JPH04289173A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To provide a plasma CVD device capable of depositing a decomposition product on a material in uniform thickness. CONSTITUTION:The first and second discharge electrodes 21 and 22 and third and fourth discharge electrodes 23 and 24 provided in a treating vessel with their flat discharge faces opposed to one another in the gaseous reactant introducing direction with a holder plate 15 for detaining a material 30 to be deposited with in between, a high-frequency power source 18 with one pole grounded and the other pole connected to the fourth discharge electrode through a phaser 19 and a low-frequency power source 25 with one pole grounded and the other pole connected to the first discharge electrode and to the second discharge electrode through a phaser 26 and generating a high-frequency voltage with the frequency lower than the high-frequency power source are provided to this plasma CVD device.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a plasma CVD apparatus for depositing decomposition products of a reactive gas decomposed by plasma on the surface of a deposited object, and particularly for depositing decomposition products on the surface of a deposited object with a uniform thickness. The present invention relates to a plasma CVD apparatus capable of performing deposition.

0002

2. Description of the Related Art Next, a conventional plasma CVD apparatus will be explained with reference to FIG. FIG. 3 is a diagram for explaining a conventional plasma CVD apparatus, and FIG.
is a schematic cross-sectional view of the main part of the device, and FIG. 3(b) is a schematic plan view of the main part of the device. In this specification, the same parts, materials, etc. are given the same reference numerals throughout the drawings.

A conventional plasma CVD apparatus is shown in FIG.
As shown in FIG. 2(b), there is a metal base plate 11 whose flat surface is horizontal and grounded, and a base plate 1 which is freely raised and lowered by a lifting device (not shown).
1 and a reaction gas 10 supplied from a reaction gas supply pipe 13 disposed inside the processing tank 12 and passing through the processing tank 12, which is ejected substantially perpendicularly to the base plate 11. The nozzle 14 and a plate-shaped holder plate 15 that is vertically disposed on the base plate 11 with nail-shaped locking nails 15a that lock the deposited material, such as the lead frame 30, arranged on both sides, and the base plate 11 The first and second discharge electrodes 16 and 17 face each other and have their respective discharge surfaces 16a and 17a orthogonal to the surface direction of the base plate 11, and one pole 18b is grounded and the other pole 18a is connected to the first discharge electrode 16 and 17. It is configured to include an AC power source directly connected to the electrode 16 and connected to the second discharge electrode 17 via a phase adjuster 19, for example, a high frequency power source 19 that generates a high frequency voltage with a frequency of 13.56 MHz.

[0004] A method of depositing a SiO2 film on the back surface of a die stage on which an object to be deposited, such as a semiconductor chip of a lead frame, is mounted on the surface using a plasma CVD apparatus configured as described above will be described.

For this purpose, first, the die stage 30a is
Small holes 30b are provided at both ends of the lead frame 30, the entire back surface of which is coated with resist (not shown) except for the back surface of the lead frame 30.
After this lead frame 30 is locked to the holder plate 15 by hooking it on the locking nail 15a of the holder plate 15, the lifting device is operated to slowly lower the processing tank 12 and gently place it on the base plate 11. Note that when locking the lead frame 30 to the holder plate 15, the surface of the lead frame 30 is attached to the holder plate 1.
It is important to face the surface of No. 5 and to be in substantially close contact with the surface of No. 5.

Next, an exhaust device (not shown) connected to an exhaust pipe 11a fixed to the base plate 11 and communicating with the inside of the processing tank 12 is activated to bring the inside of the processing tank 12 to a high degree of vacuum, and the reaction gas supply pipe 13 is activated. A reactive gas 10 made of silane (SiH4) and oxygen (O2), for example, is supplied to the gas introduction nozzle 14 through the gas introduction nozzle 14 and is directed to the base plate 11 from the spout 14a of the gas introduction nozzle 14 as shown by arrow D. For example, 1 (T
The degree of vacuum is maintained at approximately (orr).

After that, the high frequency power supply 18 is activated to apply a high frequency voltage of the above frequency to the first and second discharge electrodes 16, 17, and the discharge surface 16a of the first discharge electrode 16, the holder plate 15 and the Discharge surface 17 of discharge electrode 17 of No. 2
When a plasma is formed by a glow discharge generated between a and the holder plate 15, the reaction gas 10 is decomposed by this plasma and the decomposition product SiO
2 will be deposited as a SiO2 film on the back surface of the lead frame 30.

[0008] Thus, when the resist of the lead frame 30 coated with the SiO2 film in this manner is removed, the lead frame 30 with the SiO2 film coated only on the back surface of the die stage 30a is completed.

Note that the phase of the AC voltage from the high frequency power source 18 applied to the second discharge electrode 17 is normally adjusted from the original AC voltage phase by a phase adjuster 19 in order to improve plasma generation efficiency. For example, they are shifted by about 3π/4.

