CN102565600A - Method for determining and testing ohmic contact between black silicon material and metal electrode - Google Patents

Abstract

The invention discloses a method for determining and testing ohmic contact between a black silicon material and a metal electrode, belonging to the technical field of semiconductor photoelectronic materials and devices. The invention has the technical schemes that: an I-V characteristic curve of a metal/black silicon material can be directly tested through a three-electrode horizontal test device with a reverse bias voltage, and the contact type between the black silicon material and the metal electrode can be judged; and 2, the ohmic contact of the black silicon material can be tested by using a TLM (Transmission Line Model) method with the reverse bias voltage, thus a specific contact resistance can be obtained. According to the method disclosed by the invention, the influence on the determination and the test for the ohmic contact of the black silicon material due to heterojunction structures of black silicon/monocrystalline silicon in the traditional metal/black silicon/monocrystalline silicon sandwich structure is solved, and the specific contact resistance value of the metal/black silicon can be accurately tested.

Description

The judgement of Ohmic contact and method of testing between black silicon material and the metal electrode

Technical field

The invention belongs to Semiconductor Optoeletronic Materials and device technology field, particularly the judgement of Ohmic contact and method of testing between black silicon material and the metal electrode.

Background technology

Black silicon is that the Mazur of Harvard University teaches a kind of silicon materials that obtain when seminar utilizes femtosecond laser under certain gaseous environment, to shine monocrystalline silicon sheet surface.The black silicon material surface of gained comprises the cone structure of the micron dimension of quasi-regular arrangement, and has the atom doped layer of high concentration sulfur family (chalcogen).The experiment proof; Black silicon material almost all absorbs the light of 250～2500nm wavelength, and it is extremely responsive to incident light simultaneously, compares with the photodetector of making based on traditional silicon wafer; Black silicon wafer can promote 100～500 times to the susceptibility of light, and near infrared light is had good response.These advantages make black silicon material have important use in fields such as silicon photodetector and solar cells and are worth.

In semiconductor science, no matter be to semiconductor physics with to the research of material property, or the manufacturing of semiconductor devices, contacting with semiconductor always need metal, this is absolutely necessary.Metal contacts with semiconductor can be divided into two types: one type is the rectification contact, and this type contact forward and reverse " current-voltage " are nonlinear relationship; Another kind of is the Ohmic contact that linearity " current-voltage " characteristic is all arranged on positive and negative both direction.Because bad electrically contacting can cause big schottky barrier height; Produce very big contact resistance; Make that " current-voltage " characteristic of semiconductor devices is not to be confirmed by the resistance of semiconductor material itself, but confirm by the contact type of semiconductor material and metal electrode.Usually semiconductor devices be used for the sample of measuring semiconductor parameter and all require to be connected with Ohmic contact.The quality of Ohmic contact quality, the size of contact resistance directly have influence on the performance index such as efficient, gain and switching speed of device.

A very important parameter weighing the Ohmic contact quality is exactly specific contact resistivity ρ _cIt is crucial reference frame during device is used; Transmission line model method (TLM method);, convenient test theoretical ripe with it and can obtain specific contact resistivity and semi-conductive advantage such as resistance of metal-semiconductor contact more accurately becomes the method for testing that generally adopts at present, and be as shown in Figure 1.At first, the different strip electrode (as 1,2,3,4,5) of preparation spacing on film 8 to be measured, the length of each electrode is L, wide is W.Then, respectively at two different spacing d _nStrip electrode between galvanization or voltage, and try to achieve all-in resistance R _m, this can be expressed from the next:

$R_m=R_s+2R_C=\frac{{\mathrm{\ρ}}_s{d}_n}{W}+2R_C---\left(1\right)$

R wherein _sBe the resistance of the semiconductor material between two electrodes, R _CBe contact resistance, and R _CCan be expressed as

$R_c=\left({\mathrm{\ρ}}_s\frac{L_T}{W}\right)\coth \left(\frac{L}{L_T}\right)---\left(2\right)$

Therefore, R _mFor

$R_m=\frac{{\mathrm{\ρ}}_s{d}_n}{W}+\left(2{\mathrm{\ρ}}_s\frac{L_T}{W}\right)\coth \left(\frac{L}{L_T}\right)---\left(3\right)$

ρ wherein _sBe side's resistance of semiconductor film material, L _TBe called transmission length, as L>=1.5L _TThe time, coth (L/L _T) level off to 1, so

