer 16 is continued to strip the barrier layer 16 on the upper surface of the dielectric layer 12 and turn it into the barrier layer 1 β a. The silicon layer 18a formed above is the area of the copper wire to be formed in the following. In addition, the surface of the rare earth layer 18a after chemical mechanical polishing may be substantially flush with the upper surface of the dielectric layer 12, or A distance below the upper surface of the dielectric layer 12 can also be controlled by controlling this distance to control the height of the silicon layer 18a, and indirectly control the height of the copper wires to be formed subsequently. Next, referring to FIG. 1C, the silicon layer 18a is placed in a contact replacement solution 'to perform a redox reaction' to turn the silicon layer 18a into a copper wire 20. It is worth noting that when the silicon layer 18a is replaced with a copper wire 20 due to a redox reaction, the volume of the 'copper wire 20' will be larger than the volume of the original silicon layer 18a. Therefore, when the upper surface of the silicon layer 18a is approximately flush with the upper surface of the dielectric layer 12, the formed copper wire 20 will bulge slightly. The illustration in the figure is based on this example. If the silicon layer 18a is controlled, If the upper surface of the dielectric layer 12 is lower than the upper surface of the dielectric layer 12, the height of the copper wire 20 can be controlled indirectly. The above-mentioned contact replacement solution is composed of an aqueous solution of copper ions (Cu2 +) and fluoride ions (F-), wherein the copper ions are provided by copper sulfate (CuS04), and the fluorine ions are, for example, hydrofluoric acid (HF) Or it is provided by hydrofluoric acid / ammonium fluoride (NHJ), and the concentration of fluoride ions is about 0.3 to 5 weight percent (%). The temperature of this contact displacement solution is controlled between about 10 ° C and 55 ° c. When the wonderful layer 18a is placed in this contact replacement solution, the fluoride ions and the silicon atoms in the hair layer 18a are oxidized to form soluble silicon fluoride (si Fj-), and released.

Page 8 45 1 445

Five 'invention description ¢ 6) ΪΪ: The copper ions in the second solution Λ will accept electrons and reduce to copper atoms. When the silicon atoms in the silicon layer Ua are completely oxidized and replaced with copper atoms, the reaction is terminated. A copper wire 20 is formed in the trench 14. The above redox half-reaction and full-reaction formulas are as follows: Oxidation reaction: Si (s) + 6 F- — SiFs2_ + 4e- reduction reaction: 2 CU2 + + 4 e- 4 2 Cu⑷ full reaction: 2 Cu2 + + Si (s) + 6 F--2 Cu (s) + SiF62- where the standard oxidation potential of 'Si / SiFe2- is one U4 V, the standard reduction potential of cu2 + is + 0,337 V, and the potential of the above full reaction is + 1 577 "v. Therefore, 'This reaction is a spontaneous reaction, and no external energy is required. In addition,' The above reaction rate is directly proportional to the concentration of copper ions and fluoride ions ', so' hydrofluoric acid / ammonium fluoride The buffer solution as the source of fluoride ion will have better effect, because the concentration of fluoride ion will be present in the contact replacement solution at a solid concentration, and the concentration of fluoride ion will not decrease rapidly due to the consumption of fluoride ion. Then, a tempering step is performed to increase the density of the copper atoms in the copper wire 20, thereby reducing the resistance of the copper wire 20 itself. This tempering step is, for example, between about 200 t to 50 ° C High-temperature tempering under inert gas is a preferred temperature of about 400. (:, The best inert gas is nitrogen, and the process time required for this tempering step is about 20 minutes to 90 minutes. Since copper atoms are only selectively deposited in the trench 14, therefore, they are formed on the copper wire 20 After completion, the subsequent process can be performed directly without chemical mechanical polishing, thus simplifying the process steps, and avoiding the problems of dishing and dielectric layer 12 wear caused by grinding copper.

451445 V. Description of the invention (7) [Features and effects of the invention] In summary, the present invention has at least the following advantages: 1. The steel wire formed by the present invention is not required to be formed by electroplating, so it is not necessary Since the seed layer is formed, the problem of uneven coverage of the seed layer due to the reduction of the line width can be avoided. 2. Since the copper wire of the present invention is converted by the silicon layer through a contact displacement reaction, and the formed silicon layer has a good trench filling effect, it is very suitable for the damascene process in a submicron process with a large aspect ratio. . 3. In the process of forming the copper wire of the present invention, it is not necessary to pass through the copper metal.

The CMP process can avoid problems such as dishing and dielectric loss caused by grinding steel. 'Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to ^ i the present invention. Any person skilled in the art can make changes and decorations without departing from the present invention. Therefore, the field of the present invention What is attached after the event is defined by the scope of patent application. #solid

Claims (1)

451445 6. Scope of patent application 1. A method for manufacturing a copper wire, comprising: providing a substrate on which a dielectric layer having a trench has been formed; and forming a compliant barrier layer on the dielectric layer Covering a silicon layer on the barrier layer; stripping off part of the silicon layer so that the silicon layer fills only the trench; and performing a contact replacement reaction to turn the silicon layer into a copper wire. 2. The method for manufacturing a copper wire as described in item 1 of the scope of the patent application, wherein the barrier layer is selected from the group consisting of tantalum, button / nitride button, titanium, and titanium / titanium nitride. 3. The method for manufacturing a copper wire as described in item 1 of the scope of patent application, wherein after stripping a part of the silicon layer and before performing the contact replacement reaction, the method further includes stripping the barrier layer on the dielectric layer. So that the barrier layer is located only in the trench. 4. The method for manufacturing a copper wire according to item 1 of the scope of the patent application, wherein the silicon layer includes an amorphous silicon layer. 5. The method for manufacturing a copper wire according to item 1 of the scope of the patent application, wherein the silicon layer includes a polycrystalline silicon layer. 6. The method for manufacturing a copper wire according to item 1 of the scope of the patent application, wherein the contact displacement reaction is performed in an aqueous solution containing copper ions and fluoride ions. 7. The method for manufacturing a steel wire according to item 6 of the scope of the patent application, wherein the copper ion is provided by sulfuric acid steel. 8. Manufacturing method of copper wire as described in item 6 of the scope of patent application ’ 451445 Page 12