JPH0475316A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To execute an alignment operation highly accurately by a method wherein a semiconductor substrate around an alignment mark which is formed in an alignment mark part and which is composed of an insulating film is etched and an aluminum film is formed in a hollow formed by this etching operation and on the surface of the alignment mark. CONSTITUTION:An insulating film 5 is formed on the whole surface of a semiconductor substrate 1 including an alignment mark part. After the film has been formed, it is heat-treated in a nitrogen atmosphere and is flattened. Then, by using a photolithographic technique using a resist film, the insulating film 5 is patterned; an alignment mark 5a is formed. Then, a resist film 7 is formed on the whole surface; a patterning operation is executed so as to remove only the resist film 7 in the alignment mark part. A dry etching operation is executed by making use of the alignment mark 5a as a mask; the semiconductor substrate 1 is etched; a hollow 1a is formed. Lastly, the resist film 7 is removed; an aluminum film 8 is formed on the whole surface by a bias sputtering method. Then, the hollow 1a formed in the semiconductor substrate 1 around the alignment mark 5a is filled with the aluminum film 8; it becomes nearly equal to the surface of the semiconductor substrate 1, and the aluminum film 8 is formed also on the surface of the alignment mark 5a.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the method for forming alignment marks used in the wafer process of the semiconductor device manufacturing process, the present invention has been made to enable highly accurate alignment work in the wafer process of the semiconductor device manufacturing process. A step of forming an insulating film on the entire surface of a semiconductor substrate in which an element forming part and an alignment mark part are defined by a field insulating film, and contacting the insulating film in the element forming part. At the same time as forming the hole, patterning the insulating film in the alignment mark portion to form an alignment mark; forming a resist film on the entire surface, patterning to remove the resist film on the surface of the alignment mark portion; The method is configured to include a step of etching the semiconductor substrate around the alignment mark, and a step of removing the resist film and forming a conductive film on the entire surface.

[Industrial application field]

The present invention relates to an improvement in a method for forming alignment marks used in a wafer process for manufacturing semiconductor devices.

In recent years, as semiconductor devices have become more highly integrated and faster, flattening and
There is a demand for thinner films and finer patterns.

In the photo step of the wafer process, the pitch of the alignment marks is determined and the wavelength λ of the laser beam is adjusted.

With respect to the refractive index n of the alignment mark, the amount of interference light scattered by the alignment mark 2 decreases, and the detection rate of the alignment mark by the detector decreases.In order to improve the detection rate, the sensitivity of the detector is increased. If it is increased, noise will also be detected, reducing alignment accuracy.

Under the above circumstances, there is a need for a semiconductor device manufacturing method that can perform alignment work in the photo step of the wafer process with high precision.

When the incident angle θ holds true, the interference of the laser light becomes the strongest, and the detection rate of the interference light increases.

Alignment work is performed by scanning the alignment mark with a laser beam at such an incident angle θ and using a detector to detect the laser light scattered at the edges of the alignment mark. [Background Art] A conventional method for manufacturing a semiconductor device will be explained in detail step by step with reference to FIG. 2.

First, as shown in FIG. 2(a), the field oxide film 12
An element forming portion is defined by forming the gate oxide film 13 and the gate electrode 14, and an insulating film 15 is formed on the entire surface including the alignment mark portion.

Next, using a photolithography technique using a resist film, as shown in FIG. 2(b), a contact hole 16 is formed in the insulating film 15 on the surface of the gate electrode 14, and at the same time, the insulating film 15 at the alignment mark portion is patterned. Then, an alignment mark 15a is formed.

Then, as shown in FIG. 2(C), an aluminum film 18 is formed on the entire surface.

Finally, as shown in FIG. 2 (6), the aluminum film 18 to be left in the element forming area is patterned, and at the same time all the aluminum films 18 in the alignment mark area are patterned.
remove.

In this way, at the same time as patterning the wiring film made of the aluminum film 18 in the element forming part, the aluminum film 18 in the alignment mark part is removed to form the alignment mark 15a made of the insulating film 15.

[Problem to be solved by the invention]

In the conventional semiconductor device manufacturing method described above,
The alignment mark formed in the alignment mark part is formed at the beginning of the process by patterning the insulating film that is formed at the same time as the insulating film formed in the element forming part, so its height is determined by the thickness of the insulating film in the element forming part. If the film thickness of this insulating film is thin, it becomes difficult to recognize it as an alignment mark, resulting in a problem that the accuracy of alignment work decreases.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention aims to provide a method for manufacturing a semiconductor device that allows alignment work in a wafer process of a semiconductor device manufacturing process to be performed with high precision.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes the steps of forming an insulating film over the entire surface of a semiconductor substrate in which an element forming area and an alignment mark area are defined by a field insulating film, and forming a contact hole in this insulating film in the element forming area. At the same time as forming the alignment mark, there is a process of patterning the insulating film on the alignment mark part to form an alignment mark, and forming a resist film on the entire surface and patterning to remove the cyst film on the surface of the alignment mark part. The structure includes a step of etching the semiconductor substrate around the semiconductor substrate, and a step of removing the resist film and forming a conductive film on the entire surface.

