JP3991266B2 - Semiconductor circuit evaluation method and evaluation apparatus therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor circuit evaluation method for evaluating the influence of particulate contamination on a semiconductor circuit formed on a semiconductor substrate, and an evaluation apparatus therefor.
[0002]
[Prior art]
A technique for removing fine particles using chemical cleaning, laser cleaning, or the like when fine particles adhere as contaminants on a semiconductor substrate on which a semiconductor circuit is formed has been generally performed.
[0003]
In addition, the state of contamination of fine particles has been evaluated. For example, a method of measuring the number concentration and particle size distribution of fine particles in exhaust from a semiconductor manufacturing apparatus (Non-patent Document 1, Patent Document 1, etc.), or detecting fine particles of 100 nm or more adhering to the surface of a semiconductor substrate. There is a method (Non-Patent Document 2, etc.).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-297582 [Non-Patent Document 1]
Michael G. Simmonds, Wayne l. Gladfelter, Nagaraja Rao, Wladyslaw W. Szymanski, Kang-ho Ahn, Peter H. McMurry, J. Vac. Sci. Technol. A 9 (5) (1991) 2782
[Non-Patent Document 2]
T. Seto, K. Okuyama, Y. Inoue, S. Yokoyama, S. Kurose, M. Hirose, T. Fujii, Rev. Sci. Instrum 66 (11) (1995) 5348
[0005]
[Problems to be solved by the invention]
Conventionally, after grasping the state of contamination of fine particles, emphasis has been placed on how to prevent the fine particles from adhering to the semiconductor substrate, and time and cost have been spent on research and development of space cleaning technology.
In order to reduce the malfunction of semiconductor circuits due to fine particles and improve yield, we analyze and evaluate how the size (particle size), chemical composition, number concentration, etc. of the fine particles that cause contamination affect semiconductor circuits. It is also important to do. However, the current situation is that this point has not been evaluated.
[0006]
In particular, in recent years, the width of wiring has become narrower as the degree of integration of semiconductor circuits has improved, and it is considered that the adhesion of nano-order fine particles that are difficult to remove by conventional methods cannot be ignored. For example, the pattern size of the current DRAM (Dynamic Random Access Memory) is about 0.13 μm, and particles having a particle size of 1/10 or more of the size, that is, particles having a size of about 10 nm or more affect the characteristics of the semiconductor circuit. It is expected to be. Furthermore, since the pattern size becomes smaller as the DRAM capacity increases, the size of the fine particles to be removed is expected to become smaller in the future. Therefore, it is important to evaluate how the particle size, the number concentration, etc. of the fine particles influence the semiconductor circuit that is increasingly miniaturized.
[0007]
The present invention has been made in view of the above-described problems, and an object thereof is to provide a semiconductor circuit evaluation method and an evaluation apparatus for evaluating how a semiconductor circuit is affected by various characteristics of fine particles. It is in.
[0008]
[Means for Solving the Problems]
The semiconductor circuit evaluation method of the present invention generates fine particles of known chemical components that can occur in a semiconductor manufacturing process, aligns the particle size of the fine particles, and adheres a certain amount to the semiconductor substrate, and then the semiconductor. It is characterized by conducting an electrical test on a semiconductor circuit formed on a substrate.
[0009]
The semiconductor circuit evaluation apparatus according to the present invention includes a fine particle generation chamber in which a fine particle generation source is disposed, a heating unit for evaporating the fine particle generation source to generate fine particles, and a fine particle adhesion chamber in which a semiconductor substrate is disposed. A transport pipe for transporting the fine particles generated in the fine particle generation chamber to the fine particle adhesion chamber and spraying them onto the semiconductor substrate; a characteristic control means for controlling the characteristics of the fine particles provided in the middle of the transport pipe; And an inspection device for performing an electrical test of the semiconductor circuit on the semiconductor substrate.
[0010]
The semiconductor circuit evaluation apparatus according to the present invention includes a fine particle generation chamber in which a fine particle generation source is disposed, a heating unit for evaporating the fine particle generation source to generate fine particles, and a fine particle adhesion chamber in which a semiconductor substrate is disposed. And a transport pipe for transporting the fine particles generated in the fine particle generation chamber to the fine particle adhesion chamber and spraying them onto the semiconductor substrate, a characteristic detecting means provided in the middle of the transport pipe for detecting the characteristics of the fine particles, and the fine particles adhered And an inspection device for performing an electrical test of the semiconductor circuit on the semiconductor substrate.
