JP2005201804A - X-ray stress measuring method and X-ray stress measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rapid and highly accurate X-ray stress measurement method and measurement apparatus by one measurement.
A position sensitive X-ray detector 7 for detecting X-rays 5 generated from a sample by making the X-ray incident on the sample 4 held on the optical path of the X-ray output from the X-ray source 1 is provided. In this X-ray stress measurement method, the residual stress of the sample is measured by detecting the diffracted X-ray 5 transmitted through the sample with a position sensitive X-ray detector. By measuring the diffracted X-rays with transmitted X-rays with a thin film thickness, the reference incident X-ray 2 is also recorded in the position-sensitive X-ray detector. Can be read. As described above, since the position of the incident X-ray that becomes the reference for the measurement of the diffracted X-ray can be accurately grasped, the stress measurement can be performed quickly and highly accurately.
[Selection] Figure 1

Description

  The present invention relates to an X-ray stress measurement method and an X-ray stress measurement apparatus for measuring a stress of a material, particularly a wiring material constituting a semiconductor device, using X-rays.

  Wirings used in semiconductor devices are miniaturized as the degree of integration increases, and are formed with submicron wiring widths. Such a fine wiring is surrounded by a silicon oxide film which is an interlayer insulating film formed in the upper and lower layers, so that a large stress is generated in the fine wiring. For this reason, metal atoms of the wiring move due to stress, and a disconnection failure occurs in the wiring. This is the occurrence of so-called stress migration. In order to prevent the occurrence of such disconnection failure of fine wiring, measurement of wiring stress by X-rays has been attempted.

An X-ray stress measuring apparatus for obtaining a residual stress on the surface of a metal material or the like by using an X-ray diffraction method has been conventionally known. The sin ² ψ method is used as the most general stress measurement method.

However, in the sin ² ψ method, it is necessary to change the incident angle of X-rays to the sample and measure the diffraction angle of the diffraction line by the specific crystal lattice plane at each incident angle. Therefore, there is a problem that the time required for measurement becomes long.

In view of this, a method has been proposed in which the stress of the sample can be measured by a single measurement (for example, Patent Documents 1 and 2). These methods are methods for obtaining data necessary for stress analysis in one measurement using a two-dimensional recording method such as an X-ray film, a position sensitive X-ray detector and the like.
JP 2001-56303 A Japanese Patent Laid-Open No. 10-48158

  However, in the above X-ray stress measurement method, the diffracted X-rays diffracted at the crystal lattice plane in the sample and reflected from the sample surface are measured by a position sensitive X-ray detector or the like. When the reflected diffracted X-rays are measured, incident X-rays that serve as reference points for reading the position of the diffracted X-rays are not recorded in the detector. .

  Accordingly, an object of the present invention is to provide an X-ray stress measurement method and an X-ray stress measurement apparatus using X-rays that are quick and highly accurate in one measurement. .

  In order to solve the above problem, the X-ray stress measurement method according to claim 1 of the present invention is characterized in that an X-ray is incident on a sample held on an optical path of an X-ray output from an X-ray source, and the sample An X-ray stress measurement method using a position-sensitive X-ray detector for detecting diffracted X-rays generated from the sample, wherein the position-sensitive X-ray detector detects the diffracted X-rays transmitted through the sample. Measure the residual stress of the sample.

  The X-ray stress measurement method according to claim 2 is the X-ray stress measurement method according to claim 1, wherein the film thickness of the sample is 200 μm or less.

  The X-ray stress measurement method according to claim 3 is a position-sensitive type in which X-rays are incident on a sample held on the optical path of the X-rays output from the X-ray source and diffracted X-rays generated from the sample are detected. An X-ray stress measurement method using an X-ray detector, wherein the position-sensitive X is determined from a positional relationship in which the detection intensity of two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized. A step of obtaining an incident angle of the incident X-ray with respect to the X-ray detector; and the position-sensitive X-ray detector so that the incident X-ray is incident on the position-sensitive X-ray detector perpendicularly from the incident angle. And a step of measuring the residual stress of the sample by detecting diffraction X-rays transmitted through the sample after the adjustment by the position sensitive X-ray detector.

