JPH04151506A - Measuring method for film thickness by use of fluorescent x-ray - Google Patents

Abstract

PURPOSE:To enable checkup of a position by a simple operation and to make a measured value correct by narrowing down a primary X-ray by a collimator having a flat hole and by applying it onto the surface of a sample with the longitudinal direction of the sample made parallel to the longitudinal direction of the flat shape of the collimator. CONSTITUTION:A primary X-ray 20 generated from an X-ray source 1 is made to be a primary X-ray beam 20 having a slender shape by a collimator 2 having a rectangular hole 2a and is applied to a sample. The sample has slender-line- shaped parts 4a formed in a large number and the X-ray 20 is applied to these parts. Besides, the sample is set on a sample stage 3 being movable for each step and the movement for each step is made in the width direction of the shape of the beam of the X-ray 20. A fluorescent X-ray 21 generated by application of the X-ray 20 to the slender-line parts 4a of the sample is detected by an X-ray detector 5 and the detected X-ray 21 is sent as a signal to an amplifier 6 and amplified. This amplified signal is sent to a multichannel analyzer 7 and a controlling arithmetic element 9, and a film thickness computed from the intensity of the fluorescent X-ray of the signal is outputted as data.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention measures the amount of fluorescent XvAO generated from the sample by irradiating the sample with primary This article relates to a fluorescent XSa* thickness measurement method for measuring thickness.

[Conventional technology]

A method of measuring the film thickness of a film formed on the surface of a sample using fluorescent X-ray measurement of a thin long sample with a width of several tens of microns or more is to use primary X-rays on a plane narrower than the width of the sample. A collimator with a round hole was used to narrow down the primary X-rays, and the sample was irradiated with precisely aligned primary X-rays. In order to accurately irradiate a sample with narrowly focused primary X-rays, the sample must be observed using a microscope with high magnification or imaged using a CCD camera.

(Problems to be Solved by the Invention) In film thickness measurement using fluorescent X-rays, when the irradiation amount of primary X-rays decreases, the amount of fluorescent X-rays decreases, and the accuracy of film thickness measurement decreases. In other words, the thinner the sample, the lower the accuracy of film thickness measurement. In addition, in order to adjust the primary X-ray irradiation position and monitor the microsample as large as possible, it is necessary to increase the magnification of the optical system.
In the case of samples such as TAB used in the electronic component industry, where multiple thin wires are lined up, it may become unclear which sample is being measured. Further, there was a problem in that the irradiation position of the primary X-rays was shifted from the observation position of the optical system, and the primary X-ray irradiation was shifted with respect to the sample.

[Means to solve the problem]

The present invention has been made to solve the above problems, and is a method for measuring the film thickness of a sample using fluorescent X-rays. A collimator having a shaped hole is used to irradiate the sample surface so that the longitudinal direction of the sample is parallel to the longitudinal direction of the flat collimator shape, and the sample stage on which the sample is placed is aligned with the width of the thin line shape of the sample. This is a film thickness measurement method using fluorescent X-rays, in which the sample is fed in steps by an amount smaller than the width of the collimator, and the fluorescent X-rays generated from the sample are measured at each feeding step.

[Effect]

Since the planar shape of the hole of the collimator for focusing the primary X-rays is flat, it is possible to irradiate the sample with the primary X-rays over a relatively large area even for an elongated sample. Therefore, the amount of fluorescent X-rays increases, and measurement accuracy increases. In addition, since the sample is fed step by step in the width direction,
Even if the primary X-ray irradiation position on the sample is slightly shifted, the primary X-ray irradiation position can be determined based on the amount of fluorescent X-rays. For example, the film 11 is formed on the substrate 10 only on the top surface of the sample. When the sample, that is, the cross-sectional shape is as shown in Figure 3, the fluorescence XvA caused by primary X-ray irradiation from above the figure.
The amount of O is zero when the primary X-ray irradiation is completely shifted to the left and right with respect to the sample, and the amount of fluorescent X-ray is zero when the primary X-ray irradiates the sample at the left and right edges. The amount of fluorescent X-rays increases somewhat, and the amount of fluorescent X-rays reaches its peak when the surface of the sample is completely irradiated with primary X-rays. In other words, the relationship between the irradiation position of the primary X'41A on the sample and the amount of fluorescent X-rays generated from the sample is as shown in FIG. 2a. In other words, the peak amount of fluorescent X-rays represents the film thickness.

