JPH10209070A - Manufacturing method of semiconductor device and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve manufacturing efficiency and assure reliability of the product in a method of manufacturing a semiconductor device to form the self-alignment contact(SAC) using a silicon nitride film. SOLUTION: A resist 14 is coated on a transistor and meanwhile an N-type impurity is doped (step S1) to transistors 11, 12. After the resist 14 is removed, silicon nitride (Si3 N4 ) film 15 is formed (step S2) to the entire part of the silicon substrate 10, a resist 16 is coated on the transistors 11, 12, silicon nitride on the transistor 13 including the source and drain regions is removed and P-type impurity is doped (step S3) to the transistor 13. Under this condition, a thick silicon oxide film 17 is formed (step S4) to the entire part of the silicon substrate 10 and moreover a resist is coated on the silicon oxide film 17 as the masking and the aperture for SAC and the aperture for contact of the part other than SAC are simultaneously formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a semiconductor device for forming a self-aligned contact (SAC), and more particularly to a method of manufacturing a semiconductor device using a silicon nitride film as a stopper and a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, self-aligned contacts (SA
As a method for manufacturing a semiconductor device for forming C), there is a method using a silicon nitride film as a stopper.

FIG. 3 shows a conventional manufacturing method for forming a SAC using a silicon nitride film as a stopper.
First, as shown in step S11, the silicon substrate 30
Above, for example, three transistors 31, 32, 33
Are formed, a silicon nitride film 34 is formed thereon, and a thick silicon oxide (Si) is further formed thereon.
O ₂ ) film 35 is formed. Transistors 31, 32,
Each of the gate portions 33 has a silicon oxide film 31
Polysilicon (PolySilico) through 1,321,331
n) Films 312, 322, 332 are formed, and silicon oxide films 313, 323, 333 for offset are formed thereon.
However, sidewalls 314, 324, and 334 are further formed.

Here, transistors 31 and 32 are N-type MOS transistors, and transistor 33 is a P-type MOS transistor.
Transistor. Next, from the state of step S11, the gates, sources,
An opening for contact is formed in the drain. in this case,
An opening for a self-aligned contact (SAC), here, an opening for the sources and drains of the transistors 31 and 32, is formed before the gate. That is, step S
As shown in FIG. 12, a necessary portion is opened on the silicon oxide layer 35 from the state of step S11, a resist 36 is applied, a part of the silicon oxide layer 35 is removed by etching, and the SAC opening 37 is formed. To form

Then, as shown in step S13, etching is further performed to remove the silicon nitride film in the opening 37. After the opening 37 for SAC is formed in this way, an opening for contact other than SAC is formed.

[0006]

However, in the conventional method, it is difficult to simultaneously form the opening 37 for the SAC and the opening for the contact other than the SAC.

FIG. 4 is a view showing a procedure for simultaneously forming a SAC opening and a contact opening other than the SAC by a conventional manufacturing method. First, as shown in step S21, a resistor 36 is applied on the silicon oxide layer 35, and the silicon oxide of the opening forming portion for the SAC and the opening forming portion for the contact other than the SAC (here, the gate portion of the transistor 33) is formed. The layers are removed and openings 37,
38 are formed.

Next, as shown in step S22, the silicon nitride film in each of the openings 37 and 38 is removed. As a result, the opening 37 is in a state where aluminum is only deposited to form a contact. On the other hand, the opening 38 is further etched because the silicon oxide film 333 needs to be removed.

However, when this etching process is added, there is a problem that the number of steps of the photoresist increases and the working efficiency deteriorates. In order to etch only the opening 38, the portions of the sidewalls 314 and 324 covering the opening 37 are reduced by the etching.
2,322 cannot be ensured.

The present invention has been made in view of the above points, and has as its object to provide a method of manufacturing a semiconductor device and a semiconductor device capable of improving manufacturing efficiency and ensuring product reliability. I do.

[0011]

According to the present invention, there is provided a method of manufacturing a semiconductor device in which a self-aligned contact (SAC) is formed using a silicon nitride film as a stopper. Removing the silicon nitride film on the opening forming portion, forming a silicon oxide (SiO ₂ ) film on the removed portion of the silicon nitride film and on the upper portion of the remaining silicon nitride film, and forming the SAC opening; By removing the silicon oxide in the portion and the contact opening other than the SAC, the SAC opening and the contact opening other than the SAC are simultaneously formed, and the silicon nitride film on the SAC opening forming portion is removed. A method of manufacturing a semiconductor device is provided.

In such a manufacturing method, the silicon nitride film on the contact opening forming portion other than the SAC is removed, and then a silicon oxide film is formed on the removed portion and on the upper portion of the remaining silicon nitride film. Then, by removing the silicon oxide in the SAC opening forming portion and the contact opening forming portion other than the SAC, the SAC opening and the SA are removed.
A contact opening other than C is formed at the same time.
The silicon nitride film on the C opening formation portion is removed.

