JPS58215287A - Fine working method - Google Patents

Abstract

PURPOSE:To etch away selectively the desired place of a desired material, by irradiating a laser beam of the wavelength at which the coefft. of light absorption for the work increases to the work in a corrosive atmosphere. CONSTITUTION:The work 2 coated with a thin film 2B on a substrate 2A is prepd. and is disposed in a chamber 1 filled with a soln. LC for etching. Laser light LB of the wavelength at which the coefft. of light absorption for the film 2B increases is irradiated to the prescribed part of the work 2. Then, a groove 5 is formed in the locus part of the film 2B irradiated with the laser light but the substrate 2A having a small coefft. of light absorption for the wavelength of the light LB is not etched at all. Only the desired material of the desired place is etched away selectively by making use of the difference in the intensity of the optical absorption in the above-mentioned way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microfabrication method, in particular in a workpiece consisting of two or more material regions with similar corrosion reaction rates.
The present invention relates to a microfabrication method for forming selective erosion removal areas only in selected material regions. The material regions may be layered regions that overlap one another, or interlocking regions arranged side by side in the horizontal direction.

Techniques for selectively removing desired materials at desired locations are important for the production of various devices.

In the past, many methods have been developed for this purpose, especially when the purpose is to selectively corrode only one of different substances that have similar reaction rates in a corrosive atmosphere. The process must be carried out by some method while constantly monitoring the corrosion state, which is extremely troublesome and has poor reproducibility.

The present invention was made to eliminate these drawbacks of conventional methods, and utilizes the differences in optical absorption strength of the substances that make up the sample to easily collect only the desired substance in the desired location. The purpose is to provide a method for selectively removing corrosion.

In line with the above objective, the present inventors irradiated a sample placed in a corrosive atmosphere with laser light and conducted various studies on the corrosion rate. This invention was completed after verifying that only the absorbed substances are selectively removed by corrosion.

FIG. 1 is a diagram of the principle of the apparatus for the method according to the invention. A corrosive atmosphere is created inside the container, and a sample λ as an object to be processed is placed.

If the sample consists of multiple material regions, and two or more material regions have similar reaction rates to a corrosive atmosphere, then corrosive processing is not applied to any of the material regions. The present invention is most effective when the sample is a sample that is easily exposed.

As shown in FIG. 2A, the structure of the material region group is a layered or laminated structure in which, for example, a second material region JB as a thin film is formed on a first material region ZA as a substrate. It may be a structure, as shown in Figure 2 BIC,
The first, second, and third material regions may be arranged side by side in a combination in the horizontal direction, or may have a layered structure as shown in FIG. It is also preferable that at least one of the layers has an interlocking structure. Of course, the number of types of material regions is not limited to the illustrated case, and may be larger.

For example, if among n types of material regions, m types of material regions (2<m<n) have approximately the same corrosion reaction rate, the present invention applies to these m types of material regions. This will be particularly effective.

Of course, it is easy to obtain the desired selective processing even without applying the present invention when the amounts of substances with significantly different corrosion reaction rates are used, but the present invention can also be applied between these types of substances, and further differentiate the corrosion rates. You can also do that.

Returning to the explanation of the apparatus, the light LB of the laser 3 is focused by a lens and irradiated onto the sample. The wavelength λ of the light LB of the laser 3 is
The wavelength should be one that is sufficiently strongly absorbed by the substance to be corroded and removed, and which is not absorbed by the substance that must not be corroded and removed.

By changing the optical output of the laser 3 and the distance of the lens ≠ from the sample λ, appropriately selecting the thickness and temperature of the part of the sample irradiated with light, the relative position of the light from the laser 3 and the sample λ is determined. move according to the desired pattern. In the above configuration, in the part of the sample λ that is irradiated with the laser beam,
The material to be corroded and removed absorbs the laser light, raising its temperature. Due to this temperature rise, corrosion progresses rapidly, and the material to be corroded and removed becomes thinner.As the thickness becomes thinner, the amount of light absorbed decreases and the temperature decreases, and all the material to be corroded and removed is removed. Corrosion will stop automatically.

A basic embodiment according to the present invention will be described with reference to FIG. 6.4 using specific material examples.

The sample as the workpiece used in this example! has the structure shown in FIG. 2A in which two types of material region layers λA and λB are polymerized, and the first to lower material region layers 2A are Gd,
Gα, 0□ substrate, and the second to upper material region, 2B, was epitaxially grown on the above substrate (YBi
) s (FgGα), 0. It is a thin film.

Therefore, in this example, for such a sample λ, a groove with the same depth as the film thickness of the - strip is formed only in the upper thin film λB,
The bottom of this groove shall be exposed without damaging the substrate surface.

