JPH11238664A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize the same alignment marks, when a non-transparent 2-layer metal film such as 2-layered wiring is formed on a semiconductor substrate. SOLUTION: After a flat work film 3 which insulates a semiconductor substrate 1 from a metal film 5 has been formed, the proximate flat work film 3 comprising the upper part of an alignment mark 2 is removed to form the metal film 5 of a first layer. A protruding part 6 of the metal film 5 on the alignment mark 2 is substituted for an alignment mark, when the metal film of second layer is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming two or more non-transparent films such as wirings on a semiconductor substrate.

[0002]

2. Description of the Related Art Forming a non-transparent film such as wiring on a semiconductor substrate involves a plurality of steps of transferring a pattern from a mask to a photosensitive organic film on the semiconductor substrate. At this time, by aligning the alignment marks formed on the mask with the semiconductor substrate in the wafer state, accurate alignment of the exposure region is performed. FIG. 3 is a cross-sectional view of the vicinity of an alignment mark when a wiring is formed on a semiconductor substrate by a conventional manufacturing method.
(D) shows the state of the change during manufacturing. In FIG. 3A, various regions (not shown) have already been formed in the semiconductor substrate 1. However, since the wiring between the regions and the connection of the regions to the terminals have not been made yet, the alignment is not performed. The mark 2 is exposed on the semiconductor substrate 1. In FIG. 3B, a planarization film 3 for insulating the semiconductor substrate 1 from the wiring is formed on the semiconductor substrate 1 including the alignment mark 2.

In FIG. 3C, the flattening film 3 is flattened to prevent disconnection of the wiring. In FIG. 3D, a metal film 5 serving as a first-layer wiring is formed on the planarized processing film 3 including the planarization processing film 3 on the alignment mark 2. The mask pattern for forming the metal film 5 is flat because the alignment mark 2 can be transmitted through the planarization film 3 and confirmed because the planarization film 3 is usually a transparent film such as SiO _2. The alignment mark 2 can be used for alignment as in the case of forming the roughened film 3. However, it is not possible to form another metal film on the metal film 5 as the second-layer wiring by using the alignment mark 2. this is,
This is because the metal film 5 is non-transparent and the alignment mark 2 below the metal film 5 cannot be recognized. Therefore, when performing multi-layer wiring of two or more layers, the alignment mark 2
There is a need for another process to prevent the formation of a metal film on the top and a process to form an alignment mark for the next layer of the metal film on the metal film, which has the disadvantage of increasing the number of processes. Was.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a semiconductor device in which the same alignment mark can be used when two non-transparent films are formed on a semiconductor substrate such as a two-layer wiring. It is in.

[0005]

According to the present invention, there is provided a method of manufacturing a semiconductor device having two or more layers of non-transparent films on a semiconductor substrate, wherein a flattening film is formed on the semiconductor substrate including alignment marks, After removing the planarization film near and including the alignment mark, a first layer of non-transparent film is formed.
It is characterized by being used as an alignment mark when forming a non-transparent film of the layer.

[0006]

In the present invention, after a planarization film is formed, the planarization film near and including the alignment mark is removed to form a first non-transparent film. Then, the projection of the non-transparent film on the alignment mark formed by the first non-transparent film is used as an alignment mark when the second non-transparent film is formed.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of a method for manufacturing a semiconductor device according to the present invention. FIGS. 1A to 1F show changes in the vicinity of an alignment mark in the course of manufacture until the first-layer wiring is completed on a semiconductor substrate. The same parts as those in FIG. 3 are denoted by the same reference numerals. In FIG. 1A, an alignment mark 2 is formed on a semiconductor substrate 1 made of silicon, for example, from polycrystalline silicon. Already semiconductor substrate 1
Although various regions (not shown) are formed inside the semiconductor substrate 1, the alignment marks 2 are exposed on the semiconductor substrate 1 because the wiring between the regions or the connection between the regions is not yet performed. ing. In FIG. 1B, a planarization film 3 made of silicon dioxide (SiO ₂ ) for insulating the semiconductor substrate 1 from the wiring is formed on the semiconductor substrate 1 including the alignment marks 2. In FIG. 1C, the flattening film 3 is flattened to prevent disconnection of the wiring.

