WO1997037378A1

WO1997037378A1 - Visual inspection device for wafer bump and height measuring device

Info

Publication number: WO1997037378A1
Application number: PCT/JP1997/001078
Authority: WO
Inventors: Keiji Terada; Shigeyuki Tada; Masato Moriya; Hiroshi Tanaka; Hideyuki Wakai; Takeshi Okamoto
Original assignee: Komatsu Ltd.
Priority date: 1996-04-02
Filing date: 1997-03-28
Publication date: 1997-10-09
Also published as: JPH09275126A

Abstract

A device corrects a positioning error of a wafer with accuracy in a short period of time and performs visual inspection of bumps with accuracy at high speed. In the device, a wafer is positioned in coordinate axes of a predetermined coordinate system. A coordinate position on the coordinate system, to which a measuring visual field should move, is set so that all the bumps on the wafer is imaged by visual means. When the wafer is positioned, a rotating dislocation of the wafer with an origin of coordinates of the coordinate system as the center of rotation is detected. Respective set coordinate positions of the measuring visual field are subjected to rotating conversion as much as the detected rotating dislocation in the coordinate system and are corrected. Further, relative positions and attitudes of the wafer and the visual means are changed so that the measuring visual field is successively moved to the respective corrected coordinate positions.

Description

Description Appearance inspection device and height measurement device for wafer bump

Technical field

The present invention relates to an apparatus for visually inspecting a projection such as a bump electrode on a wafer. Further, the present invention relates to an apparatus for measuring the height of the bump or the like. Background art

As an apparatus for inspecting the appearance of a projection such as a bump electrode on a wafer, there is one disclosed in Japanese Patent Application No. 6-167032.

As shown in Fig. 20, this device consists of a 2D measurement module 31, a wafer movement stage 32, a 3D measurement module 33, and a measurement controller 34. 3 Position the wafer using 1 and the wafer moving stage 3 2, acquire 3D data of the bump shape using the 3D measurement module 3 3, which is a confocal optical system, and estimate the peak height of the bump from the 3D data. Then, the height of the bump is inspected.

Here, the wafer 1 to be inspected is an aggregate of IC chips 2a, 2b ... (see FIG. 21), and each chip has a bump electrode 3 (see FIG. 22) at a predetermined position. ) Is formed. Then, the 3D measurement module 33 captures the surface of the wafer 1 every measurement field of view 4 in a fixed range.

Figures 22 (a) to (d) show the relationship between the measurement field of view 4 and each chip 2, and at least one chip and a part of two or more chips exist in one measurement field of view 4. Are there. In order to inspect all the bumps 3 on the wafer 1, it is necessary to move the measurement visual field 4 of the 3D measurement module 3 3 so as to cover the entire area of the wafer 1.

Such a conventional bump inspection apparatus has the following problems.

(1) Regarding the processing flow

(a) Wafer positioning error and bump position identification In order to inspect the height of the bump 3, it is necessary to specify three-dimensional data near the height peak of the bump 3, and inspect the height of the bump 3 from the data.

Therefore, the XY coordinate position of the bump 3 must be specified in some way from the three-dimensional measurement data of the 3D measurement module 33. In order to specify the position of the bump 3 on the wafer 1, it is necessary to correct the position of the wafer 1, especially the posture 合わせ, in accordance with the direction of the measurement visual field 4 of the 3D measurement module 33.

In this case, as shown in FIG. 21, the 2D measurement module 31 detects feature points on the wafer 1, for example, the positions of the alignment marks M a and M b, so that the Θ direction of the air 1 can be changed. Then, the attitude of the wear 1 is corrected by rotating the wafer moving stage 32 (0 stage) in a direction matching the field of view of the 3D measurement module 33. As a result, the bump position on the XY coordinate system can be specified and inspected.

However, the resolution of the rotation of the 0 stage of the wafer moving stage 32 is limited, and the attitude cannot be completely corrected, and a rotation error Δ Θ as shown in FIG. 21 occurs. That is, a position error does not occur at the chip 2a near the coordinate origin O, but a position error (ΔΔ, ΔΥ) occurs at the chip 2b separated from the coordinate origin O.

The fact that the position error (Δ Χ, Δ Υ) increases as the distance between the chip and the coordinate origin Ο increases means that as the wafer size increases, the position error increases.

Conventionally, in order to solve these problems, the data measured for each bump 3 with different X and Υ coordinate positions was corrected by the position error (Δ Χ, Δ Υ) for the bump coordinate position. The correction process takes a long time.

(b) Judgment for each chip

Inspection results of bump height need to be summarized for each chip. This is because the final decision as to whether the product is good or not is made on a chip-by-chip basis.

Conventionally, the chip 2 is determined to be “good” only when all the bumps 3 in one chip 2 are within the specified height range. However, according to these criteria, if even one bump 3 in one chip 2 is out of the specified height range, all other bumps 3 are in the specified height range. Would be judged as "bad".

However, even if bumps 3 are out of the specified height range, chip 2 with a small number of bumps 3 will often have sufficient electrical contact with all bumps 3 during chip mounting, Not bad. Therefore, a determination method that can accurately perform a chip-by-chip test is desired.

(2) Regarding bump inspection method

(a) Estimation of IC chip surface height

FIG. 23 is a chip side view showing the level of the surface of the IC chip 2. As shown in FIG. 23, the surface of the IC chip 2 has irregularities due to the IC pattern, and is not flat. Therefore, when measuring the height of the bump 3 formed on the surface of the IC chip 2 from the surface of the IC chip, it was not possible to uniquely determine where the reference is made to be the surface of the IC chip.

Also, when the wafer 1 is inclined in the vertical Z direction, the absolute height of the surface of the IC chip 2 is not the same at one end of the IC chip 2 and the other end. It was not possible to uniquely determine whether to use the surface height of the IC chip 2.

For this reason, the height of the bump 3 on the IC chip 2 depends on the set height of the surface of the IC chip 2, which makes it possible to accurately measure the height of the bump 3. could not.

(b) Cobb inspection

Among the defective bumps 3, there are defects called bumps that are formed on bumps 3 as shown in Fig. 24. Due to the presence of bumps 5, sufficient electricity is generated when mounting the IC chip. There is a possibility that no contact can be obtained. Therefore, it is necessary to accurately detect the bump 5 at the time of the inspection and determine that the bump 5 is “defective”.

(c) Extra bump (foreign matter) inspection

As shown in Fig. 25, some of the defective bumps 3 have a defect called extra bump 6, which must also be detected at the time of inspection and judged as "defective". The extra bump (foreign matter) is a bump-like projection formed on the surface of the IC chip 2 where the bump 3 is not originally formed. However, the detection of the extra bump 6 also depends on the set height of the surface of the IC chip 2, and the detection of the extra bump 6 could not be performed accurately.

An apparatus for measuring the height of bumps on a wafer is disclosed in a patent application filed by the present applicant (Japanese Patent Application No. Hei 6-109293). It is publicly known.

That is, this application discloses a three-dimensional shape measuring apparatus to which a confocal optical system is applied.

In this type of three-dimensional shape measurement device, the entire confocal optical system, only the objective lens, or a planar workpiece (eg, wafer) is moved in the vertical direction. In other words, when the 3D measurement module 33 is regarded as the shape measuring device in FIG. 20, by moving the 3D measurement module 33 in the Z direction, the force moving stage 32 is moved in the Z direction. The work is moved relatively to the 3D measurement module 33 by a predetermined distance in the vertical direction.

In this way, while moving the workpiece in the Z direction, the moving position where the amount of light received by the light receiving unit is maximum is set as the height position of the measured object at the light receiving point. Such processing is executed for each light receiving unit arranged in an array.

If the entire object to be measured cannot be measured in one measurement field of view of the 3D measurement module 33, the same processing is executed by switching the measurement field of view.

That is, each movement position on the plane to which the measurement visual field of the 3D measurement module 33 should move is set so that the height of the entire upper surface of the work is measured by the 3D measurement module 33. Then, the measurement visual field is sequentially moved to each of the set plane movement positions, and the work is moved in the Z direction by the above-mentioned predetermined distance relative to the 3D measurement module 33 at each plane movement position. By doing so, the height of each part of the work within the measurement visual field is measured.

However, when the movement in the vertical Z direction and the movement in the plane direction of the measurement visual field are alternately performed within the measurement visual field, the following problems occur.

FIG. 30 is a diagram conceptually showing the state of such movement, and FIG. 31 shows a time chart thereof. Here, the vertical movement of the workpiece is measured by 3D measurement. It is assumed to be performed by moving the Z axis movement mechanism (Z stage) of module 33.

