TWI426125B - Cleaning solution and application thereof - Google Patents

Description

Cleaning fluid and its application

This invention relates to a cleaning fluid and its use in wafer cleaning after chemical mechanical polishing.

In semiconductor processes, chemical mechanical polishing (CMP) is often used to planarize the surface of the wafer. After the slurry is polished and the wafer is polished, a number of residues are generated on the surface of the wafer, such as abrasive particles, chemical components in the abrasive slurry, and reaction products of the polishing slurry. These residual contaminants must be cleaned before entering the next semiconductor process, otherwise the subsequent process and wafer reliability will be severely affected. Therefore, usually after the wafer is CMP-polished, a cleaning solution is used to clean the surface of the wafer.

The CMP post-cleaning solution conventionally used is mostly an alkaline solution based on ammonia. For example, one of the solutions disclosed in the patent document TW494020B is applied to a cleaning solution after polycrystalline CMP polishing, that is, a surfactant and a chelating agent are added to a diluted alkaline aqueous ammonia solution. Thereby, the cleaning liquid is used to remove abrasive particles and metal ions remaining on the surface of the polycrystalline silicon. However, the smell of organic ammonia such as ammonia water used in the cleaning liquid is unpleasant, and it is likely to cause environmental pollution.

Therefore, the present invention proposes a cleaning liquid applied to wafer cleaning after chemical mechanical polishing to solve the above problems.

The object of the present invention is to solve the above problems and to provide a cleaning liquid.

The cleaning solution of the present invention contains at least one oxidizing agent, at least one hydrazine compound and water.

In the present invention, the quinone compound has the effect of removing residual abrasive particles. Among all terpenoids, preferred choices are: barium, strontium carbonate, and Barium acid, dihydrogen phosphate, barium hydrochloride, barium nitrate, barium sulfate, aminoguanidine, aminoguanidine hydrogencarbonate, aminoguanidinesulfonate, aminoguanidine hydrochloride or aminoguanidine nitrate. The preferred content of the terpenoid is 0.01-10% by mass.

In the present invention, the preferred choice of oxidizing agent is hydrogen peroxide, urea peroxide, peroxyformic acid or peracetic acid. The preferred content of the oxidizing agent is 0.1 to 10% by mass.

In the present invention, the pH of the cleaning solution may range from pH 7 to pH 12, and preferably ranges from pH 8 to pH 11. In practical applications, a conventional pH adjusting agent such as a mineral acid may be used to adjust the cleaning liquid to a desired pH value.

According to the cleaning liquid of the present invention, water and an anthraquinone compound are added at the time of preparation, and the mixture is uniformly stirred, and a conventional pH adjusting agent such as a mineral acid is used to adjust the cleaning liquid to a desired pH value as needed. The cleaning solution can be mixed evenly by adding an oxidizing agent before use.

Another object of the present invention is to apply the cleaning solution to a wafer cleaning process after chemical mechanical polishing. The type of the wafer may be a non-metal wafer such as polycrystalline germanium, single crystal germanium or germanium dioxide.

The cleaning solution proposed by the present invention can remove abrasive particles and chemicals remaining on the surface of the wafer after chemical mechanical polishing. Moreover, since the cleaning liquid has a low metal ion content and is odorless, contamination by metal ions can be reduced.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

The invention is further illustrated by the following examples, but is not intended to limit the invention to the scope of the embodiments described below.

Examples 1 to 13

Table 1 shows the formulations used in the cleaning solutions of Examples 1 to 13, with water being the balance. According to the ingredients and their contents in the table, first add water and terpenoids, and stir them evenly. Then adjust the pH to the user's pH with sulfuric acid. Just add the oxidizing agent to the cleaning solution before use. can.

Effect Example 1

The surface of the polycrystalline germanium wafer after chemical mechanical polishing was brushed using deionized water and the cleaning solution of Example 3, respectively. In the present embodiment, the roller brush used was a polyvinyl alcohol (PVA) roller brush, the brushing time was 1 min, the roller brush rotation speed was 100 rpm, and the cleaning liquid flow rate was 500 ml/min. The surface of the wafer after washing with deionized water, as shown in Figures 1 and 2; the surface of the wafer after cleaning with a cleaning solution, as shown in Figure 3.

