JPH0412549A - Semiconductor pellet pick up device - Google Patents

Abstract

PURPOSE:To prevent leaving behind good chips on the semiconductor pellet and to reduce wasted work time on picking up by moving an X-Y table in a specified direction after perceiving the positional relationship between the virtual circle equation for a wafer and a semiconductor pellet located in the outer edge of a wafer. CONSTITUTION:An operation unit 27, which performs the virtual circle equation for a wafer 18 using the detection results from an optical identification unit 25, and a control mechanism 26, which moves an X-Y table in a specified direction after perceiving the positional relationship between the virtual circle equation and a semiconductor pallet 19 located in the outer edge of the wafer 18, are readied. Since the virtual circle equation can be set as the yardstick for the presence of the outer edge of the wafer 18, time wasted trying to identify the position of the semiconductor pellet 19 using the optical identification unit 25 and time wasted moving the X-Y table 11 can be kept to an absolute minimum. As a result, the need to suspend the semiconductor pellet pick-up process is reduced and operating efficiency is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for temporarily adhering good semiconductor pellets to the surface of a wafer sheet during the manufacture of semiconductor devices such as die bonding onto the base of a predetermined glued frame. Semiconductor pellets formed in a square pattern on a disk-shaped wafer in plan view are
This invention relates to a semiconductor pellet pickup device for picking up semiconductor pellets by suction with a suction collet located on the side of the Y table.

[Technical background]

This type of pickup device, as disclosed in, for example, the prior art Japanese Patent Laid-Open No. 57-68042, uses a wafer that is made of silicon or the like and has a disk shape in plan view.
After forming a large number of semiconductor pellets such as semiconductor elements and integrated circuits at once, the wafer is divided and each semiconductor pellet is picked up. A wafer l is temporarily attached to a sheet 2, the wafer sheet 2 is stretched over a ring body 3, the wafer 1 is broken and subdivided into individual semiconductor pellets 4, and then the wafer sheet 2 is attached to a ring body 3. The semiconductor pellets 4 are set so as to extend radially outward in a radial direction so that adjacent semiconductor pellets 4 are spaced apart from each other.

A pickup device consisting of a push-up body 5 that pushes up the semiconductor pellets 4 arranged in a square pattern on the wafer sheet 2 from a position below the wafer sheet 2, and a vacuum suction collet 6 on the upper side, as described below. The lead frame is vacuum-adsorbed and transported onto the lead frame.

That is, as described above, in order to sequentially pick up good semiconductor pellets 4 from a large number of semiconductor pellets 4 arranged in a grid pattern, the ring body 3 on which the wafer sheet 2 is stretched is placed on an XY table (not shown). A push-up body 5 is fixed at a position below the wafer sheet 2 and is provided on the inner diameter part of the ring body 3 so as to be able to swing up and down.

An optical recognition means 7 such as a video camera is disposed directly above the push-up body 5, and by moving the XY child table in the X direction and/or the X direction, the optical recognition means 7 is
Then, the quality of the shape, characteristics, etc. of the semiconductor pellet 4 and whether or not the semiconductor pellet 4 is located directly above the push-up body 5 are recognized. Note that the quality of the characteristics of the semiconductor pellets is determined by marking the surface of defective semiconductor pellets in a preliminary inspection. If it is judged to be a good product, the push-up body 5 is raised and the vacuum suction collet 6 is brought close to the semiconductor pellet 4, and the conductor pellet 4 temporarily attached to the upper surface of the wafer sheet 2 is removed by the vacuum suction collet 6. Pick it up.

Next, in order to pick up the good semiconductor pellet 4 in the horizontal position, the XY child table is moved laterally in the X direction by a predetermined pitch as shown in FIG. The process of determining the quality of the shape, etc., and the presence or absence and location of semiconductor chips and cracks is repeated.