As shown in these figures, in the past, the movement in the Z direction in each measurement field of view N-1, N, and N + 1 was always set to a fixed direction (for example, the downward direction) and measurement was performed (Fig. 3 When moving to the next measurement visual field (arrow c in Fig. 30), be sure to move the Z stage in the direction b (ascending direction) opposite to the fixed direction a when moving to the next measurement field of view. It was necessary to return the 3D measurement module 33 to the initial position.

Here, in general, the time for moving the measurement visual field is shorter than the time for returning the Z position to the initial position. Therefore, as shown in Fig. 31, even if the movement to the next measurement field of view is completed, the Z position cannot be returned to the initial position, and the time required to completely return the Z stage to the Z position is reached. Was wasted time that was not used for the original measurement and for moving the measurement field of view. As a result, the cycle time for one field of view was increased by that much, and the throughput of the device was reduced.

It is conceivable to increase the speed at which the Z stage is returned to the initial position to reduce the dead time. Could not be adopted. Disclosure of the invention

The present invention has been made in view of such a situation, and eliminates all of the above problems, accurately and quickly corrects a wafer positioning error, and accurately performs a bump appearance inspection. The purpose is to perform fast and fast.

In order to achieve this object, in the first invention of the present invention, the relative position and attitude of the wafer and the visual means for imaging the bumps on the wafer are changed by the relative position and attitude changing means. In a wafer bump appearance inspection device that inspects the appearance of bumps on a wafer,

Positioning means for positioning the wafer on a coordinate axis of a predetermined coordinate system by the relative position / posture changing means;

The viewing means has a measurement field of view capable of imaging a plurality of bumps at one time, and is arranged so that all the bumps on the wafer are imaged by the viewing means. Setting means for setting a coordinate position on the coordinate system to which the measurement visual field is to be moved; and when the wafer is positioned by the positioning means, rotation of the wafer about a coordinate origin on the coordinate system as a rotation center Detecting means for detecting a positional shift; and rotating each set coordinate position of the measurement field of view of the visual means set by the setting means on the coordinate system by the rotational position shift detected by the detecting means. Correction means for correcting

Means for driving the relative position / posture changing means so that the measurement field of view of the visual means is sequentially moved to each corrected coordinate position corrected by the correction means.

It is equipped with.

Further, in another invention of the first invention, in addition to the above configuration,

Bump coordinate position setting means for presetting the coordinate position on the coordinate system of each bump included in the measurement field of view,

Inspection means for specifying a bump position in the measurement field of view based on preset coordinate positions set by the bump coordinate position setting means, and performing a visual inspection of bumps on the wafer based on the specified bump positions; and

Is further provided.

According to the first aspect, the position error of the bump due to the rotational position shift of the wafer when positioned by the positioning means is accurately corrected by the rotation conversion in consideration of the moving distance of the measurement visual field from the coordinate origin. Therefore, the conventional problem that the position error of the bump increases as the wafer size increases is solved.

Also, instead of correcting the position error for each bump, the position error is corrected for each measurement field of view including multiple bumps, so the correction process can be completed in a short time and the bump inspection can be performed at high speed. Will be able to do it.

Further, according to a second invention of the present invention, in a wafer bump appearance inspection apparatus for imaging a plurality of bumps on a wafer by visual means and inspecting the appearance of the bumps on the wafer based on the imaging result,

An average height of a plurality of bumps in a chip is determined for each chip on the wafer based on an imaging result of the visual means, and a height of all bumps in the chip is determined with respect to the average height. If the chip is within a certain deviation, the chip is good. The decision is made.

In the second aspect of the invention, the average value of the bump height of the chip 內 is compared with the height of each bump, and the quality of the chip is determined from the result, so that the inspection of each chip can be accurately performed. It can be carried out. Therefore, it is possible to prevent a non-defective chip from which a sufficient electrical contact is obtained in all bumps during chip mounting from being erroneously determined to be defective.

According to a third aspect of the present invention, there is provided visual means for imaging a bump on a wafer with a measurement field of view of a predetermined size, and inspects the appearance of the bump on the wafer based on the imaging result of the visual means. In a wafer bump appearance inspection device,

Positioning means for positioning the wafer on a coordinate axis of a predetermined coordinate system; bump coordinate position setting means for presetting the coordinate positions of the bumps included in the measurement visual field on the coordinate system;

A bump position in the measurement field of view is specified based on a preset coordinate position set by the bump coordinate position setting means, a window is set for a certain area around the specified bump position, and only this window is set. Inspection means for inspecting the appearance of the bumps on the wafer;

It is equipped with.

In the third aspect, the bump detection is performed only in the window portion in a certain area around the bump position, so that the inspection such as the measurement of the bump height can be efficiently performed. In addition, since inspection is performed around the bump position, even if there is some error in the coordinate position of the bump, inspection such as measurement of the height of the bump can be reliably performed.

In the fourth invention of the present invention,

In the inspection means of the third invention,

Histogram creation means for finding the height of each part in the window, and creating a histogram indicating the relationship between height and frequency based on the height data;

Within a certain range from the minimum height value in the histogram to a value larger than the minimum value by a predetermined amount, the height at which the frequency becomes maximum is defined as the chip surface height, and the height in the histogram is The height of the chip surface was subtracted from the maximum value Calculating means for setting the value as the relative height of the bump in the window from the chip surface.

In another invention of the fourth invention,

In the inspection means of the third invention,

Histogram creation means for finding a height of each part in the window, and creating a histogram indicating a relationship between the height and the frequency based on the height data;

The average height within a certain range from the minimum height in the histogram to a value larger than the minimum by a predetermined amount is defined as the chip surface height, and the maximum height in the histogram is calculated from the maximum height in the histogram. Calculating means for calculating a value obtained by subtracting the height of the bump from the chip surface of the bump in the window.

It is equipped with.

According to the fourth aspect, a histogram is created based on height data of a narrow area such as a window around the coordinate position of the bump, and the height of the chip surface is obtained from this histogram, so that the IC pattern is obtained. The height of the chip surface can be accurately determined by removing the irregularities of the wafer and the effects of the wafer, so that the relative height of the bump from the chip surface can be accurately measured. Become. In the fifth invention of the present invention,

In the inspection means of the third invention,

A histogram creating means for determining the height of each part in the window, and creating a histogram indicating the relationship between the height and the frequency based on the height data;

From the height maximum value in the histogram, a cumulative frequency within a certain range from a maximum value to a first value smaller than the maximum value by a predetermined amount is obtained as a first cumulative frequency, and a predetermined amount from the maximum value is calculated. A small cumulative edge having a frequency within a certain range up to a second value larger than the first value is obtained as a second cumulative frequency, and a ratio of the second cumulative frequency to the first cumulative frequency is calculated. Is less than or equal to a predetermined threshold value, a determining means for determining that bumps are present in the bumps in the window; and

It is equipped with.

According to the fifth aspect, the bumps generated on the bumps are detected with high accuracy, and the bumps are detected. The inconvenience is prevented when sufficient electrical contact cannot be obtained during chip mounting due to missing.

In the sixth invention of the present invention,

In the inspection means of the third invention,

The height of each part in the remaining area of the chip た excluding the window part set in the chip on the wafer is obtained, and a histogram showing the relationship between the height and the frequency is created based on the height data. Histogram means to perform

Determining means for determining whether or not extra bumps are present in the chips of the wafer based on the histogram;

It is equipped with.

Further, in another invention of the sixth invention, the creation of the histogram is performed by dividing the remaining region in the chip excluding the window portion into a plurality of regions, and for each of the divided regions.

Further, in another invention of the sixth invention, the height at which the frequency is maximum in the histogram is the height of the chip surface, and the value obtained by calculating the height of the chip surface from the maximum height in the histogram is If it is equal to or greater than a predetermined threshold value, it is determined that extra bumps are present in the chip.

In another aspect of the sixth invention, the average height in the histogram is the height of the chip surface, and the value obtained by subtracting the height of the chip surface from the maximum height in the histogram is a predetermined threshold value. When the value is equal to or more than the threshold value, it is determined that an extra bump exists in the chip.

According to the sixth aspect, the presence / absence of extra bumps is determined from the histogram based on the height data of the remaining area where the bumps in the chip are masked, so that normal bumps and extra bumps are mistaken. Without this, extra bumps can be detected accurately.

Further, since the chip is divided into a plurality of parts and a histogram is created for each divided area, a histogram based on height data of a narrow area is created. Therefore, when the height of the chip surface was obtained from this histogram, IC chip was used. Eliminates the effects of pattern irregularities and wafer tilt, and accurately characterizes chip surface height. This makes it possible to accurately measure the relative height of the extra bump from the chip surface.

