TW201432807A - Silicon wafer cleaning method - Google Patents

Abstract

A silicon wafer cleaning method is provided. Firstly, a silicon wafer is provided. Then, a polymer cleaning step is performed to clean a surface of the silicon wafer. After the polymer cleaning step, a deionized water/carbon dioxide gas decharging step is performed, so that the charges accumulated on the surface of the silicon wafer can be instantly removed. After the deionized water/carbon dioxide gas decharging step, two or more particle removing steps are performed. In addition, an air-jet step is performed during the time interval between every two sub-steps of the single particle removing step. Consequently, the cleaning efficiency of removing the particles will be enhanced.

Description

矽 wafer cleaning method

The present invention relates to a wafer cleaning method, and more particularly to a wet cleaning method for a tantalum wafer.

In the manufacturing process of the integrated circuit on the semiconductor wafer, each step including etching, oxidation, deposition, photoresist removal, and chemical mechanical polishing is a source of wafer surface contamination, and thus requires repeated cleaning. The continued reduction in component size and gate oxide thickness makes wafer surface cleanliness more demanding.

The main purpose of surface cleaning is to remove all trace contaminants such as organic matter, polymers, metals, particles, etc., and control the oxide film formed on the surface.

Generally, the step of cleaning the surface of the wafer having the gate structure comprises: first cleaning the surface of the wafer with a sulfuric acid/ozone mixture (SOM), and then performing standardized first cleaning (standard clean) 1, referred to as SC1) and air-jet treatment (Air-Jet). However, when the wafer is cleaned by SOM, the surface of the wafer tends to accumulate a large amount of charge, and subsequent cleaning steps accumulate a lot of charge on the surface of the wafer. When the surface charge of the wafer exceeds the saturation critical point, a volcanic effect of charge is generated, which in turn causes the structure of the wafer surface to be destroyed.

In view of this, it is necessary to propose a new silicon wafer cleaning method to improve the cleaning efficiency of the germanium wafer and the yield of the components on the wafer.

The present invention provides a silicon wafer cleaning method to improve component yield on a germanium wafer after cleaning.

The invention provides a silicon wafer cleaning method to improve the cleaning efficiency of the germanium wafer.

In order to achieve the above advantages or other advantages, an embodiment of the present invention provides a method for cleaning a silicon wafer, comprising: providing a germanium wafer; performing a polymer cleaning process on the surface of the germanium wafer; and twinning after the polymer cleaning process The surface of the circle is subjected to a deionized water plus carbon dioxide de-charge process; and after the deionized water is added with a carbon dioxide de-charge process, the surface of the wafer is subjected to a particle cleaning process and an air jet process.

The invention further provides a method for cleaning a silicon wafer, comprising: providing a germanium wafer; performing a polymer cleaning process on the surface of the germanium wafer; and performing a first particle cleaning process on the surface of the germanium wafer after the polymer cleaning process; After the first particle cleaning process, the surface of the germanium wafer is subjected to air jet treatment; and after the air jet process, the second particle cleaning process is performed on the surface of the germanium wafer.

In summary, the wafer cleaning method of the present invention is mainly after the polymer cleaning process, that is, the deionized water plus carbon dioxide de-charge process is continued. Alternatively, the time of the polymer cleaning process is disassembled and divided, and after the first polymer cleaning process, the deionized water is added to the carbon dioxide decharge process, and then the polymer cleaning process is repeated. In this way, the charge accumulated on the surface of the wafer can be removed immediately, and the accumulation of charge on the surface of the wafer can be continued due to the subsequent cleaning process, thereby causing the volcanic effect of the charge. In addition, the wafer cleaning method of the present invention also performs a single particle cleaning process in stages, and inserts an air jet process between the two particle cleaning processes. Such a process design can improve the cleaning efficiency of the particle cleaning process to achieve complete removal of the particles attached to the surface of the wafer.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

