US-12618716-B2 - Thermal image sensor and method of manufacturing the same

US12618716B2US 12618716 B2US12618716 B2US 12618716B2US-12618716-B2

Abstract

A thermal image sensor and a method of manufacturing the same are provided. A row electrode and a column electrode are formed on a substrate. A multi-layer stack includes a sensing layer, a first sensing electrode and a second sensing electrode which are in contact with the sensing layer with a channel formed between the first sensing electrode and the second sensing electrode, an absorbing electrode connected to the first sensing electrode, an insulating layer configured to insulate the absorbing electrode from the second sensing electrode and the sensing layer, and a protecting layer configured to cover an exterior. Supports are configured to allow the multi-layer stack to float with respect to the substrate. A first intervening electrode and a second intervening electrode are configured to connect the low electrode and the column electrode to the first sensing electrode and the second sensing electrode through the supports.

Inventors

Byong Gwon SONG
Jin Myoung KIM
Jae Chul Park
Yong Seop YOON
Du Hyun Lee
Jae Kwan Kim
Choong Ho RHEE

Assignees

SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20240409
Priority Date: 20231228

Claims (20)

1 . A thermal image sensor comprising: a substrate; a multi-layer stack that is suspended above the substrate and comprises: a sensing layer configured to convert light energy into heat energy; a first sensing electrode and a second sensing electrode which are in contact with the sensing layer; a channel formed between the first sensing electrode and the second sensing electrode, an absorbing electrode connected to the first sensing electrode and configured to generate polarization in the sensing layer, an insulating layer configured to insulate the absorbing electrode from the second sensing electrode and the sensing layer; and wherein the substrate is configured to detect a change in a temperature of the sensing layer.
2 . The thermal image sensor of claim 1 , wherein: the substrate is positioned further away from the first sensing electrode and the second sensing electrode than from the sensing layer; and the substrate is positioned further away from the absorbing electrode than from the first sensing electrode and the second sensing electrode.
3 . The thermal image sensor of claim 1 , wherein: the substrate is positioned further away from the first sensing electrode and the second sensing electrode than from the sensing layer; and the substrate is positioned closer to the absorbing electrode than to the sensing layer.
4 . The thermal image sensor of claim 1 , wherein: the substrate is positioned closer to the first sensing electrode and the second sensing electrode than to the sensing layer; and the substrate is positioned further away from the absorbing electrode than from the sensing layer.
5 . The thermal image sensor of claim 1 , wherein: the substrate is positioned closer to the first sensing electrode and the second sensing electrode than to the sensing layer; and the substrate is positioned closer to the absorbing electrode than to the first sensing electrode and the second sensing electrode.
6 . The thermal image sensor of claim 1 , wherein a center region of the absorbing electrode corresponds to a center region of the channel provided between the first sensing electrode and the second sensing electrode.
7 . The thermal image sensor of claim 1 , wherein the multi-layer stack further comprises a resistance reducing layer provided between the first sensing electrode and the sensing layer and between the second sensing electrode and the sensing layer.
8 . The thermal image sensor of claim 7 , wherein the resistance reducing layer contains a donor impurity and an acceptor impurity.
9 . The thermal image sensor of claim 1 , wherein the absorbing electrode comprises titanium nitride (Tin).
10 . A bolometer comprising: a substrate; a supporting arm provided on the substrate; and a multi-layer stack that is suspended above the substrate through the supporting arm and comprises: a sensing layer configured to convert light energy into heat energy; a first sensing electrode and a second sensing electrode which are in contact with the sensing layer; a channel formed between the first sensing electrode and the second sensing electrode; and an absorbing electrode connected to the first sensing electrode and configured to generate polarization in the sensing layer, wherein the substrate comprises at least one electrode connected to the first sensing electrode and the second sensing electrode to detect a change in a temperature of the sensing layer.
11 . A method of manufacturing a thermal image sensor, the method comprising: (a) forming a row electrode and a column electrode on a substrate, followed by sequentially stacking a sacrificial layer and a protecting layer; (b) forming anchor holes to expose the row electrode and the column electrode by etching through the protecting layer to the sacrificial layer, and then patterning a first intervening electrode and a second intervening electrode in the anchor holes and the protecting layer; (c) forming a multi-layer stack on the protecting layer, the multi-layer stack comprising a sensing layer, a first sensing electrode and a second sensing electrode which are in contact with the sensing layer with a channel formed between the first sensing electrode and the second sensing electrode, and are connected to the first intervening electrode and the second intervening electrode, an absorbing electrode connected to the first sensing electrode, and an insulating layer configured to insulate the absorbing electrode from the second sensing electrode and the sensing layer; and (d) removing the sacrificial layer.
12 . The method of claim 11 , wherein the step (c) comprises: forming the sensing layer on the protecting layer; forming the first sensing electrode and the second sensing electrode on the sensing layer to connect the first sensing electrode and the second sensing electrode to the first intervening electrode and the second intervening electrode; forming the insulating layer to cover the first sensing electrode, the second sensing electrode, and the sensing layer; and forming a via hole to expose the first sensing electrode in the insulating layer, and then forming the absorbing electrode in the via hole and the insulating layer.
13 . The method of claim 11 , wherein the step (c) comprises: forming the absorbing electrode on the protecting layer; forming the insulating layer to cover the absorbing electrode; forming the sensing layer on the insulating layer; and forming a via hole to expose the absorbing electrode in the insulating layer, and then forming the first sensing electrode in the via hole and the sensing layer to connect the first sensing electrode to the first intervening electrode, and forming the second sensing electrode on the sensing layer to connect the second sensing electrode to the second intervening electrode.
