A device preparation method applied to laser simulation of single event effects

Abstract

The application discloses a device preparation method applied to laser simulation of single particle effect, and belongs to the MOSFET preparation field, and comprises the following steps: providing a substrate, forming an epitaxial layer on the surface of the substrate; forming a P well according to the pattern of a P well mask; manufacturing an N+ source end and a P+ body contact end according to the requirements of the device; forming a polycrystal gate control end according to the requirements of the device; performing a metal Ti-TiN-Al combined layer deposition process; manufacturing a first Mask and a second Mask of a metal mask according to the function of the device and the requirements of a laser beam; and performing a two-step etching process of metal etching, so as to form a device required by laser simulation of single particle effect. The two-step metal etching of dry method and wet method is adopted, the lower metal is reserved, all N+ source ends and P+ body contact ends can be fully utilized, all device design structures such as a strip gate, a hexagonal gate and a pin-shaped gate can be simultaneously covered, and the device is not limited.

Description

A method for fabricating devices for simulating single-event effects in lasers Technical Field

[0001] This invention relates to the field of MOSFET fabrication technology, and in particular to a method for fabricating a device for simulating single-event effects using lasers. Background Technology

[0002] Space is filled with various types of ionizing radiation, high-energy particles, and cosmic rays. Therefore, devices used in aerospace applications must be resistant to TID (Total Ionizing Dose) and SEE (Single Event Effect). For MOSFET devices used in space environments, single event effects are a major limitation in the high-density heavy-ion environment. Single event effects mainly include single-event gate breakdown (SEGR) and single-event burn-out (SEB), with SEB being the most frequent. SEB occurs when heavy ions pass through the device's structural region, epitaxial region, and substrate region, generating a large number of electron-hole pairs. Under the influence of an electric field, these holes migrate towards the base region, eventually forming a current. When the current density reaches a certain level, it causes the parasitic transistor to turn on, ultimately leading to device burn-out. Therefore, laser simulation is crucial for rapidly characterizing single event effects.

[0003] In the fabrication of devices for simulating single-event effects using lasers, a substrate material with low resistivity is required. Epitaxy is then performed on this substrate material to achieve the necessary resistivity and thickness, and the fabrication method required for laser simulation is then employed. Devices fabricated using conventional methods often have thick metal layers that obstruct laser light penetration, making single-event characterization impossible and failing to meet the requirements for simulating single-event effects in laser simulations. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating devices for simulating single-event effects in lasers, so as to solve the problem that existing devices cannot be rapidly characterized for simulating single-event effects in lasers after fabrication.

[0005] To address the aforementioned technical problems, this invention provides a method for fabricating a device used in simulating single-event effects in lasers, comprising:

[0006] Provide a substrate, and form an epitaxial layer on its surface;

[0007] The P-well is fabricated according to the pattern of the P-well mask;

[0008] Fabricate the N+ source terminal and P+ body contact terminal according to the device requirements;

[0009] Form the polysilicon gate control terminal according to device requirements;

[0010] Perform a metal Ti-TiN-Al composite layer deposition process;

[0011] Fabricate the first and second masks of the metal photomask according to the device function and laser beam requirements;

[0012] A two-step metal corrosion process is proposed to form the device required for laser simulation of single particles.

[0013] In one embodiment, a two-step metal etching process is proposed to form the device required for laser-simulated single-particle etching, including:

[0014] The first step involves using a common metal photomask pattern as the first mask, and then performing dry etching to complete the etching of the metal Ti-TiN-Al composite layer, forming the gate and source terminals required for the device function.

[0015] The second step involves using a laser-etched metal mask pattern and a wet etching method with dilute hydrochloric acid (HCl). This method only etches the Al in the Ti-TiN-Al composite metal layer, leaving the etching on TiN. This forms the chip locations required for laser-simulated single-particle irradiation.

[0016] In one embodiment, the substrate is a high-concentration, low-resistivity substrate made of silicon or silicon carbide with a resistivity of 0.002-0.004 Ω·cm; the epitaxial layer has a resistivity of 0.3-24 Ω·cm and a thickness of 3µm-50µm.

