JP4789993B2 - Memory failure relief analysis method and memory test apparatus equipped with failure relief analyzer to which this analysis method is applied - Google Patents

Description

  The present invention relates to an improvement of a memory failure relief analyzer that can test a memory composed of a semiconductor integrated circuit or the like and analyze a method for relieving a memory failure by a spare line for relief, and particularly relates to an address of a defective cell. The present invention proposes a failure remedy analysis method capable of shortening the time for specifying the memory and a memory test apparatus equipped with a failure remedy analyzer that operates using this failure remedy analysis method.

  FIG. 5 shows a schematic configuration of the memory test apparatus. In the figure, TES indicates the entire memory test apparatus. The memory test apparatus TES includes a main controller 111, a pattern generator 112, a timing generator 113, a waveform formatter 114, a logic comparator 115, a driver 116, an analog comparator 117, a failure analysis memory 118, a failure relief analyzer 120, a logic An amplitude reference voltage source 121, a comparison reference voltage source 122, a device power source 123, and the like are included. Although FIG. 5 shows a configuration for one terminal of the memory under test 119, in reality, there are as many terminals as the number of terminals of the memory under test 119.

  The main controller 111 is generally constituted by a computer system. The main controller 111 mainly controls the pattern generator 112 and the timing generator 113 according to a test program created by a user, and generates test pattern data from the pattern generator 112. Data is converted into a test pattern signal having an actual waveform by the waveform formatter 114, and this test pattern signal is applied to the IC under test through a driver 116 that amplifies the voltage into a waveform having an amplitude value set by the logic amplitude reference voltage source 121. Remember.

  The response signal read from the memory under test 119 is compared with the reference voltage supplied from the comparison reference voltage source 122 by the analog comparator 117, and whether or not it has a predetermined logic level (H logic voltage, L logic voltage). The signal determined to have a predetermined logic level is compared with the expected value output from the pattern generator 112 by the logic comparator 115, and if there is a mismatch with the expected value, the memory of the read address It is determined that there is a defect in the cell, a defect address is stored in the defect analysis memory 118 every time a defect occurs, and the defect repair method is analyzed by the defect repair analyzer 120 at the end of the test.

FIG. 6 shows the internal structure of the memory under test 119. A memory composed of a semiconductor integrated circuit has a plurality of storage areas (memory cell array) 2 formed in the same semiconductor chip 1 and is configured so that each of these storage areas 2 can be selectively accessed to have a desired storage capacity. An element is configured.
Each storage area is provided with a desired number of spare lines SC and SR in the row address ROW direction and the column address COL direction as shown in an enlarged manner in FIG. Spare lines SR and SC are provided for defect relief, and replace defective cells in the storage area 2 with the spare lines to make the memory under test in which defects occur non-defective. Depending on the number of spare lines SR and SC formed in the row address direction ROW and the column address direction COL, the number of defective cells that can be relieved by a spare line orthogonal to the line is limited. For this reason, after the test is completed, the number of defective cells and the row address and column address where the defective cells exist are searched for each storage area 2 to determine whether or not the repair with the spare line orthogonal to the line is possible.

  In order to make the above determination, the defect repair analyzer 120 is provided with counter / memory TFC, RFC, and CFC as shown in FIG. TFC is a defective cell total number memory that counts and stores the total number of defective cells in each storage area 2, RFC is a row address defective cell number storage memory that stores the number of defective cells existing on the row address, and CFC is a column address. A column address defective cell number storage memory in which the number of defective cells existing above is stored is shown.

  As shown in FIG. 9, there are many defective cells on one address line RLN or CLN, that is, there are more defective cells than the number of spare lines existing in the direction orthogonal to the defective cell arrangement direction. This state is called mast repair. As a procedure for defect repair analysis, first, this mast repair is detected, then the spare line used for the repair and the repaired defective cells are removed, and whether or not the remaining defective cells can be repaired by the remaining spare lines. Determine whether.

The search for the mast repair is performed in both the row address ROW direction and the column address COL direction. That is, when the row address defective cell number storage memory RFC is read in the order of addresses, the number of defective cells existing on each row address in the storage area 2 can be read. Comparing the number of numbers X ₁ and spare line SC of the defective cells are stored in each row address Y _1, X _1> if Y ₁ determines that must-repair, the main controller that address as must-repair address 111 reads and stores.

