JPH04277654A - Method for laser marking and accuracy management - Google Patents

Abstract

PURPOSE:To control the accuracy of automatic position reading in a laser marking system for putting an identification mark onto semiconductor wafers. CONSTITUTION:A semiconductor wafer 1 is positioned with respect to its orientation flat 2 and peripheral edge 3. A wafer identification mark 4 is put on an insulating film 5 in a predetermined location of a wafer by a laser. A reference frame 6 is provided on the insulating film 5, and the identification mark 4 is measured to check the accuracy of its position. The wafer is re-arranged before it is loaded in a laser marking device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for managing the positional accuracy of a substrate identification number on a semiconductor substrate. In recent years, in semiconductor device manufacturing, laser marking has become mainstream for marking substrate identification symbols on semiconductor substrates due to its high speed and readability.

[0002] Furthermore, due to the increase in the throughput of semiconductor substrates, high-speed and high-precision reading devices have been developed, and there is a corresponding demand for improved positional accuracy of substrate identification symbols.

0003

2. Description of the Related Art FIG. 5 is an explanatory diagram of a conventional example. In the figure, 18 is a semiconductor substrate, 19 is an orientation flat, 20 is an outer edge, 21 is a guide plate, 22 is a guide ring, 23 is a first photosensor, 24 is a second photosensor, 25 is a substrate chuck, and 26 is a It is an adsorption hole.

Conventionally, when marking a substrate identification number using a laser marking device, the semiconductor substrate 18
The semiconductor substrate 18 is automatically set in a laser marking device using the orientation flat 19 as a reference, and characters and numbers are marked (engraved) at the marking positions.

That is, as shown in FIG. 5(a), when the semiconductor substrate 18 is fed into the alignment mechanism using an air belt or the like, the first photosensor 23 is first blocked, the guide plate 21 is rotated, and the orientation is adjusted. flat 1
9 contacts the guide plate 21, the semiconductor substrate 18 blocks the second photosensor 24, a positioning signal is output, and the rotation of the guide plate 21 is stopped.

The guide ring 22 in front of the semiconductor substrate 18 is free to rotate, and there are two types, one for 5 inches and one for 6 inches, depending on the semiconductor substrate 18 used. When a 6-inch semiconductor substrate 18 is used, 5
The inch guide ring goes down and the semiconductor substrate 18
It is designed not to come into contact with the

Next, as shown in FIG. 5(b), the substrate chuck 25 comes below the semiconductor substrate 18 from the side.
The semiconductor substrate 18 is fixed to the substrate chuck 25 by the suction hole 26 by vacuum suction, and is set in that state at a position to be marked by a laser marking device.

[0008]

[Problem to be Solved by the Invention] However, even if such a mechanism is used, sudden positional and angular deviations may occur due to the feeding mechanism of the semiconductor substrate 18 and the adjusting mechanism of the orientation flat 19, and the positional deviation may not necessarily be the same as the specified one. It was difficult to load it in the correct position.

That is, as shown in FIG. 5(c), as a result of sudden deviation, the orientation flat 19 of the semiconductor substrate 18 does not come into complete contact with the guide plate 21, and even though there is a gap, the angle Θ Semiconductor substrate 1 when tilted
8 blocks the second photosensor 24, it is fixed as it is tilted at the angle Θ, and is horizontally moved laterally by the substrate chuck 25 having a vacuum suction hole 26, and then attached to the laser marking device. There was a problem with it being set.

[0010] Therefore, the marked substrate identification symbol may be misaligned and may be out of the reading range of the high-speed automatic reading device, resulting in unreadability or misreading.

The present invention is provided for the purpose of accurately marking a semiconductor substrate at a predetermined position and confirming the accuracy thereof.

0012

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 1 is a semiconductor substrate, 2 is an orientation flat, 3 is an outer edge, 4 is a substrate identification symbol,
5 is an insulating film, 6 is a reference frame, 7 is a guide plate, 8 is a guide ring, 9 is a ring shaft, and 10 is a ring shaft fixing plate.

