JPH04178633A - Formation of semiconductor circuit - Google Patents

Abstract

PURPOSE:To allow the transfer of circuits without using a costly polishing device by sticking a 1st substrate which is formed of the circuits with a 1st film or the 1st film and at least one layer of a 2nd film to a 2nd substrate on the side where the above-mentioned circuits are formed to each other, then etching away the 1st film and transferring the circuits onto the 2nd substrate. CONSTITUTION:A molybdenum film is first deposited at the 1st film 12 on the 1st substrate 11 consisting of Si. An SiO2 film is then deposited as the 2nd film 13 thereon and thereafter, TFTs 17 formed by using a-Si as well as picture element electrodes 18 consisting of ITO (indium tin oxide) and wirings consisting of A1 are formed thereon to produce an active matrix 14. An adhesive 15 of, for example, an epoxy system is then applied on the matrix 14 and a PET film is stuck as the 2nd substrate 16 onto the circuits. The assembly is thereafter immersed into hydrogen peroxide and the molybdenum film 12 is completely removed by etching. Finally, the 1st substrate 11 is completely peeled and the above-mentioned circuits are completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a semiconductor circuit, and particularly to a method for forming a semiconductor circuit without restrictions on the material of a substrate.

[Prior Art 1] Research and development of flat display devices (displays), which are thin and have low power consumption, such as liquid crystal displays (LCDs), are actively being conducted. These displays use substrates with wiring or active elements (amorphous S1 thin film transistors (A-3I TFTs) to obtain high display quality.
) and polycrystalline S1 thin film transistors [poly-Si
An active matrix substrate incorporating T F 7N is required, and glass is generally used as the substrate material on which the wiring and active matrix are formed.

However, glass has limitations in its heat resistance, which imposes significant restrictions on the production of the wiring and active elements. That is, the heat resistance temperature of inexpensive glass is generally low, and it is inevitable that it contains alkali metals that adversely affect active elements. For this reason, there is a demand for the development of inexpensive glass substrates that contain fewer impurities and have a high heat resistance, but there is still no progress in developing glasses that meet these demands. On the other hand, when a glass substrate is used, there is a problem that the display cannot be folded up into a small size when not in use due to its rigidity. Therefore, a display using a flexible substrate that can be folded into a small size when not in use is eagerly awaited.

As a technology to remove board constraints, International Electric Yoshi Device Meading (1989)
Internationala, I ElectronDe
device reprinting technology has been reported in Vice Meeting (IEDM) (K. Sumiyoshi (K, S.
umiyoshi, ) et al., [DEVICE LAYERTANSFE
RED POLY-5iTFT ARRAY FO
RHl(J RESOLUTION LTQIJI
DCRYSTAL PROJECTOR”) J, IEDM 89.p, 165.19
89).

1. Problems to be Solved by the Invention] The above technology fabricates an active matrix on the 81 substrate via an oxide film (SiC, film), then attaches it to another substrate, and then removes the 81 substrate in a polishing process. It is. In the polishing process, since the polishing rate of 8101 is lower than that of Sl, S10. The polishing can be stopped when the 81-substrate appears, and as a result, the device formed on the 81-substrate can be transferred onto another substrate. In the above report, the same process was used twice, first transferring to another Si substrate and then transferring to a glass substrate. This is to prevent the device from turning over, but is not essential. In this method, a high-temperature S] substrate with high heat resistance can be used as the substrate for fabricating the active matrix, so there are fewer restrictions on the fabrication temperature in matrix fabrication.
It has the advantage of making it possible to fabricate FT, but since the transfer is performed using polishing, if you try to transfer it onto a flexible substrate that has no rigidity, the substrate will deform as the Si substrate becomes thinner due to polishing, making it impossible to polish uniformly. There was a fundamental problem. Furthermore, there is a problem in that an expensive polishing device must be prepared.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a method for reprinting a circuit without restrictions on the substrate.

[Means for Solving the Problems] The present invention uses a method of removing by etching a film interposed between a circuit formed on a substrate and the substrate. If this film has a high etching speed and can be selectively removed from manufactured circuits, devices, or substrates, the circuits and devices can be reprinted.

That is, in the method for forming a semiconductor circuit of the present invention, a first substrate on which a circuit is formed via a first film, or a first film and at least one layer of a second film is placed on the side on which the circuit is formed. After attaching the first film to the second substrate, the first film is removed by etching to form the second circuit.
It is characterized by being transferred onto a board.

