DE2705407A1 - Radiation-insensitive ferroelectric component prodn. - by forming two electric contacts one on vapour deposited thin film of potassium nitrate - Google Patents

Abstract

Prodn. comprises first forming an electric empact and a solid, thin film of potassium nitrate on at least a part of the contact. The thin film is vapour deposited in vacuum of 10-5 torr. Then a second electric contact is produced over at least a part of the thin film. Subsequently a protective film of silicon dioxide is deposited over the sandwich assembly of the two contacts and the thin potassium nitrate film. Then the assembled laminate is heated for >=15 mins. at 100-300 degrees C. Gold is pref. used for the prodn. of the two contacts.

Description

Herne 1, NOO Munich 40,

Frelllgrathstrasse 19 ΠΙ «» Ι Inn UM RaKr Elsenaeher SUaSe 17

P.O. Box ι mo υΐρΐ.-ΙΠβ. Π. Π. Uanr Prt.-Anw. BeIzIw

Pat. H.rnnarm-Trentepohl DiDl.-PhVS. Eduard BetZler telephone: »» « Telephone: 51013 r # 36 3012

^{510 u} Dlpl.-lng. W. Herrmann-Trentepohl

Telegram address: Telegram address:

Bahrpatenle Merne PATENTANWÄLTE Babetzpat Munich

Telex 06229 853 Telex 5215360

π bank accounts:

- Bayerische Vereinebank Munich «52

* * , Dresdner Bank AQ Herne 7-520

Postal check account Dortmund 556 * 8-467

"" ■■ M 05 855 B / h.

Please indicate in the answer Please send a letter to:

Munich

February 8, 1977

Technovation, Inc.

711 Johnstone

Sault Ste. Marie, Michigan 49783

United States

Process for the production of a ferroelectric component and component produced according to this process

The invention relates to a method for producing a ferroelectric component, according to which a first electrical contact and then a permanent, thin film of potassium nitrate are formed over at least part of the electrical contact by vapor deposition in a vacuum at a pressure not greater than 1 χ 10 Torr . A second electrical contact is then made over at least a portion of this film. A protective cover made of silicon monoxide is then applied by vapor deposition over the first contact, the film and the second contact. The entire arrangement with the protective cover is then heated for a certain time at a predetermined temperature.

A preferred embodiment is a method for the production of a ferroelectric component including the cleaning of the substrate by chemical means with subsequent high-frequency etching.

Then the substrate is preheated and a first metal layer

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evaporated in a vacuum. Ks is followed by vapor deposition of a thin film of potassium nitrate. A second metal layer is then evaporated onto the potassium nitrate. A silicon oxide layer is then applied by vapor deposition. Finally, this assembly is heated in an oven for about 24 hours and at a temperature of about 160 ⁰ C.

Furthermore, the invention provides a manufactured according to the new method ferro-electrical component.

A preferred embodiment is a method of making a ferro-electric components with process steps to form a first electrical contact made of a suitable metallic substance, such as aluminum, silver, gold, etc. By vapor deposition in a vacuum At a pressure no greater than 1 χ 10 Torr, a permanent thin film of potassium nitrate is then produced over at least part of the contact. This is followed by a second electrical contact made of one of the above-mentioned metallic substances over at least part of the film educated. Then a coating of silicon manoxide is applied over the first contact, deposited the film and the second contact by evaporation. The layered component is then for a certain time and at heated to a certain temperature. This process provides a component that is superior to all previous products.

The thin film of phase III potassium nitrate dissolves very quickly. Will When exposed to the normal room environment, the phase III structure has a tendency to move to phase II because of this dissolution.

During the manufacture of the component, a passivation layer is made Silicon monoxide is applied to protect the potassium nitrate against external influences. The packaging of the component is used as additional protection embedding in silica gel is desirable.

As an example of a functioning component manufactured according to the above-mentioned technique, a packaged memory element consisting of a glass-coated, ceramic, ferroelectric component with 28 connections was placed in a glass of water and left therein for about 72 hours .

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The component was checked every four hours, and at the end of the 72nd Hours still fully functional. The component was then stored on a shelf and checked again a week later and was still fully in Function. This test was repeated three times with consistent results.

In accordance with another embodiment of the invention, the substrate is first chemically cleaned and then high-frequency etched. The substrate is then approximately heated to 160 ⁰ C. A first layer of an electrical contact, for example aluminum, gold, silver, etc., is then initially applied by vapor deposition in a vacuum. This arrangement is then ^{heated at a temperature of about 160 °} C. for about 15 minutes.

A thin film of potassium nitrate is then evaporated onto it, and this arrangement is ^{heated at about 160 °} C. for about 15 minutes.

