JP2003249477A - Single-wafer washing device for semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single-wafer basis washing device for a semiconductor substrate which can reduce washing process time by finishing washing process by observing the removal state of a surface oxide film without depending on washing time. <P>SOLUTION: The device has a casing 2; a rotary table 4 which is provided to the casing 2, and rotated and driven by a driving shaft 3 and whereon a semiconductor substrate W is mounted and fixed; a washing solution supply nozzle 5 which is provided to supply washing solution to the surface of the semiconductor substrate W; and an oxide film detection sensor 6 which detects the removal state of an oxide film of a surface of the semiconductor substrate W and is provided to optically face the surface of the semiconductor substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate single wafer cleaning apparatus, and more particularly to a semiconductor substrate single wafer cleaning apparatus provided with an oxide film detection sensor capable of detecting the state of an oxide film.

[0002]

2. Description of the Related Art Conventionally, cleaning of a semiconductor substrate has been carried out by a batch-type cleaning device using HF treatment to reduce the amount of particles and metal impurities. But,
In order to increase the diameter of a semiconductor substrate and obtain a substrate with higher cleanliness in recent years, a single wafer cleaning apparatus 11 as shown in FIG. 4 is utilized. In this conventional single-wafer cleaning apparatus 11, functional water L such as ozone supplied from the cleaning liquid supply nozzle 12 is supplied.
_It is general to use ₀ to remove particles of the semiconductor substrate W ₀ placed and fixed on the rotary table 13 and use HF to reduce the amount of metal impurities. In particular, this conventional single-wafer cleaning apparatus 11 cannot remove Cu and A that cannot be removed by HF cleaning.
It is said to be effective in removing impurities other than metals such as u. To remove metal impurities such as Cu, the surface of the wafer is oxidized with ozone water, and metal impurities such as Cu incorporated in the oxide film are removed by the subsequent HF treatment. Generally, in the removal of particles with ozone water, particles adhering through the interposition of organic substances are oxidatively decomposed with ozone water and removed. It is said that the surface of the wafer is oxidized by ozone water and particles adhering to the surface of the wafer are removed by the subsequent HF treatment.

However, a natural oxide film is generally formed on the surface of the silicon substrate due to oxidation in air or the like.

In the conventional single-wafer cleaning apparatus, the surface of the substrate is oxidized by the functional water such as ozone water in the step of removing particles, and then the metal impurities are removed by the HF treatment. However, the time for which the oxide film formed on the surface of the silicon substrate by ozone water or the like is removed by HF may vary depending on the state of the wafer. It is known that particles and metal impurities on the surface of the silicon substrate remain unless the oxide film is completely removed by HF cleaning.
Therefore, when cleaning the silicon substrate, the cleaning time is extended and the cleaning time is extended.

[0005]

Therefore, there is a demand for a single-wafer cleaning apparatus for semiconductor substrates, which can shorten the cleaning process time by observing the removal state of the surface oxide film and terminating the cleaning process regardless of the cleaning time. Has been done.

The present invention has been made in view of the above-mentioned circumstances, and the semiconductor substrate can be shortened by observing the removal state of the surface oxide film and terminating the cleaning process regardless of the cleaning time. An object is to provide a single-wafer cleaning device.

[0007]

To achieve the above object, according to one aspect of the present invention, a casing and a rotary table on which a semiconductor substrate is mounted and fixed by being rotationally driven by a drive shaft provided in the casing. A cleaning liquid supply nozzle provided to supply a cleaning liquid for the surface of the semiconductor substrate, and a cleaning liquid supply nozzle provided so as to optically face the surface of the semiconductor substrate by detecting the removal state of the oxide film on the surface of the semiconductor substrate. A single-wafer cleaning apparatus for semiconductor substrates is provided, which has an oxide film detection sensor. As a result, the cleaning step time can be shortened by observing the removal state of the surface oxide film and terminating the cleaning step regardless of the cleaning time.

