JP2002048724A - Organic particle monitoring device for semiconductor wafer in vacuum vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic particle monitoring device for a semiconductor wafer in a vacuum vessel capable of measuring the type, the grain size and the like of organic particles sticking to the wafer surface under a vacuum atmosphere by an in-situ method. SOLUTION: This organic particle monitoring device for a semiconductor wafer in the vacuum vessel is provide with a first optical system 12 and a second optical system 14 guiding a laser beam 11A to the wafer 1, a quartz window 10A arranged in the vacuum vessel 10, an optical detector 17 detecting fluorescence 20 emitted from the organic particle 6 by irradiation of the organic particle 6 with the laser beam 11A, and a third optical system 16 guiding the fluorescence 20 permeated through the quartz window 10A and the second optical system 14 to the optical detector 17. Based on the fluorescence 20 detected by the optical detector 17, at least the grain size, the number of particles, or the sort of the organic particle 6 is detected under a vacuum atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic particle monitor for semiconductor wafers in a vacuum vessel,
The present invention relates to a novel improvement for enabling organic particles on a wafer surface to be monitored by an in-situ method in a vacuum process (a film forming process such as CVD and etching) of a semiconductor wafer.

[0002]

2. Description of the Related Art An example of this type of apparatus conventionally used is an organic particle monitor apparatus shown in FIG. That is, in FIG. 2, what is indicated by reference numeral 1 is a wafer as an inspection object, and a laser beam 2 oscillated from a laser light source (not shown) is reflected and scattered on the surface of the wafer 1. The Mie scattered light 3 generated in this way is reflected by the integrating sphere 4, collected, and detected by the photodetector 5.

That is, in the conventional organic particle monitor, the Mie scattered light 3 is irradiated by irradiating the laser beam 2 to the organic particles 6 attached to the surface of the wafer 1.
The Mie scattered light 3 is condensed by the integrating sphere 4 and captured by the photodetector 5 to detect the particle size and defect size of the organic particles 6 attached to the surface of the wafer 1.

[0004] The organic particles 6 referred to here are mainly the wafers 1 before the wafers 1 are loaded into a vacuum vessel.
Means particles that have adhered to the surface of, for example, dust in the air, oil from the human body, and any and all kinds of adhesives that adhere to wallpaper. Is composed of organic matter.

Conventionally, in a semiconductor manufacturing process performed in a vacuum atmosphere by a CVD apparatus or the like, a particle monitor apparatus configured to measure in the atmosphere is used to measure the organic particles 6 attached to the surface of the wafer 1. Therefore, every time the organic particles 6 attached to the surface of the wafer 1 are measured, the vacuum is released from the CVD apparatus or the like, the wafer 1 is taken out of a vacuum container (not shown), and the wafer 1 is placed in the particle monitor. Transfer to organic particles 6
Was measured, and after the measurement, the wafer 1 was inserted again into the vacuum container, and the process was shifted to the next manufacturing process.

[0006]

Since the conventional organic particle monitor device is configured as described above, there are the following problems. That is, when the wafer 1 is transferred to the outside of the vacuum vessel to detect the particle size of the organic particles 6 as described above, the wafer 1 is exposed to the atmosphere. There are problems that the organic particles 6 and the like in the inside adhere and the surface of the wafer 1 is oxidized.

In the conventional optical measurement of the organic particles 6 that capture the Mie scattered light 3, the organic particles 6
Particle diameter and complex refractive index, the refractive index and thickness of the natural oxide film on the surface of the wafer 1, the surface reflectance of the wafer 1, the wavelength of irradiation light,
Since various conditions such as the incident angle and polarization, the solid angle of the light condensed by the photodetector 5 and the direction of the observation point, and the contrast of interference are complicatedly intertwined, the intensity of the Mie scattered light 3 cannot be simply expressed. .

