JPH01170021A - Semiconductor substrate - Google Patents

Abstract

PURPOSE:To make it possible to reliably conduct an autoaligning operation on a semiconductor substrate and a mask by a method wherein a conductive film is interposed between a field insulating film and an interlayer insulating film and/or a protective film, and the edge part of the pattern for alignment is steeply formed. CONSTITUTION:An alignment pattern 5 is composed of the stepping formed by the field insulating film 2 on the main surface of a semiconductor substrate 1, the conductive film 6 located above the film 2, an interlayer insulating film 4 consisting of a phosphorus glass film and the like, for example, and the protective film 22 consisting of the nitrogen film and the like formed by plasma CVD, for example, and the stepping on its edge part is steeply formed. Accordingly, when a laser beam or a single color beam is projected on the alignment pattern 5, the scattering light which is required for the detection of pattern is increased, and as a result, the detection of position of the semiconductor substrate 1 can be conducted reliably. As a result, the automatic alignment of the semiconductor substrate 1 and a photomask can be conducted reliably.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a semiconductor substrate (semiconductor wafer) for a semiconductor integrated circuit device, and in particular to automatic alignment of a semiconductor substrate and a photomask in the manufacturing process of a semiconductor integrated circuit device. The present invention relates to an alignment pattern to be used and a technique that is effective when applied to the formation technique thereof.

[Prior art]

In the manufacturing process of semiconductor integrated circuit devices, a photosensitive photoresist is applied onto a semiconductor substrate (semiconductor wafer) and exposed to light.
After development, using this as a mask, the process of selectively etching the semiconductor substrate and the photoresist process of selectively growing an oxide film are repeated. To selectively expose the photoresist to light in the photoresist process.

A photomask with a pre-designed pattern is used, but due to the manufacturing process, there are multiple photomasks, and all photomasks must be aligned at a certain position on the semiconductor substrate, and this must be done between the photomask and the semiconductor. This is called substrate alignment.

Currently, a predetermined alignment pattern is selectively formed on a semiconductor substrate using a step process such as an oxide film, which is then irradiated with a detection laser or monochromatic light to generate scattering from the edges of the alignment pattern. By capturing the light, the position of the semiconductor substrate is detected. Similarly, the Cr pattern provided on the photomask is detected, and the stage on which the semiconductor substrate of the detection system is mounted is moved to automatically align the photomask and the semiconductor substrate. Auto-alignment that performs this has become common. Conventionally, the alignment pattern on the semiconductor substrate side used for auto-alignment is formed when forming a field insulating film on the semiconductor substrate without forming the field insulating film on the alignment pattern, or MI on field insulating film
After forming a material for the gate electrode of the SFET, a portion of this material that will become the alignment pattern is formed by etching. That is, it is formed in one of the steps of forming the field insulating film or the step of forming the material for the gate electrode.

[Problem that the invention seeks to solve]

The inventor of the present invention discovered the first problem as a result of studying the alignment pattern formed on the semiconductor substrate.

As mentioned above, in the conventional technology, the alignment pattern on the semiconductor substrate side was formed by a single step during the manufacturing process of the field insulating film or gate electrode material. ) etc. In the process of performing auto-alignment after forming a glabellar insulating film or a protective film, the steps at the edges of the alignment pattern are made gentler by a ring glass or the like. For this reason, there was a problem in that a signal of scattered light in an amount necessary for pattern detection could not be obtained, and automatic alignment could not be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique that can reliably perform auto-alignment between a semiconductor substrate and a photomask.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

A brief overview of typical inventions disclosed in this application is as follows.

That is, it has an alignment pattern formed by forming a step by forming a field insulating film surrounding a predetermined region of the main surface of the semiconductor substrate, and forming an interlayer insulating film or an interlayer insulating film on top of the step. In the semiconductor substrate, a conductive film is interposed between the field insulating film and an interlayer insulating film or a protective film, so that the edge of the region serving as the alignment pattern is made steep.

[Effect]

According to the above-described means, since the edge portion of the alignment pattern has a steep step, when the alignment pattern is irradiated with a laser or monochromatic light, the scattered light, which is a signal necessary for pattern detection, increases. Therefore, the position of the semiconductor substrate can be detected reliably, and from this, the automatic alignment between the semiconductor substrate and the photomask can be performed reliably.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In addition, in all the episodes, the same reference numerals are given to the parts having the same functions, and the repeated explanation thereof will be omitted.

FIG. 1 is a plan view of an example of an alignment pattern for detecting a predetermined position on a semiconductor substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the alignment pattern of FIG. 1 taken along the line AA.

1 and 2, an alignment pattern 5 according to an embodiment of the present invention includes a field insulating film 2 on the main surface of a p-type semiconductor substrate 1, and a conductive film 6 and 1 thereon, such as phosphor glass ( It consists of a step formed by an interlayer insulating film 14 made of p s a) film or the like. Alternatively, the alignment pattern 5 includes a field insulating film 2, a conductive film 6 thereon, and a glabellar insulating film 1 made of, for example, a ring glass film.
4 and a protective film 22 made of, for example, a nitride film formed by plasma CVD. By interposing the conductive film 6 between the field insulating film 2 and the interlayer insulating film 14, the phosphorus glass film used as the interlayer insulating film can soften the level difference on the semiconductor substrate 1. Even in this case, the edges of the alignment pattern 5 formed by the field insulating film 2, the conductive film 6 thereon, and the interlayer insulating film 14 are steep. Similarly, the interlayer insulating film 14 and the protective film 22
each of them.

