JPH06281600A - Total-reflection x-ray fluorescence analyzer - Google Patents

Abstract

PURPOSE:To provide the total-reflection X-ray fluorescence analyzer having a highly accurate, inexpensive surface inspecting system with the simple constitution. CONSTITUTION:A cassette mounting stage 12 is provided at the neighboring position of a main body 11 of a total-reflection X-ray fluorescence analyzer. A wafer conveying robot 13 is provided between the analyzer main body 11 and the cassette mounting stage 12. A plurality of wafers 13 are mounted on a cassette 14. At the neighborhood of the analyzer main body 11 and the cassette mounting stage 12, an optical microscope device 16, which is the surface inspecting system of the present embodiment, is provided. The optical microscope device 16 is constituted of an optical microscope 17 and a wafer stage 18. A moving scale 18a as the positioning means in the X-Y directions is provided in the wafer stage 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total reflection X-ray fluorescence analyzer for use in total reflection X-ray fluorescence.

[0002]

2. Description of the Related Art Generally, a total reflection X-ray fluorescence analysis method is widely used as a method for analyzing trace elements on the surface of a wafer in the process of manufacturing a semiconductor wafer. Conventionally, as a total reflection X-ray fluorescence analyzer using the total reflection X-ray fluorescence analysis method, there is one disclosed in JP-A-3-202760.

This apparatus is equipped with a surface inspection system for obtaining inspection information of each point of the coordinates corresponding to the coordinates set on the surface of the wafer. Here, the inspection information means the elements (Cr, Fe, C) attached to the surface of the wafer.
u, Zn, etc.) adhesion state of the sample, distribution and particle size of the adhered sample particles, scratches and defects on the surface of the wafer, and the like. In addition, the surface inspection system obtains inspection information of each point on the surface in correspondence with the coordinates set on the surface of the wafer,
You can remember this.

Therefore, in this apparatus, the coordinate area on the surface of the wafer most suitable for performing total reflection X-ray fluorescence analysis (hereinafter abbreviated as X-ray analysis) is easily retrieved from the inspection result by the surface inspection system. It is said that it will be possible and efficient X-ray analysis will be possible.

For example, when it is desired to perform an X-ray analysis on a portion having the highest distribution concentration of the sample adhered to the surface of the wafer, a region having the highest distribution concentration of the sample is searched from the inspection result by the surface inspection system, It is said that X-ray analysis only needs to be performed on the region. In addition, the area on the surface of the wafer on which the X-ray analysis was performed corresponds to the adhesion state of the sample adhered to the entire surface, or corresponds to the area where a large amount of the sample adheres locally. It is said that it can be easily determined whether or not it is present after performing X-ray analysis. Further, since the ratio of the sample attached to the portion where the X-ray analysis is performed to the total sample is obtained from the inspection result by the surface inspection system, the quantitative determination of the sample can be easily performed by using this. Also called.

By the way, in the publication, the following is proposed as a configuration example of the surface inspection system. 1) a stage (on which a wafer to be inspected is placed), a laser (which emits a laser beam irradiated on the surface of the wafer placed on the stage), and a reflecting mirror (which reflects the laser beam from the laser) Irradiate the surface of the wafer)
, Photomultiplier (detects the reflected light intensity of the laser beam reflected from the surface of the wafer), and A / D
An example in which a surface inspection system is configured by a converter (which performs A / D conversion of the output signal of the photomultiplier) and a central processing control unit (which processes the output signal of the A / D converter). In this example, the above-described surface inspection is performed by two-dimensionally scanning the laser light.

2) An example in which a CCD is used instead of the photomultiplier in the example of 1) above. In this example, the above-mentioned surface inspection is performed by line scanning in which a laser is expanded in a certain direction to irradiate a CCD.

3) In the example of 1) above, a lamp is used instead of the laser and a CRT is used instead of the photomultiplier. In this example, the above-mentioned surface inspection is performed based on the image data obtained from the CRT.

[0009]

However, in the above-mentioned conventional surface inspection system, although a quantitative inspection is possible and the inspection accuracy is extremely high, there is a problem that the structure is complicated and the cost is high. there were.

Further, the configuration example of the surface inspection system of 1) or 2) has an advantage that the inspection accuracy for the sample particles attached to the surface of the wafer is high. However, when the sample particles enter the inside of the wafer, when the sample particles react with the semiconductor single crystal forming the wafer to form a compound, and when the surface of the wafer is smooth, On the contrary, there was a problem that the inspection accuracy was lowered.

In such a total reflection X-ray fluorescence analysis method, since trace elements are analyzed, it is necessary to pay sufficient attention to careless contamination of the wafer during the analysis process.

