KR20090075368A - Method for detecting defect of wafer - Google Patents

Abstract

A method for detecting defect of a wafer is provided to increase the accuracy of defect detection by removing a SC1 solution and a particle effectively through a cleaning process. A defect of a wafer is expanded by processing the wafer with a SC1 solution(S12), and the processed wafer is cleaned with a first cleaning solution(S13), and then is cleaned with a second cleaning solution(S14). A particle map is formed by sensing the defect of the cleaned wafer, and a first cleaning solution is the congestion aqueous solution of the hydrogen peroxide(H2O2) and the ammonia(NH4OH) in which the alkalinity is lower than the SC1 solution.

Description

Wafer defect detection method {METHOD FOR DETECTING DEFECT OF WAFER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detection method of a wafer, and more particularly to a method of detecting crystal defects of a wafer using an SC1 cleaning method.

Today, silicon wafers, which are widely used as materials for manufacturing semiconductor devices, refer to monocrystalline silicon thin films made of polycrystalline silicon as a raw material.

As the degree of integration of semiconductor devices increases, the quality of the wafer, which is a wafer for manufacturing semiconductor devices, greatly affects the yield and reliability of semiconductor devices. The quality of the wafer depends on crystal growth and defects that occur during the process of manufacturing the wafer. The defects are largely divided into crystal defects occurring during the wafer manufacturing process and defects caused by external contaminants.

For example, defects of a three-dimensional structure formed by diffusion and merging of defects among the crystal defects are called crystal originated particles (COPs) or D-defects.

On the other hand, the defect caused by the external pollutant can be easily removed by an etching or cleaning process, the crystal defect is difficult to remove. In addition, the crystal defects cause defects in the subsequent manufacturing steps of the semiconductor elements, which in turn lower the yield and reliability of the semiconductor elements. Therefore, in order to prevent defects in the semiconductor device manufacturing process described above, it is important to accurately and quickly analyze crystal defects occurring on the wafer.

Detecting crystal defects in conventional wafers include copper decoration and standard cleaning 1 solution (SC1) cleaning.

In the copper decoration method or the direct surface oxide defect (DSOD) method, when a target wafer is immersed in an electrolyte solution in which copper ions are dissolved and a voltage is applied, copper ions are deposited at positions of crystal defects on the target wafer. It is a method which can visually confirm the morphology and distribution of the said crystal defect.

However, in the case of the copper decoration, since a thermal oxide film must be formed on the target wafer, there is a problem in that it takes a long time for defect detection. In addition, if the size of the deposited copper ions is not large enough to be visually observed, it is further troublesome to check the distribution and morphology of the defect using another defect detection equipment. In addition, when the thickness of the thermal oxide film formed on the target wafer is not uniform or the thickness is too thin or thick, copper ions may be deposited even at positions which are not actual defects, thereby reducing the accuracy and reliability of the detection result.

On the other hand, the SC1 cleaning method is a method of etching the crystal defects of the target wafer to enlarge and observe the size of the target wafer by treating the target wafer with the SC1 solution.

However, in the case of the SC1 cleaning method, when the target wafer is treated with the SC1 solution, it takes time and cost to enlarge the size of the crystal defect. In addition, after the SC1 treatment, observation is performed through an optical microscope. Since defects are detected locally on the target wafer, it is difficult to accurately determine the distribution and density of crystal defects. In addition, it takes a long time to detect a crystal defect, there is a problem that the accuracy and reliability of the defect detection result is lowered because the detection result is dependent on the operator.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and to provide a defect detection method of a wafer for improving defect detection accuracy by using the SC1 cleaning method.

In addition, the present invention is to provide a defect detection method of a wafer that can reduce the time required to detect a defect.

According to embodiments of the present invention for achieving the above object of the present invention, the defect detection method of the wafer using the SC1 cleaning method, by treating the wafer with the SC1 solution to enlarge the defects of the wafer, it is about than the SC1 solution The wafer is cleaned using an alkaline first cleaning solution and an acidic second cleaning solution to form a particle map. Therefore, by effectively removing the SC1 solution and particles on the wafer by the cleaning process of the first cleaning solution and the second cleaning solution, noise components due to the SC1 solution and the particles are removed when the particle map is measured, and defect detection is performed. Improves its accuracy.

In an embodiment, the first cleaning solution is a predetermined alkaline solution having a lower acidity than the SC1 solution, and may be a mixed aqueous solution of ammonia (NH ₄ OH) and hydrogen peroxide (H ₂ O ₂ ). For example, the first cleaning solution is an aqueous solution in which ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and pure water (H ₂ O) are mixed at a weight ratio of 1: 3: 30.

In an embodiment, the second cleaning solution is an acid solution having a predetermined acidity, for example, diluted hydrochloric acid (HCl). The second cleaning solution is an aqueous solution of 1: 100 diluted hydrochloric acid (HCl) and pure water (H ₂ O).

In an embodiment, in order to improve the cleaning effect of the wafer, it is preferable to form the particle map after performing the first cleaning step and the second cleaning step at least once each.

