Patent Application
20110172941
This application is based upon and claims the benefit of the priority of Japanese patent application No. 2010-005920, filed on Jan. 14, 2010, the disclosure of which is incorporated herein in its entirety by reference thereto.
The present invention relates to a screening apparatus, a screening method, and a program for screening integrated circuits. In particular, it relates to a screening apparatus, a screening method, and a program for screening integrated circuits each having unique characteristics.
Conventionally, integrated-circuit screening apparatuses are used for screening semiconductor devices manufactured on semiconductor wafers to determine defective devices.
For example, based on a screening apparatus disclosed in Patent Document 1, as illustrated in
Patent Document 1: Japanese Patent Kokai Publication No. JP-P2008-2900A (FIG. 1)
The entire disclosure of above Patent Document 1 is incorporated herein by reference thereto. The following analysis has been given by the present invention.
However, when such a conventional screening apparatus screens semiconductor devices assembled (manufactured) from cut-out semiconductor devices (chips), instead of from semiconductor devices (chips) on a semiconductor wafer, high-precision screening may not be possible.
This is because, since measured values of a semiconductor device (DUT) are highly sensitive to conditions under which the semiconductor device is manufactured, if manufacturing conditions are different, distribution of measured values is also greatly varied. Namely, since semiconductor devices (chips) on a single semiconductor wafer are manufactured under the same manufacturing conditions, a distribution of measured values of the semiconductor devices (chips) on the semiconductor wafer falls within a narrow range. However, if semiconductor devices (chips) are manufactured from different semiconductor wafers, the manufacturing conditions of the semiconductor devices cannot be identical. Thus, a distribution of measured values of each of the semiconductor devices varies and spreads in a certain wide range. As described above, based on the screening technique, if a semiconductor device exhibits measured values that deviate from a distribution, the semiconductor device is determined to be defective. This screening technique is effective if semiconductor devices from a single semiconductor wafer having the same manufacturing conditions are screened. However, if semiconductor devices from different semiconductor wafers having different manufacturing conditions are screened, the above screening technique is not effective at all. Normally, a plurality of semiconductor devices of a single lot (product unit) include semiconductor devices manufactured from semiconductor devices (chips) on different semiconductor wafers, and a distribution of the measured values often spreads in a wide range. Therefore, the technique of detecting outliers from such distribution and determining quality of semiconductor devices may not enable high-precision screening. Thus there is much to be desired in the art.
It is an object of the present invention to provide a screening apparatus, a screening method, and a program that enable high-precision screening even when semiconductor devices manufactured under different manufacturing conditions are screened.
In a first aspect of the present invention, there is provided a screening apparatus comprising: a measurement unit measuring characteristics of a semiconductor device and reading an identification code allocated to the semiconductor device; a database storing a table representing a correspondence between an identification code and a fabrication condition of a semiconductor device; a conversion unit extracting, based on the identification code sent from the measurement unit, a fabrication condition associated with the identification code from the database and associating the extracted fabrication condition with the characteristics corresponding to the fabrication condition; a characteristics reconstruction unit classifying the characteristics according to the fabrication condition sent from the conversion unit; and an evaluation and analysis unit evaluating and analyzing the characteristics classified by the characteristics reconstruction unit according to the fabrication condition in a predetermined manner and determining a semiconductor device to be screened.
It is preferable that the screening apparatus according to the present invention further include: an inverse conversion unit extracting, based on the fabrication condition of the semiconductor device to be screened determined by the evaluation and analysis unit, a corresponding identification code associated with the fabrication condition from the database and outputting the extracted identification code.
Based on the screening apparatus according to the present invention, it is preferable that the conversion unit associate the extracted fabrication condition with the characteristics and the identification code corresponding to the extracted fabrication condition and the characteristics reconstruction unit classify the characteristics and the identification code according to the fabrication condition.
Based on the screening apparatus according to the present invention, it is preferable that the measurement unit include a measurement apparatus measuring characteristics of the semiconductor device and a reader reading an identification code allocated to the semiconductor device.
Based on the screening apparatus according to the present invention, it is preferable that the evaluation and analysis unit analyze the characteristics classified according to the fabrication conditions and determine a semiconductor device exhibiting characteristics that deviate from a distribution to be a semiconductor device to be screened.
Based on the screening apparatus according to the present invention, it is preferable that at least the conversion unit, the characteristics reconstruction unit, and the evaluation and analysis unit be realized by a calculator executing a program.
