JPS6011104B2 - Gas phase plating method - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in vapor phase plating methods.

Conventionally, in gas phase plating, it is common to heat the object 3 to be plated from the outside of the reaction tube 2 using a tube furnace 1 as shown in FIG.
The reaction occurs near the inner wall of the paper, the density of the paper decreases, and the rate of adhesion of the paper to the object 3 to be plated decreases.

For example, in the case of titanium tetrachloride, the optimal temperature for vapor phase plating is 9
00-1200°C, Tic 14 12 days 2900-1200 due to the reduction reaction with hydrogen of the carrier gas.

Titanium is precipitated by a reaction called 〇Ti-HCl HCI, and as the reaction progresses, the partial pressure of the titanium tetrachloride paper decreases and the partial pressure of hydrogen chloride increases. As described above, when the reaction tube 2 is heated from the outside by the tube furnace 1, the temperature of the region a near the inner wall of the reaction tube becomes higher than that of the region a2 near the object to be plated in the center of the tube. Therefore, the paper source reacts in area a, and the object to be plated cannot be plated efficiently. In addition, in the flow type reaction tube, a large number of objects to be plated 3, 32, 38... as shown in FIG.
......3n are arranged in the axial direction of the reaction tube 2 and the paper is flowed in the direction shown by the arrow, as shown schematically in Fig. 3, the paper gradually flows from the vicinity of the paper inlet 4. The density decreases, and the thickness of the deposited film decreases from 3 to 3.
It becomes thinner as it approaches n and exit 5.

The error in film thickness varies depending on various conditions, but is usually said to be 40 to 60%. Therefore, for products that require accurate film thickness, in the mass production process using reaction tubes as shown in FIG. 2, there are few products that fall within the allowable error range, and the yield is extremely poor. For example, in TIC coating on throwaway chips,
5 The thickness of the Buddha is considered to be appropriate, but the tolerance is ±10%.
Therefore, it is inappropriate to perform plating using the above-mentioned mass production process. In order to solve the above-mentioned problems, the present invention efficiently distributes the object to be plated in an area where the paper source is heated to the optimum temperature for vapor phase plating by a heating element arranged in the center of the reaction vessel. The purpose of the present invention is to provide a method for efficiently performing plating with a substantially uniform film thickness by performing vapor phase plating with minimal film thickness errors in mass-produced vapor phase plating.

Further, a temperature distribution substantially equivalent to that obtained by the heating element placed in the center of the reaction vessel can also be obtained by high frequency heating. In fact, when the object to be plated placed in the center of the reaction tube is heated by high-frequency heating, the deposition rate is much faster than when the object is heated from the outside of the reaction tube using a tube furnace. This proves that placing the heating element in the center of the plate is effective for efficient vapor phase plating. However, when high frequency heating is used, vapor phase plating cannot be performed on non-magnetic materials such as 18-8 stainless steel, molybdenum, and porcelain.

Furthermore, if the shape is somewhat complex, the temperature will be uneven, making it impossible to plate it in some cases. The present invention solves the drawbacks of using high-frequency heating, and provides a method that allows vapor phase plating to be performed using a simple device without being constrained by the material, shape, size, etc. of the object to be plated. That is.

That is, in the present invention, a heating element is disposed in the center of a reaction vessel, and an object to be plated is placed in a reaction temperature region through which vapor phase plating is formed in the reaction vessel by heating with the heating element, and A vapor source is supplied to the vaporization temperature region of the paper source that is formed around the paper source, and a plating film is deposited on the object to be plated in the above reaction temperature region.The reaction product is then deposited inside the reaction temperature region. It is characterized by being discharged from.

To explain more specifically, in the present invention, as shown in FIG. The inside temperature can be raised to a temperature suitable for the reaction of the paper source, and the paper source is supplied from the surroundings of this reaction vessel 10, and the object to be plated is placed inside the reaction vessel 10. When plating is performed using plating, it is necessary to change the temperature range from 1 to the vaporization temperature range of the outermost layer where the vapor source evaporates;
There is a discharged component region in the innermost layer where the density of reaction products that do not contribute to plating is high and the partial pressure of the paper source is reduced. Plating can be performed extremely efficiently and with a substantially uniform film thickness.

The vapor phase plating method of the present invention can be applied to barrel-type or batch-type plating, and may be either vertical or horizontal plating. Furthermore, without providing a separate vaporization chamber for the paper source, it is also possible to directly supply the paper source to the vaporization temperature region within the reaction vessel and vaporize it. FIG. 5 shows an example of a barrel type vapor phase plating apparatus for carrying out the method of the present invention.

