Mesa type diode

Abstract

A diode according to some embodiments of the concept of the present invention comprises: a lower electrode; a substrate on the lower electrode; an epitaxial layer located on the substrate and having a width narrower than that of the substrate; a high-concentration region and a low-concentration region on the epitaxial layer; and an upper electrode on the high-concentration region. The high-concentration region has a width narrower than that of the epitaxial layer. The low-concentration region is located on the side of the high-concentration region. The lower surface of the high-concentration region is closer to the substrate than the lower surface of the low-concentration region.

Description

Technology Field

[0001] The present invention relates to a diode, and more specifically to a mesa-type diode. Background Technology

[0002] The receiver of an RF system is composed of very precise circuits designed to achieve high sensitivity in order to process weak signals received at the receiver. Due to these structural characteristics, the receiver of an RF system is very vulnerable to strong electromagnetic signals and interference signals, and such overload signals can cause the destruction and malfunction of the system. The problem to be solved

[0003] Embodiments according to the concept of the present invention aim to provide a mesa-type diode for minimizing the electric field at the mesa interface. means of solving the problem

[0004] A diode according to some embodiments comprises: a lower electrode; a substrate on the lower electrode; an epitaxial layer located on the substrate and having a width narrower than that of the substrate; a high concentration region and a low concentration region on the epitaxial layer; and an upper electrode on the high concentration region, wherein the high concentration region has a width narrower than that of the epitaxial layer, the low concentration region is located on the side of the high concentration region, and the lower surface of the high concentration region may be closer to the substrate than the lower surface of the low concentration region. Effects of the invention

[0005] In the diode according to embodiments of the concept of the present invention, as the lower surface of the high-concentration region is closer to the substrate than the lower surface of the low-concentration region, the electric field generated at the mesa interface can be mitigated and the breakdown voltage can be adjusted. Brief explanation of the drawing

[0006] FIG. 1 is a cross-sectional view of a diode according to some embodiments. FIGS. 2a, 2b, 2c, 2d, and 2e are cross-sectional views illustrating a method for manufacturing the diode of FIG. 1. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a diode according to some embodiments. FIG. 4 is a circuit diagram of a protection circuit using a diode according to some embodiments. Specific details for implementing the invention

[0007] Hereinafter, a diode according to embodiments of the concept of the present invention will be described in detail with reference to the drawings.

[0008] FIG. 1 is a cross-sectional view of a diode according to some embodiments.

[0009] Referring to FIG. 1, the diode may include a lower electrode (142), a substrate (101) on the lower electrode (142), an epitaxial layer (102) on the substrate (101), a high concentration region (112) and a low concentration region (111) on the epitaxial layer (102), and an upper electrode (141) on the high concentration region (112).

[0010] The lower electrode (142) may have the form of a plate extending along a plane extending in a first direction (D1) and a second direction (D2). The first direction (D1) and the second direction (D2) may intersect each other. For example, the first direction (D1) and the second direction (D2) may be horizontal directions orthogonal to each other. The lower electrode (142) may include a conductive material.

[0011] A substrate (101) may be provided on a lower electrode (142). The substrate (101) may be in contact with the lower electrode (142). The substrate (101) may have the form of a plate extending along a plane extending in a first direction (D1) and a second direction (D2).

[0012] An epitaxial layer (102) may be provided on a substrate (101). The epitaxial layer (102) may be in contact with the substrate (101). The width of the epitaxial layer (102) may be smaller than the width of the substrate (101). The width of the epitaxial layer (102) may become narrower along the third direction (D3). The width of the epitaxial layer (102) may become narrower as it moves away from the substrate (101). A high-concentration region (112) and a low-concentration region (111) may be provided on the epitaxial layer (102). The width of the high-concentration region (112) may be narrower than the width of the epitaxial layer (102). The low-concentration region (111) may be in contact with the side (122s) of the high-concentration region (112). The low concentration region (111) may be located on the side (122s) of the high concentration region (112). The low concentration region (111) may surround a portion of the high concentration region (112). The lower surface (112b) of the high concentration region (112) and the lower surface (111b) of the low concentration region (111) may be in contact with the epitaxial layer (102). The level of the lower surface (112b) of the high concentration region (112) may be lower than the level of the lower surface (111b) of the low concentration region (111). The lower surface (112b) of the high concentration region (112) may be closer to the substrate (101) than the lower surface (111b) of the low concentration region (111). The side (112s) of the high concentration region (112) may be curved. The side (112s) of the high concentration region (112) may have a curved shape. The bottom surface (111b) of the low concentration region (111) may be flat. The bottom surface (111b) of the low concentration region (111) may have a straight shape.

[0013] In some embodiments, the substrate (101) may be an N+-doped semiconductor substrate, the epitaxial layer (102) may be N-doped at a lower concentration than the substrate (101), the high concentration region (112) may be P+-doped, and the low concentration region (111) may be P-doped at a lower concentration than the high concentration region (112). In this case, the substrate (101) may be a silicon substrate doped with impurities such as a Group 5 element, such as phosphorus (P), arsenic (As), or antimony (Sb).

