JPS58202807A - Method for measuring modified layer caused by surface machining of sendust - Google Patents

Abstract

PURPOSE:To improve measuring accuracy, by obtaining a refractive index, when a plane of a sample surface which is mechanochemically polished in a liquid wherein the fine powder of a specified material is suspended in pure water, is made to be reference, and using this index as a reference index for the texture of a sample to be measured. CONSTITUTION:The fine powder of MgO, SiO2, and the like, whose diameter is 0.05mum or less, is suspended in pure water, so that the weight % of the powder is 0.5-20. The surface of a sample is made to face a lap such as hard cloth and Sn in said liquid and lapped by mechanochemical polishing. Thus very precise flat plane is obtained on the sample by the lapping. With this sample as a reference, the refractive index of the texture of a sample to be measured is obtained. A complex number reflection coefficient ratio Rp/Rs of the sample to be measured is computed by a polarization analysis method. Then, a width (d) of a changed layer of the sample to be measured caused by machining is obtained. By this method, flatness and nondistortion property of a magnetic head substrate and the like can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring a process-affected layer, which non-contactly measures the layer thickness of a QO process-altered deposit that occurs on the surface of a horn when mirror finishing is applied to sendust.

1 dust is for electrical equipment, VTR or audio.
It is widely used as a tsusuke head composite material due to its long characteristics, but today there is a demand for even higher recording density.
It is desired to improve the performance of magnetic heads in various applications.

The gap accuracy of the head is a major factor that determines the performance of a magnetic head, and in order to improve the gap accuracy, sufficient flatness of the magnetic head substrate and non-distortion of the processed surface are particularly required.

Generally, on the machined surface of Sendust, which has been mirror-polished to ensure flatness, a thick processed layer is generated due to processing, and this processed layer is a factor that greatly reduces the performance of the magnetic head. It is known. Nowadays, mechanical chemical polishing is being developed as a strain-free processing method that can eliminate this processing deterioration.

However, there was no specific method for measuring the above-mentioned processing deterioration in the layer, and it was not possible to grasp the degree of occurrence of processing deterioration (1) in actual operation. Generally, only the method of determining based on conversion characteristics was used.

In addition, as testing methods, the diagonal polishing method, the Seiko beam reflection diffraction method, etc. are known, but the diagonal polishing method cannot be applied in the residue production system because it is a destructive test.
Electron beam reflection diffraction method shows the existence of processing deterioration 1-a 74 tB,
It was the only thing I could do.

7) The invention proposes a method for measuring processing deterioration that can be effectively utilized in the production process of bounty heads by non-contactly measuring the thickness of the unprocessed deformation layer generated on the processed surface of sendust. It is intended to.

That is, in this invention, fine powder of MgO, 5iOt, etc. is suspended in pure water. The refractive index of the surface of the sample subjected to mechano-chemical polishing in the solution was taken as the refractive index (n,) of the base of the sample to be measured, and the measured reflection coefficient ratio (Rp/Rs) of the temporary measurement sample was determined by ellipsometry. ) to find the thickness (a) of the sample to be measured. This is a method for measuring the surface-treated altered layer of sendust, which is moldy.

In general, the process-affected layers on the surface of sendust material are thought to exist in the order of a fluidized layer, a stress layer, and a bulk layer from the surface, and the fluidized layer exists as an amorphous phase, and the strained layer below this layer is It is thought that the stress 1- affected by □ exists in a real system in a state that cannot be distinguished from that of a fluidized bed.

To measure a thin film such as a process-affected layer using ellipsometry, the change in the amount of polarized light that occurs when polarized light is reflected on a sample is calculated by calculating the change in the amount of polarized light by one phase difference (Δ) and the amplitude reflection coefficient ratio (Rp/
The method used is to calculate the amount using Rs. In other words, it is based on reflection by the sample, so it is below the sample.

The refractive index of the ground, process-altered layer, and atmosphere are important.
To determine the uncut number of process-affected layers, the refractive index of the sample base must be specified.

Therefore, the refractive index is determined by polishing the surface of the sendust sample, but since the chemical erosion rate of sendust differs depending on the crystal orientation, crystal steps will always occur under general mirror finishing conditions, and grain boundary diffusion will be large. Grain boundaries are easily corroded,
It is not possible to obtain a refractive index that should be used as a reference.

Therefore, in this invention, for example, 1 part fine powder of MgO, Si pseudo, etc. with a particle size of 0.05 μm or less is added to 0.5 to 2 parts of pure water.
The surface of the sample was mechano-chemical polished by lapping it in the liquid against a hard cloth, Sn, etc. in a suspension of about 0 wt. The refractive index of the base of the sample to be measured is taken as the refractive index of the base of the sample to be measured, and it is possible to measure the same as the measured refractive index.

The polarization analysis method will be explained below. Figure 1 is! FIG. 2 is an explanatory diagram showing the principle of the Horimoto analysis method.

The Kakumoto analysis method projects polarized light onto the sample surface and measures the change in polarization state that occurs upon reflection to determine the thickness of the thin layer on the surface. ,
First, the phase difference (Δ) and dichroism (Rp/Rs) of the sample are determined simultaneously.

