KR20070044966A - Method of cleaning a substrate in a single wafer type - Google Patents

Abstract

The present invention relates to a method for cleaning a semiconductor substrate, and more particularly, to a single wafer cleaning method.

In a single wafer cleaning method according to an embodiment of the present invention, a first step of spraying a first cleaning liquid on a surface of a substrate to remove organic contaminants and a natural oxide film, and spraying a second cleaning liquid on the surface of the substrate A second step of removing the remaining first cleaning liquid and particles, and a third step of drying the substrate. At this time, according to one embodiment of the present invention, the second cleaning liquid is hydrogen water, the hydrogen water is characterized in that the concentration range of hydrogen is 1.4ppm to 1.8ppm. In addition, the hydrogen water has an acidity (pH) of 10 or more.

The single wafer cleaning method according to the present invention has the effect of increasing the throughput per unit time by reducing the number of steps in the unit process in the cleaning process. In addition, by effectively applying the appropriate mixing and spraying order of the respective cleaning liquids used in the cleaning process to increase the cleaning efficiency.

Single wafer cleaning, single wafer processing, substrate cleaning apparatus, substrate cleaning method.

Description

Single wafer cleaning method {METHOD OF CLEANING A SUBSTRATE IN A SINGLE WAFER TYPE}

1 is a flowchart illustrating a method of cleaning a sheet type substrate according to an exemplary embodiment of the present invention.

2 is a flowchart illustrating a method of cleaning a sheet type substrate according to another exemplary embodiment of the present invention.

3A to 3E are flowcharts illustrating a specific embodiment of the single wafer cleaning method shown in FIG. 1 or FIG. 2.

The present invention relates to a method for cleaning a semiconductor substrate, and more particularly, to a single wafer cleaning method.

In general, semiconductor manufacturing apparatus are manufactured by repeated performance of unit processes such as deposition, photolithography, etching, chemical mechanical polishing, cleaning, drying, and the like. Among these unit processes, the cleaning process is a process of removing foreign substances or unnecessary films adhering to the surface of the semiconductor substrate during each unit process. In recent years, the pattern formed on the semiconductor substrate is miniaturized, and the aspect ratio of the pattern is reduced. As it grows, its importance is increasing.

The apparatus for performing the cleaning process is classified into a batch type cleaning apparatus for simultaneously cleaning a plurality of semiconductor substrates and a sheet type cleaning apparatus for cleaning the semiconductor substrates in sheets. The batch cleaning apparatus cleans a plurality of semiconductor substrates at once by immersing the plurality of semiconductor substrates in a cleaning tank containing a cleaning liquid for cleaning the semiconductor substrate. In this case, ultrasonic vibration may be applied to the cleaning liquid contained in the cleaning tank to improve the cleaning efficiency. The single wafer cleaning apparatus includes a chuck for supporting the semiconductor substrate and nozzles for supplying the cleaning liquid to the front or rear surface of the semiconductor substrate. The cleaning liquid supplied to the semiconductor substrate may be supplied in a state where ultrasonic vibration is applied, or ultrasonic vibration may be applied in a state where the cleaning liquid is supplied on the semiconductor substrate.

As an example of a single wafer type cleaning apparatus for cleaning a semiconductor substrate by applying ultrasonic vibration to a cleaning liquid, US Pat. No. 6.039.059 (issued to Bran) uses a megasonic energy to vibrate a cleaning liquid supplied to a semiconductor substrate to An apparatus for cleaning a substrate is disclosed. The cleaning device has a quartz prolonged portion extending for applying megasonic energy to the cleaning liquid. In addition, US 2001-32657 (Itzkowitz, Herman) discloses a megasonic processing apparatus having a megasonic transducer for applying mechanical vibration to a cleaning liquid or an etching liquid provided on a semiconductor substrate.

This single wafer cleaning apparatus uses less cleaning chemicals compared to the conventional batch cleaning method, enables uniform cleaning by single wafer processing, and the cleaning efficiency is much higher than that of the batch cleaning method. It also enables clustering along with other semiconductor process equipment such as etching, deposition, etc., and also significantly reduces equipment size compared to the batch method, resulting in smaller footprint and cleaning cycle times. The cycle time can be significantly reduced.

In particular, the introduction of large-diameter wafers such as 300 mm wafers and the removal of fine particles due to the fine patterns have increased in importance, and thus, the cleaning method of the semiconductor substrate is expected to be used in the future.

However, the sheet cleaning apparatus has a disadvantage in that the throughput per unit time is smaller than that of the batch cleaning apparatus for simultaneously cleaning a plurality of wafers. Therefore, the sheet cleaning apparatus is required.

