JP2008135437A - Peeling method, semiconductor device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a peeling method by which an object can be more easily peeled, resulting in cost reduction in a manufacturing process. <P>SOLUTION: In this peeling method, the object (140) to be peeled on a substrate (100) via a peeling layer (120) is peeled from the substrate. The method completely or partially forms the peeling layer (120) using a silicide layer, and the peeling layer is irradiated with a light to cause peeling between the substrate and the object to be peeled. Preferably, a transition metal silicide is used for the silicide layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for peeling an object to be peeled (transferred layer), and more particularly to a peeling transfer method for peeling an object to be peeled made of a thin film such as a functional film and transferring it to a transfer body such as a transparent substrate. is there.

  For example, when manufacturing a liquid crystal display using a thin film transistor (TFT), a process of forming a thin film transistor on a substrate by CVD or the like is performed. Since the process of forming the thin film transistor on the substrate involves a high temperature treatment, the substrate must be made of a material having excellent heat resistance, that is, a material having a high softening point and a high melting point. Therefore, at present, quartz glass is used as a substrate that can withstand a temperature of about 1000 ° C., and heat-resistant glass is used as a substrate that can withstand a temperature of around 500 ° C. In the case of a manufacturing process involving high-temperature processing, a quartz substrate, a heat-resistant glass substrate, or the like is used, but these are very expensive, and thus increase the product price. Further, the glass substrate is heavy and has a property of being easily broken.

  Therefore, the applicant forms a thin film device (transfer object) such as a thin film transistor on the first substrate as shown in the following Patent Documents 1 to 3, and peels it off (such as cheaper glass or plastic). ) Proposal of a peeling transfer technique for transferring to a second substrate.

Japanese Patent Laid-Open No. 10-125929 Japanese Patent Laid-Open No. 10-125931 JP 2004-140381 A

  However, although it is possible to use a cheaper substrate by using the above-described peeling transfer technique, it is desirable to improve the yield (peelability) in the peeling process for mass production and reduction of manufacturing costs.

  Therefore, an object of this invention is to provide the peeling method which is easy to peel off and can reduce the cost in a manufacturing process more.

  In order to achieve the above object, a peeling method of the present invention is a method for peeling an object to be peeled existing on a substrate via a peeling layer from the substrate, wherein all or part of the peeling layer is formed by a silicide layer. It is formed, and the peeling layer is irradiated with light to cause peeling between the substrate and the object to be peeled. Silicide is a binary compound of silicon (Si) and a more electrically positive element. For example, a compound of metal and silicon is applicable.

  The peeling method of the present invention includes a step of forming a release layer including a silicide layer on a substrate, a step of forming a transfer layer on the release layer, and a step of bonding a transfer body to the transfer layer. And a step of irradiating the release layer with light to cause the release layer to peel, and a step of releasing the substrate from the release layer.

  According to this method, peeling can be performed without using an amorphous silicon layer as the peeling layer as in the previous example. When an amorphous silicon layer is used for the release layer, hydrogen expansion (gasification) in the amorphous silicon layer is a major factor that causes release, so the amount of hydrogen in the amorphous silicon layer is important for release performance. Process management is difficult. This method utilizes the fact that when light energy is applied to the silicide layer as the peeling layer, the silicide layer is aggregated and granulated to be in a polycrystalline state and the bonding force as the film is reduced. As a result of the change of the silicide layer in this manner, the bonding force between the substrate and the object to be peeled is reduced, and the object to be peeled is peeled off. Since the expansion of the hydrogen gas in the release layer is not used, the setting of the hydrogen amount is unnecessary and process management becomes easy (the process is stabilized).

The silicide layer is preferably a transition metal silicide layer. The transition metal silicide layer tends to become granular due to aggregation. The metal (M) silicide is typically M ₂ Si, MSi, or MSi ₂ . Specifically, examples of the metal silicide layer include silicides with transition metals such as titanium silicide TiSi ₂ , cobalt silicide CoSi ₂ , nickel silicide NiSi ₂ , tungsten silicide WSi ₂ , molybdenum silicide MoSi ₂ , and tantalum silicide TaSi ₂ . Further, since the silicide thin film has a lower agglomeration temperature than the melting point of silicon alone (amorphous silicon) or metal alone, the required light energy can be reduced.

  The metal silicide is preferably titanium silicide. Titanium silicide, for example, has an aggregation temperature of about 800 ° C. and is relatively lower in temperature than other metal silicides, and is suitable for a release layer. It is considered that the contact area of the interface is remarkably reduced due to aggregation and the bonding force is reduced.

