JPH0353541A - Semiconductor wafer surface inspection device - Google Patents

Abstract

PURPOSE:To make it possible to accurately perform a decision on the size of each foreign substance by a method wherein the incident angles of light are made constant to any position of the surface of a semiconductor wafer and irregularity in scattered light is inhibited. CONSTITUTION:An illuminator 5 directs light from a light source 51 to a hexagonal prism 55 through an attenuation filter 54A. This prism 55 is controlled rotationally by a control mechanism. As a result, the light is vertically shifted with its optical axis kept parallel in a vertical plane, and it is emitted sequential to predetermined positions on a semiconductor wafer 2 through a slit plate 56 and first and second reflecting mirrors 54B and 54C. In such a way, by making light scan in almost parallel to a facet part 12 in the wafer 12, the incident angles theta1 to theta2 of light to positions X1 to X3 to be inspected of a light irradiation region 7 of the wafer 2 are made constant and an inspection is conducted in order.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor wafer surface inspection apparatus for inspecting the presence or absence of foreign matter on the surface of a semiconductor wafer based on the intensity of light scattered by the foreign matter. [Prior Art] When manufacturing a semiconductor device, for example, a desired device shape or a necessary film is formed on the surface of a semiconductor wafer, and the process is moved to the next step. When a semiconductor wafer is transported, foreign matter such as minute particles ξ may adhere to the surface of the wafer. Since these foreign substances can cause various problems in subsequent processes, conventionally the surface of the semiconductor wafer is inspected before proceeding to the next process. For example, the device shown in FIG. 6 is known as a surface inspection device for semiconductor wafers. In the diagram! 4 is a wafer rotation motor that rotationally drives the table 3 on which the semiconductor wafer 2 is mounted; 4 is a wafer feeding mechanism that linearly moves the wafer rotation motor l in one direction; A light irradiator 6 for irradiating the surface of the semiconductor wafer 2 is a light receiving section that receives light scattered by foreign matter on the surface of the semiconductor wafer 2. The light irradiator 5 includes at least a light source 51 such as a semiconductor laser, and an optical system (not shown) that focuses the light emitted from the light source 51 onto the semiconductor wafer 2. Also,
The light receiving section 6 includes an integrating sphere 6l whose inner surface is mirror-finished, and an integrating sphere 6l.
A signal processing circuit (not shown) detects the presence or absence of foreign matter based on the electric signal output from the photomultiplier tube 62 according to the amount of light received. The size of foreign objects, the number of foreign objects, etc. are determined.

The above-mentioned light irradiator 5 is attached to a predetermined location of the integrating sphere 61, and the irradiator 5 applies light to the semiconductor wafer 2.
An opening 63 is provided for emitting to the outside the light that is specularly reflected by the semiconductor wafer 2 when irradiated onto the semiconductor wafer 2. This surface inspection device draws a spiral trajectory on the surface of the semiconductor wafer 2 by keeping the light emitting direction of the light irradiator 5 constant and rotating the semiconductor wafer 2 while feeding it linearly in one direction. In this way, semiconductor wafer 2
This is to inspect each position on the surface. however,
The above-mentioned surface inspection device requires two wafer rotating mokes 1 and a wafer feeding mechanism 4 to rotate and feed the semiconductor wafer 2, which makes the device complicated and increases the cost of the device. .

On the other hand, there is a semiconductor wafer surface inspection apparatus as shown in FIG. In the figure, parts and portions corresponding to those shown in FIG. 6 are given the same reference numerals. This device is
By performing light scanning across the surface of the semiconductor wafer 2 in one direction, the light irradiation position on the semiconductor wafer 2 is sequentially changed, and by feeding the semiconductor wafer 2 linearly in one direction, the surface of the semiconductor wafer 2 is Inspection is performed by sequentially changing the light irradiation position. This surface inspection apparatus includes a light irradiator 5 whose light emission direction can be arbitrarily set variably, a feeding means (not shown) that linearly feeds the semiconductor wafer 2 in the direction of the arrow, and a means for detecting scattered light from the semiconductor wafer 2. It includes at least a light receiving section 6 that receives light.

