TWI230982B - A clean method for preventing galvanic corrosion - Google Patents

Abstract

A clean method for preventing galvanic corrosion. A substrate with a plurality of metal lines is provided and then cleaned with supercritical fluid. Due to the non-conductive properties of the supercritical fluid, conductive circuits are not formed during the cleaning process, such that galvanic corrosion issue of cu process is avoided during subsequent wet etching.

Description

1230982 V. Description of the invention (1) The technical field of the invention The present invention relates to a cleaning method for a semiconductor process, and more particularly to a cleaning method for preventing current rot. The prior art has increased with the demand for high-performance integrated circuits and circuits. The size of the component is set to be small for ten days, and the requirements for the electrical conductivity of the metal interconnect (e 1 ectri C a 1 conductivity) are becoming higher and higher in order to achieve better transmission.

Efficiency ', and the test of the conductivity of metal interconnects is an indispensable part to ensure the quality of integrated circuits. Traditionally, the wires between semiconductor elements are generally made of aluminum or its alloy, which has the advantage that it is not easy to oxidize. Generally, as long as it is covered with a layer of titanium nitride (TiN) as an anti-oxidation layer, the problem of wire oxidation can be effectively prevented. However, as the size of integrated circuit components has been shrinking, the number of interconnects has continued to increase, and the large number of applications of narrow interconnect leads has limited the use of aluminum and its alloys in next-generation integrated circuits. Applications in circuits. The high electrical resistance of aluminum and its alloys is another reason for its application. Compared with Ming and its alloys, copper has a low conductive constant and high electron transfer resistance, which has a fast conduction speed, which is very suitable for the production of interconnects for high-performance integrated circuits. Copper metallic interconnects are based on the chemical mechanical polishing of copper. (Cu metal's high conductivity, high ductility, and resistance characteristics make copper metal interconnects meet the needs of high-performance integrated circuits, which is the new favorite of interconnects. Unlike aluminum metal inlays or dual inlays, (-CMP) is the copper process of integrated circuits

1230982 V. Description of the invention (2) Key process. However, copper metal is fast in liquids containing chemical substances. Therefore, how to overcome the chemical mechanical polishing cleaning process of copper, especially the current corrosion caused by the cleaning process before copper chemical mechanical polishing = a very important problem. See Figure I as shown in Figure 1A, which shows 4 of the copper metal of the conventional technology, like a substrate 100 with an N-type metal-oxide semiconductor 105 and a p-metal oxide semiconductor 110, in which shallow trench insulator STI is used as a barrier, = copper metal is a metal inner connecting wire. As shown in FIG. 1B, the potential difference between the drain 115 type metal oxide semi-transistor * source 120 and the substrate 120 is connected to the substrate when it is cleaned in a chemically-containing liquid. The second metal wire 125 of the P-type metal-oxide-semiconductor transistor drain and the second metal-alloy line 130 connected to the N-type metal-oxide-semiconductor drain can cause current corrosion due to the built-in potential energy difference between them. That is, the copper ion passes through the electrolyte-containing liquid as a path, and the first metal wire 125 of the p-type metal-oxide semiconductor transistor 115 moves to the second metal wire 13 of the N-type metal-oxide semiconductor transistor drain 120. 〇, f The first metal wire 125 may cause a corrosion phenomenon, and the second metal wire may cause a copper ion deposition phenomenon. In other words, connected to? The first metal wire 125 of the body type drain electrode of the gold type is similar to the anode, and the second metal wire 13 of the n-type oxygen semiconductor crystal drain is similar to the cathode. In addition, if there is light shining on the wafer surface at this time, it will increase the number of electron hole pairs in the N ... depleted area due to energy, and this = hole pair will also move its built-in potential difference to the PN junction. The main domain 'so the phenomenon of current rotten name will be more serious, and therefore the surface will be 0503-9936twf (nl); tsmc2002 >1331; wayne.ptd Page 5 1230982 V. Description of the invention (3) Wafers with components will produce This galvanic corrosion phenomenon is not a problem with test pieces that generally do not have components. Among the semiconductor 1C cleaning methods, Caros (H2S04 / H202), SCI (standard clean 1; NH40H / H202), and SC2 (standard clean 2; HC1 / H202) are widely used for the cleaning of Shi Xijing circle. In addition, ozone and HF are also used to clean Shixi wafers. For example, U.S. Patent Application Publication No. 2001/0017143 A1 uses ozone water and HF to clean semiconductor silicon wafers. In U.S. Patent No. 6, 240, 933, semiconductor silicon wafers are cleaned with ozone water, and oxides are removed with steam. u. s. Patent No. 6,348,157 mentions that for cleaning semiconductors, ozone water, HF (with ultrasonic vibration), deionized water, hf, and deionized water are used in order. However, the cleaning methods cited above are applied to the copper process, and they cannot avoid the problem of current corrosion caused by the built-in potential difference of the components. … Summary of the Invention In view of this, in order to solve the problem of cleaning and corrosive cleaning with a supercritical fluid, and to solve the copper process, in order to achieve the above purpose, the hair washing method includes the following steps: the substrate of the first line, the substrate is placed in the superpro In which, the connection fluid of the supercritical cleaning chamber is extracted from the first storage tank to the above-mentioned problem. The purpose of the present invention is to prevent the problem of current corrosion in the electric cleaning process during the cleaning process. Ming provides a method to prevent galvanic corrosion, and a supercritical cleaning chamber with a plurality of metal-conducting cleaning systems = a first storage tank. Next, adjust the supercritical cleaning in a critical cleaning chamber.