The thickness of the titanium silicide layer is preferably in the range of 5 to 100 nm. By forming the titanium silicide layer thin, the aggregation temperature of titanium silicide can be lowered, and peeling can be performed by applying lower light energy. However, it is difficult to control the process so that the thickness of the titanium silicide layer is 5 nm or less. Further, when the thickness of the titanium silicide layer is set to 100 nm or more, the titanium silicide layer is less likely to aggregate, and the silicide layer is less likely to be granulated (polycrystalline state), and the peelability tends to be deteriorated (hard to peel). There is.
By reducing the thickness of other metal silicides, the aggregation temperature of the metal silicide can be lowered.

  It is desirable that the object to be peeled (transfer target layer) is a functional film or a thin film device. Functional films or thin film devices include resistors, coils, capacitors, thin film transistors, thin film diodes, other thin film semiconductor devices, electrodes (including transparent electrodes ITO), solar cells, photoelectric conversion elements such as those used in image sensors, switching Various elements such as an element, a memory, an actuator of a piezoelectric element, and a multilayer film of an organic thin film and another substance are included. In general, an object to be peeled (transferred layer) formed through a relatively high process temperature is manufactured using a first substrate. By transferring this to the second substrate (transfer body), the process temperature of the second substrate can be lowered.

  The light irradiation is laser light irradiation. According to laser irradiation, for example, light energy can be concentrated on the peeling layer through the substrate, and the silicide layer can be granulated to reduce the bonding force of the film to cause peeling. In addition, the influence on other layers can be relatively reduced.

  The semiconductor device of the present invention is manufactured using the above-described peeling method. Semiconductor devices include TFTs, thin-film diodes, photoelectric conversion elements (photosensors, solar cells) consisting of silicon PIN junctions, silicon resistance elements, other thin-film semiconductor devices, and electrodes (eg ITO, transparent like mesa films) Electrodes), switching elements, memories, actuators such as piezoelectric elements, micromirrors (piezo thin film ceramics), magnetic recording thin film heads, coils, inductors, thin film highly permeable materials, and micro magnetic devices combining them, filters, reflective films, Includes dichroic mirrors.

  Moreover, an electronic apparatus according to the present invention uses the semiconductor device described above. Electronic devices include electro-optical devices such as liquid crystal panels, electroluminescence panels, electrophoretic display panels, digital micromirror devices, and light emitting panels.

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

First, in this embodiment, silicide is used as the peeling layer. Unlike the amorphous silicon layer, which is a material of the preceding example that constitutes the release layer, the silicide layer is not formed by gasification of hydrogen in the film by applying light energy, but by applying light energy to the silicide layer. Is agglomerated, and the silicide layer is granulated to cause peeling. As the silicide, it is possible to use (transition) metal silicide such as titanium silicide TiSi ₂ , cobalt silicide CoSi ₂ , nickel silicide NiSi ₂ , tungsten silicide WSi ₂ , molybdenum silicide MoSi ₂ , tantalum silicide TaSi ₂ . As the metal silicide becomes thinner, the temperature of aggregation caused by application of light energy decreases.

  In this embodiment, a thin film of titanium silicide is used as a peeling layer. This thin film has an aggregation temperature of about 800 ° C., and can be peeled off with light energy lower than that of amorphous silicon (melting point of silicon; 1414 ° C.).

(Peeling method)
A peeling method (a thin film device transfer method) using the above-described titanium silicide for the peeling layer will be described with reference to FIGS.

  First, a substrate 100 is prepared as shown in FIG. The substrate 100 is a light-transmitting and heat-resistant insulating substrate. Specific examples include heat-resistant glass such as quartz glass, Corning 7059, and Nippon Electric Glass OA-2.

On this substrate 100, for example, an amorphous silicon layer is formed to a thickness of 30 nm by thermal decomposition CVD at 550 ° C. using silane SiH ₄ or disilane Si ₂ H ₆ as a material. On this, 20 nm of titanium Ti is formed by sputtering. Next, the substrate 100 is heat-treated at 700 ° C., and a titanium silicide layer TiSi ₂ is formed by a thermal reaction between the silicon layer and the titanium layer to form a peeling layer 120 having a thickness of 50 nm.

  Next, as shown in FIG. 2, an object to be peeled (transferred layer) 140 is formed on the peeling layer 120. For example, a thin film semiconductor device TFT (thin film transistor) corresponds to the object 140 to be peeled.

First, as shown by a portion K in FIG. 2, a silicon oxide film SiO ₂ (intermediate layer) 142 is formed to about 200 nm by ECR-CVD using silane SiH ₄ and oxygen O ₂ as materials. Note that an insulating film other than a silicon oxide film such as a silicon nitride film Si ₃ N ₄ can be used as the intermediate layer 142.

