Soft breakdown circuit structure and method for measuring silicon wafer to be measured by four-probe measuring instrument

Abstract

The invention provides a soft breakdown circuit structure and a method for measuring a silicon wafer to be measured by a four-probe measuring instrument, the soft breakdown circuit structure comprises a capacitor, one end of the capacitor is grounded, and the other end of the capacitor is connected with a charging circuit and a discharging circuit; the charging circuit is used for charging the capacitor; the charging circuit comprises a plurality of charging branches which are connected in parallel, and each charging branch comprises a first switch for controlling the current branch to be connected or disconnected; the electric energy provided by each charging branch is different; the discharging circuit is used for discharging the capacitor; the discharging circuit comprises four discharging branches which are connected in parallel, each discharging branch is connected to one probe of the four-probe measuring instrument, and each discharging branch comprises a second switch which controls the current branch to be connected or disconnected. According to the invention, the capacitor is used for discharging, soft breakdown is carried out on the silicon wafer, and good ohmic contact can be formed between the probe and the surface of the tested silicon wafer.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor detection, and in particular to a soft breakdown circuit structure and a method for measuring a silicon wafer to be tested by a four-probe measuring instrument. Background Art

[0002] The four-probe measuring instrument is a special instrument for measuring the resistivity and sheet resistance of semiconductor materials. It is used to measure the resistivity of rod-shaped and block-shaped semiconductor materials (including thick and thin slices) and the sheet resistance of the diffusion layer, ion implantation layer, and epitaxial layer on the silicon wafer. The instrument has the characteristics of high measurement accuracy, high sensitivity, good stability, wide measurement range, compact structure, and the measurement results are directly displayed in digital form, which is easy to use.

[0003] In many new processes, the surface state of silicon wafers is very complex. When using four-probe measurements, the probes and silicon wafers often cannot form good ohmic contact, resulting in unstable measurements.

[0004] Therefore, how to make the probe and the surface of the silicon wafer under test form a good ohmic contact is a problem that needs to be solved at present. Summary of the invention

[0005] The purpose of the present invention is to provide a soft breakdown circuit structure and a method for measuring a silicon wafer to be tested using a four-probe measuring instrument, which can form good ohmic contact between the probe and the surface of the silicon wafer to be tested and improve the stability of silicon wafer measurement.

[0006] In order to achieve the above object, the present invention provides a soft breakdown circuit structure connected to a four-probe measuring instrument, the circuit structure comprising:

[0007] A capacitor, one end of which is grounded, and the other end of which is connected to a charging circuit and a discharging circuit;

[0008] The charging circuit is used to charge the capacitor; the charging circuit includes a plurality of charging branches connected in parallel, each of the charging branches includes a first switch that controls the connection or disconnection of the current branch; the electric energy provided by each charging branch is different;

[0009] The discharge circuit is used to discharge the capacitor; the discharge circuit includes four discharge branches connected in parallel, each of which is connected to a probe of the four-probe measuring instrument, and each of which includes a second switch for controlling the connection or disconnection of the current branch.

[0010] In an optional solution, the charging circuit provides electrical energy through a voltage source or a current source.

[0011] In an optional solution, each of the charging branches includes a voltage source, a negative terminal of the voltage source is grounded, a positive terminal is connected to a resistor, the other end of the resistor is connected to the first switch, and the other end of the first switch is connected to the capacitor; the voltage sources of different charging branches provide different voltages.

[0012] In an optional solution, each of the charging branches includes a current source, a negative terminal of the current source is grounded, a positive terminal is connected to a first resistor, the other end of the first resistor is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents.

[0013] In an optional solution, the charging circuit includes:

[0014] transformer;

[0015] A plurality of voltage-dividing resistors connected in series, connected between the transformer and a reference ground;

[0016] A plurality of the charging branches are connected between different voltage-dividing resistors.

[0017] In an optional solution, the discharge circuit includes:

[0018] A control switch connected to the capacitor;

[0019] a resistor connected to the other end of the control switch;

[0020] The four parallel discharge branches are connected to the other end of the resistor.