Further, in the seventh invention of the present invention, a height measuring device for measuring the height of each portion of the upper surface of the work by relatively moving the planar work in a vertical constant direction by a predetermined distance, Setting means for setting each movement position on a plane to which the measurement field of view of the height measuring device should move so that the entire upper surface is measured by the height measuring device; and each of the planes set by the setting means. By moving the measurement field of view to a moving position, and moving the workpiece relative to the height measuring device in the vertical constant direction relative to the height measuring device at each plane moving position, In a height measuring device equipped with a moving means for measuring the height of each part in the measurement field of view, the vertical movement in the measurement field of view of the next plane movement position will be the measurement field of the current plane movement position. Means to control the vertical movement direction so that it is performed in the opposite direction to the vertical movement direction

It is equipped with.

Further, in another invention of the seventh invention,

The height measuring device is for measuring the height of an inspection object having a predetermined size formed on a planar workpiece,

Adjacent measurement fields are overlapped so that at least one of the two measurement fields adjacent to each other on the plane contains the inspection object, and the plane movement position of the measurement field is set. I have to.

When the height of the workpiece is measured according to the seventh aspect of the invention, the alternate movement of the movement in the vertical Z direction in the measurement visual field and the movement in the planar direction of the measurement visual field is as follows.

FIG. 26 is a diagram conceptually showing the state of such movement, and FIG. 27 is a time chart thereof, corresponding to FIGS. 30 and 31 respectively.

As shown in these figures, the moving direction in the Z direction in each of the measurement visual fields N-1, N, and N + 1 is sequentially reversed. That is, in the measurement visual field N-1, the measurement is performed by moving in the descending direction d, and in the next measurement visual field N, the measurement is performed by moving in the ascending direction d 'opposite to the previous measurement, and the next measurement is performed. In the field of view N + 1, in the downward d direction opposite to the previous It is moved and measured (see arrows d and d 'in Figure 26).

In this way, measurement is performed while sequentially reversing the direction of movement in the vertical Z-axis direction. When moving to the next measurement field of view (arrow c in Fig. 26), only movement in the plane direction is performed. The movement in the vertical Z-axis direction just to return the Z stage to the original position as in the past is not performed.

For this reason, as shown in Fig. 27, one visual field cycle time is a combination of the time required to move in the Z-axis direction for measurement and the time required to move the measurement visual field in the plane direction. As shown in 1, the original measurement only to return the Z position to the initial position is not used for moving the measurement field of view, and there is no dead time. As a result, the cycle time in one field of view is reduced accordingly, and the throughput of the device can be dramatically improved.

Also, since there is no operation for returning the Z stage to the initial position, adverse effects such as vibration due to the movement are reduced. In particular, by increasing the speed at which the Z stage is returned to the initial position in order to reduce the dead time, there is no possibility that a large shadow effect due to vibration or the like will occur. In addition, since the operation for returning the Z stage to the initial position is eliminated, the durability of a driving mechanism such as an actuator for driving the Z stage is improved.

Further, according to another aspect of the seventh invention, the two inspection fields adjacent to each other on the plane are adjacent to each other so that the entire inspection object whose height is to be measured is included in at least one of the measurement fields. Since the measurement visual fields are overlapped with each other and the respective plane movement positions of the measurement visual fields are set, the height measurement of one inspection object as a whole is performed in at least one measurement visual field.

That is, in general, the driving mechanism for driving the Z stage has hysteresis between the movement in the ascending direction and the movement in the descending direction. Therefore, a height measurement error occurs between adjacent measurement fields having different Z-axis moving directions.

However, in the present invention, since the measurement of the height of one entire inspection object is completed within at least one measurement visual field, the measurement of the height of the inspection object is affected by the reciprocating hysteresis. Measurement can be performed without error. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing an embodiment of a wafer bump appearance inspection apparatus according to the present invention, and is a plan view of a wafer.

FIGS. 2 (a), (b), (c), and (d) are diagrams illustrating the relative positional relationship between a chip on a wafer and a measurement visual field.

FIG. 2 is a diagram for explaining a manner in which the measurement visual field is moved on the wafer.

FIG. 4 is a flowchart showing the procedure of the bump inspection process.

FIG. 5 is a diagram showing bumps included in the measurement visual field.

FIGS. 6A, 6B and 6C are diagrams for explaining types of bumps.

FIG. 7 is a diagram showing the positional relationship between the measurement field origin and the chip origin.

FIG. 8 is a diagram showing a chip coordinate system.

FIG. 9 is a diagram conceptually showing a data structure of a set value set in the measurement visual field. FIGS. 10 (a), (b), and (c) are flowcharts showing a processing procedure for judging pass / fail of each chip.

FIG. 11 is a histogram of height data obtained for each window.

FIG. 12 is a histogram when the wafer is tilted.

FIGS. 13 (a), (b), (c) and (d) are flow charts showing the procedure of the process for obtaining the height of the bump based on the histogram.

Figure 14 is a histogram of height data obtained by a window set for bumps with bumps.

Figure 14 is a histogram of height data obtained by a window set for bumps without bumps.

FIGS. 16 (a), (b) and (c) are flowcharts showing the procedure of the process for determining the presence or absence of bumps based on the histogram.

FIG. 17 is a plan view showing a chip having extra bumps.

FIG. 18 is a plan view showing an element obtained by dividing a chip having an extra bump into respective regions.

Fig. 19 (a) is a histogram of height data obtained by a chip with extra bumps. Figs. 19 (b) and (c) are histograms of Fig. 19 (a). 6 is a flowchart showing a procedure of a process of determining the presence or absence of an extra bump based on a system.

FIG. 20 is a perspective view of a wafer bump appearance inspection apparatus according to the embodiment.

FIG. 21 is a view for explaining a conventional wafer bump appearance inspection apparatus, and is a plan view of a wafer.

FIGS. 22 (a), (b), (c), and (d) are diagrams illustrating a conventional technique, and are diagrams illustrating a relative positional relationship between a chip on a wafer and a measurement visual field.

Figure 23 is a side view showing a state where the wafer (chip) is tilted.

FIG. 24 is a side view showing a bump having bumps.

FIG. 25 is a plan view showing a chip having extra bumps.

FIG. 26 is a diagram showing a mode of movement of each measurement visual field in the plane direction and movement of each measurement visual field in the vertical axis direction.

FIG. 27 is a time chart of FIG.

FIG. 28 is a side view of the bump.

FIG. 29 is a diagram illustrating a state in which the measurement visual fields overlap.

FIG. 30 is a diagram for explaining the prior art, and is a diagram showing a mode of movement of each measurement visual field in a plane direction and movement of each measurement visual field in a vertical axis direction.

FIG. 31 is a diagram for explaining the prior art, and is a time chart of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a wafer bump inspection apparatus according to the present invention will be described with reference to the drawings.

As a bump inspection apparatus, a conventional apparatus shown in FIG. 20 is used.

FIG. 3 is a diagram showing the relationship between the chip 2 formed on the surface of the wafer 1 and the measurement field of view 4 of the 3D measurement module 33 in an XY coordinate system.

Prior to the inspection of the wafer bump 3, the identification numbers CID are assigned to all the chips 2 in the chip group in the wafer 1 as C1, C2 to C7, and C8. In this figure, the upper left corner of chip 2 with identification number C7 in the upper left corner is set to the origin O of the XY coordinate axis (the two are indicated by double circles). And the X axis coincides with the top side of the chip group, The X-Υ coordinate axis is set so that the Y axis coincides with the left side of the chip group. On the other hand, for the measurement field of view 4 of the 3D measurement module 33, the identification numbers 1, 2, 3, ... for each X, Υ position are set so that the 3D measurement of the entire chip group is performed while the lamps are overlapped. Each measurement field of view VI, V2, V3 ... is set. The upper left corner of each measurement field VI, V2, V3 ... is set to the field origin OV (this is indicated by the X mark), and the field origin Ov of each measurement field VI, V2, V3 ... is the field coordinate. Expressed as position (VX, VY). The total number of measurement fields VI, V2, V3 ... is VN, and this total field number is also preset.

Therefore, if the XY movement axis of the XY stage of the wafer movement stage 32 shown in FIG. 20 matches the XY coordinate axis of FIG. 3, and the mechanical origin of the XY stage matches the coordinate origin O of FIG. By sequentially moving the XY stage according to the view coordinate position (VX, VY) of the view origin Ov of VI, V2, V3, etc., 3D measurement of the chip group can be performed accurately.

Here, it is assumed that the overlapping direction of the measurement visual field 4 exists not only in the X-axis direction as shown in FIG. 3 but also in the Y-axis direction as shown in FIG. 29 described later. Also, it is desired that the overlap range is wider than the size of one bump. In the case of such overlapping, the bump 3 existing near the boundary of the measurement visual field 4 enters without fail in any of the two overlapping measurement visual fields, and the 3D measurement can be accurately performed. Will be able to do so. Furthermore, it is preferable that the overlap of the measurement field of view 4 be larger than the size of a window for bump inspection described later.

