JP5088093B2 - Defective bitmap data compression method, defective bitmap display method, and defective bitmap display device - Google Patents

Description

  The present invention relates to a compression method of defective bitmap data, a defective bitmap display method, and a defective bitmap display device, and in particular, keeps the logical information and physical quantity information related to the defective bits and classifies the defective modes. The present invention relates to a method for compressing defective bitmap data, a defective bitmap display method, and a defective bitmap display device, which are characterized by a technique for compression.

  Conventionally, in order to analyze which position bit is defective in a memory part of a DRAM or SRAM, or a semiconductor product such as a flash memory or a semiconductor product in which a semiconductor memory is embedded, a failure bit map (FBM: Fail) is analyzed. Bit Map) is used.

  This defective bit map reads the information written in the memory cells regularly arranged in a matrix, and indicates whether or not the read data matches the data that should have been written in the physical position of each memory cell. It is displayed in correspondence, and visually represents the failure analysis.

  The defect information of such a defective bitmap is increasing with the increase in the memory size mounted on the semiconductor chip, and the data is compressed in order to increase the storage memory (fail bitmap memory) and decrease the display speed. Various techniques have been proposed to do this.

For example, a method has been proposed in which the memory used is reduced by dividing the addresses of defective bits in both the X and Y directions without processing the entire memory (see, for example, Patent Document 1).
Alternatively, a method of compressing data by replacing a plurality of defective data having different addresses on the same line with one data has been proposed (for example, see Patent Document 2).

In addition, a method has been proposed in which good and bad data is held in a bit string such as (0001000) for a grid-like cell that is divided into vertical and horizontal areas and divided into (0001000).
It has also been proposed to compress a memory cell array into a plurality of blocks (for example, see Patent Document 4).

It is also proposed to compress from the XY coordinates of the four points of the XY coordinates for the first and last defective cells in the first row of the defective group and the XY coordinates for the first and last defective cells in the last row. (For example, see Patent Document 5).
Furthermore, a compression method using the lower left and upper right origin in the memory cell array has been proposed (see, for example, Patent Document 6).
JP 2001-052497 A Japanese Patent Laid-Open No. 06-231599 Japanese Patent Laid-Open No. 62-169342 JP 11-1111796 A Japanese Patent Laid-Open No. 06-181244 JP 2000-164666 A

However, in the case of the above-mentioned Patent Document 1, since the entire memory used cannot be reduced, there is a problem that a memory used as a defective bit memory requires a large capacity memory as the capacity of the semiconductor memory increases. is there.
Further, in the case of the above-mentioned Patent Document 2, there is a problem that compression cannot be performed depending on the type of failure mode.

In the case of the above-mentioned Patent Document 3, even if N is divided and reduced to 1 / N ² , the compression rate is 10 ⁻⁴ even when N = 100, and in the case of a memory having a Gbit capacity, it is enormous. A large amount of data is required, and the compressed data is compressed into the same format regardless of the failure mode in one block. Therefore, there is a problem in that useless memory is used depending on the failure mode.

Also, in the case of the above-mentioned Patent Document 4, there is a problem in that if there is even one defect in the partition, the entire partition is represented as defective, so that accurate failure mode classification cannot be performed.
In the case of the above-mentioned Patent Document 5, there is a problem that an accurate shape cannot be expressed when a defective bit block is not square but distorted.

  Further, in the case of the above-mentioned Patent Document 6, since compression is performed using a physical address, there is a problem that it is difficult to display logical information because it is not linked with logical information, and a logical failure mode is present. Even if they are different, there is a problem that there is a possibility of erroneous recognition that there is one defective block.

  Accordingly, an object of the present invention is to efficiently compress while classifying a failure mode while maintaining data of logical information and physical quantity information regarding the defective bit.

Now, with reference to FIG. 1, means for solving the problems in the present invention will be described.
See FIG. 1. In order to solve the above-described problem, the present invention provides a logical conversion step of converting defective bit data into logical information represented by a combination of logical BIT and logical word in a compression method of defective bitmap data. A physical conversion step for converting logical information into physical position information of defective bits represented by a combination of row and logical column, and a mode classification step for classifying the types of defective modes from the physical position information. It is characterized by having a step of separating into groups of defective bits for each mode and a step of converting into coordinate information as a group for each group of separated defective bits.

Thus, since the logical information is converted into the physical position information of the defective bit, the logical information related to the defective bit and the data of the physical quantity information are maintained, and the logical information is also displayed on the defective bit map. .
As described above, since the logical information of the defective bit and the physical information correspond one-to-one, the logical information can be calculated from the physical information, or the logical information can be added to the physical information. Therefore, logical information can also be displayed on the defective bitmap.

