JPH03289118A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make the accurate superposition of patterns possible and to enable forming a semiconductor device at a high yield by making a substrate forming a semiconductor layer and a transparent supporting substrate constituting a photomask from materias having the same or substantially the same coefficients of thermal expansion. CONSTITUTION:The same fused quartz as that of SOI subsrate 1 is used as a transparent bearing substrate 6 in a photomask 5. A light-screening Cr film 7 patterned in the manner of corresponding to a gate electrode pattern is provided on the transparent supporting substrate 6, and after this photomask 5 is positioned by the use of an alignment mark, a resist-exposure light 9 is thrown on the photomask to form the latent image of a pattern in a photoresist 4. Further, the coefficients of thermal expansion of respective substrates are made the same or the coefficient of thirmal expansion of one substrate is set within the range of + or -10% of that of the other substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device using photoetching.

[Prior Art] Traditionally, when semiconductor devices are formed on silicon wafers, about 10 photomasks are used to sequentially repeat patterning (photolithography process) and diffusion to achieve desired impurity diffusion. A semiconductor device with a structure was formed.

In that case, the pattern of each photomask needs to be accurately superimposed on the pattern on the silicon wafer formed by the photomask in the previous process.

[Problems to be Solved by the Invention] However, the coefficient of thermal expansion of a silicon wafer is approximately 2.
6X 10-'/degree, while glass commonly used as a transparent support substrate for a food mask is about 9.5X 10-''/degree.

Therefore, when exposing and printing using two photomasks in front of each other, sometimes a 4-inch wafer (
A pattern shift of 1.4 μm occurs at both ends of the diameter of approximately 100 m (11+). This greatly affects variations in device characteristics and yield.

Therefore, temperature control is an important point for exposure equipment.
As a result, problems have arisen, such as the increased cost of the equipment and the burden of maintenance.

Furthermore, this problem becomes an obstacle to increasing the diameter of wafers and miniaturizing devices.

[Means for Solving the Problems 1] The method for manufacturing a semiconductor device of the present invention involves applying a photosensitive material to a semiconductor layer on a substrate, and applying the photosensitive material through a photomask in which a predetermined pattern is formed using a light-shielding material on a transparent support substrate. A method for manufacturing a semiconductor device in which the photosensitive material is irradiated with light to form a predetermined photosensitive material pattern and photoetched, the substrate and the transparent supporting substrate being the same or substantially the same. It is characterized by being made of a material with a high coefficient of thermal expansion.

[Function] In the present invention, the substrate forming the semiconductor layer and the transparent support substrate forming the photomask are made of materials with the same or substantially the same coefficient of thermal expansion. This prevents misalignment between the substrate coated with the transparent material and the transparent support substrate, thereby preventing pattern misalignment.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

This example describes the present invention as an SOI (Silicon 0
This is used in the manufacturing process of semiconductor devices using nInsulator) technology.

FIG. 1 is an explanatory diagram showing an embodiment of the method for manufacturing a semiconductor device of the present invention.

In the same figure, 1 is SO which becomes the substrate forming the semiconductor layer.
I-substrate (Silicon On Insulating)
A Si semiconductor layer 3 with a thickness of 0.1 μm is formed on a fused silica 2 with a thickness of 525 gm. Although not shown, a thermal oxide film is formed on the Si semiconductor layer 3 to a thickness of 0.05 μm, and a gate electrode W Si x is formed thereon to a thickness of 0.2 μm. 4 is a photoresist.

The process described here is a post-process of the photolithography process in which the Si semiconductor layer is etched into islands in order to separate the elements, and an electrode pattern for photolithography of the gate electrode is applied to the surface. This is a photolithography process in which the photoresist 4 is printed.

In the photomask 5, the same fused quartz as the SOI substrate 1 is used as a transparent support substrate 6 serving as a transparent support base. The thickness of the transparent support substrate 6 was about 2 mm, and a pattern was formed on the transparent support substrate 6 to correspond to the gate electrode pattern. A light-shielding Cr film 7 having a thickness of approximately 0.1 μm is provided. After this photomask 5 is positioned using the alignment marks from the previous process, it is illuminated with resist exposure light 9 to form a latent image of a pattern on the photoresist 4.

The exposure apparatus used in this example is a 1-magnification type exposure apparatus that exposes a photomask and a wafer substrate (SOI substrate in this example) in close contact with each other or in close proximity.

Note that 8 is a lens that converts the emitted light from the light source into parallel light.

In this example, the main substrate material of both the SOI substrate and the photomask is the same fused silica, and each has a thermal expansion coefficient of 0.55 x 10-6/degree.
Even if the temperature varies between photolithography steps, both expand and contract with the same dimensions, so no relative total pitch error occurs.

In other words, by aligning the photomask at the correct position between two separate points on the SOI substrate, it becomes possible to accurately overlap the photomask pattern and the SOI substrate pattern over the entire surface of the SOI substrate, allowing for accurate formation of minute devices. can be done.

Furthermore, the present invention is applied to the formation of large-area, low-cost devices such as thin film transistors (TPT) for contact-type image sensors, and Corning's 7059 glass is used as the transparent insulating substrate, and a photomask material is used. However, when an emulsion mask was formed using Corning Co., Ltd. 7059 glass as a support substrate and used for pattern registration, good pattern overlay was achieved despite the large area of 300 mm. Here, a mirror projection type 1x exposure device was used as the exposure device.

In addition, in the present invention, for the purpose of preventing pattern misalignment caused by differences in thermal expansion coefficients, the thermal expansion coefficient of the substrate to which the photosensitive material is coated and the thermal expansion coefficient of the transparent support substrate serving as the photomask must match. However, the surrounding substrate may be made of a material having substantially the same coefficient of thermal expansion. In other words, even if misalignment occurs between the substrate on which the photosensitive material is coated and the transparent support substrate, it is possible to use materials with different coefficients of thermal expansion as long as it does not affect the characteristics of the semiconductor device to be manufactured. good. Preferably, the coefficient of thermal expansion of one substrate is within the range of ±10% of the coefficient of thermal expansion of the other substrate.

Furthermore, in the above examples, transparent materials (fused silica, glass) were used for both the substrate on which the photosensitive material is applied and the transparent support substrate that becomes the photomask. Opaque materials may be used as appropriate.

[Effects of the Invention] As explained in detail above, according to the method for manufacturing a semiconductor device of the present invention, accurate pattern overlay is possible without temperature control of the exposure equipment, and large-area semiconductor devices can be manufactured. Alternatively, it becomes possible to form ultra-fine semiconductor devices with high yield.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the method for manufacturing a semiconductor device of the present invention. 1: sOI substrate, 2: Fused silica, 3: Si semiconductor layer, 4
: Photoresist, 5: Photomask, 6: Transparent support substrate, 7: Cr film, 8 Ni lens, 9 Ni resist exposure light.

Claims (2)

[Claims] (1) A photosensitive material is applied to a semiconductor layer on a substrate, and the photosensitive material is irradiated with light through a photomask in which a predetermined pattern is formed using a light-shielding material on a transparent support substrate. 1. A method of manufacturing a semiconductor device in which a pattern is formed and photoetching is performed, the method comprising forming the base and the transparent supporting base using materials having the same or substantially the same coefficient of thermal expansion. (2) The method for manufacturing a semiconductor device according to claim 1, wherein, regarding the base body and the transparent support base, the coefficient of thermal expansion of one base body is within a range of ±10% of the coefficient of thermal expansion of the other base body. Production method.