JP2006339254A - Wafer contour detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact device for wafer contour detection capable of precisely detecting wafer contour, with simple structure only composed of static parts and ease of handling. <P>SOLUTION: There are provided a light irradiator 1 for irradiating polarized light Ra in a predetermined direction from one surface side of a semiconductor wafer 300 which is a non-optically active substance; a reflecting member 2 which rotates or reduces and reflects the polarized light Ra from the light irradiator 1, while being arranged at another surface side of the wafer 300 so as to spread the light to the outside including the outer contour of the wafer 300 in view of the one surface side; and a light detector 3 for detecting only the polarized light Ra in the predetermined direction or only the light except the polarized light Ra among the reflecting light, arranged in a position which can receive the reflective light from the wafer 300 and the reflecting member 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer contour detection device and the like used for detecting a notch provided in a semiconductor silicon wafer.

  A semiconductor silicon wafer is a thin disk having a thickness of about 1 mm, which is sliced from a cylindrical ingot and manufactured through a series of processes such as polishing and mirror polishing, and has a single crystal structure. In order to indicate the (110) direction, which is the cleavage direction of the wafer, a part of the ingot is cut off in advance to form a so-called orientation flat. Many.

  Such notches and orientation flats are used for wafer positioning in each manufacturing process. As a notch position detection device for that purpose, there is known a device (Patent Documents 1 and 2) in which a wafer is placed on a rotary table and rotated, and a notch is detected by a linear sensor.

  However, since this type requires dynamic mechanical parts such as a rotating mechanism, notch detection cannot be performed and the wafer may be damaged when the wafer is housed in a vacuum chamber.

  On the other hand, since the wafer is a mirror surface, a light scattering member is arranged around the wafer, and light is irradiated obliquely, and only the light from the light scattering member is detected by an imaging device installed above the wafer. What can be done (Patent Document 3) is also considered. With such a structure, it is possible to detect the notch by obtaining the outline of the wafer, and since there is only a static part, there is little risk of damaging the wafer.

  However, when applying to a wafer accommodated in the chamber, it is difficult to obtain sufficient contrast due to the influence of stray light such as light reflected by the inner wall surface of the chamber. In addition, while the light is irradiated obliquely, the reflected light must be detected in the direction facing the wafer. Therefore, the light irradiation device and the image pickup device must be arranged apart from each other, and the light is supplied to the vacuum chamber. There is also a problem that two windows, an irradiation window and an imaging apparatus window, must be provided separately.

In addition, a method of detecting a notch by installing a backlight behind the wafer has been considered. However, when used in a vacuum, in order to make this backlight shine, the light must be guided from the outside by the glass fiber. However, since the glass fiber becomes extremely fragile in the vacuum, it is very difficult to handle. There is a problem that.
JP 7-260432 A JP-A-8-8328 JP 2000-31245 A

  Therefore, the present invention provides a compact wafer contour detection apparatus that can detect the contour of a semiconductor wafer with high accuracy with a simple structure including only static parts, and to solve the above-mentioned problems all at once. This is the main intended issue.

  That is, the wafer contour detection apparatus according to the present invention includes a light irradiation unit that irradiates polarized light in a predetermined direction from one surface side of a wafer that is a non-optically active material, and an outer contour of the wafer as viewed from the one surface side. The reflecting member is arranged on the other surface side of the wafer so as to extend to the outside, and reflects or reflects light from the light irradiation unit by rotating or reducing polarized light from the light irradiation unit, and reflected light from the wafer and the reflecting member. And a light detector that detects only the polarized light in the predetermined direction or only the light other than the polarized light out of the reflected light.

  In such a case, the semiconductor wafer that is a non-optically active material reflects the polarized light as it is, while the reflecting member disposed around the semiconductor wafer reflects the polarized light while changing the polarized light. The reflected light and the reflected light from the reflecting member can be detected with a contrast. Moreover, since it is a static structure using only optical components, the structure is simple, it is advantageous in terms of cost, and handling is easy. Moreover, since polarized light is used, even if there is some stray light, it is not easily affected, and the outline of the wafer can be detected with high accuracy (with a high SN ratio). Furthermore, since the light irradiation unit and the light detection unit can be arranged close to each other, the size can be reduced.

