A method of manufacturing semiconductor devices

 

(57) Abstract:

Usage: in microelectronics, in particular in the manufacture of semiconductor devices during the preparation of crystals for Assembly into the housing. The essence of the invention: on the collector side of the plate with the generated structures of semiconductor devices consistently put a layer of aluminum and Germany. The plate is divided into crystals and carry out the brazing crystals on crystallochemical. After applying a layer Germany put an extra layer of aluminum with a thickness in the range 0.05 to 0.15 the thickness of Germany, and conducting heat treatment in a gaseous environment with the content of the oxidizing components of oxygen and/or water vapor for more than 3 vol.% at 424 - 510oC.

The invention relates to microelectronics, in particular the production of semiconductor devices, and can be used in the preparation of crystals for Assembly into the case.

The known method of mounting the crystals in the metal casing on which the gasket of the eutectic alloy, such as gold-germanium, is placed between the crystal and heated to the temperature of the eutectic alloy body [1]

The disadvantage of this method is the low electrical parametrically to the base of the case.

Known the closest to the technical nature of the invention is a method of manufacturing semiconductor devices, comprising the sequential deposition on the collector side plates formed with structures of semiconductor devices of layers of aluminum and Germany, the separation of the plates at the crystals, the brazing crystals on crystallochemical covered with aluminium [2]

The disadvantages of this method are irreproducibility and low electrophysical parameters of semiconductor devices caused by incompleteness (by area) of contact of the crystal to the case base as a result of partial oxidation of Germany, and his cracking and peeling in some areas.

Reduction of the area of connection of crystal with crystallochemical leads to increased thermal resistance (Rtn-k), reducing power dissipation.

The challenge which seeks the invention is the improvement of electrical characteristics of semiconductor devices and increase the reproducibility of the process by increasing the area of the wettability of the contacting surfaces, reduce the likelihood of oxidation of the soldering p is bretania is in the method of manufacturing semiconductor devices, comprising the sequential application on the collector side of the plate with the generated structures of semiconductor devices of layers of aluminum and Germany, the separation of the plates at the crystals, the brazing crystals on crystallochemical, according to the invention after application of a layer of Germany put an extra layer of aluminum with a thickness in the range of 0.05 to 0.15 the thickness of Germany, followed by a heat treatment in a gaseous environment with the content of the oxidizing components of oxygen and/or water vapor of not more than about 3. in the temperature range 424 510oC.

In the process of trimoorti plates in the temperature range 424 510oC on the boundary of the first lying to the silicon layer of aluminum and germanium is mutual dissolution of aluminum and Germany. Formed at the boundary of layers of aluminum and germanium transition layer provides sufficient adhesion layer Germany with the underlying layer of aluminum, which ensures the integrity of the collector cover for any accompanying cutting and breaking plates mechanical stresses.

Carrying out heat treatment of the plates in any gas environments with moderate, not more than 3% steriani role of an additional layer of aluminum. The layer of aluminum germanium protects from oxidation during the heat treatment of the plates, and when the brazing crystals, which in the presence of an additional layer of aluminum is permitted to apply directly to the air, which greatly simplifies the process of soldering, providing at the same time 100% full contact crystal and Kristallografiya.

Heat treatment of the wafer with formed collector coated Al Ge - Al in gas environments with increasing content (>3%) oxidizing agents, for example air, can lead to oxidation of the collector cover and non-repeatable process soldering crystals.

The range of thicknesses additional protective layer of aluminum is selected based on the need to fulfill the complete dissolution of the aluminum layer and Germany. Violation of this provision if the thicknesses of 0.15 the thickness of the layer Germany saves after heat treatment or pure aluminum surface or layer, enriched with aluminum, which negatively affects the quality of soldering.

Reduction of the thickness of the additional layer of aluminum is less than 0.05 the thickness of Germany leads to the formation on the surface of the collector panaceia thermal treatment regimes collector coating is selected depending on thermal stability of the metallization of a semiconductor device and other possible reactions of the materials in the structure. The minimum heat treatment temperature 424oC is the temperature of the eutectic alloy aluminum germanium. Exceeding 510oC leads to a deliberate increase leakage currents of p-n junctions on most types of silicon devices due to degradation of the structures.

Tests of the proposed method on the experimental batches of transistors, small-and medium-capacity type CT 3102, CT 3107, CT 816, CT 817, CT 604, CT 602 and IP type CU NC, IN, IN showed that by introducing an additional layer of metal increased yield structures and improved characteristics such transistor structures, asCanas30 50% 10 - 20% of the reproducibility of the process of soldering crystals up to 100%

The proposed method is implemented in the manufacture of semiconductor devices according to the following route.

Example 1.

On silicon wafers create a transistor structure methods of photolithography, ion doping and diffusion.

Form aluminum metallization transistor structures.

After viginia metallization when 5100,5oC for 10 min conducting the control of the electrical parameters of the transistor structures.

Reduce the thickness of the Plaza is l Ge Al magnetron sputtering method on the installation type "ORATORIO-5" (NI-7-006) spray messenia, made of aluminum and Germany.

Mode of application:

preliminary vacuum of 5 x 10-7mm RT.article.

the temperature of the substrate 25020oC,

the current aluminium target 102 AND,

current germanium target of 1.5-2A

the pressure of argon 52 x 10-3mm RT.article.

The thickness of the first layer of aluminum, in contact with silicon, 0.2 to 0.3 μm, the second layer Germany 1.5 to 2 μm, the top layer of aluminum of 0.1 to 0.2 μm.

In the furnace LMS 125/5 conduct heat treated plates with 5000,5oC for 5 min in a stream of nitrogen gas with a flow rate of 22060 l/h at atmospheric pressure. The volume fraction of oxygen in nitrogen 1% water vapor 0,1%

The plates are cut and separated into the crystals.

Method of contact-reactive brazing crystals you solder to the base, covered with aluminum. Temperature soldering 460 480oC, time of process 1 3 C. Soldering is carried out on the air.

Example 2. Different thicknesses of the three-layer collector metallization:

the thickness of the first aluminum layer is 0.5 μm,

the thickness of the layer Germany 0.1 ám,

the thickness of the upper layer of aluminium of 0.005 μm.

Heat treatment time of 1 min at 4300,5oC.

The method of manufacturing according to Rovaniemi structures of semiconductor devices of layers of aluminum and germanium, the separation of the plates at the crystals, the brazing crystals on crystallochemical, characterized in that after applying a layer Germany put an extra layer of aluminum with a thickness in the range of 0.05 to 0.15 the thickness of Germany, followed by a heat treatment in a gaseous environment with the content of the oxidizing components of oxygen and (or) water vapor of not more than about 3. in the temperature range 424 510oC.

 

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