MSP430FR2111: How to achieve lowest power possible?

Hi all,

Below is the simple code. Basically, I am waiting for a button to be pressed. I am still getting 16uA while in deep sleep.

How can I achive sub-micro amp power consumption when in deep sleep mode? Will LPM4_bits work on external interrupt?

Any other ideas to reduce power when MSP430 is not doing anything?

Thank you all.

#include <msp430.h>

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;               // Stop watchdog timer
    P1DIR = 0xFF;
    P1OUT = 0x00;
    P2DIR = 0xFF;
    P2OUT = 0x00;
    // Configure GPIO
    P1OUT &= ~BIT0;                         // Clear P1.0 output latch for a defined power-on state
    P1DIR |= BIT0;                          // Set P1.0 to output direction

    P1OUT |= BIT3;                          // Configure P1.3 as pulled-up
    P1REN |= BIT3;                          // P1.3 pull-up register enable
    P1IES |= BIT3;                          // P1.3 Hi/Low edge
    P1IE |= BIT3;                           // P1.3 interrupt enabled

    // Disable the GPIO power-on default high-impedance mode
    // to activate previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;
    
    P1IFG &= ~BIT3;                         // P1.3 IFG cleared
    
    while(1)
    {
        __bis_SR_register(LPM3_bits | GIE); // Enter LPM3 w/interrupt
        //__delay_cycles(10000);             // Delay for 100000*(1/MCLK)=0.1s
        //P1OUT |= BIT0;                      // P1.0 = toggle
        //__delay_cycles(100000);             // Delay for 100000*(1/MCLK)=0.1s
        //P1OUT &= ~BIT0;

    }
}

#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
    P1IFG &= ~BIT3;                         // Clear P1.3 IFG
    __bic_SR_register_on_exit(LPM3_bits);   // Exit LPM3
}