When the push-up body 5 is located below the outer peripheral edge (radially outward), the XY child table
After performing a U-turn operation in which the semiconductor pellet 4 is shifted by -step in the vertical direction and then moved to the right along the be.

[Prior art and problems to be solved by the invention] At this time, the conventional technology had the following problems.

That is, when the optical recognition means 7 determines whether or not the semiconductor pellets 4 are good or not, there are chipped spots (where the semiconductor pellets have fallen off the wafer sheet) in the semiconductor pellets 4 arranged in a grid pattern. Also, the wafer l
There are various sizes (large and small diameters in plan view), and when the wafer sheet 2 is stretched over the ring body 3, the wafer 1 may be placed at a position offset from the center of the ring body 3. For these reasons, even if it is determined that there is no semiconductor pellet 4 - times, the XY child table is not immediately moved in the X direction and performs a U-turn, but it repeats the movement in the The U-turn operation is performed only when it is determined that the semiconductor pellet 4 is definitely not present.

In addition, regardless of the discrimination by such optical recognition means 7,
As shown in FIG. 9, a touch sensor 8 having a disk shape or a link shape in a plan view is mounted on the upper outer periphery of the push-up body 5, and the push-up body 5, which is located outside the outer periphery of the wafer l in a plan view, is pressed multiple times. When the touch sensor 8 comes into contact with the lower surface or the inner peripheral edge 3a of the ring body 3 on which the wafer sheet 2 is stretched, when it is moved up and down to perform so-called blank firing, it is assumed that there is no semiconductor pellet 4 above it. I was trying to make a U-turn based on my judgment.

However, even though there is actually no semiconductor pellet, the timing of the U-turn is delayed, resulting in a loss of time for extra recognition work and time for moving the XY child table. In addition, since the pick-up operation must be interrupted during that time, there is a problem in that the efficiency of subsequent processes such as die bonding is reduced.

The present invention aims to solve this problem.

[Means to solve the problem]

In order to achieve this object, the present invention temporarily adheres a disk-shaped wafer in a plan view having semiconductor pellets formed in a grid shape to the surface of a wafer sheet, arranges the wafer sheet on an XY child table, and In an apparatus that recognizes the position and shape of semiconductor pellets in plan view using an optical recognition means, and picks up good semiconductor pellets among them with a suction collet, an equation of a virtual circle of the wafer is calculated from the detection results of the optical recognition means. The apparatus is equipped with a calculation means and a control means for determining the positional relationship between the equation of the virtual circle and the semiconductor pellet located at the outer peripheral edge of the wafer and driving the XY child table in a predetermined direction.

[Operation and effects of the invention]

In this way, by comparing and determining the equation of the virtual circle of the wafer and the position of the semiconductor pellet located at the outer periphery of the actual wafer that can be recognized and detected by the optical recognition means, the equation of the virtual circle is Since the presence of the outer periphery of the semiconductor pellet can be used as a guideline, wasted time for recognizing the semiconductor pellet by the optical recognition means and wasted time for moving the XY child table can be minimized, and the work of picking up the semiconductor pellet can be This has the remarkable effect of reducing interruptions and improving work efficiency.

〔Example〕

Next, an embodiment will be described. FIG. 1 is a schematic side view of the pickup device, and reference numeral 10 is a mounting table with a U-shaped side cross section provided on the XY table II.
consists of an X-direction moving table 13 that moves in the X direction by an X servo motor 12, and a Y-direction moving table 15 that moves in the Y direction by a Y servo motor 14.

A wafer jig 17, such as a ring-shaped wafer jig, on which a wafer sheet 16 is stretched is set on the top plate 10a of the mounting table 10. A wafer 18 is temporarily attached to the upper surface (surface) of this wafer sheet 16, which has elasticity.1.
The wafer 18 is broken into individual semiconductor pellets 19.
After dividing the wafer sheet 16 into small pieces, the wafer sheet 16 is further expanded radially outward from the wafer jig 17, and adjacent semiconductor pellets 19 are spaced apart to form a square pattern (
Set it so that it is aligned in the pattern of the base.

