JPH0760825B2 - Wiring formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring forming method.

[0002]

2. Description of the Related Art A wiring correction technique by a laser CVD direct drawing method can be applied to a multilayer wiring structure substrate such as an LSI and greatly contributes to applications such as shortening the development period of the LSI. Further, since the device is excellent in operability and stability, it is expected to be introduced into every production site of LSI. However, if the board is modified at the stage where there is no insulating protection film on the top, it is necessary to form the direct drawing wiring across the existing wiring on the surface of the board, and the direct drawing wiring and the existing wiring are insulated at a required location. Is required. As described above, the local insulation technique by laser CVD is promising as a means for forming an insulating film at a specific place as described in “Journal of Applied Physics, Vol. 69,
(3), pages 1744-1747, (1991), (JO
URNAL OF APPLIED PHYSICS,
VOL. 69, NO. 3, P1744-P1747, 1
991) ”. In this method, an ArF excimer laser is irradiated to a portion where local insulation is desired in an atmosphere of disilane and nitrous oxide gas that forms a silicon oxide film by a photochemical reaction by ultraviolet light, and an insulating film is locally formed. To do. This method requires an ArF excimer laser, which is expensive and has a high running cost, in addition to a visible light source that is usually used for laser CVD for direct drawing of wiring. . In addition, disilane gas is a highly dangerous gas that spontaneously ignites in the air, so care must be taken when handling it.
A method of forming a dielectric film by spin-coating a liquid coating material for forming a dielectric film on a substrate that absorbs visible light and locally heating the substrate by irradiation with a visible light laser is known as "Journal of Science Technology, B2,
(4), pages 641-644, 1984, (October-1
February), (JOURNAL OFSCIENCE TE
CHNOLOGY, VOL. B2, NO. 4 OCTO
BER-DECEMBER, 1984) "by Osgood et al., And there is a possibility that a local insulating film can be formed easily and safely by this method. However, since the liquid coating material for forming the dielectric film is transparent to visible light, there is a problem that the film cannot be formed when the substrate has a high thermal conductivity or a transparent substrate.

A solution of a raw material for forming a SiO ₂ film which is thinned by heating is applied to the surface of a substrate, the solvent is removed and solidified, and a metal film is directly drawn on the metal by laser irradiation at that time. After the thinning of the lower part by the action, the direct drawing line is used as a mask to remove the SiO ₂ -based film forming raw material in the part not irradiated with laser light by etching. Joint Lecture Proceedings, 5
Reported on page 65 (1992). By using this method, a SiO ₂ film can be formed as an insulating film regardless of the type of substrate. However, in a simple wet etching that requires an acidic etchant, the underlying wiring and the applied SiO
_Since the difference in etching rate from the raw material for forming the ₂ type film is generally small, the wiring on the substrate surface is likely to be damaged.

The problem of damaging the wiring on the surface of the substrate can be solved by using calixarene, which can be etched with an organic solvent instead of the SiO ₂ -based film forming raw material and which hardly causes damage to the underlying wiring. By "The 39th Joint Symposium on Applied Physics, Proceedings 56
P. 8 "(1992). (For the calix arene, refer to JP-A-4-15232.)

Normally, in direct drawing laser CVD in which a conductive thin film is formed as a wiring, the temperature of the laser irradiation portion changes depending on the laser irradiation power and the thermal conductivity of the substrate. To 400 degrees.

Calixarene is, for example, 5,11,
17,23,29,35-hexamethyl-37,38,
39,40,41,42-Hexaacetoxycalix [6] arene decomposes in the vicinity of 320 degrees, and therefore, when laser CVD is performed on the calixarene film, the calixarene film is damaged unless the irradiation intensity of the laser is precisely controlled. Imitate. It directly damages the calixarene film which is exposed to laser irradiation and has a high temperature. At the surface of the calixarene surface, which was directly exposed to laser irradiation and became hot, acetyl groups were cleaved, causing surface damage.
The surface of the conductive thin film on the calixarene is apt to undergo morphological deterioration due to damage or the like. Also, when an insulating film is formed on the calixarene and laser CVD is performed on the insulating film, since the insulating film is colorless, the laser light is transmitted and the caxarene is damaged. Therefore, the reliability of the directly drawn wiring was lower when laser CVD was performed using calixarene as an insulating film than when CVD was performed on a substrate having high heat resistance such as SiO ₂ or SiN. .

