Semiconductor-chip exfoliating device and semiconductor-device manufacturing method

1. Field of the Invention

The present invention relates to device and method for manufacturing semiconductor devices. More particularly, the invention relates to semiconductor-chip exfoliating device and method that are constructed so as to lift off an adhesive sheet having a semiconductor chip by means of lift-off pins whereby one semiconductor chip can be exfoliated from the adhesive sheet.

2. Description of the Related Art

Japanese Patent Publication Laid-open (heisei) No. 10-112465 discloses a prior art apparatus for manufacturing semiconductor devices. In the apparatus, a semiconductor chip adhered to an adhesive film (dicing sheet) is lifted up by lift-off pins (needle pins) to thereby exfoliate the semiconductor chip from the adhesive sheet. The so-exfoliated semiconductor chip is used to manufacture a semiconductor device.

In the above-mentioned apparatus, a single semiconductor chip is lifted up by using a plurality of needle pins.

However, the above-mentioned manufacturing apparatus for semiconductor devices is not thoughtful of the following points.

In exfoliating one semiconductor chip from the adhesive sheet, it is preferable to allow the lift-off pin to lift off chip's margins on both sides of the semiconductor chip as a target. The knocking-up of the lift-off pins against chip's margins on both sides of the chip allows the semiconductor to be exfoliated from the adhesive sheet with ease, also allowing the exfoliated chip to be broken with difficulty.

In the above-mentioned apparatus, however, the interval between the lift-off pins is constant in spite of a variety of semiconductor chips in size to be adhered to the adhesive sheet. Therefore, if it is required to exfoliate one of semiconductor chips from the adhesive sheet, the semiconductor chips each having a different size from that of the normal semiconductor chip, it is necessary to replace an original lift-off unit for the normal semiconductor chip to another lift-off unit where the interval between the lift-off pins is changed for such a different semiconductor chip.

It is apt to take time and work in exchanging one lift-off unit to another one in the manufacturing process, causing the productivity of the semiconductor devices to be reduced.

Under such a situation, an object of the present invention is to provide a semiconductor-chip exfoliating device capable of making it ease to exfoliate a semiconductor chip from an adhesive sheet throughout semiconductor chips of difference sizes. Another object of the present invention is to provide a semiconductor-chip exfoliating method of exfoliating one semiconductor chip from the adhesive sheet through the use of the above semiconductor-chip exfoliating device.

In order to attain the former object, according to the present invention, there is provided a semiconductor-chip exfoliating device for exfoliating a semiconductor chip from an adhesive sheet to which a plurality of semiconductor chips are adhered, comprising: a holder for holding the adhesive sheet so that the semiconductor chips turn upward; at least two through-holes formed in the holder; at least two lift-off pins arranged on a backside of the holder to lift off the adhesive sheet from the holder through the through-holes; and a sliding unit arranged on the backside of the holder to slide at least one lift-off pin in a direction to depart from the other lift-off pin to thereby change an interval between the lift-off pins.

In order to attain the latter object, according to the present invention, there is also provided a semiconductor-device manufacturing method, comprising the steps of: preparing a semiconductor-chip exfoliating device including a holder for holding the adhesive sheet so that a plurality of semiconductor chips turn upward, at least two through-holes formed in the holder, at least two lift-off pins arranged on a backside of the holder to lift off the adhesive sheet from the holder through the through-holes, and a sliding unit arranged on the backside of the holder to slide at least one lift-off pin in a direction to depart from the other lift-off pin to thereby change an interval between the lift-off pins; allowing the holder to hold the adhesive sheet so that the semiconductor chips turn upward; and raising the lift-off pins to lift off the adhesive sheet from the holder, whereby one semiconductor chip can be exfoliated from the adhesive sheet.

With the above semiconductor-chip exfoliating device and semiconductor-device manufacturing method, by adjusting the interval between the lift-off pins corresponding to the size of a target semiconductor chip, it is possible to make the semiconductor chip easy to be exfoliated from the adhesive sheet, although there is a difference in size of the semiconductor chips adhered to the adhesive sheet.

