WO1991009994A1

WO1991009994A1 - Method of forming material layer

Info

Publication number: WO1991009994A1
Application number: PCT/JP1989/001307
Authority: WO
Inventors: Junji Nakata
Original assignee: Shindaigo Co., Ltd.
Priority date: 1989-12-26
Filing date: 1989-12-26
Publication date: 1991-07-11
Also published as: JPH03197389A

Abstract

This invention relates to a method of forming a layered material. It aims at forming a material layer such as diamond carbon without the necessity of the ''reduced pressure and vacuum'' conditions. For this purpose, the ''ablation plume'' generated by irradiating the base material with a pulsed laser beam is fixed and crystallized on a material to be processed. The effect of the air is removed by the ''push-out effect'' of the ''ablation plume'' against the air, presumably making it possible to form a material layer in the open air of ordinary pressure. This method is suited for forming, for example, a diamond carbon layer.

Description

Specification

Method of forming material layer

〔Technical field〕

The present invention relates to a method for forming a substance layer for forming a substance, for example, diamond-like carbon, on a surface of an object to be treated in a layered manner.

(Background technology)

Various methods for forming such a material layer have been conventionally known. For example, electrolytic plating, vacuum deposition, and chemical vapor deposition (CVD).

Looking at the technology related to the formation of a diamond-like carbon thin film from among such various conventional technologies, for example, Japanese Patent Publication No. 58-25041, Japanese Patent Publication No. 62-7262, 5 7-6 1 6 4 4

No. 1-201, 693, JP-A-62-27095, JP-A-63

-2 8 8 65, JP-A-63-111 2497, JP-A 1-8'7

Many are known, such as 7776.

By the way, all of these conventional techniques require a vacuum condition, or a combination of a plurality of different means such as treatment with an energy source such as a laser beam and reprocessing with an ion beam or the like. Is what it is. However, each of these various conditions is a major constraint on the industrial application of the technology.

In view of such conventional circumstances, the present inventor has repeatedly studied the possibility of forming a material layer, specifically, a diamond-like carbon layer, on an object to be treated even under atmospheric pressure. And the result is the invention provided here. [Disclosure of the Invention]

In the method of forming a material layer according to the present invention, the base material is irradiated with laser light, and ions in the plasma generated by the irradiation are fixed and crystallized on the object to be processed. The laser light used at this time is pulsed. To irradiate.

According to this method, for example, a diamond-like carbon layer can be formed on an object to be treated even in a normal pressure atmosphere. In addition, the formation speed is remarkably higher than that of the above-mentioned prior art. It is not always clear why the method according to the invention of pulsing and irradiating laser light makes this possible. However, under the condition of a rather probable guess, the following can be considered.

That is, by pulsing and irradiating a laser beam, a high density and high speed plasma of ions called "ablat ion plume" can be generated from the base material. Due to its high density and high speed, the abrasion plummet has a "push-off effect" against air, that is, it is almost completely eliminated, so that it does not mix with air even in air. An effect is exhibited, whereby a high-density and high-purity state of ions for forming a layer can be obtained. In other words, by forming an abrasion plume by irradiating a pulse of laser light, the effect of air can be almost completely eliminated, and therefore, it is possible even in air.

In order to efficiently generate such ablation plumes, the laser beam is irradiated with a pulse that is a square wave with a rise time of 0.5 msec (500 ^ sec) or less and a pulse width of 100 msec or less. To do Is preferred.

This method of forming the material layer is more preferable when a solid material is used as the base material. That is, the abrasion plum can be generated more efficiently because the base material is a solid material.

This material layer can be formed by using a transparent material for laser light as a processing target, and irradiating the base material with laser light by transmitting the transparent processing target. It will be efficient. The reason is considered to be as follows under the same conditions as in the above-described laser beam pulsing.

In other words, the laser light transmitted through the object to be processed acts to maintain the plasma temperature by reheating the ablation plume coming toward the object to be processed, and is fixed and crystallized on the object to be processed. Heating the substance acts to promote its crystal growth, and such a double operation results in excellent production efficiency.

In the method of forming this material layer, a diamond-like carbon layer can be formed by using a high-purity carbon plate as a base material. [Brief description of drawings]

FIG. 1 is a diagram showing an irradiation state of laser light in a method of forming a material layer according to the present invention, FIG. 2 is a schematic diagram of a plum, and FIG. 3 is a process in a state where a seed crystal is fixed. FIG. 4 is a diagram of a processing object in a state where a material layer is formed, FIG. 5 is an explanatory diagram of a relationship between a pulse and a phenomenon, and FIG. 6 is a diagram of the object. FIG. 7 is a view of an object to be processed in a state in which a material layer having a file-like surface is formed. FIG. 7 is a view showing a laser beam irradiation state according to another embodiment; The figures each show a diamond formed by the method of the present invention. It is a photograph of the crystal structure of a Mondo-like carbon layer.

