JPH03114218A - Aligner for wafer periphery - Google Patents

Abstract

PURPOSE:To unnecessitate high illuminance exposure by constituting an output end surface as a ring type shape to illuminate a ring type peripheral region of a reticle containing a reticle pattern, and equipping an optical fiber guiding the light from a light source lamp. CONSTITUTION:The light from a light source lamp 1 is converged by an elliptical converging mirror 2, reflected by a plane reflecting mirror 3, and enters an optical fiber 4. The light which has entered the optical fiber 4 is guided by the optical fiber 4, outputted from the output end surface, and illuminates a reticle 6. The light from a reticle pattern 61 of the illuminated reticle 6 is focused on a wafer W by an imagery lens 5, and the reticle pattern 61 is transferred in the resist on the wafer W. On the output side of the optical fiber 4, element lines are bundled in the form of a sheath so as to illuminate a ring type peripheral region 62 containing the reticle pattern 61, and the output end surface 41 has a ring type shape. Hence the light guided by the optical fiber 4 illuminates only the ring type peripheral part 62, so that useless light is not present.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for forming circuit patterns in the production of ICs, LSIs, and other electronic devices.
To remove unnecessary resist from the periphery of the wafer, which is applied to a semiconductor substrate such as a silicon wafer, or a dielectric, metal, or insulator substrate (collectively referred to as a wafer in this application) through a development process. This relates to exposure of the wafer periphery.

[Conventional technology]

In the manufacturing process of ICs, LSIs, etc., to form fine circuit patterns, a resist is applied to the surface of a silicon wafer, etc., and then exposed.

Next, development is performed to form a resist pattern, and processes such as ion implantation, etching, and lift-off are performed using this resist pattern as a mask.

Usually, resist is applied by a spin code method, in which the resist is poured onto the center of the wafer surface, the wafer is rotated, and the resist is applied to the entire surface of the wafer by centrifugal force.

Exposure for pattern formation is performed by a step-by-step reduction projection exposure apparatus (hereinafter referred to as a stepper). FIG. 4 is a diagram schematically showing a wafer exposed by a stepper. As shown in Fig. 4, the wafer is exposed stepwise to each chip molecule in the pattern of the substrate using a stepper, but as is clear from Fig. cannot accurately and completely draw a circuit pattern. Therefore, the step exposure for the chip molecule p is omitted to increase the exposure throughput 7) for -thick wafers.

In any case, the resist in areas where the circuit pattern is not correctly and completely drawn will remain as unnecessary resist even after development.

The presence of unnecessary resist at the periphery of the wafer, which remains even after development, causes the following problems: Wafers coated with resist are transported through various processing steps and in various ways.

At this time, the periphery of the wafer is mechanically grasped and held.
The periphery of the wafer may rub against the wall of a container such as a wafer cassette. At this time, if unnecessary resist from the periphery of the wafer comes off and adheres to the pattern forming area of the wafer, correct pattern formation will not be possible and the yield will be lowered.

Unnecessary resist around the wafer becomes "dust" and reduces yield, which is a serious problem especially now that integrated circuits are becoming more sophisticated and smaller.

Therefore, as a technology to remove unnecessary resist around the wafer, it is considered that, in addition to the exposure process for pattern formation, a separate exposure is performed to remove unnecessary resist around the wafer in the development process. ing.

[Technical Problems to be Solved by the Invention] As a method for exposing the periphery of the wafer, the following several methods can be considered. FIG. 5 is a diagram illustrating the outline of such a possible wafer peripheral area exposure method.

One method is to connect the light from the light source lamp 1 to the optical fiber 4 while rotating the wafer W, as shown in FIG. 5(a).
0 and irradiates the wafer peripheral area Wp. With this method, it is necessary to expose the resist at a fairly high illuminance and at a fast rotation speed in order not to reduce productivity, but exposing the resist at high illuminance may cause foaming of the resist, etc. As shown in FIG. 5(a), the boundary line Wt between the unnecessary resist at the wafer periphery and the resist at the pattern forming area actually has a step-like shape, but in the wafer periphery exposure method shown in FIG. , it is quite difficult to expose only unnecessary resist at the periphery of the wafer along this stepped boundary line Wt.

Another method is to use a reticle 6 with a reticle pattern formed to expose an unnecessary resist pattern, as shown in FIG. It is. This method may be a contact method or a projection method as shown in FIG. 5(b), but the reticle 6 needs to be illuminated to cover the area where the reticle pattern is formed. In contrast to the periphery of the reticle 6, the light is also irradiated to the center of the reticle 6, so there is a lot of wasted light.Furthermore, the illumination optical system I As a result, the apparatus becomes large-scale, and it becomes difficult to install it in, for example, a resist coating machine or a developing machine.

It is also conceivable to form the shape of the output end face of the optical fiber in the same manner as the unnecessary resist pattern, and to directly image the light from the output end face on the wafer with an imaging lens.
This method is not practical because the image of each strand of the optical fiber is transferred.

[Purpose of the invention]

The present invention was made in consideration of the above-mentioned problems, and in a wafer peripheral area exposure apparatus that exposes unnecessary resist at the periphery of a wafer, ■ there is no need to expose at high illuminance, and ■ there is a step-like boundary line. In line with the above, the objectives are: 1) to be able to expose only unnecessary resist; 1) no wasted light; and 2) to make the device compact.

[Structure of the Invention] In order to achieve the above object, the wafer peripheral exposure apparatus of the present invention includes a light source lamp, a reticle on which a reticle pattern is formed so as to expose resist unnecessary for circuit pattern formation, and an output end surface of the wafer peripheral area exposure apparatus. The reticle is characterized by comprising an optical fiber having a ring shape and guiding light from a light source lamp so as to illuminate only a ring-shaped peripheral area including the reticle pattern of the reticle.