[0014] In some embodiments, the substrate (101) may be a P+-doped semiconductor substrate, the epitaxial layer (102) may be P-doped at a lower concentration than the substrate (101), the high concentration region (112) may be N+-doped, and the low concentration region (111) may be N-doped at a lower concentration than the high concentration region (112). In this case, the substrate (101) may be a silicon substrate doped with group 3 impurities such as boron (B), aluminum (Al), etc., for example. An upper electrode (141) may be provided on the high concentration region (112). The upper electrode (141) may include a conductive material. The width of the upper electrode (141) may be smaller than the width of the epitaxial layer (102). The width of the portion of the upper electrode (141) that contacts the high concentration region (112) may be smaller than the width of the uppermost portion of the upper electrode (141).

[0015] The concentration and depth of the high concentration region (112) and the low concentration region (111) can be adjusted using an ion implantation process.

[0016] In some embodiments, a field oxide film (123) may surround the epitaxial layer (102), the low-concentration region (111), and the high-concentration region (112). The field oxide film (123) may surround the sides of the epitaxial layer (102). The field oxide film (123) may be for isolation between devices. A portion of the field oxide film (123) may overlap with the top electrode (141). A portion of the high-concentration region (112) may be covered by the field oxide film (123). The top electrode (141) may cover a portion of the field oxide film (123). The interface between the field oxide film (123) and the epitaxial layer (102) and the interface between the field oxide film (123) and the low-concentration region (111) may be defined as a mesa interface (131). A low concentration region (111) may be provided between the high concentration region (112) and the field oxide film (123).

[0017] In some embodiments, as a low-concentration region (111) is positioned adjacent to the mesa interface (131), the electric field generated at the mesa interface (131) between the field oxide film (123) and the epitaxial layer (102) can be mitigated. As the electric field generated at the mesa interface (131) is mitigated, the breakdown voltage of the diode can be adjusted, and a high-power signal can be stably controlled.

[0019] FIGS. 2a, 2b, 2c, 2d, and 2e are cross-sectional views illustrating a method for manufacturing the diode of FIG. 1 according to some embodiments.

[0020] Referring to FIG. 2a, a substrate (101) may be provided. An epitaxial layer (102) covering the upper surface of the substrate (101) may be formed. The epitaxial layer (102) may be formed through epitaxial growth. An initial oxide film (121) covering the upper surface of the epitaxial layer (102) may be formed.

[0021] Referring to FIG. 2b, a low concentration region (111) can be formed. The low concentration region (111) can be formed using an ion implantation process. A portion of the epitaxial layer (102) doped with impurities by the ion implantation process can be defined as the low concentration region (111). The impurities can pass through the initial oxide film (121) and be doped into the epitaxial layer (102). The low concentration region (111) can be formed between the epitaxial layer (102) and the initial oxide film (121).

[0022] Referring to FIG. 2c, a high concentration region (112) can be formed. Forming the high concentration region (112) may include defining a first region to which the high concentration region (112) is to be formed using a photo process, and forming the high concentration region (112) by performing an ion implantation process on the first region.

[0023] A heat treatment process can be performed. During the heat treatment process, the high-concentration region (112), which is doped with a high concentration, can diffuse deeper than the low-concentration region (111), which is doped with a low concentration. The thickness of the epitaxial layer (102) can be adjusted by adjusting the depth of diffusion. Depending on the depth of diffusion, the capacitance characteristics of the diode can be adjusted. An oxide can be additionally applied to the initial oxide film (121) to form a masking oxide film (122). The masking oxide film (122) can be thicker than the initial oxide film (121).

[0024] In some embodiments, a low concentration region (111) can be formed after a high concentration region (112). Subsequently, the high concentration region (112) and the low concentration region (111) can be diffused through a heat treatment process.

[0025] Referring to FIG. 2d, the masking oxide film (122), the low-concentration region (111), and the epitaxial layer (102) can be etched. Etching the masking oxide film (122), the low-concentration region (111), and the epitaxial layer (102) may include performing a photolithography process and an etching process to remove a portion of the masking oxide film (122), a portion of the low-concentration region (111), and a portion of the epitaxial layer (102). In some embodiments, a portion of the substrate (101) may be removed along with a portion of the masking oxide film (122), a portion of the low-concentration region (111), and a portion of the epitaxial layer (102). Subsequently, the remaining masking oxide film (122) may be removed. A portion of the epitaxial layer (102) and a portion of the low-concentration region (111) may be removed to form a mesa structure.

[0026] Referring to FIG. 2e, a field oxide film (123) covering a substrate (101), an epitaxial layer (102), a low concentration region (111), and a high concentration region (112) can be formed.

