JP2518419B2 - Laser CVD equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for forming a metal thin film on a sample such as a semiconductor or an integrated circuit by a laser CVD method and correcting a wiring pattern.

[Conventional technology]

2. Description of the Related Art In recent years, a thin film forming method by a laser CVD method has attracted attention as a technique capable of quickly performing wiring correction and failure analysis of semiconductors / integrated circuits, and various studies have been made. For example, W (Co)
₆ (Tungsten cambonyl) placed in vapor atmosphere
There is a report that an Ar laser beam was focused and irradiated on an LSI substrate and a W line with a width of several μm was drawn by moving the substrate (The 35th Joint Lecture on Applied Physics, 29p-G-7). In addition, the same technology can be applied to the defect correction of the thin film transistor (hereinafter referred to as TFT) substrate for liquid crystal panel.
There is a report that it was corrected by (35th Joint Lecture on Applied Physics, 30a-ZG-3). A general configuration example of this type of device is shown in FIG.
2, an optical system including a mirror 6, a beam expander 10, an objective lens, an illumination unit 27, an observation unit 28, an XY stage 18 for placing and moving a sample, a reaction chamber 16, a metal compound vapor supply source 22, and It consists of an exhaust unit 24 etc. The general wiring correction process using this device
This will be described with reference to FIGS. FIG. 6 shows a case where there is no interlayer insulating film or protective film on the wiring pattern (usually metal Al) to be corrected, and in the atmosphere of the metal compound vapor 36, the CW laser light focused in a spot form from the wiring 31. By scanning toward the wiring 32, a continuous metal film 34 is drawn.
A metal wire with a line width of several μm and a film thickness of several thousand Å can be formed with a scan speed of several μm / s and a laser beam spot diameter of several μm. CW laser light usually has a wavelength of 0.515 μm or 0
Although 488 μm Ar laser light is used, in order to suppress the heat spread due to thermal diffusion, the second harmonic light (wavelength 0.53 μm) of a CW pumped Q-switched Nd: YAG laser may be used. FIG. 7 shows a case where an insulating film or a protective film is present on the wiring pattern to be modified, and can be divided into two steps as shown in FIGS. 7 (a) and 7 (b). First, in FIG. 7A, in the step of forming a via hole 37 in the insulating film 33 on the wirings 31 and 32, the pulsed laser light different from the CW laser light is focused in the spot shape for this purpose. Then, the wirings 31 and 32 are irradiated, and the insulating film 33 on the wirings 31 and 32 is evaporated and removed to form holes. Here, it is known that the shorter the pulse width of the laser light used, the better the shape of the hole to be machined. Normally, the pulse-pumped Q-switched Nd: YAG laser or its second harmonic or fourth harmonic light is generated. The pulse width used is in the range of several tens to several ns. Next, in FIG. 7 (b), as in FIG.
Wiring from CW laser light from wiring 31 in metal compound vapor atmosphere
Scan toward 32. In this way, the wiring 31 and the wiring 32 existing under the insulating film 33 can be connected.

[Problems to be Solved by the Invention]

According to the conventional laser CVD apparatus described above, an integrated circuit or T
It is possible to modify the wiring pattern of the FT substrate, but since the metal film formed by laser CVD is exposed on the surface, the film surface is oxidized and the resistance gradually increases,
Humidity and temperature changes may deteriorate electrical characteristics and physical strength. Therefore, although the modified sample can be sufficiently used as a short-term operation evaluation sample in the development and trial production stage, it cannot be used as a long-term evaluation sample or a final product to be shipped to the user. Also, in the case of a TFT substrate for a liquid crystal panel, liquid crystal is filled on the TFT circuit pattern, and it is sandwiched by a glass plate with a transparent electrode pattern, so do not short circuit.
It is necessary to attach an insulating film on the TFT circuit pattern, and since the substrate modified by the conventional laser CVD device cannot be used as a product as it is, there is a drawback that the insulating film must be applied again by another device after the modification. is there.

[Means for solving the problem]

The laser CVD apparatus of the present invention is a device for forming a metal thin film on a sample substrate by irradiating a laser beam on a sample substrate that is in contact with a metal compound vapor and thermally decomposing the metal compound vapor. An insulating material supply source for applying an insulating film and a nozzle are provided, and the applied insulating film applied by the nozzle is irradiated and heated by the laser beam to be dried and solidified.

The present invention has a mechanism for forming an insulating film on a metal pattern formed by laser CVD, so that not only can the reliability of a modified sample be improved, but it can also be applied to the final product, which was difficult with conventional equipment. Has the advantage.