210‧‧‧ Providing silicon wafers

220a, 220b‧‧‧ Polymer cleaning process

232a, 232b‧‧‧High temperature deionized water cleaning process

234a, 234b, 260‧‧‧ Deionized water plus carbon dioxide decharge process

240a, 240b‧‧‧ for particle cleaning process

250a, 250b‧‧‧Air jet treatment

20‧‧‧矽 wafer

21, 22, 25‧ ‧ 矽 gate structure

23‧‧‧ polymer

24‧‧‧Microparticles

1A is a schematic flow chart of a wafer cleaning method according to an embodiment of the present invention.

FIG. 1B is a schematic view showing the structure of a germanium wafer cleaned by the wafer cleaning method of FIG. 1A.

2A is a schematic flow chart of a wafer cleaning method according to another embodiment of the present invention.

2B is a graph showing changes in charge accumulation amount on the surface of the germanium wafer corresponding to steps 220a to 234b of the wafer cleaning method flow of FIG. 2A.

3A is a schematic flow chart of a wafer cleaning method according to another embodiment of the present invention.

FIG. 3B is a graph showing changes in particle removal efficiency corresponding to steps 240a to 250b of the wafer cleaning method flow of FIG. 3A.

Figure 3C is a graph showing the etch rate versus time for a single particle cleaning process on the wafer surface.

1A is a schematic flow chart of a wafer cleaning method according to an embodiment of the present invention. FIG. 1B is a schematic view showing the structure of a germanium wafer cleaned by the wafer cleaning method of FIG. 1A. Please refer to FIG. 1A and FIG. 1B together. The silicon wafer cleaning method of this embodiment includes: providing a germanium wafer (step 210), wherein the germanium wafer surface may be a surface of the germanium wafer 20 on which the germanium gate structures 21, 22, 25 are formed. A surface cleaning process is then performed on the surface of the germanium wafer 20 (step 220a). The polymer cleaning process (step 220a) may be a process of cleaning the surface of the germanium wafer 20 by using a sulfuric acid/ozone mixture (SOM) cleaning agent (hereinafter referred to as SOM cleaning). It is used to remove the polymer 23 produced on the surface of the tantalum wafer 20 by the previous process.

After the polymer cleaning process (step 220a), the surface of the germanium wafer 20 is sequentially subjected to a high temperature deionized water cleaning process (step 232a) and a deionized water plus carbon dioxide decharge process (step 234a). After performing the deionized water plus carbon dioxide de-charge process, the surface of the germanium wafer 20 is sequentially subjected to a particle cleaning process (step 240a) and air jet processing (Air-Jet) (step 250a). The temperature of the high-temperature deionized water is, for example, 70 ° C, and the process temperature of the deionized water plus carbon dioxide de-charge is, for example, room temperature. The above-described particle cleaning process (step 240a) is, for example, a standard clean 1 (SC1) process. The above SC1 cleaning process generally uses a mixture of ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and deionized water (DI water) to oxidize germanium atoms on the surface of the germanium wafer 20 and etch it slightly. The surface of the wafer 20 is removed to remove the particles 24 attached to the surface of the germanium wafer 20. The air jet treatment (step 250a) is for removing yttrium oxide and fine particles 24 remaining on the surface of the tantalum wafer 20 and drying the surface of the tantalum wafer 20.

The reason for the above process flow design is that after the surface of the germanium wafer 20 has undergone the above polymer cleaning process (step 220a), the temperature of the surface of the germanium wafer 20 is about 150 degrees C, so in the preferred case, High-temperature deionized water needs to be used to clean the surface of the germanium wafer 20 to avoid a sudden drop in temperature on the surface of the germanium wafer 20, resulting in defects in the product. In addition, after the germanium wafer 20 passes through the above polymer cleaning process (step 220a), the surface of the germanium wafer 20 tends to accumulate a large amount of electric charge. Therefore, after the high temperature deionized water cleaning process (step 232a) is performed, the deionized water plus carbon dioxide decharge process is immediately performed (step 234a) to instantly remove the charge accumulated on the surface of the germanium wafer 20. In this way, it is possible to avoid accumulating charges on the surface of the germanium wafer 20 due to the subsequent cleaning process, thereby causing a volcanic effect of charges to destroy the germanium gate structures 21, 22, 25 on the surface of the germanium wafer 20.