$R_m=\frac{{\mathrm{\ρ}}_s{d}_n}{W}+2R_C\≈\frac{{\mathrm{\ρ}}_s}{W}(d+2L_T)---\left(4\right)$

This is all-in resistance R _mGap length d with potential electrode _nThe straight-line equation that changes, ρ _sCan obtain L from the slope of straight line _TCan try to achieve from the intercept of straight line, pass through relational expression again

${\mathrm{\&rho;}}_c={\mathrm{\&rho;}}_{\mathrm{<figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">s</figure-callout>}}{L}_T^{}{}_2^{}=R_c{\mathrm{WL}}_T---\left(5\right)$

Can obtain the specific contact resistivity ρ of sample thin film Ohmic contact _c

Yet; For contacting of black silicon material and metal; Because it has unique metal/black silicon/monocrystalline silicon sandwich structure, wherein has black silicon/monocrystalline silicon heterojunction, this makes and adopts the specific contact resistivity ρ between conventional transmission line model method test black silicon material and the metal electrode _cThe time have certain difficulty, even the contact type between black silicon material and the metal electrode is also difficult judges.

Summary of the invention

The present invention provides the judgement and the method for testing of Ohmic contact between a kind of black silicon material and the metal electrode, to solve the problem of the I-V characteristic that can't directly test metal/black silicon material that is caused owing to black heterogeneous the existing of silicon/monocrystalline silicon.Use this method effectively to judge, the Ohmic contact of black silicon material is accurately tested, calculate the specific contact resistivity of metal/black silicon more accurately the contact type between black silicon material and the metal electrode.

Technical scheme of the present invention is:

The judgement of Ohmic contact and method of testing between black silicon material and the metal electrode may further comprise the steps:

Step 1: square metal electrode 1～3 as shown in Figure 2, identical in three sizes of black silicon material 8 surface depositions, that spacing equates, simultaneously at the monocrystalline silicon that contacts with black silicon material 89 backside deposition metal pair electrodes 10;

Step 2: between two adjacent arbitrarily square metal electrodes of black silicon material 8 surfaces, apply a forward voltage bias U with semiconductor parametric tester 12 ₊Applying the reverse voltage U that setovers between the remaining square metal electrode in black silicon material 8 surface and the metal pair electrode 10 with variable voltage source simultaneously _-

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding two square metal electrodes in black silicon material 8 surfaces reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value; Note voltage, current value and the complete reversed bias voltage value of semiconductor parametric tester 12 this moment;

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3, promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction change forward voltage bias U described in step 2 ₊Size, and adjacent arbitrarily two the square metal electrodes in record black silicon material 8 surface are at different forward voltage bias U ₊Under current value;

Step 5: according to adjacent arbitrarily two the square metal electrodes in black silicon material 8 surfaces of step 4 record at different forward voltage bias U ₊Under current value; Obtain the I-V family curve of metal/black silicon and judge the contact type between black silicon material and the metal electrode according to this I-V family curve: if the I-V family curve of metal/black silicon is a straight line, then the contact type between black silicon material and the metal electrode is an Ohmic contact; If metal/and the I-V family curve of black silicon is a curve, then black silicon material is that rectification contacts with contact type between the metal electrode.

The black silicon material of Ohmic contact and the method for testing of the specific contact resistivity between the metal electrode may further comprise the steps:

Step 1: as shown in Figure 3, at six bullion electrodes 1～6 that size is identical, spacing increases successively of black silicon material 8 surface depositions, simultaneously at the monocrystalline silicon that contacts with black silicon material 89 backside deposition metal pair electrodes 10;

Step 2: applying the reverse voltage U that setovers between the first bar shaped metal electrode 1 on black silicon material 8 surface and the metal pair electrode 10 with variable voltage source _-Between two any adjacent bullion electrodes of black silicon material 8 surface remainders, apply a forward voltage bias U with semiconductor parametric tester 12 simultaneously ₊

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding remaining any two the bullion electrodes in black silicon material 8 surfaces reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value;

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3; Promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; Between the bullion electrode of remaining any two different spacing in black silicon material 8 surfaces, apply constant forward voltage bias with semiconductor parametric tester 12; And measure strength of current, thereby try to achieve the all-in resistance R between the electrode of different interval _m

Step 5: make all-in resistance R _mWith different electric die opening d _nBetween the funtcional relationship straight line, according to the computing formula in the transmission line model method (4)