Further, in order to increase the intensity of the Mie scattered light 3, it is necessary to converge the laser beam 2 to increase the energy density. However, since the diameter of the laser beam 2 is inversely proportional to the number of beam scans, if the diameter of the laser beam 2 is reduced to increase the number of beam scans,
There is a problem that the scanning time increases and the throughput of the measurement and inspection of the organic particles 6 decreases. As described above, in the conventional organic particle monitor, the wafer 1
Although the particle size of the organic particles 6 attached to the surface and the location of the attachment can be determined, it is difficult to determine the type of the attached organic particles 6 and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In particular, the present invention has been made without exposing a wafer to be detected to the atmosphere, and furthermore, the type and particle size of organic particles attached to the wafer surface. It is an object of the present invention to provide an organic particle monitoring device for a semiconductor wafer in a vacuum vessel capable of detecting a diameter, a defect size, and the like.

[0010]

According to the present invention, there is provided an organic particle monitoring apparatus for a semiconductor wafer in a vacuum vessel, which irradiates a laser beam oscillated from a laser oscillator onto a wafer installed in a vacuum vessel of a semiconductor manufacturing apparatus. Thereby, in an organic particle monitoring device for a semiconductor wafer in a vacuum vessel for measuring organic particles attached to the surface of the wafer, a first optical system and a second optical system for guiding the laser beam to the wafer, In order to guide the laser beam transmitted through the second optical system to the wafer disposed in the vacuum container, the laser beam is irradiated on the quartz window provided in the vacuum container and the organic particles. An optical detector for detecting fluorescence emitted from the organic particles,
A third optical system for guiding the fluorescence emitted from the organic particles and transmitted through the quartz window and the second optical system to the optical detector, wherein the fluorescence detected by the optical detector is And detecting at least the particle size, the number, or the type of the organic particles in a vacuum atmosphere. The wafer is disposed on an optical path connecting the first optical system and the second optical system. It is a configuration provided with a reflection mirror for guiding the fluorescence coming from the side to the optical detector, and is provided so as to penetrate the center of the second optical system and the reflection mirror,
It is configured to include a light-shielding pipe having a light-shielding property in a direction other than the traveling direction of the laser beam and the fluorescence, and the light-shielding pipe can vertically irradiate the laser beam to the surface of the wafer. As described above, the configuration is provided perpendicular to the surface of the wafer,
Further, the laser oscillator is a He-Cd laser oscillator, and the optical detector is configured to include an image intensifier and a CCD camera.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The same or equivalent parts as those of the conventional device are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, in the organic particle monitoring apparatus for a semiconductor wafer in a vacuum vessel according to the present invention, a wafer 1 to be inspected is set in a vacuum vessel 10 of a semiconductor manufacturing apparatus. Is irradiated with a laser beam 11A oscillated from a He—Cd laser oscillator 11. The wavelength of the laser beam 11A is 325 nm, and the laser beam 11A is vertically irradiated on the wafer 1 placed in a vacuum atmosphere through the first optical system 12 and the light shielding pipe 13, and further through the quartz window 10A provided in the vacuum vessel 10.

The first optical system 12 includes a 325 nm band-pass filter 12 A, a polarizing plate 12 B, a １ ／ wavelength plate 12
C, a reflection mirror 12D, a first laser lens 12E, and a second laser lens 12F. Further, the light-shielding pipe 13 penetrates all the centers of the first to third lenses and the 325 nm cut filter included in the second optical system 14 to be described later, and the laser beam 11A passing through the inside of the The laser beam 11A is disposed so as to be irradiated perpendicularly to the surface, and does not transmit the laser beam 11A in the transverse direction with respect to the traveling direction of the laser beam 11A (ie, has a light shielding property in the transverse direction). And so on). The second optical system 14 is 325
An nm cut filter 14A, a first lens 14B, a second lens 14C, and a third lens 14D are provided. Note that 32
The 5 nm cut filter 14A has a wavelength of about 325 nm.
Is a filter that blocks light without transmitting the light.

The first optical system 12 and the second optical system 1
4, a reflection mirror 15 is provided, and light (which will be described later, which is actually a photon) coming from the wafer 1 side is reflected by the reflection mirror 15 and travels in a direction in which the light travels. A third optical system 16 and an optical detector 17 are provided. An arithmetic processing unit 18 is connected to the CCD camera 17B. The arithmetic processing unit 18 includes a photon counting image processor, a personal computer, a monitor, and the like for arithmetically processing the intensity of the received photons. Further, the third optical system 16 includes a high-pass filter 16A.
And a 325 nm cut filter 16B. The optical detector 17 includes an image intensifier 17A and a CCD camera 17B.

