Method for generating stable metal-silicide

Abstract

The invention belongs to the technical field of semiconductor device manufacturing, and provides a method for generating a stable metal-silicide in order to microcosmically generate a more stable metal compound, which comprises the following steps of: placing a substrate deposited with a metal layer in rapid thermal annealing equipment, and performing rapid thermal annealing, the process at least comprises a preheating stage: controlling a plurality of front lamp banks responsible for main heating in equipment, heating at a low power value of rated power, and uniformly heating a substrate from room temperature to a preset initial temperature for starting a reaction; and a main reaction stage: when the initial temperature is reached, controlling the equipment to heat to a peak temperature at a preset heating rate and performing heat preservation, so that the metal and the semiconductor fully react to generate a metal-silicide, thereby improving the reverse breakdown voltage of the barrier diode.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device manufacturing technology. Background Technology

[0002] The core performance of a metal-semiconductor contact diode lies in the rectifier junction formed between the metal layer and the semiconductor material, which determines the diode's key parameter: the maximum reverse voltage it can withstand in both on- and off-state states.

[0003] Current processes deposit a specific metal on a wafer, which is then rapidly thermally annealed to react with Si to form a stable metal compound, collectively referred to as a macroscopic metal compound. However, at the microscopic level, this compound exhibits two or more structural morphologies, including a metastable phase formed during the initial thermal treatment and a stable phase with superior performance, as desired. This is because the high power during the preheating stage of rapid thermal annealing bypasses the metastable phase and directly generates the stable phase. The initial nucleation and growth process of the metastable intermediate phase is disrupted, resulting in insufficient formation of the stable phase, poor structural uniformity, and inadequate density. This leads to the formation of a non-uniform, metastable stable phase, ultimately causing the device's reverse breakdown voltage to fall short of optimal performance. Summary of the Invention

[0004] To generate more stable metal compounds at the microscopic level to improve the reverse breakdown voltage (Vz) of barrier diodes, this invention provides a method for generating stable metal-silicides, the specific technical solution of which is as follows: A method for generating stable metal-silicides includes the following steps: Deposit a metal layer on a semiconductor wafer substrate to be heated; The deposited substrate is placed in a rapid thermal annealing apparatus with multiple independent heating lamps in each zone; Rapid thermal annealing is performed, which includes at least a preheating stage: multiple front lamp groups in the control device responsible for the main heating heat the substrate at a low power value of the rated power to uniformly heat the substrate from room temperature to a preset starting temperature for the reaction to begin; and a main reaction stage: after the starting temperature is reached, the control device heats the substrate to the peak temperature at a predetermined heating rate and holds it at the temperature to allow the metal and semiconductor to fully react and generate metal-silicide. Remove the unreacted metal layer to complete the formation of the contact structure.

[0005] Technical effect: In the rapid thermal annealing process for forming metal silicides, the power setting value of the main heating zone in the preheating stage is significantly reduced from the existing high power level to a specific low power range, thereby achieving a gentle start-up preheating process. This allows for the gradual and slow generation of a stable phase, resulting in a more complete metal-silicide microstructure and thus improving the key reverse electrical performance of the device. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0007] Figure 2 This is a schematic diagram showing the relationship between Si content and reaction temperature and the products generated in Example 1 of the present invention.

[0008] Figure 3 This is a schematic diagram showing the relationship between Si content and reaction temperature and the products generated in Example 2 of the present invention. Detailed Implementation

[0009] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0010] like Figure 1 As shown, this embodiment provides a method for generating stable metal-silicides, including depositing a metal layer on a semiconductor wafer substrate to be heated; placing the deposited substrate in a rapid thermal annealing apparatus with multiple independent heating lamp groups; performing rapid thermal annealing, which includes at least a preheating stage: multiple front lamp groups responsible for main heating in the control device heat the substrate at a low power value of rated power to uniformly heat the substrate from room temperature to a preset starting temperature for the reaction to begin; and a main reaction stage: after the starting temperature is reached, the control device heats the substrate to a peak temperature at a predetermined heating rate and holds it at that temperature to allow the metal and semiconductor to fully react and generate metal-silicides; and removing the unreacted metal layer to complete the formation of the contact structure.

[0011] Furthermore, the deposited metal layers include, but are not limited to, Ti-Si, Co-Si, Ni-Si, and Pt-Si.

[0012] Furthermore, during the preheating stage, the power value of the control equipment should be within the range of 5% to 25% of the rated power. This power should be driven by the equipment voltage, and the temperature at which the driving voltage is converted should be less than or equal to the temperature at which the metal-silicide begins to diffuse.

