JP3455102B2 - Semiconductor wafer chip separation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for slicing and separating functional elements such as a large number of semiconductor circuits formed on a semiconductor wafer into chips in the field of semiconductor manufacturing.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a large number of required semiconductor circuits are formed on a semiconductor wafer, a predetermined inspection is performed, and then each semiconductor circuit is cut into chips to form devices. . The step of cutting out a chip from a semiconductor wafer has conventionally been a scribing method in which a diamond-tipped blade is used to make a scratch on the surface of the semiconductor wafer and cleave along the scratch to separate the chip. Further, there is known a dicing method in which a thin diamond wheel rotated at a high speed is cut on the surface of a semiconductor wafer and the wheel is moved in the wheel surface direction to form a kerf so as to be divided into chips.

In the conventional mechanical scribing method, a semiconductor wafer is set on a stage by a separating method.
The pitch for processing each of the X axis and the Y axis is input to the control means of the apparatus, and the angle between the vertical or horizontal scribe line on the semiconductor wafer and the direction of the diamond tip blade or the diamond wheel is detected to detect the stage. After correcting the angle by rotating, the semiconductor wafer is provided with a large number of parallel flaws or grooves in the X-axis direction at intervals of the input X-direction pitch, and then in the direction of the Y-axis at right angles to the input Y-direction pitch. A large number of parallel flaws or grooves are formed on a semiconductor wafer, and finally each chip is separated to select a desired chip.

Further, a semiconductor chip separating device for irradiating a semiconductor wafer with laser light to cut a chip is disclosed in Japanese Patent Laid-Open No. 4-180649. As an analysis sample, an arbitrary chip is selected from a semiconductor wafer and separated by laser light irradiation. This method
The image taken by the CCD on the upper surface of the semiconductor wafer is displayed on the display, the partition coordinates of the specific chip to be sampled are specified on the graphic coordinates of the wafer displayed on the display, and the specified partition of the laser emission optical system is displayed. A laser beam is irradiated by the movement to perform heating cutting.

[0005]

These mechanical separation methods form scratches or kerfs by linearly moving a scribing blade or a diamond wheel, so that a flaw continuous from the edge of the wafer to the other edge is formed. Although it is suitable for forming and separating a groove or a groove, it is not possible to separate only a necessary chip at an appropriate portion inside the wafer.

Therefore, after forming a large number of required semiconductor circuits on a semiconductor wafer, the semiconductor circuits are inspected, and a good semiconductor circuit is selected and then separated by scribing, but conventionally, no chip is required. After separating all the chips regardless of the above, only the chips of the required semiconductor circuit were selected.

When two or more types of semiconductor circuits having different chip sizes are formed on a semiconductor wafer, if only one type of chip is cut out from one semiconductor wafer,
Other types of chips cannot be cut out, and in this case, other types of chips need to be cut out from other semiconductor wafers. In order to simultaneously cut out two or more types of semiconductor circuits from one semiconductor wafer, special arrangement of these semiconductor circuits is necessary, and such arrangement has not always been realized.

The chip sampling method using laser light described in the above-mentioned Japanese Patent Laid-Open No. 4-180649 is good for cutting out only specific chips, but it is necessary to mass-produce a large number of chips from a large number of semiconductor wafers. In order to separate only such chips, it took time to set the coordinates, resulting in low efficiency, which was not practical on a mass production scale.

Cutting by laser light has a low heating efficiency of the laser light to the substrate material for the wafer, and in particular, the absorption of the laser on the metal film is poor. Therefore, also in this respect, it is necessary to develop a technique for scribing at high speed. there were. In this regard, the inventor has previously formed a scribing groove for chip cutting on a semiconductor wafer, facilitates cutting or fusing of the scribing groove by irradiation of a laser beam during scribing, and chip cutting with a laser beam can be performed at high speed. Has proposed a technology for realizing the same (Japanese Patent Application No. 8-173960).

