CN106847791A - Monitor the test structure of base width - Google Patents

Abstract

The invention discloses a kind of test structure for monitoring base width, comprising a figure for the dumbbell shape for being located at test structure zone line；It is emitter-polysilicon window to include in the middle of emitter-window, emitter-window at the two ends of dumbbell figure, and the center of window is contact hole；It is axially X-direction to define dumbbell figure, is Y-direction perpendicular to X-direction；X-direction length between the emitter-window at the two ends of dumbbell figure is defined as L, and the Y-direction width of dumbbell figure handle region is defined as W；The periphery of dumbbell figure is made up of multilayer rectangle nested step by step, and positioned at outmost turns is base polysilicon layer, and other are inwardly followed successively by emitter polysilicon layer, emitter layer, emitter polysilicon layer, emitter polysilicon layer.The test structure of monitoring base width of the present invention, in chip-scale electrical testing stage effective monitoring SiGe base resistances, the main processes that this test structure can be intuitively to SiGe HBT are monitored, and find in time and solve problem.

Description

Monitor the test structure of base width

Technical field

The present invention relates to field of semiconductor manufacture, the monitoring base width in a kind of HBT devices for SiGe is particularly related to Test structure.

Background technology

For SiGe HBT (HBT：Heterojunction Bipolar Transistor, heterojunction bipolar crystal Pipe) device, outer base area is raised using p-type polysilicon, using the autoregistration device architecture of inside wall between emitter stage and outer base area, As shown in figure 1, base resistance and base-collector capacitance can be reduced simultaneously, such germanium silicium HBT device can be more than The highest concussion frequency fmax of 300GHz, its performance can be widely used in optic communication and millimeter wave should with III-V devices quite With.

It is base stage that SiGe HBT devices use the germanium silicon-carbon alloy mixed with boron impurities of smaller bandwidth, due to emitter stage There is band difference with base stage, can be when same DC current multiplication factor HFE be ensured using base doping higher, so as to obtain To fmax higher.

Connection (Link) resistance under less external base resistance, including side wall, is the most important parameter for lifting fmax, The concentration and thickness of the boron that link resistance adulterates when being by SiGe epitaxial growths determine that concentration higher and thickness can be reduced Link resistance；But HBT is vertical devices, the thickness of interior base is exactly the pinch areas of Fig. 1, and it is highly doped launch site N-type doping (usually arsenic) is diffused into base formation, for cut-off frequency f higher_T, it is desirable to Link areas concentration and width compared with It is low；In order to the compromise of Link and pinch is balanced, emitter stage impurity needs part to be diffused into base.

Because the Impurity Distribution of the Impurity Distribution particularly base of HBT vertical devices has very big shadow to DC and microwave characteristics Ring, typically characterized with SIMS (SIMS) in R＆D process, as shown in Figure 2；But the SIMS method cycles are long, expense Height, monitors if an online test structure, then can accelerate research and development progress, and continue during follow-up volume production Measurement technology stability.

The content of the invention

The technical problems to be solved by the invention are to provide a kind of test structure for monitoring base width, with intuitively right The main processes of SiGe HBT are monitored.

To solve the above problems, the test structure of monitoring base width of the present invention, for monitoring SiGe HBT's The base resistance of technical process, described test structure is X, Y-direction along structure substantially symmetrical about its central axis, is located at comprising one and surveyed Try the figure of the dumbbell shape of structure zone line；Include emitter-window at the two ends of dumbbell figure, in the middle of emitter-window It is emitter-polysilicon window, the center of window is contact hole；It is axially X-direction to define dumbbell figure, is Y perpendicular to X-direction Direction；X-direction length between the emitter-window at the two ends of dumbbell figure is defined as L, and the Y-direction of dumbbell figure handle region is wide Degree is defined as W；

In the periphery of dumbbell figure, it is made up of multilayer rectangle nested step by step, wherein, positioned at outmost turns is many bases Crystal silicon layer, other are inwardly followed successively by emitter polysilicon layer, emitter layer, emitter polysilicon layer, emitter polysilicon layer.

Further, the emitter-window that the dumbbell figure two ends include, width and dumbbell figure hand in its Y-direction The width in handle area is consistent, and is all W.

Further, dumbbell figure two ends width in the X direction keeps one with the width of dumbbell figure handle region Cause, be all W.

Further, the width of the width of the emitter-window that the dumbbell figure two ends include and dumbbell figure handle region It is consistent, can guarantee that electric current is uniform in the direction of the width.

Further, base resistor resistance is monitored, the resistance between the contact hole at dumbbell figure two ends is measured first R_test, then calculated by formula below：

The test structure of monitoring base width of the present invention, there is provided one kind is in germanium silicon autoregistration device architecture and adopts With in the technique of selective epitaxial, in chip-scale electrical testing (WAT) stage effective monitoring base resistor test structures of SiGe；By The resistance that it is measured mainly is determined by germanium and silicon epitaxial technique, while having with the hot expense of polysilicon emitter doping and activating appts Close, the main processes that this test structure can be intuitively to germanium silicium HBT are monitored, are found in the very first time and solve to ask Topic.

