CN103954819A - Method for measuring surface dark currents of semiconductor infrared photoelectric detector near zero bias - Google Patents

Abstract

The invention discloses a kind of measurement method of semiconductor infrared photodetector surfaces dark current when nearly zero bias, this method is by measuring device surface dark current shared component ratios in total dark current in nearly zero bias To according to formula Obtain the size of surface dark current, wherein p is the perimeter of section of part table, S is the footprint of device, a is the slope of straight line, and b is the intercept of straight line, I be in the I-V characteristic of measured different scale devices level off to zero back bias voltage under the corresponding total dark current size of device.

Description

The measuring method of nearly zero photodetector surfaces of semiconductor infrared partially time dark current

Technical field

The present invention relates to the measuring method of a kind of nearly zero photodetector surfaces of semiconductor infrared partially time dark current, particularly a kind of method of the surperficial dark current of mesa structure pin type semiconductor infrared photodetector being measured by becoming the mode of device size.

Background technology

Dark current size is a very important index that is related to semiconductor infrared photoelectric detector performance.This is because dark current noise is very important source of semiconductor infrared photodetector noise, and the detectivity of detector is defined as the inverse of noise equivalent power (NEP).At present, the existing much research about infrared eye dark current mechanism, has played good impetus to the development of infrared eye in the world.The mechanism of dark current is comparatively complicated, is subject to the impact of several factors.On the whole, can be divided into body electric current and surface current two parts.Body electric current is subject to the impact of character, doping content, dislocation and the defect concentration of material itself, main relevant with the growth of material, can increase bulk resistor by inserting barrier layer, thereby reduce dark current.Surface current is main relevant with surperficial dangling bonds and interface state, can or apply bias voltage on surface by surface passivation and suppress.

At present, weigh the level of device passivation technology, can, by becoming the method for device size, make the change sized image of this group device.The transverse axis of this image is the girth Area Ratio of individual devices, the longitudinal axis is corresponding device zero inverse of dynamic resistance and device area product partially, different curve corresponding to passivation technology, pass through curve, compare different process slope of a curve and intercept, the fine or not degree of different passivation technologies can be judged, and the product of surface resistivity and body dynamic resistance and the footprint of device under different process can be calculated.But the method can not be calculated surface current percentage in the dark current of individual devices at present, thereby cannot measure surperficial dark current.If known in dark current surface current and body electric current shared ratio of component separately, when making device, can help judgement is that improving of device architecture is more important or the improvement of device technology is more important.And to accurately calculate the size of individual devices surface dark current, and need to consider the number of mechanisms that dark current forms, desired parameters is various, calculation of complex, calculated amount is large.

Summary of the invention

(1) technical matters that will solve

In view of this, fundamental purpose of the present invention is the measuring method that proposes a kind of nearly zero photodetector surfaces of semiconductor infrared partially time dark current, to measure more quickly and easily device surface dark current shared ratio of component in total dark current nearly zero partially time, thereby obtain the size of surperficial dark current

(2) technical scheme

For achieving the above object, the invention provides the measuring method of a kind of nearly zero photodetector surfaces of semiconductor infrared partially time dark current, the method comprises:

Step 1: adopt change size reticle to carry out photoetching to sample, form the devices of many group different sizes at sample surfaces;

Step 2: the samples that effects on surface forms many group different size devices carry out cleavage, obtains the chip A that comprises one group of different size device, and by chip A be bonded at copper heat sink on;

Step 3: a plurality of solder joints of surrounding's making at copper heat sink surface chip A, lead to the top electrode of the different size device of chip A on the solder joint of the heat sink upper correspondence of copper by ball bonding technique;

Step 4: get a plastic cover wrapper sheet, surrounding is made a plurality of solder joints on plastic cover wrapper sheet surface, adopts insulated conductor that the solder joint on plastic cover wrapper sheet is connected with source table, makes test fixture B;

Step 5: be bonded on plastic cover wrapper sheet copper is heat sink, and each solder joint on copper is heat sink by ball bonding technique leads on solder joint corresponding on bread board with microstrip line, make the measured device C that comprises chip A to be measured;