[0021] The present invention also provides a method for measuring a silicon wafer to be tested using a four-probe measuring instrument, comprising:

[0022] Connecting the soft breakdown circuit structure to the four-probe measuring instrument;

[0023] Placing four probes of the four-probe measuring instrument on the silicon wafer to be tested;

[0024] According to the properties of the silicon wafer to be tested, one of the charging branches of the charging circuit is selected to charge the capacitor, and then one of the discharging branches is selected to discharge the capacitor;

[0025] Repeat the above steps until all four probes complete a capacitor discharge process;

[0026] Then the silicon wafer is measured by the four-probe measuring instrument.

[0027] The beneficial effects of the present invention are:

[0028] The present invention first charges the capacitor and then discharges the capacitor, and softly breaks down the silicon wafer through the probe, so that the probe and the surface of the silicon wafer to be measured can form good ohmic contact, thereby improving the stability of silicon wafer measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0030] Figure 1 A schematic diagram of a soft breakdown circuit structure in an embodiment of the present invention is shown.

[0031] Figure 2 A schematic diagram showing a soft breakdown circuit structure in another embodiment of the present invention is shown.

[0032] Figure 3 A schematic diagram showing a soft breakdown circuit structure in another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will become clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in a variety of different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0034] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0035] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0036] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0037] Example 1

[0038] This embodiment provides a soft breakdown circuit structure, including:

[0039] A capacitor, one end of which is grounded, and the other end of which is connected to a charging circuit and a discharging circuit;

[0040] The charging circuit is used to charge the capacitor; the charging circuit includes a plurality of charging branches connected in parallel, each of the charging branches includes a first switch that controls the connection or disconnection of the current branch; the electric energy provided by each charging branch is different;

[0041] The discharge circuit is used to discharge the capacitor; the discharge circuit includes four discharge branches connected in parallel, each of which is connected to a probe of the four-probe measuring instrument, and each of which includes a second switch for controlling the connection or disconnection of the current branch.

[0042] Specifically, refer to Figure 1The charging circuit is used to charge the capacitor C. The charging circuit includes a plurality of charging branches connected in parallel. Each of the charging branches includes a voltage source. The negative terminal of the voltage source is grounded, and the positive terminal is connected to a resistor R1. The other end of the resistor R1 is connected to the first switch (the first switches of the plurality of branches are S1, S2, S3, Sn respectively), and the other end of the first switch is connected to the capacitor C. The voltage sources of different charging branches provide different voltages. Figure 1 The voltages provided by the four voltage sources are 15V, 10V, 5V and 0.1V respectively. Multiple charging branches can be set to provide different voltages to adapt to more silicon wafers with different properties to be measured.

[0043] The discharge circuit includes four parallel discharge branches, each of which is connected to a probe of the four-probe measuring instrument, and each of which includes a second switch for controlling the connection or disconnection of the current branch (the second switches on the four discharge branches are SP1, SP2, SP3, and SP4, respectively). Specifically, in this embodiment, the discharge circuit includes: a control switch Son connected to the capacitor C; a resistor R connected to the other end of the control switch Son; and the four parallel discharge branches are connected to the other end of the resistor R.

[0044] There are many types of charging circuits, see Figure 2 , each charging branch includes a current source, the negative terminal of the current source is grounded, the positive terminal is connected to a first resistor, the other end of the first resistor R1 is connected to the first switch (the first switches of the four branches are S1, S2, S3, and Sn respectively), the other end of the first switch is connected to the capacitor C, and a second resistor R2 is also connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents (the currents provided by the four current sources are 100mA, 10mA, 1mA, and 0.01A respectively).

[0045] Reference Figure 3 The charging circuit includes: a transformer T; a plurality of voltage-dividing resistors connected in series, connected between the transformer T and a reference ground; and a plurality of charging branches connected between different voltage-dividing resistors. The voltage can be boosted to a set voltage value (such as 100V) by the transformer T, and then divided by the voltage-dividing resistors connected in series, so that each charging branch has a different voltage value.

