JPH0476055B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention measures and controls the movement and position of an object to be measured that emits light or particles by measuring the incident position of a light spot or a particle beam. Particles used as a detector for cases where the emitted light or particles are very weak, or when obtaining an integral image by accumulating the positions and frequencies of randomly incident particle beams. The present invention relates to a semiconductor incident position detection device for detecting the incident position of a line or the like.

(Prior Art) A conventional particle beam position detection device using a semiconductor will be described with reference to FIG.

2. Description of the Related Art As two-dimensional semiconductor position detecting devices, there are known semiconductor position detecting devices of a surface-split type and a double-side split type.

9a, b, and c are a perspective view, a sectional view, and a plan view, respectively, of a surface-divided type semiconductor position detection device.

As shown in each figure, a conventional surface-divided type semiconductor position detection device has a resistive layer 2 of the opposite conductivity type formed on one side of a semiconductor substrate 1 of a certain conductivity type.

The shape of the resistance layer 2 is square or rectangular,
An electrode 3 is formed along the side of the resistance layer 2 at a portion corresponding to a certain length of the side.

9d, e, and f are a perspective view, a sectional view, and a plan view, respectively, of a double-sided split type semiconductor position detection device.

Electrodes 3 are formed on a semiconductor substrate 1 along a pair of opposite sides of a square or rectangular resistance layer 2 having a conductivity type opposite to that of the substrate. A resistance layer 5 of the same conductivity type is formed.

An electrode 4 is formed on the back surface along the opposite side orthogonal to the electrode 3 on the front surface.

The position of the incident particle is expressed as the coordinate axes c and f in Figure 9.
It is specified by a coordinate system that passes through the center point of a square or rectangular resistance layer, parallel to the sides of the resistance layer, and sets the point where it intersects with the electrode as ±1.

In the surface-divided type semiconductor position detection device, electrodes 3, 3, 3, and 3 are grounded, and a voltage is applied to the electrodes so that the pn junction becomes reverse biased. Further, in the double-sided split type semiconductor position detection device, a bias is applied between the electrodes 3 and 3 so that the pn junction is reverse biased.

When a particle is incident on a point at arbitrary coordinates (x, y) on the resistance layer, excited carriers generated by internal effects are separated by a p-n junction, and in the surface split type, one of the carriers is connected to the resistance layer 2. electrode 3
flows into ~. The current of electrode 3 is I ₁ , 3
Let the current of 2 be I ₂ , the current of 3 be I ₃ , and the current of 3 be I ₄ X=(I ₃ − I ₁ )/(I ₃ +I ₁ ) Y=(I ₂ − _{I 4} )/ By calculating (I ₂ +I ₄ ), a position output corresponding to (x, y) can be obtained.

In a double-sided split type semiconductor position detection device, one of the carriers separated by the pn junction is separated by a resistance layer provided on the surface and flows into the electrode 3. The other part is divided by the resistance layer 5 on the back surface and flows to the electrode 4.

The _{position corresponding} to _{( x , y} ) is calculated _{by calculating} (operating) You can get the output.

The surface-split type and double-side split type semiconductor position detection devices each have advantages and disadvantages that the other does not have. FIG. 10 is a graph showing the position output characteristics of the semiconductor position detection device. Figure A shows the position output characteristics of a surface-split type device, and Figure B shows the position output characteristics of a double-sided split type device.

Both are 10mm inside the 13mm x 13mm resistance layer 2.
This is a graph of the aforementioned X and Y output characteristics obtained by moving a light spot instead of a particle beam at a constant pitch parallel to the X and Y axes within an area of 10 mm.

In the surface division type device shown in Fig. 10A, the light spot for measurement is moved at a constant pitch so as to form a grid, but the pitch of the output figure is not constant, but is centered around the periphery. is getting narrower.

On the other hand, the output characteristics of the double-sided split type device shown in FIG. 10B have a substantially constant pitch and have little distortion.