$R_m=\frac{{\mathrm{\&rho;}}_s{d}_n}{W}+2R_C\&ap;\frac{{\mathrm{\&rho;}}_s}{W}(d+2L_T)---\left(4\right)$

Can know ρ _sL can be tried to achieve by the slope of said funtcional relationship straight line _TCan try to achieve by the intercept of said funtcional relationship straight line, again through formula (5)

${\mathrm{\&rho;}}_c={\mathrm{\&rho;}}_s{\mathrm{<figure-callout\; id="2"\; label="L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">L</figure-callout>}}_T^{}=R_{c}W{L}_T---\left(5\right)$

Draw the black silicon material of Ohmic contact and the specific contact resistivity ρ between the metal electrode _c

The judgement of Ohmic contact and method of testing between black silicon material provided by the invention and the metal electrode; Guaranteeing under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; I-V family curve through test metal/black silicon material; Realized calculate the specific contact resistivity of metal/black silicon more accurately, and experimental technique being simple, easy to operate to effective judgement of the contact type between black silicon material and the metal electrode with to the accurate test of the Ohmic contact of black silicon material.

Description of drawings

Fig. 1 is to use the floor map of transmission line model method specimen.Among the figure the 1,2,3,4, the 5th, the strip electrode of different spacing, the 8th, testing sample film.

Fig. 2 is the cross-sectional view of three electrode transverse test devices of band reverse voltage biasing.1,2,3 is metal electrode among the figure, the 8th, and black silicon material, the 9th, monocrystalline silicon, the 10th, metal back electrode, the 11st, variable voltage source, the 12nd, semiconductor parametric tester.

Fig. 3 is the principle schematic of the black silicon sample of transmission line model method test of band reverse voltage biasing.Among the figure the 1,2,3,4,5, the 6th, the strip electrode of different spacing, the 8th, black silicon material, the 9th, monocrystalline silicon, the 10th, metal back electrode.

Embodiment

For making the object of the invention, technical scheme and advantage are clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, to further explain of the present invention.

The judgement of Ohmic contact and method of testing between black silicon material and the metal electrode may further comprise the steps:

Step 1: as shown in Figure 2, at three square Al/ Ni electrodes 1,2,3 of surface preparation of black silicon material 8, electrode size is 2.0mm * 2.0mm, and spacing is 2.0mm.At the backside deposition Al of crystalline silicon 9 electrode 10, electrode size is 10.0mm * 10.0mm.

Step 2:, at electrode 2, apply the forward voltage bias of a 2V between 3, and test the strength of current between two electrodes with semiconductor parametric tester 12.

Step 3: at electrode 1, apply reverse voltage bias with variable voltage source between 10, and increase magnitude of voltage gradually, can observe the increase along with reverse voltage, electrode 2, the electric current between 3 reduce gradually, and finally reach a stationary value.At this moment read electric current, magnitude of voltage in the semiconductor parametric tester.This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value, and electrode 2, the current value between 3 are the current value between metal/black silicon.

Step 4: guaranteeing under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; Use semiconductor parametric tester to measure scope, draw the I-V family curve of metal/black silicon and judge the contact type between black silicon material and the metal electrode according to this I-V family curve for the continuous forward voltage bias bottom electrode of-2～2V 2, the strength of current between 3.

The black silicon material of Ohmic contact and the method for testing of the specific contact resistivity between the metal electrode may further comprise the steps:

Step 1: as shown in Figure 3, prepare six bar shaped Al/ Ni electrodes 1,2,3,4,5,6 on the surface of black silicon material 8 according to the transmission line model pattern, electrode size is 0.5 * 1.5mm, its spacing is respectively: 0.2mm, 0.4mm, 0.8mm, 1.4mm and 2.0mm.At the backside deposition Al of monocrystalline silicon 9 electrode 10, electrode size is 4.0mm * 4.0mm.

Step 2: applying the reverse voltage U that setovers between the first bar shaped metal electrode 1 on black silicon material 8 surface and the metal pair electrode 10 with variable voltage source _-Between two any adjacent bullion electrodes of black silicon material 8 surface remainders, apply a forward voltage bias U with semiconductor parametric tester 12 simultaneously ₊

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding remaining any two the bullion electrodes in black silicon material 8 surfaces reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value;

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3; Promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; Use semiconductor parametric tester 12 between the bullion electrode of remaining any two different spacing in black silicon material 8 surfaces, to apply constant forward voltage bias as 1V; And measure strength of current, thereby try to achieve the all-in resistance R between the electrode of different interval _m