  In addition, after classifying the types of failure modes from physical position information, they are converted into coordinate information (XY coordinates) as a group, that is, by compressing, the failure bit groups of different failure modes are combined into one group. Since it is not displayed, it can be quickly displayed when displaying each failure mode.

  In this case, in the step of converting into the coordinate information as a group for each group of defective bits, the group of defective bits is divided into a plurality of rectangular groups, and defective bits at positions on both ends of the diagonal line are divided for each divided rectangular group. It is desirable to convert to coordinate information.

In this way, by dividing the group of defective bits into rectangles, that is, squares, the divided rectangles are divided into positions at both ends on the diagonal line, specifically, the physical positions of the lower left memory bit and the upper right memory cell. Since it can be expressed, the amount of information to be displayed is small and efficient expression can be achieved.
In addition, since it is different from data compressed by a data compression technique such as a mathematical compression method, it does not require time and effort for decompression.

In this case, when dividing the group of defective bits into a plurality of rectangular groups, all the divided rectangular groups are made smaller than the group of defective bits, that is, the group of defective bits becomes a plurality of small rectangular groups. Alternatively, it may be divided into a rectangular group larger than a group of defective bits and a rectangular group having a small difference.
Note that the number of divided rectangular groups is more efficient when the amount of information to be displayed is smaller.
In addition, it is desirable to divide the group of defective bits into a plurality of rectangles based on the type of defective mode.

In addition, it is desirable to automatically classify the mode classification process for classifying the types of failure modes from physical location information using a failure mode classification algorithm determined in advance based on empirical rules, so that the mode classification process can be performed quickly. Can do.
This failure mode refers to various failure modes obtained by previous failure bit analysis, for example, block failure, pair bit failure, word line failure, bit line failure, single bit failure, cross failure, or bit failure. There is a partial line failure, and it is highly possible that a new failure mode appears with an increase in memory capacity. Therefore, it is necessary to determine the failure mode based on experience.

  In addition, since the compression method of such defective bitmap data is a compression method for each defective mode, not only the compression effect but also the same compression method as the defective mode, the defective bit is used using the data compressed in this way. When the map is displayed on the display unit, the display speed is also improved.

In addition, a logical conversion means for converting defective bit data into logical information represented by a combination of logical BIT and logical word, and logical information as physical position information of the defective bit represented by a combination of row and logical Column. Physical conversion means for conversion, mode classification means for classifying the type of defective mode from physical position information, separation means for separating into groups of defective bits for each classified mode, and group for each group of separated defective bits Defective bit capable of promptly displaying a defective bit map by comprising coordinate information converting means for converting to coordinate information and a display unit for displaying a defective bit map using compressed data converted into coordinate information A map data display device can be realized.
In this case, the above-described series of compression steps is performed in a computer, typically a personal computer, and display of defective bitmap data as a compression result is displayed by a display unit connected to the computer.

  According to the present invention, since the compression for each defective mode is performed while retaining the logical information and the physical quantity information regarding the defective bits, not only the compression effect but also the display speed is improved.

Here, an embodiment of the present invention will be described with reference to FIGS.
Again see Figure 1
FIG. 1 is a flowchart of a defective bitmap data compression method and a defective bitmap display method according to an embodiment of the present invention, and description will be given along this flowchart.
a. First, defective bit data (Fail data) is converted into logical information.
In the measurement of the defective bit data, a plurality of chips in the wafer are measured, and one or a plurality of memory macros in the chips are measured.

The defective bit data in this case is data indicating whether an output expected to be output when a test pattern is input to the memory cell is obtained, and is converted into logic information.
The defective bit data includes data indicating a chip position and data indicating a memory macro.

See Figure 2
FIG. 2 is an explanatory diagram of logical information of a defective bit and its physical arrangement. The logical BIT is composed of a memory cell group physically arranged in a matrix, and the memory is composed of a plurality of logical BITs. FIG.
Here, the logical BIT and the logical column are arranged in order from 0, but it is added that a discontinuous arrangement can be configured in addition to ascending order and descending order depending on the type of memory.

  The logical information converted from the defective bit data is a combination of the logical BIT and the logical word, that is, the logical information of the defective bit in the form of (logic BIT, logical word) in the chip position and the memory macro name.

