System for monitoring thin film stress on silicon wafer in real time

Abstract

The invention discloses a system for monitoring film stress on a silicon wafer in real time, belongs to the field of stress monitoring, and aims to solve the problem that the film stress cannot be monitored in real time in the prior art. The one or more cantilever beams are arranged on the thin film, microstructures are arranged on the one or more cantilever beams and the thin film, and the 3D confocal microscope is used for measuring bending characteristics of the one or more cantilever beams; and the controller is used for calculating the stress value of the corresponding cantilever beam as the stress value of the corresponding position of the film according to the bending characteristics of one or more cantilever beams. The method is used for monitoring the stress of the thin film on the silicon wafer in real time.

Description

Technical Field

[0001] The invention belongs to the field of stress monitoring and belongs to a chip preparation method. Background Art

[0002] Measuring the film stress on silicon wafers is a decisive factor in measuring the performance, stability and reliability of silicon wafers. The existing method is to measure the film stress once after the film is deposited on the silicon wafer. After the stress meets the measurement index, the silicon wafer is further subjected to microstructures through etching, photolithography, and front-end processes. However, the application of microstructures will affect the film stress. Therefore, the existing method only measures the stress once before applying the microstructure, and fails to monitor the film stress in real time. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing film stress cannot be monitored in real time, and a system for real-time monitoring of film stress on a silicon wafer is proposed.

[0004] A system for real-time monitoring of film stress on a silicon wafer, the system comprising a silicon wafer, a film and a microstructure, the film being deposited on the silicon wafer, the system comprising one or more cantilevers, a 3D confocal microscope and a controller;

[0005] One or more cantilever beams are arranged on the film, and microstructures are arranged on the one or more cantilever beams and the film. The 3D confocal microscope is used to measure the bending characteristics of the one or more cantilever beams; and the controller is used to calculate the stress value of the corresponding cantilever beam as the stress value of the corresponding position of the film according to the bending characteristics of the one or more cantilever beams.

[0006] Preferably, the bending characteristics of the cantilever beam include radius of curvature, thickness, length and width.

[0007] Preferably, the silicon body is a single crystal silicon body.

[0008] Preferably, the thin film material is prepared from two layers of materials, the two layers of materials are silicon oxide and silicon nitride, the silicon oxide is laid on the silicon body, and the silicon nitride is laid on the silicon oxide.

[0009] Preferably, the microstructure includes a deposited layer, a measuring resistor, a metal wire and an electrode;

[0010] A deposition layer is laid on one or more cantilever beams and the surface of the film, a measuring resistor, a metal wire and an electrode are all arranged on the deposition layer, and the measuring resistor is connected to the electrode through the metal wire.

[0011] Preferably, the deposited layer material is titanium or platinum.

[0012] The beneficial effects of the present invention are:

[0013] The present invention sets the cantilever beam on the silicon wafer, which is completely consistent with the processing technology of the silicon wafer and is completed synchronously, that is, microstructures, that is, patterns, are processed on the surfaces of both, the bending characteristics of the cantilever beam are monitored, and stress monitoring is realized.

[0014] The length and width of the cantilever beam of the present invention can be customized for easy observation. The cantilever beam will bend under the influence of stress, and the degree of bending can be measured non-destructively using non-contact techniques such as 3D confocal microscopy. The stress direction and stress value can be calculated by the curvature radius of the cantilever beam, the thickness, length and width of the beam.

[0015] The cantilever beam of the present invention is arranged on the silicon chip and can monitor stress in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A structure in which a plurality of cantilever beams are arranged on a silicon wafer;

[0017] Figure 2 It is the cantilever beam structure diagram;

[0018] Figure 3 This is the processing diagram of silicon wafer. Figure 3 (a) is a process diagram for setting up the film, Figure 3 (b) is a process diagram for setting the deposition layer. Figure 3 (c) is the process diagram of removing part of the structure. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0022] Embodiment 1:

[0023] Combination Figure 1 and 2 This embodiment is described, a system for real-time monitoring of film stress on a silicon wafer, the system comprising a silicon wafer, a film and a microstructure, the film being deposited on the silicon wafer, the system comprising one or more cantilever beams, a 3D confocal microscope and a controller;

[0024] One or more cantilever beams are arranged on the film, and microstructures are arranged on the one or more cantilever beams and the film. The 3D confocal microscope is used to measure the bending characteristics of the one or more cantilever beams; and the controller is used to calculate the stress value of the corresponding cantilever beam as the stress value of the corresponding position of the film according to the bending characteristics of the one or more cantilever beams.