The light irradiator 5 here emits the light emitted from the light #5l? JW
A polarizing mirror 53 is provided to appropriately polarize the light focused by several optical elements 52A to 52C. In addition, the light receiving section 6
is a condensing mirror 61 (corresponding to the integrator in FIG. 6) that condenses light scattered by foreign objects on the semiconductor wafer 2;
A configuration comprising at least a photomultiplier tube 62 identical to that in FIG. 6, and a plurality of optical fibers 64, one end of which is placed at the focal point of the condensing mirror 6l and the other end of which is placed on the photomultiplier tube 62 side. It is. We will explain the inspection procedure using this device. The semiconductor wafer 2 is fed linearly at a predetermined speed in the direction of the arrow in the figure by the feeding means. During this transfer, on the surface of the semiconductor wafer 2, a vertical plane perpendicular to the feeding direction of the wafer 2, for example, a facet portion 2 of the semiconductor wafer
Light is irradiated onto an area parallel to l by sequentially changing the light output direction using a polarizing mirror 53. By the way, if there is no foreign matter such as dust at the inspection position, there will be no scattering of light and total reflection will occur at an angle that corresponds to the angle of incidence of the incident light. However, if there is foreign matter such as dust at the inspection position, the light will not be scattered. is defeated without being fully reflected. In other words, the electrical intensity distribution of the scattered light in the light irradiation area 7 is detected by one optical scan, and based on this intensity distribution, the foreign matter
A signal processing circuit (not shown) determines whether there are any foreign objects, the size of the foreign objects, the number of foreign objects, etc. In this way, by performing optical scanning across the surface of the semiconductor wafer 2 in one direction, the light irradiation position on the semiconductor wafer 2 is sequentially changed, and by feeding the semiconductor wafer 2 linearly in one direction. The inspection progresses by sequentially changing the optical scanning position on the surface of the semiconductor wafer 2,
Rotating motion of the semiconductor wafer 2 is eliminated.

[Problem to be solved by the invention] By the way, the semiconductor wafer surface inspection apparatus shown in FIG.
There are the following problems.

11p, since the incident angle of light at each position in the longitudinal direction in the band-shaped light beam area 7 of the semiconductor wafer 2 is not constant and differs, even if the same foreign object is present at each position, the incident angle of light will be different. Due to the difference in angle, the directions of light scattering by each foreign object become different, making it particularly difficult to accurately determine the size of the foreign object.

Therefore, if the polarization ξ beam 53 is moved away from the semiconductor wafer 2 and the distance between the two is made as large as possible to approximate the incident angle of the light to each inspection area as much as possible, the scattering direction of the light will vary. Although it is possible to suppress this, in this case, the luminous intensity length between the polarizing mirror 53 and the semiconductor wafer 2 becomes long, resulting in an increase in the size of the device. In particular, in order to cope with the increase in the diameter of the semiconductor wafer 2 due to recent technological innovations, the arrangement of the polarizing mirror 53 becomes a bottleneck, forcing the device to become even larger.

The present invention was devised in view of these circumstances, and aims to enable accurate inspection while reducing the size of the device. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a feeding means for linearly feeding a semiconductor wafer in a horizontal position in one direction, and a means for linearly feeding a semiconductor wafer in one direction on the surface of the semiconductor wafer. A light irradiation means that irradiates light along a vertical plane orthogonal to the surface of the semiconductor wafer, and a light intensity distribution of scattered light from the light irradiation area on the surface of the semiconductor wafer is detected, and based on this light intensity distribution, foreign matter on the back surface of the semiconductor wafer is detected. A semiconductor wafer surface inspection apparatus having a configuration including detection means for determining size, number, etc. has the following configuration.

In the semiconductor wafer surface inspection apparatus of the present invention, the light irradiation means makes the light obliquely incident on the surface of the semiconductor wafer and makes the incident angle of the light constant for each position of the light irradiation area on the semiconductor wafer. It is characterized by being equipped with optical means. [Operation] In the above configuration, since the optical means provided in the light irradiation means makes the incident angle of light to all inspection positions of the semiconductor wafer constant, variations in the scattering direction of light due to foreign matter at each inspection position are suppressed. As a result, the intensity of the light scattered by foreign objects is almost uniform regardless of the position on the semiconductor wafer. Moreover, as explained in the examples, the optical means consists of optical elements such as prisms and cylindrical lenses, and these do not have any close relationship with the relative position to the semiconductor wafer. The arrangement position of this optical means with respect to the semiconductor wafer can be set arbitrarily, and it becomes possible to design the device for miniaturization.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

An embodiment of the present invention is shown in Figs. 1 to 3.
In the figure, the parts shown in Fig. 7 of the conventional example. Corresponding parts are given the same reference numerals and their explanations will be omitted.

The configuration of this embodiment differs from the conventional example shown in FIG. 7 as follows:
It is mainly a light irradiator 5.