Step 6: measured device C is put into lighttight closed container, pour liquid nitrogen into, covered container lid;

Step 7: measure respectively the I-V characteristic of the upper different size device of chip A comprising in measured device C with source table, and calculate the zero inclined to one side dynamic resistance R corresponding to different size device ₀inverse with the product of part table area S

Step 8: make the change sized image of upper that group different size device of chip A, a point in the device corresponding diagram of different size, horizontal ordinate is for to organize the p/S value of each scale device corresponding to this, and unit is cm ^-1, the perimeter of section that wherein p is part table, the footprint that S is device; Ordinate is described zero inverse of dynamic resistance and footprint product partially corresponding to variant scale device measuring unit is (Ω cm ²) ^-1, with after least-squares algorithm linear fitting, obtain slope a and the intercept b of straight line;

Step 9: obtain within the scope of the normal working temperature of device by described slope a and intercept b, applying bias is that while approaching zero negative bias, footprint is S, and the device surface dark current that perimeter of section is p accounts for the ratio of total dark current in conjunction with the device I-V properties recording, can calculate at nearly zero inclined to one side negative bias lower surface dark current and be

(3) beneficial effect

From technique scheme, can find out, the present invention has following beneficial effect:

1, utilize the measuring method of provided by the invention nearly zero photodetector surfaces of semiconductor infrared partially time dark current, because the formula adopting is simple, so realize easy, and easy operating.

The measuring method of semiconductor infrared photodetector surfaces dark current while 2, utilizing the present invention provided by the invention nearly zero partially, owing to need not considering that surperficial dark current forms mechanism, so do not need additionally to consider that other are difficult to the parameter of measuring.

Accompanying drawing explanation

For further illustrating content of the present invention, once the present invention will be further described with concrete example by reference to the accompanying drawings, wherein:

Fig. 1 is the schematic diagram at the individual devices of sample surfaces formation;

Fig. 2 a adopts insulated conductor by the solder joint on plastic cover wrapper sheet and source show the to be connected schematic diagram of the test fixture B that makes;

Fig. 2 b puts into measured device C the schematic diagram of lighttight closed container;

Fig. 3 becomes sized image; Horizontal ordinate is the perimeter of section of part table and the ratio p/S of footprint; Ordinate is the inverse of the inclined to one side dynamic resistance of device zero and footprint product

Embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

Consult shown in Fig. 1 to Fig. 3, the measuring method of provided by the invention nearly zero photodetector surfaces of semiconductor infrared partially time dark current, comprises that step is as follows:

Step 1: adopt change size reticle to carry out photoetching to sample, form the devices of many group different sizes at sample surfaces; The device of general 5-10 different size is one group, Figure 1 shows that the schematic diagram of the individual devices forming at sample surfaces; This sample comprise successively from bottom to up substrate, P layer, I layer and and N layer, wherein substrate adopts insulation or SI-substrate, P layer is for making the bottom electrode of the device of different size, and I layer is for making the device light absorbing zone of different size, and N layer is for making the top electrode of the device of different size;

In order to reduce the number of electrodes of drawing, the device of every group of different size shares same bottom electrode, but top electrode is independent of one another; In becoming size reticle, the figure of the device of every group of different size should be as far as possible compact under the prerequisite that keeps photoetching figure design rule, the impact that may produce device performance to eliminate as far as possible specimen material unevenness;

Step 2: the samples that effects on surface forms many group different size devices carry out cleavage, obtain the chip A that comprises one group of different size device, and it is heat sink upper that chip A is bonded to copper, and the surface area that copper is heat sink is greater than the surface area of chip A;

Step 3: a plurality of solder joints of surrounding's making at copper heat sink surface chip A, lead to the top electrode of the different size device of chip A on the solder joint of the heat sink upper correspondence of copper by ball bonding technique; Between solder joint and copper are heat sink, have the dielectric substrate for insulating, this dielectric substrate can be the materials such as pottery, complex media or teflon, the thickness 200-600 μ m of dielectric substrate;

