JPH03241775A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress processing defects caused by damages on the rear of a substrate by a method wherein the damage and dust are buried in a protective film on the rear side of the substrate and the damages and dusts are removed with the protective film immediately before a rear exposure process. CONSTITUTION:If damages 41 are produced on a light transmitting substrate 40 before a rear exposure process, a protective film 43 is applied to the rear side of the substrate immediately before a positive type photoresist layer 42 is applied to the surface of the substrate and the rear exposure process is carried out. After that, the photoresist layer is developed and semiconductor layers are etched and source electrodes, drain electrodes, picture element electrodes, etc., are formed to complete an active matrix array. Thus, by applying the protective film to the rear, resist remnants (and etching defects) caused by the rear damages can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a semiconductor device having a semiconductor element or the like on a transparent substrate. For example, there are methods for manufacturing semiconductor devices that have switching elements such as thin film transistors and pixel electrodes in a matrix (referred to as active matrix arrays in this case), and liquid crystal display devices and image reading devices that use this active matrix array to drive liquid crystals. This relates to sensors for use in other applications.

A method for manufacturing an active matrix array for a liquid crystal display device will be described below as an example.

Conventional technology First, a liquid crystal display device will be explained.

FIG. 4 is a circuit diagram of a main part of a liquid crystal display device using an active matrix array equipped with a signal holding capacitor. The display section surrounded by the broken line ABCD has a large number of pixels (the part surrounded by the broken line I) repeated in a matrix. A thin film transistor (hereinafter referred to as TPT) 2 is built into each pixel, and the gate electrode of the TPT is connected to a scanning signal wiring 7, the source electrode is connected to an image signal wiring 8, and the drain electrode is connected to a signal holding capacitor 3. and is connected to the pixel electrode 4. The liquid crystal 6 is sandwiched between the counter electrode 5 and the pixel electrode 4 and driven. The counter electrode 5 is composed of one wide electrode that covers the entire display section. The signal holding capacitor 3 is also connected to a common wiring 9 (the signal holding capacitor 3 and the common wiring 9 may be omitted). 10, 11, and 12 are peripheral circuits. Broken line ABC
Of the display section surrounded by D, the part other than the liquid crystal 6 and the counter electrode 5 is built on a substrate such as glass as an active matrix array (note that the number of wiring is small in the drawing, but it is used for TV display etc. In some cases, the number of scanning signal wirings 7 and image signal wirings 8 exceeds several hundred). Regarding the above, see, for example, Tadashi Matsumoto, Electronic Display Device (1984) Ohmsha.

When creating an active matrix array for use in such liquid crystal display devices, it is necessary to remove the front surface of the transparent substrate [the active matrix array components (TPT, wiring, electrodes, etc.)] for the purpose of improving performance and simplifying the process. In some cases, the photoresist coated on the substrate surface on which the substrate will be created is exposed from the back side of the substrate (hereinafter this process is referred to as the back exposure process).After this back exposure process, the photoresist is developed. It is known that this photoresist is used to process the constituent material on the front side of the substrate.

A conventional method of manufacturing an active matrix array using this backside exposure process will be explained with reference to FIG. This figure is a schematic cross-sectional view of the process, and T in one pixel area.
The PT and pixel electrode portions are shown. First, transparent substrate 2
0 (Corning 7059 glass), the gate electrode 2
1 and scanning signal wiring (not shown) are formed using a Cr thin film [FIG. 5(a)], and then a gate insulating film 22 (S + N x i silicon nitride) is formed using a plasma CVD method.
A semiconductor layer 23 (aSi; amorphous silicon) and a low resistance semiconductor layer 24 (n+a-3i; phosphorus-doped amorphous silicon) are deposited [FIG. 5(b)]. After that, a positive type photoresist 25 is applied and the photoresist is exposed using a back exposure process [FIG. 5(C)L] After that, the photoresist is developed and the semiconductor layers (23 and 24) are etched [FIG. 5 (d)]. And transparent conductive film (I
The source electrode 26, drain electrode 27, pixel electrode 28, and image signal wiring (not shown) are formed using a TO thin film (FIG. 5(e)), and the low-resistance semiconductor layer in the channel portion is etched. By doing so [FIG. 5(f)], an active matrix array is formed, and a liquid crystal display device with a greatly simplified process is realized using this active matrix array (for example, see Yomura et al. Other "Full color LCD DJ with 2 mask a-3i TFT.

