JP3530517B2 - Flip chip mounting device with alignment correction function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to alignment of a semiconductor chip and a circuit board in an apparatus for flip-chip mounting a semiconductor chip and a circuit board.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for further miniaturization and weight reduction of circuit boards in mobile information communication-related equipment and the like, higher performance due to higher frequencies, and cost reduction. Therefore, flip chip mounting, which enables direct mounting of a semiconductor chip and a circuit board, is effective. Further, miniaturization and high integration of semiconductor chips are also progressing, and along with this, miniaturization of electrode pad size in flip chip mounting and miniaturization of pitch between electrode pads are also progressing.

Most of flip-chip mounting represented by gold-gold bonding is diffusion bonding, and a self-alignment effect cannot be obtained unlike solder bonding which is fusion bonding, and therefore, positioning accuracy at the time of mounting is high. Becomes the mounting accuracy of flip chip mounting as it is.

The alignment mark of the circuit board (hereinafter referred to as "alignment mark") used for alignment during mounting is usually formed by etching near the mounting area where the semiconductor chip is mounted and outside the mounting area. In many cases, the etching solution generally flows in a certain direction due to stirring.

However, the alignment mark on the circuit board depends on the etching factor such as the flowing direction of the etching solution at the time of etching. Especially, in the case of a circuit board having a conductor thickness of about 20 μm or more, the alignment mark does not have the designed shape. Instead, the shape may be distorted from the top surface of the alignment mark to the alignment mark formation surface (bottom surface).

[0006]

If the center of gravity is obtained by imaging such an alignment mark with a camera, a deviation from the designed center point will occur. Further, since the distortion of the alignment mark shows the same tendency depending on the manufacturing lot of the circuit board, the above-mentioned deviation occurs in the whole manufacturing lot of the circuit board, and as a result, there is a problem that highly accurate flip chip mounting cannot be realized. . Further, the electrode pad size and the pitch between the electrode pads must be determined in consideration of the above-mentioned deviation, which causes a problem that the miniaturization of the electrode pad size and the miniaturization of the pitch between the electrode pads are hindered.

The present invention has been made in view of the above-mentioned circumstances, and realizes a more accurate flip chip mounting, and further enables a finer electrode pad size and a finer pitch between electrode pads. The purpose is to provide a device.

[0008]

In order to solve the above-mentioned problems, a flip-chip mounting apparatus with an alignment correction function according to the present invention forms a semiconductor chip in which bumps are formed on electrode pads on a bonding surface by the electrode pads. A flip-chip mounting device for performing face-down mounting after aligning with a printed circuit board, wherein at least two alignment marks on the semiconductor chip and at least two alignment marks on the circuit board are imaged by a camera, Find the X and Y coordinates of the centroid of the alignment mark,
Flip-chip mounting is performed based on this coordinate data, and an infrared microscope that detects infrared light of a wavelength that passes through the silicon portion of the semiconductor chip is used to detect the silicon portion of the semiconductor chip after the flip-chip mounting. Through transmission imaging, at least two predetermined electrode pads on the semiconductor chip and the corresponding electrode pads on the circuit board are detected and compared to determine the X-axis direction and the Y-axis direction or further. The feature is that the shift amount in the θ-axis direction is obtained and this shift amount is used as a correction value in the subsequent alignment. (Invention according to claim 1)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram and a functional block diagram of the flip-chip mounting apparatus with the alignment correction function. FIG. 2 is a side view of the circuit board and the semiconductor chip after flip-chip mounting when the alignment mark is distorted. FIG. 3 is a diagram of a case where FIG. 2 is viewed through an infrared microscope and imaged. Figure 4
[FIG. 6] is a side view of the circuit board and the semiconductor chip after flip-chip mounting when the alignment mark is as designed. FIG. 5 is a diagram of a case where FIG. 4 is seen through with an infrared microscope and is imaged.

