TW464972B - Wafer cleaning process added with ozone - Google Patents

Abstract

A wafer cleaning process includes: executing an APM cleaning step by using solution composed of ammonia water and hydrogen peroxide for cleaning and then washing the wafer, wherein ozone is continuously added in the washing step; then, executing a HPM cleaning step by using solution composed of hydrochloric acid and hydrogen peroxide; then, washing the wafer again, which is similar to the above washing step in continuously adding ozone; next, using diluted hydrofluoric acid to perform a cleaning step and continuously adding ozone in the process; after that, drying the wafer. The above approach of adding ozone includes, but is not restricted to: (1) linearly increasing the concentration of the ozone by the time; (2) stepwise increasing the concentration of the ozone by the time; and (3) keeping the concentration of the added ozone in a constant value by adding a specific amount of ozone periodically.

Description

V. Description of the invention (1) Field of the invention: The present invention relates to a semiconductor process. In particular, a new method is applied to the wafer cleaning process, which uses ozone to improve the characteristics of the oxide layer in the wafer cleaning process. . Background of the Invention: The integrated circuit (1C) has been significantly improved in technology. Increasing the density of electronic components has suddenly become a trend. 3 By reducing the size of electronic components, the integration density of semiconductor integrated circuits can be increased. As the size of electronic components has been reduced, integrated circuits continue to present many new challenges in the manufacturing process. As the density of wafers on semiconductor wafers continues to increase, the role of each process is also important. Based on the rapid progress of integrated circuit technology, the line width of integrated circuits has reached the level of subtle dullness. When entering the generation where the line width is less than 0.8 microdulls, the conditions of various processes are stricter than before. 3 Integrated circuits all involve a technology for cleaning the surface of the wafer. There are usually two types of dry cleaning and wet cleaning. Generally, in some cases, the above-mentioned cleaning method must be used to process the film layer to facilitate the subsequent process. . It is more critical to deal with the above steps before the component is reduced. Therefore, it is a challenging task to make effective cleaning of the wafer surface in sub-micron technology. In integrated circuits, the well-known RCA process is often used to clean wafers, which is classified as a wet c leaning method. It mainly includes two successive cleaning steps, first called SC-l (standard cleaning

Page 4 4 6 4 9 7 :::: V. Description of the invention (2) 1) The step is to use a mixed solution composed of ammonia, hydrogen peroxide and water as a cleaning solution. The general mixing ratio is about Operating from 1: 1: 5 to J: 2: 7 at 70 to 80 degrees Celsius. The second step is called SC-2 (standard cleaning 2). The composition of the mixed solution is composed of hydrogenated gas, hydrogen peroxide, and water, according to the mixing ratio of 1: 1: 6 to 12: 8. The mixing temperature at which the cleaning is performed is about 70 to 80 degrees Celsius. The sc-1 and SC-2 mentioned above are all formulated by cleaning with an aqueous solution containing hydrogen peroxide. At high pH, S (> 1 has the ability to remove oxides and organic components. Under low pH, sc_2 can remove metal components. So far, some selective steps have been added to previous cleaning steps.) Figure 1. Figure 1 shows the cleaning process of the prior art, which is generally referred to as the IMEC-clean SOM cleaning process (note: iMEC-clean technology is

Interumversity Micro electronic Center development), first put the wafer in S 0 M 100 and add Hao gas to clean, generally this step can also include sulfuric acid, hydrogen peroxide, ozone aqueous solution 3 and then place the wafer in the fast direction Wash in a quick down step (QDR) 110. The oxide component is then removed from the solution 1 2 0 containing the HF / HC 1 component. The wafer is then transferred to a cleaning tank for rinsing 130, and then the spin-drying machine (marangonl dry) 140 is used to remove moisture from the wafer. Figure 2 shows another prior art process, which is generally called IMEC-clean Ozone cleaning process = first the wafer is placed in water containing ozone