FIG. 1 is a perspective view of a semiconductor-device manufacturing apparatus including a semiconductor-chip exfoliating device in accordance with an embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of a semiconductor-chip exfoliating device of FIG. 1 ;

FIG. 3 is a plan view of the lift-off unit of FIG. 2 ;

FIG. 4 is a longitudinal sectional view showing a state where one semiconductor chip is raised together with the adhesive sheet by a pair of needle pins;

FIG. 5 is a longitudinal sectional view of the semiconductor-chip exfoliating device where an interval between the needle pins is changed;

FIG. 6 is a plan view of the lift-off unit of FIG. 5 ; and

FIGS. 7A and 7B are longitudinal sectional views of the semiconductor-chip exfoliating device, in which FIG. 7A shows one state where one semiconductor chip is raised by a leading needle pin and FIG. 7B shows another state where one semiconductor chip is raised by the needle pins.

An embodiment of the present invention will be described with reference to attached drawings.

As shown in FIG. 1 , a manufacturing apparatus for semiconductor devices includes a wafer stage 2 for mounting a semiconductor wafer (not shown) thereon. The wafer stage 2 comprises a base 3 , a first table 4 and a second table 5 both mounted on the base 3 . The second table 5 carries an adhesive sheet 6 to which a plurality of semiconductor chips 1 are adhered. The first table 4 is movable in both directions of X-axis and Y-axis. While, the second table 5 is rotatable about Z-axis in the direction of θ. For convenience of explanation, the first table 4 and the second table 5 will be referred to as “XY-axes table 4 ” and “θ table 5 ” respectively, hereinafter. The semiconductor chips 1 are produced by cutting off a piece of semiconductor wafer, which is adhered to the adhesive sheet (so-called “dicing sheet”) 6 , by means of a dicing saw (not shown) vertically and horizontally. After cutting off the wafer, the adhesive sheet 6 is expanded so as to produce a gap between the adjoining semiconductor chips 1 .

A pickup reversing unit 7 is arranged over the θ table 5 . The pickup reversing unit 7 includes a guide 8 , a third table 9 slidable along the guide 8 in the direction of Z-axis, an attachment 10 fixed to the third table 9 and an L-shaped pickup reversing tool 11 rotatably mounted on an end of the attachment 10 . For convenience of explanation, the third table 9 will be referred to as “Z-axis table 9 ” hereinafter. The pickup reversing tool 11 is arranged so as to be rotatable about a joint point to the attachment 10 within an angular range of 180 degrees between one illustrated position with solid lines and another illustrated position with broken lines. The pickup reversing tool 11 is also provided, at a tip thereof, with a pickup head 12 for carrying a semiconductor chip 1 in absorption.

Over the pickup reversing tool 11 , there are a first camera 13 and a second camera 14 . In operation, the first camera 13 is adapted so as to take a picture of the semiconductor chip 1 being mounted on the θ table 5 . Based on imaging signals from the first camera 13 , the semiconductor chip 1 carried in absorption by the pickup head 12 is identified. In detail, the positioning of the θ-table 5 in the directions of X-axis, Y-axis and θ is determined base on the imaging signals outputted from the first camera 13 . On the other hand, the second camera 14 is adapted so as to take a picture of the semiconductor chip 1 being carried in absorption by the pickup head 12 . The shooting of the second camera 14 against the semiconductor chip 1 is carried out when the pickup reversing tool 11 is rotated and consequently located in a position shown with solid lines of FIG. 1 . Based on imaging signals of the second camera 14 , a bonding head 15 is driven to allow a bonding tool 16 to receive a semiconductor chip 1 from the pickup head 12 . The so-delivered semiconductor chip 1 is picturized by a third camera 17 .

The bonding head 15 includes a base 18 . A first table 19 is attached to the base 18 so as to be slidable in the direction of X-axis. A second table 20 is attached to the first table 19 so as to be slidable in the direction of Y-axis. Further, a third table 21 is attached to the second table 20 so as to be slidable in the direction of Z-axis. For convenience of explanation, the first table 19 , the second table 20 and the third table 21 will be referred to as “X-axis table 19 ”, “Y-axis table 20 ” and “Z-axis table 21 ”, respectively. A fourth table 22 is attached to the Z-table 21 so as to be rotatable about Z-axis in the direction of θ. The fourth table 22 will be also referred to “θ table 22 ” after. The θ table 22 is provided with the above bonding tool 16 . Thus, the bonding tool 22 is movable in the directions of X-axis, Y-axis Z-axis and θ, respectively.

