JPS6052039A - Changing method into chip of semiconductor wafer - Google Patents

Abstract

PURPOSE:To remove static electricity generated in a wafer on a cutting by conductivity, and eliminate the contamination of a chip after the cutting by re-peeling simultaneously by pasting the wafer on a re-peeling conductive adhesive sheet and cutting the wafer. CONSTITUTION:The periphery of a conductive adhesive sheet 3 in which a wafer 6 is pasted on an insulating base material 8 is coated with a conductive frame 7, and the conductive frame 7 is grounded through a fixed plate 5 made of a metal grounded by a ground wire 4. The conductive frame 7 may be grounded directly by the ground wire 4 from a conductive base material 2. The conductive frame 7 grounded by the ground wire 4 may be pasted with conductive adhesives 1 and grounded. The conductive adhesive sheet 3 may be pasted on the fixed plate 5 in consideration of grounding.

Description

[Detailed Description of the Invention] The present invention uses a removable conductive laminated sheet to prevent electrostatic damage to circuits when dividing a semiconductor wafer into single devices (hereinafter referred to as chips). This invention relates to a method of making semiconductor chips into chips, which is characterized by the following.

# of semiconductor products in general! Chips such as beam-structured circuits (hereinafter abbreviated as ICs) in overfill plugs are produced by cutting a wafer into multiple circuit patterns that are simultaneously formed in a lattice-like manner on a disk made of silicon single crystal, etc. Conventionally, when cutting wafers, in order to prevent chips from scattering after cutting, wafers are fixed on a general-purpose laminated sheet and cut using a dimming machine, etc., but the number of rotations of the blade per rotation is several thousand. ~
Because the speed is tens of thousands of RPM, multiple static electricity is generated and tends to accumulate in the wear.For this reason, in the case of ICs with minute circuit patterns, dielectric breakdown may occur between conductors. This danger is especially serious in MO5 type semiconductors.

Therefore, in the case of such a semiconductor, vc is grounded without using the stacking sheet r, and the ware 1 is fixed on the 7t4 body, and in order to prevent scattering, it is limited to a part of the front surface of the cut wafer (referred to as half-cut). ) At present, they are attached to a laminated sheet in this state and then bent and broken to form chips.

The bending breakage occurs in the thickness direction when using force while using a sword. There is a drawback that the chip does not progress linearly, and the broken line on the tip end surface extends into the circuit, resulting in poor precision in chip dimensions.

As a method to improve this chip dimensional accuracy and prevent electrostatic damage to ICs, attempts have been made to cut the entire thickness of the wafer in the thickness direction (referred to as full cut) while imparting tetraelectricity to the wafer. There is.

One method is to fix T2 on a general insulating adhesive sheet and add a surfactant to increase the conductivity T to 7.
There is a way to completely cut the water by spraying it with ionized water, but for cattle conductors who do not want to hide impurity ions, there is a natural limitation in the selection of surfactants that impart ionicity to water. ! However, it has not been shown to have any significant effects because it has a high structure and does not provide sufficient conductivity.

'1st Another attempt is to fix the wafer with a conductive base material such as a conductive adhesive and a conductive adhesive sheet and then perform a full cut.

However, conventional 41i adhesives and conductive adhesive sheets are intended for permanent adhesion, and are used for wood [1M
When using 1i, the following drawback t1 (i.e., it is not possible to remove the chips from the conductive wetting agent and the adhesive sheet surface immediately after the wafer cutting process is completed.Also, even if it is forcibly removed, Adhesive and viscous powder are transferred to the chip surface.

This means that it cannot be used for semiconductor applications, which are extremely sensitive to contaminated VC.

In general conductive adhesive sheets, in order to provide both 4-electroconductivity and adhesiveness, there are adhesives that can reduce agglomeration and breakage of the S E'S agent. Peeling is not considered in the casing.

In addition, if there is contamination on the chip surface after peeling, the removal layer that fixes the chip to the substrate soil in the next process may be insufficient, or the Au
In the case of Si eutectic bonding, there is a disadvantage that contamination penetrates into the inside of the chip, resulting in circuit failure.

The present invention was made in view of the above situation. That is, the non-invention relates to a method of converting a wafer into chips, which is characterized in that, in addition to forming a 91-proof tip on the wafer, an electrolytic viscous sheet, which is removable to the chips, is used as a wafer holding member. Moreover, it takes advantage of the characteristics of a removable conductive adhesive sheet, and by pasting it on a wafer T4 conductive adhesive sheet and cutting it, the conductivity of the sheet allows it to be attached to the wafer during cutting. This makes it possible to remove the static electricity that is generated, and at the same time, due to the removability of the conductive adhesive sheet, it is possible to cut the chips without contaminating the chips after cutting, and to prevent large defects when converting the wafer into two chips. It is possible to reduce the rate.

