Method for manufacturing a sensor device
View Patent ↗A motion sensor in the form of an angular rate sensor and a method of making a sensor are provided and includes a support substrate and a silicon sensing ring supported by the substrate and having a flexive resonance. Drive electrodes apply electrostatic force on the ring to cause the ring to resonate. Sensing electrodes sense a change in capacitance indicative of vibration modes of resonance of the ring so as to sense motion. A plurality of silicon support rings connect the substrate to the ring. The support rings are located at an angle to substantially match a modulus of elasticity of the silicon, such as about 22.5 degrees and 67.5 degrees, with respect to the crystalline orientation of the silicon.
1. A method for manufacturing a sensor device having a circuit portion and a movable sensing portion, the method comprising the steps of:
providing a substrate having an insulation layer on a top surface;
providing a silicon layer on top of the insulation layer;
forming a first trench extending through the silicon layer and reaching the insulation layer so as to isolate a first portion of the silicon layer from a second portion of the silicon layer;
disposing a fill material within the first trench;
forming one or more electrical components on the first portion of the silicon layer;
forming one or more contacts on the second portion of the silicon layer;
forming one or more second trenches in the second portion of the silicon layer so as to provide one or more movable elements within the second portion of the silicon layer, wherein the one or more movable elements serve as sensing elements; and
forming one or more anti-stiction bumps to prevent a portion of movable element from sticking to an adjacent feature of the sensor;
wherein the step of forming the second trench exposes at least a portion of the anti-stiction bumps.
2. The method as defined in claim 1 , wherein the step of forming the one or more anti-stiction bumps comprises forming the anti-stiction bumps prior to delineation and release of the movable element.
3. The method as defined in claim 1 further comprising the step of forming a dielectric layer on sides of the first trench prior to disposing the fill material within the first trench.
4. The method as defined in claim 1 , wherein the sensor device comprises an angular rate sensor.
5. The method as defined in claim 1 , wherein the substrate comprises silicon.
6. The method as defined in claim 1 , wherein the silicon layer comprises an epitaxial layer.
7. The method as defined in claim 3 further comprising the step of forming an oxide film upon the top surface of the fill material.
8. A method for manufacturing a sensor device having a circuit portion and a movable sensor portion, the method comprising the steps of:
providing a substrate having an insulation layer on a top surface;
providing a silicon layer on top of the insulation layer;
forming a first trench extending through the silicon layer and reaching the insulation layer so as to isolate a first portion of the silicon layer from a second portion of the silicon layer;
forming a dielectric layer on side walls of the first trench;
disposing a first fill material within the first trench;
forming one or more electrical components on the first portion of the silicon layer;
forming one or more contacts on the second portion of the silicon layer;
forming one or more second trenches in the second portion of the silicon layer so as to provide one or more movable elements within the second portion of the silicon layer, wherein the step of forming the one or more second trenches includes delineation and release of the one or more movable elements, and wherein the one or more movable elements serve as sensing elements; and
forming one or more anti-stiction bumps to prevent a portion of a movable element from sticking to an adjacent feature of the sensor, wherein the step of forming one or more anti-stiction bumps comprises forming the anti-stiction bumps prior to the delineation and release of the movable element;
wherein the step of forming the second trench exposes at least a portion of the anti-stiction bumps.
9. The method as defined in claim 8 further comprising the step of forming an oxide film upon the top surface of the fill material.
10. The method as defined in claim 8 , wherein the sensor comprises an angular rate sensor.
11. The method as defined in claim 8 , wherein the substrate comprises silicon.
12. The method as defined in claim 8 , wherein the silicon layer comprises an epitaxial layer.