JP2009054703A - Manufacturing method of transmission type liquid crystal display element substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method effectively using measures against head diffusion during bonding by a light shielding film formed on a transmission type liquid crystal display element substrate and the light shielding film. <P>SOLUTION: The manufacturing method includes a process of pattern-forming the light shielding film 21 on a transparent substrate 20 according to a transistor formation region 25, a process of forming a silicon oxide film 22 over the entire surface, a process of flattening the silicon oxide film 22, a process of bonding a silicon substrate 23 onto the silicon oxide film 22, a process of a hydrogen rich layer 24 at a predetermined position by hydrogen ion injection, a process of separating the silicon substrate 23 at the part of the hydrogen rich layer 24, a process of polishing and removing the hydrogen rich layer 24, and a process of forming an integrated circuit on the silicon film 22, wherein a recognition mark 21A and an ID marking portion 21B is formed during the pattern formation of the light shielding film 21, and the silicon oxide film 22 is irradiated with laser light from the side of the transparent substrate 20 while the irradiation quantity of the laser light is varied depending upon whether the light shield film 21 is present. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an SOI (Silicon on Insulator) substrate, and more particularly to a method of manufacturing a transmissive liquid crystal display element substrate using a transparent substrate.

  An SOI technology in which a silicon thin film is formed on an insulating substrate and a semiconductor device is formed on the silicon thin film has been widely studied because it has advantages such as higher element speed, lower power consumption, and higher integration. Such a technique is described in Patent Document 1. Since the background art is the same as that of the present application, it is described below with reference.

  As one of the SOI techniques, there is a technique for manufacturing an SOI substrate by bonding a single crystal silicon substrate. This technique, which is generally referred to as a bonding method, is performed by bonding a single crystal silicon substrate and a support substrate using hydrogen bonding force, and then the bonding strength is enhanced by heat treatment, and then the single crystal silicon substrate is ground or polished. Alternatively, a thin single crystal silicon layer is formed on a supporting substrate by etching. In this method, since a single-crystal silicon substrate is directly thinned, a high-performance device with excellent crystallinity of the silicon thin film can be produced.

  In addition, as an application of this bonding method, hydrogen ions are implanted into a single crystal silicon substrate, bonded to a support substrate, and then a thin film silicon layer is separated from a hydrogen implantation region of the single crystal silicon substrate by heat treatment. Support by the method (US Patent 5374564) or by epitaxially growing a single crystal silicon layer on a silicon substrate with a porous surface, bonding this to a support substrate, removing the silicon substrate, and etching the porous silicon layer A method of forming an epitaxial single crystal silicon thin film on a substrate (Japanese Patent Laid-Open No. 4-346418) is known. The SOI substrate by such a bonding method is used for manufacturing various devices in the same way as an ordinary bulk semiconductor substrate. However, as a feature different from the conventional bulk substrate, various materials are used for the support substrate. Can be mentioned. That is, as a support substrate, not only a normal silicon substrate but also a transparent quartz or glass substrate can be used. By forming a single-crystal silicon thin film on a transparent substrate, high-performance transistor elements using single-crystal silicon with excellent crystallinity for devices that require light transmission, such as transmissive liquid crystal display devices Can be formed.

  In the SOI substrate in which the transparent support substrate and the single crystal silicon thin film are bonded as described above, the single crystal silicon layer is used as a channel, source, or drain region of a transistor element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). If the substrate is transparent at this time, when light is irradiated from the back surface of the substrate, a leakage current due to light irradiation is generated in the channel region of the MOSFET, and the device characteristics deteriorate. (Here, the surface on which the single crystal silicon layer is formed is the front surface of the substrate, and the opposite side is the back surface.) This point will be specifically described with reference to the drawings. FIG. 2 is a sectional view of a bonded SOI substrate using a conventionally manufactured transparent substrate. In this SOI substrate, the single crystal silicon layer 2 is bonded to the support substrate 1 with the oxide film layer 3 interposed therebetween. Since the oxide film layer 3 described here generally has a light transmitting property, a conventional SOI substrate using a transparent material such as quartz or glass for the support substrate has a light shielding property under the single crystal silicon layer 2. That is, no layer is provided.