In view of the above problems, the present invention firstly provides a semiconductor wafer chip separation method which enables efficient coordinate setting for cutting out a large number of chips from a semiconductor wafer during scribing with a laser beam. The purpose is to do. Another object of the present invention is to further provide a chip separating method suitable for cutting a small number of chips from a semiconductor wafer. Another object of the present invention is to provide a chip separation method capable of separating and separating two or more types of semiconductor circuit chips having different shapes formed on the same semiconductor wafer by dividing each chip.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a desired chip is irradiated from a semiconductor wafer by irradiating a laser beam whose XY scanning is controlled by a scanning control means for numerically controlling the scanning position of the laser beam on the semiconductor wafer. However, the method is characterized by comprising the following steps: a) laser beam scanning control of the X-axis and Y-axis cutting pitch corresponding to the chip size on the semiconductor wafer. Inputting to the means to form a virtual scribe line on the coordinates, b) specifying the XY coordinates of the non-machined scribe line area to the scanning control means with respect to the virtual scribe line, c) the laser The beam scanning control unit sequentially scans the semiconductor wafer with the laser beam in the X-axis direction and the Y-axis direction at each designated pitch, and the designated unprocessed scan is performed. Except for the live line region, and the upper other scribe lines to form a laser beam irradiating the incision, to separate the chips, it is.

According to the chip separation method of the present invention, while the laser beam is scanned in the X and Y directions on the XY coordinates, the region of the scribe line region is irradiated with the laser beam to incise. By designating each pitch in the Y direction and assuming a scribe line, and then designating a region where laser irradiation is not performed, that is, the coordinates of the non-machining scribe line region, during the laser beam scanning, The laser irradiation is stopped, and the laser beam is irradiated on the scribe line other than this region to cut and separate the chip.

Each pitch corresponds to the length and width of the chip, and a region of the scribe line is selected for the region not irradiated with laser so that adjacent chips are not separated from each other. In this method, when a large number of chips are cut out, the coordinate designation of the area is small and the labor is small, and a large number of chips can be cut out quickly from the semiconductor wafer.

The laser beam scanning control means widely includes a mechanism for relatively controlling the position of the optical axis of the laser beam with respect to the upper surface of the semiconductor wafer on the stage, and a mechanism for controlling the movement of the stage while fixing the laser emission end. A mechanism for controlling the movement of the laser beam itself can be used. Therefore, as a supplement, a mechanism for deflecting the laser beam irradiation angle can also be used.

The method of the present invention comprises the steps of pitch input:
Enter as a block pitch that contains two or more chips,
The process includes forming block areas on the coordinates and then specifying a chip unit pitch within each block area.

In the method of the present invention, further, the non-machined scribe line area is designated by designating a wide area machining area including one or more chips, and the scribe line outside the wide area machining area is being scanned. The method includes defining a region not irradiated with a laser beam. When the designation of the wide area machining area is used, the area outside the wide area machining area is not irradiated, so that the non-machining scribe line area can be designated only within the wide area machining area. If the wide area processing area is limited to the chip forming area of the wafer, the area around the wafer where no chips are formed can be excluded from the irradiation, and the work efficiency can be improved. Further, the coordinate designation of this area is preferably used for cutting out a specific one or a small number of chips on the wafer, and the coordinate designation is simplified.

The semiconductor wafer chip separating method of the present invention further includes the following steps. d) Designating the coordinates of the two position detection marks on the semiconductor wafer in advance to the scanning control means, and e) The two position detection marks on the semiconductor wafer fixed on the stage by the position detection means. Detecting and obtaining the XY coordinates of the mark, f) Comparing the designated coordinates of the mark with the detected coordinates of the mark, and obtaining the rotation angle θ of the scanning coordinates of the laser beam with respect to the wafer coordinates, g) In the step c) of forming the incision by scanning the laser beam, the laser beam is simultaneously scanned in the X direction and the Y direction in the direction inclined by the rotation angle θ.

As a result, since the rotation angle θ can be coordinate-corrected during the scanning process of the laser beam, the optical axis of the laser beam becomes
Without deviating from the scribe line on the wafer,
Therefore, it is not necessary to rotate the wafer or the stage to adjust the rotation angle θ as in the prior art.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The chip separating method of the present invention is a scribe line between chips for separating functional elements such as a large number of integrated circuits and other electronic circuits formed on a wafer into chips for each element. Laser beam irradiation to
This is an automated method of scribing chips. This method numerically controls the scanning position of the optical axis of the laser beam on the wafer by the scanning control means and irradiates the semiconductor beam by irradiating the laser beam under XY scanning control. The desired chip is separated from the wafer.

