JP4204434B2 - Method and apparatus for recovering object to be measured around wafer - Google Patents

Description

  The present invention relates to a method and an apparatus for recovering an object to be measured which is a trace amount of metal impurities present on a peripheral portion of a wafer (substrate), particularly on an end face (bevel) of the wafer.

  Conventionally, when analyzing a small amount of metal impurities adhering to the surface of a silicon wafer, such as aluminum, iron, nickel, zinc (object to be measured), as a pretreatment device, for example, vapor phase decomposition (VPD: Vapor Phase Decomposition) A recovery apparatus using the apparatus is known. First, a reactive gas such as hydrogen fluoride is introduced to the wafer surface by the vapor phase decomposition apparatus, the oxide film on the wafer surface is dissolved and the object to be measured is dissolved, and then dried and held on the wafer surface. Is done. Then, the liquid to be measured is held on the wafer surface by horizontally moving it on the wafer surface while holding a liquid drop such as a hydrofluoric acid solution dropped on the wafer surface with a holder. The collecting device for collecting the wafer surface is a horizontal type in which the wafer is horizontally set.

  On the other hand, the peripheral part of the wafer, that is, the edge part including the end face (bevel) of the wafer and the front and back surfaces near the end face, is easily contaminated by the transfer device when handling the wafer, and needs to be analyzed separately from the wafer surface. Is high.

As a device for collecting the object to be measured at the periphery of the wafer, hold the wafer perpendicular to the rotating body, and while rotating vertically, immerse the object to be measured in the chemical solution in the immersion container over the entire periphery of the wafer periphery. A recovery device (method) for recovery is known (for example, Patent Document 1). In order to immerse the entire circumference of the periphery of the wafer in the chemical solution in the immersion container, the wafer is placed in a vertical orientation and is a vertical collection device (method) that rotates.
JP-A-11-204604

  However, there are the following problems in the above-mentioned vertical collection device. That is, (a) mechanical parts such as a wafer chuck mechanism and a rotation mechanism are present on the upper part of the chemical solution, which causes contamination of the chemical solution. (B) The structure and handling are complicated, and more chemicals are required. (C) When collecting both the wafer surface and the peripheral portion, if the horizontal-type wafer surface recovery device and the vertical-type wafer peripheral portion recovery device are placed side by side, the size of the device increases. (D) In the vertical type, there is a risk of dropping the wafer because the wafer is rotated vertically.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for recovering an object to be measured around a wafer, which solves the above problems and has a simple structure and can be recovered easily and stably.

    In order to achieve the above-described object, the method and apparatus for recovering an object to be measured at the periphery of a wafer according to the present invention holds a wafer so that the wafer can be rotated horizontally by a wafer stage, and a droplet of the recovered recovery liquid holds the recovery liquid. While being held on the table and rotating the wafer horizontally, the peripheral part of the wafer is brought into contact with the droplets on the recovery liquid holding table, and the object to be measured existing on the peripheral part of the wafer is recovered.

  According to this configuration, while rotating the wafer horizontally, the wafer peripheral part is brought into contact with the droplets on the recovery liquid holding table, and the measurement object existing in the wafer peripheral part is recovered. Instead of placing the wafer vertically and immersing the periphery of the wafer in the chemical solution in the immersion vessel, the wafer is placed horizontally and the periphery of the wafer is brought into contact with the liquid droplets on the recovery liquid holding table. There is no problem of chemical contamination or complicated structure and handling, the structure is simple, and the wafer periphery can be recovered easily and stably.

  Preferably, the recovery liquid holding base is moved in the direction of the wafer base so as to change the contact area of the peripheral portion of the wafer that contacts the droplets of the recovery liquid. Therefore, it is possible to cope with both the case where the object to be measured existing only on the end face of the wafer is analyzed and the case where the object to be measured existing on the front and back surfaces near the end face and the end face is analyzed. Preferably, the object to be measured is a metal impurity.