However, in a commercially available total reflection X-ray fluorescence analyzer, a plurality of wafers are mounted in one cassette in order to analyze a plurality of wafers continuously, and the cassette is adjacent to the apparatus main body. Some of them are designed to be set on a cassette stand provided by the above. In such an apparatus, a wafer transfer robot provided separately from the apparatus main body extracts wafers one by one from a cassette set on a cassette table and transfers them to the apparatus main body. Here, the analysis and measurement chamber in the apparatus main body is in a state of being isolated from the surrounding atmosphere, and the cleanliness thereof is extremely high. Further, not only the apparatus main body but also a set of apparatuses including a cassette stand and a wafer transfer robot are installed in a clean room to obtain a sufficient cleanliness.

However, in recent years, due to the high integration of semiconductor integrated circuits, a higher degree of cleanliness than ever before is required in total reflection X-ray fluorescence analysis. However, since there are workers in the clean room, there is a limit to improving the cleanliness. In other words, in the conventional total reflection X-ray fluorescence analyzer, the analysis and measurement chamber in the main body of the apparatus is isolated from the atmosphere in the clean room, so even if the cassette mounting table and the wafer transfer robot are in the clean room atmosphere. Have been exposed to. Therefore, during the analysis of each wafer, there is a problem that the wafer is contaminated by the atmosphere in the clean room while the cassette on which the wafer is mounted is placed on the cassette stand.

The present invention has been made to solve the above problems, and an object of the present invention is to provide total reflection with a highly accurate and simple structure and an inexpensive surface inspection system. It is to provide a fluorescent X-ray analyzer.

Another object of the present invention is to provide a total reflection X-ray fluorescence analyzer capable of preventing inadvertent contamination of the wafer during the analysis process.

[0016]

The invention according to claim 1 is
In a total reflection X-ray fluorescence analyzer, a member having an optically smooth surface that totally reflects X-rays irradiated at a low irradiation angle,
The gist of the present invention is to include a positioning means for positioning the member by setting coordinates on an optically smooth surface of the member and an optical microscope.

According to a second aspect of the present invention, in a total reflection X-ray fluorescence analyzer, a box covering the total reflection X-ray fluorescence analyzer, pressurizing means for pressurizing the inside of the box, and cleanliness inside the box are provided. The gist is that it is provided with an air purifying means for enhancing it.

[0018]

Therefore, according to the first aspect of the invention, the surface of the member can be inspected by the optical microscope, and the coordinates of the surface of the member inspected by the optical microscope can be determined by the positioning means. Therefore, in the total reflection X-ray fluorescence analysis, it becomes possible to perform elemental analysis at a specific coordinate position on the surface of the member inspected by the optical microscope.

According to the second aspect of the present invention, the total reflection X-ray fluorescence analyzer is covered with a box, the inside of the box is pressurized by the pressurizing means, and the cleanliness is enhanced by the air cleaning means. Has been. Therefore, accurate total reflection X-ray fluorescence analysis can be performed regardless of the cleanliness of the installation location of the total reflection X-ray fluorescence analyzer.

[0020]

Embodiment (Embodiment of the invention described in claim 1) An embodiment of the invention described in claim 1 will be described below with reference to FIG.

FIG. 1 is a schematic view showing the appearance of a total reflection X-ray fluorescence analyzer of this embodiment. A cassette stand 12 is provided adjacent to a total reflection X-ray fluorescence analyzer main body (hereinafter abbreviated as the main body) 11. Device body 1
A wafer transfer robot 13 is provided between 1 and the cassette holder 12. A plurality of wafers 15 as members having an optically smooth surface are mounted on the cassette 14. An optical microscope device 16 which is a surface inspection system of the present embodiment is provided adjacent to the device body 11 and the cassette stand 12. The optical microscope device 16 comprises an optical microscope 17 and a wafer stage 18. Further, the wafer stage 18 is provided with a moving scale 18a as a positioning means in the XY directions.

Next, the analysis procedure by the total reflection X-ray fluorescence analyzer of this embodiment will be described. 1) Set the cassette 14 on which a plurality of wafers 15 are mounted on the cassette stand 12.

2) Any one wafer 15 mounted in the cassette 14 is transferred to the wafer stage 18 of the optical microscope device 16 by the wafer transfer robot 13. Then, the wafer 15 is set on the wafer stage 18.

3) The operator observes the surface of the wafer 15 set on the wafer stage 18 with the optical microscope 17
To obtain the inspection information described above. At this time,
Moving scale 18 provided on wafer stage 18
With a, it is possible to know the coordinates of the point being inspected by the optical microscope 17 in association with the coordinates arbitrarily set with the center of the wafer 15 as coordinates (0, 0). That is, in correspondence with the coordinates set on the surface of the wafer 15,
The inspection information of each point at the coordinates can be obtained.