Page 5 46-7 _ — V. Description of the invention (3) 'Remove particles from solution 1 0 0 a. Next, the wafer is placed in a solution containing HF / fi C 1 1 2 0 a to remove the emulsified component 3, and then the wafer is transferred to a washing tank to be washed 1 3 0 a, and then the spin drying technology is used in a spin dryer. 1 4 〇a removes moisture from the wafer. Figure 3 shows the operation flow of the conventional technology. Step 3 1 0 is mainly to clean the wafer with deionized water (ο ζ ο n e D I w a t e r) containing ozone, and the ozone concentration is about 5 ppm. The next step 3 2 0 is to use an aqueous solution containing hydrofluoric acid (0.5%) / hydrogen peroxide (0, 1-0.5%) plus a surfactant, and then remove the particles by ultrasonic vibration. Next, the wafer is washed with deionized water (ozone about 1 p p m) containing odor plus ultrasonic vibration for washing the wafer, step 3 3 0. 1%。 The wafer is then treated with diluted hydrofluoric acid (DHF) in step 3 40, with a content of about 0.1%. The wafer is then transferred to a cleaning device using deionized water in combination with a parallel downward flow and ultrasonic cleaning, step 3 50. The final step 360 is to make the wafer dry 3 and based on the continuous shrinking of the element size, the requirements for particle cleanliness are more stringent, and the gate oxide integrity (GOI) requirements are even more stringent. high. The above-mentioned cleaning technology has a certain content of ozone-doped in the cleaning device, and the ozone component solution attenuates, reducing the effect of cleaning. In addition, the conventional technology usually needs to switch the cleaning machine to reduce the cleaning. Process efficiency. Therefore, the present invention proposes a new cleaning process ° IHHI 1 ^ ·! 464972 V. Description of the invention (4) Purpose and summary of the invention: The purpose of the present invention is to provide a cleaning process to improve the phenomenon of poor cleaning in the prior art. . Another object of the present invention is to improve the efficiency by using a single cleaning tank device. Still another object of the present invention is to improve the quality and efficiency of washing by adding low content ozone concentration, linear addition step or multiple compound step addition method or variable concentration addition method or step concentration method. The wafer cleaning process of the present invention includes performing an AP cleaning step, and washing with an aqueous solution composed of ammonia and hydrogen peroxide. Thereafter, the wafer is washed, and ozone is continuously added during the washing step. The concentration range of the above-mentioned added ozone can be between about 10 and 1Q ρ ρ Π1. The way to add odor includes but is not limited to: (1) linearly increase the ozone concentration according to time. (2) Stepwise increase the ozone concentration over time. (3) Keep the content of ozone added at a certain value, and add a specific amount of ozone every time a period passes. Next, a QPM washing step is performed, including the use of hydrogen chloride, peroxide

Page 7 V. Description of the invention ¢ 5) 'Aqueous solution made of hydrogen. Then, the wafer is rinsed again, and the ozone is continuously added during the rinse step. Next, ozone was continuously added during the washing step 'using the diluted hydrofluoric acid. Rinse the wafer with a solution containing deionized water or water and add ozone. After completion, the wafer is dried. Detailed description of the invention: The method disclosed in the present invention is a method for improving the efficiency and effectiveness of the cleaning process. The method disclosed in the present invention includes, but is not limited to, treating oxides, metals, and organics on the wafer surface to improve the cleaning effect. In addition, the present invention mainly uses a single cleaning tank to perform a cleaning process to improve efficiency. Its detailed description will be as follows. It is characterized in that it is added at a low concentration of ozone content, and the addition of ozone is divided into multiple steps during the cleaning cycle, and the injected ozone concentration is changed to improve the stability of the cleaning process. Refer to FIG. 4 'for an example of a schematic configuration of the method device. Contains an adjustment container 400 connected to a process bath 410. The deionized water pipe is connected to the deionized supply (not shown) and the regulating container 400 for supplying deionized water, and the ozone pipe is similarly connected to the ozone supply device (not shown) and the regulating container 400 described above. Referring to FIG. 5, firstly, a semiconductor material can be prepared or provided as a substrate or wafer first. For example, a single crystal silicon having a crystal orientation of < 1 0 0 > can be used as an embodiment of the present invention.

V. Description of the invention (6) ‘Example wafer’ followed by some known processes such as those already made on wafers. Then in step 500, the present invention uses a solution to treat the crystal round surface to facilitate the removal of particles, organic matter or metal particles. For a preferred embodiment, the above-mentioned solution formulation uses a solution called APM (amm ο ni η peroxide mixture; A PM), which includes ammonia water (nh40h) and hydrogen peroxide (H202). Of an aqueous solution. APM treatment can restore (r e c ο ν e r) the surface of the crushed dioxide to reduce its coarse shuttle. In one embodiment, the temperature range of the same APM step is about 40 to 80 degrees Celsius. The composition of the solution has a volumetric concentration ratio of ammonia water (NH40H): argon peroxide (H2 02): water (H20) of about 1: 2-6: 15-2 5 and a ratio of 1: 4: 2 0. The steps are similar to those of SC-1. The wafer is then cleaned in a Qulck Down nnse (QDR) 510. It is worth noting that ozone needs to be added in this step, but it is not a one-time dosing as in the Senco technology. The method of adding it is shown in FIG. 6, which is a time-concentration relationship garden for adding ozone according to the present invention. It can linearly increase the concentration of ozone depending on time, and its added concentration range can be between about 10 and 100 ppm. One of the steps to add ozone = The example is to increase the concentration in a stepwise curve over time. If the mother interval is a specific time period, increase the concentration of ozone. The concentration range can also be suggested to be between 10 and 10. Between 0 ppm. Secondly, the content of ozone can be maintained at a certain value, but every time period, the