Also, a board with a rectangular cross section! In the case of a sample as shown in FIG. 3b in which Nil is formed on the entire 00 surface, the amount of fluorescent CX-rays increases when the edge of the sample is irradiated with primary X-rays. This is because when the end portions are viewed from the surface of the sample, the entire sample appears to be made of the membrane material. In other words, the relationship between the irradiation position of the primary X-ray on the sample and the amount of fluorescent X-rays generated from the sample is as shown in FIG. 2b. In other words, the amount of fluorescent X-rays between the peak values represents the film thickness.

As described above, the sample can be moved step by step without increasing the observation magnification of the sample to obtain accurate (
Fluorescent X-rays that accurately represent film thickness! #) The value can be detected. And since it can be carried out with relatively low magnification,
The turning point 1 of the entire sample can be easily identified.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure is a system configuration diagram schematically showing a fluorescent X-ray film thickness measuring device according to the present invention. I is an X-ray source that generates primary X-rays, and the primary X-rays 20 generated from the X-ray source 1 are converted into an elongated primary X-ray beam 20 by a collimator 2 having a hole 2a having an elongated rectangular planar shape. Then, sample 4 is irradiated. The sample has many thin wire-shaped portions 4a, and these portions are irradiated with primary X-rays. The width of the hole 2a of the collimator 2 is narrower than the width of the thin sample wire 4a, and the longitudinal direction of the hole 2a is limited by the size of the sample 4 and the performance of the X-ray detector 5 for detecting fluorescent X-rays. However, the longer the better.

The primary xvA beam 20 is irradiated so that its longitudinal direction coincides with the longitudinal direction of the thin line-shaped portion 4a of the sample.

Further, the sample 4 is placed on a sample stage 3 that can be moved step by step. The movement of the sample stage 3 for each step is in the width direction of the beam shape of the primary X-ray 20, that is, the movement of the sample 4
It moves in the width direction of the thin line-shaped portion 4a. The amount of movement is narrower than the width of the beam shape of the primary X-ray 20 (an amount on the order of microns).

Here, the primary X-rays focused by the collimator 2 are transferred to the sample 4.
The X-ray detector 5 detects the fluorescent X-rays 21 generated by irradiating the thin wire portion 4a as the amount per unit time.

Fluorescent X-rays 21 detected by the X-ray detector are sent as a signal to an amplifier 6 for amplification.

The signal amplified by the amplifier 6 is sent to the multi-channel analyzer 7 and the control calculation section 9, which calculates the intensity of the fluorescent X-rays and outputs the film thickness as data.Then, the calculation of the emitter 9 is completed. Then, a signal is sent to the stage controller 8 that controls the movement of the sample stage 3, and 0 or more operations are repeated to move the sample on the order of microns.
Obtain the data in Figure or Figure 2b.

When the data shown in FIG. 2a is obtained, the film thickness at the measurement position of sample 4 is converted into film thickness based on the peak value.

Further, when the data shown in Figure 2 is obtained, the film thickness at the measurement position of sample 4 is converted into film thickness based on the value between the peaks.

〔Effect of the invention〕

As mentioned above, it is possible to easily confirm the position of a sample with many thin line shapes (without requiring observation means with a large magnification), and to accurately measure the film thickness. There is an effect.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing an outline of the fluorescent X&I film thickness measuring device according to the present invention, Fig. 2a is a graph showing the relationship between the sample stage position and the fluorescent X-ray dose in Fig. 3a, and Fig. 2b is
The figure is a graph showing the relationship between the sample stage position and the fluorescent X-ray dose in Fig. 3b, and Figs. 3a and 3b are sectional views showing the cross section of the sample, respectively. 1... X-ray source 2... Collimator 2a, collimator hole 3... Sample stage 4... Sample
4a・Fine line part of sample 5・X-ray detector
6...Amplifier 7...Multi-channel analyzer 8...Stage controller, control calculation section, substrate 1, membrane 20, primary X-ray beam and above

Claims (1)

[Scope of Claims] At least one or more fine wire-shaped sample is irradiated with primary X-rays, and the intensity of fluorescent X-rays generated from the sample is measured to determine the thickness of the film formed on the surface of the sample. In the method of measuring the primary irradiate in parallel with the longitudinal direction, and step-feed the sample stage on which the sample is placed in the width direction of the thin line shape of the sample by an amount smaller than the width of the collimator, and move the sample at each feeding step. A film thickness measurement method using fluorescent X-rays that measures fluorescent X-rays generated from.