JP2009231533A - Peeling method, peeling apparatus and method of manufacturing semiconductor device - Google Patents

Abstract

A peeling method capable of easily peeling is provided. Moreover, the manufacturing yield of the apparatus is improved by improving the peeling accuracy.
A peeling method according to the present invention includes a first substrate (S1) having a peeling layer (3) and a semiconductor element (55) formed thereon, and the semiconductor element forming surface of the first substrate. And a second substrate (S2) bonded via an adhesive layer (18), the method for peeling the laminated substrate (S), wherein the peeling layer (3) of the laminated substrate is removed under a negative pressure condition. The first substrate and the second substrate are peeled off from the layer or from the interface. According to such a method, by peeling the first substrate and the second substrate under a negative pressure state, a gap in the layer of the peeling layer or the interface expands, and peeling can be easily performed.
[Selection] Figure 4

Description

  The present invention relates to a peeling method, a peeling apparatus, and a method for manufacturing a semiconductor device, and more particularly, to a technique for peeling between substrates used in a transfer process.

  In recent years, in the development of electro-optical devices such as liquid crystal devices, the use of flexible substrates has been studied because of the flexibility and impact resistance in addition to the reduction in size and weight of the devices.

  Since such a flexible substrate is inferior in heat resistance and solvent resistance to an inorganic glass substrate, it is difficult to directly form a semiconductor element on the flexible substrate. In addition, due to its flexibility, it was necessary to devise handling during the manufacturing process.

  Therefore, a technique for transferring a semiconductor element formed on a glass substrate to a flexible substrate is employed.

  For example, in the following Patent Documents 1 to 3, a transfer layer such as a thin film transistor is formed in advance on a transfer source substrate via a release layer, the transfer layer is bonded to the transfer destination substrate, and then light is applied to the release layer. A technique for transferring a transfer target onto a transfer destination substrate by performing irradiation or the like to cause separation is disclosed.

Patent Document 4 below describes a technique for peeling a transfer source substrate and a transfer destination substrate.
JP-A-10-235929 JP-A-10-235930 Japanese Patent Laid-Open No. 10-235931 JP 2004-228374 A

  Although the above transfer technology is attracting attention as a technology that can form a semiconductor element such as a thin film transistor on an arbitrary substrate in accordance with the use and convenience of various electronic devices, the peeling technology simply applies stress between the substrates. There were many things that physically peeled off.

  However, if stress is applied excessively, the transferred layer and the transfer destination substrate are damaged, and the yield decreases. In particular, when a flexible substrate is used as a transfer destination substrate, stress is easily applied, and an examination of an effective peeling technique is desired.

  The specific aspect which concerns on this invention aims at providing the peeling method which can perform peeling easily. Moreover, it aims at improving the manufacture yield of an apparatus by improving peeling precision.

  A peeling method according to the present invention includes a first substrate having a peeling layer and a semiconductor element formed thereon, a second substrate bonded to the semiconductor element forming surface of the first substrate via an adhesive layer, A method for peeling a laminated substrate comprising: separating the first substrate and the second substrate from a layer or an interface of the peeling layer of the laminated substrate under a negative pressure state.

  According to such a method, peeling between the first substrate and the second substrate under a negative pressure (depressurized from the atmosphere) expands a gap in the layer of the peeling layer or at the interface, thereby facilitating peeling. It can be carried out.

  The negative pressure state is preferably a vacuum state. If the degree of vacuum is high, the gap between the layers of the release layer or the interface expands more, and thus the release can be performed more easily.

  Peeling between the first substrate and the second substrate is performed by inserting a blade-like body into the release layer of the laminated substrate. In this manner, a crack is generated by inserting the blade-like body, and peeling can be further easily performed by expanding the crack.

  A peeling apparatus according to the present invention includes a first substrate having a peeling layer and a semiconductor element formed thereon, a second substrate bonded to the semiconductor element forming surface of the first substrate via an adhesive layer, And a processing chamber in which the multilayer substrate is processed, and a pump that puts the processing chamber in a negative pressure state.

