JPH04336448A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To protect a wafer against cracking during probing process or conveyance by applying a reinforcing board to the rear surface of the wafer applied with a surface protective tape immediately after rear surface grinding process during which strength of the wafer deteriorates considerably. CONSTITUTION:Upon finish of rear surface grinding work of a semiconductor wafer 21, a protective tape 23 is applied through a water soluble glue onto a device fabricating surface 24. A reinforcing board 25 having picker holes 26 is further applied thereon. The protective tape 23 is then peeled off and the wafer 21 is cleaned. The wafer 21 is then scribed along a scribe line by means of a dicing plate until the reinforcing board 25 is reached thus dicing the wafer. Thereafter the wafer is irradiated with ultraviolet ray from the direction of the reinforcing board 25 in order to lover the bonding force. Consequently, the wafer is protected against cracking during peeling process of surface protective tape, probing process, assembling process, and the like. Furthermore, the picker holes facilitate die pick up process.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] This invention relates to the manufacture of semiconductor devices,
In particular, it relates to a reinforcing method for wafer dicing and pickup steps after completion of element formation in the wafer process.

0002

2. Description of the Related Art FIGS. 2(a) to 2(f) show the steps from completion of a conventional semiconductor device wafer process to die scribing and pickup.

FIG. 2(a) shows a semiconductor wafer 1 that has completed the semiconductor device fabrication process, and generally has a thickness 2 of 625 μm for a 6″φ wafer and 725 μm for an 8″φ wafer. However, such a wafer thickness 2 is inappropriate for die mounting, and the back surface of the semiconductor wafer 1 has a thickness of 200 to 45 mm.
It is ground to a thickness suitable for 0μm mounting specifications. In order to protect the device surface 3 during this grinding process, a surface protection tape 4 is attached with adhesive glue (not shown). In this state, as shown in FIG. 2(b), the semiconductor wafer 1 is ground to a thickness 2' of 200 to 450 μm in accordance with mounting specifications. Figure 2 (
c). Thereafter, the chip goes through a probing process to determine whether the electrical characteristics of the chip are good or not, and then is transported to an assembly process. Thereafter, as shown in FIG. 2(d), a dicing tape 5 is adhered to the back surface of the semiconductor wafer 1 using an adhesive in order to perform a chip scribing process and die extraction. Furthermore, as shown in FIG. 2(e), the wafer 1 is diced along the scribe line, and 6 is a dicing groove at this time, and the wafer 1 is diced so as to reach the dicing tape 5. Reference numeral 7 indicates the dice separated by this process. After dicing, in order to facilitate separation of the dicing tape 5 and the dice 7, ultraviolet rays are irradiated from the tape surface to harden the adhesive paste. Thereafter, the dice 7 are peeled off from the dicing tape 5 by piercing the dice dicing tape 5 with the picker needle 8, and the dice 7 are vacuum-adsorbed by the collet 9 and extracted.

0004

[Problems to be Solved by the Invention] However, in wafers that are ground thin to 200 to 450 μm depending on packaging specifications, the strength decreases due to the thickness, and the strength of the wafers decreases due to the thickness, and the strength of the wafers decreases due to the thickness. There was a problem of wafer cracking. In particular, 8″φ wafers and 200μ wafers have recently been used.
Wafers for IC cards and the like with a diameter of less than m are a cause of many wafer cracks. Additionally, transportation between a pre-processing wafer processing factory and an assembly factory is generally a major cause of wafer cracking. As a technology for dealing with such thin wafers, Japanese Patent Application No. 180890/1983 proposes coating the back side with an organic film of about 10 μm to improve strength.
Although it is effective for the following wafers, it is insufficient to satisfy the wafer strength for wafers of 8"φ or more. Furthermore, in Japanese Patent Application No. 60-146522, in order to improve the wafer strength, A method has also been proposed in which a Styrofoam substrate is attached and the dice are picked up by piercing the Styrofoam with a picker needle.However, because the substrate material is soft, the wafer is not held in place during die scribing, resulting in chips being chipped. There was a drawback that

The present invention solves the above-mentioned problem that wafer strength is relatively reduced as wafers become thinner and have larger diameters, and wafer cracks occur during the probing process or during wafer transportation. This was prevented by improving the strength.

[0006]

[Means for Solving the Problems] For the above-mentioned purpose, the present invention provides a method for manufacturing a semiconductor device in which, during backside grinding, a tape used to protect the device surface is left on the backside to give strength to the wafer. This plate is made of a material with good ultraviolet transmittance and has a structure with a hole for a picker used in the die extraction process.