The scribing method applicable to the method of the present invention includes a method of directly scanning and moving the laser beam on the upper surface of the fixed wafer, and a method of scanning and driving the wafer with the stage on the fixed laser beam. is there.
The former method of directly scanning the laser beam includes a method of moving the laser device by a scanning device (scanner) and a method of deflecting the laser beam from the laser device.

The present invention can be applied to any system, but in the following description, a system in which the laser beam is fixed and the wafer is scanned and driven together with the stage will be taken up. In the stage driving type scribing method, a stage is attached to an XY scanning device (scanner), a wafer placed on the stage is moved in the XY direction, and the other laser device is fixed above the stage. The laser beam emitted from the laser device is applied to the upper surface of the wafer to continuously form scribing holes in the moving wafer, and the chips are separated by the scribing holes.

The XY scanning device of the stage is controlled by the scanning control means, and the scanning control means is provided with a computer capable of numerical control, and the position of the XY scanning device is controlled by the input coordinate data. The scanning control means is provided with a display connected to a computer for displaying an image, particularly coordinates, and position detection means for detecting a wafer on the stage and displaying it on the display. A video camera is usually used as the position detecting means, and an image of the wafer is reproduced on a monitor. Particularly, as will be described later, detection of two position detection marks and an image of the incised scribe hole are performed. Is displayed on the display so that the coordinates of the scanning control means formed in advance can be displayed for comparison.

Embodiment 1. According to the semiconductor wafer chip separating method of the present invention, as shown in FIG.
The -Y coordinate is defined in the scan control means as the XY plane with the wafer upper surface. For example, the X axis is defined as the longitudinal direction of the chip to be cut out on the wafer, and the Y axis is defined as the orthogonal direction (the X axis and the Y axis may be opposite). The origin O of the XY coordinates is taken at the center of the wafer.

In the step a), the X-axis and Y-axis cutting pitches Px and Py corresponding to the chip size on the semiconductor wafer are used.
Is input to the scanning control means. Normally, the intervals in the long side direction of the chip 4 are input in the X-direction pitch Px, and the short side direction of the chip is input in the X-direction pitch Py. This pitch is
The spacing can be one chip. As a result, a large number of virtual scribe lines 2 that are orthogonal to each other on the coordinate
(21, 22) (virtual scribe line) is drawn,
The coordinates of the scribe line intersection are determined.

In the step b), the coordinates of the non-machined scribe line regions 21a and 22a are designated to the scanning control means with respect to the virtual scribe line 2 (21, 22) formed by the above input. The designation of coordinates does not designate a virtual scribe line to be processed, but designates an area of a virtual scribe line that is not processed. The region of the scribe line in the X-axis direction and the region of the scribe line in the Y-axis direction are designated as the scribe line region.
Normally, the coordinates 21 (x.y), 21
Specify (x.y). Next, the wafer 1 is placed on the stage at a predetermined position and temporarily fixed.

In the step c), the scanning control means designates the optical axis of the laser beam on the semiconductor wafer 1 in either the X or Y direction, for example, in the X axis direction (FIG. 2A). Sequential scanning at the specified pitch and then in the Y direction (see FIG.
(B)) Sequential scanning is performed at the designated pitch. Through this scanning process, the area 21a of the processing scribe line,
22a is not irradiated with the laser in the OFF state, but in the scribe line regions 21b and 22b which are not designated, the irradiation position 90 of the laser beam is kept in the ON state and the beam is irradiated to form an incision hole in the scribe line on the semiconductor wafer.

In this embodiment, in the scanning process of c), the optical axis of the laser beam is fixed and is substantially perpendicular to the upper surface of the wafer, and the scanning control means controls the position of the XY scanning device. , X-Y scanning device scans the semiconductor wafer in the X and Y directions.
Move in the direction.

When the first scan is performed in the X-axis direction, as shown in FIG. 2A, the optical axis 90 of the laser beam is used.
Is repeatedly moved in the X-axis direction on the wafer from the upper left starting end portion 91a outside the wafer 1 at a designated pitch from one end (one outer edge) in the Y direction to the other end (the other end) in the Y direction. It is repeatedly swept up to the outer edge), and a large number of parallel scribe lines in the designated X-axis direction are sequentially traced to reach the end portion 92a. When the next scan is performed in the Y-axis direction, the optical axis 90 of the laser beam is, in this example, as shown in FIG.
While repeatedly moving from 1b on the wafer in the Y-axis direction,
Repeatedly sweeps from one end (one outer edge) in the X direction through the center to the other end (the other outer edge) at the specified pitch, and sequentially follows a large number of parallel scribe lines in the specified Y-axis direction. The end portion 92b is reached.