An object of the present invention for solving the above problems is to provide a single sheet cleaning method that can increase the throughput per unit time.

Another object of the present invention to provide a single-leaf cleaning method that can increase the cleaning efficiency.

According to an aspect of the present invention, there is provided a method of cleaning a sheet type substrate, in which a first cleaning solution is sprayed onto a surface of a substrate to remove organic contaminants and natural oxide films, and a second cleaning solution is applied to the surface of the substrate. And a second step of removing the first cleaning liquid and particles remaining on the surface of the substrate by spraying, and a third step of drying the substrate.

According to one embodiment of the invention, the second cleaning liquid is hydrogen water. As an example, the hydrogen water has a concentration range of 1.4 ppm to 1.8 ppm of hydrogen, and an acidity (pH) of 10 or more. In addition, the cleaning efficiency may be increased by providing ultrasonic waves having a frequency of 1.5 MHz or more in the hydrogen water.

According to another embodiment of the present invention, the sheet-type substrate cleaning method includes a first step of removing a contaminant and an oxide film by spraying a first cleaning liquid on a substrate surface, and spraying a third cleaning liquid on the surface of a substrate to spray contaminants and oxide films. A second step of removing, a third step of spraying a second cleaning solution on the surface of the substrate, a third step of rinsing the first cleaning solution and particles remaining on the surface of the substrate, and a third step of drying the substrate.

According to another embodiment of the present invention, the first cleaning liquid includes ozone water, the second cleaning liquid is hydrogen water, and the third cleaning liquid includes hydrofluoric acid and ultrapure water.

According to another embodiment of the present invention, the first cleaning liquid comprises ozone water, the second cleaning liquid is hydrogen water, and the third cleaning liquid comprises hydrogen water.

According to another embodiment of the present invention, the first cleaning liquid includes ozone water, the second cleaning liquid is hydrogen water, and the third cleaning liquid contains hydrogen, hydrofluoric acid, and ultrapure water.

According to another embodiment of the present invention, the first cleaning liquid includes ozone, hydrofluoric acid, and ultrapure water, the second cleaning liquid is hydrogen water, and the third cleaning liquid includes ammonia, hydrogen peroxide, and ultrapure water.

According to another embodiment of the present invention, the first cleaning liquid includes ozone, hydrofluoric acid, and ultrapure water, the three second cleaning liquids are hydrogen water, and the third cleaning liquid includes ammonia, hydrogen peroxide, hydrofluoric acid, and ultrapure water. .

According to another embodiment of the present invention, the first cleaning liquid includes ozone, hydrofluoric acid, and ultrapure water, the second cleaning liquid is hydrogen water, and the third cleaning liquid includes ozone water.

Hereinafter, the sheet type cleaning method according to the present invention will be described in detail with reference to FIGS. 1 and 2.

(Substrate cleaning method 1)

1 is a flowchart illustrating a method of cleaning a sheet type substrate according to an exemplary embodiment of the present invention. Referring to FIG. 1, in the method of cleaning a sheet type substrate according to an exemplary embodiment of the present disclosure, cleaning the substrate with the first cleaning solution (S10), cleaning the substrate with the second cleaning solution (S20), and rinsing the substrate It includes a step (S30).

When the substrate cleaning process is started, the substrate, which has been subjected to a predetermined semiconductor process, for example, a photoresist strip process for removing a photoresist liquid on the substrate from the surface of the substrate, is cleaned in a chamber (not shown) to clean contact holes formed in the substrate. Is mounted on the chuck (not shown) provided therein. The chuck is rotated after seating the substrate on the top surface.

When the substrate is rotated, the first cleaning liquid is sprayed through a nozzle provided at one side of the chamber to remove organic contaminants and natural oxide films remaining on the substrate surface (S10). At this time, the first cleaning solution includes ozone (O3) and diluted hydrofluoric acid (hereinafter referred to as DHF) solution. Here, the DHF solution is a solution of hydrofluoric acid (HF) and ultrapure water, and usually, effectively removes chemical oxides and native oxides generated during the cleaning process. In addition, the first cleaning liquid may effectively remove metal contaminants contained in the oxide film.

The board | substrate which completed step S10 performs the rinse process of removing the 1st washing liquid and particle which remain on the said board | substrate surface with a 2nd washing liquid (S20). The second cleaning liquid used in the rinsing step is, for example, hydrogen water having a hydrogen concentration in the range of 1.4 ppm to 1.8 ppm and an acidity (pH) of 10 or more. The hydrogen water performs particle removal and removal of the first cleaning liquid. Conventionally, in the rinsing step, by simply using ultrapure water, the remaining cleaning liquid of the substrate was rinsed, but the hydrogen water rinsed off the substrate by removing the particles remaining on the substrate together with the rinsing of the cleaning liquid remaining on the substrate. Can be performed simultaneously.

