JPH05335411A - Manufacture of pellet - Google Patents

Abstract

PURPOSE:To prevent cracks of a silicon substrate at the time of dicing, by forming a trench along a prearranged division border line of a pellet on the surface side of a silicon substrate, making the trench link with the rear at the same time when the rear of the silicon substrate is eliminated in the course of rear grinding process, and dividing each pellet. CONSTITUTION:A trench digging process is provided wherein trenches 4 having bottoms are dug on the pattern 2 forming surface side of a silicon substrate 1, along prearranged division lines of a pellet 3, with a dicing equipment. A rear grinding process is provided, after the above process, wherein the surface side of the silicon substrate 1 is retained, the rear side of the substrate 1 is grinded until at least the bottoms of the trenches 4 are opened and pellets 3 are formed. The elimination amount of the trench having the bottom by grinding is 20-25mum. Thereby it is unnecessitated that handling is again performed as in the conventional case, after the rear grinding process, and then dicing is executed.

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, VLSI ( V e
ry L arge S cale I ntegrated
The present invention relates to a method for manufacturing pellets used for semiconductor devices such as circuits.

[0002]

2. Description of the Related Art Generally, a dynamic RAM ( R and
om A ccess M emory) and many of the VLS
For I, the junction leakage current must be low. Narrow base width bipolar transistors are sensitive to the deposition of impurities, causing a short circuit between the emitter and collector (this is called the "pipe effect"). In particular, metal impurities such as transition metals are likely to cause such an effect. These elements are located in the interstitial or substitutional type, and serve as the generation recombination centers. The precipitation phase of these impurities is silicide and has electrical conductivity. There are many methods known as "gettering" processes for removing these impurities from the device region. That is,
"Gettering" is a general name for a process of removing harmful impurities and defects from an element region. Thereby,
It is possible to obtain a silicon substrate having a sink that absorbs impurities mixed during the device manufacturing process.

As the "gettering", extrinsic gettering for artificially imparting a defect to the substrate from the outside is known.
g) method and Intrinsic Gettering that introduces minute defects into the substrate.
ring method.

Of these, the extrinsic gettering method applies a lattice strain to the back surface of the substrate opposite to the device forming region. 6 to 8 show an example of the method of applying the lattice strain. That is, in this method, the pattern B is first formed on the surface side of the substrate A on which the pattern B is formed.
A protective tape C for protecting the is attached (see FIG. 6). Next, the back surface side of the substrate A on which the pattern B is formed by the thickness d is removed by grinding (see FIG. 7). Further, a groove is formed along the contour of the pellet by dicing (not shown).

However, according to this backside grinding method, when the pellet thickness is 200 μm or less and the substrate diameter is 6 ″ or more, substrate cracking occurs when the substrate is attached and detached from the chuck after the backside grinding process, or However, as a result of cracking of the substrate due to a handling error during the dicing process, it has a drawback of contributing to a decrease in yield.

[0006]

As described above, in the conventional method for manufacturing a pellet for a semiconductor device, if the pellet thickness is 200 μm or less and the substrate diameter is 6 ″ or more,
After the back surface grinding process, when the substrate is detached from the chuck, a substrate crack occurs or a handling error occurs during the dicing process, resulting in a substrate crack. As a result, the yield is lowered.

The present invention has been made in consideration of the above circumstances, and provides a pellet manufacturing method capable of solving the technical problems of the conventional semiconductor device manufacturing method described above and improving the yield. With the goal. [Constitution of Invention]

[0008]

In the method of manufacturing a pellet according to the present invention, a groove is formed in advance on a front surface side of a silicon substrate along a dividing boundary of the pellet in a grooving step, and a silicon is formed by a back surface grinding step. At the same time as the removal of the back surface of the substrate, the groove is communicated with the back surface to separate the pellets.

[0009]

According to the pellet manufacturing method having the above-described structure, it is not necessary to re-handle the wafer after the back surface grinding step and dicing as in the prior art, and it is possible to prevent cracking of the silicon substrate that occurs during dicing. This is remarkably effective when the silicon substrate has a large diameter or when the thickness of the silicon substrate after the backside grinding is thin, and contributes to the improvement in the yield of the backside grinding process and the improvement in work efficiency. It will be large.

[0010]

An embodiment of the present invention will be described in detail below with reference to the drawings.