Semiconductor pellets 19 arranged in a square pattern on the wafer sheet 16 are set above the hollow hole 20 of the top plate 10a of the mounting table 10, and below the top plate 10a of the mounting table 10. The push-up body 22 that pushes up the wafer sheet 16 from the back (bottom) side is connected to the actuator 21.
The push-up body 22 is positioned at an upper position on the vertical axis and can be moved vertically and horizontally by driving an actuator 24 such as a servo motor. A vacuum suction collet 23 is disposed above the collet 23, and an optical recognition means 25 such as a video camera using a CCD type image pickup device or the like is further provided above the collet 23.

This optical recognition means 25 detects the semiconductor pellet 19 on the mounting table 10 which is moved in the XY plane by the XY child table 1.
The image data is image-processed by the central processing unit 27.

FIG. 3 is a block diagram of the control means 26 of the present invention, which includes a read-only memory (ROM), a read/write memory (R
It has a 16-bit or 32-bit central processing unit 27 equipped with a memory such as AM) and an input/output interface, and the video signal of the image information obtained by the optical recognition means 25 is passed through an A/D converter 28. The image data is stored in the image memory unit 29, and becomes data for calculation, discrimination, etc. in the central processing unit 27 as described later.

Reference numeral 30 indicates the servo motor 12, 14 or actuator 21.
, 24, etc., is a pulse generator for synchronous operation,
31.32 is a limit switch when setting the XY child table 1 to the reference position (origin O), 33.34
is a drive circuit for the X servo motor 12 and Y servo motor 14.

Next, operation control of the pickup will be explained.

By moving the XY child table 1 in the X direction and/or the Y direction, the optical recognition means 25 disposed directly above the push-up body 22 determines whether the shape and characteristics of the semiconductor pellet 19 are good or not, and the semiconductor pellet concerned. 19 is located directly above the push-up body 22, and if it is determined to be a good product, the vacuum suction collet 23, which raises and lowers the push-up body 22, picks up the semiconductor pellet) 19.
After picking up the XY child table and laterally moving it in the X direction by a predetermined pitch, the optical recognition means 25
It is the same as the conventional method to repeat the process of determining the quality of the shape, etc. of the semiconductor pellet 19 directly below it, as well as the presence or absence and position of the semiconductor pellet, and picking up a good semiconductor pellet 19.

Then, by repeating this intermittent movement in the X direction,
When the center position of the push-up body 22 reaches a position radially outward beyond the outer circumferential edge of the expanded wafer 18 which has a disk shape in plan view, the good semiconductor pellet 19 located closest to the outer circumferential edge is removed. In order to be able to pick up the object, the XY child table 1 is moved one step in the Y direction, making a so-called U-turn.

Next, the outline of U-turn control of the XY child table 1 of the present invention will be explained with reference to the flowchart of FIG.

Note that when the wafer sheet 16 having the aligned semiconductor pellets 19 is mounted on the wafer jig 17, the center of the circle of the disk-shaped wafer 18 in plan view is concentric with the center of the wafer jig 17 in plan view. It is assumed that there are errors.

First, in step 501 following the start and initial setting, the XY child table 1 is brought into contact with the limit switches 31 and 32 that detect the origin (0) to perform a so-called origin return, and then input data to the control means 26. Or, by teaching control detected by the optical recognition means 25, the data (circle equation) of the expanded virtual circle OL of the wafer 18 is stored in software (steps 502 and 503).

Note that when returning to the origin as described above, Ueno 1 jig 17
Assume that the wafer 18 is located in the first quadrant of the XY plane, and as shown in FIGS. 4 and 6, there is a positional correspondence relationship between the center position Oo of the push-up body 22 and the origin O in plan view. is determined automatically. That is, the coordinates (a, b) of the center position OO are determined and can be calculated.

