JP3399671B2 - Sample preparation apparatus for total reflection X-ray fluorescence spectrometer and method of coagulating contamination - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample preparation apparatus for automatically preparing a measurement sample capable of highly sensitive total reflection X-ray fluorescence analysis.

[0002]

2. Description of the Related Art In a semiconductor process line, it is important to control heavy metal contamination (hereinafter referred to as "contamination") on a wafer. Generally, the contamination on the wafer surface is analyzed by the total reflection fluorescent X-ray, but the total reflection fluorescent X-ray has a drawback of low sensitivity. Therefore, when high-sensitivity analysis is required, an aqueous solution of hydrogen fluoride (HF) (hereinafter,
Drop a few drops of "hydrofluoric acid" to remove the hydrofluoric acid oxide film (S
iO ₂ ) A hydrofluoric acid droplet is rolled on the entire surface of the wafer by utilizing the etching characteristics, so that the contaminants are aggregated in the center of the wafer, and after the hydrofluoric acid is dried, only one point is analyzed, which is called a hydrofluoric acid condensation method. Become. Conventionally, a series of operations such as dropping of hydrofluoric acid, rolling, and the like have been performed manually by a person adsorbing a wafer with vacuum tweezers.

[0003]

However, in the conventional measurement, since a person manually prepares a sample, there are various problems described below. That is, there is a possibility that contaminants (for example, K, Ca, etc.) generated from the human body may adhere to the wafer, and accurate analysis of the sample may not be performed. Further, since skill is required to roll the hydrofluoric acid droplets, there is a problem that the reproducibility of the analysis is lowered due to the difference in the agglomeration rate depending on the operator. Furthermore, since hydrofluoric acid is a powerful drug, there has been concern about its danger to the human body. The present invention has been made in view of the above circumstances, provides a sample preparation apparatus that can automatically prepare a sample without human intervention, prevent contamination from the human body, stabilize hydrofluoric acid aggregation rate, And to improve safety for the human body.

[0004]

In order to achieve the above object, a sample preparation apparatus for a total reflection X-ray fluorescence analyzer according to the present invention uses hydrofluoric acid to automatically make contamination on the wafer surface centered on the wafer. A sample preparation apparatus for a total reflection X-ray fluorescence analyzer for aggregating into a wafer chuck, which adsorbs a wafer and is rotatable about the same central axis as the wafer, and hydrofluoric acid is dripped onto the wafer adsorbed on the wafer chuck. A nozzle and a rod which is disposed with a gap on the wafer surface and which contacts the dropped hydrofluoric acid droplet on the wafer and moves the tip in the diameter direction of the wafer in synchronization with the rotation of the wafer chuck. Comprising the nozzle
The rod moves the hydrofluoric acid drop on the wafer dropped from
It is characterized in that it is configured to .
A method of using hydrofluoric acid to agglomerate the contamination on the wafer surface includes a step of dropping hydrofluoric acid on the wafer and a step of moving the hydrofluoric acid on the wafer surface.
In addition, the dropping step is performed using a nozzle.
And the moving step is performed using a rod,
The pad maintains a gap between the tip and the wafer surface.
And is moved toward the center of the wafer .

[0005]

[Operation] After the hydrofluoric acid is dropped onto the wafer by the nozzle,
The rod is moved to the location where hydrofluoric acid is dropped, and the tip of the rod comes into contact with the hydrofluoric acid droplet. The rod is moved toward the center of the wafer while maintaining a gap between the tip and the wafer surface, and at the same time, the wafer chuck is rotated in synchronization with the moving speed of the rod. As a result, the hydrofluoric acid droplets are dragged by the tip of the rod and roll toward the center in a spiral shape on the wafer surface.
As the rod is moved, it follows the same trajectory and returns to the initial dropping position again. This operation is repeated several times, the hydrofluoric acid passes evenly over the wafer surface, and the contaminants are all gathered together with the hydrofluoric acid in the center of the wafer.

[0006]

EXAMPLES Preferred examples of a sample preparation apparatus for a total reflection X-ray fluorescence analyzer according to the present invention (hereinafter referred to as “sample preparation apparatus”) and a contamination aggregation method using the same will be described with reference to the drawings. To do. 1 is a perspective view of the sample preparation apparatus of the present invention, FIG. 2 is a plan view of the sample preparation apparatus of the present invention, and FIG. 3 is a front view of the sample preparation apparatus of the present invention. The nozzle and wafer chuck positions in FIG. 3 represent home position positions. A container 5 made of Teflon for storing hydrofluoric acid is arranged on the workbench surface 3 of the apparatus main body 1,
The container 5 is set at a fixed position by a jig (not shown) provided in the apparatus body 1. A nozzle 7 for sucking hydrofluoric acid from the container 5 and dropping the sucked hydrofluoric acid onto the wafer is supported by the arm 9 in the apparatus main body 1. The arm 9 is provided with a nozzle driving unit 11 provided at a rear portion of the apparatus main body 1.
Thus, the work table surface 3 can be moved up and down (direction of arrow a) and left and right (direction of arrow b).

