TW426558B - Method of cleaning wafer after chemical mechanical polishing - Google Patents

Abstract

A method of cleaning a wafer after chemical mechanical polishing comprises brushing the wafer with a rotary brush wheel to substantially remove the particles remained on the wafer; washing the wafer using megasonic cleaning; adding an electrolyte into a deionized water, in which the electrolyte is harmless to the process and is soluble in the deionized water into ions; washing the wafer with the solution containing the electrolyte to completely remove the particles and charges remained on the wafer; applying a drying process on the wafer. The wafer can also be cleaned by the following process: cleaning the wafer using megasonic cleaning; brushing the wafer with a rotary brush wheel to substantially remove the particles remained on the wafer; adding an electrolyte into a deionized water, in which the electrolyte is harmless to the process and is soluble in the deionized water to form ions; washing the wafer with the solution containing the electrolyte to completely remove the particles and the charges remained on the wafer; and applying a drying process on the wafer.

Description

426558 V. Description of the invention (1) 5 -1 Field of the invention The present invention relates to a chemical mechanical polishing process for a semiconductor process ′ and more particularly to a wafer cleaning process after chemical mechanical polishing. 5-2 Background of the Invention: Chemical-mechanical polishing (CMP) is the only technology that can provide VLSI and even ULSI process global planarization at present. It uses the principle of mechanical grinding similar to "11 sharpening knife", and cooperates with appropriate chemical agents (reagent) to smooth the wafer surface of the wafer. Technology. Once the parameters of various processes are properly controlled, CMP can provide a flatness of more than 94% of the surface being polished. In the CMP process, we usually refer to the "siurry" as the chemical aid used It is mainly composed of colloidal silica (co 11 〇i da 1) or dispersed alumina (aluminum) and alkaline KOH or ΝH40Η and other solutions. The size distribution of these abrasive and high abrasive particles in the slurry is about 0.1. Basically, these extremely abrasive particles in the abrasive polymer are used to The surface of the wafer is polished. Of course, the composition of the slurry used in the CMP of different materials will be

426558 V. Description of Invention (2) is different. For example, in the CMP etchback of metallic tungsten, the composition of the research polymerization will include some oxidants and organic agents to help the CMP process. In general, the chemical removal process performed by CMP will involve extremely complicated chemical reaction mechanisms and various kinetic problems. During the mechanical removal process, the material to be removed on the wafer is removed by grinding through the structure formed by the polishing pad on the polishing table and the abrasive particles in the slurry. Taking the CMP of the Si 〇2 dielectric layer on the wafer as an example, the polishing pad material used is a polyurethane filled polyester material, which has a certain degree of elasticity in order to Different geometry

The surface of the wafer is mechanically polished. When the CMP process is in progress, the carrier (carr 1 er) holding the wafer will apply a certain pressure to the wafer, so that the structure formed by the polishing pad and the slurry is driven by the rotation and movement of the polishing table and the carrier. Next, the uniformity of the thin film on the wafer is removed. It is generally believed that when the pressure of the crystal moon is low and the rotation speed of the polishing table is fast, CMP can provide better flatness and affect CMP flattening. The main process parameters of the technology, in addition to the above-mentioned research composition, wafer pressure, and grinding speed, as well as the material of the grinding mill, the size distribution of the grinding particles in the grinding slurry (par tic Xia e

4 ^ 65 5 8 i but i on), but the basic type is not the same as the wafer, but the result of tungsten or depends on a layer to perform wafer division, so five, description of the invention (3) size distr The report of the operating parameters of the decisive effect of the material being polished shows that it has a greater impact; mechanical mechanical grinding is mainly used for CMP, such as Si3N4, etc., which requires slurry, thorough removal, supply of slurry, etc. Although the text is different. With Si 02 under pressure, the CMP of the revolving Shi Xi has a significant difference, which is called the termination layer. The cleaning of the surface is considered to be completed. Finishing speed, temperature, pfj value control these parameters. Some of the materials to be polished in the CMP process are the most important ones. For example, according to some research speeds and the types of polishing pads, the pH value The control will be different. Generally, the CMP process stop layer is deposited after the CMP process (post work, the remaining CMP process on the wafer. In the traditional chemical mechanical polishing (CMP) process, the wafer is polished) Two types of cleaning processes can be selected. See Figure A. 'The first is after the chemical mechanical polishing step 11, first brush cleaning l2, then megasonic cleaning 1 3 and deionized water. (Di —water ri nse) Steps 14 and 4 to completely wash away the wafer and then completely dry the wafer through a spindrying procedure 1 5; the second process is shown in the first B diagram, which is in chemical machinery After grinding for 16 years, 'first go through ultrasonic cleaning 17 and deionized water washing step 1 8 for washing' and then go through the brushing process 19 and then spin-drying process 21. When the first process is selected, the brushing process For the latter part of the entire cleaning process, but the bristles and wafers made of high polymer (such as nylon)