  Preferably, the droplet of the recovered liquid is held by a holder that is sandwiched between the recovered liquid holding table and the recovered liquid holding table. Therefore, even if the droplet of the recovered liquid receives the rotational force at the periphery of the wafer, it can be held so as not to move more reliably.

  Preferably, the measurement object existing on the wafer surface is recovered by moving the droplet of the recovery liquid dropped on the wafer surface on the wafer surface while being held by a holder sandwiched between the wafer surface. Therefore, when collecting both the wafer surface and the peripheral part, the wafer peripheral part recovery device is horizontally placed like the wafer surface recovery apparatus, so that the conventional wafer surface recovery can be performed without increasing the size of the apparatus. Can be shared with the device.

  The analysis method (analysis system) according to the present invention comprises the recovery method (apparatus) and an analysis method (apparatus) such as a fluorescent X-ray analysis method (apparatus) for analyzing the recovered object to be measured. I have.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a device for collecting an object to be measured at a wafer peripheral portion 1a according to an embodiment of the present invention. The object to be measured is a metal impurity such as aluminum, iron, nickel, or zinc. The recovery apparatus includes a wafer table 2 that holds the wafer 1 horizontally, a rotation mechanism 12 that rotates the wafer table 2 horizontally, a recovery liquid holding table 4 that holds droplets 3 of the dropped recovery liquid, and a moving mechanism 14. I have.

  The recovered liquid is, for example, a hydrofluoric acid solution. For example, 100 μl (0.1 cc) of recovered liquid is dropped on the recovered liquid holding table 4. The recovery liquid holding table 4 is made of a hydrophobic material such as PTFE (polytetrafluoroethylene, registered trademark Teflon). When the recovery liquid is dropped, the recovery liquid holding base 4 drops droplets ( Liquid particles 3).

  For example, the moving mechanism 14 is configured so that the recovery liquid holding table 4 and the center of the recovery liquid holding table 4 and the wafer are viewed in a plan view so as to change the contact area of the wafer peripheral portion 1a that contacts the droplet 3 of the recovery liquid. It is moved in the direction of the wafer table 2 on a straight line connecting the centers of the tables 2. This moving mechanism 14 analyzes the object to be measured existing only on the end face of the wafer 1 in the wafer peripheral portion 1a, and the object to be measured present on the front and back surfaces of the wafer 1 in the vicinity of the end face. Both cases (dashed lines) can be handled. In addition, you may make it move the collection | recovery liquid holding stand 4 manually without providing the moving mechanism 14 especially.

  In this recovery apparatus, the wafer 1 is held by the wafer stage 2 so as to be horizontally rotatable, the dropped recovery liquid droplet 3 is held on the recovery liquid holding stage 4, and the wafer 1 is rotated by the rotating mechanism 12 of the wafer stage 2. The wafer peripheral portion 1a is brought into contact with the liquid droplet 3 of the recovered liquid by the moving mechanism 14 of the recovered liquid holding base 4 while the apparatus is horizontally rotated, and the object to be measured existing in the wafer peripheral portion 1a is recovered.

  The analysis system according to the present invention includes the recovery device of FIG. 1 and an analysis device such as a total reflection X-ray fluorescence analysis device shown in FIG. 4 for analyzing the recovered object to be measured. The total reflection fluorescent X-ray analyzer measures the primary X-ray B1 obtained by monochromatizing the X-ray from the X-ray tube 21 with the spectroscopic element 22 at a small incident angle α (for example, about 0.05 ° to 0.20 °). The light is incident on an object, and the intensity of the fluorescent X-ray B2 generated from the object to be measured is detected by the detector 23. Based on the detected value, elemental analysis of the object to be measured is performed.

