JPH06252211A - Bonding machine - Google Patents

Abstract

PURPOSE:To provide a thermocompression bonding machine capable of preventing defective bonds to bumps by controlling the pressure of a bonding tool against a semiconductor chip while controlling the position of the bonding tool. CONSTITUTION:A bonding machine comprises a bonding tool 4 having means for chucking a semiconductor chip and means for heating the chip; and a drive mechanism for moving the bonding tool along the z-axis. After a bonding operation is started, the pressure to the chip from the bonding tool is controlled. At the same time, the drive mechanism is controlled by a first timer to set the bonding tool to a predetermined position. A second timer is used to control a heater 6 on the bonding tool. According to this method, melted bumps suffer no pressure so that they may not spread and cause short circuits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a bonding device for bonding a semiconductor chip to a lead or a substrate.

[0002]

2. Description of the Related Art Conventionally, in order to bond a semiconductor chip and a substrate, as shown in FIG.
A means for arranging the bump 3 between them and applying pressure and heat was taken. At this time, in the bonding of the semiconductor chip and the substrate using the gold bump, the bonding tool is always heated, and the semiconductor chip and the substrate are pressed with a predetermined pressure to be connected. Moreover, in the bonding using the gold bumps, the conventional method can only make the connection as shown in FIG. 6, and it is not possible to form the ideal connection type of the drum-shaped bump shape as shown in FIG.

On the other hand, in the bonding using the solder bumps, when the semiconductor chip is pressed and heated by the bonding tool at the same time, the solder bumps are crushed and a short circuit occurs between the bumps. Therefore, JP-A-61
No. 289964, means for detecting the amount of displacement of the bonding tool to stop the pressurization to the semiconductor chip, and an elastic body between the semiconductor chip and the lead as described in JP-A-2-235352. To prevent excessive displacement.

[0004]

However, JP-A-61-161
The means for detecting and controlling the amount of displacement as shown in Japanese Patent No. 289964 is not only incapable of making the connection shape of the bumps into a drum shape, but also has a risk of causing connection failure due to variations in the bump shape. On the other hand, JP-A-2-235352
In the method of interposing an elastic body in the signal, although the bumps can be connected in a drum shape, the attachment of the elastic body makes the semiconductor expensive and cannot be used depending on the shape of the leads.

Therefore, the present invention is a solder bump bonding apparatus which can form the connection shape of the bumps in a drum shape and has no connection failure due to the bump shape. A bonding apparatus that can handle bumps is provided.

[0006]

In order to solve the above problems, the present invention provides a bonding apparatus having a bonding tool having a semiconductor chip suction means, a semiconductor chip heating means, and a Z-axis driving means for the bonding tool. In the above, the switching means from the pressure control for pressing the semiconductor chip of the bonding tool after the start of the bonding operation to the position control for stopping the pressing of the bonding tool and holding it at a predetermined minute elevated position, and heating at the time of switching or before switching. There is provided a bonding device.

[0007]

Embodiments will be described below with reference to the illustrated embodiments. Figure 1
FIG. 3 is a partial side view showing a bonding device, which is provided with a bonding tool 4 having a semiconductor chip suction means and a semiconductor chip heating means, and a Z-axis driving means for the bonding tool 4.

The semiconductor chip suction means in the bonding tool 4 may be a normal suction means for applying a negative pressure to a vacuum hole formed in the contact surface of the bonding tool 4 with the semiconductor chip by a suction device provided separately. The heating means may be various known means which have been conventionally used. A pressure sensor 5 shown in FIG. 1 and a thermocouple 6 shown in FIG. 2 are attached to the bonding tool 4 as control sensors.

The Z-axis drive unit of the bonding tool 4 is
As shown in detail in FIG. 2, a ball screw 8 rotated by a drive motor 7 is attached with a tool attachment 9 having a female screw portion, and the bonding tool 4 is attached to the attachment 9. Yes, the Z axis of the bonding tool 4 is driven by the control of the drive motor 7, that is, the semiconductor chip 1
The substrate 2 is driven toward and away from the substrate 2 (in the direction of the arrow in FIG. 2).

A first timer, a second timer and a pressure sensor 5 are used to control the Z-axis drive mechanism and the heating mechanism of the bonding tool 4. The first timer is used to control the Z-axis drive mechanism of the bonding tool 4 (pressure control and position control), and the second timer controls the heating mechanism of the bonding tool 4 (heating start delay time control and heating). It is used for time control).

A first embodiment of the control means will be described with reference to FIG. The control device is tool position, bonding load, chip suction,
It has a tool heating control means. In FIG. 3, t1 shown in the tool position control indicates the load control time, and t2 indicates the position control time. Further, t3 shown in the tool heating portion indicates a heating start delay time, and t4 indicates a heating time.

In the control device, point A at the tool position in FIG. 3 is the bonding start position, and when a predetermined bonding start signal is received at this position, the semiconductor chip leads (or the substrate) to the bonding tool 4. Lower it so that it is close to. Next, when the semiconductor chip and the lead come into contact with each other, the pressure sensor 5 detects this and sends a bonding start signal to the control device. B shown by the vertical dotted line in FIG.
The point is when the bonding start signal is transmitted. With this signal, the first timer and the second timer are activated.