When the pre-processing as described above is completed, the wafer 1 is placed on the wafer movement stage 32 by the wafer handling robot (not shown) of the apparatus shown in FIG.

Next, the 2D measurement module 31 detects two or more feature points on the wafer 1, for example, the positions of positioning marks. For example, the positioning marks Ma and Mb as shown in FIG. 1 are detected, and the attitude angle Θ and the positions X and Y of the wafer 1 are obtained from the detected positions. Then, the XY stage movement axis of the XY stage is aligned with the XY coordinate axis of FIG. The wafer 1 is positioned so that the point coincides with the coordinate origin O in FIG. Further, the position of the attitude position of the wafer 1 is determined by the Θ stage of the Θ Υ stage 32, up to the limit of the rotational resolution of the 0 stage. Then, the positions of the feature points Ma and Mb on the wafer 1 are detected again by the 2D measurement module 31, and the attitude error Δ0 of the XY stage of the wafer 1 with respect to the XY movement axis is obtained (see 囡 1). ). Here, when the attitude error Δ6 is 0.1 degrees, the position error ΔΧ is about 222 μπι at a position 5 inches away from the coordinate origin of the wafer 1.

By the way, the feature points on the wafer 1 to be detected by the 2D measurement module 31 need only be two or more places, and are located away from the center of the wafer 1 (chip group), and the feature points are separated from each other. This is desirable for accurately determining the attitude error ΔΘ.

Also, it is assumed that the correspondence between the direction of the visual field coordinates Χ—Υ of the 2D measurement module 31 and the coordinate origin and the direction of the Χ Υ movement axis of the wafer moving stage 32 and the coordinate origin is known in advance. I do.

The position of the attitude position of the wafer 1 is determined up to the limit of the rotational resolution of the stage of the wafer moving stage 32. However, if the attitude error described below can be corrected, However, it is not always necessary to position the attitude position of the wafer 1 up to the limit of the rotation resolution of the stage. Also, the mechanical origin of the stage and the coordinate origin in Fig. 3 do not need to be matched if the offset is known.

1 and 2 are views showing each measurement field 4 of the 3D measurement module 33. FIG. Now, the measurement field of view 4 for measuring the tip 2 b separated from the coordinate origin Ο and the surrounding chip is assumed to be without any correction, so that the measurement field of view 4 moves along the X axis. Alternatively, the measurement field of view is indicated by a broken line in FIG. This makes it impossible to accurately measure the chip 2b and the chips around it. Therefore, as shown by the solid line, the measurement field of view 4 is corrected so as to be moved by the XY stage.

FIG. 4 is a flowchart showing a procedure of the bump inspection process including the correction process.

First, the identification numbers I of the measurement fields VI, V2, V3 ... are set to 0 (step 101). This identification number I is incremented by +1 (step 102). Then, it is determined whether or not the current incremented identification number I has become larger than the total number of views VN (step 103). If the determination here is YES, the processing is terminated assuming that measurement has been completed for all measurement fields, that is, bump inspection has been completed for the entire wafer 1.

However, if the determination is NO, it is determined that the bump inspection for the entire wafer 1 has not been completed yet, and the procedure for measuring the measurement field ID (I) of the incremented identification number I is step 104. Will be migrated to.

Here, the visual field origin Ov of each measurement visual field VI, V2, V3... Is represented as a visual field coordinate position (VX, VY).

Therefore, in order to correct the position of the visual field coordinate position (VX, VY) of the measurement visual field 4 to be measured this time to a rotational position corresponding to the above-described attitude error Δ0, the visual field coordinate position ( VX, VY) and field coordinates (VX ', VY').

IVX 'cos m 0 i ri m S ^VX (1)

, νγ 's i ri m 0 co s m 0 VY

2 (a) and 2 (b) are diagrams showing the positional relationship between the chip and the measurement visual field when there is no attitude error ΔΘ, and FIGS. 2 (c) and (d) show the attitude error Δ0 FIG. 8 is a diagram showing a positional relationship between a chip and a measurement visual field when performing the measurement. 2 (a) and 2 (c) show the measurement field of view 4 set at the coordinate origin O, and FIGS. 2 (b) and 2 (d) show the measurement field of view set at a position distant from the coordinate origin O. 4 is shown.

When the correction by the above equation (1) is performed in the measurement field of view 4 at a position distant from the coordinate origin O (see Fig. 2 (d)), the coordinate displacement in the measurement field of view 4 is calculated as shown in Fig. 2 (b ), The size is negligible, and the position of the bump 3 in the measurement visual field 4 can be easily and accurately specified by referring to the set value for each measurement visual field described later. The inspection process can be performed with high accuracy.

As shown in FIG. 3, the method of moving the measurement field of view 4 to VI, V2, V3,... Other than the method of moving the stage on which the wafer 1 is mounted (moving by the wafer moving stage 32) The 3D measurement module 33 may be provided with a means for moving this in the X-axis and Y-axis directions, and a method of performing this using the XY moving means may be considered. In addition, it is desirable that each of the XY coordinate axes of the measurement visual field 4 of the 3D measurement module 33 is parallel to each of the ΧΥ movement axes of the wafer moving stage 32, and the direction of the ΧΥ coordinate axis of the measurement visual field 4 of the 3D measurement module 33 It is assumed that the correspondence between the coordinate origin, the direction of the moving axis of the wafer moving stage 32, and the coordinate origin is known in advance (steps 104 and 105).

Here, the contents of the set values set for each of the measurement visual fields VI, V2, ν3.

The set values are prepared in advance in the pre-processing stage of the actual inspection processing, similarly to the above-described visual field coordinate positions (VX, VY).

Fig. 5 shows the total of chip 2 with identification number C24, including chip 2 with identification numbers C11, CC12, C13, C23, C25, C35, C36, and C37 around it. FIG. 9 is a diagram for explaining set values of a measurement field of view 4 including nine chips in the field of view.

The following setting values are given to the measurement visual field 4.

CN: The total number of chips in the measurement visual field, and 9 is added.

C I D (CN): Identification number for each chip within the measurement field of view, C l l, C

C12, C13, C23, C25, C35, C36, C37 are awarded. CBN (CN): The total number of bumps for each chip within the measurement field of view. For example,

In the case of chip 2 with identification number C23, 6 is given.

BID (CN, CBN): The identification number of each bump in each chip within the measurement field of view. For example, in the case of identification number C23, B4, B5, B6, B7, B8, B9 Is given.

BX (CN, CBN): Origin of visual field (VX,

VY) is the X coordinate position.

BY (CN, CBN): View point origin (VX,

VY) is the Y coordinate position.

Specifically, it is set with a hierarchical data structure of the measurement field of view 4, chip 2, and bump 3 as shown in Fig. 9. In other words, “In the measurement field of view 4, there is a chip 2 with an identification number C 11, and the coordinate position BX, BY of the bump 3 with an identification number Β 7 in this chip 2 is…” Is to be specified. Here, the coordinate position BX, BY of bump 3 can be arbitrarily set as long as it is a position specifying bump 3. For example, it may be the coordinate position of the vertex of bump 3 or the coordinate position offset from the center of bump 3 by a predetermined distance.

Also, the identification number (BID) of the bump 3 is a common number チップ 1, チップ 2 '' Β for each chip 2, 2 各 if all the chips 2 on the wafer 1 are of the same design. It is possible to use 14. In addition, as the bump 3 registered as the set value of the measurement visual field 4, only the bump 3 having the center of the bump 3 in the measurement visual field 4 is targeted. In the case of FIG. 5, only the bumps 3 shown as outlines are targeted.

On the premise of the above, the coordinate position specifying process of bump 3 and the inspection process of bump 3 performed in FIG. 4 will be described.

That is, the count J for counting up to the total number of chips CN in the measurement visual field 4 is initialized to 0 (step 106), and the count J is incremented by +1 (step 107). Then, it is determined whether or not the current incremented J has become larger than the total chip number CN (step 108). If the determination here is YES, the procedure proceeds to step 102 assuming that the measurement has been completed for all the chips 2 in the current measurement field of view, that is, that the bump inspection in the measurement field of view 4 has been completed. The measurement of the measurement visual field 4 is performed. However, if the determination is NO, it is determined that the bump inspection has not yet been completed for the entire measurement field of view 4, and the procedure moves to step 109 to perform measurement in the chip 2 indicated by the incremented J. Is done.

