JPH05194092A - Thin diamond film, its preparation and thermal head provided with the same thin diamond film - Google Patents

Abstract

PURPOSE:To provide a thin diamond film having good surface properties, its preparation and a thermal head provided with the thin diamond film. CONSTITUTION:A substrate is dipped in an organic solvent solution of an alkylchlorosilane (according to a substrate dipping process 1) and passed through a substrate drying process (2) and a substrate annealing process (3) into a film forming process (4) to form the objective thin diamond film. Thereby an organic solution of an alkylchlorosilane is treated with an enzyme on the substrate surface prior to lamination of the thin diamond film and an alkyl group is bound to the substrate surface. As a result, the affinity between the alkyl group and a hydrocarbon compound which is a raw material for carrying out CVD method is increased and formation density of a diamond crystal nucleus is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond thin film formed as a wear resistant layer, an insulating layer or a heat dissipation layer, a method for manufacturing the same, and a thermal head having the diamond thin film.

[0002]

2. Description of the Related Art In the field of electronics, a so-called hydrogenated amorphous carbonized thin film formed by a vapor phase growth method known as a CVD method using a hydrocarbon material is often called a diamond thin film. This diamond thin film has excellent properties such as hardness, thermal conductivity, and insulating properties, and various uses are considered by utilizing these properties. However, depending on the raw material gas and the conditions during film formation, The characteristics and surface properties of the film change.

As a method of growing such a thin film from the vapor phase, two methods, a hot filament CVD method and a plasma CVD method, are widely used. By the way, in the method for producing a diamond thin film of this kind, generally, the generation density of crystal nuclei necessary for starting the growth of the thin film on the substrate surface for forming the diamond thin film is low, and the surface property of the obtained diamond thin film is poor. was there.

In order to increase the generation density of the above crystal nuclei,
Although treatments such as scratching the underlying surface with diamond powder or roughening the surface with hydrofluoric acid are performed, even if the density of each can be increased, the diamond thin film deposited on the surface should be close to the mirror surface. I couldn't get it. Also,
A method in which a substrate is subjected to electropolishing in mineral acid to form innumerable projections and the surface is scratched with abrasive grains (JP-A-3-107460), or the substrate is processed in a methane atmosphere to form crystal nuclei Attempts have been made to increase the generation density (Koizumi, et al., "4th Microelectronics Symposium (MES'91) Lecture Collection", May 1991.
pp217-220), the surface property of the formed thin film is not sufficient.

[0005]

As described above, according to the prior art, even if the surface condition of the substrate on which the diamond thin film is to be formed is roughened to increase the density of each, the formed diamond is formed. There is a problem that the surface condition of the thin film cannot be made good. An object of the present invention is to provide a diamond thin film having a good surface property, a method for producing the same, and a thermal head provided with this diamond thin film.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted earnest researches on a method of forming a diamond thin film, and in particular, on improving the surface property of the formed diamond thin film. As a result, the generation density of crystal nuclei is increased and the thin film is increased. We have found a means to significantly improve the surface properties of. In order to achieve the above object, the present invention increases the crystal nucleus generation density by processing a substrate before vapor phase growth of a thin film using a CVD method or the like by a new method, and forms a diamond thin film after film formation. And a method for producing the same, and a thermal head provided with this diamond thin film.

As a specific treatment method for increasing the nucleation density according to the present invention, a hydrocarbon-based material which is a raw material for CVD is used by covering the surface of the substrate with an alkyl group with an organic solvent solution of dialkyldichlorosilane. This increases the affinity between the raw material and the surface of the substrate, and thereby increases the generation density of diamond crystal nuclei.

