JPH05283334A - Method for planarizing metallic wiring layer and planarizing - Google Patents

Abstract

PURPOSE:To provide a method for planarizing a metallic wiring layer by optical alignment for aligning inter layer patterns can be performed. CONSTITUTION:After forming a metallic wiring film 14 on a semiconductor wafer, heat rays are applied. Wiring materials are heated and fluidized. As a result, the metallic wiring film is planarized. As a result, the metallic wiring film is planarized. At this time, heat rays are applied, except the surface of rough pattern regions 5 for alignment marks which have been previously made on the wafer, and the metallic wiring film 14 is planarized except the rough pattern region 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for flattening a wiring layer when forming a multi-layered metal wiring on a semiconductor wafer, and particularly to irradiating a heat ray such as a laser beam after forming the metal wiring layer. And apparatus for flattening.

[0002]

2. Description of the Related Art When wiring connection holes (contact holes, via holes) become smaller due to miniaturization of elements of a semiconductor device, metal wiring is formed on an insulating film 12 on a semiconductor substrate 11, as shown in FIG. When forming the layer 14, the insulating film 1
The coverage of the wiring layer 14 with respect to the connection hole 13 opened in 2 is deteriorated, and disconnection of the wiring layer 14 occurs in the connection hole 13. In order to avoid this, the wiring layer 14 is formed on the substrate 11.
The wiring layer 14 is flattened as shown in FIG.

As a technique for flattening the wiring layer 14 as described above, (a) a method of applying a bias voltage to a semiconductor substrate at the time of forming a wiring film (bias / sputtering method, bias ECR, etc.), (b) wiring There are a method of fluidizing the wiring material by heating at the time of forming the film, (c) a method of heating the fluidizing the wiring material by irradiating the entire surface of the wiring film with, for example, a laser beam after forming the wiring film. is there.

On the other hand, at the time of forming a pattern of each layer on a wafer in manufacturing a semiconductor device, it is necessary to perform alignment for aligning patterns between layers in a photolithography process. This alignment is usually performed using an optical recognition method. That is, when the desired pattern is formed on the wafer, as shown in FIG. 7, the concave-convex pattern 5a for the alignment mark, which is previously formed of the insulating layer, and the desired pattern are formed on the substrate 11. The alignment pattern 84 on the glass mask 83 is aligned with the optical system 85.

The concavo-convex pattern 5a on the substrate is usually detected by scanning the He--Ne laser beam 16 or image recognition, as shown in FIG. At this time, the accuracy of pattern recognition depends on the contrast strength and sharpness generated by the scattered light 16a from the edge of the uneven pattern 5a on the substrate 11.

Now, as shown in FIG. 9, let us consider a case where the concavo-convex pattern 5a for the alignment mark on the substrate is detected in the photolithography process after the metal wiring film 14 is formed on the substrate 11. In this case, normally, the alignment light 16 transmitted through the photoresist 15 is reflected on the surface of the metal wiring film 14, but in the coverage portion of the wiring film 14, the direction of the reflected light deviates from the optical axis of the incident light. Therefore, contrast occurs.

However, as shown in FIG. 10, the concave-convex pattern 5a for the alignment mark is formed in the step after the flattening as described above is performed on the metal wiring film 14 on the substrate 11.
In the case of detecting, the alignment light 16 that has passed through the photoresist 15 does not change in the light reflected on the surface of the metal wiring film 14 and contrast does not occur, so that the alignment as described above becomes impossible. Become.

[0008]

As described above, the conventional method for flattening a metal wiring layer has a problem that optical alignment for aligning interlayer patterns becomes impossible after the flattening of the metal wiring layer. It was

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for planarizing a metal wiring layer which enables optical alignment for aligning interlayer patterns.

[0010]

According to the present invention, when a metal wiring film is formed on a semiconductor wafer, the wiring material is irradiated with heat rays to heat and fluidize the wiring material for planarization. It is characterized in that the metal wiring film is flattened by irradiating with a heat ray while avoiding the alignment mark concavo-convex pattern region previously formed thereon, and excluding the concavo-convex pattern region.

[0011]

According to the flattening method of the present invention, when a metal wiring film is formed on a semiconductor wafer and then flattened by irradiating with a heat ray, the area of the concave-convex pattern for the alignment mark is avoided so as to avoid the heat-heat ray. The irradiation area is limited.

As a result, when the concave-convex pattern for the alignment mark is detected in the step after the flattening of the metal wiring layer, the alignment light is reflected on the surface of the metal wiring layer and reflected at the coverage portion of the metal wiring layer. The direction deviates from the optical axis of the incident light. Therefore, the contrast of the reflected light and the received light signal of the pattern recognition device is generated, and the concave-convex pattern for the alignment mark can be detected. Further, according to the flattening apparatus of the present invention, the flattening method of the present invention can be easily realized.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the upper surface of a semiconductor wafer 1 to which the method for planarizing a metal wiring layer of the present invention is applied. The wafer 1 has a plurality of chip areas 2 ... And 3 in the drawing shows an area that can be exposed by one pattern exposure operation.