It is preferable that the screening apparatus according to the present invention further include a second database storing characteristics and a fabrication condition of a past semiconductor device and the characteristics reconstruction unit send the characteristics and the fabrication condition sent from the conversion unit to the second database and update data in the second database.
Based on the screening apparatus according to the present invention, it is preferable that the characteristics reconstruction unit extract necessary data from the second database and classify the characteristics according to the fabrication condition based on the extracted necessary data.
In a second aspect of the present invention, there is provided a screening method comprising: measuring characteristics of a semiconductor device and reading an identification code allocated to the semiconductor device; extracting, based on the read identification code, a fabrication condition associated with the identification code from a database storing a table representing a correspondence between an identification code and a fabrication condition of a semiconductor device and associating the extracted fabrication condition with the characteristics corresponding to the fabrication condition; classifying the characteristics according to the fabrication condition; and evaluating and analyzing the characteristics classified according to the fabrication condition in a predetermined manner and determining a semiconductor device to be screened.
It is preferable that the screening method of the present invention further include adding the characteristics and the fabrication condition to the second database between associating the fabrication condition with the characteristics corresponding to the fabrication condition and classifying the characteristics.
In a third aspect of the present invention, there is provided a program that causes a calculator (or computer) to execute: measuring characteristics of a semiconductor device, reading an identification code allocated to the semiconductor device, extracting, based on the read identification code, a fabrication condition associated with the identification code from a database storing a table representing a correspondence between an identification code and a fabrication condition of a semiconductor device, and associating the extracted fabrication condition with the characteristics corresponding to the fabrication condition; classifying the characteristics according to the fabrication condition; and evaluating and analyzing the characteristics classified according to the fabrication condition in a predetermined manner and determining a semiconductor device to be screened.
It is preferable that the program of the present invention cause the calculator (or computer) to execute adding the characteristics and the fabrication condition to the second database between associating the fabrication condition with the characteristics corresponding to the fabrication condition and classifying the characteristics.
The meritorious effects of the present invention are summarized as follows.
According to the present invention, even when semiconductor devices manufactured under different fabrication conditions (manufacturing conditions) are screened, high-precision screening can be executed. This is because, since various characteristics of a semiconductor device are highly sensitive to fabrication conditions (manufacturing conditions), if a single lot includes semiconductor devices manufactured under many different fabrication conditions (manufacturing conditions), a distribution of characteristics (measured values) of the semiconductor devices naturally spreads in a wide range. Thus, based on a conventional screening apparatus that simply determines a semiconductor device exhibiting characteristics (measured values) that deviate from a distribution to be defective, it is difficult to determine whether the measured values deviate from a distribution. However, if fabrication conditions (manufacturing conditions) are classified, a distribution of characteristics (measured values) falls within a certain narrow range, outliers of the distribution can easily be determined. Namely, if fabrication conditions (manufacturing conditions) are extracted based on identification codes (IDs) of semiconductor devices and a distribution of characteristics (measured values) is created for the corresponding fabrication conditions (manufacturing conditions), the distribution of characteristics (measured values) falls within a certain narrow range. Thus, a semiconductor device having characteristics (measured values) that deviate from a distribution can easily be determined.
A screening apparatus according to exemplary embodiment 1 of the present invention includes: a measurement unit (1 of
A screening method according to exemplary embodiment 2 of the present invention includes: measuring characteristics of a semiconductor device and reading an identification code allocated to the semiconductor device (step A1 of
A program according to exemplary embodiment 3 of the present invention causes a calculator to execute: measuring characteristics of a semiconductor device, reading an identification code allocated to the semiconductor device, extracting, based on the read identification code, a fabrication condition associated with the identification code from a database storing a table representing a correspondence between an identification code and a fabrication condition of a semiconductor device, and associating the extracted fabrication condition with the characteristics corresponding to the fabrication condition (step A3 of
Note that the reference symbols mentioned in the above description of the exemplary embodiments are intended merely for better understanding and illustration and should not be regarded as limitative. In the following examples are described with reference to the Drawings.
A screening apparatus according to example 1 of the present invention will be described with reference to the drawings.
