TWI899856B - Wafer cleaning liquid and wafer cleaning method - Google Patents

Abstract

The present invention provides a wafer cleaning liquid, which includes an alkanolamine compound and an alcohol ether compound. The alkanolamine compound includes ethanolamine, diethanolamine or a combination thereof, and the alcohol ether compound includes ethylene glycol tert-butyl ether, diethylene glycol monobutyl ether or a combination thereof; the weight ratio of the alkanolamine compound to the alcohol ether compound is 1:20 to 1:1.5. In addition, the present invention provides a wafer cleaning method, which includes: providing a wafer that has undergone a cutting process; providing the aforementioned wafer cleaning liquid and performing a cleaning process on the wafer that has undergone the cutting process with the wafer cleaning liquid to obtain a cleaned wafer; and performing a rinsing process on the cleaned wafer with water to obtain a cleaned wafer. The present invention can effectively remove residues still attached to the surface of the grain after the cutting process.

Description

Wafer cleaning liquid and wafer cleaning method

This invention relates to a wafer cleaning fluid, particularly a wafer cleaning fluid used in a post-wafer dicing cleaning process. This invention also relates to a wafer cleaning method using the aforementioned wafer cleaning fluid.

In conventional integrated circuit manufacturing processes, integrated circuits or bumps are typically formed on a silicon wafer, which is then placed on wafer dicing tape and cut into multiple dies. During the die saw process, chipping or cracking of the die edges is unavoidable, and residues (such as, but not limited to, residual adhesive), impurities, and debris, along with particles awaiting removal, remain attached to the die surfaces. Furthermore, copper oxide or copper-silicon compounds are easily formed on the exposed surfaces of the die. Failure to remove these particles or surface residues can impact subsequent manufacturing processes and may even cause circuit shorts during packaging, negatively impacting the performance, reliability, and/or yield of subsequent products.

To remove the debris, the industry often uses pure water spraying to clean the debris generated during the dicing process. However, due to the use of new materials in the process or the miniaturization of dicing lane sizes, even if the amount of pure water used for cleaning is increased, unsatisfactory cleaning results may still occur. Alternatively, the wafer dicing equipment may need to be repurchased to reduce or directly remove debris, resulting in increased costs for the overall processing process.

Given that the aforementioned wafer cleaning fluids and cleaning methods cannot meet the cleaning requirements of wafers undergoing the dicing process, the purpose of this invention is to provide a wafer cleaning fluid that can easily and quickly complete the cleaning process after dicing without requiring large amounts of clean water, thereby improving overall process efficiency and helping to maintain the quality of subsequent applications.

Another purpose of this invention is to provide a wafer cleaning fluid that does not require limiting the specifications of the cutting equipment or repurchasing complex and expensive cutting equipment, thereby reducing the cost of the overall processing process and thus having greater potential for commercial product development.

To achieve the aforementioned objectives, the present invention provides a wafer cleaning solution comprising an alkanolamine compound and an alcohol ether compound. The alkanolamine compound comprises ethanolamine, diethanolamine (DEA), or a combination thereof; the alcohol ether compound comprises ethylene glycol mono-tert-butyl ether (ETB), diethylene glycol monobutyl ether (DB), or a combination thereof. The weight ratio of the alkanolamine compound to the alcohol ether compound is 1:20 to 1:1.5.

This invention utilizes specific alkanolamine compounds and alcohol ether compounds simultaneously, with these components within a specific ratio. This not only effectively removes residues (such as adhesive residues), impurities, and silicon powder remaining on the surfaces of wafers after dicing, but also prevents the formation of copper oxide and/or copper-silicon compounds on the sides of the wafers, thus avoiding chemical reactions. Consequently, the resulting cleaned wafers have the advantage of improved yield in subsequent applications.

Preferably, the wafer cleaning solution may further comprise water. Preferably, the ratio of the total weight of the alkanolamine compound and the alcohol ether compound to the weight of the water is 1:7.5 to 1:9.5.

Preferably, the weight ratio of the alkanolamine compound to the alcohol ether compound is 1:5 to 1:2, but is not limited thereto. More preferably, the weight ratio of the alkanolamine compound to the alcohol ether compound is 1:4 to 1:2.5.

In some embodiments, the alkanolamine compound may be a combination of ethanolamine and diethanolamine, wherein the weight ratio of ethanolamine to diethanolamine is 2:1 to 5:1, but is not limited thereto. Preferably, in the aforementioned combination, the weight ratio of ethanolamine to diethanolamine is 2:1 to 4:1.

