JPH06112309A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device which can reduce a step when obtaining a leading electrode from a source/drain region without making an electrical connection to a field region which is demarcated by the LOCOS method by eliminating a poor influence of the bird's beak of a field oxide film and preventing a rapid increase in Vth for improving the method for demarcating the channel width of a transistor and to provide the manufacturing method. CONSTITUTION:The title manufacture is provided with a process for forming silicon oxide film and silicon nitride film on the surface of a semiconductor substrate 1 by lamination, forming a channel cut 4 on the semiconductor substrate 1 by injecting an impurity with silicon nitride film where the silicon nitride film is subjected to patterning as a mask, forming a field oxide film 5 by performing selective oxidation with the silicon nitride film a mask. and then for demarcating the channel region of a transistor and that for forming the transistor where a channel width is demarcated by patterning the field oxide film 5 after eliminating the silicon nitride film and the silicon oxide film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method for defining the channel width of a transistor. With the recent high integration of semiconductor devices, it is required to reduce the size of the region where a transistor is formed.

Although the transistor region of fine dimensions is defined by the Locos method, when the transistor region is defined by the field oxide film by using the Locos method, a projection called bird's beak is formed on the field oxide film that defines the transistor region. The bird's beak deteriorates the dimensional accuracy of the transistor region and adversely affects the transistor characteristics.

Under the circumstances as described above, there is a demand for a semiconductor device capable of defining a transistor region without being adversely affected by the bird's beak by the Locos method.

[0004]

2. Description of the Related Art Conventional semiconductor devices of first to fourth examples and a method of manufacturing the same will be described in detail with reference to FIGS.

FIG. 7 is a diagram showing a method of manufacturing a semiconductor device of a first conventional example in process order, FIG. 8 is a diagram showing a method of manufacturing a semiconductor device of a second conventional example in process step, and FIG. 9 is a conventional method. FIG. 10 is a side sectional view showing a semiconductor device of a third example, and FIG. 10 is a side sectional view showing a semiconductor device of a conventional fourth example.

In order to manufacture the semiconductor device of the first conventional example, first, as shown in FIG. 7A, a silicon oxide film 82 and a silicon nitride film are formed by laminating on the surface of a semiconductor substrate 81,
The silicon nitride film is patterned to form a silicon nitride film 83.

Next, as shown in FIG. 7B, using the silicon nitride film 83 as a mask, impurities are implanted to form a channel cut 84, and the silicon nitride film 83 is used as a mask to selectively oxidize the field. An oxide film 85 is formed.

Next, the silicon nitride film 83 and the silicon oxide film
After removing 82, gate oxide 87 is removed as shown in Figure 7 (c).
A conductive layer to be a gate electrode is formed through the above and patterned to form a gate electrode 88.

In the conventional semiconductor device of the first example as shown in FIG. 7C thus formed, the dimensions of the patterned silicon nitride film 83, that is, the designed channel width b and the formed field. A gap between the oxide films 85, that is, a dimensional difference from the effective channel width a, that is, a shift amount due to bird's beak occurs.

Since this shift amount fluctuates due to variations in the film thicknesses of the silicon oxide film 82, the silicon nitride film 83, the field oxide film 85, etc., the same design channel width b
In contrast, the effective channel width a varies.

In order to manufacture the semiconductor device of the second conventional example, first, as shown in FIG. 8A, impurities are implanted into the entire surface of the semiconductor substrate 91 to form a channel cut 94, and then the semiconductor substrate 91 is formed. A silicon oxide film to be a field oxide film 95 that defines an element formation region is formed on the entire surface of the film, and the silicon oxide film is patterned as shown in the figure to form the field oxide film.
Forming 95.

Then, as shown in FIG. 8B, a conductive layer to be a gate electrode is formed through a gate oxide film 97 in an element forming region defined by the field oxide film 95 and patterned to form a gate. The electrode 98 is formed.

