JPH03285339A - Detection of contamination, device for it and semiconductor manufacturing line - Google Patents

Abstract

PURPOSE:To make it possible to detect easily the degree of contamination of a substrate and the presence or absence of foreign substances by a method wherein when the whole surface of the substrate is scanned with spot light, scattered light from a spot position on the substrate is detected while the generation of an unnecessary Rayleigh scattering is suppressed. CONSTITUTION:A sample 3 subjected to heating treatment is next placed on a mount stage 205 and thereafter, the height of the surface of the sample 3 is adjusted so as to coincide with the focus surface of a scattered light detection system 223. After that, while the sample 3 is rotated by a stage 204 and moreover, while the sample 3 is moved by an X stage 202 in a direction X, the whole surface of the sample is scanned with a laser beam spot. In the case foreign substances or contamination exist at a certain scanning position, a laser beam scattered by them is detected by a detector 209 via an objective lens 208 and with this detection it can be decided that the foreign substances or the contamination exist. As a vacuum chamber 201 is exhausted so as to bring its interior in a vacuum state prior to the detection of the contamination, the scattered light of the laser beam can be detected by the detector 209 in a large S/N ratio in a state that the generation of an unnecessary Rayleigh scattering is suppressed as much as possible.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a contamination detection method for detecting foreign matter or contamination present on a substrate, or contaminant elements present in the substrate with high accuracy. The present invention relates to a semiconductor manufacturing line in which the apparatus is disposed at a predetermined position in the line.

[Prior Art] In semiconductor manufacturing, if minute foreign matter is present on a wafer, this tends to cause poor insulation, short circuits, etc. on wiring. Additionally, as semiconductor devices become smaller, if elements such as heavy metals are present on the wafer, the capacitor's insulating film, gate oxide film, etc. are more likely to be destroyed or short-circuited due to these elements. .

By the way, as a technique for detecting minute foreign matter on a wafer, for example, Japanese Patent Application Laid-open No. 1983-1.35848 is cited. In this case, the wafer is irradiated with a laser, or if a foreign object is attached to the wafer, the foreign object itself generates scattered light, and the foreign object is detected by detecting this scattered light. It has become so.

The foreign matter detected as described above is analyzed by known techniques such as laser photoluminescence or secondary X-ray spectroscopy (XMR).

In addition to the above-mentioned literature, there is also a paper entitled “C.
U Kantamine Yonon 5i (100) Surf Ace” (Nyabani Sun Yarnal of Abright Finx Volume 27 No. 10-Yumi 1988 IO Month 1 Page L181
9-L1821) [TEM 0bservatio
no Defects Induced by Cu
Contamination on S 1 (100)
Surface (JAPANESE JOURNAL)
OF APPLIED PHYSIC3Vol, 27. N
o,10,,0CTOBER,198g,pp,L18
19-Lla21)J, when the Si substrate is heat-treated,
The phenomenon of diffusion and precipitation of Cu in the Si substrate is introduced.

Furthermore, “Applied Physics” (Vol. 51, No. 11 (1982)
1, pp. 1246-1254) discusses the relationship between crystal defects and contaminant precipitation.

[Problems to be Solved by the Invention] Incidentally, as LSIs become smaller, the reality is that the presence of minute foreign matter is gradually becoming a problem in semiconductor manufacturing. However, it is no longer possible to detect such minute foreign particles using the technology disclosed in the above-mentioned publication, and even more so, it is impossible to detect contamination due to heavy metal elements existing in or on the wafer surface. It has become.

SUMMARY OF THE INVENTION An object of the present invention is to provide a contamination detection method that can accurately detect foreign matter and contamination present on a substrate.

Another object of the present invention is to provide a method for detecting 115 staining that can detect contaminant elements and the like present in a substrate with good accuracy.

Furthermore, another object of the present invention is to provide a stain detection device capable of detecting foreign matter and contamination present on a substrate with high accuracy;
It is an object of the present invention to provide a contamination detection device that can detect contaminant elements and the like existing in a substrate with good accuracy.

Still another object of the present invention is to provide a semiconductor manufacturing line in which the degree of contamination of a substrate to be processed and the presence or absence of foreign matter can be easily detected in each vacuum processing apparatus for semiconductor manufacturing.

[Means for Solving the Problems] The above object is achieved by detecting scattered light from the spot position on the substrate while suppressing unnecessary Rayleigh scattering when the entire surface of the substrate is scanned by spot light.

Another object is achieved by detecting foreign matter or contamination after heating the substrate as a pretreatment.

Furthermore, another object of the present invention is to provide a contamination detection system that detects foreign matter or contamination present on a substrate by detecting scattered light from the foreign matter or contamination. By equipping a contamination detection device equipped with an atmosphere setting and holding system with an atmosphere setting and holding system that enables detection while suppressing unnecessary Rayleigh scattering in a specific atmosphere, the substrate is preheated prior to contamination detection. This can be achieved by providing a substrate heating system that maintains the temperature.

Furthermore, another object is achieved by providing a contamination detection device configured as described above at the substrate entrance/exit of each vacuum processing apparatus for semiconductor manufacturing.

[Operations] Generally, when the entire surface of the substrate is scanned by spot light,
When foreign matter or contamination exists on the substrate, scattered light is generated at the location where the foreign matter or contamination exists, and the foreign matter or contamination can be detected by detecting this scattered light. However, in this case, if you try to irradiate the substrate surface with the spot light in normal air or make it reflect on the substrate surface, and also to detect the scattered light due to foreign objects or contamination, the irradiation path and reflection path of the spot light must be Not only does unnecessary Rayleigh scattering occur due to molecules, but also unnecessary Rayleigh scattering occurs due to air molecules on the way to the scattered light detection system, so the scattered light has a high S/N ratio and cannot be detected. That is what it is. Therefore, scattered light is detected under specific atmospheric conditions where unnecessary Rayleigh scattering is suppressed (specifically, low pressure, low temperature, or atmospheric conditions of specific gases (those with less Rayleigh scattering than air)). By doing so, foreign objects and contamination can be detected with good accuracy.

Additionally, if the substrate is heated, for example, by laser beam scanning prior to detecting foreign matter or contamination, contaminant elements such as heavy metals present in the substrate will be diffused and collected and precipitated on the substrate surface. Therefore, contaminant elements present in the substrate can be detected. At that time,
If the substrate is etched with processing gas after heating, or if the substrate is heated with low potential areas or minute scratches formed on its surface, teta staining will be particularly emphasized, resulting in higher precision. Contamination can be detected.

Furthermore, contamination detection devices are generally configured to detect foreign matter present on the substrate or scattered light from contamination;
Alternatively, a contamination detection device that detects scattered light from contamination is equipped with an atmosphere setting/maintenance system that allows the scattered light detection system to detect foreign objects or scattered light from contamination while suppressing unnecessary Rayleigh scattering in a specific atmosphere. If you are forced to
Not only can the occurrence of unnecessary Rayleigh scattering on the spot light irradiation path and reflection path be suppressed, but also Rayleigh scattering on the scattered light detection path of scattered light, which is necessary for detecting foreign objects or contamination, can be suppressed. Therefore, foreign objects or contamination can be detected with good accuracy. Also,
To detect contaminant elements present in the substrate, a 7'f5 dye detection device equipped with an atmosphere setting and holding system is used.
If the substrate heating system for preheating the substrate prior to contamination detection is further provided with a device 61η, then for the reasons stated above, (
Contaminant elements present in the plate can be easily detected.

Furthermore, if a contamination detection device configured as described above is installed at the substrate entrance/exit of each vacuum processing device as a component in a semiconductor manufacturing line, the contamination detection device configured as described above is installed before and after processing in each vacuum processing device. This makes it possible to control contamination.

[Example] The present invention will be explained below with reference to FIGS. 1 to 6.

First, the contamination detection device according to the present invention will be described. FIG. 1 shows the configuration of an example thereof. As shown in the figure, the entire structure of this example is composed of a contamination precipitation section 100, a contamination detection section 200, and a contamination analysis section 300. Of these, the contamination precipitation section (heating section for the substrate as a sample) 100 is configured with a vacuum chamber 101 as its center.
A sample (substrate: specifically a wafer, T
(e.g. LCD TV substrate with PT formed) 3 is the mounting table 1
10 , it is heated by an infrared heater 109 , and after heating, it is introduced into the contamination detection section 200 via the sample extraction/intake port 104 . The heating temperature at that time is measured by a thermometer 108, and the atmosphere in the vacuum chamber 101 is set and controlled by a reaction gas supply system 112, a reaction gas exhaust system 107, and a vacuum exhaust system 106. It has become a thing.

Incidentally, a brief explanation of the infrared heater 109 as a heating source, the thermometer 108 as a temperature measuring means, and atmosphere setting control is as follows.

That is, first, as a heating source, in addition to the infrared heater 109,
A filament type lamp (halogen lamp, tungsten lamp, etc.) or a laser light source (Ar laser, excimer laser, YAG laser, COt laser, etc.) can be used. The sample 3 can be easily heated by focusing laser light from a laser light source and scanning the sample 3. In addition, since this method can process only a limited area on the wafer, it is possible to process TEG (TEST ELEM) on the wafer during device manufacturing.
If an area for contamination evaluation is formed on ENTGROUP), contamination generated in each process can be evaluated.

Regarding the temperature measurement means, there are those that directly measure the temperature of the sample 3, such as an infrared radiation type and a diffraction light detection type (described in JP-A-62-88929), and those that directly measure the temperature of the sample 3. The temperature of the mounting table 110 may be measured. At this time, contact thermometers such as thermocouples can also be used.

Furthermore, to explain the atmosphere setting control, first of all, regarding the vacuum υ gas system 106 for evacuating the inside of the vacuum chamber 101, it is possible to use a rotary pump, an oil diffusion pump, a turbo molecular pump, etc. However, it is necessary to have the ability to maintain a sufficient degree of vacuum to prevent the samples from reacting with unexpected gas molecules in the atmosphere during heat treatment.Specifically, The degree of vacuum is 10-
It is desirable that the pressure be at around 'Torr, and for that purpose, it is desirable to draw it with a rotary pump and pull it with a turbo molecular pump or the like. Further, the reaction gas exhaust system 107 is configured as a vacuum exhaust system, but normally only the vacuum exhaust system 106 is used for vacuum exhaust.

However, if the reactive gas is a harmful gas or a reactive gas, the reactive gas exhaust system 107 is used, but if the exhaust performance of the vacuum exhaust system 106 is insufficient, the vacuum exhaust system 106 and They are now used together. Furthermore, in the reaction gas supply system 112, one or more types of gases such as 02, N3, CF, etc. are accumulated in a cylinder 104, and one or more types of gases are selected from these gases and mixed in a mixer 203. In addition, the vacuum chamber 10 is
It is designed to be supplied within 1 minute.

The contamination precipitation section 100 has been described above. Next, the contamination detection section 200 will be explained.
19, vacuum chamber system 220, light source system 222, scattered light detection system 2
23 and a signal processing system 224. As shown in the figure, in the stage system 219, the sample 3 is placed on the Z stage 218 and the θ stage 20 via the mounting table 205.
4. Since the sample 3 is placed on the X stage 202, it is rotatable and movable in the X and Z directions. In addition, the vacuum chamber system 220 is
4.217 is composed of a vacuum chamber 2゜1 formed by heating the vacuum chamber 2゜1, and a vacuum υ1-gas system 203 for evacuating the vacuum chamber 2゜1, and the light source system 222 also includes a He-Cd laser light source (wavelength: 325 nm). 206, an optical window (constituting a part of the partition wall of the vacuum chamber 201) 218, a condensing optical system 221, and a mirror (for scanning) 207. Furthermore, the scattered light detection system 223 includes an objective lens 208 and a detector 20.
9 and a cooler (for cooling the detector 209) 210, and the signal processing system 224 further includes a light source blinking controller 212, a synchronization detection circuit 213, a binary circuit 214, and a data processing section 216. There is. Note that in this example, only the detector 209 is heated by liquid nitrogen.
Although it is cooled to about 80° C., the analog portion including the synchronization detection circuit 213 and the binary circuit 214 may also be cooled. This is because noise in the analog part is reduced by cooling.

Now, after the sample 3 is placed on the mounting table 205, the stage system 219 is finely adjusted by the autofocus system 211 under the control of the control unit 215 so that the sample is positioned on the focal plane of the scattered light detection system 223. However, after this adjustment, if the X stage 202 is moved while rotating the θ stage 204, the entire surface of the sample 3 will be scanned by the laser beam spot from the mirror 207. By the way,
As the autofocus system 211, an appropriate method such as a striped pattern projection method or a laser oblique illumination method can be adopted.

FIG. 2 shows another example of the configuration of the scattered light detection system 223. As illustrated, the objective lens 208, the detector 209, etc. may be provided outside the vacuum chamber 201. However, in this configuration, an optical window 229 (constituting a part of the partition wall of the vacuum chamber 201) is required. In addition, at this time, the objective lens 208 is
Aberrations including the thickness and position of the lens 29 must be corrected. In some cases, the optical window 229 is the objective lens 2
It may be configured as part of 08.

FIG. 3 also shows an example in which an infrared heater 109 constituting a part of the contamination precipitation section 100 is provided outside the vacuum chamber 101. In this case, the entire vacuum chamber 101 is the sample chamber 11
It is configured as 3.

The sample chamber 113 itself is movable in the direction of the contamination detection unit 200 so as to be positioned directly below the objective lens 208, and a part of the partition wall of the vacuum chamber 101 is configured as an optical window Ill. Vacuum chamber 101 is contamination detection section 2
When moved to 00 (a part of sample 3 etc. is displayed with a broken line),
Scattered light from inside the sample chamber 113 is detected outside the vacuum chamber 101 through the optical window 111. The other circumstances are the same as in the case of FIG.

Note that in this example, the θ stage 204 of the stage system 219 is replaced with the Y stage 205 because it is necessary to move the vacuum chamber 101 in the direction of the contamination detection unit 200.

Of course, the θ stage 204 and the Y stage 205 may be used together. Note that the autofocus system is not shown in FIG. 3.

Here, returning to FIG. 1 again to explain the contamination analysis section 300, the contamination analysis in the contamination analysis section 300 is performed by the control section 30.
The process is carried out in a vacuum chamber 301 under the control of 9. Sample removal/intake port 217, sample I4 removal port 30
A mounting table 305, a Z stage 318, and a θ stage 30 are installed in the vacuum chamber 301 equipped with
4 and an X stage 302, and a scanning electron microscope 306 for contamination analysis. In this case, it is desirable that the scanning electron microscope 306 be equipped with a secondary X-ray spectroscopy (XMR) means 308. Scanning electron microscope 306
Instead of the above, a scanning tunneling microscope, secondary ion mass spectrometry means, etc. may be provided.

Now, to explain the overall operation, the contamination detection device according to the present invention shown in FIG. 1 evaluates the foreign matter and contamination present on the sample 3. The cleanliness of various LSI manufacturing equipment (for example, dry processing equipment 1 such as etching equipment, CVD equipment, sputtering equipment, and exposure equipment, or wet processing equipment 2 such as cleaning equipment and wet etching equipment) can be evaluated. There is. When evaluating the LSI
A gummy sample for contamination evaluation is passed through the manufacturing equipment, and the sample I43 thus obtained is first passed through the contamination precipitation section 100.
It is scheduled to be placed on.

Further, when using the TEG region on the wafer described above, it may be a sample during device fabrication instead of a dummy sample. In the contamination precipitation section 100, the sample 3 is heated prior to contamination detection, and the reason why this heating is necessary is as follows.
This is already clear from the papers listed in the section on [Walking techniques]. According to that paper, the temperature is 115 in Nt atmosphere.
0.2x0.2μm, depth 0 after heat treatment at 0℃ for 1 hour
．． 5. It has been reported that Cu and Si of the order of czm were precipitated and formed in defects on the surface of the Si substrate, but the reason for this phenomenon is not clear, but in that paper the SL
It is explained that this is because Cu atoms contained in the substrate are diffused by heat treatment and gettered into Si defects. By analogy, it is expected that a similar phenomenon will occur with other metals that have a small solid solubility limit in Si, such as Fe, Cr, and W.

In order to take advantage of the above phenomenon, the contamination detection unit 100
is heat treated at about 1000° C. for about 1 hour. The processing temperature and processing time at this time are both guidelines, and the temperature and time are not limited to these and can be determined appropriately. In addition, in order to make the above-mentioned phenomenon caused by heating more reliable, crystal defects (gJ) are formed on the surface of sample 3 in order to form a low potential area.
is starting to form. The scratches become the core of contamination precipitation. However, the scratch needs to be small enough so that it does not become a noise when it is detected whether or not contamination has been deposited. Specifically, it is desirable that the size is 0.01 μm or less. The scratches at this time are described in the literature (Nanometer Scale Struc
turing of 5ilicon by Dire
It is effective to use a scanning tunneling microscope, as described in CT Indentation). Furthermore, at that time, when a specific gas species is selected as the atmosphere in the vacuum chamber 101, it is possible to selectively grow only a specific element.

Now, to explain the operation of the contamination detection unit 200, the heat-treated sample 3 is then placed on the mounting table 205, and the scattered light detection system 223 is placed at the height of the surface of the sample 3.
It is adjusted to match the focus plane of
3 is being rotated by the e-stage 204, and
The entire surface of the stage 202 is scanned by a laser beam spot while being moved in the X direction by a stage 202. If a foreign object or contamination exists at a certain scanning position, the laser beam scattered by the foreign object or contamination is detected by the detector 209 via the objective lens 208, and the detection of this scattered light indicates whether the foreign object or contamination is present. It can be determined that the In this example, since the vacuum chamber 201 is evacuated to a vacuum state prior to contamination detection,
The scattered light can be detected by the detector 209 with a high S/N ratio while the occurrence of unnecessary Rayleigh scattering is suppressed as much as possible. At that time, instead of evacuating the vacuum chamber 201 to a vacuum state as much as possible, the atmosphere inside the vacuum chamber 201 may be filled with a specific gas (one that causes less Rayleigh scattering than air), or it may be kept at a low temperature. Similar effects can be obtained. The generation of scattered light is suppressed by keeping the inside of the vacuum chamber 201 in a low pressure state, and FIG. 4 shows this situation.

This figure was calculated with reference to "Principles of Optics + 11J (Tokai University Press p9.950-962)" written by Max Horn and Emil Wurtz, translated by Toru Kusayo and Hidetsugu Yokota. As can be seen, the scattered light output due to Rayleigt scattering of air molecules under 1 atm is at the same level as a foreign object with a size of about 0.05 μm.Therefore, if air normally exists, , the size of the foreign object becomes the detection limit.However, by creating a vacuum of υ1 air in the vacuum chamber 201,
For example, if the pressure is reduced to 100 mTOrr, foreign matter can be detected up to a size of about 0.01 μm.

Note that since the operation of the contamination analysis section 300 is not directly related to the present invention, its operation will be omitted.

The contamination detection device according to the present invention has been explained above.
This contamination detection device can be incorporated into semiconductor manufacturing lines. When a contamination detection device is provided at the substrate entrance/exit of each vacuum processing device constituting a semiconductor manufacturing line, contamination before and after processing in each vacuum processing device can be easily controlled.

Finally, a method for preparing a sample used to evaluate the performance of the contamination detection device according to the present invention will be described. When evaluating the contamination detection device, 001 μm to 0.00 μm.
Although it is necessary to deposit fine particles with a size of about 0.3 μm on a sample, it has been difficult to obtain a sample to which such fine particles are attached. This is because even if standard fine particles such as polystyrene are used, the adhesion position on the sample may become unclear or the ultrapure mixture may aggregate, making it difficult to obtain an appropriate performance evaluation sample. was difficult.

By the way, "Journal of Science Ant Technology 86 (6), NOV/DEC1988J (J, V
AC5C1, TEC) INOL, B6. NOV/DEC
1988), pages 1877-1880, it is reported that deposit particles with a size of 0.02 to 0.03 μm were created. As shown in FIG. 5, using a scanning tunneling microscope 1 and tungsten carbonyl (W(Co)) as a reaction gas 2, deposited particles 3 of that size are deposited on the surface of a wafer 4. However, this technology makes it possible to obtain a performance evaluation sample.As shown in Figure 6, the deposited particles 3 are almost regularly distributed on the surface of the performance evaluation sample 5. Therefore, compared to the method using standard particles, the position of the deposited particles is clearer, so that evaluation can be carried out quantitatively and quickly.

[Effects of the Invention] As explained above, in the case of claims 1 to 4, foreign matter and contamination existing on the substrate can be detected with good accuracy, and in the case of claims 5 to 8, , contaminant elements present in the substrate can be detected with good accuracy. Furthermore, according to claim 9, if foreign matter or contamination present on the substrate is also according to claim 10,
A contamination detection device that can detect contaminant elements and the like present in a substrate with good accuracy can be obtained.

Furthermore, according to claim 11, the degree of contamination of a substrate to be processed and the presence or absence of foreign matter can be easily evaluated and detected in each vacuum processing apparatus constituting a semiconductor manufacturing line.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an example of the contamination detection device according to the present invention, FIG. 2 is a diagram showing the configuration of another example of the scattered light detection system shown in FIG. 1, and FIG. FIG. 4 is a diagram illustrating how Rayleigh scattering by air molecules changes depending on atmospheric pressure conditions; FIG. FIG. 6 is a diagram for explaining a method for producing deposit particles in a certain paper, and is a diagram showing a sample for evaluating the performance of the contamination detection device according to the present invention. 3...Sample (substrate), 100...Contamination precipitation part, 101
, 201... Vacuum chamber, 109... Infrared heater, 20
0.T5 dye detection section, 206... Item 1e-Cd laser light source, 208.Objective lens, 209...Detector Fig. 2 10 03

Claims (1)

[Claims] 1. When the entire surface of the substrate is scanned by spot light, foreign matter or contamination present on the substrate is detected by detecting scattered light from the spot light position on the substrate. The method includes a method in which Rayleigh scattering of spot light in the irradiation path and reflection path and Rayleigh scattering of scattered light from foreign objects or contamination in the path to the scattered light detection system are suppressed to a small level. Or a contamination detection method in which scattered light from contamination is detected. 2. The contamination detection method according to claim 1, wherein the scanning of the substrate with the spot light is performed in an atmosphere at a pressure lower than atmospheric pressure. 3. The contamination detection method according to claim 1, wherein the scanning of the substrate with the spot light is performed in a low temperature atmosphere. 4. The contamination detection method according to claim 1, wherein the scanning of the substrate with the spot light is performed in a gas atmosphere with less scattering than air. 5. The contamination detection method according to any one of claims 1 to 4, wherein foreign matter or contamination is detected after heating the substrate as pretreatment. 6. The contamination detection method according to claim 5, wherein the foreign matter or contamination is detected while the substrate is etched with a processing gas after being heated so that the foreign matter or contamination is emphasized. 7. The contamination detection method according to claim 5, wherein the substrate is preheated by scanning a laser beam onto the substrate. 8. The contamination detection method according to any one of claims 5 to 7, wherein the heating of the substrate is performed with a low potential portion or a minute scratch formed on the surface of the substrate. 9. Remove foreign matter or contamination existing on the substrate.
Alternatively, there is a contamination detection device that detects by detecting scattered light from contamination, which includes a stage system on which a substrate is placed so as to be movable in the X, Y, and Z directions and rotatable within the XY plane, and movement of the stage. an illumination light source system that scans the entire surface of the board with a spot light in conjunction with the system; a scattered light detection system that uses photoelectric conversion to detect only the scattered light from the spot light position on the board; an imaging system that forms an image of the scattered light from the scattered light; a signal processing system that processes the scattered light detected by the scattered light detection system in synchronization with scanning by the spot light; A contamination detection device comprising at least an atmosphere setting/maintaining system that detects only scattered light from the surrounding area while suppressing unnecessary Rayleigh scattering in a specific atmosphere. 10. The contamination detection device according to claim 9, further comprising a substrate heating system for preheating the substrate prior to contamination detection. 11. A semiconductor manufacturing line, wherein the contamination detection device according to claim 9 or 10 is provided at each substrate entrance/exit of a vacuum processing apparatus for semiconductor manufacturing.