JPH0744208B2 - Method for recognizing special pattern position of semiconductor wafer - Google Patents

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer special pattern position recognition method.

[0003]

2. Description of the Related Art As a device for measuring a semiconductor wafer chip (hereinafter referred to as a chip) in a semiconductor wafer manufacturing process, there is a wafer prober for determining whether a chip is a good product or a defective product and for marking a defective chip with a defective mark.

In this wafer prober, a large number of chips are arranged on the surface of a semiconductor wafer (hereinafter referred to as a wafer), and electrode pads are arranged inside the chips. A probe card stylus attached to the wafer prober is brought into contact with this electrode pad to establish continuity with a tester, which is a device for determining good / defective products, and this tester determines whether the chip is a good product or a defective product. A defective chip is marked with a defective mark by a device called an inker (or marker).

More specifically, this wafer prober is aligned with electrode pads in a large number of chips arranged on the wafer surface so that the probe card stylus is at a desired position. Then, it is observed whether the probe card stylus contacts the electrode pad at a desired position. Therefore, the wafer prober is provided with a microscope, and after confirming whether the alignment is correct, all the chips on the first wafer are sequentially measured.

Subsequently, the second and subsequent wafers are transferred, the wafer is adsorbed on the mounting table of the wafer prober, the mounting table is moved to the measurement position, and the measurement is performed there. Since the relationship between the probe card stylus and the electrode pad position at that time is already determined by the first wafer alignment, the measurement operation is automatically started. Next, read the coordinates, output this to the tester side, and use the inker (or marker) to
A defective mark is attached to the chip determined to be a defective chip.

[0007]

As a first drawback of the above-mentioned conventional technique, "deviation" occurs from the beginning when the mask is coated on the wafer surface in the pre-process of wafer production. That is, since the mask is covered for each wafer, the position of the wafer and the position of the mask are different for each wafer, and a positional deviation such as a manufacturing error occurs. To explain this with a diagram,
As shown in FIGS. 4A and 4B, this “deviation” (Δ
2) because the coordinates of the chip itself are “shifted” in x, Δy)
Since the test data of each chip after the first one is changed, the test data for the coordinates of each chip cannot be compared for all wafers.

An object of the present invention is to solve the above problems, and to provide a special pattern position recognizing method for a semiconductor wafer capable of accurately recognizing a special pattern position for a semiconductor wafer while compensating for manufacturing errors. It is in.

[0009]

[Constitution of the invention]

[0010]

According to the present invention, a step of obtaining the center of a semiconductor wafer and a step of reading out the special pattern position of the semiconductor wafer from a memory in which coordinates from the center to a predetermined special pattern are stored. And a step of optically detecting the special pattern and a regular chip pattern around the pattern, and a step of accurately recognizing the position of the special pattern based on the data obtained in this step. It is a method of recognizing a chip position of a semiconductor wafer.

[0011]

[Effect] The position of the special pattern provided on each wafer is automatically recognized for each wafer even when a manufacturing error occurs for each wafer and the chip arrangement position is displaced for each wafer. be able to.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the method of the present invention is applied to a method for measuring a semiconductor wafer chip will be described below with reference to the drawings.

In FIGS. 1A and 1B, the wafer 1
The XY stage 16 provided with the mounting table 15 for sucking the 4 by vacuum pressure has the XY having the X-axis and Y-axis drive motors 18.
It can be moved two-dimensionally by the stage drive device 6.

The laser light irradiation device 7 includes a laser light source 17
The laser light emitted from the XY stage 1 is bent by the reflection plate 13 through the laser light selector 11 '.
The surface of the wafer 14 on 6 is irradiated.

In the above, the laser beam applied to the surface of the wafer 14 on the XY stage 16 is the XY stage 1.
Along with the movement of 6, both the special chip and the pattern chip are irradiated. The scattered light that is reflected from the surface is condensed through the lens system 12 that constitutes the light receiving device 8 and reaches the photoelectric element 11.

The photoelectric signal captured by the photoelectric element 11 is amplified by the amplifier 10 to a predetermined amount and applied to the A / D converter 9. The digital signals D ₁ and D ₂ output from the A / D converter 9 are assumed to be proportional to the intensity or amount of scattered light with which the wafer 14 is irradiated.

The digital signals D ₁ and D ₂ are selected by the laser light selector 11 ', and after irradiating the surface of the wafer 14 with each slit light or spot light, the reflected light is condensed on the photoelectric element 11 and each wafer. It is converted into a signal corresponding to the pattern above 14.