Next, as shown in FIG. 8C, a source 99 and a drain 100 are formed in the channel cut 94 of the semiconductor substrate 91 using the field oxide film 95 and the gate electrode 98 as a mask. In the conventional semiconductor device of the second example as shown in FIG. 8C thus formed, the field oxide film is formed.
Since there is a channel cut 94 under 95, _Vth of the transistor characteristic varies depending on the size of the channel width.

In order to manufacture the semiconductor device of the third conventional example, first, as shown in FIG. 9, a silicon oxide film and a silicon nitride film are laminated on the surface of a semiconductor substrate 111 to form a silicon nitride film. Patterning is performed to form a silicon nitride film, the silicon nitride film is used as a mask to inject impurities to form a channel cut 114, and the silicon nitride film is used as a mask to selectively oxidize to form a field oxide film 115. The field oxide film 115 is patterned in the element formation region on the left side of the drawing.

Then, after removing the silicon nitride film and the silicon oxide film, as shown in FIG. 9, a conductive layer to be a gate electrode is formed through the gate oxide film 117 and patterned to form a gate electrode 118, and a gate electrode 118 is formed. A source 119 and a drain 120 are formed using the electrode 118 as a mask.

Finally, an insulating film 121 is formed on the entire surface, and the drain 120 of the left transistor and the source of the right transistor are formed.
A contact hole is formed at the position of 119, a conductive layer extending in the contact hole and on the surface of the insulating film 121 is formed and patterned, and a lead electrode 122 is formed to electrically connect the left and right transistors.

In the thus formed conventional semiconductor device of the third example as shown in FIG. 9, a contact hole is formed to electrically connect the left transistor and the right transistor, A conductive layer extending in the contact hole and on the surface of the insulating film 121 must be formed and patterned to form the extraction electrode 122.

To manufacture the semiconductor device of the fourth conventional example, as shown in FIG. 10, impurities are implanted into the entire surface of the semiconductor substrate 131 to form a channel cut 134, and the semiconductor substrate is formed.
A silicon oxide film serving as a field oxide film 135 that defines an element formation region is formed on the entire surface of 131, and the silicon oxide film is patterned as shown in the figure to form a field oxide film 135.

Then, as shown in the figure, a conductive layer to be a gate electrode is formed through the gate oxide film 137 in the element formation region defined by the field oxide film 135.
The gate electrode 138 is formed by patterning.

Then, a source 139 and a drain 140 are formed in the channel cut 134 of the semiconductor substrate 131 using the field oxide film 135 and the gate electrode 138 as a mask in the figure. In the conventional semiconductor device of the fourth example as shown in the figure formed in this way, since there is a channel cut 134 under the field oxide film 135, the _Vth of the transistor characteristic varies depending on the size of the channel width. Is occurring.

[0021]

In the conventional semiconductor device of the first example described above, a region called a bird's beak is formed in the field oxide film to narrow the region, and the shift amount is the silicon oxide film. , The silicon nitride film, the field oxide film, and the like have variations in the effective channel width with respect to the same designed channel width due to variations in the film thickness. In the conventional semiconductor device of the second example, In a transistor with a small width, the channel cut has a large influence of the exudation formed by penetrating into the region, and V _th has already risen, so there is little fluctuation, but in a transistor with a large channel width, the channel cut the influence of the exudation was less there is a problem that V _th increases rapidly, semiconductors third conventional example However, in the semiconductor device of the fourth example of the related art, the field oxide film must be patterned to form an electrical connection with the field region defined by the Locos method. When the extraction electrode is taken from the defined source / drain region, there is a problem that the step may be large because the extraction electrode is extracted from a deep position.

In view of the above situation, the present invention easily and easily removes the adverse effect of bird's beak of the field oxide film, prevents a rapid rise in V _th , and electrically connects with the field region defined by the Locos method. It is an object of the present invention to provide a semiconductor device and a method for manufacturing the same that can reduce the step difference when the extraction electrode is taken from the source / drain region without making the connection again.

[0023]

According to a method of manufacturing a semiconductor device of the present invention, a silicon oxide film and a silicon nitride film are laminated on a surface of a semiconductor substrate, and the silicon nitride film is patterned to form a silicon nitride film. Impurity implantation is performed as a mask to form a channel cut in this semiconductor substrate,
A step of forming a field oxide film by performing selective oxidation using this silicon nitride film as a mask to define a channel region of a transistor, and after removing the silicon nitride film and the silicon oxide film, patterning the field oxide film And a step of forming a transistor having a defined channel width.