The conductive adhesive sheet used in the present invention includes carbon,
Adhesive t in which conductive light-emitting agent such as fine metal powder is dispersed
Static electricity generated on the wafer during cutting in 1-gold kA foil or plastic film can be grounded.It is advantageous to have a structure that can be grounded along the thickness direction of the wafer and in the vertical direction at the shortest possible distance. The configuration may be such that it can be grounded to.

The electrical resistance in the thicker direction of the adhesive layer (hereinafter referred to as translayer resistance) is 104
Ω/- or less, preferably rX10'0/- or less 5-, and the adhesion property is preferably one that exhibits the removability VW described below. In other words, removability in the present invention means that the wafer can be attached to the adhesive sheet by some method, and even when cutting, the wafer is not laminated Ntn.
VC layer, and after cutting, apply a viscosity force that allows the chip to be peeled off by an appropriate means from the viscosity agent, and furthermore, do not leave any contamination such as lamination transfer on the chip surface. Adhesive strength cannot be defined unconditionally because it varies depending on the chip size, but it is usually 50 to 600 g/19 fl 1 m (JI
The viscosity increasing force by S C-2107) can be used. If the thickness is less than 30 g/19 mm, the dense layer during cutting will not be sufficient and the wafer or chips will easily scatter (60 g/19 mm or less).
If it is 0 g/19 mm or more, it becomes difficult to peel off the chip after cutting.

As a means of imparting removability, this is achieved by crosslinking the lamination process, and the crosslinking means for this purpose includes adding carboxyl groups, hydroxyl groups, and amine groups as functional groups to the adhesive.
Monomers with tM6- such as acid amide groups can be co-combined independently or in combination, or they can be blended with monomers having these functional groups, such as polyester resins and phenol resins, to form isocyanate groups, methylol groups, alkyl etherified methylols. Crosslinking is generally carried out using a crosslinking agent containing a base material.

In addition, in the case of natural rubber, etc., it is also possible to use sulfur cross-linking, resin cross-linking, etc., which are known. It is effective because the reaction rate is very high.

The VC that is being cut is laminated according to your peace of mind 1#I4
．． It is also possible to use a shielding agent such as a plasticizer.

When pasting, as a blade to obtain safe lamination strength, for example, means such as activation of laminated blood by pressurization, heating, solvent, etc.〒11
It can be used alone or in combination.

For example, as shown in Fig. 1, the grounding method for removing static electricity during cutting is through a small hole (not shown) provided in a metal fixed platen 5 that is grounded by a grounding wire 4. It is fixed to the 4-electroconductive adhesive sheet 3' on which six wafers are pasted by vacuum suction. Alternatively, there is a method in which the base material 2 of the electrically conductive laminated sheet or the adhesive 1 is used alone or the surroundings of both are grounded and a π conductive frame is used. Typical examples of this case are shown in Figs.

In FIG. 2, a wafer 6 is pasted on an insulating base material 8, a circumference #15 of a π4 conductive sticky sheet 3 is covered with a conductive frame 7, and a 4
The electric frame 7 is grounded via a metal fixed platen 5 which is grounded by a 7-seat W14. In Figure 6, 4
The conductive frame 7 can be directly grounded from the conductive base material 2 by the ground #4. Figure 4 is based on ground wire 4! ll Grounded conductive frame 7'? ! This is a case where it is attached to the electric adhesive 1 to provide a ground connection. In FIGS. 2 to 4, the ground wire 4 is directly connected to the conductive base material 2 without using the 4-conductor frame 7.
Alternatively, it is also possible to take it out from the conductive laminate 1, and the conductive frame 7 is typically made of gold W4, but as shown in FIG. You may attach it with care so that it can be removed.

As for the wafer cutting method, devices and methods commonly used for cutting conductor wafers can be used, such as a method using a dicing saw that cuts by rotating a very thin diamond blade at high speed.

It should be noted that the rc%vc is advantageous in the case of a full cut, but it can also be applied to the M effect in a half cut.

In the following examples, g-1 = detailed explanation will be attached.

100 parts, polyterpene resin (melting point 1
A 41#L adhesive composition consisting of 50 parts by weight of 50 parts of sulfur powder as a crosslinking agent and 1% of silver powder (trade name: Silvest TCG-1, manufactured by Tokuriki Co., Ltd.). Composition t Viscous 50% solids diluted with toluene
A drug bath solution was obtained.

9- This adhesive solution was applied to aluminum foil with a thickness of 50μ by a roll coater, dried, and a laminated sheet with a 20μ thick layer was formed.The translayer resistance in the thickness direction of this laminated sheet was 101Ω/ It was af. A 75φ wafer on which a bipolar integrated circuit was formed on this laminated sheet was attached using a purple rubber roll at a pressure of 2 kg/cIIP so that the wafer was exposed. At this time, the crushing force on the wafer was 80 g. / 19n+m'''C 7m□ (J I
S The wafer 6 is fixed by negative air suction through the hole, and the wafer 6 is placed so that the adhesive 1 of the conductive laminated sheet is in contact with the wafer 6.
The periphery of the sheet was fixed using a 4m adhesive sheet 5F obtained in the Fusho Example. That is, order wafer 6 and 7+: Static electricity is made of gold pA through conductive adhesive 1 and base material 2τ! I'I
It was configured as 1r#, which is connected to redundant board 5 and grounded.