[0017] In one embodiment, the process of forming the P-well according to the pattern of the P-well mask includes:

[0018] P-type impurities are injected into the pattern of the P-well mask and then subjected to high-temperature annealing; among which,

[0019] The P-type impurities include B and BF2, and the injection dose is 1E12-1E14 cm⁻¹. -2 The energy is 50-100 KeV.

[0020] In one embodiment, fabricating the N+ source terminal and P+ body terminal according to device requirements includes:

[0021] N-type impurities were implanted at the N+ source site, with an implantation dose of 5E14-1E16 cm⁻¹. -2 The energy is 50-80 KeV. After implantation, high-temperature annealing is performed to form N+ source terminals. The N-type impurities include P, As, and In.

[0022] P-type impurities were implanted at the contact point of the P+ body preparation, with an implantation dose of 5E14-5E15 cm⁻¹. -2The energy is 50-100 KeV. After injection, high-temperature annealing is performed to form P+ body contact ends. The P-type impurities include B and BF2.

[0023] In one embodiment, forming a polygate control terminal according to device requirements includes:

[0024] A silicon dioxide layer is formed on the surface by gate oxide oxidation at a growth temperature of 800℃-1050℃ and a thickness of 30nm-1000nm; a polycrystalline layer is formed on the surface of the silicon dioxide layer by polycrystalline silicon deposition.

[0025] Photolithography and etching are performed on the silicon dioxide layer and polycrystalline layer to expose the N+ source terminal and P+ body contact terminal, while the silicon dioxide layer and polycrystalline layer in other areas are retained to form the polycrystalline gate control terminal.

[0026] In one embodiment, before performing the metal Ti-TiN-Al combined layer deposition process, the process further includes: depositing a metal pre-dielectric layer on the entire surface and etching it to expose the P+ body contact and part of the N+ source, with the remaining PMD covering the polycrystalline gate control.

[0027] In one embodiment, the metal Ti-TiN-Al composite layer is composed of a Ti layer, a TiN layer, and an Al layer from bottom to top; wherein the thickness of the Ti layer is 10-100 nm, the thickness of the TiN layer is 20-150 nm, and the thickness of the Al layer is 4-8 μm.

[0028] The present invention provides a method for fabricating a device for simulating single-event effects in lasers, which has the following beneficial effects:

[0029] (1) Using a metal Ti-TiN-Al composite layer, a two-step metal etching process of dry + wet is carried out to form a power device that meets the requirements of high current characteristics.

[0030] (2) The two-step metal etching method of dry method + wet method is adopted, and the lower metal layer is retained, so that all N+ source terminals and P+ body contact terminals can be fully utilized. It can simultaneously cover all device design structures such as bar grid, hexagonal grid, and triangular grid without restriction.

[0031] (3) The formed power device metal layer meets the characterization requirements of power devices for fast laser simulation of single-event effects. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the fabrication process of a device for simulating single-event effects in lasers, provided by the present invention.

[0033] Figure 2 is a schematic diagram of a structure in which a substrate is provided and an epitaxial layer is formed on its surface.

[0034] Figure 3 is a schematic diagram of the structure for fabricating the P-well photomask and forming the P-well.

[0035] Figure 4 is a schematic diagram of the structure for fabricating the N+ source end and the P+ body contact end.

[0036] Figure 5 is a schematic diagram of the structure for gate oxide oxidation and polysilicon deposition.

[0037] Figure 6 is a schematic diagram of the structure for fabricating the polygate control terminal.

[0038] Figure 7 is a schematic diagram of the structure after PMD deposition and etching.

[0039] Figure 8 is a schematic diagram of the structure forming the metal Ti-TiN-Al composite layer.

[0040] Figure 9 is a schematic diagram of the first mask and wet etching structure for fabricating a metal photomask.

