JPH05198671A - Dicing method of semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide a dicing method which eliminates the need for a frame for holding a sheet attached to a wafer during dicing of a full cut method or a semi-full cut method. CONSTITUTION:A wafer 4 to be processed is finished to a thickness of 400 to 500mum by rear grinding. A polyvinyl chloride or polyethylene sheet 5 is attached to the rear of the wafer 4. The configuration of the sheet is practically the same as that of the rear of the wafer 4. A cutting groove is not formed in a peripheral edge part of the wafer 4 (e.g. in a range of 2cm from an outer periphery) and a cutting groove is formed between elements by a full cut method similar to a conventional one only in a region in the inside thereof (in a range of about 8cm from the center). A depth of the cutting groove is shown by a broken line 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dicing method which is one of the steps for taking individual semiconductor elements from a semiconductor wafer.

[0002]

2. Description of the Related Art A so-called dicing process is one of the processes for individually taking out a large number of semiconductor elements formed on a semiconductor wafer (hereinafter abbreviated as a wafer).

FIG. 6 is a plan view for explaining a typical conventional dicing process, and FIG. 7 is a sectional view taken along the line XY in FIG. Metal frame 1 as shown in both figures
The synthetic resin sheet 2 is attached to the (outer frame), and the wafer 3 to be processed is attached to one surface of the sheet 2. In this state, a cutting groove having a predetermined depth is formed between the semiconductor elements on the wafer by a blade (cutting blade) that rotates at high speed.

At this time, the depth of the cutting groove is equal to that of the wafer 3.
There is a method called a so-called full-cut method in which the thickness is larger than the thickness of the wafer 2 to cut into the sheet 2, and a method called a semi-full-cut method in which the depth of the cutting groove is slightly smaller than the thickness of the wafer 3.

In the case of the full-cut method, the wafer is divided into individual semiconductor elements at the time when dicing is completed, so that a sheet is required to support the semiconductor elements. Even in the semi-full-cut method, the wafer after dicing is extremely fragile, so that it is necessary to support the sheet 2.
And the frame 1 was used for holding the sheet.

[0006]

In recent years, the diameter of wafers has increased, and some wafers having a diameter of about 20 cm have appeared. If the above-described tiling method is applied to a wafer having such a large diameter, the size of the frame may reach about 40 cm on a side, and the weight may be increased. Therefore, the size of the dicing device that processes the dicing device is increased, and it is becoming difficult to manually handle and transport the dicing device. This problem will become more and more serious with the future increase in the diameter of wafers. In order to solve such a problem, it is an object of the present invention to provide a dicing method that does not require a frame for holding a sheet.

[0007]

To achieve the above object, the dicing method of the present invention comprises a step of attaching a sheet having substantially the same shape as the back surface to the back surface of the wafer, and a constant distance from the outer periphery of the wafer. Forming a dicing groove having a depth of at least a half or more of the thickness of the wafer from the surface of the wafer except for a region within the distance.

The present invention also includes the step of removing a portion having a constant thickness from the back surface to the front surface except for the area within a certain distance from the outer periphery of the semiconductor wafer, and the area from which the certain thickness has been removed. Characterized by comprising a step of pasting a sheet on the entire back surface or forming a resin layer, and a step of forming a dicing groove having a depth of half or more of the thickness left in the removed region of the constant thickness There is.

[0009]

According to the above-mentioned dicing method, the region (peripheral portion) within a certain distance from the outer periphery of the wafer to be processed is not cut, or even if it is cut, the groove is relatively shallow, so that the wafer mechanical The strength is maintained, and this part plays the role of a conventional outer frame. That is, even if the wafer is completely or almost completely cut in the region inside the peripheral portion, it is held by the back surface sheet, and the sheet is held by the peripheral portion of the wafer. Therefore, the frame for holding the sheet, which has been necessary in the past, becomes unnecessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1B is a sectional view showing the dicing method according to this embodiment.

A wafer 4 (for example, a silicon wafer) having a diameter of about 20 cm has the necessary elements formed on its surface and wiring has been completed.
Finished to 500 μm. A sheet 5 made of polyvinyl chloride or polyethylene is attached to the back surface of the wafer 4 to be processed. This sheet has substantially the same shape as the back surface of the wafer 4 to be processed. The sheet 5 may have a shape substantially the same as the back surface shape of the wafer 4 to be processed in advance, or may be a sheet larger than the wafer 4 to be processed and then the back surface shape of the wafer 4 to be processed. You may cut it according to. Also,
The sheet 5 has a thickness of, for example, 60 to 100 μm.

The wafer 4 to be processed is cut by using a dicing saw, but no cutting groove is formed in the peripheral portion (for example, a range of 2 cm from the outer periphery) of the wafer 4 to be processed, and an inner region (center) is formed. The cutting groove between the elements is formed by the full-cut method similar to the conventional method only in the range of from about 8 cm). The depth of the cutting groove in this case is as shown by the broken line 6 in FIG. In order to change the depth of the cutting groove in the wafer as described above, the height of the blade of the dicing device is set as shown in FIG.
Control is performed as shown by the blade height locus 7 in (b).