As mentioned earlier, in the case of such groove processing, in the conventional technology, the thin film if3 is simply covered with a protective layer except for the area where the groove is to be formed, and then simply immersed in a corrosive atmosphere such as phosphoric acid. If substances such as 2A and 2B have similar reaction rates to phosphoric acid, even if a groove is formed that completely removes the thickness of thin film 2B, the subsequent corrosion of the substrate will automatically occur at that point. Therefore, in addition to the drawbacks mentioned at the beginning, there is also the problem that it takes a long time to process.

On the other hand, if the present invention is applied, as shown below, it will be the same as having a substantially or equivalently large reaction time difference between the two substances, and the processing speed will also be extremely increased, so that the equivalent In terms of processing time, it is possible to buy a large amount of time before corrosion starts to become a problem on the board, and it is possible to obtain almost the same effect as automatic stopping.

As schematically shown in Fig. 5A, a sample is placed in a sample chamber filled with phosphoric acid I (3PO4) as a corrosive solution Lc, and the configuration shown in Fig. 1 is adjusted to the required groove width. A predetermined portion of the sample 2 is irradiated with a laser beam LB that has been focused to a spot diameter of 100 nm through a window (not shown) above the sample chamber.

Of course, as is usually the case with this type of device, the sample is
It may be placed on a sample stage (not shown) that can move along each axis of the Y orthogonal axis and has good movement controllability.

The laser used in this example had a wavelength of 4BBnm and 515 nm.
This is an argon ion laser that emits a nm laser beam. Therefore, in sample λ, 53[]IL'1 of thin film 2B
The light absorption coefficient at 7L is about 5200 cm-', and that at substrate 2A is so small that it can be ignored.

Under the above conditions, the laser beam LB is focused by a lens with a focal length of 200 m placed at a distance of 206 m from the sample, and the relative position of this beam and the sample is adjusted at a speed of 5 μm on the sample surface. I moved it. When the sample was taken out of the container and observed under a microscope, it was found that a groove j was dug in the laser irradiated trajectory, as shown in FIG. 6B.

In order to verify whether or not this groove j satisfies the previously planned specifications, the thickness of the thin film 2B was measured in advance using an optical method, and the known value TA = 5.95 μm was known. The depth Tm of the groove j was measured.

Figure 4 shows this measurement result as a function of laser light output. When the laser light is weak, the thin film -! Corrosion removal has been completed halfway in the depth direction of point B, but as the laser beam becomes stronger, the groove depth Tm matches the thickness 1 of the thin film. No increase was observed.

Further, when the composition of iron, which is a component contained only in the thin film, was analyzed in the groove portion having a depth of 5.95 μm, no iron was detected. The above indicates that only the thin film that absorbs the laser beam was selectively corroded and removed by laser irradiation, and the purpose was achieved.

Furthermore, since the rising portion of the curve shown in Figure 4 can be seen to be relatively linear, the depth of the groove 5 formed in the thin film 2B can be adjusted to any desired depth with a degree of accuracy by adjusting the light intensity. It can also be as deep as .

Judging from the above examples, it is clear that the present invention can be similarly applied to other amounts of substances;
Good results can be obtained.

In this way, the present invention can greatly contribute to the formation of structural structures of various elements such as magnetic elements, semiconductor elements, and dielectric elements. Let me prove the magnitude of the ripple effect.

Closely related to, and directly directed to, the embodiments described above, the present invention can be readily applied to a method of measuring the thickness of a film formed on a substrate.

Various methods have been developed for measuring film thickness. One method is to measure film thickness using the property that light is reflected and interferes with the front and back surfaces of the film, but this method requires assuming the refractive index of the film, and the surface Applicable only to specular specimens. Also,
Another method is to obtain the film thickness by obliquely polishing the sample, but the disadvantages of this method are that it destroys a large part of the sample and is time-consuming.

On the other hand, if the present invention described above is used, a laser beam having a wavelength λ is selected such that the light absorption coefficient of the film to be measured is large and that of the substrate on which this film is mounted is small.
If a groove j is created in the film 2B to completely remove this film thickness using a power greater than that achieved by the above method, and the depth Tm of this groove j is measured using an existing roughness meter, etc., the result described above can be obtained. As shown in FIG. 4, this groove depth scale and the actual film thickness n match, so that accurate measurement can be easily performed.

