JPH0982967A - Method for manufacturing semiconductor device - Google Patents

Abstract

(57) Abstract: To solve the upper limit of the process temperature at the time of forming a group IV semiconductor film due to the heat resistant temperature of a transparent insulating substrate. SOLUTION: On a heat resistant substrate such as a metal wheel, aS
Forming a plurality of films such as an i film and a group IV semiconductor film such as a polycrystalline Si film and an insulating film, and then pasting a transparent insulating substrate such as a glass substrate or a resin transparent substrate on the laminated film, The heat resistant substrate is removed from the laminated film, and the removed surface is subjected to various processes to manufacture a semiconductor device. That is, in the present invention, the heat treatment at the relatively high temperature required for forming the group IV semiconductor film or the insulating film is completed on the heat resistant substrate. As a result, the upper limit of the process temperature due to the heat resistant temperature of the transparent insulating substrate is eliminated, and the degree of freedom in selecting the film forming method is expanded. Especially polycrystalline S
When the i film is formed, a simple thermal CVD method can be used for the process that conventionally requires the laser annealing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device using a transparent insulating substrate, such as a pixel switching element and a driving circuit element in a liquid crystal display device.

[0002]

2. Description of the Related Art Generally, glass is used for a substrate of a semiconductor device incorporated in a pixel portion or a drive circuit portion of a liquid crystal display device. Therefore, the semiconductor device is required to be manufactured by a low temperature process because the upper limit of the manufacturing process temperature is limited by the heat resistant temperature of glass. In recent years, the demand for low-temperature processes has tended to increase with the increase in screen size of liquid crystal display devices (increasing the area of glass substrates).

However, such a restriction on the process temperature is not only an obstacle to the improvement of the mobility and reliability of the transistor mounted in the liquid crystal display device, but also the formation of the polycrystalline Si film on the glass substrate. , Simple thermal CV
The laser annealing method must be used instead of the D method, which causes the process to be complicated.

Further, from the weight requirement accompanying the increase in size of liquid crystal display devices, it is desired to use a resin substrate which is lighter than glass as a substrate of a semiconductor device. However, since the resin substrate is inferior in heat resistance to glass, the process temperature is more strictly limited than that of the glass substrate, and a more complicated manufacturing process is required.

[0005]

Thus, when a glass substrate or a resin transparent substrate is used as the transparent insulating substrate of the semiconductor device, the process temperature is limited by the heat resistant temperature of the glass substrate or the resin transparent substrate, As a result, there is a problem that the performance of the semiconductor device is increased and the process is complicated.

The present invention is intended to solve such problems, and even if an insulating transparent substrate of a semiconductor device, such as a glass substrate or a resin transparent substrate, having poor heat resistance is used, IV
An object of the present invention is to provide a method of manufacturing a semiconductor device, which can obtain a high-performance semiconductor device without being subject to an upper limit of a process temperature when forming a group semiconductor film.

[0007]

In order to achieve the above object, the present invention forms a plurality of films including a group IV semiconductor film on a heat resistant substrate, and thereafter forms a transparent insulating substrate on the laminated film. Is attached, the heat-resistant substrate is removed from the laminated film, and various processes for forming a functional element are performed on the substrate removal surface to manufacture a semiconductor device.

That is, in the present invention, since the heat treatment at a relatively high temperature required for the formation of the group IV semiconductor film or the insulating film is completed on the heat resistant substrate, the group IV heat resistance depending on the heat resistant temperature of the transparent insulating substrate is used. The upper limit of the process temperature at the time of various film formation including a semiconductor film is solved. Therefore, the degree of freedom in selecting the film forming method is expanded, and particularly, as a group IV semiconductor film, polycrystalline S
In the case of forming an i film, the conventional process that had to use the laser annealing method is simple thermal CVD.
The law will do.

Since the upper limit of the process temperature at the time of film formation due to the heat resistant temperature of the transparent insulating substrate has been eliminated, a resin transparent substrate having a heat resistant temperature lower than that of the glass substrate is used as the substrate of the semiconductor device. Will be possible.