Below the bonding head 15 , there is a bonding stage 23 which is movable in the direction of X-axis. A substrate 24 is mounted on the bonding stage 23 . The semiconductor chip 1 delivered to the bonding tool 16 is installed on the substrate 24 .

A guide 25 is arranged above the bonding stage 23 . A table 26 is attached to the guide 25 so as to be slidable in the direction of Y-axis. A fourth camera 27 is attached to the so-called “Y-axis” table 26 so as to be movable in the direction of Z-axis. The fourth camera 27 is adapted so as to take a picture of a semiconductor chip 1 mounted on the substrate 24 . Thus, the fourth camera 27 is movable in the directions of X-axis, Y-axis and Z-axis relatively to the substrate 24 on the bonding stage 23 .

FIG. 2 shows a semiconductor-chip exfoliating device forming the semiconductor-device manufacturing device. Inside the θ table 5 , as shown in FIGS. 2 and 3 , there are a backup holder 28 (as a holder of the invention) in the form of a hollow cylinder, a lift-off unit 29 accommodated in the backup holder 28 and a decompressor (not shown) for reducing pressure in the backup holder 28 .

The backup holder 28 is adapted so as to be slidable in the θ table 5 in both directions of X-axis and Y-axis, together with the lift-off unit 29 accommodated in the holder 28 . The backup holder 28 has a top wall 28 a opposed to the lower surface of the adhesive sheet 6 through a slight gap. In the backup holder 28 , the top wall 28 a is formed with through-holes 31 a , 31 b through which later-mentioned needle pins 30 a , 30 b (as lift-off pins of the invention) move in and out. The through-hole 31 a is shaped to be a circular hole, while the through-hole 31 b is shaped to be an elongated hole. The through-hole 31 a is positioned to be an extension of the through-hole 31 b in the longitudinal direction.

In operation, the lift-off unit 29 lifts off a semiconductor chip 1 by the needle pins 30 a , 30 b to exfoliate the chip 1 from the adhesive sheet 6 . The lift-off unit 19 includes the above needle pins 30 a , 30 b , shuttle mechanisms 32 a , 32 b and a sliding unit 33 .

The needle pins 30 a , 30 b have respective one ends opposed to the through-holes 31 a , 31 b and the other ends abutting on eccentric cams 33 a , 33 b , respectively. When the needle pins 30 a , 30 b reciprocate in their axial direction to allow the respective ends to project from the through-holes 31 a , 31 b , one semiconductor chip 1 is lifted up together with the adhesive sheet 6 .

The shuttle mechanisms 32 a , 32 b are provided to reciprocate the needle pins 30 a , 30 b in the axial direction and comprise the above cams 33 a , 33 b abutting on the other ends of the needles pins 30 a , 30 b and motors 34 a , 34 b connected to the cams 33 a , 33 b , respectively. The cam 33 a is formed with a width “a” smaller than a width “b” of the cam 33 b . When the motors 34 a , 34 b are driven to rotate the cams 33 a , 33 b , the needle pins 30 a , 30 b reciprocate in the axial direction. Not-shown urging means, such as springs, are attached to the needle pins 30 a , 30 b . The urging means urge the pins 30 a , 30 b in the direction to abut their other ends on the cams 33 a , 33 b , respectively.

The lift-off timing of the needle pins 30 a , 30 b is switchable between an operation mode of the same timing and another operation mode of different timings. When the former mode of the same timing is selected, the motors 34 a , 34 b are driven at the same timing, so that the needle pins 30 a , 30 b are lifted up at the same timing. On the other hand, when the later mode of the different timings is selected, the motors 34 a , 34 b are driven at the different timing, so that the needle pins 30 a , 30 b are lifted up one by one with a time difference.

The sliding unit 33 is constructed so as to slide the needle pin 30 b in the direction to change an interval between the needle pin 30 a and the needle pin 30 b . The sliding unit 33 includes a slide shaft 35 perpendicular to the needle pins 30 a , 30 b , a female screw part 36 fixed to the slide shaft 35 , a ball screw shaft 37 screw-engaged with the female screw part 36 and a motor 38 connected to the ball screw shaft 37 .