For example, the logical information of the 6 and 4 bad BIT groups shown in FIG. 2 includes the chip position and the memory macro name,
(Logic BIT, logic word) = (1,17), (1,18), (1,22), (1,23), (1,27), (1,28)
(Logic BIT, logic word) = (3, 13 ), (3, 18 ), (3, 23 ), (3, 28 )
It is expressed.

b. Next, such logical information is converted into physical information. In this case, the physical information regarding the defective bit is represented by a combination of row and logical column, that is, in the form of (row, logical column).
For example, the physical information of the 6 and 4 bad BIT groups shown in FIG.
BIT = 1 (row, logical column) = (3,1), (3,2), (4,1), (4,2), (5,1), (5,2)
BIT = 3 (row, logical column) = (2,2), (3,2), (4,2), (5,2)
Is converted to
The row of the physical information and the logical column indicate a physical positional relationship in the logical BIT.
Here, since the chip position and the memory macro name are common , the display is omitted.

c. Next, the failure mode is classified based on the physical information of the failure bit.
As a failure mode in this case, various failure modes obtained by the failure bit analysis so far, for example, block failure, pair bit failure, word line failure, bit line failure, single bit failure, cross failure, or bit line Some defects are listed.

d. Since these defective modes physically convert defective bit data, the converted physical information is automatically classified by a defective mode classification algorithm determined by comparing with the empirical rules accumulated conventionally.
The data after the classification includes a group of a chip position, a memory macro name, a failure mode name, a serial number for each failure mode, and a failure bit.

e. Next, data compression is performed for each separated defective bit group.
Again see Figure 2
The defective bit group shown in FIG. 2 is a case where there are two defective bit groups having the same defective mode. If a total of ten defective bits are designated as they are, 10 sets of data are required. By specifying the defective bit positions at both ends of the diagonal line every time, only a total of four sets of data are required, and the data is compressed because the number of data is reduced.
Here, since the two failure modes are both rectangular, the compression unit and the failure mode classification are the same.

For example, the defective bit groups shown in FIG.
(1,3,1)-(1,5,2) (3,2,2)-(3,5,2)
Express as
Here, the first numerical value in () indicates the value of the logical BIT, and the next two numerical values indicate the row and logical column of the physical information, and these two sets of data are defective bits at both ends of the diagonal line. The lower left and upper right of the group are represented, and the group of defective bits is represented by these two sets of numerical values.

In this case, the lower left-upper right representation of the group of bad bits represents all the cells in the square, so that it can be expressed efficiently, and specially by a data compression technique such as a mathematical compression method. Since it is not compressed data, the time for decompression is not necessary, so the display speed is increased.
Further, this physical information holds data together with logical information at the time of physical conversion.

However, if the defective bit group is not a square, the above expression cannot be applied immediately, so the defective bit group is divided into a plurality of squares, and each divided group is expressed by the lower left-upper right.
This will be described with reference to FIG.

See Figure 3
FIG. 3 is an explanatory diagram of a method of dividing and compressing one defective bit group into a plurality of rectangles,
The logical information of the defective cell in this case is
(Logical BIT, logical word) = (2, 17), (3, 17), (3, 18), (4, 27), (4, 28)
Is represented by two rectangles,
(2,3,1)-(2,5,1)
(2,4,2)-(2,5,2)
Or (2,3,1)-(2,3,1)
(2,4,1)-(2,5,2)
Express by compressing.

The data after classification in the above step d is
Chip position, memory macro name, failure mode name, serial number for each failure mode, lower left logical information, upper right logical information.
However, this data becomes one or a plurality of data with respect to one data of the data after classification in the above-mentioned step d.

f. Such data compression for each failure mode is performed for all failure modes.
The data subjected to coordinate transformation is recorded in a computer-readable recording medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, or a semiconductor memory.

After performing the above-described series of steps in a computer, typically a personal computer,
g. Finally, based on the recorded data compressed data, the FBM is displayed based on the arrangement information (X and Y positions in the chip) of each memory cell of the memory macro in the chip.

In this case, the FBM is displayed on a display device connected to the computer.
In this case, although the display is based on the data compressed as described above, there is no need for decompression, and the memory cells in the rectangular area designated by the lower left-upper right are displayed as defective bits. Only.
In addition, the number of times that consecutive defective bits are converted into the X and Y coordinates in the chip can be reduced.

  Further, when displaying, since one compressed group is not separated into different modes, for example, when displaying a cross failure mode, it is only necessary to represent only the group belonging to this, and the processing speed Can be expressed quickly.

Based on the above, next, a compression method of defective bitmap data according to the first embodiment of the present invention will be described with reference to FIG.
See Figure 4
FIG. 4 is an explanatory diagram of a method for compressing defective bitmap data according to the first embodiment of the present invention. Here, a case where the failure mode is a cross failure will be described.
The cross failure is a failure mode caused by a failure of a memory cell located at the intersection of a defective bit line and a defective word line.

