JP3353477B2 - Pure water rinsing method and semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of rinsing a semiconductor wafer with pure water after cleaning the wafer with a chemical solution and a semiconductor device.
And a method for manufacturing the device .

[0002]

2. Description of the Related Art Contaminants adhere to the surface of a wafer in almost all of the manufacturing steps of a semiconductor device. Since the attachment of the contaminants to the wafer surface causes a reduction in the yield of the semiconductor device, a wafer cleaning step is repeatedly inserted into the process flow of manufacturing the semiconductor device.

In the above-described wafer cleaning step, a chemical treatment of the wafer is performed using various chemicals, and after this chemical treatment, a pure water rinse for removing a residual chemical attached to the wafer surface is performed. This pure water rinse is to immerse the wafer in pure water supplied in an overflow state in a water tank,
Alternatively, the cleaning is performed by spraying pure water onto the cleaning surface of the wafer. The above-mentioned pure water is used at a high temperature or a normal temperature, and when high-temperature pure water is used, the rinsing time can be shortened because the residual chemical solution on the wafer surface can be removed earlier as compared with the normal temperature pure water. it can. With it
The growth of bacteria in pure water is prevented, and the wafer can be rinsed with pure water having a high degree of cleanliness.

[0004]

However, the pure water rinse described above has the following problems. That is, in the rinsing using high-temperature pure water, the reaction between the chemical liquid locally remaining on the wafer surface and the high-temperature pure water promotes the local reaction of the chemical liquid on the wafer surface. As a result, for example, unevenness of the chemical treatment effect such as etching unevenness occurs on the wafer surface. On the other hand, in the case of rinsing using pure water at room temperature, it takes more time to remove the residual chemical solution attached to the wafer surface than in the case of using pure water at high temperature. For this reason, the pure water rinsing step determines the rate of the entire cleaning step including the chemical solution treatment, and causes a reduction in the throughput of the cleaning step.

Further, pure water at normal temperature has a weak etching effect on the wafer surface. For this reason, rinsing with pure water at room temperature does not have the effect of removing contaminants remaining on the wafer surface, for example, from the residual chemical solution. 2. Description of the Related Art In recent years, miniaturization of a device structure has been progressing with high integration of a semiconductor device. For this reason, the contaminants taken out of the cleaning solution as described above remain on the wafer surface, which greatly affects product yield and reliability.

Accordingly, an object of the present invention is to provide a pure water rinsing method and a method of manufacturing a semiconductor device which solve the above-mentioned problems.

[0007]

In order to achieve the above object, a pure water rinsing method and a method of manufacturing a semiconductor device according to the present invention are provided.
First, a wafer that has been treated with a chemical solution is rinsed with pure water at normal temperature, and then rinsed with pure water at high temperature. After rinsing the wafer with high-temperature pure water, rinsing is performed with normal-temperature pure water.

The high-temperature pure water is set at a predetermined temperature between 50 ° C. and the boiling point or between 65 ° C. and the boiling point.

[0009]

In the above-described pure water rinsing method and semiconductor device manufacturing method , first, the wafer rinsed with normal temperature pure water is rinsed with high temperature pure water, so that most of the chemical remaining on the wafer surface is at room temperature. After being removed by pure water, the wafer is rinsed with high-temperature pure water. Therefore, in a state where the reaction between the residual chemical and the high-temperature pure water is prevented, the remaining residual chemical is removed by the high-temperature pure water. Since the etching of the wafer surface and the oxidation of the wafer surface proceed in high-temperature pure water, contaminants on the wafer surface are removed and a natural oxide film is formed on the wafer surface.

When rinsing the wafer with high-temperature pure water and then rinsing with normal-temperature pure water, the pure-water rinsing is completed in a state where the wafer temperature is cooled to normal temperature and the activity is suppressed to a low level. I do.

When the temperature of the high-temperature pure water is set to a predetermined temperature between 50 ° C. and the boiling point, at least the surface layer of the natural oxide film formed in the normal-temperature pure water is etched. . On the other hand, the temperature of the high-temperature pure water is set to 65 ° C.
When the temperature is set to a predetermined temperature before the boiling point, the natural oxide film on the wafer surface is etched.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the process chart of FIG. Here, the wafer 1 to be rinsed with pure water has been subjected to chemical treatment, and the chemical attached to the wafer 1 during the chemical treatment remains on the surface. When the wafer 1 is rinsed with pure water in the process of manufacturing a semiconductor device , first, as shown in FIG. 1A, pure water 10 at normal temperature is supplied into a pure water tank 2 while overflowing. Then, the wafer 1 is rinsed by immersing the wafer 1 in the pure water 10 at normal temperature. Here, for example, rinsing is performed for about 1 minute.