In some embodiments, the alcohol ether compound may be a combination of ethylene glycol tert-butyl ether and diethylene glycol monobutyl ether, wherein the weight ratio of ethylene glycol tert-butyl ether to diethylene glycol monobutyl ether is 1:1 to 1:4, but is not limited thereto. Preferably, in the aforementioned combination, the weight ratio of ethylene glycol tert-butyl ether to diethylene glycol monobutyl ether is 1:1 to 1:2.

In some embodiments, the wafer cleaning solution is composed of, but not limited to, ethanolamine, diethylene glycol monobutyl ether, and water. In other embodiments, the wafer cleaning solution is composed of, but not limited to, diethanolamine, diethylene glycol monobutyl ether, and water.

Preferably, the ethanolamine is 2-aminoethanol.

In response to the diverse and convenient subsequent applications of the wafer cleaning solution of this invention, the wafer cleaning solution may further include auxiliary additives, depending on different usage requirements, without affecting its primary effect. The auxiliary additives may be, but are not limited to, surfactants to reduce the surface tension of the wafer cleaning solution. Specifically, the surfactant may be, but is not limited to, sodium dodecyl sulfate (SDS), sodium laureth sulfate (SLES), or a combination thereof.

According to the present invention, the pH value of the wafer cleaning solution is 9 to 13, but is not limited thereto. Preferably, the pH value of the wafer cleaning solution is 10 to 12.5.

This invention also provides a wafer cleaning method, comprising steps (A) to (C). Step (A): providing a wafer that has undergone a dicing process, wherein the diced wafer comprises a plurality of dies; Step (B): providing the aforementioned wafer cleaning solution and performing a cleaning process on the diced wafer with the wafer cleaning solution to obtain a cleaned wafer; and Step (C): rinsing the cleaned wafer with water to obtain a cleaned wafer.

Preferably, the operating temperature of step (B) is 10°C to 75°C, but is not limited thereto. More preferably, the operating temperature of step (B) is 25°C to 35°C.

Preferably, in step (B), the cleaning process may be performed by spraying, immersion, ultrasonic vibration, or a combination thereof, but is not limited thereto. Specifically, a spray device may be used to spray the wafer cleaning liquid onto the diced wafer; alternatively, the diced wafer may be immersed in the wafer cleaning liquid; or alternatively, the diced wafer may be immersed in the wafer cleaning liquid while being subjected to ultrasonic vibration.

In some embodiments, when the surface of the diced wafer contains a polymer material, the cleaning process can be performed by immersing the diced wafer in the wafer cleaning solution for a duration of greater than 0.5 minutes to 30 minutes. Preferably, the duration of immersion is 0.8 minutes to 10 minutes, but is not limited thereto. Furthermore, the polymer material can be a molding compound, including, but not limited to, epoxy resin.

In other embodiments, when the surface of the wafer that has undergone the dicing process contains a polymer material, the cleaning process can be performed by spraying the wafer cleaning liquid onto the surface of the wafer that has undergone the dicing process, wherein the spraying time is greater than 1 minute to 30 minutes; preferably, the spraying time is 2 minutes to 15 minutes, but is not limited thereto.

In some embodiments, when the surface of the cut wafer contains silicon material, the cleaning process can be performed by immersing the cut wafer in the wafer cleaning solution, wherein the immersion time is greater than 0.5 minutes to 30 minutes; preferably, the immersion time is 0.8 minutes to 10 minutes, but is not limited thereto.

In other embodiments, when the surface of the cut wafer contains silicon material, the cleaning process may be performed by spraying the wafer cleaning liquid onto the surface of the cut wafer, wherein the spraying time is greater than 1 minute to 30 minutes; preferably, the spraying time is 2 minutes to 15 minutes, but is not limited thereto.

In some embodiments, the cleaning process can be performed by first immersing the cut wafer in the wafer cleaning solution for 0.5 to 10 minutes and then removing the wafer from the solution. Then, the wafer cleaning solution is continuously sprayed onto the surface of the cut wafer for 1 to 10 minutes to obtain the cleaned wafer.

Preferably, in step (C), the rinsing process may be performed by spraying, but is not limited thereto.

Preferably, step (C) may include: step (C1) and step (C2). Step (C1): rinsing the cleaned wafer with water to obtain a wet-cleaned wafer; and step (C2): drying the wet-cleaned wafer to obtain the cleaned wafer.