  According to such a configuration, peeling can be performed in a processing chamber in a negative pressure state, and a gap between the layers of the peeling layer or the interface can be expanded, so that peeling can be easily performed.

  A blade-like body inserted into the release layer of the laminated substrate is provided in the processing chamber. In this manner, a crack is generated by inserting the blade-like body, and peeling can be further easily performed by expanding the crack.

  Stress applying means for applying a force in the thickness direction of the laminated substrate to the blade-like body is provided. Thus, peeling can be further easily performed by applying a force in the thickness direction of the laminated substrate using the blade-like body.

The method for manufacturing a semiconductor device according to the present invention includes a step of forming a release layer on a first substrate, a step of forming a semiconductor element on the release layer, a formation surface of the semiconductor element on the first substrate, A step of joining two substrates through an adhesive layer to form a laminated substrate, and a step of separating the first substrate and the second substrate from the layer or interface of the release layer under a negative pressure state. When,
Have

  According to this method, by peeling the first substrate and the second substrate under a negative pressure state, the gap in the layer of the peeling layer or the interface expands, and peeling can be easily performed. In addition, physical stress applied to the laminated substrate is not applied, or even if the applied stress is small, the gap can be easily peeled due to expansion, so that damage to the first and second substrates or the semiconductor element can be reduced. The manufacturing yield of the device can be improved.

  The step of peeling the first substrate and the second substrate is performed by inserting a blade-like body into the release layer of the laminated substrate and applying a force to the blade-like body in the thickness direction of the laminated substrate. Done. A crack is generated by inserting the blade-like body, and peeling can be further easily performed by expanding the crack. Further, peeling can be further easily performed by applying a force in the thickness direction of the laminated substrate.

  For example, before the step of peeling the first substrate and the second substrate, there is a step of ablating the release layer by irradiating the release layer with laser light. As described above, after a large number of minute bubbles (spaces) are formed in the peeling layer or at the peeling layer interface by ablation, peeling may be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or related code | symbol is attached | subjected to what has the same function, and the repeated description is abbreviate | omitted.

(1) Transfer process (semiconductor device manufacturing process)
1 to 3 are cross-sectional views showing a transfer process of the semiconductor element of the present embodiment. The transfer process, that is, the process of transferring the semiconductor element formed on the first substrate S1 to the second substrate S2 and further transferring to the third substrate S3 will be described with reference to these drawings. Here, a thin film transistor (TFT) is illustrated and described as a semiconductor element.

(TFT formation process)
As shown in FIG. 1A, a release layer 3 is formed on the first substrate S1. The conditions of the first substrate S1 are not particularly limited as long as the substrate can withstand each process in the subsequent TFT (element) formation process. For example, a glass substrate can be used as the first substrate S1.

  Next, an amorphous silicon film is formed as a peeling layer (separation layer, sacrificial layer, adhesion / peeling layer) 3 on the first substrate S1 by a CVD (chemical vapor deposition) method. As the release layer 3, an organic polymer material such as polyethylene or polypropylene may be used in addition to a silicon oxide film and an inorganic thin film. Further, not only a single layer but also a plurality of layers may be used.

  Next, a TFT is formed on the release layer 3. Although there is no particular limitation on the TFT formation process, the TFT can be formed by the following processes.

  As shown in FIG. 1B, a silicon oxide film, for example, is formed as a base protective film 5 on the release layer 3 by a CVD method, and an amorphous silicon film, for example, is formed as a semiconductor layer 7 thereon by a CVD method. . Next, this film is crystallized by laser irradiation to form a polycrystalline silicon film. Thereafter, the semiconductor film 7 is patterned to form an island-shaped semiconductor film 7, and a silicon oxide film, for example, is formed as a gate insulating film 9 on the semiconductor film 7 by a CVD method. Next, for example, an aluminum (Al) film or the like is formed as a gate electrode 11 on the gate insulating film 9 by a sputtering method and patterned. Next, source and drain regions 7a and 7b are formed by implanting impurities such as boron (B) or phosphorus (P), for example, using the gate electrode 11 as a mask and impurity ions. A TFT is formed by the above process.