[Effect]

In the wafer peripheral area exposure apparatus of the present invention having the above configuration, the light from the light source lamp is guided by the optical fiber, and is emitted from the ring-shaped output end face to form the ring-shaped peripheral area including the reticle pattern part. Illuminate the area.

Light from the reticle is irradiated onto unnecessary parts of the resist applied to the wafer, and a reticle pattern previously formed as an unnecessary resist pattern is transferred onto the resist.

〔Example〕

Hereinafter, embodiments of the present invention will be invented.

FIG. 1 is a schematic explanatory diagram of a wafer peripheral area exposure apparatus according to an embodiment of the present invention. H is a light source device, 4 is an optical fiber, 5 is a lens, 6 is a reticle, 7 is an imaging lens, and W is a wafer.

FIG. 2 is an explanatory diagram of a reticle illuminated by light from the optical fiber of FIG. Reference numeral 61 indicates a reticle pattern formed to expose only the resist unnecessary for circuit pattern formation, and 62 indicates a peripheral area including the reticle pattern 61.

In FIG. 1, a light source device H includes a light source lamp 1 such as a seat arc type ultra-high pressure mercury lamp, an elliptical condensing mirror 2, a flat reflecting mirror 3, and the like. This light source device H is arranged separately from the main body M of the wafer peripheral area exposure apparatus shown by the dotted line. Therefore, the main body M can be designed compactly, and can be easily placed in a narrow space, such as when mounted on an organic lens.

In Fig. 1, light from a light source lamp 1 is transmitted to an elliptical condenser mirror 2.
The light is focused by the plane reflector 3 and then enters the optical fiber 4. The light incident on the optical fiber 4 is guided by the optical fiber 4 and exits from the output end face, illuminating the reticle 6. Then, the light from the illuminated reticle pattern 61 of the reticle 6 is directed onto the wafer W by the imaging lens 5, and the reticle pattern 61 is transferred to the resist on the wafer W.

Here, the output side of the optical fiber 4 shown in FIG. 1 has a ring-shaped peripheral area 62 including the reticle pattern 61 shown in FIG.
The wires are bundled in ambush to illuminate the output end face 41.
has a ring shape. Therefore, the light guided by the optical fiber 4 illuminates only the ring-shaped peripheral area 62 shown in FIG.
Among the resist coated on the resist, several parts of the central chip part are also unnecessary and the exposure by the stepper may be omitted, so the reticle pattern 61 and the fiber 4 are configured so that these parts are also exposed at the same time. Also good, also
If there is a separate part to be held by a wafer clamp or the like in a later process, the reticle pattern 61 and the fiber 4 may be configured so that the resist of the held part is also exposed. However, in this embodiment, unlike the method shown in FIG. 3(a), a reticle transfer method is used, so that only unnecessary resist can be exposed freely. Lens 5 is for making light from reticle 6 enter imaging lens 7 correctly.

FIG. 3 is a schematic explanatory diagram of another embodiment of the present invention. As shown in FIG. 3, instead of the lens 5 shown in FIG.
The output side of the optical fiber 4 is manufactured so as to be inclined toward the center of the ring, so that the light from the reticle is correctly incident on the imaging lens. Although manufacturing the optical fiber 4 is slightly more difficult than in the embodiment shown in FIG. 1, since the lens 5 is not required, the cost can be reduced and the device can be made more compact.

In the embodiment shown in FIGS. 1 and 3, the reticle pattern 61 is imaged onto the wafer W using the imaging lens 7 to expose the wafer periphery, so the boundary shown in FIG. It becomes possible to expose the line Wt sharply and with good darkness. However, exposure may be performed using a contact method or a proximity method without using the imaging lens 7.

By the exposure described above, it is possible to completely omit the step exposure for the chip component p shown in FIG. 4 in the exposure process for forming a circuit pattern using a stepper, and it is expected that the throughput in the exposure process will be improved.

〔Effect of the invention〕

As explained above, the wafer peripheral exposure apparatus of the present invention has the following features:
A light source lamp, a reticle on which a reticle pattern is formed so as to expose resist unnecessary for forming a circuit backbone, and a ring-shaped emitting end surface having a ring-like shape so as to illuminate a ring-shaped peripheral area including the reticle pattern of the reticle. Since it is equipped with an optical fiber that guides the light from the light source lamp,
It has the following effects.

■There is no need to expose at high illuminance.

■Only unnecessary resist can be exposed along the stepped border.

■No wasted light.

■The device can be made compact.

[Brief explanation of drawings]

FIG. 1 is a schematic illustration of a wafer peripheral exposure apparatus according to an embodiment of the present invention, FIG. 2 is an illustration of a mask illuminated by light from the optical fiber of FIG. 1, and FIG. A schematic illustration of another embodiment of the invention, FIG. 4 is a diagram schematically showing a wafer exposed by a stepper, and FIG. 5 is a diagram illustrating an outline of a possible wafer peripheral exposure method. In the figure: 1 - - - - - - Light source lamp 4 - - - - - - Optical fiber 41 - - Output end face of optical fiber 6 - - -
--Reticle 61 ------ Reticle pattern 62 ---
... Peripheral region 7 --- Imaging lens W --- Wafer Wp --- Shows the wafer peripheral portion. Fig. Fig. (a no. 5 Fig. (b)

Claims (1)

[Claims] A light source lamp, a reticle on which a reticle pattern is formed so as to expose resist unnecessary for circuit pattern formation, and an emitting end face having a ring shape so as to illuminate a ring-shaped peripheral area including the reticle pattern of the reticle. 1. A wafer peripheral area exposure apparatus, comprising: an optical fiber that guides light from a light source lamp.