The digital signal D ₁ is supplied to the XY stage 16
On the other hand, it is a digital signal for automatic correction by rotating the wafer 14 left and right in the circumferential direction θ. Also digital signal D
₂ is a digital signal for detecting the pattern of the special chip arranged on the wafer surface.

C based on the digital signals D ₁ and D ₂
Calculation is performed by PU1, and the wafer 14 is moved to a predetermined position by the XY stage drive device 6 according to the result. The digital signal D ₂ is a program for first recording the reference data 3 in the memory device, and then recording the pattern data 4 searched for the pattern chips around the special chip arranged on the surface of the wafer 14 in the memory device. Has been done.

The above-mentioned reference data 3 is pattern data of a normal chip and is recorded in the storage device. The pattern data 4 is pattern data around the special chip.

The means for detecting the position of the center point of the wafer will be described. As shown in FIG. 2A, the capacitance type height sensor 20 is positioned on the upper side, and the mounting table 15 on which the wafer 14 is adsorbed is moved in the arrow direction. The boundary points 21 and 23 when moving from the wafer mounting surface to the wafer surface, the boundary points 22 and 24 when moving from the wafer surface to the wafer mounting surface, and the lengths Lx and Ly of the respective chords are set to the CPU 1. Enter the C
The intersection point 0 of the midpoints of the lengths of the respective chords is detected by the PU 1 as the center point position 25 of the wafer and recorded in the storage device.

Next, the operation will be described with reference to FIGS. 5 and 6.

Generally, there are two types of methods when forming pattern chips on the surface of the wafer 14.

The first is a method in which the entire surface of the wafer is baked at once, and the manufacturing method is a method in which a mask plate is printed on the surface of the wafer with pattern chips. As shown in FIG. 5, the characteristic feature of the obtained wafer is that pattern chips are formed over the entire surface of the wafer 14, but one or more chips used as mask aligner targets are present in the chips. ing. A wafer including such an aligner target chip is called an aligner target chip wafer.

The second method is a method in which the pattern dimension of the wafer becomes finer and finer, and one or a plurality of patterns are repeatedly printed on the entire surface of the wafer without printing them all at once. The characteristics of this wafer are as shown in FIG.
The pattern chips 28 are repeatedly printed on the circular wafer 14, but the areas where the chip area is insufficient are not printed, and thus remain as the wafer base 27. A wafer having the wafer ground 27 in this way is called a stepper type wafer.

In the former wafer, FIGS. 3 and 5 show the case where the aligner target is a special chip.
This will be described with reference to the figure. First, in the wafer prober in the wafer test process, the wafer storage box is arranged at the place 104 where the wafer storage box is set, the wafer 14 is transferred from the wafer storage box to the mounting table 15 by a transfer device, and the position where the wafer 14 is attracted to the mounting table 15 The mounting table 15 is moved from 100 to the alignment position 101 by driving the XY stage. Next, the center point 25 of the wafer 14 is detected and recorded in the storage device. In this case, the XY stage 16 moves according to preset movement amount data 2, and a predetermined position on the surface of the wafer 14 is irradiated with laser light there. After that, the mounting table 15 is moved again by driving the XY stage, and the wafer 14 is stored in the wafer storage box.

Regarding the operation for searching the base point position on the wafer at the alignment position, for example, as shown in FIG. 2, since the center point position 25 of the wafer 14 has already been detected and recorded, it is located to the left of the center point. It is also preset that the special chip is arranged at a position moved by 3 pitches. Therefore, as shown in FIG. 5, the special chip 26 and the pattern chips in the periphery are connected to "L.M.
Laser light is irradiated in the order of "N", "IJK", and "FGH".

Positioning of each position on the wafer 14 for irradiating the laser beam can be easily performed because the chip size is predetermined. That is, when the length of one chip from the center point position 25 of the wafer 14 is one pitch,
To irradiate the laser beam on the "L, M, N" row, 2
Irradiation becomes possible by moving the mounting table 15 by the pitch. Next, in order to irradiate the laser light to the "I, J, K" rows, the mounting table 15 for 3 pitches from the center point position 25 is used.
To move. Similarly, in the “F / G / H” row, it is possible to irradiate the laser light by moving the mounting table 15 by 4 pitches from the center point position 25.