Here, the first cleaning liquid may be vibrated at high frequency using high frequency ultrasonic waves for more effective cleaning of the substrate. In particular, the use of a very high frequency of about 1000 kHz frequency is called megasonic cleaning, which applies the high frequency to the substrate surface and vibrates the first cleaning liquid sprayed on the surface of the substrate to remove the first cleaning liquid. It is a substrate cleaning method to increase the cleaning rate. For example, the hydrogen water is sprayed on the substrate by a nozzle disposed within a distance of 40 mm from the substrate, and the ultrasonic wave having a frequency of 1.5 MHz or more is supplied to the substrate and the first cleaning liquid sprayed on the substrate to provide the ultrasonic wave. The substrate is cleaned by vibrating the cleaning liquid.

After the step S20 is completed, the substrate is spin dried using, for example, a rotational force of 3000 rpm or more (S30). In other words, the spin drying rotates the substrate to remove the cleaning liquid remaining on the surface of the substrate from the surface of the substrate using a rotational force.

The single wafer cleaning method as described above is a first cleaning liquid containing ozone and DHF solution to remove organic contaminants, natural oxide films, and metal contaminants present on the substrate, and thereafter, the first substrate remaining on the substrate with hydrogen water. By performing the rinsing process of removing the cleaning liquid and the pitacle, the cleaning step of the substrate can be made in two steps, which greatly shortens the cleaning process time of the substrate.

(Substrate cleaning method 2)

2 is a flowchart illustrating a method of cleaning a sheet type substrate according to another exemplary embodiment of the present disclosure. Referring to FIG. 2, in the single wafer cleaning method according to another embodiment of the present invention, in the single wafer cleaning method shown in FIG. 1, the step of cleaning the substrate with a third cleaning liquid is performed between steps S10 and S20. It is characterized by including. That is, the single wafer cleaning method according to another embodiment of the present invention includes the step of cleaning the substrate with the first cleaning liquid (S10), the step of cleaning the substrate with the third cleaning liquid (S20), and rinsing the substrate with the second cleaning liquid. Step S30, and drying the substrate (S40).

When the substrate cleaning process is started, the substrate, which has been subjected to a predetermined semiconductor process, is rotated by being seated on a chuck provided in the chamber to clean organic contaminants, natural oxide films, and metal contaminants existing on the surface of the substrate.

When the substrate is rotated, the first cleaning liquid is sprayed through a nozzle provided at one side of the chamber to remove organic contaminants remaining on the surface of the substrate (S10). At this time, the first cleaning solution includes an ozone (O3) and DHF (Dilute Hydrofluori Acid. DHF) solution as in an embodiment of the present invention. Alternatively, the first cleaning liquid may be ozone water including ozone (O 3) and ultrapure water (UPW: Ultrapure Water). The ozone water is a more powerful oxidant than hydrogen peroxide, and does not decompose in solution to form a reaction product harmful to the human body, and it is environmentally friendly and economical because it can reduce the amount of waste water during the cleaning process.

When step S10 is completed, a 3rd washing | cleaning liquid is sprayed on the said substrate surface which rotates, and a washing process is performed (S20). In this case, the third cleaning liquid is a DHF solution described in the substrate cleaning method 1, a solution in which the DHF solution and hydrogen water are mixed, or hydrogen water. The third cleaning liquid removes the native oxide film, metal contaminants, and particles present on the substrate surface.

Alternatively, the third cleaning solution may be a standard cleaning solution-1 (SC-1: Standard Clean-1, hereinafter referred to as 'SC-1'). The SC-1 solution is a cleaning solution containing ammonia (NH 4 OH), hydrogen peroxide (H 2 O 2), and ultrapure water. For example, a typical SC-1 solution is mixed with ammonia, hydrogen peroxide, and ultrapure water at a ratio of approximately 1: 1: 5 and used to remove particles and organic contaminants at temperatures between 75 and 90 degrees.

When step S20 is completed, a rinsing step of removing the first and third cleaning solutions, particles, and the like remaining on the surface of the substrate is performed (S30). The second cleaning liquid used in the rinse step is, for example, hydrogen water having a hydrogen concentration in the range of 1.4 ppm to 1.8 ppm and an acidity (pH) of 10 or more. Here, the second cleaning liquid may include a case of ultrapure water (UPW). In this case, the substrate may be cleaned by a method using high frequency ultrasonic waves, that is, a megasonic cleaning method, for more effective cleaning of the substrate. For example, the hydrogen water is sprayed on the substrate by a nozzle disposed within a distance of 40 mm from the substrate, and the ultrasonic wave having a frequency of 1.5 MHz or more is supplied to the substrate and the first cleaning liquid sprayed on the substrate to provide the ultrasonic wave. The substrate is cleaned by vibrating the cleaning liquid.