Next, the column address defective cell number storage memory CFC is read in the column address COL direction, the number X _{2 of} defective cells stored in each column address COL is compared with the number Y ₂ of spare lines SR, and X ₂ > Y ₂ In this case, it is determined as a mast repair, and the address is taken into the main controller 111 as a mast repair address.
When the search for the mast repair address is completed, the main controller 111 sets the mast repair address in the defect repair analyzer 120, and performs an operation of updating the analysis data. In other words, if there is a mast repair on the row address line RLN, the number of the spare line SR is set to −1, and the number of defective cells on the address line is set as supposing that the mast repair is relieved by using the spare line SR. An operation of subtracting from the row address defective cell number storage memory RFC and the defective cell total number memory TFC is executed.

This is shown in FIG. In the example shown in FIG. 10, there is shown a case where there is a mast repair MS at the row address RN and the number of defective cells constituting this mast repair MS is “9” on the row address line RLN. When using the spare line SR shall rescued must-repair, the stored value of the defective cell total memory TFC is changed to "3" from the "12", on the row address fail cell total memory RFC row address R _N defective The number of cells “9” changes to “0”, the number of defective cells in the row address defective cell number storage memory CFC is subtracted by −1, and the number of defective cells on the column address of the number of defective cells “1” is “0”. In addition, the number of defective cells “3” changes to “2”, and the number of defective cells “2” changes to “1”.

  An object of the present invention is to provide a memory defect repair analysis method capable of quickly searching for the address of a defective cell remaining after executing the above-described repair process of the mass repair, and a defect repair analysis to which this analysis method is applied. A memory test apparatus is proposed.

  Conventionally, in order to search for the address of the remaining defective cell after the repair process shown in FIG. 10, under the control of the main controller 111, the row address defective cell storage memory RFC is sequentially read in the row address ROW direction. Each time the remaining number of defective cells is detected, the row address is stored in the main controller 111, and the remaining defective cells are searched until the final address of the row address.

Similarly, the column address defective cell storage memory CFC is sequentially read in the column address COL direction, and each time a defective cell remaining is detected, the column address is stored in the main controller 111, and the defective cell remains until the final address of the column address. Explore.
When the row address defective line search and the column address defective line search are completed, the row address and the column address where the stored defective cells exist are read out, and the defective cells are read in all the combined addresses of the row address and the column address as shown in FIG. Therefore, the failure analysis memory 118 is read for all the combined addresses, and the defective cells are specified and stored.

  Thus, conventionally, under the control of the main controller 111, a row address and a column address where a defective cell exists is detected and stored in advance, and the failure analysis memory 118 is stored with an address obtained by combining the stored row address and column address. When reading and this address is a defective cell, it is stored as the address of the defective cell. Therefore, it is necessary to repeatedly execute the defective line search, the address calculation, and the reading of the defect analysis memory 118. is there.

According to the first aspect of the present invention, a memory under test that includes a plurality of storage areas, selectively accesses, writes, and reads the plurality of storage areas is tested, and defective cells obtained as a result of the test are tested. In the failure relief analysis method for analyzing the failure relief solution by detecting the number and address,
Detecting whether a plurality of storage areas searched by defective cell number defective cell memory for storing the number of defective cells in each is present, the presence of the defective cell is present its defective cell each time it is detected storage area The row address defective cell number memory or the column address defective cell number memory for storing the number of defective cells existing at the row address or the column address only is searched to detect the row address or column address where the defective cell exists, and the defective Each time a row address or column address in which a cell exists is detected, the address of the defective cell on the detected address line is stored in the column address or defective cell number memory or row for storing the number of defective cells existing in the column address or row address. The present invention proposes a memory failure remedy analysis method characterized by searching and specifying and storing a memory having an address defective cell count .

According to the second aspect of the present invention, whether or not there is a defective cell by searching a memory for the number of defective cells for storing the number of defective cells for each storage area of the memory under test configured with a plurality of storage areas. Analyzed region search means for determining whether to perform defect repair analysis by
In this storage area determined as an area to be subjected to defect repair analysis by this analyzed area search means, a row address defective cell number memory or a column address defective cell number memory for storing the number of defective cells existing at a row address or a column address is searched. And defective line search means for detecting the presence of defective cells,
When this defective line search means detects a row address line or column address line in which a defective cell exists, it is activated and stores the number of defective cells existing in the column address or row address. Address scanning means for searching the memory to detect an address in a direction orthogonal to the detected address of the defective cell on the row address line or the column address line;
A defective cell address memory for storing addresses of defective cells detected by these defective line search means and address scanning means;
We propose a memory testing device that is equipped with a failure relief analyzer configured by

  According to the memory defect repair analysis method and the memory test apparatus equipped with the defect repair analyzer to which the defect repair analysis method is applied according to the present invention, the row address or column address where the defective cell exists is detected by the defective line search means. When a row address or column address in which a defective cell exists is detected, an address in the orthogonal direction is immediately scanned at the address position by the address scanning means, and at the same time, the address of the defective cell is specified by reading out the failure analysis memory. .