  5. The X-ray stress measuring apparatus according to claim 4, wherein X-rays are incident on a sample held on an optical path of X-rays output from an X-ray source, and diffraction X-rays generated from the sample are converted into position-sensitive X-rays. An X-ray stress measurement apparatus for measuring residual stress of the sample by detecting with a detector, wherein the detected intensity of two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized. An incident angle of the incident X-ray with respect to the position-sensitive X-ray detector is obtained from a positional relationship, and the position is set so that the incident X-ray is perpendicularly incident on the position-sensitive X-ray detector from the incident angle. A control mechanism for adjusting the orientation of the sensitive X-ray detector was provided.

  According to the X-ray stress measurement method of the first aspect of the present invention, the residual stress of the sample is measured by detecting the diffracted X-ray transmitted through the sample with the position sensitive X-ray detector. By measuring the diffracted X-rays with the transmitted X-rays while reducing the thickness, the reference incident X-rays are also recorded in the position-sensitive X-ray detector. For this reason, the diffraction X-ray pattern can be read accurately. In this way, since the position of the incident X-ray that becomes the reference for measurement of the diffracted X-ray can be accurately grasped, it is possible to perform stress measurement quickly and with high accuracy. This facilitates the stress evaluation of the thin film constituting the semiconductor device, enables the manufacture of a semiconductor device with reduced stress, and has the effect of producing a highly reliable semiconductor device.

  According to the second aspect of the present invention, since the film thickness of the sample is 200 μm or less, the stress can be measured using transmitted X-rays.

  According to the X-ray stress measurement method of the third aspect of the present invention, the position-sensitive X-ray detection is based on the positional relationship in which the detection intensity of the two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized. Determining the incident angle of the incident X-ray with respect to the detector, adjusting the orientation of the position-sensitive X-ray detector so that the incident X-ray enters the position-sensitive X-ray detector perpendicularly from the incident angle; And measuring the residual stress of the sample by detecting the diffracted X-ray transmitted through the sample with a position-sensitive X-ray detector after adjustment, so that the incident X-ray is perpendicular to the position-sensitive X-ray detector. It can be made incident. Therefore, the distance between the incident X-ray and the diffracted X-ray on the position-sensitive X-ray detector is equalized, so that the diffraction pattern can be read accurately, so that the stress measurement can be performed quickly and with high accuracy. Is possible. This facilitates the stress evaluation of the thin film constituting the semiconductor device, enables the manufacture of a semiconductor device with reduced stress, and has the effect of producing a highly reliable semiconductor device.

  According to the X-ray stress measuring apparatus of the fourth aspect of the present invention, the position-sensitive X-ray detection is based on the positional relationship in which the detection intensity of the two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized. A control mechanism is provided for determining the incident angle of the incident X-ray with respect to the detector and adjusting the orientation of the position-sensitive X-ray detector so that the incident X-ray is incident on the position-sensitive X-ray detector perpendicularly from the incident angle. Therefore, it is possible to accurately grasp the position of the incident X-ray that is a reference for the measurement of the diffracted X-ray, and it is possible to measure the stress quickly and with high accuracy. The position sensitive X-ray detector can be adjusted by the control mechanism so as to be perpendicular to the incident X-ray. As a result, the distance between the incident X-ray and the diffracted X-ray on the position-sensitive X-ray detector is equalized so that the diffraction pattern can be read accurately, so that the stress measurement can be performed quickly and with high accuracy. Is possible.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram of an X-ray stress measurement method according to the first embodiment of the present invention.

  In FIG. 1, 1 is an X-ray generator, 2 is an incident X-ray emitted from the X-ray generator 1, 3 is an incident slit, 4 is a measurement sample, 5 is a diffracted X-ray transmitted, 6 is an X-ray irradiation point, 7 is a position sensitive X-ray detector, and 8 is a personal computer. The present embodiment is an X-ray stress measurement method using an X-ray diffractometer equipped with a position sensitive X-ray detector 7 for detecting diffracted X-rays 5 generated from a sample 4, a personal computer, and the like.