14 . The method of claim 11 , wherein the step (c) comprises: forming the first sensing electrode and the second sensing electrode on the protecting layer to connect the first sensing electrode and the second sensing electrode to the first intervening electrode and the second intervening electrode; forming the sensing layer on the first sensing electrode and the second sensing electrode; forming the insulating layer to cover the first sensing electrode, the second sensing electrode, and the sensing layer; and forming a via hole to expose the first sensing electrode in the insulating layer, and then forming the absorbing electrode in the via hole and the insulating layer.
15 . The method of claim 11 , wherein the step (c) comprises: forming the absorbing electrode on the protecting layer; forming the insulating layer to cover the absorbing electrode; forming a via hole to expose the absorbing electrode in the insulating layer, and then forming the first sensing electrode in the via hole and the insulating layer to connect the first sensing electrode to the first intervening electrode, and forming the second sensing electrode on the insulating layer to connect the second sensing electrode to the second intervening electrode; and forming the sensing layer on the first sensing electrode and the second sensing electrode.
16 . The method of claim 11 , wherein the step (c) comprises forming a resistance reducing layer between the first sensing electrode and the sensing layer and between the second sensing electrode and the sensing layer.
17 . The method of claim 16 , wherein the resistance reducing layer contains a donor impurity and an acceptor impurity.
18 . The method of claim 11 , wherein the absorbing electrode comprises titanium nitride (Tin).
19 . The method of claim 11 , wherein the first sensing electrode and the second sensing electrode comprise titanium nitride (Tin).
20 . The method of claim 11 , wherein the sensing layer comprises Amorphous Silicon.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application claims priority from Korean Patent Application No. 10-2023-0193898, filed on Dec. 28, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND 1. Field Apparatuses and methods consistent with embodiments of the disclosure relate to a thermal image sensor for converting incoming light energy in a predetermined wavelength range into heat energy and outputting the heat energy to generate image data. 2. Description of the Related Art The sensing materials of uncooled Long-wave Infrared (LWIR) sensors have been developed into two types: Vanadium oxide (VOx) and amorphous silicon (a-Si). Recently, in consideration of compatibility with the CMOS manufacturing process, sensors using the PN diode have reached a commercialization stage, and besides, research has been conducted on various devices/materials and the like for use in uncooled LWIR sensors. Responsivity, which represents the sensitivity of the LWIR sensor, is defined by how efficiently the LWIR sensor converts input power into a voltage value. The responsivity is determined based on parameters, such as input power, readout current, sensor resistance, and temperature change. If the sensor resistance value and readout current are the same, higher temperature Coefficient of Resistance (TCR), which indicates resistance change characteristics according to the inherent temperature of a material, is more effective in increasing the responsivity. Alternatively, in the case of applying a semiconductor material, such as α-Si, to a sensing material, responsivity may be increased by allowing for higher current flow at lower input voltages, assuming that the Temperature Coefficient of Resistance (TCR) is constant. There have been proposed methods for improving thermal capacity and thermal conductivity of a sensing unit in order to increase responsivity, but in a bolometer structure using a semiconductor material such as α-Si, a method of increasing the width of a sensing electrode is proposed or structural changes for adjusting the spacing between sensing electrodes are proposed in order to improve current characteristics of the sensing unit. In a bolometer pixel, as the thermal conductivity and thermal capacity decreases, the change in temperature of the sensing unit increases under the same input power conditions. As the pixel size decreases in order to increase the resolution of a sensor, a method for reducing thermal conductivity is required. A widely known method involves increasing the length of a support arm that supports a sensing unit, but the method has a problem in that the effective area of the sensor is limited. Accordingly, decreasing the thermal capacity of the sensor is important in improving the sensor performance. In the existing sensing materials such as Vox and α-Si described above, the sensor is in the form of a surface, such that the effect of decreasing the thermal capacity of the sensor is limited. SUMMARY According to an aspect of an example embodiment, a thermal image sensor may include: a multi-layer stack including: a sensing layer configure to convert light energy into heat energy; a first sensing electrode and a second sensing electrode which are in contact with the sensing layer; a channel formed between the first sensing electrode and the second sensing electrode, an absorbing electrode connected to the first sensing electrode, an insulating layer configured to insulate the absorbing electrode from the second sensing electrode and the sensing layer; and a substrate physically separated from the sensing layer and configured to detect a change in a temperature of the sensing layer. The substrate is positioned further away from the first sensing electrode and the second sensing electrode than from the sensing layer; and the substrate is positioned further away from the absorbing electrode than from the first sensing electrode and the second sensing electrode. The substrate is positioned further away from the first sensing electrode and the second sensing electrode than from the sensing layer; and the substrate is positioned closer to the absorbing electrode than to the sensing layer. The substrate is positioned closer to the first sensing electrode and the second sensing electrode than to the sensing layer; and the substrate is positioned further away from the absorbing electrode than from the sensing layer. The substrate is positioned closer to the first sensing electrode and the second sensing electrode than to the sensing layer; and the substrate is positioned closer to the absorbing electrode than to the first sensing electrode and the second sensing electrode. A center region of the absorbing electrode corresponds to a center region of the channel provided between the first sensing electrode and the second sensing electrode. The multi-layer stack may further include a resistance reducing layer prov