JP6979922B2 - Electronic balance and wafer weight measurement method - Google Patents

Description

The present invention relates to an electronic balance.

The electronic balance is suitable for precise weight measurement of a sample (see, for example, Patent Document 1). Electronic balances are used to measure wafer film thickness by gravimetric methods in semiconductor wafer processes.

Registered Utility Model No. 3136080

When setting the wafer on the electronic balance to measure the weight of the wafer (sample), the vacuum tweezers and the weighing pan interfere with each other. Therefore, it is difficult to set and take out the wafer.

Also, during weight measurement, the wafer is placed on a weighing pan. Therefore, the mounting surface of the wafer that comes into contact with the mounting surface of the weighing pan is scratched.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electronic balance that is suitable for sample measurement and can suppress deterioration of sample quality after measurement. ..

Electronic balance according to the present invention comprises a load cell, a weighing pan connected to wafer can be placed in and and a load cell, a. The weighing pan is a flat plate , at least one recess in which a part of the side surface of the flat plate is recessed inside the flat plate, and an installation surface provided along the outer peripheral portion of the upper surface of the flat plate, from the upper surface of the flat plate. Also includes an upper mounting surface, including a protrusion on which the wafer can be placed. The at least one recess penetrates the upper and lower surfaces of the flat plate so that the back surface of the wafer placed on the installation surface is exposed from the at least one recess.

According to the present invention, it is possible to provide an electronic balance that is suitable for sample measurement and suppresses deterioration of sample quality after measurement.

The objects, features, aspects, and advantages of the present invention will be made clearer by the following detailed description and accompanying drawings.

It is a figure which shows the structure of the electronic balance in Embodiment 1. FIG. It is a perspective view which shows the structure of the weighing dish of the electronic balance in Embodiment 1. FIG. It is a side view which shows the structure of the weighing dish of the electronic balance in Embodiment 1. FIG. It is a perspective view which shows the structure of the electronic balance in the modification of Embodiment 1. FIG. It is a side view which shows the structure of the electronic balance in the modification of Embodiment 1. FIG. It is a perspective view which shows the structure of the weighing dish of the electronic balance in Embodiment 2. FIG. It is a side view which shows the structure of the weighing dish of the electronic balance in Embodiment 2. FIG.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of an electronic balance 1 according to the first embodiment.

The electronic balance 1 has a load cell 2, a housing 3, and a weighing pan 4.

The load cell 2 has a function of measuring the weight of the sample placed on the weighing pan 4. In Embodiment 1, the sample is a wafer 5.

The housing 3 is provided so as to surround the load cell 2.

The weighing pan 4 is connected to the load cell 2 and is provided above the housing 3. The weighing pan 4 has a flat plate 4A on which the wafer 5 can be placed.

FIG. 2 is a perspective view showing the configuration of the weighing pan 4 included in the electronic balance 1 according to the first embodiment. The weighing pan 4 has at least one recess 4B in which a part of the side surface of the flat plate 4A is recessed inside the flat plate 4A. In the first embodiment, the weighing pan 4 has two recesses 4B. The two recesses 4B are provided so as to face each other in the plane of the flat plate 4A.

FIG. 3 is a side view showing the configuration of the weighing pan 4 included in the electronic balance 1 according to the first embodiment. The weighing pan 4 has a convex portion 4C on which the wafer 5 can be placed. The convex portion 4C has an installation surface 4D. The installation surface 4D is a surface provided along the outer peripheral portion of the upper surface of the flat plate 4A, and is a surface above the upper surface of the flat plate 4A. The wafer 5 is placed in contact with the installation surface 4D.

When the weighing pan 4 of the electronic balance 1 has the recess 4B, the wafer 5 held in the vacuum tweezers 6 is set in the electronic balance 1, or the wafer 5 set in the electronic balance 1 is set in the vacuum tweezers 6. The vacuum tweezers 6 and the weighing pan 4 do not interfere with each other when taken out. Therefore, the electronic balance 1 in the first embodiment improves the work efficiency of setting and taking out the wafer 5.

