JPH1167872A - Plasma cleaning method for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and uniformly perform plasma cleaning, by measuring the length of a substrate before the substrate is transported into a vacuum chamber, controlling a transportation means based on the length, and always placing the substrate in the center of the vacuum chamber. SOLUTION: A substrate detection sensor 65 is arranged in a transportation path 14 on the upstream side of a vacuum chamber 11. The length Lp of a substrate 1 is obtained from the time when the substrate 1 under transportation is detected and from transportation speed. When the substrate 1 is transported into the vacuum chamber 11 in a length wipe direction Lv and it is placed on an electrode 12, a distance xb from the tip part of the substrate 1 to an end part on the downstream side in the vacuum chamber 11 is designated, and the substrate 1 is pushed to the center in the vacuum chamber 11. A cover member 13 descends and the vacuum chamber 11 is closed. Then, plasma leaning of the surface of the substrate 1 is performed. At that time, the substrate 1 is always placed is the center of the vacuum chamber 11, and the generated plasma is stabilized. Then, uniform and efficient plasma cleaning can always be executed on the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of plasma cleaning a substrate surface before mounting electronic components on a substrate such as a printed circuit board or a lead frame.

[0002]

2. Description of the Related Art Before mounting electronic components on a substrate such as a printed circuit board or a lead frame, an electronic component mounting apparatus cleans the surface of the substrate. 2. Description of the Related Art Plasma cleaning is known as a method for cleaning the surface of a substrate. In plasma cleaning, a substrate to be processed is placed on an electrode in a vacuum chamber, a vacuum is sucked in the vacuum chamber, a plasma generation gas is introduced into the vacuum chamber, and a high-frequency voltage is applied to the electrode to form a vacuum. Plasma is generated in the chamber, and ions and electrons generated as a result are caused to collide with the surface of the substrate to perform a cleaning process on the surface of the substrate by an etching effect of the ions and electrons.

[0003]

However, the effect of the above-described plasma cleaning depends on the density of the plasma generated in the vacuum chamber, and the plasma density is not always uniform over the entire range in the vacuum chamber. The effect of the plasma cleaning varies from site to site in the vacuum chamber. Generally, the central portion of the vacuum chamber has a higher and more stable plasma cleaning effect than the peripheral portion.

[0004] The size of a substrate to be processed by the same plasma cleaning apparatus varies in size. Therefore, when a small-sized substrate is to be processed, it is desirable to consider a position where the substrate is placed so that plasma cleaning can be performed uniformly and efficiently.

However, in the conventional plasma cleaning apparatus, when a small substrate is to be processed, the substrate is not always placed at a position having the highest plasma cleaning efficiency in the vacuum chamber. There is a problem in that plasma cleaning is not performed, and as a result, productivity improvement is hindered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plasma cleaning method for a substrate, in which a substrate is always placed at the center of a vacuum chamber and plasma cleaning can be performed efficiently and uniformly.

[0007]

According to a first aspect of the present invention, there is provided a plasma cleaning method for a substrate, wherein a substrate is carried into a vacuum chamber by a transfer means, and a vacuum generating chamber is evacuated. A plasma cleaning method for a substrate, comprising: introducing, applying a high-frequency voltage to an electrode provided in a vacuum chamber, generating plasma in the vacuum chamber, and plasma-cleaning a substrate placed in the vacuum chamber, Before carrying the substrate into the vacuum chamber, the length of the substrate was measured by the length measuring means, and the transport means was controlled based on the measurement result so that the substrate was always placed at the center of the vacuum chamber.

[0008]

According to the present invention having the above structure, the length of the substrate is measured by the length measuring means before the substrate is carried into the vacuum chamber, and the transfer means is controlled based on the measurement result. Thereby, the substrate can always be placed in the center of the vacuum chamber and uniform plasma cleaning can be performed.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view of the plasma cleaning apparatus for the same substrate, and FIG. 3 shows a configuration of a control system of the plasma cleaning apparatus for the same substrate. FIG. 4 is a partial cross-sectional view of a plasma cleaning apparatus for the same substrate, FIG. 5 is a flowchart of length measurement of the same substrate, and FIGS. 6 and 7 are partial cross-sectional views of the plasma cleaning apparatus for the same substrate.

First, the overall structure of a plasma cleaning apparatus for a substrate will be described with reference to FIG. In FIG. 1, 1
Reference numeral 0 denotes a base member, and a transfer path 14 for the substrate 1 is provided on an upper surface of the base member 10. The transport path 14 is a concave portion formed continuously in the longitudinal direction corresponding to the width of the substrate 1. The substrate 1 is placed in this concave portion, and the substrate 1 is transported by pushing the substrate 1 in the longitudinal direction. Is what you do.

A vacuum chamber 11 is provided on the transfer path 14. The vacuum chamber 11 includes a base member 10, an electrode 12 (see FIGS. 2 and 3) mounted on the base member 10, and a box-shaped lid member 1 provided on the base member 10.
3. Two plate-shaped brackets 15 are fixed to the outer surface of the lid member 13.
Is connected to the block 16. Block 16
Is connected to the opening / closing means 17 of the lid member 13. The opening / closing means 17 is composed of a cylinder or the like. By driving the opening / closing means 17, the lid member 13 moves up and down, and the vacuum chamber 11 opens and closes.