In an embodiment, after performing the first cleaning step and the second cleaning step, a third cleaning step and a fourth cleaning step may be further performed to improve the cleaning effect of the wafer.

Here, in the first washing step, an alkaline third washing liquid having an acidity different from the first washing liquid is used. For example, the third washing liquid is ammonia (NH ₄ OH), and ammonia (NH ₄ OH) and hydrogen peroxide (H ₂ O ₂₎ and pure water (H ₂ O) as a mixed aqueous solution of hydrogen peroxide (H ₂ O ₂₎ the A solution mixed in a weight ratio of 1: 2: 80 can be used. In the fourth cleaning step, an acidic fourth cleaning liquid having an acidity different from that of the second cleaning liquid is used. For example, the fourth cleaning solution may be diluted hydrochloric acid (HCl), and an aqueous solution obtained by diluting hydrochloric acid (HCl) and pure water (H ₂ O) to 1: 200.

According to the present invention, first, the cleaning process effectively improves the accuracy of defect detection in the SC1 cleaning method.

Second, the SC1 cleaning method saves time and costs for defect detection.

In particular, when detecting crystal defects for a plurality of wafers, the time required for defect detection can be effectively reduced.

Third, crystal defects on the wafer can be detected simply and easily using the SC1 cleaning method.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Although the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, the present invention is not limited or restricted by the embodiments.

1 is a flow chart illustrating a defect detection method of a wafer according to an embodiment of the present invention. 2 and 3 are diagrams illustrating a particle map formed by the defect detection method of FIG. 1.

Hereinafter, a defect detection method of a wafer according to an embodiment of the present invention will be described in detail with reference to FIG. 1.

Referring to the drawings, an object wafer to be detected is provided.

For example, the target wafer may be a silicon wafer that becomes a semiconductor substrate. However, the present invention is not limited thereto, and the target wafer may be a glass substrate for a flat panel display device such as an LCD and a PDP. In addition, the target wafer is not limited in shape or size by the drawings, and may have substantially various shapes and sizes, such as circular and rectangular plates.

In the present embodiment, a silicon wafer for semiconductor substrate is described as an example as the target wafer.

In addition, defects to be detected in the present embodiment are defects formed in a wafer growth process, such as crystal originated particles (COPs) or D-defects.

The target wafer is treated with the SC1 solution (S11) to enlarge the defect of the target wafer (S12).

In the SC1 processing step (S11), the target wafer is immersed in the SC1 solution for a predetermined time to enlarge the crystal defect on the target wafer to a predetermined size. For example, in the SC1 treatment step S11, the target wafer is immersed in the SC1 solution at a temperature of 70 to 80 ° C. for 2 hours.

In addition, the SC1 processing step (S11) not only enlarges the size of a defect of the target wafer, but also has an effect of removing particles adhering to the surface of the target wafer.

Here, the SC1 solution (standard cleaning 1 solution) is a solution containing ammonia and hydrogen peroxide, for example, ammonia (NH ₄ OH): hydrogen peroxide (H ₂ O ₂ ): pure water (H ₂ O) 1: 1 It is an aqueous solution mixed with the weight ratio of: 5.

Next, a first cleaning process for removing the SC1 solution from the target wafer on which the SC1 processing step S11 is completed is performed (S13).

The first cleaning step S13 cleans the target wafer with an alkaline first cleaning liquid having a predetermined acidity. The first cleaning solution is a weaker alkaline solution than the SC1 solution. For example, the first cleaning solution is ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and pure water (H ₂ O) 1: 3: The aqueous solution mixed in the weight ratio of 30 can be used.

Next, when the first cleaning step S13 is completed, the target wafer is second cleaned with an acidic second cleaning liquid having a predetermined acidity (S14).

For example, the second cleaning solution uses an aqueous solution in which hydrochloric acid (HCl) and pure water (H ₂ O) are diluted in a weight ratio of 1: 100.

When the second cleaning process S14 is completed, a particle map is formed on the target wafer (S15).

The particle map shows locations of crystal defects detected on the target wafer on a map corresponding to the target wafer. That is, the number, area and distribution of crystal defects on the target wafer can be known using the particle map.

// For example, the particle map may be formed using scattered light scattered from the target wafer.

That is, since there is a difference in the surface roughness of the defective part and the defective part of the target wafer, the defect of the target wafer can be detected through the scattered light detected by the target wafer.

Meanwhile, in order to form the particle map through the scattered light detected by the target wafer, the scattered light detected by the target wafer is compared with a preset reference value, and when the reference value is satisfied, it is determined that the defect is caused by the defect. It is shown on a map corresponding to the wafer.

For example, localized light scatters (hereinafter referred to as LLS) or non cleanable light point defect (LPD-N) may be used as a reference value of the scattered light.

According to the present embodiment, the SC1 cleaned target wafer is completely or repeatedly washed the first cleaning process S13 and the second cleaning process S14, thereby completely removing the SC1 solution on the target wafer. It is possible to effectively remove particles on the target wafer surface. Therefore, the particles and the SC1 solution prevent the occurrence of noise during defect detection and improve the accuracy of defect detection.