[0006]

According to the present invention, while converging a laser beam on the surface of a substrate placed in an atmosphere of a raw material gas for depositing a raw material gas for depositing a conductive material by a thermal decomposition reaction, In a wiring forming method of drawing wiring by scanning relative to a substrate, a calixarene thin film and a lane film for sequentially forming a metal thin film are etched on the substrate before drawing, and the metal under the drawing wiring is etched. A wiring forming method comprising a step of leaving a thin film and the calixarene thin film.

[0007]

When the metal thin film is formed on the calixarene as the insulating film and the laser CVD is subsequently performed, the metal thin film absorbs the laser light and is heated, and the calixarene is not directly heated. In addition, the effect on the calixarene under the heated metal thin film is that the metal has a high thermal conductivity and the heat is transferred to the metal thin film other than the laser irradiation portion, so that the thermal damage to the calixarene is greatly reduced. In the present invention, after forming a metal thin film on the surface of the calixarene, it is not necessary to precisely control the conditions of the laser CVD such as light intensity. It is possible to prevent deterioration and form a highly reliable direct drawing wiring.

A more specific process procedure is as follows. After coating calixarene on a substrate, a metal film is formed on the entire surface,
A conductive thin film is formed. A laser beam focused in a source gas atmosphere is scanned on the substrate to form a conductive thin film pattern, and at the same time, the substrate surface and the conductive thin film pattern are locally insulated. It is a thing. The coating film and the metal film other than the insulating desired are removed by etching with an organic solvent using the conductive thin film pattern formed by the laser straight line as a mask. Since the metal film is formed sufficiently thinner than the calixarene film, it can be removed together with the calixarene film by a lift-off method when etching with an organic solvent.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the method according to the present invention is applied to a wiring modification that requires wirings on both sides of the wiring over exposed wirings will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing the method of the present invention.
FIG. 2 is a diagram showing the chemical formula of 5,11,17,23,29,35-hexamethyl-37,38,39,40,41,42-hexaacetoxycalix [6] arene. First, on the surface of the silicon LSI substrate 1 having the exposed wiring shown in FIG. 1A, as shown in FIG.
11,17,23,29,35-hexamethyl-37,
38, 39, 40, 41, 42 Hexaacetochiaix [6] arene 2 is applied to form a film having a thickness of 1 μm, and then a gold thin film is formed by sputtering as shown in FIG. 17,23,29,35-hexamethyl-37,38,39,40,41,42-hexaacetoxycalix [6] arene 2 is formed to a thickness of 1/100 to 1/1000 or less. Next, silicon L
A laser CVD chamber 7 in which the SI substrate 1 is shown in FIG.
It is fixed on the XY stage 8 inside.

The XY stage 8 can be moved within a horizontal plane by a control signal from the outside. Laser direct drawing C
The emitted light of the VD Ar laser 4 is applied to the silicon LSI substrate 1 through the mirror 9, the half mirror 10, and the lens 11. The pulse-excited YAG laser 5 for forming a contact hole in the insulating film is focused and irradiated on the silicon LSI substrate 2 through the half mirror 10 and the lens 11.

