JPS6317226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor wafer, and particularly to a semiconductor wafer with integrated transistors.

In a monolithic integrated circuit, which incorporates a large number of semiconductor devices on a single semiconductor wafer, all of the devices have a planar structure.

The above semiconductor device is manufactured by selectively diffusing impurities, forming a contact window in the surface oxide film, forming an insulating protective film to protect the surface of the semiconductor for electrical wiring between semiconductor elements, and finally by forming a lead wire. It is formed through a process such as exposing the wiring only in the bonding pad portion for extraction.

Through the above steps, a large number of semiconductor devices having certain circuit functions, usually called chips, are formed on the semiconductor wafer.

In order to assemble these chips, there is a wafer probing process to check whether the chips meet predetermined circuit characteristic standards before being separated at scribe lines.

That is, this is a process of inspecting how many non-defective chips there are on the wafer. In this process, a group of measurement probes called probes is brought into contact with a group of bonding electrodes on the chip, and an electrical signal is input to the semiconductor wafer through the probe group to test the electrical characteristics of the device. This is repeated for all chips.

By the way, the size of the bonding pad part is 100
~150μ, and the size of the tip of the probe is less than a few tens of micrometers, so in the wafer probing process, the bonding pads of all chips on the wafer and the probe need precise positional alignment with each other. Needless to say.

Therefore, before inspection, the work to ensure the positional consistency of the probe and the bonding pads on all chips on the wafer is usually called needle alignment, and requires considerable skill and time, and it is difficult to improve the efficiency of the autoprobing process. This was a factor that prevented improvement.

For the above reasons, there has been a strong demand in recent years in the industry to automate the needle alignment work in the autoprobing process, and in order to meet this demand, automatic probe devices (usually called autoprobers) have appeared in recent years. ing.

The autoprober has a stage on which a semiconductor wafer is placed and a mechanism for rotating this stage,
In addition, after placing the semiconductor wafer on the stage and aligning the direction of the scribe line (line for dividing chips) on the semiconductor wafer with the direction of movement of the stage, there is a mechanism for intermittently feeding one chip at a time, and a mechanism for intermittently feeding one chip at a time. In order to make contact between the probe group and the electrode group (pad) of the semiconductor wafer, it has a mechanism for pushing the semiconductor wafer up to the top where the probe group is fixed. In the mechanism for matching the direction of the scribe line with the moving direction of the stage, as shown in FIG. The direction of the scribe line on the wafer is determined by reflecting and irradiating the wafer, condensing the reflected light 7 or 8 at the condenser 6, and measuring its intensity at the light receiving section 4. Some devices have a mechanism that rotates the stage to match the direction of movement of the stage and the direction of the scribe line.

The method of determining the direction of the scribe line is that the light irradiated on an uneven surface is diffusely reflected and a large proportion of the light reaches the light receiving part through the optical path 7, but the light irradiated onto a mirror surface passes through the optical path 8. This is done by determining the unevenness of the wafer's surface by utilizing the fact that the light returns to the light emitting part through the light emitting part and reaching the light receiving part is low, and repeating the determination a predetermined number of times at a predetermined location on the wafer.

For this reason, it is necessary to create an area within the wafer in which the uneven area and the mirror-like area both have a predetermined extent or more, and are adjacent to each other through a boundary that can be clearly distinguished from each other. becomes.

For the above reasons, immediately after the introduction of this autoprober, as shown in Figures 2 and 3,
A region having the surface of the metal wiring layer 11 was considered as a place for scattering light on the wafer, and an exposed scribe region 12 of the silicon substrate existing between adjacent chips was considered as a mirror-like surface.

However, this method has the following problems.

(1) Depending on the product, needle alignment may not be possible automatically.

(2) Even if the product is manufactured using (1), depending on the wafer production lot, there may be products that cannot be automatically aligned.
There are many things that can be missed.

As a result of the investigation, it was found that the former problem is because the planar shape of the metal wiring layer is so fine and complex that the prober cannot recognize where the scribe line is on the wafer, and the latter problem is due to the surface condition of the metal wiring layer being uneven. This is because wafers with a relatively low scattering degree may not be able to be aligned or may be inaccurate.

However, in recent years, the element density of semiconductor devices such as ICs and LSIs has been increasing, and the complexity of the planar shape of the metal wiring layer near the scribe lines has been increasing. Attempting to improve the processing software would require a huge amount of time and effort, and the time required for automatic alignment of the probe and wafer would significantly increase, making production in the wafer probing process difficult. This method cannot be adopted because it results in a decrease in performance and an adverse effect on the manufacturing cost of the semiconductor device.

Further, the variation in the surface condition of the metal wiring layer, which is the cause of the latter problem, is difficult to solve with current semiconductor device manufacturing technology because a large number of semiconductor wafers are processed in actual mass production of semiconductor devices.

As a result of intensive research, the present invention has solved the above-mentioned problems related to automatic needle alignment work in the wafer probing process using an autoprober, and is a novel semiconductor that can perform the above-mentioned work accurately, stably, and in a short time. It provides the structure of the device.

A feature of the present invention is that a target pattern is formed in at least two of a large number of regions partitioned into a matrix by scribe lines without forming a semiconductor chip, and each target pattern is formed on the surface of a silicon substrate or A first region of a flat surface with a rectangular planar shape consisting of the surface of a dielectric layer on the surface of a silicon substrate, and a polycrystalline silicon layer surrounding the first region in one direction only. and a second region of the surface of the semiconductor wafer having an uneven surface formed by a periodic pattern in which a large number of linearly extending filaments are arranged in a periodic manner. The first and second like this
Since there is generally no wiring pattern with the surface shape of the region, there is no possibility of misidentifying the target pattern and the wiring pattern. Further, in alignment not only by laser but also by image processing, the target pattern in which the flat first area is surrounded by the uneven second area is easily visible, improving work efficiency. Furthermore, since polycrystalline silicon can be patterned more sharply than general metals, unevenness with a predetermined interval can be obtained with high accuracy, which makes alignment in laser processing more accurate and alignment in image processing easier.