As shown in FIG. 1 to FIG. 3, the cleaning liquid according to the present invention has good cleaning performance for abrasive particles and chemicals remaining on the surface of the polycrystalline silicon wafer after polishing. force. Moreover, during the cleaning process, the cleaning liquid has a low metal ion content and is odorless, so that the contamination caused by the metal ions can be reduced.

Effect Example 2

The surface of the cerium oxide wafer after chemical mechanical polishing was brushed with deionized water and the cleaning liquid of Example 7, respectively. In this embodiment, the roller brush used was a polyvinyl alcohol (PVA) roller brush, brushed. The time was 1 min, the rolling brush speed was 100 rpm, and the cleaning liquid flow rate was 500 ml/min. The surface of the wafer after washing with deionized water is shown in FIG. The surface of the wafer after cleaning with a cleaning solution is shown in FIG.

As shown in FIGS. 4 and 5, the cleaning liquid according to the present invention has a good cleaning ability for the abrasive particles and chemicals remaining on the surface of the ceria wafer after polishing. Moreover, in the cleaning process, the cleaning liquid according to the present invention has a low metal ion content and is odorless, so that contamination by metal ions can be reduced.

Effect Example 3

The surface of the wafer having the polycrystalline germanium/cerium oxide pattern was subjected to chemical mechanical polishing using deionized water and the cleaning liquid of Example 9, respectively. In the present embodiment, the roller brush used was polyvinyl alcohol (PVA). Rolling brush, brushing time 1 min, roller brush speed 100 rpm, cleaning fluid flow rate 500 ml / min. The surface of the wafer after washing with deionized water, as shown in Fig. 6, was cleaned with a cleaning liquid, as shown in Fig. 7.

As shown in Figures 6 and 7, the cleaning solution according to the present invention has a good cleaning ability for the abrasive particles and chemicals remaining on the polished surface of the polysilicon/cerium oxide wafer. Moreover, in the cleaning process, the cleaning liquid according to the present invention has a low metal ion content and is odorless, so that contamination by metal ions can be reduced.

The starting materials and reagents used in the present invention are all commercially available.

The features and spirit of the present invention are more clearly described in the above detailed description of the preferred embodiments, and the preferred embodiments disclosed herein The scope of the invention is limited. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed. Therefore, the scope of the patented scope of the invention should be construed as broadly construed in the

Figure 1 is an SEM image of the surface of a polycrystalline silicon wafer after cleaning with deionized water, where the white spots are abrasive particles remaining on the surface of the wafer.

Figure 2 is an SEM image of the surface of a polycrystalline silicon wafer after cleaning with deionized water, where the white stains are chemicals remaining on the surface of the wafer.

Figure 3 is an SEM image of the surface of a polycrystalline silicon wafer after cleaning using the cleaning solution of Example 3.

Figure 4 is an SEM image of the surface of a ceria wafer after cleaning with deionized water, where the white spots are wafer surface residues.

Figure 5 is an SEM image of the surface of a ceria wafer after cleaning using the cleaning solution of Example 7.

Figure 6 is an SEM image of the surface of a patterned polysilicon/cerium oxide wafer after cleaning with deionized water, where the spots are wafer surface residues.

Figure 7 is an SEM image of the surface of a patterned polycrystalline germanium/cerium oxide wafer after cleaning using the cleaning solution of Example 9.

Claims (3)

A cleaning solution comprising at least one oxidizing agent, at least one hydrazine compound and water, wherein the hydrazine compound is cerium, cerium carbonate, cerium acetate, cerium hydrogen phosphate, cerium hydrochloride, cerium nitrate, cerium sulfate, amino guanidine, aminoguanidine a hydrogencarbonate, an aminoguanidine sulfonate, an aminoguanidine hydrochloride or an aminoguanidine nitrate, the oxidant being hydrogen peroxide, urea peroxide, peroxyformic acid or peracetic acid, the pH of the cleaning solution being 7-12 Wherein the content of the anthraquinone compound is 0.01-10% by mass, wherein the content of the oxidizing agent is 0.1-10% by mass. The cleaning solution of claim 1, wherein the cleaning solution has a pH of 8-11. For example, the cleaning liquid described in claim 1 is applied to wafer cleaning after chemical mechanical polishing.