JP2014137278A - Inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that various portions are driven by electric power in an optical inspection device, the optical inspection device is considered to operate continuously after the start of an inspection, a long-time operation causes heat generation undesired for the portions driven by the electric power, and this point is not sufficiently considered in a conventional technology.SOLUTION: In the present invention, heat generation in a predetermined portion in an inspection device is monitored. The predetermined portion indicates at least one of a sensor, driver unit, stage, control device, and illumination system, for example.

Description

  The present invention relates to an inspection apparatus for inspecting defects on a substrate. In particular, the present invention relates to an inspection apparatus for inspecting a defect on a semiconductor wafer on which a circuit pattern is formed.

  In the semiconductor manufacturing process, defects such as foreign matters and scratches on the wafer surface cause defects such as a short circuit of a wiring pattern, and also cause defects in insulation of capacitors and breakdown of gate oxide films. Similarly, defects on the wafer on which the circuit pattern is formed also affect the electrical characteristics of the semiconductor element. Therefore, it is important to detect defects in the semiconductor manufacturing process and feed back to the semiconductor manufacturing process.

  It is a so-called inspection device that detects such defects. An example of the inspection apparatus is an optical inspection apparatus that detects a defect on the substrate by irradiating the substrate with light and detecting the scattered light. The following patent documents are listed as conventional techniques.

JP 2007-248086 A JP 2008-249571 A JP 2004-157444 A JP 2011-027485 A

  In the optical inspection apparatus, various parts are driven by electric power. It is conceivable that the optical inspection apparatus operates continuously once inspection is started. Long operation causes undesired heat generation in the part driven by electric power. In this regard, the prior art has not been sufficiently considered.

  The present invention is characterized by monitoring heat generation at a site in the inspection apparatus.

  According to the present invention, a phenomenon undesirable for inspection can be prevented.

1 is a diagram illustrating an inspection apparatus according to Embodiment 1. FIG. The figure explaining the upper detection system 800. 3 is a flowchart for explaining the first embodiment. The figure explaining exothermic function f (t). FIG. 6 is a diagram illustrating a second embodiment. 9 is a flowchart for explaining a second embodiment.

    Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating an inspection apparatus according to the present embodiment. The inspection apparatus according to the present embodiment is a wafer inspection apparatus with a pattern, and illuminates illumination light 301 from an oblique direction on the inspection target 200. The illumination light 301 is illuminated from the illumination system 300. The illumination system 300 includes a cylindrical lens, a cylindrical mirror, and the like, and the illumination light 301 may form a linear illumination region in the shape of the inspection target 200. Scattered light from the illumination region formed by the illumination light 301 is detected and imaged by the upper detection system 800 and the oblique detection systems 100 and 101.

  Next, the upper detection system 800 and the oblique detection systems 100 and 101 will be described in detail. The upper detection system 800 is arranged along the direction of the normal line 204 of the inspection target 200. The upper detection system 800 includes an objective lens 805, an imaging lens 809, and a sensor 802 (a one-dimensional line sensor, a two-dimensional sensor, etc.). The oblique detection systems 100 and 101 are arranged obliquely with respect to the inspection target 200. A point having an objective lens 805, an imaging lens 809, and a sensor 802 (a one-dimensional line sensor, a two-dimensional sensor, etc.) is the same as the upper detection system. It should be noted that at least one of the upper detection system 800 and the oblique detection systems 100 and 101 has a spatial frequency plane (Fourier) for shielding undesired diffracted light from a circuit pattern formed on the inspection target 200. In some cases, a so-called spatial filter may be provided. In the inspection apparatus of the present embodiment, three dark field images are obtained for one illumination area.

  The dark field images obtained from the upper detection system 800 and the oblique detection systems 100 and 101 are sent to the arithmetic processing system 701. The arithmetic processing system 701 detects a defect on the inspection target 200 by obtaining a difference between the inspection image and the reference image (which can also be expressed as difference processing) and performing threshold processing on the difference. The defect detection may be performed by integrating the comparison result using a so-called feature amount. In the arithmetic processing system 701, the dark field images obtained from the upper detection system 800 and the oblique detection systems 100 and 101 that have been sent may be integrated.

  Furthermore, dark field images obtained under different conditions (for example, different optical conditions) may be integrated.

  The result of the defect detection is sent to the display device 702 and displayed as a map in association with the coordinates of the inspection target.

  The inspection target 200 is mounted on the stage 400. The stage 400 moves mainly in the XY directions based on a signal from the control device 703. This movement becomes a scanning operation, and defect detection is performed on the entire surface of the inspection target 200. In the present embodiment, it can also be expressed that the X direction is the scanning direction and the y direction is the feeding direction.

  Note that the defect inspection apparatus may include a so-called review microscope 803 (also referred to as a bright field optical system) and a reference chip 205 for confirming the shape of the linear illumination.

  Next, details of the upper detection system 800 will be described with reference to FIG. In the upper detection system 800, the sensor 802 is particularly likely to generate heat. Therefore, in this embodiment, a wattmeter 802 for measuring the power consumption of the sensor is provided. Also, the sensor unit 802 and the driver unit 2003 that drives the spatial filter 2001 tend to generate heat. Therefore, in this embodiment, a power meter 2004 for measuring the power consumption of the driver unit 2003 is provided. The wattmeters 2002 and 2004 may be provided in the oblique detection systems 100 and 101. Furthermore, the stage 400, the arithmetic processing system 701, the control device 703, and the illumination system 300 are examples of parts that are likely to generate heat other than the upper detection system 800 and the oblique detection systems 100 and 101. Therefore, at least one of the wattmeters 2002 and 2004 may be employed in at least one of the stage 400, the arithmetic processing system 701, the control device 703, and the illumination system 300.

