KR20140128670A - Wafer chip failure analysis system equipped with thermal camera - Google Patents

Abstract

An apparatus for analyzing die failure using a thermal camera is disclosed. The apparatus for analyzing die failure using a thermal camera, of the present invention, comprises: a fixing means for fixing a wafer; a thermal camera for capturing the surface temperature distribution of a die included in the wafer that is fixed on the fixing means; a pair of needles which electrically comes into contact with a pad of the die; a probe manipulator for controlling the position of the needles in response to a user operation; a power drive for applying power to the die via the needles; and a control analyzing means for determining coordinates of a point where the temperature is increased more than a predetermined value from the captured image of the thermal camera for the die with applied power for a predetermined time.

Description

TECHNICAL FIELD [0001] The present invention relates to a die failure analyzer using a thermal camera,

The present invention relates to a die failure analysis apparatus.

In the final test after the manufacturing process of the semiconductor wafer, the operation of each wafer on the wafer is tested using a wafer prober.

Wafer prober is a device that judges whether a chip is defective by contacting a probe card connected to a tester and a pad inside a wafer loaded in a chuck from a cassette.

Fig. 1 illustrates the shape of a wafer and a probe card according to the prior art.

After the wafer fabrication process, the wafers are loaded into the wafer prober for final testing, and the wafer prober tests the operation of the die by contacting the pins of each die on the wafer with the pins of the probe card and generating a test signal.

Upon completion of the test for the wafer, the wafer prober transports the wafer back to the cassette and transports the next wafer for loading.

As a result of the final test, the dies determined as Fail are discarded, and the remaining dies are manufactured from the wafer by sawing.

Fig. 2 shows the shape of the die produced through such a process.

At this time, among the dies included in the manufactured wafers, the ratio of good products which are passed through the test and produced is referred to as Yield Rate. In general, the initial yield of development of new products is only 50% When technology improves, it is common to increase by more than 50%.

The technological competitiveness of the semiconductor industry depends on how quickly it can raise the yield.

In order to increase the yield, wafers are sampled and sent to the analytical laboratory. In the analytical laboratory, the causes of failures are analyzed for dies that have failed by using a failure analysis device. The cause of the failure is fed back to the manufacturing process, and the yield is improved through this process.

Various methods have been developed for analyzing defective dies in analytical laboratories.

Among them, there have been developed devices for determining the position where heat generation of a defective die occurs by photographing using a thermal camera.

However, there is a problem in that such known equipment takes an excessively long time to analyze one die because it takes 15 to 20 minutes to test one die.

In addition, even when a hot spot is photographed, there is a problem in that it is not easy to accurately grasp where a shot has occurred in the die in consideration of the characteristics of a thermal camera image.

Another problem is that because the wafer is analyzed on a wafer-by-wafer basis, the remaining dies that are not defective are also discarded.

For example, if the yield is 70%, 70% of the good products will be discarded for the cause analysis of the defective wafer chip corresponding to 30%. Thus, unnecessary losses are only generated in domestic billions of billions It is known to reach.

US Patent No. 5,196,353 entitled " Method for controlling a semiconductor CMP process by measuring a surface temperature and developing a thermal image of the wafer "(Micron technology, inc.)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a die failure analysis apparatus using a thermal camera in which test time is remarkably shortened.

It is another object of the present invention to provide a die failure analysis apparatus using a thermal imaging camera which can clearly and clearly identify an image of a die on which a shot has occurred by photographing with a thermal imaging camera using a SIL lens.

It is still another object of the present invention to provide a die failure analysis apparatus using a thermal imaging camera which enables easy power application by accurately contacting needles to a plurality of die.

It is still another object of the present invention to provide a die failure analysis apparatus using a thermal imaging camera capable of performing analysis by applying power to individual sawing die and imaging the wafer with a thermal imaging camera.

According to an aspect of the present invention, there is provided an apparatus for analyzing die failure using a thermal imaging camera, comprising: fixing means for fixing a wafer;

A thermal image camera for photographing a surface temperature distribution of the die included in the wafer fixed to the fixing means;

A pair of needles electrically contacting the pads of the die;

A probe manipulator for controlling a position of the needle according to a user operation;

A power drive for applying power to the die through the needle; And

And control analysis means for determining coordinates of a point at which the temperature is increased by a predetermined value or more from the photographed image of the thermal imaging camera with respect to the die to which power is supplied for a predetermined period of time.

According to another aspect of the present invention, there is provided an apparatus for analyzing a die failure using a thermal imaging camera, including: fixing means for fixing two or more sawed dies;

A laminating camera for photographing a surface temperature distribution of one of the dies fixed to the fixing means;

A pair of needles electrically contacting the pads of the die;

A probe manipulator for controlling a position of the needle according to a user operation;

A power drive for applying power to the die through the needle; And

And control analysis means for determining coordinates of a point at which the temperature is increased by a predetermined value or more from the photographed image of the thermal camera with respect to the die to which power is supplied for a predetermined time,

The fastening means comprising: a plate having at least one chip mounter on which the sawed die is mounted; And

And tilting means for rotating the angle of the plate with a rotation axis perpendicular to the surface of the chip mount facing the die bottom.

