JPS6362328A - Rear surface processing of semiconductor substrate - Google Patents

Abstract

PURPOSE:To prevent damage to a wafer by a method wherein a process to punch out a resin film with size larger than that of a semiconductor substrate while molten-removing the jutting out portion of the resin film using a heating wire as well as another process to peel off the resin film from semiconductor substrate using a bonding tape, are provided. CONSTITUTION:A resin film 5 is pressed down upon the surface of Si wafers 2 by an automatic push roller 18 at specified optimum pressure to punch out the Si wafers 2 along a circular guide larger than the Si wafers 2 continuously stuck on the tape of resin film 5. Later, the Si wafers 2 with a Ni-Cr wire heater 24 pressed down upon the edge of Si wafers 2 by spring 27 pressure are turned to cut off the jutting out resin film 5 from the Si wafers 2 cleanly along the edge of Si wafers 2 without fail. After pressing down a bonding tape 31 upon the resin film 5 by a pressure fixing roller 32, the bonding tape 31 can be wound up from the end thereof so that the resin film 5 may be peeled off from the wafers 2 due to the higher adhesion of bonding tape 31 than that of the resin film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for treating the back surface of a semiconductor substrate on which elements are formed.

Conventional Technology During the manufacturing process of semiconductor devices, before the assembly process, there is a backside treatment process to reduce the thickness of the silicon (Si) wafer in order to make the semiconductor element perform its electrical functions and make it easier to assemble. .

A conventional back surface treatment process will be explained with reference to the drawings shown in FIGS. 9 to 13.

FIG. 9 shows a Si wafer 2 that has undergone a diffusion process and has a large number of semiconductor elements 1 formed on its surface. The grid-like lines indicate scribe lines, and a semiconductor element 1 such as an IC or an LSI is formed in a region surrounded by the scribe lines.

First, a Si wafer 2 on which such elements are formed
A photoresist is applied to the surface of the Si wafer 2. Then, this Si wafer 2 is placed on a soft stage 4 covered with urethane rubber 3 with the element side facing upward. Next, a soft resin film 5 for surface protection is placed on top of the silicon wafer 2, and the resin film 5 is coated on the Si wafer 2 by manually pressing the roller 6 while being careful not to introduce air bubbles. figure).

Next, place the Si wafer 2 on the rubber plate 7, and cut out the portion of the resin film 5a protruding from the Si wafer 2 along the edge of the Si wafer 2 with the cutter 9 held in the hand 8 (Fig. 11). . Note that 2-F is a facet portion where the edge of the Si wafer 2 is a straight line.

Next, the Si wafer 2 is placed on the suction stage 10 of the back grinder with the front surface facing down, and is fixed by drawing a vacuum through the pores 11 of the suction stage 10. Then, the suction stage is moved to apply the Si wafer 2 to the grinding blade 12 rotating at high speed, and the back surface of the Si wafer 2 is ground (first
Figure 2).

Further, the Si wafer 2 is placed on a fixed stage 14 having a perforated plate 13 for vacuum suction on its surface, and the Si wafer 2 is fixed by drawing a vacuum. Then, the resin film 5 protecting the surface of the Si wafer 2 is peeled off using the bottle set 16 held in the hand 15 (FIG. 13).

Finally, remove the photoresist.

Through the above steps, the backside treatment process of the semiconductor substrate is completed.

Problems to be Solved by the Invention Conventional backside processing methods often rely on manual labor because Si wafers are extremely fragile and easily damaged. In particular, the work of cutting the resin film 5 shown in FIG. 11 along the outer shape of the Si wafer 2 is necessary because the Si wafer 2 is not a perfect circle but has a facet portion 2-F that is cut in a straight line. Mechanization was difficult. For this reason, the resin film 5 is cut with the cutter 9 held in the hand 8.
Careful cutting work was carried out along the edge of i-wafer 2. However, since this work is manual work that relies on delicate touch, there are inconveniences in that the cutter sometimes damages the periphery of the Si wafer and the resin film 5 is cut in a shape that protrudes beyond the outer shape of the Si wafer.

By the way, if the back side work is performed with the resin film 5 protruding from the Si wafer 2, the scraps of the resin film protruding from the Si wafer 2 will wrap around the grinding blade 11 and cause the S
The area around the i-wafer was frequently damaged.

In addition, since the process of attaching the resin film 5 shown in FIG. 10 to the surface of the Si wafer 2 is done manually, the pressing force of the roller 6 varies, and the Si wafer 2 may be damaged during handling. .

Furthermore, the work of peeling off the surface protection resin film 5 from the surface of the Si wafer 2 using the bottle set 16 shown in FIG. 13 had a high risk of damaging the important semiconductor element surface with the bottle set.