Effect] In the present invention, it is possible to use a substrate with a high heat resistance or a substrate that does not contain substances that adversely affect the circuit as a substrate forming a circuit, and it is possible to reduce restrictions on the substrate. In addition, unlike conventional technology, polishing is not required when reprinting a circuit, so expensive polishing equipment is not required.
In addition, even when attempting to transfer onto a flexible substrate without rigidity, there is no problem of the substrate deforming.

[Example] Example 1 FIGS. 1(a) to 1(f) are process cross-sectional views of a first example of the method for forming a semiconductor circuit of the present invention.

In this embodiment, an example is shown in which an active matrix is formed as a circuit on a first substrate 81 having a diameter of 4 inches, and is transferred onto a second substrate made of polyethylene terephthalate (PUT).

First, as shown in FIG. 1(a), a first substrate l of Si is prepared.
A molybdenum film is deposited as a first film 12 on the substrate 1 to a thickness of about 1 μm. Next, as shown in (b), in order to prevent the molybdenum film 12 from being exposed to an oxidizing atmosphere during the manufacturing process, Si, O, and other films are deposited as the second film 13, and then a film is deposited using a normal active matrix manufacturing method. -TFT17 using 3i
and IT○ (indium tin oxide) pixel electrode 18, A
1 wiring is formed, and the active matrix 14 is manufactured. Next, as shown in (c), for example, an epoxy adhesive 15 is applied onto the active matrix 14, and (
As shown in d), PETM is laminated on the circuit as a second substrate]6.

Thereafter, the molybdenum film 12 is etched by immersing it in hydrogen peroxide water as shown in (e). At this time, the etching solution was heated to improve the etching speed. In this way, the etching progresses and the molybdenum film 12 is etched.
is completely removed, and finally, the first substrate 11 is completely separated as shown in (f), and the process is completed.

Here, molybdenum was used for the first film 12 because it is sensitive to oxidizing atmosphere and can be easily removed by etching by immersion in hydrogen peroxide solution.
This is because the materials used for producing the active matrix, such as Al and ITO, are not etched at all, and therefore have extremely high selective etching properties. Further, the reason why the second film 13 is provided is to prevent the molybdenum film 12 from being directly exposed to an oxidizing atmosphere during active matrix fabrication.

Thereafter, this substrate (second substrate 16) and a counter substrate made of PET on which a counter electrode was formed were attached with the polymer dispersed liquid crystal sandwiched therebetween, thereby completing the display. When this display was displayed, it was confirmed that display characteristics equivalent to those formed on a glass substrate were obtained.Also, this display has flexible properties and can be easily bent to a moderate degree. Do you get it. Therefore, it is possible to realize a display that can be folded into a small size when not in use.

Example 2 In place of the molybdenum film 12 of Example 1, a molybdenum film sputtered with an oxygen-containing gas during formation of the molybdenum film was used. Therefore, the molybdenum film contains oxygen at a high concentration. A molybdenum film containing a high concentration of oxygen has a higher etching rate with hydrogen peroxide than a molybdenum film. The subsequent steps were the same as in Example 1. As a result, the molybdenum film shown in FIG. 1(e) was removed at an extremely high speed. The characteristics etc. were exactly the same.

Example 3 As the first film 12 of Example 1, a CaF (calcium fluoride) film was used instead of the molybdenum film. This material can be epitaxially grown on a single crystal Si substrate, and CaF 81 can also be epitaxially grown on top of it.

In this example, the epitaxially grown S1 film was
An active matrix was fabricated using this as an active layer. A PET film was laminated as a second substrate, and CaF was removed with diluted hydrofluoric acid. CaFt could be easily etched with diluted hydrofluoric acid, and the active matrix could be transferred to the second substrate as in Examples 1 and 2. In this example, the second
The film 13 (SiC, film) was not formed.The subsequent steps were the same as in Example 1 to produce a display.

As a result, it was confirmed that display characteristics could be obtained.

Embodiment 4 FIG. 2(a) is a diagram showing a fourth embodiment of the present invention.
FIG. 2(b) is an enlarged sectional view of the main part of FIG. 2(a). Using the method described in Example 1, a large number of 81 substrates are connected to the first substrate 41.
An active matrix was fabricated thereon, and these were laminated onto a second PET substrate 42 as shown in FIG. 2(a). Thereafter, in the same manner as in Example 1, the active matrix was transferred onto a second substrate "42". Thereafter, as shown in FIG. 2(b), a through hole 43 was opened by a photo process, and then a metal film was deposited to form a metal wiring 44 connecting each active matrix using a photo process. As a result, we were able to complete a large-area active matrix in which individual active matrices were connected.