When a heat-resistant substrate made of Al is used, the remaining Al can be used as a wiring layer by partially removing (thinning) the Al substrate. Further, before forming the IV group semiconductor film, for example, the polycrystalline Si film, a semiconductor underlayer film made of at least one material selected from Al ₂ O ₃ , MgO, and CaF ₂ is formed to form the polycrystalline Si film. It allows the membrane to be obtained at relatively low temperatures.

The group IV semiconductor may be a semiconductor such as Si, Ge or C, or a compound semiconductor such as SiGe or SiC.

[0012]

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

FIG. 1 is a schematic diagram in order of steps for explaining a part of the method for manufacturing a semiconductor device according to the present invention.

In the figure, 1 is a metal wheel wound in a roll shape. The metal wheel 1 pulled out from the roll portion has, for example, S
A plurality of vapor deposition steps for forming various films of iO ₂ , a (amorphous) -Si, Al, etc., and an insulating transparent substrate 2 such as a glass substrate or an organic transparent substrate on the laminated film formed by these vapor deposition steps. After the pressure-bonding process, the process is transferred to a subsequent stage (not shown) such as a metal wheel removing process and a transistor forming process. The vapor deposition method adopted here is chemical vapor deposition (CVD), physical vapor deposition (PVD), or the like, and is selected according to the purpose and the film forming material. Note that FIG. 1 shows a case where an organic transparent substrate wheel is used as the insulating transparent substrate 2.

Next, with reference to FIGS. 2 and 3, a method of manufacturing a MOS transistor according to the first embodiment of the present invention will be described.

In this example, the thickness of the metal wheel is 25 μm.
Al wheel 11 of was used. First, as shown in FIG. 2A, a 100 nm thick SiO film was formed on the Al wheel 11.
₂ Insulating film 12, 200nm thick SiN insulating film 13, thickness
100 nm SiO ₂ insulating film 14, 50 nm thick a-Si
A film 15, a 200 nm thick SiO ₂ insulating film 16 and a 200 nm thick Al film 17 were sequentially deposited. As the vapor deposition method, a sputtering method was used for Al, and a plasma CVD method was used for other cases. In addition, the heating of the Al wheel 11 in each vapor deposition step was performed at 250 ° C. using a heater (heating lamp) arranged opposite to the back surface of the Al wheel 11. The temperature of 250 ° C. is almost the same as the temperature when forming a transistor on a glass substrate conventionally. Subsequently, an acrylic substrate 19 having a thickness of 0.8 mm was attached onto the Al film 17 by using an adhesive 18 made of epoxy resin.

After that, the Al wheel 11 is entirely removed by etching using a solution containing acetic acid as a main component, and Al is sputter-deposited again to a thickness of 800 nm on the Al-removed surface.
Al film 20 to be a gate electrode of a MOS transistor
Was formed (FIG. 2B). At this time, the Al wheel 11
May be thinned as it is and used as a wiring layer.

2 (b-d) and FIG.
The SiO ₂ insulating film 12, the SiN insulating film 13, and the SiO ₂ insulating film 14 are notated as one layer and are denoted by reference numerals 12 + 13 + 14
In addition, the adhesive layer 18 and the acrylic substrate 19 are also indicated by reference numeral 18 + 19 as one layer for description.

Then, as shown in FIG.
The Al film 20, the three-layer insulating film 12 + 13 + 14, the a-Si film 15, the SiO ₂ insulating film 16, and the Al film 17 are sequentially etched from above by photolithography so as to leave the source, drain, and gate regions of the transistor. processed. Thereafter, as shown in FIG. 2D, the Al film 20 other than the gate region is removed by leaving the resist in the gate region, and the remaining A
Alumina 21 is formed on the surface of the film 20, 17 by chemical oxidation
Was formed.