Means for Solving the Problems The method for backside processing of a semiconductor device of the present invention includes the steps of bringing a tape-shaped resin film into close contact with the surface of a semiconductor substrate while pressing it with an automatic pressure roller, and applying pressure along the edge of the semiconductor substrate. a step of cutting out a resin film thicker than the semiconductor substrate; and a step of bringing a heating wire into contact with the edge of the semiconductor substrate and fusing and removing the resin film protruding from the semiconductor substrate while rotating the semiconductor substrate. , a step of fixing the front side of the semiconductor substrate to a stage and grinding the back side with a grinding blade, and pressing an adhesive tape onto the resin film on the semiconductor substrate with a roller, and then separating the adhesive tape from the semiconductor substrate. and peeling off the resin film from the semiconductor substrate.

Function: Since the resin film that protects the element surface of the Si wafer according to the present invention is pressed onto the Si wafer surface with an optimal constant pressure using an automatic pressing roller, variations and unevenness in the adhesion of the resin film can be reduced.

Next, after cutting out the Si wafer continuously pasted on the resin film tape along a circular guide that is thicker than Si wafer 2 so as not to damage it, a nichrome wire heater is applied with spring pressure to the edge of the Si wafer. By rotating the Si wafer while being pressed against the edge, the resin film protruding from the Si wafer can be neatly and reliably cut off along the edge of the Si wafer.

Furthermore, after pressing the adhesive tape onto the resin film with a pressure roller, and then winding up the adhesive tape from the edge, the resin film cannot be peeled off from the Si wafer because the adhesive strength of the adhesive tape is stronger. can.

Embodiment An embodiment of the method for processing the back surface of a semiconductor substrate according to the present invention will be described with reference to process diagrams shown in FIGS. 1 to 8.

A Si wafer 2 whose surface is coated with photoresist is placed on a conveyor belt 17 and fed in the direction of the arrow in the figure, a tape-shaped resin film 5 is placed over it and pressed by an automatic pressing roller 18.

Then, since the Si wafer 2 has been coated with a photoresist for surface protection in advance and the resin film 5 is soft, it comes into close contact with the surface of the Si wafer 2 (FIG. 1).

Next, the resin film is mechanically cut out using a burr cutter 19 to a size larger than the Si wafer 2 so as not to damage the Si wafer 2. The details are shown in FIG.

After the Si wafer 2 is fixed by the vacuum suction tube 20, the cutter 21 is rotated around the groove of the circular guide 22 to cut out the resin film 5 covering the Si wafer 2 in a circular shape. This state is shown in FIG. Resin film 5 is better than Si wafer 2! It is cut out in a large size.

Next, the Si wafer 2 in the state shown in FIG. 3 is fixed to a vacuum suction head and slowly rotated by a drive belt 23. Then, the nichrome wire heater 24 is applied to the edge of the Si wafer 2 to melt the resin film in contact with it, and the resin film 5 is cut out along the edge of the Si wafer (FIG. 4). Note that current flows through the nichrome wire heater 24 through a roller electrode 25, and the nichrome wire generates heat. Also, since the facet portion 2-F of the Si wafer 2 has a different shape than the other edges, the pivot 26 is used as a fulcrum so that the nichrome wire heater 24 always hits the edge of the Si wafer 2 at a certain pressure. It is pressed by spring 27. This pressure can be adjusted using the adjustment screw 28. Furthermore, the fifth
The figure shows an enlarged view of how the nichrome wire heater 24 is applied to the edge of the Si wafer 2 and the edge 5a of the resin film is cut off as the Si wafer 2 rotates. A current flows through the nichrome wire heater 24, generating heat, and the spring 27 described above constantly presses the edge of the Si wafer 2. For this reason, facet part 2
The resin film 5a protruding from -F is also reliably cut off by fusing.

Note that the role of the nichrome wire 29 is as the nichrome wire heater 24.
The purpose is to support the cut ends of the resin film so that they do not get stuck. Therefore, in this part,
No current passes through it. Further, the nichrome wires 24 and 28 are wound on spools, and are slowly fed out while being wound up little by little onto another spool.

After cutting off the resin film protruding from the Si wafer 2 in this way, the back surface of the Si wafer 2 is ground.

A method for grinding the back surface of the Si wafer 2 is shown in FIG.

It is placed on the suction stage 10 of a back grinder with the surface on which the semiconductor element 1 is formed facing downward.

The surface of the adsorption stage 10 is provided with a large number of pores 11 for vacuum adsorption of the Si wafer 2. If the surface of the semiconductor element 1 comes into direct contact with the suction stage 10, it will be damaged, so in order to protect the surface of the Si wafer 2, photoresist is applied and then covered with a thin and soft resin film 5. In this state, the Si wafer 2 is fixed by vacuum suction on the suction stage 10 of the back grinder, and the suction stage 10 is moved in the direction of the arrow while the grinding blade 12 embedded with diamond powder is rotated at high speed to remove the Si wafer. When applied to the back surface of the Si wafer 2, the surface of the Si wafer 2 is ground to a predetermined thickness along the grinding surface shown by the dotted line (in addition, the grinding is performed by reciprocating the suction stage 1o against the grinding blade 12 several times). conduct.

Next, the resin film 5 covering and protecting the surface of the Si wafer 20 is stripped off using a surface protection film automatic stripping device. The situation is shown in FIG. 7, and an enlarged view is shown in FIG. 8.