In the case of teaching control, X
The Y child table 1 is moved, and the maximum position Max and the minimum position Min in the Y direction of the outer peripheral edge of the wafer 18 are
The optical recognition means 25 reads the Y coordinate value or the XY coordinate value of a position near the Y coordinate value (step 502). By this reading, the diameter or radius (r) of the virtual circle OL of the expanded wafer 18 can be calculated, and the center position 0
Since the coordinates (a, b) of 0 are known as mentioned above,
The coordinates of the center position OO of the push-up body 22 and the virtual circle OL
The equation of the virtual circle OL, assuming that the center of the circle coincides with the center of the circle, can be obtained using a simple formula (
Step 503).

Incidentally, the equation of this virtual circle is r"=(X-a)"+(Y-b)2.

Next, in step 504, recognition of the semiconductor pellet 19 is started. For example, within the contour in Figure 4,
Semiconductor pellet at the top and rightmost position) 19 [coordinates (A
, B)) The XY child table 1 is operated so that the optical recognition means 25 is positioned above it.

In the case of data input, the degree of expansion of the circle according to the degree of normal expansion is inputted in advance, and the wafer 1
8, the radius of the virtual circle OL of the wafer 18 can be calculated.

In this case as well, since the coordinates of the center position Oo of the push-up body 22 with respect to the origin O are known as described above, the equation of the virtual circle OL can be calculated by calculation in the same manner as described above.

In addition, in both the teaching and data input, the size of the semiconductor pellet 19 and the movement pitch (P x, P y) when moving the XY child table one step at a time in the X direction and the Y direction are input as data. I'll keep it.

In step 505, it is determined whether or not the semiconductor pellet 19 has been recognized. If yes (yes), the recognition result of the semiconductor pellet is determined in step 506.

In step 506, if the semiconductor pellet 19 is recognized as a defective pellet, the process directly proceeds to step 508 without performing the pickup operation.

When the pellet is a good one, a pellet pickup operation is performed in step 507, and after performing the operation,
In step 508, before moving the XY child table 1 by one pitch (P x) in the
Find Px, B). In other words, to set the new coordinates,
Read the coordinate value as A4-A+nPx. n is the number of movements in the X-axis direction.

In this case, as shown in FIG.
When moving to the right in the axial direction, the coordinate value decreases, and when moving to the left, the coordinate value increases. Similarly, as will be described later, when the XY child table 1 is moved downward in the Y-axis direction, the coordinate value increases, and when moved upward in the Y-axis direction, the coordinate value is decreased.

This means that the coordinates of the center position OO of the push-up body 22 are located in the first quadrant of the XY coordinates, and when the Ueno\18 is placed, the XY coordinates are moved closer to the center position Oo.
This is based on the fact that when the child table origin 0 is moved, the coordinate values become smaller.

In step 509, in order to calculate the position where the U-turn should be made, the equation of the virtual circle OL is transformed, and the coordinates on the right semicircle of the virtual circle are: X, ==a+r"-(y-b) ' and the coordinates on the left semicircle, X2 = a-r'' - (y-bF), and in step 510,
In step 8, it is determined whether the X coordinate value (A) when moving in the X-axis direction is on the inner diameter side of the virtual circle OL, and whether it exceeds the coordinate value at which a U-turn is to be made.

When the coordinate value A is within the virtual circle (x +≧A≧X2, in step 511, the next horizontally adjacent semiconductor pellet 19
In order to recognize this, the XY child table 1 is moved to the coordinate values (A, B).

When it is determined in step 510 that the coordinate value A is outside the virtual circle, it is further determined whether or not there is a semiconductor pellet 19 next to it in the X-axis direction (step 512).
.