FIG. 2 shows the pattern exposure range 3 taken out and enlarged. 4 is a region between the chip regions 2 ..., and the inter-chip region 4 ... Is a region to be diced when divided into individual chip regions 2 ... After the wafer process is completed.

A concave-convex pattern area 5 for an alignment mark is formed at a specific position within the pattern exposure area 4. For example, in the inter-chip region 4, ... One concavo-convex pattern region 5 is formed in each of two directions (X direction and Y direction) orthogonal to each other. For example, as shown in FIG. 3, the uneven pattern region 5 has an uneven pattern 5a in which an insulating layer is intermittently formed on the wafer 1 in the X direction or the Y direction. The shape of the uneven pattern 5a varies depending on the exposure apparatus.

An example of a method of forming a metal wiring layer on the wafer 1 and planarizing the metal wiring layer will be described with reference to FIGS. 6 and 9. On the semiconductor substrate 11, a transistor,
Elements such as resistors and capacitors are formed. After that, a hole 13 for taking out an electrode is formed in the interlayer insulating film 12 on the substrate by using ordinary photolithography and RIE (reactive ion etching). At the same time, the concave-convex pattern 5a for the alignment mark is formed at a specific position on the substrate 11. In this uneven pattern 5a, the thickness of the protrusion (insulating layer) was 1.0 micron and the width was 2.0 microns. next,
As the first-layer metal wiring film 14, for example, an aluminum-based alloy film (for example, an aluminum film containing 1% of silicon) is formed with a thickness of 1.0 micron on the entire surface of the substrate by a normal sputtering method.

After that, in order to flatten the metal wiring film 14, the metal wiring film 14 is irradiated with a laser beam while scanning, so that the wiring material is heated to a molten state (fluidized). To flatten. At this time, the laser light beam is selectively irradiated while avoiding the above-mentioned concave / convex pattern area 5 for the alignment mark formed on the substrate 11, and the metal wiring film 14 is formed on the concave / convex pattern 5a for the alignment mark. The surface is flattened leaving the uneven pattern. As the laser light, for example, A
Using rF excimer laser light, pulse energy density is 8.5 J / cm ^2. Set to.

According to the flattening method of the above-described embodiment, when the metal wiring film 14 is formed on the semiconductor wafer and then flattened by irradiating the laser light beam, the uneven pattern areas 5 for the alignment marks are formed. Since the irradiation area is limited so as to avoid the above, the uneven pattern of the metal wiring film 14 remains on the uneven pattern 5a for the alignment mark as shown in FIG.

As a result, when the concave / convex pattern 5a for the alignment mark is detected in the photolithography process after the flattening of the metal wiring layer, as shown in FIG. 9, the alignment light 16 transmitted through the photoresist 15 is detected. The light is reflected on the surface of the metal wiring film 14, and the direction of the reflected light deviates from the optical axis of the incident light at the coverage portion of the metal wiring film 14.

Therefore, the contrast of the reflected light and the received light signal of the pattern recognition device is generated, and the concavo-convex pattern 5a for the alignment mark can be detected. in this case,
The accuracy of pattern recognition depends on the intensity and sharpness of the contrast generated by the scattered light from the coverage portion of the metal wiring film 14, but according to the above-described embodiment, sufficiently good recognition accuracy can be obtained.

When ArF excimer laser light is used as the laser light, since the wavelength (193 nm) is short, only the surface of the metal wiring layer can be heated and the flattening can be performed well. Further, not only the laser light beam but also other heat rays such as electron rays may be irradiated. Moreover, as the metal wiring film, for example, an aluminum film, copper, or a copper-based alloy film may be used.

FIG. 4 schematically shows the construction of an embodiment of a flattening apparatus for realizing the above-mentioned flattening method. Here, 51 is a laser light source, 52 is a laser light, 53 is a reflection mirror for reflecting the laser light sent from the laser light source, and 54 is for irradiating the wafer 1 with the laser light reflected from the reflection mirror. Optical lens system, 55 is an XY stage for mounting the wafer 1 and driving it in the X and Y directions, and 56 is an XY stage for moving the XY stage in the XY direction based on the laser light irradiation area setting signal input. An XY stage drive system for driving, 57 is a shutter for laser beam intermittent control arranged in front of the laser light source 51 (laser beam sending direction), and 58 is a stage given from the XY stage drive system. It is a shutter drive system that drives the shutter based on the position information to interrupt the laser light.

If the above flattening device is used, the wafer 1
In order to planarize the metal wiring film formed above, by irradiating the metal wiring film while scanning the laser light beam, it is possible to heat the wiring material and bring it into a molten state so as to be planarized. Become. At this time, the shutter 57 is intermittently controlled so as to selectively irradiate the laser light beam while avoiding the region of the concave / convex pattern for the alignment mark which is previously formed on the wafer 1, and the concave / convex pattern for the alignment mark is formed on the concave / convex pattern. It becomes possible to flatten the metal wiring film leaving the concavo-convex pattern. That is, according to the flattening apparatus for a metal wiring layer of the above-described embodiment, the above-described flattening method for a metal wiring layer can be easily realized.