0010

However, as described above, the reaction gas 10 is ejected from the top of the holder plate 15 toward its base, that is, toward the base plate 11.

For this reason, the concentration of the reactive gas 10 decreases from the top of the holder plate 15 toward its base, so a thick SiO2 film is deposited on the lead frame 30 that is fixed near the top of the holder plate 15. Further, a thin SiO2 film is deposited on the lead frame 30 that is fixed to the base of the holder plate 15.

The present invention has been made to solve these problems, and its purpose is to provide a plasma CVD apparatus that can deposit decomposition products with a uniform thickness on the surface of a material to be deposited. It's on offer.

[0013]

[Means for Solving the Problems] As shown in FIG. 1, the object is to provide a holder which is grounded in a processing tank 12 into which a reaction gas 10 is introduced from a gas introduction nozzle 14 and which locks a deposited material 30. The processing tank 21 is arranged with the flat discharge surfaces 21a and 22a facing each other and parallel to the introduction direction of the reaction gas 10 via the plate 15 and the holder plate 15.
a first discharge electrode and a second discharge electrode 21 disposed within the
, 22 are spaced apart from the gas introduction nozzle 14 in the processing tank 12 than the first discharge electrode 21, and the discharge surface 23a is the first
A third discharge electrode 23 is flush with and insulated from the discharge surface 21a of the discharge electrode 21, and is opposed to the third discharge electrode 23 via the holder plate 15 in the processing tank 12, and the discharge surface 24a is insulated from the discharge surface 21a of the discharge electrode 21. A fourth discharge electrode 24 that is flush with and insulated from the discharge surface 22a of the discharge electrode 22, and one pole 18
b is grounded, and the other pole 18a is connected to the third discharge electrode 23
and a high frequency power source 18 connected to the fourth discharge electrode 24 via the transfer regulator 19, and one pole 25b.
is grounded, the other pole 25a is connected to the first discharge electrode 21 and also connected to the second discharge electrode 22 via the transfer regulator 26, and a low frequency power source that generates a high frequency voltage of a lower frequency than the high frequency power source 18 is connected. This is achieved by a plasma CVD apparatus characterized in that it includes a power source 25.

[0014]

[Operation] The frequency of the AC voltage applied to the discharge electrode and the rate of formation of a decomposition product (SiO2) of a reactive gas, such as a reactive gas consisting of silane (SiH4) and oxygen (O2), are shown in Figure 2.
It is known that the speed increases with frequency as shown in .

Therefore, the discharge electrode is divided into parts in a direction perpendicular to the ejection direction of the reaction gas, and an AC voltage of, for example, about 50 to 200 KHz is applied to the discharge electrode on the side where the concentration of the reaction gas is high. Since the plasma CVD apparatus of the present invention is configured to apply a high-frequency high-frequency voltage, for example, an AC voltage of 13.56 MHz, to the lower discharge electrode, the surface of the object to be deposited can be coated with a uniform thickness. This allows the decomposition products of the reaction gas to be deposited.

[0016]

Embodiment A plasma CVD apparatus according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram for explaining a plasma CVD apparatus according to an embodiment of the present invention, and FIG. 1(a) is a schematic cross-sectional view of main parts of the apparatus;
FIG. 2B is a schematic plan view of the main parts of the device.

The plasma CVD apparatus according to an embodiment of the present invention shown in FIGS. 3(a) and 3(b) is based on the plasma CVD apparatus described with reference to FIG. 3, and has been reconfigured by adding three modifications. It is something.

That is, the first modification point is that the first discharge electrode 16 of the conventional plasma CVD apparatus is divided and separated in the direction perpendicular to the jetting direction of the reactive gas 10, and Then, the first and third discharge electrodes 21,
23, and the second discharge electrode 17 of the conventional plasma CVD apparatus is divided and separated in the direction perpendicular to the jetting direction of the reactive gas 10, and the second and fourth discharge electrodes are separated along the jetting direction of the reactive gas 10. The discharge electrodes 22 and 24 are used as discharge electrodes 22 and 24.

The second modification point is that the conventional plasma C
The high frequency power supply 18 and voltage regulator 19 of the VD device can be used as they are, and one pole 18a of the high frequency power supply 18 can be connected directly to the third pole.
When reconnecting to the discharge electrode 23 of the phase adjuster 19,
The reason is that it is also reconnected to the fourth discharge electrode 24 via.

Furthermore, the third modification point is to generate an AC voltage of a lower frequency than the high frequency power supply 18, for example, 100 KHz, to ground one pole 25b, and to connect the other pole 25a to the first
This is because a low frequency power source 25 is additionally installed, which is directly connected to the second discharge electrode 21 and also connected to the second discharge electrode 22 via a newly added phase adjuster 26.