Even if the level difference on the semiconductor substrate 1 can be made smooth, it is possible to make the step formed by the field insulating film 2, the conductive film 6 thereon, the interlayer insulating film 14, and the protective film 22. The edge of the alignment pattern 5 consisting of steps is steep. 3 is a p-type channel stopper region, 7 is M
A thin silicon oxide film formed when forming the gate insulating film of an ISFET.

Reference numeral 13 denotes an n.type semiconductor region formed when forming the source and drain of the n-channel MISFET.

As shown in FIG. 1, the alignment pattern 5 is
It is formed in a predetermined region 4 of a semiconductor substrate (wafer) 1. Further, the alignment pattern 5 is formed on the semiconductor substrate 1.
so that the photomask can be aligned vertically and horizontally.
The layout is inclined at 45 degrees with respect to the scanning line when laser or monochromatic light scans the semiconductor substrate 1.

Next, the operation of the alignment pattern 5 according to the embodiment of the present invention will be explained.

FIG. 3 is a diagram for explaining the effect when the alignment pattern 5 is composed of a step formed by the field insulating film 2, the conductive film 6 thereon, and the first interlayer insulating film 14. FIG. 4 is a diagram for explaining the effect when the alignment pattern 5 is composed of a step formed by the field insulating film 2, the conductive film 6 thereon, the interlayer insulating film 14, and the protective film 22. It is.

First, with reference to FIG. 3, the function of the alignment pattern 5 composed of the field insulating film 2, the conductive film 6 thereon, and the interlayer insulating film 14 will be explained.

As shown in FIG. 3, after the alignment pattern 5 is formed by the field insulating film 2, the conductive film 6 thereon, and the glabellar insulating film 14, the glabellar insulating film 14 is formed on the glabellar insulating film 14. A resist film 15 is coated on the semiconductor substrate 14 to serve as an etching mask when forming connection holes.
The resist film 15 is cured by baking. Next, the semiconductor substrate 1 is placed on an X-Y stage, and then a laser or monochromatic light 16 is applied to detect the position of the semiconductor substrate 1 on the X-Y stage. , along the scanning line shown in FIG. When the edge of the alignment pattern 5 is irradiated with the laser or monochromatic light 16, since the edge of the alignment pattern 5 is steep, a lot of scattered light 17, which becomes a signal for detecting the position of the semiconductor substrate 1, is emitted. arise. Therefore, the position of the semiconductor substrate 1 on the XY stage can be detected reliably. After detecting the position of the semiconductor substrate 1, the position of the photomask is detected. Similar to the position detection of the semiconductor substrate 1, this photomask position detection is performed using chromium (Cr) provided at a predetermined position of the photomask. ), and the X-Y stage on which the semiconductor substrate 1 is mounted is moved under the photomask so that the alignment pattern 5 of the semiconductor substrate 1 overlaps the alignment pattern of the photomask. At this time, in the semiconductor substrate 1 of the present invention, as described above, there is a lot of scattered light 17 as a signal emitted from the alignment pattern 5, and the semiconductor substrate 1 Since the position of the semiconductor substrate 1 and the photomask can be reliably detected, automatic alignment of the semiconductor substrate 1 and the photomask can be performed reliably.

Next, using FIG. 4, form the field insulating film 2.

The action of the alignment pattern 5, which is made up of a step formed by the conductive film 6, the glabella insulating film 14, and the protective film 22 thereon, will be explained.

As shown in FIG. 4, a resist film 23 is formed on the protective film 22 to serve as an etching mask when removing the portion of the protective film 22 above the bonding pad. After this, same as above.

A laser or monochromatic light 24 for detecting the position of the semiconductor substrate 1 on the XY stage is scanned along the scanning line shown in FIG. When the edge of the alignment pattern 5 is irradiated with the laser or monochromatic light 16, since the edge of the alignment pattern 5 is steep, a lot of scattered light 25 is generated which serves as a signal for detecting the position of the semiconductor substrate 1. . Therefore, the position of the semiconductor substrate 1 on the XY stage can be detected reliably. After detecting the position of the semiconductor substrate 1, the position of the photomask is detected, and then the semiconductor substrate 1 is moved under the photomask to perform auto-alignment of the photomask and the semiconductor substrate 1. In the semiconductor substrate 1, since the position of the semiconductor substrate 1 is reliably detected as described above, the auto-alignment of the semiconductor substrate 1 and the photomask can be performed reliably.

Next, a method of forming the conductive film 6 for making the edge of the alignment pattern 5 steep will be described.

5 to 11 show the alignment pattern 5.
11 is a diagram for explaining a method of forming a conductive film 6 to make the edge of the M
A cross-sectional view of the portion taken along line A-A in FIG. 1 in the ISFET manufacturing process, and region B in FIGS. 5 to 11 are as follows:
It is a sectional view in a manufacturing process of MISFET.