  That is, the incident X-ray 2 emitted from the X-ray generator (X-ray source) 1 is irradiated through the slit 3 onto the measurement sample 4 held on the optical path of the X-ray. Diffracted X-rays 5 are generated by the specific crystal lattice plane of the sample 4. The film thickness of the sample 4 is desirably 200 μm or less. In this way, the residual stress of the sample 4 is measured by reducing the thickness of the sample 4 and detecting the transmitted diffracted X-ray 5 with the position sensitive X-ray detector 7. In FIG. 1, the diffracted X-ray 5 is shown as a single straight line, but the diffracted X-ray 5 travels in a cone-shaped region having the X-ray irradiation point 6 as a vertex. The cone-shaped diffracted X-ray 5 is detected by a position sensitive X-ray detector 7. The detected diffraction image is sent to the personal computer 8 and subjected to image processing and the like, and the residual stress of the sample 4 is obtained from the diffraction pattern by a predetermined calculation process. The actual stress calculation can be obtained using the calculation method described in Patent Document 1 above.

  As described above, in the X-ray stress measurement method according to the embodiment of the present invention, since transmitted X-rays are used, incident X-rays 2 are simultaneously recorded in the position-sensitive X-ray detector 7 together with the diffraction X-ray pattern. For this reason, a diffraction X-ray pattern can be read accurately, and stress measurement can be performed with high accuracy.

  Next, a modification of the first embodiment will be described with reference to FIGS. In the first embodiment, when the X-ray 2 is not perpendicularly incident on the position sensitive X-ray detector 7 as shown in FIG.

  As shown in FIG. 3, when the incident X-ray 2 is incident perpendicular to the position-sensitive X-ray detector 7, the position-sensitive X-ray detector 7 of the incident X-ray 2 and the diffracted X-rays 5a and 5b is used. The above distances 10a and 10b are equal. 9a and 9b are diffraction angles. However, when the incident X-ray 3 is incident obliquely on the position-sensitive X-ray detector 7 as shown in FIG. 4, the position-sensitive X-ray detector 7 of the incident X-ray 2 and the diffracted X-rays 5a and 5b. There is a problem that the distances 11a and 11b are not equal.

  In this case, if the position sensitive X-ray detector 7 is made perpendicular to the incident X-ray 2 as shown in FIG. 5, the position sensitive X-ray of the incident X-ray 2 and the diffracted X-rays 5a and 5b. The distances 12a and 12b on the detector 7 are equal.

  A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an explanatory diagram of an X-ray stress measurement method according to the second embodiment of the present invention. This embodiment solves the problem of the first embodiment.

  In FIG. 6, the configurations 1 to 8 are the same as those in the first embodiment in FIG. Here, 13 is a slit, and 14 is an adjuster (control mechanism) that adjusts the orientation of the position-sensitive X-ray detector 7.

  As shown in FIG. 6, in the second embodiment, the incident angle of the incident X-ray 2 with respect to the position-sensitive X-ray detector 7 is set by two slits 13 provided on the optical path of the incident X-ray 2 transmitted through the sample 4. The orientation of the position-sensitive X-ray detector 7 is adjusted by the adjuster 14 so that the incident angle of the incident X-ray 2 with respect to the position-sensitive X-ray detector 7 is vertical from this incident angle. The residual stress of the sample 4 is measured by detecting the diffracted X-ray 5 transmitted through the sample 4 after the adjustment by the position sensitive X-ray detector 7.

  Hereinafter, an adjustment method for directing the position-sensitive X-ray detector 7 perpendicularly to the incident X-ray 2 will be described with reference to FIGS. Here, 15 is an angle formed by the mechanical central axis and the incident X-ray 2. 7 to 9, the scales of the x axis and the y axis are different for easy understanding. Also, although it is originally three-dimensional, it will be described in two dimensions for ease of explanation.

  First, as shown in FIG. 7, only the slit 13a is placed on the optical path, and the position of the slit 13a is adjusted so that the detection intensity becomes maximum. Next, as shown in FIG. 8, the slit 13b is placed on the optical path, and the position of the slit 13b is adjusted so that the detection intensity is maximized. The incident angle 15 of the incident X-ray is obtained from the positional relationship between the two slits 13a and 13b at this time. In this case, the distance between the two slits 13a and 13b in the x-axis direction is 300 mm, and the difference between the slits 13a and 13b in the y-axis direction is 0.1 mm. This shows that the incident angle 15 of the incident X-ray 2 is 0.02 degrees.