Note that the phase of the 100 KHz AC voltage from the low frequency power source 25 applied to the second discharge electrode 22 is as follows:
In order to improve plasma generation efficiency, the phase adjuster 26 usually adjusts the phase of the original AC voltage by 3π, for example.
13.56MH from the high frequency power supply 18 applied to the fourth discharge electrode 24 in the same way.
The phase of the AC voltage z is shifted by, for example, about 3π/4 from the phase of the original AC voltage by the phase adjuster 19.

With the plasma CVD apparatus according to the embodiment of the present invention having the above structure, SiO2 is deposited on the back surface of the die stage on which the semiconductor chip of the lead frame is mounted.
The deposition of the two films is performed using the conventional plasma CV method explained with reference to FIG.
This will be carried out in accordance with the method using device D.

That is, first, the small holes 30b provided at both ends of the lead frame 30, which has a resist (not shown) coated on the entire back surface except for the back surface of the die stage 30a, are hooked onto the locking nails 15a of the holder plate 15. After this lead frame 30 is locked to the holder plate 15, a lifting device (not shown) is operated to gradually lower the processing tank 12 and place it on the base plate 11.

Next, an exhaust device (not shown) connected to an exhaust pipe 11a fixed to the base plate 11 and communicating with the inside of the processing tank 21 is operated to bring the inside of the processing tank 21 to a high degree of vacuum, and the reaction gas supply pipe 13 is activated. A reactive gas 10 made of silane (SiH4) and oxygen (O2), for example, is supplied to the gas introduction nozzle 14 through the gas introduction nozzle 14 and is directed to the base plate 11 from the spout 14a of the gas introduction nozzle 14 as shown by arrow D. For example, 1 (T
The degree of vacuum is maintained at approximately (orr).

After this, the high frequency power supply 18 and the low frequency power supply 25
10 to the first and second discharge electrodes 21 and 22.
While applying an AC voltage of 0 KHz, the third and fourth
When an alternating current voltage of 13.56 MHz is applied to the discharge electrodes 23 and 24 of the discharge electrodes 21 to 24 and a plasma is formed by the glow discharge generated between the discharge electrodes 21 to 24 and the holder plate 15, a reactive gas such as silane (SiH4 )
The reaction gas 10 consisting of and oxygen (O2) is decomposed by this plasma, and its decomposition product, SiO2, is deposited as a uniform SiO2 film on the back surface of the lead frame 30.

Note that the formation of a uniform SiO2 film on the back surface of the lead frame 30 is as described in the "effect" section above.

[0027]

As described above, the present invention makes it possible to provide a plasma CVD apparatus capable of depositing decomposition products to a uniform thickness on the surface of an object to be deposited. Therefore, the decomposition products generated by decomposing the reactive gas by the plasma CVD apparatus of the present invention are deposited with a uniform thickness on the surface of the object to be deposited.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a plasma CVD apparatus according to an embodiment of the present invention;

[Fig. 2] is a diagram showing the relationship between the frequency of AC voltage and the decomposition rate of reaction gas,

FIG. 3 is a diagram for explaining a conventional plasma CVD apparatus.

[Explanation of symbols]

10 is a reaction gas, 11 is a base plate, 11a is an exhaust pipe, 12 is a processing tank, 13 is a reaction gas supply pipe, 14 is a gas introduction nozzle, 14a is a spout, 15 is a holder plate, 15a is a locking nail, 16, 21 is a first discharge electrode, 16a, 17a, 21a, 22a, 23a, 24a is a discharge surface, 17, 22 is a second discharge electrode, 18 is a high frequency power source , 19 and 26 are phase adjusters, 23 is a third discharge electrode, 24 is a fourth discharge electrode, 25 is a low frequency power supply, 30 is a lead frame, 30a is a die stage, 30b is, Each small hole is shown.

Claims (1)

[Claims] 1. Grounded within the processing tank (12) into which the reaction gas (10) is introduced from the gas introduction nozzle (14),
Holder plate (15) that locks the deposited material (30)
and a first tube disposed in the processing tank (12) with the flat discharge surfaces (21a, 22a) facing each other and parallel to the direction of introduction of the reaction gas (10) via the holder plate (15). A discharge electrode and a second discharge electrode (21, 2
2) and a gas introduction nozzle (14) in the processing tank (12).
spaced apart from the first discharge electrode (21) from the discharge surface (2
3a) is the discharge surface (21a) of the first discharge electrode (21)
a third discharge electrode (23) coplanar and insulated with the
The discharge surface (24a) faces the third discharge electrode (23) via the holder plate (15) in the treatment tank (12).
is connected to a fourth discharge electrode (24) which is flush with and insulated from the discharge surface (22a) of the second discharge electrode (22), one pole (18b) is grounded, and the other pole (18a) is connected to the third discharge electrode (24). The transfer regulator (1) is connected to the discharge electrode (23) of the
9) to the fourth discharge electrode (24), one pole (25b) is grounded, and the other pole (25a) is connected to the first discharge electrode (21). At the same time, the second discharge electrode (
22) and a low frequency power source (25) that generates a high frequency voltage having a lower frequency than the high frequency power source (18).