In this vapor phase plating apparatus, a cylindrical reaction vessel 10
is supported by struts 12, and a protective tube 13 containing a heating element 11 is fixed in the center of this reaction vessel 10,
A supply pipe 14 for supplying a paper source together with a carrier gas is connected to the periphery, and a rotary barrel 16 with holes for accommodating an object to be plated 15 is rotatably supported around the heating element 11.

The rotating barrel 16 has its drive shaft 17 airtightly led out from the reaction vessel, and a pulley 18 for rotational driving is fixed thereon.
Further, the support shaft 19 at the other end is formed into a hollow cylindrical shape, and the inside of the support shaft is connected to a discharge pipe 20 for discharging discharge components including high-density reaction products from the center of the rotating barrel 16 to the outside.
Inside the rotating barrel 16, there is a cylindrical blade plate 21 for holding the object 15 to be plated as required.
can be provided. The power source 22 connected to the heating element 11 detects the temperature near the rotating barrel 16 with a thermocouple 23 and is controlled by a temperature regulator 24 so that the temperature is at an appropriate temperature. As a result, the vaporization temperature region A is formed between the peripheral wall of the reaction vessel 10 and the rotating barrel 16, and a reaction temperature region A is also formed in the vicinity of the object to be plated 15 within the rotating barrel 16.

In the figure, 25 is a rubber seal, 26 is a heat insulating material, 27 is an exhaust pipe connected to a vacuum pump to exhaust air from the reaction vessel during plating, and 28 is a thermometer for measuring the temperature of the paper vaporization area. .

Further, FIG. 6 shows an example of a batch type vapor phase plating apparatus for carrying out the method of the present invention, in which a heating element 31 connected to a power source (not shown) is disposed in the center of the reaction vessel 30. A supply pipe 32 for supplying the paper source together with a carrier gas is provided at one end, and from this supply pipe 32 a passage 3 forming a vaporization temperature region A around the reaction vessel 30 is provided.
3, and the material to be plated 3 is connected to the reaction temperature region inside the vaporization temperature region.
The end of the reaction vessel 30 is arranged such that a teaching table 35 having a heating element 4 is disposed in a row, and an exhaust component containing a high-density reaction product is discharged from a space between the training table 35 and the heating element 31. A discharge pipe 36 is connected to. Note that, similarly to the apparatus shown in FIG. 5, a thermocouple and a temperature regulator can be provided to control the power supply so as to maintain the temperature inside the reaction vessel 30 appropriately. According to the method of the present invention detailed above, the object to be plated is placed in a reaction temperature range suitable for vapor phase plating using an extremely simple device, and the deposition rate is the same as when using high frequency heating means. This makes it possible to perform vapor phase plating efficiently, and it is also possible to perform vapor phase plating with a substantially uniform film thickness regardless of the material, shape, and size of the material to be plated.

Regarding the uniformity of film thickness when performing vapor phase plating based on the present invention, the following experimental results were obtained.

In carrying out the present invention, it is necessary to arrange a heating element in the center of the reaction vessel and place the object to be plated around it. It is necessary to use a large device equivalent to a machine, and therefore implementing it on a laboratory scale poses various practical problems, such as the need for a high-output power source. Therefore, here, miniaturization of the experimental apparatus was considered within a range that would not pose a problem in confirming the quality of film thickness uniformity. The experimental apparatus had a structure as shown in FIG.

That is, both ends of a glass reaction tube 40 having an inner diameter of 4 mm and a length of approximately 1 skin are closed by sealing members 41 and 42, and a 1. A molybdenum wire 45 having a length of 90 mm was stretched on the side, and this was used as the object to be plated. In this case, since the diameter of the pipe 40 is small, the diameter of the discharge pipe 48 is even smaller, and it is difficult to separately install a heating element of a predetermined capacity therein. By energizing the molybdenum wire itself through power sources 43 and 44, it is possible to control heating to a predetermined temperature. The red-hot molybdenum wire is considered to be equivalent to the molybdenum wire heated by the heat from the heating element provided in the discharge pipe 48, as will be described later. Reference numeral 46 indicates a paper inlet pipe for supplying plating paper, and reference numeral 47 indicates a paper outlet pipe.The paper outlet pipe 47 has an inlet pipe 46 extending in the axial direction of the reaction tube 40 in close proximity to and parallel to the molybdenum wire 45. A reaction gas discharge pipe 48 was installed to reach the vicinity of the reactor.

