DE2341179C3 - Method of making a two-phase charge transfer device and the use of materials in this method - Google Patents

Description

Charge transfer devices of this type are bebereiche leads, known in an oblique direction to the substrate For example, in the German disclosure - * --- "<■■ '- - ₅ supply magazine 22 01395 a Ladungsverschiebeanord

voltage described, takes place in a doping of edge regions below the electrodes inclined by a z _ur surface ion beam and in which the regions below the column to improve the Poten'ialverlaufs perpendicularly through a beam of ions are doped to the substrate surface. Such an arrangement of a charge transfer element with electrodes in one plane (one-gate technique) has the advantage that

-— _β _ .. "." .. *. ν— / _<u ... ν, www ww. a two-phase operation and an almost loss-free one

Substrate surface, so that due to the thickness of the 25 charge transfer are possible. In the case of such an ^electric pden (3) and, if applicable, a charge shifting arrangement loaded on it, the length becomes one

Shift stage determined by the length of two gate electrodes and two gap areas.

_r , In the publication IEEE Journal of Solid-State

Electrodes (3, 31) on the first level and on that in 30 Circuits, Vol. SC-6, 1971, No. 5, pp. 314 to 322 are twos Columns of exposed electrically insulating phase charge transfer devices are described

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1. A method for producing a two-phase charge transfer arrangement with a substrate made of semiconductor material and an electrically insulating layer thereon, on which electrodes of the first level are provided, separated by gaps, in which edge areas below the edge of the electrodes and partial areas are provided in the semiconductor material by two ion implantations are doped below the column, one ion implantation, Öie leading to the doping of the edge areas, taking place in an oblique direction to the substrate surface, characterized in that the other ion implantation (6), which leads to the doping of the subregions (13) , takes place in an oblique direction to the substrate surface that the angle (7) between the direction (5) of the one ion implantation, which leads to the doping of the edge areas (12), and the substrate surface is set smaller than the angle (8) between the direction ( 6) the other ion implantation necessary for doping the subregions (13) leads, and the substrate surface, so that due to the thickness of the electrodes (3) and possibly a photosensitive layer (4) located thereon, a shadowing is effected, which allows undoped regions (14) to arise below the gaps on the

Layer (2) a further electrically insulating layer (9) is applied and that above the Column on this further electrically insulating Shih (9)

phase charge arrangements described. There is a silicon dioxide layer on a silicon substrate on which electrodes of the first level are applied, separated by gaps. This Elekd d Eb bh

p er further electrically insulating electrodes have been brought. This elec-

Layer (9) electrodes (10) of the second level on the first level consist of silicon. On the to be brought. Silicon dioxide layer and on the electrodes of the

2. The method according to claim 1, characterized in the marked level, a further silicon dioxide layer is recorded, that with an η-conductive substrate (1) brings, on the above the column electrodes of the Phosphorus ions in the edge areas (12) and boron-second level, which are made of aluminum ions are brought into the subregions (13) below the column 40.

be implanted.

3. The method according to claim 1, characterized in that that with a p-conductive substrate (1) Bori i di Rdbi

, in the case of a failing substrate (1)

Boron ions in the edge areas (12) and phosphorus ions in the Teilbih (13) hlb d S It is an object of the invention to provide a method of manufacturing a two-phase charge shifting arrangement indicate where the area of a

d areas (12) and phosphor shift stage with the same electrode widths against ions are now implanted in the sub-areas (13) below the column 45 via the above-mentioned charge shift arrangement. _{according to} the prior art reduced to half

This object is achieved by a method, as mentioned at the beginning, for producing a two-phase Ladhibd lö d f

4. Use of silicon as a material for the substrate in the method according to one of the

say 1 to 3 and a two-phase charge

5. Use of a SiOi layer as an electrical 50 movement displacement arrangement solved the invention insulating ^ layer ^ (2) in the process according to measure characterized by it dß h di one of claims 1 to 3 or the use

after approach 4

according to claim 4.

b. Use of a SiO ₂ or AbOs layer as a further lkth lid

measured is characterized in that the other ion implantation, which leads to the doping of the subregions leads in an oblique direction to the substrate surface

«, ..; ♦» 1 u · 1 ■ - ■ "". "· ~", ■ "*""" takes place that the angle between the direction of the

further electrically insulating layer (9) at a 55 an ion implantation, which is used for doping the edge Method according to one of Claims 1 to 3 or areas, and the substrate surface is smaller the use according to claim 4 or 5.

7. Use of silicon, molybdenum, aluminum, tungsten or chromium as material for the electrodes (3, 31) of the first level in the method according to one of Claims 1 to 3 or the use according to one of claims 4 to 6.

8. Use of aluminum, tungsten, silicon or chromium as material for the electrodes (10) the second level in the method according to any one of claims 1 to 3 or the use according to one of claims 5 to 7.

is set as the angle between the direction of the other ion implantation leading to the doping of the subregions leads, and the substrate surface, so that in-

follow the thickness of the electrodes and optionally a photosensitive layer on them a shadowing is caused, the undoped areas below the column can arise that on the First level electrodes and on the one in the column

exposed electrically insulating layer a further electrically insulating layer is applied and that above the column on this further electrically insulating layer electrodes of the second Fhp.

ne be applied.

A major advantage of the process according to the invention is that you can go through a double Angled implantation for charge shifting arrangements with electrodes in two buildings and potential barriers under the electrodes of the first level as well as under the electrodes of the second level can.