When step S30 is completed, a drying process for removing the solution remaining on the surface of the substrate is performed (S40). The drying process method is spin drying for removing the cleaning liquid remaining on the surface of the substrate using the rotational force described in Example 1.

According to another embodiment of the present invention described above, the substrate is cleaned by using ozone water solution and hydrogen water continuously. That is, in general, after washing with ozone water, after washing with a predetermined washing liquid, the rinse process is performed with ultrapure water. However, in the above-described embodiment, the rinse process is performed on the substrate with hydrogen water after washing the substrate. A rinsing process for removing the first and second cleaning liquids and particles is performed. Thus, the step of cleaning the substrate can be reduced.

Hereinafter, specific embodiments of the single wafer cleaning method illustrated in FIGS. 1 and 2 will be described in detail with reference to FIGS. 3A to 3B. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the invention to those skilled in the art. Parts denoted by the same reference numerals throughout the specification represent the same components, specific details of the above-described components are not described repeatedly.

Example 1

Figure 3a is a flow chart showing an embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3A, the single wafer cleaning method according to the present invention includes washing the substrate with a cleaning solution including ozone water and DHF (S11), washing the substrate with an SC-1 solution (S21), and hydrogen water. Rinsing the substrate (S31), and drying the substrate (S41).

When cleaning of the substrate is started, the substrate is subjected to the semiconductor process is placed on the upper surface of the chuck is rotated, the cleaning liquid removes the organic contaminants and natural oxide film present on the surface of the substrate (S11).

When step S11 is completed, the SC-1 solution is sprayed on the substrate surface to remove particles remaining on the substrate surface (S21). Since the SC-1 solution may cause trace metal contamination due to a low redox potential, the SC-1 solution may be a SC-2 (Standard Clean-2) solution. It can be combined with the cleaning method. The SC-2 solution, for example, mixes hydrochloric acid, hydrogen peroxide, and ultrapure water in a ratio of approximately 1: 1: 5 to remove the transition metal contaminants at temperatures ranging from 75 to 90 ° C.

When step S21 is completed, a rinse step of removing the cleaning liquid remaining on the substrate surface with hydrogen water is performed (S31). Megasonic cleaning may be used for the rinsing process. When step S31 is completed, a board | substrate is dried (S41). Drying of the substrate includes a spin drying method.

Example 2

Figure 3b is a flow chart showing another embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3B, the method of cleaning a sheet type substrate according to the present invention includes cleaning the substrate with a cleaning solution including ozone water and DHF (S12), and cleaning the substrate with a cleaning solution including SC-1, a solution, and a DHF solution. Step S22, rinsing the substrate with hydrogen water (S32), and drying the substrate (S42).

Step S12 is a step of removing the organic contaminants and the natural oxide film present on the surface of the substrate by spraying a cleaning liquid containing ozone water and DHF through the nozzle. Thereafter, step S22 removes particles and natural oxide films remaining on the surface of the substrate with a cleaning solution containing an SC-1 solution and a DHF solution. After the step S22 is completed, the rinsing process of removing the cleaning liquids and particles remaining on the surface of the substrate with hydrogen water is performed, followed by drying the substrate (S42) to complete the cleaning of the substrate. A megasonic cleaning method is used for the rinsing process, and the substrate may be spin dried.

Example 3

Figure 3c is a flow chart showing another embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3B, the method for cleaning a single wafer according to the present invention includes cleaning the substrate with a cleaning solution including ozone water and DHF (S13), cleaning the substrate with ozone water (S23), and cleaning the substrate with hydrogen water. Rinsing (S33), and drying the substrate (S43).

Step S13 is a step of removing the organic contaminants and the natural oxide film present on the substrate surface by spraying a cleaning liquid containing ozone water and DHF to the substrate surface through a nozzle. Subsequently, step S23 removes particles and natural oxide film remaining on the substrate surface with ozone water. When step S23 is completed, a rinsing process of removing the cleaning liquids and particles remaining on the surface of the substrate with hydrogen water is performed (S33), and then the substrate is dried (S43) to complete the cleaning of the substrate. A megasonic cleaning method is used for the rinsing process, and the substrate may be spin dried.