This reaction gas discharge pipe 48 is connected to the reaction gas inflow hole 4 on the second side.
9 were drilled at intervals of two capes. In the above device, when the molybdenum wire 45 as a heating element is energized to generate heat, a reaction temperature region is formed around the molybdenum wire 45, and a vaporization temperature region is further formed outside the region.

This means that the molybdenum wire 45, ie, the object to be plated, is placed in the center of the reaction temperature region. When the plating paper is supplied to the vaporization temperature region from the paper inlet pipe 46, it reaches the reaction temperature region around the red-hot molybdenum wire 45, and the plating paper vaporized in that region undergoes a vapor phase plating reaction on the surface of the molybdenum wire 45. Thereafter, the reaction product diffuses from the surface of the object to be plated, flows into the reaction gas discharge pipe 48, and eventually flows out from the paper outlet pipe 47. Therefore, the above-mentioned apparatus has the fifth feature in that the heating element and the object to be plated are the same, and the reaction products are discharged from around the object to be plated.
Although different from the devices shown in FIGS.
In terms of forming the required temperature range, both devices can be said to be equivalent in principle.

In other words, even if the same heating element and the object to be plated are used, the difference is only in the heating method, and in any case, the reaction temperature region is near the object to be plated, and the vaporization temperature region is outside it. and are technically equivalent in that sense. Therefore, the implementation of the vapor phase plating method using the apparatus shown in FIG. 7 is effective as a preliminary experiment of the present invention. On the other hand, as a comparative example, an experiment was also conducted under the same conditions for the apparatus shown in FIG.

It goes without saying that this experiment is also equivalent to a normal CVD method that is not based on the present invention. The plating conditions in these two experiments were both plating temperature (temperature of the plated object) 115
Pi 0, plating time r, plating paper flow rate 150 nm
The molybdenum wire was plated with titanium nitride.

As a result of performing vapor phase plating under the above conditions, it was possible to obtain a film thickness that was approximately 40% larger on average than when heating from the outer periphery of the reaction tube using a similar device. The internal heating method, in which a heating element is installed inside the reaction vessel, has been confirmed to be effective in terms of equipment design and saving of plating raw materials.

Moreover, FIG. 8 shows the distribution of the thickness of the plating film obtained by the above experiment.

The film thickness shown here is the average film thickness within each section of every 45 ribs from the inlet pipe 46 side to the outlet pipe 47 side of the plated molybdenum wire. In addition, when plating, the electrode 4
3 and 44, both ends of the molybdenum wire of the object to be plated attached to the electrodes 43 and 44 were cooled. Therefore, the concentration measurement was performed only on the central portion where the molybdenum wire was uniformly heated. As can be seen from FIG. 8, while there is very little variation in the film thickness directly from the experimental bag in FIG. It can be seen that the discharge pipe works extremely effectively and can even out the waist thickness.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view to explain the temperature distribution of a conventional vapor phase plating apparatus, Figure 2 is a longitudinal cross-sectional view to explain film thickness errors in the conventional apparatus, and Figure 3 is the apparatus of Figure 2. FIG. 4 is an explanatory diagram of the principle of the present invention; FIGS. 5 and 6 are cross-sectional views of barrel-type and batch-type plating equipment for carrying out the method of the present invention; FIG. 7 is a sectional view of the apparatus used in experiments related to the present invention, and FIG. 8 is a diagram showing the experimental results. 10,30... Reaction vessel, 1 1,31...
... Heating element, 15, 34 ... Object to be plated, N... Vaporization temperature range, N... Reaction temperature range. Line 1 diagram Shigeru 2 Koji Shigeru 8 pith 4th neighbor Figure 5 Shigeru 8 diagram Shigeru 7 box fin 8 wings

Claims (1)

[Claims] 1. A heating element is disposed in the center of the reaction vessel, and the object to be plated is placed in a reaction temperature range suitable for gas phase plating formed in the reaction vessel by heating by the heating element, and the object to be plated is placed in a reaction temperature range suitable for gas phase plating, which is formed around it. A vapor phase characterized by supplying a vapor source to a vaporization temperature region of the vapor source, depositing a plating film on the object to be plated in the reaction temperature region, and discharging the reaction product from inside the reaction temperature region. Metsuki method.