Next, as shown in FIG. 1 (2), high-temperature pure water 20 is supplied into the pure water tank 2 while overflowing. As a result, the wafer 1 is rinsed with the high-temperature pure water 20. Here, rinsing is performed, for example, until the specific resistance of the high-temperature pure water 20 recovers.

After the above, as shown in FIG. 1 (3), room temperature pure water 30 is supplied into the pure water tank 2 while overflowing. Thus, the wafer 1 is rinsed with pure water 30 at room temperature.

In the pure water rinsing method, since the wafer 1 rinsed with the pure water 10 at normal temperature is first rinsed with the pure water 20 at high temperature, most of the chemical solution remaining on the surface of the wafer 1 is removed by the pure water 10 at normal temperature. After that, the wafer 1 is rinsed with high-temperature pure water 20. For this reason, in a state where the reaction between the residual chemical liquid locally attached to the surface of the wafer 1 and the high-temperature pure water 20 is prevented, the remaining high-temperature pure water 20 removes the remaining residual chemical liquid. In the high-temperature pure water 20, etching of the surface of the wafer 1 and oxidation of the surface of the wafer 1 progress, so that contaminants on the surface of the wafer 1 are removed and a natural oxide film is formed on the surface of the wafer 1.

Further, The wafer 1 in the above state is
Since the wafer 1 is again rinsed with the normal temperature pure water 30, the pure water rinse is completed in a state where the temperature of the wafer 1 is cooled down to the normal temperature and the activity of the wafer surface is kept low.

The temperature of the high-temperature pure water 20 is set, for example, as follows. The graph of FIG. 2 is a graph showing the dependence of the removal of particles on pure water temperature when a wafer intentionally contaminated with silicon chips made into fine particles as particles adsorbed on a natural oxide film is rinsed with high-temperature pure water. Show. From this graph, it can be seen that when the temperature of pure water is 50 ° C. or higher, the particle removal efficiency is significantly increased. From this, the temperature of high-temperature pure water is set to 50
The temperature is set to a predetermined temperature between ° C and the boiling point. Here, the temperature is, for example, 60 ° C. FIG. 3 is a graph showing the rinsing time dependency of particle removal with pure water at 60 ° C. From this graph, it can be seen that in pure water at 60 ° C., the rinsing time of 15 minutes or more increases the particle removal efficiency. Therefore, here, the rinsing time with the high-temperature pure water (20) is set to 15 minutes or more and until the specific resistance of the pure water recovers.

As described above, when the high temperature of the pure water (20) is set between 50 ° C. and the boiling point, the wafer 1 is rinsed as shown in FIG. First, FIG.
As shown in FIG. 5, a natural oxide film 1a is formed on the surface of the wafer 1 which is rinsed with high-temperature pure water (20) as described above. On the natural oxide film 1a, for example, a particle-like contaminant 2 is attached. In the pure water rinsing, the temperature of the high-temperature pure water (20) is set to 5
The temperature was set to a predetermined temperature between 0 ° C and the boiling point. Therefore, in the rinsing using the high-temperature pure water (20), FIG.
As shown in (1), the surface layer of the native oxide film 1a is etched and the native oxide film 1a is etched together with the native oxide film 1a.
The contaminants 2 adhering to a are removed. Then, in the same manner as described above, in the high-temperature pure water (20), the formation of a new natural oxide film proceeds, so that as shown in FIG.
Is a natural oxide film 1b having a newly formed surface
Covered with.

The temperature of the high-temperature pure water (20) is as follows:
For example, it may be set as follows. The graph in FIG.
In particular, it shows the concentration of Fe after immersing a wafer intentionally contaminated with Fe easily taken into a natural oxide film into pure water at each temperature in the same manner as the above-mentioned rinsing with high-temperature pure water (20). . From this graph, it can be seen that up to 65 ° C., the removal efficiency of Fe increases with the temperature of pure water. For this reason, the temperature of the high-temperature pure water (20) is set to a predetermined temperature between 65 ° C. and the boiling point. Here, the temperature is, for example, 65 ° C. The graph of FIG. 6 is a graph showing the rinsing time dependency of Fe removal with pure water at 65 ° C. From this graph, it can be seen that in pure water at 65 ° C., the rinsing time of 5 minutes or more increases the Fe removal efficiency. Therefore, here, the rinsing time with the high-temperature pure water (20) is set to 5 minutes or more and until the specific resistance of the pure water recovers.

