SEMICONDUCTOR DEVICE

• US 20090046405A1
• Filed: 08/06/2008
• Published: 02/19/2009
• Est. Priority Date: 08/06/2007
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Device Technology Company Limited (Fuji Electric Systems Company Limited)
• Inventors: ICHIKAWA, Hiroaki
• Granted Patent: US 8,325,452 B2
• Time in Patent Office: Days
• US Class Current: 361/103
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H03K 17/0822 in field-effect transistor switches
• CPC Class Codes: H03K 2017/0806 against excessive temperature

Abstract

In order to enable detection of degradation of the heat dissipation from a semiconductor chip, even when the operating state of a semiconductor device cannot be predicted, a thermal resistance calculation circuit calculates the thermal resistance of the heat dissipation path from the semiconductor chip, based on the loss of a switching element calculated by a loss calculation circuit and the temperature of the semiconductor chip calculated by a temperature calculation portion, and when the voltage corresponding to the thermal resistance calculated by the thermal resistance calculation circuit exceeds a reference voltage, switching operation of the switching element is halted.

Claims

1. A semiconductor device, comprising:

a semiconductor chip on which a switching element is formed;

a mounting substrate on which the semiconductor chip is mounted with an intervening solder layer;

a heat dissipation mechanism that dissipates heat generated by the semiconductor chip;

a current detection circuit that detects current flowing in the switching element;

a voltage detection circuit that detects a voltage applied to the switching element;

a loss calculation circuit that calculates a loss occurring in the switching element based on the current detected by the current detection circuit and the voltage detected by the voltage detection circuit;

a temperature detection mechanism that detects a temperature of the semiconductor chip; and

a thermal resistance calculation circuit that calculates a thermal resistance in a dissipation path from the semiconductor chip based on the switching element loss calculated by the loss calculation circuit and the semiconductor chip temperature detected by the temperature detection mechanism.

2. The semiconductor device according to claim 1, wherein the thermal resistance calculation circuit comprises:

a temperature difference calculation portion that calculates the temperature difference before and after the occurrence of the loss calculated by the loss calculation circuit by referencing the temperature detected by the temperature detection mechanism; and

a thermal resistance calculation portion that calculates the thermal resistance in the heat dissipation path from the semiconductor chip based on the loss calculated by the loss calculation circuit and the temperature difference calculated by the temperature difference calculation portion.

3. The semiconductor device according to claim 2, wherein the thermal resistance calculation circuit calculates an integrated value of losses occurring in the switching element and the temperature difference of the semiconductor chip based on time elapsed until saturation of temperature in the heat dissipation path from the semiconductor chip and a semiconductor chip temperature difference, and calculates the thermal resistance at a specific location on the heat dissipation path from the semiconductor chip.

4. The semiconductor device according to claim 3, wherein by setting a time interval, over which the integrated value of losses occurring in the switching element and the semiconductor chip temperature difference are calculated, to 200 ms or less, the thermal resistance calculation circuit monitors anomalies in the solder layer fixing the semiconductor chip to the mounting substrate, and by setting the time interval, over which the integrated value of losses occurring in the switching element and the semiconductor chip temperature difference are calculated, to two seconds or less, the thermal resistance calculation circuit monitors anomalies in a contact face of the heat dissipation means, and by setting the time interval, over which the integrated value of losses occurring in the switching element and the semiconductor chip temperature difference are calculated, to two seconds or more, the thermal resistance calculation circuit monitors anomalies in the heat dissipation mechanism.

5. The semiconductor device to claim 1, further comprising:

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with a prescribed value; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the prescribed value.

6. The semiconductor device according to claim 1, further comprising:

a control circuit that controls switching operation of the switching element;

a thermal resistance prediction circuit that calculates the switching element loss and temperature based on control information controlling the switching operation, and predicts the thermal resistance in the heat dissipation path from the semiconductor chip;

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with the thermal resistance predicted by the thermal resistance prediction circuit; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the thermal resistance predicted by the thermal resistance prediction circuit.

7. The semiconductor device to claim 2, further comprising:

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with a prescribed value; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the prescribed value.

8. The semiconductor device according to claim 2, further comprising:

a control circuit that controls switching operation of the switching element;

a thermal resistance prediction circuit that calculates the switching element loss and temperature based on control information controlling the switching operation, and predicts the thermal resistance in the heat dissipation path from the semiconductor chip;

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with the thermal resistance predicted by the thermal resistance prediction circuit; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the thermal resistance predicted by the thermal resistance prediction circuit.

9. The semiconductor device to claim 3, further comprising:

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with a prescribed value; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the prescribed value.

10. The semiconductor device according to claim 3, further comprising:

a control circuit that controls switching operation of the switching element;

a thermal resistance prediction circuit that calculates the switching element loss and temperature based on control information controlling the switching operation, and predicts the thermal resistance in the heat dissipation path from the semiconductor chip;

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with the thermal resistance predicted by the thermal resistance prediction circuit; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the thermal resistance predicted by the thermal resistance prediction circuit.

11. The semiconductor device to claim 4, further comprising:

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with a prescribed value; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the prescribed value.

12. The semiconductor device according to claim 4, further comprising:

a control circuit that controls switching operation of the switching element;

a thermal resistance prediction circuit that calculates the switching element loss and temperature based on control information controlling the switching operation, and predicts the thermal resistance in the heat dissipation path from the semiconductor chip;

a comparison mechanism that compares the thermal resistance calculated by the thermal resistance calculation circuit with the thermal resistance predicted by the thermal resistance prediction circuit; and

a protection circuit that either halts operation of the switching element or limits the current flowing in the switching element, when the thermal resistance calculated by the thermal resistance calculation circuit exceeds the thermal resistance predicted by the thermal resistance prediction circuit.