JPH0316130A - Formation of electrode wiring by using laser flow technique - Google Patents

Abstract

PURPOSE:To restrain an element including an Al wiring layer from being damaged by a method wherein an Al alloy film is formed on a contact hole and on an intermediate insulating film and a light antireflection film is formed on the Al alloy film. CONSTITUTION:Contact holes 16 are made in source and drain diffusion layers 14 by using an RIE method. A high-melting metal such as a Ta-Si film 17 and an Al-Si film 18 as barrier metals are formed one after another on the whole surface of an Si substrate 11 by using a sputtering method. In addition, a W (tungsten) film 19 as an antireflection film is formed on the Al-Si film 18. When the antireflection film 19 is applied to the Al alloy film in this manner, the light absorption efficiency of the Al alloy film is increased. Consequently, a beam size is expanded to be larger than a chip size, and a beam overlap part is set on a grid-line region. Thereby, a uniform beam intensity is obtained on an element formation region on an IC chip, and it is possible to restrain an element from being damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming electrode wiring, and particularly to a method for forming Al wiring using laser flow technology.

(Conventional technology) A conventional wiring method will be explained using FIGS. 4 and 5.

FIGS. 4(a) and 4(b) are process diagrams using the laser flow technique, and FIG. 5 is a beam pattern diagram in the laser flow process.

First, as shown in FIG. 4(.), a field oxide film 2 is formed on the non-active region of the St substrate 1 using the LOCOS method. A dart electrode 3 is formed on the active region of the Si substrate 1. Source and drain diffusion layers 4 are formed on the surface of the St substrate 1 on both sides of the r-} electrode 3. sauce·
A BPSG film 5 as an intermediate insulating film is deposited over the entire surface of the Si substrate 1 on which the drain diffusion layer is formed. BPSG film 5
Then, a contact hole 6 for connection with the source/drain diffusion layer 4 is opened using the RIE method. 1 of St is applied to the entire surface of the BPSG film in which the contact hole 6 is formed.
% of AA'-St film 7 and an amorphous Si film 8 as a light antireflection film are sequentially laminated using the snow-nine-vine method. It is difficult for the films 7 and 8 formed by sputtering to be stacked in the contact hole 6 (the film thickness becomes thinner).

Next, on the IC chip formed on the 81 substrate 1, wavelength 3
08 nm of XeCl excimerade.

Laser light irradiation is performed by scanning a beam of a predetermined diameter as shown in FIG. At this time, the beam is irradiated with 10 to 50% of the beam size superimposed on other beams.

As a result, as shown in FIG. 4(b), the Al-Si film 7
The contact hole 6 is backfilled by the metal flow effect, and the contact hole is filled with Al--Si. Thereafter, the Al--Si film 7 is converted to zetan to form an Al wiring layer over the contact hole 6. Note that during metal flow, the amorphous ST film 8 melts into the Al-Sig 7.

(Problem to be Solved by the Invention) In the case of laser beam irradiation as described above, it is necessary to overlap the laser beams, so the overlapping part of the beams receives more light energy than the non-overlapping part, so Al-S
If the grain size of the i-film 7 grows abnormally large, or worse, the AI-Si film 7 evaporates or peels off. As described above, there is a problem in that the elements formed within the IC chip are seriously damaged.

Furthermore, since the amorphous Si film 8 melts into the Al--St film 7, the wiring resistance of the A4 wiring 8 increases, and migration tends to occur due to an increase in Si nanoleaves. Therefore, there is a problem that the life of the wiring is significantly reduced.

An object of the present invention is to provide a method for forming electrode wiring that can suppress damage to elements within an IC chip due to overlapping laser beams.

Another object of the present invention is to provide a method for forming electrode wiring that can prevent deterioration in the quality of the wiring film due to the antireflection film.

(Means for Solving the Problems) After laminating an intermediate insulating film on a predetermined portion of a semiconductor wafer, forming a contact hole in the intermediate insulating film, and forming an HT alloy film on the contact hole and the intermediate insulating film. A step of depositing an anti-reflection film on the Al alloy film, a step of depositing an anti-reflection film on the Al alloy film, and a step of depositing an anti-reflection film on the entire surface of the semiconductor wafer, the beam size being larger than the chip size and the beam overlapping portion being on the grid line area of the semiconductor wafer. A step of irradiating the Al alloy film with a laser beam set to metal flow and backfilling the contact hole with the Al alloy film, and sequentially selectively etching the anti-reflection film and the Al alloy film. and forming an Al wiring layer having an anti-reflection film on its upper surface over the contact hole.