Although the double-sided split type device has excellent output characteristics as described above, it is difficult to getter the crystal defects in the substrate 1. Therefore, the junction leakage current is much larger than that of a surface-divided type device, and its value can reach 10 to 100 times that of a surface-divided type device.

Further, the noise characteristics of the position detection device are mainly determined by the sheet resistance of the resistance layer, and when the signal level is low, it is necessary to increase the sheet resistance to reduce noise.

However, the deterioration of characteristics caused by the incidence of particles becomes more pronounced as the sheet resistance increases.

Irradiation causes damage to the silicon substrate surface, especially if the incident particles are electrons or charged particles. If this damage occurs near the pn junction, it will cause a slight increase in dark current in a normal particle beam detection device, but it will not cause fatal deterioration.

However, in the case of a position detection device, the resistance value of the resistance layer changes due to thin impurity doping, and the dark current and conversion sensitivity deteriorates to a greater degree than in a normal particle beam detection device. Furthermore, when the protective film covering the resistive layer is removed in order to reduce the insensitive layer to the incidence of electrons and charged particles, the characteristics of the resistive layer with a low carrier concentration deteriorate even more due to surface contamination and surface parasitic charges. becomes.

To summarize the above, the surface split type position sensing device can reduce leakage current, but the position output error is large, and the double side split type position sensing device has a small position output error, but the leakage current is large, and both position sensing devices In both cases, the incidence of particles from the resistive layer side is accompanied by deterioration of characteristics, especially in the case of electrons and charged particles.

(Objective of the Invention) The object of the present invention is to have low leakage current, small distortion of position output, easy application of reverse bias, and change in position output characteristics by irradiation with particle beams (especially electrons or charged particles). An object of the present invention is to provide a semiconductor incident position detection device for detecting the incident position of a particle beam or the like with high sensitivity and without deterioration of sensitivity.

(Structure of the Invention) In order to achieve the above object, a semiconductor incident position detection device for detecting the incident position of a particle beam, etc. according to the present invention includes a semiconductor substrate having a first conductivity type, a semiconductor substrate having a first conductivity type, a semiconductor substrate having a second conductivity type, a particle beam, etc. A current generated by a particle beam or optical spot (hereinafter referred to as "particle beam, etc.") incident on the semiconductor substrate is divided into a plurality of electrodes provided around the resistive layer and output. A semiconductor position detection element configured to allow the incidence of a particle beam or the like to enter from the semiconductor substrate on the opposite side of the surface on which the resistive layer of the second conductivity type is formed, and the semiconductor substrate serving as the incident surface. A sufficiently thin and highly concentrated layer of the first conductivity type is formed on the surface of the resistor layer, and the shape of the resistor layer is formed by four arcuate resistance wires, each of which has a square or rectangular connection point. The sheet resistance r of the resistance layer and the linear resistivity Ri of the arc-shaped resistance wire are
The relationship between and the radius of curvature ai of the arc-shaped resistance wire is set as Ri=r/ai (i is an integer from 1 to 4).

The particle beam to be detected is an electron or a charged particle.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a plan view and a longitudinal sectional view showing an embodiment of a semiconductor incident position detection device for detecting the incident position of a particle beam or the like according to the present invention.

In this embodiment, the detection target is particularly the incident position of electrons and charged particles.

An n-type silicon wafer as the semiconductor substrate 11;
Use one with a specific resistance of 3kΩcm or more.

Both sides of this semiconductor substrate 11 are mirror polished.

This semiconductor substrate 11 is thermally oxidized to grow a thick layer of SiO ₂ on the entire surface, which will serve as a diffusion mask for the next boron.
Next, a hole with a width of 300 μm is formed in the SiO ₂ on one side of the semiconductor substrate 1 by photolithography along an arc with a radius of acm connecting the vertices of a square with a side length of 26 mm. .