That is, the present invention is characterized in that it is formed by a film forming method using a hydrocarbon as a raw material on a substrate whose surface is treated with alkylchlorosilane and covered with an alkyl group. in the method for manufacturing a diamond thin film of depositing a diamond thin film, said prior to the deposition of the diamond film, the surface and the alkyl chlorosilane substrate having oxygen _{(R n Cl m Si: n} , m is an integer from 1 to 3 and, n + m = 4, R is an alkyl group C _x H _{2x + 1}
Where x is a positive integer), and a diamond thin film is formed on the substrate by a CVD method using a hydrocarbon as a raw material and a surface treatment step of binding an alkyl group to the substrate surface. And a film forming step of forming a film.

The film forming conditions by the above CVD method are as follows: DC electric field: ~ 200V / cm, reaction gas pressure: 20 ~ 200T.
orr, substrate temperature: 800 to 900 ° C. Also,
According to the present invention, a plurality of drive electrodes, a common electrode formed so as to face the drive electrode, a heating resistor formed between the common electrode and the driving electrode, and at least the heating resistor are covered. In a thermal head including a heat-resistant protective layer containing oxygen, alkylchlorosilane (R _n Cl _m Si: n, m is an integer of 1 to 3) is formed on the surface of the heat-resistant protective layer.
And n + m = 4, R represents an alkyl group C _x H _{2x + 1} , x
Is a positive integer), and a wear resistant layer composed of a diamond thin film formed by a CVD method using a hydrocarbon as a raw material after the alkyl group is bonded to the surface is reacted. Characterize.

The organic solvent for the alkylchlorosilane is not particularly limited as long as it can dissolve the alkylchlorosilane. And, as a raw material of the diamond thin film in the CVD method, methane is mainly used.

[0011]

According to the above-described structure of the present invention, the organic solution of alkylchlorosilane is reacted with the enzyme on the substrate surface to bond the alkyl group to the substrate surface prior to the lamination of the diamond thin film, and the alkyl group and the CVD method. The affinity with the hydrocarbon compound, which is the raw material, increases, and the diamond crystal nucleus generation density increases.

By forming the diamond thin film as the wear-resistant layer of the thermal head on the upper layer of the heat-resistant protective layer, a wear-resistant layer having excellent surface lubricity can be obtained. The life can be dramatically improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for producing a diamond thin film according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a process diagram for explaining a method for forming a diamond thin film according to the present invention, in which 1 is a substrate dipping process in a processing liquid, 2 is a substrate drying process, 3 is a substrate annealing process, and 4 is a film formation on a substrate. Steps 1 to 3 are substrate pretreatment steps.

In the figure, first, the following processing is performed on a silicon (Si) substrate having a natural oxide film formed on its surface. Preparation of treatment liquid Dimethyldichlorosilane: 2%. Benzene: 98%.

[0015] The substrate was immersed in adjusted treatment solution as pretreatment above substrate and left to stand for 2 hours. --- Substrate soaking step (1) After that, pull out the substrate from the above treatment liquid and perform 1
Dry for 5 minutes. --- Substrate drying step (2) Anneal the dried substrate at 200 ° C for 1 hour.

Substrate annealing step (3) By the above treatment, the hydroxyl group (-OH) or oxygen atom (O) bonded to silicon (Si) on the substrate surface completely reacts with silicon in dimethyldichlorosilane. Then, only the methyl group (CH ₃ ) bonded to silicon is present on the surface of the substrate. The above reaction is as follows. It is considered to occur as shown in the reaction formula.

2-Si-OH + (CH ₃ ) ₂ Cl ₂ Si → (-Si-O-) ₂ Si (CH ₃ ) ₂ + 2HCl film-forming treatment As a method for growing a diamond thin film on the substrate thus treated, Hot filament CVD method and plasma CVD
Two of the laws are widely used.

In this embodiment, the direct current CVD method using direct current discharge is adopted in order to increase the density of crystal nucleus generation. Figure 2
FIG. 1 is a schematic configuration diagram of a DC CVD film forming apparatus used in this embodiment, 20 is a CVD chamber, 21 is a cathode, 22 is an anode, 23 is a plasma region formed between the cathode and the anode,
24 is a substrate on which a film is formed, 25 is an observation window, 26 is a DC power supply, 27 is a reaction gas introduction pipe, and 28 is a reaction gas exhaust pipe.