When the optical recognition means 25 recognizes that there is no semiconductor pellet 19 next to the target semiconductor pellet 19 on the imaging screen 36 (no), the XY child table 1 is moved 1 in the Y-axis direction to immediately make a U-turn. Pituchi (Py)
Calculate the coordinate value B in the Y-axis direction when moving (step 513), and from the y value, create a virtual circle OL similar to the above.
In step 514, calculate the coordinates on the right semicircle, x+=a+r−(i=or the coordinates on the left semicircle, x2=ar=y−b), and use the value of X to calculate the X-axis direction. Find the coordinate value A of (step 515) and move the XY child table 1 to that coordinate value (A, B) (
(See step 511 above).

In this case, the U-turn is as shown in FIG.
If it is determined that there is no semiconductor pellet 19 on the left side of the imaging screen 36 at that stage, the opposite A U-turn is executed to move the semiconductor pellet by one pitch (Px) in the direction to ensure that no semiconductor pellet is left behind.

Further, in step 511, the semiconductor pellet 19 is placed next to the semiconductor pellet 19.
When it is determined that there is, there are the following cases.

That is, if there is a deviation when the wafer sheet 16 is stretched with respect to the wafer jig 17, the center position O of the push-up body 22
This means that the coordinates of o and the center of the virtual circle OL are deviated from each other. Due to this deviation, the semiconductor pellet 19 on the outer periphery of the actual wafer 18 may be recognized on the imaging screen 36 beyond the boundary line of the calculated virtual circle OL (8th
(see figure).

In such a case, it is necessary to correct the coordinates (a, b) of the center position OO of the virtual circle OL.

Step 515 is for correcting the center coordinate value (a) in the X-axis direction in the equation of the circle, and with A obtained in step 507 and x and x2 obtained in step 508, a+a+ (A X+ ) or a+- Execute the operation a-(X2-A), step 50
During the next semiconductor pellet recognition control returned from step 1 to before step 504, the coordinates (
a, b) are used to calculate the U-turn coordinates.

If such a correction is performed, the equation of the virtual circle will be corrected each time the outer peripheral edge of the wafer 18 is determined by the optical recognition means 25, and the equation of the virtual circle will be modified to approximate the actual disk shape of the wafer 18 and its actual placement position ( Therefore, compared to teaching, which is a one-time calculation of a virtual circle, this method has the effect of eliminating the need to leave good semiconductor pellets behind and reducing wasted work time for picking them up.

It goes without saying that the present invention can also be applied to an apparatus in which the wide surface of the XY child table wafer 18 is not parallel to the horizontal plane but is disposed in any direction, for example parallel to the vertical line.

[Brief explanation of drawings]

Figure 1 is a side view of the pickup device, Figure 2 is a plan view,
Figure 3 is a block diagram of the control device, Figure 4 is a plan view of the wafer on the XY table, Figure 5 is a flowchart, Figure 6 is an explanatory diagram of the equation of the virtual circle, and Figures 7 and 8 are the imaging screen. FIG. 9 is a sectional side view of the main part of the prior art, and FIG. 1O is a XX celebratory view of FIG. 9. 1.18...Wafer, 2.16...Wafer sheet,
3... Ring body, 4,19... Semiconductor pellet, 1
0...Placement table, 11...XY child table 22...
Push-up body, 25... Optical recognition means, 26... Control means, 27... Central processing unit, 36... Imaging screen.

Claims (1)

[Claims] (1) A wafer having a disk shape in a plan view having semiconductor pellets formed in a square pattern is temporarily attached to the surface of a wafer sheet, the wafer sheet is placed on an XY table, and the position of the semiconductor pellet is determined in a plan view. Recognize the shape etc. with optical recognition means,
The apparatus for picking up good semiconductor pellets among them with a suction collet includes a calculation means for calculating the equation of a virtual circle of the wafer from the detection result of the optical recognition means, and a calculation means that calculates the equation of the virtual circle of the wafer from the detection result of the optical recognition means, and a calculation means located at the outer periphery of the wafer based on the equation of the virtual circle. A pickup device for a semiconductor pellet, comprising: a control means for determining a positional relationship with the semiconductor pellet and driving the XY table in a predetermined direction.