Step 4: get a plastic cover wrapper sheet, the surface area of plastic cover wrapper sheet is greater than the heat sink surface area of copper, and on plastic cover wrapper sheet surface, surrounding is made a plurality of solder joints, adopts insulated conductor that the solder joint on plastic cover wrapper sheet is connected with source table, make test fixture B, as shown in Figure 2 a; Source table, for measuring the I-V characteristic of different size device, is measured stepping and should be less than 0.1mV, and source table can adopt Catherine's 2400 source tables;

Step 5: be bonded on plastic cover wrapper sheet copper is heat sink, and each solder joint on copper is heat sink by ball bonding technique leads on solder joint corresponding on bread board with microstrip line, make the measured device C that comprises chip A to be measured, as shown in Figure 2 b; The material of microstrip line can be Au, Al or Cu, and width is 2-3mm;

Step 6: measured device C is put into lighttight closed container, pour liquid nitrogen into, covered container lid, as shown in Figure 2 b;

Due to what measure, be the dark current characteristic of device, described container must be airtight light tight, and in order to extend the test duration, should select the container that heat-proof quality is good, prevents that liquid nitrogen from gasifying too early;

Step 7: measure respectively the I-V characteristic of the upper different size device of chip A comprising in measured device C with source table, and calculate the zero inclined to one side dynamic resistance R corresponding to different size device ₀inverse with the product of part table area S

During measurement, between can be chosen in-0.3V～0.3V of bias voltage scope, in order guaranteeing in the accuracy of calculating, to measure stepping and should be less than 0.1mV;

Step 8: make the change sized image of upper that group different size device of chip A, a point in the device corresponding diagram of different size, in order to organize the p/S value of each scale device corresponding to this, (unit is cm to horizontal ordinate ^-1), the perimeter of section that wherein p is part table, the footprint that S is device; Ordinate is described zero inverse of dynamic resistance and footprint product partially corresponding to variant scale device measuring (unit is (Ω cm ²) ^-1), with after least-squares algorithm linear fitting, obtain slope a and the intercept b (as Fig. 3) of straight line;

Step 9: obtain within the scope of the normal working temperature of device by described slope a and intercept b, applying bias is while approaching zero negative bias, footprint is S, perimeter of section is the ratio that the device surface dark current of p accounts for total dark current, in conjunction with the device I-V properties recording, can calculate the size at nearly zero inclined to one side negative bias lower surface dark current;

Due to

$\frac{1}{R_{o}S}\≡\frac{\mathrm{dI}}{\mathrm{Sdv}},---\left(1\right)$

$\frac{1}{R_{\mathrm{bulk}}S}\≡\frac{{\mathrm{dI}}_{\mathrm{bulk}}}{\mathrm{SdV}},---\left(2\right)$

Semiconductor photo detector is generally operational under zero inclined to one side or minimum negative bias, when | V| levels off to zero time,

$\frac{1}{R_{o}S}\≡\frac{\mathrm{dI}}{\mathrm{SdV}}=\frac{I}{\mathrm{SV}},---\left(3\right)$

$\frac{1}{R_{\mathrm{bulk}}S}\≡\frac{d{I}_{\mathrm{bulk}}}{\mathrm{SdV}}=\frac{I_{\mathrm{bulk}}}{\mathrm{SV}},---\left(4\right)$

From upper two formulas,

$\frac{1}{R_{\mathrm{bulk}}S}:\frac{1}{R_{o}S}=I_{\mathrm{bulk}}:I,---\left(5\right)$

Again because

I＝I _bulk+I _surface， (6)

Convolution (1), (2) and can obtain:

$\frac{1}{r_{\mathrm{surface}}}\·\frac{P}{S}:\frac{1}{R_{o}S}=I_{\mathrm{surface}}:I---\left(7\right)$

Convolution (5), (7) can obtain:

$I_{\mathrm{bulk}}:I_{\mathrm{surface}}=\frac{1}{R_{\mathrm{bulk}}S}:(\frac{1}{r_{\mathrm{surface}}}\·\frac{P}{S})=b:(a\·\frac{P}{S})$

Thereby can calculate, in the normal operating temperature range of device, under nearly zero inclined to one side negative bias, the computing formula that device surface dark current accounts for the ratio of total dark current is

Measured again the dark current I-V characteristic of each device, thereby for the device of a certain size, under nearly zero inclined to one side negative bias, the computing formula of device surface dark current is i is leveling off to the total dark current size of corresponding device under zero negative bias in the I-V characteristic of measured different size device.