Referring to FIG. 2A, in another embodiment of the present invention, a germanium wafer is first provided (step 210), and then the polymer cleaning process (step 220a) and the high temperature deionized water cleaning process (step 232a) may be sequentially performed. After the deionized water is added to the carbon dioxide decharge process (step 234a), the polymer cleaning process (step 220b), the high temperature deionized water cleaning process (step 232b), and the deionized water plus carbon dioxide decharge process are sequentially repeated. Step 234b) at least one cycle, and the number of times can be adjusted according to the process requirements, and then the particle cleaning process (step 240a) and the air jet process (step 250a) are continued.

The design of the above process flow is equivalent to completing a single polymer cleaning process, for example, into a polymer cleaning process of steps 220a and 220b. And after the first polymer cleaning process, for example, after completing step 220a, deionized water plus carbon dioxide is first applied. The charge process is removed to instantly remove the charge accumulated on the surface of the germanium wafer. Alternatively, deionized water plus carbon dioxide de-charge process may be performed after each polymer cleaning process. This allows for a more complete removal of the charge accumulated on the surface of the germanium wafer after the polymer cleaning process.

2B is a graph showing changes in charge accumulation amount on the surface of the germanium wafer corresponding to steps 220a to 234b of the wafer cleaning method flow of FIG. 2A. In Fig. 2B, the vertical axis represents the amount of charge accumulation, and the horizontal axis represents the time taken for each cleaning process. Further, the polymer cleaning (steps 220a, 220b) in Fig. 2B is based on the SOM cleaning data as an illustrative example. As can be seen in Figure 2B, each time the polymer cleaning process (steps 220a, 220b) and the high temperature deionized water process (steps 232a, 232b) are performed, then a deionized water plus carbon dioxide decharge process is performed (step 234a). , 234b), can effectively remove the charge accumulated on the surface of the germanium wafer. This effectively avoids the accumulation of charge on the surface of the wafer to saturation (illustrated in Figure 2B as a horizontal line) and the volcanic effect of the charge.

Referring to FIG. 3A, in another embodiment of the present invention, a germanium wafer is first provided (step 210), and the polymer cleaning process (step 220a) and the high temperature deionized water cleaning process (step 232a) are sequentially performed. Deionized water is added to the carbon dioxide de-charge process (step 234a), and then after the particle cleaning process (step 240a) and the air jet process (step 250a) are sequentially performed, the above-mentioned particle cleaning process (step 240b) and air injection may be repeated. Process (step 250b) at least one cycle and adjust the number of times as required by the process. Finally, a deionized water plus carbon dioxide decharge process is performed (step 260) to remove the charge remaining on the surface of the germanium wafer. In FIG. 3A, the cleaning step before the particle cleaning process (step 240a) is illustrated by the flow of FIG. 1A, but the flow of FIG. 2A may also be applied, and the invention is not limited thereto.

The above process flow is designed to solve the problem that the cerium oxide formed by the single particle cleaning process is not deep enough to completely etch the particles on the surface of the ruthenium wafer; When a certain depth of cerium oxide is formed, the processing time required for the single-particle cleaning process is too long, resulting in a problem of low process efficiency. Therefore, the present invention divides (or divides) the time required for a single particle cleaning process into two or more than two, for example, The microparticle cleaning process of step 240a and step 240b. That is, the present invention utilizes a method of dividing the surface of the yttrium oxide wafer to achieve complete removal of the particles attached to the surface of the ruthenium wafer, and to improve the cleaning efficiency. After each completion of the SC1 cleaning, it is combined with air jet treatment. After two or more cycles of SC1 cleaning and air jet treatment, the deionized water plus carbon dioxide decharge process is finally performed (step 260), and the entire cleaning process is completed.

