JPS6321345B2 - - Google Patents

Description

Detailed Description of the Invention A. Field of Industrial Application This invention relates to a test method for examining the quality of the characteristics of a large number of semiconductor elements formed in a vertical and horizontal arrangement on a semiconductor wafer. and a method for detecting defective product distribution areas.

B. Prior Art The distribution of good/bad characteristics of semiconductor elements formed in large numbers on a semiconductor wafer generally exhibits a distribution in which the number of good is higher in the center of the semiconductor wafer and the number of defects is higher in the periphery. This distribution of good and bad results may be due to the fact that the crystal structure of the semiconductor wafer is superior in the center and inferior in the periphery, or the temperature differs between the center and the periphery during heat treatment such as diffusion, or the transfer of the semiconductor wafer into and out of the diffusion furnace is different. This can occur due to various reasons such as the peripheral area being susceptible to rapid heating and cooling, and the boundary between the good product distribution area and the defective product distribution area may be
Each piece is slightly different. For this reason, conventionally, the characteristics of semiconductor elements are measured one by one for all the semiconductor elements on one semiconductor wafer.

For example, as shown in FIG. 1, a large number of semiconductor elements (hereinafter referred to as elements) 2, 2, . First, the characteristics of all the elements 2, 2, etc. in one row at the right end of the drawing of the wafer 1 are sequentially measured, and when the measurement of this one row is completed, all the elements 2, 2,... in the adjacent row are sequentially measured.
This was repeated to measure the characteristics of all the elements 2, 2, . . . on the wafer 1 in a zigzag pattern, and defective products were marked with defective marks on their surfaces.

C. Problems to be Solved by the Invention As a method for efficiently measuring the characteristics of the above elements, one tester and two probers (not shown) are used to measure the characteristics of one element on each of two wafers. The multiple-choice measurement method involves alternating and consecutive
Parallel measurement methods have been implemented in which characteristics of elements are simultaneously measured one by one on each wafer. However, since the characteristics of all the elements on one wafer are individually measured, the measurement time per wafer tends to become long. Especially for devices such as diodes, which have small device dimensions and the number of devices per wafer is tens of thousands, even if the above alternative measurement method or parallel measurement method is efficient, it will take at least an hour to measure all the devices. There was more than one time.

D. Means for Solving the Problems The present invention was made in view of the current situation in which a normal wafer has a large number of non-defective devices continuously distributed in the center and a large number of defective devices continuously distributed in the periphery. As a means for solving the above-mentioned problems, we provide the following means for detecting the boundary line between the distribution area of good and defective devices on a wafer. In other words, the quality of devices in the same row is sequentially searched from one end of an arbitrary row of devices formed in a grid pattern in the vertical and horizontal directions on the wafer, and when a certain number of non-defective devices are detected in succession, the searched row is moved to the adjacent row. Next, perform a pass/fail search for the elements in this changed column in the opposite direction to the search column, and then change the search column to the adjacent column when a certain number of defective products are detected consecutively. By repeating these operations, the boundaries between the good and bad distribution areas are sequentially searched. By detecting the boundary line between good and defective distribution areas in this way, all elements within the boundary line can be treated as good, and it is no longer necessary to measure the characteristics of all elements on the wafer, which significantly reduces wafer processing time. The time can be shortened.

E Example As shown in FIG. 2, the characteristics of each element 2, 2... of one wafer 1 are marked with a mark "a" if the characteristics are good.
Assuming that defective products are unmarked, the good product distribution area M on the wafer 1 is at the center of the wafer, the defective product distribution area N is at the periphery of the wafer, and the boundary line L between the two areas is an irregular ring shape. Appears with age. Therefore, in order to obtain the boundary line L, the characteristics of the elements 2, 2, . . . are sequentially measured as indicated by the zigzag arrows shown in FIG.

Y on or near the center P0 of wafer 1
One end of a group of elements in a row X1 along the axial direction is set as a starting point P1, and the X coordinate of this point P1 is stored in memory. Then, when the characteristics of elements 2, 2, etc. in the X1 row are sequentially measured from point P1 in the -Y axis direction, since the beginning is in the defective product distribution area, defective products continue, and from the point beyond the boundary line L Good products continue, and each pass/fail result is stored in memory.

Change the column to search for pass/fail at point P2 where a predetermined number of non-defective products follow from X1 to the adjacent column X2, and
A pass/fail search is performed sequentially in the +Y-axis direction starting from element 2 at point P2' adjacent to P2 of X2. At this time, good products continue at first, and after crossing the boundary line L, defective products continue, so the search for X2 is stopped at point P3, where a predetermined number β of defective products continue, and the process moves to the adjacent column X3. In column
At consecutive points P4, change the column to X4, and in column X4 +Y
Point P5 where there are β defective products after searching for pass/fail in the axial direction
Change the column to X5. Such a search is sequentially repeated for each column, the boundary line L is gradually detected, and the results are stored in memory.

Then, in the column Xi along the tangential direction of the boundary line L, -
If the search is performed in the Y-axis direction and α pieces of non-defective products cannot be detected consecutively, the search proceeds to the end Pi of the column Xi, where the edge of wafer 1 is detected by another means, and the next step is
Return to the Xi-1 column and start searching in the +Y axis direction,
The boundary line L is determined in the same manner as described above. Boundary line L
For rows Xi along other tangential directions, the same procedure as for Xi is performed. And the point where most of the boundary line L is detected
When the X coordinate of this point Pk at Pk matches the memory of the X coordinate of the starting point P1, the search is terminated at that point.

The numbers α and β that serve as a guideline for determining the boundary line L are changed depending on the type of wafer. Also the starting point
P1 does not necessarily have to be determined at the edge of the wafer;
Since the position of the boundary line L can be roughly predicted, the starting point P1 may be set at a part of the periphery of the wafer. Further, in parallel with the operation of determining the boundary line L, it is desirable to attach a mark for indicating a defective element (or indicating a non-defective element) on a defective element (or a non-defective element) along the boundary line L.

F. Effects of the Invention As described above, according to the present invention, wafer processing can be performed to inspect whether the elements are good or bad simply by selectively measuring the characteristics of the elements near the boundary between the good and bad distribution areas of the elements on the wafer. Wafer processing time can be significantly shortened. Furthermore, mechanical components such as the blower of the conventional device characteristic measuring device can be used as is by simply changing the software and adding some memory, which is advantageous in terms of equipment.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a semiconductor wafer for explaining the conventional method of measuring semiconductor device characteristics, Fig. 2 is a diagram of the quality distribution of semiconductor elements on the semiconductor wafer, and Fig. 3 is an operation example diagram for explaining the method of the present invention. It is. 1... Semiconductor wafer, 2... Semiconductor element, M... Good product distribution area, N... Defective product distribution area, L... Boundary line.

Claims (1)

[Claims] 1. When measuring the characteristics of semiconductor elements on a semiconductor wafer in which a plurality of semiconductor elements are formed in a vertical and horizontal arrangement, the quality of the characteristics of the semiconductor elements in the same row is sequentially searched from one end of a predetermined row of semiconductor elements to find a non-defective product. When a predetermined number of consecutive defective products are detected, the search column is changed to the adjacent column, and then a quality search for the semiconductor elements in this changed column is performed in the opposite direction to the previous search column to find a predetermined number of consecutive defective products. It is characterized by including the step of repeatedly changing the column to be searched to an adjacent column at the time of detection to search for and detect the boundary line between the non-defective distribution area and the defective distribution area of semiconductor elements on the semiconductor wafer. Semiconductor wafer testing method.