  FIG. 3 is a cross-sectional view of a MOSFET fabricated using the conventional SOI substrate shown in FIG. There is an oxide film layer 3 on the support substrate 1, and further there are a source region 2b, a channel region 2a, and a drain region 2c of a MOSFET formed by patterning the single crystal silicon layer. It is covered with a gate insulating film 2d formed by surface oxidation. A gate electrode 6 is provided on the gate insulating film 2 d, and the single crystal silicon region of the MOSFET and the gate electrode 6 are covered with a first interlayer film 7. Further, the source line 9 and the drain line 8 are connected to the source region 2b and the drain region 2c through the opening of the first interlayer film 7, respectively. A second interlayer film 10 is further formed thereon, and an upper light shielding layer 11 is formed on the second interlayer film 10. The upper light shielding layer 11 is formed of an opaque insulating material such as black polyimide resin or a metal thin film such as aluminum. When the light 12a is directly incident from the substrate surface side, light leakage due to the light 12a can be suppressed by the upper light shielding layer 11 in the channel region 2a of the MOSFET provided on the substrate. However, when the light indicated by 12c directly enters the MOSFET channel region 2a from the back surface of the substrate, light leakage cannot be prevented. Further, when there is light such as 12b reflected at the back side interface 1a of the substrate, even if it is incident from the substrate surface, a part of it reaches the channel region 2a of the MOSFET and causes light leakage. Become.

  That is, in the conventional SOI substrate shown in FIG. 2, since the light shielding layer is not provided between the support substrate 1 and the single crystal silicon layer 2, a MOSFET made of a single crystal silicon thin film is formed using this SOI substrate. In this case, the MOSFET channel region 2a cannot be shielded from the direct incident light 12c from the back surface of the substrate or the reflected light 12b from the back surface of the substrate. For this reason, the MOSFET manufactured with the SOI substrate having the conventional structure has a fundamental problem in that light leakage occurs and the characteristics of the element deteriorate. Further, it is difficult to use a transparent SOI substrate for a device using light, and there is a problem that versatility is low.

  An object of the invention according to Patent Document 1 is to provide an SOI substrate capable of manufacturing a semiconductor device that does not cause a problem of light leakage even when a transparent support substrate is used, and a manufacturing method thereof. Another object is to provide a high-performance semiconductor device using an SOI substrate that does not leak light and uses a transparent substrate.

  In order to achieve the above object, an embedded light shielding layer for preventing light leakage is provided between a transparent support substrate and a single crystal silicon layer formed thereon. The light shielding layer is formed on one surface of the support substrate, and the single crystal silicon layer is formed on the insulating layer deposited on the light shielding layer. The light shielding layer is patterned so as to cover the channel region of the MOSFET constituting the device to be manufactured, and there is no light shielding layer in a portion other than the channel region of the MOSFET. For this reason, it can be used for applications where the substrate needs to transmit light, such as a transmissive liquid crystal display device. In addition, by using a refractory metal or a silicon compound (silicide) as a material for the light shielding layer, the light shielding layer has sufficiently stable characteristics for thermal processes indispensable for MOSFET manufacturing such as impurity diffusion into a single crystal silicon layer. An SOI substrate can be manufactured.

JP-A-10-293320

  When a thin and transparent single crystal silicon is bonded to a transparent substrate through a transparent oxide film, and then put into an LSI manufacturing apparatus that processes a normal single crystal silicon substrate, the substrate is not recognized because the substrate is transparent. Therefore, a mark or the like for the LSI manufacturing apparatus to recognize must be created on the transparent substrate. Usually, since an opaque film is formed on the back surface of the transparent substrate, one step is required for that purpose.

  In addition, in order to leave a history of the substrate and the like on the transparent substrate, it is necessary to perform ID marking on each substrate. However, in order to perform the marking with a laser, the substrate is transparent, so that marking with high energy is required.

  After bonding the single crystal silicon substrate and the support substrate using hydrogen bonding force, the bonding strength is strengthened by heat treatment. When a method of irradiating an excimer laser is used as the heat treatment, a metal light-shielding film Depending on the presence or absence of, the heat treatment state to the bonded portion changes, and the adhesive strength becomes unstable.

at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
In the process of bonding the silicon substrate onto the silicon oxide film, a method of manufacturing a transmissive liquid crystal display element substrate in which the silicon oxide film is bonded by irradiating a laser from the transparent substrate side, and the amount of laser irradiation is changed depending on the presence or absence of a light shielding film. .

at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
A method of manufacturing a transmissive liquid crystal display element substrate in which a transparent substrate recognition mark is formed in a process of forming a pattern of a light shielding film in accordance with a transistor formation region.

at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
A method of manufacturing a transmissive liquid crystal display element substrate in which a transparent substrate ID stamped portion is formed in a process of forming a light shielding film in accordance with a transistor formation region.

  According to the first aspect of the present invention, the portion having the light shielding film is irradiated with laser with high energy, and the portion without the light shielding film is irradiated with laser with low energy, whereby the heat treatment of the bonded portion can be made uniform.