  Next, as shown in FIG. 1C, for example, a silicon oxide film is formed as an interlayer insulating film 13 on the gate electrode 11 by a CVD method, and the interlayer insulating film 13 on the source and drain regions 7a and 7b is etched. As a result, a contact hole is formed. Next, for example, an Al film is deposited as a conductive film on the interlayer insulating film 13 including the inside of the contact hole by a sputtering method and patterned to form source and drain lead lines 15a and 15b.

  Next, for example, a silicon oxide film is formed as the protective film 17 on the source / drain lead-out wirings 15a and 15b by, for example, the CVD method. A multilayer wiring may be formed on the source and drain lead wirings 15a and 15b by repeating the deposition of the conductive film, the patterning, and the deposition of the interlayer insulating film.

(First transfer process)
1) First bonding step The TFT and wiring formed in the above steps are transferred to the second substrate S2. This transfer is called first transfer (intermediate transfer, temporary transfer). The condition of the second substrate S2 may be any substrate that can withstand the subsequent processes. For example, a substrate (for example, a glass substrate) made of the same material as the first substrate S1 may be used.

  As shown in FIG. 2A, an adhesive (temporary adhesive) 18 is formed on the protective film 17 of the first substrate S1. The adhesive 18 is made of, for example, a thermosetting adhesive or a photocurable adhesive. On the adhesive 18, a second substrate S2 in which, for example, an amorphous silicon film is formed as the peeling layer 19 by the CVD method is bonded (adhered).

2) First peeling step Next, as shown in FIG. 2 (A), the peeling layer 3 is irradiated with laser light from the first substrate S1 side to cause ablation, whereby the inside of the peeling layer 3 or other A portion with reduced adhesion, such as a crack, is generated at the interface with the film. Ablation refers to a phenomenon in which a material layer that has absorbed irradiation light is excited chemically or thermally, causing melting or vaporization of the material layer on the surface or inside thereof. Therefore, a large number of minute bubbles (spaces) are generated on the surface (interface) and inside of the material layer, which weakens the adhesive force and causes cracks.

  At this time, the focus of the laser beam is adjusted so that the peeling layer 19 is not affected by the laser beam. In addition, when the film | membrane (or the film | membrane which reduces the intensity | strength of a laser beam) which does not permeate | transmit a laser beam is used between the peeling layer 3 and the peeling layer 19, the said adjustment is unnecessary.

  Next, as shown in FIG. 2B, the first substrate S1 is peeled off with the second substrate S2 side as the lower side. Next, the residue of the release layer 3 remaining on the surface of the second substrate S2 is removed by etching or the like. With the above steps, the first transfer step is completed. At this time, as shown in FIG. 2B, the TFT (T) and the wirings (15a, 15b) are transferred in the reverse direction on the second substrate S2.

(Second transfer process)
1) Second Bonding Step Next, the TFT and the wiring on the second substrate S2 are second transferred (final transfer) to the third substrate S3. The third substrate S3 is, for example, a plastic substrate such as polyimide, polyester, polycarbonate, polyethersulfone, polyethylene terephthalate, or polyethylene naphthalate, or a silicate mineral having a layered crystal structure and an organic / inorganic composite. A flexible substrate made of a substrate, a metal substrate, or the like. Such substrates are diverse because they are lightweight and inexpensive, and are also resistant to stress.

  First, as shown in FIG. 3A, a thermosetting adhesive, a photocurable adhesive, or the like is formed as the permanent adhesive 21 on the base protective film 5 of the second substrate S2. Next, the third substrate S3 is bonded (adhered) on the permanent adhesive 21.

2) Second peeling step Next, as shown in FIG. 3 (B), the peeling layer 19 is irradiated with laser light from the second substrate S2 side to cause ablation, whereby the inside of the peeling layer 19 or other Cracks are generated at the interface with the film.

  Next, the residue of the release layer 19 remaining on the surface of the second substrate S2 and the adhesive 18 are removed by etching or the like, and the second transfer is completed.

  The TFT is an example of a semiconductor element, and various semiconductor elements can be formed on a desired substrate by the transfer process.