Page 9 丨] u: ______ V. Description of the Invention (7) '' This specific amount of ozone. The next step (step 5 2 0) is to perform the ΗPM cleaning process. The composition of the mixed solution is composed of hydrogen chloride, hydrogen peroxide, and water, and is mixed according to the ratio 1: 1: 1: 6 to 1: 2: 8. Proportional mixing, the temperature at which cleaning is performed is about 70 to 80 degrees Celsius, and HPM can remove metal components. Then, a quick down washing step (quick down r 1 n s e; Q D R) is performed to clean the wafer. In the same way, ozone needs to be added in this step. The method of adding ozone is similar to that in step 5 10, please refer to Figure 6. It can linearly increase the concentration of ozone according to time, or increase its concentration over time in a step curve manner or add ozone at a specific time period = the content of ozone added can be between about 10 and 100 ppm . The next step. Step 5 40 is to perform the washing step with diluted hydrofluoric acid, including adding ozone, and the composition of the mixed solution is composed of hydrogenated gas, ozone, and water. After the wafer is rinsed with deionized water or water and ozone is continuously added in the manner described above, step 5 50. After that, the moisture on the wafer is removed by using a drying technology, which may generally include spin-drying technology, heating method or airflow technology to remove the liquid components on the wafer. 3 The advantages of the present invention are:

Page 10 464972 V. Description of the invention ¢ 8) * (1) Reduce the washing process time. (2) Improve the efficiency of adding ozone. (3) Improve the characteristics of GOI. The present invention has been described above with reference to the preferred embodiments, and those skilled in the art can make some modifications without departing from the spirit of the present invention. For example, although the present invention provides a way to add ozone content, it is not intended to limit For its method, the scope of its patent protection depends more on the scope of the attached patent application and its equivalent fields.

Page 11 46 /: Brief description of the drawings Icon Description • The preferred embodiment of the present invention will be explained in more detail with the following figures in the following description: Figure 1 shows the cleaning process of the conventional technology. Figure 2 shows the process of another conventional technique. Figure 3 shows the process of another technique. Figure 4 shows the configuration of the invention. Fig. 5 is the cleaning process of the invention = Fig. 6 is a graph showing the time concentration of ozone added according to the invention. Drawing number comparison table: 100 Place the wafer in the SOM 110 Place the wafer in the Quick Down Wash Step (QDR) 120 Use the HF / HC1 solution to remove the oxide component 130 Transfer the wafer to the washing tank and rinse 140 Remove Moisture on the wafer 100a Place the wafer in an odorous aqueous solution 120a Place the wafer in a solution containing HF / HC 1 130a Transfer the wafer to a cleaning tank Rinse 140a Use spin-drying technology to remove the water on the wafer 310 Use Wafer 320 was washed with deionized water containing ozone, and was dissolved in water containing hydrofluoric acid (0.5%) / hydrogen peroxide (0.1 -0, 5%).

The diagram on page 12 is a simple explanation. The liquid is removed by ultrasonic vibration. 3 3 0 is deionized water containing ozone (ozone is about 1 ppm), and ultrasonic vibration is used to rinse wafer 340 to dilute the hydrofluoric acid (DHF). ) Treatment 3 5 0 Use deionized water with parallel downward water flow plus ultrasonic cleaning 3 6 0 Dry the wafer 40 ◦ Adjust the container 410 Washing process device (process bath) 5 0 0 Use AP Μ solution Treat the surface of the wafer to facilitate the removal of particles, organics, or metal particles 5 1 0 Place the wafer in a rapid downward cleaning step (QDR) 5 2 0 Perform a ίΡΜ cleaning process 5 3 0 Perform a rapid downward cleaning step ( QDR) 5 4 0 Use the diluted hydrofluoric acid to perform the washing step 5 5 0 Wash the wafer with deionized water or water to rinse the wafer 5 6 0 to dry the wafer

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Claims (1)