[0013] In order to solve the above problems, Fig. 1
As shown in FIG. 2, a reference frame 6 is created by etching the insulating film 5 at the position where the substrate identification symbol 4 is to be marked on the semiconductor substrate 1, and the inclination of the semiconductor substrate 1 is adjusted when the semiconductor substrate 1 is loaded into the marking device. This problem can be solved by using an alignment mechanism when re-correcting the angle, etc.

That is, the object of the present invention is to position the semiconductor substrate 1 using the orientation flat 2 and the outer edge 3 as a reference, as shown in FIG. In the laser marking method for marking 4, a reference for accuracy detection is placed on the insulating film 5 formed on the semiconductor substrate 1 at a predetermined position where the substrate identification symbol 4 is to be marked, as shown in FIG. 1(b). By providing a frame 6 and measuring the positional accuracy of the substrate identification number 4 using the reference frame 6 as a reference, when loading the semiconductor substrate 1 into the laser marking device, as shown in FIG. , the semiconductor substrate 1
This is achieved by realigning the

[0015]

[Operation] In the present invention, laser marking can be performed with high precision by repositioning the semiconductor substrate fed into the laser marking device with the orientation flats aligned using the realignment mechanism, and it is also possible to perform laser marking with high precision by using a realignment mechanism to reposition the semiconductor substrate that is fed into the laser marking device with the orientation flat aligned. Misalignment can be easily detected by the frame.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a realignment mechanism according to an embodiment of the present invention. FIG. 3 shows an accuracy measuring method according to an embodiment of the present invention, and FIG. 4 shows the amount of deviation in the Θ direction and the number of sheets generated.

In the figure, 7 is a guide plate, 8 is a guide ring, 11 is a motor, 12 is an eccentric cam, 13 is a roller, 14 is a diamond-shaped movable shaft, 15 is a guide shaft, 16 is a spring, and 17 is a fixed plate. .

First, the actual accuracy of the conventional laser marking device was investigated. Measurements were performed on a total of 100 semiconductor substrates, 10 from each lot of 10 lots, targeting 6-inch semiconductor substrates.

First, a substrate is set on a metallurgical microscope equipped with a micrometer, and the orientation flat is aligned with the reference line of the micro eyepiece. After moving the measurement point to the marking position, we first measured the deviation in the X and Y directions, but none of them exceeded ±0.1 mm.

Next, Θ is measured. As shown in FIG. 3, the amount of deviation between the dots of the first character and the dots of the final 12th character is read using a reference line. The size of the laser dot within the character is 80 μm. That is, if there is a shift of one dot, the shift will be 0.08 mm.

The measurement results are shown in Table 1 and FIG. 4.

[0022]

[Table 1]

According to the results of measuring 100 semiconductor substrates, as shown in Table 1, the deviations in the tilt direction of the semiconductor substrates are as follows, except for deviations due to sudden alignment failures mentioned above in the section of the prior art. With normal variation, the number is 1.
As can be seen, the standard value range of ±0.5° is not exceeded. Here, the deviation of ±0.5° corresponds to the vertical deviation of the characters at the beginning and end of the symbol, and corresponds to ±0.57 mm.

[0024]

[Math 1]

However, if the reading device also deviates in angle with the same probability, Equations 2 and 3

[0026]

[Math 2]

[0027]

[Math 3]

Therefore, it is expected that there will be a reading error of approximately 1 out of 100 sheets. Further, if the angular deviation on the reading device side does not exceed 1 mm, the equations are 4 and 5, and a reading error of about 1 in 1,000 sheets is expected. (See Table 1 Values B)

[0029]

[Math 4]

[0030]

[Math 5]

[0031] As mentioned above, automatic reading is 100%
In order to make this possible, it is necessary to eliminate not only normal variations but also sudden deviations of 1 mm or more. Therefore, in the present invention, alignment is performed using a laser marking device, and by providing a realignment mechanism for the semiconductor substrate that is set at the marking position using a substrate chuck in that state, sudden angular deviations are completely eliminated.

