JPS62204541A - Method and apparatus for dividing wafer - Google Patents

Abstract

PURPOSE:To divide a wafer in high reliability without displacement of the moving position of other wafer by irradiation of predetermined light on a tape through a mask formed on a light screening pattern of predetermined shape. CONSTITUTION:A transparent plastic tape 9 which reduces its bonding strength by irradiation of ultraviolet rays is bonded on a frame 8, and its adhesive surface is coated with a wafer 2 in which an element forming surface is disposed upside. After a dicing is completed, the frame 8 is fed to an irradiation unit 5. The unit 5 has 2-stage XY tables 14, 15 and an ultraviolet irradiation lamp 16, and a mask 17 formed with a light screening pattern 19 of a predetermined shape is placed on the table 14. After the mask 17 and the wafer 2 are completely positioned, only the position corresponding to the back surface of a pellet 10 of the wafer 2 is irradiated by means of the lamp 16, fed to a pickup unit 7 in the state that the bonding strength is reduced, and the pellet 10 protruded by a pin 21 is held by means of a collet 22 by vacuum suction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique that is effective for use in dividing semiconductor wafers in the manufacture of semiconductor devices.

[Conventional technology]

For information on how to divide half-unit wafers, see, for example, "IC Mounting Technology" (edited by the Japan Microelectronics Association), published by Kogyo Kenkyukai Co., Ltd., January 15, 1980, P1.
00 to P101. Here, a technology is introduced in which a wafer is divided on a plastic adhesive sheet, the sheet is stretched, and then the pellet portion is pushed up from the back side of the sheet using a push-up tool, and then adsorbed from above with a collet.

The present inventor studied wafer dividing technology. The following are the techniques studied by the present inventor, and the outline thereof is as follows.

As circuits become more highly integrated and the patterns on pellets become finer, alignment of the mask and wafer becomes more difficult.
Since it becomes difficult to achieve accurate positioning accuracy with only alignment at the wafer level, so-called chimp alignment, in which alignment is performed in units of pellets, becomes necessary. It is known to form seven alignment marks for this chimbu alignment in the remaining area adjacent to the pellet on the wafer.

On the other hand, at the prototyping stage or when starting mass production of semiconductor devices, a large number of test elements having the same structure as the element part formed on the pellet are formed outside the pellet area, and these test elements are inspected. It is conceivable to indirectly inspect the formation state of the element portion.

As mentioned above, in order to form alignment marks and test elements, TEG (Test
It is known to provide an element group section. Specifically, for example, in a pellet on which a memory element having a capacity of about 1 megabyte is formed, if the pellet area is about 5 cm in length and 2 ions in width, the TEG part should be adjacent to the short side of the pellet. Width 1
．． A TEG area of about 5 dragons is required.

By the way, when dividing the above wafer into pellets,
It is conceivable that the wafer be divided into pellets by cutting at the center position in the width direction of the TEG portion.

However, in the above method, the picked up pellet has a TEG portion with a width of about 0.75 cm. The addition of this TEG section not only makes the pellet unnecessarily large during mounting, but also requires a long wire loop to jump the unnecessary TEG section when wire bonding is performed. ,
Therefore, there is a possibility that the wire is likely to short-circuit with the pellet.

From the above points, it is conceivable to perform so-called two-stage cutting in which both ends of the TEG portion are cut when cutting the wafer, and pick up only the pellet portion.

[Problem that the invention seeks to solve]

However, in the case of the above technology, when picking up the pellet part by vacuum suction with a collet or the like, when pushing up the pellet with the pick-up push-up pin for peeling the pellet from the tape, the adjacent TE
The inventor of the present invention has revealed that there is a risk that the G part may float or move together with the adsorbed pellets, damaging the surfaces of other pellets.

Furthermore, in the above technology, since the adhesive force is almost equal over the entire surface of the tape, when picking up pellets at a predetermined location, the pellets and the adhesive tape cannot be easily separated, resulting in deformation of the tape. , the entire wafer may be misaligned on the tape, making it difficult to pick it up at an accurate position.

The present invention has been made focusing on the above problems,
The purpose is to perform reliable wafer division.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

A brief overview of the representative inventions disclosed in this application is as follows.