497 2__ VI. Application for Patent Scope 1. A wafer cleaning process, the wafer cleaning process includes: performing an AP cleaning step using an aqueous solution containing ammonia and hydrogen peroxide; rinsing the wafer, Ozone is continuously added during the rinsing step; the HPM cleaning step is performed using an aqueous solution containing hydrogen chloride and hydrogen peroxide; the wafer is rinsed again, and the ozone is continuously added during the rinsing step; the diluted hydrogen fluoride is used The washing step performed by the acid includes adding ozone; the wafer is rinsed with a solution containing deionized water or water and includes continuous addition of the ozone; and the wafer is dried 3 2. The wafer cleaning as described in the first scope of the patent application In the net process, the temperature range of the above AP step is about 40 to 80 degrees Celsius. 3. For the wafer cleaning process of item 1 of the scope of the patent application, wherein the volume concentration ratio of the above ammonia water: hydrogen peroxide: water is about 1: 2-6: 1 5-2 5, preferably 1: 4 : 2 0. 4. For the wafer cleaning process of item 1 of the patent application scope, wherein the method of adding ozone includes linearly increasing the ozone concentration according to time. 5. The wafer cleaning process according to item 4 of the patent application range, wherein the concentration range of the above-mentioned added ozone can be between about 10 ppm and 100 ppm. Page 14 6. Scope of patent application 6 For the wafer cleaning process of item 1 of the scope of patent application, the above-mentioned method of adding ozone includes stepwise increasing the ozone concentration over time. 7. If the wafer cleaning process of item 6 of the patent application is applied, the concentration range of the above-mentioned added ozone can be between about 10 and 100 p p m. 8. If the wafer cleaning process of item 1 of the patent scope is applied, the above-mentioned way of adding ozone includes keeping the content of the ozone added to a certain value, and adding a specific amount of the ozone every time period. 9. If the wafer cleaning process for item 8 of the patent application scope, wherein the concentration range of the ozone added above can be between about 0 and 100 ppm = 1 〇. For example, the wafer cleaning process for the first scope of patent application scope In the manufacturing process, the temperature range of the above-mentioned ΗPM step is about 70 to 80 degrees Celsius. 1 1. The wafer cleaning process according to item 1 of the scope of the patent application, wherein the volume concentration ratio of hydrogen gas: hydrogen peroxide: water is about 1: 1: 6 to 1: 2: 8. 1 2. —Seed crystal over-cleaning process ”The wafer cleaning process includes: (1) performing an AP cleaning step ′ using an aqueous solution composed of ammonia and hydrogen peroxide; Page 15ά ^ Α 9 7 _______ 6. Scope of patent application (2) Rinse the wafer, and ozone is continuously added during this washing step; C 3) Perform a ΗPM cleaning step, using hydrogen chloride and hydrogen peroxide. The composition of the aqueous solution; (4) Repeat step (2); (5) Perform the washing step using diluted hydrofluoric acid, including performing step (2); (6) Rinse the wafer with deionized water or an aqueous solution And includes performing step (2); and drying the wafer. 1 3. If the wafer cleaning process of item 12 in the scope of patent application, the temperature range of the above A PM step is about 40 to 80 degrees Celsius 3 1 4. If the scope of the patent application area is in paragraph 12 Wafer cleaning process, wherein the volume concentration ratio of the above-mentioned ammonia water: hydrogen peroxide: water is about 1: 2-6: 1 5-2 5, preferably 1: 4: 2 〇 α 1 5. If applying for a patent The wafer cleaning process of the item 12 in the range, wherein the method of adding ozone in step (2) above includes linearly increasing the ozone concentration according to time. 16. The wafer cleaning process according to item 15 of the scope of patent application, wherein the concentration range of the above-mentioned added ozone can be between about 10 and 100 ppm. 1 7. The wafer cleaning process according to item 12 of the patent application scope, wherein the above steps Page 16 41 B // 6. Patent Application Scope The step (2) of adding ozone includes increasing the ozone concentration over time in a step curve manner. 18 If the wafer cleaning process of item 17 in the scope of patent application is applied, the concentration range of the above-mentioned added ozone may be between about 10 and 0 0 p p m. 19. If the wafer cleaning process according to item 12 of the patent application scope, wherein the method of step (2) above, the method of adding ozone includes keeping the content of ozone added to a certain value, and adding the specific amount after each time period. The ozone. 2 〇. For the wafer cleaning process of item 19 in the scope of patent application, wherein the concentration range of ozone added above can be between about 0 and 0 0 pp ra 3 2 1. If the scope of patent application is in item 12 In the wafer cleaning process, the temperature range of the above HPM step is about 70 to 80 degrees Celsius. 2 2. If the wafer cleaning process according to item 12 of the patent application scope, wherein the volume concentration ratio of argon chloride: hydrogen peroxide: water is about 1: 1: 6 to 1: 2: Page 17