First, the cross defect shown in the upper diagram is divided into three blocks as shown in the lower diagram, and (X, Y) coordinate transformation is performed for each block using the expression of lower left-upper right.
For example, for bit lines represented by ■, ▲, and ●,
(0,4,0)-(4,4,4)
(2,5,1)-(2,6,1)
(2,0,1)-(2,3,1)
Convert to

Next, a method for compressing defective bitmap data according to the second embodiment of the present invention will be described with reference to FIG.
See Figure 5
FIG. 5 is an explanatory diagram of a method for compressing defective bitmap data according to the second embodiment of the present invention. Here, a case where a bit line is partially defective will be described.
Note that part of the bit line is a failure mode that occurs when there is a problem with the drive capability of the peripheral circuit, and good bits also appear on the side close to the drive circuit, but all memory cells at locations away from the drive circuit Bad bit.

First, the cross defect shown in the upper diagram is divided into three blocks as shown in the lower diagram, and (X, Y) coordinate transformation is performed for each block using the expression of lower left-upper right.
For example, for bit lines represented by ■, ▲, and ●,
(0,4,0)-(3,4,0)
(3,4,2)-(4,4,0)
(4,4,2)-(4,4,4)
Convert to

Next, a method for compressing defective bitmap data according to the third embodiment of the present invention will be described with reference to FIG.
See FIG.
FIG. 6 is an explanatory diagram of a method for compressing defective bitmap data according to the third embodiment of the present invention. Here, although it is physically compressible as a group, it is actually a case where a defect is caused by a different cause. explain.
For example, in the case of FIG. 6, the logical BIT1 is a group of defective bits caused by a peripheral circuit near the input / output terminal in the RAM macro or a circuit outside the RAM macro, and the logical BIT2 is a peripheral bit in the RAM macro. This is a group of defective bits generated due to a circuit.

When this bad bit group is compressed without being separated for each bad mode,
(1,0,0)-(2,6,0)
However, different failure modes are mixed.

Therefore, the defective bit group shown in the upper diagram is divided into two blocks as shown in the lower diagram, and (X, Y) coordinate conversion is performed for each block by the expression of lower left-upper right.
For example, for bit lines represented by ■ and ▲,
(1,0,0)-(1,6,4)
(2,0,0)-(2,6,0)
Convert to

  The embodiment and each example of the present invention have been described above, but the present invention is not limited to the configurations and conditions described in the embodiment and each example, and various modifications are possible. For example, in the above embodiment, the distorted defective bit group is divided into a plurality of small square groups, but a large square containing the distorted defective bit group and a square with a small difference therebetween. It may be expressed.

For example, in the case of FIG.
(2,3,1)-(2,5,2)
(2,3,2)-(2,3,2) (good bit flag)
The region represented as a good bit from the first representing the large square containing the defective bit group may be represented with a flag in order to represent it as a square with a small difference.

3 is a flowchart of a defective bitmap data compression method and a defective bitmap display method according to an embodiment of the present invention. It is explanatory drawing of the logic information of a defective bit. It is explanatory drawing of the division | segmentation / compression method of a defective bit group. It is explanatory drawing of the compression method of the defect bitmap data of Example 1 of this invention. It is explanatory drawing of the compression method of the defect bitmap data of Example 2 of this invention. It is explanatory drawing of the compression method of the defect bitmap data of Example 3 of this invention.

Claims (6)

A logical conversion step of converting defective bit data into logical information represented by a combination of logical BIT and logical word ;
A physical conversion step of converting the logical information into physical position information of the defective bit represented by a combination of row and logical column ;
A mode classification step of classifying the types of failure modes from the physical position information;
Separating into groups of defective bits for each classified mode;
And a step of converting the group of the separated defective bits into coordinate information as the group. The step of converting into the coordinate information is characterized by dividing the group of defective bits into a plurality of rectangular groups and converting into coordinate information of defective bits at positions on both ends of the diagonal line for each of the divided rectangular groups. The method of compressing defective bitmap data according to claim 1. 3. The method of compressing defective bitmap data according to claim 2, wherein the division is executed such that each of the plurality of rectangular groups is smaller than the group of defective bits. 4. The method of compressing defective bitmap data according to claim 2, wherein the dividing is performed by dividing the group of defective bits into a plurality of rectangles based on the type of the defective mode. 5. A defective bitmap display method, wherein a defective bitmap is displayed on a display unit using data compressed by the defective bitmap data compression method according to any one of claims 1 to 4. Logical conversion means for converting defective bit data into logical information represented by a combination of logical BIT and logical word ;
Physical conversion means for converting the logical information into physical position information of the defective bit represented by a combination of row and logical column ;
Mode classification means for classifying the type of failure mode from the physical position information;
Separating means for separating into groups of defective bits for each classified mode;
Coordinate information conversion means for converting the group of the separated defective bits into coordinate information as the group;
A defective bit map data display device comprising: a display unit that displays a defective bit map using the compressed data converted into the coordinate information.

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