1989 Television Society National Conference Preliminary Lectures P, 7
(see 7). In addition to this, a method has also been proposed in which a negative photoresist is subjected to a backside exposure process to process the constituent material on the front side of the substrate.

Problems to be Solved by the Invention The backside exposure process is an excellent process with high utility value. On the other hand, when using this process, if there are gores or scratches on the back surface of the substrate, the photoresist will be underexposed in those areas, and depending on the degree of this underexposure, processing defects such as etching defects will occur. For example, if a backside exposure process is performed on the positive photoresist 33 with dust 31 and scratches 32 on the transparent substrate 30 as shown in FIG. 6(a), when it is developed, the exposure Resistance 34 occurs due to shortage. If etching is performed with this resist remaining, the semiconductor layer 35 will remain in unnecessary areas [FIG. 6(b)]. When carrying out a method of manufacturing a semiconductor device using a backside exposure process as described above, process control to reduce scratches and scratches on the backside of the substrate becomes a very important issue. In the case of scratches, it is possible to avoid the problem by thorough cleaning, but cleaning has no effect on scratches that have already occurred.

The present invention has focused on this problem and aims to suppress the occurrence of processing defects caused by scratches (which may include dust) on the back surface of the substrate.

Means for Solving the Problems The technical means of the present invention for solving the above problems is as follows: (a) Forming a protective film on the back side of the pre-warmed translucent substrate (this is done at the beginning of the entire process). (preferably), the protective film is removed immediately before the backside exposure process.

(b) A protective film is formed on the back surface of the transparent substrate, and a back surface exposure process is performed through the protective film.

(C) A liquid layer is formed on the back side of the transparent substrate, and a back side exposure process is performed through the liquid layer.

It is.

Effect According to the above means (a), since scratches and dents are generated on the protective film on the back side of the substrate, the scratches and dents can be easily removed together with the protective film immediately before exposure of the back side. Further, according to the above means (b) to (C), reflection due to scratches during exposure can be suppressed (it is optimal to use a protective film or liquid layer having a refractive index similar to that of the transparent substrate).
. These methods reduce the amount of resist remaining during the backside exposure process caused by scratches and gore ξ on the backside of the substrate, thereby suppressing the occurrence of defects.

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

FIG. 1 is an explanatory diagram of the first embodiment of the present invention, and shows a schematic process sectional view (part) for explaining the method for manufacturing an active matrix array (the active matrix array shown in FIG. 5). (I am creating something with almost the same configuration as the array). The figure shows a case where a scratch 41 is generated on the transparent substrate 40 before the backside exposure process [Figure 1 (
a)]. Therefore, immediately before coating the positive photoresist 42 on the front surface, a protective film 43 [any film that transmits ultraviolet light for exposure may be used, such as glass resin (manufactured by Showa Denko),
NHC (manufactured by Yasan Kagaku Kogyo), etc., which can be used] was applied to the back side of the substrate, and the back side exposure process was performed [Figure 1 (b)].
. Thereafter, the photoresist was developed and the semiconductor layer was etched [FIG. 1(C)]. Then, in the same manner as shown in FIG. 5, the source electrode, drain electrode, pixel electrode, etc. were formed to complete the active matrix array. In this example, by applying the protective film 43, the occurrence of resist residue (and etching defects) caused by scratches on the back surface was reduced.