When scanning in the X-axis direction, a large number of scribe lines 21 parallel to each other in the X-direction are irradiated with a laser beam except for the designated region 21a to form incisions, that is, scribe holes 31. When the next scan is performed in the Y-axis direction, scribe holes 32 are formed in a large number of parallel scribe lines 22 in the Y direction except for the designated region 22a, and thus, as shown in FIG. As shown in B), the scribe holes 31, which intersect in the XY direction,
The part surrounded by 32 is separated as the chip 4.

This embodiment further includes a method of correcting the deviation between the coordinate X-Y set by the scanning control means on the stage and the coordinate X'-Y 'on the wafer 1. For the coordinate correction, the following process is provided before the scanning process of c) above. A flow chart including a method for performing coordinate correction processing is shown in FIG. 4, and a correction method is shown in FIG.

In the step d), as shown in FIG. 2, the XY coordinates (X'-Y 'coordinate system of the wafer) of the two position detection marks Ma and Mb on the semiconductor wafer 1 are determined. The scanning control means is designated in advance. Two position detection marks Ma, Mb
For this, for example, an alignment mark printed in a specific chip is used. In the step e), the position detection means detects the position detection marks Ma ′ and Mb ′ (alignment marks) at two points on the semiconductor wafer 1 fixed on the stage, and the stage (X-Y of the stage) is detected.
The coordinates of the mark viewed from the coordinate system) are obtained and input to the scanning control means. A video camera is usually used as the position detecting means, and an image of the wafer is reproduced on a monitor,
The position detection mark of the point is compared with the coordinates of the scanning control means formed in advance on the monitor, that is, the coordinates of the stage, and is input to the scanning control means.

In the process of f), the designated coordinates Ma and Mb of the mark on the wafer and the detected coordinate M of the mark as seen from the stage.
By comparing a ′ and Mb ′, the displacements Δx and Δy in the X and Y directions of the wafer coordinates and the rotation angle θ with respect to the stage coordinates (which are also the scanning coordinates of the laser beam) are calculated. From these data, the virtual scribe line 21 is subjected to coordinate conversion into wafer coordinates viewed from the stage coordinates, and the equation of the virtual scribe line 21 ′ viewed from the converted stage coordinates (XY coordinates) is described. .

In the step g), in the step of forming the incision by scanning the laser beam in the step c), when the stage is scanned according to the virtual scribe line formula after conversion, the optical axis of the laser beam is actually measured. The scribe line can be traced on the wafer, and by a series of operations in the above step c), the unspecified scribe line area is appropriately opened by the laser beam irradiation without deviating from the scribe line, and the necessary chip 4 is obtained. To be

As a result, since the rotation angle θ of the wafer on the stage can be corrected during the scanning process of the laser beam, it is not necessary to rotate the wafer or the stage to adjust the rotation angle θ as in the conventional case.

FIG. 4 shows a flow chart as an example of this embodiment. In this step, the first stage is
First, the pitches in the X and Y directions are input to the scanning control means, then a virtual scribe line is formed, a non-processed scribe area is designated on the scribe lines in the X and Y directions, and the next position is set. Enter the coordinates of the detection mark.

In the next step, the wafer is placed and fixed on the stage, the position detecting mark on the upper surface of the wafer is detected by the detecting means, and the coordinates in the wafer coordinate system are input.
At this point of the coordinate correction, the coordinates of the scribe line equation as viewed from the stage coordinate system are determined.

In the next step, the optical axis of the laser beam is traced on the scribe line by scanning the stage in the X direction, and on the scribe line in the X direction other than the non-machined region,
The laser beam is turned on to make an incision. After scanning in the X direction, the same scanning in the Y direction and laser beam irradiation are performed to cut along the scribe line in the Y direction. Finally, the chips are separated.

Embodiment 2. In this embodiment, the step of pitch input of a) includes the step of inputting as a block pitch including two or more chips in between and forming a block area on the coordinates.

In the step a), the X-axis and Y-axis cutting pitches corresponding to the chip size on the semiconductor wafer are input to the scanning control means. In this process, a block pitch including two or more chips is input to form two or more block areas on the coordinates. Each block is designated to include an appropriate number of chips, and this designation is made by the block pitch in the X direction and the block pitch in the Y direction.