After that, the remaining Al film 20 is used as a mask to etch the three-layer insulating film 12 + 13 + 14 by RIE so that the a-Si film 15 is exposed (under the etching conditions of SiO ₂ and SiN, Al and alumina are almost Not etched.), Thickness after etching
A 200 nm n-type a-Si film 22 was formed by a plasma deposition method at 120 ° C. (FIG. 2E).

Next, the n-type a-Si film 22 is left in the source / drain regions by photolithography again.
The Si film 22 is etched, and subsequently the polyimide resin 23 and the spin-coated SiO ₂ (SO
G) A film 24 was sequentially coated on the entire surface to a thickness of 800 nm, and a resist was further coated. After photoprocessing the resist,
The SOG film 24 is etched with a hydrofluoric acid solution. The RIE method may be used in this etching. Next, the polyimide resin 23 was etched. Then, after removing the alumina 21 exposed in the gate region with a gas containing SF ₆ , the resist on the SOG film 24 is removed (FIG. 2).
(F)). In this state, the Al film 20 and the n-type a-Si film 22 which will be the gate electrode of the MOS transistor are exposed through the openings 25 of the polyimide resin 23 and the SOG film 24.

Subsequently, the SOG film 24 is completely removed with a hydrofluoric acid solution, a TiN film 26 having a thickness of 50 nm is sputter-deposited, and finally an Al film 27 having a thickness of 800 nm is formed by a photolithography method (see FIG. 2 (g)). As described above, the MOS transistor using the acrylic substrate 19 as the insulating transparent substrate was completed.

In this semiconductor device, the interface between the a-Si film 15 and the gate insulating film 14, which affects the element characteristics, is formed under the same temperature condition as when it is formed on the glass substrate. The element characteristics and reliability same as those of the transistor formed on the glass substrate are secured. Further, by using this completed glass substrate as an array substrate of a liquid crystal display device, it is possible to provide a large area liquid crystal display device of 1 m square or more with reduced cost.

Next, a method of manufacturing a MOS transistor according to a second embodiment of the present invention will be described with reference to FIGS.

In this example, as a metal wheel, an iron wheel 31 having 50 μm thick chrome plating 20 on both sides is used.
Was used. A 100 nm thick SiO ₂ insulating film 32 is formed on one surface of the iron wheel 31 by the CVD method, and the thickness is formed on the SiO ₂ insulating film 32.
A CaF ₂ film 33 having a thickness of 250 nm was deposited by the ΡVD method. Subsequently, a polycrystalline Si film 34 having a thickness of 100 nm was deposited by the CVD method. In this case, the temperature is 450 ° C., and the CaF ₂ film 33
Is formed as a base of the polycrystalline Si film 34, the polycrystalline Si film of the same property is directly formed on the SiO ₂ insulating film 32.
The required polycrystalline Si film can be obtained at a lower temperature than when a film is obtained (580 ° C.). Of course, CaF
_It does not depart from the gist of the present invention to deposit polycrystalline Si at a high temperature without vapor deposition of ₂ or the like. The same effect can be obtained by forming an Al ₂ O ₃ film or a MgO film instead of the CaF ₂ film. Next, on the polycrystalline Si film 34, the thickness 2
A SiO ₂ insulating film 35 having a thickness of 00 nm was deposited, and an Al film 36 having a thickness of 800 nm was further deposited thereon (FIG. 4A).

Next, a glass substrate 38 is attached onto the Al film 36 by using an adhesive 37 made of a polyimide resin, and then the iron wheel 31, the SiO ₂ insulating film 32, C are attached.
The aF ₂ film 33 was sequentially removed to expose the polycrystalline Si film 34 (FIG. 4B).

In the subsequent manufacturing process, since the polyimide resin is used as the adhesive 37 in this example, the upper limit of the process temperature is preferably 280 ° C. or lower.