At this time, the control analysis means photographs a die mounted on any one of the chip mounts using a thermal camera, determines an error angle between the photographed die and a predetermined reference position, and controls the tilting means To the reference position.

According to the present invention, the time required for the analysis of the defective die through the thermal camera is drastically shortened.

Furthermore, by shooting with a thermal camera using the SIL lens, there is an effect that the image of the die on which the shot occurs can be more clearly and clearly distinguished.

There is an effect that workability is improved by accurately contacting the needles with a plurality of dies.

In addition, it is possible to automate and process a series of steps of sowing and mounting a plurality of dies, aligning them, contacting the needles with pads, applying power, and taking pictures when heat is generated, .

1 is a reference view showing a shape of a wafer and a probe card according to the prior art,
2 is a reference view showing the shape of a wafer chip according to the prior art,
3 is a diagram showing an outline of a die failure analysis apparatus using a thermal camera according to an embodiment of the present invention,
4 is a block diagram schematically showing a structure of a die failure analysis apparatus using a thermal imaging camera according to the present invention,
5 is a diagram for explaining the duty ratio of the PWM power supply or the application of a higher voltage,
6 is a view showing a state in which a thermal camera, a SIL and a die are sequentially arranged,
Fig. 7 is a diagram showing an outline of a die failure analysis apparatus using a thermal camera according to this embodiment of the present invention,
8 is a view showing a structure of a plate and a chip mounter in the present invention shown in Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments and accompanying drawings. In order to clarify the present invention, contents which are not related to the configuration of the present invention will be omitted, and the same reference numerals are used for the same components.

On the other hand, when an element is referred to as being "comprising" another element in the description of the invention or in the claims, it is not interpreted as being limited to only that element, Elements may be further included.

Also, in the description of the invention or the claims, the components named as "means", "parts", "modules", "blocks" refer to units that process at least one function or operation, Each of which may be implemented by software or hardware, or a combination thereof.

[First Embodiment]

3 to 6, a die failure analysis apparatus using a thermal camera according to an embodiment of the present invention will be described.

FIG. 3 is a diagram showing an outline of a die failure analysis apparatus using a thermal camera according to an embodiment of the present invention, FIG. 4 is a block diagram schematically showing the structure of a die failure analysis apparatus using a thermal image camera according to the present invention to be.

4, an apparatus 1000 for analyzing die failure using a thermal imaging camera according to the present invention includes:

A fixing device 1100, a thermal imaging camera 1200, a solid immersion lens 1300, a needle 1400, a probe manipulator 1500, a power drive 1600 and a control analysis means 1700.

At this time, the fixing means 1100 fixes the wafer 1.

The thermal camera 1200 radiates infrared rays to take a picture of the surface temperature distribution of the die 1 'included in the wafer 1.

On the other hand, the needle 1400 is in electrical contact with the pad of the die.

The probe manipulator 1500 corresponds to an operation device for controlling the position of the needle 1400.

The user manipulates the probe manipulator 1500 while viewing the die 1 'of the wafer 1 through the microscope so that a pair of needles 1400 are positioned on the pad 1' 'corresponding to +, - of the die 1' ).

On the other hand, the power drive 1600 applies power to the die 1 'through the needle 1400.

Each die 1 'has a reference voltage and a reference current value. For example, it may have a reference value such as 5 V, 5 mA.

The control analyzing means 1700 obtains the reference voltage value and the reference current value from the information on the corresponding die 1 'inputted thereto and controls the power drive 1600 to calculate the reference voltage value of the die 1' The power can be supplied in accordance with the reference current value.

On the other hand, since the die 1 'to be tested by the die failure analysis apparatus 1000 using the thermal camera according to the present invention is determined to be defective in the final test process, if a power supply is supplied for a predetermined time or longer, do.

When the user shoots the die 1 'using the thermal camera 1200 after the power is applied for a predetermined time or longer, the control analyzing means 1700 analyzes the thermal image of the thermal camera 1200 with respect to the die 1' The coordinates of the point at which the temperature is increased from the image by a predetermined value or more is determined.

That is, the position where the heat is generated in the die 1 'is analyzed in the form of coordinates of the x, y, and z axes.

The user can compare the analysis result with the design structure of the die 1 'so as to know which portion of the die is defective.

However, when the power source is applied in accordance with the reference current value and the reference power source value of the die 1 ', it takes 15 to 20 minutes to generate a significant level of heat.