  Next, the operation of this analysis system will be described. First, in the collection apparatus of FIG. 1, (1) the wafer 1 is set horizontally on the wafer table 2. (2) The recovered liquid is dropped on the recovered liquid holding table 4 to hold the droplet 3 on the recovered liquid holding table 4. (3) The recovered liquid holding table 4 is moved by the moving mechanism 14 to bring the wafer peripheral portion 1a into contact with the recovered liquid droplet 3. (4) The wafer stage 2 is rotated by the rotation mechanism 12, and the wafer 1 is rotated, for example, 1 to 2 times. (5) The droplet 3 in which the object to be measured in the wafer peripheral portion 1a is dissolved is sucked up by, for example, a nozzle and collected. Thus, the object to be measured on the wafer peripheral portion 1a is recovered.

  Next, (6) the object to be measured is collected and then dried and held on the wafer 1. (7) The wafer 1 holding the object to be measured is transferred to a total reflection X-ray fluorescence analyzer, and the object to be measured is subjected to total reflection X-ray fluorescence analysis. In (6), the object to be measured may be held on a new wafer 1.

  As a result, the present recovery apparatus makes the wafer peripheral portion 1a contact the droplet 3 on the recovery liquid holding stand 4 while rotating the wafer 1 horizontally, and recovers the measurement object existing in the wafer peripheral portion 1a. Therefore, as in the prior art, the wafer periphery is not vertically immersed and the wafer periphery is immersed in the chemical solution in the immersion container. Therefore, unlike the conventional vertical type, there is no problem of chemical contamination or complicated structure and handling, and the structure is simple, and the wafer peripheral portion 1a can be recovered easily and stably. .

  As shown in FIG. 2, a holder 5 that holds the droplet 3 so as to be sandwiched between the recovered liquid holding base 4 during the rotation of the wafer may be provided. The holder 5 is attached to the arm 7, for example, and can move in the horizontal and vertical directions. The holder 5 is made of, for example, a PTFE nozzle, and drops the recovery liquid and holds the liquid droplet 3 between the tip and the recovery liquid holding stand 4. Therefore, even when the droplet 3 of the recovery liquid receives the rotational force of the wafer peripheral portion 1a during the rotation of the wafer, it can be held so as not to move as it is.

  In this embodiment, in order to recover the wafer peripheral portion 1a, the wafer peripheral portion 1a is immediately brought into contact with the droplet 3 and recovered. However, when vapor phase decomposition is necessary, the wafer peripheral portion 1a is vapor-phase decomposed. Later, it is brought into contact with the droplet 3 and collected.

  In this analysis system, the collected object to be measured is analyzed by a total reflection X-ray fluorescence analyzer. However, the present invention is not limited to this, and other fluorescent X-ray analyzers may be used. An absorption analyzer or the like may be used. When an atomic absorption analyzer is used, the collected liquid is analyzed as it is without being dried.

  FIG. 3 is a configuration diagram showing a device for collecting an object to be measured of the wafer 1 according to another embodiment. The recovery device of the above embodiment has a single function of recovering only the wafer peripheral portion 1a. However, this recovery device recovers both the wafer peripheral portion 1a and the surface 1b, and is a well-known horizontal type. The apparatus for recovering the object to be measured on the wafer surface 1b and the apparatus for recovering the object to be measured on the laterally placed wafer peripheral portion 1a are provided. The configuration and operation of the device for collecting the object to be measured at the wafer peripheral portion 1a are the same as described above.

  The apparatus for collecting an object to be measured on the wafer surface 1b moves the wafer 3 on the wafer surface 1b while holding the droplet 3 of the collected liquid dropped on the surface of the wafer 1 with the holder 5, and the object to be measured present on the wafer surface 1b. The gas phase decomposition apparatus and the sample recovery apparatus are provided. The vapor phase decomposition apparatus is a reactive gas such as hydrogen fluoride in a decomposition chamber (not shown) in which a measurement object existing on the wafer surface 1b or a surface of a film formed on the wafer surface 1b or a measurement object existing in the film is not shown. After being dissolved, it is dried and held on the wafer surface 1b. Then, the sample recovery apparatus uses the arm 7 to hold the droplet 3 in which the hydrofluoric acid solution is dropped from the holder 5 near the outer periphery of the wafer 1 while holding the wafer 1 horizontally while holding the wafer 5 with the arm 7. The object to be measured held on the wafer surface 1b is collected. In addition, the dropping position of the recovered liquid and the movement path of the holder 5 are not limited to this.

