JPS60153138A - Wafer alignment mechanism of automatic prober - Google Patents

Abstract

PURPOSE:To enable the parallel lead-out working of chips in the direction of arrangement and that of a stage in the direction of movement to be performed accurately and easily by a method wherein the light source illuminating a wafer performing linear movement is reduced to a spot form. CONSTITUTION:The light source when a wafer pattern 2 on the reciprocating stage 1 is visually observed by means of a microscope and the like in order to attain theta=0 deg. is reduced to a spot form and then put into selective illumination to an extremely small region on the wafer (e.g. small to a degree that one chip of semiconductor devices formed within the wafer is included), or into irradiation of the region with a stronger light than of the other region. Focalization of this illuminated region allows no deterioration in alignment accuracy due to the blur of the tip of a probe 3. In other words, adjustment to theta=0 deg. can be made while a flow of the chip pattern linearly reciprocating within the illuminated region is observed whether to have components in the upper and lower directions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a blow μ alignment mechanism for evaluating the electrical characteristics of a semiconductor device formed on a semiconductor wafer.

[Background technology]

Electrical measurements of semiconductor devices repeatedly formed in large numbers on a semiconductor wafer are carried out by fixing the wafer 12 on a stage II movable in the x, Y, and Z directions as shown in FIG. This is done by making contact. After measuring one chip, lower the stage, release the probe, move it in the X or Y direction by the length of the chip's repetition period, and then raise the stage again in two directions.
Start measurement of the next chip IJfl. When there are a large number of chips on a wafer, it takes a huge amount of time to manually repeat measurement, stage movement, and measurement, and it also means that all chips are not measured, resulting in incomplete chips. Mistakes such as this are likely to occur. Therefore, a series of these operations is performed by controlling the blow μ stage, drive circuit, and d+++ constant meter by a controller as shown in FIG. 1, and measurements are automatically performed one after another. In this case, the horizontal movement of the stage is in the X and Y directions in the figure, so if the chip arrangement direction is not accurately aligned to the The probe may be misaligned from the conductive pad, causing measurement errors and even damaging the semiconductor device with the probe.

Therefore, in order to accurately align the chip arrangement direction with the moving direction of the stage before measurement, the stage is usually reciprocated in the X or Y direction, and the stage is rotated around the Z axis while following the pattern on the wafer as it appears to flow. Rotate to align.

) For example, as shown in FIG. 2 (), suppose that the chip arrangement direction is rotated by θ with respect to the stage movement direction. X
When the wafer is reciprocating in the direction, the pattern moves from top to bottom as the wafer moves from left to right when viewed in the field of view 21 surrounded by dotted lines. It can be determined that the parallelization of the two has been achieved.

However, since the work of setting θ-0 during this reciprocating movement is performed while following a pattern flowing within the field of view, it takes a long time to set θ-0 accurately compared to a car. This problem becomes even more pronounced when processing a large number of wafers.

In addition, the process of setting θ-0 is actually done by observing the wafer moving back and forth with the tip of the probe as the aim, and when the pattern passing through the tip of the probe no longer moves in the vertical direction, the wafer is set to θ-0°.
I judge that.

However, at this time, the distance between the reciprocating wafer surface and the tip of the probe is usually several hundred micrometers or more for safety reasons. Therefore, with a microscope etc., 1lAill! When performing the operation from iL to θ-q, it is not possible to focus on both the needle tip and the wafer surface at the same time.

That is, either the pattern on the wafer surface or the tip of the probe, or both, are out of focus within the field of view and become blurred, making it difficult to accurately determine θ=0°.

[Disclosure of the invention]

The present invention solves the above-mentioned problems and provides a method for accurately and easily aligning the chip arrangement direction and the stage movement direction.

[Configuration and action]

In other words, in order to achieve θ-〇0, the light source used to visually observe the wafer pattern on a reciprocating stage using a microscope or the like is narrowed down to a spot, and a very small area on the wafer (e.g. approximately the area formed within the wafer) is focused. selectively illuminate only the area (large enough to include one chip of a semiconductor device) or irradiate it with stronger light than other areas.

If we aim at this illuminated area, the distance between the probe tip and the wafer surface is large (because of the difference, θ=
There is no possibility that the tip of the probe aimed at θ° becomes blurred and the alignment accuracy deteriorates.

In other words, it is possible to adjust θ=08 without checking whether the flow of the chip pattern that is linearly reciprocating within the illuminated area has a component in the vertical direction. Since only a field of view with an area of 1 chip at most can be seen brightly without looking at a wide area, the line of sight will not be scattered all over the place during observation and it will be difficult to judge whether θ-0 or not, and the optimal alignment for θ = 0°. states can be achieved accurately and easily.

〔effect〕

The present invention makes it easier and more accurate to align the wafer to the prober, improving work efficiency, and reducing the possibility of chip damage caused by the probe, thereby preventing a drop in chip yield during measurement.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing electrical measurements of a large number of semiconductor devices on a semiconductor wafer, and FIGS. 2(a) and 2(b) are diagrams showing the difference between the stage movement direction and the chip arrangement direction. 21... Wafer chuck 22... Semiconductor wafer 23... Measurement probe 21... Observation field of view 22... Arranged chips 28... Semiconductor wafer FIG. 2 Y

Claims (1)

[Claims] (1) While the stage on which the semiconductor wafer is fixed is linearly reciprocating, the stage is rotated so that one of the array directions of the semiconductor devices repeatedly formed on the wafer is parallel to the linear movement direction of the stage. In an automatic blow μ for performing alignment, a light source illuminating a linearly moving wafer is focused into a spot shape to facilitate the work of aligning one of the semiconductor devices parallel to the linearly moving direction of the stage. Features automatic blow μ wafer alignment mechanism.