[0007]

[Operation] As described above, according to the present invention, immediately after the backside grinding process, in which the wafer strength is significantly reduced, a reinforcing plate is attached to the backside of the wafer with a surface protection tape attached, and the wafer is Since the strength is improved, it is possible to eliminate cracks in the wafer that occur during the surface protection tape peeling process, probing process, assembly process, etc. Further, since it has a picker hole to accommodate a picker, it can be used up to the step of removing the dice by die picker processing, and the step of attaching the dicing tape can be eliminated.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view of a wafer showing steps of an embodiment of the present invention. Figure 1(a) shows the back surface after grinding, 21 is a semiconductor wafer, 22 is a semiconductor wafer that has been ground to a thickness of 200 to 450 μm due to mounting specifications, and 23 is a semiconductor wafer after this grinding process. , device fabrication surface 2
4, and is attached to the device fabrication surface 24 with a water-soluble adhesive (not shown). Next, as shown in FIG. 1(b), a reinforcing plate 25 having a thickness of 300 to 1000 μm is attached using adhesive while keeping the tape attached. In this method, the reinforcing plate 25 is made of, for example, quartz with good ultraviolet transmittance, and the adhesive is made of a material that is cured by ultraviolet rays and has a weak adhesive strength, so that it is easy to peel the dice from the reinforcing plate, which will be described later. can do. Furthermore, this reinforcing plate 25 is structured to have a picker hole 26.

Next, as shown in FIG. 1(c), the protective tape 23 is peeled off, and the water-soluble glue is washed away by a spin washing method or the like. Thereafter, as shown in FIG. 1(d), the film is scribed along the scribe line with a dicing plate until it reaches the reinforcing plate 25, and divided into dice. 27 is a scribe groove at this time, and 28 is a divided die. After the scribing is completed, the adhesive paste is irradiated with ultraviolet rays from the direction of the reinforcing plate 25 to reduce the adhesive strength. Thereafter, as shown in FIG. 1(e), by pushing up the picker 29 from the picker hole 26, the die 28 is inserted into the reinforcing plate 25.
The film is peeled off, vacuum-adsorbed using a collet 30, and the die is extracted. FIG. 3(a) shows a cross-sectional view of the positional relationship between the die 28, the picker 26, and the reinforcing plate 25 at this time, and FIG. 3(h) shows a plan view thereof. Depending on the size of the die 28, the reinforcing plate 25 is set in advance to correspond to the die 28 and to be sufficiently larger than the diameter of the picker needle 26, and the picker spacing is set in accordance with the spacing of the picker holes. This picker hole 26 is
In the figure, four picker needles are installed for one die, and the die is supported by four picker needles, but any number of picker needles may be used as long as it is three or more. The picker hole 26 installed as described above is used when bonding the wafer.
Aiming at the scribe line, adhere it to the scribe line at equal intervals using adhesive glue 31.

FIG. 4 shows a structure in which the reinforcing plate is not cut by the dicing plate during die scribing, and a die blade avoidance groove 32 is installed along the scribe line, and the groove width 33 is as follows. Approximately 40μ
100-1000 μm for a die blade thickness of m
In addition to providing a sufficient margin, the groove depth 34 is set to be approximately 100 μm deep relative to the depth of cut.

[0011]

[Effects of the Invention] As described above, according to the present invention, a reinforcing plate is attached to the back side of the wafer with the surface protection tape attached immediately after the back side grinding step, which significantly reduces the wafer strength. Since the wafer strength is improved, it is possible to eliminate wafer cracks that occur during the surface protection tape peeling process, probing process, assembly process, etc. Furthermore, since this reinforcing plate is made of a material such as quartz, it can also be used as a substrate for die scribing, and since it has a picker hole to accommodate a picker, it can be used in the die extraction process using a die picker. It has the feature that it can be used up to the point where the dicing tape is applied, and the step of attaching the dicing tape can be eliminated.

[Brief explanation of drawings]

[Fig. 1] Illustration of an embodiment of the present invention

[Fig. 2] Explanatory diagram of conventional example

[Figure 3] Relationship diagram between die, picker hole, and reinforcing plate

[Figure 4]
Reinforcement plate with blade guard grooves

[Explanation of symbols]

21 Semiconductor wafer 22 Wafer thickness 23 Protective tape 25 Reinforcement plate 26 Picker hole 27 Scribe groove 28 Dice 29 Picker 30 Colette

Claims (4)

[Claims] 1. In the manufacture of semiconductor devices, as a reinforcing method for processes such as dicing and pickup after completion of semiconductor element formation in a wafer process, the semiconductor wafer is ground with a surface protection tape attached thereto. A method for manufacturing a semiconductor device, characterized in that a reinforcing plate is bonded to the back surface. 2. The reinforcing plate according to claim 1 is made of a highly ultraviolet transmitting material, the adhesive thereof is made of an ultraviolet curing material, and after die scribing, ultraviolet rays are irradiated from the reinforcing material surface to reduce the adhesive strength. A method for manufacturing a semiconductor device, characterized in that: 3. The reinforcing plate according to claim 1 is arranged to correspond to the die, and a hole for a die picker is provided,
A method for manufacturing a semiconductor device, characterized in that the die is peeled off from the reinforcing plate by pushing up through the hole with a pick needle. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the reinforcing plate is provided with a blade-preventing groove to prevent the reinforcing plate from being cut by a dicing blade during die scribing.