The method for forming the conductive film 6 for making the edges of the alignment pattern 5 steep in one embodiment of the present invention is as follows: First, as shown in areas A and B in FIG. Field insulating film 2TP type channel stopper 3. Each thin silicon oxide film (gate insulating film) 7 is formed.

Next, as shown in regions A and B in FIG. 6, a conductive film 6 made of a polycrystalline silicon film or the like is formed on each of the silicon oxide films 7, which are 2° thinner than the field insulating film, by, for example, CVD.

Next, as shown in areas A and B in FIG. 7, a resist film 8 is applied on the conductive film 6, and then baked and cured.

Next, as shown in areas A and B in FIG. 8, after a photomask 11 is aligned at a predetermined position on the semiconductor substrate 1, the resist film 8 is exposed to ultraviolet light 12, for example. 8A
is the exposed portion of the resist film 8.

After removing the photomask 11 and removing the exposed portion 8A of the resist film 8, areas A and B in FIG.
As shown in FIG. 3, the exposed portion of the conductive film 6 from the resist film 8 is removed by etching, and a conductive film 6 used for forming the alignment pattern 5 is formed in the region A.
A gate electrode 6A of the MISFET is formed in region B.

Next, as shown in regions A and B in FIG. 10, the resist film 8 on the conductive film 6 and the gate electrode 6A is removed.

Next, as shown in region B of FIG. 11, n.type semiconductor regions 13 that will become the source and drain of the n-channel MISFET are formed by ion implantation.

At this time, the n.
A type semiconductor region 13 is formed.

In this way, the conductive film 6 for configuring the alignment pattern 5 in one embodiment of the present invention is a common MISFET.
can be formed simultaneously using the process of forming the gate electrode 6A.

As described above, according to this embodiment, the step is formed by forming the field insulating film 2 surrounding a predetermined region of the main surface of the semiconductor substrate 1.

In a semiconductor substrate 1 having an alignment pattern 5 formed by forming an interlayer insulating film 14 or a protective film 22 thereon, there is a gap between the field insulating film 2 and the interlayer insulating film 14 or a protective film 22. By interposing the conductive film 6 and making the edge of the region that will become the alignment pattern 5 steep, when the alignment pattern 5 is irradiated with a laser or monochromatic light, scattering, which is a signal necessary for pattern detection, is generated. Since the light increases, the position of the semiconductor substrate 1 can be detected reliably, and from this, the automatic alignment between the semiconductor substrate 1 and the photomask can be reliably performed.

The present invention has been specifically described above based on examples, but 1.
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

Because the edges of the alignment pattern have steep steps, when the alignment pattern is irradiated with a laser or monochromatic light, scattered light, which is a signal necessary for pattern detection, increases, so the position of the semiconductor substrate Detection becomes easy, and from this, automatic alignment between the semiconductor substrate and the photomask can be performed easily and reliably.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an example of an alignment pattern for detecting a predetermined position on a semiconductor substrate according to an embodiment of the present invention. FIG. A cross-sectional view of. FIG. 3 is a diagram for explaining the effect when the alignment pattern 5 is composed of a step formed by the field insulating film 2, the conductive film 6 thereon, and the glabellar insulating film 14. FIG. 4 is a diagram for explaining the effect when the alignment pattern 5 is composed of a step formed by a field insulating film 2, a conductive film 6 thereon, an interlayer insulating film 14, and a protective film 22. . 5 to 11 show the alignment pattern 5.
FIG. 6 is a diagram for explaining a method of forming a conductive film 6 to make the edges of the conductive film steep. In the figure, 2... Field insulating film, 5... Alignment pattern, 6... Conductive film, 14... Interlayer insulating film, 22... Protective film, 9, 16, 24... Laser Or monochromatic light, 10°1? , 25...This is scattered light. Figure 1 Taku 2 causes Figure 3 Figure 4

Claims (1)

[Claims] 1. A step formed by forming a field insulating film surrounding a predetermined region of the main surface of a semiconductor substrate, and forming an interlayer insulating film or a protective film thereon. In the semiconductor substrate having an alignment pattern, a conductive film is interposed between the field insulating film and an interlayer insulating film or a protective film, so that the edge of the region that becomes the alignment pattern is made steep. Semiconductor substrate. 2. The semiconductor substrate according to claim 1, wherein the alignment pattern is used for detecting the position of the semiconductor substrate when performing automatic alignment of the semiconductor substrate and a photomask. 3. The semiconductor substrate according to claim 1, wherein the alignment pattern is irradiated with a laser or monochromatic light for auto-aligning the semiconductor substrate and a photomask. 4. The conductor layer provided on the field insulating film is
2. The semiconductor substrate according to claim 1, wherein the semiconductor substrate is formed in the same process as a gate electrode of a MISFET. 5. The method according to claim 1, wherein a phosphosilicate glass (PSG) film is provided on the conductor layer on the field insulating film to reduce steep steps on the semiconductor wafer. semiconductor substrate.