A schematic diagram of the realignment mechanism of the present invention is shown in FIG. In principle, as shown in FIG. 1(c), after the orientation flat 2 of the semiconductor substrate 1 is positioned in the Y direction by making the angular deviation Θ zero with the guide plate 7, the outer edge 3 of the semiconductor substrate 1 is aligned. is held down by two guide rings 8 for positioning in the X direction.

That is, the guide plate 7 and the guide ring 8 of the realignment mechanism move the roller 13 facing the eccentric cam 12 rotated by the rotation of the motor 11 in the X direction by friction, and form a diamond-shaped movable ring whose one end is connected to the roller 13. axis 14
is moved to move the guide ring 8 and guide plate 7 in the Y direction along the guide shaft 15. Further, the guide ring 8 and the guide plate 7 are constantly pulled by the spring 16.

Guide ring 8 of this realignment mechanism
The guide plate 7 is initially opened, and after setting the semiconductor substrate 1 carried by the substrate chuck in this realignment mechanism, the motor 11 is rotated and the semiconductor substrate 1 is gradually moved by the guide ring 8 and the guide plate 7. Pinch and secure completely.

As a result, the angle Θ of the semiconductor substrate 1 becomes zero, there is no deviation in the X and Y directions, and the substrate identification symbol 4 is marked at a desired position by laser marking. This ensures 100% positional accuracy.

However, as a countermeasure against positioning problems of the laser mechanism of the laser marking device and positional deviation due to aging, an insulating film 5 is formed on the semiconductor substrate 1 as shown in FIG. A reference frame 6 surrounding the board identification symbol 4 is formed using photolithography technology and is inserted into a laser marking device at regular intervals as a tool to perform accuracy control.
Deal with problems on the equipment side.

[0037] In fact, the semiconductor substrate 1 used in the process
by initial oxidation before or after laser marking,
By forming the reference frame 6 on all the semiconductor substrates 1 at the same time when patterning the element isolation region or the buried diffusion region, it is also possible to detect the deviation accuracy before or after laser marking.

[0038]

[Effects of the Invention] As explained above, according to the present invention, by providing a realignment mechanism, it is possible to cope with sudden displacement of the substrate identification symbol on the semiconductor substrate. By providing a reference frame on the insulating film and using it as a tool, or by forming a substrate frame on all semiconductor substrates, it is possible to deal with aging of laser marking and equipment failure, and it is also possible to rearrange semiconductor substrates, align sets, etc. This greatly contributes to improving the performance of automatic reading technology.

Furthermore, in the future, there is a possibility of developing a marking device that can automatically align a board identification symbol to a reference frame on a semiconductor board.

[Brief explanation of the drawing]

[Figure 1] Diagram explaining the principle of the present invention

[Figure 2] Realignment mechanism of one embodiment of the present invention

[
Figure 3: Accuracy measurement method according to an embodiment of the present invention

[Figure 4]
Amount of deviation in Θ direction and number of sheets generated

[Figure 5] Explanatory diagram of conventional example

[Explanation of symbols]

1 Semiconductor substrate 2 Orientation flat 3 Outer edge 4 Board identification symbol 5 Insulating film 6 Reference frame 7 Guide plate 8 Guide ring 9 Ring shaft 10 Ring shaft fixing plate 11 is the motor 12 is an eccentric cam 13 is a roller 14 is a diamond-shaped movable axis 15 is the guide shaft 16 is a spring 17 is a fixed plate

Claims (2)

[Claims] [Claim 1] Laser marking for positioning a semiconductor substrate (1) based on the orientation flat (2) and outer edge (3) and marking a substrate identification symbol (4) at a predetermined position on the semiconductor substrate (1). In the step, an insulating film (
5) A reference frame (6) for accuracy detection is provided at the predetermined position where the board identification symbol (4) is marked.
A laser marking accuracy control method characterized by measuring the positional accuracy of the substrate identification number (4) using the reference frame (6) as a reference. 2. When loading the semiconductor substrate (1) into a laser marking device, the semiconductor substrate (1)
A laser marking method characterized by realigning.