X-ray image sensor and method for fabricating the same

• US 6,423,973 B2
• Filed: 12/29/2000
• Issued: 07/23/2002
• Est. Priority Date: 12/31/1999
• Status: Expired due to Term

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Choo, Kyo-Seop, Park, June-Ho
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US09/750,244
• Publication Number:
  US 20010013577A1
• Time in Patent Office: 571 Days
• Field of Search: 250/370.09, 438/96
• US Class Current: 250/370.09
• CPC Class Codes: H01L 27/14665 Imagers using a photoconductor layer
• CPC Class Codes: H01L 27/14696 The active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe

Abstract

An X-ray image sensor fabricated using eight-mask steps. A thin film transistor (TFT) having a gate electrode, a first insulation layer, pure and doped amorphous silicon layers, and source and drain electrodes is on a substrate. An island-shaped first insulation layer, semiconductor layer, and ground line are also formed. A second insulation layer having a first drain contact hole and a ground line contact hole covers the TFT, the substrate, and the ground line. An auxiliary drain electrode on the second insulation layer contacts the drain electrode through the first drain contact hole. A capacitor electrode on the second insulation layer contacts the ground line through the ground line contact hole. A third insulation layer having a second drain contact hole that exposes the auxiliary drain is on the second insulation layer, the auxiliary drain electrode, and the capacitor electrode. A pixel electrode on the third insulation layer contacts the auxiliary drain electrode through the second drain contact hole.

Claims

1. An X-ray image sensor, comprising:

a substrate having a pixel region and a switching region at one corner of the pixel region;

a thin film transistor (TFT) formed in the switching region, the TFT having a gate electrode, a first insulation layer, a pure amorphous silicon layer, a doped amorphous silicon layer, and source and drain electrodes;

an island-shaped first insulation layer and an island-shaped semiconductor layer formed in the pixel region;

a ground line formed on the island-shaped semiconductor layer;

a second insulation layer formed on the TFT, on the substrate; and

on the ground line, the second insulation layer having a first drain contact hole which exposes a portion of the drain electrode, and a ground line contact hole which exposes a portion of the ground line;

an auxiliary drain electrode formed on the second insulation layer and contacting the drain electrode through the first drain contact hole;

a capacitor electrode formed on the second insulation layer and contacting the ground line through the ground line contact hole;

a third insulation layer formed on the second insulation layer, on the auxiliary drain electrode and on the capacitor electrode, the third insulation layer having a second drain contact hole which exposes a portion of the auxiliary drain electrode; and

a pixel electrode formed on the third insulation layer and contacting the auxiliary drain electrode through the second drain contact hole.

2. An X-ray image sensor according to claim 1, wherein the pixel electrode extends over the source and drain electrodes.

3. An X-ray image sensor according to claim 1, wherein the second insulation layer is made of BCB (benzocyclobutene).

4. An X-ray image sensor according to claim 1, wherein the auxiliary drain electrode and the capacitor electrode are made of a transparent conductive material.

5. A method for fabricating an X-ray image sensor, comprising:

providing a substrate that has a pixel region with a switching region at one corner and portions for data and gate lines;

forming a gate electrode, a data pad connector and a data pad on the substrate by depositing and patterning a first metallic material using a first mask process;

sequentially forming a first insulation layer, a pure amorphous silicon layer and a doped amorphous silicon layer such that the first insulation layer covers the substrate, the gate electrode, the data pad connector, and the data pad;

forming a first data pad contact hole, a semiconductor layer, and an island-shaped semiconductor layer by patterning the doped amorphous silicon layer, the pure amorphous silicon layers, and the first insulation layer using a second mask process, wherein a first data contact hole exposes a portion of the data pad connector;

forming a data line, a source electrode, a drain electrode, and a ground line on the semiconductor layer and on the island-shaped semiconductor layer by depositing and patterning a second metallic material using a third mask process, wherein the data line contacts the data pad connector through the first data pad contact hole;

forming a second insulation layer on the TFT, on the substrate, and on the ground line;

forming a first drain contact hole and a ground line contact hole by patterning the second insulation layer using a fourth mask process, wherein a first drain contact hole exposes a portion of the drain electrode, and a ground line contact hole exposes a portion of the ground line;

forming an auxiliary drain electrode and a capacitor electrode on the second insulation layer by depositing and patterning a transparent conductive material using a fifth mask process, wherein an auxiliary drain electrode contacts the drain electrode through the first drain contact hole, and wherein a capacitor electrode contacts the ground line through the ground line contact hole;

forming the third insulation layer on the second insulation layer, on the auxiliary drain electrode, and on the capacitor electrode;

forming a second drain contact hole to expose a portion of the auxiliary drain electrode by patterning the third insulation layer using a sixth mask process;

forming a pixel electrode on the third insulation layer by depositing and patterning a transparent conductive material using a seventh mask process, wherein the pixel electrode contacts the auxiliary drain electrode through the second drain contact hole; and

forming a second data pad contact hole to expose a portion of the data pad by patterning the first, second, and third insulation layers, and the pure and doped amorphous silicon layers.

6. A method for fabricating an X-ray image sensor according to claim 5, wherein the second insulation layer is formed from BCB (Benzocyclobutene).

7. A method for fabricating an X-ray image sensor according to claim 5, further comprising, forming a channel region by removing a portion of the doped amorphous silicon layer over the pure amorphous silicon layer using the source and drain electrodes as masks.

8. A method for fabricating an X-ray image sensor according to claim 5, wherein the auxiliary drain electrode, the capacitor electrode and the pixel electrode are formed from indium tin oxide (ITO).

9. A method for fabricating an X-ray image sensor according to claim 5, wherein the auxiliary drain electrode, the capacitor electrode and the pixel electrode are formed from indium zinc oxide (IZO).

10. A method for fabricating an X-ray image sensor according to claim 5, wherein the gate electrode, the data pad connector and the data pad are formed from a material selected from a group consisting of aluminum (Al) and aluminum-neodymium (AlNd).