JPH01145869A - Manufacture of uveprom with redundant circuit - Google Patents

Abstract

PURPOSE:To reduce the area of a redundant circuit and to make it possible to perform the operation tests of a UVEPROM cell, by performing a step for covering the UVEPROM cell for programs in the redundant circuit with an ultroviolet ray shielding film, other than a circuit wiring pattern. CONSTITUTION:Operation tests are conducted by using a wafer prover. Thereafter, a polyimide film having a thickness of about 1mum is selectively formed. Heat treatment is performed at 400 deg.C. A UVEPROM element and its peripheral part are covered with an ultraviolet ray shielding film 4. Then the device is sealed into a package in an assembling step. Operation tests after assembling is performed in conformity with an ordinary method. The ultraviolet ray shielding film 4 comprising polyimide is provided at a layer other than that of an aluminum electrode 6. Therefore, the area of the UVEPROM can be made small and can be provided over a wide area other than a memory cell 1 and a spare memory cell 2. The sufficient shielding effect can be provided. The operation test of the UVEPROM cell 3 can be performed under the wafer state, and the steps can be rationalized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a UVEPROM with a redundant circuit.

[Conventional technology]

UVEPROM irradiates memory cells with ultraviolet light to erase data. Therefore, the UVEPRO for the program
UVEPR with built-in redundant circuit switched by M cell
In OM, UVEPRO for programming during erasing
If the M cell is also exposed to ultraviolet light and this data is erased, a defective memory cell will be selected and the redundancy function will be lost. Therefore, the conventional manufacturing method of UVEPROM with redundant circuit includes a step of coating the programming UVEPROM cell with an aluminum film to prevent it from being exposed to ultraviolet rays, but this step was performed at the same time as electrode wiring formation.

FIG. 4 is a pattern diagram of a UVEPROM cell for explaining a conventional example, and FIG. 5 is a cross-sectional view of the semiconductor chip taken along the line χ-X' in FIG.

Floating gate 10. Control gate 11. N+ diffusion layer 8-7.
UVEPROM with 8-8 as the large source/drain region
The cell is covered with an aluminum electrode 6-1 to block ultraviolet rays. Since the ultraviolet shielding film also serves as electrode wiring, no other elements can be placed in this portion. Further, in order to improve the shielding effect, the aluminum film covers a wide area.

[Problem that the invention seeks to solve]

In the conventional manufacturing method of UVEPROM with a redundant circuit described above, a UVEPROM cell for programming is covered with an aluminum film that also serves as electrode wiring to form an ultraviolet shielding film, so other elements are placed under the ultraviolet shielding film. This has the disadvantage that the area occupied by the redundant circuit increases.

Also, when performing an operation test, the UVEP for programming is already covered with an aluminum film and cannot be erased.
Another drawback is that ROM cells cannot be tested.

[Means for solving problems]

The method of manufacturing a UVEPROM with a redundant circuit according to the present invention includes a memory cell for storing data, a spare memory cell for replacing the defective memory cell when a defect occurs in a part of the memory cell, and a UVEPROM cell for programming. UVEP with a redundant circuit, which has a redundant circuit that switches between defective memory cells and spare memory cells.
When manufacturing a ROM, the UVEPROM is
The method involves a step of coating the cell with an ultraviolet shielding film.

Since the ultraviolet shielding film is separate from the aluminum film for wiring, it can be made large independently of surrounding elements as long as it does not cover memory cells or spare memory cells, and the area of redundant circuits can be reduced. can. Also, during the operation test, there was no ultraviolet shielding film, and the UVEP for programming
This test can be performed because the ROM cells can be erased.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram for explaining an embodiment of the present invention, FIG. 2 is a cross-sectional view of a semiconductor chip showing a UVEPROM cell and its surrounding area, and FIG. 3 is a flowchart of an embodiment of the present invention. .

Floating gate 10. Control gate 11. N+ diffusion layer 8-3.
UVEPROM element whose source/drain region is 8-4, its peripheral circuit (M including N+ diffusion layer 8-1, 8-2)
OS transistor, M including N+ diffusion layer 8-5, 8-6
(having a configuration including an oS transistor and an aluminum electrode 6) is covered with a cover insulating film 5. So far,
It can be manufactured using the same process as the conventional method except that the upper part of the floating gate 10 is not widely covered with the aluminum film. After such a wafer manufacturing process 21, an operation test 22 was performed using a wafer prober, and the wafer was found to have a thickness of about 1 μm.
A polyimide film is selectively formed and heat-treated at 400° C. to cover the UVEPROM element and its surrounding area with the ultraviolet shielding film 4 (23). Next, in an assembly step 24, the product is sealed in a package, and a post-assembly operation test 25 is conducted according to a conventional method.

Since the ultraviolet shielding film 4 made of polyimide is provided on a layer different from the aluminum electrode 6, the area of the UVEPROM can be reduced, and it can be applied over a wide area without covering the memory cell 1 or the spare memory cell 2. It is possible to provide a sufficient shielding effect. Furthermore, it is possible to test the operation of UVEPROM cells in the wafer state, thereby streamlining the process.

〔Effect of the invention〕

As explained above, the present invention reduces the area of the redundant circuit by performing a step of covering the programming UVEPROM cell in the redundant circuit with an ultraviolet shielding film separate from the circuit wiring pattern after the operation test. is possible,
It is also possible to test the operation of UVEPROM cells, which has the effect of streamlining the manufacturing process of UVEPROMs with redundant circuits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining an embodiment of the present invention, FIG. 2 is a cross-sectional view of a semiconductor chip showing a UVEPROM cell and its surrounding area, and FIG. 3 is a flowchart of an embodiment of the invention. FIG. 4 is a pattern diagram for explaining a conventional example, and FIG. 5 is a cross-sectional view of the semiconductor chip taken along the line xx' in FIG. 4. 1...Memory cell, 2...Spare memory cell, 3.
・・UVEPROM cell, 4・・UV shielding film, 5・
...Cover insulating film, 6.6-1.6-1...Aluminum electrode, 7...Gate, 8-1 to 8-8...N+
Diffusion layer, 9... Well, 10... Floating gate, 11
...Control gate, 12...P-silicon substrate, 13
...Field oxide film, 14...Interlayer insulating film, 21
...Wafer manufacturing process, 22...Operation test process, 2
3... UVE PROM cell coating process, 24... Assembly process, 25... Operation test process.

Claims (1)

[Claims] It has a memory cell for storing data, a spare memory cell to replace the defective memory cell when a part of the memory cell becomes defective, and a UVEPROM cell for programming. UVE with redundant circuit equipped with redundant circuit that can be used by switching cells
When manufacturing PROM, after operation test, the UVEPRO
A method for manufacturing a UVEPROM with a redundant circuit, comprising the step of coating an M cell with an ultraviolet shielding film.