4? 6 5 5 8 V. The constant friction of the description of the invention (4) generates a large amount of electrostatic charges, which then remain on the wafer. Even in the subsequent spin-drying step, it cannot be removed. As for the completion of the entire CMP process, this charge still remains on the wafer and enters the subsequent process together, so it will cause troubles in the post-process and even damage the product quality. The impact caused by the quality cannot be ignored; even if the second cleaning described above is implemented The process' that is, the brushing procedure is placed in the previous step, and the subsequent deionized water washing step 'the deionized water used is electrically neutral (that is, it does not carry any charge)', so the charge on the wafer cannot be taken away. Will get the same results as the aforementioned first process, causing obstacles to the semiconductor process. β, for the reasons mentioned above. With the improvement of quality of current and future semiconductor products, it is necessary to develop a new CMP method to solve this 5-3 invention purpose and summary of generating electrostatic charges: In view of the above background of the invention, Disadvantages arising from the cleaning process The static electricity generated by the brushing step 7 'The wafer after chemical mechanical polishing is passed' The purpose of the present invention is to eliminate the above-mentioned & method of grinding and cleaning according to the present invention A chemical-mechanical dissociation ion is provided to remove the charge from the surface of the sun-dried tablets dissolved in carbon dioxide dissolved in deionized water, and the applied cleaning procedure

Page 8 426558 V. Description of the invention (5) There are at least two types' described in the two embodiments. In one embodiment, the wafer is first placed on a polishing pad, the polishing surface of the wafer is in contact with the polishing pad, and a slurry (s 1 ur ry) is added to the contact surface; and then the wafer is rotated on the polishing pad. And move, and grind the polishing surface of the wafer by grinding to flatten the wafer; use a rotating brush wheel to scrub the wafer to roughly remove the remaining particles on the wafer; then treat the wafer by ultrasonic cleaning; add a carbon dioxide gas to a In deionized water, this carbon dioxide gas is dissolved in deionized water to form three sons: money utilization has been added to this: this deionized water that vaporizes carbon gas, residual particles on the wafer; Drying program processing. In another embodiment, the wafer is placed on the grinding pad, and the grinding surface of the wafer is in contact with the grinding pad and: This contact surface is added with a slurry contact, and is cleaned in 2; Π :::: 晶 坦Add " Add-carbon dioxide gas in a deionized water% ::,: clever chip; here deionized water becomes ions; use J chemical, gas to dissolve ionized water, clean the wafer, and feed the carbon monoxide into Finally, the wafer is treated with the remaining particles and charges 9 on the second wafer. The dry process is used to process the 5 to 4 drawings. The month is a month: the first A picture is shown after chemical mechanical polishing. Flow chart of traditionally used wafer method.

Page 9 426558 V. Description of the invention (6) The first diagram B is a flow chart showing another conventional method for cleaning wafers after chemical mechanical polishing. FIG. 2A is a flow chart showing a method for cleaning a wafer after chemical mechanical polishing according to the present invention. FIG. 2B is a flowchart showing a second method for cleaning a wafer after chemical mechanical polishing according to the present invention. Representative symbols of the main parts: 11-21 Each step of the traditional cleaning process 2 2-33 Each step of the cleaning process of the present invention 5-5 Detailed description of the invention: The present invention is suitable for chemical mechanical polishing of semiconductor planarization process , CMP) and cleaning steps. In general CMP polishing, the equipment used includes at least a wafer carrier, a polishing pad, a slurry, and the like. The wafer is fixed with a wafer carrier, and the polishing surface of the wafer faces the polishing pad and is placed on the polishing pad (the polishing surface contacts the polishing pad), and a slurry (s 1 urry) is added to the contact surface, and then the wafer is applied. Rotate and move the polishing surface of the wafer with the slurry and pressure on the polishing pad to planarize. This is the basic principle of general CMP polishing. After this polishing is completed, many polishing particles (polishing particles) will remain on the wafer.