  The effect of the wafer contour detecting apparatus according to the present invention is particularly remarkable when used for detecting the contour of a wafer held in a vacuum chamber. In other words, since it is a static structure that uses only optical components, even if the wafer is housed in a vacuum chamber, it is possible to detect the alignment without difficulty and align the wafer. Although the reflected light from the inner wall becomes noise and causes the SN ratio to deteriorate, according to the present invention, the polarization of the polarized light emitted from the light irradiation unit is rotated or reduced when reflected by the inner wall of the chamber. Therefore, it is difficult to cause stray light (noise) in the light detection unit.

  Further, in the present invention, as described above, the light irradiation unit and the light detection unit can be disposed close to each other. Therefore, the light irradiation unit and the light detection unit are disposed outside the chamber, and the light irradiation unit and the window of the chamber are arranged. Thus, it is possible to irradiate the wafer with polarized light and allow the light detection unit to receive reflected light through the same window.

  It is more preferable if the reflecting member also serves as a holding member that holds the outer peripheral portion of the wafer.

  As a specific embodiment of the light irradiator, the light irradiator may include a light emitter and a first polarizing filter that allows only polarized light in the predetermined direction to pass through from the light emitter. Can do.

  In order to perform contour detection with higher accuracy, the light irradiation unit includes a plurality of light emitters arranged in a ring shape around the observation hole, and a light shielding member provided on the inner side of the light emitters. It is desirable that the member is configured so as to cut light that spreads by a predetermined angle or more toward the central axis of the observation hole among the light emitted from the light emitter.

  As a specific embodiment of the photodetection unit, the photodetection unit is provided in front of the photodetection element and the photodetection element, and passes only the polarized light in the predetermined direction or only the light excluding the polarized light. The thing provided with the 2 polarizing filter can be mentioned.

  As a specific example in which the effect of the present invention is particularly remarkable, one used for detecting a notch on a wafer can be cited.

  When the wafer is only a silicon single crystal main body, it is a non-optically active material as described above, but an optically active layer made of polyimide or the like may be formed on the surface of the main body through subsequent surface treatment or the like. . In this case, if a non-optically active material is used for the reflecting member, the contour of the wafer can be detected with the difference in polarization as contrast.

  In other words, from one side of the wafer, a light irradiation unit that irradiates polarized light in a predetermined direction, and the other side of the wafer so as to extend to the outside including the outer contour of the wafer when viewed from the one side. A reflection member disposed on the surface side, and a light detection unit disposed at a position where the reflected light from the wafer and the reflection member can be received, and the optical activity of the wafer is predetermined for the reflection member As described above, materials having different optical activities may be used, and the light detection unit may substantially detect only the polarized light or only light other than the polarized light.

  The contour detection apparatus using such polarized light does not limit the wafer to the measurement object. Since the light irradiation unit and the light detection unit can be arranged at substantially the same position, the contour of the measurement object inside can be detected from the outside through one small window, so the partition wall can In an environment that is isolated from the environment (for example, in the vacuum chamber described above, other explosion-proof rooms, painting rooms, etc.), it is not necessary to provide many windows on the partition wall. It is very suitable when performing.

  In other words, the outside is to detect the outline of the measurement object installed in the internal environment isolated by the partition wall, and is installed outside and passes through the window provided in the partition wall to the measurement object. A light irradiating unit that irradiates polarized light in a predetermined direction from one side, and a reflection member disposed on the other side of the measurement object so as to extend to the outside including the outer contour of the measurement object as viewed from the one side. A light detection unit disposed at a position capable of receiving reflected light reflected by the measurement object and the reflection member and transmitted to the outside through the same window as the window, and the measurement object on the reflection member It is preferable that a material whose optical activity is different from the optical activity by a predetermined amount or more is used, and the light detection unit substantially detects only the polarized light or only the light excluding the polarized light.