In FIG. 1D, a pattern of the photosensitive organic film 4 is formed on the planarized film 3. In FIG. 1E, the planarizing film 3 near and including the alignment mark 2 is removed using the pattern of the photosensitive organic film 4 as a mask. In FIG. 1F, a metal film 5 as a first-layer wiring is formed on the alignment mark 2 and in the vicinity of the alignment mark 2 where the planarization film 3 has been removed. The metal film 5 on the alignment mark 2 protrudes for the lower alignment mark 2. The alignment between the mask and the semiconductor substrate 1 until the metal film 5 is formed is performed using the alignment mark 2 which can be always optically confirmed from above the semiconductor substrate 1.

When a metal film serving as a second layer wiring is formed on the metal film 5, the alignment mark 2 can no longer be confirmed. It can be used as a substitute for the mark 2. By using the protruding portion 6 as a substitute for the alignment mark 2, the metal film serving as the second-layer wiring is formed as shown in FIG.
(B), it is clear that it is formed on another planarized film on the metal film 5 through a state similar to that of FIG. 1 (c).
FIG. 2 is a cross-sectional view showing another embodiment of the method of manufacturing a semiconductor device according to the present invention. FIGS. 2A to 2E show a manufacturing process until a single-layer wiring is completed on a semiconductor substrate. In the vicinity of the alignment mark. 2 (a) to 2 (b) are the same as the changes from FIG. 1 (a) to FIG. 1 (b). In FIG. 2C, the pattern of the photosensitive organic film 4 is formed on the planarized film 3 without planarizing the planarized film 3.

In FIG. 2D, the planarizing film 3 near and including the alignment mark 2 is removed using the pattern of the photosensitive organic film 4 as a mask. In this state,
The remaining flattening film 3 other than the vicinity of the alignment mark 2 (not shown) is subjected to a flattening process. Then, as shown in FIG. 2E, a metal film 5, which is a first-layer wiring, is formed on the alignment mark 2 and in the vicinity of the alignment mark 2 where the planarization film 3 has been removed. The metal film 5 on the alignment mark 2 protrudes for the alignment mark 2 on the lower side, and a protruding portion 6 is formed. When a metal film to be a second-layer wiring is formed on the metal film 5, the alignment mark 2 cannot be confirmed. Therefore, the protrusion 6 of the metal film 5 on the alignment mark 2 is Use as a substitute for 2
Is the same as FIG. 2 is different from the case of FIG. 1 in that the planarization processing film 3 is planarized after the planarization processing film 3 on and near the alignment mark 2 is removed.
In the embodiment, the case where a two-layer metal film is formed has been described. However, it is apparent that the present invention can be widely applied to a case where a non-transparent film is formed over two layers on a semiconductor substrate. An example of forming such a non-transparent film corresponds to a case where a polycrystalline silicon film is formed in two or more layers in an integrated circuit in which a circuit is formed using MOS transistors.

[0011]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the first non-transparent film on the alignment mark is used as the alignment mark when the second non-transparent film is formed on the semiconductor substrate. The projection of the transparent film is used as a substitute. Using the same alignment mark again, 2
This is efficient because the non-transparent film of the layer can be formed, and the manufacturing process can be simplified since no extra step for preventing the formation of the non-transparent film of the first layer on the alignment mark is required. This has the advantage that its reliability is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a sectional view showing another embodiment of the method for manufacturing a semiconductor device of the present invention.

FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Alignment mark 5 Metal film 6 Projection part

Claims (1)

[Claims] In a method of manufacturing a semiconductor device having two or more layers of non-transparent films on a semiconductor substrate, a flattening film is formed on a semiconductor substrate including an alignment mark, and a planarizing film is formed on the semiconductor substrate including the alignment mark. Forming a first layer of non-transparent film after removing the flattening film, and using a protruding portion of the non-transparent film on the mark as an alignment mark when forming a second layer of non-transparent film. A method for manufacturing a semiconductor device.