JPH06204237A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of semiconductor device capable of displaying the specific electric characteristics without deteriorating the reliability upon the device. CONSTITUTION:An oxide film 15 wherein bird's beaks 15a are formed between the parts corresponding to the edge part of a gate electrode 8 and the edge parts of LDD regions 10 of a P type semiconductor substrate 8 is formed by removing a gate oxide film 5 so as to oxidize the removed part.

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 more particularly to an N channel type MOS having an LDD region.
The present invention relates to a method for manufacturing a transistor.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing an N-channel type MOS transistor having a conventional LDD structure. In the figure, 1 is a P-type semiconductor region, 2 is an N-type semiconductor region formed so as to surround the P-type semiconductor region 1, and 3 is a P-type semiconductor composed of a P-type semiconductor region 1 and an N-type semiconductor region 2. The impurity concentration of the substrate is adjusted so that desired electrical characteristics can be obtained. Reference numeral 4 is an oxide film for separating elements formed on the semiconductor substrate 3, and reference numeral 5 is a gate oxide film formed between both oxide films 4 on the semiconductor substrate 3.

Reference numeral 6 denotes a semiconductor substrate 3 via a gate oxide film 5.
The polycrystalline silicon thin film formed above, 7 is a refractory metal thin film formed on this polycrystalline silicon thin film 6, 8 is a gate electrode composed of the polycrystalline silicon thin film 6 and the refractory metal thin film 7, and 9 is this Spacers formed on the sidewalls of the gate electrode 8 are N-type LDD regions formed between the oxide films 4 and the gate electrode 8 in the semiconductor substrate 3, and 11 are formed below the LDD regions 10. , LDD region 10
Together with this, it is a high-concentration N-type impurity region that constitutes the source and drain regions.

Next, a method of manufacturing the semiconductor device having the above structure will be described with reference to FIG. First, FIG.
As shown in (a), an oxide film 4 is formed on both ends of the semiconductor substrate 3, and a gate oxide film 5 is formed between the oxide films 4. Next, as shown in FIG. 6B, a polycrystalline silicon thin film 6 and a refractory metal thin film 7 are sequentially deposited on the surface of the semiconductor substrate 3 through the gate oxide film 5 and molded to form a gate electrode 8. To do. Then, as shown in FIG. 6C, N-type impurities are implanted around the gate electrode 8 in the direction of arrow 12 by the large-angle tilt ion implantation method to form an N-type LDD.
Region 10 is formed.

Next, as shown in FIG. 6D, an oxide film 13 is deposited on the entire surface of the semiconductor substrate 3 by the CVD method. Then, as shown in FIG. 6E, the spacer 9 is formed on the side wall of the gate electrode 8 by removing the desired portion of the oxide film 13 by dry etching and removing the other portion. Finally, as shown in FIG. 5, N-type impurities are ion-implanted from the direction of arrow 14 to form high-concentration N-type impurity regions 11, and the semiconductor device is completed.

[0006]

As described above, since the conventional semiconductor device manufacturing method adjusts the concentration profile of the N-type impurity in the LDD region by the large tilt angle ion implantation method, it is not possible to perform fine concentration profile adjustment. There is a problem that it is difficult to obtain desired electrical characteristics because it is possible.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method of manufacturing a semiconductor device capable of obtaining desired electrical characteristics without degrading reliability. To aim.

[0008]

[Means for Solving the Problems] Claim 1 according to the present invention
In the method of manufacturing a semiconductor device, the step of forming a gate electrode on a P-type semiconductor substrate, the step of forming an LDD region by implanting N-type impurity ions on the P-type semiconductor substrate, and the step of forming a gate oxide film And a step of forming an oxide film having bird's beaks formed between the edge portion of the gate electrode and the portion corresponding to the edge portion of the LDD region of the P-type semiconductor substrate by oxidizing the removed portion. It is a thing.