Therefore, it can be seen that it takes an excessively long time to obtain the analysis data.

In order to solve this problem, the control analysis means 1700 controls the power drive 1600 in the following manner.

When the power drive 1600 applies pulse width modulated PWM power to the die 1 ', the control analyzer 1700 multiplies the reference pulse width of the die 1' by a constant greater than one The duty ratio is changed and applied.

FIG. 5A illustrates a case where the duty ratio of the PWM power supply is changed and applied.

The left side of FIG. 5 (a) corresponds to the reference pulse width of the die 1 ', and the right side represents a power source in which the duty ratio is changed by multiplying by a constant larger than 1.

At this time, the voltage remains the same.

By changing the duty ratio in this way, the heat generation time of the die 1 'is drastically shortened. Of course, in this case, considering that the die 1 'may be unreasonable but the die 1' is not a fixed product and is discarded after one test, this configuration is adopted for the effect of shortening the time do.

At this time, a constant value larger than 1 may be stored in advance in the control analyzing means 1700 according to the type of the die 1 ', which is set in advance according to the reference voltage or current value.

Another method is to apply a voltage that is higher than the reference voltage directly.

Fig. 5 (b) illustrates the application of a higher voltage to the die 1 'by a certain ratio than the reference voltage.

The left side of FIG. 5 (b) shows the reference voltage, and the right side shows a higher voltage at a certain rate than the reference voltage.

The control analysis means 1700 controls the power drive 1600 to apply power to the die 1 'and apply a voltage of a magnitude that is multiplied by a constant value greater than 1 to the reference voltage of the die 1' .

At this time, the maximum current limit is set.

At this time, a constant value larger than 1 may be stored in advance in the control analyzing means 1700 according to the type of the die 1 ', which is preset according to the reference voltage or the reference current.

The maximum current limit can also be preset according to the reference voltage or the reference current.

For example, when the reference voltage and the reference current of the die 1 'are 5V and 5mA, respectively, the control analyzing means 1700 can multiply the reference voltage value by 1.4 and apply 7V. At this time, it is possible to set the maximum current limit to 5 mA to limit the flow of current.

By doing so, the time during which significant heat generation occurs in the die 1 'can be drastically shortened.

As a result of the experiment, it was found that it took about 15 to 20 minutes for significant heat generation to occur. When the duty ratio is changed or the voltage is directly increased, it is confirmed that it is shortened to about 30 seconds to 1 minute there was.

However, slight deviation may occur depending on the cause of failure. However, it has been possible to quantitatively measure to what extent the duty cycle time is shortened when the duty ratio is changed to some extent or how long the duty cycle time is shortened when the duty cycle is increased to some extent. In general, It can be seen that the time of occurrence of fever is in the predictable category according to the value of the value.

On the other hand, the control analyzing means 1700 analyzes the image of the photographed die 1 'through such a process to find out the coordinates where the heat is generated. The die 1' has a highly integrated structure, There is a limit in that it is difficult to clearly grasp the structure of the die 1 'due to the characteristics of a thermal camera using infrared rays.

In order to solve this problem, a solid immersion lens (SIL) 1300 is further provided on the optical path from the thermal camera 1200 to the die 1 '.

By photographing via the solid immersion lens, it is possible to precisely grasp the failure site of the die 1 '.

[Second Embodiment]

7 to 8, a die failure analyzing apparatus using a thermal camera according to this embodiment of the present invention will be described.

According to the embodiment described above, the wafer 1 determined to be defective in the final test process is fixed to the fixing means 1100, and the thermal camera 200 is used to mount the wafer 1 in the middle of the die 1 ' Although the die 1 'determined to be faulty is photographed, the defective die 1' is sacked and tested individually.

At this time, unlike the wafer 1, there arises a problem of alignment when the die 1 'is picked up and shot.

That is, since the wafer 1 has a number of dies 1 'arranged precisely, it is possible to easily test the dies 1' using a probe card without a separate alignment process, There is a fatal problem in that the structure of the die 1 'does not coincide with the coordinate value of the heating point found from the photographed image.

When the die 1 'is used by sowing, the dies 1' that are not defective can be commercialized instead of disposing the entire wafer 1, so that unnecessary discarding of the die 1 ' It can be minimized.

To this end, the fixing device 1100 of this embodiment includes a plate 1110 and a tilting means 1120. [ The plate 1110 has a plurality of chip mounters 1111 and a discharge hole 1112 is provided on the bottom surface of each chip mounter 1111.

7, the plate 1110 is provided with a plurality of chip mounters 1111 on which the sawed die is mounted.

On the other hand, the tilting means 1120 rotates the angle of the plate 1110 with a straight line perpendicular to the surface of the chip mount 1111 facing the bottom surface of the die 1 '.