Further, since the weighing pan 4 of the electronic balance 1 has the convex portion 4C, the contact area between the wafer 5 and the weighing pan 4 is reduced. Therefore, the electronic balance 1 in the first embodiment reduces the possibility that the wafer 5 is scratched.

(Variation example of Embodiment 1)
FIG. 4 is a perspective view showing the configuration of the electronic balance 1 in the modified example of the first embodiment. FIG. 5 is a side view showing the configuration of the electronic balance 1 in the modified example of the first embodiment.

In addition to the configuration shown in the first embodiment, the electronic balance 1 has a configuration in which a protective sheet 7 is attached on the installation surface 4D of the weighing pan 4.

With such a configuration, the electronic balance 1 can further reduce the possibility of scratches due to contact between the wafer 5 and the installation surface 4D.

<Embodiment 2>
The electronic balance according to the second embodiment has the same configuration as that of the first embodiment shown in FIG. 1 except for the weighing pan 4.

FIG. 6 is a perspective view showing the configuration of the weighing pan 4 of the electronic balance according to the second embodiment. FIG. 7 is a side view showing the configuration of the weighing pan 4 of the electronic balance according to the second embodiment.

The weighing pan 4 each has at least four protrusions 8 provided on the upper surface of the flat plate 4A. In the second embodiment, the weighing pan 4 has four protrusions 8. Each protrusion 8 has a columnar shape. In the weighing pan 4, the wafer 5 can be placed on the four protrusions 8. That is, the wafer 5 is placed in contact with the upper surface of the protrusion 8. As a result, each protrusion 8 supports the wafer 5. Further, each protrusion 8 contains a soft resin as a constituent material.

With such a configuration, a space is created between the wafer 5 supported by each protrusion 8 and the flat plate 4A of the weighing pan 4. When the wafer 5 held in the vacuum tweezers 6 is set on the electronic balance, or when the wafer 5 set in the electronic balance is taken out by the vacuum tweezers 6, the space is filled with the vacuum tweezers 6 and the weighing pan 4. Prevent interference. Therefore, the electronic balance according to the second embodiment improves the work efficiency of setting and taking out the wafer 5.

Further, since each protrusion 8 is made of a soft resin, the possibility that the wafer 5 is scratched is reduced.

In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

Although the present invention has been described in detail, the above description is exemplary in all embodiments and the present invention is not limited thereto. It is understood that innumerable variations not illustrated can be assumed without departing from the scope of the present invention.

1 Electronic balance, 2 load cell, 4 weighing pan, 4A flat plate, 4B concave, 4C convex, 4D installation surface, 5 wafer, 7 protective sheet, 8 protrusion.

Claims (3)

Load cell and
A weighing pan on which a wafer can be placed and connected to the load cell is provided.
The weighing pan is
Flat plate and
With at least one recess in which a part of the side surface of the flat plate is recessed inside the flat plate,
An installation surface provided along the outer peripheral portion of the upper surface of the flat plate, including the installation surface above the upper surface of the flat plate, and a convex portion on which the wafer can be placed. , Including
The at least one recess is an electronic balance that penetrates the upper and lower surfaces of the flat plate so that the back surface of the wafer placed on the installation surface is exposed from the at least one recess. The weighing pan is
The electronic balance according to claim 1, further comprising a protective sheet provided on the installation surface of the convex portion. The method for measuring the weight of a wafer by the electronic balance according to claim 1 or 2.
The vacuum tweezers holding the back surface of the wafer are removed from the wafer through the concave portion of the weighing pan, and the wafer is placed on the mounting surface of the convex portion of the weighing pan.
The weight of the wafer is measured by the load cell,
Through the recess of the weighing pan, the said rear surface of the wafer held by the vacuum tweezers, removing said wafer from said setting surface of the convex portion, the weight measurement method of a wafer.

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