Advantageously, two electrodes lying next to one another, that is to say one electrode of the first level and one electrode of the second level, together form a shift stage, while in the usual manufacturing technique only A adjacent gate electrodes represent a shifting element. As a result of this fact, the area of a shift stage is reduced to half with the same widths of the electrodes.

Further explanations of the invention can be found in the description and the figures of preferred exemplary embodiments the invention and its further developments.

F i g. 1 shows a schematic representation of a cross section through a charge shifting arrangement, in which doped regions are generated in the semiconductor substrate by ion implantation in oblique directions will;

F i g. 2 shows a schematic representation of a charge shifting arrangement produced according to the method according to the invention;

F i g. 3 shows the potential profile in a charge transfer arrangement produced according to the method according to the invention.

In FIG. 1 is the substrate on which the charge transfer device is set up, denoted by 1. This substrate is preferably made of n- or p-conducting Silicon.

An electrically insulating layer 2, which preferably consists of S1O2, is applied to this substrate 1. With the aid of photolithographic process steps, the electrically insulating layer 2 Electrodes 3, 31 applied to the first level. These electrodes are preferably made of silicon, molybdenum, Aluminum, tungsten or chrome. After etching the gap 11 between the electrodes on these Remaining residues of the previously photosensitive layer are denoted by 4.

As in FIG. 1, the edge regions 12 are now shown in individual ion implantation steps and the subregions 13 are produced. The doped edge regions located in the substrate 1, which are essentially as can be seen from the figure, located below the edge of the electrodes 31, which the ion beam is facing are denoted by 12. The ion beam, with the help of which ions are introduced into the edge region 12 are implanted is denoted by 5. The ion beam 5 is irradiated at an angle to the substrate surface. The angle that the ion beam 5 forms with the substrate surface is denoted by 7.

With the help of the ion beam 5 ions that are from of the same kind of ions as the ions contained in the substrate are implanted. For example, in the edge regions 12 in the case of an η-conductive substrate 1 phosphorus ions and in the case of a p-conductive substrate Implanted boron ions.

With the help of the ion beam 6, which is also inclined to the (15 Substrate surface is irradiated, that is partially located below the gap 11 in the substrate Sub-area 13 doped. The ion beam is denoted by 6. The angle between the ion beam 6 and the substrate surface bears the reference number 8. As a result of the thickness of the electrode 3 and that located on it Photoresist layer 4, due to the oblique irradiation of the ion beam 6, shading occurs, so that a non-doped region 14 arises in the substrate 1. This non-doped area 14 causes, like the doped Pand region 12, a potential barrier during operation of the charge shifting arrangement.

With the help of the ion beam 6, ions of the complementary ion type as those in the substrate contained ions are implanted. For example, in the subregions 13 in the case of an η-conductive substrate Boron ions and, in the case of a p-conducting substrate, phosphorus ions are implanted.

In further process steps, as shown in FIG. 2 shown after the remnants 4 of the photoresist layer are removed to the arrangement of FIG. 1, d. H. that is to say on the areas of the exposed in the gap 11 Substrate surface and on the surface of electrodes 3, 31 a further electrically insulating layer 9 upset. This layer 9, like the layer 2, preferably consists of silicon dioxide. On the Layer 9 are now the electrodes above the gaps between the electrodes 3, 31 of the first level 10 of the second level made. These electrodes 10 of the second level are preferably made of aluminum, Silicon, tungsten or chromium. To manufacture these second level electrodes, it is preferred first an aluminum layer 9 is applied to the entire surface of the layer 9, from which then with The electrodes 10 of the second level with the aid of per se known photolithographic process steps getting produced.

In Figure 3 is the potential curve that is in a Charge shifting arrangement produced according to the method according to the invention during operation is shown. From the figure it can be seen that in the area 14 a potential barrier 141 and in the Area 12 a potential barrier 121 is created.

It is essential for two-phase operation that there is also a potential barrier under the electrodes of the second level 14 is arranged. For example, with the help of the ion beam 5 phosphorus ions and boron ions are implanted into an η-conductive silicon substrate 1 by the beam 6, as is also shown in FIG. 3 It can be seen that the potential under the electrodes 31 is raised to generate potential barriers and lowered in the implanted gap areas. The reduction happens so far that good transmission properties be achieved. The potentials in the gap area can match the potentials under the electrodes 3 and 31 can still be adapted by changing the potentials in the entire gap area by a customary Vertical implantation can be raised or lowered. In the non-implanted cleft areas 14, the surface potential is not influenced, which means that there are those for two-phase operation necessary potential barriers 141.

With the aid of charge shifting arrangements produced by the method according to the invention, the length of a shift stage can advantageously be reduced to the length of two electrodes, see above that the area of a shift stage is only half as large as the area in the known charge shifting arrangements with electrodes in two levels of the prior art. The area is advantageous

a shift stage only about ² Ii as large as in known charge shifting arrangements in which electrodes are only arranged in one plane when the gaps are about half as wide as the electrodes.

This advantage of the higher packing density is evident crucial for the application in memory sound systems and for sensors in solid-state cameras.

1 sheet of drawings

Claims (1)

Patent claims: The invention relates to a method for producing a two-phase charge displacement arrangement with a substrate made of semiconductor material ι, _η ή an electrically insulating 5 layer located thereon, on which electrodes of the first level are provided separated by gaps, in which the semiconductor material is provided with two ion implantations Edge areas below the edge of the electrodes and partial areas below the column are doped ο with the one ion implantation, which leads to the doping of the edge areas, taking place in an oblique direction to the substrate surface.