JPH0550429U - Drive board for light valve device - Google Patents

Abstract

(57) [Summary] [Structure] The single crystal silicon thin film 1 on which the drive electrodes and the drive elements are formed and the carrier layer 2 are bonded together by an adhesive 3 which cures at room temperature. [Effect] In the bonding process, since the curing of the adhesive is performed in the normal temperature range, the temperature change during the curing of the adhesive is reduced, so that the warpage of the driving substrate due to the difference in the coefficient of thermal expansion between the silicon and the carrier layer is suppressed. it can.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flat type light valve device used for a direct view type display device, a projection type display device and the like. More specifically, the present invention relates to an active matrix type light valve device including a semiconductor thin film substrate in which a driving circuit and a pixel electrode group are integrally formed.

[0002]

[Prior Art]

 The principle of the active matrix device is relatively simple. Each pixel is provided with a switch element and the corresponding switch element is made conductive when a specific pixel is selected, and the switch element is made non-conductive when not selected. It is something to keep. The individual switch elements are formed on the semiconductor thin film substrate that constitutes the light valve device.

Conventionally, in an active matrix type light valve device, a thin film transistor is formed on a surface of an amorphous silicon thin film deposited on a glass substrate and used as a driving substrate. Since the amorphous silicon thin film and the polycrystalline silicon thin film can be easily deposited on the glass substrate by using the physical vapor deposition method or the chemical vapor deposition method, an active matrix type light valve device having a relatively large screen is manufactured. Suitable for

Further, as an active matrix type light valve device in which the thin film switch element is miniaturized and the pixel electrode is highly densified, a drive substrate in which a single crystal silicon thin film layer is formed on a glass plate which is a carrier layer is used. The one used is proposed. This makes it possible to realize an ultra-compact high-definition active matrix type light valve device used for projection display devices and the like.

FIG. 9 shows an ultrahigh-density active matrix light valve device having a single crystal silicon thin film layer. As shown in the figure, the light valve device comprises a counter substrate 11 facing the driving substrate 14 at a predetermined interval, and an electro-optical material layer, for example, a liquid crystal layer 12 filled in the previous period. The surface of the drive substrate 14 is covered with an alignment film 13 for aligning the liquid crystal molecules contained in the liquid crystal layer 12. Each pixel electrode formed in the pixel region of the driving substrate 14 is selectively excited by conduction of a corresponding transistor element and acts on the liquid crystal layer 12 to control its light transmission characteristics and act as a light valve. Since the size of each pixel electrode is about 1 μm, an extremely high-definition active matrix liquid crystal device can be obtained.

FIG. 10 is an enlarged view of the drive substrate 14 shown in FIG. Here, the single crystal silicon thin film layer 10 on which the pixel electrode and its driving element are formed is bonded onto a carrier layer, for example, a quartz glass plate 2. Adhesion is performed here with an adhesive 15. The manufacturing process of the drive substrate of this light valve device is the first process of forming various semiconductor elements such as drive electrodes and drive circuits on the surface of a single crystal silicon wafer by a semiconductor manufacturing process (hereinafter, the wafer obtained by the first process). Is called an IC wafer), a second step of adhering the surface of the IC wafer on which the elements are formed to the glass plate, and the surface of the IC wafer on which the elements are not formed is polished or removed to form a single crystal silicon thin film. And a third step of forming a layer.

[0007]

[Problems to be solved by the device]

 However, in the drive substrate of the conventional light valve device using amorphous and polycrystalline silicon thin films, the silicon thin film was formed directly on the glass plate, but the light valve using single crystal silicon thin film was used. In the drive circuit of the device, the IC wafer and the glass plate must be bonded (corresponding to the second step, hereinafter abbreviated as the bonding step). Usually, an adhesive is used for adhesion.

In the bonding step using an adhesive, the adhesive layer transmits light, there are no bubbles in the adhesive layer, the adhesive layer has a uniform thickness, and the substrate does not warp after bonding. It is necessary to consider quality such as not occurring, ensuring sufficient adhesive strength, and having resistance to post-process and usage environment. Before the adhesive is cured by bonding the IC wafer and the glass plate together, because the thermal expansion coefficient of the IC wafer and the glass plate will differ if the temperature change accompanying the curing of the adhesive is large in the bonding process. Although no warpage occurs in the, the warpage occurs after the adhesive is cured.