In step 109, the count K, which counts up to the total number of bumps CBN (J) (6 in the case of chip 2 of C23) in the chip 2 which is currently incremented by J, is initialized to 0 (step 109). The count number K is incremented by +1 (step 110). Then, it is determined whether or not the current incremented K has become larger than the total bump number CBN (J) (step 1 1 1). If the determination here is YES, the procedure proceeds to step 107 assuming that the measurement has been completed for all bumps 3 in chip 2, that is, the bump inspection in chip 2 has been completed, and the next chip Perform the measurement of 2 c. If the judgment is NO, the bump inspection for the entire chip 2 has been completed. It is determined that the measurement has not been performed, and the procedure proceeds to step 112 in order to measure the bump 3 indicated by the incremented K.

That is, the coordinate position BX (J, K), BY (J, K) is read from the stored data shown in FIG.

Since the coordinate position of the bump 3 is specified in this way, the 3D measurement module 33 performs a height inspection on the specified coordinate position BX, BY of the bump 3. Specifically, as shown in FIG. 5, in the case of the bump 3 having the identification number B 13 of the chip 2 C having the identification number C 12, the entire bump 3 is provided with a window 7 as indicated by diagonal lines. By measuring the height of each part in the window 7 as described later, the height of the bump 3 in the window 7 is detected (step 113).

When the bump inspection is completed in this way, the inspection result is transferred to a predetermined storage location for each bump 3. That is, data to which the identification number C ID of the chip 2 subjected to the inspection and the identification number B ID of the bump 3 subjected to the inspection are added to the inspection result are transferred. Here, as the transfer method, only the data indicating the inspection result may be stored in a location where the identification numbers CID and BID are specified as addresses in advance, and the identification number CID, BID and the inspection result may be stored. May be transmitted via a communication network and stored in the memory of another processor connected to the network.

Further, as a set value for specifying the bump 3, a set value for specifying the type of the bump 3 may be added in addition to the identification number B ID, the coordinate position BX, and the BY described above.

In other words, as shown in Fig. 6 (the left side is a top view and the right side is a side view), there are three types of bumps: (a) spherical, (b) trapezoidal, and (c) connected type. By previously storing the types as set values, the inspection method (inspection algorithm) can be made different for each type of bump 3. Further, it may be determined whether or not the bump 3 should be inspected according to the content of the set value indicating the type of the bump 3. By the way, in steps 1 12 and 1 13 of FIG. 4, the coordinate positions BX and BY of all the bumps 3 are stored as data for each measurement visual field 4, and the coordinate positions of the individual bumps 3 are stored based on the data. Although it is specified, the amount of such data becomes enormous as the total number of bumps 3 in the wafer 1 increases. For this reason, a memory having a large storage capacity must be used, which leads to a problem of high cost.

Then, next, when all the chips 2, 2,... In the wafer 1 have the same design, the data amount of the coordinate position BX, BY of the bump 3 can be reduced, and the data can be stored in a memory having a small storage capacity. Embodiments which can be stored and cost can be reduced will be described.

That is, the following set values are used as the set values for each measurement field of view 4 instead of the above set values.

CN: The total number of chips in the measurement visual field, and 9 is added.

C12, C13, C23, C25, C35, C36, C37 are awarded. CX (CN): Chip origin O c from visual field origin O V for each chip within the measurement visual field

X-coordinate position.

CY (CN): Chip origin Oc from visual field origin Ov for each chip in the measurement visual field

This is the Y coordinate position.

CBN (CN): The total number of bumps for each chip within the measurement field of view. For example,

In the case of chip 2 with identification number C23, 6 is given.

BID (CN, CBN): The identification number of each bump for each chip within the measurement field of view. For example, in the case of identification number C23, B4, B5, B6, B7, B8, B9 Granted.

On the other hand, the following chip coordinate position is set as a common setting value for all measurement fields of view 4.

b X (B ID): The X coordinate position of each bump in the chip from the chip origin Oc.

by (BID): The Y coordinate position from the chip origin O c of each bump in the chip And

Note that the chip coordinate origin Oc is set, for example, in the upper left corner of each chip 2 as shown in FIG. Also, a chip coordinate system X—y having the origin at the chip coordinate origin O c is set as shown in FIG. 8, and the coordinate position bx, by of the bump 3 in the chip 2 is a coordinate on the chip coordinate axis x, y. Set as position. Incidentally, W and H in FIG. 8 indicate the external dimensions of one chip 2.

By setting the set values as described above, it is not necessary to store the coordinate position from the visual field origin Ov for all the bumps 3 on the wafer 1, so that the data amount of the set values can be reduced. However, since the coordinate position BX, BY of each bump 3 needs to perform the calculation as shown in the following equation (2), the load of the calculation processing increases.

BX = CX (J) + b X (B ID (K))

B Y = CY (J) + b y (B ID (K)) (2)

Such arithmetic processing is executed as step 115 instead of the processing of steps 112 in FIG.

Next, with reference to FIG. 10, a description will be given of a processing procedure for determining whether a chip is good or defective for each chip 2. FIG.

'Determine whether all the data of the inspection results of bump 3 in chip 2 have been acquired

First, a check flag F (C ID) for checking whether all the inspection result data has been acquired for each chip 2 is prepared. This check flag F (CID) is set to CN, the total number of bumps in chip 2 (CN == 14 in chip 2 illustrated in FIG. 5).

Then, in step 114 of FIG. 4, the inspection result for each bump 3, that is, data H (CID, BID) indicating the height H of the bump 3 of the identification number BID in the chip 2 of the identification number CID is transferred. Each time (step 201), the check flag F (CID) is decremented by one (step 202).

As a result, when the content of the check flag F (CID) becomes 0 (determination in step 203), it is determined that all the inspection result data for all the bumps 3 in the chip 2 has been acquired, and The quality of chip 2 is determined based on the data thus obtained (step 204). -First chip judgment processing (Fig. 10 (b))

First, the code I for counting the identification number BID of the bump 3 is initialized to 15, the code BM indicating the calculated value of the height H of the bump 3 is initialized to 0 (step 205), and the code I is decremented by 1 (step 205). 206). Unless the code I has reached 0 (NO in step 207), the process of updating the content of BM with the current BM plus the current bump height data H (CID, I) (Step 208), the process of decrementing the code I by 1 (Step 206) is sequentially performed.

As a result, the total value BM of the heights of all the bumps 3 in the chip 2 is finally obtained, and the result obtained by dividing this by 14 is used as the new BM content. That is, the average value BM of the heights of the bumps 3 in the chip 2 is obtained (step 209).

Next, the code I for counting the identification number B ID of the bump 3 is initialized to 15 again (step 210), and the code I is decremented by 11 (step 211). Then, as long as the code I does not reach 0 (decision N in step 212)

0), the current bump height data H (C ID,

The process of determining whether the absolute value of the value obtained by subtracting 1) is smaller than a predetermined threshold value ΔΒΗ (step 213), and the process of decrementing the code I by 11 (step 211) are sequentially performed. .

Here, if the deviation between the height H of the bump 3 and the above average value BM is within the prescribed range (BH) for all the bumps 3 in the chip 2, the chip 2 is judged as “good J”. It is determined that there is (YE S in step 212), and when the deviation between the height H of the bump 3 and the average value BM falls outside the predetermined specified range (soil BH) for any of the bumps 3 (No in step 213), the chip 2 is determined to be “defective”.

-Second chip judgment processing (Fig. 10 (c))

Further, the chip determination processing may be performed without obtaining the average value of the bump height.

That is, the code I for counting the identification number BID of the bump 3 is initialized to 15 (step 214), and the code I is decremented by 1 (step 2). 1 5). Unless the sign I has reached 0 (NO in step 2 16), the current height data H (CID, I) of the bump 3 is set to the lower limit BL of the predetermined range of the preset height. Is determined to be greater than or equal to and smaller than the current height data H (CID, I) of the bump 3 and the preset upper limit value BH of the prescribed range of height (step 217). The process of decrementing I by 11 (step 215) is performed sequentially. As a matter of course, the set values for comparison of ΔΒΗ, BL, BH, etc. described above may be set to the relative ratio (R) of a certain reference value (BM) instead of the absolute value. . For example, ΔΒΗ = ΒΜ · Κ, or BL = (1-R) .BM, BH = (1 + R) · BM. In this case, BM is not necessarily required to be an average value.

Here, if the height H of the bump 3 is within the prescribed range (BL to BH) for all the bumps 3 of the chip 2 內, the chip 2 is determined to be “non-defective” (step 216). When the height H of the bump 3 falls outside the predetermined range (BL to BH) for one of the bumps 3 (NO in step 217), the chip 2 It is determined to be "defective."

As described above, in the first and second chip determination processes described above, when bump 3 having a height outside the specified range is found (determination NO in step 213, determination NO in step 217), The chip 2 is determined to be defective and the subsequent determination of the bump 3 is terminated, thereby shortening the calculation processing time.

Such an algorithm for shortening the calculation processing time may be applied to the processing of the inspection of the bump 5 described later. In other words, when bump 5 is found on bump 3 in chip 2, the subsequent determination on bump 3 may be terminated, and chip 2 may be determined to be defective.