[0041] Figure 10 is a schematic diagram of the second mask and dry etching structure for fabricating a metal photomask. Detailed Implementation

[0042] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for fabricating a device for simulating single-event effects in lasers, based on the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0043] This invention provides a method for fabricating a device for simulating single-event effects in lasers, the process of which is shown in Figure 1 and includes the following steps:

[0044] Step S11: Provide a substrate and form an epitaxial layer on its surface;

[0045] Step S12: Fabricate the P-well according to the pattern of the P-well mask;

[0046] Step S13: Fabricate the N+ source terminal and P+ body contact terminal according to the device requirements;

[0047] Step S14: Fabricate the polygate control terminal according to the device requirements;

[0048] Step S15: Perform the deposition process of the metal Ti-TiN-Al composite layer;

[0049] Step S16: Fabricate the pattern of the metal mask. First Mask photolithography and etching are performed to form the metal contacts that fully function the power device.

[0050] Step S17: Fabricate the pattern of the metal mask according to the laser beam requirements. Perform second mask lithography and etching to form a metal gap that the laser beam can pass through.

[0051] First, a substrate 1 is provided, which has the characteristics of high energy density and low resistivity. The material can be silicon or silicon carbide. In this embodiment, a silicon substrate is used as an example, and its resistivity is 0.002-0.004 Ω·cm. An epitaxial layer 2 is formed on the surface of the substrate 1. The resistivity of the epitaxial layer 2 is 3-24 Ohm, and the thickness is 3um-50um, as shown in Figure 2.

[0052] Fabricate a P-well photomask according to device requirements, with an injection dose of 1E12-1E14 cm⁻¹. -2 P-type impurities such as B and BF2 with energies of 50-100 KeV are implanted and then subjected to high-temperature annealing to form a P-well 3 with the PN junction of the N-type substrate, as shown in Figure 3.

[0053] According to device requirements, N+ source terminal 41 and P+ body contact terminal 42 are fabricated. N-type impurities such as P, As, and In are implanted at the location where the N+ source terminal is fabricated, with an implantation dose of 5E14-1E16 cm⁻¹. -2 The energy is 50-80 KeV. After implantation, high-temperature annealing is performed to form the N+ source end 41. P-type impurities such as B and BF2 are implanted at the P+ body contact end, with an implantation dose of 5E14-5E15 cm⁻¹. -2 The energy is 50-100 KeV. After injection, high-temperature annealing is performed to form P+ body contact end 42; as shown in Figure 4.

[0054] A silicon dioxide layer 5 is formed by gate oxide oxidation on the surface, with a growth temperature of 800℃-1050℃ and a thickness of 30nm-1000nm; a polycrystalline silicon layer 6 is formed by polycrystalline silicon deposition on the surface of the silicon dioxide layer 5, as shown in Figure 5.

[0055] Photolithography and etching are performed on silicon dioxide layer 5 and polycrystalline layer 6 to expose N+ source terminal 41 and P+ body contact terminal 42, while silicon dioxide layer 5 and polycrystalline layer 6 in other areas are retained to form polycrystalline gate control terminals, as shown in Figure 6.

[0056] PMD (pre-metal dielectric layer) is deposited on the entire surface and etched to expose the P+ body contact 42 and part of the N+ source 41. The remaining PMD covers the polygate control terminal, as shown in Figure 7.

[0057] Ti layer 8, TiN 9 and Al layer 10 are deposited sequentially to form a metal Ti-TiN-Al composite layer, as shown in Figure 8; wherein the thickness of the Ti layer is 10-100 nm, the thickness of the TiN layer is 20-150 nm, and the thickness of the Al layer is 4-8 μm.

[0058] According to the functional requirements of the device, the pattern of the metal photomask is fabricated using the first Mask11 and wet etching to form the metal contact that completes the function of the power device, so that the device can reach the normal working state, as shown in Figure 9.

[0059] The pattern of the metal mask is fabricated according to the requirements of the laser beam. The second Mask12 is then dry etched to form a metal gap that the laser beam can pass through, as shown in Figure 10. Since dilute hydrochloric acid (HCl) is used, only the Al layer is etched, and the etching stops at the TiN layer. Therefore, the thick Al metal at the top of the Ti-TiN-Al composite layer is broken with a gap, while the Ti-TiN metal at the bottom is still connected together, forming the chip position required for laser simulation of single particles for laser irradiation.