As described above, when the temperature of the high-temperature pure water (20) is set between 65 ° C. and the boiling point, the wafer 1 is rinsed as shown in FIG. First, FIG.
As shown in FIG. 5, a natural oxide film 1a is formed on the surface of the wafer 1 which is rinsed with high-temperature pure water (20) as described above. The contaminant 2 adheres to the surface of the natural oxide film 1a, and the contaminant 3 is incorporated therein. Here, the temperature of the high-temperature pure water (20) is set to a predetermined temperature between 65 ° C. and the boiling point, particularly from the efficiency of removing Fe easily taken into the oxide film. For this reason, in rinsing with the high-temperature pure water (20), most of the natural oxide film 1a is etched, and contaminants 2 and 3 are removed together with the natural oxide film 1a. Further, in the high-temperature pure water (20), the formation of a new natural oxide film proceeds along with the etching of the natural oxide film 1a, and therefore, as shown in FIG. 7B, the surface of the wafer 1 is newly formed. It is covered with the formed natural oxide film 1c.

In the above embodiment, a dip method in which a wafer is immersed in pure water supplied in an overflow state into a pure water tank has been described as an example. However, the present invention is also applicable to a spray method in which pure water is sprayed on a wafer.

[0022]

As described above, the pure water rinse of the present invention is described above.
According to the method and the method for manufacturing a semiconductor device performing the pure water rinsing , the wafer surface is first rinsed with normal temperature pure water and then rinsed with high temperature pure water, so that the residue locally adhered to the wafer surface is rinsed. The rinsing time can be reduced while preventing the reaction between the chemical solution and the high-temperature pure water. Therefore, it is possible to improve the throughput of the cleaning process while preventing etching unevenness on the wafer surface. In the rinsing with the high-temperature pure water, the etching of the wafer surface and the formation of the natural oxide film proceed to form a clean natural oxide film on the wafer surface from which contaminants on the wafer surface have been removed. Becomes possible. Therefore, the yield of the semiconductor device can be improved. When the wafer is rinsed with high-temperature pure water and then with normal-temperature pure water, the activity of the wafer surface can be suppressed to a low level, and the pure-water rinse can be completed. It is possible to prevent the contaminant from being adsorbed to the subsequent wafer. Further, when the high-temperature pure water is set at a predetermined temperature between 50 ° C. and the boiling point, it becomes possible to remove contaminants adhering to the natural oxide film on the wafer surface. On the other hand, when the high-temperature pure water is set at a predetermined temperature between 65 ° C. and the boiling point, it becomes possible to remove the contaminants taken into the natural oxide film together with the contaminants.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining an embodiment.

FIG. 2 is a graph of pure water temperature dependence of particle removal.

FIG. 3 is a graph showing the rinsing time dependence of particle removal.

FIG. 4 is a diagram showing a change in a wafer surface layer according to an embodiment.

FIG. 5 is a graph of the temperature dependence of pure water for removing Fe.

FIG. 6 is a graph of rinse time dependency of Fe removal.

FIG. 7 is a diagram showing a change in a wafer surface layer according to an example.

[Explanation of symbols]

 1 Wafer 10,30 Pure water at normal temperature 20 Pure water at high temperature

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-31945 (JP, A) JP-A-6-246247 (JP, A) JP-A-3-270228 (JP, A) JP-A-63-1988 133534 (JP, A) JP-A-63-114131 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304

Claims (4)

(57) [Claims] 1. A method of rinsing a wafer after chemical treatment with pure water, rinsing the wafer with pure water at room temperature, rinsing the wafer with pure water at high temperature, and then purifying the wafer with pure water at room temperature. With the wafer
Rinsing the pure water. 2. A pure water rinsing method according to claim 1 , wherein said high-temperature pure water is set at a predetermined temperature between 50 ° C. and a boiling point. 3. The pure water rinsing method according to claim 1 , wherein the high-temperature pure water is set at a predetermined temperature between 65 ° C. and a boiling point. 4. A method for manufacturing a semiconductor device, comprising rinsing a wafer after chemical treatment with pure water, wherein the wafer is rinsed with pure water at room temperature, and then the wafer is rinsed with pure water at high temperature . After that, the wafer with pure water at room temperature
Rinsing the semiconductor device.