  Subsequently, as shown in FIG. 9, the position sensitive X-ray detector 7 is adjusted by the adjuster 14 so as to be perpendicular to the incident X-ray 2.

  As described above, in the X-ray stress measurement apparatus according to the present embodiment, when measuring the diffracted X-ray transmitted through the sample, the X-ray can be vertically incident on the position-sensitive X-ray detector. Since the pattern can be read, the stress can be measured quickly and with high accuracy.

  The X-ray stress measurement method and the X-ray stress measurement apparatus according to the present invention can accurately determine the position of incident X-rays that are the reference for measurement of diffracted X-rays, so that quick and highly accurate stress measurement is possible. It is useful for a method and an apparatus for measuring the stress of a wiring material constituting a semiconductor device.

It is explanatory drawing of the X-ray stress measuring method of the 1st Embodiment of this invention. It is explanatory drawing which shows the case where the incident X-ray inclines in the modification of the 1st Embodiment of this invention. It is explanatory drawing which shows the case where the incident X-ray is injecting into the position sensitive X-ray detector perpendicularly in the modification of the 1st Embodiment of this invention. It is explanatory drawing which shows the case where the incident X-ray injects into the position sensitive X-ray detector diagonally in the modification of the 1st Embodiment of this invention. It is explanatory drawing about adjustment of the direction of a position sensitive X-ray detector, when the incident X ray injects into the position sensitive X-ray detector diagonally in the modification of the 1st Embodiment of this invention. It is explanatory drawing of the X-ray stress measuring apparatus of the 2nd Embodiment of this invention. It is explanatory drawing which shows the adjustment method by the X-ray stress measuring method of the 2nd Embodiment of this invention. It is explanatory drawing which shows the adjustment method by the X-ray stress measuring method of the 2nd Embodiment of this invention. It is explanatory drawing which shows the adjustment method by the X-ray stress measuring method of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X generator 2 Incident X-ray 3 Slit 4 Measurement sample 5 Diffracted X-ray 6 X-ray irradiation point 7 Position sensitive X-ray detector 8 Personal computer 9 Diffraction angle 10 Incident X-ray on position sensitive X-ray detector Distance from diffracted X-ray 11 Distance between incident X-ray and diffracted X-ray on position-sensitive X-ray detector (when incident X-ray is tilted)
12 Distance between incident X-rays and diffracted X-rays on position-sensitive X-ray detector (when tilt of position-sensitive X-ray detector is corrected)
13 Slit 14 Adjuster

Claims (4)

X-ray stress measurement method using a position-sensitive X-ray detector for detecting X-rays diffracted from the sample by making the X-ray incident on the sample held on the optical path of the X-ray output from the X-ray source Because
An X-ray stress measurement method, comprising: measuring a residual stress of the sample by detecting diffraction X-rays transmitted through the sample with the position sensitive X-ray detector.   The X-ray stress measurement method according to claim 1, wherein the film thickness of the sample is 200 μm or less. X-ray stress measurement method using a position-sensitive X-ray detector for detecting X-rays diffracted from the sample by making the X-ray incident on the sample held on the optical path of the X-ray output from the X-ray source Because
Obtaining an incident angle of the incident X-ray with respect to the position-sensitive X-ray detector from a positional relationship in which the detection intensity of two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized;
Adjusting the orientation of the position sensitive X-ray detector so that the incident X-ray is incident perpendicularly to the position sensitive X-ray detector from the incident angle;
And measuring the residual stress of the sample by detecting the diffracted X-ray transmitted through the sample after the adjustment by the position sensitive X-ray detector. X-rays are incident on a sample held on the optical path of the X-rays output from the X-ray source, and the residual stress of the sample is detected by detecting the diffracted X-rays generated from the sample with a position-sensitive X-ray detector. An X-ray stress measuring device for measuring
An incident angle of the incident X-ray with respect to the position-sensitive X-ray detector is obtained from a positional relationship in which the detection intensity of the two slits provided on the optical path of the incident X-ray transmitted through the sample is maximized, and the incident An X-ray stress measurement apparatus comprising a control mechanism that adjusts the orientation of the position-sensitive X-ray detector so that the incident X-ray is incident perpendicularly to the position-sensitive X-ray detector from an angle.

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