A silicon monoxide coating is then evaporated onto this arrangement. Optionally, the arrangement is placed on top of a silicon jelly and heated ^{at 160 ° C. for about 24 hours.}

Alternatively, it is not necessary after each of the previously mentioned work steps switch on a heat-up stage, but there can also only be one last heat-up stage are provided.

In a further embodiment of the invention, the potassium nitrate film is on a Thickness not held above 1500 Å units.

The following table A shows some examples of those following the new procedure manufactured components.

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Table - "Λ"

Step mr .

1. Material
Precipitation time

measured on the monitor
thickness

2. Material

Precipitation time

measured on the monitor
thickness

3. Material
Precipitation time

measured on the monitor
thickness

4. Material
Precipitation time

measured on the monitor
thickness

Λ-Ι

rehearse

Λ-ΙΙ ß-I B-II C-I

C-II

gold gold gold gold gold gold 2:40 2:00 1:20 1-15 1:10 1:00

150
KNO

150 KNO _n

150

KNO _n

150 KNO _n

150

150

KNO ₃

15:00 15:00 18:00 15:00 15:00 10:00

400

400

700

1000 1000

gold gold gold gold gold gold 1:40 1:50 1:00 1:10 1:20 1:10

150 150 150 150

150 150

SiO SiO SiO SiO SiO SiO 2:00 3:00 2:00 2:20 3:00 2:00

800

800 1000 1000 800

In table "A" the units for the precipitation times are minutes, the thickness read on the monitor indicates the thickness and density at the measuring point, measured by a crystal thickness / quantity measuring device.

10

In this way, components were obtained which are capable of driving 10 to 10 Hz cycles. This has primarily been achieved with gold electrodes, with the potassium nitrate film having a thickness of less than 1500 Å, and preferably in the range from 600 to 800 Å. There is only a heating or tempering time of 15 minutes

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Λ-

required at a temperature of 180 ° to 380 ⁰ C, preferably from 180 ° C, after applying the Siliziummonoxidüberzuges and prior to setting and application of the gel material. It is also advisable to keep the thickness of the gold electrodes at around 150 Å.

The second parameter determining the service life is the number, which indicates how often information can be written into the component and read again with deletion of this information and this process can be repeated, or in other words, the total number of read / write cycles. The invention was the

Number of read / write cycles improved to at least 10. In the experiment there were pauelements that were activated at 850 kH with 10 write / read cycles and all of them retained their original information with a fluctuation of + _ 5%. In contrast , the manufacturers of memory elements based on nitrite only guarantee a service life of 10 to 10 read / write cycles. Components according to the invention were at a repetition frequency of 833.333 Hz for 12.025 sec. switched. That means a read / write frequency of 1.002 χ 10 .

In contrast to the nitrite-based components, the storage time of the components according to the invention is not a function of the write time. Read and write times are symmetrical for the components according to the invention.

The components according to the invention are insensitive to radiation. They were exposed to radiation of gamma 10, were working normally and maintained the information. The component was right next to the gamma source. In comparison, bipolar components are destroyed at 10 gamma, while other memory elements on the market are destroyed at 10 gamma or less.

i - Claims: -

709833/065 «

Claims (10)

Claims rl. ^ Process for the production of a ferro-electric component, characterized by the following steps: forming a first electrical contact; Formation of a solid thin film of potassium nitrate on at least a portion of the contact by vacuum evaporation at one pressure not greater than 10 ~ Torr; Forming a second electrical contact over at least one Part of the film; Evaporation of a protective layer of silicon monoxide over the first Contact, the film and the second contact and heating the first and second contact, the film and the Protective layer for a certain time and at a certain temperature. 2. The method according to claim 1, characterized in that the heating time is not less than 15 minutes and the temperature falls ^{in the range from about 100 °} C to 300 ^{° C.} 3. The method according to claim 1 or 2, characterized by the use of gold for the first and second contact. 4. The method according to any one of the preceding claims, characterized in that the film is vapor deposited in a thickness of not more than 1500 Å. 5. The method according to any one of the preceding claims, characterized in that the film has a thickness in the range from about 600 to 800 Α units is evaporated. 709833/0659 6. The method according to any one of the preceding claims, characterized in that the component is included in the packaging is coated with a silicone gel. 7. The method according to any one of the preceding claims, characterized in that the first and the second contact from Gold made about 150 Α units thick each will. 8. The method according to any one of the preceding claims, characterized in that before forming the first contact a substrate is first chemically cleaned, high-frequency etched and preheated, after which the first contact in a vacuum on the substrate being knocked down. 9. The method according to any one of the preceding claims, characterized in that after the formation of the first contact and at least one additional heating stage is provided before the protective layer made of silicon monoxide is deposited. 10. According to the method according to one or more of the preceding claims manufactured ferro-electric component. 709833 / 06B9