A disk-shaped wafer chuck 1 is provided on the work surface 3
3 is provided, and the central axis of the wafer chuck 13 is the nozzle 7
It is located on the moving straight line. Wafer chuck 13
The wafer centering drive unit 15 (see FIG. 3) can be moved up and down in the vertical direction and can be rotated. A centering piece 17 is provided on the work table surface 3 so as to surround the wafer chuck 13. The centering piece 17 has a plurality of annular steps having different inner diameters and formed in a multi-step manner at the same center. Centering piece 1
Reference numeral 7 is for centering the wafer before adsorbing the wafer on the wafer chuck 13. For example, it is possible to automatically perform centering on a 4-inch, 5-inch, or 6-inch wafer. It is possible. The centering piece 17 is, as shown in FIG.
Alternatively, the arcuate step portions may be arranged so as to face each other with the center portion 3 being the center.

A rod 19 for gathering the hydrofluoric acid dropped on the wafer to the center of the wafer is supported by an arm 21 on the apparatus main body 1, and the arm 21 moves vertically (in the direction of arrow a) with respect to the workbench surface 3 (right and left). It can be moved in the direction of arrow b). The rod 19 is moved in the direction of arrow b on a straight line passing through the center of the wafer centered by the centering piece 17. A pure water tank 23 for cleaning the tip portion of the rod 19 is provided on the work table surface 3. The pure water tank 23 is kept clean by removing pure water from the water supply port 25 while the apparatus is in use. It is supposed to be. An operation panel 27 is provided on the front surface of the apparatus main body 1, and the operation panel 27 enables operation of each of the drive units described above.

A plurality of linear exhaust ports 29 are provided in the rear portion of the work table surface 3 at predetermined intervals in the left-right direction of the work table surface 3, and the exhaust ports 29 suck and remove hydrogen fluoride generated during use of the apparatus. Although illustration is omitted, the apparatus body 1 is housed in a clean bench (class 10 specification) provided with a PVC door for the safety of human body against hydrogen fluoride. Device body 1, container 5, nozzle 7, arms 9, 2
1, a wafer chuck 13, a centering piece 17, a rod 19, and a deionized water tank 23 are main elements, and a sample preparation apparatus 31 is configured.

Sample preparation device 3 having the above-mentioned configuration
The operation of No. 1 will be described with reference to FIGS. 4 is a plan view for explaining the initial hydrofluoric acid droplet rolling situation, FIG. 5 is a side view for FIG. 4, FIG. 6 is a plan view for explaining the hydrofluoric acid droplet rolling situation for the second time and thereafter, and FIG. 7 is a side view for FIG. It is a figure. First, an operator sets the wafer 33 on the wafer chuck 13. When “start” is designated on the operation panel 27, the wafer chuck 13 sucks the wafer 33 after the centering piece 17 centers the wafer 33. Next, the nozzle 7
Sucks up a few drops (0.5 cc to 1 cc) of hydrofluoric acid from the container 5 and drops it at a point A located within a few mm from the outer peripheral portion of the wafer 33. This operation is performed at least twice. The first dropping is to dissolve the oxide film on the wafer surface and to make the hydrofluoric acid dropped after the second dropping into particles by the surface tension without spreading.

Next, the rod 19 is moved to the place where the hydrofluoric acid is dropped, and the tip of the rod 19 is brought into contact with the hydrofluoric acid drop 35. The rod 19 keeps the gap between the tip of the rod 19 and the wafer surface to be about 0.5 mm, and
Moving towards the center of. At this time, as the wafer chuck 13 rotates in synchronization with the moving speed of the rod 19, the hydrofluoric acid droplet 35 is dragged by the tip of the rod 19 to form a spiral B shape on the wafer surface toward the center C. Roll around. The hydrofluoric acid droplet 35 that has reached the center C follows the same trajectory as the rod 19 is moved, and returns to the point A again.

The hydrofluoric acid droplet 35 returning to the point A is again dragged toward the center C. At that time, the oxide film on the wafer surface is already dissolved in the hydrofluoric acid droplets 35, and the hydrofluoric acid droplets 35 have the shapes shown in FIGS. 6 and 7. That is, when an oxide film is present, the hydrofluoric acid droplet 35 is compatible with the oxide film, and the hydrofluoric acid droplet 35 has a flat streamline (width 6 mm, total length 10 to 13 mm) shown in FIGS. 4 and 5. On the other hand, since the hydrofluoric acid droplets 35 are not compatible with the silicon surface after being taken into the hydrofluoric acid droplets 35 by melting the oxide film, the original surface tension causes the rounded grain shape shown in FIGS. 6 and 7. (Width 6 mm, total length 8-10 mm, height 1-2 mm). Rod 1 in which hydrofluoric acid droplet 35 is reciprocated multiple times
9 is finally stopped at the wafer center C, and the hydrofluoric acid droplet 3
Evacuate upward with 5 left.