As the high-pass filter 16A, a plurality of types having different transmission bands are used. For example, about ten high-pass filters 16A are used from transmission wavelengths of 340 nm or more to transmission wavelengths of 600 nm or more. In the actual measurement, the high-pass filter 16A is sequentially replaced with the one having the shorter transmission wavelength, and only the light having each transmission wavelength or more is transmitted, and the image intensifier 1A is transmitted.
By making the light incident on 7A or the like, the excited species can be specified. The specifying method will be described later.

If a plurality of types of high-pass filters 16A having different transmission bands are formed as rotary cut filters, the high-pass filters 16A can be easily replaced. The reason for setting the shortest transmission wavelength to 340 nm corresponds to the fact that the wavelength of the laser beam 11A is 325 nm, and it is thought that the fluorescence of 340 nm or less is buried in the reflected light of the laser beam 11A and cannot be observed. Because it is

The structure of the 325 nm cut filter 16B is the same as that of the 325 nm cut filter 14A included in the second optical system 14. The image intensifier 17A has a f105 mm UV
Equipped with a lens. The first optical system 12 to the optical detector 17 are housed in a housing 19 having a light-shielding property.

Next, the operation will be described. The first optical system 12, the second optical system 14, and the quartz window 1 as described above
When the wafer 1 is irradiated with the laser beam 11A through the laser beam 0A, the organic particles 6 attached to the surface of the wafer 1
Are excited by the laser beam 11A, and fluorescence 20 (substantially photons) unique to the molecule is emitted.

The fluorescent light 20 reaches the second optical system 14 through the quartz window 10A, and first enters the 325 nm cut filter 14A. At this time, light having a wavelength of 325 nm (that is, reflected light of the laser beam 11A) arriving together with the fluorescent light 20 is blocked, and the fluorescent light 20 having a wavelength other than 325 nm is blocked.
Pass through the first to third lenses 14B to 14D and reach the reflection mirror 15. The fluorescent light 20 passes through a portion of the second optical system 14 other than the light-shielding pipe 13 and reaches the reflecting mirror 15.

Further, the fluorescent light 2 reflected by the reflection mirror 15
0 is split when transmitting through the high-pass filter 16A of the third optical system 16, and the transmission wavelength is 340 to 340 as described above.
The light passes through a 600 nm high-pass filter 16A. Here, for example, 340 nm high-pass filters 16A and 3A
When the wavelength of the fluorescent light 20 is 360 nm in the case where the high-pass filter 16A of 80 nm is used, 3
When the 40 nm high-pass filter 16A is used, the fluorescence 20 is transmitted and can be observed.
When the high-pass filter 16A of the
Can not be observed because it cannot be transmitted. In this way, the type of the organic particles 6 can be specified by replacing the high-pass filters 16A having different transmission wavelengths sequentially, narrowing down the wavelength of the fluorescent light 20 and specifying the excitation type. Can be.

The fluorescent light 20 transmitted through the high-pass filter 16A further transmits through the 325 nm cut filter 16B. Thus, 325 nm immediately above the quartz window 10A
The reason why the 325 nm cut filter is provided immediately before the image intensifier 17A in addition to the cut filter 14A is that the laser beam 11A irradiating the wafer 1 and the reflected light from each optical system and the like are used for the image intensifier 17A.
This is for surely preventing the light from being incident on A.

Since the fluorescence 20 reaching the image intensifier 17A is very weak light in this way, it is amplified by the image intensifier 17A before being incident on the CCD camera 17B. CCD camera 17B
Is processed by the arithmetic processing unit 18, the components of the organic particles 6 are analyzed, and the particle size of the organic particles 6 is specified based on the light intensity. The organic particles 6 based on the light intensity
For example, the relationship between the fluorescence intensity and the particle size is determined in advance using a sample in which a phosphor-containing polystyrene latex (PSL) is adhered to the wafer 1, and the CC size is actually determined.
This can be performed by applying the intensity of the fluorescence 20 detected by the D camera 17B to the above-described relationship, and the intensity of the actually detected fluorescence is determined by the relationship actually obtained using the wafer 1 to which the organic particles 6 are attached. The particle size may be determined by applying the values. In fact, it has been confirmed that the organic particle monitor for semiconductor wafers in the vacuum vessel of the present invention can detect a fluorescent material-containing polystyrene latex having a particle size of 0.071 μm in about 5 to 30 minutes.