[0013] Furthermore, in this embodiment, the diameter of the front light assembly is larger than the size of the wafer to be heated inside the cavity.

[0014] The beneficial effects of the present invention will be further illustrated by two specific examples below.

[0015] Example 1: Metal-silicide Co-Si growth: First, a pure Co thin film is sputtered onto a silicon substrate, and the wafer is then fed into the RTP (Regenerative Thermal Phosphating) machine. In the first preheating stage, the front heating lamp power is set to 5-15%, slowly and uniformly heating the wafer to the initial Co-Si reaction temperature of 300°C. In the first main reaction stage, the temperature is rapidly increased to the peak target temperature of 500°C and held to form a uniform CoSi mesophase. Unreacted metal is then selectively etched away. In the second preheating stage, the front heating lamp power is set to 9-15%, slowly and uniformly heating the wafer to the initial Co-Si reaction temperature of 300°C. In the second main reaction stage, the temperature is rapidly increased to the peak target temperature of 690°C and held to completely convert the mesophase to CoSi2.

[0016] like Figure 2 As shown, the rapid thermal annealing temperature for the first step of metal-silicide Co-Si growth is approximately 450~550℃; the rapid thermal annealing temperature for the second step is approximately 650~800℃. Low power consumption can prevent premature island-like growth of CoSi2 and avoid insufficient formation of the CoSi mesophase, which can lead to uneven CoSi2 transformation later.

[0017] Example 2: Metal-silicide Ti-Si growth, requiring the formation of a stable TiSi2 phase with low resistivity. This growth is not a one-step process but involves many intermediate phase transitions, and the entire process is extremely sensitive to temperature, time, heating rate, and initial interface conditions. First, a pure Ti thin film is sputtered onto a silicon substrate, and then the wafer is fed into an RTP (Reverse Timing Process) machine. Figure 3 As shown, during the preheating stage, the power of the front heating lamp group is set to 9-25%, and the wafer is slowly and uniformly heated to the initial temperature of 450°C, where the Ti-Si reaction begins. When the temperature slowly rises to about 450°C, the deposited Ti film begins to undergo a significant solid-state reaction with the underlying Si substrate. Ti and Si diffuse bidirectionally, with Ti diffusion being faster than Si. First, silicides with high Ti content are formed, such as Ti5Si4 and Ti3Si. With further diffusion, TiSi / TiSi2 (the metastable C49 phase) is generated. The low-power preheating allows the adhesion of the two film layers before the formation of the Ti-Si metal compound without side reactions, avoiding premature formation of TiSi2. After the temperature continues to rise and crosses the critical temperature, the C49 phase begins to undergo an allotropic phase transition to the C54 phase.

[0018] In the main reaction stage, the temperature is gradually increased to the peak target temperature of 1000℃ and held at that temperature to form a uniform TiSi2. The above steps gradually and slowly generate the C49 phase → the C49 phase is saturated and transformed into the C54 phase, which can make the microstructure more complete.

[0019] This document uses two specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely illustrative of the method and its core ideas; it is neither necessary nor possible to exhaustively describe all possible implementations. The method provided by this invention is applicable to products using metal silicide technology, such as Schottky diodes, power metal-semiconductor field-effect transistors, Schottky barrier and success rate MOSFETs, and self-aligned silicide logic chips at the 45-180nm node. Furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for generating stable metal-silicides, characterized in that, Includes the following steps: Deposit a metal layer on a semiconductor wafer substrate to be heated; The deposited substrate is placed in a rapid thermal annealing apparatus with multiple independent heating lamps in each zone; Rapid thermal annealing is performed, which includes at least a preheating stage: multiple front lamp groups in the control device responsible for the main heating heat the substrate at a low power value of the rated power to uniformly heat the substrate from room temperature to a preset starting temperature for the reaction to begin; and a main reaction stage: after the starting temperature is reached, the control device heats the substrate to the peak temperature at a predetermined heating rate and holds it at the temperature to allow the metal and semiconductor to fully react and generate metal-silicide. Remove the unreacted metal layer to complete the formation of the contact structure.

2. The method for generating stable metal-silicides according to claim 1, characterized in that, The deposited metal layers include Ti-Si, Co-Si, Ni-Si, and Pt-Si.

3. The method for generating stable metal-silicides according to claim 1, characterized in that, During the preheating stage, the power value of the control equipment is within the range of 5% to 25% of the rated power, and the temperature of the drive voltage conversion is less than or equal to the temperature at which the metal-silicide begins to diffuse.

4. The method for generating stable metal-silicides according to claim 1, characterized in that, The diameter of the front light assembly must be larger than the size of the wafer to be heated inside the cavity.

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