1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5, 10 is a semiconductor chip having a circuit formed on a silicon substrate, 11a and 11b are alignment marks of the semiconductor chip 10, and 121 ... 12n are semiconductor chips. 13n are gold bumps formed on the electrode pads 121 ... 12n of the semiconductor chip 10, 20 is a circuit board, 21a and 21b are alignment marks of the circuit board 20, 221 ... 22n are electrodes of the circuit board 20. Pads, 2
31 ... 23n are electrode pads 221 ... 22 of the circuit board 20.
n is a wiring pattern, 30 is a bonding stage that holds the circuit board 20, and 31 is the semiconductor chip 1 during alignment.
0 alignment marks 11a and 11b, circuit board 2
A camera for picking up the alignment marks 21a and 21b of 0, a beam splitter 32 for picking up images of the semiconductor chip 10 and the circuit board 20 at the same time by the camera 31, and a suction tool 33 for holding the semiconductor chip 10,
Reference numeral 34 is an elevating arm that attaches the suction tool 33 and moves up and down. Reference numeral 35 drives the elevating arm 34 and the semiconductor chip
0 is a pressurizing section for joining the circuit board 20, 36 is an inspection stage for holding the circuit board 20 after the semiconductor chip 10 is joined,
37 detects infrared rays having a wavelength of 900 nm to 1200 nm that pass through the silicon portion of the semiconductor chip 10 after bonding,
12n of the semiconductor chip 10 and the electrode pads 221 ... 22n of the circuit board 20. Reference numeral 41 denotes alignment marks 11a and 11b of the semiconductor chip 10 imaged by the camera 31, alignment marks 21a of the circuit board 20, and 21b image data 2
A camera image processing unit 47 for quantifying and calculating the coordinates of the center of gravity, 47 is the electrode pads 121 and 12n of the semiconductor chip 10 imaged by the infrared microscope 37, and the electrode pad 22 of the circuit board 20.
An infrared image processing unit for binarizing the image data of 1 and 22n to obtain the coordinates of the center of gravity, and 48 is the coordinates of the center of gravity of the alignment marks 11a, 11b, 21a and 21b obtained by the camera image processing unit 41, and the infrared image processing. A coordinate calculation unit that performs a calculation for alignment from the coordinates of the center of gravity of the electrode pads 121, 12n, 221 and 22n obtained by the unit 47, and 49 is the pressure control for the pressure unit 35 and / or the bonding stage 30 and / or the addition stage. It is a control unit that performs alignment control for the pressure unit 35.

The alignment mark 21a shown in FIG. 2 and FIG.
The shape of the alignment mark 21b and the alignment mark 21b is X
An example is shown in which the shaft extends to the left.
The dotted lines in the alignment marks 21a and 21b in FIG. 2 indicate the shapes as designed.

First, in FIG. 1, the semiconductor chip 10 is attached to the suction tool 33, and the circuit board 20 is attached to the bonding stage 30.

Next, the control section 49 moves the camera 31 and the beam splitter 32 in the direction of the arrow so that the camera 31 images the alignment marks 21a and 21b of the circuit board 20. When the image data captured by the camera image processing unit 41 is binarized, the shaded areas in FIG. 3 can be detected, so the X and Y coordinates of these centroids are determined. Similarly, regarding the alignment marks 11a and 11b of the semiconductor chip 10, the image data captured by the camera image processing unit 41 is also binarized to obtain the X and Y coordinates of the center of gravity. Based on these coordinates, the coordinate calculation unit 48 calculates the position, and the control unit 49 controls the bonding stage 30 and / or the pressure unit 35 based on the calculation result.
Is moved in the X-axis direction and the Y-axis direction or further in the θ-axis direction to perform alignment.

The operation of aligning the circuit board 20 and the semiconductor chip 10 is carried out by either the bonding stage 30 holding the circuit board 20 or the pressing section 35 holding the semiconductor chip 10 by the suction tool 33, or Both of them work together to move in the X-axis direction and the Y-axis direction, or further in the θ-axis direction.

After the image pickup of the four alignment marks is completed, the controller 49 moves the camera 31 and the beam splitter 32 in the directions of the arrows to return them to their original positions.

Here, in FIG. 3, the deviation amount of the coordinates of the center of gravity of the alignment mark 21a is Δxma and Δyma from the designed position. Similarly, the amount of deviation of the coordinates of the center of gravity of the alignment mark 21b is Δxmb and Δymb from the designed position. However, it is difficult to accurately measure the amount of these deviations before flip-chip mounting, and even if it is possible to correct the position of the semiconductor chip 10 using this deviation amount, it is necessary to correct the position at the time of subsequent bonding. Since it is not a good idea because mechanical error will occur further, it is not corrected in the first time.

