KR0172735B1 - Fabricating method for exposure aligned-key - Google Patents

Abstract

The present invention discloses a method for manufacturing an exposure alignment key formed in a scribe line for pattern alignment in each step of a semiconductor device manufacturing process. The method comprises the steps of: forming an alignment key by etching the last polysilicon deposited on the sub-oxide film formed on the silicon substrate on which the scribe line is located simultaneously with the mask and etching process of the last polysilicon formed in the cell region; Stripping the mask photoresist and forming a planarization insulating film on the entire surface; Removing the formed planarization insulating film and the sub oxide film under the planarization insulating film; Depositing a layer of metal on the front surface; Forming a photoresist film on the entire surface.

Description

Manufacturing method of alignment key for exposure

1 is a process flow diagram showing a method for manufacturing an alignment key according to a conventional embodiment.

2 is a process flow diagram showing a method for manufacturing an alignment key according to an embodiment of the present invention.

3 is a process flow diagram illustrating a method of manufacturing an alignment key in accordance with another embodiment of the present invention.

4 is a plan view of a mask used in the manufacture of alignment keys of the present invention.

* Explanation of symbols for main parts of the drawings

11 and 21: sub semiconductor substrate 12 and 22: sub oxide film

13, 23: polysilicon 14, 17, 27: photosensitive film

15: planarization oxide film 16, 24: metal 1 layer

25: metal 2 layers

[Technical Field]

The present invention relates to a method for manufacturing an exposure alignment key formed on a scribe line for pattern alignment in each step of a semiconductor device manufacturing process.

[Private Technology]

In the process of manufacturing a semiconductor device, alignment and exposure are two purpose process steps. One purpose is to precisely align the wafer to the mask and the other purpose is to properly expose the photoresist through the mask after the alignment.

As a result of the right two steps, the pattern of the mask is transferred to the photosensitive film. The exposure polymerizes the photopolymerized film that is not polymerized depending on the composition of the resist and the mask or vice versa.

Alignment and exposure form the pattern of the mask in the photoresist and ultimately in the wafer.

The first mask in the alignment process is a mask for aligning the crystal structure, which of course has no pattern to align to the wafer. Because the first mask aligns the pattern with the crystal structure of the wafer, the crystal structure is not visible and indicates its direction as the position of the flat surface of the wafer. Thus, the first mask fits the flat of the wafer, which represents the crystal structure of the wafer. This is why all patterns are perpendicular to the flat.

In a manual alignment system, the wafer flat should be within + 2 ° of the aligner stage. Automatic aligner adjusts automatically.

After the first mask is aligned to the flat, the wafer is automatically placed under the mask and the exposed area is activated.

All masks other than the first mask must be aligned with the pattern of the wafer. Once the wafer is positioned, the wafer and mask are viewed simultaneously through a split field microscope of the aligner. This system (microscope viewing two objects) shows that one side of the wafer is misaligned with the other. The slight rotational misalignment between the wafer and the disk cannot be seen from only one side of the wafer. Split field microscopes provide a clear view of misalignments.

However, in most semiconductor devices, since the circuit pattern is very complicated, alignment by the pattern is impossible. Therefore, an alignment mark for alignment must be present in each mask. These marks usually have a cross or square shape, which is called a vernier pattern and is usually located at the edge of the mask.

1 is a flowchart illustrating a method of manufacturing an alignment key according to a conventional embodiment.

First, as shown in FIG. 1A, in the region where the mask alignment key is to be formed before the metal 1 contact mask, a sub-oxide layer 2 of about 10,000 mV or more is formed on the semiconductor substrate 1 of silicon. The key pattern 3 of the metal 1 contact mask is formed on the photoresist film, and the key is formed by the wet etching portion I of the curve and the dry etching portion II of the straight line by sequentially performing wet etching and dry etching. do.

Next, as shown in FIG. 1B, the metal 1 (4) is deposited after the photosensitive film 3 is stripped. Thereafter, the photosensitive film 5 is coated for the metal 1 masking process, and then aligned using an alignment beam as shown by an arrow.

As described above in the manufacturing method of the conventional alignment key, the key formed in the metal 1 contact process is used as the alignment key of the conventional metal 1 mask. This key is formed through wet etching and dry etching, and has a merit of being clearly recognized after deposition of metal 1, but has a disadvantage of inferior uniformity.

In addition, as the alignment accuracy is emphasized as the device gradually progresses to a high level, and a process such as annealing after deposition of the metal 1 is added, the conventional alignment key has a problem that the frequency of alignment fail is high and the accuracy is low.