Example 4

Figure 3d is a flow chart showing another embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3D, in the method of cleaning a sheet type substrate according to the present invention, a step of cleaning the substrate with ozone water (S14), a step of cleaning the substrate with DHF solution (S24), and a step of rinsing the substrate with hydrogen water (S34). And, and drying the substrate (S44).

Step S14 is a step of removing the organic contaminants and the natural oxide film present on the substrate surface by spraying ozone water onto the substrate surface through a nozzle. Step S24 then removes the particles and natural oxide film remaining on the substrate surface with ozone water. When step S24 is completed, a rinse process of removing the cleaning liquids and particles remaining on the surface of the substrate with hydrogen water is performed (S34), and then the substrate is dried (S44) to complete the cleaning of the substrate. A megasonic cleaning method is used for the rinsing process, and the substrate may be spin dried.

Example 5

Figure 3e is a flow chart showing another embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3E, in the method of cleaning a single wafer according to the present invention, the substrate is cleaned with ozone water (S15), the substrate is cleaned with a cleaning solution including hydrogen water and a DHF solution (S25), and the substrate is cleaned with ultrapure water. Rinsing (S35), and drying the substrate (S45).

Step S15 is a step of washing organic contaminants and natural oxide films present on the substrate surface by spraying ozone water onto the substrate surface through a nozzle. Thereafter, step S25 removes the particles and the magnetic oxide film remaining on the surface of the substrate with a cleaning solution containing hydrogen water and DHF. Here, the cleaning liquid including hydrogen water and DHF may perform a rinsing process to remove the particles and the natural oxide film while simultaneously removing the ozone water used in step S15.

When step S25 is completed, a rinsing process of removing the cleaning liquids and particles remaining on the surface of the substrate with ultrapure water is performed (S35), and the substrate is dried (S45) to complete the cleaning of the substrate. A megasonic cleaning method is used for the rinsing process, and the substrate may be spin dried.

Example 6

Figure 3f is a flow chart showing another embodiment of a single wafer cleaning method according to the present invention. Referring to FIG. 3F, the sheet-type substrate cleaning method according to the present invention includes: cleaning the substrate with ozone water (S16), cleaning the substrate with hydrogen water (S26), rinsing the substrate with ultrapure water (S36), And drying the substrate (S46).

Step S16 is a step of washing organic contaminants and natural oxide films present on the substrate surface by spraying ozone water onto the substrate surface through a nozzle. Thereafter, step S26 removes particles remaining on the surface of the substrate with hydrogen water. Step 26 may perform a rinse process for removing the ozone water used in step S10.

When step S26 is completed, a rinse process of removing the cleaning liquids and particles remaining on the surface of the substrate with ultrapure water is performed (S36), and then the substrate is dried (S46) to complete the cleaning of the substrate. A megasonic cleaning method is used for the rinsing process, and the substrate may be spin dried.

As described above, the single wafer cleaning method according to the present invention has the effect of increasing the throughput per unit time by reducing the number of steps in the unit process in the cleaning process.

In addition, the single wafer cleaning method according to the present invention increases the cleaning efficiency of the single wafer cleaning apparatus by effectively applying the appropriate mixing and spraying order of the respective cleaning liquids.

Claims (9)

In the single wafer cleaning method, (a) spraying a first cleaning solution on the substrate surface to remove contaminants and oxide films; (b) spraying a second cleaning liquid onto the substrate surface to rinse the first cleaning liquid and particles remaining on the substrate surface; (c) drying the substrate. The method of claim 1, The second cleaning solution is a single wafer cleaning method, characterized in that the hydrogen water. The method of claim 1, The single wafer cleaning method further comprises the step of cleaning the substrate surface with a third cleaning liquid between step (a) and (b). The method of claim 3, wherein The first cleaning liquid comprises ozone water, and the third cleaning liquid comprises hydrofluoric acid and ultrapure water. The method of claim 3, wherein The first cleaning liquid comprises ozone water, and the third cleaning liquid comprises hydrogen water. The method of claim 3, wherein The first cleaning liquid comprises ozone water, and the third cleaning liquid comprises hydrogen, hydrofluoric acid, and ultrapure water. The method of claim 3, wherein The first cleaning liquid comprises ozone, hydrofluoric acid, and ultrapure water, and the third cleaning liquid comprises ammonia, hydrogen peroxide, and ultrapure water. The method of claim 3, wherein The first cleaning liquid comprises ozone, hydrofluoric acid, and ultrapure water, and the third cleaning liquid comprises ammonia, hydrogen peroxide, hydrofluoric acid, and ultrapure water. The method of claim 3, wherein The first cleaning liquid comprises ozone, hydrofluoric acid, and ultrapure water, and the third cleaning liquid comprises ozone water.

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