(Function) In the present invention, since the light antireflection film is deposited on the Al alloy film, the light absorption efficiency of the Al alloy film is increased. Therefore, the beam size is much larger than the chip size, and the beam overlapping portion is set on the grid line area.

Therefore, uniform beam intensity is obtained on the element formation surface on the IC chip, and element damage is suppressed. Furthermore, since the anti-reflection film and the Al alloy film do not react, the properties of the Al alloy film will not deteriorate, and the anti-reflection film will not react with the Al alloy film.
It becomes a protective film for the l wiring layer.

(Example) An example of the manufacturing method of the present invention will be described based on FIGS. 1 to 3 and FIG. 6.

Incidentally, FIG. 1 shows a manufacturing process diagram, FIG. 2 shows a beam nocturne diagram, and FIG. 3 shows a characteristic diagram of the thickness of the antireflection film and the light reflectance.

First, as shown in Figure 1 (.), a semiconductor wafer (Si
Field oxide film 12 is placed on the non-active area of substrate 1.
It is formed using the OCOS method. Further, a dart electrode 13 is formed in a predetermined part of the active region of the St substrate 1. Thereafter, source/drain diffusion layers 14 are formed on the surface of the Si substrate 11 on both sides of the gate electrode 13. After depositing a BPSG film 15 as an intermediate insulating film on the entire surface of the Si substrate 11, this BPSG film 15 is partially etched away and a contact hole 16 is opened on the source/drain diffusion layer 14 using the RIE method. . Next, a Ta-St film 17 with a thickness of IOOOX is applied as a barrier metal over the entire surface of the Si substrate 1.
etc., and 0.6 μm thick fi. The l-St film 18 is Adhesion is formed sequentially using the ivy method. Furthermore, a W (tungsten) film 19 as a light antireflection film is formed to a thickness of 300X on this l'-St film J8.

Next, the St wafer 31 that has been treated as described above is ripened by a laser beam.

FIG. 6 shows an apparatus for heating the St wafer 31 with a laser. A Si wafer is placed on a stage 33 of an XY table provided in a chamber 32 and heated with a heater 34 .

The temperature should be within the range of 300°C or above the recrystallization temperature of AI (150°C to 200°C, although it varies depending on the method of forming the Al-Si film 18) and does not affect the elements formed on Si Weno 31. Good condition. The inside of the chamber 31 is made into an inert gas atmosphere or the pressure is reduced to D10 Torr by a vacuum pump.

By doing so, the heated W film 19 can be prevented from being oxidized.

While the Si wafer 31 is heated, the surface of the Si wafer 3l is irradiated with a laser beam from the XeCl laser 35.

The laser beam has a frequency of 100 Hz, /? It oscillates with a pulse width of several 10 mBeC and a wavelength of 308 nm. The laser beam is reflected by a mirror 36 and passes through an optical system 37 to irradiate the surface of the Si wafer 31. The optical system 37 has a lens 38 and an aperture 39 having an opening similar to the shape of each IC chip.
The beam energy is 2.5~3. OJ/crn2
Adjust to. In addition, the intensity of the oscillated laser beam is determined by detecting the light that has slightly passed through the mirror 36 with the controller 40, and
Adjustment is made by controlling the l laser 35. To determine whether the laser beam is correctly irradiated onto the IC chip, the light emitted from the arclan F41 is split by a transparent plate 42 that slightly reflects the light, and the light is detected using a photodiode 43 and a camera 44, and then monitored. Photographed in 45.

This signal is also transmitted to the XY stage controller 46, and the XY stage 33 is moved to a required position by this control signal. These detected signals are also input to the host computer 47, which controls each of the controllers mentioned above, and also controls the optical system controller 48 to adjust the optical system 37.

When heating one IC chip on three Sify wafers with a laser beam, the following relationship is satisfied between the beam size AXB and the IC chip size aXb, as shown in FIG.

A = a + C X (0.6~0.8) X
:2 Akebono B=b+Cx(0.6~0.8)X2+l! l
I (where C is the grid line width) The beam overlap dimension of adjacent beams irradiated at this time is CX (0.2 to 08) IIm.

When the Stig is sufficiently small or when the laser beam has a sufficiently large output, the heat treatment is performed on two adjacent IC chips or four IC chips at a time. Beam size An X B when heating an IC chip in n rows and m columns
m is An=na+(n-1)C+CX(0.6~0.
8)X2mBm=mb+(n-1)C+CX
(0.6-0.8)×2m.

The aperture of the annocha 39 of the optical system 37 used at this time is made similar to the Chigg shape of n rows and m columns.