  When the address of the defective cell is specified with respect to the row address and the column address, the address is stored in the memory, and the defective line search means is restarted to continue the defective line search operation. When the defective line search operation reaches the final address, the defect repair analysis of the storage area is completed, and the analysis target is shifted to the defect repair analysis of the next storage area.

  As described above, when the defective line search means detects the presence of a defective cell, an address scan in the orthogonal direction is immediately performed at the address position to identify the address of the defective cell. Therefore, the address where the defective cell is detected is set. Since there is no such work, the address of the defective cell can be specified in a short time, and the time required for the defect repair analysis can be shortened.

As described above, according to the present invention, when the defective line search means SEA detects the presence of a defective cell at the row address _RN1 , for example, the operation of the defective line search means SEA is temporarily stopped at the row address _RN1. , running direction of the address scanning orthogonal thereto, because detecting a column address C _N1 of the defective cell FC1, detects the row address R _N1 and R _N2 for the defective cells in a conventional manner, the row address _RN1 and _RN2 are once read by the main controller 111, and after all the row addresses are read, the row address _RN1 is set in the failure remedy analyzer, and the read column address C _N1 is detected in the column address direction. Compared with the analysis method, the addresses of the defective cells FC1 and FC2 can be specified in a short time. As a result, there is an advantage that the overall time required for defect repair analysis can be shortened.

  1 and 2 show an embodiment of a failure relief analyzer to which a failure relief analysis method as a main part of the present invention is applied. The failure remedy analyzer, which is the main part of the present invention, comprises an analyzed region search means BLS, a defective cell search means SEA, an address scan means SCA, and a controller CON that controls them. FIG. 1 shows the configuration of the controller CON and the analyzed region search means BLS, and FIG. 2 shows the configuration of the defective cell search means SEA, the address scan means SCA, and the defective cell address memory 125.

  The analyzed area search means BLS is accessed by an area address generator TAP that generates addresses assigned to a plurality of storage areas 2 constituting the memory under test 119, and an area address output from the area address generator TAP. A defective cell total number memory TFC that stores the total number of defective cells in the storage area 2, a zero detector ZO1 that detects that the number of defective cells read from the defective cell total number storage memory TFC is “0”, and an area address generation And a carry selector CY1 that detects that the area address output from the unit TAP has reached the final address state and outputs a carry signal TAP MAX.

  The total number of defective cells in each storage area 2 in the defective cell data fetched into the defect analysis memory 118 is totalized and stored in each storage area 2 in the total number of defective cell storage memory TFC. The area address generator TAP sequentially increments the address in increments of +1 from the initial address, and reads the total number of defective cells from the address corresponding to each storage area of the total memory cell TFC for defective cells.

The number of defective cells read from the defective cell total number storage memory TFC is determined by the zero detector ZO1 to be “0” or a numerical value other than “0”. If the number of read defective cells is “0”, the zero detector ZO1 gives an enable signal to the area address generator TAP to increment the generated area address by +1. While the number of defective cells read from the defective cell total number storage memory TFC is “0”, the area address generator TAP repeats the operation of incrementing the area address by 1 and continues reading the defective cell total number storage memory TFC. When the area address reaches the final address without detecting a numerical value other than “0” and is to be incremented by 1 from the final address, the carry selector CY1 outputs the carry signal TAP MAX, and the carry signal TAP MAX is output from the controller CON. This completes the defect repair analysis of one memory.

If the number of defective cells read from the defective cell total number storage memory TFC is other than “0” before the area address reaches the final address, the controller CON stops the stepping operation of the area address generator TAP and stores it. A defect repair analysis operation is performed on region 2.
The defect relief analysis operation is started by outputting an output signal R-SEARCH or C-SEARCH from the controller CON. Which output signal is generated can be preset in the controller CON. Here, it is assumed that the output signal R-SEARCH is output.