In a preferred example, the oxide film detection sensor receives a light emitting element which emits light in a wavelength range which is absorbed or diffusely reflected by the presence of a liquid and a light which is reflected from the surface of the semiconductor substrate. And a light receiving element that operates. As a result, it becomes possible to easily monitor the removal state of the oxide film on the substrate surface with a simple structure.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a single-wafer cleaning apparatus for semiconductor substrates according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of a single-wafer cleaning apparatus for semiconductor substrates according to the present invention.

As shown in FIG. 1, a single-wafer cleaning apparatus for semiconductor substrates 1 according to the present invention has a casing 2 and a semiconductor device W mounted on the casing 2 and rotationally driven by a drive shaft 3 to mount and fix the semiconductor substrate W thereon. A rotary table 4, a cleaning liquid supply nozzle 5 provided to supply a cleaning liquid L to the surface of a semiconductor substrate, for example, a silicon substrate W, and an oxide film detection sensor 6 for detecting a removal state of an oxide film on the surface of the semiconductor substrate W. have.

The casing 2 serves to prevent the cleaning liquid L from scattering outside the single-wafer cleaning apparatus 1. The rotary table 4 provided in the casing 2 is mounted on the rotary table 4. The silicon substrate W fixed by the base material fixing member 7 is rotated at high speed.

The cleaning liquid supply nozzle 5 is for cleaning the surface of the semiconductor substrate W by spraying ozone water, HF water and pure water onto the surface of the silicon substrate W to supply the same.

Further, the oxide film detection sensor 6 is for detecting the presence of HF water on the surface of the silicon substrate W and monitoring the removal state of the oxide film on the substrate surface. The oxide film detection sensor 6 is provided so as to be optically opposed to the surface of the semiconductor substrate W, and for example, has a wavelength range in which visible light is absorbed on the surface of the silicon substrate in addition to the presence of liquid or diffuse reflection occurs. A light emitting element that emits light,
It has a light receiving element for receiving light reflected from the surface of the silicon substrate, and inputs a reflection signal to a control device (not shown) that controls the whole single wafer cleaning apparatus 1 to rotate the rotary table 4 and The cleaning liquid supply nozzle 5 is controlled. As a result, the removal state of the oxide film on the substrate surface can be easily monitored with a simple structure.

Next, a substrate single wafer cleaning method using the semiconductor substrate single wafer cleaning apparatus according to the present invention will be described.

As shown in FIG. 1, the silicon substrate W is placed on the turntable 4, and the silicon substrate W is fixed to the turntable 4 by the base material fixing member 7. Thereafter, the rotary table 4 is rotated to rotate the silicon substrate W, and functional water such as ozone water is sprayed from the cleaning liquid supply nozzle 5 onto the silicon substrate W to remove particles, and the substrate is processed by this ozone water. Remove particles on the surface. The surface of the substrate is oxidized, and generally the surface of the substrate becomes hydrophilic as shown in FIG.

Then, in order to remove metal impurities from the surface of the substrate, HF water is sprayed from the cleaning liquid supply nozzle 5 onto the surface of the oxidized silicon substrate W, and HF treatment is performed to gradually remove the oxide film. The surface of the silicon substrate from which the oxide film has been removed becomes hydrophobic.

However, in this cleaning process, since the silicon substrate W is rotating, H is generated at a specific location.
As the F-treated water flows, the substrate surface generally has a portion that is not covered with the HF-treated water as shown in FIG.

Therefore, by arranging the oxide film detection sensor 6 so as to face the silicon substrate W, the oxide film is removed to make the film hydrophobic and exposed to light, and the HF is used to remove the oxide film to make it hydrophobic. It is possible to monitor the condition of the surface of the substrate that has been activated.