Further, according to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, which comprises forming a gate electrode on a P-type semiconductor substrate and implanting N-type impurity ions on the P-type semiconductor substrate. A bird's beak is formed between the edge portion of the gate electrode and the portion corresponding to the edge portion of the LDD region of the P-type semiconductor substrate by removing the gate oxide film and oxidizing the removed portion. It comprises a step of forming the formed oxide film, a step of forming a spacer on the side wall of the gate electrode, and a step of implanting N-type impurity ions into the LDD region.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of forming a gate electrode on a P-type semiconductor substrate and implanting N-type impurity ions on the P-type semiconductor substrate. To form an LDD region, a step of forming a spacer on the side wall of the gate electrode in at least two steps or more, and an N-type impurity ion is implanted into the LDD region at each step of forming the spacer. And a process.

[0011]

The bird's beak between the edge portion of the gate electrode and the portion corresponding to the edge portion of the LDD region of the P-type semiconductor substrate, which is formed by the method of manufacturing a semiconductor device according to the first aspect of the present invention, is Alleviates the electric field strength at the edges, and shallows the LDD region as a diffusion layer,
Improve short channel resistance.

The spacer formed by the method for manufacturing a semiconductor device according to the second aspect of the present invention prevents ions of N-type impurities implanted in the LDD region from entering near the side wall of the gate electrode. The density profile of the LDD region is adjusted without changing the effective channel length of the semiconductor device.

Further, the spacer formed in at least two steps in the method for manufacturing a semiconductor device according to the third aspect of the present invention is LDD at each step of forming the spacer.
The concentration profile of the LDD region is adjusted and the ability to control the depth of the LDD region as a diffusion layer is improved by changing the region that blocks N-type impurity ions implanted into the region stepwise.

[0014]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view showing a manufacturing process of a semiconductor device according to a first embodiment of the present invention. In the figure, first, as shown in FIG. 1A, a gate electrode 8 is formed on a P-type semiconductor substrate 3 with a gate oxide film 5 interposed therebetween, as shown in FIG. 1B. As described above, N-type impurities are implanted around the gate electrode 8 in the direction of arrow 12 by the large-angle tilt ion implantation method to form N-type LDD regions 10 as source and drain regions.

Next, as shown in FIG. 1C, the portion of the gate oxide film 5 where the gate electrode 8 is not formed is removed,
By oxidizing this portion at a temperature of 900 ° C. or less to a depth of about angstrom, bird's beaks 15a are formed between the edge portion of the gate electrode 8 and the portion corresponding to the edge portion of the LDD region 10 of the semiconductor substrate 3. Oxide film 1
5 is obtained, and the semiconductor device is completed. According to the first embodiment, since the bird's beak 15a is formed between the edge portion of the gate electrode 8 and the portion corresponding to the edge portion of the LDD region 10, the electric field strength at the edge portion of the gate electrode 8 is relaxed, Generation of current in the semiconductor substrate 3 is suppressed, and
Since the concentration profile of the LDD region 10 corresponding to the lower part of the gate electrode 8 can be adjusted, the short channel margin can be improved.

Example 2. Although the oxide film 15 is formed after forming the LDD region in the first embodiment, the same process can be performed if the LDD region 10 is formed after the reverse process, that is, the oxide film 15 having the bird's beaks 15a is formed. A semiconductor device is obtained.

Embodiment 3. FIG. 2 is a sectional view showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention. In the figure, first, as shown in FIG. 2A, the edge portion of the gate electrode 8 and the LDD region 1 of the semiconductor substrate 3 as in the first embodiment.
Bird's beak 15 between the part corresponding to the edge part of 0
An oxide film 15 having a formed thereon is formed. Next, FIG.
As shown in (b), as in the conventional case, an oxide film (not shown) is deposited on the entire surface of the semiconductor substrate 3 by a CVD method, and a desired portion of the oxide film is left to dry the other portion. The spacer 9 is formed on the side wall of the gate electrode 8 by removing it, and as shown in FIG.
A second LD is formed by implanting N-type impurities around the gate electrode 8 in the direction of arrow 12 by a large tilt rotation ion implantation method.
The D region 16 is formed.