Further, in each block, the interval in the long side direction of each chip is the pitch in the X direction, and the short side direction of the chip is X direction.
It is input as the direction pitch. This pitch can be the spacing of one chip. As a result, a large number of virtual scribe lines that are orthogonal to each other are drawn on the coordinates, and the coordinates of the intersections of the scribe lines are determined.

In the step b), the coordinates of the non-machined scribe line area are designated to the scanning control means with respect to the virtual scribe line formed by the above input. To specify the scribe line area, first, the corresponding block is specified, and the X-axis direction scribe line area and the Y-axis direction scribe line area in the block are coordinate-input.

The formation of the block area is convenient for designating the non-processed scribe line area, and in particular, 100 pitches in the X direction (100 rows of Y direction scribe lines) and 200 pitches in the Y direction (200 rows) on the wafer. In the case of having a scribe line (X direction), the coordinates are counted in block units, so that the risk of mistakes when inputting coordinates can be effectively prevented. Similarly, it is easy to specify a chip with two position detection marks. The subsequent step c) is the same as in the first embodiment. It may be done in the same manner as.

Embodiment 3. In this embodiment, a method of designating coordinates of a wide area working region is introduced in the process of b) designating a non-working scribe line region. That is, the designation of the non-machined scribe line area is broadly designated as the surface area prior to the designation of the area on the line of the scribe line. By stipulating that the area outside the designated surface area is treated as a non-machined area, it is possible to save the troublesome coordinate designation when the non-machined area is large.

In this embodiment, in the step a), the X-axis and Y-axis cutting pitches corresponding to the chip size on the semiconductor wafer are input to the scanning control means. Inputs are made with the interval in the long side direction of the chip as the X-direction pitch and the short side direction of the chip as the X-direction pitch. This pitch is
The spacing can be one chip. As a result, a large number of virtual scribe lines that are orthogonal to each other are drawn on the coordinates, and the coordinates of the intersections of the scribe lines are determined.

In the step b), the coordinates of the non-machined scribe line area are designated to the scanning control means with respect to the virtual scribe line formed by the above input. In this embodiment, the designation is performed by designating one or more wide area processing regions 30 including one or more chips in the area of the closed circuit of the line segment formed between the designated coordinates. For example, as shown in FIG. 5, if this area is a rectangle on coordinates, the coordinates of the four corners 30a, 30b, 3
Specify 0c and 30d. However, the designation of the wide area processing area 30 is not limited to the rectangle. It may be a polygon having a step or a cross, and in this case, the coordinates of the corner 301 and the corner 302 of the contour line are designated.

The virtual scribe line outside the wide area processing area 30 is defined as not processed. On the other hand, it is convenient to define that the virtual scribe line inside it is all processed. When the line segment between the coordinates that specify the surface area coincides with the virtual scribe line, the handling of the scribe line can be defined as appropriate, but it is convenient to define that it is processed. In this case, all the scribe lines are incised inside the wide area processing area. Therefore, if there is an additional non-machined scribe line area in the wide area machined area, the area is designated again by coordinates.

This wide area processing area is effective when the unnecessary chip or the theoretical outside chip area in the peripheral portion of the semiconductor wafer is excluded. For example, when processing a smaller wafer, for example, a 2-inch wafer in an apparatus having a 4-inch wafer cutting capability, it is necessary to designate the entire outer area of the 2-inch wafer as a non-process scribe area.
In this embodiment, only the region in which the chips are substantially formed on the 2-inch wafer needs to be designated as the wide-area processed region, and it is possible to avoid the complexity of the designation of the non-processed scribe region in the outer region.

In addition, even if the unprocessed scribe region is large without cutting out the chips on the wafer, it is not necessary to specify the unprocessed scribe region again by designating the large processed region. A plurality of wide area processing areas may be designated on the coordinates. Only the designated wide area is irradiated with the laser beam and separated into chips. Further, the designation of the wide area working area is used for designation including a plurality of chips, and the designation of the wide area working area is also allowed for designation of a single chip.