Embodiments of the present invention will be described in detail below with reference to the drawings. 4 to 6 show a first embodiment according to the present invention.

Target 1 for autoprober according to this embodiment
In the structure of 4, a polycrystalline silicon thin layer 15 having a striped planar shape with a width of several to several tens of μw as shown in FIG. In the region 20 surrounded by 21 the thin layer 15 is removed to expose the silicon surface 10'. According to the target 14 according to this embodiment, since the polycrystalline silicon thin layer is left in a striped manner in the region 21, the surface has an ideal uneven state as shown in FIG. 5, and the laser beam is extremely effective. Scattered. Furthermore, since the silicon substrate surface in region 20 has an optical mirror surface,
The laser light is not scattered at all.

Therefore, by scanning the laser beam across the target 14 in the order of regions 21→20→21 and measuring the reflected light, an extremely stable difference in light intensity, ie, contrast, can be obtained. Therefore, by setting the planar dimensions of each area to a predetermined value or more, it is extremely easy to distinguish them from the metal wiring 11 and scribe area 12 on a normal chip 13. This is because, on a normal chip, the area where the wafer surface is mirror-like due to exposure of the silicon substrate usually extends by several tens of microns at most.

As a result of the prototype test, in this example, the area 20 is a square with a side of 200 μm, and the area 2 surrounding the area is
1 was found to be sufficiently distinguishable from ordinary chips if it had a width of 150 μm.

Therefore, the size of the target according to this embodiment is a square of approximately 500 μm×500 μm at most. In this embodiment, as shown in FIG. 6, it is proposed to insert the targets 14 at two predetermined positions on the left and right sides of the silicon wafer.

This is because when there is only one target on the wafer, during the needle alignment process, it is necessary to adjust the rotation of the stage 1 to align the direction of the scribe line 12 on the wafer with the direction of movement of the stage 1, that is, to align the wafer. This is because it is impossible to perform needle alignment for all chips on the wafer.

As described above, in the first embodiment of the present invention, the targets 14 for the wafer probing process are formed at two locations on the semiconductor wafer in addition to the usual chips on the silicon wafer, thereby achieving automatic needle alignment of the autoprober compared to the conventional method. It is much more stable and can be done in a shorter time than .

Next, a second embodiment of the present invention will be described. As shown in FIGS. 7 to 9, the target 14' for an autoprober according to this embodiment has a silicon oxide film 1 of uniform thickness on a silicon substrate surface 10'.
8 is formed, and polycrystalline silicon 15 having a striped planar shape with a width of several to several tens of microns is deposited in a region 21' on the film 18, and a polycrystalline silicon 15 is deposited in a region 21' surrounded by the region 21'. The silicon thin layer 15 is completely removed and the silicon oxide layer 15 is exposed over the entire area.

As can be easily seen from this embodiment, the only difference from the first embodiment is that a silicon oxide film is formed on the silicon substrate surface 10' over the entire target section 14' for the autoprober, and other conditions such as This embodiment is the same as the first embodiment in that the shapes and dimensions of the regions 20 and 20' and 21 and 21' are inserted at two positions on the left and right sides of the wafer. It has been demonstrated that the second embodiment of the target 14' has the same effect on autoprober needle alignment as the first embodiment.

Furthermore, in the second embodiment, the same effect can be expected even if another dielectric thin film such as a silicon nitride film is used in place of the silicon oxide film 15.

The semiconductor device according to the present invention as described above can be fully realized with the current technology, and provides a semiconductor device that significantly improves productivity in the wafer probing process, which occupies an important position in the semiconductor device manufacturing process, compared to the conventional one. can do.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing an autoprober, FIGS. 2 and 3 are a plan view and a cross-sectional view showing the vicinity of the scribe area of a semiconductor wafer,
4 and 5 are a plan view and a sectional view thereof showing a target according to a first embodiment of the present invention, and FIGS. 7 and 8 are a plan view and a sectional view thereof showing a target according to a second embodiment of the present invention. Its cross-sectional view, No. 6
9 and 9 are top views of semiconductor wafers containing first and second targets according to the present invention. In the figure, 1... stage, 2... semiconductor wafer, 3... laser emission source, 4... light receiving section, 5, 5'... laser reflecting mirror, 6... condensing section,
7, 8... Laser reflection optical path, 10... Silicon substrate, 10'... Silicon substrate surface, 12... Scribe region, 13... Chip, 14, 14'...
Target for autoprober, 15... polycrystalline silicon thin layer, 18... silicon oxide film, 20...
...A region where the silicon substrate is exposed, 20'...
Areas where silicon oxide is exposed, 21, 21'
...A region where a polycrystalline silicon pattern having a striped planar shape is formed.

Claims (1)

[Claims] 1 A target pattern is formed in at least two of a large number of regions partitioned into a matrix by scribe lines without forming a semiconductor chip, and each target pattern is formed on the surface of a silicon substrate or on the surface of a silicon substrate. A first region of a flat surface made of the dielectric layer surface and having a rectangular planar shape, and a polycrystalline silicon layer surrounding the first region and extending linearly in only one direction. 1. A semiconductor wafer comprising: a second region of a surface having concavities and convexities formed by a periodic pattern formed by periodically arranging a large number of filaments.