1230982

The force and the degree of washing to make the fluid in the supercritical cleaning chamber supercritical. Finally, the carbon dioxide-induced metal wire in the supercritical cleaning chamber does not generate electric friction during the cleaning process. In order to make the above-mentioned and other purposes, features, and excellent features of the "X Ming Ming easy to understand", a preferred embodiment is described below, and the detailed description with the accompanying drawings is as follows. A substrate 300 is provided. First, a semiconductor substrate as shown in FIG. 3A is deposited and a dielectric layer 302 is deposited on the substrate so as to be oxidized by a tetraethoxy group (TEOS). The layer 302 is here. The dielectric layer is defined by a conventional lithography and etching method, and a conductive layer is deposited in the trench and on the dielectric layer. The conductive layer can be made of hafnium copper or tungsten. Flattening I t @ and forming a plurality of metal wires, liquid or particles during the flattening process. Chemical mechanical polishing left on the surface of the board

As shown in FIG. 2 ', the substrate 300 is placed in the ultra-critical cleaning chamber 2.8. Next, the "titanium dioxide power from the first storage system" is connected to the storage tank for the liberation / carbon oxide storage via the oxygen pipeline-the pipeline 202 and the second tube fiber which adds an emulsified chemical substance, With the first pump following the first tube; =-0.2 ~~ 0.6 litre extraction rate 'extracted into the supercritical cleaning chamber 208 mother ^ of which

1230982 V. Description of the invention (5) The pressure of the first storage tank is 25 to 35 atmospheres (ATM), the temperature is room temperature, and the stored carbon dioxide is liquid. In addition, by the second pump, the second pump m extracts the chemical substance that increases the degree of CO 2 to the rhyme of the rhyme residues into the supercritical cleaning chamber 208 to select = it can be methanol, benzene, and so on. The extraction step until the supercritical cleaning chamber 208 is completely filled with carbon oxide, and the pressure and temperature of the supercritical cleaning chamber 208 are increased, so that the back end of a pump 206 to the supercritical cleaning chamber 208 The pipeline was supercritically cleaned until carbon dioxide in 2008 was maintained in a supercritical state ... its temperature was 3 1 0. C ~ 5 0 0. C, the pressure is i 50 0 psi to 1000 psi, and the density at this time is 50 kg / W to 900 kg / ffl3. At the same time, the internal circulation of carbon dioxide in the supercritical cleaning chamber 2008 is increased to increase the cleaning effect, and the internal circulation speed may be 0.5 to 3 meters per second. After the cleaning is completed, the used carbon dioxide is extracted to the recovery system through the third pipeline 210 connected to the supercritical cleaning chamber 208 and the recovery system 212, and the reusable carbon dioxide is recovered through the connection. The second line 218 of the system 2 and the first storage tank 200 are pumped to the first storage tank 200 by the fourth pump 2 ^ 2 thereon and continue to be used. The non-reusable carbon dioxide is extracted to the heated exhaust system 2 through the fourth pipe 2 1 4 connected to the recovery system 2 1 2 and the heated exhaust system 2 1 6 and the third pump 2 2 0 thereon. ^ 16 discharge. After the cleaning step is completed, the substrate 300 is taken out, and the substrate 300 can be used to clean the metal surface by supercritical fluid to remove impurities generated during the planarization of the conductive layer and the metal wire does not cause current corrosion during the cleaning process. 1230982