Gold thin films 3 and 5, 11, 17, 23, 29 on the two wirings, wiring 12 and wiring 15, which require connection.
35-hexamethyl-37,38,39,40,41,
A contact hole is formed by irradiating the pulsed YAG laser 5 with the 4-hexaacetoxycalix [6] arene 2 to thermally evaporate it, and the wiring surface is exposed. A source gas W (CO) ₆ (Tungstelcarbonyl) was flown, and the emitted light of the Ar laser 4 was swept between both wirings to form a W line (line width 5 μm). Next, as shown in FIG. 1 (e), the silicon LSI substrate 1 is immersed in ethyl alcohol, and W
Gold thin films 3 and 5, 11, 17, 23, 2 using lines as masks
9,35-hexamethyl-37,38,39,40,4
The 1,42-hexaacetoxycalix [6] arene 2 was removed by a lift-off method, and locally 5,11,17,23,29,35 was formed between the underlying wiring and the deposited W line.
-Hexamethyl-37,38,39,40,41,42
Form an insulating film of hexaacetoxycalix [6] arene 2.

In the present invention, 5, 11, 17, 23,
29,35-hexamethyl-37,38,39,40,
Since the laser irradiation is performed not directly on the upper part of the 41,42-hexaacetoxycalix [6] arene 2 but indirectly by using the gold thin film 3 as a protective film, 5,11,17,23,2
9,35-hexamethyl-37,38,39,40,4
The thermal damage to the 1,42-hexaacetoxycalix [6] arene 2 is significantly reduced, and a directly drawn W line with good morphology can be obtained. Therefore, the reliability and controllability of wiring correction are improved.

In the present invention, other than the calixarene used in the examples, a caricarene which has good solubility in an organic solvent such as ethyl alcohol and can lift off a metal thin film during etching is shown in FIG. 3 (a). Examples include tributyl calix [8] arene acetate and tributyl calix [6] arene acetate shown in FIG. 3 (b).

In the present invention, it is not always necessary to use gold as the protective film, and tungsten, aluminum, molybdenum, chromium or the like may be used.

The raw material gas for direct drawing is W (CO) ₆ as well as Mo (CO) ₆ (molybdenum carbonyl) and Cr.
(CO) ₆ (chromium carbonyl) and Au (CH ₃ ) (A
cAc) AuF ₃ (CH ₃ ) (AcAc) (dimethyl gold acetylacetonate, dimethyl gold fluoroacetylacetonate).

In addition to ethyl alcohol, the etching solution includes organic solvents such as acetone, xylene, toluene and monochlorobenzene.

Although the sputtering method is used for forming the protective film in the present invention, another film forming method such as a vapor deposition method may be used as long as the temperature is low enough not to damage the calix arene.

[0019]

EFFECTS OF THE INVENTION In wiring formation by laser direct writing CVD using calixarene as an insulating film, by using a metal thin film as a protective film for calixarene, it is possible to precisely control laser CVD conditions such as light intensity. Also, the morphology of the surface of the calixarene is not deteriorated, the insulating film can be locally formed without deteriorating the film quality of the drawing wiring, and a highly reliable direct drawing wiring can be formed.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment to which the present invention is applied.

FIG. 2 is a diagram showing the chemical formula of 5,11,17,23,29,35-hexamethyl-37,38,39,40,41,42-hexaacetoxycalix [6] arene.

FIG. 3 is a diagram showing the chemical formula of another calixarene that can be carried out in the present invention.

[Explanation of symbols]

1 Silicon LSI Substrate 25, 11, 17, 23, 29, 35-Hexamethyl-37, 38, 39, 40, 41, 42-Hexaacetoxycalix [6] arene 3 Gold Thin Film 4 Ar Laser 5 Pulse Excited YAG Laser 6 W (CO) ₆ 7 Laser CVD chamber 8 XY stage 9 Mirror 10 Half mirror 11 Lens 12 Wiring 13 Wiring 14 Wiring 15 Wiring

Claims (1)

[Claims] 1. A wiring is drawn on a surface of a substrate placed in an atmosphere of a raw material gas for depositing a conductive substance by a thermal decomposition reaction while scanning laser light while relatively scanning the substrate. In the wiring forming method, a step of sequentially forming a calixarene thin film and a metal thin film on the substrate before drawing, and further after drawing the wiring, the calixarene film is etched by using this drawing wiring as a mask to form the drawing wiring. A wiring forming method comprising a step of leaving the metal thin film and the calixarene thin film below.