  As described above, by using the transfer technique, a plurality of types of semiconductor elements having different manufacturing conditions are formed on the transfer source substrate (S1, S2) under optimum conditions, and then moved to the transfer destination substrate (S3). A desired electronic device can be manufactured.

(2) Peeling method and peeling device Next, the peeling method and peeling device used in the first and second peeling steps will be described in detail. FIG. 4 is a cross-sectional view showing the peeling method and the peeling apparatus of the present embodiment.

  As shown in FIG. 4A, the peeling apparatus is covered with a decompression chamber (decompression treatment chamber) 50 and can be adjusted to a negative pressure state by a vacuum pump 53.

  In the decompression chamber 50, a stage (fixed plate) 51 for mounting a substrate and a blade-like body 57 constituting a peeling means are incorporated. For example, the stage 51 has a mechanical fixing mechanism, and fixes the lower substrate (here, the second substrate S2). The means for fixing is not limited. For example, the periphery of the second substrate S <b> 2 may be fixed by a hook-shaped member in which the lower substrate is protruded from the stage 51. Moreover, you may fix using an electrostatic chuck etc.

  Further, the blade-like body 57 is made of a metal member having a substantially L-shaped cross section, for example, and has a shape with a sharp tip in the horizontal direction. As shown in FIG. 4B, the width of the blade-like body 57 is, for example, 1/3 or more of one side of the laminated substrate, and can hold the upper substrate (here, the first substrate S1) after peeling. It has a configuration.

  Further, a force (stress) in the thickness direction of the laminated substrate S (the peeling direction, the substrate direction opposite to the fixed substrate, and the upward direction in FIG. 4A) is applied to the blade body 57. Yes. The stress applying mechanism 59 is not limited. For example, as shown in FIG. 4A, the stress applying mechanism 59 can be configured to have a pulley 59b and a weight 59a connected to the blade-like body 57.

  For example, the laminated substrate (see FIG. 2A) S of the first substrate S1 and the second substrate S1 is mounted on the stage (fixed plate) 51 and fixed. Here, a detailed configuration of a semiconductor element such as a TFT is omitted, and a layer in which the semiconductor element such as a TFT is formed is indicated by a transfer layer 55.

  Subsequently, the air in the decompression chamber 50 is decompressed by the vacuum pump 53, and the inside is brought into a negative pressure state. Next, the blade 57 is inserted into the release layer 3 of the multilayer substrate S, and the first substrate S1 is peeled by pulling the first substrate S1 upward by the blade 57.

  Here, as described above, the inside of the decompression chamber 50 is in a negative pressure state. On the other hand, in the stage before being transferred into the decompression chamber 50, the processing is performed in the atmosphere. Therefore, as described above, a large number of minute bubbles (spaces) generated on the surface (interface) and inside of the release layer 3 generated by ablation expand, and are connected to each other to form a large crack.

  Therefore, the first substrate S1 can be easily peeled off by simply lifting the blade-like body 57 upward, and the peeling accuracy can be improved. In addition, the manufacturing yield of the device can be improved.

  That is, in the peeling layer 3 that is the interface between the first substrate S1 and the second substrate S2, a ringing (adhesion) phenomenon occurs between the contacting layers, and the pressure is slightly reduced from the atmosphere between these layers. Considered.

  Therefore, in the present embodiment, by further reducing the pressure in the decompression chamber 50 (negative pressure), gaps (bubbles, spaces, cracks) located between the layers are expanded, and the stress applied to the substrate is reduced. In this way, peeling is realized.

As for the degree of negative pressure (reduced pressure), it is desirable that the pressure is smaller. However, for example, a vacuum of about 10 ⁻¹ Pa to 10 ⁻² Pa can be easily obtained with a rotary pump, and the apparatus cost is low. Can be reduced. You may use the vacuum below the said negative pressure. The atmospheric pressure is 1 atm = 1.01325 × 10 ⁵ Pa = 760 Torr.