That is, a wafer is adhered to the adhesive surface of a translucent tape whose adhesive strength decreases when irradiated with a predetermined light, and a mask on which a light-shielding pattern of a predetermined shape is formed is aligned on the back side of the adhesive surface of the tape. After irradiating the tape with a predetermined light through this mask, the pellets at a predetermined portion on the back surface of the wafer are pick-amplified.

[Effect]

According to the above-mentioned means, depending on the pattern formation of the mask,
Since it is possible to reduce the adhesive force only at any part of the back surface of the wafer, when performing pink-up, it is possible to maintain a strong adhesive force in the area where pink-up is not performed. Therefore, it is possible to prevent the portion of the wafer that is not subjected to pick-amplification from moving, prevent damage to the wafer due to movement, prevent the entire wafer from shifting, and perform highly reliable wafer division.

〔Example〕

FIG. 1 is a schematic diagram showing a wafer dividing apparatus which is an embodiment of the present invention, FIG. 2 is a plan view showing a wafer attached to a frame, and FIG. 3 is a plan view showing a mask attached to a frame. FIG. 4 is an enlarged partial sectional view showing the state of formation of pellets and TEG portions on a wafer during P-2 Quanop.

The wafer dividing apparatus 1 of this embodiment includes, for example, as shown in FIG. 1, a dicing section 3 for cutting a semiconductor wafer 2;
It consists of an irradiation section 5 that irradiates ultraviolet rays 4 and a pickup section 7 that takes out pellets 10.

The wafer 2 is provided in a frame 8 as shown in FIG. 2, and this frame 8 has a UV tape 9 (Ultra
a Violet Tape), that is, a transparent plastic tape whose adhesive strength decreases when irradiated with ultraviolet rays is stretched, and the wafer 2 is attached to the adhesive surface of the UV tape 9 with the element formation side facing upward. has been done. Note that cutouts 8b and 8C for alignment are formed on the outer periphery of the frame member 8a at predetermined positions, respectively.

In the wafer 2 of this embodiment, a large number of semiconductor pellets 10 having a memory capacity of, for example, 1 megabyte are formed as one unit in the vertical and horizontal directions, and one side of each pellet 10 is A rectangular TEG portion 11 (remaining area) is formed adjacent to this TE
A large number of alignment marks and inspection elements (not shown) are provided on the surface of the G section 11.

When the frame 8 is moved to a predetermined position on the dicing stage 12 of the dicing unit 3 by a transfer means (not shown), the disc-shaped dicing blade 13 is lowered to a predetermined position on the wafer 2 while rotating at high speed, and then horizontally wafer 2 and performs dicing work on the wafer 2.

Here, the dicing of this embodiment is not so-called full dicing in which the front surface of the wafer 2 is completely separated from the back surface thereof, but the wafer parts are slightly connected in the vicinity of the back surface as shown in FIG. This is so-called semi-dicing, in which cuts 23 are formed as shown in FIG.

In addition, dicing is performed for each pellet 10 and the TEG section 11.
each along its boundary area. Therefore, the cross-sectional state of the wafer 2 after dicing is as shown in FIG.
Belem) 10 (10a, 10b) and TEG section 11
are connected in a block-like manner.

After the dicing is completed, the frame 8 is sent to the irradiation section 5.

The irradiation unit 5 includes a two-stage XY table 14.15 each having an XY direction drive means (not shown), and an ultraviolet irradiation lamp 16 provided below the XY table 14.15.
It has

Here, each XY table 14, 15 has an irradiation window 14a, 15a in its center, and this irradiation window 14.
'a, 15a are opened with a size that approximately corresponds to the inner circumferential edge of the frame member 8a.

A mask 17 is placed on the lower XY table 14. As shown in FIG. 3, the mask 17 has a light shielding pattern 19 of a predetermined shape made of chromium (Cr) formed on the surface of a transparent quartz glass 18, and is similar to a photomask used in a photoresist process, for example. It has a structure.

Like the wafer 2, the mask 19 is attached to a frame member 20a made of stainless steel, and cutouts 20b and 20C for alignment are formed on the outer periphery of the frame member 20a at predetermined positions. There is.

Next, the frame 8 is placed on the upper XY table 15.
t, the mask 17 and the wafer 2 are aligned. This alignment can be performed as follows.