No cutting groove is formed at the peripheral portion of the wafer 4 to be processed, and a cutting groove reaching the sheet 5 is formed only in an area inside the wafer 4, and the semiconductor element is completely cut and divided in this area. ..

FIG. 3 is a perspective view of the wafer 4 and the sheet 5 to be processed which have been subjected to the dicing according to the method of the above embodiment.
Cutting grooves 9 are formed between the semiconductor elements in a region inside the peripheral edge of the wafer 4 to be processed.

According to this embodiment, in the area inside the peripheral edge of the wafer to be processed, that is, in the range of a certain distance from the center of the wafer to be processed (area in which a semiconductor element satisfying the product standard can be formed), Similar to the full-cut method, the cutting groove is formed and the semiconductor element is completely divided, so that the die-bonding step can be performed by the same die pickup as in the conventional case. On the other hand, no cutting groove is formed in the peripheral portion of the wafer to be processed, and mechanical strength is maintained.
Therefore, the sheet on the back surface of the wafer to be processed is held by this portion, and the conventional metal frame becomes unnecessary.

FIG. 2 is a sectional view showing a second embodiment of the present invention. Similar to the first embodiment, the wafer 4 (for example, a silicon wafer) having a diameter of about 20 cm has the necessary elements formed on its surface and wiring is completed, and its back surface is ground to a thickness of 400 to 500 μm. There is.
A sheet 5 made of polyvinyl chloride or polyethylene is attached to the back surface of the wafer 4 to be processed. This sheet has substantially the same shape as the back surface of the wafer 4 to be processed. The sheet 5 is the wafer 4 to be processed in advance.
A sheet having a shape substantially the same as the back surface shape may be attached, or a sheet larger than the wafer 4 to be processed may be attached and then cut according to the back surface shape of the wafer 4 to be processed. The thickness of the sheet 5 is, for example,
It is 60 to 100 μm.

The wafer 4 to be processed is cut by using a dicing saw, but no cutting groove is formed in the peripheral portion (for example, a range of 2 cm from the outer circumference) of the wafer 4 to be processed, and an area inside the wafer (center) is formed. The cutting groove between the semiconductor elements is formed by the semi-full-cut method similar to the conventional method only in the range of from about 8 cm). The depth of the cutting groove in this case is as shown by the broken line 8 in FIG. In this way, the depth of the cutting groove in the wafer is changed by controlling the height of the blade of the dicing device in the same manner as the blade height locus 7 shown in FIG.

The depth of the cutting groove needs to be at least a half or more of the thickness of the wafer to be processed, and preferably the cutting is performed to a depth of at least two thirds of the thickness of the wafer to be processed. In this embodiment, cutting grooves are formed from the back surface of the wafer 4 to be processed, leaving a thickness of several tens of μm. Even when the dicing according to this embodiment is performed, the perspective view of the wafer to be processed is as shown in FIG.

Also in this embodiment, in the region inside the peripheral edge of the wafer 4 to be processed, that is, in the range of a certain distance from the center of the wafer 4 to be processed (the region where a semiconductor element satisfying the product standard can be formed), it is conventional. Similar to the semi-full-cut method, the cutting groove is formed and the semiconductor element is connected only at a part of several tens of μm near the back surface of the wafer, so it can be easily split (break) at the same time as the conventional die pickup, and the die bond It can be connected to the process. on the other hand,
No cutting groove is formed in the peripheral portion of the wafer to be processed, and mechanical strength is maintained. Therefore, the sheet 5 on the back surface of the wafer to be processed is held by this portion, and the conventional metal frame becomes unnecessary.

In the above two examples, no cutting groove was formed at the peripheral edge of the wafer to be processed.
There is no problem even if the cutting groove is formed in the peripheral portion as long as the mechanical strength of the peripheral portion is maintained.

Next, a third embodiment of the present invention will be described. FIG. 4 is a sectional view of a wafer to be processed when dicing is performed according to the third embodiment. The processed wafer 14 has completed the formation of the necessary elements on its surface, and its thickness is first finished to 400 to 500 μm by backside grinding. Furthermore, in the region at a fixed distance from the center, the wafer 14 is about 1
Etching or grinding is performed from the back surface so as to leave a thickness of 00 to 200 μm. Then, a sheet 15 made of polyvinyl chloride or polyethylene is attached to the entire back surface of the wafer including the relatively thick region at the peripheral portion. The thickness of the sheet is 60 to 100 μm. The sheet 15 may be a sheet obtained by spin-coating a low-viscosity resin on the back surface of a wafer and curing it.

Next, a cutting groove is formed with a dicing saw. In the case of the present embodiment, a depth sufficient to fully cut a relatively thin portion of the wafer (shown by a broken line 16 in FIG. 4). ), A cutting groove is formed on the entire wafer. Therefore,
It is not necessary to control the height of the blade for changing the depth of the cutting groove between the peripheral portion of the wafer to be processed 14 and the region inside thereof.