By repeating the dropping of hydrofluoric acid by the nozzle 7 and the operation of moving the rod 19 toward the wafer center C several times, the hydrofluoric acid passes evenly over the wafer surface, and the contaminants together with the hydrofluoric acid are on the wafer. All are gathered together in center C. When the sample preparation is completed, the tip portion of the rod 19 is automatically cleaned in the pure water tank 23 in preparation for the next sample preparation.

[0014]

As described [Effect Invention above in detail, total reflection X-ray fluorescence analysis dexterity sample preparing apparatus and configuration according to the present invention
According to the Tami aggregation method , a wafer chuck that attracts a wafer and is rotated about the same central axis as the wafer, a nozzle that drops hydrofluoric acid onto the wafer, and a wafer chuck that contacts the dropped hydrofluoric acid drops on the wafer Since it is equipped with a rod that moves in the diameter direction of the wafer in synchronism with the rotation of the wafer, the hydrofluoric acid droplets are dragged by the tip of the rod and roll toward the center in a spiral shape on the wafer surface. Can be collected together with the hydrofluoric acid at the center of the wafer. As a result, it is possible to automatically prepare a sample without human intervention, prevent contamination from the human body, and stabilize the hydrofluoric acid agglomeration rate.
The safety to the human body can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a sample manufacturing apparatus of the present invention.

FIG. 2 is a plan view of a sample manufacturing apparatus of the present invention.

FIG. 3 is a front view of the sample manufacturing apparatus of the present invention.

FIG. 4 is a plan view illustrating the initial rolling condition of hydrofluoric acid droplets.

FIG. 5 is a side view of FIG.

FIG. 6 is a plan view illustrating a hydrofluoric acid droplet rolling condition after the second time.

FIG. 7 is a side view of FIG.

[Explanation of symbols]

1 device body 3 Work surface 5 containers 7 nozzles 9 arms 13 Wafer chuck 17 Centering coma 19 rod 31 Sample preparation device for total internal reflection X-ray fluorescence analyzer 33 wafers 35 hydrofluoric acid drops C wafer center

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-241959 (JP, A) JP-A-6-249769 (JP, A) JP-A-2-28533 (JP, A) JP-A-4- 225526 (JP, A) JP 6-132376 (JP, A) JP 7-176580 (JP, A) Patent 3298089 (JP, B2) JP 6-63943 (JP, B2) JP 6 -25717 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 1/00-1/44 G01N 23/00-23/227 G01T 1/00-1/40 H01L 21 / 66 JISST file (JOIS)

Claims (5)

(57) [Claims] 1. A sample preparation apparatus for a total reflection X-ray fluorescence analyzer, which uses hydrofluoric acid to automatically agglomerate the contamination on the wafer surface to the center of the wafer. A wafer chuck rotatable about an axis, a nozzle for dropping hydrofluoric acid onto the wafer attracted to the wafer chuck, a tip having a gap on the wafer surface, and the hydrofluoric acid on the dropped wafer. A rod that moves in the diameter direction of the wafer in synchronization with the rotation of the wafer chuck, the rod contacting the droplet and moving the hydrofluoric acid droplet on the wafer dropped from the nozzle.
A sample preparation device for a total reflection X-ray fluorescence analyzer, characterized in that the head is configured to move . 2. A pure water tank for cleaning the tip portion of the rod
The sample preparation device for a total reflection fluorescent X-ray analyzer according to claim 1, wherein the sample preparation device is provided. 3. Contamination on the wafer surface is reduced.
To collect hydrofluoric acid from the nozzle
And the movement of hydrofluoric acid droplets by the rod are repeated several times.
The sample preparation device for a total reflection X-ray fluorescence analyzer according to claim 1 or 2, characterized in that 4. A contour on a wafer surface using hydrofluoric acid.
A method for aggregating terminations , which comprises a step of dropping hydrofluoric acid onto a wafer and a step of moving the hydrofluoric acid on the wafer surface.
In addition, the dropping step is performed using a nozzle, and the moving work is performed.
A rod is used to maintain the gap between the tip and the wafer surface.
While Chi, be moved towards the center of the wafer
A method for aggregating contamination characterized by: 5. The rod faces toward the center of the wafer.
After being moved, it returns to the dropping position again.
The contamination according to claim 4, characterized in that
Aggregation method.