Please refer to Figure 3B. FIG. 3B is a graph showing changes in particle removal efficiency corresponding to steps 240a to 250b of the wafer cleaning method flow of FIG. 3A. The above-mentioned particle cleaning process (steps 240a, 240b) is an example of the data of the SC1 cleaning process. In FIG. 3B, the vertical axis is the removal rate of the microparticles, or the surface etching rate; and the horizontal axis is the time taken for each cleaning process. As can be seen in Figure 3B, the single particle cleaning process is performed in divided portions and, after each completion of the SC1 cleaning, is combined with an air jet process (steps 250a, 250b). This can effectively improve the particle removal rate of the wafer surface.

Figure 3C is a graph showing the relationship between etch rate and time for a single particle cleaning process on the surface of a germanium wafer. The particle cleaning process utilizes the SC1 cleaning process to generate the data in the graph. The vertical axis is the removal rate of the microparticles, or the etching rate of the wafer surface, in angstroms per minute (Angstrom/minute); the horizontal axis is the cleaning time in seconds. As can be seen from Figure 3C, when the cleaning time is greater than 30 seconds, the microetch rate begins to decrease. Therefore, for example, in the present invention, for example, the first SC1 cleaning can be designed to be the longest time before the etching rate is lowered, for example, 30 seconds, and then the air ejection processing is continued. The subsequent SC1 cleaning time is adjusted according to the process requirements and the micro-etching rate in FIG. 3C. This oxidation and micro-etching of the wafer surface in this way to achieve the desired depth of the removed layer can improve the efficiency and completeness of the particle cleaning process.

It is worth mentioning that the various cleaning steps provided by the wafer cleaning method of the present invention (polymer cleaning, high temperature deionized water cleaning, deionized water plus carbon dioxide decharge processing, particle cleaning process, air jet treatment) may be Completed in the same chamber. Or, in the process method of FIG. 1A and FIG. 2A, the polymer cleaning process, deionized water plus carbon dioxide The charge process and the particle cleaning process can be performed, for example, in the same chamber. Alternatively, in the process of FIG. 3A, the polymer cleaning process, the first particle cleaning process, the air jet process, and the second particle cleaning process can be performed, for example, in the same chamber. Furthermore, the wafer cleaning method of the present invention can be applied, for example, to a cleaning step before or after forming a lightly doped drain (LDD) structure.

In summary, the wafer cleaning method of the present invention is mainly after the polymer cleaning process, that is, the deionized water plus carbon dioxide de-charge process is continued. Alternatively, the time of the single polymer cleaning process can be disassembled and divided, and after the first polymer cleaning process, the deionized water plus carbon dioxide de-charge process is continued, and then the polymer cleaning process is repeated. In this way, the charge accumulated on the surface of the germanium wafer can be removed immediately, so as to avoid the accumulation of charge on the surface of the germanium wafer by the subsequent cleaning process, thereby causing the volcanic effect of the charge. In addition, the wafer cleaning method of the present invention also performs a single particle cleaning process in stages, and inserts an air jet process between the two particle cleaning processes. Such a process design can improve the cleaning efficiency of the particle cleaning process to achieve complete removal of the particles attached to the surface of the germanium wafer.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

210‧‧‧ Providing silicon wafers

220a‧‧‧ Polymer cleaning process

232a‧‧‧High temperature deionized water cleaning process

234a‧‧‧Deionized water plus carbon dioxide decharge process

240a‧‧‧Particulate cleaning process

250a‧‧‧Air jet treatment

Claims (22)