FIG. 6, FIG. 7, and FIG. 8 schematically show an example in which a thermosetting adhesive is used as an adhesive. As shown in FIG. 6, the drive substrate of the light valve device in which the thermosetting adhesive (liquid) 7 is applied on the IC wafer 1 and the quartz plate glass 2 is placed thereon is a thermosetting adhesive ( No warpage occurred before the liquid 7 was cured. Since the temperature becomes high during heating, as shown in FIG. 7, the thermosetting adhesive (during curing) 8 becomes more solid than the IC wafer 1 and the quartz glass plate 2 in the expanded state as compared with normal temperature. .. When the temperature returns to room temperature after the adhesive is cured, the IC wafer 1 and the quartz glass plate 2 shrink, but at this time, the quartz glass plate 2 has a larger coefficient of thermal expansion than the IC wafer 1, so the shrinkage amount becomes large. .. Therefore, after returning to normal temperature, the drive substrate of the light valve device is warped as shown in FIG.

As described above, when the drive substrate of the light valve device is warped, the optical characteristics are changed, it is difficult to parallelize the device with the device in the post process of the bonding process, and the stress due to the warp is caused. However, there is a problem that reliability is lowered due to damage or susceptibility to damage of the element formed on the surface. Even if the warp is corrected by some method, there are problems such as damage to the element due to stress generated by the correction and deterioration of reliability, and price increase due to the need for new parts for correction. There is.

As described above, the drive substrate of the conventional light valve device has many drawbacks. Therefore, in order to solve such a drawback, the present invention aims to obtain a drive substrate of a light valve device in which warpage is suppressed as much as possible.

[0012]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a semiconductor single crystal thin film layer in which a carrier layer, a drive electrode, and a drive circuit for exciting the drive electrode in response to a predetermined signal are integrally formed. In a drive substrate of a light valve device comprising an adhesive layer interposed between the carrier layer and the semiconductor single crystal thin film layer, the adhesive step is performed by using an adhesive that cures at room temperature. The change in temperature due to the curing of the adhesive at 2 is reduced, and the occurrence of warpage is minimized.

[0013]

[Action]

 According to the above configuration, since the adhesive curing in the bonding step is performed in the normal temperature range, the temperature change during the curing of the adhesive is much smaller than that when the thermosetting adhesive is used. .. Therefore, the amount of expansion and contraction of the IC wafer and glass plate due to the temperature change also decreases. Therefore, it is possible to minimize the occurrence of warpage of the drive substrate of the light valve device before and after the adhesive is cured due to the difference in thermal expansion coefficient between the IC wafer and the glass plate. By suppressing the warp, changes in optical characteristics due to the warp are suppressed, parallelism with the device in the subsequent process can be maintained, and stress generation due to the warp is also suppressed. Since it is not necessary to correct the price, it is possible to suppress the price increase due to extra parts and so on.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 are vertical cross-sectional views of a drive substrate of a light valve device according to a first embodiment of the present invention, that is, before and after curing an adhesive when an ultraviolet curable adhesive is used. .. In FIG. 1, an element for driving a liquid crystal panel is formed on the surface of an IC wafer 1. An ultraviolet curable adhesive (liquid) 3 is applied to the side of the IC wafer 1 on which the elements are formed. A quartz glass plate 2 which is a carrier layer having the same shape as the IC wafer 1 is placed on the ultraviolet curable adhesive (liquid) 3. FIG. 2 shows that the drive substrate of the light valve device of FIG. 1 is irradiated with ultraviolet rays from the quartz glass plate 2 side so that the ultraviolet curable adhesive (liquid) 3 becomes the ultraviolet curable adhesive (solid) 4. ing . Here, since the temperature change during curing is small, the drive substrate of the light valve device does not warp as after curing when using a thermosetting adhesive. Also, the adhesive curing time is short because it is only the time of irradiating with ultraviolet rays.

Therefore, the mass productivity is excellent and the delivery time can be shortened. In this embodiment, the case where quartz glass is used as the glass plate has been described, but it is needless to say that the present invention is not limited to this, and the same applies when various other glasses are used. FIG. 3 shows a completed drive substrate of the light valve device by removing the back surface of the IC wafer 1 of FIG. 2 and leaving only the single crystal silicon thin film layer 10 on which the semiconductor elements are formed. This allows light to pass through the substrate.