Second Embodiment As shown in FIG. 3B, a base plate 3 0 0 provided with a plurality of metal wires 312 and teQnn Gan province & is provided with copper wires. Then, Shen: (TEOS) ○ ^ means the upper layer; the electrical layer to form a wire contact window 3, 6; and in the process, a human compound is left on the surface of the substrate 300. Residual photoresist, particles, or particles are left as shown in FIG. 2, and the substrate 3 is placed in an ultra-cleaning chamber 208. Next, oxidize ^ "糸 ,, super super 4 ^". 〇, the storage of two Lr via connection: ;;: storage tank (Tank plus carbon dioxide solubility of the first and second son of the chemical substance: = 202: connection increase by the first pump 20 on the pipeline 20 2 per minute : Said :: 203 'rate, pumped to the mother in the supercritical cleaning chamber 208? 0.2: 0.6: The pumping force is 25 ~ 35 atmospheres (ATM), and the pressure carbon in the storage tank A /, Zhongli 1 is liquid . In addition *, by connecting; J is for storage, to increase the solubility of carbon dioxide in the dioxide: / / quality, supercritical cleaning chamber 208 substance can be methanol or hydrogen peroxide U; 0 force ;; carbon oxide solubility The chemical extraction process is continued until the dioxide is broken and the supercritical cleaning is increased: 2 = Qingyou Chamber 20! Fully fills the back end of the first-pump 206 to the supercritical cleaning system and temperature, so that The force m of this chamber 2008's pipeline is supercritically cleared and t is held in a supercritical state: its temperature is ⑴.

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C ~ 500J C, the pressure is 150 psi ~ 1000 psi, and the degree of anaerobic dioxide at this time is 500 kg / m3 to 900 kg / m3. At the same time, the internal carbon dioxide generates internal circulation to increase the cleaning effect. The degree of the complex internal ring can be 0.5 to 3 meters per second. Eight internal circulation

After the washing of main, main, and 2 is completed, the used carbon dioxide is extracted to the recovery system through the third pipeline 210 connected to the supercritical cleaning chamber 208 and the recovery system 212, and the reusable The carbon dioxide is extracted through the fifth line 218 connecting the recovery system 2j 2 and the first storage tank 200 to the first storage tank 200 through the fourth pump 222 thereon and continued to be used. The non-recyclable oxidant is extracted to the heated exhaust gas through the fourth pipe 2 1 4 ′ connecting the recovery system 2 1 2 and the heated exhaust system 2 1 6 and the third pump 2 2 〇 thereon. System 216 is drained. After the cleaning step is completed, the substrate 300 is taken out. The substrate 300 can be used to clean the metal surface by supercritical fluid to remove impurities generated during the planarization of the conductive layer, and the metal wire does not cause current corrosion during the cleaning process. 0 Applicable The supercritical fluid in the present invention also includes but is not limited to: methane, ethane, propane, ammonia, nitrous oxide, monofluorinated methane, and difluorinated methane. Among them, the supercritical state of methane is a temperature of -100 ° c to -50 ° C 'and the pressure is 20 Bar to 60 Bar, and the supercritical state of ethane is a temperature of 15. C ~ 50 ° C, pressure is 20Bar ~ 60Bar, supercritical state of propane is 80 ° C ~ 120 ° C, pressure is 30Bar ~ 600Bar, supercritical state of ammonia water is 100 ° C ~ 150 ° C, pressure is 100Bar ~ 130Bar, supercritical state of nitrous oxide is 20 ° C ~ 50 ° C, pressure is 50Bar ~ 90Bar, supercritical state of monofluorinated methane is 30 ° C ~

0503-9936twf (nl); tsmc2002-1331; wayne.ptd Page 10 1230982 V. Description of the invention (8) 60 ° C, pressure 30Bar ~ 80Bar, supercritical state of difluorinated methane is 60 ° 0 100 ° (:, pressure is 40681 * ~ 80 6 & 1 '. Features and advantages of the present invention The feature of the present invention is to clean the wafer with a supercritical fluid, because the supercritical fluid does not have conductive properties and will not be affected during the cleaning process. The formation of a conductive circuit can prevent the phenomenon of current corrosion and solve the problem of current corrosion in the cleaning process of copper. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, some modifications and retouching can be made. Therefore, the protection scope of the present invention shall be determined by the scope of the appended patent application.