A method for cleaning a wafer, comprising: providing a wafer; performing a polymer cleaning process on a surface of the germanium wafer; performing a deionized water addition on the surface of the germanium wafer after the polymer cleaning process a carbon dioxide de-charge process; and a particle cleaning process and an air jet process on the surface of the germanium wafer after the deionized water plus carbon dioxide de-charge process. The wafer cleaning method according to claim 1, wherein the polymer cleaning process is a sulfuric acid/ozone mixture (SOM) cleaning process. The wafer cleaning method of claim 1, wherein the high temperature deionized water cleaning process is performed after performing the polymer cleaning process and before performing the deionized water plus carbon dioxide decharge process. The wafer cleaning method according to claim 3, wherein the high temperature deionized water cleaning temperature is 70 degrees C. The wafer cleaning method of claim 1, wherein the polymer cleaning process is performed again after performing the deionized water plus carbon dioxide decharge process and before performing the particle cleaning process. The wafer cleaning method according to claim 5, wherein after the polymer cleaning process is performed again and before the particle cleaning process is performed, a high temperature is sequentially included. The deionized water cleaning process and the deionized water plus carbon dioxide decharge process are performed again. The wafer cleaning method according to claim 6, wherein the high temperature deionized water cleaning process has a temperature of 70 degrees C. The wafer cleaning method according to claim 1, wherein the particle cleaning process is a standardized first cleaning (standard clean 1, SC1), and the standardized first cleaning comprises using ammonium hydroxide (NH ₄ OH). ), hydrogen peroxide (H ₂ O ₂ ) and deionized water for the cleaning process. The wafer cleaning method according to claim 1, wherein the performing the air jet processing further comprises performing the particle cleaning process and the air jet processing in sequence. The wafer cleaning method according to claim 9, wherein after the particle cleaning process and the air jet processing are performed in sequence, the deionized water plus carbon dioxide de-charge process is further performed. The wafer cleaning method of claim 1, wherein a surface of the germanium wafer has a gate structure formed thereon. The wafer cleaning method of claim 1, wherein the polymer cleaning process, the deionized water plus carbon dioxide decharge process, and the particle cleaning process are performed in the same chamber. A method for cleaning a wafer, comprising: providing a wafer; performing a polymer cleaning process on a surface of the germanium wafer; Performing a first particle cleaning process on the surface of the germanium wafer after the polymer cleaning process; performing an air jet process on the surface of the germanium wafer after the first particle cleaning process; and after the air jet processing A second particle cleaning process is performed on the surface of the germanium wafer. The wafer cleaning method of claim 13, wherein the first particle cleaning process and the second particle cleaning process are a standard first cleaning (standard clean 1, SC1), the standardized first cleaning This includes the use of ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and deionized water for the cleaning process. The wafer cleaning method according to claim 13, wherein a surface of the germanium wafer has a gate structure formed thereon. The wafer cleaning method of claim 13, wherein the performing the second particle cleaning process further comprises performing the air jet processing again. The wafer cleaning method of claim 16, wherein after the air jet treatment is performed again, performing a deionized water plus carbon dioxide decharge process. The wafer cleaning method according to claim 13, wherein the polymer cleaning process is a sulfuric acid/ozone mixture (SOM) cleaning process. The wafer cleaning method according to claim 13 , wherein after the polymer cleaning process and before the first particle cleaning process, a high-temperature deionized water cleaning process is sequentially performed. Ionized water plus carbon dioxide to charge the process. The wafer cleaning method according to claim 19, wherein the high temperature deionized water cleaning process has a temperature of 70 degrees C. The wafer cleaning method according to claim 19, wherein the performing the polymer cleaning process is performed sequentially after performing the deionized water plus carbon dioxide decharge process and before performing the first particle cleaning process. The high temperature deionized water cleaning process and the deionized water plus carbon dioxide decharge process. The wafer cleaning method of claim 13, wherein the polymer cleaning process, the first particle cleaning process, the air jetting process, and the second particle cleaning process are performed in the same chamber.