[0060] The metal layer of the power device fabricated through the above main processes meets the characterization requirements for rapid laser simulation of single-event effects in power devices. The Ti-TiN-Al metal composite layer is subjected to a two-step metal etching process (dry + wet) to form a power device that meets the requirements for high current characteristics without affecting the testing and evaluation of other device parameters. The two-step metal etching process (dry + wet) retains the underlying metal layer, allowing full utilization of all N+ source regions and P+ body regions. It can simultaneously cover all device design structures such as bar grids, hexagonal grids, and triangular grids without limitation.

[0061] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for fabricating a device for simulating single-event effects in lasers, characterized in that, include: Provide a substrate and form an epitaxial layer on its surface; fabricate a P-well according to the pattern of the P-well mask; Fabricate N+ source terminals and P+ body contacts according to device requirements; form polycrystalline gate control terminals according to device requirements; perform metal Ti-TiN-Al composite layer deposition process; fabricate the first and second masks of the metal photomask according to device function and laser beam requirements; A two-step metal etching process is proposed to form the device required for laser simulation of single particles. The fabrication of the P-well according to the pattern of the P-well mask includes: injecting P-type impurities into the pattern of the P-well mask and performing high-temperature annealing; wherein the P-type impurities include B and BF2, and the injection dose is 1E12-1E14 cm⁻¹. -2 The energy is 50-100 KeV; the fabrication of N+ source terminals and P+ body contacts according to device requirements includes: implanting N-type impurities at the location where the N+ source terminal is fabricated, with an implantation dose of 5E14-1E16 cm⁻¹. -2 The energy is 50-80 keV. After implantation, high-temperature annealing is performed to form the N+ source end. The N-type impurities include P, As, and In. P-type impurities are implanted at the contact end of the P+ body at a dose of 5E14-5E15 cm⁻¹. -2 The energy is 50-100 KeV. After implantation, high-temperature annealing is performed to form the P+ body contact terminal. The P-type impurities include B and BF2. Forming the polycrystalline gate control terminal according to device requirements includes: oxidizing the surface to form a silicon dioxide layer at a growth temperature of 800℃-1050℃ and a thickness of 30nm-1000nm; depositing polycrystalline silicon on the surface of the silicon dioxide layer to form a polycrystalline layer; performing photolithography and etching on the silicon dioxide layer and polycrystalline layer to expose the N+ source terminal and the P+ body contact terminal, while retaining the silicon dioxide layer and polycrystalline layer in other areas to form the polycrystalline gate control terminal. The two-step metal etching process for forming the device required for laser-simulated single-particle lasers includes: First, using a standard metal photomask pattern (Mask 1), dry etching is performed to complete the etching of the Ti-TiN-Al composite layer, forming the metal contacts necessary for the full functionality of the power device. Second, using a laser-etched metal photomask pattern (Mask 2), wet etching is performed using dilute hydrochloric acid (HCl). This process only etches the Al in the Ti-TiN-Al composite layer, leaving the etching at the TiN. The thick Al at the top is broken with gaps, forming the chip positions required for laser-simulated single-particle laser irradiation.

2. The method for fabricating a device for simulating single-event effects in lasers as described in claim 1, characterized in that, The substrate is a high-concentration, low-resistivity substrate made of silicon or silicon carbide, with a resistivity of 0.002-0.004 Ω·cm; the epitaxial layer has a resistivity of 0.3-24 Ω·cm and a thickness of 3µm-50µm.

3. The method for fabricating a device for simulating single-event effects in lasers as described in claim 1, characterized in that, Before performing the metal Ti-TiN-Al combined layer deposition process, the process also includes: depositing a metal pre-dielectric layer on the entire surface and etching it to expose the P+ bulk contact and part of the N+ source, with the remaining PMD covering the polycrystalline gate control.

4. The method for fabricating a device for simulating single-event effects in lasers as described in claim 1, characterized in that, The metal Ti-TiN-Al composite layer consists of a Ti layer, a TiN layer, and an Al layer from bottom to top; wherein the thickness of the Ti layer is 10-100 nm, the thickness of the TiN layer is 20-150 nm, and the thickness of the Al layer is 4-8 μm.

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