In
The measurement unit 1 measures characteristics such as an output signal, an output voltage, and an output current from integrated circuits of the DUTs 5. The measurement unit 1 can be electrically connected to the DUTs 5 (terminals thereof) via a probe or the like and can apply an appropriate signal, voltage, and current to the DUTs 5. Further, the measurement unit 1 can set operation environments (the temperature, etc.) of the DUTs 5. By measuring values (physical values) such as an output signal, an output voltage, and an output current from the DUTs 5 under such environments, the measurement unit 1 evaluates the measured values (physical values) of the DUTs 5, and based on results of the evaluation, determines quality of each of the DUTs 5 of a lot. In addition, when evaluating and determining the DUTs 5, the measurement unit 1 can read an identification code (ID) uniquely allocated to each of the DUTs 5. The measurement unit 1 is connected to the conversion unit 2, so that the measurement unit 1 can communicate with the conversion unit 2. The measurement unit 1 sends the measured values (physical values such as current values, voltage values, and frequencies) obtained during the inspection of the DUTs 5 to the conversion unit 2, along with the IDs and the determination results.
The conversion unit 2 converts the inputted IDs into corresponding diffusion conditions. Namely, based on the IDs sent from the measurement unit 1, the conversion unit 2 extracts diffusion conditions associated with the IDs from the database 6. The conversion unit 2 is connected to the database 6 (a storage unit (not illustrated) storing the database 6) and the measured-value reconstruction unit 3, so that the conversion unit 2 can communicate with the database 6 and the measured-value reconstruction unit 3. The conversion unit 2 associates the extracted diffusion conditions with corresponding measured values (physical values), determination results, and IDs and sends these associated data to the measured-value reconstruction unit 3.
The measured-value reconstruction unit 3 reconstructs the inputted measured values based on the diffusion conditions. Namely, based on the diffusion conditions sent from the conversion unit 2, the measured-value reconstruction unit 3 classifies (groups) the measured values (physical values) and the determination results sent from the conversion unit 2 according to the diffusion conditions. The measured-value reconstruction unit 3 is connected to the conversion unit 2 and the evaluation and analysis unit 4, so that the measured-value reconstruction unit 3 can communicate with the units 2 and 4. The measured-value reconstruction unit 3 sends the measured values (physical values) and the determination results classified according to the diffusion conditions to the evaluation and analysis unit 4.
The evaluation and analysis unit 4 analyzes the inputted determination results and measured values (physical values) classified according to the diffusion conditions and evaluates whether each of the DUTs 5 exhibits measured values (physical values) that deviate from a distribution. Namely, the evaluation and analysis unit 4 analyzes the determination results and the measured values (physical values) that are classified according to the diffusion conditions and that are sent from the measured-value reconstruction unit 3 and determines DUTs 5 each exhibiting measured values (physical values) that deviate from a distribution. The evaluation and analysis unit 4 is connected to the measured-value reconstruction unit 3 and the inverse conversion unit 7, so that the evaluation and analysis unit 4 can communicate with these units 3 and 7. The evaluation and analysis unit 4 sends DUT information (including diffusion conditions, determination results, and physical values) about the DUTs 5 each exhibiting measured values (physical values) that deviate from a distribution to the inverse conversion unit 7.
The inverse conversion unit 7 converts the inputted diffusion conditions into corresponding IDs. Namely, based on the DUT information sent from the evaluation and analysis unit 4, the inverse conversion unit 7 extracts corresponding IDs from the database 6. The inverse conversion unit 7 is connected to the evaluation and analysis unit 4 and the database 6 (a storage unit (not illustrated) storing the database 6), so that the inverse conversion unit 7 can communicate with these units 4 and 6. The inverse conversion unit 7 outputs (displays, prints, etc.) the extracted IDs as screening results 8.
The database 6 stores information including a table that represents a correspondence between IDs and diffusion conditions (production conditions such as diffusion lot names, wafer numbers, and information about intra-wafer positions) associated with the IDs. The database 6 is stored in a storage unit (not illustrated) and is used to search for the diffusion conditions from the IDs and for the IDs from the diffusion conditions.
Next, an operation of the screening apparatus according to example 1 of the present invention will be described with reference to the drawings.
First, the measurement unit (1 of
Next, the measurement unit (1 of
Next, based on the IDs of all of the DUTs (5 of
Next, the measured-value reconstruction unit (3 of
Next, after receiving information (a collection of pieces of information about the DUTs classified into groups according to the diffusion conditions) from the measured-value reconstruction unit (3 of
Next, the evaluation and analysis unit (4 of
Finally, the inverse conversion unit (7 of
According to example 1, the diffusion conditions (manufacturing conditions) are extracted based on the IDs of DUTs, measured values (physical values) of the DUTs are classified into groups according to the manufacturing conditions, and a distribution of measured values (physical values) is created for each group. In this way, since each of the distributions of the measured values (physical values) falls within a certain narrow range, a semiconductor device exhibiting measured values (physical values) that deviate from a distribution can be easily determined. Thus, high-precision screening of the DUTs is enabled.