In the step c), the scanning control means controls the XY scanning device to scan-drive the stage so that the optical axis of the laser beam on the semiconductor wafer is in either the X or Y direction, for example, The X-axis direction is sequentially scanned at a designated pitch, and then the Y direction is sequentially scanned at a designated pitch. Through this scanning process, when the optical axis of the laser beam is outside the wide processing area, the laser is not irradiated in the OFF state as the area of the non-processing scribe line.
When scanning inside the large machining area, the laser
A beam is irradiated in the N state to form an incision hole on the scribe line on the semiconductor wafer. However, the laser beam is not irradiated to the region where the region of the non-machined scribe line is designated inside the wide region, because the laser is in the OFF state. In this way, the inside of the wide processing area on the wafer is separated as chips by the portion surrounded by the scribe holes except the area of the non-processing scribe line, and the area outside this wide processing area is not processed on the wafer. It is left as it is.

Fourth Embodiment This Embodiment 4. Is 1
The method of the above embodiment is repeated twice or more for one semiconductor wafer. This is to separate the semiconductor wafer after the chips are separated by the method of the above-described embodiment from the other chips that remain unprocessed on the wafer by the method of the above-described embodiment.

In the first example, according to the first embodiment, one semiconductor wafer has two or more kinds of chips in which certain kinds of chips having different dimensions, that is, different pitches and other kinds of chips are arranged. The process for the case of including the chip will be described.

In the first separation work, in the pitch inputting process of a), the X-axis and Y-axis first cutting pitches corresponding to the first-type chip size are input to the scanning control means. Coordinates of intersections of virtual scribe lines are determined on all coordinates. In the process of b), with respect to the virtual scribe line formed by the above input, all the areas other than the array area of the chips of the first type are set as the non-processed scribe line area, and their coordinates are designated to the scanning control means. In the step c), the scanning control means causes the optical axis of the laser beam on the semiconductor wafer in the X direction and then in the Y direction, respectively.
The laser is turned off in the area of the non-processed scribe line during the scanning process by sequentially scanning at the cutting pitch of
In the region of the scribe line which is not designated, but is not designated, that is, in the arrangement region of the first type chips, the laser is
In the N state, beam irradiation is performed to separate the first type chips on the semiconductor wafer to form a wafer in which the second type chips are left.

In the second separation operation, in the pitch inputting process of a), the X-axis and Y-axis second cutting pitches corresponding to the second type of chip size are input to the scanning control means. In the process of b), with respect to the virtual scribe line, all areas other than the array area of the second type chips left on the wafer are set as the non-processed scribe line area, and similarly, the coordinates thereof are designated to the scanning control means. To do. In the process of c), the scanning control means sets the optical axis of the laser beam on the semiconductor wafer to, for example, X.
Sequential scanning is performed in the axial direction and then in the Y direction at the designated second cutting pitches. Through this scanning process, the laser beam is not emitted to the non-processed scribe line region in the OFF state, but the laser beam is turned on in the unspecified scribe line region, that is, the second type chip array region.
In this state, beam irradiation is performed to separate the second type chips of the semiconductor wafer from the wafer, and as a result, the two types of chips are separated. If a single wafer is formed with various types of chips having different pitches, the separating operation may be performed as many times as the number of the types.

In the following example, in accordance with the third embodiment described above, one semiconductor wafer is arranged with chips of a certain type and chips of another type having different sizes, that is, different pitches, and two types of chips are arranged. The steps performed for the case including a chip will be described.

In the first separation work, in the pitch input process of a), after inputting the first cutting pitches of the X-axis and the Y-axis corresponding to the chip size of the first type to the scanning control means,
In the process of b), the wide area is designated as the array region of the first type chips by the coordinates of the intersections of the virtual scribe lines, and in the process of c), the scanning control means controls the laser beam on the semiconductor wafer. The optical axis is sequentially scanned, for example, in the X direction and then in the Y direction at the above specified first cutting pitch, and the laser is not radiated in the OFF state outside the wide area through the scanning process. However, the laser is turned on inside the wide processing region to irradiate the beam to separate the first type chips and form a wafer in which the second type chips are left.

In the second separation work, the same procedure is followed.
In the pitch input process of a), after inputting the second cutting pitch of the X-axis and the Y-axis corresponding to the second type of chip size to the scanning control means, in the process of b), the intersection of the virtual scribe lines is changed. In the process of c), the scanning control means specifies the optical axis of the laser beam on the semiconductor wafer in the X direction, for example, by designating the wide area as the array region of the second type chips by the coordinates.
Then, in the Y direction, the respective second designated cutting pitches are sequentially scanned, and through this scanning process,
The laser is not irradiated in the OFF state outside the wide area processing area, but the laser is turned on inside the wide area processing area to irradiate the beam to separate the second kind of chips and the two kinds of chips are separated. . Such separation work is performed many times according to the types of chips similarly formed on the wafer and having different pitches.