Then, boron is introduced into this part by ion implantation and diffused by heat treatment, so that the resistance per unit length (1 cm) in the direction of the length of the arc part becomes R (Ω/cm) after the completion of the entire process. I adjusted it so that This linear arc portion will be referred to as a border resistance portion 13.

The semiconductor substrate 11 is oxidized again, and the border resistance part 1 is
Grow 5000 Å of SiO ₂ on top of 3.

Next, by photolithography, the border resistor part 1 is
SiO ₂ in the area surrounded by 3 and the entire surface on the opposite side where the border resistance part 13 is formed.
Remove _SiO2 .

At this time, the border resistance section 13 is also overlapped.
Try to remove _SiO2 . The width of the overlap is 50 μm.

This semiconductor substrate 11 is thermally oxidized to grow SiO ₂ of 1500 Å in the SiO ₂ removed portion.

Next, boron ions were implanted into the pattern side of the semiconductor substrate at an acceleration energy of 75 keV, and phosphorus ions were implanted into the entire surface on the opposite side from the pattern at 150 keV. After implantation, the substrate is annealed in a _N2 atmosphere.
Pattern surface after annealing (boron sulfur implanted surface)
The sheet resistance value r (Ω/□) is R after all processes are completed.
=r/a. Further, the sheet resistance value of the phosphorus ion implantation layer is 50 (Ω/□), and the thickness of the implantation layer is 3000 Å. 1500 on the phosphorus ion implantation layer side
The oxide film of Å was completely removed after annealing.

The boron ion implanted portion surrounded by the border resistance portion 13 will be referred to as a resistance layer portion 14, and the phosphorus ion implanted portion on the opposite side will be referred to as an n ⁺ portion 12.

At the apex portions of the four corners of the border resistance section 13, the diameter is
A 600 μm AL electrode 15 is formed concentrically, and n ⁺
Gold (Au) is mask-deposited around the portion 12,
It was alloyed with a semiconductor substrate to form an electrode on the back surface.

The semiconductor substrate is connected to a 5-pin ceramic case by die bonding and wire bonding.

The dimensions of the chip are 30 mm x 30 mm, the linear resistivity R of the border resistance part 13 is 8 kΩ/cm, the radius of curvature a of the arc part is 5 cm, and the sheet resistance of the resistive layer part is 40 kΩ/cm.
It is □.

FIG. 2 is a block diagram of an arithmetic circuit for position detection using the semiconductor position detection device manufactured through the above steps.

_C1 to _C4 are charge-voltage converters.

The potential of the inputs of C ₁ to _{C 4} is the ground potential, and charge signals converted by the incidence of particles flow into them, and signals V ₁ to _{V 4} converted to voltages are output, respectively.

_A1 to _A5 are adders. S ₁ and S ₂ are subtractors. The X and Y signals sent by the D ₁ and D ₂ dividers are X = [(V ₂ + V ₃ ) - (V ₁ + V ₄ )]
/(V ₁ +V ₂ +V ₃ +V ₄ ) Y=[(V ₁ +V ₂ )−(V ₃ +V ₄ )]
/(V ₁ +V ₂ +V ₃ +V ₄ ).

Instead of incident particles, a spot-like light pulse is applied to the n ⁺ area 12 on the element surface attached to the device.
Figure 3 shows the results of position calculations performed by moving while irradiating the central 20 mm x 20 mm area at a constant pitch.
As is clear from FIG. 3, the pitch of the position calculation output is almost constant and the distortion of the straight line is small.

It is clear that the position output characteristics are improved compared to conventional surface-divided position detection devices that have the same structure in the thickness direction of the substrate.

Next, the reason why the position output characteristics are improved by the present invention will be explained.

As shown in FIG. 4, assuming that a uniform resistance layer is formed between two parallel electrodes 61 and 62 extending to an infinite length, the X coordinate axis is taken as shown in the figure.

