JPS59155922A - Device for depositing metal by laser - Google Patents

Abstract

PURPOSE:To ensure monitoring of film thickness by a method wherein when a sample substrate is attached to a window of a cell containing metal complex solution and is irradiated with laser beam for excitation to deposit metal on the back surface of the substrate, laser beam for probe is projected into simultaneously to detect state of deposition of metal by permeable ray of the probe light. CONSTITUTION:Emitted light rays from a source 1 of laser beam for excitation and a source 2 of laser beam for probe are lapped in parallel by a beam compounding device 3 and are projected into a sample substrate 5 attached to a window of a solution cell 6 through a light collecting optical system 4 comprising a microscopic observing optical system 7. The cell 6 is filled with benzene solution including bisbenzene Mo metal complex of 10<-2>-10<-1>mol/l of concentration and the cell 6 is adjusted minutely by using a driving device 8. Meanwhile on the opposite side to the substrate 5 in the cell 6, a filter 9 and a light detector 10 are arranged to detect the film thickness of metal deposited on the back surface of the substrate 5. After that, a chopper 11 arranged on an optical path of the source 2 and the light detector 10 are connected to a controller 13 through a lock-in amplifier 12 and the output is returned to the laser source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser metal deposition apparatus for depositing metal on a sample substrate using laser light.

BACKGROUND OF THE INVENTION With the development of integrated circuits, etc., local metal deposition techniques in minute areas have become necessary.

For example, in addition to blind defects (black defects), hole defects (white defects) may occur in photomasks for integrated circuits, so metals such as chromium and molybdenum are locally applied onto the photomask. It is necessary to fill this hole by depositing a large amount of material. In particular, the presence of even a single defect is not tolerated in the reticle used in the step-and-repeat method, so repairing hole defects is absolutely necessary from the perspective of improving photomask productivity. It has become a technology.

For this reason, in recent years, various laser metal deposition apparatuses have been proposed that take advantage of the light focusing and high brightness properties of laser light, and attempts have been made to put them into practical use.

This laser metal deposition technology can be roughly divided into two methods: deposition from a gas phase and deposition from a liquid phase. Although deposition from the gas phase has a promising future as a dry process, many metal compound gases are dangerous to handle;
Because it is troublesome and the rate of deposition from the gas phase is not very fast, research is currently being carried out to put deposition into practical use mainly from the liquid phase.

This metal deposition method from the liquid phase uses a solution of a metal complex such as bisbenzene molybdenum, irradiates the metal complex solution with strong laser light to liberate the metal, and thereby deposits the metal onto the sample substrate. Recently, the method of deposition has been attracting attention as a safe and simple method.

However, with conventional metal deposition equipment from the liquid phase, it was not possible to monitor the metal deposition process well, resulting in uneven deposited film thickness and insufficient filling of hole defects. However, there were some drawbacks in terms of reliability and operability. That is, in the conventional laser metal deposition apparatus,
The reflected light of the laser beam from the metal deposited on the sample substrate was monitored, but this method has the drawback of overlooking the presence of extremely small pinballs. In addition to monitoring the excitation light, the transmitted light is monitored. Although it is possible in principle,
Since the wavelength of the excitation laser light is selected within the absorption band of the metal complex solution, the excitation light is strongly absorbed by the solution, making it impossible to keep the photodetector separate from the sample substrate, and causing problems with the equipment. The disadvantage is that there is no freedom in configuration.

An object of the present invention is to eliminate these conventional drawbacks and provide a highly reliable laser metal deposition apparatus that can monitor metal film thickness.

The configuration of the present invention includes an excitation laser light source, a condensing optical system that condenses excitation light from the excitation laser light source, and a condensed excitation light that is incident through a sample substrate used as a window material. A laser metal deposition apparatus comprising a metal complex solution cell, in which the incident light liberates metal from the metal complex and deposits the metal at a desired position on the sample substrate, wherein the excitation laser light source is A glove laser light source with different oscillation wavelengths and a glow from this glove laser light source? - a beam combiner that superimposes the probe light in parallel with the excitation light and makes it enter the solution cell; and a metal complex solution that interposes the probe light transmitted through the sample substrate with a metal complex solution behind the sample substrate with respect to the incident light; The invention is characterized in that it is equipped with a photodetector for detecting.