The scattered light or the like generated by the above laser light irradiation is automatically detected by the photoelectric element of the light receiving device at the spot for detecting the pattern of each chip, and the obtained digital signal D is obtained.
₂ is read by the CPU 1 and recorded in the storage device. At this time, a photoelectric signal that does not have a large average value in the area where the normal chip is formed and has a maximum value when the special chip 26 is a mirror surface is generated.

As described above, the laser light is emitted from the special chip 26 and the peripheral chips "L, M, N", "I, J, K",
The laser beam is irradiated while moving in the order of “F / G / H” at every pitch. By the irradiation, the special chip 26 is recognized by being compared with the reference data stored in advance. Therefore, the position of the special chip 26 can be set as the relative origin of the wafer map.

In the latter wafer 14, as shown in FIG. 6, the mirror area of the peripheral portion of the wafer when printed by a stepper is used as a special area 27, and this special area 27 is used.
Can be regarded as the special chip described above. Therefore, this special area portion 27 can be used as a relative origin on the memory map.

The concept of the special chip 26 described above will be explained by introducing it to the special area section 27. After the center of the wafer 14 is detected and recorded in the storage device as described above, X-
The Y stage is moved by a predetermined set movement amount, and the periphery of the special area portion 27 is irradiated with laser light. The special area portion 27 is located at a position which is moved by 4 pitches on the left side in the X axis direction and 3 pitches on the lower side in the Y axis direction from the so-called wafer center point position 25.
Is assumed to exist, laser light is irradiated in the order of "fghi".

“Fh i” is a normal pattern chip, and after recognizing that “g” is a special area pattern by the method described above, the special area pattern of “g” is recognized as a special chip. .

Next, in the same manner as described above, the special chip is compared with the reference data previously recorded in the storage device and recognized, and in this case, the pattern distribution of "f.g.h.i" is determined. You have to recognize that it is as decided. That is, the base points of all the wafers are set as the same origin with the special chip of the wafer as the base point, and the chip coordinates of all the wafers are aligned.

The alignment means described above can also be applied to the next embodiment.

In a general wafer test process, if the chip is defective based on the measurement result of each chip, a defect mark is attached by an inker (marker). Conventionally, ink is scattered at this time, and other non-defective non-defective chips become defective chips.

However, according to the above-described embodiment, a clear special pattern (base point) is provided on the wafer 14, and the base point position is set as the origin of the memory map. Even if it is not attached, it is recorded as map data based on the coordinates corresponding to the measurement result of each chip. Then, even without marking, by reading the map data of the wafer in the next step (die bonding step) after measuring the wafer, recognizing the special pattern, and aligning the semiconductor wafer chip with this pattern as the origin, It can be used to automatically sort out defective chips and non-defective chips in the next step. In the so-called wafer test process, by outputting the map data including the base point coordinates, it is not necessary to install an inker (marker) on the measurement wafer prober, and the ink is not harmful to the wafer.

[0038]

In the manufacture of semiconductor chips on a semiconductor wafer, a manufacturing error occurs for each wafer. In this way, even when the chip array position is displaced for each wafer, the position of the special pattern provided on each wafer can be automatically recognized for each wafer.

Furthermore, the coordinate position of the semiconductor wafer chip can be aligned by recognizing the special pattern formed on the wafer.

[0040]

[Brief description of drawings]

1A and 1B are block diagrams showing an embodiment of the method of the present invention.

2A and 2B are a cross-sectional view and a plan view showing a process of detecting the center point position of the wafer shown in FIG.

FIG. 3 is a plan view showing the trajectory of the wafer 14 in FIG.

FIG. 4 is a plan view of a wafer showing a “deviation” during manufacturing with a mask.

5A and 5B are plan views showing a process of detecting a special chip provided on the wafer of FIG. 1, respectively.

6A and 6B are plan views showing a process of detecting a special chip provided on the wafer shown in FIG. 1, respectively.

[Explanation of symbols]

 11 Photoelectric Element 11 'Laser Light Selector 12 Lens System 13 Reflector 14 Wafer 15 Mounting Table 16 XY Stage 17 Laser Light Source 18 Drive Motor

Claims (1)

[Claims] 1. A step of obtaining a center of a semiconductor wafer, a step of reading a special pattern position of the semiconductor wafer from a memory in which coordinates from the center to a predetermined special pattern are stored, the special pattern and the special pattern. A method for recognizing a special pattern position of a semiconductor wafer, comprising: a step of optically detecting a regular chip pattern around the pattern; and a step of recognizing the position of the special pattern based on the data obtained in this step.