As a result, as shown in FIG. 1(b), the Al-St film 1
The Al--Si film 18 backfills the contact hole 16 due to the metal flow effect of 8. Thereafter, the W film 19 is patterned into a predetermined shape by RIE using CF4 gas using photolithography, and then Aj! -Si film 18 and Ta
The -St film 17 is sequentially patterned by RIE using B (J3) to complete the Al wiring layer 20.

By the way, the W film 19 as a light antireflection film has a light absorption coefficient of 9X for ultraviolet light with a wavelength of 308 nm, for example.
It is extremely large at 10m, and as shown in Figure 3,
In the W/Aj-S i/S 10 2/S i structure, the light reflectance can be sufficiently reduced even with the W film 19 having a thickness of about 300 mm. Therefore, the light absorption efficiency of the At-Si film 18 is increased, and the beam size can be expanded. Also, RBS
According to the analysis, when the substrate temperature is 300°C, W film 19 and A7
- It is difficult to react with the Si film 18, and since the wavelength of the irradiation beam is short, the light transmission depth is only about several tens of times, so the reaction between the W film 19 and the Al-St film 18 is suppressed to a minimum. be done. Furthermore, since the wettability of AI is good on the barrier metal Ta-Si film 17, Al flow is possible even with a small beam energy, and element damage under the Ta-Si film 17 is suppressed.

Note that the anti-reflection film is not limited to the W film 19, and may include TiW film, TiN film, Ti film, Cu film, which does not easily react with Al.
It may be a film or a Mo film.

(Effects of the Invention) As explained above, in the present invention, an anti-reflection film is formed on the Al alloy film, so the light absorption rate of the Al alloy film is improved and the beam size can be made larger than the chip size. becomes. Since the Si wafer is further heated above the recrystallization temperature of Al, AI flow is possible even with relatively small energy. At this time, since the Mb portions of the adjacent Rade beams are set on the grid line area, the elements on each IC chip are irradiated with a laser beam of uniform intensity. Therefore, damage to elements including the Al wiring layer can be suppressed, and the yield of ICs can be greatly improved.

In addition, since the antireflection film and the Al alloy film do not react, A
1. Deterioration of properties of the alloy film can be prevented. Furthermore, since the anti-reflection film acts as a protective film, it has unique effects such as preventing the occurrence of hillocks in the Al alloy film and improving migration life.

[Brief explanation of the drawing]

FIG. 1(a) and FIG. 1(bl) are diagrams for explaining the metal flow process using a laser beam in the method of the present invention,
Fig. 2 is a diagram of the laser beam irradiation pattern of the method of the present invention, Fig. 3 is a characteristic diagram showing the relationship between the thickness of the antireflection film and the light reflectance, and Figs. (b) is a diagram for explaining the metal flow process using a laser beam in the conventional method, FIG. 5 is a diagram of the laser beam nosoturn in the conventional method, and FIG. FIG. 2 is a diagram of the device. 11...Si substrate, 12...field oxide film, J
3... Dirt electrode, 14... Source/drain diffusion layer, 15... BPSGg, Je;... Contact hole, 17... Ta-Si film, J8/Al? −
St film, 19-W film. 0 20 40 60 Mark 100 R1 thickness (nm) of anti-reflection film (nm) Fig. 4 of the engineering drawings of Hiichiichino and Shin drawings of Fig. 5.

Claims (1)

[Claims] 1) forming an intermediate insulating film on a semiconductor wafer; forming a contact hole in the intermediate insulating film; and forming an Al alloy film on the contact hole and the intermediate insulating film. a step of forming an anti-reflection film on the Al alloy film; and a step of forming an anti-reflection film on the surface of the semiconductor wafer on which the anti-reflection film is formed, the beam size being larger than the chip size and a beam overlapping portion with an adjacent shot. Irradiate a laser beam set to be on the grid line of the semiconductor wafer,
Forming an electrode wiring comprising: metal-flowing the Al alloy film to fill the contact hole with the Al alloy film; and patterning the Al alloy film on which the anti-reflection film is formed to form a wiring layer. Method. 2) The electrode wiring according to claim 1, wherein the light antireflection film is made of a high melting point metal film that does not easily react with Al, and the patterning is performed so that the high melting point metal film remains on the Al alloy film even after patterning. How to form. 3) The method for forming an electrode wiring according to claim 1, wherein a high melting point metal film is formed directly under the Al alloy film. 4) The method of forming electrode wiring according to claim 1, wherein the laser beam irradiation is performed with the semiconductor wafer heated to a temperature higher than the recrystallization temperature of Al using a heater. 5) The method for forming electrode wiring according to claim 1, wherein the laser beam has a wavelength in the ultraviolet region.