JPH0644564B2 - Wiring formation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of forming repair wiring on the surface of a semiconductor device, and more particularly, to a defective portion when a partial defect exists in a prototyped semiconductor device. The present invention relates to a wiring forming method suitable for specifying and repairing.

[Conventional technology]

In recent years, the degree of integration of semiconductor devices has been remarkably increased, and the wiring layers have also been multi-layered. For this reason, semiconductor devices in the process of development do not always operate as designed, and by temporarily disconnecting the wiring on the chip or by connecting an arbitrary part to identify the defective part or repairing it temporarily. The characteristics are evaluated so that a complete operation can be obtained.

As a method of connecting any of these, the Extended Abstract of the Seventeenth Conference on Solid State Devices and Materials, Tokyo (1985), pages 193 to 196 Page (Extended Abstracts of the 17-th Conferen
ce on Solid State Devices and Materials, Tokyo 1985
pp193-196). That is,
Mo (MO) ₆ vapor in a CVD cell installed on the XY stage and atmospheric pressure Ar gas were introduced, and a Si substrate coated with SiO ₂ in the CVD cell was initially irradiated with an Ar ion laser of several 10 μW. The Mo film is deposited by photochemical reaction by irradiating 2 harmonics (wavelength 257 nm), and then the fundamental wave (wavelength 515 nm) of Ar ion laser of several 100 mW is irradiated on the Mo film deposited by photochemical reaction locally. After performing thermal CVD, place the CVD cell in XY
It is moved by a stage to form Mo wiring and connect arbitrary places.

[Problems to be solved by the invention]

In the above conventional technology, the specific resistance of the formed Mo wiring is 40 μΩ · cm.
And 8 times larger than the bulk resistivity (5.4 μΩ · cm). Therefore, when it is used for repair wiring of a high-speed logic LSI used in a large-scale computer or the like, the signal is delayed and the characteristics cannot be evaluated.

There is a method of increasing the wiring film thickness as a countermeasure for reducing the resistance value of the wiring. However, due to the residual stress of the film formed by laser CVD, the difference in the expansion coefficient from the substrate, and the like, cracks or peeling occur. Occurs, and there is a limit to the increase in film thickness.

Therefore, in order to reduce the resistance value of the wiring, it is essential to reduce the specific resistance of the wiring itself.

An object of the present invention is to provide a method for forming a repair wiring having a small specific resistance without causing signal delay.

[Means for solving problems]

The above-mentioned object is to provide a vacuum device for maintaining the wiring formed by laser CVD in a non-oxidizing or reducing atmosphere, and an energy beam focused to the same width as the wiring, for example, a laser beam focused to the same width as the wiring. This is achieved by annealing the wiring by means of irradiation to improve the film quality.

[Action]

The wiring to be annealed by laser light irradiation is CV beforehand.
It is formed by operating while irradiating a sample (semiconductor integrated circuit) with a laser beam focused in a D gas atmosphere. The CVD gas surrounding the wiring is exhausted to 10 ^-5 Torr
By keeping the sample in the above vacuum or in the atmosphere of inert gas or reducing gas, the wiring surface is prevented from being oxidized in the process of annealing.

By irradiating the energy beam (laser light) focused to the same extent as the width of the wiring, uniform annealing and high-speed processing can be performed. This is because if the light is condensed within the width, the effect of re-evaporation becomes more remarkable than the effect of annealing and the wiring is damaged.