Electrode 61 and electrode 62 are grounded. If the current source I is connected to the point where X= _X1 , the relationship between the currents _I1 , _I2 , and _X1 flowing into the electrodes 61 and 62 is as follows: X=( _I2 − _I1 )/( _I2 + _I1 ) becomes.

Therefore, if we create an electrode in this state,
The linearity of the position should be the best and the position error should be zero.

By the way, as shown in FIG. 5, there is a hole with a radius of a (cm) in the uniform and infinitely wide resistance layer 72.
It is assumed that a wire resistance 71 is attached along the arc. Let the resistivity of the line resistance 71 be R (Ω/cm), and the sheet resistance of the resistance layer 73 be r (Ω/□).

Take the X-axis so that it passes through the center 0 of the circle, and take the angle θ from the -X-axis.

Assuming that a uniform current J is flowing in the X direction and is not disturbed by the circular hole, a current of Jasinθ flows into the line resistance between θ=0 and θ= _θ1 .

The potential drop caused by this current in the line resistance of θ = θ ₁ and θ = θ ₁ + dθ is the projection of dθ in the direction perpendicular to x as dx,
If the potential drop is dVx, then since dx=asinθ, dVx=Jasinθ・rdθ. When the potential drop on the wire resistor 71 and the potential drop on the resistance layer are equal, it means that the current is not disturbed, so Jasinθ·aR·dθ=Jasinθ·r·dθ ∴R=r/a.

Now, as shown in Fig. 6, there is a resistance layer 85 surrounded by arcs with radii _{a 12 ,} a ₂₃ , a ₃₄ , and a ₁₄ passing through the vertices of a rectangle with side lengths l 1 and l ₂ . Resistance line 7 of line resistance along which line resistivity is R ₁₂ , R ₂₃ , R ₃₄ , R ₁₄
Assume that 1, 72, 73, and 74 are attached.

Letting the sheet resistance of the resistance layer be r (Ω/□), R ₁₂ = r/a ₁₂ , R ₂₃ = r/a ₂₃ , R ₃₄ = r/a ₃₄ , and R ₁₄ = r/a ₁₄ .

Connect resistance wires 71 and 74 and ground them.
Connect 2 and 73 and ground.

Comparing this with FIG. 4, it is considered that FIG. 6 and FIG. 4 are equivalent from the relationship shown in FIG. 5.

In this way, by using the electrode structure as shown in FIG. 6, a position output without any position error can be obtained.

FIG. 7 is a perspective view showing the usage state of the device of the embodiment and a graph showing the impurity concentration distribution in the substrate.

The features of the semiconductor incident position detecting device for detecting the incident position of a particle beam or the like according to the present invention configured and used as described above will be listed below.

By using the electrode shape as described above, a position output with small position error can be obtained.

The semiconductor incident position detection device for detecting the incident position of a particle beam, etc. of the present invention is capable of gettering crystal defects in a semiconductor substrate by ion implantation and annealing of ^{the n} It is now on the same level as or even lower than the type of device.

In the surface-divided type device, the converted current due to particle beam incidence is used separately for X calculation and Y calculation as the information amount of the signal, whereas in the detection device of the present invention, the converted current for X calculation and Y calculation is used separately. Both are advantageous in terms of S/N because they are calculated using the entire converted current.

The semiconductor incident position detection device for detecting the incident position of particle beams, etc. of the present invention does not make the particles incident from the resistance layer side, so especially when the particles are electrons or charged particles, there is a resistance due to the incident. There is no change in sheet resistance of the layers or increase in junction dark current.

The semiconductor incident position detecting device for detecting the incident position of a particle beam, etc. of the present invention is different from a detection device in which particles are incident from the resistance layer ^side .
Since the impurity concentration is high and the n ⁺ part is formed sufficiently thin, it is possible to increase the accelerating electric field due to the impurity concentration gradient in the depth direction.

Therefore, carriers generated near the surface due to the incidence of electrons or charged particles can be quickly caused to travel inward from the semiconductor surface where many recombination centers exist.

