JPH05206094A - Plasma cleaner - Google Patents

Abstract

PURPOSE:To make uniform a temperature distribution of a holder by a method wherein a structure of the holder capable of simply and readily cleaning is improved concerning improvements in the structure of the holder to be processed which is a plasma cleaner. CONSTITUTION:A member is placed within a glass chamber 1 at a reduced indoor pressure and a high frequency voltage is applied using a high frequency power source 7 between upper and lower electrode plates 5, 6 arranged in the periphery of the glass chamber 1 to produce plasma within the glass chamber 1. In a plasma cleaner for cleaning the surface of this member by the plasma, a member 14 in which thermal capacity is smaller than a holder 4 is provided at both ends of the holder 4 mounting this member, or a member in which thermal capacity is greater than the holder 4 is provided in a central part of the holder 4 mounting the member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a holder for an object to be processed of a plasma cleaning device.

When the plasma cleaning device performs a cleaning process on an object to be processed, if the plasma distribution becomes non-uniform, the temperature distribution of the holder becomes non-uniform, and the etching rate depending on the heating temperature of the holder is partially non-uniform. There is a uniform failure.

Under the circumstances as described above, there is a demand for a plasma cleaning apparatus which can make the etching rate of the plasma cleaning apparatus uniform in any part of the holder.

[0004]

2. Description of the Related Art A lead frame cleaning process using a conventional plasma cleaning apparatus immediately before a resin sealing step will be described in detail with reference to FIGS.

3 to 4 are views showing a conventional plasma cleaning device, and FIG. 5 is a view showing a detailed structure of a holder of the conventional plasma cleaning device. As shown in FIG. 3, one end of the glass chamber 1 made of quartz is connected to an exhaust device (not shown), and the side wall is provided with a plurality of reaction gas supply ports 1a.

The opening of the other end of the glass chamber 1 which is not connected to the exhaust device is covered with a lid 3 made of stainless steel, and is provided on the side wall of the glass chamber 1 which is integral with the lid 3. As shown in FIG. 4, a lead frame 8 as an object to be processed is mounted on a holder 4 made of stainless steel which is movable by being guided by a guide 2 made of Teflon.

An upper electrode plate 5 and a lower electrode plate 6 are provided above and below the glass chamber 1, the upper electrode plate 5 is connected to a high frequency power source 7, the lower electrode plate 6 is grounded, and the frequency is 13.56. High-frequency power supply 7 with MHz and output of 1,000 W
Plasma is generated in the glass chamber 1 by applying a high-frequency voltage.

As shown in FIG. 5, the holder 4 has a structure in which the lead frame 8 is held by the peripheral portion of the lead frame 8 which is not embedded in the sealing resin. When the lead frame 8 is cleaned by using such a plasma cleaning device, first, the lead frame 8 is mounted on the holding portion of the holder 4, and the holder 4 is placed in the glass chamber 1 along the guide 2. Insert and seal glass chamber 1 with lid 3.

Next, the air in the glass chamber 1 is exhausted by an exhaust device (not shown) to bring the room pressure to 10 ^-1 to 10 ^-2 Torr, and then the reaction gas supply port 1a is maintained so as to maintain this room pressure.
The reaction gas is supplied under the following conditions, and a plasma is generated in the glass chamber 1 by applying a high frequency voltage using the high frequency power supply 7.

As the reaction gas, 500 sccm of argon gas is supplied for 3 minutes, or a mixed gas of 500 sccm of argon gas and hydrogen is supplied for 2 minutes. Such a lead frame 8
Immediately after performing the cleaning process of
Resin is sealed before it is recontaminated.

[0011]

In the conventional plasma cleaning apparatus described above, the reaction gas is supplied from the reaction gas supply port on the side wall of the glass chamber and exhausted from one of the glass chambers. There is a problem that the flow concentrates on this part, the plasma concentrates on the holder near this part, and the temperature rises higher than the central part, and the opening on the opposite side of the exhaust port is covered with a metal lid. Therefore, there is a problem that plasma is concentrated on the lid and the temperature of the holder near the lid rises higher than that of the central portion.

In view of the above situation, the present invention provides an improved holder structure that can be easily and easily provided.
An object of the present invention is to provide a plasma cleaning device that can make the temperature distribution of the holder uniform.