Meanwhile, although the first cleaning process S13 and the second cleaning process S14 may be performed alone or repeatedly, an additional cleaning step of the target wafer may be further performed before forming the particle map. .

In detail, the target wafer on which the second cleaning process S13 is completed is third cleaned using a third cleaning liquid (S141).

The said 3rd washing | cleaning liquid uses the alkaline aqueous solution which has a different acidity than the said 1st washing liquid. Here, the third cleaning liquid is preferably a weak alkaline solution than the first cleaning liquid, for example, the third cleaning liquid is ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and pure water (H ₂ An aqueous solution in which O) is mixed in a weight ratio of 1: 2: 80 can be used.

Next, the target wafer on which the third cleaning process S141 is completed is fourth cleaned using a fourth cleaning liquid (S142).

The fourth cleaning liquid is an acidic aqueous solution, and an acidic solution having an acidity different from that of the second cleaning liquid is used. Here, the fourth cleaning liquid is preferably a weakly acidic solution than the second cleaning liquid, for example, the fourth cleaning liquid is diluted with a hydrochloric acid (HCl) and pure water (H ₂ O) in a weight ratio of 1: 200. An aqueous solution can be used.

Therefore, according to the present exemplary embodiment, the SC1 solution and the particles may be effectively removed from the target wafer by cleaning the target wafer using a weakly alkaline cleaning solution and an acidic cleaning solution rather than the SC1 solution. Therefore, noise components due to the SC1 solution and particles are removed to improve the accuracy of crystal defect detection.

2 and 3 are particle maps detected by a crystal defect method according to an embodiment of the present invention, FIG. 2 is a particle map detected by a conventional SC1 cleaning method, and FIG. 3 is detected by a defect detection method according to the present invention. Particle map.

Here, in order to verify the conventional SC1 cleaning method and the defect detection method of the present invention, the target wafer is formed of a particle map using a wafer in which defects are concentrated in a central portion and a wafer in which defects are distributed along an edge.

FIG. 2 is a particle map measured after washing a target wafer by using SC1 solution to enlarge crystal defects of the target wafer and then using pure water.

Referring to FIG. 2, it appears that defects exist in the entire surface of the target wafer in the existing particle map, and it is not known that the grains of the target wafer are distributed along the center or the edge through the existing particle map. The reason why the existing particle map is incorrectly formed is that the particles and the SC1 solution, etc., which have not been removed from the target wafer, adversely affect the detection of the defect. Therefore, it is difficult to accurately grasp the distribution of defects on the target wafer through the particle map formed by using a conventional defect detection method.

On the other hand, referring to Figure 3, it can be easily seen that the defects are distributed along the center and the edge in the particle map according to the present embodiment. Therefore, it can be seen that the accuracy of the defect detection method according to the present embodiment is excellent.

1 is a flowchart illustrating a defect detection method according to an embodiment of the present invention;

2 and 3 are diagrams illustrating a particle map detected according to the defect detection method of FIG. 1.

Claims (11)

Providing a wafer; Treating the wafer with SC1 solution to enlarge defects in the wafer; First cleaning the SC1-treated wafer using an alkaline first cleaning liquid; Performing a second cleaning of the wafer on which the first cleaning is completed using an acidic second cleaning liquid; And Forming a particle map detecting a defect in the wafer on which the second cleaning is completed; Defect detection method of the wafer comprising a. The method of claim 1, And the first cleaning solution is a mixed aqueous solution of ammonia (NH ₄ OH) and hydrogen peroxide (H ₂ O ₂ ) having a lower alkalinity than the SC1 solution. The method of claim 2, The first cleaning solution is a wafer defect detection method, characterized in that the aqueous solution of ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and pure water (H ₂ O) mixed in a weight ratio of 1: 3: 30. The method of claim 1, And the second cleaning liquid is diluted hydrochloric acid (HCl). The method of claim 4, wherein The second cleaning solution is a defect detection method of a wafer, characterized in that the aqueous solution diluted 1: 100 of hydrochloric acid (HCl) and pure water (H ₂ O). The method of claim 1, And repeating the first cleaning step and the second cleaning step a plurality of times before forming the particle map. The method of claim 1, Third cleaning the wafer on which the second cleaning is completed with an alkaline third cleaning liquid having an acidity different from that of the first cleaning liquid; And Fourth cleaning the wafer on which the third cleaning is completed with an acidic fourth cleaning liquid having an acidity different from the second cleaning liquid; The defect detection method of the wafer further comprises. The method of claim 7, wherein And the third cleaning liquid is a mixed aqueous solution of ammonia (NH ₄ OH) and hydrogen peroxide (H ₂ O ₂ ). The method of claim 8, The third cleaning solution is a defect detection method of a wafer, characterized in that the aqueous solution mixed with ammonia (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ) and pure water (H ₂ O) in a weight ratio of 1: 2: 80. The method of claim 5, And the fourth cleaning liquid is diluted hydrochloric acid (HCl). The method of claim 10, The fourth cleaning liquid is a defect detection method of a wafer, characterized in that the aqueous solution diluted 1: 200 of hydrochloric acid (HCl) and pure water (H ₂ O).

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