In addition, when data is transferred together with the data of the identification number CID of the chip 2 as in the inspection result of the extra bump 6 as described later, the subsequent processing can be terminated at the time of the data transfer. is there. That is, when the inspection result data indicating that the extra bump 6 is present is transferred, the chip 2 with the identification number CID is determined to be defective, and the subsequent processing for the chip 2 is terminated, and the next chip Wait for the data transfer for step 2. In the embodiment described above, the set value data such as CID and CBN prepared in advance before the inspection can be obtained based on the CAD data of the wafer 1.

Next, the details of the measurement of the height H of the bump 3 performed in step 113 of FIG. 4 will be specifically described.

That is, as shown by the diagonal lines in Fig. 5, when measuring the height H of the bump 3, a square window 7 centered on the center coordinate position of the bump 3 is set to surround this bump 3. . As described above, since the window 7 is set so as to include not only the entire bump 3 but also the surface of the IC chip near the bump 3, even if there is some error in the XY coordinate position of the bump 3, The whole can be reliably taken into the window 7, and the inspection can be performed effectively and accurately. For example, the diameter of a circular bump 3 as shown in Fig. 6 (a) is 100 μπ! In the case of 1150 til, a window ゥ 7 having a size of 200 / χπιΧ200 μ μη (length x width) is set.

In addition, when the window 7 is set, if the window 7 protrudes from the measurement visual field 4 of the 3D measurement module 3 3, that is, the identification number in the chip 2 of the identification number C 12 in FIG. When the window 7 is set to the bump 3 of, the vertical position data cannot be acquired for a part of the window 7 depending on the 3D measurement module 33. Therefore, it is desirable that the inspection of the bump 3 having the identification number 望ましい 13 should not be performed, since the histogram described later cannot be effectively created. However, if the pressure is left as it is, the inspection of the height of the bump 3 may be omitted, which is not preferable.

However, when setting the measurement fields of view VI, V2, V3, etc. as described above, they are made to overlap as shown in FIG. Therefore, if the size of the overlap is set to be larger than the size of the window 7, the window to be applied to the bump 3 of the identification number B1 3 in the chip 2 of the identification number C12 in FIG. As described above, even if the window 7 is near the measurement field boundary, the entire measurement field can be completely inserted into one of the two measurement fields that have been overlapped. Can be prevented. The 3D measurement module 33 acquires the vertical position data of each part in the window 7, and the obtained vertical position data is represented as a histogram as shown in FIG.

Therefore, the maximum value MX (the highest position) and the minimum value MN (the lowest position) of the vertical position data are obtained from this histogram. Here, the maximum value MX means the absolute height of the bump 3. On the other hand, the absolute height C of the surface of the IC chip 2 is determined as follows.

In other words, the frequency between the maximum value MX and the minimum value MN (MX-MN) / 2 to the minimum value MN is searched, and the vertical position data that gives the maximum frequency is the absolute height of the surface of the IC chip 2. C. Alternatively, in the same manner, the frequency from the intermediate value of the maximum value MX and the minimum value MN (MX—MN) / 2 to the minimum value MN is searched, and the average value of the vertical position data in that range is obtained by the IC chip 2. Absolute height C of the surface. Here, the frequency between the maximum value MX and the minimum value MN (MX-MN) / 2 to the minimum value MN is searched for because there are irregularities in the IC pattern. This is for consideration and consideration.

The deviation (MX-C) of these absolute position data is defined as the (relative) height H of the bump 3 from the surface of the IC chip 2.

Fig. 12 shows the case where the wafer 1 is inclined in the vertical direction as shown in Fig. 23 and the window 7 is set relatively large with respect to the area of the bump 3 (in the window 7, the IC chip 2 has a large proportion of the surface). Thus, when the wafer 1 is inclined, the peak indicating the frequency of the surface of the IC chip 2 is broad as shown by the broken line, and is uniquely determined by the same arithmetic processing as in the case of FIG. Determining the height H of the bump 3 at the same time results in inaccuracy. That is, as described above, the height of the surface of the IC chip 2 differs between one end of the window 7 and the other end due to the inclination of the wafer 1. Therefore, in order to reduce the influence of the inclination, the window 7 may be set narrow.

That is, if the window 7 is set to be relatively small with respect to the area of the bump 3 (the window 7 is set so that the ratio of the surface of the IC chip 2 occupies a small amount), the window shown in FIG. Broad histogram showing IC chip surface The peak is changed to a peak, as shown in Fig. 11.

Therefore, it is possible to apply the same calculation as in the case of FIG. 11, and it is possible to accurately obtain the absolute height of the surface of the IC chip. That is, the height H of the bump 3 can be accurately obtained.

As described above, the height H of the bump 3 from the chip surface can be accurately measured even if the IC pattern has irregularities or the wafer 1 is inclined.

FIGS. 13 (a), (b), (c) and (d) show processing procedures for obtaining the minimum value MN, the maximum value MX, the chip surface height C, and the height H of the bump 3.

In the following, I is a code indicating the size of the vertical position data, and is set in the range of 1 to 100. H IST (I) indicates the frequency of each vertical position for each size I (see Fig. 11).

• Calculation of minimum value MN

First, the vertical position data I is initialized to 0 (step 301), and the size I of the vertical position is incremented by +1 (step 302). Hereinafter, as long as the frequency HI ST (I) corresponding to the current vertical position size I is 0 (NO in step 303), the vertical position size I is incremented by +1; When the frequency HI ST (I) corresponding to the vertical position size I is no longer 0 (judgment YE S in step 303), the vertical position size I is set to the minimum value MN (step 304).

• Calculation of maximum value MX

First, the size I of the vertical position is initialized to 101 (step 305), and the size I of the vertical position is decremented by -1 (step 306). Hereinafter, as long as the frequency HIST (I) corresponding to the size I of the current vertical position is 0 (NO in step 307), the vertical position data I is decremented by 11, but When the frequency HI ST (I) corresponding to the size I is no longer 0 (decision YE S in step 307), the size I of the vertical position is set to the maximum value MX (step 308).

• Chip surface height C

First, the magnitude I of the vertical position is initialized to the minimum value MN, and P indicating the large frequency is initialized to 0 (step 309), and the magnitude I of the vertical position is incremented by +1 (step 310).

In the following, it is determined whether or not the magnitude of the current vertical position is greater than the intermediate value between the maximum value MX and the minimum value MN (MX + MN) / 2 (step 31 1). The process is determined to be outside the range for searching for the maximum value of frequency, and the processing is terminated. Otherwise, the process is in the range for searching for the maximum value of frequency, so the procedure moves to the next step 312.

In step 312, it is determined whether the current maximum frequency P is greater than the frequency HI ST (I) corresponding to the current vertical position size I (step 312). If so, the content of the maximum frequency P is updated to the current frequency HI ST (I), and the chip surface height C is used as the current vertical position data I (step 313). If YES, the procedure shifts to step 310 without performing the update as in step 313, and the same processing is repeated.

Eventually, the determination in step 311 becomes YES, and when the frequency exceeds the range for searching for the maximum value of the frequency, the content of P finally updated in step 313 becomes the maximum frequency and the content of the finally updated C Is the chip surface height at which the maximum frequency is obtained.

• Inspection of bump height

As shown in FIG. 11, based on the vertical position data in the window 7, a frequency H 1 ST (I) corresponding to the magnitude I of each vertical position S is created (step 314), and the minimum is determined as described above. The value MN is calculated (step 315), the maximum value MX is calculated (step 316), and the height C of the chip surface is calculated (step 317). Then, as the value obtained by subtracting the chip surface height C from the maximum value MX, the height H of the bump 3 of the identification number B ID in the chip 2 of the identification number C ID is obtained (step 318).

Next, a case where the presence or absence of the bump 5 is inspected by using a histogram similar to that in FIG. 11 will be described.

That is, the maximum value M is calculated from the intermediate value (MX-MN) / 2 between the maximum value MX and the minimum value MN. The frequency is counted in the range up to X, and the cumulative frequency S in this range is obtained. On the other hand, the frequencies in the range from the value (MX-X) (> (MX-MN) / 2) smaller than the maximum value MX by a predetermined amount X to the maximum value MX are counted, and the cumulative frequency SX in this range is calculated. Can be

Therefore, the ratio SX / S of these cumulative frequencies is evaluated with a predetermined evaluation value R, and the presence or absence of the bump 5 is determined. That is, as shown in FIG. 24, the bump 3 having the bump 5 has a ratio SX / S smaller than the evaluation value R. Conversely, bump 3 without bump 5 has a ratio SX / S equal to or greater than evaluation value R.

Here, the evaluation value R can be statistically determined from the ratio SX / S obtained from the histogram of the normal bump 3 without the bump 5 as shown in FIG.