According to this embodiment, in a region inside the peripheral edge of the wafer to be processed 14, that is, within a certain distance from the center of the wafer to be processed (a region in which a semiconductor element satisfying the product standard can be formed). As in the conventional full-cut method, the cutting groove is formed and the semiconductor element is completely divided, so that the die-bonding step can be performed by the same die pickup as in the conventional method. On the other hand, processed wafer 1
Although a cutting groove is also formed in the peripheral portion of No. 4, a sufficient thickness is left in the peripheral portion, so that the mechanical strength is maintained. Therefore, the sheet on the back surface of the wafer to be processed is held by this portion, and the conventional metal frame becomes unnecessary.

FIG. 5 is a sectional view for explaining the fourth embodiment of the present invention. The processed wafer 24 has completed the formation of the necessary elements on its surface, is finished to a thickness of 400 to 500 μm by backside grinding, and is approximately 100 to 300 μm from the surface in a region at a constant distance from the center.
Etching or grinding is performed from the back surface so as to leave a thickness of m. Then, a sheet 25 made of polyvinyl chloride or polyethylene is attached to the entire back surface of the wafer including the relatively thick region at the peripheral portion. The thickness of the sheet is 60 to 100 μm. The sheet 25 may be formed by spin-coating a low-viscosity resin on the back surface of the wafer and curing the resin.

Next, a cutting groove is formed with a dicing saw. At this time, the depth of the cutting groove is preferably at least half the thickness of the relatively thin portion of the wafer to be processed. In the case of the present embodiment, a cutting groove is formed over the entire wafer to be processed at a depth (shown by a broken line 26 in FIG. 5) in which a relatively thin portion of the wafer to be processed is semi-full cut leaving several tens of μm. .. Therefore, it is not necessary to control the height of the blade for changing the depth of the cutting groove between the peripheral portion of the wafer to be processed 24 and the region inside thereof.

Also in this embodiment, in the region inside the peripheral edge of the wafer 24 to be processed, that is, in the range of a certain distance from the center of the wafer 24 to be processed (the region where a semiconductor element satisfying the product standard can be formed), it is conventional. Similar to the semi-full-cut method, the cutting groove is formed and the semiconductor element is connected only at a part of several tens of μm near the back surface of the wafer, so it can be easily split (break) at the same time as the conventional die pickup, and the die bond It can be connected to the process.
On the other hand, a cutting groove is also formed in the peripheral portion of the wafer to be processed, but a sufficient thickness is left in the peripheral portion, so that mechanical strength is maintained. Therefore, the sheet 25 on the back surface of the wafer 24 to be processed is held by this portion, and the conventional metal frame becomes unnecessary.

In any of the above-mentioned embodiments, effective dicing is not performed at the peripheral portion of the wafer to be processed, and the semiconductor elements cannot be divided and sampled. In the first place, however, semiconductor elements satisfying the product standard are satisfied. Is almost never formed, the loss in each of the above-mentioned embodiments is negligible.

Although the dicing method using the dicing saw is adopted in the above-mentioned embodiments, the present invention is not limited to this, and can be applied to the case of dividing between semiconductor elements by other dicing means, for example, scribing by laser, The same effect can be obtained.

[0029]

According to the method for dicing a semiconductor wafer of the present invention, when the wafer is supported by the backside sheet for dicing, an outer frame for holding the sheet is not required, which is suitable for processing a large diameter wafer. A suitable dicing method can be realized. In addition, the step of attaching or peeling the sheet to the frame is not necessary, and the overall process and cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a dicing method of the present invention.

FIG. 2 is a sectional view showing a dicing method of the present invention.

FIG. 3 is a perspective view showing a dicing method of the present invention.

FIG. 4 is a sectional view showing a dicing method of the present invention.

FIG. 5 is a sectional view showing a dicing method of the present invention.

FIG. 6 is a plan view showing a conventional dicing method.

FIG. 7 is a sectional view showing a conventional dicing method.

[Explanation of symbols]

 4 Processed Wafer 5 Sheet 6 Broken Line Denoting Cutting Groove Depth 7 Blade Height Locus 8 Broken Line Denoting Cutting Groove Depth 9 Cutting Groove 14 Processed Wafer 15 Sheet 24 Processed Wafer 25 Sheet

Claims (2)

[Claims] 1. A step of attaching a sheet having substantially the same shape as the back surface to the back surface of the semiconductor wafer, and at least the front surface of the semiconductor wafer except a region within a certain distance from the outer periphery of the semiconductor wafer. And a step of forming a dicing groove having a depth not less than half the thickness of the semiconductor wafer. 2. A step of removing a portion having a constant thickness from the back surface to the front surface except for an area within a constant distance from the outer periphery of the semiconductor wafer, and the entire back surface including the area where the constant thickness is removed. A method for dicing a semiconductor wafer, comprising: a step of attaching a sheet or forming a resin layer; and a step of forming a dicing groove having a depth of half or more of the thickness left in the removed region having the constant thickness.