After the alignment is completed, the control unit 49 controls the pressure unit 3
5 is instructed to pressurize (lower) for joining. The pressure unit 35 moves the elevating arm 34 in the direction of the arrow to flip-chip mount the semiconductor chip 10 on the circuit board 20. After the flip chip mounting, the control unit 49 controls the suction tool 3
3, the semiconductor chip 10 is removed, and the pressing unit 3
Instruct to 5 and move the lifting arm in the direction of the arrow to return it to the original position.

After the first flip-chip mounting, the circuit board 20 is mounted on the inspection stage 36 in the direction of the arrow in FIG.
To the semiconductor chip 1 by using the infrared microscope 37 capable of being imaged through the silicon portion of the semiconductor chip 10.
0 two predetermined electrode pads 121 and 12n,
Corresponding to this, two electrode pads 2 on the circuit board 20
21 and 22n are imaged. The image data captured by the infrared image processing unit 47 is binarized, and the X coordinate and the Y coordinate of the total of four centroids are obtained.

The circuit board 20 may be moved to the position of the inspection stage 36 while the bonding stage 30 holds the circuit board 20. Alternatively, the circuit board 20 may be removed from the bonding stage 30 and the inspection stage 36 may be moved. It may be newly attached to.

Next, in the coordinate calculation unit 48, the semiconductor chip 1
From the coordinates of the center of gravity of the electrode pad 121 on 0 and the coordinates of the center of gravity of the corresponding electrode pad 221 on the circuit board 20,
The deviations Δx1 and Δy1 of the electrode pads 121 of the semiconductor chip 10 after flip-chip mounting from the original positions are obtained.

Similarly, in the coordinate calculation unit 48, from the coordinates of the center of gravity of the electrode pad 12n on the semiconductor chip 10 and the coordinates of the center of gravity of the corresponding electrode pad 22n on the circuit board 20, the semiconductor after flip chip mounting is carried out. Deviation of the electrode pad 12n of the chip 10 from its original position, Δxn and Δyn
Ask for.

Further, the coordinate calculation unit 48 calculates Δx1 and Δy.
From 1, Δxn and Δyn, the deviation from the original position of the center of the semiconductor chip 10, Δx, Δy, and Δθ are obtained.

Here, taking advantage of the fact that the distortions of the alignment marks 21a and 21b of the circuit board 20 show the same tendency depending on the manufacturing lot of the circuit board 20, the coordinates are used in the alignment in the second and subsequent flip-chip mounting. The values of Δx, Δy, and Δθ obtained above by the calculation unit 48 are used as correction values. That is, from the positions obtained from the alignment marks 21a and 21b of the circuit board 20 and the alignment marks 11a and 11b of the semiconductor chip 10, they are displaced by -Δx in the X coordinate direction and by -Δy in the Y coordinate direction,
By shifting (rotating) by −Δθ in the θ coordinate direction, more accurate alignment becomes possible.

The correction values Δx, Δy and Δθ obtained by using the above infrared microscope 37 are obtained only after the first flip-chip mounting, and the first correction values are used for the second and subsequent alignments.
The correction may be performed using the correction value for the second time, but if possible, the correction value may be calculated each time, or may be calculated again immediately after the manufacturing lot of the circuit board 20 is switched, and the correction value may be used for the next alignment. desirable.

Here, the method of obtaining the correction value every time has a merit that it is not necessary to control the manufacturing lot of the circuit board 20 although a time loss occurs, and conversely, the correction value of the circuit board 20 is obtained. The method of re-obtaining immediately after changing the manufacturing lot requires management of the manufacturing lot of the circuit board 20, but has an advantage that time loss is small.

Further, the above-mentioned position adjustment may be carried out manually by manual input, but more preferably, it is preferably carried out automatically without human labor and without input error.

The positions of the predetermined electrode pads 121 and the electrode pads 12n on the semiconductor chip 10 and the corresponding positions of the electrode pads 221 and 22n on the circuit board 20 are on the diagonal line of the semiconductor chip 10. Needless to say, it is desirable to set the distance to as long as possible so that the measurement can be performed more accurately.