  According to the second aspect of the present invention, the transparent substrate recognition mark can be formed simultaneously with the patterning of the light shielding film by forming the transparent substrate recognition mark in the process of patterning the light shielding film in accordance with the transistor formation region. A formation process becomes unnecessary.

  According to the invention of claim 3, the transparent substrate ID marking portion is formed in the step of forming a pattern of the light shielding film in accordance with the transistor formation region, so that the low energy can be easily applied to the ID marking portion formed of the light shielding film with a laser or the like. ID marking is possible.

at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
In the process of patterning the light shielding film in accordance with the transistor formation region, the transparent substrate recognition mark and the transparent substrate ID stamped portion are formed using the light shielding film,
In the process of bonding the silicon substrate onto the silicon oxide film, a method of manufacturing a transmissive liquid crystal display element substrate in which the silicon oxide film is bonded by irradiating a laser from the transparent substrate side, and the amount of laser irradiation is changed depending on the presence or absence of a light shielding film. .

  FIG. 1 is a cross-sectional view of main steps for explaining a method for producing a transmission type liquid crystal display element substrate of the present invention. (A) is a step of forming a light shielding film on a transparent substrate, (B) is a step of forming a transparent substrate recognition mark and a transparent substrate ID stamped portion simultaneously with patterning the light shielding film in accordance with a transistor formation region, (C ) Is a step of forming and planarizing a silicon oxide film on the transparent substrate and the light shielding film pattern, (D) is a step of bonding the silicon substrate onto the silicon oxide film, and (E) is a predetermined position from the surface of the single crystal silicon substrate. (F) is a heating step for increasing the bonding strength between the bonded silicon oxide film 22 and the single crystal silicon substrate, and (G) is a hydrogen rich layer portion on the transparent substrate side. And the silicon substrate side are separated, the hydrogen-rich layer on the transparent substrate side is polished and removed to expose the single crystal silicon layer, and (H) is a step of forming an integrated circuit on the single crystal silicon.

  Step (A) is a step of forming a light shielding film 21 on the entire surface of a transparent substrate (for example, a quartz substrate) 20. The material of the light shielding film may be selected from those having high light-melting point metal, carbon, silicon carbide, metal silicide, silicon, and the like which are stable and light-shielding with respect to the maximum temperature of the LSI manufacturing process. The film forming means is appropriately selected from a sputtering method, a CVD method, an electron beam heating vapor deposition method and the like depending on the material, and the film thickness may be a thickness that can be shielded from light, but generally 1 μm or less is sufficient.

  Step (B) is patterning of the light shielding film 21, which is usually performed to form the light shielding film in accordance with the transistor arrangement to be formed, and to form the transparent substrate recognition mark 21 </ b> A and the transparent substrate ID marking portion 21 </ b> B on the outer peripheral portion of the transparent substrate 20. This is a step of patterning by the etching process. FIG. 4 is a top view of the transparent substrate 20 in which the light-shielding film 21 is patterned to form the transparent substrate recognition mark 21A and the transparent substrate ID marking portion 21B (other patterns are omitted).

  In the step (C), an insulating film, for example, a silicon oxide film 22 is formed to ensure insulation between the patterned light-shielding film 21 and a single crystal silicon substrate to be attached (adhered) in a subsequent process. The silicon oxide film is formed by means such as sputtering or plasma CVD, but is formed to a thickness that sufficiently covers the groove of the patterned light shielding film. Thereafter, the surface of the silicon oxide film 22 is planarized by a CMP (Chemical Mechanical Polishing) method in order to attach a single crystal silicon substrate.

  Step (D) is a step of bonding the single crystal silicon substrate 23 to the surface of the planarized silicon oxide film 22. For example, a single crystal silicon substrate having a thickness of 300 μm is directly bonded, and heat treatment is performed at 300 ° C. for about 2 hours.

  Step (E) is a step of forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the single crystal silicon substrate 23, and hydrogen ions are implanted into the single crystal silicon substrate 23. The position at which the high concentration layer (hydrogen rich layer) 24 of hydrogen ions is formed varies depending on the acceleration voltage and dose of hydrogen ions (H +). By performing the heat treatment, the single crystal silicon substrate 23 can be separated by the hydrogen-rich layer 24.