When the output signal R-SEARCH is output from the controller CON, the defective line search means SEA is activated. In this embodiment, the defective line search means SEA reads the row address defective cell number storage memory RFC and searches for whether or not there is a defective cell on the row address.
Therefore, in the embodiment shown in FIG. 2, the defective line search means SEA combines the row address generator RAP and the row address output from the row address generator RAP and the region address output from the region address generator TAP. A formatter ANF1, a row address defective cell number storage memory RFC that is accessed by an address signal synthesized by the address formatter ANF1 and reads the number of defective cells on the row address of each storage area 2, and this row address defective cell number storage memory RFC A zero detector ZO2 that detects that the number of defective cells read out from “0” is “0”, and a gate G1 that controls whether or not to output a zero detection signal output from this zero detector ZO2 depending on the state The row address generated by G3 and the OR gate OR1 and the row address generator RAP is Constituted by the carry selector CY2 which outputs a carry signal RAP MAX detects the +1 state from a final address.

When the controller CON raises the output signal R-SEARCH to H logic, the row address generator RAP starts operation. At the same time, an output signal R-SEARCH is input to one input terminal of the gate G1, thereby controlling the gate G1 to be in an open state.
When the row address generator RAP starts operation, the row address defective cell storage memory RFC reads the row address of the storage area 2 indicated by the area address TAP. The zero detector ZO2 monitors whether the number of defective cells is “0” or a numerical value “0” or less for each row address. When a numerical value other than “0” is detected, the zero detector ZO2 outputs an H logic, and R-Fail Address indicating that a defective cell exists in the row address is input to the controller CON through the gate G1 and the OR gate OR1. .

  When this input signal R-Fail Address is input, the controller CON once lowers the output signal R-SEARCH to L logic. The operation of the row address generator RAP is stopped. At the same time, the output signal C-SCAN is raised to H logic. When this output signal C-SCAN rises to H logic, the column address generator CAP starts operating in this example constituting the address scanning means SCA.

In this embodiment, the address scanning means SCA is configured to scan column addresses. Thus the column address generator CAP address scan hand stage SCA to an address formatter ANF2 for combining the area address output by the column address signal and the area address generator TAP output from the column address generator CAP, this address formatter The column address defective cell number storage memory CFC which is accessed by the address signal synthesized by the ANF 2 and reads the number of defective cells on each column address, and the number of defective cells read from the column address defective cell number storage memory CFC is “0”. Zero detector ZO3 for monitoring whether or not, gates G2 and G4 and OR gate OR2 for controlling whether or not a detection signal output from this zero detector ZO3 is output according to the state, and column address generator CAP output Detects that the column address to be changed to the final address and carries Constituted by the carry selector CY3 for outputting No. CAP MAX.

  When the controller CON outputs the output signal C-SCAN, the column address generator CAP starts operation, and reading of the column address defective cell number storage memory CFC is started simultaneously with reading of the failure analysis memory 118. If the number of defective cells read from the column address defective cell number storage memory CFC is “0”, the column address generator CAP repeats the operation of incrementing the value of the output address signal by one.

  When the zero detector ZO3 detects a value other than “0” and the read data of the defect analysis memory 118 is “1” indicating a defective cell, the output signal C-SCAN is input to the gate G4 at this time. Therefore, an H logic signal is output through the gate G4, and this H logic signal is input to the controller CON as an input signal C-Fail Address.

When the input signal C-Fail Address is input, the controller CON outputs the write signal WT and writes the area address, the row address, and the column address indicating the position of the defective cell in the defective cell address memory 125.
When the writing is completed, the column address generator CAP repeats the operation of incrementing the address by +1. When the final address of the column address is reached, the output signal C-SCAN is lowered to the L logic, and the output signal R-SEARCH is set to H instead. The logic is restored, and the defective line search operation for searching for the presence or absence of a defective cell at the row address is resumed.

  FIG. 3 shows how the defective line search means SEA and the address scanning means SCA operate. The row address is incremented by +1 in the row address ROW direction to search for the presence of a defective cell. The number of defective cells stored in the row address defective cell number storage memory RFC, the column address defective cell number storage memory CFC, and the defective cell total number storage memory TFC shown in FIG. 3 is removed by the mast repair repair process described in FIG. It shows the state.

When the row address by the search operation of the defective line search means SEA reaches R _N1, since in this row address R _N1 the defective cell FC1, perform address scan operation to the column address COL direction at this address R _N1. When the address is advanced in the column direction by the address scan operation and reaches C _N1 , the zero detector ZO3 outputs an H logic signal indicating that the output of the memory CFC is not “0”. At this time, if the read data of the failure analysis memory is not “0”, the output of G4 becomes H, and this H logic signal is input to the controller CON as the input signal C-Fail Address. Since the write signal WT is output when the input signal C-Fail Address is input to the controller CON, if the defective cell search is performed in the storage area A, the defective address memory 125 is shown in FIG. Thus, the area address A where the defective cell exists, the row address R _N1 and the column address C _N1 are stored.