[0027] Referring to FIG. 1, an upper electrode (141) and a lower electrode (142) may be formed. Forming the upper electrode (141) may include removing a portion of the field oxide film (123) on the high-concentration region (112) and applying a conductive material to form the upper electrode (141). The lower electrode (142) may be formed to be in contact with the lower surface of the substrate (101).

[0028] In some embodiments, the distance from the substrate of the lower surface (111b) of the low concentration region (111) and the lower surface (112b) of the high concentration region can be individually adjusted according to the heat treatment process, and the breakdown voltage and capacitance characteristics of the diode can be adjusted. The breakdown voltage and capacitance characteristics of the diode can be adjusted by adjusting the width of the low concentration region (111), which is the distance between the mesa interface (131) and the high concentration region (112). The breakdown voltage and capacitance characteristics of the diode can be adjusted by adjusting the concentration of the low concentration region (111) and the high concentration region (112).

[0030] FIG. 3 is a cross-sectional view illustrating a method for manufacturing a diode according to some embodiments.

[0031] Referring to FIG. 3, a substrate (101), an epitaxial layer (102), and an initial oxide film (121) can be formed similarly to that described in FIG. 2a.

[0032] In some embodiments, after forming an initial oxide film (121), a low concentration region (111) may be formed similarly to that described in FIG. 2b. Subsequently, a portion of the initial oxide film (121) may be removed, and a high concentration region (112) may be formed through an ion implantation process.

[0033] In some embodiments, after forming an initial oxide film (121), a portion of the initial oxide film (121) may be removed and a high concentration region (112) may be formed through an ion implantation process. Subsequently, a low concentration region (111) may be formed by performing an ion implantation process through the initial oxide film (121).

[0034] After forming the high concentration region (112) and the low concentration region (111), the upper electrode (141), the lower electrode (142), and the field oxide film (123) can be formed similarly to those described in FIG. 2d, 2e and 1.

[0036] FIG. 4 is a circuit diagram of a protection circuit using a diode according to some embodiments.

[0037] Referring to FIG. 4, a protection circuit (400) using a diode may include an input terminal (IN), an output terminal (OUT), DC blocks (403), a diode (401), and an RF choke (402). The DC block (403) may be connected to the input terminal (IN) or the output terminal (OUT). The diode (401) may be connected between the DC blocks (403). The diode (401) may be similar to the diode described in FIG. 1. The RF choke (402) may be connected between the DC blocks (403). A Low Noise Amplifier (LNA) may be connected to the output terminal (OUT).

[0038] The protection circuit (400) may include a diode (401). As the diode (401) is similar to the diode described in FIG. 1, the circuit (400) can pass a small signal, attenuate and transmit a large power signal above a threshold value, minimize the parasitic capacitance of the diode (401), and have a high breakdown voltage characteristic. Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications and changes are possible by those skilled in the art within the technical spirit and scope of the present invention.

Claims

Claim 1 A diode comprising: a lower electrode; a substrate on the lower electrode; an epitaxial layer located on the substrate and having a width narrower than that of the substrate; a high-concentration region and a low-concentration region on the epitaxial layer; and an upper electrode on the high-concentration region, wherein the high-concentration region has a width narrower than that of the epitaxial layer, the low-concentration region is located on the side of the high-concentration region, the lower surface of the high-concentration region is closer to the substrate than the lower surface of the low-concentration region, the high-concentration region protrudes into the interior of the epitaxial layer, the epitaxial layer has a first conductivity type, and the high-concentration region and the low-concentration region have a second conductivity type. Claim 2 A diode according to claim 1, wherein the substrate is an N+-doped semiconductor substrate, the epitaxial layer is N-- doped at a lower concentration than the substrate, and the high-concentration region is P+-doped. Claim 3 A diode according to claim 1, wherein the substrate is a P+ doped semiconductor substrate, the epitaxial layer is P- doped at a lower concentration than the substrate, and the high concentration region is N+ doped. Claim 4 A diode according to claim 1, comprising the epitaxial layer and a field oxide film covering the low-concentration region. Claim 5 In claim 4, the upper electrode covers a portion of the field oxide film, and the field oxide film covers a portion of the high concentration region, the diode. Claim 6 In claim 4, a diode located in the low concentration region between the high concentration region and the field oxide film. Claim 7 A diode according to claim 1, wherein the width of the epitaxial layer narrows as it moves away from the substrate. Claim 8 A diode according to claim 1, wherein the width of the high-concentration region is narrower than the width of the epitaxial layer, and the side of the high-concentration region has a curved shape. Claim 9 A diode according to claim 1, wherein the width of the portion where the upper electrode contacts the high concentration region is smaller than the width of the uppermost portion of the upper electrode. Claim 10 A diode according to claim 1, comprising the epitaxial layer and a field oxide film covering the low-concentration region, and comprising a mesa interface defined as an interface between the field oxide film and the epitaxial layer and an interface between the field oxide film and the low-concentration region.

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