[0025] Further introduction to bending characteristics: The bending characteristics of a cantilever beam include the radius of curvature, thickness, length, and width.

[0026] Specifically, Figure 2 The design diagram of four groups of cantilever beams is shown in Figure 1. A1 and B1 are of the same size, A2 and B2 are of the same size, A3 and B3 are of the same size, and A4 and B4 are of the same size. The cantilever beam structure and the formal chip are on the same wafer, and the processing technology is completely consistent with that of the formal chip and is completed synchronously, which can realize in-situ monitoring of stress. One or more groups of cantilever beams can be designed according to actual needs.

[0027] It is further defined that the bending characteristics of the cantilever beam include a radius of curvature, a thickness, a length, and a width.

[0028] It is further defined that the silicon body is a single crystal silicon body.

[0029] It is further defined that the thin film material is prepared from two layers of materials, the two layers of materials are silicon oxide and silicon nitride, the silicon oxide is laid on the silicon body, and the silicon nitride is laid on the silicon oxide.

[0030] It is further defined that the microstructure includes a deposited layer, a measuring resistor, a metal wire, and an electrode;

[0031] A deposition layer is laid on one or more cantilever beams and the surface of the film, a measuring resistor, a metal wire and an electrode are all arranged on the deposition layer, and the measuring resistor is connected to the electrode through the metal wire.

[0032] It is further defined that the deposited layer material is titanium or platinum.

[0033] Specifically, combined Figure 3 Description of the process:

[0034] Step 1, after one or more cantilever beams are arranged on the front side of the single crystal silicon wafer, thermal oxidation of silicon oxide and low-pressure chemical vapor deposition of silicon nitride are sequentially performed on the front and back sides of the single crystal silicon wafer and the cantilever beams;

[0035] Step 2: depositing a titanium or platinum thin film on the silicon nitride surface on the front side of the single crystal silicon wafer by magnetron sputtering, and making a temperature measuring resistor and metal wiring by photolithography, etching, and annealing processes; depositing a gold thin film by thermal evaporation, and making lead electrodes by photolithography and etching processes;

[0036] Step 3: Remove the silicon oxide and silicon nitride on the release area and bonding area as well as the back of the single crystal silicon wafer by photolithography and etching processes; complete the release of the temperature measuring resistor by double-sided alignment photolithography and etching processes;

[0037] Step 4: Complete the bonding of the airflow channel and the single crystal silicon wafer frame through a wafer bonding process to achieve the assembly of the airflow channel and the temperature measuring resistor.

[0038] Specifically, the shape of the flow channel can be adjusted to a rectangular, arc-shaped or other streamlined shape according to the needs of the measurement pneumatic layout, and a curved channel can be set to improve the device's anti-pollution ability; the airflow channel is installed on the silicon wafer through wafer-level bonding technology, and can be arranged in an array as a measurement unit to improve measurement accuracy or increase redundancy.

[0039] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A system for real-time monitoring of film stress on a silicon wafer, the system comprising a silicon wafer, a film and a microstructure, wherein the film is deposited on the silicon wafer, and characterized in that: The system includes one or more cantilevers, a 3D confocal microscope, and a controller; One or more cantilever beams are disposed on the film, microstructures are disposed on the one or more cantilever beams and the film, and a 3D confocal microscope is used to measure bending characteristics of the one or more cantilever beams; The controller is used to calculate the stress value of the corresponding cantilever beam as the stress value of the corresponding position of the film according to the bending characteristics of one or more cantilever beams.

2. The system for real-time monitoring of film stress on a silicon wafer according to claim 1, characterized in that: The bending characteristics of a cantilever beam include radius of curvature, thickness, length, and width.

3. The system for real-time monitoring of film stress on a silicon wafer according to claim 1, characterized in that: The silicon body is a single crystal silicon body.

4. The system for real-time monitoring of film stress on a silicon wafer according to claim 1, characterized in that: The thin film material is prepared from two layers of materials, namely silicon oxide and silicon nitride. The silicon oxide is laid on the silicon body, and the silicon nitride is laid on the silicon oxide.

5. The system for real-time monitoring of film stress on a silicon wafer according to claim 1, characterized in that: The microstructure includes deposited layers, measuring resistors, metal wires, and electrodes; A deposition layer is laid on one or more cantilever beams and the surface of the film, a measuring resistor, a metal wire and an electrode are all arranged on the deposition layer, and the measuring resistor is connected to the electrode through the metal wire.

6. The system for real-time monitoring of film stress on a silicon wafer according to claim 5, characterized in that: The deposited layer material is titanium or platinum.

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