JPH03296224A - Bipolar transistor - Google Patents

Abstract

PURPOSE:To enable an entire element area to be reduced and parasitic resistance which is produced between a collector electrode and a collector buried layer to be reduced by providing a penetration hole between the collector electrode and the collector buried layer and by connecting the collector electrode and the collector buried layer electrically through a conduction part which is formed inside this penetration hole. CONSTITUTION:In a vertical-type bipolar transistor production process, a photoresist 19 with an opening pattern is formed on a silicon oxide layer 18. Using this photoresist 19 as a mask, the silicon oxide layer 18 is etched to an epitaxial layer 13, thus forming an opening 20a. Then, the epitaxial layer 13 is etched to a collector buried layer 12 by an anisotropical etching using a chloride gas, thus forming a penetration hole 20. After etching ends, the photoresist 19 is eliminated. Then, a metal material such as aluminum and tungsten is buried into the penetration hole 20, thus forming a conduction part 21. Then, a collector electrode 22, a base electrode 23, and an emitter electrode 24 which are connected to each of the conduction part 21, a base 16, and an emitter 17 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vertical bipolar transistor having a buried collector layer.

[Prior Art] Among vertical bipolar transistors in which an emitter, base, and collector are arranged in the depth direction of a substrate, a type in which a collector buried layer is formed under the collector is conventionally known. In this type of bipolar transistor, impurities are diffused from the lower part of the collector electrode to the collector buried layer to reduce parasitic resistance generated between the collector electrode and the collector buried layer.

[Problem to be Solved] Since the distance from the collector electrode to the collector buried layer is usually about several micrometers, impurities are diffused not only in the depth direction of the substrate but also in the lateral direction. Therefore,
A corresponding dimensional margin must be provided in the lateral direction, and a large element area is required. Furthermore, since the impurities spread widely in the lateral direction, parasitic resistance could not be sufficiently reduced.

A first object of the present invention is to reduce the device area of a vertical bipolar transistor having a buried collector layer.

A second object of the present invention is to reduce parasitic resistance occurring between the collector electrode and the collector buried layer.

[Means for Solving the Problems] The present invention provides a through hole between the collector electrode and the collector buried layer, and forms a conductive portion inside the through hole to connect the collector electrode and the collector buried layer with electricity. It is connected to

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 to FIG. 6 are cross-sectional views showing manufacturing steps in an example.

11 is a silicon substrate, 12 is a collector buried layer, 13 is an epitaxial layer, 14 is an element isolation diffusion, 15 is a collector, 16 is a base, 17 is an emitter, 18 is a silicon oxide layer, 19 is a photoresist, and 20 is a through hole. be. 2
Reference numeral 1 denotes a conductive portion, which is embedded in the through hole 20 using aluminum or tungsten. 22 is a collector electrode, 23 is a base electrode, and 24 is an emitter electrode.

Next, the manufacturing process will be explained according to FIGS. 1 to 6.

Step (1): After forming an N-type collector buried layer 12 on a P-type silicon substrate 11, an epitaxial layer of silicon is grown to form an epitaxial layer 13. next,
Boron is diffused into the epitaxial layer 13 to form element isolation diffusions 14. Next, boron and arsenic are sequentially diffused into the epitaxial layer 13 to sequentially form a base 16 and an emitter 17. Next, thermal oxidation method, CVD method,
Alternatively, the silicon oxide layer 18 is formed by a method using a combination of these methods. The above steps are steps that are used projectively in a vertical bipolar transistor having a buried collector layer.

Step (2) A photoresist 19 having an opening tab is formed on the silicon dioxide layer 18. Using this photoresist 19 as a mask, the silicon oxide layer 18 is etched by anisotropic etching using fluorine gas until it reaches the epitaxial layer 13, thereby forming an opening 20a.

Step (3): Subsequently, the epitaxial layer 13 is etched by anisotropic etching using chlorine gas until it reaches the collector buried layer 12, thereby forming the through hole 20.

Step (4): After the etching is completed, the photoresist 19 is removed.

Step (5): A metal material such as aluminum or tungsten is filled into the through hole 20 to form a conductive portion 21 using a method combining a bias sputtering method and an etchback method or a selective CVD method.

Note that in the drawing, the surface of the conductive part 21 is the same as the epitaxial layer 1.
3 and the silicon oxide layer 18, this position may be any position as long as it can be easily connected to a collector electrode, which will be described later.

Step (6) After forming contact holes in the silicon oxide layer 18 above the second base 16 and the emitter 17,
An aluminum film is formed and patterned to form a collector electrode 22, a base electrode 23, and an emitter electrode 24 connected to the conductive portion 21, base 16, and emitter 17, respectively. Subsequently, the process is completed by sintering the aluminum, forming an overcoat, and opening a window in the pad area.

[Effects] In the present invention, a through hole is provided between the collector electrode and the collector buried layer, and the collector electrode and the collector buried layer are electrically connected via a conductive portion formed inside the through hole. Therefore, the overall device area is reduced, and the parasitic resistance generated between the collector electrode and the collector buried layer is significantly reduced.

[Brief explanation of drawings]

1 to 6 are cross-sectional views showing manufacturing steps in an embodiment of the present invention. 12...Collector buried layer 20...Through hole 21...Conductive part 22...Collector electrode

Claims (1)

[Claims] In a vertical bipolar transistor having a buried collector layer, a through hole reaching the buried collector layer is provided under the collector electrode, and the collector electrode and the buried collector are connected through a conductive part formed inside the through hole. A bipolar transistor that is electrically connected to the layers.