If the measured values (physical values) of all the DUTs included in a single lot are used as a population for evaluation and analysis and if DUTs each exhibiting measured values (physical values) that deviate from a distribution are determined without classifying the measured values (physical values) according to the diffusion conditions, since the DUTs included in the single lot are likely to include devices with various diffusion conditions, each of the distributions of the measured values (physical values) often becomes widespread. Thus, since it is difficult to determine DUTs each exhibiting measured values (physical values) that deviate from a distribution, appropriate screening cannot be executed. In contrast, as in example 1, if the measured values (physical values) are classified according to the diffusion conditions, for example, if a distribution of measured values (physical values) of DUTs included in the same diffusion lot and manufactured on a chip of the same wafer is created, the distribution falls within a narrow range. Thus, since DUTs each exhibiting measured values (physical values) that deviate from a distribution can easily be determined, appropriate screening can be executed.
A screening apparatus according to example 2 of the present invention will be described with reference to the drawings.
Example 2 is a variation of example 1, and the screening apparatus according to example 2 realizes the units (1 to 4 and 7 of
The LSI tester 11 is a measurement apparatus for measuring a voltage and a current of an integrated circuit such as an LSI (see
The calculator 12 is a computer performing calculation and information processing by executing the program 16 based on the information sent from the LSI tester 11 (see
The calculator 12 executes the program 16 to realize an ID-to-diffusion-information conversion unit 12a, a diffusion conditions-classified measured-value reconstruction unit 12b, an evaluation and analysis unit 12c, and a diffusion-information-to-ID conversion unit 12d.
Based on the IDs sent from the LSI tester 11, the ID-to-diffusion-information conversion unit 12a extracts diffusion conditions associated with the IDs from the database 15, associates the extracted diffusion conditions with the measured values (physical values) and the determination results, and sends the associated data to the diffusion-condition-classified-measured-value reconstruction unit 12b.
Next, the diffusion-condition-classified-measured-value reconstruction unit 12b classifies (groups) the measured values (physical values) and the determination results sent from the ID-to-diffusion-information conversion unit 12a according to the diffusion conditions sent from the ID-to-diffusion-information conversion unit 12a. The diffusion-condition-classified-measured-value reconstruction unit 12b then sends the measured values (physical values) and the determination results classified according to the diffusion conditions to the evaluation and analysis unit 12c.
Next, the evaluation and analysis unit 12c analyzes the determination results and the measured values (physical values) classified according to the diffusion conditions and sent from the diffusion-condition-classified-measured-value reconstruction unit 12b, to determine DUTs 14 each exhibiting measured values (physical values) that deviate from a distribution. The evaluation and analysis unit 12c then sends DUT information (including diffusion conditions, determination results, and physical values) about the DUTs 14 each exhibiting measured values (physical values) that deviate from a distribution to the diffusion-information-to-ID conversion unit 12d.
Based on the DUT information sent from the evaluation and analysis unit 12c, the diffusion-information-to-ID conversion unit 12d searches the database 15 to extract corresponding IDs and outputs (displays, prints, etc.) the extracted IDs as the screening results 13.
Each of the DUTs 14 is a semiconductor device that has a unique number (ID) distinguishable from those of any other DUTs 14.
In addition, in the form of a correspondence table, the database 15 stores information about diffusion conditions set when the DUTs 14 having IDs are manufactured. The information includes unique diffusion lot numbers, wafer numbers, and intra-wafer positions, for example. Such information is used when the diffusion conditions are extracted based on the IDs or when the IDs are extracted based on the diffusion conditions.
Next, an operation of the screening apparatus according to example 2 of the present invention will be described with reference to the drawings.
First, the LSI tester (11 of
Next, the ID-to-diffusion-information conversion unit (12a of
Next, the diffusion-condition-classified-measured-value reconstruction unit (12b of
Next, the evaluation and analysis unit (12c of
Next, the diffusion-information-to-ID conversion unit (12d of
Finally, the diffusion-information-to-ID conversion unit (12d of
While the calculator (12 of
Example 2 provides similar meritorious effects as those provided by example 1.
A screening apparatus according to example 3 of the present invention will be described with reference to the drawings.