Step 5: make all-in resistance R _mWith different electric die opening d _nBetween the funtcional relationship straight line, according to the computing formula in the transmission line model method

$R_m=\frac{{\mathrm{\&rho;}}_s{d}_n}{W}+2R_C\&ap;\frac{{\mathrm{\&rho;}}_s}{W}(d+2L_T)$

Can know ρ _sL can be tried to achieve by the slope of said funtcional relationship straight line _TCan try to achieve by the intercept of said funtcional relationship straight line, pass through formula again

${\mathrm{\&rho;}}_c={\mathrm{\&rho;}}_s{\mathrm{<figure-callout\; id="2"\; label="L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">L</figure-callout>}}_T^{}=R_c{\mathrm{WL}}_T$

Draw the black silicon material of Ohmic contact and the specific contact resistivity ρ between the metal electrode _c

Below only be the exemplary embodiment in the numerous concrete ranges of application of the present invention, protection scope of the present invention is not constituted any limitation.All employing conversion or equivalence are replaced and the technical scheme of formation, all drop within the rights protection scope of the present invention.

Claims (2)

1. the judgement of Ohmic contact and method of testing between black silicon material and the metal electrode may further comprise the steps:

Step 1: the square metal electrode (1～3) identical in three sizes of black silicon material (8) surface deposition, that spacing equates, simultaneously at monocrystalline silicon (9) the backside deposition metal pair electrode (10) that contacts with black silicon material (8);

Step 2: between two adjacent arbitrarily square metal electrodes of black silicon material (8) surface, apply a forward voltage bias U with semiconductor parametric tester (12) ₊Use variable voltage source (11) between the remaining square metal electrode in black silicon material (8) surface and metal pair electrode (10), to apply the reverse voltage U that setovers simultaneously _-

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding two square metal electrodes in black silicon material (8) surface reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value; Note voltage, current value and the complete reversed bias voltage value of semiconductor parametric tester this moment (12);

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3, promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction change forward voltage bias U described in step 2 ₊Size, and arbitrarily adjacent two the square metal electrodes in record black silicon material (8) surface are at different forward voltage bias U ₊Under current value;

Step 5: according to adjacent arbitrarily two the square metal electrodes in black silicon material (8) surface of step 4 record at different forward voltage bias U ₊Under current value; Obtain the I-V family curve of metal/black silicon and judge the contact type between black silicon material and the metal electrode according to this I-V family curve: if the I-V family curve of metal/black silicon is a straight line, then the contact type between black silicon material and the metal electrode is an Ohmic contact; If metal/and the I-V family curve of black silicon is a curve, then black silicon material is that rectification contacts with contact type between the metal electrode.

2. the method for testing of the black silicon material of Ohmic contact and the specific contact resistivity between the metal electrode may further comprise the steps:

Step 1: at six of black silicon material (8) the surface depositions bullion electrode (1～6) that size is identical, spacing increases successively, simultaneously at monocrystalline silicon (9) the backside deposition metal pair electrode (10) that contacts with black silicon material (8);

Step 2: applying the reverse voltage U that setovers between the first bar shaped metal electrode (1) on black silicon material (8) surface and the metal pair electrode (10) with variable voltage source _-Use semiconductor parametric tester (12) between two any adjacent bullion electrodes of black silicon material (8) surface remainder, to apply a forward voltage bias U simultaneously ₊

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding remaining any two the bullion electrodes in black silicon material (8) surface reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value;

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3; Promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; Between the bullion electrode of remaining any two different spacing in black silicon material (8) surface, apply constant forward voltage bias with semiconductor parametric tester (12); And measure strength of current, thereby try to achieve the all-in resistance R between the electrode of different interval _m

Step 5: make all-in resistance R _mWith different electric die opening d _nBetween the funtcional relationship straight line, according to the computing formula in the transmission line model method

$R_m=\frac{{\mathrm{\&rho;}}_s{d}_n}{W}+2R_C\&ap;\frac{{\mathrm{\&rho;}}_s}{W}(d+2L_T)$

Can know ρ _sL can be tried to achieve by the slope of said funtcional relationship straight line _TCan try to achieve by the intercept of said funtcional relationship straight line, pass through formula again

${\mathrm{\&rho;}}_c={\mathrm{\&rho;}}_s{L}_T^2=R_c{\mathrm{WL}}_T$

Draw the black silicon material of Ohmic contact and the specific contact resistivity ρ between the metal electrode _c

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