JP3022396B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device having a MOS FET.

[0002]

2. Description of the Related Art In recent years, with miniaturization and high integration of semiconductor devices, thinning of a gate oxide film (insulating film) of a MOS transistor has been promoted. Accordingly, deterioration and destruction of the gate oxide film during the gate electrode formation process have become a problem.

A method of manufacturing a semiconductor device having a conventional MOS transistor will be described with reference to FIG. FIG. 4 (a)
First, a field oxide film 12 is formed on a main surface of a silicon substrate 11 as shown in FIG. Thereafter, as shown in FIG. 4B, a gate oxide film 13 is formed on the entire surface of the substrate by thermal oxidation.

Next, as shown in FIG. 4C, the gate oxide film 13 is not subjected to any chemical treatment, or the gate oxide film 13 is subjected to SPM cleaning and HPM cleaning, and then the gate oxide film 13 is subjected to a CVD method. Polycrystalline silicon 14 serving as an electrode is formed. Thereafter, the polycrystalline silicon 14 is patterned by dry etching or the like to form a gate electrode, and then impurities are introduced by ion implantation to form a diffusion layer region serving as a source or a drain, thereby completing a MOS transistor. Was.

[0005]

However, in the prior art shown in FIG. 4, since the measures against the initial breakdown voltage of the gate oxide film 13 are insufficient, the gate oxide film 13
There is a problem that the initial withstand voltage failure occurs.

An object of the present invention is to provide a method of manufacturing a highly reliable semiconductor device by preventing a failure in initial withstand voltage of a gate oxide film.

[0007]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device including a step of forming a gate electrode film on a gate insulating film, In a pretreatment step of forming the gate electrode film, the surface of the gate insulating film is treated with an amine-based solvent.

[0008] The treatment with the amine-based solvent includes at least immersion treatment, spray treatment, and spinner treatment.

Further, the gate electrode film is made of polysilicon.

[0010] The gate insulating film is a thin film formed by thermal oxidation.

Also, a solution of 70% monoethanolamine and 30% dimethyl sulfoside is used as the amine-based solvent. Using this solution, the photoresist on the gate insulating film is removed, and the gate insulating exposed from the photoresist is removed. The surface treatment of the film is performed in the same step.

[0012]

The surface of the insulating film is treated with an amine solvent. For this reason, the interface state between the insulating film and the polysilicon changes, so that the initial withstand voltage failure of the insulating film can be prevented.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a method for manufacturing a semiconductor device according to Embodiment 1 of the present invention in the order of steps.

As shown in FIG. 1A, an element isolation region 2 is formed on a main surface of a semiconductor substrate 1, and then, as shown in FIG. 1B, an insulating film 3 is formed on the entire surface of the substrate. .

Next, as shown in FIG.
Is treated with an amine solvent 4 for several minutes. Next, as shown in FIG. 1D, an electrode film 5 is formed on the insulating film 3.

After the treatment with the amine-based solvent shown in FIG. 1B, the insulating film 3 is subjected to alcohol treatment, water washing, SPM
A step of processing with a cleaning solution, an HPM cleaning solution, or the like may be performed.

(Embodiment 2) FIG. 2 is a sectional view showing Embodiment 2 of the present invention in the order of steps. Embodiment 2 of the present invention
Is applied to a method for manufacturing a semiconductor device having a direct contact.

As shown in FIG. 2A, an element isolation region 2 is formed on the main surface of the semiconductor substrate 1, and thereafter, as shown in FIG.
As shown in FIG. 7, an insulating film 3 is formed on the entire surface of the substrate.

Next, as shown in FIG. 2C, a photoresist 6 is applied on the insulating film 3, and the photoresist 6 is patterned by photolithography.
Then, an opening 6a exposing a part of the insulating film 3 is formed.

Next, as shown in FIG. 2D, a photoresist 6 is etched using an etching solution 7 such as buffered hydrofluoric acid.
Is used as a mask, a part of the insulating film 3 exposed in the opening 6a of the photoresist 6 is removed by etching.

Thereafter, as shown in FIG. 2E, the photoresist 6 is removed using a solution of 70% monoethanolamine and 30% dimethyl sulfoxide, which are amine solvents 4, and the insulating film 3 is removed. Perform surface treatment.

Thereafter, alcohol treatment, washing with water and HP
After performing M cleaning or the like, as shown in FIG. 2F, a polycrystalline silicon (polysilicon) 5 serving as a gate electrode (electrode film) is formed.
Is formed on the entire surface of the substrate.

The polycrystalline silicon 5 is patterned to form a gate electrode. The gate electrode 5 is directly bonded to the silicon substrate 1 through an opening 3a opened in a part of the insulating film 3.

The solution of 70% monoethanolamine and 30% dimethyl sulfoxide, which are the amine solvents 4 used in the second embodiment of the present invention, has the property of peeling off the photoresist. Utilizing the nature,
It is characterized in that the removal of the photoresist 4 on the gate oxide film 3 and the surface treatment of the gate oxide film 3 are performed simultaneously.

