JPH0834240B2 - Alignment device - Google Patents

Description

The present invention relates to an alignment apparatus, and is particularly suitable for application to a semiconductor wafer inspection apparatus.

[Outline of Invention]

According to the present invention, in an alignment device, a positioning target is illuminated by a parallel light beam, and specularly reflected light can be selectively formed on the image recognition means. It is possible to easily realize an alignment device that can be detected and that can position an object to be positioned with sufficient accuracy for practical use.

[Conventional technology]

As an alignment device used for a semiconductor wafer inspection device such as a so-called prober, various types of an open loop system having no position detecting mechanism and a feed back system having a position detecting mechanism are known.

Some of the feed back type alignment devices have an image processing system as a position detecting mechanism. This is to illuminate a semiconductor wafer, which is a positioning target placed on a table that can freely move in parallel and rotationally in the XY plane, with illumination light obtained from a diffused light source, and reflect the reflected light with, for example, a linear light. The position of a component such as a scribe line or a bonding pad formed on the surface of the semiconductor wafer is detected by the image recognition means composed of an array sensor, and the table is driven to position the semiconductor wafer based on the detection result. Has been done.

In practice, the semiconductor wafer has a linear orientation flat W1 formed on a part of the outer peripheral portion of the semiconductor wafer W, as shown in a partially enlarged view in FIG. With the X-axis as a direction along the orientation flat W1 and the Y-axis as a direction perpendicular to the orientation flat W1, the position on the semiconductor wafer W can be represented by XY orthogonal coordinates. There is.

Thus, each chip is formed on the semiconductor wafer W.
The IC circuit section W2 is divided by a scribe line W3 extending in the X direction and the Y direction at a predetermined interval, and a bonding pad (not shown) can be expressed by XY coordinates.

[Problems to be solved by the invention]

However, when the semiconductor wafer W is illuminated with a diffused light source and an image of the surface thereof is formed on the image recognition means, the constituent elements on the surface of the semiconductor wafer W, such as the IC circuit section W2, and the IC circuit section W2 are There is a problem that the difference in luminous intensity between the divided scribe lines W3 or the wire bonding pad becomes small, making it practically difficult to detect the position of the semiconductor wafer from the detection information of the image recognition means.

The present invention has been made in consideration of the above points, and it is necessary to maximize the difference in luminous intensity between the reflected light obtained from the IC circuit portion on the semiconductor wafer and the reflected light obtained from the scribe line or the wire bonding pad. Therefore, an attempt is made to propose an alignment apparatus that can position a semiconductor wafer with sufficient accuracy in practical use.

[Means for solving problems]

In order to solve such a problem, in the present invention, a scribe on the surface of the substrate 7 having a plurality of pattern areas 7A in which a circuit pattern is formed and a linear scribe line 7B separating the plurality of pattern areas 7A from each other. Line 7B
In the alignment apparatus 1 for detecting the position of the substrate 7 by detecting the position of the substrate 7 and illuminating a part of the substrate 7 with the parallel light flux,
3, 4, 5) and the irregular reflection light RA generated from the pattern area 7A on the substrate 7 illuminated by the parallel light flux and the specular reflection light RB mainly generated from the scribe line 7B are separated, and the specular reflection light RB
And a light separation means (8, 9) for selectively transmitting the light and a linear light receiving surface, and an image of a specific scribe line 7B on the substrate 7 is connected to the linear light receiving surface. The specific scribe line 7B is arranged so as to form an image, and when the parallel light flux irradiates a part of the substrate 7, the scribe line 7B of the regular reflection light RB selected by the light separating means (8, 9). An image recognition means 10 for picking up an image, and a signal processing means 11 for detecting the position of the specific scribe line 7B with respect to the linear light receiving surface based on the image information obtained by the image recognition means 10 are provided. Based on the detected position information obtained by the processing means 11, the substrate 7 is positioned at a predetermined reference position.

[Action]

The parallel luminous flux formed by the illumination means (2, 3, 4, 5) illuminates the substrate 7. Of the reflected light R reflected on the substrate 7, only the specular reflected light RB is selectively separated by the light separating means (8, 9), and thus the image of the constituent element of the image of the substrate 7 which generates the specular reflected light RB. Is imaged on the image recognition means 10 with a large light intensity difference as compared with the image of the component that produces the diffusely reflected light RA. This facilitates the position detection of the substrate 7.

