JPS5846772B2 - Regeneration needle of regeneration element that detects changes in capacitance value - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A reproducing element (pickup ) and detects the change in capacitance value that occurs according to the state of the information signal in the recording trace as a change in the amount of electricity, so that the information signal recorded at high density on the disk can be reproduced. In the so-called capacitance change detection type information recording and reproducing method, the information signal in the recording trace on the disk is read by detecting the change in capacitance value with an electrode provided on the reproduction needle. The resolution can be improved by making the thickness of the electrode provided on the reproducing needle sufficiently smaller than the length of the pit corresponding to the information signal (the size of the pit in the direction in which the recording trace extends), Therefore, in addition to having the feature that information signals can be recorded and reproduced even at a low rotational speed of the disk, for example, optical information recording in which the information signals recorded on the disk are optically read out is possible. Compared to the reproduction method, research into its practical application has been promoted because it has the following advantages: it does not require a so-called focus servo system, the configuration of the reproduction system is simpler, and other advantages.

By the way, on discs on which information signals are recorded at high density, the interval between recording traces (trunk pitch) is small and the recording wavelength on the disc surface is extremely short. The reproducing needle of the reproducing element used for reading the data has an electrode thickness that is less than 1/2 of the shortest recording wavelength on the disk surface, and a recording trace that is designed to prevent crosstalk from adjacent recording traces from becoming a problem. An electrode portion is formed of a conductive material on the electrode forming surface of the regenerated needle body so that an electrode end portion having an electrode width approximately equal to the spacing can appear on the sliding contact surface. The above-mentioned electrode portion to be formed on the recycled needle must be attached to the recycled needle body with a sufficiently large adhesion force so that it will not peel off from the recycled needle body even when it comes into sliding contact with the disk surface. In addition, it is necessary that the electrode section be configured to exhibit a low electrical resistance value so that the information signal can be detected in a state that exhibits a good C/N. Ru.

In other words, with the playback needle of the capacitance change detection type playback element, the recording information on the disk is detected by the electrode section, mainly the electrode end, while the sliding surface is in sliding contact with the disk surface that is rotating at high speed. is detected by changes in capacitance value, but if the adhesive force between the regenerating needle body and the coating made of conductive material that makes up the electrode part is small, sliding contact with the high-speed rotating disk may occur. When the electrode part is peeled off from the regenerated needle body due to an external force applied to the end of the electrode in a state of External force applied to the electrode part when shaping the needle into the desired shape causes the electrode part to peel off from the recycled needle body, making it difficult to obtain a complete recycled needle, and reducing the yield when manufacturing recycled needles. Problems such as

In addition, in a capacitance change detection type playback element, the capacitance between the electrode part of the playback needle and the information surface of the disc is tuned by a tuning circuit to which a signal of a fixed frequency is applied from a high-frequency oscillator. It is used as all or a part of the frequency determining frequency converter, and the recording of the disc from the tuning circuit is performed by changing the resonant frequency of the tuning circuit due to the change in the capacitance value between the electrode part of the playback needle and the information surface of the disc. Normally, a signal whose amplitude has been modulated by information is extracted and amplitude demodulated to obtain information recorded on the disc (FM wave). Since the electrode part of the regeneration needle used to detect changes is used as an element in the resonant circuit as described above, the electrical resistance of the electrode part determines the sharpness Q of the resonance of the resonant circuit. It becomes an element to do.

Therefore, when the electrical resistance of the electrode part is large and the Q of the resonant circuit becomes low, the resonant frequency changes from f2 to fl as shown in the first diagram due to the change in capacitance value, and the resonant curves change from ■ to ■. , the amount of change α in the resonance curve at the position of the frequency fn of the signal supplied from the high-frequency oscillator to the resonant circuit is extremely small. The information signal is output from the reproducing element as a signal with a poor C/N ratio.

In Fig. 1, the curves ■ and ■ are the resonance curves of the resonant circuit when the electrode part of the regeneration needle is constructed with a small electrical resistance value, and the frequency of the resonant circuit changes as the capacitance value changes. When changing from f2 to fl,
The amount of change β in the resonance curve at the position of the frequency fn of the signal being supplied from the high-frequency oscillator to the resonant circuit is larger than the amount of change α described above, and therefore, the reproducing element can detect a good C/N ratio. A reproduced signal can be obtained.

As described above, the regeneration needle of the regeneration element that detects changes in capacitance requires several factors, such as the adhesion between the electrode part and the regeneration needle body to be sufficiently strong, and the electrical resistance of the electrode part to be low. The conditions must also be satisfied.