  Next, a flowchart for estimating heat generation in this embodiment will be described with reference to FIG. First, the worker specifies a predetermined place (step 3001). Here, the predetermined place is, for example, at least one of the sensor 8002, the driver unit 2003, the stage 400, the control device 703, and the illumination system 300. The predetermined location may be specified by the control device 703 according to a predetermined program.

  Next, power consumption is measured for each specified predetermined part (step 3002). The heat generation temperature can be expressed most simply as a function of power consumption and time. Therefore, after the power consumption is measured, a heat generation function f (t) is defined for each predetermined part (step 3003). Step 3002 and step 3003 may be performed before the inspection or at the start of the inspection.

  During the inspection, the control unit 703 monitors the time for each specified predetermined part, and starts cooling the predetermined part when a time at which an exothermic temperature that is undesirable for the inspection elapses has elapsed (step 3004). (Step 3005). As a cooling method, the following methods can be considered. (1) Supplying airflow to a heat generating part by a fan (2) If the heat generating part includes a drive unit such as a motor, reduce the number of motors supplying power (3) If the heat generating part includes a processing substrate, (4) Supply a medium with high thermal conductivity (for example, gas) to the heat generating portion. In the case of (1) and (4), in order to prevent undesired dew condensation in the heat generating part, it is desirable that the dew point of the air current and gas is controlled by a dehumidifying agent before supplying to the heat generating part. It is desirable to be cooled to a temperature lower than the atmosphere.

  FIG. 4 is a diagram for explaining the heat generation function f (t). For example, if the time t1 is the time when the temperature T1 that is not desirable for the inspection is reached, even if cooling is started after the time t1, the temperature does not drop rapidly, and the sensor element is destroyed due to heat generation, and the position shift due to thermal expansion Undesirable phenomena occur in inspection such as increase. Therefore, in this embodiment, cooling may be started from time t1 before time t1.

  According to this embodiment, it is possible to prevent a phenomenon that is not desirable for the inspection. Note that the method of estimating heat generation by electrically obtaining power consumption as in the present embodiment is effective for an inspection apparatus having a very limited internal space.

  Next, Example 2 will be described. In Example 1, the heat generation temperature was estimated from the relationship between power consumption and time. In this embodiment, the heat generation temperature is directly measured. In the following description, parts different from the first embodiment will be mainly described. FIG. 5 is a diagram for explaining the present embodiment. A temperature measuring unit 5001 is connected to the sensor 802, and a temperature measuring unit 5002 is connected to the driver unit 2003. As an example of the temperature measuring units 5001 and 5002, a thermocouple or a means for measuring the temperature optically can be considered. Of course, at least one of the temperature measurement units 5001 and 5002 may be adopted as at least one of the stage 400, the control device 703, and the illumination system 300.

  FIG. 6 is a flowchart for explaining the present embodiment. In the present embodiment, the temperature of a predetermined part selected during the examination is measured (step 6001). If the selected predetermined part is equal to or higher than the predetermined temperature (step 6002), the heat generating part is cooled in the same manner as in the first embodiment.

  Even in this embodiment, it is possible to prevent a phenomenon undesirable for the inspection.

  Hereinafter, although the embodiments of the present invention have been described, the present invention is not limited to the embodiments. For example, the heat generating portion may be cooled when the inspection target 200 is replaced. In addition, the heat generation function f (t) may be taken into account the amount of heat released per unit time of the heat generation site.

100, 101 Oblique detection system 200 Inspected object 300 Illumination system 301 Illumination light 400 Stage 701 Arithmetic processing system 702 Display device 703 Control device 802 Sensor 805 Objective lens 809 Imaging lens

Claims (8)

It is possible to select a predetermined part,
Get the power consumption of the selected part,
Measuring time for the selected site;
Determine whether a certain amount of time has passed,
The inspection apparatus, wherein the selected portion is cooled by a cooling unit when a predetermined time has elapsed. The inspection apparatus according to claim 1,
The said cooling part starts cooling, before the said selected site | part produces the heat_generation | fever undesirable for a test | inspection, The inspection apparatus characterized by the above-mentioned. The inspection apparatus according to claim 2,
A sensor for detecting light from the object to be inspected;
A driver unit for driving the sensor,
The inspection apparatus according to claim 1, wherein the predetermined portion includes at least one of the sensor and the driver unit. The inspection apparatus according to claim 3, wherein
The inspection apparatus, wherein the predetermined part includes the sensor and the driver unit. The inspection apparatus according to claim 4,
At least one of a stage on which the inspection target is mounted, a processing unit that detects a defect on the inspection target from a signal of the sensor, and an illumination system that supplies light to the inspection target at the predetermined portion. Inspection apparatus characterized by including two. The inspection apparatus according to claim 5, wherein
The said cooling part supplies a medium with respect to the said selected site | part, The inspection apparatus characterized by the above-mentioned. The inspection apparatus according to claim 6, wherein
The inspection apparatus characterized in that the temperature of the medium is lower than the temperature of the atmosphere around the selected part. The inspection apparatus according to claim 7,
The said cooling part has a dehumidification part for controlling the dew point of the said medium, The inspection apparatus characterized by the above-mentioned.