  According to the present invention configured as described above, attention is paid to the optical activity of a measurement object such as a wafer, and the contour of the wafer or the like is detected by skillful use of polarized light. Therefore, it is possible to reduce the cost by simplifying the configuration and to handle it easily. Moreover, since polarized light is used, even if there is some stray light, it is not easily affected, and the outline of the wafer can be detected with high accuracy (with a high SN ratio) even under various manufacturing processes with different environments. Furthermore, since the light irradiation unit and the light detection unit can be arranged close to each other, it is possible to reduce the size.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, a wafer contour detection apparatus 100 according to the present embodiment includes a semiconductor silicon single crystal wafer 300 (hereinafter simply referred to as wafer 300) accommodated in a vacuum chamber 200 in an ion implantation process, for example. In other words, the notch 300b may be detected.

  Specifically, the wafer contour detection apparatus 100 includes a light irradiation unit 1 that irradiates light Ra (hereinafter referred to as polarization Ra) having a vibration surface in a predetermined direction from one surface (here, the upper surface) 300a of the wafer 300. The reflection member 2 disposed on the other surface side (here, the lower side) of the wafer 300 and the light detection unit 3 that receives the reflected light from the wafer 300 and the reflection member 2 are provided.

  Each part will be described in detail.

  As shown in FIGS. 1 and 3, the light irradiation unit 1 is supported by the frame 11 by arranging the frame 11 with the observation hole 1 a penetrating through the center and arranging the observation hole 1 a in a ring around the observation hole 1 a. A plurality of LEDs 12 that are light emitters and a first polarizing filter 13 that is provided in front of the LEDs 12 and that substantially passes only the polarized light Ra of the light emitted from the LEDs 12. The hole 1 a is disposed so as to face the outside of the transparent window 201 provided in the chamber 200 so that the central axis C of the hole 1 a substantially coincides with the central axis of the wafer 300.

  The LED 12 is, for example, a shell type that emits light at a predetermined solid angle (directivity), and the optical axis of each LED 12 coincides with the direction of the central axis C of the observation hole 1a, that is, the optical axis is in contact with the wafer upper surface 300a. It is arranged to be vertical.

  The inner wall that forms the observation hole 1a in the frame 11, that is, the inner wall that is disposed on the inner side of the LED 12 (on the side of the central axis C) serves as the light shielding member 4, and among the light emitted from the LED 12, Light that spreads by a predetermined angle or more toward the central axis C of the observation hole 1a, more specifically, light that reaches the opposite edge beyond the center of the wafer 300 is cut.

  As shown in FIGS. 1 and 3, the reflecting member 2 is an annular member having a constant width that includes the outer contour of the wafer 300 and extends to the outside as viewed from above, and has a dispersion characteristic for light such as alumina. It is formed of a high material, that is, a material that reflects and rotates the irradiated polarized light Ra. Here, the reflecting member 2 also serves as a holding member that holds the outer peripheral portion of the wafer 300 and is in contact with the lower peripheral edge of the outer periphery of the wafer 300. However, as shown in FIG. 300 may be supported, and the reflecting member 2 may be separated from the wafer 300. Further, the reflecting surface 2a of the reflecting member 2 may not be horizontal, and may be inclined obliquely so as to be a conical concave surface as shown in FIG. Further, the reflecting surface 2a may be a rough surface that scatters and reflects light, or a specular surface that reflects specularly.

  As shown in FIG. 1, the light detection unit 3 is arranged coaxially with the light irradiation unit 1, that is, arranged above the observation hole 1 a or in the observation hole 1 a, and is reflected by the wafer 300 and the reflection member 2. Of the reflected light that has passed through the chamber window 201, a second polarizing filter 31 that substantially passes only the polarized light Ra, and a lens system 32 that forms an image of the light that has passed through the second polarizing filter 31, An area image sensor (photodetection element) 33 such as a CCD is provided.