Conventionally, the electrode part of a recycled needle is made of a conductive material that can provide a large sealing force with the abrasion-resistant, high-hardness material used for the recycled needle body, and the conductive material is used as the material for the recycled needle. It was formed by depositing a film of a desired thickness on the electrode forming surface of the main body by sputtering or vapor deposition. For example, if the regenerated needle main body was made of diamond, titanium was used to form the material. For example, when the regenerated needle body is made of sapphire, the electrode part is made of hafnium, which provides low electrical resistance and sufficient adhesion to the extent that it does not cause any major problems in practical use. The electrode part was attached to the regenerated needle body using adhesive force, but there is a feeling that regenerated needles that have a long life and stable regeneration characteristics are just a step away. The emergence of regenerated needles with even better performance has been eagerly awaited.

In order to solve the above-mentioned problem of peeling off of the electrode part of the regenerated needle, metal ions and impurity ions are injected into the electrode forming surface of the regenerated needle body using an ion implantation method to form the electrode part. Attempts have been made to extend the lifespan of the needle, but when the electrode part is implanted into the regenerated needle body by ion implantation and formed with metal ions or impurity ions, it is certain that the electrode part will peel off. Although this problem is solved, the electric resistance value of the electrode portion inevitably becomes high, making it difficult to obtain a reproduced signal with a good C/N ratio.

That is, for example, the sheet resistance value Rs obtained when titanium is ion-implanted into diamond under the conditions of an implantation energy of 100 Kev and a dose (DO8E) of 1015 to 1016 ions/c is approximately 7Ω at room temperature. ~IOKΩ, and the distribution state of the ions implanted into the diamond in the depth direction is as shown in Figure 2a, according to the data analyzed using the helium backscattering method. The half-width of the injection amount is approximately 30
0 angstrom.

Now, in order to find the specific resistance value ρ in the implanted layer described above, the distribution of ions in the depth direction shown in FIG. 2A is rewritten into the distribution shown in FIG. When ρ is calculated from the formula, ρ is given by assuming that the sheet resistance Rs is IOKΩ, and the depth and thickness t is 300 angstroms.

Incidentally, the sheet resistance R8 of a 3000 angstrom thick electrode thin film deposited by sputtering on the electrode formation surface of the regenerated diamond or sapphire needle body is several ohms or less, whereas The sheet resistance Rs of the electrode is 7Ω~IOK
Ω is extremely high, and it is clear that it is not possible to obtain a reproduced signal with a good C/N.

In order to obtain a reproduction signal with a good C/N using a reproduction needle equipped with an electrode formed by ion implantation, it is necessary to reduce the sheet resistance Rs of the electrode. Even if the dose is increased beyond the dose indicated by , or even if an attempt is made to lower the sheet resistance by increasing the implantation energy, the semiconductor-like conductivity of the surface will be lost due to deterioration of crystallinity. Perhaps because of this, the sheet resistance value Rs increases, and the crystal becomes brittle due to damage, resulting in a deterioration of the wear resistance method.

Although it is conceivable that the deterioration of crystallinity caused by the above-mentioned causes can be recovered by annealing treatment and the conductivity can be increased, it seems difficult to realize a large decrease in the resistance value due to this.

The present invention provides an electrode made of a conductive material on an ion-implanted layer exhibiting P-type or N-type conductivity formed on the electrode-forming surface of a regenerated needle body made of a highly hard material with wear resistance. The object of the present invention is to provide a regenerated needle in which all of the conventional problems described above are satisfactorily resolved by forming a coating. The contents will be explained in detail.

FIG. 3 is a partial perspective view of an embodiment of the regeneration needle of the capacitance value change detection type regeneration element of the present invention, and in FIG. 3, 1 is the regeneration needle main body; The regenerated needle body 1 is made of a highly hard material having wear resistance, such as diamond or sapphire.

Reference numeral 2 denotes a sliding surface of the reproducing needle main body, and this sliding surface 2 is brought into sliding contact with the disk surface during the reproducing operation.

Reference numeral 3 denotes an electrode forming surface of the reproducing main body. On this electrode forming surface 3, an ion implantation layer 4 showing P type or N type is formed, and an electrode coating 5 made of a conductive material forms an electrode part. is configured.

In the regenerated needle of the present invention shown in the third figure, the regenerated needle main body 1
The electrode portion to be formed on the electrode forming surface 3 is constituted by providing an electrode coating 5 made of a conductive material on the ion implantation layer 4 near the surface of the electrode forming surface 3, so the electrode portion is sufficiently low. The reproduced signal has a good C/N due to the electrode coating 5 having an electrical resistance value, and the electrode coating 5 also eliminates extremely fine particles generated on the surface of the electrode forming surface 30 during the formation of the ion implantation layer 4 on the electrode forming surface 3. The atoms of the constituent material of the electrode coating 5 enter into the lattice defects caused by such damage, and the adhesion strength is improved, making it possible to easily obtain a regenerated needle in which the electrode portion does not peel off.

Note that if the material used to form the ion implantation layer 4 and the constituent material of the electrode coating 5 are the same, the adhesion of the electrode coating 5 to the electrode forming surface 3 may be caused by the constituent material of the regenerated needle body 1. Since the constituent materials of the electrode coating 5 adhere to the mixed layer of the electrode coating 5 and the electrode coating 5, the adhesion strength between the electrode coating 5 and the regenerated needle body 1 becomes even greater.