0503-9936twf (nl); tsmc2002-1331; wayne.ptd Page 11 1230982 Brief description of the drawings Figures 1 A to 1 B show the schematic diagram of the phenomenon of current corrosion caused by conventional component cleaning. Fig. 2 shows a system diagram of a supercritical fluid preparation device according to the present invention. FIG. 3A is a cross-sectional view showing a process of the first embodiment of the present invention. FIG. 3B is a cross-sectional view showing a process of the second embodiment of the present invention. Explanation of symbols Conventional technology I 0 0 ~ substrate; Φ 105 ~ N type metal oxide semiconductor; 110 ~ P type metal oxide semiconductor; STI ~ shallow trench insulator; II 5 ~ P type metal oxide semiconductor Drain electrode; source of 120-N metal-oxide semiconductor transistor; 125-first metal wire; 130-second metal wire. 203 ~ second pipeline 2 06 ~ first pump 210 ~ third pipeline 214 ~ fourth pipeline 218 ~ fifth pipeline 2 22 ~ fourth pump 0 technology of the present invention 2 0 2 ~ first pipe 2 0 4 ~ second storage tank; 208 ~ supercritical cleaning chamber 2 1 2 ~ recovery system; 2 1 6 ~ heating exhaust system 22 0 ~ third pump;

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Claims (1)