Next, the present invention will be explained in detail with reference to the drawings.

The figure is a block diagram showing a schematic configuration of an embodiment of the present invention. Excitation laser light source 1 and probe laser light source 2
The emitted laser beams are superimposed in parallel by a beam combiner 3, focused by a condensing optical system 4, and then entered into a solution cell 6 via a sample substrate 5 used as a window material. incident. This solution cell 6 contains a concentration of 1o-2 to 10-
It is filled with a benzene solution in which approximately 1 mol of bisbenzene molybdenum metal complex is dissolved, and the back surface of the sample substrate 5 is immersed in the metal complex solution.

The irradiation position of the laser beam onto the sample substrate 5 is determined by finely adjusting the solution cell 6 using the driving device 8 while observing the pattern provided on the back surface of the sample substrate 5 using the microscope observation optical system 7. Positioned by

On the other hand, the globe light from the light source 2 is detected by a photodetector 10 via a filter 9 that selectively transmits the globe light. This globe light is made into intermittent light by a chopper 11, and the globe light incident on the photodetector 10 is detected with high sensitivity by a lock-in amplifier 12. The output of this lock-in amplifier 12 is transmitted to the excitation laser light source 1 via the controller 10-13, and when the probe light is no longer detected by the photodetector 1°, the oscillation of the excitation laser light source 1 is stopped. make it work.

In this embodiment, the excitation laser light source 1 uses a wavelength of 483, which has strong absorption in the bisbenzene molybdenum metal complex.
mm argon laser (output 100 mw) is used, and as the glove laser light source 2, A7GaAs, which has weak absorption of metal complexes and is relatively transparent, oscillates in the near-infrared region.
Or a semiconductor laser such as InGaAsP is used. Further, the filter 9 is a narrowband filter that selectively transmits only the globe light.

This strong excitation light from the excitation laser light source 1 is applied to the solution cell 6.
When the laser beam enters the laser beam, the metal complex strongly absorbs it, so that the metal is liberated from the metal complex, and this liberated metal is locally deposited on the laser beam irradiation area on the sample substrate 5. Since this metal is opaque, if it is deposited sufficiently thickly on the sample substrate 5, the globe light will not pass through it.
When the excitation light is no longer detected, it can be reliably determined that the excitation light irradiation can be stopped. This makes it possible to avoid unnecessary irradiation of laser excitation light onto mold for a long time, and conversely, it is also possible to avoid cases where the irradiation time of excitation light is too short and leaves one pinhole defect.

In this example, bisbenzene molybdenum, which can liberate the metal with low excitation input, was used as the gold a complex, and metal complexes such as bisbenzene chromium and manganese ammine complex salts were added as necessary. Can be used.

Further, the components used in this embodiment can be replaced without departing from the spirit of the present invention. For example, in this embodiment, the driving device 8 is used to position the irradiation on the sample substrate 5. Although the cell 6 is driven, a new laser beam scanning optical system may be provided instead, and the laser beam may be used for scanning.

[Brief explanation of drawings]

The figure is a block diagram showing a schematic configuration of an embodiment of the present invention. In the figure,

Claims (1)

[Claims] An excitation laser light source, a condensing optical system that condenses excitation light from the excitation laser light source, and a metal complex solution cell into which the condensed excitation light enters through a sample substrate used as a window material. a laser metal deposition apparatus for liberating metal from the metal complex by the incident light and depositing the metal at a desired position on the sample substrate; A laser light source, beam synthesis a) in which the globe light from the probe laser light source is superimposed in parallel with the excitation light and made to enter the solution cell, and the probe light transmitted through the sample substrate is combined with the probe light incident on the sample substrate. A laser metal deposition apparatus comprising: a photodetector that detects the metal complex solution by interposing the metal complex solution behind the metal complex solution.