In addition, if the material used to form the ion implantation layer 4 and the constituent material of the electrode coating 5 are the same, the ion implantation layer 4 can be By lowering the accelerating voltage,
It is also possible to subsequently form the electrode coating 5 by the ion blating method, and by doing so, the manufacturing process can be simplified.

Figures 4 a - d and Figures 5 a - d (Figure 4 d and Figures 5 c, d, etc. are partially enlarged.

) is a perspective view for explaining the manufacturing process when manufacturing the regenerated needle of the present invention, and FIGS. 4a and 5a are
This is the material A of the regenerated needle main body, and in the following description, the material A of the regenerated needle main body is assumed to be a prismatic diamond.

First, the manufacturing process of the regenerated needle will be explained with reference to FIGS. 4a to 4d.

The electrode forming surface 3 of the diamond prism shown in FIG. An injection layer 4 is formed.

It goes without saying that the formation of the ion-implanted layer 4 is performed in a vacuum chamber.

Next, a titanium electrode film 5 of a predetermined thickness is deposited by sputtering on the surface of the raw material of the regenerated needle main body in the state shown in FIG. 4, on which the ion implantation layer 4 is formed. Figure C).

The thickness of the titanium electrode coating 5 is determined as required, taking into account the depth of the ion implantation layer 4 (for example, 2000 to 3000
00A) Next, a regenerated needle having the desired external shape as shown in FIG. 4d is obtained by polishing, but the shape of the sliding surface may be made into a shape other than that shown in the figure. Of course.

The step of attaching the electrode coating 5 to the state shown in FIG. 4 described above may be replaced by the ion blating method instead of the sputtering method, which has the advantage of simplifying the manufacturing process. .

The manufacturing process of the recycled needle shown in Figures 5a-d is as shown in Figure 5a.
An ion-implanted layer 4 of metal ions is formed on the electrode forming surface 3 of the material A of the regenerated needle body made of a diamond prismatic pillar as shown in FIG. 5, and then polished as shown in FIG. 5C. The ion implantation layer 4 shown in FIG. 3C is used as an electrode to form an electrode coating 5 on the ion implantation layer 4. It is.

According to the manufacturing method shown in FIG.
As shown in FIG. 5C, a metal layer is deposited by electroplating only on the ion-implanted layer 4 left in the portion formed by polishing into a predetermined shape electrode forming surface.
Since so-called selective adhesion is automatically performed, as in the case of processing a recycled needle according to the process shown in FIG. Therefore, the electrode coating 5 will not be damaged or peeled off during polishing, and the electrode coating 5 will not be formed on the ion-implanted layer 4 by electroplating. The prepared electrode coating 5 is polished as shown in FIG. 4d in order to have a width similar to that of the electrode forming surface throughout its thickness as shown in FIG. 5d. The cross-sectional area of the end of the electrode is thicker than that of the electrode coating 5, which has a trapezoidal (or triangular in some cases) cross-sectional shape, such as the electrode coating 5, which is made according to the steps shown in Figure 5. The regenerated needle also has the advantage that the regenerated needle has an increased regeneration output than the regenerated needle manufactured according to the steps shown in FIG.

Note that the ions to form the ion implantation layer 4 may be any ions that exhibit P-type or N-type conductivity; It is preferable that the constituent material of the electrode coating 5 to be formed has the same coefficient of thermal expansion and other physical properties.

As is clear from the detailed explanation above, in the regenerated needle of the present invention, P
The structure has an ion-implanted layer that exhibits type or N-type conductivity, and an electrode film made of a conductive material attached to the ion-implanted layer, so the adhesion strength between the electrode film and the regenerated needle body is extremely high. Therefore, the problem of peeling of the electrode film does not occur, and since the electrode portion can be constructed with a sufficiently low electrical resistance value, it is possible to obtain a reproduced signal with a good C/N ratio. According to the present invention, the above-mentioned conventional problems can be satisfactorily solved.

[Brief explanation of the drawing]

Fig. 1 is a tuning curve diagram for explanation, Fig. 2a. Figure b is a distribution diagram of the amount of ion implantation, Figure 3 is a perspective view of a part of the regenerated needle of the present invention, Figures 4 a - d, and Figures 5 a and d are explanatory diagrams of the manufacturing process of the regenerated needle. It is. 1... Recycled needle body, 2... Sliding surface, 3
... Electrode formation surface, 4 ... Ion implantation layer, 5 ... Electrode coating, A ... Material of the recycled needle body.

Claims (1)

[Claims] 1. An electrode coating made of a conductive material is formed on the ion implantation layer exhibiting P-type or N-type conductivity formed on the electrode-forming surface of the regenerated needle body made of a highly hard material with wear resistance. A regeneration needle of a regeneration element that detects changes in capacitance value.