4) The wafer 15 set on the wafer stage 18 is transferred to the apparatus main body 11 by the wafer transfer robot 13. Then, the device body 11
X-ray analysis is performed.

At this time, the operator performs an X-ray analysis based on the inspection information of the surface of the wafer 15 obtained by the surface inspection. That is, by making the coordinates of the X-ray analysis in the apparatus body 11 common to the coordinates at the time of the surface inspection by the optical microscope 17, the coordinates most suitable for performing the X-ray analysis from the inspection result by the surface inspection system. The area can be easily searched.

As described above, in this embodiment, by providing the optical microscope device 16 as the surface inspection system, efficient X-ray analysis can be performed as in the conventional example. Here, it cannot be denied that the surface inspection by the operator's optical microscope 17 is inferior to the conventional example in terms of quantitative inspection. However, there is an extremely high sensitivity to the human visual sense, and there are some that are inferior to those of the conventional example in the recognition power for the subtle changes in the state of the wafer surface, especially the changes in the color. For example, when the sample particles have entered the inside of the wafer, when the sample particles react with the semiconductor single crystal forming the wafer to form a compound, and when the surface of the wafer is smooth, Also, accurate inspection information can be obtained from the change in the color of the wafer surface.

Further, since the optical microscope device 16 has a simple structure as compared with the surface inspection system of the conventional example, it is easy to maintain and is very inexpensive. The present invention is
It goes without saying that it may be used not only for semiconductor wafers but also for X-ray analysis of other measurement samples.

(Embodiment of the invention described in claim 2) Next, an embodiment in which the invention described in claim 2 is embodied will be described with reference to FIG. In this embodiment, the same components as those shown in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 2 schematically shows a set of total reflection X-ray fluorescence analyzers of this embodiment. This total reflection fluorescence X
The complete line analyzer is installed in a clean room.
The analysis and measurement room 11a in the apparatus main body 11 is isolated from the atmosphere in the clean room. The cassette stand 12 and the wafer transfer robot 13 are housed in a box 21, which is isolated from the atmosphere in the clean room. An operator does not enter the box 21.

In the box 21, pressurized nitrogen gas is introduced through the pipe 22 and the air filter 23 into the suction port 23a.
Sent in from. Further, an exhaust pipe 24 is provided below the cassette holder 12 so that the nitrogen gas in the box 21 is discharged.

Therefore, the cleanliness of the nitrogen gas fed into the box 21 becomes extremely high by the air filter 23, and the inside of the box 21 is filled with the clean nitrogen gas. Here, the air filter 23 is a HEPA (High Efficiency Particulate Ai).
r-filter) filter and ULPA (Ultra Low Penetratio)
n Air-filter) A high-performance air filter such as a filter.

Further, since the nitrogen gas fed into the box 21 is pressurized, the inside of the box 21 is at a positive pressure with respect to the atmospheric pressure inside the clean room in which the apparatus is installed.

Further, the nitrogen gas suction port 23a is provided above the box 21, and the exhaust port of the exhaust pipe 24 is provided at the bottom of the box 21. Therefore, an air flow from the top to the bottom is generated in the box 21 by the nitrogen gas, and the particles in the nitrogen gas in the box 21 are diluted with clean nitrogen gas and discharged to the outside of the box 21.

As a result, the cleanliness inside the box 21 becomes extremely high. Next, the analysis procedure by the total reflection X-ray fluorescence analyzer of the present embodiment will be described. First, the cassette 14 on which a plurality of wafers 15 are mounted is set on the cassette stand 12. Next, the arbitrary wafer 15 mounted in the cassette 14 is transferred by the wafer transfer robot 13 to the analysis measurement chamber 11a in the apparatus main body 11.
Then, X-ray analysis is performed in the apparatus main body 11.

As described above, in this embodiment, the cassette holder 12 and the wafer transfer robot 13 are housed in the box 21 having high cleanliness. Therefore, the cassette table 12 and the wafer transfer robot 13 are not exposed to the atmosphere in the clean room. Therefore, during the analysis of each wafer 15, the wafer 15 is not contaminated by the atmosphere in the clean room while the cassette 14 mounting each wafer 15 is placed on the cassette stand 12. Furthermore, the atmosphere inside the box 21 is set to 10
By using 0% nitrogen gas, it is possible to prevent an oxide film from being formed on the surface of the wafer 15 by oxygen in the air.

The present invention is not limited to the above embodiment, and for example, the gas fed into the box 21 may be replaced with another inert gas such as argon gas instead of nitrogen gas.