[Effect]

That is, in the present invention, the semiconductor substrate around the alignment mark made of an insulating film formed in the alignment mark portion is etched, and an aluminum film is formed on the recess formed by this etching and on the upper surface of the alignment mark. It becomes possible to make the step of the film significantly larger than the step between the surface of the semiconductor substrate and the upper surface of the alignment mark made of the insulating film, and it becomes possible to improve the precision of the alignment work.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail in the order of steps with reference to FIG.

First, as shown in FIG. 1, an element formation area is defined by a field oxide film 2, a gate oxide film 3 and a gate electrode 4 made of polysilicon are formed, and a silicon film with a thickness of 1 μm is formed over the entire surface including the alignment mark area. - Form an insulating film 5 made of a silicon oxide film.

After forming the insulating film 5, the insulation film 5 was heated at 90°C for 10 minutes in a nitrogen atmosphere.
Planarization is performed by heat treatment at °C.

Next, using a photolithography technique using a resist film, a contact hole 6 is formed in the insulating film 5 on the surface of the gate electrode 4 as shown in FIG. 1(b), and at the same time,
The insulating film 5 in the alignment mark portion is patterned to form an alignment mark 5a.

Next, as shown in FIG. 1(C), a resist film 7 with a thickness of 2 μm is formed on the entire surface, patterned to remove only the resist film 7 in the alignment mark portion, and tetrafluorinated film is applied using the alignment mark 5a as a mask. The semiconductor substrate 1 is etched to a depth of 1all by dry etching using carbon (CF) to form a recess 1a.

Finally, when the resist film 7 is removed and an aluminum film 8 with a thickness of 1u11 is formed on the entire surface by bias sputtering, as shown in FIG. A wiring layer is formed on the surface,
In the alignment mark section, alignment mark 5
The recess la formed in the semiconductor substrate 1 around point a is filled with an aluminum film 8 so that the surface is almost equal to the surface of the semiconductor substrate 1, and the aluminum film 8 is also formed on the surface of the alignment mark 5a, with a step difference of about 2μ. Become a lint.

In this way, when the aluminum film 8 is formed on the surface of the alignment mark 5a of the alignment mark part and on the semiconductor substrate 1 at the same time as the wiring layer made of the aluminum film 8 in the element formation part, the insulating film 5 with a film thickness of 1' μm is formed. It becomes possible to form an alignment mark consisting of the alignment mark 5a and the aluminum film 8 which is significantly thicker than the alignment mark 5a, and it becomes possible to perform highly accurate alignment work.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to form an alignment mark with a step difference larger than that of a conventional alignment mark by changing an extremely simple process, thereby improving the accuracy of alignment work. It is possible to provide a method for manufacturing a semiconductor device that can be expected to be significantly economical and to improve reliability.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view showing an embodiment of the present invention in order of steps, and FIG. 2 is a side cross-sectional view showing a conventional method for manufacturing a semiconductor device in order of steps. In the figure, 1 is a semiconductor substrate, 1a is a recess, 2 is a field oxide film, 3 is a gate oxide film, 4 is a gate electrode, 5 is an insulating layer, 5a is an alignment mark, 6 is a contact hole, 7 is a resist film, 8 indicates an aluminum film; dl Removal of resist film (7) and formation of aluminum I [(8) Figure 2 (side sectional view) showing an embodiment of the present invention in the order of steps (Part 2) (al Formation of insulation II! (15) Conventional semiconductor device (Part 1) !al Formation of insulation@(5) Contact hole (6) and alignment mark (5a)
Formation of contact hole (16) and alignment mark (1)
5a) Formation el Formation of Aluminum I (Part 3)

Claims (1)

[Scope of Claims] A step of forming an insulating film (5) on the entire surface of a semiconductor substrate (1) in which an element forming area and an alignment mark area are defined by a field insulating film (2); A step of forming a contact hole (6) in the film (5) and simultaneously patterning the insulating film (5) in the alignment mark portion to form an alignment mark (5a), and forming a resist film (7) on the entire surface. and patterning to remove the resist film (7) on the surface of the alignment mark portion, and etching the semiconductor substrate (1) around the alignment mark (5a); and removing the resist film (7). . A method for manufacturing a semiconductor device, comprising: forming a conductive film (8) on the entire surface.