The slide shaft 35 is formed with through-holes 39 a , 39 b into which the needle pins 30 a , 30 b are inserted. The through-hole 39 a for the needle pin 30 a is shaped to be an elongated hole. The through-hole 39 b for the needle pin 30 b is shaped to be a circular hole having an inner diameter somewhat larger than the outer diameter of the needle pin 30 b . The through-hole 39 b is positioned to be an extension of the through-hole 39 a in the longitudinal direction.

The operation of exfoliating the semiconductor chip 1 from the adhesive sheet 6 with use of the lift-off unit 29 will be described below. When a semiconductor chip 1 to be exfoliated is determined based on the shooting result by the first camera 13 , the backup holder 28 is moved to a position beneath the semiconductor chip 1 on determination.

After the backup holder 28 reaches the position beneath the target semiconductor chip 1 , the above decompressor is started to drive. Consequently, air inside the backup holder 28 is sucked in the decompressor and simultaneously, outside air is also sucked in the backup holder 28 through the through-holes 31 a , 31 b . With this air suction into the backup holder 28 via the through-holes 31 a , 31 b , the adhesive sheet 6 is absorbed onto the top wall 28 a of the back up holder 28 .

After a predetermined time has passed since the decompression was started by the decompressor, the motors 34 a , 34 b are driven to rotate the cams 33 a , 33 b , causing the needle pins 30 a , 30 b to be pushed up, as shown in FIG. 4 . The tips of the needle pins 30 a , 30 b pushed up by the cams 33 a , 33 b rise through the through-holes 31 a , 31 b and lift off one semiconductor chip 1 while being adhered to the adhesive sheet 6 . Then, the adhesive sheet 6 just under the so-pushed semiconductor chip 1 is partially expanded to weaken the bonding property between the semiconductor chip 1 and the adhesive sheet 6 , making the chip 1 easy to be exfoliated from the adhesive sheet 6 .

Corresponding to the size of the semiconductor chip 1 , the interval between the needle pins 30 a , 30 b is established so that they can lift off chip's margins on both sides of the semiconductor chip 1 .

Further, in the timing synchronous with the lifting operation of the needle pins 30 a , 30 b , the pickup head 12 is moved to a position above the semiconductor chip 1 and successively, it is carried in absorption by the pickup head 12 .

The semiconductor chip 1 carried in absorption by the pickup head 12 is delivered to the bonding tool 16 of the bonding head 15 and subsequently installed on the substrate 24 mounted on the bonding stage 23 .

FIGS. 5 and 6 are views explaining the operation of the lift-off unit 29 directed to semiconductor chips 1 A adhered to the adhesive sheet 6 , each of which is larger than the afore-mentioned semiconductor chip 1 . In case of such a large-sized semiconductor chip, the interval between the needle pins 30 a , 30 b is also increased correspondingly.

When it is required to increase the interval between the needle pins 30 a , 30 b , the sliding unit 33 is operated to slide only the needle pin 30 b on the cam 33 b in a direction to depart from the other needle pin 30 a . For this purpose, the motor 38 is driven to slide the slide shaft 35 to the right in the figures through the use of screw-engagement of the ball screw shaft 37 with the female screw part 36 . With the sliding of the slide shaft 35 to the right, the needle pin 30 b inserted into the through-hole 39 b having the inner diameter somewhat larger than the outer diameter of the pin 30 b is slid on the cam 33 b to the right together with the slide shaft 35 . While, the other needle pin 30 a inserted into the through-hole 39 a in the form of an elongated hole does not slide to the right due to no interference with an inner sidewall of the through-hole 39 a in spite of the sliding of the needle pin 30 b . In this way, the interval between the needle pins 30 a , 30 b is increased.

A final interval between the needle pins 30 a , 30 b resulting from the rightward sliding of the needle pin 30 b is determined corresponding to the size of the semiconductor chip 1 A to be lifted off by the needles 30 a , 30 b . The final interval is established so that the needle pins 30 a , 30 b can lift off chip's margins on both sides of the semiconductor chip 1 A.

