JP2913987B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device such as a semiconductor integrated circuit.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor integrated circuit, 2
In some cases, the photoresist layer is formed continuously.
For example, when manufacturing a semiconductor integrated circuit according MOSFET (metal oxide semiconductor field effect transistor), first, to be etched by Si ₃ N _4, or the like on the surface of the semiconductor substrate
After the material layer is formed, a first photoresist layer having an opening corresponding to an active region in which a transistor is formed is formed on the material layer to be etched, and a region not covered by the photoresist layer is formed. Material to be etched
The layer is selectively removed. Here, when the material layer to be etched is Si ₃ N ₄ , a carbon-based etching gas such as CF ₄ or CHF ₃ has been conventionally used. Then, without removing the first photoresist layer, a second photoresist layer is formed to cover the region where the inversion prevention ion implantation is not performed. 2 and 3 show the cross-sectional structure of the semiconductor integrated circuit at the stage where the above processing has been completed. Figure 2 and Figure
In 3 , 1 is a semiconductor substrate, 2 is a material layer to be etched ,
Reference numeral 3 denotes a first photoresist layer formed for patterning the material layer 2 to be etched, and reference numeral 4 denotes a second photoresist layer. In the state where the first and second photoresist layers 3 and 4 are formed as described above , ion implantation is performed. As a result, ions are implanted into a region not covered by any of the first and second photoresist layers. In the case where the source and drain regions of the transistor are formed after the formation of the gate electrode, the photoresist layer for forming the source and drain can be formed without removing the photoresist layer used for forming the gate electrode.
It is formed. Also in this case, a carbon-based etching gas has been used to etch polysilicon, polycide, and the like, which are gate electrodes.

[0003]

When the above-described conventional method for manufacturing a semiconductor device is used, a polymer layer having poor wettability is formed on the first photoresist layer 3 ;
There is a problem that the adhesion between the first and second photoresist layers 3 and 4 is deteriorated. For this reason, when the pattern of the first photoresist layer 3 has a narrow gap, the second photoresist layer 4 does not spread into the gap due to poor wettability of the surface of the first photoresist layer 3. , between the second photoresist layer 4 and the substrate 1, reference characters 2
The problems such as the formation of a cavity as indicated by 5 and the unevenness of the applied film thickness occurred. When the cavity 5 and the second photoresist layer 4 having an uneven thickness are formed, the patterning using the second photoresist layer 4 is not performed normally, and the patterning at the time of patterning is not performed. There is a problem that the maskability of the second photoresist layer 4 is poor, and ions are implanted into a region that should not be ion-implanted. As a countermeasure for this, it is conceivable to add a modification processing step of performing a plasma treatment or the like on the surface of the first photoresist layer 3 with an inert gas such as N ₂ or Ar. However, in such a case, the following problem occurs. Extra processes and equipment are required. As the steps are added, foreign substances attached to the semiconductor device increase, and the manufacturing yield decreases. The shape and dimensions of the first photoresist layer 3 change. Therefore, the mask of reduced area, such as shown by reference numeral 6 in FIG. 3, i.e., the original first
1 photo to should have been covered by the resist layer 3 not covered by the first photoresist layer 3 region is formed. In this case, if a process such as ion implantation or etching is performed using the first and second photoresist layers 3 and 4 as a mask, the process is also performed on a region where the maskability is reduced. The present invention has been made in view of the above-mentioned circumstances, and without increasing the number of steps, the first and second photoresist layers 3,
4 can be satisfactorily formed, and an object thereof is to provide a method of manufacturing a semiconductor device capable of accurately forming a desired element pattern.

[0004]

According to the present invention, there is provided an etchant.
A first pattern having a predetermined pattern is formed on the substrate surface on which the material layer is formed.
Forming a photoresist layer, the first photo
Material layer to be etched using resist layer as etching mask
An etching step of selectively removing a second photoresist having a predetermined pattern on the first photoresist layer and the substrate surface.
Forming a first photoresist layer
In the method of manufacturing a device, in the etching step, carbon may be used.
Is characterized in that an etching gas containing no gas is used .

[0005]

According to the above construction, the wettability and adhesion between the first and second photoresist layers are improved without performing the modification process.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below. In this manufacturing method, the error
After applying a first photoresist layer to the entire surface of the semiconductor substrate on which the etching layer is formed , exposure and development are performed in a predetermined pattern.
Using this as an etching mask, a gas containing no carbon, for example, SF ₆ , NF ₃ , Cl
Dry etching is performed using an etching gas such as ₂ to selectively remove the material layer to be etched. When an etching gas containing no carbon is used for etching using the first photoresist layer as a mask, a polymer layer that deteriorates wettability is not formed on the resist surface. Therefore, the adhesion between the first and second photoresist layers is improved. FIG. 1 shows a cross-sectional structure of the semiconductor device to which the present manufacturing method is applied at the stage of completing the patterning of the second photoresist layer 4 . Thus, the first and second processes can be performed without adding a process such as a modification process or a polymer layer removal process.
The adhesion between the photoresist layers 3 and 4 is improved, and the manufacturing yield of the semiconductor device is improved.

[0007]

As described above, in the method of manufacturing a semiconductor device according to the present invention, the material layer to be etched is formed.
A first photoresist layer having a predetermined pattern is formed on the substrate surface.
Forming and etching the first photoresist layer
And edge <br/> quenching step of selectively removing the etched material layer as Ngumasuku, the first photoresist layer and the
A second photoresist layer having a predetermined pattern on a substrate surface
Forming a semiconductor device.
In the etching step, an etchant containing no carbon
Since the etching gas is used , the adhesion between the first and second photoresist layers can be improved without increasing the number of manufacturing steps. Therefore, an effect is obtained in which an element pattern having a desired shape is accurately formed, and the manufacturing yield of the semiconductor device is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a semiconductor device to which a manufacturing method according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a cross-sectional structure of a semiconductor device to which a conventional manufacturing method is applied.

FIG. 3 is a diagram showing a cross-sectional structure of a semiconductor device to which a conventional manufacturing method is applied.

[Explanation of symbols]

1 ... semiconductor substrate, 3 ... first photoresist layer, 4
... Second photoresist layer.

Claims (1)

(57) [Claims] 1. A substrate surface on which a material layer to be etched is formed.
Forming a first photoresist layer in a predetermined pattern
Using the first photoresist layer as an etching mask
An etching step of selectively removing the material layer to be etched; and an etching step on the first photoresist layer and the substrate surface.
Forming a second photoresist layer having a predetermined pattern
In the method for manufacturing a semiconductor device, the method further comprises:
Semiconductor device manufacturing method characterized by using gas
Law.