First, the mask 17 is positioned on the lower XY table 14. This positioning of the mask 17 involves, for example, positioning the notches 20b and 20C of the frame member 20a in a manner corresponding to the shape of the notch formed on the XY table 15. The mask position thus determined, performed by matching to a bin (not shown), is once memorized.

Next, place the frame 8 5X on the upper XY table 15.
71, and moves the upper XY table 15 by a predetermined amount so as to match the memorized position of the mask 17. In this way, the optimal positioning is completed in a state where the memorized position of the mask 17 and the position of the wafer 2 are completely matched.

Next, the ultraviolet ray 4 is irradiated by the ultraviolet ray irradiation lamp 16 located below the lower XY table 14, and the ultraviolet 4 passes through the irradiation window 14a of the lower XY table 14, that is, the mask 17, and then passes through the upper XY table 14. XY tenible 1
The back side of the UV tape 9 of the frame 8 placed on the XY table 15 is irradiated through the irradiation window 15a of No. 5.

Here, in this embodiment, for example, as shown in FIG.
On the surface of the mask 17, a portion corresponding to the 720 portion 11 of the wafer 2 is covered with a light shielding pattern 1 of a predetermined shape using a vapor-deposited chromium film.
9 is formed, the ultraviolet rays 4 will not pass through this pattern 19 portion. Therefore, wafer 2
Only the part corresponding to the back side of the pellet 10 is irradiated with the ultraviolet ray 4, and the part corresponding to the back side of the 720 part 11 is not irradiated with the ultraviolet ray 4. Therefore, Belene) 10 is adhered on the UV tape 9. The adhesive strength is reduced only in that part, and the part where the 720 part 11 is attached maintains a strong adhesive strength.

Place pellet 1 on UV tape 9 of frame 8 as described above.
The frame 8 is transferred to the pickup section 7 with the adhesive strength of only the adhered portion of the frame 8 reduced.

In the pickup section 7, a push-up bin 21 is located below a frame 8 fixed by a fixing means 24.
This push-up bin 21 moves to a predetermined position directly below the back surface of the wafer 2, and further rises to perform the push-up operation of the pellets 10 in sequence.
A collet 22 that adsorbs O is located, and as the push-up bottle 21 pushes up, the pellet 10 pushed up from the adhesive surface of the UV tape 9 is picked up by the collet 22.
2 comes down and is held by vacuum suction. At this time, in this embodiment, as shown in FIG.
The adhesive surface of the pellet IO portion on the V-tape 9 has decreased adhesive strength due to the irradiation with ultraviolet rays 4, so the pellet l
0 (10a) is easily separated from the UV tape 9 and vacuum-adsorbed to the collet 22. On the other hand, 720 copies 11
Because the ultraviolet rays 4 were blocked by the irradiation part 5 due to the action of the mask 17, the adhesive force remained strong,
It is designed so that it cannot be easily separated from the UV tape 9. Therefore, the collet 22 makes the pellet 1
When 0 is vacuum-adsorbed, the part 720 11 adjacent to the pellet 1O subjected to big amplification is prevented from moving at a predetermined position on the UV tape 9. Therefore, 720
Damage to the wafer 2 due to movement of the portion 11 can be prevented.

Furthermore, 720 parts 11 has a strong adhesive strength that makes UV tape 9
Since it remains on the top, it is possible to prevent the entire position of the wafer 2 from shifting. This is particularly effective when picking up only good pellets. That is, as shown in FIG. 4, only the good pellets 10a are picked up from the UV tape 9, and the defective pellets 1 are picked up.
If 0b is left on the UV tape 9, the defective Veret 1-10b that remains on the UV tape 9 will be adhered with low adhesive strength due to the irradiation with ultraviolet 4 as described above. However, the surrounding 720 parts 11, which maintain a slight connection state, are adhered to the UV tape 9 with strong adhesive force. Therefore, good quality Beret IOa
Even when only the wafer 2 is selectively picked up, the entire wafer 2 maintains its predetermined position on the UV tape without any displacement. Therefore, the pellet 10 can be picked up at an accurate position.

As described above, according to this embodiment, the following effects can be obtained.