FIGS. 16 (a), (b) and (c) are flowcharts showing the processing procedure of the cumulative error SX, the cumulative error S, and the bump test. Hereinafter, these will be described.

• Calculation of cumulative frequency SX

First, the magnitude I of the vertical position is initialized to the maximum value MX, SX indicating the cumulative frequency is initialized to 0 (step 401), and the magnitude I of the vertical position is decremented by -1 (step 402). ).

Hereinafter, it is determined whether or not the current vertical position size I has become smaller than (MX-X) (step 403). If the determination is YES, it is determined that the range exceeds the range for obtaining the cumulative frequency, and the processing is performed. , But otherwise the frequency is in the range to be accumulated, so the procedure moves to the next step 404.

In step 404, the content of the maximum frequency SX is updated as the current maximum frequency SX plus the frequency H I ST (I) corresponding to the current vertical position size I (step 404). This process is repeatedly executed while sequentially decrementing I as long as the determination in step 403 is NO.

Eventually, the determination in step 403 becomes YES, and when the maximum frequency is exceeded, the content of SX updated in step 404 is finally obtained as the cumulative frequency.

-Calculation of ferocity frequency S

In this process, (MN + MX) / 2 is used instead of (MX-X) in Fig. 16 (a), The description is omitted because it is the same except that S is used instead of SX (see Fig. 16 (b)).

As described above, the cumulative frequency S X is calculated (step 409), and the cumulative frequency S is calculated (step 410). The presence or absence of bump 5 is determined for bump 3 of identification number BID in chip 2 of identification number CID based on whether the ratio SX / S is smaller than evaluation value R (step 41). 1).

The data indicating the height H of bump 3 and the presence or absence of bump 5 obtained as described above are transferred as inspection result data together with the identification number CID of the chip 2 and the identification number BID of bump 3. (Steps 1 1 4).

Next, a case will be described in which the presence / absence of the extra bump 6 is inspected using the same histogram as in FIG.

FIG. 17 shows how each window 7 is set for one chip 2. As described above, when determining the height H of bump 3, the histogram was created assuming that the vertical position data in window 7 was valid, but in the inspection of extra bump 6, the data in window 7 This results in an error in the inspection of bump 6.

Therefore, the window 7 is masked as shown by hatching, and a histogram is created based on the vertical position data of only the other portions.

However, if the vertical position data for the entire chip 2 is used, errors due to the inclination of the chip 2 may occur as described in FIG. 12, and the surface height C of the chip 2 may be accurately detected. It may not be possible.

Therefore, the chip 2 may be divided into small areas so that the peaks indicating the chip surface have a certain peak as shown in FIG. 11, and a histogram may be created for each of the divided regions. For example, as shown in FIG. 18, it is conceivable to divide the entire chip 4 into four and create a histogram for each divided region 8.

FIG. 19 (a) shows a histogram for region 8 in FIG.

That is, the 3D measurement module 33 obtains the vertical position data of each part in the area 8, and the obtained vertical position data is represented as a histogram as shown in FIG. 19 (a). Therefore, the maximum value MX (the highest position) and the minimum value MN (the lowest position) of the vertical position data are obtained from this histogram. Here, the maximum value MX means the absolute height of the provisional extra bump 6. On the other hand, the absolute height C of the surface of the IC chip 2 is determined as follows.

That is, the frequency from the maximum value MX to the minimum value MN is searched, and the vertical position data at which the maximum frequency is obtained is determined as the absolute height C of the surface of the IC chip 2. Alternatively, similarly, the frequency from the maximum value MX to the minimum value MN is searched, and the average value of the vertical position data in that range is taken as the absolute height of the surface of the IC chip 2.

Then, the deviation (MX-C) of these absolute position data is assumed to be the (relative) height H of the temporary extra bump bump 6 from the surface of the IC chip 2.

Then, this H is compared with a preset value T. If the height H is equal to or less than T, it is determined that there is no extra bump 6, and if the height H is larger than T, the extra bump 6 is It is determined that there is.

FIGS. 19 (b) and (c) are flowcharts showing the processing procedure for chip surface height C and extra bump inspection. .

• Calculation of chip surface height C

This operation is the same as in FIG. 13 (c) except that MX is used instead of (MX + MN) / 2, and a duplicate description is omitted.

.Extra bump inspection

The maximum value MX is calculated in the same manner as in FIG. 13 (b) (step 506), and the height C of the chip surface is calculated as shown in FIG. 19 (b) (step 507) . Then, the presence or absence of the extra bump 6 is determined for the area 8 in the chip 2 of the identification number C ID depending on whether MX-C is smaller than the set value T (step 508). This process is performed in the same manner for the remaining regions 8, 8, and 8 of the chip 2, and based on the determination results for all four regions, whether or not there is finally the extra bump 6 in the chip 2 Is determined.

The data indicating the presence or absence of the extra bump 6 obtained as described above is transferred as inspection result data together with the identification number CID of the chip 2 (step 114). Next, an embodiment capable of inspecting bumps on a wafer at high speed will be described.

An apparatus for measuring the height of the bumps 3 on the wafer 1 shown in FIG. 20 is disclosed in a patent application filed by the present applicant (Japanese Patent Application No. 6-109293). Can be used.

That is, the three-dimensional shape measurement apparatus to which the confocal optical system disclosed in this application is applied can be used as the 3D measurement module 33.

In this type of 3D measurement module 33, the entire confocal optical system, only the objective lens, or the stage on which the wafer 1 is mounted is moved in the vertical direction. In this case, the 3D measurement module 33 in FIG. 20 is provided with a Z-axis movement mechanism for moving the 3D measurement module 33 in the Z-axis direction. The Z-axis movement mechanism moves the 3D measurement module 33 in the Z-axis direction. It is assumed that the wafer 1 is moved relative to the 3D measurement module 33 by a predetermined distance in the vertical direction.

In this way, the wafer 1 is moved in the Z direction, and the movement position at which the amount of light received by the light receiving unit of the 3D measurement module 33 becomes the maximum is the height of the object to be measured (the bump 3 on the wafer 1) at the light receiving point. Position. Such processing is performed for each light receiving unit arranged in an array.

Then, as described above, since the entire wafer 1 cannot be measured in one measurement field 4 of the 3D measurement module 33, the measurement field 4 is switched and the same processing is executed. In other words, so that the height of the entire upper surface of the wafer 1 is measured by the 3D measurement module 33, each movement position O v, O v, O v… are set (see Fig. 3). Then, the measurement field of view 4 is sequentially moved to each of the set plane movement positions in the order of VI, V2, V3, etc., and the wafer 1 is moved relative to the 3D measurement module 33 for each plane movement position. By moving the predetermined distance in the Z direction, the height H of the bump 3 in the measurement visual field 4 is measured.

Fig. 26 is a diagram showing the movement of each measurement field of view VI, V2, V3 --- V-1, VN, ViV + 1 ... in the plane direction, and the movement of each measurement field of view in the vertical Z-axis direction. FIG. 27 shows a timing chart thereof, which corresponds to FIGS. 30 and 31 of the prior art, respectively. As shown in these figures, the Z-axis movement mechanism drives the 3D measurement module 33 so that the movement direction in the Z direction is sequentially reversed in each of the measurement visual fields ViV-l, ViV, and ViV + 1. That is, in the measurement visual field ViV-1, the height H of the bump 3 is measured by moving in the descending direction d, and in the next measurement visual field ViV, the measurement is performed by moving in the ascending direction d 'opposite to the previous one. In the next measurement field of view VN + 1, measurement is performed by moving in the downward direction d opposite to the previous one (see arrows d and d 'in Fig. 26).

The measurement of the height H of the bump 3 is performed by setting the window 7 as described above.

Fig. 28 shows a cross-sectional view of the bump 3. The 3D measurement module 33 measures the distance Z1 from the origin of the Z-axis movement mechanism (Z stage) to the surface of the chip 2. The distance Z 2 to the vertex of 3 is measured. The height H of the bump 3 in the window 7 is measured as these deviations Z 1 —Z 2. The bump height H is determined as the relative height Zl—Z2 for each window 7 for the following reason. That is, if the position of the wafer 1 is different (if the window setting position is different), the absolute height of the chip surface is different. For this reason, if the height of the bump 3 is determined as an absolute height with respect to one reference, an error occurs in the bump height. This is to avoid this.

As described above, in this embodiment, measurement is performed while sequentially reversing the movement direction in the vertical Z-axis direction, and when moving to the next measurement visual field (arrow c in FIG. 27), Only the movement in the plane direction is sufficient, and the movement in the vertical Z-axis direction only for returning the 3D measurement module 33 to the initial position in the Z direction as in the conventional case is not performed.