Rotation speed 30. The wafer was fully cut in the thickness direction using a dicing saw using OOORPM to obtain 5 mm square bipolar type IC chips. At this time, there is no chip scattering during cutting (it is possible to successfully convert the wafer into t-chips).
JiLVC was able to be peeled off, and when the surface of the chip peeled from the laminated sheet was observed under a purple microscope, no layer shift of the adhesive was observed.

Also, as a result of testing this chip, the failure rate due to electrostatic damage was 0%.
There were no chip size defects as the full cut was h]nhi.

Examples 2 to 4 and Comparative Examples 1 to 2 The dispersion tVO of 2s conductive carbon black (DENKA BLACK, trade name of Denki Kagaku Kogyo Hoten) was changed to 40%, and the acrylic pressure-sensitive adhesive OiL was prepared using a kneader. Made of subsynthetic material 5
It was dispersed in Aron S-1511). The electrical resistance of the adhesive varies depending on the carbon black mold.

A cross-linking agent (made by Nippon Polyurethane Kogyo, trade name: Coronate L) was added to each of the 100 trays of the above adhesive at a solid content ratio of 3M Dobe gamma. After coating with a roll coater on Super Ohm (100 .mu.m), the ice was dried at 120.degree. C. for 2 minutes to obtain a viscous ice sheet If having a thickness of 10 .mu.m.

Comparison? 1J-1 is non-exclusive to the adhesive used by carbon black Mitsutsukuda, and Comparative Example 2 was formulated with a sticky agent similar to Example 5 and ldl, but without using the crosslinking agent.

Chip size 5 is placed on the surface of the four-electrode Karenuma sheet consisting
II1m square C-MO3lc! It was attached to a 100φ wafer with a circuit pattern BZ-C using a rubber roll.

In this case, in Example-4, because the stackability was insufficient, the wafer was heated to 100°C and the 0 wafer was pasted, and the adhesive sheet purple and the 4-density sheet were vacuum-sucked from the bottom. , in contact with the four-electrode substrate, tt! ! Kim J'Ji board r
I'm secretly watching and I'm off to the ground.

RPM 10 with a dicing saw. Wafer r with DOORPM
A C-MOS chip f of τ and 5 mmq was obtained by full cutting in the thickness direction.

Regarding this chip, as in Example-1, sticky sheet 〃1
What about the chip peelability, chip surface contamination, and electrostatic damage failure rate? It was measured. These results are shown in Table 1.

As a result, it was found that in the adhesives applied to the four-electrode treated Lfi+ of Examples 2 to 4, the failure rate due to electrostatic damage was extremely reduced or completely eliminated.

It was also found that by using VC in combination with adhesive, re-peelability of the adhesive occurs, and the adhesive can be easily peeled off without causing any viscous migration on the chip surface. As in Example 1, the static electricity generated during cutting was grounded onto the Kinjo board, which was grounded through the 4-electrostatic viscous sheet τ valve.
The O5 circuit 2 was not charged, and it appears that there were no electrostatic breakdown defects.

In Examples 2 to 4, there were no chip size defects or chip scattering during cutting, as in Example-1.

In Comparative Example-1, the adhesive was non-conductive, so the defective rate due to electrostatic damage was as high as 10%.In the case of Comparative Example-2, the pasting and cutting were good, but there was no electrostatic damage. No defects occurred, but since the adhesive did not seal the removability of the chip, the adhesive was used to clean the chip more thoroughly.

As mentioned above, by making chips using a special viscous sheet with removability, it is possible to reduce the static destructive phenomenon during wafer cutting, which has been a problem in the past. Or, it has become possible to eliminate it at all.

In addition, the obtained chip has a 4-electric adhesive sheet of 4f+ψ1
1 g, γM, η, etc., it is easy to remove the adhesive from the proprietary adhesive sheet, and there is no transfer of adhesive, etc. to the chip surface. For this reason, the step of surface example sumality is recommended.

The art of craftsmanship and non-invention has led to a significant reduction in defective rates in the semiconductor industry, providing highly demanded IC chips.

[Brief explanation of drawings]

Figures 1 to 5 are schematic cross-sectional views showing how to ground the ground for the uninvented method. 6. Conductive stacking sheet 4. Ground wire 5, gold x + i! Ii surface plate 6. Wafer 7, Conductive frame Continued from page 1 0 Inventor Kazuchika Mogami Inside the Oaza Ogawa 1 factory, Shimodate City

Claims (1)

[Scope of Claims] 1. A method of making chips by dicing a beef conductor coated on a sticky sheet. The adhesive sheet has a weight of 50 to 600 g/19 mm (JIS
C21D7) lamination force and 104Ω/al? Method for converting semiconductor wafers into chips, characterized in that the removable laminated sheet has the following electrical resistance r: t%