[PROBLEMS TO BE SOLVED BY THE INVENTION]

Accordingly, the present invention reinforces uniformity, which is a disadvantage of the key formed in the first metal contact, by adopting a method of forming the key in the poly 4 layer and making the sharpness during the etching of the first metal contact. It is an object of the present invention to provide a method of manufacturing an alignment key for exposure that can be utilized.

[Configuration and Function of the Invention]

According to the present invention, the method of manufacturing the alignment key may include forming the alignment key by simultaneously etching the last polysilicon deposited on the sub-oxide film formed on the silicon substrate on which the scribe line is located with the mask and etching process of the last polysilicon formed in the cell region. ; Stripping the mask photoresist and forming a planarization insulating film on the entire surface; Removing the formed planarization insulating film and the sub oxide film under the planarization insulating film; Depositing a layer of metal on the front surface; Forming a photoresist film on the entire surface.

Since the alignment key manufacturing method of the present invention having the above-described configuration is made in the poly 4 process, in which the formation of the alignment key is the last polysilicon formation, the bending portion of the key is prevented from being formed by wet etching.

EXAMPLE

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a flowchart illustrating a method of forming an alignment key according to an embodiment of the present invention, and FIG. 4 is a reticle used in an area in which an alignment key is formed. It is for.

As shown in FIG. 2A, the sub silicon substrate 11 and the sub oxide 12 are formed in the scribe region of the wafer on which the alignment key is formed. An alignment key 13 is formed on the sub oxide 12 by using a poly 4 mask and an etching process in the poly 4 process, which is the last polysilicon forming layer in the cell region. The reticle for forming the alignment key 13 corresponds to FIG. 4A.

Then, after the photoresist mask 14 is stripped, a planarization process is performed to form a pattern as shown in FIG. Thereafter, when wet etching or dry etching is performed to form the metal 1 contact, the deposited planarized oxide film 15 and the suboxide 12 below it are etched. The reticle for metal 1 contact has the shape shown in FIG. 4B without chromium (Cr) in all regions for complete removal of the planarization oxide film 15 and formation of a clear key.

Next, as shown in c, when the metal 1 16 is deposited on the entire surface and the photosensitive film 17 is applied on the entire surface, a vertical pattern is formed without a curved portion. In the pattern formation of the deposited metal 1 (16), the mask in the key pattern area is chromed in all the key areas, as shown in FIG. 4C, which prevents etching of the metal key already formed, and removes particles and It is for use as a key in the metal 2 mask.

Thereafter, alignment is performed by irradiation of the beam for alignment.

Unlike the conventional case shown in FIG. 1, the pattern formed in the present invention forms a vertical pattern without a curved portion, thereby improving alignment accuracy.

In another embodiment of the present invention, as shown in FIG. 3A, when a single layer of metal is deposited as in FIG. 2C, and then a planarization oxide film is coated on the entire surface, as shown in FIG. 4D, chromium This area is opened using a metal-free contact mask. Therefore, all of the deposited planarization oxide films are removed, and only the metal one layer 24 is deposited.

Thereafter, as shown in FIG. 4B, metal 2 26 is deposited, and a photosensitive film is applied thereon. The reticle of metal 2 26 formed is in the form of chromium throughout the entire region of the key region, as shown in FIG. 4E, to prevent the key region from becoming a particle source.

Also in the second embodiment of the present invention, a vertical alignment key is formed to improve the alignment accuracy during the metal 2 alignment.

[Effects of the Invention]

As described above, the alignment key forming method of the present invention obtains a new metal 1 alignment key forming method using poly keys, thereby improving the alignment accuracy and preventing the alignment failure, thereby increasing productivity, reducing rework, and obtaining a stable device. . Moreover, since it can also be used for a metal 2 mask, the alignment problem in a metal layer can be eliminated.

Although specific embodiments of the present invention have been described and illustrated herein, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (3)

Forming an alignment key by simultaneously etching the last polysilicon deposited on the sub-oxide film formed on the silicon substrate on which the scribe line is located with the mask and etching process of the last polysilicon formed in the cell region; Stripping the mask photoresist and forming a planarization insulating film on the entire surface; Removing the formed planarization insulating film and the sub oxide film under the planarization insulating film; Thickening a metal layer on the front surface; Forming a photosensitive film on the front surface comprising the step of manufacturing a sorting key. The method of claim 1, further comprising depositing a metal layer and forming a photoresist on the entire surface after the deposition of the metal layer. The method according to claim 1 or 2, wherein the etching of the exposed polysilicon and the sub-oxide film below is performed by an anisotropic etching method.