The flattening device for the metal wiring layer of the present invention is not limited to the above-mentioned embodiment, but an excimer laser light source is used as the laser light source 51, and based on stage position information given from the XY stage drive system 56. The shutter 57 and the shutter drive system 58 can be omitted by directly controlling the excimer laser light source.

Further, the reflecting mirror 53 or the optical lens system 54 is input based on the laser beam irradiation area setting signal input.
If the laser light irradiation position is controlled by controlling, the XY stage 55 and the XY stage drive system 56 can be omitted.

It is also possible to always generate an electron beam having thermal energy capable of melting the metal wiring layer instead of the laser beam and intermittently control this electron beam by a beam shutter.

[0028]

As described above, according to the present invention, a method of flattening a metal wiring layer that enables optical alignment for aligning interlayer patterns, and a flattening of a metal wiring layer that can easily realize the method. A device can be provided.

[Brief description of drawings]

FIG. 1 is a plan view showing an upper surface of a semiconductor wafer to which a planarizing method of the present invention is applied.

FIG. 2 is a plan view showing a pattern exposure range in FIG. 1 in an enlarged manner.

3 is a plan view showing an example of a concavo-convex pattern in a concavo-convex pattern area for alignment marks in FIG.

FIG. 4 is a diagram schematically showing a configuration of an example of a flattening apparatus of the present invention.

FIG. 5 is a cross-sectional view showing a state in which the coverage of the wiring layer with respect to the connection hole is poor at the time of manufacturing the semiconductor device.

FIG. 6 is a cross-sectional view showing a state in which a wiring layer is flattened in manufacturing a semiconductor device.

FIG. 7 is a diagram schematically showing how optical alignment is performed between a concave-convex pattern for an alignment mark on a wafer and an alignment pattern on a glass mask when manufacturing a semiconductor device.

FIG. 8 is a diagram showing a path of alignment reflected light from an uneven pattern for alignment marks during alignment in manufacturing a semiconductor device.

FIG. 9 is a diagram showing a path of alignment alignment reflected light during alignment in a photolithography process after forming a metal wiring film on a wafer in manufacturing a semiconductor device.

FIG. 10 is a diagram showing a path of alignment reflected light at the time of alignment in a photolithography process after a metal wiring film is formed on a wafer and then planarized in manufacturing a semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor wafer, 2 ... Chip area | region, 3 ... Pattern exposure range, 4 ... Inter-chip area | region, 5 ... Alignment mark uneven | corrugated pattern area, 5a ... Alignment mark uneven | corrugated pattern, 11 ... Semiconductor substrate, 12 ... Insulating film , 13 ...
Connection holes, 14 ... Metal wiring film, 15 ... Photoresist, 1
6 ... Alignment light, 51 ... Laser light source, 52 ... Laser light, 53 ... Reflecting mirror, 54 ... Optical lens system, 5
5 ... XY stage, 56 ... XY stage drive system, 5
7 ... Shutter, 58 ... Shutter drive system.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 7735-4M H01L 21/88 K 7735-4M N

Claims (7)

[Claims] 1. An alignment preformed on the wafer when a metal wiring film is formed on a semiconductor wafer and the wiring material is flattened by heating and fluidizing the wiring material by irradiating it with a heat ray. A method of flattening a metal wiring layer, which comprises irradiating a heat ray while avoiding the concave-convex pattern area for marks to flatten the metal wiring film except on the concave-convex pattern area. 2. The method of planarizing a metal wiring layer according to claim 1, wherein the metal wiring film is an aluminum film or an aluminum alloy film. 3. The method of planarizing a metal wiring layer according to claim 1, wherein the heat ray is a laser light beam. 4. The method for planarizing a metal wiring layer according to claim 3, wherein the laser light is an excimer laser light. 5. A flattening apparatus for flattening a metal wiring film formed on a semiconductor wafer by heating a wiring material by heating while irradiating the metal wiring film on a semiconductor wafer while heating the wiring material into a molten state. A flattening device for a metal wiring layer, comprising: a selective irradiation means for irradiating the heat ray while avoiding the alignment mark concave-convex pattern area formed in advance on the wafer when the heat ray is irradiated. 6. The flattening device for a metal wiring layer according to claim 5, wherein the heat ray is a laser light beam, and a reflecting mirror arranged in an irradiation path of the laser light for scanning the laser light beam. Alternatively, a flattening device for a metal wiring layer, which has means for controlling an optical lens system. 7. The flattening apparatus for a metal wiring layer according to claim 5, wherein the heat ray is an excimer laser light beam, and the selective irradiation means intermittently controls the light source of the excimer laser light. A flattening device for a metal wiring layer.