FIG. 4 and FIG. 5 are respectively a second embodiment of the drive substrate of the light valve device according to the present invention, that is, before the adhesive curing and when the epoxy resin-based room temperature curing adhesive is used. FIG. In FIG. 4, an epoxy resin-based room temperature curing adhesive (liquid) 5 is applied on the IC wafer 1, and a quartz glass plate 2 having the same shape as the IC wafer 1 is placed on it. .. In FIG. 5, the driving substrate of the light valve device of FIG. 4 has passed a predetermined adhesive curing time, and the epoxy resin room temperature curing adhesive (liquid) 5 is replaced with the epoxy resin room temperature curing adhesive (solid) 6 It has become. Here, since the adhesive is hardened at room temperature, there is basically no change in temperature during hardening. Therefore, the warp of the drive substrate of the light valve device due to the difference in the coefficient of thermal expansion between the IC wafer 1 and the quartz glass plate 2 does not occur. Further, since the heating tank, the irradiation device, etc. are not required to cure the adhesive, the bonding can be performed easily and the capital investment can be reduced.

[0017]

[Effect of the device]

 As described above, the present invention can suppress warpage by using an adhesive that hardens at room temperature as an adhesive for the drive substrate of the light valve device. By providing a drive substrate for the light valve device that is easy to perform and has less damage to the element due to stress, there is an effect that a higher quality light valve device can be obtained.

[Brief description of drawings]

FIG. 1 is a first embodiment of a drive substrate of a light valve device according to the present invention.
FIG. 3 is a schematic vertical sectional view of the adhesive before being cured.

FIG. 2 is a first embodiment of a drive substrate of a light valve device according to the present invention.
FIG. 3 is a schematic vertical cross-sectional view after the adhesive is cured.

FIG. 3 is a first embodiment of a drive substrate of a light valve device according to the present invention.
FIG. 6 is a schematic vertical cross-sectional view after the back surface is removed.

FIG. 4 is a second embodiment of the drive substrate of the light valve device according to the present invention.
FIG. 3 is a schematic vertical sectional view of the adhesive before being cured.

FIG. 5 is a second embodiment of the drive substrate of the light valve device according to the present invention.
FIG. 3 is a schematic vertical cross-sectional view after the adhesive is cured.

FIG. 6 is a schematic vertical cross-sectional view before hardening of an adhesive on a drive substrate of a conventional light valve device.

FIG. 7 is a schematic vertical cross-sectional view of the drive substrate of the conventional light valve device during curing of the adhesive (when heated).

FIG. 8 is a schematic vertical cross-sectional view after the adhesive is cured on the drive substrate of the conventional light valve device.

FIG. 9 is a tangential vertical sectional view of an active matrix type light valve device.

FIG. 10 is a contact type enlarged sectional view of a drive substrate portion of the active matrix type light valve device.

[Explanation of symbols]

 1 IC Wafer 2 Quartz Glass Plate 3 Ultraviolet Curing Adhesive (Liquid) 4 Ultraviolet Curing Adhesive (Solid) 5 Epoxy Resin Room Temperature Curing Adhesive (Liquid) 6 Epoxy Resin Room Temperature Curing Adhesive (Solid) 7 Thermosetting adhesive (liquid) 8 Thermosetting adhesive (during curing) 9 Thermosetting adhesive (solid) 10 Single crystal silicon thin film layer 11 Counter substrate 12 Liquid crystal layer 13 Alignment film 14 Drive substrate 15 Adhesive

Claims (2)

[Scope of utility model registration request] 1. A drive substrate on which a drive electrode and a drive circuit for exciting the drive electrode in response to a predetermined signal are formed, a counter substrate arranged to face the drive substrate, the drive substrate, and the drive substrate. In the drive substrate of a light valve device having an electro-optic material layer disposed between opposing substrates as a main component, the drive substrate is a carrier layer, the drive electrode and the drive circuit are integrated. The semiconductor single crystal thin film layer is formed, and a three-layer structure comprising an adhesive layer interposed between the carrier layer and the semiconductor single crystal thin film layer, the adhesive is of a type that cures at room temperature. The drive substrate of the light valve device is characterized in that the drive substrate is prevented from warping after being adhered. 2. The drive substrate for the light valve device according to claim 1, wherein the adhesive layer is formed of an ultraviolet curable adhesive.