That is, the fast axis of the compensator (C) is tilted by π/4, the polarizer (Pl) and the analyzer (A1) are rotated together, so that a so-called cross niffle state is created, and the light transmitted through the analyzer becomes 4. At this time, the polarizer azimuth (P azimuth) θ is measured, and the phase difference (Δ) of the sample (Sa) is obtained from equation (1).

Next, the change in polarization is determined by the anti-It rate ratio in the sample of the P component wave that oscillates once P and the S component wave that oscillates perpendicularly to this,
In other words, it is measured by "r02 chromaticity. This is done by measuring the analyzer azimuth angle (S direction Ig, ) ψ when measuring the above P azimuth angle θ, and calculating the reflection coefficient ratio (R1) using equation (2). /R11)
get.

When the reflection by sample A (Sa) is determined by the phase difference (Δ) and the reflection coefficient ratio (Rp/Rs) in this way, the complex reflection coefficient ratio (ip/Rs) can be obtained from equation (3). That is, the two quantities d and ψ become polarization parameters, which are important keys in ellipsometry.

Δ = π/2-2θ ・・・・・・・・・・・・(
1) Formula Rp/R@=tanψ ・・・・・・・・・
...(2) Formula Rp/Rs= (Rp/Rs)
exp (tΔ)−・−・−(Formula 31 Also, sample (S
In the reflection in a), the refractive index of the atmosphere is n, the refractive index of the processed damaged layer is n, its thickness is d, the refractive index of the base is n3,
The incident angle at each layer is φ1゜b-fs, and the measurement wavelength is λ
Then, the complex reflection coefficient ratio (Rp/Rs) can be expressed by these functions, and the Fresnel reflection coefficient at each boundary surface can also be determined. Furthermore, from Nunell's law, nl sinφ* = ”t sin 42 = 11
3 sinφ.

It is.

That is, by decomposing the real and imaginary parts of equation (3), Δ=f(ni m ”! m d s ”3 eφ8.
λ)ψ=f("le"! e ds "S-φ
1. λ).

Here, if "Lm", *-□, and λ are known, Δ=
f, cnt, a) ψ=g ("* * d)," and a function of "2*d is obtained.

Therefore, using the refractive index n3 of the process-affected layer and its thickness d as parameters, ψ as shown in Fig. 3 can be calculated using the Eko calculator.
- By making the Δ diagram f1m, the measured values Δ and ψ
From this, the thickness (a) of 1- due to processing damage can be obtained.
However, in this invention, the refractive index of this sample is determined from the base of the test fence to be measured. Since the refractive index (n,) is set to , it is easy to set the standard and a high measurement density can be obtained. 2. Since Sendust is an absorber, its refractive index (n,) is expressed by the complex J.

Next, an example according to the present invention will be shown to clarify its effects.

Sendust (composition: Fe/Al/s
i=8515.4/9.6, 1100℃X3HrH,
The method of the present invention was carried out using each sample whose surface was polished under the conditions shown in Table 1.

Figure 3 shows the ψ and Δ values obtained for each sample using the polarization analyzer a (product name, Shimadzu Ep-10).
It is shown on the chart, and the numbers in the figure and sample numbers match. The incident angle (φ1) is 700, and the measurement wavelength (λ
) is 5461X.

Sample 1 was subjected to mechano-chemical polishing using a processing fluid in which 5 wt* of MgO fine powder with a particle size of 0.0011 Im was suspended in pure water, and this was used as a standard.
□ Then, from the values of ψ and Δ of sample 1, as the refractive index of the base.
s=1.998 3L195j was obtained.

Next, using an electronic computer, we exploded the ψ-Δ diagram using the average refraction 4n2 of the beaten-up altered layer and its thickness d as parameters, and plotted Δ so that the plots of samples 1 to 4 were included.

Heni n! The dog was determined. Kono time, il, =
i, go −1,70i.

n, = 1.95-2.201: was obtained.

Thicknesses a and -i are calculated and plotted on two n2 curves, and the two points are connected with a green line. The Galloe altered layer thickness (d) of each sample obtained from this is shown in Table 7.

Table 1 From Table 1, the thickness of the damaged layer of sample 2 is 100^, that of sample 3 is 300^, and that of sample 4 is 500^. It can be seen that the value of d changes and the correlation with the processing conditions matches well.

As is clear from the above examples, the method of the present invention allows non-contact measurement of the process-affected layer on a mirror-polished surface, and can be applied to mass production, for example, to determine the loft, resulting in an improvement in productivity 90 and yield 90. This is an excellent method for measuring the surface treatment-altered layer of sendust.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the principle of ellipsometry, Figure 2 is an explanatory diagram showing reflection at a single degraded layer of a sample, and Figure 3 is a diagram showing the relationship between ψ and Δ of sample measurements by this invention method. It is. P8...Polarizer, C...Compensation plate, Sa...Sample,
A1...Analyzer. Applicant Sumitomo Special Metals Co., Ltd. Agent 1) Yoshihisa Figure 2

Claims (1)

[Claims] In a solution in which fine powders such as I Mgo, SIO, etc. are suspended in pure water, the refractive index of the test surface subjected to mechanochemical polishing is used as the refractive index of the temporary measurement sample base, and the polarization index analysis method is used. , the complex reflection coefficient ratio (Rp/Rs
) is calculated to determine the thickness (a) of the process-affected layers of the sample to be measured.