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

Abstract

The present invention provides a soft breakdown circuit structure and a method for a four-probe measuring instrument to measure a silicon wafer to be measured. Among them, the soft breakdown circuit structure includes: a capacitor, one end of the capacitor is grounded, and the other end 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 parallel charging branches, and each charging branch includes a first switch for controlling the connection or disconnection of the current branch; the electric energy provided by each charging branch is different; the discharging circuit is used to discharge the capacitor; the discharging circuit includes four parallel discharging branches, each discharging branch is connected to a probe of the four-probe measuring instrument, and each discharging branch includes a second switch for controlling the connection or disconnection of the current branch. The present invention uses capacitor discharge to perform soft breakdown on the silicon wafer, which can form a good ohmic contact between the probe and the surface of the silicon wafer to be measured.

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 alternative embodiment, each of the charging branches includes a voltage source, the negative terminal of the voltage source is grounded, the 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 alternative embodiment, each of the charging branches 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 is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is also connected between the positive and negative terminals of the current source; the current sources of different charging branches provide different currents.

[0013] In an alternative embodiment, the charging circuit includes:

[0014] A transformer;

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

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

[0017] In an alternative embodiment, the discharging 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 discharging 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 measured by a four-probe measuring instrument, including:

[0022] Circuit-connecting the above-mentioned soft breakdown circuit structure to the four-probe measuring instrument;

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

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

[0025] Repeat the above steps until each of the four probes has completed a process of capacitor discharging;

[0026] After that, measure the silicon wafer through the four-probe measuring instrument.

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

[0028] The present invention first charges a capacitor and then discharges the capacitor. By using a probe to perform soft breakdown on a silicon wafer, a good ohmic contact can be formed between the probe and the surface of the silicon wafer to be measured, improving the stability of silicon wafer measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By describing the exemplary embodiments of the present invention in more detail with reference to the accompanying drawings, the above and other objects, features, and advantages of the present invention will become more apparent. In the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

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

[0031] Figure 2 FIG. shows a schematic diagram of the soft breakdown circuit structure in another embodiment of the present invention.

[0032] Figure 3 FIG. shows a schematic diagram of the soft breakdown circuit structure in another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in many different forms and is not limited to the specific embodiments described herein. The accompanying drawings are all in very simplified forms and use non-precise scales, only for the purpose of facilitating and clearly assisting 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" another element or layer, it can be directly on, adjacent to, connected to, or coupled to the other element or layer, or there can 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" another element or layer, there are 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 can be referred to as the second element, component, region, layer, or part.

[0035] Spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over", etc. may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures with other elements or features. It should be understood that, in addition to the orientation shown in the figures, spatial relationship terms are also intended to include different orientations of the device in use and operation. For example, if the device in the attached drawings is flipped, then an element or feature described as "under other elements" or "beneath them" or "under it" will be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "beneath" can include both upward and downward orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are to be interpreted accordingly.

[0036] The purpose of the terms used herein is only to describe specific embodiments and not to limit the present invention. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0037] Embodiment 1

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

[0039] A capacitor, one end of which is grounded and the other end 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 parallel charging branches, each charging branch contains a first switch for controlling the connection or disconnection of the current branch; the electrical energy provided by each charging branch is different;

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

[0042] Specifically, referring to Figure 1, the charging circuit is used to charge the capacitor C. The charging circuit includes multiple parallel charging branches. Each charging branch 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 multiple 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 in Figure 1 are 15V, 10V, 5V, and 0.1V respectively. Multiple charging branches can be set to provide different voltages to adapt to more silicon wafers to be measured with different properties.

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

[0044] The form of the charging circuit can be various. Refer to Figure 2 , each charging branch includes a current source. The negative terminal of the current source is grounded, and 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 four branches are S1, S2, S3, Sn respectively), and the other end of the first switch is connected to the capacitor C. 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] Refer to Figure 3 , the charging circuit includes: a transformer T; multiple series-connected voltage-dividing resistors connected between the transformer T and the reference ground; and multiple charging branches are connected between different voltage-dividing resistors. It can be boosted to a set voltage value (such as 100V) through the transformer T, and then voltage division is performed through the series-connected voltage-dividing resistors so that each charging branch has a different voltage value.

[0046] In this embodiment, according to the properties of the wafer to be measured, a charging branch with suitable energy is selected to charge the capacitor, and then the capacitor is discharged. The silicon wafer is soft-breakdown through the probe, which can form a good ohmic contact between the probe and the surface of the silicon wafer to be measured and improve the stability of silicon wafer measurement. The energy for charging the capacitor is 1 / 2CU 2, soft breakdown of the silicon wafer is performed by capacitor discharge, which will not cause harm to the silicon wafer. If power is directly applied, it may cause harm to the silicon wafer. The forms of the charging circuit and the discharging circuit of the capacitor can be various, as long as the capacitor can be charged and discharged.

[0047] Embodiment 2

[0048] This embodiment provides a method for measuring a silicon wafer to be measured by a four-probe measuring instrument, including:

[0049] Connect the soft breakdown circuit structure in Embodiment 1 to the four-probe measuring instrument for circuit connection;

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

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

[0052] Repeat the above steps until each of the four probes has completed a process of capacitor discharge;

[0053] After that, measure the silicon wafer through the four-probe measuring instrument.

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

[0055] Before measuring the silicon wafer in this embodiment, soft breakdown of the silicon wafer is first performed to form a good ohmic contact between the probe and the surface of the silicon wafer to be measured, improving the stability of silicon wafer measurement.

[0056] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention according to the above disclosure shall fall within the protection scope of the claims.

Claims

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

2. The soft breakdown circuit structure according to claim 1, wherein The charging circuit provides electric energy through a voltage source or a current source.

3. The soft breakdown circuit structure according to claim 1, wherein Each charging branch includes a voltage source, the negative terminal of the voltage source is grounded, the 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, wherein 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 is connected to the first switch, the other end of the first switch is connected to the capacitor, and a second resistor is also 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, wherein The charging circuit includes: A transformer; A plurality of series-connected voltage-dividing resistors connected between the transformer and the 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 discharging circuit includes: A control switch connected to the capacitor; A resistor connected to the other end of the control switch; The four parallel discharging branches are connected to the other end of the resistor.

7. A method for measuring a silicon wafer to be measured by a four-probe measuring instrument, characterized in that, Includes: Circuit-connect the soft breakdown circuit structure according to any one of claims 1-6 to the four-probe measuring instrument; Place the four probes of the four-probe measuring instrument on the silicon wafer to be measured; According to the properties of the silicon wafer to be measured, perform the following operations for each probe: select one of the charging branches of the charging circuit to charge the capacitor, and then select one of the discharging branches to discharge the capacitor; until all four probes have completed a process of charging and discharging the capacitor; Then measure the silicon wafer through the four-probe measuring instrument.

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