This eliminates the need for a step of forming an opening other than the SAC in the contact opening forming portion after removing the silicon oxide in the SAC opening forming portion. Therefore, the number of photoresist steps can be reduced. In addition, there is no need to reduce the number of sidewalls on the opening of the SAC opening formation portion, so that product reliability can be ensured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are views showing a method for manufacturing a semiconductor device according to the present embodiment. In FIG. 1, steps S1 to S
FIG. 2 shows steps S5 and S6. First, in the state of step S1, gate terminals of, for example, three transistors 11, 12, and 13 are formed on the silicon substrate 10. Silicon oxide (SiO ₂ ) films 11 are provided on the gate portions of the transistors 11, 12, and 13, respectively.
1, 121, 131 through the polysilicon film 112, 1
22 and 132 are formed thereon, and silicon oxide films 113, 123 and 133 for offset, and sidewalls 114, 124 and 134 are further formed thereon. The steps up to this point are performed by a conventional method.

Here, transistors 11 and 12 are used.
Is an N-type MOS transistor, and the transistor 13 is a P-type MOS transistor. In step S1, a resist 14 is applied on the P-type transistor 13, while
Doping an impurity I _N for N-type N-type transistors 11 and 12. After the resist 14 is removed, a silicon nitride (Si ₃ N ₄ ) film 15 is formed on the entire surface of the silicon substrate 10 as shown in step S2. Next, as shown in step S3, a resist 16 is applied on the transistors 11 and 12, the silicon nitride on the transistor 13 including the source and drain regions is removed, and the P-type impurity I _N is added to the transistor 13. Dope.

In this state, as shown in step S4,
A thick silicon oxide film (Si) is formed on the entire surface of the silicon substrate 10.
O ₂ ) 17 is formed. Further, as shown in step S5 in FIG. 2, a resist 18 is applied on the silicon oxide film 17 and masked, and an opening 19 for SAC and an opening 20 for contacts other than SAC are formed simultaneously.

Finally, as shown in step S6, the contact opening is formed by removing the silicon nitride in the opening 19 portion. Then, opening 1
9, contacts are formed in the openings 20 by depositing aluminum (not shown).

As described above, in this embodiment, the silicon oxide film 17 is formed after removing only the silicon nitride on the P-type transistor 13, and the SAC opening 19 and the SAC
Since the contact openings 20 other than those described above are formed simultaneously, the number of photoresist steps can be reduced as compared with the conventional method. Therefore, manufacturing efficiency is improved.

Further, since there is no fear of reducing a part of the side walls 114 and 124 over the SAC opening 19, the breakdown voltage between the polysilicon films 112, 122 and 132 and the contacts can be maintained, and the reliability of the product can be improved. Nature can be secured.

In this embodiment, for simplicity of description, only the state in which the SAC opening 19 is formed in the transistors 11 and 12 is shown, but it is formed using a normal mask instead of the SAC. Opening for gate contact (located on the front side of the drawing or on the other side)
Are formed simultaneously in the same manner as the opening 20 of the transistor 13.

[0021]

As described above, according to the present invention, the SAC
After removing the silicon nitride film on the contact opening forming portions other than the SAC opening forming portion and the contacts other than the SAC opening forming portion and the SAC, Since the SAC opening and the contact opening other than the SAC are simultaneously formed by removing the silicon oxide in the opening for forming the SAC, and finally, the silicon nitride film on the opening for forming the SAC is removed. There is no need for a step of forming a contact opening other than the SAC after removing the silicon oxide in the formation portion. Therefore, the number of photoresist steps can be reduced, and the manufacturing efficiency is improved.

Further, since there is no need to reduce the number of sidewalls on the opening of the SAC opening forming portion, the reliability of the product can be ensured.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method of manufacturing a semiconductor device according to an embodiment.

FIG. 2 is a diagram illustrating a method for manufacturing a semiconductor device of the present embodiment.

FIG. 3 shows a SAC using a silicon nitride film as a stopper.
FIG. 3 is a diagram showing a conventional manufacturing method for forming a semiconductor device.

FIG. 4 is a view showing a procedure for simultaneously forming a SAC opening and another contact opening by a conventional manufacturing method.

[Explanation of symbols]

10 ... silicon substrate, 11, 12 ... (N type)
Transistor, 13 ... (P-type) transistor, 1
4 ··· resist, 15 ··· silicon nitride film, 19 ·
..Opening (for SAC), 20... (For contact), 112, 122, 132... Polysilicon film.

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device in which a self-aligned contact (SAC) is formed using a silicon nitride film as a stopper, wherein the silicon nitride film on a contact opening other than the SAC is removed. A silicon oxide (SiO ₂ ) film is formed on the removed portion of the silicon nitride film and the upper layer of the remaining silicon nitride film, and the silicon oxide of the SAC opening forming portion and the contact opening forming portion other than the SAC is formed. Forming a SAC opening and a contact opening other than the SAC simultaneously, and removing the silicon nitride film on the SAC opening formation portion. 2. The method according to claim 1, wherein the contact opening other than the SAC is a source / drain diffusion region of a P-type transistor. 3. A semiconductor device in which a self-aligned contact (SAC) is formed using a silicon nitride film as a stopper, wherein the silicon nitride film on a contact opening forming portion other than the SAC is removed and the silicon nitride film is formed on an upper layer. A semiconductor device having a silicon oxide film formed thereon. 4. The semiconductor device according to claim 3, wherein the contact opening other than the SAC is a source / drain diffusion region of a P-type transistor.