Subsequently, the polycrystalline Si film 34 was etched into an island shape, and a SiO ₂ insulating film 39 was deposited by plasma CVD (FIG. 4 (c)). Then, an alloy film 40 of tantalum and molybdenum was vapor-deposited by the sputtering method, and the alloy layer 40 was patterned by the CD method to form a gate electrode 40a of the MOS transistor (FIG. 5D).

Next, the polycrystalline Si film 3 is formed by the ion implantation method.
4 was doped with phosphorus ions 41 at a rate of 5 × 10 ¹⁵ per square centimeter. Activation of implanted ions in polycrystalline Si was performed by heat treatment at 260 ° C. for 1.5 hours. Furthermore, by plasma CVD method, S of 1 μm thickness
An iO ₂ insulating film 42 was vapor-deposited, and a contact hole was formed by photolithography. Then, the TiN film 43 was sputter-deposited, and finally the Al film 44 was formed by the photolithography method (FIG. 5E). As described above, the MOS transistor using the glass substrate 38 as the insulating transparent substrate was completed. It goes without saying that the liquid crystal display device using this glass substrate exerts the same effect as that of the first embodiment.

As described above, according to the method of manufacturing a semiconductor device of the present invention, the heat treatment at the relatively high temperature required for forming the polycrystalline Si film on the metal wheel is completed, so that the heat resistant temperature of the glass substrate is increased. The upper limit of process temperature due to is eliminated. Therefore, the degree of freedom in selection of the film forming method is expanded, and the process in which the conventional laser annealing method must be adopted in forming the polycrystalline Si film is simple thermal CV.
The D method will be sufficient.

[0031]

As described above, according to the present invention, the heat treatment at the relatively high temperature required for the formation of the group IV semiconductor film is completed on the heat resistant substrate. The upper limit of the process temperature at the time of forming the group IV semiconductor film is solved. Therefore, the degree of freedom in the selection of the film forming method is expanded, and particularly in the case of forming a polycrystalline Si film as a group IV semiconductor film, the conventional thermal annealing method is a simple thermal CVD method that requires the laser annealing method. In addition, a resin transparent substrate having heat resistance lower than that of the glass substrate can be used as the insulating transparent substrate.

[Brief description of drawings]

1A to 1C are schematic views in order of steps for explaining a part of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a diagram for explaining a method of manufacturing a MOS transistor according to the present invention.

FIG. 3 is a view for explaining the manufacturing method of the MOS transistor subsequent to FIG. 2;

FIG. 4 is a diagram for explaining another MOS transistor manufacturing method according to the present invention.

FIG. 5 is a view for explaining the manufacturing method of the MOS transistor subsequent to FIG. 4;

[Explanation of symbols]

11 ... Al wheel 12, 14, 16 ... SiO ₂ insulating film 13 ... SiN insulating film 15 ... a-Si film 17 ... Al film 19 ... Acrylic substrate 31 ... Iron wheel 32, 35 ... SiO ₂ Insulating film 33 ... CaF ₂ film 34 ... Polycrystalline Si film 36 ... Al film 38 ... Glass substrate

Claims (4)

[Claims] 1. A film forming step of forming a plurality of films containing at least a group IV semiconductor film on a heat-resistant substrate, and a transparent insulating film on the laminated film containing the group IV semiconductor film obtained in the film forming step. A method of manufacturing a semiconductor device, comprising: a step of adhering a substrate; and a step of removing the heat resistant substrate from the laminated film. 2. A film forming step of forming a plurality of films including at least a group IV semiconductor film on a heat-resistant substrate, wherein Al ₂ O ₃ , MgO and CaF ₂ are formed before forming the group IV semiconductor film. A film forming step including a step of forming a semiconductor underlayer film made of at least one material selected from the above, and a transparent insulating substrate attached on the laminated film including the group IV semiconductor film obtained in the film forming step. And a step of removing the heat resistant substrate and the semiconductor underlayer film from the laminated film, respectively. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the group IV semiconductor film is a polycrystalline Si film. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the transparent insulating substrate is a resin transparent substrate.