The wiring that has been irradiated with an energy beam such as a laser is locally heated, and the specific resistance of the wiring is reduced by improving the crystallinity of the wiring material and removing impurities such as carbon and oxygen.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows an apparatus suitable for carrying out the method of the present invention. The apparatus includes a laser oscillator 1 that oscillates a laser beam 2, a dichroic mirror 3 that reflects the laser beam 2 and guides it to a sample 19, and an objective lens 4 that collects the laser beam 2 and irradiates it onto the sample 19. A processing optical system, a filter 6 for extracting the observation light 8 having a wavelength close to that of the observation light source 5 and the laser 2, a half mirror 7 for guiding the observation light 8 onto the sample 19, and an image of the sample 19. An observation optical system including an imaging lens 9 for forming an image, a prism 10 and an eyepiece lens 11, and a chamber 13 for accommodating a sample 19 which is an object of wiring formation, and a window for introducing a laser beam 2 12, CVD
A gas supply / exhaust system including a gas introduction pipe 14 connected from a cylinder 16 containing a material gas via a valve 15 and an exhaust pipe 17 connected to a vacuum exhaust device (not shown) via a valve 18 is further provided. , A Z stage 20 for mounting the sample 19 and moving the sample 19 in the optical axis direction for focusing with the laser light 2 and the observation light 8, and XY for moving the sample 19 in a plane perpendicular to the optical axis. A chamber 13 having a sample position specifying means including a stage 21 and a computer 22 for controlling the drive of the Z stage 20 and the XY stage 21 and the drive of a shutter 23 for opening and closing the optical path of the laser beam 2 It's made up.

Next, a procedure for forming a wiring using the above device will be described.

First, the valve 15 is closed, the valve 18 is opened, and the inside of the chamber 13 is evacuated by a vacuum evacuation device (not shown) until the degree of vacuum reaches 10 ^−b Torr or more. Then, after closing the valve 18, the valve 15 is opened to introduce the CVD gas into the chamber 13 until the desired pressure is reached, and the valve 15 is closed to keep the CVD gas in the chamber 13. Then, the sample is moved to an arbitrary place by the XY stage 21 while observing the pattern on the sample 19 by the observation optical system.

Next, the laser beam 1 is oscillated from the laser oscillator 1 and the shutter
23 is opened and the laser light 2 is condensed by the objective lens 4 and irradiated on an arbitrary position of the sample 19. Laser light 2 for CVD gas
Is decomposed by the thermal energy of and the wiring material is deposited.
The deposition is an XY stage 20 controlled by a computer 22.
It moves at an arbitrary speed to the desired connection position along the movement of. The wiring is completed by closing the shutter 23 and stopping the irradiation of the laser beam 2.

After forming all the repair wirings, the valve 18 is opened, and the CVD gas in the chamber 13 is exhausted by a vacuum exhaust device (not shown) to make a vacuum of at least 10 ⁻⁵ Torr. Then, the sample 19 is moved back and forth in the optical axis direction by the Z stage 20 so that the irradiation diameter of the laser beam 2 becomes approximately the same as the width of the wiring formed by the above method. The computer 22 controls the XY stage 21 so as to irradiate only the wiring portion with the defocused laser beam thus obtained, and moves the wiring at an arbitrary speed to anneal the wiring.

Next, the wiring forming procedure will be specifically described with reference to FIG.

First, as shown in FIG. 2 (a), an Al wiring layer is formed on the Si substrate 30 with the SiO film 31 interposed therebetween.
A sample in which 33 is formed and the passivation film 32 is formed on the entire surface is shown. The passivation film 32 on the Al wiring layer 33 in the portion that requires connection is windowed by a technique such as etching using a lithography technique, laser processing, or ion beam processing, and windowed portions 34a and 34b are formed. This sample is placed in a CVD gas 35 atmosphere (for example, Mo
Laser light 2 (for example, Ar laser fundamental wave, power 20) was placed on (CO) ₆ vapor 0.1 Torr and focused on the window opening 34a.
0 mW). Then, while the CVD gas 35 is decomposed by a thermochemical reaction to deposit the Mo film 36, the sample is moved in the direction of the arrow to the window opening 34b at an arbitrary speed (for example, 0.1 mm / min). Thus, as shown in FIG. 2C, the Mo film 36 connects the Al wirings in the window openings 34a and 34b. Next, as shown in FIG. 2 (d), the CVD gas 35 is exhausted and at least 10
-Expose the sample in a vacuum atmosphere of ^-5 Torr. And laser light 2
The sample is shifted back and forth in the optical axis direction so that the irradiation diameter of the Mo film 36 is about the same as the Mo film 36, and the Mo film 36 deposited on the window opening 34a is irradiated and annealed. The sample is moved in the direction of the arrow so that the irradiation reaches the window opening 34b, and only the Mo film 36 is annealed as shown in FIG. 2 (e).