Preferably, the operating temperature of step (C1) can be 10°C to 75°C, but not limited thereto. More preferably, the operating temperature of step (C1) can be 25°C to 40°C. Preferably, the duration of step (C1) is 1 minute to 10 minutes, but not limited thereto.

Preferably, in the step (C2), the drying step may include using nitrogen or compressed clean dry air (CDA) to remove the liquid on the surface of the wet-cleaned wafer; wherein the operation time of the step (C2) may be 1 minute to 5 minutes.

In some embodiments, the step (B) and the step (C1) of the wafer cleaning method may be alternately cycled at least once. For example, the wafer cleaning method sequentially performs the step (B), the step (C1), the step (B), and the step (C1), but is not limited thereto.

In some embodiments, the wafer cleaning liquid is provided to the surface of the wafer that has undergone the cutting process in a vertical manner (i.e., perpendicular to the surface of the wafer that has undergone the cutting process, with an angle of 90°); in other embodiments, the wafer cleaning liquid is provided to the surface of the wafer that has undergone the cutting process in an oblique manner (i.e., not perpendicular to the surface of the wafer that has undergone the cutting process, with an angle greater than 0° and less than 90°, for example, 30° to 50°, but not limited to this).

In this manual, ranges expressed as "a decimal value to a large number" unless otherwise specified indicate that the range is greater than or equal to the decimal value and less than or equal to the large number. For example, if the operating temperature can be 10°C to 75°C, this means the operating temperature range is "greater than or equal to 10°C and less than or equal to 75°C."

The following will illustrate the specific implementation methods of the wafer cleaning solution of this invention through several embodiments and comparative examples. Those skilled in the art can easily understand the advantages and effects that can be achieved by this invention through the contents of this manual, and make various modifications and changes without departing from the spirit of this invention to implement or apply the contents of this invention.

Embodiment 1 、 2 and comparative example 1 : Wafer cleaning fluid

According to the ratios shown in Table 1 (in wt%), wafer cleaning solutions of Examples 1 and 2 and Comparative Example 1 were prepared, respectively. The main differences between them lie in the composition or content thereof.

Table 1 Compositions and contents of the wafer cleaning solutions of Examples 1, 2, and Comparative Example 1 (unit: wt%) Ingredients Example 1 Example 2 Comparative example 1 Ethanolamine 3 3 -- Diethanolamine 1 0 -- Total amount of alkanolamine compounds 4 3 -- Diethylene glycol monobutyl ether 7 7 -- Ethylene glycol tert-butyl ether 5 0 -- Total amount of alcohol ether compounds 12 7 -- water 84 90 100 pH 12 11 7

Embodiment 3 to 6 and comparative example 2 : Wafer cleaning method

Referring to the flow chart of the wafer cleaning method shown in FIG1 , Examples 3 to 6 and Comparative Example 2 use the wafer cleaning solution in Table 1 to perform a cleaning process on the sample of the wafer that has undergone the dicing process. The wafer cleaning solutions used in Examples 3 to 6 and Comparative Example 2 are shown in Table 2.

First, in step (A), a wafer sample is provided after a dicing process. The samples used in Examples 3 and 4 have a surface containing a polymer material (molding material); and the samples used in Examples 5 and 6 have a surface containing a silicon material.

Next, in step (B), a sample of the diced wafers was cleaned with the aforementioned wafer cleaning solution to obtain a cleaned wafer. The operating temperature in step (B) was 25°C, and each sample was placed in the wafer cleaning solution by spraying or immersion. The duration of the treatment for each embodiment and comparative example is shown in Table 2.

In step (C1), the cleaned wafer is rinsed with water to obtain a wet-cleaned wafer. The operating temperature in step (C1) is 25°C, and each sample is rinsed using a spraying method for 2 minutes. Subsequently, in step (C2), the wet-cleaned wafer is dried to obtain a sample of the cleaned wafer. The drying step is performed at 25°C using nitrogen purge for 2 minutes to remove liquid from the surface of the wet-cleaned wafer.

analyze 1 : Reliability test

Each set of cleaned wafer samples obtained in Examples 3 to 6 and Comparative Example 2 was further placed in a high temperature (85°C) and high humidity (85±5%) environment for 5 days. The surfaces of each set of samples were then examined using a scanning electron microscope (SEM). If no copper-silicon compounds were observed on the sample surface, the sample was evaluated as "cleaning effective." Conversely, if copper-silicon compounds were observed on the sample surface, the sample was evaluated as "cleaning ineffective." The analysis results for each set of samples are recorded in Table 2.