(1) By irradiating the back side of the UV tape 9 on which the wafer 2 is attached with ultraviolet rays 4 through the mask 17 on which the light-shielding pattern 19 of a predetermined shape is formed, 720 copies are applied on the adhesive surface of the UV tape 9. Since it is possible to maintain strong adhesive force in the portion 11 and reduce the adhesive force only in the portion of the pellet 10, it is possible to easily pick up only the pellet 10 at a predetermined position.

(2) Due to the above-mentioned fil, only the pellet 10 can be picked up while the 720 part 11 remains strongly attached to the UV tape 9, so damage to the wafer 2 due to movement of the 720 part 11 can be prevented. can.

(3) According to (1) above, when selectively picking up only the good pellets 10a from the wafer 2, the wafer 2
It is possible to prevent the entire position from shifting, and it is possible to pick up at an accurate position.

(4) With (11, (2+), and (3) above, highly reliable wafer division can be realized.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, in the embodiment, a case was explained in which so-called semi-dicing was used in which each wafer part maintained a connected state, but each wafer part was
So-called full dicing, in which the wafer is divided completely independently on the V-tape, may also be used.

In the above explanation, the invention made by the present inventor was mainly applied to its field of application, which is the division of wafers used in the manufacture of semiconductor devices, but the present invention is not limited to this, and other It may also be a wafer used for manufacturing electronic devices.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, the wafer was diced while attached to the adhesive surface of a translucent tape whose adhesive strength decreased when irradiated with a predetermined light, and a light-shielding pattern of a predetermined shape was formed on the back side of the adhesive surface of the tape. After aligning the mask and irradiating the tape with a predetermined light through the mask, by picking up the pellet at a predetermined location, depending on the light-shielding pattern formed on the mask, any part of the backside of the wafer can be detected. Since it is possible to reduce only the adhesive strength of the part,
When picking up the wafer, no movement or displacement of other wafer parts occurs. Therefore, highly reliable wafer division can be performed.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic diagram showing a wafer dividing device which is an embodiment of the present invention, Fig. 2 is a plan view showing a wafer attached to a frame, and Fig. 3 is a plan view showing a wafer attached to a frame. FIG. 4 is a plan view showing the attached mask; and FIG. 4 is an enlarged partial sectional view showing the formation of the pellet and TEC on the wafer during pickup. DESCRIPTION OF SYMBOLS 1... Wafer dividing device, 2... Wafer, 3... Dicing part, 4... Ultraviolet rays, 5... Irradiation part, 7...
・Pink-up part, 8... Frame, 8a... Frame member, 8b, 8c... Notch, 9... UV tape, 10... Pellet, IOa... Good pellet,
10b...defective pellet, 11...TBG section, 1
2... Dicing stage, 13... Dicing blade, 14.15... XY table, 14a. 15a... Irradiation window, 16... Ultraviolet irradiation lamp, 1
7...Mask, 1B...Quartz glass, 19...S
m optical bar 9-, 20a... frame member, 20b, 2
0c... Notch, 21... Push-up bottle, 22...
-Collet, 23...notch, 24...fixing means.

Claims (1)

[Claims] 1. Dice the wafer with the wafer attached to the adhesive surface of a translucent tape whose adhesive strength decreases when irradiated with a predetermined light, and place a predetermined amount of adhesive on the back side of the adhesive surface of the tape. A wafer dividing method in which a mask on which a shaped light-shielding pattern is formed is aligned, a predetermined light is irradiated onto the tape through the mask, and then pellets at a predetermined portion are picked up. 2. The wafer has, on its front surface, an extra area where test elements are formed as well as a pellet forming area, and the mask has a pattern that blocks irradiation of a predetermined light to a back surface part of the extra area. A wafer dividing method according to claim 1. 3. The wafer dividing method according to claim 1 or 2, wherein the irradiated light is ultraviolet light. 4. Aligning the dicing mechanism that dices the wafer with the wafer attached to the adhesive surface of the tape whose adhesive strength decreases when irradiated with a predetermined light, and the mask on which a light-shielding pattern of a predetermined shape is formed on the wafer. an irradiation mechanism having an irradiation means for irradiating a predetermined light onto the back surface of the adhesive surface of the tape through the mask;
A wafer dividing apparatus comprising a pickup mechanism having a pickup pin that pushes up pellets at a predetermined position from the back side of the adhesive surface of the tape. 5. The wafer dividing apparatus according to claim 4, wherein the light irradiation means is an ultraviolet irradiation means.