In this method, the laser beam 2 is applied to the Mo film 36 when annealing is performed.
Since the irradiation is performed with a diameter approximately equal to the width, the annealing can be performed uniformly in a short time. When the focused laser light is irradiated a plurality of times, the deposited Mo film 36 is likely to be peeled and deteriorated, and stress stress is likely to remain in the film itself.

The effect of annealing by this method is that the resistivity of the deposited Mo film is about 30 μΩ ・ cm, whereas
The specific resistance of 38 is about 11 μΩ · cm, and the specific resistance can be reduced by about 40%. There is no significant change in the geometry of the Mo film before and after annealing. Therefore, the crystallinity of the Mo film can be improved and impurities such as carbon and oxygen can be removed by laser annealing without changing the film thickness and the wiring width. In addition, the laser 2 is used to open the windows 34a and 34b.
By illuminating the Mo film 36 for a few minutes, the contact portion between the Mo film 38 and the Al wiring is alloyed by the diffusion phenomenon due to heat, and the contact resistance can be reduced.

Here, the laser light 2 is converged by the objective lens 4, but a cylindrical lens 24 may be used as shown in FIG. That is, the objective lens 4 is used when wiring is formed, and the cylindrical lens 24 is used when annealing is performed.
By using, the laser light 2 is linearly condensed, and annealing can be performed with uniform energy with respect to the width of the wiring. According to this method, since the sample 19 is not displaced from the focus position of the observation light 8, there is an effect that the alignment at the time of annealing is facilitated.

Although the sample 19 was placed in a vacuum atmosphere at the time of annealing in this example, the same effect can be obtained in a reducing atmosphere or an inert gas atmosphere.

Next, a wiring forming method which is another embodiment of the present invention will be described with reference to FIG.

Regarding the configuration of the device, the processing optical system and the tourism system are the same as those described in FIG. The chamber 40 has a window 12 for introducing the laser beam 2 in the upper part, a nozzle 41 installed so that the sample 19 CVD gas can be sprayed inside, and the CVD gas is stored at the tip of the nozzle 41. Cylinder 16 and valve for adjusting the flow rate of CVD gas
Fifteen are tied. Further, the sample 19 has a nozzle 42 installed so as to blow the reducing gas, and a cylinder 44 containing the reducing gas and a valve 43 for adjusting the flow rate of the reducing gas are connected to the tip of the nozzle 42. And nozzle 4
An exhaust pipe 45 for exhausting the CVD gas and the reducing gas is provided so as to oppose the 1, 42, and a valve 18 for adjusting the exhaust amount is connected to the exhaust pipe 45 so that the CVD gas or the reducing gas can be discharged. It is designed to be able to exhaust a certain amount.

The sample 19 is placed on a stage 20 which moves back and forth in the optical axis direction in order to focus the laser beam 2 and the observation light 8 and an XY stage 21. The Z stage 20 and the XY stage 21 are connected to a computer 22, and movement control to a predetermined position at an arbitrary speed is possible.

Next, a procedure for forming a wiring using the above-mentioned device will be described.