However, although FIG. 6B shows an example in which the groove j is cut across the entire width of the sample λ in the X direction, the groove j is cut in order to measure the film thickness. , the length t may be sufficiently short < (L < tM)
In some cases, even a pinhole-like groove or hole without relative movement between the sample and the beam can be sufficiently applied to the roughness meter if the beam spot diameter is made slightly thicker. Note that known roughness meters have fairly high accuracy even on the μm order or less.

As described above, if the present invention is applied to film thickness measurement, there will be no drawbacks as in the conventional method, and simple and accurate measurement can be performed by simply destroying a minute area of the sample.

The present invention can also be applied to fabricating a low-loss fixed connector structure between a pair of optical fibers, optical fibers, or optical elements.

A method of simply and stably coupling an optical element and an optical fiber by propagating light through a film is an important technology for measurement and control systems using light.

However, conventionally, optical fibers and light-transmissive films such as YsFgsO□ have been mainly bonded by directly bonding the optical fibers to the end surfaces of the films.

However, the adhesive surface created by this method has low mechanical strength, and requires advanced technology to precisely align the tip of the optical fiber with the center of the thin film. Furthermore, in an optical element configured in such a way that light introduced into a film from an optical fiber is propagated through the film for a certain length, and then introduced into the optical fiber from the other end, the film is kept at a certain level along with the substrate. After cutting the fibers to a length, it was necessary to align the optical axes of a pair of opposing optical fibers so that their centers matched correctly and then bond them to the membrane, which required a lot of labor and skill.

On the other hand, if the present invention is applied and a guide groove for fixing the optical fiber is formed in the film, the fixed connection between the optical fiber and the film, the original fiber and the optical fiber, etc. can be easily performed, and the optical axis can be increased. It can be achieved with consistency.

This application example will be described in more detail with reference to FIG. 5 and subsequent figures, but here, as shown in FIG. The end of an output optical fiber (described later) is physically and optically coupled to the film lλB, and the end of the input fiber is aligned with the optical axis of the output fiber, while the film is similarly connected to the film lλB. Let's take as an example the case of combining.

In the application of the present invention, the substrate /, 2A, and the film lλB are as follows:
This corresponds to each layer 2A, 2B of the previous embodiment of the present invention.

If the correspondence with the sample is taken, the whole can be indicated by the reference numeral 7.2. Here, this is called the optical element base material 12, and this is the object to be processed in the applied process of the present invention.

The method of the present invention explained with reference to FIG. 5 was applied to the optical element base material /J, and the results are as follows:
Along the X-axis, a pair of grooves /j, each of length t, r tII, facing each other via a connection part λθ of intermediate length m, /
Create jB (Figure 5B).

In the manufacturing example of the present applicant, the laser beam from the argon ion laser is placed at an appropriate distance from the optical element base material /,2 soaked in phosphoric acid at a focal length of 20, which will be described later in relation to the spot diameter.
Focus with 0rn7/lrL lens, beam power 4W
The laser beam was moved at a relative velocity of 1 μmA at the membrane surface.

In Fig. 5B, if we consider the movement of base material /2 in the direction of arrow X, then after irradiating the beam a distance Htt from the tip edge of base material /2, The beam was interrupted, the parent phase was relatively sent for a length of 41 minutes, and the laser beam was irradiated again over a length of 28 minutes.

As a result, the membrane 12B has a pair of grooves /jA, /j
13 are formed sandwiching the intermediate connecting portion 0, and the bottom surface of each groove is flat with the surface of the substrate 2A exposed.
The axes of both grooves /j), , /JB in the X-axis direction completely or necessarily coincide with each other.

For each layer /J'A, 1Zf3 created in this way, respectively,
The core 2/B of an optical fiber with a length of t, , t3 or more, with the cladding 2/A stripped to expose the core and 2/B.
As shown in FIG. 5C, the core end surfaces are placed in contact with the inner end surfaces of each layer. During this operation, two suitable adhesives (FIG. 5D) are filled into each groove, and after curing, the fibers are fixed to the grooves. In addition, it is preferable to match the beam spot diameter when cutting the fiber to the core diameter of the optical fiber used to prevent lateral wobbling and to use the groove as a guide.

In this way, when the present invention is applied to important points, in both grooves/6,
/! The alignment of the optical axes of the optical fibers B can be performed easily and with extremely high accuracy, and therefore the alignment of the optical axes of both optical fibers using this as a guide can be satisfied without the need for troublesome work. Also, of course, membrane/2
When it is not necessary to propagate the light to f3 in the transverse force direction, for example, when optical coupling is performed only between the two fibers, the whole cladding is housed in the guide groove, and the length of the intermediate connecting part 2o is set to t.
, may be made sufficiently short, or in some cases, the end faces of both fibers may be directly connected to each other as cut-through grooves.In any case, it is highly versatile and can be applied to optical circuit technology.