As described above, according to the organic particle monitoring apparatus for semiconductor wafers in a vacuum vessel of the present invention, the surface of the wafer 1 can be placed on the surface of the wafer 1 without breaking the vacuum of the vacuum vessel 10 and taking out the wafer 1 to the atmosphere as in the prior art. The kind, number of particles, particle size, defect size, and the like of the attached organic particles 6 can be measured by a so-called in-situ method under a vacuum atmosphere. In particular, although the type of particles cannot be determined by the conventional method of capturing the Mie scattered light, the apparatus of the present invention can perform the determination with high accuracy and by the in-situ method.

Further, in order to measure the fluorescence 20 emitted from the excited species, a high-sensitivity camera (image intensifier) is used. The organic particles 6 can be measured. Since organic particles can be measured with high accuracy and easily in this way, there has been a problem in shortening the processing time and the number of steps in the semiconductor manufacturing process, and further exposing the wafer 1 to the atmosphere for conventional measurement. Secondary contamination (for example, oxidation of the surface) of the wafer 1 can be prevented.

In order to increase the irradiation density of the laser beam 11A, a 325 nm cut filter 14A,
First lens 14B, second lens 14C, third lens 14
A hole is formed in the center of the mirror D and the reflection mirror 15 so that the laser beam 11A is irradiated perpendicularly to the surface of the wafer 1. Therefore, the laser beam 11A adheres to the wafer 1 without increasing the irradiation energy of the laser beam 11A more than necessary. The molecules constituting the organic particles 6 are easily excited, and the fluorescence 20 can be observed reliably.

In order to excite the organic particles 6 on the surface of the wafer 1 and obtain the fluorescent light 20, it is necessary to apply high-density energy. Therefore, in the above description, the He-Cd laser oscillator 11 having a short irradiation wavelength is used. Is described, but if the device can oscillate a laser beam (ultraviolet laser) having a short wavelength and high energy,
Oscillator other than He-Cd laser oscillator can be applied to the present invention. However, a laser oscillator that does not damage the wafer 1 is required. The configuration shown as the first optical system, the second optical system, and the third optical system is merely an example. The first optical system is a laser wavelength polarization adjusting system and a laser beam diameter adjusting system, and the second optical system is The laser beam irradiation diameter adjustment system on the wafer and the fluorescence diameter adjustment system. The third optical system is an optical system that separates the fluorescence from the laser beam and an optical system that adjusts the fluorescence to the light receiving diameter of the optical detector. These optical systems may be other optical systems.

[0027]

According to the first aspect of the present invention, the state of the wafer surface can be easily and accurately measured by a so-called in-situ method in a vacuum atmosphere, and without opening the vacuum container to the atmosphere. Since the measurement can be performed, the processing time and the number of steps in the semiconductor manufacturing process can be reduced, and further, the secondary contamination of the wafer can be prevented. Also,
According to the second aspect of the present invention, the fluorescence emitted from the organic particles can be reliably guided to the optical detector. According to the third aspect of the present invention, the organic particles can be efficiently irradiated with the laser beam, and the fluorescence emitted from the organic particles can be efficiently guided to the optical detector. Further, according to the fourth aspect of the present invention, the organic particles can be efficiently irradiated with the laser beam without increasing the output of the laser beam itself. According to the fifth aspect of the present invention, it is possible to irradiate a laser beam having a sufficient energy intensity and to configure the entire apparatus at a relatively low cost.
Further, according to the invention of claim 6, it is possible to detect even a fluorescent signal having a weak signal level, and in combination with a servo control positioning device, it is possible to discriminate the type of organic particles from an organic semiconductor wafer in a vacuum vessel. A particle monitor device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an organic particle monitoring device for a semiconductor wafer in a vacuum vessel according to the present invention.