In the figure, a substrate 24 is placed on the anode 22, and the substrate 24 can be independently heated by a heating means (not shown). The distance between the anode 22 and the cathode 21 is 2-3 cm, and the cathode 21 is heated to 1000 ° C to 1200 ° C during the formation of the diamond thin film. This heating temperature is necessary in order to avoid the deposition of amorphous carbon on the surface of the cathode 21 and stabilize the discharge.

The reaction gas introduced from the reaction gas introducing pipe 27 into the CVD chamber 20 is hydrogen (H ₂ ) containing 0.5% to 2% of methane (CH ₄ ). The reaction gas is discharged by the DC voltage applied from the DC power supply 26 to the cathode 21, and plasma is generated between the cathode 21 and the anode 22. The reaction gas pressure during this discharge is 50 To
It is about rr.

The temperature of the substrate 24 is monitored by an infrared radiation thermometer, and the diamond film is deposited in the range of 800 ° C to 900 ° C. The diamond thin film thus deposited has a surface irregularity of about 20 nm for a thickness of 1 μm, which is extremely excellent in surface smoothness. In this example, dimethyldichlorosilane was used as the alkylchlorosilane that was the substrate treatment liquid.
The present invention is not limited to this, and is generally R _n Cl _m Si (R is an alkyl group, including diethyldichlorosilane,
n and m are integers from 1 to 3, and alkylchlorosilane represented by n + m = 4) can be widely used.

Next, an embodiment of a method of manufacturing a thermal head to which the diamond thin film forming method of the present invention is applied will be described. FIG. 3 is a structural diagram of a main part of a thermal head in which a wear-resistant layer is formed on a heat-resistant protective layer by using the method for forming a diamond thin film according to the present invention. 31 is an insulating substrate made of glass or ceramics, and 32 is an insulating substrate. A glass heat storage layer, 33 is a common electrode, 34 is an individual electrode, 35 is a heating resistor, 36 is a heat resistant protective layer made of glass or the like, and 37 is a wear resistant layer made of a diamond thin film.

In the figure, a diamond thin film 37 according to the present invention is formed as a wear resistant layer formed on the surface of the heat resistant protective layer 36 covering the heating resistor 35. By providing this diamond thin film 37, it is possible to obtain a long-life thermal head having a wear-resistant layer having excellent surface smoothness.
4 to 7 are process explanatory views for explaining the method of manufacturing the thermal head according to the present invention, and the same reference numerals as those in FIG. 3 correspond to the same portions.

First, as shown in FIG. 4, an insulating substrate 31 made of an insulating material such as alumina is prepared. A glass paste made of a glass-based material is applied to the surface of the insulating substrate 31 and baked to deposit the glass heat storage layer 32. Next, for example, a metal organic paste (metalloorganic gold paste) containing gold (Au) as a main component is solid-printed and fired to form a gold conductor film. A photoresist is applied onto the gold conductor film, dried, and then exposed and developed through a photomask to expose unnecessary portions of the gold conductor film.
The exposed gold conductor film is etched with, for example, an iodine-potassium iodide aqueous solution to obtain a common electrode 33 and an individual electrode 34.

As shown in FIG. 5, a ruthenium oxide-based thick film resistor paste is printed in a strip shape across the common electrode 33 and the individual electrode 34 formed in the step of FIG.
The resistor 35 is formed by drying at 30 ° C. and firing at a peak temperature of 800 ° C. Next, as shown in FIG. 6, a glass paste is printed on a 400-mesh screen by covering the whole of the resistor 35 and the common electrode 33 and the individual electrodes 34 excluding the wiring pad portions (not shown). The glass protective layer 36 is formed by firing at a peak temperature of about 800 ° C.