Page 10 42655 8 V. Description of the invention (7)) and the chemical reaction of private particles Subsequent processes must be removed from the spleen and porcine retentate, that is, cleaning 泱 p 彳., Sulphur cleaning. Figure A, the residual of the wafer (nylon, these sonic waves; then the water washing step to remove the ionized water and charge it with this method) spin-drying method in the cleaning process of one embodiment of the present invention, see the second when the wafer After the chemical-mechanical polishing step 22, first, a rotary brush-brush cleaning 23 is performed to roughly remove the wafer: particles. The material of the rotary brush wheel is usually an organic polymer such as nylon, which results from constant friction with the wafer. Many electrostatic charges will be generated on the surface of the wafer; then, the wafer is processed by megasonic cleaning 24, and the vibration function is used to remove the particles still attached to the wafer and remove them using water washing ( rinse) 25 steps to process (rinse) this wafer. The water used in this step is carbon dioxide (CO 2) gas is blown into DI water under pressure and dissolved and dissociated. Yin has carbonate ions and the pH value is about 5 to 6, so it can be removed from the wafer and completely remove the remaining particles on the wafer. It can also be used to dissolve carbon dioxide in water. To enter the gas; Finally, 'clean each wafer to dry without processing program, this program is available dried (spi n dry i ng) 26 is completed. Referring to the second diagram B, after the chemical mechanical polishing 27, in the cleaning process of the embodiment of the present invention, the ultrasonic cleaning 28 is first used as A ® Ming another-'Bujudi ~ steps · deionized water can be performed thereafter Rinse (rinse) 2 9, wash the wafer, + +, 'T, then the deionized water washing step 2 9 can also be omitted; then use a rotating brush to add the wafer to the " 9.

Page 11 426558 V. Description of the invention (8)-The brushing step 30 is performed. As described in the previous embodiment, this brushing (cleaning at the mouth) step 30 will leave an electrostatic charge on the crystal moon; The step of sonic cleaning 31 (also can be omitted); the next cleaning step only needs to wash away the remaining particles, and must also be able to remove the above charge from the lamp, using the same method as the previous embodiment, that is, in the Ionized water enters carbon dioxide, dissolves and dissociates, and then uses this water to perform the J step 32 on the wafer. The final drying step can also use the spin-drying method 33 to dry the wafer. \ In the above two embodiments, the most common point is It uses two = charged ions dissociated after deionized water to remove the static on the wafer. What's more, the main steps of the two yoke examples are the same, except that some steps are changed. Both are used as crystals after CMP polishing. It is used for monthly cleaning, and it can remove the electrostatic charge generated on the surface of the wafer where the brush is located, so that the wafer can maintain good quality. — The above description is only a preferred embodiment of the present invention, which is used to limit & the scope of patent application of the present invention; all other specific changes or modifications that do not depart from the spirit disclosed by the present invention, All should be included in the scope of patent application described below.

Claims (1)