FIG. 2 is a configuration diagram schematically showing a main part of a conventional organic particle monitor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 6 Organic particle 10 Vacuum container 10A Quartz window 11 Laser oscillator 11A Laser beam 12 First optical system 12A Bandpass filter 12B Polarizer 12C Quarter-wave plate 12D Reflection mirror 12E First laser lens 12F Second laser lens 13 Light shielding Pipe 14 Second optical system 14A 325 nm cut filter 14B First lens 14C Second lens 14D Third lens 15 Reflector mirror 16 Third optical system 16A High pass filter 16B Cut filter 17 Optical detector 17A Image intensifier 17B CCD camera 18 Operation Processing unit 19 Housing 20 Fluorescence

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsumi Takami 1-1-25 Tsujido West Coast, Fujisawa-shi, Kanagawa Shonan Institute of Technology Faculty of Engineering Department of Mechanical Engineering (72) Inventor Takafumi Matsunaga 1-1-2 Yurakucho, Chiyoda-ku, Tokyo No. 1 Inside the Japan Steel Works, Ltd. (72) Inventor Yasumasa Kaneda 1-2-1, Yurakucho, Chiyoda-ku, Tokyo 1-21-2 Inside the Japan Steel Works, Ltd. (72) Inventor Masashi Tamae 1-chome, Funakoshi Minami, Hiroshima, Hiroshima No. 1 Inside Nippon Steel Design Co., Ltd. (72) Inventor Hiroshige Shinohara 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Inside Nippon Steel Design Co., Ltd. 1-6-1 Echinan, Nippon Steel Design Co., Ltd. (72) Shinji Susada, Inventor 1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima F Terms (reference) 2G043 AA06 BA14 CA05 DA08 EA01 GA08 GB07 HA01 HA02 HA04 HA07 HA08 HA15 JA02 JA03 KA03 KA05 KA09 LA03 2G051 AA51 AB01 AB07 BA05 BA10 BB07 CA01 CA04 CB01 CB05 CB10 CC07 CC09 CC11

Claims (6)

[Claims] A laser beam (11A) oscillated from a laser oscillator (11) irradiates a wafer (1) installed in a vacuum vessel (10) of a semiconductor manufacturing apparatus, whereby the wafer (1) is irradiated. In an organic particle monitor for a semiconductor wafer in a vacuum vessel for measuring organic particles (6) attached to a surface, a first optical system (12) for guiding the laser beam (11A) to the wafer (1) And the second optical system (14), to guide the laser beam (11A) transmitted through the second optical system (14) to the wafer (1) disposed in the vacuum vessel (10), A quartz window (10 provided in the vacuum vessel (10)
A), an optical detector (17) for detecting fluorescence (20) emitted from the organic particles (6) by irradiating the laser beam (11A) to the organic particles (6), Fluorescence (20) emitted from the organic particles (6) and further transmitted through the quartz window (10A) and the second optical system (14)
Optical system (16) for guiding the light to the optical detector (17)
The fluorescence (2) detected by the optical detector (17)
An organic particle monitoring device for a semiconductor wafer in a vacuum vessel, wherein at least the particle size, the number or the type of the organic particles (6) is detected in a vacuum atmosphere based on the above (0). 2. The first optical system (12) and the second optical system
(14) disposed on an optical path for connecting, and comprising a reflection mirror (15) for guiding the fluorescence (20) coming from the wafer (1) side to the optical detector (17). Claim 1
An organic particle monitoring device for a semiconductor wafer in a vacuum container according to the above. 3. The second optical system (14) and the reflection mirror
It is provided so as to penetrate the center of (15), and comprises a light-shielding pipe (13) having a light-shielding property other than the traveling direction of the laser beam (11A) and the traveling direction of the fluorescent light (20). 3. An apparatus for monitoring an organic particle of a semiconductor wafer in a vacuum vessel according to claim 2. 4. The light-shielding pipe (13) is connected to the wafer (1).
4. A semiconductor wafer in a vacuum vessel according to claim 3, wherein the semiconductor wafer is provided perpendicular to the surface of the wafer so that the surface of the wafer can be irradiated with the laser beam vertically. Organic particle monitor. 5. The laser oscillator (11) includes a He-Cd
5. The apparatus according to claim 1, wherein the apparatus is a laser oscillator. 6. A semiconductor in a vacuum vessel according to claim 1, wherein said optical detector (17) comprises an image intensifier (17A) and a CCD camera (17B). Organic particle monitor for wafers.