That is, the light irradiator 5 allows the emitted light from the light aSl to enter the hexagonal prism 55 via the attenuation filter 54A, and controls the rotation of the hexagonal prism 55 by a control mechanism (not shown), so that the light emitted from the light aSl is emitted in the vertical plane. The slit plate 56 and the first and second
The semiconductor wafer 2 is
It is configured so that the light is sequentially incident on predetermined locations on the surface of the. By changing the rotational phase of the hexagonal prism 55, this light irradiator 5 can emit light with a predetermined time difference in a vertically shifted parallel manner. People are now shooting at people. The angle of incidence (θ, ~θ, in Fig. 3) is set to, for example, 5 to 6 degrees. That is, the optical means described in the claims includes the hexagonal prism 55 and the slit plate 56. In the figure, 8 is a control circuit that drives and controls the light source 5l, and 9 is a signal processing circuit that processes the output signal from the light receiving section 6. The detection means described in the claims includes a light receiving section 6 and a signal processing circuit 9. Further, 10 is a second reflection mirror 54
C is a beam modulator that modulates light by swinging, and 11 is a sensor that detects the position of the semiconductor wafer 2 with respect to the main body of the surface inspection apparatus. In the light receiving section 6, a conventional photomultiplier tube 6
2, a light receiving element array 65 is used. Next, we will explain the inspection procedure. The semiconductor wafer 2 is transported by a feeding means (not shown) (for example, a structure using a conveyor belt or a structure using a pole screw).
is sent at a predetermined speed in the direction of the arrow, that is, in one direction perpendicular to the longitudinal direction of the face/knot portion 2l. At the same time, light is sequentially irradiated on the surface of the semiconductor wafer 2 along a vertical plane that is substantially parallel to the facet portion 21 of the semiconductor wafer 2 . in particular,
First, when the hexagonal prism 55 is in the position shown in FIG. 2 tal, the light incident from the light source 51 is emitted downward and parallel to its optical axis, forming an optical path as shown by ■ in FIG. 3. , is incident on the first inspection position X1 on the semiconductor wafer 2. Then, when the hexagonal prism 55 is in the position shown in FIG. The light enters the second inspection position Xs in Ueno\2.Furthermore, when the hexagonal prism 55 is in the position shown in FIG. The light is then incident on the third inspection position H x s on the semiconductor wafer 2 as an optical path as shown by ■ in FIG.

In this way, each inspection position of the light irradiation area 7 of the semiconductor wafer 2 (Xl shown in FIG.
-Xs ) with respect to the incident angle of light (θ shown in Figure 3, ~θ
3) is kept constant.

In addition, presence or absence of foreign matter. Size of foreign object. To determine the number of foreign objects,
Since this is carried out in substantially the same manner as the conventional example shown in FIG. 7, the explanation here will be omitted.

Subsequently, scanning with light irradiation is performed using the same procedure as described above, and inspection is sequentially performed.

Further, FIGS. 3 and 4 show other embodiments of the present invention. This embodiment is different from the above embodiments in that two cylindrical lenses 57 are used instead of the hexagonal prism 55. 58 is used. A concave cylindrical lens 57 is arranged on the upstream side in the direction of light incidence, and a convex cylindrical lens 58 is arranged opposite to it on the downstream side in the direction of light incidence. light source 5
The optical east diameter of the light emitted from l is expanded by a predetermined magnification. These two cylindrical lenses 57. The light expanded by the slit plate 58 is shaped into a vertically elongated band shape so as to irradiate one row of the inspection required portions of the semiconductor wafer 2 at once. Note that this semiconductor wafer 2
The length of the band-shaped light incident on both cylindrical lenses 57. 58, the slit size of the slit plate 56, or the reflection angle by the second reflection ξ roller 54C, etc., it is possible to set the reflection angle appropriately. Also in this case, since each light beam of the band-shaped light beam is parallel light, the incident angle of each light beam with respect to the semiconductor wafer 2 is constant. [Effects of the Invention] As described above, - According to the present invention, since the angle of incidence of light is kept constant at any position on the surface of a semiconductor wafer and variations in scattered light are suppressed, it is particularly easy to determine the size of foreign particles. can be done accurately. Moreover, since there is no need to place the optical means for making the incident angle of light constant at a position far away from the semiconductor wafer, the degree of freedom in design is increased compared to conventional systems, and the device can be made more compact. Become.

[Brief explanation of drawings]

1 to 3 relate to an embodiment of the present invention, and FIG. 1 is a perspective view showing a schematic configuration of a semiconductor wafer surface inspection apparatus, and FIG. The explanatory diagram used, FIG. 3, is an explanatory diagram showing the optical path for irradiating the semiconductor wafer. FIGS. 4 and 5 relate to other embodiments of the present invention, and FIG. 4 is a diagram corresponding to FIG. 1. , FIG. 5 is an explanatory diagram used to explain the operation during light irradiation. Also, FIGS. 6 and 7 relate to two different conventional examples,
Both are perspective views showing a schematic configuration. 2...Half 4-piece wafer, 5...Hikarijiki, 55
...Hexagonal prism, 56...Slit, 5
7.58... Cylindrical lens, 6... Light receiver, 7... Light irradiation area.

Claims (1)

[Claims] (1) A feeding means for linearly feeding a semiconductor wafer in a horizontal position in one direction, a light irradiation means for irradiating light along a vertical plane orthogonal to the feeding direction of the wafer on the surface of the semiconductor wafer, and In a semiconductor wafer surface inspection apparatus comprising: a detection means for detecting a light intensity distribution due to scattered light from a light irradiation area and determining the size and number of foreign particles on the semiconductor wafer surface based on this light intensity distribution; , characterized in that the light irradiation means includes an optical means that makes the light obliquely incident on the surface of the semiconductor wafer and makes the incident angle of the light constant for each position of the light irradiation area on the semiconductor wafer. Surface inspection equipment for semiconductor wafers.