Finally, as shown in FIG. 2D, N-type impurities are ion-implanted from the direction of arrow 14 to form an N-type impurity region 17. And the LDD formed in this way
Region 10, second LDD region 16 and N-type impurity region 17
By configuring the source and drain regions 18, the semiconductor device is completed. According to the third embodiment, the bird's beak 15a is formed in the same manner as in the above respective embodiments, and the LD
N-type impurity ions implanted in the D region 10 are prevented from entering the vicinity of the side wall of the gate electrode 8 by the spacer 9, so that the source and drain regions 18 can be formed without changing the effective channel length of the semiconductor device. The concentration profile of can be adjusted, and the drive capability of the semiconductor device can be compensated and improved.

Example 4. 3 is a sectional view showing a method for manufacturing a semiconductor device according to a fourth embodiment of the present invention. In the figure, first, as shown in FIG. 3A, an oxide film 15 having bird's beaks 15a is formed between the edge portion of the gate electrode 8 and the portion corresponding to the edge portion of the LDD region 10 of the semiconductor substrate 3. By depositing an oxide film (not shown) on the entire surface of the semiconductor substrate 3 by the CVD method and removing the other part of the oxide film by dry etching leaving a desired part, the side wall of the gate electrode 8 is removed. The one-stage spacer 9a is formed, and N-type impurities are implanted around the gate electrode 8 in the direction of arrow 12 by the large tilt rotation ion implantation method as in the case of the third embodiment, and the second LDD region 19 is formed.
To form.

Next, as shown in FIG. 3B, an oxide film (not shown) is again deposited on the entire surface of the semiconductor substrate 3 by the CVD method, and another portion of the oxide film is dry-etched by leaving a desired portion. By removing the portion, a second-stage spacer 9b is formed on the side wall of the gate electrode 8, and the spacer 9 is formed together with the first-stage spacer 9a. By injecting into the periphery of the gate electrode 8 from the direction of 12, the third L
The DD region 20 is formed.

Finally, as shown in FIG. 3C, N type impurities are ion-implanted from the direction of arrow 14 to form the N type impurity region 2.
1 is formed. Then, the LDD region 10, the second LDD region 19, and the third LDD region 20 thus formed are formed.
And the N-type impurity region 21, the source and drain region 2
The semiconductor device is completed by constructing 2. According to the fourth embodiment, the bird's beak 1
5a is formed and the spacer 9 is formed stepwise to change the implantation region of the implanted N-type impurity ions stepwise, without changing the effective channel length of the semiconductor device. Further, since the concentration profile of the source / drain region 22 can be finely adjusted, it is possible to compensate and improve the driving ability of the semiconductor device.

Embodiment 5. In the fourth embodiment, the example in which the spacer 9 is formed in two steps is shown, but the present invention is not limited to this, and a desired spacer is formed in three or more steps, and the LDD region is formed in each step of forming the spacer. By implanting N-type impurity ions, it is possible to finely adjust the concentration profile of the LDD region.

Example 6. FIG. 4 is a sectional view showing a method of manufacturing a semiconductor device according to a sixth embodiment of the present invention. In the figure, first, as shown in FIG. 4 (a), as in the conventional case, an N-type impurity is formed by an arrow 12 by a large-angle tilt ion implantation method.
To form an N-type LDD region 10 by injecting it around the gate electrode 8 from the direction of FIG.
An oxide film (not shown) is deposited on the entire surface by the CVD method, and the oxide film is removed by dry etching while leaving the desired part, and the other part is removed.
A first-stage spacer 9c is formed on the side wall of the gate electrode 8, and N-type impurities are implanted around the gate electrode 8 in the direction of arrow 12 by the large-angle tilt ion implantation method to form the second LDD region 23.

Next, as shown in FIG. 4 (c), an oxide film (not shown) is again deposited on the entire surface of the semiconductor substrate 3 by the CVD method, and this oxide film is dry-etched by leaving a desired portion. The second step spacer 9d is formed on the side wall of the gate electrode 8 by removing the portion of FIG. 9 and the spacer 9 is formed together with the first step spacer 9c, and the N-type impurity is again formed by the large tilt rotation ion implantation method. By injecting into the periphery of the gate electrode 8 from the direction of arrow 12, the third L
The DD region 24 is formed.