First, the valve 18 is opened with the valves 15 and 43 closed, and the chamber 0 is evacuated to at least 1 by a vacuum exhaust device (not shown).
Evacuate to a vacuum of 0 ^-6 Torr. While observing the pattern of the sample 19 by the observation optical system during the evacuation, the XY stage 21 moves the sample 19 to an arbitrary place. Thereafter, the valve 15 is opened and the CVD gas is sprayed onto the sample 19 from the nozzle 41. The sprayed CVD gas is exhausted from the exhaust pipe 45, and the CVD gas exists only near the sample 19. In this state, the laser light 2 is condensed by the objective lens 4 and irradiated on an arbitrary place of the sample 19, and the CVD gas is decomposed by the thermal energy to deposit the wiring material. This deposition is controlled by computer 22 XY stage 21
Move at any speed along the movement of to the position you want to connect. After forming the desired wiring, the shutter 23 is closed to shut off the optical path of the laser beam 2 and the wiring forming process is completed. And after forming all the repair wiring, the valve
15 is closed and the supply of CVD gas is stopped. Then valve 43
And the reducing gas is blown onto the sample 19 through the nozzle 42.
The blown reducing gas is exhausted from the exhaust pipe 45, and the reducing gas exists only near the sample 19. In this state, the sample 19 is moved back and forth in the optical axis direction by the Z stage 20 so that the irradiation diameter of the laser beam 2 with respect to the wiring formed by the above method becomes approximately the same as the width of the wiring. In this way, the XY stage 21 is controlled by the computer 22 so that only the wiring portion is irradiated with the laser light 2 with the laser light 2 defocused, and the wiring is annealed by moving the XY stage 21 at an arbitrary speed.

As a result, the crystallinity of the wiring can be improved, impurities such as carbon and oxygen can be removed, and the specific resistance can be reduced.

Furthermore, according to the present embodiment, it is not necessary to completely exhaust the CVD gas after forming the wiring, so that there is an effect that the transition to the annealing process after the wiring formation can be performed quickly.

Here, in order to precipitate Mo as a wiring material, Mo (CO) ₆
However, MoCl ₅ , MoF ₆ or the like can also be used. When W is deposited as another wiring material, W (CO) ₆ or WF ₆ , and Ni (CO) ₄ is deposited as Ni, and the fundamental wave of the Ar laser (wavelength) is used as laser light for deposition annealing.
514.5 nm), or the second harmonic of Ar laser (wavelength 257 nm) is used to deposit Al (CH ₃ ) ₂ to Al and Cd (CH ₃ ) ₂ to Cd, and anneal with Ar laser fundamental wave. Any combination that does However, the present invention is not limited to these.

〔The invention's effect〕

According to the present invention, since the resistance value of the wiring formed by laser CVD can be reduced, it can be used as a repair wiring for a semiconductor device in which signal delay is a problem. Further, since the energy beam such as a laser is applied only to the above wiring, there is an effect that repairing can be carried out without exerting a thermal influence on the surrounding completed elements.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment for forming the wiring of the present invention, FIG. 2 is a diagram for explaining the wiring forming process of the present invention, and FIG.
FIG. 4 is a diagram showing another embodiment for forming wiring according to the present invention, and FIG. 4 is a diagram showing another embodiment for forming wiring according to the present invention. 1 ... Laser oscillator, 2 ... Laser light, 4 ... Objective lens, 13 ... Chamber, 16 ... CVD gas cylinder, 19 ...
… Sample, 20 …… Z stage, 21 …… XY stage, 22
…… Computer, 33 …… Al wiring layer, 34a, 34b …… Window opening, 36 …… Mo film, 38 …… Annealed Mo film, 24 …… Cylindrical lens, 41,42 …… Nozzle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidezo Sano Inventor Shuzo Sano 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside Production Engineering Laboratory, Hitachi, Ltd. (72) Inventor Katsuro Mizukoshi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Production Technology Laboratory, Hitachi, Ltd. (56) References JP-A-60-216555 (JP, A)

Claims (5)

[Claims] 1. A wiring to be connected to a conductor is formed by local CVD, and a laser is relatively scanned on the formed wiring in an atmosphere of a vacuum, a reducing gas or an inert gas, and the formed wiring is formed. A method for forming a wiring, characterized in that the resistance is locally reduced by heating the metal. 2. The local CVD is a CVD using a laser.
The wiring forming method according to claim 1, wherein 3. The wiring forming method according to claim 2, wherein the laser for performing the local CVD and the laser for locally heating are performed using the same laser light source. 4. The wiring forming method according to claim 2 or 3, wherein the step of forming wiring by the local CVD is CVD using an organic metal gas. 5. The wiring formed by the local CVD is M
5. The wiring forming method according to claim 4, which is a refractory metal such as o or W.