A Si wafer 2 with a resin film pasted on its surface is transported by a conveyor belt 30. On the other hand, the adhesive tape 31 is pressed against the resin film covering the surface of the Si wafer 2 at the pressure roller 32. The pressure is adjustable.

Both the pressure roller 32 and the lower roller 33 are made of Si.
It has the function of transporting the wafer 2 in the direction of the arrow in the drawing.

When the adhesive tape 3 is fed out by the pressure roller 32,
1 is pulled upward at a steep angle. At this time, the surface protection resin film is peeled off from the end so that it adheres to the adhesive tape 31 (in addition, 34 indicates the peeled off resin film).

Finally, the photoresist on the Si wafer 2 is removed.

Through the above steps, the back surface treatment process of the semiconductor substrate is completed.

Effects of the Invention In the present invention, first, a surface protection resin film is automatically and continuously attached to a Si wafer using an automatic roller with an optimum pressure, so that the Si wafer is not damaged.

Next, the S
The i-wafer is hollowed out to a size thicker than its external size together with a surface protection resin film, and then Si
Since the protruding resin film is cut along the outer periphery of the wafer using a nichrome wire heater, it can be accurately cut along the edge of the Si wafer without damaging the periphery of the Si wafer.

Furthermore, by pressing the adhesive tape against the resin film that protects the surface of the Si wafer with a roller and winding it up, it can be easily peeled off without touching the Si wafer directly, eliminating the possibility of damaging the Si wafer. .

In addition to the above effects, there is also the effect of reducing time loss due to automation.

[Brief explanation of the drawing]

Figures 1 to 8 are process diagrams according to the present invention, and Figure 1 is a perspective view of an apparatus that automatically and continuously coats the surface of a Si wafer with a protective resin film using a roller. Figure 2 is an enlarged view of a so-called bri-cutter that cuts out a tape-shaped resin film covering a Si wafer to be slightly larger than the Si wafer, and Figure 3 shows the Si wafer cut out by the bri-cutter device and its surface covered. A perspective view showing the resin film, Fig. 4 is a schematic diagram of a device for cutting off the resin film protruding from the Si wafer along the edge of the Si wafer, Fig. 5 is an enlarged view of a part of it, and Fig. 6 is the back side. Figure 7 is a cross-sectional view of the grinding machine, Figure 7 is a perspective view of a device that uses adhesive tape and rollers to peel off the resin film attached to the surface of a Si wafer, Figure 8 is an enlarged view of a part of it, Figure 9
The drawings from Fig. 13 to Fig. 13 are related to the conventional method, and Fig. 9 is a schematic diagram showing a large number of semiconductor elements formed on a Si wafer, and Fig. 10 is a schematic diagram showing a protective layer on the surface of the Si wafer. Fig. 11 is a perspective view showing a manual method of pasting a resin film along the outer shape of Si wafer 1, Fig. 12 is a perspective view of a method of manually pasting a resin film onto the Si wafer. The sectional view and FIG. 13 are perspective views showing a method of peeling off the resin film covering the surface of the Si wafer using a bin set. 1... Semiconductor element, 2... Si wafer, 2-F... Facet, 3... Urethane rubber, 4... Stage, 5...
Resin film, 5a...Resin film protruding from the Si wafer, 6...Roller, 7...
...Rubber plate, 8,15...Hand, 9...
・Cutter, 10...Adsorption stage, 11...
... Pore, 12 ... Grinding blade, 13 ...
... Adsorption porous plate, 14 ... Fixed stage, 16
... Bin set, 17 ... Conveyor belt, 18 ... Press roller, 19 ... Bri cutter, 20 ... Vacuum suction tube ,2
1... Cutter, 22... Circular guide, 23... Drive belt, 24... Nichrome wire heater, 25... Roller electrode, 26
...Pivot, 27...Sbring,
28... Adjustment screw, 29... Nichrome wire, 30... Conveyor belt, 31... Adhesive tape, 32... Pressure roller, 33...
... Lower roller, 34 ... Peeled off resin film. Name of agent: Patent attorney Toshio Nakao
figure
November 4th Figure 3 Figure 5 Figure 7 Figure 9 Figure 2 St Heno\-

Claims (1)

[Claims] A step of bringing a tape-shaped resin film into close contact with the surface of a semiconductor substrate while pressing it with an automatic pressure roller, a step of cutting out the resin film larger than the semiconductor substrate along an edge of the semiconductor substrate, and an edge of the semiconductor substrate. A heating wire is brought into contact with the semiconductor substrate and the resin film protruding from the semiconductor substrate is melted and removed while the semiconductor substrate is rotated.The front side of the semiconductor substrate is fixed to a stage and the back side is ground with a grinding blade. and a step of pressing an adhesive tape against the resin film on the semiconductor substrate with a roller, and then separating the adhesive tape from the semiconductor substrate to peel off the resin film from the semiconductor substrate. A method for processing the back side of a semiconductor substrate.