1 to 5 show a method of manufacturing pellets according to this embodiment. This pellet manufacturing method is, for example, a bottomed groove 4 having a width of, for example, 50 μm on the pattern 2 formation surface (surface of the silicon substrate 1) side of a silicon substrate 1 having a thickness of 600 μm along the dividing boundary line of the pellet 3. Grooving process for engraving ... with a dicing machine (see Fig. 1)
And a cleaning step of cleaning and drying the silicon substrate 1 after the grooving step to remove polishing dust generated in the grooving step, and a pattern 2 of the silicon substrate 1 after the cleaning step.
Protective tape 5 for protecting this pattern 2 on the formation surface
And a protective tape attaching step (see FIG. 2), and a back surface grinding step in which the protective tape 5 side of the silicon substrate 1 is vacuum-sucked by a chuck after the protective tape attaching step to grind the back surface of the silicon substrate 1 (FIG. 3)), a mounting tape attaching step (see FIG. 4) for attaching the mounting tape 6 to the back surface side of the silicon substrate 1 after the back surface grinding step, and the protective tape 5 after the mounting tape attaching step. Of the protective tape peeling step (see FIG. 5) for peeling the silicon from the front surface side of the silicon substrate 1 and the pellets 3 ... Attached integrally to the mounting tape after the protective tape peeling step are predetermined in a lead frame (not shown). It comprises a pellet fixing step (not shown) in which one piece is placed on each part separately from the mounting tape. Then, in the grooving step, grooving is performed in a grid pattern by a dicing device according to the dimensions of the pellets 3 ... Depth D1 of each groove 4 (for example, 22
0 μm) is the thickness T of the silicon substrate 1 after the back surface grinding step.
20 μm to 25 μ more than 1 (for example, 200 μm)
It is set to be larger by about m. On the other hand, the removal amount T2 in the back surface grinding step is, for example, such that the sum of the removal amount T2 and the thickness T1 of the silicon substrate 1 after the back surface grinding step becomes equal to the thickness T3 of the silicon substrate 1 before processing. 40
Set to 0 μm. Therefore, after the back surface grinding step, the grooves 4 ... Open to the back surface side of the silicon substrate 1. As a result, the pellets 3 ... Are separated and are ready to be separated. Further, the grinding wheel of the dicing device used in the grooving step has, for example, a mesh size of # 20.
00 / # 3000 diamond abrasive grains, for example, cutting depth of 300 μm, rotation speed of 50 / min
Dicing is done at 00m. In addition, the back surface grinding apparatus has a mesh size of # 1000, for example.
/ # 1500 diamond abrasive grains are surface-ground by a cup-type grindstone bonded with a vitrified binder.

As described above, according to the pellet manufacturing method of this embodiment, in the grooving step, the grooves 4 ... Are engraved on the surface side of the silicon substrate 1 along the planned dividing line of the pellets 3 ... At the same time as the removal of the back surface of the silicon substrate 1 by the back surface grinding step, the grooves 4 ... Are communicated with the back surface to separate the pellets 3 ... There is no need. Therefore, in the pellet manufacturing method of this embodiment, it is possible to prevent cracking of the silicon substrate 1 that occurs during this dicing. This is remarkably effective when the silicon substrate 1 has a large diameter or when the thickness of the silicon substrate 1 after grinding the back surface is thin. Further, the cutting precision of the grooving by the dicing device may be worse than the conventional one. Furthermore, in the finishing process of backside grinding, since grinding is performed in pellet form, the wraparound of the grinding liquid is improved and the grinding performance is improved. Together, these various effects contribute to improving the yield and work efficiency of the backside grinding process.

[0013]

According to the pellet manufacturing method of the present invention,
In the grooving process in advance, grooves are engraved on the front surface side of the silicon substrate along the planned dividing line of the pellets, and at the same time the back surface of the silicon substrate is removed by the back surface grinding step, the grooves are communicated with the back surface and each pellet is separated. Since this is done, there is no need to perform re-handling and dicing after the back surface grinding step as in the conventional case. Therefore, in the pellet manufacturing method of the present invention, it is possible to prevent the silicon substrate from cracking during dicing. This is remarkably effective when the silicon substrate has a large diameter or when the thickness of the silicon substrate after the backside grinding is thin, and as a result, it improves the yield and the work efficiency of the backside grinding process. The contribution will be large.

[Brief description of drawings]

FIG. 1 is a diagram showing a grooving step in a method for manufacturing pellets according to an embodiment of the present invention.

FIG. 2 is a diagram showing a protective tape attaching step of the pellet manufacturing method according to the embodiment of the present invention.

FIG. 3 is a diagram showing a back surface grinding step of the pellet manufacturing method according to the embodiment of the present invention.

FIG. 4 is a diagram showing a step of attaching a mounting tape for a pellet manufacturing method according to an embodiment of the present invention.

FIG. 5 is a diagram showing a protective tape peeling process of the pellet manufacturing method according to the embodiment of the present invention.

FIG. 6 is a diagram showing a protective tape attaching step of a conventional pellet manufacturing method.

FIG. 7 is a diagram showing a backside grinding step of a conventional pellet manufacturing method.

[Explanation of symbols]

1: silicon substrate, 3: pellet, 4: groove, 5: protective tape.

Claims (3)

[Claims] 1. A grooving step of forming a bottomed groove in accordance with a pellet dividing schedule on a front surface side of the substrate, and a front surface side of the substrate is held after the grooving step, and a back surface side of the substrate is at least a bottom portion of the groove. And a backside grinding step of grinding until the pellets are formed. 2. A margin for grinding a bottomed groove is 20 to 20.
It is 25 micrometers, The manufacturing method of the pellet of Claim 1 characterized by the above-mentioned. 3. The method for producing pellets according to claim 1, wherein a lattice strain for gettering is formed by grinding on the back surface side of the substrate.