Note, the stable needle pin 30 a is maintained so that its tip opposes the through-hole 31 a , while the movable needle pin 30 b is maintained so that its tip opposes the through-hole 31 b in form of an elongated hole.

As mentioned before, the cam 33 b is formed with a width “b” larger than that of the cam 33 a . The formation of the cam 33 b is provided for the purpose of maintaining the abutment of the cam 33 b on the other end of the needle pin 30 b in spite of its sliding.

As shown in FIGS. 5 and 6 , after adjusting the interval between the needle pins 30 a , 30 b corresponding to the size of the semiconductor chip 1 A, the backup holder 28 is moved to a position beneath the semiconductor chip 1 A to be exfoliated from the adhesive sheet 6 , similarly to the above case of exfoliating the semiconductor chip 1 and simultaneously, the decompressor is driven to allow the backup holder 28 to absorb the adhesive sheet 6 on the top wall 28 a . Next, the motors 34 a , 34 b are driven to rotate the cams 33 a , 33 b , causing the needle pins 30 a , 30 b to be pushed up. The tips of the needle pins 30 a , 30 b pushed up by the cams 33 a , 33 b rise through the through-holes 31 a , 31 b to lift off the semiconductor chip 1 A while being adhered to the adhesive sheet 6 .

In this way, for the semiconductor chips of different sizes, it is possible to make the interval of the needle pins 30 a , 30 b address a target semiconductor chip, allowing an abutment of the pins 30 a , 30 b on the chip's margins on both sides of the chip. Thus, it is possible to exfoliate the semiconductor chips 1 , 1 A of difference sizes from the adhesive sheet 6 appropriately.

As for the lift-off timing of the needle pins 30 a , 30 b , there may be optionally selected either the operation mode of the same timing or the operation mode of the different timing, as similar to the above-mentioned case. When selecting the former mode of the same timing, the motors 34 a , 34 b are driven at the same timing, so that the needle pins 30 a , 30 b are lifted up at the same timing. On the other hand, when selecting the later mode of the different timing, the motors 34 a , 34 b are driven at the different timings, so that the needle pins 30 a , 30 b are lifted up one by one with a time difference. For instance, as shown in FIG. 7A , only the needle pin 30 a is lifted up at first. Then, after the lapse of a predetermined time since the rising of the pin 30 a , the remained needle pin 30 b is lifted up as shown in FIG. 7B .

As shown in FIGS. 7A and 7B , by lifting up the needle pins 30 a , 30 b with a time difference therebetween, the adhesive sheet 6 beneath the semiconductor chip 1 A is drawn in twice of one expansion by the needle pin 30 a and another expansion by the needle pin 30 b , so that the adhesive joint between the semiconductor chip 1 A and the adhesive sheet 6 can be further weakened in comparison with a single expansion of the same timing, making the chip 1 A easier to be exfoliated from the adhesive sheet 6 .

The semiconductor chip 1 A lifted off by the needle pins 30 a , 30 b is carried in absorption by the pickup head 12 and further delivered to the bonding tool 16 of the bonding head 15 . Finally, the so-delivered semiconductor chip 1 A is installed on the substrate 24 mounted on the bonding stage 23 .

In this way, according to the present invention, by adjusting the interval between the lift-off pins corresponding to the size of a target semiconductor chip, it is possible to make the semiconductor chip easy to be exfoliated from the adhesive sheet despite that there is a difference in size of the semiconductor chips adhered to the adhesive sheet.

In a modification, the number of lift-off pin may be increased to lift off one semiconductor chip in more stable condition, although the illustrated embodiment adopts a pair of lift-off pins.

Additionally, the lift-off pins may be moved up and down by the other appropriate means, such as linear actuators, although they are driven due to their abutment on the eccentric cams 33 a , 33 b rotated by the motors 34 a , 34 b in the illustrated embodiment,

Although the present invention has been described above by reference to one embodiment of the invention, this invention is not limited to this and modifications will occur to those skilled in the art, in light of the teachings. The scope of the invention is defined with reference to the following claims.

This application is based upon the Japanese Patent Applications No. 2007-067974, filed on Mar. 16, 2007, the entire content of which is incorporated by reference herein.