[0024]

That is, in the present invention, since the transistor having the channel region defined by the field oxide film and the transistor having the channel width defined by patterning the field oxide film are provided, the advantages of each transistor are utilized and the drawbacks are brought about. By removing it, it becomes possible to manufacture a semiconductor device having high quality and stable characteristics.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 2 are views showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention in the order of steps, FIG.
FIG. 4 is a cross-sectional view in the longitudinal direction of the channel showing the method for manufacturing the semiconductor device of the second embodiment according to the present invention in the order of steps, and FIG. FIGS. 5 to 6 are views showing a method of manufacturing a semiconductor device according to a fourth embodiment of the present invention in the order of steps.

In order to manufacture the semiconductor device of the first embodiment according to the present invention, first, as shown in FIG.
A silicon oxide film 2 and a silicon nitride film are formed by laminating on the surface of, and the silicon nitride film is patterned to form a silicon nitride film 3.

Next, as shown in FIG. 1B, a channel cut 4 is formed by implanting impurities using the silicon nitride film 3 as a mask, and the silicon nitride film 3 is used as a mask to selectively oxidize the field. The oxide film 5 is formed.

Then, the silicon nitride film 3 and the silicon oxide film 2 are removed to define a field region, and then a resist film 6 is formed on the entire surface to form a gate electrode of a cross section in the channel width direction as shown in FIG. 1 (c). Dimensional accuracy is obtained by patterning the resist film 6 on the surface of the channel cut 4 in the width and channel longitudinal section and etching and removing the field oxide film 5 in the channel width direction section and the field oxide film 5 in the channel longitudinal section. Defines a channel region of a transistor that requires a high channel width of

After that, as shown in FIG. 2A, a conductive layer to be a gate electrode is formed in the field region through the gate oxide film 7 and patterned to form a gate electrode 8, which is used as a mask. Then, impurities are injected into the semiconductor substrate 1 to form the source 9 and the drain 10.

In order to manufacture the semiconductor device of the second embodiment according to the present invention, first, as shown in FIG.
A resist film is formed on the surface of the field oxide film 25 provided on the surface of the
26 is formed and patterned, the region defined by etching the field oxide film 25 using the resist film 26 as a mask is provided adjacent to the region defined by the Locos method, and the resist film 26 is removed. As shown in FIG. 3 (b), a gate electrode 28 is formed in each region through a gate oxide film 27, and the gate electrode 28 is used as a mask to inject impurities into the semiconductor substrate 21 and patterned to define it. The drain 30 of the region and the source 29 of the region defined by the Locos method are formed to be connected.

The transistor thus formed does not need to be electrically connected by the extraction electrode 122 using the contact hole provided in the insulating film 121 as in the conventional semiconductor device of the third example shown in FIG.

In order to manufacture the semiconductor device of the third embodiment according to the present invention, first, as shown in FIG. 4 (a), the same steps as those of the manufacturing process of the semiconductor device of the second embodiment shown in FIG. The film 46 is removed, then the gate oxide film 47 is formed in all the field regions as shown in FIG. 4B, and the gate electrode 48 is formed in the field region formed by patterning the field oxide film 45. An insulating film 51 is formed on the entire surface, a contact hole 51a is formed in a region defined by the Locos method, and a lead electrode 52 is formed in this contact hole 51a.

The extraction electrode 52 of the transistor thus formed is formed by etching the field oxide film 135 as in the conventional semiconductor device of the fourth example shown in FIG. It is possible to form the electrode shallower than the extraction electrode 142 formed by using the contact hole provided in.

In order to manufacture the semiconductor device of the fourth embodiment according to the present invention, first, as shown in FIG.
A silicon oxide film 62 and a silicon nitride film are laminated and formed on the surface of, and the silicon nitride film is patterned to form a silicon nitride film 63.