First Embodiment Next, the present invention will be described with reference to the drawings. First
1 is a block diagram of a device configuration showing a first embodiment of the present invention. A pulsed laser light source 1 is used for forming a via hole in an insulating film or a protective film or cutting an aluminum wiring. Normally, pulse excitation Q switch Nd: YAG
Laser (wavelength 1.06 μm) and its second harmonic light (wavelength
0.53 μm), fourth harmonic light (wavelength 0.266 μm), etc. are used. Reference numeral 2 is a CW laser light source for laser CVD, and in the present invention, a CW pumped Q-switched Nd: YAG laser, and 3 is an SHG element. As a result, the second harmonic light (wavelength 0.53 μm) having a pulse width of several hundred ns and a repetition rate of several kHz can be obtained. In this configuration example, the SHG element 3 is placed outside the Nd: YAG laser 2, but it may be placed inside (so-called internal SHG). Reference numeral 4 is a dichroic mirror, which has the property of totally reflecting the fundamental wave (hereinafter referred to as 1.06 μm light) that has not been converted by the SHG element and transmitting the second harmonic light. A dichroic mirror 5 has a property of totally reflecting the laser light emitted from the pulse laser 1 and transmitting the second harmonic light from the SHG element 3. A mirror 6 totally reflects the laser light emitted from the pulse laser 1. 10 and 11
Is a beam expander, which serves to expand the beam diameter of the laser upon incidence and to collimate, and is a combination of a concave lens and a convex lens in this figure, but a combination of a convex lens and a convex lens may be used. Since the beam diameter (diameter) of laser light is usually about 1 to 2 mm, this is expanded to about 5 to 10 mm. This is to make it possible to collect the laser beam with a lens so that it can be condensed to a smaller size, but if it is not necessary to reduce the beam diameter on the sample so much,
This beam expander may be omitted. 7 is 1.
Mirrors for totally reflecting 06 μm light, and 12 and 29 are shutters for blocking the beam. 8 is a two-wavelength mirror that totally reflects both pulse laser and CW laser, 9 is a mirror 8
It is a dichroic mirror that reflects the laser light coming from the laser and transmits the 1.06 μm light emitted from the beam expander 11. A dichroic mirror 13 has a property of reflecting laser light and transmitting visible light other than the laser wavelength. Reference numeral 14 denotes a condenser lens, which has a function of condensing the laser light on the sample, and is usually a microscope objective lens. Reference numeral 15 is a window, which is made of quartz glass that transmits laser light and visible light for observation light well. Reference numeral 16 denotes a chamber on which a sample can be placed, and a metal compound vapor introduction port 19, a discharge port 20, and an insulating material supply nozzle 21 are installed. Reference numeral 17 denotes a sample such as a semiconductor or an integrated circuit, which is placed on the XY stage 18 with the pattern surface to be corrected as the upper surface. Reference numeral 22 is a metal compound vapor supply source. When metal carbonyl such as W (Co) ₆ or Cr (Co) ₆ is used as a raw material, it is a heater for vaporizing the raw material, and is for diluting the vaporized gas and supplying it to the chamber. It consists of an inert gas supply source. An insulating material supply source 23 is normally filled with a liquid insulating material, and is configured to supply a fixed amount from the nozzle 21 onto the sample when necessary. The nozzle 21 has a needle-like shape with an outer diameter of about 1 mm and an inner diameter of about 0.5 mm at the tip, and is installed close to the sample surface within a range that does not interrupt the laser light. Reference numeral 24 denotes an exhaust unit for exhausting gas in the chamber, which is composed of a metal compound trap and a vacuum pump. Reference numeral 25 is a filter for blocking the laser light, which is for preventing the laser light from entering the observation unit. 26 is a half mirror and lighting unit
The illumination light from 27 is reflected, and the observation light reflected from the sample is transmitted. 27 is a lighting unit, which comprises a lamp and a collimator. An observation unit 28 is composed of an eyepiece and a TV camera, and the surface of the sample can be observed with an inner eye or a TV monitor.

The wiring correction process according to this device example will be described below with reference to FIGS. 4, 6, and 7. First, the sample is set in the chamber, the chamber is evacuated and purged, and the metal compound vapor is caused to flow. Next, if the sample is a sample without a protective film, the laser CV is used as shown in FIG.
Do D. If the sample is a sample with a protective film, a via hole is formed using a pulse laser 1 as shown in FIG. 7 (a), and then a laser light source 2 is formed as shown in FIG. 7 (b). Is used to perform laser CVD. When the laser CVD process is completed, the supply of the metal compound vapor is stopped, and the chamber is evacuated and purged. And finally laser CVD
A step of forming an insulating film in a place is performed. This is, as shown in FIG. 4, a step of applying a desired insulating material to the sample surface (FIG. 4 (a)), and a step of drying and solidifying the applied insulating film 35 by laser light (see FIG. b) and (c)). First, in the insulating film coating step, as shown in FIG. 4 (a), the portion subjected to laser CVD is positioned near the insulating material supply nozzle 21, and a certain amount of insulating material is dropped to apply the insulating coating film.
Form 35. In this case, it is necessary to adjust the dropping amount and move the sample according to the desired range. next,
As shown in FIG. 4 (b), the coating insulating film portion is condensed and irradiated with laser light emitted from the laser light source 2, that is, 1.06 μm light, and heated to dry and solidify. For this purpose, the shutter 29 should be closed and 12 open. When the area to be dried and solidified is wider than the focused beam diameter, the laser beam is scanned. Further, in a narrow range, the focused beam diameter may be increased and the irradiation may be performed all at once as shown in FIG. 4 (c). For this purpose, the beam expander 11 may be adjusted to change the divergence angle of the laser light to defocus the focusing position and increase the beam diameter on the sample. May be changed to one having a different focal length to reduce the magnification and increase the focused beam diameter on the sample. As described above, when the step of drying and solidifying the insulating film is completed, the sample is taken out and the correction work is completed.

