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Method for producing an integrated circuit including a trench transistor and integrated circuit

Method for producing an integrated circuit including a trench transistor and integrated circuit description/claims

The invention relates to a method for producing a vertical trench transistor, and to a vertical trench transistor.

Trench transistors are sufficiently known. These are MOS transistors in which a gate electrode is arranged in a trench extending into a semiconductor body. In this case, the gate electrode is insulated from the semiconductor body by a gate dielectric layer and serves for controlling a conducting channel in a body zone arranged between a source zone and a drift zone/drain zone of the transistor.

The switch behavior of a MOS transistor is crucially influenced by the gate-drain capacitance, which is also referred to as Miller capacitance. The gate-drain capacitance is formed by sections of the gate electrode and of the drift zone/drain zone which mutually overlap, and a section of the gate dielectric which lies between the sections. In this case, a switching delay of the transistor upon a transition from a conducting to a blocking state, and vice versa, is shorter, the smaller the capacitance. Since the switching losses of a transistor increase as the switching delay increases, a rapidly switching transistor, that is to say a transistor having a smallest possible gate-drain capacitance, is desirable with regard to reducing the switching losses.

One embodiment relates to a method for producing a trench transistor having a drift zone and a body zone adjacent to the drift zone, the method including: providing a semiconductor body having a first side and a first semiconductor zone of a first conduction type, producing a first trench, which has trench sidewalls and a trench bottom and which extends into the semiconductor body proceeding from the first side, producing at least one first spacer at the trench sidewalls which leaves free a section of the trench bottom, producing a second semiconductor zone of a second conduction type complementary to the first conduction type, which second semiconductor zone is adjacent to the first semiconductor zone in the direction of the first side of the semiconductor body and extends in the direction of the first semiconductor zone as far as below the trench bottom, and producing at least one third semiconductor zone of the first conduction type by introducing dopant atoms via the left-free section of the trench bottom, the first and the at least one third semiconductor zone forming the drift zone and the second semiconductor zone forming the body zone at least in sections.

Another embodiment relates to a method for producing a trench transistor having a drift zone and a body zone adjacent to the drift zone. This method provides for providing a semiconductor body having a first semiconductor zone of a first conduction type and a second semiconductor zone of a second semiconductor zone complementary to the first conduction type, the second semiconductor zone being adjacent to the first semiconductor zone in a vertical direction of the semiconductor body; producing a trench having trench sidewalls and a trench bottom and extending through the second semiconductor zone right into the first semiconductor zone; producing a further semiconductor zone of the second conduction type, which reaches along the first trench from the first semiconductor zone as far as the second semiconductor zone; producing spacer layers at the trench sidewalls which leave free a section of the trench bottom; and producing at least one third semiconductor zone of the first conduction type in a section of the second semiconductor zone which is arranged between the trench bottom and the first semiconductor zone, by introducing dopant atoms into the semiconductor body via the left-free section of the trench bottom. In this case, the first and the at least one third semiconductor zone form the drift zone, and the second and the further semiconductor zone of the second conduction type form the body zone at least in sections.

Another embodiment relates to a trench transistor, including: a semiconductor body, a drift zone of a first conduction type arranged in the semiconductor body, and a body zone of a second conduction type adjacent to the drift zone in a vertical direction of the semiconductor body, a gate electrode arranged in a first trench of the semiconductor body, the gate electrode being insulated from the semiconductor body by a gate dielectric layer. In this component, the drift zone has a first drift zone section, which is arranged at a distance from the trench, and a second drift zone section, which reaches from the first drift zone section as far as a bottom of the trench and which does not reach beyond the trench in the lateral direction of the semiconductor body.

Another embodiment relates to a method for producing a trench transistor having a drift zone, the method including: providing a semiconductor body having a first side, producing a trench extending into the semiconductor body proceeding from the first side and having trench sidewalls, producing a field electrode in the trench, which field electrode is insulated from the semiconductor body by a field electrode dielectric and partly fills the trench, such that regions of the trench sidewalls are not covered by the field plate dielectric and the field plate dielectric is uncovered at the bottom of a trench produced after the production of the field electrode, producing a protective layer at regions of the trench sidewalls which are not covered by the field plate dielectric, introducing dopant atoms into uncovered regions of the field plate dielectric, and introducing dopant atoms from the field plate dielectric into the semiconductor body in order to produce a doped semiconductor zone forming a part of the drift zone.

The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

FIG. 1 illustrates a method for producing a drift zone section—arranged below a trench—of a trench transistor using spacers applied to sidewalls of the trench.

FIG. 2 illustrates a method for producing the spacers at the sidewalls of the trench.

FIG. 3 illustrates a method which is modified relative to the method in accordance with FIG. 1 and in which two spacers are applied to the sidewalls of the trench one above another.

FIG. 4 illustrates, on the basis of a vertical cross section through a semiconductor body, a first exemplary embodiment of a trench transistor having a drift zone with two drift zone sections.

FIG. 5 illustrates a second exemplary embodiment of a trench transistor with two drift zone sections.

FIG. 6 illustrates a third exemplary embodiment of a trench transistor with two drift zone sections.

FIG. 7 illustrates a fourth exemplary embodiment of a trench transistor with two drift zone sections.

FIG. 8 illustrates a horizontal cross section through the semiconductor body of the trench transistors in accordance with FIGS. 4 to 7 (FIG. 8A) and a further vertical cross section through the semiconductor body in a different sectional plane (FIG. 8B).

FIG. 9 illustrates a further method for producing a drift zone section of a trench transistor.

• Provisional Patent
• Utility Patent

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