Thus, the position of the substrate 7 can be detected with a simple structure, and an alignment apparatus that can position the substrate 7 with sufficient accuracy for practical use can be easily realized.

Embodiment An embodiment in which the present invention is applied to a semiconductor wafer inspection apparatus will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an alignment apparatus as a whole, and light emitted from a light source 2 is collected on a pinhole 4 by a condenser lens 3. Cylindrical lens group 5 consisting of two cylindrical lenses whose axes are orthogonal to each other
Is the beam splitter 6 that emits the light emitted from the pinhole 4.
The image is formed on the semiconductor wafer 7 as a flat illumination spot LS formed by a slit-like parallel light flux extending in the X direction as shown in FIG.

Illumination spot reflected on the surface of the semiconductor wafer 7.
The LS enters the objective lens 8 as reflected light R. A pinhole 9 is arranged on the optical axis on the exit side of the objective lens 8 at a focal distance f, and the reflected light R enters the linear array sensor 10 through the pinhole 9.

The linear array sensor 10 is composed of a row of photoelectric conversion elements that convert light of one pixel into an electric signal. By electrically scanning the photoelectric conversion element row, an output indicating the arrangement of the constituent elements on the semiconductor wafer 7 is output. A current I is obtained. The output current I obtained in the linear array sensor 10 is sent to the control circuit 11, and the control circuit 11 calculates the semiconductor wafer 7 from the preset position of the semiconductor wafer 7 and the output current I.
Calculate the deviation from the position.

The semiconductor wafer 7 is placed on the table 12, and its position is represented by XY orthogonal coordinates. Table 12 is second
As shown in the figure, the table 12 can be moved in parallel in the X and Y directions and can be rotated in the XY plane, and the control circuit 11 sends a drive signal corresponding to the calculation result to the table 12 so that the table 12 can be moved. By driving, the semiconductor wafer 7 is positioned.

In the alignment apparatus 1 having such a configuration, when the illumination spot LS is imaged on the semiconductor wafer 7 in which the scribe lines 7B are formed in a grid pattern so as to divide the IC circuit portion 7A as shown in FIG. Since the circuit pattern on the IC circuit portion 7A is composed of a surface that is significantly rougher than the surface of the scribe line 7B, the reflected light RA reflected by the IC circuit portion 7A becomes irregularly reflected light. On the other hand, the reflected light RB reflected on the scribe line 7B is almost regular reflected light.

Therefore, most of the diffusely reflected light RA cannot pass through the pinhole 9 and is blocked, whereas the specularly reflected light RB is blocked by the objective lens 8.
Then, the light is incident on the pinhole 9 in parallel with the optical axis thereof, and is focused on the pinhole 9, and most of the light passes through the pinhole 9. As a result, the linear array sensor 10 is formed so that an image in which the scribe line 7B projected on the semiconductor wafer 7 by the regular reflection light RB is emphasized has a positional relationship such that the image intersects the linear sensor array 10. Will be imaged, linear array sensor
The output current I obtained from 10 is a signal of the output current I _B corresponding to the scribe line 7B as compared with the output current I _A corresponding to the IC circuit portion 7A, as shown by the solid line in FIG. 3 (A). The level is dramatically increased.

Therefore, the position of the scribe line 7B in the X direction can be easily detected by setting an appropriate threshold level I _sh .

For example, as shown in FIG. 2, when the mounting position of the semiconductor wafer 7 on the table 12 is rotated and the scribe line 7B does not coincide with the X axis or the Y axis,
When the position on the semiconductor wafer 7 illuminated by the illumination spot LS is changed by driving the table 12 in the negative Y direction, the rising portion of the output current I obtained from the linear array sensor 10 becomes
In FIG. 3 (A), the position changes from the position indicated by the solid line to the position indicated by the broken line in the X direction. Therefore, the rotation amount of the semiconductor wafer 7 can be calculated from the movement distance in the Y direction at this time and the movement amount of the detected position of the scribe line 7B in the X direction. 12
Can be rotationally driven to correct the rotation of the mounting position of the semiconductor wafer 7.

Further, since the position of the scribe line 7B on the semiconductor wafer 7 in the Y direction can be detected as described above, the control circuit 11 can drive the table 12 in the X direction to correct the position of the semiconductor wafer 7 in the X direction.