  Step (F) is a heating step for increasing the bonding strength between the bonded silicon oxide film 22 and the single crystal silicon substrate 23. In this embodiment, the bonding surface is heated by an excimer laser from the transparent substrate 20 side to be bonded. is doing. In the method of heating the whole, since the thermal expansion coefficients of the metal film and the base substrate are different, the difference in the thermal expansion coefficient is large as a whole. When the difference in thermal expansion coefficient is forcibly adhered, the stress is concentrated, and the thin film semiconductor substrate is peeled off in a later process, or the thin film semiconductor substrate has deteriorated characteristics. By using an excimer laser and partially advancing the adhesion, the stress generated by the difference in thermal expansion coefficient can be reduced. In addition, the base substrate and the thin film semiconductor substrate can be gradually bonded by partially bonding, that is, the stress at the bonding can be relieved by using the adjacent non-bonded region. And distortion due to adhesion to the substrate can be reduced. It can be used as a good thin film semiconductor substrate. In particular, the present invention is very effective for the present invention in which a metal film is formed in a pattern. Since the light shielding film has good thermal conductivity, heat diffuses in the light shielding film and the bonded surface cannot be melted, so the laser irradiation power must be increased. In the figure, a graph of laser irradiation power (laser energy) is added, but irradiation is performed by changing the laser irradiation power depending on the presence or absence of a light shielding film. In the figure, the change is made in two steps, but it is preferable to further adjust the laser irradiation power according to the area of the light shielding film. It may be possible to reduce the shadow of the light shielding film by changing the incident angle of the laser. A uniform adhesive force can be obtained by adjusting the laser irradiation power.

  Step (G) is a step of separating the transparent substrate 20 side and the single crystal silicon substrate 23 side at the hydrogen rich layer 24 part, polishing and removing the hydrogen rich layer 24 on the transparent substrate 20 side, and exposing the single crystal silicon layer. It is. Thereby, an SOI substrate in which the light shielding film pattern is formed on the transparent substrate 20 is completed. In the figure, various films are shown thick for easy understanding. For example, the light shielding film is 400 nm, the silicon oxide film is 500 nm, and the single crystal silicon substrate (single crystal silicon film) is about 200 nm.

  Step (H) is a step of forming the transistor 25 and other circuit elements on the single crystal silicon substrate 23 by the LSI manufacturing process, and is a general LSI manufacturing step. In this step, it goes without saying that the transparent substrate recognition mark 21A and the transparent substrate ID stamped portion 21B are used as formed in the step (B).

Sectional drawing of the main process for demonstrating the manufacturing method of the transmissive liquid crystal display element substrate of this invention Cross section of bonded SOI substrate using transparent substrate manufactured in the past Cross-sectional view of a MOSFET fabricated using a conventional SOI substrate Top view of a transparent substrate on which a light-shielding film is patterned to form a transparent substrate recognition mark and a transparent substrate ID stamped portion (other patterns are omitted)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 2 Single crystal silicon layer 2a Channel region 2b Source region 2c Drain region 2d Gate insulating film 3 Oxide film layer 4 Light shielding layer 5 Insulating layer 6 Gate electrode 7 First interlayer film 8 Drain line 9 Source line 10 Interlayer film 11 Upper light shielding layer 12a Incident light 12b from substrate surface side Reflected light 12c Incident light from substrate back side 20 Transparent substrate 21 Light shielding film 21A Transparent substrate recognition mark 21B ID marking portion 22 Silicon oxide film 23 Single crystal silicon substrate 24 Hydrogen rich layer 25 transistors

Claims (3)

at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
A transmissive liquid crystal display element substrate characterized in that, in the step of bonding the silicon substrate onto the silicon oxide film, the silicon oxide film is bonded by irradiating the laser from the transparent substrate side, and the laser irradiation amount is changed depending on the presence or absence of the light shielding film. Manufacturing method. at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
A transparent substrate recognition mark is formed in a step of forming a pattern of a light shielding film in accordance with a transistor formation region. at least,
Forming a light shielding film on a transparent substrate;
Forming a pattern of the light shielding film in accordance with the transistor formation region;
Forming a silicon oxide film on the transparent substrate and the light-shielding film pattern;
A step of planarizing the silicon oxide film;
Bonding a silicon substrate on a silicon oxide film;
Forming a hydrogen rich layer by hydrogen implantation at a predetermined position from the surface of the silicon oxide film;
Separating the transparent substrate side and the silicon substrate side at the hydrogen-rich layer portion;
Polishing and removing the hydrogen-rich layer on the transparent substrate side to expose the single crystal silicon;
In a method for manufacturing a transmissive liquid crystal display element substrate comprising a step of forming an integrated circuit on single crystal silicon,
A method of manufacturing a transmissive liquid crystal display element substrate, comprising forming a transparent substrate ID stamped portion in a step of patterning a light shielding film in accordance with a transistor formation region.

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