[Mode for Carrying Out the Invention]

Hereinafter, an embodiment of the method for forming a material layer according to the present invention will be described. A YAG laser (wavelength: 1.06 im) was used as a laser beam, and the laser beam was irradiated in a pulsed manner. Here, the pulse is preferably a square wave having a rise time of 0.5 msec (500 ^ sec) or less and a pulse width (pulse duration) of 100 msec or less. The processing object used is a glass plate, which is transparent to the YAG laser. The base material is a solid plate made of calcined carbon with a purity of 99%.

The processing method under the above conditions is as shown in FIG.

That is, a laser beam 1 from a laser oscillator (not shown) is condensed by a lens 2, and the laser beam 1 is transmitted through a glass plate 3, which is an object to be processed, and is irradiated on the surface of a base material 4. At this time, the laser beam 1 is focused on the surface of the base material 4 as far as possible.

From the base material 4 irradiated with the laser beam 1, "ablation plume" (hereinafter simply referred to as "plume") is generated at each rising edge of each pulse. This plume 5 is ejected at high speed from the base material 4 by a phenomenon called “ablation” generated by irradiation of the pulsed laser light 1, and is composed of carbonized plasma and carbon ions ( C +, C ", etc.) at a high density and high purity. Here, in order to make the Plum 5 faster, the" explosion "should be generated more efficiently. It is preferable that the base material 4 is a hard solid material in order to efficiently produce the plum _(see FIG. 2 which schematically shows an image of the plume 5 obtained by computer processing, (Coarse and dense) corresponds to temperature However, as you can see, there are several hot spots that appear darker in the vertical direction. This is considered to indicate a state in which the high-temperature plume 5 generated from the surface of the base material 4 once cools down while rising, is re-heated by the laser beam 1, and becomes high in temperature again. In this way, when the plum 5 is reheated with the laser beam 1 and the seed crystal is fixed to the glass plate 3 as described later, it is necessary to maintain the high-temperature state of the plum 5 as much as possible. Produces more favorable results for crystal formation. In other words, the base material 4 is irradiated with the laser beam 1 so that the plum 5 is generated in a direction opposite to the irradiation direction of the laser beam 1, so that the generated plum 5 can always be heated by the laser beam 1. Is a more favorable condition.

The carbon ions in the plume 5 collide with the glass plate 3 and first form a seed crystal 7 (FIG. 3) on the surface of the glass plate 3. Since the seed crystal 7 has poor transmittance of the laser beam 1, it absorbs the laser beam 1 passing through the glass plate 3, and is heated by the laser beam 1 to form a uniform crystal 8, that is, a diamond-like carbon layer 8. And grow (Fig. 4).

The relationship between the phenomena and the pulse during this period is thought to be that plume 5 occurs at the rise of the pulse, and reheating and seed crystal heating are performed during the duration of the pulse (Fig. 5).

If the pulsed laser light 1 is further irradiated, the uniform crystal 8 transmits the laser light 1, so that “plum 5 generation → seed crystal 7 formation on crystal 8—addition of uniform crystal 8 This phenomenon is repeated for each pulse, and the diamond-like carbon layer 8 having a desired thickness is grown and formed. .

In laser light with a pulse width of 9 ms ec and an energy of 25 Joule pulses, the size of the crystal formed per pulse , With its thickness of about 1 7 / m before and after the area of about 3 mm ² rarely before and after.

Here, it is also possible to stop the growth of the crystal 8 in an appropriate state and form a diamond-like carbon layer 8s having a file-like surface as shown in FIG. Such a diamond-like carbon layer 8 s is suitable for a cutting tool or the like.

A major advantage of this method is that a layer of material, such as a diamond-like carbon layer, can be formed easily and at a much higher speed in conventional atmospheres than conventional methods. However, the reasons why this is possible are beyond the scope of the preceding explanation. However, empirically, the following points can be said.

The distance between the glass plate 3 and the base material 4 is involved in the growth and formation of the diamond-like carbon layer while correlating with the pulse width, pulse power, pulse energy, and the like. For the time being, for a pulse width of 9 msec and an energy of 25 joules, a result of 1.5 to 3 cm is preferred, but this is naturally due to differences in pulse width and the like. Will change. This is probably because the distance between the glass plate 3 and the base material 4 is related to the temperature of the plume 5 colliding with the glass 扳 3, the concentration and purity of the carbon ions at that time.