Finally, as shown in FIG. 4D, N-type impurities are ion-implanted from the direction of arrow 14 to form N-type impurity regions 25. And the LDD formed in this way
Region 10, second LDD region 23 and third LDD region 2
The semiconductor device is completed by forming the source and drain regions 26 by 4 and the N-type impurity region 25.
According to the sixth embodiment, since the spacer 9 is formed stepwise and the implantation region of the implanted N-type impurity ions is varied stepwise, the concentration profile of the source and drain regions 26 can be finely adjusted.

Example 7. Although the example of forming the spacer 9 in two steps has been described in the sixth embodiment, the present invention is not limited to this, and the desired spacer is formed in three or more steps, and the LDD region is formed in each step of forming the spacer. By implanting N-type impurity ions, it is possible to finely adjust the concentration profile of the LDD region.

[0027]

As described above, according to claim 1 of the present invention, a step of forming a gate electrode on a P-type semiconductor substrate,
A step of forming an LDD region by implanting N-type impurity ions on the P-type semiconductor substrate, and a step of removing the gate oxide film and oxidizing the removed portion to form an edge portion of the gate electrode and the P-type semiconductor substrate. A step of forming an oxide film in which bird's beaks are formed between the LDD region and a portion corresponding to the edge portion, and a step of forming a gate electrode on the P-type semiconductor substrate according to claim 2, LDD by implanting N-type impurity ions on a P-type semiconductor substrate
A step of forming a region, an edge portion of the gate electrode by removing the gate oxide film, and oxidizing the removed portion,
A step of forming an oxide film having bird's beaks formed between the p-type semiconductor substrate and a portion corresponding to an edge portion of the LDD region, and a step of forming a spacer on a side wall of the gate electrode,
Implanting N-type impurity ions into the LDD region, and forming the gate electrode on the P-type semiconductor substrate according to claim 3; and implanting N-type impurity ions on the P-type semiconductor substrate. A step of forming an LDD region by implanting, a step of forming a spacer in the sidewall of the gate electrode in at least two steps or more, and an ion of an N-type impurity is implanted into the LDD area at each step of forming the spacer. Since the steps are provided, it is possible to provide a method for manufacturing a semiconductor device capable of obtaining desired electrical characteristics without degrading reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention.

FIG. 3 is a sectional view showing a method for manufacturing a semiconductor device according to a fourth embodiment of the present invention.

FIG. 4 is a sectional view showing a method for manufacturing a semiconductor device according to a sixth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the configuration of a conventional semiconductor device.

6 is a cross-sectional view showing the method of manufacturing the semiconductor device shown in FIG.

[Explanation of symbols]

 3 Semiconductor Substrate 4, 15 Oxide Film 5 Gate Oxide Film 8 Gate Electrode 9 Spacers 9a, 9c First Stage Spacer 9b, 9d Second Stage Spacer 10 LDD Regions 11, 17, 21, 25 N-type Impurity Region 15a Bird's Beak 16 , 19, 23 Second LDD region 18, 22, 26 Source and drain region 20, 24 Third LDD region

Claims (3)

[Claims] 1. A step of forming a gate electrode on a P-type semiconductor substrate, a step of forming an LDD region by implanting ions of an N-type impurity on the P-type semiconductor substrate, and removing a gate oxide film. Oxidizing the removed portion to form an oxide film having bird's beaks formed between the edge portion of the gate electrode and the portion corresponding to the edge portion of the LDD region of the P-type semiconductor substrate. A method of manufacturing a semiconductor device, comprising: 2. A step of forming a gate electrode on a P-type semiconductor substrate, a step of forming LDD regions by implanting N-type impurity ions on the P-type semiconductor substrate, and removing a gate oxide film. Forming an oxide film having bird's beaks formed between the edge portion of the gate electrode and the portion corresponding to the edge portion of the LDD region of the P-type semiconductor substrate by oxidizing the removed portion. A method of manufacturing a semiconductor device, comprising: a step of forming a spacer on a sidewall of the gate electrode; and a step of implanting N-type impurity ions into the LDD region. 3. A step of forming a gate electrode on a P-type semiconductor substrate, a step of forming an LDD region by implanting N-type impurity ions on the P-type semiconductor substrate, and a sidewall of the gate electrode. A method of manufacturing a semiconductor device, comprising: a step of forming a spacer in at least two steps or more; and a step of implanting N-type impurity ions into the LDD region at each step of forming the spacer. .