426558 VI. Residues in the scope of patent application 1. A method for cleaning a wafer after chemical mechanical grinding, including at least: "Washing the wafer with a rotating brush wheel" to substantially remove particles on the wafer and treating the wafer by ultrasonic cleaning ; Add an electrolyte to a deionized water, the electrolyte must be harmless and dissolved in the deionized water to become ions; use the deionized water with the electrolyte added to clean the wafer, r completely remove the residue on the wafer Particles and charges; and Λ processes the wafer in a drying process. 2. The method according to item (1) of the scope of patent application, wherein the material of the above-mentioned rotating brush wheel contains at least one organic polymer 3. The method according to item (2) of the scope of patent application, wherein the above organic polymerization includes at least nylon. Cut 4: For example, the method of item (2) of the Ming patent, in which the above-mentioned ultrasonic cleaning is to remove particles on the wafer from the surface of the wafer by the principle of ultrasonic oscillation. 5. The method according to item 1 of the patent application range, wherein the above electrolyte contains at least two atmosphere carbons. 6_ The method according to item 1 of the scope of patent application, wherein the above-mentioned electrolyte is at least Page 13 426558 VI * Patent Application Fan Garden Contains a gas electrolyte. 7. The method according to item 6 of the scope of patent application, wherein said gas electrolyte contains at least carbon dioxide gas. 8. The method according to item 1 of the patent application range, wherein the pH of the deionized water after the electrolyte is added is about 5 to 6. 9. The method of claim 1 in the scope of patent application, wherein the above-mentioned drying process includes at least spin drying 13 1 〇.-A method of cleaning a wafer after chemical mechanical polishing, including at least an ultrasonic cleaning process Process the wafer; scrub the wafer with a rotating brush wheel; add an electrolyte to deionized water; the electrolyte must be harmless to the process and be dissolved in the deionized water to become ions; using the deionized water to which the electrolyte has been added, Cleaning the wafer to completely remove particles and charges remaining on the wafer; and processing the wafer in a drying process. 11. The material of the method according to item 10 of the patent application scope includes at least one organic polymer. wheel Page 14 4 265 5 8 6. Scope of patent application 12. The method according to item 11 of the scope of patent application, wherein the above organic polymer contains at least nylon. 13. The method according to item 10 of the patent application range, wherein the above-mentioned ultrasonic cleaning procedure is to remove particles on the wafer from the surface of the wafer by the principle of ultrasonic oscillation. 14. The method according to item 10 of the patent application scope, wherein the above-mentioned electrolysis contains less carbon dioxide. 15. The method of claim 10 in the scope of patent application, wherein the above-mentioned battery includes a gas electrolyte. : To two: The method of the 15th item of the range of Γ '. The above-mentioned gas electrolyte includes / contains carbon dioxide gas. 17. The method according to item 10 of the scope of patent application, wherein the pH of the deionized water 'after the quality of the coffee is divided into about 5 to about 6. ~ 1 to 8 less UL "Method of item η1." The above-mentioned drying procedure Wei Xiba 3 spin drying. 19 ’A kind of chemical mechanical polishing and cleaning in a semiconductor process. The method includes: Page 15 426558 VI. Scope of patent application Place a wafer on a polishing pad, visit ^ 0 to recognize that the grinding surface of the “A” secret piece of “a” is in contact with the polishing pad, and add slurry to this contact surface (slur Rotate the wafer on the grinding wheel 44 & 'Swirl and move, and use the slurry to grind the grinding surface of the wafer to flatten; coffin XW scrubs the wafer with a rotating brush wheel, w λ, Day and month to roughly remove the particles remaining on the wafer; process the wafer by ultrasonic cleaning; add a carbon dioxide gas to a deionized water, the carbon dioxide gas is dissolved in the deionized water to become ions; using the carbon dioxide that has been added Gas, the deionized water, cleaning the wafer to completely remove particles and charges remaining on the wafer; and processing the wafer with a drying process. 20_ The method according to item 19 of the patent application scope, wherein The material of the rotating brush wheel includes at least one organic polymer. 21. The method according to item 20 of the patent application scope, wherein the above organic polymer includes at least nylon. 22. For example, the method of item 19 in the scope of patent application, wherein the above-mentioned ultrasonic cleaning is to remove particles on the wafer from the surface of the wafer and remove them by the principle of ultrasonic oscillation. Method wherein the above carbon dioxide Page 16 426558 VI. Scope of patent application The gas system is directly dissolved in the deionized water by using air pressure. 24. The method according to item 19 of the patent application park, wherein the pH of the deionized water after adding the carbon dioxide is about 5 to 6. 25. The method of claim 19 in the scope of patent application, wherein the above-mentioned drying process π. ,, '^ drying process at least includes spin drying (sp i n dry i ng). 26 · A chemical mechanical polishing and cleaning process in a semiconductor manufacturing process includes: until a wafer is placed on a polishing pad, the polishing surface of the wafer is in contact with the polishing pad, and a slurry is added to the contact surface; ° > Rotate and move the wafer on the polishing pad, and use the slurry to grind the polishing surface of the wafer for flattening; process the wafer with an ultrasonic cleaning program; scrub the wafer with a rotating brush wheel; body ice S oxidizes and breaks the gas in deionized water, and the carbon dioxide gas is made into ions in the deionized water; the wafer is washed with the deionized water that has been immersed in the carbon dioxide, and is removed by imitation Particles and charges remaining on the wafer; and processing the side wafer in a drying process. The second method of the 26th item of the Li Chao Dynasty is that the material of the rotating brush wheel described at least contains organic polymer. Page 17 426558 VI. Scope of patent application 28. For the method of scope 27 of the patent application, the above-mentioned organic polymer includes at least nylon. 29. The method of claim 26, wherein the above-mentioned ultrasonic cleaning procedure is to remove particles on the wafer from the surface of the wafer by using the principle of ultrasonic oscillation. 30. The method of claim 26, wherein the pH of the deionized water after the carbon dioxide is added is about 5 to 6. 31. The method according to item 26 of the patent application, wherein the above drying process includes at least spin drying. Page 18