Table 2 Wafer cleaning solution composition, cleaning target, cleaning process method and duration, and reliability test results used in the wafer cleaning methods of Examples 3 to 6 and Comparative Example 2 Group Example 3 Example 4 Example 5 Example 6 Comparative example 2 Wafer cleaning fluid set Example 1 Example 2 Comparative example 1 Cleaning objects Surface contains polymer materials Surface contains silicon material Surface contains polymer materials How the cleaning process is carried out soak Spray soak Spray soak Duration 1 minute 3 minutes 1 minute 3 minutes 5 minutes Analysis results Cleaning is effective Cleaning is effective Cleaning is effective Cleaning is effective Cleaning is ineffective

Figure 2 shows an SEM image of a wafer sample cleaned using the cleaning method of Example 3. Figure 3 shows an SEM image of a wafer sample cleaned using the cleaning method of Comparative Example 2, taken under the same conditions. Figures 2 and 3 are SEM images taken at an accelerating voltage of 5 kilovolts (kV) and a magnification of 50.

Comparing Figures 2 and 3, it can be seen that the cleaned wafer surface still has a large amount of deposits in the specially framed area in Figure 3. In contrast, the similar area in Figure 2 is much smoother and cleaner. This demonstrates that the wafer cleaning fluid of this invention can indeed remove cutting residues and inhibit the formation of copper oxide and/or copper-silicon compounds on the side surfaces of the die.

In summary, the wafer cleaning fluid and wafer cleaning method using the same of the present invention can indeed complete the cleaning process simply and quickly without the need for large amounts of clean water, thus being cost-effective. Furthermore, wafers treated with the wafer cleaning fluid of the present invention can prevent the formation of copper oxide and/or copper-silicon compounds on the sides of the wafers contained therein, thereby avoiding chemical reactions and thus helping to maintain the quality of subsequent wafer applications. As a result, the resulting cleaned wafers can have the advantage of improved yield in subsequent applications.

The above embodiments are provided for the purpose of illustration only and are not intended to limit the scope of the patent application for this invention. Any other changes, modifications, and other alterations that do not deviate from the disclosed content of this invention should be included in the patent scope covered by this invention.

without

Figure 1 is a schematic diagram of the wafer cleaning method of this invention. Figure 2 is a SEM photograph of the cleaned wafer obtained in Example 3. Figure 3 is a SEM photograph of the cleaned wafer obtained in Comparative Example 2.

without

Claims (8)

A wafer cleaning solution comprises: Water; An alkanolamine compound comprising ethanolamine, diethanolamine, or a combination thereof; and An alcohol ether compound comprising ethylene glycol tert-butyl ether, diethylene glycol monobutyl ether, or a combination thereof; The ratio of the total weight of the alkanolamine compound and the alcohol ether compound to the weight of the water is 1:7.5 to 1:9.5; The weight ratio of the alkanolamine compound to the alcohol ether compound is 1:20 to 1:1.5. The wafer cleaning solution as described in claim 1, wherein the alkanolamine compound is a combination of ethanolamine and diethanolamine; wherein the weight ratio of ethanolamine to diethanolamine is 2:1 to 5:1. The wafer cleaning solution as described in claim 1 or 2, wherein the weight ratio of the alkanolamine compound to the alcohol ether compound is 1:5 to 1:2. A wafer cleaning method comprises: Step (A): providing a wafer that has undergone a dicing process, wherein the diced wafer comprises a plurality of dies; Step (B): providing a wafer cleaning solution as described in any one of claims 1 to 3, and performing a cleaning process on the diced wafer using the wafer cleaning solution to obtain a cleaned wafer; and Step (C): rinsing the cleaned wafer with water to obtain a cleaned wafer. The wafer cleaning method as described in claim 4, wherein the operating temperature of step (B) is 10°C to 75°C. The wafer cleaning method of claim 4, wherein step (C) comprises: Step (C1): rinsing the cleaned wafer with water to obtain a wet-cleaned wafer; and Step (C2): drying the wet-cleaned wafer to obtain the cleaned wafer. A wafer cleaning method as described in any one of claims 4 to 6, wherein, in the step (B), the cleaning process is performed by spraying, immersion, ultrasonic vibration or a combination thereof; and in the step (C), the rinsing process is performed by spraying. A wafer cleaning method as described in any one of claims 4 to 6, wherein the surface of the wafer that has undergone the cutting process contains a polymer material or a silicon material; and the cleaning process is carried out by immersing the wafer that has undergone the cutting process in the wafer cleaning solution, wherein the immersion time is greater than 0.5 minutes to 30 minutes.