The screening apparatus according to example 3 is a variation of the screening apparatus according to example 2 (see
Example 3 provides similar meritorious effects as those provided by example 2.
A screening apparatus according to example 4 of the present invention will be described with reference to the drawings.
The screening apparatus according to example 4 is a variation of the screening apparatus according to example 2. When compared with the units (12a to 12d of
Example 4 provides similar meritorious effects as those provided by example 2.
A screening apparatus according to example 5 of the present invention will be described with reference to the drawings.
The screening apparatus according to example 5 is a variation of the screening apparatus according to example 1. When compared with the screening apparatus according to example 1 (see
The measured-value database 9 includes a database established based on IDs. More specifically, the measured-value database 9 stores measured values (physical values), determination results, diffusion conditions, and IDs of the DUTs 5 obtained in the past. The measured-value reconstruction unit 3 is connected to the storage unit (not illustrated) storing the above information, so that the measured-value reconstruction unit 3 can communicate with the storage unit.
The measured-value reconstruction unit 3 sends the diffusion conditions, the measured values (physical values), the determination results, and the IDs sent from the conversion unit 2 to the measured-value database 9 and updates the database in the measured-value database 9. Further, the measured-value reconstruction unit 3 acquires necessary data (physical values, determination results, diffusion conditions, and IDs) from the measured-value database 9, classifies the acquired data according to the diffusion conditions, and sends the classified data to the evaluation and analysis unit 4.
Next, an operation of the screening apparatus according to example 5 of the present invention will be described with reference to the drawings.
First, the measurement unit (1 of
Next, the measurement unit (1 of
Next, based on the IDs of all of the DUTs (5 of
Next, the measured-value reconstruction unit (3 of
Next, based on the diffusion conditions, the measured-value reconstruction unit (3 of
Next, the measured-value reconstruction unit (3 of
Next, after receiving information (a collection of pieces of information about the DUTs classified into groups according to the diffusion conditions) from the measured-value reconstruction unit (3 of
Next, the evaluation and analysis unit (4 of
Finally, the inverse conversion unit (7 of
According to example 5, measured values of all the DUTs (5 of
A screening apparatus according to example 6 of the present invention will be described with reference to the drawings.
Example 6 is a variation of example 5, and the screening apparatus according to example 6 realizes the units (1 to 4 and 7 of
The calculator 12 is connected to the measured-value database (a storage apparatus storing the measured-value database 18) storing previously measured physical values as a database, so that the calculator 12 can communicate with the measured-value database 18. The calculator 12 can freely access the measured-value database 18. The calculator 12 executes the program 16 to realize the ID-to-diffusion-information conversion unit 12a, the measured-value update unit 12e, the diffusion-condition-classified-measured-value reconstruction unit 12b, the evaluation and analysis unit 12c, and the diffusion-information-to-ID conversion unit 12d.
The measured-value update unit 12e sends the diffusion conditions, the measured values (physical values), the determination results, and the IDs sent from the ID-to-diffusion-information conversion unit 12a to the measured-value database 18 and updates the database in the measured-value database 18. Next, the diffusion-condition-classified-measured-value reconstruction unit 12b extracts necessary data (physical values, determination results, diffusion conditions, and IDs) from the measured-value database 18. Based on the diffusion conditions included in the acquired data, the diffusion-condition-classified-measured-value reconstruction unit 12b then classifies (groups) the measured values (physical values) and the determination results included in the acquired data according to the diffusion conditions and sends the measured values (physical values) and the determination results classified according to the diffusion conditions to the evaluation and analysis unit 12c.
Other functions and units in the calculator 12 are the same as those of the calculator (12 of
Next, an operation of the screening apparatus according to example 6 of the present invention will be described with reference to the drawings.
First, the LSI tester (11 of
Next, the ID-to-diffusion-information conversion unit (12a of
Next, the measured-value update unit (12e of
Next, the diffusion-condition-classified-measured-value reconstruction unit (12b of
Next, the evaluation and analysis unit (12c of
Next, the diffusion-information-to-ID conversion unit (12d of
Finally, the diffusion-information-to-ID conversion unit (12d of
While the calculator (12 of
Example 6 provides similar meritorious effects as those provided by example 5.
Modifications and adjustments of the exemplary embodiments and examples are possible within the scope of the overall disclosure (including claims) of the present invention and based on the basic technical concept of the invention. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the overall disclosure including the claims and the technical concept.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-005920 | Jan 2010 | JP | national |
