JPS63151019A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain an accurate active region as designed, by providing a protruding part at each outer corner part, using an exposure mask having an active region pattern, in which each inner corner part has a slant side, and patterning an oxidation mask layer. CONSTITUTION:On a semiconductor substrate 31, a pad SiO2 film 32 and an Si3N4 film 33 are laminated and formed. This part is patterned by photolithography using an exposure mask 41. Only an active region forming area is made to remain. The exposure mask 41 is formed so that protruding parts 43 are formed at the outer corner parts of an active-region forming pattern 42 and the inner corner parts become slant sides 44. Therefore, Si3N4 film patterns 33a are formed in an L shape or a T shape, which has the protruding parts 34 and slant sides 35. With the Si3N4 film patterns 33a as masks, the device is oxidized in a steam atmosphere. Thus a field oxide film 36, in which right angles are maintained at the corners of the Si3N4 film patterns 33a, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a semiconductor device, and in particular, the present invention relates to a method for manufacturing a semiconductor device.
The present invention relates to a method of separating a field region and an active region using a method (ofSilicon).

(Prior Art) The conventional separation method described above will be explained with reference to FIG. However, in FIG. 3, a sectional view is shown on the left side, and a plan view is shown on the right side.

First, as shown in FIG. 3(a), pads S10. The film 2 and the Si3N4 film 3 are formed in an overlapping manner.

Next, the 55N4 film 3, pad Sin, and film 2 are patterned by photolithography using the exposure mask 11 shown in FIG. 4 as an example, as shown in FIG. 3(b). Leave it only in the area where it will be formed. Here, in the exposure mask 11 shown in FIG. 4, L-shaped and T-shaped active regions/4 turns 12 are formed, and Si3N4 is formed in the same shape as the active regions/9 turns 12.
Membrane 3 and nodes Sin.

Membrane 2 remains.

Next, using the remaining 5isN4 film 3 as a mask, the semiconductor substrate l is
By oxidizing it at 1000 DEG C. in a steam atmosphere for 2 to 3 hours, a thick field oxide film 4 is formed in the portion of the semiconductor substrate 1 where the Si3N4 film 3 is not present, as shown in FIG. 3(c).

After that, by removing the Si, N, and film 3 with phosphoric acid at about 170°C and the pad Si0g film 2 underneath with an HF-based solution, the substrate surface covered with them is removed with a third layer. figure(
Expose as shown in d). The exposed portion of the substrate surface is the active region 5, and the peripheral portion covered with the field oxide film 4 is the field region 6. The active region 5 is here formed by the active region pattern 12 of the exposure mask 11 in FIG. 4 and FIG. 3(b) + ((
Similar to the three 811N4 film patterns, L-shape and T-shape are obtained.

(Problems to be Solved by the Invention) However, in the conventional method as described above, field oxidation is full! In the oxidation formation step of step 4, 5iaN
4 Film 3/# Due to the concentration of stress on the corner of the turn, the S
i, N, the outer corners of the 3 film patterns are rounded (Figure 3 (e)
), a notch 21 was formed at the inner corner. As a result, at the corner of the active region 50, the field oxide film 4 intrudes into the active region 5 as shown by the circle in the right plan view of FIG. A decrease occurred. Also,
In a severe case, the active region 5 is cut off by the field oxide film 4 which has dug into the active region 5 at an inner corner.

This invention was made in view of the above points, and its purpose is to prevent the area of the active region from being reduced or cut due to rounded corners 9 or cuts in the oxidation-resistant mask layer pattern in the LOGO8 process, and to prevent the area of the active region from being cut as designed. An object of the present invention is to provide a method for manufacturing a semiconductor device that can obtain an accurate active area.

(Means for Solving the Problems) In the present invention, in the LOCO8 process, e) 74 turns of the oxidation-resistant mask layer by IJ graphing are performed using the following exposure mask. The exposure mask has a protrusion at the outer corner and an active region pattern with the inner corner as the hypotenuse.

(Function) When the oxidation-resistant mask layer is made into 9-turns using the exposure mask having the above-mentioned active area turns, the resulting oxidation-resistant mask layer No.J? The turn is similar to the active area pattern of the exposure mask, for example, the second
As shown in the plan view on the right side of Figure (b), the outer corner has a protruding portion and the inner corner is the oblique side, forming a notch turn. Then, when field oxidation is performed using the oxidation-resistant mask layer/4 turns as a mask, stress concentration occurs at the corners of the oxidation-resistant mask layer pattern; The symptoms that occur are due to the above-mentioned protrusion and oblique side, and the corners do not become rounded or notched, but only the corners become right angles, as shown in the plan view on the right side of FIG. 2(C). In the first place, it is desired to maintain the angle of the oxidation-resistant mask layer A turn at a right angle. In this invention as described above, the corners of the oxidation-resistant mask layer pattern have the desired shape of right angles due to deformation due to concentration of stress during field oxidation, and as a result, there is no intrusion of the field oxide film. It becomes possible to obtain an active area having a desired shape with right-angled corners as designed.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 2(a) to 2d) show an embodiment of the present invention in the order of steps, with the left side being a sectional view and the right side being a plan view.