In FIG. 1, a guide rail 40 is provided on a side surface of the base member 10. Two sliders 41 and 42 are slidably fitted on the guide rail 40. Bracket 4 for sliders 41 and 42
3 and 44 are respectively fixed. Bracket 43,
A first cylinder 45 and a second cylinder 47 are mounted on 44, respectively. A first transfer arm 49 and a second transfer arm 50 are connected to the rod 46 of the first cylinder 45 and the rod 48 of the second cylinder 47, respectively.

The distal end of the first transport arm 49 and the distal end of the second transport arm 50 extend on the transport path 14 and are bent downward, and have a first transport claw 49a and a second transport arm 49a. It is a nail 50a. The first transport claws 49a and the second transport claws 50a are located on the transport path 14, and the rod 46 of the first cylinder 45 and the rod 48 of the second cylinder 47
Is moved up and down as a result.

A first motor 57 and a second motor 58 are provided on the side of the base member 10. Pulleys 55 and 56 are mounted on the rotating shafts of the first motor 57 and the second motor 58, respectively. Base member 1
Driven pulleys 53 and 54 are provided on the side surface of 0 in correspondence with the pulleys 55 and 56. Belts 59 and 60 are tuned to the pulley 55 and the driven pulley 53, and to the pulley 56 and the driven pulley 54, respectively. The belts 59, 60 are connected to the brackets 43, 44 by connecting members 51, 52.

Therefore, when the first motor 57 and the second motor 58 are driven forward and backward, the belts 59 and 60 travel in the horizontal direction, and the first cylinder 45 and the first cylinder 45 mounted on the brackets 43 and 44, respectively. The second cylinder 47 moves forward and backward in the horizontal direction. By combining the forward / reverse movement in the horizontal direction and the vertical movement of the first cylinder 45 and the second cylinder 47, the first transport claws 49a and the second transport claws 50a move the substrate 1 on the transport path 14 Push and transport. That is, the first transport claws 49a and the second transport claws 50
a is a means for transporting the substrate 1 and the first transport claws 49
In a, the substrate 1 is loaded into the vacuum chamber 11 from the upstream side (left side in FIG. 1). The second transport claw 50a unloads the substrate 1 from the vacuum chamber 11 to the downstream side (to the right in FIG. 1).

On the upstream side of the base member 10, a loader section 20 of the substrate 1 is provided. The loader unit 20 has a Z table 22 provided with a Z axis motor 23, and a magazine 21 is mounted on the Z table 22. A large number of substrates 1 are stacked and stored in the magazine 21 in a horizontal posture. A pusher 24 pushes the substrate 1 in the magazine 21 onto the transport path 14.

On the downstream side of the base member 10, an unloader section 30 for the substrate 1 is provided. The unloader unit 30 has a Z table 32 provided with a Z-axis motor 33, and a magazine 31 is mounted on the Z table 32. The substrate 1 after the plasma cleaning process is inserted into the magazine 31 by the second transport claw 50a and collected.

Next, the structure of the vacuum chamber 11 will be described with reference to FIG. In FIG. 2, an opening 10 a is provided in the base member 10, and an electrode 12 is attached to the opening 10 a from below via an insulating member 8. The electrode 12 is electrically connected to the high-frequency power supply 19, and the lid member 13 is electrically grounded to the grounding portion 61, and serves as a counter electrode facing the electrode 12. Also, the vacuum chamber 11
Is connected to the vacuum suction unit 62, the plasma gas supply unit 63, and the atmosphere release valve 64 through the pipe 18. The vacuum suction unit 62 suctions the inside of the vacuum chamber 11 under vacuum. The plasma gas supply unit 63 supplies a gas for generating plasma into the vacuum chamber 11. By opening the atmosphere release valve 64, air for vacuum breaking is introduced into the vacuum chamber 11.

A substrate detection sensor 65 is provided on the transport path 14 on the upstream side of the vacuum chamber 11. The substrate detection sensor 65 detects the substrate 1 from below while the substrate 1 is being transported on the transport path 14. From the time T during which the substrate 1 is continuously detected and the transport speed V of the substrate 1, the length Lp of the substrate 1 is obtained.
Can be requested. That is, the board detection sensor 65
Before the substrate 1 is transferred into the vacuum chamber 11,
Is a length measuring means for measuring the length Lp. The substrate 1 is carried into a vacuum chamber 11 having a length dimension Lv and mounted on the electrode 12. At this time, the distance x from the front end of the substrate 1 to the downstream end in the vacuum chamber 11
By designating “b”, the vacuum chamber 11 of the substrate 1 is
Is determined.