  In the above embodiment, the laminated substrate S is fixed on the stage 51. However, if the negative pressure state is large (the degree of vacuum is high), the weight of the lower substrate (here, the second substrate S2) is reduced. But it can be easily peeled off. Further, if the degree of vacuum is high, it is possible to perform peeling by simply carrying it into the decompression chamber 50. However, by forming a crack with the blade 57, the crack expands and expands starting from the crack, so that the peeling can be performed efficiently.

  In FIG. 4, the second substrate S2 side is fixed on the stage 51, but the first substrate S1 side may be fixed.

  In FIG. 4, the laminated substrate S of the first substrate S1 and the second substrate S2 is peeled off, but the laminated substrate (see FIG. 3B) of the second substrate S2 and the third substrate S3 is peeled off. Also, the above peeling method and peeling device can be applied.

(3) Application Examples and Modifications FIG. 5 is a cross-sectional view showing another peeling method and peeling apparatus of the present embodiment. Hereinafter, application examples and modification examples of the present embodiment will be described with reference to FIG.

  As shown in FIG. 5, a stress is applied to the upper side (in the direction of the first substrate S1 in FIG. 5) through the blade-like body 57A, and the lower side (in FIG. 5, the second substrate in FIG. 5). Stress may be applied in the direction of S2.

  Further, the second substrate S2 is fixed by the fixing plate 51A, the first substrate S1 is fixed by the fixing plate 51B, the second substrate S2 is placed downward via the fixing substrate 51A, and the first substrate S1 is fixed by the fixing substrate 51A. Peeling may be performed by pulling upward through 51B. Such stress application mechanisms can be used singly or in combination.

  In FIG. 5, the laminated substrate S of the first substrate S1 and the second substrate S2 is peeled off, but the laminated substrate (see FIG. 3B) of the second substrate S2 and the third substrate S3 is peeled off. The above-mentioned various application examples and modifications can also be applied.

  In FIG. 5, the blades 57 are inserted on both sides of the multilayer substrate S, but may be inserted and peeled only on one side.

  Moreover, although the wide blade-like body 57 was used in FIG. 5, you may use the several acicular member arrange | positioned for every predetermined space | interval. Further, the needle-like member or the narrow blade-like body 57 may be moved horizontally along the outer periphery of the laminated substrate S to perform peeling.

  Further, in FIG. 5, peeling was performed using a substrate that had been subjected to adhesive strength reduction processing in advance by ablation or the like, but a processing unit for weakening the adhesive strength of the peeling layer, such as a light irradiation unit, was provided in the peeling device. It is also possible to perform the above-described treatment and peeling step continuously.

<Description of electro-optical device and electronic device>
Although there is no restriction on the specific application location of the semiconductor element (TFT) transferred in the above embodiment, the TFT is used as a pixel circuit or a drive circuit of an electro-optical device (display device), for example. FIG. 6 is a diagram showing a circuit configuration of the active matrix substrate. For example, in an active matrix liquid crystal device, as shown in FIG. 6, a TFT and a pixel electrode 60 are arranged at the intersection of a data line Y and a gate line, one end of the TFT is the data line Y, and the other end is a pixel electrode. 60 and its gate is connected to the gate line X. The data line Y is connected to the data line driving circuit 63, and the gate line X is connected to the gate line driving circuit 65. A TFT is also used as an element constituting such a drive circuit.

  Therefore, the semiconductor element (TFT) transferred in the above embodiment constitutes, for example, the pixel circuit or the drive circuit, and a liquid crystal or an electrophoretic capsule is disposed between the transfer substrate (S3) and the counter substrate. The display unit is configured by.

  The display unit is an electronic device such as a mobile phone, a video camera, a roll-up television, a fax machine with a display function, a digital camera finder, a portable TV, an electronic notebook, an electric bulletin board, a display for advertisements, and electronic paper. It can be incorporated in equipment (electro-optical device).

  FIG. 7 is a perspective view showing a microcomputer formed on a flexible substrate. The semiconductor element (TFT) transferred in the above embodiment can be applied not only to the electro-optical device but also to a microcomputer formed on a flexible substrate shown in FIG. 571 is a flexible substrate. For example, 573 is a RAM (random access memory), 575 is a CPU (central processing unit), 777 is an input / output circuit, and 579 is a solar cell.