Therefore, the sensitivity can be high, and the sensitivity is stable even if damage occurs due to the incidence of electrons or charged particles. It is also less susceptible to surface (particle incidence surface) contamination and surface parasitic charges.

In order to further explain the above effect, FIG.
The change in sensitivity of the detection device (curve S) with respect to the incidence of electrons with an energy of 3 keV is shown.

The figure also shows the results when SiO ₂ on the resistance layer is removed and the light is incident from the resistance layer side (curve J).

(Effects of the Invention) As explained above, the semiconductor incident position detection device according to the present invention allows the incidence of particle beams, etc. to be made from the semiconductor substrate on the opposite side to the side where the resistive layer of the second conductivity type is formed. It is set as. A sufficiently thin and highly concentrated layer of the first conductivity type is formed on the surface of the semiconductor substrate serving as the incident surface.

Therefore, leakage current is small, distortion of position output is small, reverse bias can be easily applied, there is no change in position output characteristics or deterioration of sensitivity due to irradiation with particle beams (especially electrons or charged particles), and high sensitivity. It is possible to detect the incident position of particle beams, etc.

[Brief explanation of drawings]

FIG. 1 is a plan view and a longitudinal sectional view showing an embodiment of a semiconductor incident position detection device for detecting the incident position of a particle beam or the like according to the present invention. FIG. 2 is a block diagram of an arithmetic circuit for position detection using the semiconductor position detection device. FIG. 3 is a graph showing the position output characteristics of the semiconductor position detection device according to the present invention. FIG. 4, FIG. 5, and FIG. 6 are diagrams showing models for explaining a configuration for preventing the occurrence of position detection errors in a semiconductor position detection device. FIG. 7 is a perspective view showing the usage state of the device of the embodiment, and a graph showing the impurity concentration distribution in the substrate. FIG. 8 is a graph showing the results of a life test of the semiconductor incident position detection device for detecting the incident position of a particle beam or the like according to the present invention. FIG. 9 is a diagram showing a conventional semiconductor position detection device, and FIG. , e, and f are a perspective view, a sectional view, and a plan view, respectively, of a double-sided split type semiconductor position detection device. FIG. 10 is a graph showing the position output characteristics of the conventional semiconductor position detection device, in which FIG. 10A shows the position output characteristics of the surface split type semiconductor position detection device, and FIG. It shows. 11...Semiconductor substrate, 12...n ⁺ part, 13...
...Border resistance section, 14...Resistance layer section, C ₁ to _{C 4} ...
...Charge-voltage converter, _A1 to _A5 ...Adder, _S1 ,
S ₂ ...subtractor, D ₁ , D ₂ ...divider.

Claims (1)

[Claims] 1. A resistive layer of a second conductivity type is formed on a semiconductor substrate of a first conductivity type, and a particle beam or light spot (hereinafter referred to as "particle beam, etc.") incident on the semiconductor substrate is formed.
A semiconductor position detection element in which a current generated by the resistive layer is divided into a plurality of electrodes provided around the resistive layer and outputted, the resistive layer having a second conductivity type being A sufficiently thin and highly concentrated layer of the first conductivity type is formed on the surface of the semiconductor substrate serving as the incident surface, and the shape of the resistive layer is surrounds the resistance layer with four arc-shaped resistance wires such that the connection points of the resistance wires are located at each corner of a square or rectangle, so that current is taken out from the connection points of the resistance wires, and the resistance layer The sheet resistance value r and the linear resistivity Ri of the arc-shaped resistance wire
A semiconductor incident position detection device for detecting the incident position of a particle beam, etc., configured such that the relationship between the radius of curvature ai of the arc-shaped resistance wire and the radius of curvature ai is Ri=r/ai (i is an integer from 1 to 4). 2. A semiconductor incident position detection device for detecting an incident position of a particle beam or the like according to claim 1, wherein the particle beam to be detected is an electron or a charged particle.