In this monitoring process, before the surface of the substrate is completely made hydrophobic by the action of HF treatment, since the cleaning liquid is present on the surface of the substrate, the light emitted from the light emitting element 6a in the oxide film detection sensor 6 is The light is absorbed or irregularly reflected by the cleaning liquid and does not reach the light receiving element 6b. On the other hand, when the substrate surface is completely hydrophobic, the light emitting element 6a is
The light emitted from the substrate is reflected by the surface of the substrate and received by the light receiving element 6b.
To reach.

The state of the oxide film on the surface of the substrate can be monitored by determining the light receiving state of the light receiving element 6b by a control device (not shown).

As described above, the cleaning process time can be optimized by monitoring the state in which the substrate surface becomes hydrophobic during the HF treatment with the sensor.

[0023]

EXAMPLES Test method: Using the single-wafer cleaning apparatus for semiconductor substrates according to the present invention, an 8-inch silicon wafer was used as an object to be cleaned, and the surface of the silicon wafer was previously oxidized with ozone water. In order to change the state of oxide film formation on the wafer surface, wafers that were previously contaminated with isopropyl alcohol and those that were not contaminated were used. After that, HF treatment is performed and the case where the oxide film detection sensor is used (Example) and the case where it is not used (Conventional example)
The cleaning process time and the amount of Cu metal impurities present on the wafer surface were compared with each other. The number of wafers was 10 under each condition. Wafer surface before cleaning 1x1 Cu metal impurities
It is 0 ¹² atoms / cm ² . The cleaning process time in the conventional example was set to 15 seconds.

Results: Shown in Table 1.

[0025]

[Table 1]

HF treatment time is 15 sec with organic contamination
In the case of the conventional example fixed to c, it was found that the Cu metal impurity amount on the surface of each wafer had a difference of 1 × 10 ⁹ to 10 ¹⁰ .

On the other hand, in the example, it was found that the HF treatment time could be optimized, and the Cu metal impurity amount on the wafer surface was all 1 × 10 ⁹ or less, which was below the detection limit.

When there is no organic contamination, C on the wafer surface
It was found that there was no difference in the amount of u metal impurities between the conventional example and the example. However, in the embodiment, the HF processing time is 4 times that of the conventional example.
It turned out that it can be shortened to 0-60%.

[0029]

According to the single-wafer cleaning apparatus for semiconductor substrates of the present invention, the cleaning process time can be shortened by observing the removal state of the surface oxide film and terminating the cleaning process regardless of the cleaning time. A single-wafer cleaning apparatus for semiconductor substrates can be provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a single-wafer cleaning apparatus for semiconductor substrates according to the present invention.

FIG. 2 is a conceptual diagram of a surface state of a semiconductor substrate during a general cleaning process.

FIG. 3 is a conceptual diagram of a surface state of a semiconductor substrate during a general cleaning process.

FIG. 4 is a conceptual diagram of a conventional single-wafer cleaning apparatus for semiconductor substrates.

[Explanation of symbols]

1 Single-wafer cleaning equipment for semiconductor substrates 2 casing 3 drive axis 4 turntable 5 Cleaning liquid supply nozzle 6 Oxide film detection sensor 7 Base material fixing member L cleaning liquid W Silicon substrate

Claims (2)

[Claims] 1. A casing, a rotary table which is provided on the casing and is rotationally driven by a drive shaft to mount and fix a semiconductor substrate, and a cleaning liquid supply nozzle which is provided to supply a cleaning liquid for the surface of the semiconductor substrate. A single-wafer cleaning apparatus for a semiconductor substrate, comprising: an oxide film detection sensor that is provided so as to detect a removal state of an oxide film on the surface of the semiconductor substrate and optically oppose the surface of the semiconductor substrate. 2. The oxide film detection sensor includes a light emitting element that emits light in a wavelength range that is absorbed or diffusely reflected due to the presence of a liquid, and a light receiving element that receives light reflected from the surface of a semiconductor substrate. The single-wafer cleaning apparatus for semiconductor substrates according to claim 1, further comprising: