JPS58164227A - Inspection of pattern defect - Google Patents

Abstract

PURPOSE:To detect surely a foreign matter such as dust, etc., adhered on the glass face side of a reticle by a method wherein a laser beam is irradiated to the fine pattern provided on an IC, scattered light from the edge part of the pattern is detected to perform the comparative inspection, while reflected light from the pattern is also detected to perform the comparative inspection the same. CONSTITUTION:The transcribed image 121 of the circuit pattern and the transcribed image 122 of the foreign matter on the glass face side of the reticle adjoining thereto are provided on a semiconductor chip 120, and the transcribed image 124 of the circuit pattern is formed also on another chip 123. An wafer 125 having the two chips like this on the surface is fixed with an wafer chuck 126, and objective lenses 128, 127 and beam splitters 136, 135 are arranged respectively at the upper parts of the chip 123 and the transcribed image 122 of the foreign matter. A reflected laser beam 140 from the transcribed image 122 of the foreign matter and a reflected beam 141 from the chip 123 having no transcribed image of the foreign matter are detected respectively by photomultipliers 137, 138 by this way, outputs amplified by amplifiers 131, 132 are inputted to a differential amplifier 133, and existence of the foreign matter is detected based upon the difference of the quantity of light.

Description

[Detailed description of the invention] The present invention relates to a pattern defect inspection method.

In recent years, as the density of medium conductor integrated circuits W and Awayuki has increased, methods for forming fine patterns have become more and more overlapping. As a means for forming this fine pattern, a recently developed fine projection exposure method has superior performance in resolution and alignment accuracy compared to conventional Iokki.

However, unlike the conventional exposure method, the exposure method is step-and-repeat for each chip, so if there is any foreign matter such as dust on the reticle, the foreign matter will be exposed on all chips. is transferred and becomes a common defect. Even if the defect is large, all wafers may become unnecessary depending on the position within the chip.

Therefore, the most important problem is to detect the foreign matter on the reticle with a high degree of accuracy.

[Detection] & Conventional methods have multiple chips of the same shape and are used to reduce and transfer onto a wafer. There is a method of comparing and inspecting the chip of 7t#Il which was defective due to the presence of dust and a second chip which was not defective because there was no foreign matter such as dust. This method will be explained below using the drawings.

No. 111 is a plan view of a defective chip 103 having a transferred image 101 of an am pattern and a transferred foreign matter 111021.
Figure 2 shows a transferred image 10 of a circuit pattern having the same shape as Figure 1.
4 is a plan view of a non-defective product 1050. FIG. 3 is a diagram explaining the principle of this method. As shown in Figure 3, f
Wafer 106 having transfer images 101 and 104 of i-path pattern and transfer image 1021 of foreign matter; k wafer 107
The objective lens 108, 109t-
The laser beam 110 is placed at a distance equal to an integral multiple of 1,000 mm and is irradiated onto the wafer 106 from above, while at the same time scanning the wafer 106 in a direction parallel to the paper surface and perpendicular to the laser beam 110111. This laser beam 110 is used to transfer the circuit pattern 101, 104 and foreign matter f.
Scattered at the end of the putter 7 of l1102, photoful 1
11.112 K, the light is received and converted into an electrical signal. These two signals are each amplified 16113.11
After being amplified by 4.

A differential amplification 1111B leads to a comparison output 116.

Here, if the laser beam 110 is irradiated to the end of the transferred image 102 of the foreign matter in the thousand dub 1'o3 as shown in FIG. Since such a transferred image does not exist in 10ISK, no scattered light enters Photoful 112K.

Therefore, a difference occurs between the two electrical signals mentioned above,
Output 116K is differential amplification 1111! A zero signal is generated from $.

On the other hand, if the laser beam is irradiated to the edge of *Ii1@Papa p-yo transfer image 101.104, Photomal 111.
Since the same amount of 0IklL light is incident on 112, there is no difference between the two electrical signals mentioned above, and the output is 1.
16K is a differential amplifier]. Therefore, a signal is generated at the output 116 only when a transferred image of a foreign object is present, so that the presence of a defect can be detected. However, according to this method, as shown in FIG. 4, one layer is placed on the glass surface side of the reticle 117, that is, on the side opposite the circuit butter by □□8°. Foreign object 1□ is present.
tt of the FIaK light transferred to the wafer
) The transferred image 11a is the transferred image 10 of the pattern.
When the laser beam 110 is irradiated onto a pattern with such a thin film thickness and a gentle shape (Fig. 5), Generally, the scattered light at the edge of the pattern becomes very weak. Therefore, only weak scattered light enters the photoful 111 and almost no electrical signal is generated, so there is no difference between the two electrical signals, and a signal is output from the differential amplifier 115 to the output 116. However, since the presence of defects cannot be detected, reliability is extremely low.

Therefore, the present invention has been developed to address the above problems, and provides a pattern defect inspection method that can reliably detect the presence of foreign matter such as dust even if it exists on the glass surface side of the glass. There is a particular thing.

In other words, the OIN feature of the present invention is that, in a pattern comparison and inspection device, a pattern is irradiated with a laser beam, the scattered light from the edge of the pattern is detected and comparatively inspected, and the reflected light from the scissor pattern is detected. The process of comparative inspection and the pattern defect inspection method are characterized by:

The details of the present invention will be explained below using the drawings. 6th
The figure is an explanatory diagram of the principle of a pattern defect inspection method using an apparatus. K as in all cases.

Inside the chip 120, there is a transfer image 122k of foreign matter on the glass surface side of approximately n patterns 11121° and 1,000 km.

+9 F1! 3 KWA@t4p-yf)fl
A wafer 125 having ix'4fll 124 is fixed on a quenching rack 126, and objective lenses 127, 128°7 otomaru 129 and 1310 are installed above T, and these photoful 12L 130 are each amplified. 11131°s sg K*tR@Rete, Difference 11 Amplification 11t s3 K Te output 134 is reached.The driving method of the wafer chuck 126 and the scanning method of the laser beam 139 are the same as in FIG.

As a trap for the present invention 0IfI # mold, objective lens 127°1
Beam splitters 135, 136 and photofuls 1317, 138 are installed above 28 as shown in the figure, and Ly photofuls 37, 138 are amplified by 11,131 respectively.
．． 132km! I! has been done. This beam splitter is a half mirror for guiding the laser beam 139 to the reflected beam 140, 1411, and photoful 137, 138 when irradiated onto the wafer 125, respectively. Therefore, an electric signal corresponding to the amount of light obtained by adding the scattered light and the reflected light at the end of the pattern is input to the amplification 1) 131 and 132.

Here, when the laser beam 139 is irradiated to the edge of the thin, gently shaped transfer image 122 of foreign matter present on the side of the glass surface, as described above, the transferred image 1
Since the film 22 has a thin film thickness and a gentle shape, almost no scattered light is generated and no electric signal is generated in the photoful 129. The same is true for the photoful 130. However, the reflected lights 140 and 141 enter the photofuls 137 and 138, respectively. Since these two reflected lights 140 and 141 are monochromatic lights, they interfere with each other depending on the film thickness of the transferred image formed on the chip, and the amount of light changes significantly. Therefore chip 12
The light 140 reflected from the transferred image 122 of the foreign matter on 0;
There is a significant difference in the amount of light 141 reflected from the area on the chip 12S where there is no transferred image of the foreign matter. Therefore, there is a significant difference between the electrical signals input to the amplifiers Ws 131 and 132, and the signals are outputted to the output 134 by the differential amplifier 5133. However, if the transferred image 122 of the foreign matter has a steep shape and is thick, the above-mentioned electric signal will be further affected.

Transfer of foreign matter 1111! ! Diffusion from 1 Photoful of light 12
Since the electrical signal generated as incident on 9 is added, amplification 1) 131.13! The difference between the signals input to Kl1
A signal is output to the destination 9 output 134. On the other hand, laser beams 1
39 is irradiated, the same amount of 1Ikt will be incident on the photomultiplier 129.130. Also, rjXA16/
Since the film thickness of fter:/1211124 is the same, the same amount of reflected light 140.141 is reflected on Photoful 137.138.
is incident. Therefore, there is no difference in the electrical signals input to the amplifiers 11131 and 132, and the output 134 has a differential amplifier @11.
No signal is output from 1$3.

When the laser beam 139 is irradiated onto the transferred image 121 and 124 of the next Kll path pattern, %at does not occur, so %
Since no light is incident on the 7th and 1st lenses 129 and 130, and the film thicknesses of the circuit parameters 7121 and 124 are the same, the same amount of reflected light 140 enters the photoful 137 and 1311.
．． 141 is incident. Therefore amplification 111131.132
There is no difference in the electrical signals input to the differential amplifier 11133, and no signal is output from the differential amplifier 11133 to the output 134.

As mentioned above, when the shape of the transferred image of the foreign object is smooth and the film thickness is thin, the conventional method, that is, the method of detecting scattered light, cannot obtain a sufficient electrical signal and the reliability of defect inspection becomes poor. However, according to the present invention, a sufficient electrical signal can be obtained and a sufficient electrical signal can be obtained, making it possible to perform defect inspection. Highly reliable.

Since this interference of monochromatic light is determined only by the film thickness, it is possible to realize defect detection that is not affected by the shape of the transferred image. Furthermore, if the shape of the transferred image is steep and the film thickness is thick, Kti,
Since it is possible to detect scattered light in addition to reflected light, the obtained electrical signal is even larger, making it possible to perform defect inspection1** with much higher reliability than conventional technology.

[Brief explanation of drawings]

11Il to 3rd panel are original theories of the conventional pattern defect inspection method, 4th figure is *wml of the line reticle, 5th figure is a cross-sectional view of the 411th reticle 0 transfer image, and 6th figure is the present invention Primal layer theory I in one example of! It is a diagram. In addition, in the figure, 101...Bl! Transferred image of pattern, lOt... Transferred image of foreign matter, t03...
...Natsume Sentsubu, 104...1III pattern transfer L105...Natsume Shina Sentsubu, 1o6...
...Wafer, 1o7...Wafer chuck,
1o8...Objective lens, 1o9...Objective lens 1110...Laser light, 111...
...□7t) full, 112...fo) ”t
k, 113118...Circuit pattern, 11
9... Dust and other OA materials 120... 1,000 rubs* 121... Transfer image of circuit pattern, 12
G...Transferred image of foreign matter on the glass side of the reticle, 1
23... Chip 5124... Transfer image of circuit pattern, 125... Wafer, 126...
...Wafer chuck, 127...Objective lens, 128...Objective lens X, 129...
・7 Otomaru, 13o...Photoful, 131
......Amplifier, 132...Amplification at, 1
33... Differential amplification Ill, 134...
This is the output. //vinegar

Claims (1)

[Scope of Claims] A step of irradiating the putter y with laser light and detecting scattered light from the end of the pattern for comparative inspection. A pattern defect inspection method comprising the steps of detecting and comparatively inspecting reflected light from a scissor pattern.