As shown in FIG. 2(a), first, the semiconductor substrate 3
A pad 5i01 film 32 and a Si, N, film 33 are formed on top of each other.

Next, the 813N4 film 33, the pad sio, and the film 32 are patterned by photolithography using the exposure mask 41 shown in FIG. 1 to form an active region as shown in FIG. 2(b). Leave it only in the scheduled area. Here, an active area pattern 42 is formed in a FiL shape and a T shape in the exposure mask 41 shown in FIG.
and is formed so that the inner corner portion becomes the oblique side 44. Therefore, such an exposure mask 41
When the 5isN+ film 33 and the pad 5i01 film 32 are photolithographically formed using
The N4 film pattern 33a is similar to the active area no-turns 42 of the exposure mask 41 as shown in FIG. 2(b).
As shown in the right side plan view, there is a protrusion 3 on the outer corner.
4, and the inner corner is the hypotenuse 35.
It is formed into a T-shape or T-shape. However, the protruding portion 34 and the oblique side 35 are slightly rounded. Further, the pad Sin and the film pattern 32a below the 5isNa film pattern 33a are also obtained in the same shape as the 5isNa film pattern 33a. Note that if the patterning (photolithography) of the Si, N, film 33 and the 9-SiO film 32 is carried out using a positive resist, the active area pattern 42 of the exposure mask 41 is made of Cr.
It is formed as a transparent part.

Thereafter, the semiconductor substrate 31 is oxidized at 1000° C. for 2 hours in a steam atmosphere using the 818N4 film pattern 33a as a mask, so that the Si3N4 film pattern 33a on the semiconductor substrate 31 is no longer present, as shown in FIG. 2(c). A thick field oxide film 36 is formed in the portion.

At this time, stress concentration occurs at the corners of the 5IJN4 film pattern 33a, and conventionally the outer corners were rounded and the inner corners were notched, but in the above-mentioned St, N4 film pattern 9 turn 3
3a has a protrusion 34 on the outside corner and the hypotenuse 35 on the inside corner, so no rounded corners or notches occur, and as shown in FIG. As shown in the plan view on the right side of (c), the corners are at right angles. In other words, the desired shape of the right angle is maintained at the corner of the film pattern 33a by 5ilN.

After that, St, N, film pattern 33& and the pad S10 . By removing the film pattern 32m with phosphoric acid and HF-based liquid, the substrate surface covered with them is exposed as shown in FIG. 2(d), and an active region 37, which is the exposed portion of the substrate, is obtained. . This active area 3
7 is the 5isN4 film Noreen 3 during the field oxidation.
Since the corner of 3a is maintained at a right angle, the corner becomes a corresponding right angle, and the field oxide film 36 does not enter.
Obtained in the designed shape and area.

(Effects of the Invention) As described in detail above, according to the present invention, an exposure mask is used which has a protrusion at the outer corner and has an active area/turn with the inner corner as the hypotenuse. Since the oxidation-resistant mask layer pattern was formed using
During field oxidation, it is possible to prevent rounding of the outer corners of the mask layer and notches at the inner corners, and to maintain the corners at right angles.As a result, the field oxide film is prevented from penetrating into the active area at the corners. Since this can be prevented, reduction in the area of the active region or cutting can be prevented, and an accurate active region as designed can be obtained. The method of the present invention is particularly advantageous when forming fine active region nozzles.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the method for manufacturing a semiconductor device of the present invention, FIG. 1 is a plan view of an exposure mask, FIG. 2 is a sectional view and a plan view showing the manufacturing method in order of steps, FIG. 3 is a sectional view and a plan view showing the conventional method in the order of steps;
FIG. 4 is a plan view of an exposure mask used in the conventional method. 31... Semiconductor substrate, 32... (RAD 5i02 film, 32a---Illll Rad Si0 pattern, 33
- 5t8N4 film, 33a...SimN+ film/turn, 34...Protrusion, 35...Octenuse, 36...Field oxide film, 37...Active region, 41...
- Exposure mask, 42... active area pattern,
43... Protruding part, 44... Hypotenuse. Figure 1: Mask for number f and y of the entire book 1 day ￥ application column τ

Claims (1)

[Claims] By forming an oxidation-resistant mask layer on a semiconductor substrate, patterning this oxidation-resistant mask layer by photolithography, leaving it only in the area where the active region is to be formed, and oxidizing the semiconductor substrate using the oxidation-resistant mask layer pattern as a mask. In a method of manufacturing a semiconductor device in which a semiconductor substrate surface is separated into a field region and an active region, an exposure mask having a protrusion at an outer corner and an active region pattern with an inner corner as a hypotenuse is provided. A method of manufacturing a semiconductor device, comprising performing photolithography on the oxidation-resistant mask layer.