[0011]
That is, according to the present invention, an electrical test of a semiconductor circuit is performed after a predetermined amount of fine particles having a known chemical composition, for example, having a known chemical composition and having a desired particle size are deposited on a semiconductor substrate. Examples of characteristic control means for controlling the characteristics of fine particles include a differential mobility analyzer (DMA) (EOKnuson and KTWhitby, J. Aerosol Sci. 6 (1975) 443.). . After classifying the particle diameter of the fine particles with this classifier, only fine particles having a desired particle diameter are sprayed onto the semiconductor substrate.
Examples of the means for detecting the characteristics of the fine particles include a concentration detector for detecting the number concentration of the fine particles.
The chemical components of the fine particles are determined by the material of the fine particle generation source, the pressure in the fine particle generation chamber atmosphere, the components of the atmospheric gas, and the like.
The amount of fine particles attached to the semiconductor substrate is determined by the number concentration of fine particles, the spraying time, the spraying speed, and the like.
In this way, the relationship between the characteristics of the fine particles and the operating condition of the semiconductor circuit can be obtained by attaching the fine particles whose characteristics are known to the semiconductor substrate and then conducting an electrical test of the semiconductor circuit. It becomes possible to detect problems in the semiconductor manufacturing process.
[0012]
Examples of the chemical component of the fine particles include metals, ceramics, and organic substances.
Examples of metals include Cu, Fe, Ni, Zn, Cr, W, Al, and In.
Examples of ceramics include oxides and nitrides of the above metals.
Examples of the organic matter include breath from an operator, sweat, and oil.
Other examples include Na, K, Ca, B, and dust, Si oxide, Si nitride, Ti, Ti nitride, Ta, and the like generated in the semiconductor manufacturing process.
Furthermore, the composite of what was mentioned above is mentioned.
[0013]
Further, when a crucible is used as a heating means for the fine particle generation source, for example, there are problems such as reaction with the crucible and contamination from the crucible. In addition, for high melting point substances, there is a problem that it is difficult to produce fine particles because there is no suitable crucible material. Further, when resistance heating or arc heating is used, degassing from the chamber wall or contamination from the electrodes is likely to occur. In addition, these methods have problems from the viewpoint of controlling the characteristics of the fine particles, such as the wide particle size and particle size distribution of the fine particles.
Considering the above points, a laser ablation method is preferable as a method for producing fine particles.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 is a schematic diagram showing an overall configuration of a semiconductor circuit evaluation apparatus 1 according to an embodiment of the present invention. The evaluation apparatus 1 includes a so-called gas deposition apparatus including a particle generation chamber 2, a particle adhesion chamber 3, a transfer pipe 10, and the like, a characteristic control unit 11 that controls the characteristics of the particles, and a characteristic detection unit 14 that detects the characteristics of the particles. And an inspection apparatus 20 that performs an electrical test on the semiconductor circuit to which the fine particles are attached.
[0016]
In the fine particle generation chamber 2, for example, a target 4 made of a metal material is held by a target holder 5 as a fine particle generation source. The target 4 has a disk shape with a diameter of 50 mm and a thickness of 3 mm, for example. The target holder 5 is connected to the rotating shaft 6a of the motor 6 and is rotatable.
[0017]
The fine particle generation chamber 2 is connected to an exhaust system 22 and can be evacuated through the exhaust system 22. Further, a fine particle production gas introduction system 21 is connected, and through this fine particle production gas introduction system 21, an inert gas such as He, for example, or a reactive gas when the target 4 is a ceramic material, is introduced into the fine particle production chamber 2. Is introduced.
[0018]
A laser oscillator 24 that is a heating unit for the target 4 is disposed outside the fine particle generation chamber 2. Laser light emitted from the laser oscillator 24 is transmitted from a laser light introduction window 9 attached to the fine particle generation chamber 2 through a mirror 7 and a condenser lens 8 which are also arranged outside the fine particle generation chamber 2. 4 is condensed. The condensing lens 8 is movable in the optical axis direction, and by moving the condensing lens 8, the power density of the laser light can be changed, and the difference in evaporation temperature of the target material can be dealt with. Further, by rotating the target 4 together with the target holder 5 by the motor 6, the surface of the target 4 can be uniformly heated and evaporated.
[0019]
In the fine particle adhesion chamber 3, a semiconductor substrate 17 on which a semiconductor circuit is formed is supported on a stage 18. In the fine particle adhesion chamber 3, a slit plate 16 in which slits 16 are formed is disposed above the semiconductor substrate 17. The slit plate 16 functions as a mask that limits the adhesion range of the fine particles blown out from the nozzle 15 that is a fine particle blowing port onto the semiconductor substrate 17. The particulate adhesion chamber 3 is connected to an exhaust system 23, and vacuum exhaust is possible through the exhaust system 23.