1230982 VI. The scope of the patent application provides f: ^ Electrolytic cleaning method, which includes the following steps. There are multiple i 2. The substrate has multiple n-type wells and 1 " type wells. The metal v-line in the well area has a potential difference; and the metal wire is cleaned after cleaning the substrate, so that the flow corrodes. The electric method for generating the metal wire due to the potential difference is described in item 1 of the present invention to prevent the current from being washed by neodymium corrosion. The semiconductor substrate is a semiconductor substrate. Method 3: ΐ !: ί: Cleaning of current corrosion prevention described in item 1 of the scope 'Eight Chinese metal wires are made of copper or tungsten. The cleaning method for preventing the current from being corrupted according to item 1 of the patent scope, wherein the fluid in the supercritical state is carbon dioxide. Fang, Guang Shi: The cleaning method for preventing galvanic corrosion as described in item 4 of the patent scope, wherein the supercritical state of the carbon dioxide is 31 ° C. c ~ 500 ° C, pressure is 1500pSi ~ 100000psi. 6. The cleaning method for preventing galvanic corrosion according to item 1 of the stated patent scope, wherein the fluid in the supercritical state contains at least methane, ethane, propane, ammonia, nitrous oxide, monofluorinated oxane, and difluoride Fluorinated pinane. 7. The cleaning method for preventing galvanic corrosion as described in item 1 of the scope of patent application, wherein the cleaning method further includes an internal circulation step to increase cleaning results. " 8. A cleaning method to prevent galvanic corrosion, including the following steps: providing a substrate; 1230982 VI. Application scope Deposition a dielectric layer on the substrate; define the dielectric layer to form a trench; deposit a conductive layer in the trench and on the dielectric layer; planarize the conductive layer to form a plurality A metal wire; and cleaning the metal surface with a supercritical fluid to remove impurities generated during the planarization of the conductive layer so that the metal wire does not cause galvanic corrosion during the cleaning process. 9. The cleaning method for preventing galvanic corrosion according to item 8 of the scope of patent application, wherein the substrate is a semiconductor substrate. 10. The method for preventing galvanic corrosion as described in item 8 of the scope of patent application, wherein the conductive layer is composed of copper or tungsten. 11. The cleaning method for preventing galvanic corrosion according to item 8 of the scope of the patent application, wherein the impurities are particles or a chemical mechanical polishing liquid. '1 2. A method for cleaning against galvanic corrosion as described in item 8 of the scope of the patent application, wherein the fluid in a supercritical state is carbon dioxide. 1 3. A method for preventing galvanic corrosion as described in item 12 of the scope of the patent application The cleaning method, wherein the supercritical state of the carbon dioxide is a temperature of 3 1 0 ° C ~ 5 0 0 ° C, and a pressure of 1 500 psi ~ 1000 psi. 1 4. Prevent electric current as described in item 12 of the scope of patent application Corrosion cleaning method, wherein the fluid in the supercritical state still includes methane, ethane, propane, ammonia, nitrous oxide, monofluorinated scorch, and difluorinated methane. 1 5. If the scope of patent application is the 8th The cleaning method for preventing galvanic corrosion according to the above item, wherein the cleaning method further includes an internal circulation step to increase the cleaning effect. 0503-9936twf (nl); tsmc2002-1331; wayne.ptd Page 15 1230982 6. Application for patent scope 1 6. A cleaning method to prevent galvanic corrosion, including the following steps: providing a substrate with a plurality of metal wires; deposition An upper dielectric layer on the metal wire; defining the upper dielectric layer to form a wire contact window; and cleaning the substrate with a supercritical fluid to remove impurities that define the upper dielectric layer so that the metal During the cleaning process, the wire does not generate electric rot. 1 7. The cleaning method for preventing galvanic corrosion as described in item 16 of the scope of patent application, wherein the substrate is a semiconductor substrate. 1 8. The cleaning method for preventing galvanic corrosion as described in item 16 of the scope of patent application, wherein the metal wire is composed of copper or tungsten. 19. The cleaning method for preventing galvanic money as described in item 16 of the scope of patent application, wherein the impurities are particles, photoresist or polymers. ‘20. The cleaning method for preventing galvanic corrosion as described in item 16 of the scope of the patent application, wherein the supercritical fluid is carbon dioxide. 2 1. The cleaning method for preventing galvanic corrosion as described in item 20 of the scope of the patent application, wherein the supercritical state of the carbon dioxide is a temperature of 3 1 0 ° C ~ 5 0 0 ° C and a pressure of 15 0 0 psi ~ lOOOOpsi ° 2 2. The cleaning method for preventing galvanic corrosion as described in item 20 of the scope of the patent application, wherein the fluid in the supercritical state still includes oxane, ethane, propane, ammonia, nitrous oxide, single Fluorinated methane and difluorinated methane. 2 3. The cleaning method for preventing galvanic corrosion as described in item 16 of the scope of patent application, wherein the cleaning method further includes an internal circulation step to increase the cleaning effect. 0503-9936twf (nl); tsmc2002-1331; wayne.ptd page 16 1230982 2j · A cleaning method for preventing galvanic corrosion, including the following steps: providing a substrate with a plurality of metal wires; 8. placing the substrate in a supercritical cleaning a, a supercritical cleaning system, wherein the supercritical cleaning chamber Connected to a first storage tank; and / or to draw a fluid from the first storage tank into the supercritical cleaning chamber · adjust the pressure and temperature of the supercritical cleaning chamber so that the Fluid is maintained in a supercritical state; and The carbon dioxide in the supercritical cleaning chamber is caused to circulate internally, so as to clean the substrate by using a fluid in a supercritical state in the supercritical cleaning chamber, so that the current does not corrode during the cleaning process. 25. The cleaning method for preventing galvanic corrosion as described in item 24 of the scope of patent application, wherein the substrate is a semiconductor substrate. 2 6 · The cleaning method for preventing galvanic corrosion as described in item 24 of the scope of patent application, wherein the metal wire is composed of copper or tungsten. 27. The cleaning method for preventing galvanic corrosion as described in item 24 of the scope of patent application, wherein the fluid in the supercritical state is carbon dioxide. 2 8 · The cleaning method for preventing galvanic corrosion as described in item 27 of the scope of the patent application, wherein the supercritical state of the carbon dioxide is 3 1 0. C ~ 500 ° C, pressure is 15000psi ~ 1000Psi. 2 9 · The cleaning method for preventing galvanic corrosion as described in item 27 of the scope of the patent application, wherein the supercritical fluid still includes methane, ethane, propane, ammonia, nitrous oxide, monofluorinated methane and Difluorinated methane. 30. The cleaning method for preventing galvanic corrosion as described in item 24 of the scope of the patent application, wherein the supercritical cleaning system further includes a recovery system connected to the 1230982 6. Scope of patent application The supercritical cleaning chamber, the first storage tank and a heating exhaust system are connected to the recovery system. Ο 0503-9936twf (nl); tsmc2002-1331; wayne.ptd page 18