In the first and second embodiments, the treatment using the amine-based solvent is carried out by immersing the surface of the insulating film 3 in the amine-based solvent 4 or by treating the surface of the insulating film 3 with the amine-based solvent. A method of spraying the amine-based solvent 4 for treatment, a method of rotating the insulating film 3 to spray the amine-based solvent 4 onto the surface of the insulating film 3, and the like are used.

(Example) Next, the first embodiment of the present invention is
An example in which a method for manufacturing a semiconductor device having an S-type transistor is applied will be described as an example.

As shown in FIG. 1A, a field oxide film (element isolation region) 2 is formed on a silicon substrate (semiconductor substrate) 1. Thereafter, as shown in FIG. 1B, a gate oxide film (insulating film) 3 is formed on the silicon substrate 1 by thermal oxidation.
Form 5Å.

Next, as shown in FIG. 1C, the surface of the gate oxide film 3 is treated with a solution of 70% monoethanolamine and 30% dimethyl sulfoxide for about 10 minutes.

Thereafter, alcohol treatment, washing with water and HP
After the M cleaning, as shown in FIG. 1D, polycrystalline silicon 5 as a gate electrode film is
Grows $ 00. Thereafter, the polycrystalline silicon 5 is patterned by dry etching or the like to form a gate electrode, impurities are introduced by ion implantation, and a diffusion layer region serving as a source or a drain is formed.
The S-type transistor is completed.

FIG. 3A is a sectional view showing an N-channel MOS capacitor formed based on the embodiment of the present invention shown in FIG. The manufacturing method will be briefly described below. After forming the polycrystalline silicon 5 shown in FIG. 1D, phosphorus, which is an N-type impurity, is introduced into the polycrystalline silicon 5 by diffusion. Thereafter, the polycrystalline silicon 5 is patterned by using dry etching or the like, thereby forming an electrode 5 of a MOS capacitor. Further, a P-type silicon substrate is used as the semiconductor substrate 1.

Next, an accelerated breakdown test was performed to evaluate the reliability of the gate oxide film 3 of the N-channel MOS type capacitor formed by the above method.

As shown in FIG. 3A, the area S = 300
A constant current (PN tunnel current) is passed through the gate oxide film 3 of the N-channel MOS type capacitor of 300 μm ² until the current density J = 80 mA / cm ² until the gate oxide film 3 is broken. The total charge Q per unit area injected into the gate oxide film 3 up to the breakdown is Q = J × t (C
/ Cm ² ), which is defined as Qbd. The same test is performed on many (several tens or more) samples, and the obtained Qbd values are plotted on Weibull probability paper. From the slope of the graph, the failure mode of destruction is estimated.
The direction of the current was such that a negative voltage was applied to the gate electrode side so that the substrate side was in the accumulation state.

Next, the results of the reliability test will be described. FIG. 3B is a Weibull plot of the Qbd of the gate oxide film of the N-channel MOS capacitor formed according to the present embodiment and the Qbd of the N-channel MOS capacitor in which the gate oxide film is not treated with an amine-based solvent. ). When many initial defects exist in the gate oxide film, the number of samples having a small Qbd value increases, and the slope of the Weibull plot decreases.

In the case of the N-channel MOS capacitor manufactured in the conventional example, there are many samples with small Qbd, and the slope of the straight line is small. This indicates that there are many initial failures of the gate oxide film.

On the other hand, in the case of the N-channel MOS capacitor manufactured according to the embodiment of the present invention, the slope of the straight line is large. All of these breakdowns are considered to indicate the intrinsic breakdown voltage of the gate oxide film, and no sample is considered to have been destroyed due to the initial failure.

[0037]

As described above, according to the present invention, the state of the surface of the polysilicon formed on the insulating film is changed by treating the surface of the insulating film with the amine-based solvent. Can be reduced, and a highly reliable semiconductor device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in the order of steps.

FIG. 2 is a sectional view showing Embodiment 2 of the present invention in the order of steps.

FIG. 3A is a cross-sectional view illustrating an operation mode of an embodiment of the present invention, and FIG. 3B is a characteristic diagram illustrating a result of an operation in the present invention and a conventional example.

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate (silicon substrate) 2 element isolation region (field oxide film) 3 insulating film (gate oxide film) 4 polycrystalline silicon (polysilicon)

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 29/78 H01L 21/336 H01L 21/316 H01L 21/31

Claims (5)

(57) [Claims] 1. A method of manufacturing a semiconductor device including a step of forming a gate electrode film on the gate insulating film, at a pretreatment step of forming the gate electrode film, the gate
A method for manufacturing a semiconductor device, comprising: treating a surface of an insulating film with an amine-based solvent. 2. The method according to claim 1, wherein the treatment with the amine-based solvent includes at least immersion treatment, spray treatment, and spinner treatment. 3. The method according to claim 1, wherein the gate electrode film is made of polysilicon. 4. The method according to claim 1, wherein the gate insulating film is a thin film formed by thermal oxidation. 5. A solution of 70% monoethanolamine and 30% dimethyl sulfoside as the amine-based solvent. Using this solution, the photoresist on the gate insulating film is removed, and the gate exposed from the photoresist is removed. 2. The method according to claim 1, wherein the surface treatment of the insulating film is performed in the same step.
13. The method for manufacturing a semiconductor device according to item 5.