When the column address generator CAP generates up to the final address, the state is detected by the carry selector CY3, and a carry signal CAP MAX is output. When the carry signal is input, the controller CON restarts the defective line search means SEA, and the defective line search means SEA repeatedly executes a defective cell search. When defective line search reaches to the row address R _N2, the presence of one defective cell FC2 is detected. As a result, the defective line search means SEA temporarily stops the operation, activates the address scan means SCA, and detects the column address C _N2 . The detected row address R _N2 and column address C _N2 are stored in the defective address memory 125.

  When the storage operation is completed, the address scanning means SCA repeats the address scanning up to the final address of the column address, and after reading the final address, the operation right is transferred to the defective line search means SEA to execute the defective line search operation. When the defective line search operation reaches the final address of the row address, the defect repair analysis of the storage area 2 is finished, and the defect repair analysis of the next storage area 2 is executed.

  In the above description, the case where the defective line search means SEA is configured to detect a defective cell on the row address has been described. However, the defective line search means SEA may be set to detect a defective cell on the column address and execute a defective line search. it can. The setting may be made by setting means provided in the controller CON. When the defective line search means SEA is configured by detecting defective cells on the column address, the configuration on the side for detecting the presence of the defective cell on the row address constitutes the address scanning means SCA.

FIG. 3 is a block diagram for explaining a memory defect repair analysis method according to the present invention and a configuration of a controller of a defect repair analyzer to which the defect repair analysis method is applied and portions to be inspected area searching means; The block diagram for demonstrating the structure of the part of the defective line search means of the defect repair analyzer similar to FIG. 1, an address scanning means, and a defective cell address memory | storage device. The figure for demonstrating the defect relief analysis method of this invention. The figure for demonstrating the operation | movement of the Example shown in FIG.1 and FIG.2. The block diagram for demonstrating the outline | summary of a memory test apparatus. FIG. 3 is a plan view for explaining the internal structure of the memory under test. The enlarged plan view which expanded and showed a part of structure shown in FIG. The figure for demonstrating the defective cell data required for the defect repair analysis of a memory. The top view for demonstrating the mast repair which is one of the forms of the defect of a memory. The figure for demonstrating the mode of the defect cell data after carrying out relief processing of the mass repair shown in FIG. The figure for demonstrating the conventional fault.

Explanation of symbols

1 Semiconductor chip
2 storage area
BLS analysis area search means
TAP area address generator ZO1, ZO2, ZO3 Zero detector CY1, CY2, CY3 Carry selector
SEA Defective line search means
RAP row address generator
RFC row address defective cell number storage memory
SCA address scanning means
CAP column address generator
CFC column address defective cell number storage memory
CON controller
119 Memory under test
125 Bad cell address memory

Claims (2)

A plurality of storage areas are provided, a memory under test that selectively accesses, writes, and reads the plurality of storage areas is tested, and the number and address of defective cells obtained as a result of the test are detected. In the defect relief analysis method for analyzing the defect relief solution,
A search is made for a defective cell number memory for storing the number of defective cells for each of the plurality of storage areas to detect whether or not a defective cell exists, and each time a defective cell is detected, the memory in which the defective cell exists is detected. Search the row address defective cell number memory or the column address defective cell number memory for storing the number of defective cells existing in the row address or the column address only in the region, and detect the row address or column address where the defective cell exists, Each time a row address or column address in which a defective cell exists is detected, the address of the defective cell on the detected address line is stored in the column address defective cell number memory for storing the number of defective cells existing in the column address or row address, or A memory defect remedy analysis method characterized by searching and specifying and storing a row address defective cell count memory . A. Search for a defective cell number memory that stores the number of defective cells for each storage area of a memory under test configured with a plurality of storage areas, and perform defect repair analysis based on whether or not there are defective cells. An analysis area search means for determining whether or not,
B, a row address defective cell number memory or a column address defective cell number memory for storing the number of defective cells existing at a row address or a column address in a storage area determined as an area to be subjected to defect repair analysis by the analyzed area search means A defective line search means for detecting the presence of a defective cell by searching for
C, column address defective cell number memory or row address defect which is activated when this defective line search means detects a row address line or column address line in which a defective cell exists and stores the number of defective cells present in the column address or row address Address scanning means for searching the cell number memory and detecting an address in a direction orthogonal to the detected address of the defective cell on the row address line or the column address line;
D, a defective cell address storage device for storing addresses of defective cells detected by these defective line search means and address scanning means;
A memory test apparatus equipped with a failure relief analyzer constituted by

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