Further, by driving the table 12 in the Y direction and observing a change in the total sum of the output currents I of all the pixels of the linear array sensor 10 (this is called the output current sum) IS,
As shown in FIG. 3 (B), the output current sum IS _B when the lighting spot LS crosses the scribe line 7B is the IC circuit section 7
Since the output current sum IS _A across A is remarkably large, the position of the semiconductor wafer 7 in the Y direction can be easily detected by setting an appropriate threshold level IS _sh. . Therefore, the control circuit 11 can drive the table 12 in the Y direction to correct the position of the semiconductor wafer 7 in the Y direction.

Thus, regardless of the position of the semiconductor wafer 7, the semiconductor wafer 7 can be reliably positioned at a predetermined position.

According to the above-described embodiment, it is possible to easily realize the alignment device that can detect the position of the positioning target with a simple configuration and can position the positioning target with practically sufficient accuracy.

In the above-described embodiment, the slit-shaped illumination spot LS formed by the cylindrical lens group 5 is configured to irradiate the linear array sensor 10, but instead of this, a circular illumination spot formed by a collimator lens and A two-dimensional array sensor may be used, and a laser may be used as the light source. In short, it suffices that the semiconductor wafer 7 can be illuminated by the parallel light flux.

Further, in the above-mentioned embodiment, the objective lens 8 and the pinhole 9 are used as means for selectively forming the image on the image recognition means through the regular reflection light, but the present invention is not limited to this, and other configurations may be used. Is also good.

Further, in the above description, the array sensor is used as the image recognition means, but the present invention is not limited to this, and the position detection may be performed by obtaining a video signal with a television camera and analyzing the video signal. The same effect as described above can be obtained.

Further, in the above-mentioned embodiment, only the IC circuit section 7A and the scribe line 7B are the constituent elements on the semiconductor wafer 7, but in addition to this, even if the position of the wire bonding pad is detected, The same effect can be obtained.

Further, in the above description, the embodiment in which the present invention is applied to the semiconductor wafer inspection apparatus has been described, but the present invention is not limited to this and can be applied to various devices.

〔The invention's effect〕

As described above, according to the present invention, it is possible to easily perform position detection with a simple configuration, and it is possible to easily realize an alignment device that can perform positioning with practically sufficient accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an alignment apparatus according to the present invention, FIG. 2 is a schematic diagram showing a positional relationship between an illumination spot LS and a semiconductor wafer, and FIG. 3 is an output current of a linear array sensor and a semiconductor. FIG. 4 is a schematic signal waveform diagram showing the relationship with the surface shape of the wafer, and FIG. 4 is a schematic diagram showing the relationship between the components on the surface of the semiconductor wafer and the orientation flat. 1 ... Alignment device, 2 ... Light source, 5 ... Cylindrical lens group, 7 ... Semiconductor wafer, 8 ... Objective lens, 9 ... Pinhole, 10 ... Linear array sensor, 12
…… Table, LS …… Lighting spot.

Claims (3)

[Claims] 1. A substrate by detecting the scribe line on a surface of a substrate having a plurality of pattern regions in which a circuit pattern is formed and a linear scribe line separating the plurality of pattern regions from each other. In the alignment apparatus for detecting the position of the substrate and positioning the substrate, illuminating means for illuminating a part of the substrate with a parallel light beam, and diffuse reflection light generated from the pattern area on the substrate illuminated with the parallel light beam and the A light separating unit that separates specularly reflected light mainly generated from the scribe line and selectively transmits the specularly reflected light, and a linear light receiving surface, and an image of a specific scribe line on the substrate is The specific scribe line is arranged so as to form an image in a relationship intersecting with a linear light-receiving surface, and the parallel light flux is part of the substrate. Image recognition means for picking up an image of the scribe line by the specular reflection light selected by the light separation means when illuminating, and the straight line based on the image information obtained by the image recognition means. A signal processing means for detecting a position of the specific scribe line with respect to a light receiving surface of a circular shape, and positioning the substrate at a predetermined reference position based on detection position information obtained by the signal processing means. Alignment device. 2. A moving means for placing and moving the substrate, wherein the signal processing means is arranged so that the image of the specific scribe line intersects the linear light receiving surface. Is arranged, the relative position of the specific slive line and the linear light receiving surface is changed by the moving means, and the specific position is determined based on the changing image information obtained on the light receiving surface. The alignment device according to claim 1, wherein the position of the scribe line is detected. 3. The light separating means has a lens system, and an aperture member having a minute aperture at a focal position on the optical axis of the lens system opposite to the substrate with respect to the lens system. The alignment device according to claim 1.