Fabrication method for device structure having transparent dielectric substrate
AssigneeOki Semiconductor Co., Ltd.
InventorsToshiyuki Nakamura, Satoshi Machida, Sachiko Yabe, Takashi Taguchi
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Abstract
A semiconductor device has a transparent dielectric substrate such as a sapphire substrate. To enable fabrication equipment to detect the presence of the substrate optically, the back surface of the substrate is coated with a triple-layer light-reflecting film, preferably a film in which a silicon oxide or silicon nitride layer is sandwiched between polycrystalline silicon layers. This structure provides high reflectance with a combined film thickness of less than half a micrometer.
Claims17
A method of fabricating a semiconductor integrated circuit chip comprising:
- preparing a wafer including a dielectric substrate that is transparent to light and having a front surface and a back surface, a first film formed on the back surface of the dielectric substrate, a second film formed on the first film, a third film formed on the second film, and a fourth film formed on the front surface, the second film having a lower refractive index than the first and third films;
- forming circuitry in and on the fourth film, and dicing the wafer into chips;
- and
- illuminating the third film by sensing light for detection of the wafer, during said forming,
- wherein the first, second and third films are formed to cover only selected parts of the dielectric substrate, so that the chips produced by the dicing do not include the first, second and third films.
A method of fabricating a semiconductor integrated circuit chip comprising:
- preparing a wafer including a dielectric substrate that is transparent to light and having a front surface and a back surface, a first film formed on the back surface of the dielectric substrate, a second film formed on the first film, a third film formed on the second film, and a fourth film formed on the front surface, the second film having a lower refractive index than the first and third films;
- forming circuitry in and on the fourth film, and dicing the wafer into chips;
- and
- illuminating the third film by sensing light for detection of the wafer, during said forming,
- wherein the first film comprises polysilicon, the second film comprises silicon oxide, and the third film includes polysilicon, and
- wherein the first film has a thickness of substantially 42 nm, the second film has a thickness of substantially 110 nm, and the third film has a thickness of substantially 42 nm.
A method of fabricating a semiconductor integrated circuit chip comprising:
- preparing a wafer including a dielectric substrate that is transparent to light and having a front surface and a back surface, a first film formed on the back surface of the dielectric substrate, a second film formed on the first film, a third film formed on the second film, and a fourth film formed on the front surface, the second film having a lower refractive index than the first and third films;
- forming circuitry in and on the fourth film, and dicing the wafer into chips;
- and
- illuminating the third film by sensing light for detection of the wafer, during said forming,
- wherein the first film comprises polysilicon, the second film comprises silicon nitride, and the third film comprises polysilicon, and
- wherein the first film has a thickness of substantially 42 nm, the second film has a thickness of substantially 80 nm, and the third film has a thickness of substantially 42 nm.
A method of fabricating a semiconductor integrated circuit chip comprising:
- preparing a wafer including a dielectric substrate that is transparent to light and having a front surface and a back surface, a first film formed on the back surface of the dielectric substrate, a second film formed on the first film, a third film formed on the second film, and a fourth film formed on the front surface, the second film having a lower refractive index than the first and third films;
- forming circuitry in and on the fourth film, and dicing the wafer into chips;
- and
- illuminating the third film by sensing light for detection of the wafer, during said forming,
- wherein the dielectric substrate has side surfaces, the method further comprising forming a sixth film covering the side surfaces,
- wherein the sixth film comprises polysilicon and silicon nitride, and
- wherein the sixth film also covers the back surface of the dielectric substrate, the sixth film disposed between the back surface and the first film.
Dependencies are inferred from the claim text.