Each of the chip mounts 1111 can be rotated or the plate 1110 can be rotated with respect to the center point of the chip mount 1111. [

On the other hand, the control analysis means 1700 photographs the die 1 'mounted on any one of the chip mounts 1111 using the thermal image camera 1200, and the photographed die 1' Is determined.

To this end, the position of the pads of the die 1 'may be photographed to determine the error angle from the difference between the position where the pads should be and the actual position.

When the error angle is determined, the control analysis means 1700 controls the tilting means 1120 to align the die 1 'to the reference position.

At this time, since it is necessary to fix the die 1 'during tilting by the tilting means 1120 or power supply by the needle 1400,

The control analyzing means 1700 generates an intake air flow from a vacuum hole 1112 provided in the bottom surface of each chip mounter 1111 to generate a suction air stream to fix the die 1 '.

When power supply to the die 1 'mounted on one of the chip mounters 1111 is completed and the photographing is completed, the control analyzing unit 1700 aligns the next chip mounter 1111 with the same process, And analyze the coordinates of the heat generation point.

On the other hand, when the information on each die 1 'mounted on the plurality of chip mounters 1111 is input, the control analysis means 1700 determines the coordinates of the pads corresponding to + and - of each die 1' The probe manipulator 1500 can be automatically controlled to bring the needle 1400 into contact with the pad.

Thus, the entire process described above can be automated.

That is, when the user sags and mounts the defective dies 1 'on a plurality of chip mounters 1111 and then executes the test, the alignment of each die 1' by the control of the control analyzing means 1700, The coordinate analysis process of the power application, the photographing, and the heat generation point is processed.

While the present invention has been described with reference to the accompanying drawings and embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. . Accordingly, the scope of the present invention should be determined only by the technical idea of the appended claims, and is not limited to the above embodiments.

The present invention can be applied to the field of semiconductor failure analysis equipment / semiconductor test equipment technology.

1: wafer
1 ': die
1 '': pad
1000: Die failure analyzer
1100: fixing means
1110: Plate
1111: Chip Mounter
1112:
1120: tilting means
1200: Thermal camera
1300: Solid immersion lens
1400: Needle
1500: probe manipulator
1600: Power Drive
1700: control analysis means

Claims (7)

Fixing means for fixing the wafer;
A thermal image camera for photographing a surface temperature distribution of the die included in the wafer fixed to the fixing means;
A pair of needles electrically contacting the pads of the die;
A probe manipulator for controlling a position of the needle according to a user operation;
A power drive for applying power to the die through the needle; And
And control analysis means for determining coordinates of a point at which the temperature is increased by a predetermined value or more from the photographed image of the thermal imaging camera with respect to the die to which power is supplied for a predetermined period of time. The method according to claim 1,
Wherein the control analyzing means controls the power drive to apply PWM power of the pulse width modulation type to the die and changes the duty ratio by a value obtained by multiplying the reference pulse width of the die by a constant value larger than 1 An apparatus for analyzing die failure using a thermal camera. The method according to claim 1,
The control analyzing means controls the power drive to apply power to the die and set a maximum current limit and apply a voltage of a magnitude that is obtained by multiplying the reference voltage of the die by a constant greater than 1, Device. The method according to claim 1,
And a solid immersion lens (SIL) is further provided on the optical path from the thermal image camera to the die. The method according to claim 1,
Fastening means for fastening two or more soaked dies;
A laminating camera for photographing a surface temperature distribution of one of the dies fixed to the fixing means;
A pair of needles electrically contacting the pads of the die;
A probe manipulator for controlling a position of the needle according to a user operation;
A power drive for applying power to the die through the needle; And
And control analysis means for determining coordinates of a point at which the temperature is increased by a predetermined value or more from the photographed image of the thermal camera with respect to the die to which power is supplied for a predetermined time,
The fastening means comprising: a plate having at least one chip mounter on which the sawed die is mounted; And
And tilting means for rotating the angle of the plate with a rotation axis perpendicular to the surface of the chip mount facing the die bottom,
Wherein the control analyzing means photographs a die mounted on any one of the chip mounts using a thermal imaging camera and determines an error angle between the photographed die and a predetermined reference position, An apparatus for analyzing die failure using a thermal camera to align alignment with position. 6. The method of claim 5,
Further comprising a discharge hole for generating a suction airflow on a bottom surface of each chip mounter,
The control analyzing means generates a suction airflow through the discharge hole as the die is mounted on the chip mounter, and the die breakdown is performed using a thermal camera which fixes the die while the plate is rotated by the tilting means or by the thermal camera Interpretation device. 6. The method of claim 5,
The control analyzing means automatically controls the probe manipulator by using the coordinates of the pads of the respective die as information of each die mounted on the plurality of chip mounters is inputted by the user so that the laths contacting the needles with specific pads of each die Die failure analysis using camera.

Images