Finally, as shown in FIG. 7, the glass protective layer 36 was dipped in a benzene solution of 2% dimethyldichlorosilane, left for 60 minutes, then left at 80 ° C. for 15 minutes, and then at 200 ° C. for 1 minute. Let dry for an hour. Then, a 0.5 μm diamond thin film is formed by DC discharge plasma CVD. The wear-resistant layer 37 of the thermal head formed in the above step was
Only wear below the measurement limit was observed. As a result, a thermal head having excellent wear resistance and improved surface smoothness could be obtained.

[0027]

As described above, according to the present invention,
By treating the substrate surface to be formed with alkylchlorosilane and then forming a diamond thin film by the CVD method, it can be used as an insulating layer, heat conduction layer or wear resistant layer in the electronics field, and it has a dense and good surface property. A simple diamond thin film can be easily manufactured.

By increasing the generation density of diamond crystal nuclei, it is possible to form a dense diamond thin film having good surface smoothness. Further, by forming this diamond film on the protective film of the thermal head, the wear resistance of the thermal head is remarkably improved, and the life thereof is dramatically increased.

[Brief description of drawings]

FIG. 1 is a schematic process diagram illustrating an example of a method for producing a diamond thin film according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a DC CVD film forming apparatus used in this embodiment of the present invention.

FIG. 3 is a structural diagram of a main part for explaining an example of a thermal head in which a wear resistant layer is formed on a heat resistant protective layer by using the method for forming a diamond thin film according to the present invention.

FIG. 4 is an explanatory diagram of a partial process for explaining a method of manufacturing a thermal head according to the present invention.

FIG. 5 is an explanatory diagram of a partial process for explaining a method of manufacturing a thermal head according to the present invention.

FIG. 6 is an explanatory diagram of a partial process for explaining a method of manufacturing a thermal head according to the present invention.

FIG. 7 is an explanatory diagram of a partial process for explaining a method of manufacturing a thermal head according to the present invention.

[Explanation of symbols]

1 Substrate soaking step 2 Substrate drying step 3 Substrate annealing step 4 Deposition step 20 Deposition chamber 21 Cathode 22 Anode 23 Plasma generation region 24 Substrate
25 Observation Window 26 DC Power Supply 27 Reactive Gas Introducing Tube 28 Reactive Gas Exhaust Tube 31 Insulating Substrate of Thermal Head 32 Glass Heat Storage Layer 33 Common Electrode 34 Individual Electrode 35 Heating Resistor 36 Glass Protecting Layer 37
Wear resistant layer consisting of diamond thin film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23C 16/02 7325-4K 16/26 7325-4K

Claims (3)

[Claims] 1. A diamond thin film formed on a substrate, which is treated with alkylchlorosilane and whose surface is covered with an alkyl group, by a film forming method using hydrocarbon as a raw material. 2. A method for producing a diamond thin film, comprising forming a diamond thin film on a substrate having oxygen on its surface, wherein the surface of the substrate having oxygen and alkyl chlorosilane (R _n Cl _m Si:
n and m are integers from 1 to 3, and n + m = 4, R represents an alkyl group C _x H _{2x + 1} , and x is a positive integer. A method for producing a diamond thin film, comprising: a surface treatment step of bonding a group; and a film forming step of forming a diamond thin film on the substrate by a CVD method using hydrocarbon as a raw material. 3. A plurality of drive electrodes, a common electrode formed so as to face the drive electrodes, a heating resistor formed between the common electrode and the driving electrode, and at least this heating resistor is covered in plural layers. And a heat-resistant protective layer containing oxygen, wherein the surface of the heat-resistant protective layer is alkylchlorosilane (R _n
Cl _m Si: n, m is an integer from 1 to 3, and n + m =
4, R represents an alkyl group C _x H _{2x + 1} , and x is a positive integer), so that an alkyl group is bonded to the surface to cause CV to be a hydrocarbon-based raw material.
A thermal head comprising a wear resistant layer made of a diamond thin film formed by the D method.