TW463354B - Method for reducing resistance value of metal conducting wire - Google Patents

Abstract

The present invention provides a kind of method for reducing the resistance value of metal conducting wire that contains aluminum. For this method, an aluminum oxide layer is first formed on the surface of metal conducting wire that contains aluminum. Then, a titanium metal layer and a blocking layer are formed on the aluminum oxide layer. After that, a tungsten metal plug is formed on the blocking layer. The aluminum oxide layer is used to prevent the reaction, which is occurred between titanium metal layer and the metal conducting wire at high temperature when manufacturing the tungsten metal plug, from affecting the resistance value of metal conducting wire that contains aluminum.

Description

46335 4 V. Description of the Invention (l) Field of the Invention The present invention provides a method for reducing the resistance of a metal wire containing aluminum. Background Description A multilevel metallization process uses a plurality of metal wire layers to serially connect metal oxide semiconductor (MOS) components on a semiconductor wafer to each other to form a stacking circuit architecture. Because the multiple metallization process can improve the integration of semiconductor wafers, it is widely used in various very large scale integration (VLSI) processes. Figure 1 shows a conventional metal wire and For the structure diagrams of the plurality of contact plugs, it is known that the manufacturing process of the metal wire layer aluminum-copper / titanium / titanium nitride structure is generally to deposit a metal film on the surface of the semiconductor wafer by the money recording method. 5% 至 4% 之间 的 However, due to the electromigration of electron atoms (electron migration), which may cause the metal name line to open (open), most of the conventional techniques use the content of about 0.5% to 4% in aluminum metal. Copper to prevent the occurrence of disconnection mechanism. Then, a titanium metal layer 12 is deposited on the surface of the aluminum copper metal 10, and the thickness is about 200 to 500 angstroms, followed by titanium gold.

4 6 335 4 V. Description of the invention (2) A layer of titanium nitride is formed on the surface of the metal layer 12 as a barrier layer 14 with a thickness of about 500 to 1500 angstroms. Generally speaking, the barrier layer 14 has two different manufacturing methods. One is to perform a Nitridation reaction on the titanium metal layer 12 to form a nitrided drink layer on the surface of the metal layer 12; the other is By reactive sputtering, a titaniumized layer is directly deposited on the surface of the titanium metal layer 12. After the structure of the metal wire layer is completed, a yellow light and etching process is then used to define the pattern of the metal wire. A dielectric layer is then formed between the MOS transistor and each metal wire layer to isolate and protect the components on the semiconductor wafer. In order for these MOS transistor elements to be electrically connected to each metal wire layer smoothly to form a complete electronic device, a contact plug must be formed in these dielectric layers during the multiple metallization process. As a wire electrically connected between each MOS transistor and the metal wire layer. The conventional method for making contact plugs on the surface of a semiconductor wafer is to first form a plurality of plug holes on a dielectric layer 16 and reach the surface of a conductive region that is to be electrically connected to the outside, such as a MOS transistor. The surface of the source / drain or other underlying metal wires. Then deposit a glue layer (glue U y r) and a tungsten metal layer on the surface of the dielectric layer 16 and the conductive area at the bottom of each plug hole and fill each plug hole. Then, a touch-etching (e t c h b a c k) process is performed again, and the crane metal layer is etched to be approximately aligned with the surface of the dielectric layer i 6 to form a contact plug 18.

Page 5 46335 4 Five 'invention description (3) However, the deposition of tungsten metal layer, sputtering temperature higher than 400 ° C will affect the structure of the metal wire layer previously completed by conventional methods, because Under the influence of the high temperature of the plug 18 process, the titanium metal layer 12 easily reacts with the aluminum metal 10 to form a high-resistance aluminum-titanium compound, which further increases the resistance value of the metal wire and severely affects the electrical performance. SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide a method for reducing the resistance value of an aluminum-containing metal wire so as to solve the problems of the conventional techniques. The method of the present invention first forms an aluminum oxide layer on the surface of the metal wire containing is, then forms a titanium metal layer and a barrier layer on the aluminum oxide layer, and finally forms a tungsten metal plug on the barrier layer. Stuffed. The aluminum oxide layer is used to prevent the high temperature during the manufacture of the tungsten metal plug from causing the titanium metal layer to react with the metal wire to affect the resistance value of the aluminum-containing metal wire. The method of the present invention generates a thin layer of aluminum oxide on the surface of the metal wire, so it can effectively utilize to prevent the titanium metal layer and aluminum metal from reacting at a high temperature for making a tungsten metal plug, causing the resistance of the metal wire to increase. i Detailed description of the invention