The invention is also applicable to the formation of composite epitaxial films.

Epitaxial growth of films with different compositions on a single substrate is important for creating various devices with high functionality. For example, devices using garnet films are important as magnetic bubble memory devices, magnetic optical devices, etc., but conventionally, for this material, films that have been grown epitaxially are It was not possible to remove and re-expose the substrate.

On the other hand, by applying the present invention, it becomes possible to expose the substrate by etching away the formed garnet film, and then epitaxially grow a garnet film with a different composition on the substrate again. It becomes possible to grow multiple layers of garnet films with different compositions on a single substrate.

To explain this application example by giving a concrete example, Fig. 6A
GtlsG ((Y, Nrl) sF epitaxially grown on a LyO□ substrate 1 oaA) as shown in
e The present invention was applied to the member 102 having the 60tt film 101f3 as a workpiece, and the processing shown in the first drawing was performed as shown in the sixth drawing to selectively open the upper film 102B as shown in FIG. 6B. A hole or groove 103 is formed, and the surface of the substrate 101A is exposed at the bottom of the groove. Each layer is 10A.

10 pieces B are the first and second layers 2A of the basic embodiment of the present invention.

, will be treated as equivalent to 2B.

Specifically, the member 102 is immersed in a phosphoric acid solution in the sample chamber l (Figs. 1 and 3), and a laser beam LB from an argon ion laser with an output of 5 W is applied to the member 102 at 206 mA.
Light was collected and irradiated with a lens having a focal length of 200rn/rrL placed at a distance TL. The film absorbed about 90% of the laser beam energy. The light absorption of the substrate is so small that it can be ignored. When the laser beam was moved on the surface of the member 10 at a speed of 5 μm'r/s, a groove 101 with a width of about 200 μm and a depth of about 4 μm equal to the film thickness was obtained. surface was exposed. Part made like this/(1
7,2 by the usual liquid phase epitaxy method, (YB< )
When a (FgGα), 0□ film was grown, a good quality film io-〇 was obtained. That is, as shown in FIG. 6C, (YNd) a (FgGcL) is formed on the substrate 102.
There is a 5Ott film 102f3, and (YBi)s (Fg
Gcz) 50tt film 10C is grown to form a new member lθ
It forms a ko′.

As described above, by applying the present invention, by etching away the garnet film on the substrate, the surface of the substrate can be exposed, and the garnet film can be epitaxially grown on it again. Many films with different compositions can be fabricated at arbitrary locations on a single substrate.

This involves making use of the difference in light absorption coefficient between the newly grown film 10.2C and its underlying film 102f3 and the substrate 10A, and drilling a series of through holes in both films, followed by the same procedure. This means that the third and subsequent layers can also be grown from the substrate.

The member 102' constructed in this manner is given a useful function as a magnetic bubble storage element, a magnetic optical element, etc., and plays an active role, and ultimately benefits from the present invention.

As described in detail in each application example above, even if there are at least two material regions with similar reaction rates in a corrosive atmosphere, the It provides a method that can remove selective parts, has excellent workability, and is highly accurate, and its contribution to various technical fields is extremely high, and goes beyond the above application examples. . In addition, the laser beam is not limited to relative scanning as described above, but is also used for large-diameter laser beams with mask butter/
It can also be one with information.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of the apparatus used in the method of the present invention, FIG. 2 is an explanatory diagram of an example of the material region configuration of the workpiece, and FIG.
Figure 4 is an explanatory diagram of an example method of the present invention, Figure 4 is an explanatory diagram of an example of a processing result, Figure 5 is an explanatory diagram of each step in producing an optical device applying the present invention, and Figure 6 is an explanatory diagram of each process when creating an optical device applying the present invention. The figure is an explanatory diagram of each step when the present invention is applied to forming a composite epitaxial film. In the figure, yu, /ko, 101 is the workpiece, ;Ik, 2
B, /2A. 10B, 10C), 10B, 10C are each material region, 3 is the laser, j, /j, 103 is the removed part or groove or hole as a result of processing, Yl is the optical fiber, here is an adhesive. Fig. 1Q Fig. 2N Fig. 3, A) (B) Fig. 4 ε 0 1 2 3 4 (W) Leuri Panic (Samurai 2) Fig. 6 (A) Fig. 425-1 (D) ＼-mer 1

Claims (1)

[Claims] A microfabrication method for forming a removal portion of a material in a predetermined portion of a predetermined material region under a corrosive atmosphere, the method comprising: A microfabrication method characterized in that the predetermined section is irradiated with the laser beam using a laser beam having a wavelength of