Embodiment 5. In this embodiment, in the separation method described above, a groove, that is, a scribe groove is previously formed on a semiconductor wafer on a scribe line for separating the wafer into chips. As shown in FIG. 6 (A, B),
The scribe groove 20 is formed by removing the semiconductor layer 12 of the semiconductor wafer 1 to a narrow width by etching to form a groove and leaving the electrode metal layer on the back surface side of the semiconductor wafer as a groove bottom. When the semiconductor wafer is provided with the scribed grooves, when the laser beam is irradiated, the laser cutting speed can be increased by the absence of the semiconductor layer.

The present inventors filed another application (Japanese Patent Application No. 8-173).
No. 960), the electrode metal layer 11 forming the bottom of the scribe groove, for example, a layer of gold or its alloy, has a high laser beam reflectance and thus a low heating efficiency by a laser. As suggested in
Further, a metal coating 23 having a high laser beam absorption efficiency is formed on the bottom of the groove along the scribe groove. As such a metal film 23,
Ni can be used. More preferably, the electrode metal layer 11
It may be possible to further increase the cutting speed by the laser beam by forming a groove also on the back surface of the above and thinning the electrode metal layer 11 at the laser beam irradiation site.

By previously forming the scribe groove 20 on which the Ni film is formed as the metal film 23 on the scribe line on the upper surface of the semiconductor wafer, the processing speed and the cutting speed by the laser beam can be remarkably improved, and the chip separation work can be performed. Can be made more efficient.

Therefore, in the semiconductor wafer, a groove is formed in the semiconductor layer 12 along the scribe line to be cut between the circuit elements by etching, and then the Ni film 23 is formed on the bottom metal layer by the vapor deposition method or the like. To form the scribed groove 20, and thereafter, the above-mentioned Embodiment 1. Through 4. Any of the above chip separation methods is applied. Such a scribed groove 20 can be applied to all of the methods of the present invention.

[0061]

According to the chip separating method of the present invention, a desired beam is separated from the semiconductor wafer by irradiating a laser beam whose XY scanning is controlled by the scanning control means.
The cutting pitches of the X-axis and the Y-axis corresponding to the chip size are input, b) the coordinates of the non-processed scribe line area are designated, and the scanning control means of c) sets the laser beam optical axis on the semiconductor wafer as X or Y. By sequentially scanning at a specified pitch in the direction, a laser beam is irradiated on the scribe line except the specified non-machined scribe line area to form an incision hole and separate the chips, so a wide range of individual specifications can be specified. Large amount of chips quickly and efficiently without
Can be separated.

In the method of the present invention, in the above pitch input process, since the block pitch including two or more chips is input to form the block area on the coordinate, the coordinate of the subsequent non-machined scribe line area is formed. Can be specified easily, and the coordinates of two position detection marks can be easily specified and detected.

According to the method of the present invention, in the process of designating the non-machined scribe line area, by designating the coordinates of the wide area machining area, chip cutting in a specific range can be easily performed by scanning the laser beam. It is easy to distinguish and specify two or more types of chips having different pitches, and it is possible to quickly and efficiently separate a small number of various types of chips on a wafer. Since the wide area processing area can be specified so as to exclude unnecessary chips or areas outside the theoretical chip in the peripheral portion of the semiconductor wafer, it is possible to avoid the complicated specification of the non-processing scribe line area.

According to the method of the present invention, the designation of the wide area processing region can be designated on a chip-by-chip basis, and a plurality of chips can be designated. Therefore, it is extremely simple even when only one chip is sampled from the wafer. Can be The method of the present invention can be repeated twice or more for one wafer, which is effective for separating chips having different chip shapes.

The method of the present invention further performs coordinate conversion by designating the coordinates of the position detection marks at two points on the semiconductor wafer and detecting the marks on the actual wafer on the stage. In the step c) of forming the incision hole by scanning the laser beam, the X direction and the Y direction can be scanned in a direction inclined by the rotation angle θ, and fine adjustment of the angle of the wafer on the stage is not necessary.

