JPH0222842A - Trimming by laser - Google Patents

Abstract

PURPOSE:To execute a trimming treatment without being restricted by a design of an IC by a method wherein a memory IC chip provided with a redundant circuit is divided into small divided regions, alignment marks are arranged, an alignment operation is executed and a fuse is blown in each divided region. CONSTITUTION:When a trimming treatment of a memory IC 1 provided with a redundant circuit is executed, a chuck is shifted in such a way that the center of a divided region 4 is always situated, in the center of a laser beam by using the region 4 as a reference. In the case of a good chip and a chip which cannot be relieved, the chuck is shifted by an amount of a size of a chip which is not divided. In the case of a chip which can be relieved, an alignment operation is executed and a fuse is blown in the divided region 4; after that, the chuck is shifted in such a way that the center of a divided region 5 is situated in the center of the laser beam. An alignment operation is executed and a fuse is blown in the divided region 5; after that, the chuck is shifted in such a way that the center of the divided region 4 for a next chip is situated in the center of the laser beam. Thereby, it is possible to execute the trimming treatment of the memory IC provided with the redundant circuit which is larger than a movable range of the laser beam.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser trimming method, and more particularly to a laser trimming method using a beam movable laser trimming device that performs positioning by moving a laser beam. It is.

[Conventional technology]

FIG. 2 is a diagram for explaining the conventional laser trimming method. In the figure, 1 is a memory IC (IC chip) with a redundant circuit to which the laser trimming process is applied, and 2 is a memory IC (IC chip) formed on the surface area of the memory IC. An alignment mark 3 is used to align the chip coordinate system and the laser beam coordinate system, and 3 is a movable range of the trimming laser beam.

Next, the operation will be explained.

The laser trimming equipment holds memory ICs (IC chips) with redundant circuits in a wafer state using a chuck, and by moving the chuck, the chips are indexed and processed one by one.Functions were also tested using a testing device. As a result, in the case of a defect that becomes a non-defective product by using a spare cell, the fuse placed in the chip of the memory IC with redundant circuit is blown out with a laser beam depending on the defect content, and the defect is replaced with a spare cell, thereby resolving the defect. do.

Here, if the laser trimming device is of a type that moves the laser beam to hit the fuse inside the chip, the position of the laser beam is determined by scanning the alignment mark placed inside the chip and using the chip coordinate system. Accurate setting can be achieved by correcting the position of the laser beam coordinate system based on .

[Problems to be Solved by the Invention] [However, in a laser beam movable type laser trimming device that performs positioning by moving the laser beam in this way, for memory ICs whose chip size exceeds the movable range of the laser beam, If the fuses and alignment marks are not within the movable range of the laser beam, trimming becomes impossible, and arranging the fuses and alignment marks within the movable range of the laser beam is a major constraint in IC design.

In other words, in normal trimming processing, the center of the movable range of the laser beam is set at the center of the chip, so placing an alignment mark, etc. within the movable range means that it is part of the memory cell area at the center of the chip. This means that the company will occupy the entire This poses a problem in that it becomes a constraint on the design of the memory cell section and is difficult to realize.

This invention was made to solve the above-mentioned problems, and it provides a memory IC with a redundant circuit whose chip size exceeds the movable range of the laser beam of the laser trimming device.
An object of the present invention is to obtain a laser trimming method that enables trimming processing without imposing restrictions on IC design.

[Means to solve the problem]

The laser trimming method according to the present invention divides the surface area of a memory IC chip with a redundant circuit whose chip size exceeds the movable range of the laser beam into divided regions smaller than the movable range of the laser beam, and divides each of the divided regions into Alignment marks are provided, and the laser trimming process is performed by performing positioning using the alignment marks and laser trimming for each divided area.

[Effect]

In this invention, a memory IC chip with a redundant circuit is
The surface area is divided into divided areas smaller than the laser beam movable range, alignment marks are placed in each divided area, and alignment and fuse blowing are performed for each divided area. Trimming processing of a memory IC with a redundant circuit that is larger than the movable range of the memory IC can be performed without imposing restrictions on IC design.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a laser trimming method according to an embodiment of the present invention, in which 1 is a memory IC (IC chip) with a redundant circuit to be trimmed whose chip size is larger than the laser beam movable range 3; .5 is a divided area created by dividing the surface area of the IC chip into two in the short side direction, and each divided area 4.5 is smaller than the above laser beam movable range, and alignment marks 2 are provided at the periphery thereof. is installed.

Next, the effects will be explained.

Memo +71 with redundant circuit divided as shown in Figure 1
In the CI trimming process, the chuck is always moved using the divided area 4 as a reference so that the center of the area 4 is the center of the laser beam. The chuck movement method differs depending on whether the chip is a defective chip that cannot be repaired or if it is a salvageable defective chip that requires blowing the fuse.

For non-defective chips and chips that cannot be salvaged, move the chuck by the size of the chip that will not be divided. For a salvageable chip, after alignment and blowing of the fuse are performed in the divided region 4, the chuck is moved so that the center of the divided region 5 becomes the center of the laser beam.

After alignment of the divided region 5 and blowing of the fuse, the chuck is moved so that the center of the divided region 4 of the next chip becomes the center of the laser beam. Note that due to the configuration of the redundant circuit, it is not necessarily necessary to blow the fuses in each area depending on the nature of the defect, and if it is sufficient to blow the fuses in only one area, the process of selecting the area in which to blow the fuses based on the nature of the failure may be performed. Attachment is added. Furthermore, here, the positions of the alignment marks and fuses in each region on the chip are assumed to be the coordinates when the center of each region is (0,0).

In this example, the surface area of the memory IC with redundant circuit is divided into divided areas smaller than the laser beam movable range, and an alignment mark is placed in each divided area, and the laser trimming process is performed in each of the above divided areas. Since alignment and fuse blowing are performed for each region, it is possible to trim a memory IC with a redundant circuit that is larger than the movable range of the laser beam. Further, since the alignment mark is arranged in the space around the divided area, the arrangement of the alignment mark does not impose any restrictions on IC design.

Although the above embodiment shows the case where the surface area of the IC chip is divided into two, it may be divided into even more divided areas.

〔Effect of the invention〕

As described above, according to the laser trimming method of the present invention, the surface area of a memory IC chip with a redundant circuit is divided into divided regions smaller than the laser beam movable range, and an alignment mark is placed in each divided region. Since the trimming process is performed by performing alignment and fuse blowing for each divided area, the trimming process of a memory IC with a redundant circuit whose chip size exceeds the movable range of the laser beam can be performed in accordance with the tC design. This has the effect of making it possible without incurring any restrictions.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a laser trimming method according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a conventional laser trimming method. 1... Memory IC with redundant circuit 12... Alignment mark, 3... Laser beam movable range, 4.5...
・Divided area. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1

Claims (1)

[Claims] (1) A method of performing laser trimming processing on a memory IC with a redundant circuit having a chip size larger than the movable range of the laser beam using a trimming device of a laser beam movable type, the memory IC with a redundant circuit comprising: The surface area is divided into divided areas smaller than the movable range of the laser beam, and each divided area is provided with an alignment mark, and the laser trimming process is performed using the alignment mark for each divided area. A laser trimming method characterized by aligning a coordinate system of a divided area and a laser beam coordinate system and blowing a fuse.