  It should be noted that the examples and application examples described through the above embodiment can be used in appropriate combination according to the application, or can be used with modifications or improvements, and the present invention is limited to the description of the above embodiment. Is not to be done. It is apparent from the description of the scope of claims that the embodiments added with such combinations or changes or improvements can be included in the technical scope of the present invention.

It is sectional drawing which shows the transcription | transfer process of the semiconductor element of this Embodiment. It is sectional drawing which shows the transcription | transfer process of the semiconductor element of this Embodiment. It is sectional drawing which shows the transcription | transfer process of the semiconductor element of this Embodiment. It is sectional drawing which shows the peeling method and peeling apparatus of this Embodiment. It is sectional drawing which shows the other peeling method and peeling apparatus of this Embodiment. It is a figure which shows the circuit structure of an active matrix substrate. It is a perspective view which shows the microcomputer formed on the flexible substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Release layer, 5 ... Base protective film, 7 ... Semiconductor layer, 7a, 7b ... Source, drain region, 9 ... Gate insulating film, 11 ... Gate electrode, 13 ... Interlayer insulating film, 15a, 15b ... Source, drain extraction Wiring, 17 ... protective film, 18 ... temporary adhesive layer, 19 ... release layer, 21 ... permanent adhesive, 50 ... decompression chamber, 51 ... stage, 51A, 51B ... fixing plate, 53 ... vacuum pump, 55 ... transfer layer, 57: Blade, 59 ... Stress application mechanism, 59a ... Weight, 59b ... Pulley, 63 ... Data line drive circuit, 65 ... Gate line drive circuit, 571 ... Flexible substrate, 573 ... RAM, 575 ... CPU, 579 ... On Output circuit, 579 ... solar cell, S ... laminated substrate, S1 ... first substrate, S2 ... second substrate, S3 ... third substrate, T ... TFT, X ... gate line, Y ... data line

Claims (9)

A method for peeling a laminated substrate comprising: a first substrate having a peeling layer and a semiconductor element formed thereon; and a second substrate bonded to the semiconductor element forming surface of the first substrate through an adhesive layer. Because
A peeling method, wherein the first substrate and the second substrate are peeled from a layer or an interface of the peeling layer of the laminated substrate under a negative pressure state.   The peeling method according to claim 1, wherein the negative pressure state is a vacuum state. The peeling between the first substrate and the second substrate is as follows:
The peeling method according to claim 1, wherein the peeling method is performed by inserting a blade-like body into the peeling layer of the laminated substrate. A laminated substrate peeling apparatus comprising: a first substrate having a peeling layer and a semiconductor element formed thereon; and a second substrate bonded to the semiconductor element forming surface of the first substrate via an adhesive layer. Because
A processing chamber in which the laminated substrate is processed;
A pump for bringing the processing chamber into a negative pressure state;
The peeling apparatus characterized by having.   The peeling apparatus according to claim 4, further comprising a blade-like body inserted into the peeling layer of the laminated substrate in the processing chamber.   6. The peeling apparatus according to claim 5, further comprising stress applying means for applying a force in the thickness direction of the laminated substrate to the blade. Forming a release layer on the first substrate;
Forming a semiconductor element on the release layer;
Bonding the formation surface of the semiconductor element of the first substrate and the second substrate through an adhesive layer to form a laminated substrate;
Peeling the first substrate and the second substrate from the inside or the interface of the release layer under a negative pressure state;
A method for manufacturing a semiconductor device, comprising: The step of peeling the first substrate and the second substrate includes:
Insert the blade into the release layer of the laminated substrate,
The method of manufacturing a semiconductor device according to claim 7, wherein the method is performed by applying a force in a thickness direction of the multilayer substrate to the blade-like body. Before the step of peeling the first substrate and the second substrate,
9. The method of manufacturing a semiconductor device according to claim 7, further comprising the step of ablating the release layer by irradiating the release layer with laser light.

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