Next, as shown in FIG. 5B, a channel cut 64 is formed by implanting impurities with the silicon nitride film 63 as a mask, and the silicon nitride film 63 is used as a mask to selectively oxidize the field. An oxide film 65 is formed.

Next, the silicon nitride film 63 and the silicon oxide film
After removing the 62 to define the field region, a resist film 66 is formed on the entire surface, and as shown in FIG. 5C, the width of the gate electrode in the channel width direction section and the surface of the channel cut 64 in the channel longitudinal direction section. By patterning the resist film 66 of and the field oxide film 65 in the cross section in the channel width direction and the field oxide film 65 in the cross section in the longitudinal direction of the channel are removed by etching, the channel region of the transistor requiring a channel width with high dimensional accuracy To define

After that, as shown in FIG. 6A, a conductive layer to be a gate electrode is formed in the field region through a gate oxide film 67, and patterned to form a gate electrode 68. The gate electrode 68 is used as a mask. Then, impurities are injected into the semiconductor substrate 61 to form the source 69 and the drain 70.

[0038]

As is apparent from the above description, according to the present invention, it is possible to reduce variations in the channel width and to obtain stable transistor characteristics by changing the process in an extremely simple manner. It is possible to provide a semiconductor device which has advantages, and can be expected to have a remarkable economic effect and an effect of improving reliability, and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention in the order of steps (1),

FIG. 2 is a diagram showing the method of manufacturing the semiconductor device of the first embodiment according to the present invention in the order of steps (2),

FIG. 3 is a longitudinal cross-sectional view of a channel showing a method of manufacturing a semiconductor device according to a second embodiment of the present invention in process order.

FIG. 4 is a longitudinal cross-sectional view of a channel showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention in process order.

FIG. 5 is a diagram showing the method of manufacturing a semiconductor device according to the fourth embodiment of the present invention in the order of steps (1),

FIG. 6 is a diagram showing a method of manufacturing a semiconductor device according to a fourth embodiment of the present invention in the order of steps (2),

FIG. 7 is a diagram showing a method of manufacturing a semiconductor device according to a conventional first example in the order of steps;

FIG. 8 is a diagram showing a method of manufacturing a semiconductor device of a second conventional example in the order of steps,

FIG. 9 is a side sectional view showing a conventional semiconductor device of a third example;

FIG. 10 is a side sectional view showing a conventional semiconductor device of a fourth example;

[Explanation of symbols]

1 is a semiconductor substrate, 2 is a silicon oxide film, 3 is a silicon nitride film, 4 is a channel cut, 5 is a field oxide film, 6
Is a resist film, 7 is a gate oxide film, 8 is a gate electrode, 9
Is the source, 10 is the drain,

Claims (4)

[Claims] 1. A silicon oxide film on the surface of a semiconductor substrate (1).
A channel cut (4) is formed in the semiconductor substrate (1) by stacking (2) and a silicon nitride film, and using the silicon nitride film (3) obtained by patterning the silicon nitride film as a mask to implant impurities. Then, selective oxidation is performed using the silicon nitride film (3) as a mask to form a field oxide film (5) to define a channel region of a transistor, and the silicon nitride film (3) and the silicon oxide film ( And (2) are removed, and then the field oxide film (5) is patterned to form a transistor having a defined channel width. 2. A method of manufacturing a semiconductor device, comprising the step of forming a transistor having a channel width defined by patterning a field oxide film so as to overlap a field region defined by the Locos method. 3. A step of forming a field region defined by the Locos method adjacent to a transistor having a channel width defined by patterning a field oxide film, and forming an extraction electrode in the field region defined by the Locos method. A method of manufacturing a semiconductor device, comprising: 4. A resist film (66) is formed in a field region defined by the Locos method, and the resist film (66) is patterned to form an opening having a channel width. Field oxide film using 66) as a mask
A step of patterning (65), and forming a gate electrode (68) through the gate oxide film (67) in the channel length direction of the field region defined by the Rocos method,
Source (69) and drain using the gate electrode (68) as a mask
A method of manufacturing a semiconductor device, comprising the step of forming (70).