The bonding tool 4, as shown in the comparison of tool heating and bonding load in FIG.
Until the heating start delay time t3 elapses, the semiconductor chip is not heated and only pressure is applied. Therefore, the lowering of the bonding tool 4 is stopped at a position where the stress of the solder bump 3 and the pressure of the bonding tool 4 are balanced. Then, when the first timer counts t1, that is, when the load control time elapses, the pressing is stopped, and the bonding tool 4 is
It is held in that position. Stopping this pressurization and holding at this position is the first step of position control.

On the other hand, when the second timer counts t3, that is, after the heating start delay time has elapsed, the bonding tool 4 starts heating the semiconductor chip. When the first timer resets t1 and further counts t2, that is, when the position control time elapses, the bonding tool 4 rises by a preset small distance and is held at that position. The preset small distance is shown as the tool shift amount D at the tool position in FIG. This minute distance increase and holding at that position is the second stage of position control. At this time as well, the chip suction means is operating as shown by the chip suction and tool heating in FIG. 3 (chip suction portion ON in FIG. 3), and heating has already been performed and the solder bumps have melted.

The heating is stopped when the second timer resets t3 and further counts t4, that is, when the heating time elapses. Since the tool position at the time of stopping heating is in the position control state of the second stage, the solder bumps have a drum-shaped connection shape during the time until the solder is fixed. After that, when the temperature of the bonding tool 4 drops to the solder fixing temperature or when a predetermined bonding end time t5 is detected, the bonding tool 4 stops the chip adsorption and rises. This completes the bonding operation for one cycle.

Next, a second embodiment of the control means will be described with reference to FIG. The second embodiment is a bonding tool 4
Is a control means when the heating speed is fast, that is, when the solder bumps are easily melted. The control regarding the tool position, the bonding load, and the chip adsorption is the same as that of the first embodiment, but only the tool heating control is different. . That is, the load control time t1 and the heating start delay time t3 are the same, and the tool heating is started when the pressure control is switched to the position control. The control after the start of heating is the same as in the first embodiment.

In the first embodiment (FIG. 3) of the control means, the start point is the pressurization start point, and the pressure control and the heating control are in one stage. However, like the control means shown in FIG. In addition, the start point may be an arbitrary set point before the start of pressurization, and the pressurization control and the heating control can be two-step control.

That is, in the third embodiment shown in FIG. 5, the bonding tool 4 is lowered to the bonding start height (point C position) in response to the bonding start signal. At this point, the first timer and the second timer are activated. First
After counting the tool descent start delay time t0, the bonding tool descends again and shifts to load control, but the load control time is t1-1 (1st pressure time).
And t1-2 (2nd pressure time) can be set in two stages, and the joining load in each stage can be changed. Also, in the heating control, the heating time is t4-1 (1st heating time) and t
It is also possible to set the temperature in two stages such as 4-2 (2nd heating time), and control heating with different amounts of heat in each heating stage.

[0019]

Since the present invention is constructed as described above, it exhibits the following effects. In the conventional bonding apparatus, since the semiconductor chip is heated and pressed simultaneously by the bonding tool, the solder bumps in a melted state are pressed, and the solder is crushed and short-circuited. Therefore, the solder bumps cannot be used in the bonding apparatus. However, according to the present invention, since the tool heating is performed within the time period of the bonding tool position control t2, the bonding load is not applied to the melted bumps and the solder bumps are not applied. There is no longer a risk of crushing and short-circuiting.

Further, according to the present invention, since the tool shift amount D can be set in the Z-axis drive mechanism of the bonding tool, the solder bump is processed into a drum shape by shifting the semiconductor chip upward after melting the solder. It has become possible. This made it possible to reduce the stress caused by the difference in the coefficient of thermal expansion between the chip and the substrate. In addition, the gap between the chip and the substrate can be controlled, and the sealing resin can be easily introduced.

[Brief description of drawings]

FIG. 1 is a partial side view of a bonding apparatus.

FIG. 2 is an explanatory diagram showing a Z-axis drive mechanism of a bonding tool.

FIG. 3 is a control diagram showing the first embodiment.

FIG. 4 is a control diagram showing a second embodiment.

FIG. 5 is a control diagram showing a third embodiment.

FIG. 6 is an explanatory view showing a normal bump connection shape.

FIG. 7 is an explanatory diagram showing a drum-shaped bump connection shape.

[Explanation of symbols]

 1. ． ． ． ． Semiconductor chip 2. ． ． ． ． Substrate 3. ． ． ． ． Bump 4. ． ． ． ． Bonding tool 5. ． ． ． ． Pressure sensor 6. ． ． ． ． Thermocouple 7. ． ． ． ． Drive motor 8. ． ． ． ． Ball screw 9. ． ． ． ． Tool mounting body

Claims (1)

[Claims] 1. A bonding apparatus comprising a bonding tool having a semiconductor chip suction means, a semiconductor chip heating means, and a Z-axis driving means for the bonding tool, wherein the bonding tool is pressed against the semiconductor chip after the bonding operation is started. A bonding apparatus comprising: switching means for performing pressure control to stop the pressing of the bonding tool and maintaining the bonding tool at a predetermined minute elevated position; and heating means during or before the switching.