  Thus, according to the wafer contour detecting apparatus 100 as described above, the wafer 300 is a non-optically active material and reflects the polarized light Ra as it is, while the reflecting member 2 disposed around the wafer 300 changes the polarization degree of the polarized light Ra. Reflect. In the light detection unit 3, only the polarized light Ra, that is, only the reflected light from the wafer 300 is detected by the second polarizing filter 31, so that an image captured by the light detection unit 3 is shown in FIG. 4. The detection can be performed with contrast so that only the wafer 300 is bright and the other portions are darkened so that the outline of the wafer 300 can be clearly seen.

  In addition, since it is a static structure using only optical components, it can be applied to the wafer 300 accommodated in the vacuum chamber 200 and can be aligned. In addition, the configuration is simple, the cost can be reduced, and handling is also possible. Easy.

  Moreover, since the light emitted from the light irradiation unit 1 and reflected by the inner wall of the chamber 200 has already lost its polarization characteristics, it cannot become stray light, and even in an environment where the light is irregularly reflected as in the chamber 200, the wafer 300 contours can be detected with high accuracy (with a high SN ratio).

  Furthermore, since the light irradiation unit 1 and the light detection unit 3 can be arranged close to each other, the size can be reduced, and the light irradiation unit 1 and the light detection unit 3 are arranged in the chamber 200 as shown in FIG. The wafer 300 can be irradiated with light and received through the same window 201 of the chamber 200.

  Further, in this embodiment, a ring illuminator in which LEDs 12 are arranged in a ring shape is used as the light irradiation unit 1, but the light from each LED 12 is reflected by the light shielding member 4 in the vicinity of the wafer 300 immediately below it. It reaches only the reflecting member 2 and hardly reaches the outer peripheral portion on the opposite side of the wafer 300. Therefore, it is possible to prevent a phenomenon in which light having significantly different irradiation angles reaches the same location twice, and to prevent the detection of the contour blur caused by the phenomenon, and accurately and sharply detect the contour of the wafer 300 including the notch 300b. It becomes possible to do.

  The present invention is not limited to the above embodiment.

  For example, a filter that substantially allows light other than the polarized light to pass therethrough may be used as the second polarizing filter. In that case, the light detection unit detects light other than the reflected light from the wafer, and as shown in the detected image in FIG.

  Further, the surface 2a of the reflecting member 2 does not have to be flat over the entire surface, and there may be a step in the middle as shown in FIG. 8, or it is divided into a plurality of portions 21 as shown in FIG. Alternatively, the portions 21 may be configured to overlap each other when viewed from one surface side. In short, as shown in FIG. 10, it is only necessary that the reflection member 2 is continuous so as to include all the outer contours when viewed from one surface side of the wafer 300. In various manufacturing processes, limited to the vacuum chamber, there may be other inspection and manufacturing structures around the wafer, and this configuration is particularly effective in avoiding them. Become prominent.

  Furthermore, the above-described configuration is very suitable when applied to detect the outer contour of a measurement object in an environment isolated from the outside, such as an explosion-proof chamber and a painting chamber, as well as a wafer.

  Moreover, you may use the light-emitting body different from LED, and a light irradiation part is not restricted to ring illumination.

  In addition, the present invention may be appropriately combined with the above-described components, and various modifications can be made without departing from the spirit of the present invention.