Next, the configuration of a control system of the plasma cleaning apparatus will be described with reference to FIG. In FIG. 3, the control unit 70 performs opening and closing operations of the vacuum chamber 11 and the loader unit 2.
0, controls the entire plasma cleaning apparatus such as the operation of the unloader unit 30. The storage unit 72 includes the vacuum chamber 1
The parameters such as a position coordinate value, a vacuum chamber dimensional value, and a transfer speed are stored. The control unit 70 calculates the length Lp of the substrate 1 based on the signal from the substrate detection sensor 65, and places the substrate 1 at the set position in the vacuum chamber 11 based on the parameters of the storage unit 72. To control the motor driving unit 71. The motor driving unit 71 drives the first transport claw 49a according to the control command. The input means 73 is a keyboard or the like, and is a position coordinate value of the vacuum chamber 11, a length dimension value Lv of the vacuum chamber, a transfer speed V
Enter parameters such as

The apparatus for cleaning a plasma of a substrate is constituted as described above, and the operation will be described with reference to the drawings. Before the start of the operation, the transfer speed V of the substrate 1 and the length dimension Lv of the vacuum chamber 11 are previously input to the input unit 73.
Has been entered. First, in FIG. 4, in a state where the vacuum chamber 11 is opened, that is, in a state where the lid member 13 is raised, the vacuum chamber 11 is moved by the first transfer claws 49a.
Substrate 1 is carried in. At this time, the length Lp of the substrate 1
Is measured by the length measuring means in accordance with the flow shown in FIG. 5, and at the same time, the distance xb for placing the substrate 1 in the center of the vacuum chamber 11 is calculated.

Hereinafter, the flow of FIG. 5 will be described. In FIG. 5, when the loading of the substrate 1 is started (ST1),
When the board detection sensor 65 starts the detection operation and detects the board 1 (ST2), the time t1 at that time is read (ST3). The board detection sensor 65 continues to detect the board 1, and if the board 1 is no longer detected (ST
4) Read the time t2 at that time. As a result, substrate 1
Is completed (ST5). Next, the substrate length Lp is calculated from the transport speed V and the time (t2-t1) when the substrate detection sensor 65 continuously detects the substrate 1 (ST).
6). Then, a distance xb for mounting the substrate 1 at the center of the vacuum chamber 11 is calculated (ST7).

According to the distance xb obtained in this way, the substrate 1 is moved by the first transfer claws 49a to the vacuum chamber 1
When the cover member 13 is pushed down to the center in 1, the lid member 13 is lowered and the vacuum chamber 11 is closed. Thereafter, the inside of the vacuum chamber 11 is evacuated by the vacuum suction unit 62, and then a plasma generating gas is introduced into the vacuum chamber 11 by the plasma gas supply unit 63. Next, the high frequency power supply 19
Is driven to apply a high-frequency voltage to the electrode 12, thereby generating a plasma in the vacuum chamber 11 as shown in FIG. The ions and electrons generated as a result collide with the surface of the substrate 1 (see the downward arrow shown in FIG. 6), whereby the surface of the substrate 1 is subjected to plasma cleaning. At this time, since the substrate 1 is always placed in the center of the vacuum chamber 11, the generated plasma is stable,
A uniform and efficient plasma cleaning is always performed on the substrate 1.

When the plasma cleaning is completed, air is introduced into the vacuum chamber 11 through an atmosphere release valve 64, and thereafter, as shown in FIG. 7, the lid member 13 is raised to open the vacuum chamber 11. Next, the first transport claws 49
a) By moving the second transfer claw 50a to the downstream side, a new substrate 1 is loaded into the vacuum chamber 11, and the substrate 1 after the plasma cleaning processing is unloaded from the vacuum chamber 11. The unloaded substrate 1 is collected in the magazine 31, and one cycle of the plasma cleaning is completed.

[0025]

According to the present invention, the length of the substrate is measured by the length measuring means before the substrate is carried into the vacuum chamber, and the transport means is controlled based on the measurement result. Even when substrates of different lengths are carried in, the substrates are always placed in the center of the vacuum chamber with a stable and uniform plasma density, so that the substrates can be uniformly and efficiently plasma-cleaned. .

[Brief description of the drawings]

FIG. 1 is a perspective view of a substrate plasma cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a substrate plasma cleaning apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a control system of the substrate plasma cleaning apparatus according to one embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention.

FIG. 5 is a flowchart of substrate length measurement according to an embodiment of the present invention.

FIG. 6 is a partial cross-sectional view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention.

FIG. 7 is a partial cross-sectional view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 10 base member 11 vacuum chamber 12 electrode 13 lid member 14 transfer path 19 high-frequency power supply 20 loader unit 30 unloader unit 49a first transfer claw 50a second transfer claw 62 vacuum suction unit 63 plasma gas supply unit 65 substrate detection sensor

Claims (1)

[Claims] 1. A substrate is carried into a vacuum chamber by a transfer means, a vacuum gas is sucked into the vacuum chamber, a plasma generating gas is introduced into the vacuum chamber, and a high-frequency voltage is applied to an electrode provided in the vacuum chamber. A plasma cleaning method for a substrate, comprising: generating plasma in a vacuum chamber to perform plasma cleaning on a substrate placed in the vacuum chamber, wherein the substrate is measured by a length measuring unit before the substrate is carried into the vacuum chamber. A length of the substrate is measured, and a transfer means is controlled based on a result of the measurement, whereby the substrate is always placed in the center of the vacuum chamber.