Brief description of the drawings

Fig. 1 is the profile of SiGe HBT devices.

Fig. 2 is the curve that SiGe HBT vertical devices are carried out with SIMS (SIMS) analysis.

Fig. 3 is the test structure of present invention monitoring base width.

Fig. 4 is the schematic diagram along Fig. 3 length L direction cuttings.

Fig. 5 is the schematic diagram along Fig. 3 width W direction cuttings.

Description of reference numerals

1 is base polysilicon, and 2,4,5,8 is emitter-polysilicon, and 3,7 is emitter-window, and 6 is dumbbell graph area, and 9 are Contact hole.

Specific embodiment

The test structure of monitoring base width of the present invention, the base electricity of the technical process for monitoring SiGe HBT Resistance, as shown in figure 3, described test structure be X, Y-direction along structure substantially symmetrical about its central axis, be located at test structure comprising one The figure of the dumbbell shape of zone line；Include emitter-window 7 at the two ends of dumbbell figure, be hair in the middle of emitter-window 7 Emitter polysilicon window 8, the center of emitter-polysilicon window 8 is contact hole 9；It is axially X-direction to define dumbbell figure, vertically In X-direction be Y-direction；X-direction length between the emitter-window 7 at the two ends of dumbbell figure is defined as L, dumbbell figure handle The Y-direction width in area is defined as W.

In the periphery of dumbbell figure, it is made up of multilayer rectangle nested step by step, wherein, positioned at outmost turns is many bases Crystal silicon layer 1, other are inwardly followed successively by emitter polysilicon layer 2, emitter layer 3, emitter polysilicon layer 4, emitter-polysilicon Layer 5.

The emitter-window that the dumbbell figure two ends include, the width of width and dumbbell figure handle region in its Y-direction Degree is consistent, and is all W, can guarantee that electric current is uniform in the direction of the width.Dumbbell figure two ends width in the X direction with The width of dumbbell figure handle region is consistent, and is all W.

Base resistor resistance is monitored, the actual resistance R between the contact hole 9 at dumbbell figure two ends is measured first_test, Then calculated by formula below：

Fig. 4 is the section of X-direction wherein one end of the test structure, is drawn with contact hole between 8 and 9；Main technique Flow includes：Active area is grown in N-type extension, active area is isolated by STI；(oxide layer+heavy doping is more for growth transmitting very thin films Crystal silicon+oxide layer+nitration case), photoetching and etching form emitter-window；SiGe selective epitaxial growths；Emitter-polysilicon Growth, photoetching and etching；Base polysilicon photoetching and etching.

Fig. 5 is the section of Y-direction one end of this test structure, wherein the polysilicon emitter between 4 and 5 is to disconnect, This is because while germanium silicon layer is that selective epitaxial is grown up, only there is epitaxial growth in active area, but in shallow trench region, Ke Nengye There is part germanium silicon growth, a groove is opened here and the germanium silicon layer that emitter-polysilicon and germanium and silicon epitaxial dissipate possible growth is carved can together Eating away, so as to ensure that test structure is disconnected with other regions.

The preferred embodiments of the present invention are these are only, is not intended to limit the present invention.Come for those skilled in the art Say, the present invention there can be various modifications and variations.It is all any modifications within the spirit and principles in the present invention, made, equivalent Replace, improve etc., should be included within the scope of the present invention.

Claims (5)

1. it is a kind of monitor base width test structure, the base resistance of the technical process for monitoring SiGe HBT, its feature It is：Described test structure be X, Y-direction along structure substantially symmetrical about its central axis, be located at test structure zone line comprising one Dumbbell shape figure；It is emitter-polysilicon to include in the middle of emitter-window, emitter-window at the two ends of dumbbell figure Window, the center of window is contact hole；It is axially X-direction to define dumbbell figure, is Y-direction perpendicular to X-direction；Dumbbell figure X-direction length between the emitter-window at two ends is defined as L, and the Y-direction width of dumbbell figure handle region is defined as W；

In the periphery of dumbbell figure, it is made up of multilayer rectangle nested step by step, wherein, positioned at outmost turns is base polysilicon Layer, other are inwardly followed successively by emitter polysilicon layer, emitter layer, emitter polysilicon layer, emitter polysilicon layer.

2. the test structure of base width is monitored as claimed in claim 1, it is characterised in that：The dumbbell figure two ends include Emitter-window, the width in its Y-direction is consistent with the width of dumbbell figure handle region, is all W.

3. the test structure of base width is monitored as claimed in claim 1, it is characterised in that：The dumbbell figure two ends are in X Width on direction is consistent with the width of dumbbell figure handle region, is all W.

4. the test structure of base width is monitored as claimed in claim 2, it is characterised in that：The dumbbell figure two ends include The width of emitter-window be consistent with the width of dumbbell figure handle region, can guarantee that electric current is uniform in the direction of the width.

5. the test structure of base width is monitored as claimed in claim 1, it is characterised in that：Base resistor resistance is monitored, Resistance R first between the contact hole at measurement dumbbell figure two ends_test, then calculated by formula below：

$R_{pinch}=R_{test}\×\frac{W}{L}.$