Adjustment of the pulse width also affects the growth and formation of the diamond-like carbon layer. Specifically, if the pulse width is too narrow, the efficiency of growth and formation will be poor, and if it is too wide, the pulsing effect will decrease. For these reasons, the upper limit of the pulse width is about 100 msec, and the lower limit is about 0.2 msec. .

Adjustment of the energy level of the laser beam also affects the state of formation of the crystal (material layer). The size and the state can be arbitrarily controlled to some extent. Preferred energy levels include 1 to 100 joule nopulses.

As can be seen from the above description, this method has the elements of pulsing laser light, reheating the plum, and growing the seed crystal by laser light heating. These elements are not always realized only in the configuration as in the above embodiment. In other words, as shown in Fig. 7, this can also be realized by using a plurality of laser beams 1 and using each of the laser beams 1 to generate the plume 5, reheat the plume 5, and heat the seed crystal. It is possible. Of course, in this case, it is sufficient to pulse only the laser light for generating the plume. The advantage of such a configuration is that a material layer can be formed on the processing object 9 that is not transparent to the laser beam 1.

In the above embodiment, a YAG laser is used as a laser beam, but other laser beams can of course be used. Particularly, in the case of C 0 ₂ lasers, because it has a pair permeabilized in silicon crystal or germanium crystals, such as chromatic advantage for processing of semiconductor substrates.

In the above embodiments, carbon was used as the base material, and the diamond-like carbon layer was formed on the object to be processed. However, the method of the present invention is not limited to this, and an appropriate base material may be used. Of course, depending on the choice, it can be applied to various substances.

Further, the present invention is characterized in that the treatment can be performed in the atmospheric pressure atmosphere, but this does not necessarily mean that the treatment is performed in the atmospheric pressure atmosphere. That is, the method Combining with a reduced-pressure atmosphere or a specific gas atmosphere that is less affected by air enables formation of a higher-quality material layer.

'As can be understood from the above description, the method according to the present invention also has a feature that a necessary material layer can be formed while precisely controlling its forming range and thickness. Such features provide enormous advantages when applied to, for example, semiconductor manufacturing. For that purpose, for example, the following method can be applied. That is, first, an insulating layer composed of a diamond-like carbon layer as described above is formed using a carbon solid plate as a base material. Next, using a solid plate of arsenic (A s) in addition to a carbon solid plate as a base material, carbon plasma and arsenic plasma are generated in a mixed state, and a diamond-like carbon layer containing arsenic as an impurity is formed as an N layer. I do. Furthermore, a gallium (Ga) solid plate is used as a base material in addition to a carbon solid plate, and carbon plasma and gallium plasma are generated in a mixed state, and a diamond-like carbon layer containing gallium as an impurity is formed as a P layer. I do. In forming each of these layers, a slit member for controlling a range (area) of the plum reaching the substrate (the object to be processed) is appropriately used, and a range of the material layer fixed and crystallized on the object to be processed is used. The PN junction is formed by controlling arbitrarily.

[Industrial applicability]

The method of forming a material layer according to the present invention is to irradiate a laser beam into a base material by pulsing a laser beam. Thus, even in a normal-pressure atmosphere, for example, a technology for practical use has been sought for a long time. It enables the formation of a diamond-like carbon layer. Moreover, reducing the constraints on industrialization simply by enabling it in atmospheric pressure atmosphere 'a——

Needless to say, the processing means itself is simpler than the conventional technology, and the formation speed of the diamond-like carbon layer is much higher than that of the conventional technology. This greatly contributes to the industrial use of diamond-like carbon layers, which are expected to be used in various applications, including carbon dioxide.

Claims

The scope of the claims

(1). A method of forming a material layer by irradiating a base material with laser light and fixing and crystallizing ions in the plasma generated by the irradiation on an object to be processed. Forming a material layer.

(2). Claims characterized in that the pulse is a square wave with a rise time of 0.5 msec (5 '0 zsec) or less and a pulse width of 100 msec or less (1). The method for forming a material layer according to the above.

(3). The method according to claim 1, wherein the base material is a solid material.

(4). The method according to claim 1, wherein the object to be processed is transparent to laser light, and the base material is irradiated with laser light by transmitting the transparent object to be processed. The method for forming the material layer.

(5) The claim according to any one of claims (1) to (4), wherein the base material is a high-purity carbon solid material, and the substance layer formed is a diamond-like carbon layer. Method of forming a material layer.