For this reason, as shown in Fig. 27, one view cycle time is the time during which the 3D measurement module 33 is moved in the Z-axis direction for height measurement and the time when the measurement view field 4 is moved in the plane direction. As shown in Fig. 31, there is no dead time that is not used for moving the measurement field of view 4 in the original height measurement just to return the Z position to the initial position. As a result, the cycle time for one field of view is reduced accordingly, and the throughput of the device can be dramatically improved.

In addition, since there is no operation for returning the 3D measurement module 33 to the initial position in the Z direction, adverse effects such as vibration due to movement are reduced. Above all, dead time By increasing the speed at which the 3D measurement module 33 is returned to the initial position for the purpose of shortening, there is no possibility that a large influence due to vibration or the like may occur. In addition, since the operation for returning the 3D measurement module 33 to the initial position is eliminated, the durability of the Z-axis movement mechanism is improved.

The embodiment of increasing the measurement speed by reciprocating the Z-axis moving mechanism in this way can be applied to any measurement target without being limited to the measurement of the bump.

Now, as described above, when setting each measurement visual field VI, V2, ν3,..., They are made to overlap as shown in FIG.

FIG. 29 shows an overlapping mode for four adjacent measurement fields of view A, B, C, and D.

That is, window 7 is set such that approximately 1/20 of the length of one side of the measurement visual field is the length of one side of window 7. Then, the overlap area (which is indicated by oblique lines) is set to be larger than the size of the force window 7. As a result, the entire window 7 including the bump 3 whose height is to be measured enters the at least one measurement field of view のうち of both adjacent measurement fields, and the measurement of one window 7 is performed by at least one of the two measurement fields. This will be done within the measurement field of view. For example, as shown in window 7α in Fig. 29, even a window that is originally near the boundary of the measurement field of view できない and cannot be measured only with the measurement field of view A, due to the overlap described above, The entire window 7a can be measured only with this measurement field of view B since the entire window is included without any loss. The same applies to window 7b, and measurement can be performed only in measurement field A. Further, for the window 7c completely included in the overlapped area 內, measurement is overlapped between the measurement visual fields A and B. In this case, it is possible to deal with this by overwriting the measurement result of the window 7c or determining in advance which of the measurement results A or B has priority.

As described above, by overlapping the measurement visual fields, the inspection of the entire window 7 can be reliably performed in at least one measurement visual field. As a result, the inspection of the bump 3 can be prevented from being missed.

By combining this embodiment with the above-described embodiment in which the Z-axis moving mechanism is reciprocated to increase the speed of measurement, the following effects can be obtained.

That is, in general, the Z-axis movement mechanism that drives the 3D measurement module 33 has hysteresis between the movement in the ascending direction and the movement in the descending direction. Therefore, if there is no overlap between the measurement visual fields, a height measurement error occurs between the measurement visual fields A and B.

In other words, if the measurement visual field A and the measurement visual field B do not overlap, and if the window 7 is set over both fields in the boundary area of these measurement visual fields, a part of the window 7 Will be measured in measurement field A, and the rest of window 7 will be measured in measurement field B. In these adjacent measurement fields of view A and B, the Z-axis movement direction at the time of measurement is reversed, and there is hysteresis, and the measurement part of the window ゥ 7 by the measurement field A and the measurement part of the window 7 by the measurement field B Thus, an error occurs.

However, in this embodiment, the measurement fields A and B are overlapped, and the measurement of the entire window 7 is completed in at least one of the fields of view. The measurement of the height of the bump 3 included in 7 is not affected by the hysteresis of the reciprocating movement, and the measurement can be performed without error. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention can be applied to inspection of the appearance of protrusions other than bump electrodes on a wafer.

Claims

The scope of the claims

1. Inspection of the appearance of the bumps on the wafer by changing the relative position and orientation between the wafer and the visual means for imaging the bumps on the wafer by the relative position and orientation change means, and inspecting the appearance of the bumps on the wafer. In the device,

The visual means has a measurement visual field capable of imaging a plurality of bumps at once, and the measurement visual field should be moved so that all the bumps on the wafer are imaged by the visual means. Setting means for setting a coordinate position on the coordinate system; and when the wafer is positioned by the positioning means, detecting a rotational position shift of the wafer about a coordinate origin on the coordinate system as a rotation center. A detecting unit, and correcting each set coordinate position of the measurement field of view of the viewing unit set by the setting unit by rotating the coordinate system on the coordinate system by a rotational position shift detected by the detecting unit. Correction means;

Apparatus for inspecting wafer bump appearance.

2. Bump coordinate position setting means for presetting the coordinate position on the coordinate system of each bump included in the measurement field of view,

2. The wafer bump appearance inspection device according to claim 1, further comprising:

3. In a wafer bump appearance inspection apparatus that images a plurality of bumps on a wafer by visual means and inspects the appearance of the bumps on the wafer based on the imaging result,

For each chip on the wafer, the average height of a plurality of bumps in the chip is determined based on the imaging result of the visual means, and the height of all bumps in the chip is Apparatus for inspecting the appearance of wafer bumps that determines that the chip is non-defective if it falls within a certain deviation from the average height.

4. In a wafer bump appearance inspection apparatus, comprising visual means for imaging a bump on a wafer with a measurement field of a predetermined size, and inspecting the appearance of the bump on the wafer based on an imaging result of the visual means,

Apparatus for inspecting wafer bump appearance.

5. The inspection means includes:

Within a certain range from the minimum height value in the histogram to a value larger than the minimum value by a predetermined amount, the height at which the frequency is maximum is defined as the chip surface height, and the maximum height in the histogram 5. The wafer bump appearance inspection device according to claim 4, further comprising: a calculating unit that sets a value obtained by subtracting the height of the chip surface from the value to a relative height of the bump of the window # from the chip surface.

6. The inspection means includes:

The average height within a certain range from the minimum height value in the histogram to a value larger than the minimum value by a predetermined amount is defined as the chip surface height.From the maximum height value in the histogram, the chip surface is determined. Calculating means for calculating a value obtained by subtracting the height of the bump from the chip surface of the bump in the window.

5. The visual inspection device for wafer bumps according to claim 4, comprising:

7. The inspection means includes:

From the height maximum value in the histogram, a cumulative frequency within a certain range from a maximum value to a first value smaller than the maximum value by a predetermined amount is obtained as a first cumulative frequency, and a predetermined amount from the maximum value is calculated. The second frequency is calculated as a second cumulative frequency, which is smaller and is larger than the first value and which is within a certain range up to a second value, wherein the ratio of the second cumulative frequency to the first cumulative frequency is Judging means for judging that bumps are present in the bumps in the window when the difference is equal to or less than a predetermined threshold value;

8. The inspection means includes:

The height of each part in the remaining area in the chip excluding the window part set in the chip on the wafer is determined, and a histogram showing the relationship between the height and the frequency is created based on the height data. Histogram means for performing

Determining means for determining whether or not extra bumps are present on the chips の of the wafer based on the histogram;

9. The wafer bump appearance inspection apparatus according to claim 8, wherein the histogram is created by dividing a remaining region in the chip excluding the window portion into a plurality of regions and performing the division for each of the divided regions.

1 0. The determining means

The height at which the frequency is maximum in the histogram is the height of the chip surface, and the value obtained by subtracting the height of the chip surface from the maximum height in the histogram is equal to or greater than a predetermined threshold value. , It was determined that extra bumps were present on the chip 、,

9. The visual inspection apparatus for a wafer bump according to claim 8, wherein:

1 1. The determining means

The average height in the histogram is defined as the height of the chip surface. When a value obtained by calculating the height of the chip surface from the maximum height of the ram is equal to or larger than a predetermined threshold value, it is determined that an extra bump exists in the chip.

1 2. A height measuring device that measures the height of each part of the upper surface of the work by relatively moving a planar work by a predetermined distance in the vertical constant direction, and measuring the height of the entire upper surface of the work Setting means for setting each movement position on a plane to which the measurement field of view of the height measuring device is to be moved, so that the measurement field of view is measured at each plane movement position set by the setting means. By moving the work relative to the height measuring device and moving the work by the predetermined distance in the vertical constant direction at each plane movement position, each part of the work in the measurement visual field is moved. In a height measuring device provided with a moving means for measuring the height of

Means for controlling the vertical movement direction so that the next vertical movement in the measurement visual field at the plane movement position is performed in the opposite direction to the vertical movement direction in the measurement visual field at the current plane movement position.

Height measuring device equipped with.

13. The height measuring device is for measuring the height of an inspection object of a predetermined size formed on a planar workpiece,

Adjacent measurement fields are overlapped so that the entire inspection object falls within at least one of the two measurement fields adjacent to each other on the plane, and the plane movement position of the measurement field is set. ,

The height measuring device according to claim 12.