[0013]

In the plasma cleaning apparatus of the present invention, a member is placed in a glass chamber whose chamber pressure is reduced, and a high frequency wave is placed between an upper electrode plate and a lower electrode plate arranged around the glass chamber. In a plasma cleaning device that cleans the surface of this member by plasma generated in this glass chamber by applying a high frequency voltage using a power supply, the heat capacity at both ends of the holder of this member is smaller than that of this holder. A member is provided, or a member having a larger heat capacity than the holder is provided at the center of the holder of the member.

[0014]

That is, in the present invention, since members having a small heat capacity are provided at both ends of the holder on which the members are placed where the plasma is concentrated and the temperature becomes high, even if the plasma is concentrated at the both ends It is possible to suppress the temperature rise of the above, and conversely, since a member having a large heat capacity is provided in the central portion, it is possible to raise the temperature of the central portion so as to approach the temperature of both ends.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a diagram showing a plasma cleaning apparatus of a first embodiment according to the present invention, and FIG. 2 is a diagram showing a plasma cleaning apparatus of a second embodiment according to the present invention.

The overall structure of the plasma cleaning apparatus shown in FIG. 1 is the same as that of the conventional plasma cleaning apparatus shown in FIG. 3, but a member 14 having a small heat capacity, such as alumina, is provided at both ends of the holder 4 shown in FIG. Has been.

The overall structure of the plasma cleaning apparatus shown in FIG. 2 is the same as that of the conventional plasma cleaning apparatus shown in FIG. 3, but the structure of the holder 4 in FIG. 2 is different from the conventional one, and the central portion of the holder 4 is different. A member 24 having a large heat capacity, for example, a nickel-plated copper plate is provided in the.

Since the member 14 having a small heat capacity is provided at both ends of the holder 4 and the member 24 having a large heat capacity is provided at the center of the holder 4 as described above, the temperature distribution in the holder can be kept uniform. Therefore, it becomes possible to make the etching rate uniform in each part of the lead frame 8 of the object to be processed.

In order to compare the etching rates, a negative resist film is formed on the surface of the lead frame 8, the average etching rate is set to 2,000 Å / min, and the results of the cleaning process performed under the following conditions are shown. Shown in 1.

Argon flow rate: 1,000 sccm, high frequency power output: 1,000 W, glass chamber chamber pressure: 0.1 Torr, etching time: 4 minutes

[0021]

[Table 1]

From Table 1, assuming that the etching rate of the reference portion is 100 in the past, it is 4 in the portion with a low etching rate.
6, the high etching rate is 160, and in the first embodiment of the present invention, the etching rate of the reference portion is 1
When it is 00, it is 86 in the low etching rate part and 120 in the high etching rate part.
In this example, when the etching rate of the reference portion is 100, it is found that the portion having a low etching rate is 84 and the portion having a high etching rate is 119.

[0023]

As is apparent from the above description, according to the present invention, the temperature of each part of the holder can be made uniform by changing the structure of the holder very easily. There is an advantage that the etching rate of the processed material can be made uniform, and it is possible to provide a plasma cleaning apparatus which can be expected to be significantly economical and to improve reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing a plasma cleaning apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a plasma cleaning apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a conventional plasma cleaning device.

4 is a sectional view taken along line AA of FIG.

FIG. 5 is a view showing a detailed structure of a holder of a conventional plasma cleaning device.

[Explanation of symbols]

 1 is a glass chamber, 1a is a reaction gas supply port, 2 is a guide, 3 is a lid, 4 is a holder, 5 is an upper electrode plate, 6 is a lower electrode plate, 7 is a high frequency power supply, 8 is a lead frame, and 14 is a heat capacity. Small member, 24 is a member with large heat capacity,

Claims (2)

[Claims] 1. A member (8) is placed in a glass chamber (1) whose chamber pressure is reduced, and an upper electrode plate (5) and a lower electrode plate (6) arranged around the glass chamber (1). ) Between the members (8) by the plasma generated in the glass chamber (1) by applying a high frequency voltage using a high frequency power supply (7).
In the plasma cleaning apparatus for cleaning the surface of the member, a plasma cleaning device characterized in that a member (14) having a heat capacity smaller than that of the holder (4) is provided at both ends of the holder (4) of the member (8). apparatus. 2. The plasma cleaning apparatus according to claim 1, wherein a member (24) having a heat capacity larger than that of the holder (4) is provided in a central portion of the holder (4) of the member (8). And a plasma cleaning device.