5. Explanation of the invention on page 6 (4) Please refer to FIG. 2. FIG. 2 is a schematic diagram of a method for making a low-resistance metal wire according to the present invention. The metal wire can be located between and above each metal-oxide semiconductor element on a semiconductor wafer. Or in each metal interconnect layer. As shown in FIG. 2, the present invention first uses a low pressure sputtering process to form a metal wire 20 made of aluminum or an aluminum-copper alloy on a substrate surface (not shown) of a semiconductor wafer. The surface of the aluminum metal wire 20 is exposed to an oxygen-containing environment, or an oxygen-containing plasma is used to react with the surface of the aluminum-containing metal wire 20 to form an aluminum oxide layer 22. The thickness of the aluminum oxide layer 22 is within about 50 angstroms. Subsequently, a titanium metal layer 24 having a greater reduction ability than aluminum is formed on the alumina layer 22, and finally, a barrier layer 26 made of titanium nitride is formed on the titanium metal layer 24 to form a metal wire layer. After the metal wiring layer is completed, a dielectric layer is formed around each metal wiring layer to isolate and protect the components on the semiconductor wafer. In order for these metal wire layers to be smoothly and electrically connected to each MOS transistor element or other metal wire layers to form a complete electronic device, a contact plug must be formed in these dielectric layers as each M 0 S electrical A wire that is electrically connected between a crystal or other element and a metal wire layer. As shown in FIG. 2, a dielectric layer 28 is formed on the titanium nitride layer 26 of the metal wire layer, and then a plug hole is formed in the dielectric layer 28, and finally a tungsten is filled in each plug hole. Metal to form a contact plug 30. In the process of filling tungsten metal, a high temperature above about 400 ° C is required.

Page 7 4 633 5 4 V. Description of the invention (5) Because the metal wire layer produced by the method of the present invention has an aluminum oxide layer formed between the aluminum-copper alloy and the titanium metal layer, when manufacturing a tungsten metal plug It can avoid direct contact between aluminum metal and titanium metal, and react at high temperatures to form aluminum-titanium compounds, which causes the resistance value of metal wires to increase. In addition, since the thickness of the alumina layer 22 is only about 50 angstroms, it is easily consumed by the titanium metal layer 24 having a reduction ability greater than that of aluminum, and hardly remains in the semiconductor wafer. Compared with the conventional method for making metal wires, the method of the present invention can effectively avoid the reaction between aluminum-copper alloy and titanium metal to form compounds and increase the resistance value of the metal wires, affecting the electrical performance of the final product wafer. The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the patent of the present invention.

Page 8 463354 Brief description of the diagrams Brief description of the diagrams Figure 1 is a structure diagram of conventionally making a metal wire layer and a plurality of contact plugs. FIG. 2 is a schematic structural diagram of a low-resistance metal wire layer and a plurality of contact plugs according to the present invention. Explanation of symbols in the figure 10 Aluminum-copper metal layer 12 Titanium metal layer 14 Barrier layer (nitride layer) 16 Dielectric layer 18 Contact plug 20 Metal wire 22 Alumina layer 24 Titanium metal layer 26 Barrier layer (nitrogen Titanium layer) 28 Dielectric layer 30 Contact plug

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Claims (1)

46 335 4 VI. Scope of patent application 1. A method for reducing the resistance value of an aluminum-containing metal wire, the method includes the following steps: forming an aluminum oxide layer on the surface of the aluminum-containing metal wire; on the aluminum oxide layer Forming a metal layer, wherein the metal layer is composed of a metal having a greater reduction ability; and forming a barrier layer on the metal layer. 2. The method according to item 1 of the patent application range, wherein the aluminum-containing metal wire is composed of aluminum or an aluminum-copper alloy. 3. The method of claim 1 in which the method of forming the alumina layer is to expose the surface of the aluminum-containing metal wire to an oxygen-containing environment. 4. The method according to item 1 of the patent application range, wherein the alumina layer is formed by reacting an oxygen-containing plasma with the surface of the aluminum-containing metal wire. 5. The method of claim 1 in which the thickness of the alumina layer is within about 50 angstroms. 6. The method of claim 1, wherein the metal layer is a titanium (Ti) layer. Page i463463354 6. Scope of patent application 7. The method of the first scope of patent application, wherein the barrier layer is a titanium nitride (TiN) layer ° 8. A method for reducing a metal wire containing aluminum A method of resistance value, which comprises the following steps: forming an aluminum oxide layer on the surface of the aluminum-containing metal wire; forming a titanium metal layer on the oxide layer; forming a titanium nitride layer on the titanium metal layer Forming a dielectric layer on the titanium nitride layer; forming a plug hole in the dielectric layer; and filling a tungsten (W) metal plug in the plug hole; wherein the alumina The layer system is used to avoid the high temperature when making the tungsten metal plug to cause the titanium metal layer to react with the metal wire and cause the resistance of the metal wire to increase. 9. The method of claim 8 in which the aluminum-containing metal wire is composed of aluminum or an aluminum-copper alloy. 10. If the method according to item 8 of the patent application is applied, wherein the method for generating the alumina layer is to expose the surface of the aluminum-containing metal wire to an oxygen-containing environment. 11. If the method according to item 8 of the patent application, The alumina layer is formed by reacting an oxygen-containing plasma with the surface of the aluminum-containing metal wire. Page 11 4 6 335 4 Page 12