[0020]
One end of the transfer tube 10 is inserted into the particle generation chamber 2, while the other end to which the nozzle 15 is attached is inserted into the particle adhesion chamber 3. The nozzle 15 is located on the slit 16a.
[0021]
In the middle of the transport pipe 10, a classifier 11 that is a particle characteristic control unit and a concentration detector 14 that is a particle characteristic detection unit are interposed. A valve 12 is provided between the classifier 11 and the nozzle 15, and a branch pipe 19 is branched from between the valve 12 and the classifier 11, and concentration detection is performed on the branch pipe 19 via the valve 13. A device 14 is connected. Further, a charger unit 25 for charging fine particles introduced into the classification device 11 is provided in front of the classification device 11 (on the fine particle generation chamber 2 side).
[0022]
The classification device 11 is a device that classifies fine particles having a particle size distribution according to a difference in electric mobility (the movement speed of fine particles per unit electric field) and takes out the particles as particles having a uniform particle size. As shown in FIG. 2, the classification device 11 has a double cylindrical structure of an outer cylinder 31 and an inner cylinder 32 to which a voltage is applied, and fine particles charged by radiation or the like in advance in the charger unit 25 are Introduced from a slit 31 a formed in the outer cylinder 31.
[0023]
A sheath gas is introduced from the slit 31b formed in the upper part of the outer cylinder 31, passes through the filter 33, and forms a flow exhausted from an exhaust port 31c formed in the lower part of the outer cylinder 31. The fine particles are transported by the balance between the velocity of the sheath gas flow in the vertical direction and the moving velocity of the fine particles due to the electrostatic force in the horizontal direction, and only the fine particles having a specific particle diameter are taken out from the slit 32 a formed in the inner cylinder 32. By controlling the voltage applied to the inner cylinder 32, the particle size of the classified fine particles is determined.
[0024]
The classified fine particles are introduced into the concentration detector 14, and the number concentration of the fine particles is detected. The concentration detector is, for example, a Faraday cup ammeter, and detects charged fine particles as an electric current.
[0025]
Next, the generation of fine particles in the fine particle generation chamber 2 and the action of attaching the generated fine particles to the semiconductor substrate 17 will be described.
[0026]
First, after reducing the pressure inside the particle generation chamber 2 and the particle adhesion chamber 3 to a predetermined pressure, the vacuum exhaust of the particle generation chamber 2 is stopped and, for example, high-purity He gas is introduced into the particle generation chamber 2 to near atmospheric pressure. To do. The inside of the fine particle adhesion chamber 3 is continuously evacuated. As a result, a gas flow is formed from the particle generation chamber 2 to the particle adhesion chamber 3 via the transfer pipe 10, the classifier 11, and the open valve 12.
[0027]
Next, fine particles are generated by a laser ablation method. When the target 4 is irradiated with laser light, the material constituting the target 4 evaporates. At this time, since the atmosphere (He gas) in the fine particle generation chamber 2 is normal temperature, the vapor is rapidly cooled to generate nano-order fine particles.
[0028]
The generated fine particles flow in the transport pipe 10 on the gas flow of He gas, are charged by the charger unit 25, and then are classified into fine particles having a desired particle diameter in the classifier 11, and pass through the valve 12. Then, it blows out from the nozzle 15. The blown out fine particles are blown and adhered to desired positions on the semiconductor substrate 17 through the slits 16a. Further, the stage 18 that supports the semiconductor substrate 17 is movable in a three-dimensional direction. By moving the stage 18, fine particles having a desired particle diameter are attached to any location on the semiconductor substrate 17. be able to.
[0029]
Detection of the number concentration of the fine particles can be performed by conveying the classified fine particles to the concentration detector 14 by closing the valve 12 and opening the valve 13 before spraying the fine particles onto the semiconductor substrate 17. . Alternatively, both the valves 12 and 13 may be opened, and the number concentration may be detected simultaneously with the spraying onto the semiconductor substrate 17.
[0030]
FIG. 3 is a transmission electron microscope image of tungsten fine particles classified to a particle size of, for example, 10 nm by the classifier 11, and FIG. 4 is a graph showing the particle size distribution in which the particle size was actually measured from this image. It is. From these results, it can be seen that fine particles having an average particle diameter of 9.8 nm and a geometric standard deviation of 1.2 or less and having a very uniform particle diameter are obtained. The geometric standard deviation of 1.2 or less means that more than half of the fine particles are included in a particle size range within about ± 12.5% of the average particle size.
[0031]
FIG. 5 is a concentration distribution of, for example, gold fine particles obtained by measuring the number concentration with the concentration detector 14. This figure shows the change in the concentration distribution of the gold fine particles due to the pressure in the fine particle generation chamber 2.