The gas fed into the box 21 may be ordinary air. However, in this case, it is not possible to prevent the formation of an oxide film on the surface of the wafer 15 by oxygen in the air.

Furthermore, this embodiment may be applied to the embodiment shown in FIG. By the way, in the manufacturing process of semiconductor wafers, a wafer washing process is indispensable. Conventionally,
A water washing apparatus used in the water washing process of the wafer is disclosed in Japanese Patent Laid-Open No. 3-296218.

By the way, before the wafer washing process,
Generally, a cleaning process with a predetermined chemical solution is performed. And, in order to shorten the time required for the production and to carry out the production process rationally, the washing tank for the washing process is usually installed adjacent to the cleaning device using the chemical solution.

However, when the water washing tank is adjacent to the cleaning device using the chemical liquid, the wafers that have been taken out of the water washing tank after the water washing process are carelessly contaminated by the atmosphere of the chemical liquid leaking from the cleaning device using the chemical liquid. There was a problem.

Therefore, the applicant of the present invention has proposed a new water washing apparatus for solving this problem. FIG. 3 is a cross-sectional view schematically showing a vertical cross section of the water washing device.

A pipe 42 for introducing ultrapure water into the water washing tank 41 is attached to the bottom of the water washing tank 41 formed by processing a fluororesin plate such as Teflon. A plurality of wafers 44 are stored in the wafer carrier 43. A plurality of gas blowing devices 45 are provided so as to surround the upper opening 41a of the washing tank 41. The gas blowing device 45 includes a gas introduction pipe 46 and an air filter 47. The pressurized nitrogen gas is fed into the gas introduction pipe 46. Then, the nitrogen gas from the gas introduction pipe 46 is blown out through the air filter 47 onto the upper opening 41a of the washing tank 41. Since a plurality of gas blowing devices 45 are provided, a turbulent flow occurs on the upper opening 41a of the washing tank 41, and the upper opening 41a has a positive pressure with respect to the surrounding atmosphere.

Next, a method of using the water washing device thus constructed will be described. First, the wafer 44, which has undergone the cleaning process using a predetermined chemical solution, is placed in the water washing tank 41 together with the wafer carrier 43. Then, when ultrapure water is introduced from the pipe 42, the ultrapure water flows from the bottom to the top in the washing tank 41 to wash the wafer 44, and then the upper opening 4 of the washing tank 41.
1a overflows and is discharged.

At this time, nitrogen gas is blown from the gas blowing device 45 onto the upper opening 41a of the washing tank 41,
The upper opening 41a is made to have a positive pressure with respect to the surrounding atmosphere. Then, the atmosphere of the chemical liquid leaking from the chemical liquid cleaning device (not shown) provided adjacent to the water washing tank 41 is
It will not enter the upper opening 41a of the washing tank 41,
The wafer 44 pulled up from the water washing tank 41 is no longer contaminated.

The gas blown out from the gas blowing device 45 may be replaced with an inert gas such as argon or air. In addition, the upper opening 41a of the washing tank 41 is surrounded by a frame,
By providing the gas blowing device 45 in the frame, the action of positively pressing the upper opening 41a with respect to the surrounding atmosphere can be further enhanced.

[0047]

As described above in detail, according to the present invention, according to the invention of claim 1, there is provided a total reflection fluorescent X-ray analyzer having a highly accurate and simple structure and an inexpensive surface inspection system. It has an excellent effect that it can be provided.

Further, the invention according to claim 2 has an excellent effect that it is possible to provide a total reflection fluorescent X-ray analyzer capable of preventing inadvertent contamination of a wafer in the process of analysis.

[Brief description of drawings]

FIG. 1 is an external view showing an embodiment in which the invention according to claim 1 is embodied.

FIG. 2 is a schematic view showing an embodiment embodying the invention described in claim 2.

FIG. 3 is a cross-sectional view schematically showing a vertical cross section of a new water washing device proposed by the present applicant.

[Explanation of symbols]

 15 Semiconductor Wafer 17 Optical Microscope 18a Moving Scale 21 Box 22 Piping 23 Air Filter 24 Exhaust Pipe

Claims (2)

[Claims] 1. A member having an optically smooth surface that totally reflects X-rays irradiated at a low irradiation angle, and coordinates are set on the optically smooth surface of the member to position the member. A total reflection X-ray fluorescence analyzer, which is provided with a positioning means for performing the above and an optical microscope. 2. A total reflection apparatus comprising: a box for covering the total reflection X-ray fluorescence analyzer, a pressurizing means for pressurizing the inside of the box, and an air cleaning means for enhancing the cleanliness inside the box. X-ray fluorescence analyzer.