[0046] According to the properties of the wafer to be tested, this embodiment selects a charging branch with suitable energy to charge the capacitor, and then discharges the capacitor. The silicon wafer is soft-punctured by the probe, so that the probe and the surface of the silicon wafer to be tested can form a good ohmic contact, thereby improving the stability of the silicon wafer measurement. The energy for charging the capacitor is 1 / 2CU 2, soft breakdown of the silicon wafer by capacitor discharge will not cause harm to the silicon wafer. If power is directly applied, it may cause harm to the silicon wafer. There can be many forms of capacitor charging circuits and discharge circuits, as long as they can charge and discharge the capacitor.

[0047] Example 2

[0048] This embodiment provides a method for measuring a silicon wafer to be tested using a four-probe measuring instrument, comprising:

[0049] The soft breakdown circuit structure in Example 1 is connected to a four-probe measuring instrument;

[0050] Place four probes of a four-probe measuring instrument on the silicon wafer to be tested;

[0051] According to the properties of the silicon wafer to be tested, one of the charging branches of the charging circuit is selected to charge the capacitor, and then one of the discharging branches is selected to discharge the capacitor;

[0052] Repeat the above steps until all four probes complete a capacitor discharge process;

[0053] Then the silicon wafer is measured by the four-probe measuring instrument.

[0054] Normally, when measuring a silicon wafer, the same charging branch can be used for four charging processes. Multiple charging branches are used to adapt to different silicon wafers.

[0055] In this embodiment, before measuring the silicon wafer, the silicon wafer is first soft-punctured so that a good ohmic contact is formed between the probe and the surface of the silicon wafer to be measured, thereby improving the stability of the silicon wafer measurement.

[0056] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A soft breakdown circuit structure connected to a four-probe measuring instrument, characterized in that: The circuit structure comprises: A capacitor, one end of which is grounded, and the other end of which is connected to a charging circuit and a discharging circuit; The charging circuit is used to charge the capacitor; the charging circuit includes a plurality of charging branches connected in parallel, each of the charging branches includes a first switch that controls the connection or disconnection of the current branch; the electric energy provided by each charging branch is different; The discharge circuit is used to discharge the capacitor; the discharge circuit includes four discharge branches connected in parallel, each of which is connected to a probe of the four-probe measuring instrument, and each of which includes a second switch for controlling the connection or disconnection of the current branch.

2. The soft breakdown circuit structure according to claim 1, characterized in that: The charging circuit provides electrical energy via a voltage source or a current source.

3. The soft breakdown circuit structure according to claim 1, characterized in that: Each of the charging branches includes a voltage source, a negative terminal of the voltage source is grounded, a positive terminal is connected to a resistor, the other end of the resistor is connected to the first switch, and the other end of the first switch is connected to the capacitor; the voltage sources of different charging branches provide different voltages.

4. The soft breakdown circuit structure according to claim 1, characterized in that: Each of the charging branches includes a current source, a negative terminal of the current source is grounded, a positive terminal is connected to a first resistor, the other end of the first resistor is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents.

5. The soft breakdown circuit structure according to claim 1, characterized in that: The charging circuit comprises: transformer; A plurality of voltage-dividing resistors connected in series, connected between the transformer and a reference ground; A plurality of the charging branches are connected between different voltage-dividing resistors.

6. The soft breakdown circuit structure according to claim 1, characterized in that: The discharge circuit comprises: A control switch connected to the capacitor; a resistor connected to the other end of the control switch; The four parallel discharge branches are connected to the other end of the resistor.

7. A method for measuring a silicon wafer to be tested using a four-probe measuring instrument, characterized in that: include: Connecting the soft breakdown circuit structure according to any one of claims 1 to 6 to the four-probe measuring instrument; Placing four probes of the four-probe measuring instrument on the silicon wafer to be tested; According to the properties of the silicon wafer to be tested, one of the charging branches of the charging circuit is selected to charge the capacitor, and then one of the discharging branches is selected to discharge the capacitor; Repeat the above steps until all four probes complete a capacitor discharge process; Then the silicon wafer is measured by the four-probe measuring instrument.

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