1 is a schematic overall view of a wafer contour detection device according to an embodiment of the present invention. The top view which shows the wafer and reflective member in the embodiment. The bottom view which shows the light irradiation part in the embodiment. The image figure which shows the captured image of the wafer in one Embodiment of this invention. The typical side view which shows the wafer and reflective member in other embodiment of this invention. The typical side view which shows the wafer and reflective member in other embodiment of this invention. The image figure which shows the captured image of the wafer in other embodiment of this invention. The perspective view which shows the wafer and reflection member in other embodiment of this invention. The perspective view which shows the wafer and reflection member in other embodiment of this invention. The top view which shows the wafer and reflection member in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wafer outline detection apparatus 200 ... Chamber 201 ... Window 300 ... Wafer 300a ... One side (upper surface)
300b ... Notch 1 ... Light irradiation part 12 ... Light emitter (LED)
DESCRIPTION OF SYMBOLS 13 ... 1st polarizing filter 1a ... Observation hole 2 ... Reflective member 3 ... Photodetection part 31 ... 2nd polarizing filter 33 ... Photodetection element 4 ... Light shielding member Ra ... Polarization C ... Center axis

Claims (10)

A light irradiation unit that irradiates polarized light in a predetermined direction from one surface side of a wafer that is a non-optically active material,
It is arranged on the other surface side of the wafer so as to include the entire outer contour of the wafer as viewed from the one surface side and extend to the outside, and reflects by rotating or reducing the polarized light from the light irradiation unit. A reflective member;
A light detection unit that is disposed at a position where the reflected light from the wafer and the reflecting member can be received, and that substantially detects only the polarized light or only the light other than the polarized light out of the reflected light. A wafer contour detecting device.   Used for detecting the outline of a wafer held in a vacuum chamber, a light irradiation unit and a light detection unit are arranged outside the chamber, and polarized on the wafer from the light irradiation unit through the window of the chamber. The wafer contour detecting apparatus according to claim 1, wherein the light detecting unit receives the reflected light through the same window.   3. The wafer contour detecting apparatus according to claim 1, wherein the reflecting member also serves as a holding member that holds an outer peripheral portion of the wafer.   4. The wafer contour detection device according to claim 1, wherein the light irradiation unit includes a light emitter and a first polarizing filter that allows only the polarized light of the light emitted from the light emitter to pass therethrough.   The light irradiation unit includes a plurality of light emitters arranged in a ring around the observation hole, and a light shielding member provided inside the light emitters, and the light shielding member emits light emitted from the light emitter. The wafer contour detection device according to claim 4, wherein the wafer contour detection device is configured to substantially cut light that spreads more than a predetermined angle toward the central axis of the observation hole.   The light detection unit includes a light detection element and a second polarizing filter provided in front of the light detection element and substantially allowing only the polarized light or only light other than the polarized light to pass therethrough. Item 6. A wafer contour detection device according to Item 1, 2, 3, 4 or 5.   7. The wafer contour detecting device according to claim 1, wherein the wafer contour detecting device is used for detecting a notch of the wafer.   A step is provided on the surface of the reflecting member, or the reflecting member is divided into discontinuous parts, and each part is configured to overlap when viewed from one surface side. 8. A wafer contour detecting apparatus according to 6 or 7. A light irradiation unit that irradiates polarized light in a predetermined direction from one surface side of the wafer,
A reflective member disposed on the other surface side of the wafer so as to extend to the outside including the outer contour of the wafer as viewed from the one surface side;
A light detection unit disposed at a position where the reflected light from the wafer and the reflection member can be received, and
The reflective member is made of a material having a predetermined optical activity different from the optical activity of the wafer, and the light detection unit substantially detects only the polarized light or only the light other than the polarized light. A wafer contour detecting device. The outside is to detect the contour of the measurement object in the internal environment isolated by the partition wall,
A light irradiating unit that is installed outside and irradiates polarized light in a predetermined direction from one side of the measurement object through a window provided in the partition;
A reflection member disposed on the other side of the measurement object so as to include the outer contour of the measurement object as viewed from the one side and extend to the outside thereof;
A light detection unit that is reflected by the measurement object and the reflection member and is disposed at a position capable of receiving reflected light that is transmitted to the outside through the same window as the window;
A material whose optical activity is different from the optical activity of the measurement object by a predetermined amount or more is used for the reflecting member, and the light detection unit substantially detects only the polarized light or only the light excluding the polarized light. A contour detecting device characterized by being made.