  The intermediate layer 142 is formed for various purposes, and includes, for example, a protective layer that physically or chemically protects the object to be peeled 140, an insulating layer, a conductive layer, a laser light shielding layer, a barrier layer for preventing migration, and a reflection layer. The function as a layer is mentioned.

When the above-described TFT is formed on the intermediate layer 142, for example, the following is performed. An amorphous silicon film having a thickness of 50 nm is formed on the intermediate layer 142 by low pressure CVD (Si ₂ H ₆ gas, 425 ° C.), and this amorphous silicon film is irradiated with laser light (wavelength 308 nm). Crystallize to obtain a polysilicon film. Thereafter, the polysilicon film is subjected to predetermined patterning to form regions that become source / drain / channels of the thin film transistor. Thereafter, the surface of the polysilicon film is thermally oxidized at a high temperature of 1000 ° C. or more to form a gate insulating film SiO ₂ , then a gate electrode is formed on the gate insulating film, and ion implantation is performed using the gate electrode as a mask. The source / drain regions are formed in a self-aligned manner (self-alignment), and a thin film transistor is formed. Thereafter, electrodes and wirings connected to the source / drain regions and wirings connected to the gate electrode are formed as necessary. A protective film is formed thereon to complete the TFT.

  A TFT that is an object to be peeled (transferred layer) 140 includes a source / drain layer 146 formed by introducing an n-type impurity into a polysilicon layer, a channel layer 144, a gate insulating film 148, a gate electrode 150, In addition, an interlayer insulating film 154 and an electrode 152 made of, for example, aluminum are provided.

  As shown in FIG. 3, an ultraviolet curable adhesive 160 is applied on the object to be peeled 140 by a spin coating method to a thickness of about 100 μm, and a glass substrate 180 as a transfer body is bonded. The adhesive 160 is cured by irradiating ultraviolet rays from the glass substrate 180 side, and the glass substrate 180 is fixed.

  As the adhesive 160, various curable adhesives such as a reactive curable adhesive, a thermosetting adhesive, an ultraviolet curable adhesive, and an anaerobic curable adhesive are used as appropriate. Is done. As the transfer body, various synthetic resins (thermoplastic resin, thermosetting resin, etc.) or various glass materials (quartz glass, alkali glass, etc.) can be used.

Next, as shown in FIG. 4, Xe—Cl excimer laser (wavelength 308 nm) is irradiated from the substrate 100 side to cause the peeling layer 120 to peel off. The energy density of the irradiated laser was 500 mJ / cm ² . As described above, the titanium silicide layer as the release layer 120 is condensed and granulated by applying energy. The titanium silicide layer is divided into polycrystalline grains and loses its integrity as a film. As a result, the titanium silicide layer is easily peeled off.

  Note that irradiation may be performed while shifting the irradiation region by about 1/10 at a lower energy density.

  Next, as shown in FIG. 5, the substrate 100 and the substrate 180 as a transfer body are peeled off, and the semiconductor device (TFT) as the object to be peeled 140 is transferred to the substrate 180 side.

  Further, as shown in FIG. 6, if necessary, the peeling layer 120 remaining on the substrate 180 side is removed by washing or etching. Further, the quartz substrate 100 is subjected to the same processing and reused.

  Thus, according to the peeling transfer method of the embodiment of the present invention, the aggregation temperature is set to about 800 ° C. using the titanium silicide thin film as the peeling layer. Since the titanium silicide release layer has a lower film stability at a high temperature than when an amorphous silicon layer is used as the release layer, the release is more easily caused by application of light energy than amorphous silicon. Further, by forming the titanium silicide layer thinner, the agglomeration temperature can be lowered, and peeling can be performed with a lower power laser output (light energy). Further, unlike the case where amorphous silicon is used for the release layer, it is not necessary to accurately control the amount of hydrogen in the film, and process management is easy. The factor of yield reduction is reduced and it is in good condition (process stability is improved).

Note that the method of forming the titanium silicide layer as the release layer is not limited to the combination of the thermal CVD method and the sputtering method described above, and may be another method that can obtain the same result. For example, a titanium silicide layer may be formed on the substrate 100 by sputtering using titanium silicide TiSi ₂ as a material (target).

  In the above embodiment, the release layer 120 is composed of only a silicide layer. However, the release layer 120 is formed of a plurality of layers, and further includes a protective layer, an insulating layer, a conductive layer, a laser light shielding layer, and a laser reflection layer. A layer or the like may be provided.

  As the object to be peeled 140, in addition to TFT, for example, a thin film diode, a photoelectric conversion element (photosensor, solar cell) or a silicon resistance element composed of a silicon PIN junction, other thin film semiconductor devices, electrodes (examples) : Transparent electrodes such as ITO and mesa films), switching elements, memories, actuators such as piezoelectric elements, micromirrors (piezo thin film ceramics), magnetic recording thin film heads, coils, inductors, thin film highly permeable materials and combinations thereof There are micro magnetic devices, filters, reflective films, dichroic mirrors, etc.