A scribing groove for dividing each chip is formed in advance on the semiconductor wafer, and in particular, a metal film having a high absorption efficiency of the laser beam is formed on the bottom of the scribing groove. The scribing work by the laser beam can be speeded up, which is particularly effective for improving work efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a coordinate (A) showing a state in which a pitch is input on a coordinate and an unprocessed scribe region is designated on a virtual scribe line in a chip separating method according to an embodiment of the present invention, and a laser beam. The top view (B) of the irradiated and cut wafer.

FIG. 2 is a diagram showing a method of forming a scribe hole by scanning the optical axis of the laser beam and irradiating the laser beam on the wafer in the chip separating method according to the embodiment of the present invention, FIG. 3B is a diagram showing a scanning process in the X-direction, and FIG. 6B is a diagram showing a scanning process in the Y-direction.

FIG. 3 is a diagram showing coordinates for correcting the coordinates of the wafer viewed from the stage in the chip separating method according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a process of a chip separating method according to an embodiment of the present invention.

FIG. 5 is a top view of a wafer showing a wide-area processing area used for designating a non-processing scribe area according to an embodiment of the present invention.

FIG. 6 is a sectional view (A) and a partial top view (B) of a wafer used in the chip separation method according to the embodiment of the present invention.

[Explanation of symbols]

1 Semiconductor wafer 12 Semiconductor layer 11 Electrode metal layer 2 scribe lines 20 scribe groove 21a Unprocessed scribe area 3 scribe holes 30 Wide area processing area 4 chips

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaharu Moriyasu 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) References JP-A-57-50446 (JP, A) JP-A-59 -16344 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/301 B23K 26/00

Claims (10)

(57) [Claims] 1. A laser beam controlled by X-Y axis scanning by a scanning control means for numerically controlling a scanning position of a laser beam optical axis on a wafer chip to separate a desired chip from the semiconductor wafer. A method for separating a semiconductor wafer chip, comprising the following steps. a) inputting the X-axis and Y-axis cutout pitches corresponding to the chip size on the semiconductor wafer into the scanning control means, b) the imaginary scribe line formed by the above input, in the unprocessed scribe line region Designating coordinates to the scanning control means, c) The scanning control means sequentially scans the optical axis of the laser beam on the semiconductor wafer at a designated pitch in either the X or Y direction, and then designates the other direction. A chip is separated by irradiating a laser beam on the scribe line to form an incision hole on the scribe line while sequentially scanning at a specified pitch. 2. The step of inputting the pitch, the block pitch including two or more chips is input to form a block area on the coordinate, and then the chip unit pitch is input in each block area. The chip separation method according to claim 1, further comprising: 3. In the process of designating the non-machining scribe line area, coordinates of one or more wide area machining areas including one or more chips are designated, and the non-machining scribe line is formed in each of the wide area machining areas. The chip separation method according to claim 1, further comprising: designating an area, wherein an area outside the wide area processing area is set as a non-processing scribe line area. 4. The chip separating method according to claim 3, wherein the wide area processing area is designated so as to exclude unnecessary chips or areas outside the theoretical chip in the peripheral portion of the semiconductor wafer. 5. The chip separating method according to claim 3, wherein the designation of the wide area processing region is designation on a chip-by-chip basis. 6. The chip separation method according to claim 3, wherein the designation of the wide area processing region is designation including a plurality of chips. 7. A chip separating method for separating another chip by the method according to claim 1 from the semiconductor wafer after separating the chip by the method according to claim 1. 8. The chip separation method according to claim 1, further comprising the following steps. d) Designating the coordinates of two or more position detection marks on the semiconductor wafer to the movement control unit in advance, e) The above 2 on the semiconductor wafer fixed on the stage.
The position detecting means detects a position detecting mark having a number of points or more to obtain the XY coordinates of the mark. F) The coordinate data of the inputted marks are compared to detect the rotation angle θ of the coordinate axis with respect to the wafer. G) In the step c) of forming the incision hole by scanning the laser beam, the X direction and the Y direction are scanned in a direction inclined by the rotation angle θ. 9. The semiconductor wafer is preliminarily formed with a scribing groove for dividing each chip.
9. The chip separation method according to any one of 8 to 8. 10. The bottom of the scribing groove is
The chip separation method according to claim 9, wherein a metal film having a high absorption efficiency of the laser beam is formed by deposition.