Here, an insulating material that can be used in the present invention will be described.
The easiest material to handle is a material that is liquid at room temperature and solidifies when heated. Recently, a coating liquid for forming a SiO ₂ film of this kind has been commercially available for semiconductor devices, for example, an OCD coating liquid manufactured by Tokyo Ohka Kogyo. This is a coating solution used not only in the field of semiconductors but also when forming a protective film and an insulating film required in the production of various electronic component materials, and a silicon compound and an additive dissolved in an organic solvent, Suitable for the present invention. Other than this, it can be used if it has similar properties.

In addition, in this embodiment, the insulating material is described as a liquid that is suitable as a liquid, but may be atomized and sprayed.

[Embodiment 2] FIG. 2 is a block diagram of an apparatus configuration showing Embodiment 2 of the present invention. In this embodiment, the laser section, the chamber section, the raw material supply section, etc. have the same construction as in the first embodiment, but the laser optical system is slightly different. That is, the slit 30 is installed after the beam expander 11. This is because the beak shape and beak diameter condensed on the sample are made variable by limiting the beam diameter of 1.06 μm light for drying the coating insulating film. Generally, there is a relation of d = 4λf / (πD) between a parallel beak (wavelength λ) having a diameter D and a spot diameter d when the lens having a focal length f condenses, and the incident beam diameter D can be reduced. By doing so, the spot diameter d can be increased. Therefore, when it is desired to increase the diameter of the laser beam on the sample surface as described in the first embodiment, it is sufficient to reduce the opening diameter of this slit, and it is not necessary to adjust the beam expander 11. Similarly, when the shape of the focused beam on the sample surface is desired to be rectangular instead of circular, the opening shape of this slit may be rectangular.
The shapes of such various slits are shown in FIG.
(A) is a circular slit, (b) is a rectangular slit,
The shape and size are fixed. Therefore, several different shapes and sizes may be prepared in advance and they may be exchanged at appropriate times. (C) is a variable circular slit, which is realized by an electric aperture mechanism used in a camera or the like. (D) is a variable rectangular slit, which has a structure in which two sets of opposing knife edges are in close contact with each other, and the opening width can be continuously varied by linearly moving each knife edge by a motor drive. it can. In any case, it is possible to easily change the shape of the focused beam by the slit described above, as compared with the case of the first embodiment. Therefore, there is an advantage that the work efficiency of the coating insulating film drying step is improved.

It should be noted that, in the above-mentioned embodiment, the Nd: YAG laser was used as the laser light source, and it was dried and solidified with 1.06 μm light.
It goes without saying that light may be used or an Ar laser or another laser light source may be used.

〔The invention's effect〕

As described above, according to the present invention, an insulating film can be locally attached to a portion subjected to laser CVD to protect the portion, so that the life and reliability of the wiring formed by laser CVD are improved. There is an effect that can be done. Therefore, the semiconductor or integrated circuit modified by the device of the present invention has an advantage that it can be shipped not only as an evaluation sample at the development and trial production stage but also as a final product. Further, if the present invention is applied to the modification of a TFT substrate for a liquid crystal panel or the like, it can be immediately put into the production line of the next step without the need for another insulating film coating device. Not only can it be significantly shortened, but it also has the advantage of not increasing the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a block diagram of a device configuration showing a first embodiment of the present invention,
FIG. 2 is a block diagram of an apparatus showing Example 2, FIG. 3 is an external view of various slits, FIG. 4 is a process diagram of forming an insulating film of the present invention, FIG. 5 is a block diagram of a conventional apparatus, Sixth
7 and 8 are process diagrams of wiring correction. 1 ... Pulse laser, 2 ... CW pumped Nd: YAG laser, 3 ...
… SHG element, 10,11 …… Beam expander, 14 …… Condenser lens, 17 …… Sample, 19 …… Metal compound vapor inlet,
20 …… outlet, 21 …… insulating material supply nozzle, 22 …… metal compound vapor supply source, 23 …… insulating material supply source, 24 …… exhaust unit, 30 …… slit.

Claims (1)

(57) [Claims] 1. An apparatus for forming a metal thin film on a sample substrate by irradiating a laser beam on a sample substrate that is in contact with the metal compound vapor to thermally decompose the metal compound vapor, thereby forming an insulating film on the sample surface. A laser CVD apparatus comprising an insulating material supply source and a nozzle for coating, and configured to irradiate and heat the coating insulating film coated by the nozzle with the laser beam to dry and solidify.