  Further, the irradiation light (applied energy) may be any light that causes the release layer silicide to be granulated. For example, X-rays, ultraviolet rays, visible light, infrared rays (heat rays), laser light, millimeter waves, microwaves, electron beams, radiation (α rays, β rays, γ rays) and the like can be mentioned. Among these, laser light is preferable in that it is easy to cause peeling by concentrating energy as much as possible only on the peeling layer.

Examples of laser devices that generate this laser light include various gas lasers, solid-state lasers (semiconductor lasers), and the like. Excimer lasers, Nd-YAG lasers, Ar lasers, CO ₂ lasers, CO lasers, He-Ne A laser or the like is preferably used, and an excimer laser is particularly preferable among them.

  Since the excimer laser outputs high energy in a short wavelength region, it can agglomerate the silicide of the release layer in a very short time to cause granulation, and the adjacent transfer body 180, the substrate 100, and the like hardly increase in temperature. Good condition without generating. That is, the peeling layer 120 can be peeled without causing deterioration or damage to the substrate 100 or 180.

  In addition, in the case where the area of the release layer 120 is larger than the irradiation area of one irradiation light, the entire area of the release layer 120 can be irradiated with irradiation light in a plurality of times. Moreover, you may irradiate the same location twice or more. Further, irradiation light (laser light) of different types and different wavelengths (wavelength regions) may be irradiated twice or more to the same region or different regions.

  As described above, since the embodiment of the present invention uses the titanium silicide layer as the peeling layer, it does not need to control the amount of hydrogen in the amorphous silicon layer as compared with the case where the amorphous silicon layer is used as the peeling layer. Moreover, peeling can be performed with low power. In addition, the variation in peeling is reduced, and it is possible to improve the yield in the peeling transfer method.

  (Electronics)

  Next, an example of an electronic apparatus including a semiconductor device manufactured by the above-described peeling method will be described. The semiconductor device according to the present embodiment can be applied to manufacture of a liquid crystal panel, an electroluminescence panel, an electrophoretic display panel, and the like that constitute a display unit, a circuit unit, and the like in various electronic devices.

  FIG. 7 is a schematic perspective view illustrating an example of an electronic device. FIG. 6A shows an application example to a mobile phone, and the mobile phone 530 includes an antenna portion 531, an audio output portion 532, an audio input portion 533, an operation portion 534, and a display portion 535.

  FIG. 5B shows an application example to a video camera. The video camera 540 includes an image receiving unit 541, an operation unit 542, an audio input unit 543, and a display unit 544.

  FIG. 6C shows an application example to a television device, and the television device 550 includes a display portion 551.

  FIG. 4D shows an application example to a roll-up television device, and the roll-up television device 560 includes a display portion 561. Further, the thin film device according to the present invention is not limited to the above-described example, and can be applied to various electronic devices. For example, in addition to these, it can also be used for a fax machine with a display function, a finder for a digital camera, a portable TV, an electronic notebook, an electric bulletin board, a display for advertisements, and the like.

  The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention.

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Explanation of symbols

100 quartz substrate (first substrate), 120 release layer, 140 object to be peeled off (transfer target layer), 160 adhesive, 180 glass substrate (second substrate)

Claims (10)

A method of peeling an object to be peeled existing on a substrate via a peeling layer from the substrate,
All or part of the release layer is formed of a silicide layer;
A peeling method, wherein the peeling layer is irradiated with light to cause peeling between the substrate and the object to be peeled. Forming a release layer including a silicide layer on a substrate;
Forming an object to be peeled on the release layer;
Bonding a transfer body to the object to be peeled;
Irradiating the release layer with light, causing the release layer to peel off, and
Separating the substrate from the release layer;
The peeling method characterized by having.   The peeling method according to claim 1, wherein the silicide layer is a metal silicide layer.   The peeling method according to claim 3, wherein the aggregation temperature of the metal silicide layer is lower than the melting point temperature of the amorphous silicon layer.   The peeling method according to claim 3 or 4, wherein the metal silicide layer is titanium silicide.   The peeling method according to claim 5, wherein the titanium silicide layer has a thickness in a range of 5 to 100 nm.   The peeling method according to claim 1, wherein the object to be peeled is a functional film or a thin film device.   The peeling method according to claim 1, wherein the light irradiation is laser light irradiation.   A semiconductor device manufactured using the peeling method according to claim 1.   An electronic apparatus using the semiconductor device according to claim 7.

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