[0028]

As described above, according to the flip-chip mounting apparatus with the alignment correction function of the present invention, the positional deviation amount, Δx, Δy, and Δθ in the flip-chip mounting due to the distortion of the alignment mark is obtained, and next time Higher precision flip chip mounting can be realized by correcting this misalignment amount during alignment in the subsequent flip chip mounting. Furthermore, in consideration of the above misalignment amount, the electrode pad size of the circuit board and the gap between the electrode pads can be estimated. It is not necessary to set a large pitch, and it is possible to reduce the size of the electrode pads and the pitch between the electrode pads. (Invention according to claim 1)

Further, by obtaining the deviation amount of the immediately preceding flip chip mounting result each time and using it as the correction value at the time of the next alignment, the flip chip with higher precision can be realized without controlling the change of the manufacturing lot of the circuit board. Can be implemented. (Invention of Claim 2)

Further, by re-calculating the correction value immediately after the change of the circuit board manufacturing lot and using this correction value as a common value for each circuit board manufacturing lot, there is less time loss and higher accuracy. Flip chip mounting is possible. (Invention of Claim 3)

Further, since the correction value is automatically fetched and used, it is possible to perform flip chip mounting with higher accuracy, without requiring any manual labor and without input error.
(Invention of Claim 4)

[Brief description of drawings]

FIG. 1 is an explanatory diagram and a functional block diagram of a flip-chip mounting apparatus with an alignment correction function.

FIG. 2 is a side view of the circuit board and the semiconductor chip after flip-chip mounting when the alignment mark is distorted.

FIG. 3 is a diagram when FIG. 1 is seen through from above with an infrared microscope.

FIG. 4 is a side view of the circuit board and the semiconductor chip after flip-chip mounting when the alignment mark is as designed.

FIG. 5 is a diagram when FIG. 3 is seen through with an infrared microscope from above.

[Explanation of symbols]

10 ... Semiconductor chip 11a ... Alignment mark a of semiconductor chip 11b ... Alignment mark b of semiconductor chip 121 ... Electrode pad 1 of semiconductor chip 12n ... Electrode pad n of semiconductor chip 13 ... Gold bump 20 ... Circuit board 21a ... Alignment mark a on the circuit board 21b ... Alignment mark b on the circuit board 221 ... Electrode pad 1 of the circuit board 22n ... Electrode pad n of the circuit board 23 ... Wiring pattern 30 ... Joining stage 31 ... Camera 32 ... Beam splitter 33… Suction tool 34 ... Lifting arm 35 ... Pressurizing unit 36 ... Inspection stage 37 ... Infrared microscope 41 ... Camera image processing unit 47 ... Infrared image processing unit 48 ... Coordinate calculation unit 49 ... Control unit

Claims (4)

(57) [Claims] 1. A flip-chip mounting apparatus for aligning a semiconductor chip having a bump formed on an electrode pad on a bonding surface with a circuit board having an electrode pad and then performing face-down mounting, at least on a semiconductor chip. The two alignment marks and at least two alignment marks on the circuit board are imaged by a camera, the X and Y coordinates of the center of gravity of the alignment marks are obtained, and alignment is performed based on this coordinate data and flipped. A chip is mounted and a silicon part of the semiconductor chip after the flip-chip mounting is transparently imaged by using an infrared microscope that detects infrared light having a wavelength that passes through the silicon part of the semiconductor chip. Of at least two electrode pads and the corresponding electrode pads on the circuit board are detected. Flip-chip mounting with an alignment correction function characterized by obtaining a displacement amount in the X-axis direction and the Y-axis direction or further in the θ-axis direction by comparison, and using this displacement amount as a correction value in the subsequent alignment. apparatus. 2. The flip-chip mounting apparatus with an alignment correction function according to claim 1, wherein the correction value is used as a correction value by obtaining the deviation amount of the immediately preceding flip-chip mounting result each time. 3. The alignment correction function according to claim 1, wherein the correction value is re-obtained immediately after the manufacturing lot of the circuit board is switched, and the correction value is used as a common value for each manufacturing lot. Flip chip mounting device. 4. The alignment operation after the second alignment operation is a alignment operation programmed so as to automatically capture and use the correction value. Flip-chip mounting device with alignment correction function described in.