Next, a schematic process sectional view (partial) for explaining the method for manufacturing an active matrix array according to the second embodiment of the present invention is shown in FIG. (creating an active matrix array). In the case of this example, a protective film 51 was applied to the back side of the transparent substrate 50 at the beginning of the manufacturing process. After this, the same steps as in the conventional example up to FIG. 5(c) were performed. In this case, most of the gobs 52 and scratches 53 that occur on the back side of the substrate will occur on the surface of the protective film 51 [Fig. 2 (a)
]. Therefore, after removing the dust 52 and scratches 53 together with the protective film 51, a positive type photoresist 54 was applied, and a backside exposure process was performed [FIG. 2(b)]. After this, the photoresist was developed and the semiconductor layer was etched [Figure 2 (
C)]. Then, in the same manner as shown in FIG. 5, the source electrode, drain electrode, pixel electrode, etc. were formed to complete the active matrix array. In this example, by using the protective film 51, the occurrence of resist residue (and etching defects) generated in the backside exposure process was reduced.

Next, a schematic process sectional view (partial) for explaining the method for manufacturing an active matrix array according to the third embodiment of the present invention is shown in FIG. (creating an active matrix array). 1st
As in the embodiment shown in FIG. 3, a scratch 61 is generated on the transparent substrate 60 before the backside exposure process [FIG. 3(a)].

Therefore, after applying positive photoresist 62 on the front surface,
The entire substrate was left still in a container 63 filled with a liquid 64 (for example, water, which can be carried out with a liquid that has little effect on other constituent materials), and the back side exposure process was performed with a thin liquid layer interposed therebetween. [Figure 3(b)]. After this, the photoresist is developed,
The semiconductor layer was etched [FIG. 3(C)]. Then, in the same manner as in FIG. 5, the source electrode, drain electrode, pixel electrode, etc. were shaped to charge the active matrix array. In this example, by exposing through the liquid 64, the occurrence of resist residue (and etching defects) caused by scratches on the back surface was reduced.

Effects of the Invention As described above, by employing the means of the present invention in a method of manufacturing a semiconductor device having a backside exposure step, the amount of resist remaining during the backside exposure step can be significantly reduced.
It is possible to suppress the occurrence of defects such as etching residue in unnecessary parts, and improve yield.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are steps for explaining a method for manufacturing a semiconductor device (active matrix array) according to a first embodiment, a second embodiment, and a third embodiment of the present invention, respectively. 4 is a circuit diagram of a main part of a liquid crystal display device using an active matrix array having thin film transistors, FIG. 5 is a sectional view of a process of a conventional semiconductor device W (active matrix array), and FIG. 6 is a back side of a substrate. FIG. 3 is an explanatory diagram of the occurrence of defects due to dust and scratches generated in the product. 20, 30.40.50.60...Transparent substrate, 31.52...Trash, 32.4L 53.6
1... Scratch, 25.33.42°54,62.
...Positive photoresist.

Claims (4)

[Claims] (1) A step of depositing a photoresist on the front side of a light-transmitting substrate, a step of exposing the photoresist by irradiating light from the back side of the light-transmitting substrate, and a step of passing through the exposure step. A step of processing components on the front side of the light-transmitting substrate using a photoresist, and applying a protective film on the back side of the light-transmitting substrate before the exposure step from the back side. A method for manufacturing a semiconductor device, comprising a step of forming a semiconductor device. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the protective film is made of a material that transmits light used in the exposure step from the back side. (3) The method for manufacturing a semiconductor device according to claim (1), further comprising the step of removing the protective film before the step of exposing from the back side. (4) a step of depositing a photoresist on the front side of the light-transmitting substrate; a step of bringing a liquid into contact with at least the back side of the light-transmitting substrate; and a step of applying a photoresist to the light-transmitting substrate through the liquid. A semiconductor device comprising a step of exposing the photoresist by irradiating light from the back side of the semiconductor device, and a step of processing components on the front side of the transparent substrate using the photoresist that has undergone the exposure step. Production method.