[0032]
As described above, the concentration, particle size, and chemical composition of the fine particles attached to the semiconductor substrate 17 as a contamination source are known. Then, the semiconductor substrate 17 to which fine particles with known characteristics are attached is transferred to the inspection apparatus 20 (see FIG. 1), and an electrical test (operation test) of the semiconductor circuit formed on the semiconductor substrate 17 is performed. By performing the above, the relationship between the various characteristics of the fine particles and the quality of the operation of the semiconductor circuit is obtained. Based on this, it is possible to evaluate the influence on the semiconductor circuit of the particle size, chemical composition, and number concentration of the fine particles as the contamination source.
[0033]
The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.
[0034]
Two laser oscillators, a generation laser and an assist laser, may be used. That is, since a refractory metal or the like is difficult to evaporate, the temperature of the target surface is first raised with an assisting laser in order to efficiently generate fine particles, and further, only the surface layer is evaporated by irradiating the generating laser.
Of course, a high-frequency melting furnace, an arc furnace, or the like may be used as the fine particle generation source in addition to the laser.
[0035]
As the classification device, a device using Brownian motion, centrifugal force, inertial force, or the like may be used other than those described in the above embodiment.
[0036]
In addition, both the particle diameter and the number concentration of the fine particles are not limited to known, and only one of them may be known.
[0037]
【The invention's effect】
As described above, according to the present invention, fine particles having known characteristics are attached to a semiconductor substrate as a contamination source, and then the semiconductor circuit formed on the semiconductor substrate is evaluated. It can be seen whether the semiconductor circuit malfunctions or is not affected at such times. If this result is returned to an actual semiconductor manufacturing process, it is possible to improve production efficiency and yield.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of a semiconductor circuit evaluation apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of the classification device shown in FIG.
FIG. 3 is a TEM image obtained as a result of classification so that fine particles have a particle diameter of 10 nm.
4 is a graph showing a particle size distribution obtained by actually measuring the particle size from the TEM image shown in FIG. 3. FIG.
FIG. 5 is a graph showing the pressure dependence of the concentration distribution of fine particles measured for number concentration by a concentration detector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor circuit evaluation apparatus, 2 ... Fine particle production | generation chamber, 3 ... Fine particle adhesion chamber, 4 ... Fine particle production | generation source, 10 ... Conveyance pipe, 11 ... Classification apparatus, 14 ... Concentration detector, 15 ... Nozzle, 16a ... Slit, 17 ... Semiconductor substrate, 20 ... Inspection device, 24 ... Laser oscillator.

Claims (7)

After producing fine particles of known chemical components that can occur in the semiconductor manufacturing process, aligning the particle size of the fine particles, and attaching a certain amount to the semiconductor substrate, the electrical circuit of the semiconductor circuit formed on the semiconductor substrate A method for evaluating a semiconductor circuit, comprising performing a test. The semiconductor circuit evaluation method according to claim 1, wherein the fine particles are generated by a laser ablation method. A particle generation chamber in which a particle generation source is disposed;
Heating means for evaporating the fine particle production source to produce fine particles;
A particulate adhesion chamber in which a semiconductor substrate is disposed;
A transport pipe for transporting the fine particles generated in the fine particle generation chamber to the fine particle adhesion chamber and blowing the fine particles to the semiconductor substrate;
A characteristic control means for controlling the characteristics of the fine particles, provided in the middle of the transport pipe;
An inspection device for a semiconductor circuit, comprising: an inspection device for performing an electrical test on a semiconductor circuit on the semiconductor substrate to which the fine particles are attached. A particle generation chamber in which a particle generation source is disposed;
Heating means for evaporating the fine particle production source to produce fine particles;
A particulate adhesion chamber in which a semiconductor substrate is disposed;
A transport pipe for transporting the fine particles generated in the fine particle generation chamber to the fine particle adhesion chamber and blowing the fine particles to the semiconductor substrate;
A characteristic detecting means provided in the middle of the conveying pipe for detecting the characteristics of the fine particles;
An inspection device for a semiconductor circuit, comprising: an inspection device for performing an electrical test on a semiconductor circuit on the semiconductor substrate to which the fine particles are attached. 5. The semiconductor circuit evaluation apparatus according to claim 3, wherein the heating unit is a laser oscillator. 6. A stage, which is movable with respect to the particle outlet of the transfer pipe, is provided in the particle adhesion chamber, and the semiconductor substrate is supported on the stage. The evaluation apparatus of the semiconductor circuit in any one of. The apparatus for evaluating a semiconductor circuit according to claim 6, wherein a mask is provided between the fine particle outlet and the semiconductor substrate to limit a range in which the fine particles adhere to the semiconductor substrate.

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