Thereafter, this substrate (second substrate 42) and a counter substrate made of PET on which a counter electrode was formed were attached with the polymer dispersed liquid crystal sandwiched therebetween, thereby completing a display. When this display was used, it was confirmed that the display characteristics could be obtained.

Since the through-holes 43 and wiring 44 could be formed at low temperatures, they could be formed without any problem even on a substrate with a low heat-resistant temperature, such as a PET substrate (42). Also, the wiring could be formed by screen printing.

In this way, by dividing and forming a circuit and transferring them onto a large-area substrate, a large-scale circuit can be easily formed on a large-area substrate. In this case, the divided circuits can be selected through individual tests before being pasted onto a large-area board, and only non-defective products can be transferred, thereby increasing the manufacturing yield of large-scale circuits.

Embodiment 5 FIG. 3 is a diagram showing a fifth embodiment of the present invention. The 81 substrate was made into the first substrate 5 using the same method as described in Example 1.
A poly-3i T F
As shown in FIG. 3, the active matrix 54 using A-3i TFTs was bonded to a second glass substrate 52 on which an active matrix 54 was formed. Next, the drive circuit was transferred to the second substrate 52 in the same manner as in Example 1. Thereafter, the drive circuit 53 and the active matrix were connected in the same manner as in Example 4. When the circuit operation was tested, it was confirmed that the signal from the drive circuit was transferred to the active matrix 54. Example 6 The display was completed in the same manner as Example 1, and the display operation was confirmed. FIG. 4 is a diagram showing a sixth example of the present invention. Using the same method as described in Example 1, the 81 substrate was used as the first substrate and poly-5i was applied on it to form 1] channel 1" FT6.
] and p-channel TF on another 81 substrate.
T62 was formed. These are transferred onto a second glass substrate 63 as shown in FIG.
, OS (CM, OS) were connected to form a circuit. When this circuit was tested, it was confirmed that it operated in CMO3 mode.

In this way, the process can be simplified by forming the CMO3 circuit, which would be complicated if manufactured in a series of steps, by dividing it into the 1-channel and p-channel parts, and then reprinting them to configure the circuit.

As explained above, in each of the above embodiments, it is possible to use a substrate that has a high heat resistance temperature and a substrate that does not contain substances that adversely affect the circuit as the substrate forming the circuit, and it is possible to reduce restrictions on the substrate. .

In addition, unlike conventional technology, polishing is not required when reprinting a circuit, eliminating the need for expensive polishing equipment, reducing costs, and reprinting onto non-rigid flexible substrates. In this case, there is no problem of the board deforming.

The gist of the present invention is to form a first film that can be easily removed by etching on a first substrate, form a circuit thereon, bond it to a second substrate, and then remove the first film. In other words, the circuit is transferred onto a second substrate. The second film protects the first film from being damaged during circuit fabrication. Therefore, it goes without saying that various changes can be made without departing from the gist of the present invention.
Although active matrices and drive circuits using i TFTs, poly-8i TFTs, and epitaxially grown S] films have been shown, circuits such as data buffer circuits may also be used. For the second film, SjO, S
An INx film or the like can be used. It is clear that the adhesive can be selected depending on the purpose and there are no restrictions.

[Effects of the Invention] As explained above, according to the present invention, circuits can be transferred without using expensive polishing equipment, so that cost reduction can be achieved. Further, by forming the circuit in sections and transferring them onto a large-area substrate, a large-scale circuit can be easily formed. At this time, the divided circuits can be selected through individual tests and only non-defective products can be reprinted, making it possible to increase the manufacturing yield of large-scale circuits. moreover,
The process can be simplified by forming the CMO3 circuit, which would be complicated if manufactured in a series of steps, by dividing it into n-channel and p-channel parts, and then reprinting the circuit to configure the circuit.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1(a) to 1(f) are process cross-sectional views of a first embodiment of the method for forming a semiconductor circuit of the present invention, and FIG. 2(b) is a diagram showing the embodiment of No. 4, FIG.
FIG. 3 is a diagram showing a fifth embodiment of the present invention, and FIG. 4 is a diagram showing a sixth embodiment of the present invention. 11.41.51.62...First substrate 12...First film 13...Second film 14...Active matrix 15...Adhesive 16.42.52.63...・Second substrate 61...n
Channel TF 'I" 62...p channel 1" FT Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. After laminating the first substrate on which a circuit is formed via the first film or the first film and at least one layer of the second film to the second substrate on the side on which the circuit is formed, A method for forming a semiconductor circuit, comprising transferring the circuit onto the second substrate by removing the first film by etching.