JPH01184191A - Ic chip and ic card - Google Patents

Abstract

PURPOSE:To enhance the mechanical strength of an IC chip and to prevent the damage thereof by the bending of an IC card, by specifying the center line average roughness (Ra) of the back surface of the IC chip. CONSTITUTION:When the center line average roughness of the polished surface of a silicon wafer is large, an IC chip is low in strength and extremely easy to break, because the strength of the IC chip is affected by the small injury or minute crack on the polished surface of the silicon wafer. Therefore, the center line average roughness (Ra) is set to 0.05mum or less, pref., to 0.03mum or less. When this roughness (Ra) is reduced, the strength of the IC chip becomes high. That is, the IC chip becomes extremely hard to crack even when bending deformation is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an IC chip or an IC card using the same.

(Prior art and problems to be solved by the present invention) In recent years, semiconductor devices (hereinafter referred to as IC chips) have come to be used in many fields, but miniaturization is desired in an increasing number of application fields in the future. ing. Under these circumstances, for certain specific applications, such as IC cards and memory cards, it is necessary to make the engineered C chip thinner and thinner, and the strength of the IC chip itself becomes an issue. It is becoming.

For example, the standard for IC cards is determined by 15O (International Organization for Standardization), and the thickness of the card is 0.76 m. An IC card with an IC chip mounted inside such a thin card can be easily bent if force is applied from outside the card, so the problem is how to prevent damage to the IC chip inside the card. . Therefore, methods of preventing damage to the IC chip are currently being considered, such as by strengthening the structure around the IC chip or by strengthening the card itself.

The present invention provides a new technology for increasing the strength of the IC chip itself, and also provides a highly reliable IC card that can prevent damage to the IC chip even when bending or other force is applied from the outside. provide.

(Means for solving the problem) The present invention has a center line average roughness (Ra) of 0 on the back surface of an IC chip.
．． IC chip with a size of 0.05μ or less or an IC equipped with it
provide the card.

The present inventor discovered that the strength of an IC chip is greatly influenced by the polishing state (surface roughness) of the IC chip. That is, by reducing the surface roughness of the back surface of the IC chip, the strength of the IC chip itself can be greatly increased. The surface roughness is a numerical value expressed as center line average roughness (Ra) according to the surface roughness standard of JISBO601-1982.

According to experiments conducted by the present inventor, IC chips can be
It became clear that Tep's own strength was greatly amplified.

For example, in an IC card, which is one of the uses for IC chips, the back side of the IC chip is polished to allow it to be installed inside a thin card.
Although it is necessary to make the thickness about 0 μm, it has become clear that even in this case, the strength of the IC chip itself is greatly amplified by the strength of the back surface of the IC chip.

The method of polishing IC chips is usually to bake an electric circuit onto a wafer, then polish the silicon wafer to a predetermined thickness, make it thinner, and then divide it by dicing.
A commonly used method is to make it into an IC chip. The silicon wafer is polished using a commonly used method such as a surface polisher or a grinder.

The present inventor discovered that the strength of the IC chip changes depending on the polishing state of the silicon wafer at this time, that is, the roughness of the polished surface of the silicon wafer. In other words, if the center line average roughness (Ra) of the polished surface of the silicon wafer is large, I
The strength of C-chip is weak and it is very easy to break. This is because small scratches and minute racks on the polished surface of the silicon wafer affect the strength of the IC chip. The required center line average roughness (Ra) varies depending on the application, but is usually 0.
0.05μ or less, preferably 0.03μ or less, more preferably 0.02μ or less. If this roughness (Ra) is reduced, the strength of the IC tip will be increased. That is, even if bending deformation occurs, the IC balance will be severely cracked.

As mentioned above, as an example of a specific application of the IC chip of the present invention,
Although the IC card of the present invention has been described, the strength of the IC chip is a major problem in the field where IC chips need to be made smaller and thinner, and the need for the IC chip of the present invention is very high. This is extremely meaningful.

(Example) First, a brief description of the drawings will be given below. FIG. 1 is a diagram for explaining the definition for measuring the bending strength of an IC chip according to an example of the present invention. 1 is a bending jig (tip R = 1 mri), speed 0.451R
2 indicates an IC chip (lower side of the polished surface), and 3 indicates a bending table (distance: 4 m).

FIG. 2 is a diagram for explaining the definition of the amount of bending in the bending resistance test of an IC card. 1 indicates the card, 2 indicates the IC module, and d indicates the amount of card bending.

Example 1-5 = The back surface of a silicon wafer was polished to a thickness of 260μ, and the center line average roughness (Ra) of the back surface was processed to seven types of roughness, each of which was 5.7 HX 5 by dicing.
．． It was cut into 71!11 chips and the bending strength was measured. The bending strength was measured by the measuring method shown in FIG. The measurement results are shown in Table 1 and Figure 3.

As is clear from this measurement result, the centerline average roughness (R
There is a relationship between a) and chip strength, and the centerline average roughness (
By reducing Ra ), the chip strength increases and damage to the IC chip can be prevented.

Table 1 Example 2 The IC chip produced in Example 1 was made into a module, mounted on a card, and subjected to a bending resistance test. The bending resistance test is I
In accordance with SO's latest proposal, the card was bent 250 times in the short side direction by a bending amount d21° defined in FIG. 2 at a cycle of 30 times per minute. The test results are shown in Table 2. As shown in Table 2, the IC chip centerline average roughness (
If the center line average roughness (Ra) is large, the IC chip will crack, but if the center line average roughness (Ra) is small, the chip will not break.

Table 2 (Effects of the Invention) As described above, the present invention can greatly improve the mechanical strength of the iC chip, and the IC chip mounted with the IC chip of the present invention.
In the C card, damage to the IC chip due to bending of the card or the like is effectively prevented, and a highly reliable IC card can be provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the definition for measuring the bending strength of an IC chip according to an embodiment of the present invention. 1...
・Bending jig (tip R: 1mm), speed 0.51min
, 2 - IC chip (lower polished surface), 3... bending table (distance: 4 mm), Figure 2 is a diagram for explaining the definition of the amount of bending in the bending test of IC cards. . 1...Card, 2...IC module, d...Card bending amount FIG. 3 shows the relationship between the centerline average roughness and bending fracture strength of the IC chip in Example 1. Patent applicant: Asahi Kasei Industries, Ltd. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) The center line average roughness (Ra) of the back surface of the IC chip is 0.
IC chip with a thickness of 05μ or less (2) The center line average roughness (Ra) of the back surface of the IC chip is 0.
IC card equipped with an IC chip of 0.05μ or less