Above-described specific embodiment; object of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (9)

1. a measuring method for nearly zero photodetector surfaces of semiconductor infrared partially time dark current, is characterized in that, the method comprises:

Step 1: adopt change size reticle to carry out photoetching to sample, form the devices of many group different sizes at sample surfaces;

Step 2: the samples that effects on surface forms many group different size devices carry out cleavage, obtains the chip A that comprises one group of different size device, and by chip A be bonded at copper heat sink on;

Step 3: a plurality of solder joints of surrounding's making at copper heat sink surface chip A, lead to the top electrode of the different size device of chip A on the solder joint of the heat sink upper correspondence of copper by ball bonding technique;

Step 4: get a plastic cover wrapper sheet, surrounding is made a plurality of solder joints on plastic cover wrapper sheet surface, adopts insulated conductor that the solder joint on plastic cover wrapper sheet is connected with source table, makes test fixture B;

Step 5: be bonded on plastic cover wrapper sheet copper is heat sink, and each solder joint on copper is heat sink by ball bonding technique leads on solder joint corresponding on bread board with microstrip line, make the measured device C that comprises chip A to be measured;

Step 6: measured device C is put into lighttight closed container, pour liquid nitrogen into, covered container lid;

Step 7: measure respectively the I-V characteristic of the upper different size device of chip A comprising in measured device C with source table, and calculate the zero inclined to one side dynamic resistance R corresponding to different size device ₀inverse with the product of part table area S

Step 8: make the change sized image of upper that group different size device of chip A, a point in the device corresponding diagram of different size, horizontal ordinate is for to organize the p/S value of each scale device corresponding to this, and unit is cm ^-1, the perimeter of section that wherein p is part table, the footprint that S is device; Ordinate is described zero inverse of dynamic resistance and footprint product partially corresponding to variant scale device measuring unit is (Ω cm ²) ^-1, with after least-squares algorithm linear fitting, obtain slope a and the intercept b of straight line;

Step 9: obtain within the scope of the normal working temperature of device by described slope a and intercept b, applying bias is that while approaching zero negative bias, footprint is S, and the device surface dark current that perimeter of section is p accounts for the ratio of total dark current in conjunction with the device I-V properties recording, can calculate at nearly zero inclined to one side negative bias lower surface dark current and be

2. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, it is characterized in that, sample described in step 1 comprise successively from bottom to up substrate, P layer, I layer and and N layer, wherein substrate adopts insulation or SI-substrate, P layer is for making the bottom electrode of the device of different size, I layer is for making the device light absorbing zone of different size, and N layer is for making the top electrode of the device of different size.

3. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, is characterized in that, the surface area that copper described in step 2 is heat sink is greater than the surface area of chip A.

4. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, it is characterized in that, between solder joint described in step 3 and copper are heat sink, there is the dielectric substrate for insulating, this dielectric substrate is pottery, complex media or polytetrafluoroethylmaterial material, the thickness 200-600 μ m of dielectric substrate.

5. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, it is characterized in that, the surface area of the wrapper sheet of plastic cover described in step 4 is greater than the heat sink surface area of copper, described source table, for measuring the I-V characteristic of different size device, adopts Catherine's 2400 source tables.

6. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, is characterized in that, the material that microstrip line described in step 5 adopts is Au, Al or Cu, and width is 2-3mm.

7. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, it is characterized in that, container described in step 6 is airtight light tight, in order to extend the test duration, should select the container that heat-proof quality is good, prevent that liquid nitrogen from gasifying too early.

8. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, is characterized in that, while measuring described in step 7, between be chosen in-0.3V～0.3V of bias voltage scope, measures stepping and should be less than 0.1mV.

9. the measuring method of according to claim 1 nearly zero photodetector surfaces of semiconductor infrared partially time dark current, is characterized in that, described in step 9, at nearly zero inclined to one side negative bias lower surface dark current, is in, I is leveling off to the total dark current size of corresponding device under zero negative bias in the I-V characteristic of measured different size device.