  Both the wafer peripheral portion 1a recovery device and the wafer surface 1b recovery device are of the horizontal type in which the wafer 1 is set horizontally, and share the wafer table 2, the rotation mechanism 12 and / or the holder 5 (arm 7). Is.

  As a result, when both the wafer peripheral portion 1a and the surface 1b are recovered, the size of the apparatus is increased by making the recovery device for the wafer peripheral portion 1a a horizontal type like the conventional recovery device for the wafer surface 1b. It is possible to share the recovery device for the wafer peripheral portion 1a and the conventional recovery device for the wafer surface 1b.

It is a block diagram which shows the collection | recovery apparatus of the to-be-measured object of the wafer peripheral part which concerns on one Embodiment of this invention. It is a schematic block diagram which shows the other example of the collection | recovery apparatus of FIG. It is a block diagram which shows the collection | recovery apparatus of the to-be-measured object of the wafer peripheral part which concerns on other embodiment. It is a block diagram which shows a total reflection fluorescent-X-ray-analysis apparatus.

Explanation of symbols

1: Wafer 1a: Wafer peripheral portion 1b: Wafer surface 2: Wafer table 3: Droplet 4: Recovery liquid holding table 5: Holder 12: Rotating mechanism 14: Moving mechanism

Claims (12)

A first step of holding the wafer horizontally and rotatably on the wafer stage;
A second step of holding the dropped recovery liquid droplets by a holder sandwiched between the recovery liquid holding base and
A third step of bringing the droplet of the recovered liquid into contact with the peripheral portion of the wafer;
A fourth step of recovering the object to be measured present in the periphery of the wafer into droplets of the recovery liquid while rotating the wafer horizontally;
A recovery method comprising:   3. The recovery liquid according to claim 1, wherein the third step includes a step of changing the contact area of the peripheral portion of the wafer in contact with the recovery liquid droplet when the recovery liquid droplet contacts the peripheral portion of the wafer. A collection method for moving the holding table in the direction of the wafer table.   The recovery method according to claim 1, wherein the object to be measured is a metal impurity. According to claim 1, further droplets of recovered liquid was dropped on the wafer surface is moved over the wafer surface while held by the holder sandwiching between the wafer surface, collecting the measured object present on the wafer surface A recovery method comprising a process. Analysis method for analyzing a measured object recovered by any recovery method of claims 1 4. 6. The analysis method according to claim 5, wherein the measurement object is analyzed by a fluorescent X-ray analysis method. A wafer stage for holding the wafer horizontally and rotatably;
A recovery liquid holding table that holds the dropped liquid droplets on the table;
A holder for holding the liquid drop of the recovery liquid so as to be sandwiched between the recovery liquid holding table;
With
A recovery device for recovering the object to be measured existing in the peripheral portion of the wafer by bringing the peripheral portion of the wafer into contact with the droplet of the recovery liquid on the recovery liquid holding table while rotating the wafer horizontally. 8. The recovery apparatus according to claim 7 , further comprising a moving mechanism for moving the recovery liquid holding base in the direction of the wafer base so as to change the contact area of the peripheral portion of the wafer that contacts the liquid droplets of the recovery liquid. 8. The recovery apparatus according to claim 7, wherein the object to be measured is a metal impurity. 8. The recovery apparatus according to claim 7, wherein the recovery liquid dropped on the wafer surface is moved on the wafer surface while being held by a holder sandwiched between the wafer surface and the object to be measured existing on the wafer surface is recovered. . An analysis system comprising the collection device according to any one of claims 7 to 10 and an analysis device for analyzing the collected measurement object. 12. The analysis system according to claim 11, wherein the analyzer is a fluorescent X-ray analyzer.

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